Science.gov

Sample records for qt syndrome type

  1. QT Dynamics During Exercise in Asymptomatic Children with Long QT Syndrome Type 3.

    PubMed

    Takahashi, Kazuhiro; Nabeshima, Taisuke; Nakayashiro, Mami; Ganaha, Hitoshi

    2016-06-01

    Sympathetic provocative testing is commonly used to detect the abnormal QT dynamics in long QT syndrome (LQTS) patients, particularly LQTS type 1 and type 2. However, little is known about LQTS type 3 (LQT3). We investigated QT dynamics during exercise testing in LQTS patients, particularly LQT3. This study included 37 subjects, comprising 16 genotyped LQTS patients and 21 unrelated healthy subjects without QT prolongation. LQTS patients were divided into LQT3 and non-LQT3 groups. During exercise tests using a modified Bruce protocol, 12-lead electrocardiogram monitoring was performed using a novel multifunctional electrocardiograph. QT intervals were automatically measured. The QT/heart rate (HR) relationship was visualized by plotting the beat-to-beat confluence of the recorded data. A linear regression analysis was performed to determine the QT/HR slope and intercept. Estimated QT intervals at HR 60 bpm (QT60) were calculated by the regression line formula. QT/HR slopes were steeper for each LQTS group than for the control group (P < 0.001). QT60 values demonstrated a moderate correlation with QT intervals at rest (P < 0.0001) for both groups. The corrected QT intervals (QTc) at 4 min of recovery after exercise were significantly longer in the non-LQT3 group than in the control group but were not different between the LQT3 and the control groups. Abnormal QT dynamics during exercise testing were observed in both LQT3 patients and other LQTS subtypes. This method may be useful for directing genetic testing in subjects with borderline prolonged QT intervals.

  2. Marked, transient, emotion-triggered QT accentuation in an adolescent female with type 1 long QT syndrome.

    PubMed

    Anderson, Heather N; Medford, Beth A; Ackerman, Michael J

    2015-02-01

    Type 1 long QT syndrome is the most common long QT syndrome genetic subtype. Exercise and emotional stress can precipitate sudden cardiac events in patients with type 1 long QT syndrome; however, the precise mechanism remains elusive. We report the case of a teenage girl with type 1 long QT syndrome secondary to a rare frameshift mutation (p. L191fs+90X) in the KCNQ1-encoded Kv7.1 potassium channel. During emotional distress, her continuous QTc recordings precipitously increased, peaking within minutes to 669 ms and then returning to baseline (520 ms) as she calmed without concomitant increase in heart rate. This is the first described case documenting transient, marked accentuation of the QTc interval in a long QT syndrome patient during emotional distress. Such events may be triggered by transient accentuation of the intrinsic perturbation in cardiac repolarisation and increase the risk of degeneration to a ventricular arrhythmia. This case illustrates the need improved understanding of the complex interaction between emotion and cardiac stability in patients with long QT syndrome.

  3. Time, frequency and information domain analysis of heart period and QT variability in asymptomatic long QT syndrome type 2 patients.

    PubMed

    Bari, Vlasta; Girardengo, Giulia; Marchi, Andrea; De Maria, Beatrice; Brink, Paul A; Crotti, Lia; Schwartz, Peter J; Porta, Alberto

    2015-01-01

    This study was designed to characterize in time, frequency and information domains heart period (HP) and QT interval variabilities in asymptomatic (ASYMP) long QT syndrome type 2 (LQT2) subjects. HP, approximated as the temporal distance between two consecutive R-wave peaks, and QT, approximated as the temporal distance between the R-wave peak and the T-wave offset, were automatically derived from 24h Holter recordings in 10 ASYMP LQT2 patients and 13 healthy non mutation carriers (NMC) subjects. All analyses were carried out during DAY (from 2 to 6 PM) and NIGHT (from 12 to 4 AM). Mean, variance, spectral power and complexity indices at short, medium and long time scales were assessed over HP and QT beat-to-beat series. Circadian rhythmicity was evident in both NMC and ASYMP LQT2 but ASYMP LQT2 subjects were characterized by higher HP, QT interval and HP variability during both DAY and NIGHT. In addition, multiscale complexity analysis was able to differentiate the groups by showing a higher HP complexity and a lower QT complexity at long time scales in ASYMP LQT2 during DAY. ASYMP LQT2 exhibited a different autonomic control compared to NMC and such a differentiation could be protective and assure them a lower risk profile.

  4. Mechanisms of disease pathogenesis in long QT syndrome type 5

    PubMed Central

    Harmer, Stephen C.; Wilson, Andrew J.; Aldridge, Robert

    2010-01-01

    KCNE1 associates with the pore-forming α-subunit KCNQ1 to generate the slow (IKs) current in cardiac myocytes. Mutations in either KCNQ1 or KCNE1 can alter the biophysical properties of IKs and mutations in KCNE1 underlie cases of long QT syndrome type 5 (LQT5). We previously investigated a mutation in KCNE1, T58P/L59P, which causes severe attenuation of IKs. However, how T58P/L59P acts to disrupt IKs has not been determined. In this study, we investigate and compare the effects of T58P/L59P with three other LQT5 mutations (G52R, S74L, and R98W) on the biophysical properties of the current, trafficking of KCNQ1, and assembly of the IKs channel. G52R and T58P/L59P produce currents that lack the kinetic behavior of IKs. In contrast, S74L and R98W both produce IKs-like currents but with rightward shifted voltage dependence of activation. All of the LQT5 mutants express protein robustly, and T58P/L59P and R98W cause modest, but significant, defects in the trafficking of KCNQ1. Despite defects in trafficking, in the presence of KCNQ1, T58P/L59P and the other LQT5 mutants are present at the plasma membrane. Interestingly, in comparison to KCNE1 and the other LQT5 mutants, T58P/L59P associates only weakly with KCNQ1. In conclusion, we identify the disease mechanisms for each mutation and reveal that T58P/L59P causes disease through a novel mechanism that involves defective IKs complex assembly. PMID:19907016

  5. Mechanisms of disease pathogenesis in long QT syndrome type 5.

    PubMed

    Harmer, Stephen C; Wilson, Andrew J; Aldridge, Robert; Tinker, Andrew

    2010-02-01

    KCNE1 associates with the pore-forming alpha-subunit KCNQ1 to generate the slow (I(Ks)) current in cardiac myocytes. Mutations in either KCNQ1 or KCNE1 can alter the biophysical properties of I(Ks) and mutations in KCNE1 underlie cases of long QT syndrome type 5 (LQT5). We previously investigated a mutation in KCNE1, T58P/L59P, which causes severe attenuation of I(Ks). However, how T58P/L59P acts to disrupt I(Ks) has not been determined. In this study, we investigate and compare the effects of T58P/L59P with three other LQT5 mutations (G52R, S74L, and R98W) on the biophysical properties of the current, trafficking of KCNQ1, and assembly of the I(Ks) channel. G52R and T58P/L59P produce currents that lack the kinetic behavior of I(Ks). In contrast, S74L and R98W both produce I(Ks)-like currents but with rightward shifted voltage dependence of activation. All of the LQT5 mutants express protein robustly, and T58P/L59P and R98W cause modest, but significant, defects in the trafficking of KCNQ1. Despite defects in trafficking, in the presence of KCNQ1, T58P/L59P and the other LQT5 mutants are present at the plasma membrane. Interestingly, in comparison to KCNE1 and the other LQT5 mutants, T58P/L59P associates only weakly with KCNQ1. In conclusion, we identify the disease mechanisms for each mutation and reveal that T58P/L59P causes disease through a novel mechanism that involves defective I(Ks) complex assembly.

  6. Short QT syndrome.

    PubMed

    Schimpf, Rainer; Wolpert, Christian; Gaita, Fiorenzo; Giustetto, Carla; Borggrefe, Martin

    2005-08-15

    The short QT syndrome constitutes a new clinical entity that is associated with a high incidence of sudden cardiac death, syncope, and/or atrial fibrillation even in young patients and newborns. Patients with this congenital electrical abnormality are characterized by rate-corrected QT intervals<320 ms. Missense mutations in KCNH2 (HERG) linked to a gain-of-function of the rapidly activating delayed-rectifier current I(Kr) have been identified in the first two reported families with familial sudden cardiac death. Recently, two further gain-of-function mutations in the KCNQ1 gene encoding the alpha-subunit of the KvLQT1 (I(Ks)) channel and in the KCNJ2 gene encoding the strong inwardly rectifying channel protein Kir2.1 confirmed a genetically heterogeneous disease. The possible substrate for the development of ventricular tachyarrhythmias may be a significant transmural dispersion of the repolarisation due to a heterogeneous abbreviation of the action potential duration. The implantable cardioverter defibrillator is the therapy of choice in patients with syncope and a positive family history of sudden cardiac death. However, ICD therapy in patients with a short QT syndrome has an increased risk for inappropriate shock therapies due to possible T wave oversensing. The impact of sotalol, ibutilide, flecainide, and quinidine on QT prolongation has been evaluated, but only quinidine effectively suppressed gain-of-function in I(Kr) with prolongation of the QT interval. In patients with a mutation in HERG, it rendered ventricular tachycardias/ventricular fibrillation non-inducible and restored the QT interval/heart rate relationship towards a normal range. It may serve as an adjunct to ICD therapy or as a possible alternative treatment, especially for children and newborns.

  7. Spontaneous initiation of premature ventricular complexes and arrhythmias in type 2 long QT syndrome.

    PubMed

    Huang, Xiaodong; Kim, Tae Yun; Koren, Gideon; Choi, Bum-Rak; Qu, Zhilin

    2016-12-01

    The occurrence of early afterdepolarizations (EADs) and increased dispersion of repolarization are two known factors for arrhythmogenesis in long QT syndrome. However, increased dispersion of repolarization tends to suppress EADs due to the source-sink effect, and thus how the two competing factors cause initiation of arrhythmias remains incompletely understood. Here we used optical mapping and computer simulation to investigate the mechanisms underlying spontaneous initiation of arrhythmias in type 2 long QT (LQT2) syndrome. In optical mapping experiments of transgenic LQT2 rabbit hearts under isoproterenol, premature ventricular complexes (PVCs) were observed to originate from the steep spatial repolarization gradient (RG) regions and propagated unidirectionally. The same PVC behaviors were demonstrated in computer simulations of tissue models of rabbits. Depending on the heterogeneities, these PVCs could lead to either repetitive focal excitations or reentry without requiring an additional vulnerable substrate. Systematic simulations showed that cellular phase 2 EADs were either suppressed or confined to the long action potential region due to the source-sink effect. Tissue-scale phase 3 EADs and PVCs occurred due to tissue-scale dynamical instabilities caused by RG and enhanced L-type calcium current (ICa,L), occurring under both large and small RG. Presence of cellular EADs was not required but potentiated PVCs when RG was small. We also investigated how other factors affect the dynamical instabilities causing PVCs. Our main conclusion is that tissue-scale dynamical instabilities caused by RG and enhanced ICa,L give rise to both the trigger and the vulnerable substrate simultaneously for spontaneous initiation of arrhythmias in LQT2 syndrome.

  8. Light phase-restricted feeding slows basal heart rate to exaggerate the type-3 long QT syndrome phenotype in mice.

    PubMed

    Schroder, Elizabeth A; Burgess, Don E; Manning, Cody L; Zhao, Yihua; Moss, Arthur J; Patwardhan, Abhijit; Elayi, Claude S; Esser, Karyn A; Delisle, Brian P

    2014-12-15

    Long QT syndrome type 3 (LQT3) is caused by mutations in the SCN5A-encoded Nav1.5 channel. LQT3 patients exhibit time of day-associated abnormal increases in their heart rate-corrected QT (QTc) intervals and risk for life-threatening episodes. This study determines the effects of uncoupling environmental time cues that entrain circadian rhythms (time of light and time of feeding) on heart rate and ventricular repolarization in wild-type (WT) or transgenic LQT3 mice (Scn5a(+/ΔKPQ)). We used an established light phase-restricted feeding paradigm that disrupts the alignment among the circadian rhythms in the central pacemaker of the suprachiasmatic nucleus and peripheral tissues including heart. Circadian analysis of the RR and QT intervals showed the Scn5a(+/ΔKPQ) mice had QT rhythms with larger amplitudes and 24-h midline means and a more pronounced slowing of the heart rate. For both WT and Scn5a(+/ΔKPQ) mice, light phase-restricted feeding shifted the RR and QT rhythms ~12 h, increased their amplitudes greater than twofold, and raised the 24-h midline mean by ~10%. In contrast to WT mice, the QTc interval in Scn5a(+/ΔKPQ) mice exhibited time-of-day prolongation that was flipped after light phase-restricted feeding. The time-of-day changes in the QTc intervals of Scn5a(+/ΔKPQ) mice were secondary to a steeper power relation between their QT and RR intervals. We conclude that uncoupling time of feeding from normal light cues can dramatically slow heart rate to unmask genotype-specific differences in the QT intervals and aggravate the LQT3-related phenotype.

  9. Purkinje Cells as Sources of Arrhythmias in Long QT Syndrome Type 3.

    PubMed

    Iyer, Vivek; Roman-Campos, Danilo; Sampson, Kevin J; Kang, Guoxin; Fishman, Glenn I; Kass, Robert S

    2015-08-20

    Long QT syndrome (LQTS) is characterized by ventricular arrhythmias and sudden cardiac death. Purkinje cells (PC) within the specialized cardiac conduction system have unique electrophysiological properties that we hypothesize may produce the primary sources of arrhythmia in heritable LQTS. LQTS type 3 (LQT3) transgenic mice harboring the ΔKPQ(+/-) mutation were crossed with Contactin2-EGFP BAC transgenic mice, which express a fluorescent reporter gene within the Purkinje fiber network. Isolated ventricular myocytes (VMs) (EGFP(-)) and PCs (EGFP(+)) from wild type and ΔKPQ mutant hearts were compared using the whole-cell patch clamp technique and microfluorimetry of calcium transients. Increased late sodium current was seen in ΔKPQ-PCs and ΔKPQ-VMs, with larger density in ΔKPQ-PCs. Marked prolongation of action potential duration of ΔKPQ-PCs was seen compared to ΔKPQ-VMs. ΔKPQ-PCs, but not ΔKPQ-VMs, exhibited frequent early afterdepolarizations, which corresponded to repetitive oscillations of intracellular calcium. Abnormalities in cell repolarization were reversed with exposure to mexiletine. We present the first direct experimental evidence that PCs are uniquely sensitive to LQT3 mutations, displaying electrophysiological behavior that is highly pro-arrhythmic.

  10. β-blockers protect against dispersion of repolarization during exercise in congenital long-QT syndrome type 1.

    PubMed

    Gemma, Lee W; Ward, Gregory M; Dettmer, Mary M; Ball, Jennifer L; Leo, Peter J; Doria, Danielle N; Kaufman, Elizabeth S

    2011-10-01

    β-Blocker therapy reduces syncope and sudden death in long-QT syndrome type 1 (LQT1), but the mechanism of protection is incompletely understood. This study tested the hypothesis that β-blockade reduces QT prolongation and dispersion of repolarization, measured as the T peak-to-end interval (T(pe) ), during exercise and recovery in LQT1 patients. QT and T(pe) were measured in 10 LQT1 patients (33 ± 13 years) and 35 normal subjects (32 ± 12 years) during exercise tests on and off β-blockade. In LQT1 patients, β-blockade reduced QT (391 ± 25 milliseconds vs 375 ± 26 milliseconds, P = 0.04 during exercise; 419 ± 41 milliseconds vs 391 ± 39 milliseconds, P = 0.02 during recovery) and markedly reduced T(pe) (91 ± 26 milliseconds vs 67 ± 19 milliseconds, P = 0.03 during exercise; 103 ± 26 milliseconds vs 78 ± 11 milliseconds, P = 0.02 during recovery). In contrast, in normal subjects, β-blockade had no effect on QT (320 ± 17 milliseconds vs 317 ± 16 milliseconds, P = 0.29 during exercise; 317 ± 13 milliseconds vs 315 ± 14 milliseconds, P = 0.15 during recovery) and mildly reduced T(pe) (69 ± 13 milliseconds vs 61 ± 11 milliseconds, P = 0.01 during exercise; 77 ± 19 milliseconds vs. 68 ± 14 milliseconds, P < 0.001 during recovery). In LQT1 patients, β-blockers reduced QT and T(pe) during exercise and recovery, supporting the theory that β-blocker therapy protects LQT1 patients by reducing dispersion of repolarization during exercise and recovery. © 2011 Wiley Periodicals, Inc.

  11. Genetics of long QT syndrome.

    PubMed

    Tester, David J; Ackerman, Michael J

    2014-01-01

    Long QT syndrome (LQTS) is a potentially life-threatening cardiac arrhythmia characterized by delayed myocardial repolarization that produces QT prolongation and increased risk for torsades des pointes (TdP)-triggered syncope, seizures, and sudden cardiac death (SCD) in an otherwise healthy young individual with a structurally normal heart. Currently, there are three major LQTS genes (KCNQ1, KCNH2, and SCN5A) that account for approximately 75% of the disorder. For the major LQTS genotypes, genotype-phenotype correlations have yielded gene-specific arrhythmogenic triggers, electrocardiogram (ECG) patterns, response to therapies, and intragenic and increasingly mutation-specific risk stratification. The 10 minor LQTS-susceptibility genes collectively account for less than 5% of LQTS cases. In addition, three atypical LQTS or multisystem syndromic disorders that have been associated with QT prolongation have been described, including ankyrin-B syndrome, Anderson-Tawil syndrome (ATS), and Timothy syndrome (TS). Genetic testing for LQTS is recommended in patients with either a strong clinical index of suspicion or persistent QT prolongation despite their asymptomatic state. However, genetic test results must be interpreted carefully.

  12. "QT clock" to improve detection of QT prolongation in long QT syndrome patients.

    PubMed

    Page, Alex; Aktas, Mehmet K; Soyata, Tolga; Zareba, Wojciech; Couderc, Jean-Philippe

    2016-01-01

    The QT interval is a risk marker for cardiac events such as torsades de pointes. However, QT measurements obtained from a 12-lead ECG during clinic hours may not capture the full extent of a patient's daily QT range. The purpose of this study was to evaluate the utility of 24-hour Holter ECG recording in patients with long QT syndrome (LQTS) to identify dynamic changes in the heart rate-corrected QT interval and to investigate methods of visualizing the resulting datasets. Beat-to-beat QTc (Bazett) intervals were automatically measured across 24-hour Holter recordings from 202 LQTS type 1, 89 type 2, and 14 type 3 genotyped patients and a reference group of 200 healthy individuals. We measured the percentage of beats with QTc greater than the gender-specific threshold (QTc ≥470 ms in women and QTc ≥450 ms in men). The percentage of beats with QTc prolongation was determined across the 24-hour recordings. Based on the median percentage of heartbeats per patient with QTc prolongation, LQTS type 1 patients showed more frequent QTc prolongation during the day (~3 PM) than they did at night (~3 AM): 97% vs 48%, P ~10(-4) for men, and 68% vs 30%, P ~10(-5) for women. LQTS type 2 patients showed less frequent QTc prolongation during the day compared to nighttime: 87% vs 100%, P ~10(-4) for men, and 62% vs 100%, P ~10(-3) for women. In patients with genotype-positive LQTS, significant differences exist in the degree of daytime and nocturnal QTc prolongation. Holter monitoring using the "QT clock" concept may provide an easy, fast, and accurate method for assessing the true personalized burden of QTc prolongation. Copyright © 2016 Heart Rhythm Society. Published by Elsevier Inc. All rights reserved.

  13. Long QT syndrome with craniofacial, digital, and neurologic features: Is it useful to distinguish between Timothy syndrome types 1 and 2?

    PubMed

    Diep, Vinson; Seaver, Laurie H

    2015-11-01

    Timothy syndrome (TS) is a rare genetic condition that associates long QT syndrome, structural heart defects, dysmorphic facial features, syndactyly, seizures, developmental delay, and autism. Timothy syndrome type 1 is caused by a recurrent de novo mutation (p.Gly406Arg) in exon 8A of the L-type calcium channel gene CACNA1C. Timothy syndrome type 2 was originally reported to be associated with a more severe cardiac phenotype but without syndactyly. Timothy syndrome type 2 is caused by mutation in an alternatively spliced exon 8 of the CACNA1C gene. Other mutations in CACNA1C are also reported with long QT syndrome with and without syndromic features overlapping that described in Timothy syndrome. The purpose of this report is to describe the presentation, physical features and natural history of a 4-year-old girl with Timothy syndrome type 2 due to the recurrent p.Gly406Arg mutation in exon 8 of CACNA1C. She has similar facial features to Timothy syndrome type 1 without syndactyly. She is developmentally delayed without autism. She recently had her first episode of torsade de pointes associated with febrile illness and hypoglycemia. The findings in this case provide further information about the phenotype and natural history of CACNA1C exon 8 mutation and together with previously reported cases of Timothy syndrome question whether the clinical and molecular distinction between Timothy syndromes types 1 and 2 remains clinically useful.

  14. Multiscale Complexity Analysis of the Cardiac Control Identifies Asymptomatic and Symptomatic Patients in Long QT Syndrome Type 1

    PubMed Central

    Bari, Vlasta; Valencia, José F.; Vallverdú, Montserrat; Girardengo, Giulia; Marchi, Andrea; Bassani, Tito; Caminal, Pere; Cerutti, Sergio; George, Alfred L.; Brink, Paul A.; Crotti, Lia; Schwartz, Peter J.; Porta, Alberto

    2014-01-01

    The study assesses complexity of the cardiac control directed to the sinus node and to ventricles in long QT syndrome type 1 (LQT1) patients with KCNQ1-A341V mutation. Complexity was assessed via refined multiscale entropy (RMSE) computed over the beat-to-beat variability series of heart period (HP) and QT interval. HP and QT interval were approximated respectively as the temporal distance between two consecutive R-wave peaks and between the R-wave apex and T-wave end. Both measures were automatically taken from 24-hour electrocardiographic Holter traces recorded during daily activities in non mutation carriers (NMCs, n = 14) and mutation carriers (MCs, n = 34) belonging to a South African LQT1 founder population. The MC group was divided into asymptomatic (ASYMP, n = 11) and symptomatic (SYMP, n = 23) patients according to the symptom severity. Analyses were carried out during daytime (DAY, from 2PM to 6PM) and nighttime (NIGHT, from 12PM to 4AM) off and on beta-adrenergic blockade (BBoff and BBon). We found that the complexity of the HP variability at short time scale was under vagal control, being significantly increased during NIGHT and BBon both in ASYMP and SYMP groups, while the complexity of both HP and QT variability at long time scales was under sympathetic control, being smaller during NIGHT and BBon in SYMP subjects. Complexity indexes at long time scales in ASYMP individuals were smaller than those in SYMP ones regardless of therapy (i.e. BBoff or BBon), thus suggesting that a reduced complexity of the sympathetic regulation is protective in ASYMP individuals. RMSE analysis of HP and QT interval variability derived from routine 24-hour electrocardiographic Holter recordings might provide additional insights into the physiology of the cardiac control and might be fruitfully exploited to improve risk stratification in LQT1 population. PMID:24705789

  15. A Neonate with Susceptibility to Long QT Syndrome Type 6 who Presented with Ventricular Fibrillation and Sudden Unexpected Infant Death

    PubMed Central

    Sauer, Charles W.; Marc-Aurele, Krishelle L.

    2016-01-01

    Patient: Female, 19-day Final Diagnosis: 19 day old neonate with susceptibility to Long QT syndrome • ventricular fibrillation Symptoms: Cardiac arrest • cardiac arrhythmia • encephalopathy Medication: — Clinical Procedure: Cardioversion Specialty: Pediatrics and Neonatology Objective: Rare disease Background: This is a case of a neonate with susceptibility to long QT syndrome (LQTS) who presented with a sudden unexpected infant death. Experts continue to debate whether universal electrocardiogram (ECG) screening of all newborns is feasible, practical, and cost-effective. Case Report: A 19-day-old neonate was found unresponsive by her mother. ECG showed ventricular fibrillation and a combination of a lidocaine drip plus multiple defibrillations converted the rhythm to normal sinus. Unfortunately, MRI brain imaging showed multiple infarcts and EEG showed burst suppression pattern with frequent seizures; life supportive treatment was stopped and the infant died. Genetic testing revealed two mutations in the KCNE2 gene consistent with susceptibility to LQTS type 6. Conclusions: We believe this case is the first to demonstrate both a precipitating electrocardiographic and genetic cause of death for an infant with LQTS, showing a cause-and-effect relationship between LQTS mutation, ventricular arrhythmia, and death. We wonder whether universal ECG newborn screening to prevent LQTS death could have saved this baby. PMID:27465075

  16. Human iPS cell model of type 3 long QT syndrome recapitulates drug-based phenotype correction.

    PubMed

    Malan, Daniela; Zhang, Miao; Stallmeyer, Birgit; Müller, Jovanca; Fleischmann, Bernd K; Schulze-Bahr, Eric; Sasse, Philipp; Greber, Boris

    2016-03-01

    Long QT syndrome is a potentially life-threatening disease characterized by delayed repolarization of cardiomyocytes, QT interval prolongation in the electrocardiogram, and a high risk for sudden cardiac death caused by ventricular arrhythmia. The genetic type 3 of this syndrome (LQT3) is caused by gain-of-function mutations in the SCN5A cardiac sodium channel gene which mediates the fast Nav1.5 current during action potential initiation. Here, we report the analysis of LQT3 human induced pluripotent stem cell-derived cardiomyocytes (hiPSC-CMs). These were generated from a patient with a heterozygous p.R1644H mutation in SCN5A known to interfere with fast channel inactivation. LQT3 hiPSC-CMs recapitulated pathognomonic electrophysiological features of the disease, such as an accelerated recovery from inactivation of sodium currents as well as action potential prolongation, especially at low stimulation rates. In addition, unlike previously described LQT3 hiPSC models, we observed a high incidence of early after depolarizations (EADs) which is a trigger mechanism for arrhythmia in LQT3. Administration of specific sodium channel inhibitors was found to shorten action and field potential durations specifically in LQT3 hiPSC-CMs and antagonized EADs in a dose-dependent manner. These findings were in full agreement with the pharmacological response profile of the underlying patient and of other patients from the same family. Thus, our data demonstrate the utility of patient-specific LQT3 hiPSCs for assessing pharmacological responses to putative drugs and for improving treatment efficacies.

  17. Genetics Home Reference: short QT syndrome

    MedlinePlus

    ... instructions for making channels that transport positively charged atoms (ions) of potassium out of cells. In cardiac ... the disorder. Some affected individuals have a family history of short QT syndrome or related heart problems ...

  18. Assessment for congenital long QT syndrome.

    PubMed

    Heidenreich, Wayne F

    2003-01-01

    A 29-year-old male presented for an evaluation of his risk for having congenital long QT syndrome. Despite being asymptomatic and having a normal QTc interval on the resting ECG, a suggestive family history was an indication for a thorough cardiac evaluation. A geneticist reviewed this workup and recommended against genetic testing. While up to 10% of affected carriers of a congenital long QT syndrome gene mutation can be asymptomatic with a normal QTc, consideration of all of the clinical factors allowed for further risk stratification. The evaluation of an ECG for the long QT syndrome includes calculating a corrected QT interval for the heart rate and assessing the T-waves for morphology associated with this syndrome.

  19. Sports participation in long QT syndrome.

    PubMed

    Aziz, Peter F; Saarel, Elizabeth V

    2017-01-01

    Untreated congenital long QT syndrome may result in potentially lethal ventricular tachycardia. In the most common type, risk of such an event has been linked to exercise. This originally resulted in very restrictive guidelines for sports participation in affected individuals. Although the complex interactions of a specific genotype, modifying cofactors, and risk are only now being explored, scientific evidence based on clinical experience now suggests that in many instances such restrictive guidelines are unwarranted. In particular, patients with this condition who are compliant with β-blocker therapy and who have never had symptoms during exertion are now enjoying the benefits of athletic activity.

  20. Foetal presentation of long QT syndrome.

    PubMed

    Theeuws, Chloe; Nuyens, Dieter; Gewillig, Marc

    2013-06-01

    Long-QT syndrome is a rare, inherited cardiac channelopathy that is characterized by arrhythmia, syncope and sudden cardiac death. Foetal symptoms are very rare and prenatal diagnosis is difficult. We report on a foetal presentation of long-QT syndrome with severe hydrops and a chaotic heart rhythm at 32 weeks of gestation. Postnatal electrocardiography showed runs of polymorphic ventricular tachycardia and an extremely prolonged-QT segment (QTc of 640 ms). The initial approach of overdrive pacing, followed by the combined therapy of a beta blocker, a sodium channel blocker (mexiletine) and potassium suppletion proved successful in maintaining a stable sinus rhythm. The girl was doing well at eight months of followup. In this patient a timely diagnosis and effective management after birth have been life-saving.The intrauterine manifestation of foetal atrioventricular dissociation and ventricular arrhythmia should raise suspicion of congenital long-QT syndrome.

  1. Origin of complex behaviour of spatially discordant alternans in a transgenic rabbit model of type 2 long QT syndrome.

    PubMed

    Ziv, Ohad; Morales, Eduardo; Song, Yoon-kyu; Peng, Xuwen; Odening, Katja E; Buxton, Alfred E; Karma, Alain; Koren, Gideon; Choi, Bum-Rak

    2009-10-01

    Enhanced dispersion of repolarization has been proposed as an important mechanism in long QT related arrhythmias. Dispersion can be dynamic and can be augmented with the occurrence of spatially out-of-phase action potential duration (APD) alternans (discordant alternans; DA). We investigated the role of tissue heterogeneity in generating DA using a novel transgenic rabbit model of type 2 long QT syndrome (LQT2). Littermate control (LMC) and LQT2 rabbit hearts (n = 5 for each) were retrogradely perfused and action potentials were mapped from the epicardial surface using di-4-ANEPPS and a high speed CMOS camera. Spatial dispersion (Delta APD and Delta slope of APD restitution) were both increased in LQT2 compared to LMC (Delta APD: 34 +/- 7 ms vs. 23 +/- 6 ms; Delta slope: 1.14 +/- 0.23 vs. 0.59 +/- 0.19). Onset of DA under a ramp stimulation protocol was seen at longer pacing cycle length (CL) in LQT2 compared to LMC hearts (206 +/- 24 ms vs. 156 +/- 5 ms). Nodal lines between regions with APD alternans out of phase from each other were correlated with conduction velocity (CV) alternation in LMC but not in LQT2 hearts. In LQT2 hearts, larger APD dispersion was associated with onset of DA at longer pacing CL. At shorter CLs, closer to ventricular fibrillation induction (VF), nodal lines in LQT2 (n = 2 out of 5) showed persistent complex beat-to-beat changes in nodal line formation of DA associated with competing contribution from CV restitution and tissue spatial heterogeneity, increasing vulnerability to conduction block. In conclusion, tissue heterogeneity plays a significant role in providing substrate for ventricular arrhythmia in LQT2 rabbits by facilitating DA onset and contributing to unstable nodal lines prone to reentry formation.

  2. Large-scale mutational analysis of Kv11.1 reveals molecular insights into type 2 long QT syndrome

    NASA Astrophysics Data System (ADS)

    Anderson, Corey L.; Kuzmicki, Catherine E.; Childs, Ryan R.; Hintz, Caleb J.; Delisle, Brian P.; January, Craig T.

    2014-11-01

    It has been suggested that deficient protein trafficking to the cell membrane is the dominant mechanism associated with type 2 Long QT syndrome (LQT2) caused by Kv11.1 potassium channel missense mutations, and that for many mutations the trafficking defect can be corrected pharmacologically. However, this inference was based on expression of a small number of Kv11.1 mutations. We performed a comprehensive analysis of 167 LQT2-linked missense mutations in four Kv11.1 structural domains and found that deficient protein trafficking is the dominant mechanism for all domains except for the distal carboxy-terminus. Also, most pore mutations—in contrast to intracellular domain mutations—were found to have severe dominant-negative effects when co-expressed with wild-type subunits. Finally, pharmacological correction of the trafficking defect in homomeric mutant channels was possible for mutations within all structural domains. However, pharmacological correction is dramatically improved for pore mutants when co-expressed with wild-type subunits to form heteromeric channels.

  3. Molecular Pathophysiology of Congenital Long QT Syndrome.

    PubMed

    Bohnen, M S; Peng, G; Robey, S H; Terrenoire, C; Iyer, V; Sampson, K J; Kass, R S

    2017-01-01

    Ion channels represent the molecular entities that give rise to the cardiac action potential, the fundamental cellular electrical event in the heart. The concerted function of these channels leads to normal cyclical excitation and resultant contraction of cardiac muscle. Research into cardiac ion channel regulation and mutations that underlie disease pathogenesis has greatly enhanced our knowledge of the causes and clinical management of cardiac arrhythmia. Here we review the molecular determinants, pathogenesis, and pharmacology of congenital Long QT Syndrome. We examine mechanisms of dysfunction associated with three critical cardiac currents that comprise the majority of congenital Long QT Syndrome cases: 1) IKs, the slow delayed rectifier current; 2) IKr, the rapid delayed rectifier current; and 3) INa, the voltage-dependent sodium current. Less common subtypes of congenital Long QT Syndrome affect other cardiac ionic currents that contribute to the dynamic nature of cardiac electrophysiology. Through the study of mutations that cause congenital Long QT Syndrome, the scientific community has advanced understanding of ion channel structure-function relationships, physiology, and pharmacological response to clinically employed and experimental pharmacological agents. Our understanding of congenital Long QT Syndrome continues to evolve rapidly and with great benefits: genotype-driven clinical management of the disease has improved patient care as precision medicine becomes even more a reality.

  4. A Neonate with Susceptibility to Long QT Syndrome Type 6 who Presented with Ventricular Fibrillation and Sudden Unexpected Infant Death.

    PubMed

    Sauer, Charles W; Marc-Aurele, Krishelle L

    2016-07-28

    BACKGROUND This is a case of a neonate with susceptibility to long QT syndrome (LQTS) who presented with a sudden unexpected infant death. Experts continue to debate whether universal electrocardiogram (ECG) screening of all newborns is feasible, practical, and cost-effective. CASE REPORT A 19-day-old neonate was found unresponsive by her mother. ECG showed ventricular fibrillation and a combination of a lidocaine drip plus multiple defibrillations converted the rhythm to normal sinus. Unfortunately, MRI brain imaging showed multiple infarcts and EEG showed burst suppression pattern with frequent seizures; life supportive treatment was stopped and the infant died. Genetic testing revealed two mutations in the KCNE2 gene consistent with susceptibility to LQTS type 6. CONCLUSIONS We believe this case is the first to demonstrate both a precipitating electrocardiographic and genetic cause of death for an infant with LQTS, showing a cause-and-effect relationship between LQTS mutation, ventricular arrhythmia, and death. We wonder whether universal ECG newborn screening to prevent LQTS death could have saved this baby.

  5. Effect of Age and Sex on the QTc Interval in Children and Adolescents With Type 1 and 2 Long-QT Syndrome.

    PubMed

    Vink, Arja S; Clur, Sally-Ann B; Geskus, Ronald B; Blank, Andreas C; De Kezel, Charlotte C A; Yoshinaga, Masao; Hofman, Nynke; Wilde, Arthur A M; Blom, Nico A

    2017-04-01

    In congenital long-QT syndrome, age, sex, and genotype have been associated with cardiac events, but their effect on the trend in QTc interval has never been established. We, therefore, aimed to assess the effect of age and sex on the QTc interval in children and adolescents with type 1 (LQT1) and type 2 (LQT2) long-QT syndrome. QTc intervals of 12-lead resting electrocardiograms were determined, and trends over time were analyzed using a linear mixed-effects model. The study included 278 patients with a median follow-up of 4 years (interquartile range, 1-9) and a median number of 6 (interquartile range, 2-10) electrocardiograms per patient. Both LQT1 and LQT2 male patients showed QTc interval shortening after the onset of puberty. In LQT2 male patients, this was preceded by a progressive QTc interval prolongation. In LQT1, after the age of 12 years, male patients had a significantly shorter QTc interval than female patients. In LQT2, during the first years of life and from 14 to 26 years, male patients had a significantly shorter QTc interval than female patients. On the contrary, between 5 and 14 years, LQT2 male patients had significantly longer QTc interval than LQT2 female patients. There is a significant effect of age and sex on the QTc interval in long-QT syndrome, with a unique pattern per genotype. The age of 12 to 14 years is an important transitional period. In the risk stratification and management of long-QT syndrome patients, clinicians should be aware of these age-, sex-, and genotype-related trends in QTc interval and especially the important role of the onset of puberty. © 2017 American Heart Association, Inc.

  6. QT Adaptation and Intrinsic QT Variability in Congenital Long QT Syndrome.

    PubMed

    Seethala, Srikanth; Singh, Prabhpreet; Shusterman, Vladimir; Ribe, Margareth; Haugaa, Kristina H; Němec, Jan

    2015-12-16

    Increased variability of QT interval (QTV) has been linked to arrhythmias in animal experiments and multiple clinical situations. Congenital long QT syndrome (LQTS), a pure repolarization disease, may provide important information on the relationship between delayed repolarization and QTV. Twenty-four-hour Holter monitor tracings from 78 genotyped congenital LQTS patients (52 females; 51 LQT1, 23 LQT2, 2 LQT5, 2 JLN, 27 symptomatic; age, 35.2±12.3 years) were evaluated with computer-assisted annotation of RR and QT intervals. Several models of RR-QT relationship were tested in all patients. A model assuming exponential decrease of past RR interval contributions to QT duration with 60-second time constant provided the best data fit. This model was used to calculate QTc and residual "intrinsic" QTV, which cannot be explained by heart rate change. The intrinsic QTV was higher in patients with long QTc (r=0.68; P<10(-4)), and in LQT2 than in LQT1/5 patients (5.65±1.28 vs 4.46±0.82; P<0.0002). Both QTc and intrinsic QTV were similar in symptomatic and asymptomatic patients (467±52 vs 459±53 ms and 5.10±1.19 vs 4.74±1.09, respectively). In LQTS patients, QT interval adaptation to heart rate changes occurs with time constant ≈60 seconds, similar to results reported in control subjects. Intrinsic QTV correlates with the degree of repolarization delay and might reflect action potential instability observed in animal models of LQTS. © 2015 The Authors. Published on behalf of the American Heart Association, Inc., by Wiley Blackwell.

  7. Individualized corrected QT interval is superior to QT interval corrected using the Bazett formula in predicting mutation carriage in families with long QT syndrome.

    PubMed

    Robyns, Tomas; Willems, Rik; Vandenberk, Bert; Ector, Joris; Garweg, Christophe; Kuiperi, Cuno; Breckpot, Jeroen; Corveleyn, Anniek; Janssens, Stefan; Heidbuchel, Hein; Nuyens, Dieter

    2017-03-01

    Long QT syndrome (LQTS) is characterized by reduced penetrance and variable QT prolongation over time, resulting in an estimate of 25% carriers of a pathogenic mutation with a normal corrected QT (QTc) interval on the resting electrocardiogram (ECG). The purpose of this study was to test the hypothesis that an individualized corrected QT interval derived from 24-hour Holter data more accurately predicts carriage of a pathogenic LQTS mutation than did QT derived from a standard 12-lead ECG and corrected using the Bazett formula (QTc interval). Carriers of a pathogenic LQTS mutation and their genotype-negative family members who had both resting ECG and Holter recordings available were included. Automated and manual measurements of QTc were performed. QTi was derived from 24-hour Holter recordings and defined as the QT value at the intersection of an RR interval of 1000 ms, with the linear regression line fitted through QT-RR data points of each individual patient. In total, 69 patients with LQTS (23 long QT type 1, 39 long QT type 2, and 7 long QT type 3) and 55 controls were selected. Demographic characteristics were comparable. A comparison of the receiver operating characteristic curves indicates that the test added diagnostic value compared to manual measurement (P = .02) or automated measurement (P = .005). The diagnostic accuracy of manually measured QTc using conventional cutoff criteria was 72%, while it was 92% using a sex-independent QTi cutoff of 445 ms. This was caused by a 39% increase in sensitivity without compromising the specificity. QTi derived from Holter recordings is superior to conventional QTc measured from a standard 12-lead ECG in predicting the mutation carrier state in families with LQTS. Copyright © 2016 Heart Rhythm Society. Published by Elsevier Inc. All rights reserved.

  8. Population-based beat-to-beat QT analysis from Holter recordings in the long QT syndrome.

    PubMed

    Page, Alex; McNitt, Scott; Xia, Xiaojuan; Zareba, Wojciech; Couderc, Jean-Philippe

    2017-08-10

    The increasing dissemination of wearable ECG recorders (e.g. Holter, patches, and strap sensors) enables the acquisition of large amounts of data during long periods of time. However, the clinical value of these long-term continuous recordings is hindered by the lack of automatic tools to extract clinically relevant information (other than non-sinus and life-threatening rhythms) from such long-term data, particularly when targeting population-based research. In this work, we propose and test a new tool for analyzing beat-to-beat interval measurements and extracting features from Holter ECGs. Specifically, we assess the adaptation of the QT interval following sudden changes in heart rate in the primary long QT types (1 & 2). We find that in long QT syndrome type 2, certain QT adaptation patterns can indicate a higher risk for cardiac events. Copyright © 2017 Elsevier Inc. All rights reserved.

  9. Management of Patients with Long QT Syndrome

    PubMed Central

    2016-01-01

    Long QT syndrome (LQTS) is a rare cardiac channelopathy associated with syncope and sudden death due to torsades de pointes and ventricular fibrillation. Syncope and sudden death are frequently associated with physical and emotional stress. Management of patients with LQTS consists of life-style modification, β-blockers, left cardiac sympathetic denervation (LCSD), and implantable cardioverter-defibrillator (ICD) implantation. Prohibition of competitive exercise and avoidance of QT-prolonging drugs are important issues in life-style modification. Although β-blockers are the primary treatment modality for patients with LQTS, these drugs are not completely effective in some patients. Lifelong ICD implantation in young and active patients is associated with significant complications. LCSD is a relatively simple and highly effective surgical procedure. However, LCSD is rarely used. PMID:27826330

  10. Clarithromycin-Induced Long QT Syndrome: A Case Report

    PubMed Central

    Cetin, Mecnun; Yıldırımer, Munevver; Özen, Serkan; Tanrıverdi, Sema; Coskun, Senol

    2012-01-01

    Long QT syndrome develops for a number of reasons. The number of non-antiarrhythmic drugs reported to induce QT interval prolongation with or without torsade de pointes continues to increase. Clarithromycin is a macrolide antibiotic being increasingly used for the treatment of atypical pneumonia. In this paper, we describe a patient who developed long QT prolongation syndrome after receiving clarithromycin for the treatment of atypical pneumonia. PMID:22489247

  11. What Are the Signs and Symptoms of Long QT Syndrome?

    MedlinePlus

    ... NHLBI on Twitter. What Are the Signs and Symptoms of Long QT Syndrome? Major Signs and Symptoms If you have long QT syndrome (LQTS), you ... first sign of the disorder. Other Signs and Symptoms Often, people who have LQTS 3 develop an ...

  12. Increased QT interval dispersion in diagnosis of acute coronary syndrome with atypical symptoms and EKG.

    PubMed

    Rodríguez, Fernando; Chávez, Elibet; Machín, Wilfredo J; Alonso, Alain; González, Vielka

    2014-01-01

    INTRODUCTION EKG remains a highly valuable tool for heart disease management. Corrected QT interval dispersion is a useful EKG parameter to assess prognosis in ischemic heart disease and specifically acute coronary syndrome. Understanding QT interval physiopathology helps assess importance of QT measurement in this context. Although increased QT dispersion is an ominous prognostic marker, its utility has not been evaluated for all types of acute coronary syndrome, even though in many circumstances it is the only tool available for diagnosing patients with equivocal EKG signs and/or atypical symptoms. OBJECTIVE Describe corrected QT interval dispersion in acute coronary syndrome in three groups of patients-with ST elevation, without ST elevation, and without ST elevation with equivocal EKG signs-admitted to the intensive care unit of Celestino Hernández Robau University Hospital in Santa Clara, Cuba, from January 2010 through June 2011. METHODS A descriptive retrospective study was conducted in 194 patients admitted with diagnosis of acute coronary syndrome. QT interval was measured and its dispersion calculated for the first EKG after symptom onset. Patterns were assessed for typical and atypical clinical presentations, and unequivocal and equivocal EKG signs. RESULTS Nonclassifiable acute coronary syndrome was found in 6.7% of patients (13/194), the majority of whom had increased QT dispersion (76.9%, 10/13). There were significant differences in QT dispersion patterns between patients with typical and atypical presentations and between patients with equivocal and unequivocal EKG findings. In non-ST elevation acute coronary syndrome and nonclassifiable acute coronary syndrome with increased dispersion, atypical presentation was the most common (65.5%, 19/29; and 90%, 9/10, respectively). CONCLUSION Corrected QT interval dispersion is a useful diagnostic tool for acute coronary syndrome, especially when patients present with atypical symptoms and equivocal EKG

  13. Arrhythmic risk in congenital long QT syndrome.

    PubMed

    Kaufman, Elizabeth S

    2011-01-01

    One of the most important and challenging aspects of caring for patients with congenital long QT syndrome (LQTS) is assessing an individual's risk of sudden cardiac death (SCD) because of torsades de pointes. Current risk assessment integrates clinical and genetic features known to be associated with SCD, but more accurate methods of risk assessment could lead to more appropriate use of therapies, potentially saving lives and avoiding overtreatment. Conventional indices of risk include sex, age, extent of QT prolongation, history of symptoms (syncope or aborted SCD), and genetic subtype. The biophysical properties of specific mutations (eg, those that affect transmembrane segments of the ion channel protein or those that cause a dominant negative effect on ion channel function vs haplotype insufficiency) also contribute to risk. A growing body of basic mechanistic and clinical evidence points to heterogeneity of repolarization as a potent determinant of risk in LQTS patients. Mechanistically, heterogeneities of repolarization provide substrate for reentry, which likely causes perpetuation of torsades de pointes. Clinical markers that reflect heterogeneity of repolarization include abnormal microvolt-level T wave alternans, increased Tpeak-end interval, and dispersion of mechanical contraction time. The optimal methodology for using these indices as risk predictors in LQTS remains under active investigation. Further studies are needed to determine how indices of heterogeneity such as microvolt-level T wave alternans, Tpeak-end interval, and dispersion of mechanical contraction can be incorporated into models of risk prediction in LQTS, both for initial risk stratification and for assessment of efficacy of therapies.

  14. Automated T-wave analysis can differentiate acquired QT prolongation from congenital long QT syndrome.

    PubMed

    Sugrue, Alan; Noseworthy, Peter A; Kremen, Vaclav; Bos, J Martijn; Qiang, Bo; Rohatgi, Ram K; Sapir, Yehu; Attia, Zachi I; Brady, Peter; Caraballo, Pedro J; Asirvatham, Samuel J; Friedman, Paul A; Ackerman, Michael J

    2017-04-21

    Prolongation of the QT on the surface electrocardiogram can be due to either genetic or acquired causes. Distinguishing congenital long QT syndrome (LQTS) from acquired QT prolongation has important prognostic and management implications. We aimed to investigate if quantitative T-wave analysis could provide a tool for the physician to differentiate between congenital and acquired QT prolongation. Patients were identified through an institution-wide computer-based QT screening system which alerts the physician if the QTc ≥ 500 ms. ECGs were retrospectively analyzed with an automated T-wave analysis program. Congenital LQTS was compared in a 1:3 ratio to those with an identified acquired etiology for QT prolongation (electrolyte abnormality and/or prescription of known QT prolongation medications). Linear discriminant analysis was performed using 10-fold cross-validation to statistically test the selected features. The 12-lead ECG of 38 patients with congenital LQTS and 114 patients with drug-induced and/or electrolyte-mediated QT prolongation were analyzed. In lead V5 , patients with acquired QT prolongation had a shallower T wave right slope (-2,322 vs. -3,593 mV/s), greater T-peak-Tend interval (109 vs. 92 ms), and smaller T wave center of gravity on the x axis (290 ms vs. 310 ms; p < .001). These features could distinguish congenital from acquired causes in 77% of cases (sensitivity 90%, specificity 58%). T-wave morphological analysis on lead V5 of the surface ECG could successfully differentiate congenital from acquired causes of QT prolongation. © 2017 Wiley Periodicals, Inc.

  15. Repolarization analysis in children with the long QT syndrome.

    PubMed

    Brockmeier, Konrad; Khalil, Markus; Sreeram, Narayanswami; Ulmer, Herbert E

    2003-01-01

    QT duration changes were analysed in 26 children with long QT syndrome (median age 9 years). With 12-lead Holter recordings, we found that macroscopically QT adaptation to heart rate changes was slow and only 3 of 26 patients showed abrupt changes in QT interval duration. These changes in the time domain were always accompanied by changes of STT morphology in the 3 of 26 patients. Application of Bazett's heart rate correction algorithm was inappropriate to show true QT changes in this young patient group due to temporary typical large cycle length variations, where moreover an overcorrection of the heart rate impact resulted in reflection of RR interval changes rather than true QT duration changes.

  16. Drug-Induced Long QT Syndrome

    PubMed Central

    Kannankeril, Prince; Darbar, Dawood

    2010-01-01

    The drug-induced long QT syndrome is a distinct clinical entity that has evolved from an electrophysiologic curiosity to a centerpiece in drug regulation and development. This evolution reflects an increasing recognition that a rare adverse drug effect can profoundly upset the balance between benefit and risk that goes into the prescription of a drug by an individual practitioner as well as the approval of a new drug entity by a regulatory agency. This review will outline how defining the central mechanism, block of the cardiac delayed-rectifier potassium current IKr, has contributed to defining risk in patients and in populations. Models for studying risk, and understanding the way in which clinical risk factors modulate cardiac repolarization at the molecular level are discussed. Finally, the role of genetic variants in modulating risk is described. PMID:21079043

  17. [The long QT syndrome: epilepsy as the form of presentation].

    PubMed

    Gatto, E M; Fernández Pardal, M M; Micheli, F; González, M A; Daru, V D

    1993-05-01

    Prolongation of the QT interval, either on a congenital or an acquired basis, is associated with an increased likelihood of malignant ventricular arrhythmias with a high rate of morbimortality. Symptoms are variables, and patients may develop seizures, syncope and sudden death. Herein we report a young woman 17 years old with long QT syndrome, seizures and recurrent attacks of syncope; her initial diagnosis was primary epilepsy. An electrocardiogram performed 3 years after the initials symptoms was able to make the diagnosis long QT syndrome. The specific treatment controlled the malignant ventricular arrhythmias and the symptomatic status of this patient.

  18. Drug-induced fatal arrhythmias: Acquired long QT and Brugada syndromes.

    PubMed

    Turker, Isik; Ai, Tomohiko; Itoh, Hideki; Horie, Minoru

    2017-08-01

    Since the early 1990s, the concept of primary "inherited" arrhythmia syndromes or ion channelopathies has evolved rapidly as a result of revolutionary progresses made in molecular genetics. Alterations in genes coding for membrane proteins such as ion channels or their associated proteins responsible for the generation of cardiac action potentials (AP) have been shown to cause specific malfunctions which eventually lead to cardiac arrhythmias. These arrhythmic disorders include congenital long QT syndrome, Brugada syndrome, catecholaminergic polymorphic ventricular tachycardia, short QT syndrome, progressive cardiac conduction disease, etc. Among these, long QT and Brugada syndromes are the most extensively studied, and drugs cause a phenocopy of these two diseases. To date, more than 10 different genes have been reported to be responsible for each syndrome. More recently, it was recognized that long QT syndrome can be latent, even in the presence of an unequivocally pathogenic mutation (silent mutation carrier). Co-existence of other pathological conditions in these silent mutation carriers may trigger a malignant form of ventricular arrhythmia, the so called torsade de pointes (TdP) that is most commonly brought about by drugs. In analogy to the drug-induced long QT syndrome, Brugada type 1 ECG can also be induced or unmasked by a wide variety of drugs and pathological conditions; so physicians may encounter patients with a latent form of Brugada syndrome. Of particular note, Brugada syndrome is frequently associated with atrial fibrillation whose therapeutic agents such as Vaughan Williams class IC drugs can unmask the dormant and asymptomatic Brugada syndrome. This review describes two types of drug-induced arrhythmias: the long QT and Brugada syndromes. Copyright © 2017. Published by Elsevier Inc.

  19. Syncope in genotype-negative long QT syndrome family members.

    PubMed

    Olde Nordkamp, Louise R A; Ruwald, Martin H; Goldenberg, Ilan; Wieling, Wouter; McNitt, Scott; Polonsky, Bronislava; Wilde, Arthur A M; van Dijk, Nynke; Moss, Arthur J

    2014-10-15

    Unaffected long-QT syndrome family members (FMs) frequently experience syncope. The aims of this study were to test the hypothesis that syncope events in FMs are benign events and to compare clinical characteristics, triggers eliciting the syncope events, and long-term outcomes between FMs and those with LQT1 or LQT2 mutations from the international Long QT Syndrome Registry. A total of 679 FMs, 864 LQT1 patients, and 782 LQT2 patients were included. Seventy-eight FMs (11%) experienced cardiovascular events. Almost all cardiovascular events were nonfatal syncope; only 1 FM, with an additional mitral valve prolapse, experienced aborted cardiac arrest during exercise. The mean age at first syncope in FMs was 17 years, and female FMs experienced syncope more frequently than male FMs (14% vs 9%, p = 0.027). Syncope was more frequently triggered by exercise in LQT1 patients (43% in LQT1 patients vs 5% in FMs, p <0.001), while syncope triggered by a variety of other triggers was more frequent in FMs (54% in FMs vs 22% in LQT1 patients and 30% in LQT2 patients, p <0.001 for both). None of the FMs experienced aborted cardiac arrest or sudden cardiac death after the first syncopal episode. In conclusion, syncope is frequently present in FMs, and these syncopal events occurred more frequently in female than in male FMs, with an increased incidence in midadolescence. Triggers eliciting the syncopal events were different between FMs and patients with long-QT syndrome mutations. Hence, the type of trigger is useful in distinguishing between high- and low-risk syncope. These data indicate that FMs from families with LQTS have a benign form of syncope, most likely related to vasovagal syncope and not ventricular tachyarrhythmic syncope.

  20. Structure of the Cyclic Nucleotide-Binding Homology Domain of the hERG Channel and Its Insight into Type 2 Long QT Syndrome

    PubMed Central

    Li, Yan; Ng, Hui Qi; Li, Qingxin; Kang, CongBao

    2016-01-01

    The human ether-à-go-go related gene (hERG) channel is crucial for the cardiac action potential by contributing to the fast delayed-rectifier potassium current. Mutations in the hERG channel result in type 2 long QT syndrome (LQT2). The hERG channel contains a cyclic nucleotide-binding homology domain (CNBHD) and this domain is required for the channel gating though molecular interactions with the eag domain. Here we present solution structure of the CNBHD of the hERG channel. The structural study reveals that the CNBHD adopts a similar fold to other KCNH channels. It is self-liganded and it contains a short β-strand that blocks the nucleotide-binding pocket in the β-roll. Folding of LQT2-related mutations in this domain was shown to be affected by point mutation. Mutations in this domain can cause protein aggregation in E. coli cells or induce conformational changes. One mutant-R752W showed obvious chemical shift perturbation compared with the wild-type, but it still binds to the eag domain. The helix region from the N-terminal cap domain of the hERG channel showed unspecific interactions with the CNBHD. PMID:27025590

  1. How Is Long QT Syndrome Diagnosed?

    MedlinePlus

    ... a simple test that detects and records the heart's electrical activity. This test may show a long QT interval ... a Holter monitor . A Holter monitor records the heart's electrical activity for a full 24- or 48-hour period. ...

  2. Genotype-phenotype correlation in long QT syndrome

    PubMed Central

    Baskar, Shankar; Aziz, Peter F.

    2015-01-01

    Congenital long QT syndrome, caused by a cardiac channelopathy, is a leading cause of sudden cardiac death in the young population. In total, 16 genes have been implicated in this condition, with three genes being the most commonly affected. Long QT syndrome is one of the earliest conditions for which a genotype specific treatment was designed. This genotype-phenotype correlation extends to involve the clinical presentation, electrocardiographic manifestation and treatment strategies. It is necessary for the clinician treating these patients to be cognizant of the important role played by the genotype in order to best provide counseling and treatment options to this unique population. PMID:26779509

  3. Antiarrhythmic vs. pro-arrhythmic effects depending on the intensity of adrenergic stimulation in a canine anthopleurin-A model of type-3 long QT syndrome.

    PubMed

    Chinushi, Masaomi; Izumi, Daisuke; Iijima, Kenichi; Ahara, Shizue; Komura, Satoru; Furushima, Hiroshi; Hosaka, Yukio; Aizawa, Yoshifusa

    2008-02-01

    The effects of adrenergic activity and beta-blockade were studied in a canine experimental model of type-3 long QT syndrome (LQT3) induced by application of anthopleurin-A. Boluses of epinephrine at 0.5 and/or 1.0 microg/kg were administered before and after propranolol, 0.3 mg/kg, and the distribution of the ventricular repolarization and the development of polymorphic ventricular tachyarrhythmia (VA) were assessed. Using needle electrodes, transmural unipolar electrograms were recorded across the left ventricle (LV) and right ventricle (RV). Activation-recovery interval (ARI) was measured in each electrogram to estimate local repolarization during RV pacing at the cycle length of 750 ms after the creation of complete atrioventricular block. Before propranolol, epinephrine, 0.5 microg/kg, did not induce VA in any experiment. However, a dose of 1.0 microg/kg induced polymorphic VA following multiple premature ventricular complex (PVC) in four of six experiments. Epinephrine, 0.5 microg/kg, shortened ARI at all sites and lessened LV transmural ARI dispersion. Neither ARI nor its dispersion could be determined after 1.0 microg/kg of epinephrine because of the induction of PVC, polymorphic VA, or both. Propranolol (i) prevented epinephrine-induced PVC and polymorphic VA in all experiments, (ii) slightly prolonged ARI at all sites, along with a decrease in LV transmural ARI dispersion, and (iii) reversed the epinephrine-induced shortening of ARI. In this LQT3 model, an increase in adrenergic activity by epinephrine had dose-dependent, opposite effects on ventricular electrical stability. Since beta-adrenergic blockade suppressed epinephrine-induced PVC and polymorphic VA, it might be considered for supplemental therapy to suppress VA in patients presenting with LQT3.

  4. Stressful life events and depressive symptoms among symptomatic long QT syndrome patients.

    PubMed

    Hintsa, Taina; Jokela, Markus; Elovainio, Marko; Määttänen, Ilmari; Swan, Heikki; Hintsanen, Mirka; Toivonen, Lauri; Kontula, Kimmo; Keltikangas-Järvinen, Liisa

    2016-04-01

    We examined whether long QT syndrome status moderates the association between stressful life events and depressive symptoms. Participants were 562 (n= 246 symptomatic) long QT syndrome mutation carriers. Depressive symptoms were measured with a modified version of the Beck's Depression Inventory. There was an interaction between long QT syndrome status and stressful life events on depressive symptoms. In the symptomatic long QT syndrome patients, stressful life events were associated with depressive symptoms (B= 0.24, p< 0.001). In the asymptomatic long QT syndrome mutation carriers, this association was 62.5 percent weaker (B= 0.09, p= 0.057). Compared to asymptomatic long QT syndrome mutation carriers, symptomatic long QT syndrome patients are more sensitive to the depressive effects of stressful life events. © The Author(s) 2014.

  5. [Long QT syndrome. History, genetics, clinical symptoms, causes and therapy].

    PubMed

    Krönauer, T; Friederich, P

    2015-08-01

    The long QT syndrome is caused by a change in cardiac repolarization due to functional ion channel defects. A differentiation is made between a congenital (cLQTS) and an acquired (aLQTS) form of the disease. The disease results in the name-giving prolongation of the QT interval in the electrocardiogram and represents a predisposition for cardiac arrhythmia and sudden cardiac death. This article summarizes the current knowledge on the history, pathophysiology, clinical symptoms and therapy of cLQTS and aLQTS. This knowledge of pathophysiological features of the symptoms allows the underlying anesthesiological approach for individualized perioperative concepts for patients suffering from LQTS to be derived.

  6. Provocation of sudden heart rate oscillation with adenosine exposes abnormal QT responses in patients with long QT syndrome: a bedside test for diagnosing long QT syndrome

    PubMed Central

    Viskin, Sami; Rosso, Raphael; Rogowski, Ori; Belhassen, Bernard; Fourey, Dana; Zeltser, David; Rozovski, Uri; Levitas, Aviva; Wagshal, Abraham; Katz, Amos; Oliva, Antonio; Pollevick, Guido D.; Antzelevitch, Charles

    2006-01-01

    Aims As arrhythmias in the long QT syndrome (LQTS) are triggered by heart rate deceleration or acceleration, we speculated that the sudden bradycardia and subsequent tachycardia that follow adenosine injection would unravel QT changes of diagnostic value in patients with LQTS. Methods and results Patients (18 LQTS and 20 controls) received intravenous adenosine during sinus rhythm. Adenosine was injected at incremental doses until atrioventricular block or sinus pauses lasting 3 s occurred. The QT duration and morphology were studied at baseline and at the time of maximal bradycardia and subsequent tachycardia. Despite similar degree of adenosine-induced bradycardia (longest R-R 1.7 + 0.7 vs. 2.2 + 1.3 s for LQTS and controls, P = NS), the QT interval of LQT patients increased by 15.8 + 13.1%, whereas the QT of controls increased by only 1.5 + 6.7% (P<0.001). Similarly, despite similar reflex tachycardia (shortest R-R 0.58 + 0.07 vs. 0.55 + 0.07 s for LQT patients and controls, P = NS), LQTS patients developed greater QT prolongation (QTc = 569 + 53 vs. 458 + 58 ms for LQT patients and controls, P<0.001). The best discriminator was the QTc during maximal bradycardia. Notched T-waves were observed in 72% of LQT patients but in only 5% of controls during adenosine-induced bradycardia (P<0.001). Conclusion By provoking transient bradycardia followed by sinus tachycardia, this adenosine challenge test triggers QT changes that appear to be useful in distinguishing patients with LQTS from healthy controls. PMID:16105845

  7. Ratio of late to early T-wave peak amplitude in 24-h electrocardiographic recordings as indicator of symptom history in patients with long-QT Syndrome types 1 and 2.

    PubMed

    Viitasalo, Matti; Oikarinen, Lasse; Swan, Heikki; Glatter, Kathryn A; Väänänen, Heikki; Fodstad, Heidi; Chiamvimonvat, Nipavan; Kontula, Kimmo; Toivonen, Lauri; Scheinman, Melvin M

    2006-01-03

    We reviewed 24-h electrocardiographic recordings from 214 genotyped subjects--97 with long-QT syndrome type 1 (LQT1), 62 with LQT2, and 55 unaffected--to record maximal diurnal amplitude ratios between late and early T-wave peaks. Maximal amplitude ratios between late and early T-wave peaks were higher in symptomatic than in asymptomatic patients both in LQT1 (3.2 +/- 1.0 vs. 2.3 +/- 0.8; p < 0.001) and in LQT2 patients (2.6 +/- 1.0 vs. 1.7 +/- 0.5; p < 0.001). The maximal amplitude ratio between late and early T-wave peaks was independently associated with symptom history in both LQT1 and LQT2 patients. We tested the hypothesis that in long-QT syndrome types 1 (LQT1) and 2 (LQT2), the diurnal maximal ratio between late and early T-wave peak amplitudes correlates with a history of symptoms better than QT interval durations. Genotype and phenotype studies have delineated clinical profiles of the most prevalent LQT1 and LQT2 subtypes of inherited LQT, but prediction of arrhythmia risk remains uncertain, the baseline QTc interval being the best predictor. In experimental long-QT syndrome models, the ratio between late and early T-wave peak amplitude predicts onset of torsade de pointes. We reviewed 24-h electrocardiographic recordings from 214 genotyped subjects--97 with LQT1, 62 with LQT2, and 55 unaffected-to record maximal amplitude ratios between late and early T-wave peaks by use of a computer-assisted program. Maximal amplitude ratios between late and early T-wave peaks were higher in symptomatic than in asymptomatic patients both in LQT1 (3.2 +/- 1.0 vs. 2.3 +/- 0.8; p < 0.001) and LQT2 patients (2.6 +/- 1.0 vs. 1.7 +/- 0.5; p < 0.001). Although the QTc interval also was longer in symptomatic patients, only the maximal amplitude ratio between late and early T-wave peaks was independently associated with symptoms in both LQT1 and LQT2 patients. Maximal diurnal ratio between late and early T-wave peak amplitude improves noninvasive risk assessment both in LQT1

  8. Congenital and drug-induced long-QT syndrome: an update

    PubMed Central

    Wehrens, X.H.T.; Doevendans, P.A.

    2004-01-01

    The congenital long-QT syndrome is a potentially life-threatening condition characterised clinically by prolonged QT intervals, syncope and sudden cardiac death. The abnormally prolonged repolarisation is the result of mutations in genes encoding cardiac ion channels. The diagnosis of long-QT syndrome is based on clinical, electrocardiographic, and genetic criteria. Beta-blocking therapy is important in the treatment of long-QT syndrome, although pacemakers and implantable cardioverter defibrillators (ICD) are useful in certain categories of patients. In the near future, mutation-specific treatment will probably become a novel approach to this potentially lethal syndrome. Drug-induced long-QT syndrome has been associated with silent mutations and common polymorphisms in potassium and sodium channel genes associated with congenital long-QT syndrome. Genetic screening for such mutations and polymorphisms may become an important instrument in preventing drug-induced 'torsades de pointes' arrhythmias in otherwise asymptomatic patients. PMID:25696318

  9. Use of mutant-specific ion channel characteristics for risk stratification of long QT syndrome patients.

    PubMed

    Jons, Christian; O-Uchi, Jin; Moss, Arthur J; Reumann, Matthias; Rice, John J; Goldenberg, Ilan; Zareba, Wojciech; Wilde, Arthur A M; Shimizu, Wataru; Kanters, Jorgen K; McNitt, Scott; Hofman, Nynke; Robinson, Jennifer L; Lopes, Coeli M B

    2011-03-30

    Inherited long QT syndrome (LQTS) is caused by mutations in ion channels that delay cardiac repolarization, increasing the risk of sudden death from ventricular arrhythmias. Currently, the risk of sudden death in individuals with LQTS is estimated from clinical parameters such as age, gender, and the QT interval, measured from the electrocardiogram. Even though a number of different mutations can cause LQTS, mutation-specific information is rarely used clinically. LQTS type 1 (LQT1), one of the most common forms of LQTS, is caused by mutations in the slow potassium current (I(Ks)) channel α subunit KCNQ1. We investigated whether mutation-specific changes in I(Ks) function can predict cardiac risk in LQT1. By correlating the clinical phenotype of 387 LQT1 patients with the cellular electrophysiological characteristics caused by an array of mutations in KCNQ1, we found that channels with a decreased rate of current activation are associated with increased risk of cardiac events (hazard ratio=2.02), independent of the clinical parameters usually used for risk stratification. In patients with moderate QT prolongation (a QT interval less than 500 ms), slower activation was an independent predictor for cardiac events (syncope, aborted cardiac arrest, and sudden death) (hazard ratio = 2.10), whereas the length of the QT interval itself was not. Our results indicate that genotype and biophysical phenotype analysis may be useful for risk stratification of LQT1 patients and suggest that slow channel activation is associated with an increased risk of cardiac events.

  10. TRPM4 non-selective cation channel variants in long QT syndrome.

    PubMed

    Hof, Thomas; Liu, Hui; Sallé, Laurent; Schott, Jean-Jacques; Ducreux, Corinne; Millat, Gilles; Chevalier, Philippe; Probst, Vincent; Guinamard, Romain; Bouvagnet, Patrice

    2017-03-18

    Long QT syndrome (LQTS) is an inherited arrhythmic disorder characterized by prolongation of the QT interval, a risk of syncope, and sudden death. There are already a number of causal genes in LQTS, but not all LQTS patients have an identified mutation, which suggests LQTS unknown genes. A cohort of 178 LQTS patients, with no mutations in the 3 major LQTS genes (KCNQ1, KCNH2, and SCN5A), was screened for mutations in the transient potential melastatin 4 gene (TRPM4). Four TRPM4 variants (2.2% of the cohort) were found to change highly conserved amino-acids and were either very rare or absent from control populations. Therefore, these four TRPM4 variants were predicted to be disease causing. Furthermore, no mutations were found in the DNA of these TRPM4 variant carriers in any of the 13 major long QT syndrome genes. Two of these variants were further studied by electrophysiology (p.Val441Met and p.Arg499Pro). Both variants showed a classical TRPM4 outward rectifying current, but the current was reduced by 61 and 90% respectively, compared to wild type TRPM4 current. This study supports the view that TRPM4 could account for a small percentage of LQTS patients. TRPM4 contribution to the QT interval might be multifactorial by modulating whole cell current but also, as shown in Trpm4(-/-) mice, by modulating cardiomyocyte proliferation. TRPM4 enlarges the subgroup of LQT genes (KCNJ2 in Andersen syndrome and CACNA1C in Timothy syndrome) known to increase the QT interval through a more complex pleiotropic effect than merely action potential alteration.

  11. Evaluation and Management of Athletes With Long QT Syndrome.

    PubMed

    Gomez, Andrew T; Prutkin, Jordan M; Rao, Ashwin L

    The congenital long QT syndrome (LQTS) is an inherited channelopathy known for its electrocardiographic manifestations of QT prolongation and its hallmark arrhythmia, torsades de pointes (TdP). TdP can lead to syncope or sudden death and is often precipitated by triggers such as physical exertion or emotional stress. Given that athletes may be at particular risk for adverse outcomes, those suspected of having LQTS should be evaluated, risk stratified, treated, and receive appropriate counseling by providers with sufficient expertise according to the latest guidelines. The following keywords were used to query MEDLINE and PubMed through 2016: LQTS, LQT1, LQT2, LQT3, long QT, long QTc, prolonged QT, prolonged QTc, QT interval, QTc interval, channelopathy, channelopathies, athletes, torsades de pointes, and sudden cardiac death. Selected articles within this primary search, in addition to relevant references from those articles, were reviewed for relevant information and data. Articles with pertinent information regarding pathophysiology, evaluation, diagnosis, genetic testing, treatment, and guidelines for athletes were included, particularly those published in the prior 2 decades. Clinical review. Level 3. Diagnosis of LQTS involves eliciting the patient's family history, clinical history, and evaluation of electrocardiographic findings. Genetic testing for common mutations can confirm suspected cases. β-Blockers represent the mainstay of treatment, though interventions such as implantable cardioverter-defibrillator placement or left cardiac sympathetic denervation may be required. Properly evaluated and treated athletes with LQTS have a low risk of cardiac events. Detection and management of LQTS in the athletic population is crucial given the possibility of adverse outcomes with the stress of athletic participation. Preparticipation screening examinations should include a thorough clinical and family history. Screening electrocardiograms may display key findings

  12. Brief report: Emotional distress and recent stressful life events in long QT syndrome mutation carriers.

    PubMed

    Määttänen, Ilmari; Jokela, Markus; Pulkki-Råback, Laura; Keltikangas-Järvinen, Liisa; Swan, Heikki; Toivonen, Lauri; Merjonen, Päivi; Hintsa, Taina

    2015-11-01

    To study emotional distress in symptomatic and asymptomatic long QT syndrome mutation carriers who had experienced a recent stressful life event. The participants were 209 symptomatic and 279 asymptomatic long QT syndrome mutation carriers. Emotional distress was assessed with the Cope questionnaire and stressful life events with the Social Readjustment Rating Scale. Symptomatic long QT syndrome mutation carriers with burdening recent stressful life events reported a higher emotional distress (β = 0.35, p < 0.001), while the asymptomatic did not show such difference (β = 0.13, p = 0.393). Symptomatic long QT syndrome mutation carriers who have experienced stressful life events recently report an increased emotional distress.

  13. Human congenital long QT syndrome: more than previously thought?

    PubMed

    Attali, Bernard

    2002-06-01

    Mutations in KCNQ1 and KCNE1, the alpha- and beta-subunits of the I(KS) K+ channel, produce the cardiac long QT (LQT) syndrome. These subunits are expressed in heart and inner ear, but also in epithelial tissues such as kidney or intestine where their functional roles have remained elusive. Recent work has shown that KCNE1-deficient mice display chronic hypokalemia and hyperaldosteronism. These results have significant implications for human congenital LQT syndromes because hypokalemia increases the risk of ventricular arrhythmia and cardiac sudden death.

  14. Anaesthesia Application for Cardiac Denervation in a Patient with Long QT Syndrome and Cardiomyopathy

    PubMed Central

    Karadeniz, Ümit; Demir, Aslı; Koçulu, Rabia

    2016-01-01

    Long QT syndrome is a congenital disorder that is characterized by a prolongation of the QT interval on electrocardiograms and a propensity to ventricular tachyarrhythmias, which may lead to syncope, cardiac arrest or sudden death. Cardiomyopathy and pulmonary hypertension diseases have additional risks in anaesthesia management. In this study, we emphasize on one lung ventilation, pacemaker-implantable cardioverter–defibrillator and the anaesthesia management process in a patient with long QT syndrome, cardiomyopathy and pulmonary hypertension who underwent thoracic sympathectomy. PMID:27366557

  15. Genetic and clinical advances in congenital long QT syndrome.

    PubMed

    Mizusawa, Yuka; Horie, Minoru; Wilde, Arthur A M

    2014-01-01

    Congenital long QT syndrome (LQTS) is an inherited arrhythmia syndrome characterized by a prolonged QT interval on the 12-lead ECG, torsades de pointes and a higher chance of sudden cardiac death. LQTS segregates in a Mendelian fashion, which includes Romano-Ward syndrome with an autosomal dominant pattern as well as a rare autosomal recessive pattern (Jervell and Lange-Nielsen syndrome). Since 1957 when Jervell and Lange-Nielsen reported the first familial LQTS with congenital deafness, progress in understanding the genetic and electrophysiological mechanisms of LQTS has tremendously improved diagnostic methods and treatments. In the meantime, it has become evident that LQTS may not always be explained by a single gene mutation, but seems to follow a more complex genetic model intertwined with genetic common polymorphisms that have a mild to moderate effect on disease expression. In this review, we summarize the characteristics of LQTS (mainly LQT1-3) and briefly describe the most recent advances in LQTS clinical diagnostics as well as genetics.

  16. I(Kr) channel blockade to unmask occult congenital long QT syndrome.

    PubMed

    Jeyaraj, Darwin; Abernethy, Denise P; Natarajan, Rupa N; Dettmer, Mary M; Dikshteyn, Maria; Meredith, Diana M; Patel, Kevin; Allareddy, Raghavendra R; Lewis, Steven A; Kaufman, Elizabeth S

    2008-01-01

    Patients with genetic evidence of long QT syndromes type 1 and 2 (LQT1, associated with impaired outward potassium current I(Ks); and LQT2, associated with impaired outward potassium current I(Kr)) may have normal baseline QT intervals (phenotype/genotype discordance) and elude clinical detection. Beta-adrenergic stimulation may unmask occult LQT1, but no maneuver has consistently unmasked the LQT2 phenotype. The purpose of this study was to test the repolarization reserve hypothesis (multiple challenges to repolarization are required to produce an abnormal phenotype), using subjects with LQT1 and LQT2 mutations but normal QT interval. We hypothesized that I(Kr) channel blockade would prolong the QT interval excessively in subjects with LQTS compared with controls and that I(Kr) channel blockade could unmask the abnormal LQTS phenotype in subjects with LQTS versus controls, as measured by the T peak-to-end interval (Tpe), a sensitive measure of abnormal repolarization. Subjects with known LQT1 (n = 5) and LQT2 (n = 6) mutations but baseline QTc < or = 450 ms and age- and gender-matched controls (n = 22) received intravenous erythromycin (an I(Kr) blocker). RR, QRS, QT, and Tpe intervals were measured at baseline and after drug infusion. Erythromycin caused only modest QT prolongation in all groups. In contrast, Tpe was specifically prolonged by I(Kr) channel blockade in LQT2 subjects but not in LQT1 subjects or controls. Short-acting I(Kr) channel blockade, together with the sensitive repolarization measure Tpe, can unmask abnormal repolarization in LQT2. Our finding of abnormal repolarization in LQT2 subjects exposed to I(Kr) channel blockade supports the repolarization reserve hypothesis.

  17. Drugs to be avoided in patients with long QT syndrome: Focus on the anaesthesiological management

    PubMed Central

    Fazio, Giovanni; Vernuccio, Federica; Grutta, Giuseppe; Re, Giuseppe Lo

    2013-01-01

    Long QT syndrome incidence is increasing in general population. A careful pre-, peri- and post-operative management is needed for patients with this syndrome because of the risk of Torsades de Pointes and malignant arrhythmias. The available data regarding prevention of lethal Torsades de Pointes during anesthesia in patients with long QT syndrome is scant and conflicting: only case reports and small case series with different outcomes have been published. Actually, there are no definitive guidelines on pre-, peri- and post-operative anesthetic management of congenital long QT syndrome. Our review focuses on anesthetic recommendations for patients diagnosed with congenital long QT syndrome furnishing some key points for preoperative optimization, intraoperative anesthetic agents and postoperative care plan, which could be the best for patients with c-long QT syndrome who undergo surgery. PMID:23675554

  18. Drugs to be avoided in patients with long QT syndrome: Focus on the anaesthesiological management.

    PubMed

    Fazio, Giovanni; Vernuccio, Federica; Grutta, Giuseppe; Re, Giuseppe Lo

    2013-04-26

    Long QT syndrome incidence is increasing in general population. A careful pre-, peri- and post-operative management is needed for patients with this syndrome because of the risk of Torsades de Pointes and malignant arrhythmias. The available data regarding prevention of lethal Torsades de Pointes during anesthesia in patients with long QT syndrome is scant and conflicting: only case reports and small case series with different outcomes have been published. Actually, there are no definitive guidelines on pre-, peri- and post-operative anesthetic management of congenital long QT syndrome. Our review focuses on anesthetic recommendations for patients diagnosed with congenital long QT syndrome furnishing some key points for preoperative optimization, intraoperative anesthetic agents and postoperative care plan, which could be the best for patients with c-long QT syndrome who undergo surgery.

  19. Toward Personalized Medicine: Using Cardiomyocytes Differentiated From Urine-Derived Pluripotent Stem Cells to Recapitulate Electrophysiological Characteristics of Type 2 Long QT Syndrome

    PubMed Central

    Jouni, Mariam; Si-Tayeb, Karim; Es-Salah-Lamoureux, Zeineb; Latypova, Xenia; Champon, Benoite; Caillaud, Amandine; Rungoat, Anais; Charpentier, Flavien; Loussouarn, Gildas; Baró, Isabelle; Zibara, Kazem; Lemarchand, Patricia; Gaborit, Nathalie

    2015-01-01

    Background Human genetically inherited cardiac diseases have been studied mainly in heterologous systems or animal models, independent of patients’ genetic backgrounds. Because sources of human cardiomyocytes (CMs) are extremely limited, the use of urine samples to generate induced pluripotent stem cell–derived CMs would be a noninvasive method to identify cardiac dysfunctions that lead to pathologies within patients’ specific genetic backgrounds. The objective was to validate the use of CMs differentiated from urine-derived human induced pluripotent stem (UhiPS) cells as a new cellular model for studying patients’ specific arrhythmia mechanisms. Methods and Results Cells obtained from urine samples of a patient with long QT syndrome who harbored the HERG A561P gene mutation and his asymptomatic noncarrier mother were reprogrammed using the episomal-based method. UhiPS cells were then differentiated into CMs using the matrix sandwich method. UhiPS-CMs showed proper expression of atrial and ventricular myofilament proteins and ion channels. They were electrically functional, with nodal-, atrial- and ventricular-like action potentials recorded using high-throughput optical and patch-clamp techniques. Comparison of HERG expression from the patient’s UhiPS-CMs to the mother’s UhiPS-CMs showed that the mutation led to a trafficking defect that resulted in reduced delayed rectifier K+ current (IKr). This phenotype gave rise to action potential prolongation and arrhythmias. Conclusions UhiPS cells from patients carrying ion channel mutations can be used as novel tools to differentiate functional CMs that recapitulate cardiac arrhythmia phenotypes. PMID:26330336

  20. Left thoracic sympathectomy in a premature infant with long QT syndrome and heart failure.

    PubMed

    Surendran, Sushitha; Kumar, Thittamaranahalli K S; Knott-Craig, Christopher J

    2017-01-01

    Left thoracic sympathectomy has been shown to be an effective treatment for adults with long QT syndrome who are refractory to medical therapy. We report the successful use of left thoracic sympathectomy for the management of a 10-week-old premature baby with long QT syndrome and heart failure from a large ventricular septal defect and patent ductus arteriosus.

  1. Case report, aetiology, and treatment of an acquired long-QT syndrome.

    PubMed

    Van Asbroeck, P J; Huybrechts, W; De Soir, R

    2014-04-01

    Acquired long-QT syndrome is an iatrogenic disorder, usually induced by drugs, which can cause life-threatening arrhythmias. We present a case report on an acquired long-QT syndrome with an interesting confluence of circumstances, and comment on aetiology and treatment.

  2. Long QT Syndrome and Duodenal Ampullary Adenoma: A New Association

    PubMed Central

    Hughes, Laura; Talha Khan, Muhammad; Khalid Hasan, Muhammad; Inayat, Irteza

    2016-01-01

    KCNQ1 gene mutation has a well-known association with long QT syndrome (LQTS). However, recent studies suggest that it may be implicated in intestinal neoplasia. We present a 27-year-old Hispanic man with a known history of LQTS secondary to KCNQ1 mutation, who presented with painless jaundice. Endoscopic retrograde pancreatic cholangiography revealed a prominent ampulla, with histology consistent with ampullary adenoma with high-grade dysplasia. Further endoscopic studies did not suggest familial adenomatous polyposis. To date, this is the index case of duodenal ampullary adenoma in the setting of KCNQ1 mutation. PMID:27921062

  3. Epinephrine-induced QT interval prolongation: a gene-specific paradoxical response in congenital long QT syndrome.

    PubMed

    Ackerman, Michael J; Khositseth, Anant; Tester, David J; Hejlik, Joseph B; Shen, Win-Kuang; Porter, Co-burn J

    2002-05-01

    To determine the effect of epinephrine on the QT interval in patients with genotyped long QT syndrome (LQTS). Between May 1999 and April 2001, 37 patients (24 females) with genotyped LQTS (19 LQT1, 15 LQT2, 3 LQT3, mean age, 27 years; range, 10-53 years) from 21 different kindreds and 27 (16 females) controls (mean age, 31 years; range, 13-45 years) were studied at baseline and during gradually increasing doses of intravenous epinephrine infusion (0.05, 0.1, 0.2, and 0.3 microg x k(-1) x min(-1)). The 12-lead electrocardiogram was monitored continuously, and heart rate, QT, and corrected QT interval (QTc) were measured during each study stage. There was no significant difference in resting heart rate or chronotropic response to epinephrine between LQTS patients and controls. The mean +/- SD baseline QTc was greater in LQTS patients (500+/-68 ms) than in controls (436+/-19 ms, P<.001). However, 9 (47%) of 19 KVLQT1-genotyped LQT1 patients had a nondiagnostic resting QTc (<460 milliseconds), whereas 11 (41%) of 27 controls had a resting QTc higher than 440 milliseconds. During epinephrine infusion, every LQT1 patient manifested prolongation of the QT interval (paradoxical response), whereas healthy controls and patients with either LQT2 or LQT3 tended to have shortened QT intervals (P<.001). The maximum mean +/- SD change in QT (AQT [epinephrine QT minus baseline QT]) was -5+/-47 ms (controls), +94+/-31 ms (LQT1), and -87+/-67 ms (LQT2 and LQT3 patients). Of 27 controls, 6 had lengthening of their QT intervals (AQT >30 milliseconds) during high-dose epinephrine. Low-dose epinephrine (0.05 microg x kg(-1) x min(-1)) completely discriminated LQT1 patients (AQT, +82+/-34 ms) from controls (AQT, -7+/-13 ms; P<.001). Epinephrine-triggered nonsustained ventricular tachycardia occurred in 2 patients with LQTS and in 1 control. Epinephrine-induced prolongation of the QT interval appears pathognomonic for LQT1. Low-dose epinephrine infusion distinguishes controls from

  4. [Long QT syndrome: a brief review of the electrocardiographical diagnosis including Viskin's test].

    PubMed

    Márquez, Manlio F

    2012-01-01

    The QT interval measures both repolarization and depolarization. Learning to measure the QT interval and know how to correct (QTc) for heart rate (HR) is essential for the diagnosis of long QT syndrome (LQTS). The QTc interval changes in duration and even morphology depending on the time of the day and on a day-to-day basis. A diminished adaptive response of the QTc interval to changes in HR is known as QT hysteresis. Viskin has introduced a very simple clinical test to confirm the diagnosis of LQTS based on the "hypoadaptation" of the QT when standing. This phenomenon gives the appearance of a "stretching of the QT" on the surface ECG. Likewise, he has coined the term "QT stunning" to refer to the phenomenon that the QTc interval does not return to baseline despite recovery of baseline HR after standing. This article shows some examples of the Viskin's test.

  5. Novel long QT syndrome-associated missense mutation, L762F, in CACNA1C-encoded L-type calcium channel imparts a slower inactivation tau and increased sustained and window current.

    PubMed

    Landstrom, Andrew P; Boczek, Nicole J; Ye, Dan; Miyake, Christina Y; De la Uz, Caridad M; Allen, Hugh D; Ackerman, Michael J; Kim, Jeffrey J

    2016-10-01

    Mutations in the CACNA1C-encoded L-type calcium channel have been associated with Timothy syndrome (TS) with severe QT prolongation, syndactyly, facial dysmorphisms, developmental delay, and sudden death. Recently, patients hosting CACNA1C mutations with only long QT syndrome (LQTS) have been described. We sought to identify novel variants in CACNA1C associated with either TS or LQTS, and to determine the impact of the mutation on channel function. Two probands were identified with mutations in CACNA1C, one with a TS-associated mutation, G406R, and a second with genotype-negative LQTS. Illumina HiSeq 2000 whole exome sequencing on the genotype-negative LQTS proband revealed a novel variant, CACNA1C-L762F, that co-segregated within a multi-generational family. The missense mutation localized to the DII/DIII intracellular interlinker segment of the channel in a highly conserved region in close proximity to the 6th transmembrane segment of domain II (DIIS6). Whole cell patch clamp of heterologously expressed CACNA1C-L762F in TSA201 cells demonstrated slower inactivation tau and increased sustained and window current. Comprehensive review and topological mapping of all described CACNA1C mutations revealed TS-specific hotspots localizing to the cytoplasmic aspect of 6th transmembrane segment of respective domains. Probands hosting TS mutations were associated with elevated QTc, higher prevalence of 2:1 AV block, and a younger age at presentation compared to LQTS. The CACNA1C-L762F mutation is associated with development of LQTS through slower channel inactivation and increased sustained and window current. TS-associated mutations localize to specific areas of CACNA1C and are associated with a younger age at presentation, higher QTc, and 2:1 AV block than isolated LQTS-associated mutations. Copyright © 2016 Elsevier Ireland Ltd. All rights reserved.

  6. A Tale of 2 Diseases: The History of Long-QT Syndrome and Brugada Syndrome.

    PubMed

    Havakuk, Ofer; Viskin, Sami

    2016-01-05

    The Brugada syndrome (BrS) and long-QT syndrome (LQTS) present as congenital or acquired disorders with diagnostic electrocardiograms (ST-segment elevation and prolonged QT interval, respectively) and increased risk for malignant arrhythmias. Our understanding of the 2 disease forms (congenital vs. acquired) differs. A female patient on quinidine for atrial fibrillation who develops ventricular fibrillation is diagnosed with "acquired LQTS" and is discharged with no therapy other than instructions to avoid QT-prolonging medications. In contrast, an asymptomatic male patient who develops a Brugada electrocardiogram on flecainide is diagnosed with "asymptomatic BrS" and could be referred for an electrophysiological evaluation that could result in defibrillator implantation. The typical patient undergoing defibrillator implantation for BrS is asymptomatic but has a Brugada electrocardiogram provoked by a drug. The authors describe how the histories of LQTS and BrS went through the same stages, but in different sequences, leading to different conclusions.

  7. Drug-induced long QT syndrome increases the risk of drowning.

    PubMed

    Vincenzi, Frank F

    2016-02-01

    There is strong evidence linking inherited long QT syndromes with an increased risk of drowning due to fatal arrhythmias in the water. Drug-induced long QT syndrome (DILQTS) is hypothesized to increase the risk of drowning by similar mechanisms. It is suggested that QT prolongation caused by a drug or drugs, when combined with the autonomic conflict associated with the mammalian dive reflex and/or the cold shock reflex, sets up conditions that may result in a sudden fatal arrhythmia while in water - thus an increased risk of drowning related to a drug-induced prolongation of the QT interval. Many widely used drugs prolong the QT interval thus raising a drug safety issue that needs confirmation or refutation.

  8. Long QT syndrome mutation detection by SNaPshot technique.

    PubMed

    Edelmann, Jeanett; Schumann, Stefanie; Nastainczyk, Marina; Husser-Bollmann, Daniela; Lessig, Rüdiger

    2012-11-01

    Long QT syndrome (LQTS) is a cardiac disorder with an abnormality of cardiac rhythm associated with sudden death especially in younger, apparently healthy individuals. If there is no clear cause of death detectable during comprehensive coroner's inquest (autopsy-negative cases), you have to consider LQTS and other heritable arrhythmia syndromes. A molecular genetic screening regarding mutations in associated genes can help to ensure the cause of death and to protect affected family members. Genetic testing of LQTS, currently performed mainly by sequencing, is still very expensive and time consuming. With this study we present a rapid and reasonable method for the simultaneously screening of some of the most common mutations associated with LQTS, focused on the KCNQ1 and KCNH2 genes. With the method of SNaPshot minisequencing, a total of 58 mutations were analyzed in four multiplex assays which were successfully established and optimized. The comparison with samples previously analyzed by direct sequencing showed concordance. Furthermore, autopsy-negative cases were tested but no mutations could be observed in any of the specimen. The presented method is well suitable for LQTS mutation screening. An enhancement to further mutations and population-based investigations regarding mutation frequencies should be the aim of prospective studies.

  9. [Progress in research on defective protein trafficking and functional restoration in HERG-associated long QT syndrome].

    PubMed

    Fang, Peiliang; Lian, Jiangfang

    2016-02-01

    The human ether-a-go-go related gene (HERG) encodes the α -subunit of the rapid component of the delayed rectifier K(+) channel, which is essential for the third repolarization of the action potential of human myocardial cells. Mutations of the HERG gene can cause type II hereditary long QT syndrome (LQT2), characterized by prolongation of the QT interval, abnormal T wave, torsade de pointes, syncope and sudden cardiac death. So far more than 300 HERG mutations have been identified, the majority of which can cause LQT2 due to HERG protein trafficking defect. It has been reported that certain drugs can induce acquired long QT syndrome through directly blocking the pore and/or affecting the HERG trafficking. The trafficking defects and K(+) currents can be restored with low temperature and certain drugs. However, the mechanisms underlying defective trafficking caused by HERG mutations and the inhibition/restoration of HERG trafficking by drugs are still unknown. This review summarizes the current understanding of the molecular mechanisms including HERG trafficking under physiological and pathological conditions, and the effects of drugs on the HERG trafficking, in order to provide theoretical evidence for the diagnosis and treatment of long QT syndrome.

  10. Long QT Syndrome: An Emerging Role for Inflammation and Immunity

    PubMed Central

    Lazzerini, Pietro Enea; Capecchi, Pier Leopoldo; Laghi-Pasini, Franco

    2015-01-01

    The long QT syndrome (LQTS), classified as congenital or acquired, is a multi-factorial disorder of myocardial repolarization predisposing to life-threatening ventricular arrhythmias, particularly torsades de pointes. In the latest years, inflammation and immunity have been increasingly recognized as novel factors crucially involved in modulating ventricular repolarization. In the present paper, we critically review the available information on this topic, also analyzing putative mechanisms and potential interplays with the other etiologic factors, either acquired or inherited. Accumulating data indicate inflammatory activation as a potential cause of acquired LQTS. The putative underlying mechanisms are complex but essentially cytokine-mediated, including both direct actions on cardiomyocyte ion channels expression and function, and indirect effects resulting from an increased central nervous system sympathetic drive on the heart. Autoimmunity represents another recently arising cause of acquired LQTS. Indeed, increasing evidence demonstrates that autoantibodies may affect myocardial electric properties by directly cross-reacting with the cardiomyocyte and interfering with specific ion currents as a result of molecular mimicry mechanisms. Intriguingly, recent data suggest that inflammation and immunity may be also involved in modulating the clinical expression of congenital forms of LQTS, possibly triggering or enhancing electrical instability in patients who already are genetically predisposed to arrhythmias. In this view, targeting immuno-inflammatory pathways may in the future represent an attractive therapeutic approach in a number of LQTS patients, thus opening new exciting avenues in antiarrhythmic therapy. PMID:26798623

  11. Genotype–phenotype correlation in long QT syndrome families

    PubMed Central

    Qureshi, Sameera Fatima; Ali, Altaf; Venkateshwari, Ananthapur; Rao, Hygriv; Jayakrishnan, M.P.; Narasimhan, Calambur; Shenthar, Jayaprakash; Thangaraj, Kumarasamy; Nallari, Pratibha

    2015-01-01

    Heterogeneity in clinical manifestations is a well-known feature in Long QT Syndrome (LQTS). The extent of this phenomenon became evident in families wherein both symptomatic and asymptomatic family members are reported. The study hence warrants genetic testing and/or screening of family members of LQTS probands for risk stratification and prediction. Of the 46 families screened, 18 probands revealed novel variations/compound heterozygosity in the gene/s screened. Families 1–4 revealed probands carrying novel variations in KCNQ1 gene along with compound heterozygosity of risk genotypes of the SCN5A, KCNE1 and NPPA gene/s polymorphisms screened. It was also observed that families- 5, 6 and 7 were typical cases of “anticipation” in which both mother and child were diagnosed with congenital LQTS (cLQTS). Families- 16 and 17 represented aLQTS probands with variations in IKs and INa encoding genes. First degree relatives (FDRs) carrying the same haplotype as the proband were also identified which may help in predictive testing and management of LQTS. Most of the probands exhibiting a family history were found to be genetic compounds which clearly points to the role of cardiac genes and their modifiers in a recessive fashion in LQTS manifestation. PMID:27479201

  12. Greater insulin resistance indicates decreased diurnal variation in the QT interval in patients with type 2 diabetes.

    PubMed

    Tanaka, Kotoko; Yodogawa, Kenji; Ono, Takuya; Yana, Kazuo; Miyamoto, Masaaki; Atarashi, Hirotsugu; Kato, Takao; Mizuno, Kyoichi

    2014-03-01

    Circadian variations in the QT interval (QT) and QT dispersion are decreased in patients with type 2 diabetes because of cardioneuropathy. Insulin resistance has been recently identified as an independent determinant of QT prolongation in normoglycemic women. However, the relationship between QT prolongation and the degree of insulin resistance as well as circadian variation remains unclear in diabetic patients. This study was designed to assess the relationship between insulin resistance and the circadian variation in QT measurements in patients with type 2 diabetes. In 14 patients with diabetes, QT, corrected QT (QTc), QT dispersion, QTc dispersion, and RR interval (RR) were analyzed using 12-lead Holter monitoring and commercial software. The degree of diurnal variation in each measurement was defined as the amplitude between the maximum and mean values on curves fitted using the mean cosinor method (A_QT, A_QTc, A_QT dispersion, A_QTc dispersion, and A_RR). The cosine curve was fitted to all measured values in each QT measurement and RR for 24 h. Insulin resistance (glucose infusion rate (GIR)) was measured using the euglycemic hyperinsulinemic glucose clamp method. The maximum QT, QTc, QT dispersion, and QTc dispersion were >450 ms. GIR was significantly correlated with A_QT only (r = 0.59, P < 0.05). GIR was not correlated with other variables, and was dependent only on the circadian variation in QT.

  13. Congenital long QT syndrome: severe torsades de pointes provoked by epinephrine in a digenic mutation carrier.

    PubMed

    Tan, Vern Hsen; Duff, Henry; Kuriachan, Vikas; Gerull, Brenda

    2014-01-01

    Congenital Long QT Syndrome (LQTS) is a potentially lethal cardiac channelopathy characterized by prolongation of the corrected QT (QTc) interval on the surface electrocardiogram. The hallmark phenotypic features are syncope, seizure or sudden death, however most of the mutation carriers are asymptomatic and their risk for arrhythmias such as Torsade de pointes (TdP) are low. We report a case of Long QT syndrome with a corrected QT of 520 ms. For symptom - arrhythmia correlation a loop recorder was implanted with no documented arrhythmias. Epinephrine testing was performed for clinical risk stratification leading to Torsades de pointes during recovery phase which required defibrillation. Genetic testing discovered two pathogenic heterozygous mutations in two different LQT genes (SCN5A and KCNQ1). We propose a calcium homeostasis mechanism for the interaction of both mutations that exaggerated the phenotype, while each mutation by itself is causing a relatively modest phenotype.

  14. [Acquired long QT syndrome and cardiac arrest after general anesthesia. Case report and review of literature].

    PubMed

    Leclercq, T; Parrel, S; Mierdl, S; Cottin, Y; Girard, C

    2014-06-01

    A 30-year-old woman, with no medical history, is operated on for breast implants. In recovery room, an episode of torsade de pointes occurs, progressing to ventricular fibrillation. The ECG after cardiopulmonary resuscitation and conversion to a normal sinus rhythm shows a corrected QT interval prolongation, whereas it is normalized after 48hours. We hypothesize that a ventricular fibrillation occurred after a torsade de pointes, due to drug-induced long QT syndrome during general anesthesia, with probably drug interaction.

  15. Evidence of genetic heterogeneity in the long QT syndrome

    SciTech Connect

    Keating, M. )

    1993-06-25

    thee long QT syndrome (LQT) is a familial predisposition to sudden death from cardiac arrhythmias. M. Keating et al. performed linkage analysis in a large Utah family and found that th disease was closely linked to the Harvey ras-1 (H-ras-1) locus on chromosome 11. With the use of the probe pTBB-2 at the H-ras-1 oncogene, a logarithm of the likelihood ratio for linkage (lod score) of +16.44 was obtained by Keating et al. In a subsequent study, tight linkage of LQT to the H-ras-1 locus was found in six other small LQT families. The combined lod score from these two studies was +21.65 at a recombination fraction of 0. This tight linkage suggests that mutations at the H-ras-1 locus or at a closely linked locus resulted in LQT in the families studied. In view of the clinical heterogeneity and possible genetic heterogeneity in this syndrome, we analyzed a large Jewish family with a history of LQT. This family, whose origin is the island of Jerba near Tunic and whose members reside in Israel, is probably the largest family with LQT outside the United States. It comprises 131 individuals, of whom 28 have been affected. Clinical and electrocardiographic data collected over 7 years were available for 92 family members and blood samples for genetic analysis were available for 74. This analysis, together with that of Keating et al., provides evidence for genetic heterogeneity in the determination of the LQT.

  16. Increased QT dispersion during hypoglycaemia in patients with type 2 diabetes mellitus.

    PubMed

    Landstedt-Hallin, L; Englund, A; Adamson, U; Lins, P E

    1999-09-01

    To study effects of insulin-induced hypoglycaemia on the cardiac repolarization, using QT interval measurements, in patients with type 2 diabetes. Hypoglycaemia was induced by an i.v. insulin-infusion and blood glucose was clamped at 2.7 mmol L-1 for 60 min (T = 90-150 min) in two experiments, with (+GLIB) and without (-GLIB) glibenclamide. In a third experiment, with similar hyperinsulinaemia, glucose was clamped at a euglycaemic level (;5 mmol L-1). ECG was continuously recorded for arrhythmia-monitoring, and 12-lead ECGs were recorded at T = 0 and 150 min. QT intervals were measured, and we determined QT dispersion (difference between the maximum and the minimum QT interval) reflecting interlead variability of repolarization. Thirteen patients with type 2 diabetes, on combined insulin and glibenclamide treatment, were studied during hypoglycaemia, and eight of them participated in the euglycaemic experiment. No significant arrhythmias were seen during hypoglycaemia but the mean QT intervals and QT dispersion increased significantly (P < 0.001), with no differences between -GLIB and +GLIB. During the euglycaemic clamp all QT measurements remained unchanged. Serum potassium decreased significantly (P < 0.001) during all three clamps, but the decrease was more pronounced during hypoglycaemia. The change in potassium was not correlated to the degree of QT prolongation or QT dispersion. Significant changes in the repolarization of the heart can be seen during hypoglycaemia in patients with type 2 diabetes, indicating an increased risk of arrhythmia at low blood glucose levels.

  17. Genotype Positive Long QT Syndrome in Patients With Coexisting Congenital Heart Disease.

    PubMed

    Ebrahim, Mohammed A; Williams, Matthew R; Shepard, Suzanne; Perry, James C

    2017-07-15

    Congenital long QT syndrome (LQTS) is characterized by QT prolongation with predisposition to life-threatening arrhythmia. There have been sporadic reports of LQTS coexisting with more common forms of congenital heart disease (CHD). However, the diagnosis of LQTS when CHD is present may be confounded by several common variables including postoperative electromechanical factors predisposing to ventricular arrhythmia, intrinsic, and postoperative QRS abnormalities. This report documents a single-center experience with patients who have both genetically confirmed LQTS and CHD to examine their modes of presentation and factors associated with making the diagnosis of LQTS in this patient population, as well as potential confounding variables that may mask or delay both LQTS diagnosis and initiation of therapy. A retrospective review was performed of subjects with confirmed LQTS and associated CHD from 1999 to January 2017. Genetic analysis was performed predominantly using commercially available panel testing. A chart review included detailed analysis of electrocardiograms, 24-hour 3-lead rhythm monitors and exercise stress test tracings as well as the genetic test reports. QT intervals were measured using Bazett's formula. Eleven patients were identified. Four patients had LQTS type 1, 6 had LQTS type 2, and 1 had a disease-associated mutation in KCNQ1 and a variant of unknown significance in KCNH2 gene. Two patients had positive cascade screening. Arrhythmia presentations of the LQTS were at both extremes of the cohort age range (in-utero and midchildhood age). There was a seeming overrepresentation of conotruncal anomalies and/or arch anomalies, with 7 of the 11 patients. In conclusion, the diagnosis of LQTS may be challenging in the setting of CHD (a prolonged ST segment may be helpful), and high index of suspicion is required. The overall incidence of LQTS in CHD appears extremely rare, but the diagnosis and true incidence may be masked by confounding

  18. Transmural dispersion of repolarization and arrhythmogenicity: the Brugada syndrome versus the long QT syndrome.

    PubMed

    Antzelevitch, C; Yan, G X; Shimizu, W

    1999-01-01

    Recent studies have shown that ventricular myocardium is composed of at least 3 electrophysiologically distinct cell types: epicardial, endocardial, and M cells. Action potentials recorded from epicardial and M cells, unlike those recorded from endocardium, display a spike-and-dome morphology, the result of a prominent transient outward current-mediated phase 1. M cells are distinguished from endocardial and epicardial cells by the ability of their action potential to prolong disproportionately in response to a slowing of rate and/or to agents with class III actions. This intrinsic electrical heterogeneity contributes to the inscription of the electrocardiogram as well as to the development of a variety of cardiac arrhythmias. The transmural dispersion of repolarization is in large part responsible for the inscription of the J wave and T wave of the electrocardiogram. Because full repolarization of epicardium defines the peak of the T wave and that of the M cells, the end of the T wave, the interval between the peak and the end of the T wave provides a valuable index of transmural dispersion of repolarization. Differences in the response of the 3 cell types to pharmacologic agents and/or pathophysiological states often results in amplification of intrinsic electrical heterogeneities, thus providing a substrate as well as a trigger for the development of reentrant arrhythmias, including torsade de pointes (TdP) commonly associated with the long QT syndrome (LQTS) and the polymorphic ventricular tachycardia/fibrillation encountered in patients with the Brugada syndrome. Early repolarization of the epicardial action potential results in abnormal abbreviation of action potential duration due to an all-or-none repolarization at the end of phase 1 of the epicardial action potential. The loss of the action potential dome in epicardium but not endocardium gives rise to a large dispersion of repolarization across the ventricular wall, resulting in a transmural voltage

  19. The KCNH2-IVS9-28A/G mutation causes aberrant isoform expression and hERG trafficking defect in cardiomyocytes derived from patients affected by Long QT Syndrome type 2.

    PubMed

    Mura, Manuela; Mehta, Ashish; Ramachandra, Chrishan J; Zappatore, Rita; Pisano, Federica; Ciuffreda, Maria Chiara; Barbaccia, Vincenzo; Crotti, Lia; Schwartz, Peter J; Shim, Winston; Gnecchi, Massimiliano

    2017-08-01

    Long QT Syndrome type 2 (LQT2) is caused by mutations in the KCNH2 gene that encodes for the α-subunit (hERG) of the ion channel conducting the rapid delayed rectifier potassium current (IKr). We have previously identified a disease causing mutation (IVS9-28A/G) in the branch point of the splicing of KCNH2 intron 9. However, the mechanism through which this mutation causes the disease is unknown. We generated human induced pluripotent stem cell-derived cardiomyocytes (iPSC-CMs) from fibroblasts of two IVS9-28A/G mutation carriers. IVS9-28A/G iPSC-CMs showed prolonged repolarization time, mimicking what observed at the ECG level in the same patients. The expression of the full-length ERG1a isoform resulted reduced, whereas the C-terminally truncated ERG1aUSO isoform was upregulated in mutant iPSC-CMs, with consequent alteration of the physiological ERG1aUSO/ERG1a ratio. Importantly, we observed an impairment of hERG trafficking to the cell membrane. The severity of the alterations in hERG expression and trafficking correlated with the clinical severity of the disease in the two patients under study. Finally, we were able to revert the trafficking defect and reduce the repolarization duration in LQT2 iPSC-CMs using the proteasome inhibitor ALLN. Our results highlight the key role of the KCNH2 intron 9 branch point in the regulation of KCNH2 isoform expression and hERG channel function, and allow to categorize the IVS9-28A/G mutation as LQT2 class 2 mutation. These findings may result in a more personalized clinical management of IVS9-28A/G mutation carriers. Copyright © 2017 Elsevier B.V. All rights reserved.

  20. Factors influencing uptake of familial long QT syndrome genetic testing.

    PubMed

    Burns, Charlotte; McGaughran, Julie; Davis, Andrew; Semsarian, Christopher; Ingles, Jodie

    2016-02-01

    Ongoing challenges of clinical assessment of long QT syndrome (LQTS) highlight the importance of genetic testing in the diagnosis of asymptomatic at-risk family members. Effective access, uptake, and communication of genetic testing are critical for comprehensive cascade family screening and prevention of disease complications such as sudden cardiac death. The aim of this study was to describe factors influencing uptake of LQTS genetic testing, including those relating to access and family communication. We show those who access genetic testing are overrepresented by the socioeconomically advantaged, and that although overall family communication is good, there are some important barriers to be addressed. There were 75 participants (aged 18 years or more, with a clinical and/or genetic diagnosis of LQTS; response rate 71%) who completed a survey including a number of validated scales; demographics; and questions about access, uptake, and communication. Mean age of participants was 46 ± 16 years, 20 (27%) were males and 60 (80%) had genetic testing with a causative gene mutation in 42 (70%). Overall uptake of cascade testing within families was 60% after 4 years from proband genetic diagnosis. All participants reported at least one first-degree relative had been informed of their risk, whereas six (10%) reported at least one first-degree relative had not been informed. Those who were anxious or depressed were more likely to perceive barriers to communicating. Genetic testing is a key aspect of care in LQTS families and intervention strategies that aim to improve equity in access and facilitate effective family communication are needed.

  1. Sports Participation in Genotype Positive Children With Long QT Syndrome

    PubMed Central

    Aziz, Peter F.; Sweeten, Tammy; Vogel, Ramon L.; Bonney, William J.; Henderson, Jacqueline; Patel, Akash R.; Shah, Maully J.

    2015-01-01

    OBJECTIVE The study sought to examine the prevalence and outcomes of sports participation (both competitive and recreational) in our single-center LQTS genotype positive pediatric population. BACKGROUND The risks of sports participation in patients with long QT syndrome (LQTS) are not clearly elucidated. METHODS A retrospective review was performed on genotype positive patients referred for the evaluation and management of LQTS between 1998 and 2013 at the Children’s Hospital of Philadelphia. Pediatric patients participating in competitive or recreational sports were included in the analysis and their charts were reviewed for documented LQTS events during follow-up. RESULTS The cohort of genotype-positive LQTS patients included 212 patients, and 103 patients (49%, female n = 53, average follow-up 7.1 ± 4.0 years, average QTc 468 ± 42 ms) participated in sports. A total of 105 LQTS disease-causing mutations were identified: KCNQ1 n = 60 (58%), KCNH2 n = 36 (35%), SCN5A n = 6 (6%), KCNE1 n = 1 (1%), and KCNE2 n = 2 (2%). All patients were treated with beta-blockade, with noncompliance in 1 patient and intolerance in 1 patient. Twenty-six patients participated in competitive sports (26%, female n = 15, average follow-up 6.9 ± 4.1 years, average QTc 461 ± 35 ms). Seventy-seven patients (75%, female n = 35, average follow-up 7.3 ± 3.9 years, average QTc 470 ± 43 ms) participated in recreational sports. No patients had LQTS symptoms during sports participation. Five appropriate implantable cardioverter-defibrillator shocks occurred in 2 patients, though none were related to sports participation. CONCLUSIONS In this series no cardiac events and no deaths were observed in treatment-compliant LQTS children while participating in sports in 755 patient-years of follow-up. PMID:26301263

  2. In Utero Diagnosis of Long QT Syndrome by Magnetocardiography

    PubMed Central

    Cuneo, Bettina F.; Strasburger, Janette F.; Yu, Suhong; Horigome, Hitoshi; Hosono, Takayoshi; Kandori, Akihiko; Wakai, Ronald T.

    2013-01-01

    Background The electrophysiology of long QT syndrome (LQTS) in utero is virtually unstudied. Our goal here was to evaluate the efficacy of fetal magnetocardiography (fMCG) for diagnosis and prognosis of fetuses at risk of LQTS. Methods and Results We reviewed the pre/postnatal medical records of 30 fetuses referred for fMCG due to a family history of LQTS (n=17); neonatal/childhood sudden cardiac death (n=3) and/or presentation of prenatal LQTS rhythms (n=12): 2° AVB, ventricular tachycardia, heart rate < 3rd percentile. We evaluated heart rate and reactivity, cardiac time intervals, T-wave characteristics, and initiation/termination of Torsade de Pointes (TdP), and compared these with neonatal ECG findings. After birth, subjects were tested for LQTS mutations. Based on accepted clinical criteria, 21 subjects (70%; 9 KCNQ1, 5 KCNH2, 2 SCN5A, 2 other, 3 untested) had LQTS. Using a threshold of QTc= 490 ms, fMCG accurately identified LQTS fetuses with 89% (24/27) sensitivity and 89% (8/9) specificity in 36 sessions. Four fetuses (2 KCNH2 and 2 SCN5A), all with QTc ≥ 620 ms, had frequent episodes of TdP, which were present 22–79% of the time. While some episodes initiated with a long-short sequence, most initiations showed QRS aberrancy and a notable lack of pause dependency. T-wave alternans was strongly associated with severe LQTS phenotype. Conclusions QTc prolongation (≥490 ms) assessed by fMCG accurately identified LQTS in utero; extreme QTc prolongation (≥620 ms) predicted TdP. FMCG can play a critical role in the diagnosis and management of fetuses at risk of LQTS. PMID:24218437

  3. Holter monitoring in the evaluation of congenital long QT syndrome.

    PubMed

    Mauriello, Daniel A; Johnson, Jonathan N; Ackerman, Michael J

    2011-09-01

    Long QT syndrome (LQTS) is a potentially lethal cardiac channelopathy that affects one in 2,000 persons; causes syncope, seizures, and sudden death; and is both under- and overdiagnosed. LQTS diagnostic miscues have stemmed from assessment of ambulatory electrocardiographic monitoring (Holter) results. We sought to determine the prevalence of positive Holter monitor tests and its diagnostic significance in evaluating LQTS. We performed an institutional review board-approved review of patients evaluated in our LQTS clinic from 2000 to 2009 who had Holter testing during their evaluation. Included patients (N = 473) were diagnosed with LQTS or dismissed as otherwise normal. Holters classified as positive had an episode of nonsustained ventricular tachycardia, supraventricular tachycardia, ≥4 couplets/day, ≥10 premature ventricular contractions/hour, or >5-second sinus pause. Among 209 patients dismissed as normal (128 females, average age 21 ± 15 years, average QTc 424 ± 39 ms), 27 (12.9%) had a positive Holter, while among 264 patients with LQTS (149 females, average age 22 ± 16 years, average QTc 472 ± 41 ms), 30 (11.3%) had a positive Holter (P = NS). Patients with LQT3 (5/23, 21%) and genotype-negative LQTS (5/19, 26%) had a higher rate of positive Holter testing compared to LQT1 patients (7/124, 6%, P < 0.03). Among the 473 Holters, only one (0.2%) impacted clinical decision making. Routine Holter monitoring appears to be of minimal clinical utility from a diagnostic and prognostic perspective in evaluating LQTS, and may not be cost effective. Whether Holter monitoring aids in therapeutic decisions such as dosing or whether ambulatory QTc measurements, provided by some newer devices, might help in the diagnostic evaluation warrants further scrutiny. ©2011, The Authors. Journal compilation ©2011 Wiley Periodicals, Inc.

  4. Must every child with long QT syndrome take a beta blocker?

    PubMed

    Waddell-Smith, Kathryn E; Earle, Nikki; Skinner, Jonathan R

    2015-03-01

    Long QT syndrome is the most commonly recognised cause of sudden cardiac death in children. With a prevalence of 1 in 2000, family screening is identifying large numbers of hitherto asymptomatic gene carriers in the community, about a third of whom have a normal QT interval. The mainstay of treatment is long term uninterrupted beta blocker therapy, a treatment with many potential side effects. This article reviews the evidence and suggests a cohort who may, after assessment in a specialised cardiac-genetic clinic, be spared this treatment because of very low baseline risk. These are asymptomatic boys and prepubertal girls with a heart rate corrected QT interval persistently less than 470 ms who do not indulge in high risk activities (especially swimming) and do not have a missense mutation in the c-loop region of the KCNQ1 (long QT 1) gene.

  5. QT Interval Derived Measurements in Patients with Cardiac Syndrome X Compared to Coronary Artery Disease.

    PubMed

    Lutfi, Mohamed F

    2016-01-01

    Previous studies assessing effect of ischemia on ventricular repolarization are mostly directed toward patients with coronary artery disease (CAD); however, similar reports on cardiac syndrome X (CSX) are scarce. Whether microvascular dysfunction of CSX and ischemia induced by CAD produce comparable effect on ventricular repolarization is unclear and deserve further studies. In the present study, ECG measures of ventricular repolarization were compared between CAD and CSX patients (40 subjects in each group). Following evaluation of sociodemographic characteristics, medical and past medical history, a resting ECG was used to assess measurements of ventricular repolarization in each patient, namely, QT interval (QT), corrected QT interval (QTc), QT dispersion (QTd), corrected QT dispersion (QTcd), adjacent QT dispersion (AdQTd), QT dispersion ratio (QTdR), JT dispersion (JTd), and Corrected JT dispersion (JTcd). Results showed comparable QT intervals and QTd in CAD and CSX patients even after adjustment for the possible variations in gender, age and body mass index of the studied groups. Although JTd was increased in CSX subjects (26.6 ± 7.2 ms) compared with CAD patients (22.7 ± 6.5 ms, p = 0.019), statistical significance disappeared after correcting JT for variations in heart rate. QT and QTc were significantly below 440 ms in CAD as well as CSX patients (p < 0.001). In contrast, maximum QTd, maximum QTcd and AdQTd of CAD and CSX patients were significantly above 440 ms (p < 0.001). The means of JTd and JTcd were significantly above 22 ms and 24 ms respectively (p < 0.001, p = 0.001) in CSX but not CAD patients (p = 0.529, p = 0.281). The present findings clearly demonstrate comparable measures of ventricular repolarization in CAD and CSX patients and consequently an equal risk of cardiac events in both groups.

  6. Treating an Adolescent with Long QT Syndrome for Bipolar Disorder: A Case Presentation

    PubMed Central

    Önen, Özlem; Kutlu, Ayşe; Erkuran, Handan Özek

    2017-01-01

    Objectives Long QT syndrome (LQTS) is described as the development of sudden syncope attacks or death as a result of ventricular tachycardia (VT) episodes that might be observed as elongated QT interval in electrocardiography (ECG). Implantable Cardioverter Defibrillator (ICD) is recommended as first-line treatment for the condition in guidelines. We aimed to present an adolescent recently diagnosed with Bipolar Disorder (BD) who had LQTS that was treated with ICD, discussing her follow up and treatment along with relevant literature. Methods Psychiatric assessment of the case that applied to our child psychiatry unit due to manic symptoms were carried out by using Diagnostic and Statistical Manual of Mental Disorders 5th edition (DSM-5) criteria. Symptom severity was monitored via Young Mania Rating Scale scores (YMRSS). Results The case met criteria for Bipolar Disorder Type I (BD-I). She had improvement in her mood symptoms with treatment regimen as risperidone 3 mg/day, valproate 1000 mg/day and lorazepam 1 mg/dayi after her 2–week follow up as well as no reported ICD activity, reflecting fine cardiac functions and rhythm. Conclusions LQTS is a serious health issue for children and adolescents diagnosed with BD. This condition should be kept in mind especially in cases where familial risk factors are present and precautions need to be maintained upon required assessments. These cases need to be closely monitored due to risk factors related to both BD and LQTS, in a multidisciplinary fashion, involving both psychiatry and cardiology divisions. PMID:28138202

  7. The impact of recent advances in genetics in understanding disease mechanisms underlying the long QT syndromes.

    PubMed

    Harmer, Stephen C; Tinker, Andrew

    2016-07-01

    Long QT syndrome refers to a characteristic abnormality of the electrocardiogram and it is associated with a form of ventricular tachycardia known as torsade-de-pointes and sudden arrhythmic death. It can occur as part of a hereditary syndrome or can be acquired usually because of drug administration. Here we review recent genetic, molecular and cellular discoveries and outline how they have furthered our understanding of this disease. Specifically we focus on compound mutations, genome wide association studies of QT interval, modifier genes and the therapeutic implications of this recent work.

  8. Sex differences in the mechanisms underlying long QT syndrome.

    PubMed

    Salama, Guy; Bett, Glenna C L

    2014-09-01

    Sexual dimorphism is a well-established phenomenon, but its degree varies tremendously among species. Since the early days of Einthoven's development of the three-lead galvanometer ECG, we have known there are marked differences in QT intervals of men and women. It required over a century to appreciate the profound implications of sex-based electrophysiological differences in QT interval on the panoply of sex differences with respect to arrhythmia risk, drug sensitivity, and treatment modalities. Little is known about the fundamental mechanism responsible for sex differences in electrical substrate of the human heart, in large part due to the lack of tissue availability. Animal models are an important research tool, but species differences in the sexual dimorphism of the QT interval, the ionic currents underlying the cardiac repolarization, and effects of sex steroids make it difficult to interpolate animal to human sex differences. In addition, in some species, different strains of the same animal model yield conflicting data. Each model has its strengths, such as ease of genetic manipulation in mice or size in dogs. However, many animals do not reproduce the sexual dimorphism of QT seen in humans. To match sex linked prolongation of QT interval and arrhythmogenic phenotype, the current data suggest that the rabbit may be best suited to provide insight into sex differences in humans. In the future, emerging technologies such as induced pluripotent stem cell derived cardiac myocyte systems may offer the opportunity to study sex differences in a controlled hormonal situation in the context of a sex specific human model system. Copyright © 2014 the American Physiological Society.

  9. [Long QT syndrome and Brugada syndrome: 2 aspects of the same disease?].

    PubMed

    Cerrone, M; Crotti, L; Faggiano, G; De Michelis, V; Napolitano, C; Schwartz, P J; Priori, S G

    2001-03-01

    In clinical cardiology, resort has recently been made to molecular genetics in order to explain some mechanisms that underlie sudden cardiac death in young people with structurally normal hearts. It has become evident that genetic mutations regarding cardiac ion channels may disrupt the delicate balance of currents in the action potential, thus inducing malignant ventricular tachyarrhythmias. The cardiac sodium channel gene, SCN5A, is involved in two of such arrhythmogenic diseases, the Brugada syndrome and one form of the long QT syndrome (LQT3). It is believed that these syndromes result from opposite molecular effects: Brugada syndrome mutations cause a reduced sodium current, while LQT3 mutations are associated with a gain of function. The effects of class I antiarrhythmic drugs have been used to differentiate these diseases. Intravenous flecainide is used as a highly specific test to unmask the electrocardiographic phenotype of the Brugada syndrome. On the other hand, on the basis of experimental and clinical studies, the possibility that the same drugs act as a gene-specific therapy in this disorder by contrasting the effect of mutations in LQT3 has been explored. Recent evidence shows that phenotypic overlap may exist between the Brugada syndrome and LQT3. One large family with a SCN5A mutation and a "mixed" electrocardiographic pattern (prolonged QT interval and ST-segment elevation) has been reported. Moreover, our recent data showed that flecainide challenge may elicit ST-segment elevation in some LQT3 patients. The presence of "intermediate" phenotypes highlights a remarkable heterogeneity suggesting that clinical features may depend upon the single mutation. Only deepened understanding of the genotype-phenotype correlation will allow the definition of the individual patient's risk and the development of guidelines for clinical management.

  10. Prevalence and risk factors for prolonged QT interval and QT dispersion in patients with type 2 diabetes.

    PubMed

    Ninkovic, Vladan M; Ninkovic, Srdjan M; Miloradovic, Vanja; Stanojevic, Dejan; Babic, Marijana; Giga, Vojislav; Dobric, Milan; Trenell, Michael I; Lalic, Nebojsa; Seferovic, Petar M; Jakovljevic, Djordje G

    2016-10-01

    Prolonged QT interval is associated with cardiac arrhythmias and sudden death. The present study determined the prevalence of prolonged QT interval and QT dispersion and defined their clinical and metabolic predictors in patients with type 2 diabetes. Cross-sectional study included 501 patients with type 2 diabetes. A standard 12-lead electrocardiogram was recorded. QT corrected for heart rate (QTc) >440 ms and QT dispersion (QTd) >80 ms were considered abnormally prolonged. QTc ≥ 500 ms was considered a high-risk QTc prolongation. Demographic, clinical and laboratory data were collected. Independent risk factors for prolonged QTc and QTd were assessed using logistic regression analysis. Prevalence of QTc > 440 ms and QTd > 80 ms were 44.1 and 3.6 %, respectively. Prevalence of high-risk QTc (≥500 ms) was 2 % only. Independent risk factors for QTc prolongation >440 ms were mean blood glucose (β = 2.192, p < 0.001), treatment with sulphonylurea (β = 5.198, p = 0.027), female gender (β = 8.844, p < 0.001), and coronary heart disease (β = 8.636, p = 0.001). Independent risk factors for QTc ≥ 500 ms were coronary heart disease (β = 4.134, p < 0.001) and mean blood glucose level (β = 1.735, p < 0.001). The independent risk factor for prolonged QTd was only coronary heart disease (β = 5.354, p < 0.001). Although the prevalence of prolonged QTc > 440 ms is significant, the prevalence of high-risk QTc (≥500 ms) and QTd > 80 ms is very low in patients with type 2 diabetes. Hyperglycaemia and coronary heart disease are strong predictors of high-risk QTc.

  11. Long QT interval in Turner syndrome--a high prevalence of LQTS gene mutations.

    PubMed

    Trolle, Christian; Mortensen, Kristian H; Pedersen, Lisbeth N; Berglund, Agnethe; Jensen, Henrik K; Andersen, Niels H; Gravholt, Claus H

    2013-01-01

    QT-interval prolongation of unknown aetiology is common in Turner syndrome. This study set out to explore the presence of known long QT mutations in Turner syndrome and to examine the corrected QT-interval (QTc) over time and relate the findings to the Turner syndrome phenotype. Adult women with Turner syndrome (n = 88) were examined thrice and 68 age-matched healthy controls were examined once. QTc was measured by one blinded reader (intra-reader variability: 0.7%), and adjusted for influence of heart rate by Bazett's (bQTc) and Hodges's formula (hQTc). The prevalence of mutations in genes related to Long QT syndrome was determined in women with Turner syndrome and a QTc >432.0 milliseconds (ms). Echocardiographic assessment of aortic valve morphology, 24-hour blood pressures and blood samples were done. The mean hQTc in women with Turner syndrome (414.0 ± 25.5 ms) compared to controls (390.4 ± 17.8 ms) was prolonged (p<0.001) and did not change over time (416.9 ± 22.6 vs. 415.6 ± 25.5 ms; p =0.4). 45,X karyotype was associated with increased hQTc prolongation compared to other Turner syndrome karyotypes (418.2 ± 24.8 vs. 407.6 ± 25.5 ms; p = 0.055). In women with Turner syndrome and a bQTc >432 ms, 7 had mutations in major Long QT syndrome genes (SCN5A and KCNH2) and one in a minor Long QT syndrome gene (KCNE2). There is a high prevalence of mutations in the major LQTS genes in women with TS and prolonged QTc. It remains to be settled, whether these findings are related to the unexplained excess mortality in Turner women. NCT00624949. https://register.clinicaltrials.gov/prs/app/action/SelectProtocol/sid/S0001FLI/selectaction/View/ts/3/uid/U000099E.

  12. The phenomenon of “QT stunning”: The abnormal QT prolongation provoked by standing persists even as the heart rate returns to normal in patients with long QT syndrome

    PubMed Central

    Adler, Arnon; van der Werf, Christian; Postema, Pieter G.; Rosso, Raphael; Bhuiyan, Zahir A.; Kalman, Jonathan M.; Vohra, Jitendra K.; Guevara-Valdivia, Milton E.; Marquez, Manlio F.; Halkin, Amir; Benhorin, Jesaia; Antzelevitch, Charles; Wilde, Arthur A.M.; Viskin, Sami

    2012-01-01

    BACKGROUND Patients with long QT syndrome (LQTS) have inadequate shortening of the QT interval in response to the sudden heart rate accelerations provoked by standing—a phenomenon of diagnostic value. We now validate our original observations in a cohort twice as large. We also describe that this abnormal QT-interval response persists as the heart rate acceleration returns to baseline. OBJECTIVES To describe a novel observation, termed “QT stunning” and to validate previous observations regarding the “QT-stretching” phenomenon in patients with LQTS by using our recently described “standing test.” METHODS The electrocardiograms of 108 patients with LQTS and 112 healthy subjects were recorded in the supine position. Subjects were then instructed to stand up quickly and remain standing for 5 minutes during continuous electrocardiographic recording. The corrected QT interval was measured at baseline (QTcbase), when heart rate acceleration without appropriate QT-interval shortening leads to maximal QT stretching (QTcstretch) and upon return of heart rate to baseline (QTcreturn). RESULTS QTcstretch lengthened significantly more in patients with LQTS (103 ± 80 ms vs 66 ± 40 ms in controls; P <.001) and so did QTcreturn (28 ± 48 ms for patients with LQTS vs −3 ± 32 ms for controls; P <.001). Using a sensitivity cutoff of 90%, the specificity for diagnosing LQTS was 74% for QTcbase, 84% for QTcreturn, and 87% for QTcstretch. CONCLUSIONS The present study extends our previous findings on the abnormal response of the QT interval in response to standing in patients with LQTS. Our study also shows that this abnormal response persists even after the heart rate slows back to baseline. PMID:22300664

  13. Ankyrin-B mutation causes type 4 long-QT cardiac arrhythmia and sudden cardiac death.

    PubMed

    Mohler, Peter J; Schott, Jean-Jacques; Gramolini, Anthony O; Dilly, Keith W; Guatimosim, Silvia; duBell, William H; Song, Long-Sheng; Haurogné, Karine; Kyndt, Florence; Ali, Mervat E; Rogers, Terry B; Lederer, W J; Escande, Denis; Le Marec, Herve; Bennett, Vann

    2003-02-06

    Mutations in ion channels involved in the generation and termination of action potentials constitute a family of molecular defects that underlie fatal cardiac arrhythmias in inherited long-QT syndrome. We report here that a loss-of-function (E1425G) mutation in ankyrin-B (also known as ankyrin 2), a member of a family of versatile membrane adapters, causes dominantly inherited type 4 long-QT cardiac arrhythmia in humans. Mice heterozygous for a null mutation in ankyrin-B are haploinsufficient and display arrhythmia similar to humans. Mutation of ankyrin-B results in disruption in the cellular organization of the sodium pump, the sodium/calcium exchanger, and inositol-1,4,5-trisphosphate receptors (all ankyrin-B-binding proteins), which reduces the targeting of these proteins to the transverse tubules as well as reducing overall protein level. Ankyrin-B mutation also leads to altered Ca2+ signalling in adult cardiomyocytes that results in extrasystoles, and provides a rationale for the arrhythmia. Thus, we identify a new mechanism for cardiac arrhythmia due to abnormal coordination of multiple functionally related ion channels and transporters.

  14. Identification of Concealed and Manifest Long QT Syndrome Using a Novel T Wave Analysis Program.

    PubMed

    Sugrue, Alan; Noseworthy, Peter A; Kremen, Vaclav; Bos, J Martijn; Qiang, Bo; Rohatgi, Ram K; Sapir, Yehu; Attia, Zachi I; Brady, Peter; Asirvatham, Samuel J; Friedman, Paul A; Ackerman, Michael J

    2016-07-01

    Congenital long QT syndrome (LQTS) is characterized by QT prolongation. However, the QT interval itself is insufficient for diagnosis, unless the corrected QT interval is repeatedly ≥500 ms without an acquired explanation. Further, the majority of LQTS patients have a corrected QT interval below this threshold, and a significant minority has normal resting corrected QT interval values. Here, we aimed to develop and validate a novel, quantitative T wave morphological analysis program to differentiate LQTS patients from healthy controls. We analyzed a genotyped cohort of 420 patients (22±16 years, 43% male) with either LQT1 (61%) or LQT2 (39%). ECG analysis was conducted using a novel, proprietary T wave analysis program that quantitates subtle changes in T wave morphology. The top 3 discriminating features in each ECG lead were determined and the lead with the best discrimination selected. Classification was performed using a linear discriminant classifier and validated on an untouched cohort. The top 3 features were Tpeak-Tend interval, T wave left slope, and T wave center of gravity x axis (last 25% of the T wave). Lead V6 had the best discrimination. It could distinguish 86.8% of LQTS patients from healthy controls. Moreover, it distinguished 83.33% of patients with concealed LQTS from controls, despite having essentially identical resting corrected QT interval values. T wave quantitative analysis on the 12-lead surface ECG provides an effective, novel tool to distinguish patients with either LQT1/LQT2 from healthy matched controls. It can provide guidance while mutation-specific genetic testing is in motion for family members. © 2016 American Heart Association, Inc.

  15. High prevalence of four long QT syndrome founder mutations in the Finnish population

    PubMed Central

    MARJAMAA, ANNUKKA; SALOMAA, VEIKKO; NEWTON-CHEH, CHRISTOPHER; PORTHAN, KIMMO; REUNANEN, ANTTI; KARANKO, HANNU; JULA, ANTTI; LAHERMO, PÄIVI; VÄÄNÄNEN, HEIKKI; TOIVONEN, LAURI; SWAN, HEIKKI; VIITASALO, MATTI; NIEMINEN, MARKKU S.; PELTONEN, LEENA; OIKARINEN, LASSE; PALOTIE, AARNO; KONTULA, KIMMO

    2009-01-01

    Aims Long QT syndrome (LQTS) is an inherited arrhythmia disorder with an estimated prevalence of 0.01%–0.05%. In Finland, four founder mutations constitute up to 70% of the known genetic spectrum of LQTS. In the present survey, we sought to estimate the actual prevalence of the founder mutations and to determine their effect sizes in the general Finnish population. Methods and results We genotyped 6334 subjects aged≥30 years from a population cohort (Health 2000 study) for the four Finnish founder mutations using Sequenom MALDI-TOF mass spectrometry. The electrocardiogram (ECG) parameters were measured from digital 12-lead ECGs, and QT intervals were adjusted for age, sex, and heart rate using linear regression. A total of 27 individuals carried one of the founder mutations resulting in their collective prevalence estimate of 0.4% (95% CI 0.3%–0.6%). The KCNQ1 G589D mutation (n=8) was associated with a 50 ms (SE 7.0) prolongation of the adjusted QT interval (P=9.0×10-13). The KCNH2 R176W variant (n=16) resulted in a 22 ms (SE 4.7) longer adjusted QT interval (P=2.1×10-6). Conclusion In Finland 1 individual out of 250 carries a LQTS founder mutation, which is the highest documented prevalence of LQTS mutations that lead to a marked QT prolongation. PMID:19160088

  16. QT correction formulas and laboratory analysis on patients with metabolic syndrome and diabetes

    NASA Astrophysics Data System (ADS)

    Wong, Sara; Rivera, Pedro; Rodríguez, María. G.; Severeyn, Érika; Altuve, Miguel

    2013-11-01

    This article presents a study of ventricular repolarization in diabetic and metabolic syndrome subjects. The corrected QT interval (QTc) was estimated using four correction formulas commonly employed in the literature: Bazett, Fridericia, Framingham and Hodges. After extracting the Q, R and T waves from the electrocardiogram of 52 subjects (19 diabetic, 15 with metabolic syndrome and 18 control), using a wavelet-based approach, the RR interval and QT interval were determined. Then, QTc interval was computed using the formulas previously mentioned. Additionally, laboratory test (fasting glucose, cholesterol, triglycerides) were also evaluated. Results show that metabolic syndrome subjects have normal QTc. However, a longer QTc in this population may be a sign of future complication. The corrected QT interval by Fridericia's formula seems to be the most appropriated for metabolic syndrome subjects (low correlation coefficient between RR and QTc). Significant differences were obtained in the blood glucose and triglyceride levels, principally due to the abnormal sugar metabolization of metabolic syndrome and diabetic subjects. Further studies are focused on the acquisition of a larger database of metabolic syndrome and diabetics subjects and the repetition of this study using other populations, like high performance athletes.

  17. Peripartum cardiomyopathy presenting with syncope due to Torsades de pointes: a case of long QT syndrome with a novel KCNH2 mutation.

    PubMed

    Nishimoto, Orie; Matsuda, Morihiro; Nakamoto, Kei; Nishiyama, Hirohiko; Kuraoka, Kazuya; Taniyama, Kiyomi; Tamura, Ritsu; Shimizu, Wataru; Kawamoto, Toshiharu

    2012-01-01

    Peripartum cardiomyopathy (PPCM) is a cardiomyopathy of unknown cause that occurs in the peripartum period. We report a case of PPCM presenting with syncope 1 month after an uncomplicated delivery. Electrocardiography showed Torsades de pointes (TdP) and QT interval prolongation. Echocardiography showed left ventricular systolic dysfunction and endomyocardial biopsy showed myocyte degeneration and fibrosis. Administration of magnesium sulfate and temporary pacing eliminated recurrent TdP. Genetic analyses revealed that recurrent TdP occurred via electrolyte disturbance and cardiac failure due to PPCM on the basis of a novel mutation in KCNH2, a gene responsible for inherited type 2 long QT syndrome.

  18. Biophysical Properties of 9 KCNQ1 Mutations Associated with Long QT Syndrome (LQTS)

    PubMed Central

    Yang, Tao; Chung, Seo-Kyung; Zhang, Wei; Mullins, Jonathan G.L.; McCulley, Caroline H.; Crawford, Jackie; MacCormick, Judith; Eddy, Carey-Anne; Shelling, Andrew N.; French, John K.; Yang, Ping; Skinner, Jonathan R.; Roden, Dan M.; Rees, Mark I.

    2009-01-01

    Background Inherited long QT syndrome (LQTS) is characterized by prolonged QT interval on the EKG, syncope and sudden death due to ventricular arrhythmia. Causative mutations occur mostly in cardiac potassium and sodium channel subunit genes. Confidence in mutation pathogenicity is usually reached through family genotype-phenotype tracking, control population studies, molecular modelling and phylogenetic alignments, however, biophysical testing offers a higher degree of validating evidence. Methods and Results By using in-vitro electrophysiological testing of transfected mutant and wild-type LQTS constructs into Chinese Hamster Ovary cells, we investigated the biophysical properties of 9 KCNQ1 missense mutations (A46T, T265I, F269S, A302V, G316E, F339S, R360G, H455Y, and S546L) identified in a New Zealand based LQTS screening programme. We demonstrate through electrophysiology and molecular modeling that seven of the missense mutations have profound pathological dominant negative loss-of-function properties confirming their likely disease-causing nature. This supports the use of these mutations in diagnostic family screening. Two mutations (A46T, T265I) show suggestive evidence of pathogenicity within the experimental limits of biophysical testing, indicating that these variants are disease-causing via delayed or fast activation kinetics. Further investigation of the A46T family has revealed an inconsistent co-segregation of the variant with the clinical phenotype. Conclusions Electrophysiological characterisation should be used to validate LQTS pathogenicity of novel missense channelopathies. When such results are inconclusive, great care should be taken with genetic counselling and screening of such families, and alternative disease causing mechanisms should be considered. PMID:19808498

  19. Congenital long QT syndrome with compound mutations in the KCNH2 gene.

    PubMed

    Bando, Sachiko; Soeki, Takeshi; Matsuura, Tomomi; Niki, Toshiyuki; Ise, Takayuki; Yamaguchi, Koji; Taketani, Yoshio; Iwase, Takashi; Yamada, Hirotsugu; Wakatsuki, Tetsuzo; Akaike, Masashi; Aiba, Takeshi; Shimizu, Wataru; Sata, Masataka

    2014-07-01

    Congenital long QT syndrome is a genetic disorder encompassing a family of mutations that can lead to aberrant ventricular electrical activity. We report on two brothers with long QT syndrome caused by compound mutations in the KCNH2 gene inherited from parents who had no prolonged QT interval on electrocardiography. The proband had syncope, and his elder brother suffered from ventricular fibrillation. Genetic testing revealed that both brothers had multiple mutations in the KCNH2 gene, including a missense mutation of C1474T (exon 6) as well as a frameshift/nonsense mutation, resulting from the insertion of 25 nucleotides, which caused an altered amino acid sequence beginning at codon 302 and a premature termination codon (i.e., TAG) at codon 339 (exon 4). Family genetic screening found that their father had the same frameshift mutation, and their mother and sister had the same missense mutation, in the KCNH2 gene. However, these other family members were asymptomatic, with normal QT intervals on electrocardiography. These results suggest that compound mutations in the KCNH2 gene inherited independently from the parents made the phenotypes of their sons more severe.

  20. Mutation of an A-kinase-anchoring protein causes long-QT syndrome

    PubMed Central

    Chen, Lei; Marquardt, Michelle L.; Tester, David J.; Sampson, Kevin J.; Ackerman, Michael J.; Kass, Robert S.

    2007-01-01

    A-kinase anchoring proteins (AKAPs) recruit signaling molecules and present them to downstream targets to achieve efficient spatial and temporal control of their phosphorylation state. In the heart, sympathetic nervous system (SNS) regulation of cardiac action potential duration (APD), mediated by β-adrenergic receptor (βAR) activation, requires assembly of AKAP9 (Yotiao) with the IKs potassium channel α subunit (KCNQ1). KCNQ1 mutations that disrupt this complex cause type 1 long-QT syndrome (LQT1), one of the potentially lethal heritable arrhythmia syndromes. Here, we report identification of (i) regions on Yotiao critical to its binding to KCNQ1 and (ii) a single putative LQTS-causing mutation (S1570L) in AKAP9 (Yotiao) localized to the KCNQ1 binding domain in 1/50 (2%) subjects with a clinically robust phenotype for LQTS but absent in 1,320 reference alleles. The inherited S1570L mutation reduces the interaction between KCNQ1 and Yotiao, reduces the cAMP-induced phosphorylation of the channel, eliminates the functional response of the IKs channel to cAMP, and prolongs the action potential in a computational model of the ventricular cardiocyte. These reconstituted cellular consequences of the inherited S1570L-Yotiao mutation are consistent with delayed repolarization of the ventricular action potential observed in the affected siblings. Thus, we have demonstrated a link between genetic perturbations in AKAP and human disease in general and AKAP9 and LQTS in particular. PMID:18093912

  1. Bifurcation diagrams of frequency dependence of repolarization during long QT syndrome using the Luo-Rudy model of cardiac repolarization

    NASA Astrophysics Data System (ADS)

    Bondarenko, V. E.; Doedel, E. J.; Rasmusson, R. L.

    2000-02-01

    We applied bifurcation analysis to the Luo-Rudy model of the guinea pig cardiac ventricular cell to investigate the behavior of repolarization in response to a simulated form of inherited arrhythmia, long QT syndrome. In this paper, we simulate pathological changes in cardiac repolarization through reductions in IKr. Decreased expression of this current has been linked to an inherited form of long QT syndrome which results in a high mortality, presumably due to sudden cardiac death from ventricular fibrillation.

  2. Modeling Tissue- and Mutation- Specific Electrophysiological Effects in the Long QT Syndrome: Role of the Purkinje Fiber

    PubMed Central

    Iyer, Vivek; Sampson, Kevin J.; Kass, Robert S.

    2014-01-01

    Congenital long QT syndrome is a heritable family of arrhythmias caused by mutations in 13 genes encoding ion channel complex proteins. Mounting evidence has implicated the Purkinje fiber network in the genesis of ventricular arrhythmias. In this study, we explore the hypothesis that long QT mutations can demonstrate different phenotypes depending on the tissue type of expression. Using computational models of the human ventricular myocyte and the Purkinje fiber cell, the biophysical alteration in channel function in LQT1, LQT2, LQT3, and LQT7 are modeled. We identified that the plateau potential was important in LQT1 and LQT2, in which mutation led to minimal action potential prolongation in Purkinje fiber cells. The phenotype of LQT3 mutation was dependent on the biophysical alteration induced as well as tissue type. The canonical ΔKPQ mutation causes severe action potential prolongation in both tissue types. For LQT3 mutation F1473C, characterized by shifted channel availability, a more severe phenotype was seen in Purkinje fiber cells with action potential prolongation and early afterdepolarizations. The LQT3 mutation S1904L demonstrated striking effects on action potential duration restitution and more severe action potential prolongation in Purkinje fiber cells at higher heart rates. Voltage clamp simulations highlight the mechanism of effect of these mutations in different tissue types, and impact of drug therapy is explored. We conclude that arrhythmia formation in long QT syndrome may depend not only on the basis of mutation and biophysical alteration, but also upon tissue of expression. The Purkinje fiber network may represent an important therapeutic target in the management of patients with heritable channelopathies. PMID:24892747

  3. Management of ventricular fibrillation or unstable ventricular tachycardia in patients with congenital long-QT syndrome: a suggested modification to ACLS guidelines.

    PubMed

    Homme, Jason H; White, Roger D; Ackerman, Michael J

    2003-10-01

    Prolongation of the QT interval is a known risk factor for syncope, seizures and sudden cardiac death. Most patients with QT prolongation have an acquired cause, but congenital forms of QT prolongation are being increasingly recognized. However, existing advanced cardiac life support (ACLS) treatment algorithms for prolonged QT mediated ventricular fibrillation pertains to acquired long-QT syndrome (LQTS). Here, a young patient with out-of-hospital cardiac arrest secondary to congenital LQTS illustrates critical exceptions to the current ACLS treatment algorithms for ventricular fibrillation and unstable ventricular tachycardia when QT prolongation is congenital in origin. A clarified ACLS algorithm is proposed.

  4. Update on the Diagnosis and Management of Familial Long QT Syndrome.

    PubMed

    Waddell-Smith, Kathryn E; Skinner, Jonathan R

    2016-08-01

    This update was reviewed by the CSANZ Continuing Education and Recertification Committee and ratified by the CSANZ board in August 2015. Since the CSANZ 2011 guidelines, adjunctive clinical tests have proven useful in the diagnosis of LQTS and are discussed in this update. Understanding of the diagnostic and risk stratifying role of LQTS genetics is also discussed. At least 14 LQTS genes are now thought to be responsible for the disease. High-risk individuals may have multiple mutations, large gene rearrangements, C-loop mutations in KCNQ1, transmembrane mutations in KCNH2, or have certain gene modifiers present, particularly NOS1AP polymorphisms. In regards to treatment, nadolol is preferred, particularly for long QT type 2, and short acting metoprolol should not be used. Thoracoscopic left cardiac sympathectomy is valuable in those who cannot adhere to beta blocker therapy, particularly in long QT type 1. Indications for ICD therapies have been refined; and a primary indication for ICD in post-pubertal females with long QT type 2 and a very long QT interval is emerging. Copyright © 2016. Published by Elsevier B.V.

  5. Patient Recall, Interpretation, and Perspective of an Inconclusive Long QT Syndrome Genetic Test Result.

    PubMed

    Predham, Sarah; Hathaway, Julie; Hulait, Gurdip; Arbour, Laura; Lehman, Anna

    2017-02-01

    Patients' perceptions of inconclusive results have been previously investigated in cancer genetics. The differences in how patients recall and interpret an uninformative test result compared to a known pathogenic result can affect medical decisions post disclosure. However, there is little to no data available on patients' interpretation and perception of uninformative genetic results in inherited heart disease. We report the results of a qualitative analysis of 16 telephone interviews with participants who received a negative or a variant of unknown significance (VUS) result from Long QT syndrome (LQTS) genetic testing. Our results suggest that the type of result (negative versus VUS) does not affect recall, regardless of the reason for testing. When receiving a negative result, a majority of participants appropriately perceived no change in their diagnosis, while the perception of risk for family members varied. The majority of participants felt they maintained an awareness of their condition after the result disclosure, and that clinical follow-up was similar to that planned prior to the genetic test result. Further work is needed to determine if there are any differences between obtaining a VUS result versus a negative result in this population.

  6. Reconstruction of action potential of repolarization in patients with congenital long-QT syndrome

    NASA Astrophysics Data System (ADS)

    Kandori, Akihiko; Shimizu, Wataru; Yokokawa, Miki; Kamakura, Shiro; Miyatake, Kunio; Murakami, Masahiro; Miyashita, Tsuyoshi; Ogata, Kuniomi; Tsukada, Keiji

    2004-05-01

    A method for reconstructing an action potential during the repolarization period was developed. This method uses a current distribution—plotted as a current-arrow map (CAM)—calculated using magnetocardiogram (MCG) signals. The current arrows are summarized during the QRS complex period and subtracted during the ST-T wave period in order to reconstruct the action-potential waveform. To ensure the similarity between a real action potential and the reconstructed action potential using CAM, a monophasic action potential (MAP) and an MCG of the same patient with type-I long-QT syndrome were measured. Although the MAP had one notch that was associated with early afterdepolarization (EAD), the reconstructed action potential had two large and small notches. The small notch timing agreed with the occurrence of the EAD in the MAP. On the other hand, the initiation time of an abnormal current distribution coincides with the appearance timing of the first large notch, and its end time coincides with that of the second small notch. These results suggest that a simple reconstruction method using a CAM based on MCG data can provide a similar action-potential waveform to a MAP waveform without having to introduce a catheter.

  7. Reduced Uptake of Family Screening in Genotype-Negative Versus Genotype-Positive Long QT Syndrome.

    PubMed

    Hanninen, Mikael; Klein, George J; Laksman, Zachary; Conacher, Susan S; Skanes, Allan C; Yee, Raymond; Gula, Lorne J; Leong-Sit, Peter; Manlucu, Jaimie; Krahn, Andrew D

    2015-08-01

    The acceptance and yield of family screening in genotype-negative long QT syndrome (LQTS) remains incompletely characterized. In this study of family screening for phenotype-definite Long QT Syndrome (LQTS, Schwartz score ≥3.5), probands at a regional Inherited Cardiac Arrhythmia clinic were reviewed. All LQTS patients were offered education by a qualified genetic counselor, along with materials for family screening including electronic and paper correspondence to provide to family members. Thirty-eight qualifying probands were identified and 20 of these had family members who participated in cascade screening. The acceptance of screening was found to be lower among families without a known pathogenic mutation (33 vs. 77 %, p = 0.02). A total of 52 relatives were screened; fewer relatives were screened per index case when the proband was genotype-negative (1.7 vs. 3.1, p = 0.02). The clinical yield of screening appeared to be similar irrespective of gene testing results (38 vs. 33 %, p = 0.69). Additional efforts to promote family screening among gene-negative long QT families may be warranted.

  8. Ion channels, long QT syndrome and arrhythmogenesis in ageing.

    PubMed

    Jeevaratnam, Kamalan; Chadda, Karan R; Salvage, Samantha C; Valli, Haseeb; Ahmad, Shiraz; Grace, Andrew A; Huang, Christopher L-H

    2016-12-26

    Ageing is associated with increased prevalences of both atrial and ventricular arrhythmias, reflecting disruption of the normal sequence of ion channel activation and inactivation generating the propagated cardiac action potential. Experimental models with specific ion channel genetic modifications have helped clarify the interacting functional roles of ion channels and how their dysregulation contributes to arrhythmogenic processes at the cellular and systems level. They have also investigated interactions between these ion channel abnormalities and age-related processes in producing arrhythmic tendency. Previous reviews have explored the relationships between age and loss-of-function Nav 1.5 mutations in producing arrhythmogenicity. The present review now explores complementary relationships arising from gain-of-function Nav 1.5 mutations associated with long QT3 (LQTS3). LQTS3 patients show increased risks of life-threatening ventricular arrhythmias particularly after 40 years of age consistent with such interactions between the ion channel abnormailities and ageing. In turn clinical evidence suggests that ageing is accompanied by structural, particularly fibrotic, as well as electrophysiological change. These abnormalities may result from biochemical changes producing low-grade inflammation resulting from increased production of reactive oxygen species and superoxide. Experimental studies offer further insights into the underlying mechanisms underlying these phenotypes. Thus, studies in genetically modified murine models for LQTS implicated action potential recovery processes in arrhythmogenesis resulting from functional ion channel abnormalities. In addition, ageing WT murine models demonstrated both ion channel alterations and fibrotic changes with ageing. Murine models then suggested evidence for interactions between ageing and ion channel mutations and provided insights into potential arrhythmic mechanisms inviting future exploration. This article is

  9. Genotype- and Phenotype-Guided Management of Congenital Long QT Syndrome

    PubMed Central

    Giudicessi, John R.; Ackerman, Michael J.

    2014-01-01

    Congenital Long QT syndrome (LQTS) is a genetically heterogeneous collection of heritable disorders of myocardial repolarization linked by their shared clinical phenotype of QT prolongation on electrocardiogram and an increased risk of potentially life-threatening cardiac arrhythmias. At the molecular level, mutations in 15 distinct LQTS-susceptibility genes that encode ion channel pore-forming α-subunits and accessory/auxiliary subunits central to the electromechanical function of the heart have been implicated in its pathogenesis. Over the past two decades, our evolving understanding of the electrophysiological mechanisms by which specific genetic substrates perturb the cardiac action potential has translated into vastly improved approaches to the diagnosis, risk stratification, and treatment of patients with LQTS. In this Review, we detail how our understanding of the molecular underpinnings of LQTS has yielded numerous clinically meaningful genotype-phenotype correlations and how these insights have translated into genotype- and phenotype-guided approaches to the clinical management of LQTS. PMID:24093767

  10. Epilepsy misdiagnosed as long QT syndrome: it can go both ways.

    PubMed

    Medford, Beth A; Bos, J Martijn; Ackerman, Michael J

    2014-01-01

    Cardiogenic seizures are common and could be the sentinel event heralding the presence of congenital long QT syndrome (LQTS). Distinguishing a cardiogenic seizure from a neurogenic one is of the utmost importance. Herein, we present the case of a 12-year-old boy with recurrent episodes of syncope and seizures. Despite absence of QT prolongation on electrocardiogram, absence of documented arrhythmias, a negative LQTS genetic test, and recurrent episodes while on nadolol beta-blocker therapy, he was diagnosed with LQTS and implanted with an implantable cardioverter defibrillator (ICD). When syncope and seizure occurred with normal sinus rhythm documented on the ICD, he was referred to neurology, and an electroencephalogram was positive for numerous bursts of bilaterally synchronous generalized discharges. He was started on antiepileptic treatment after which his seizures resolved. His LQTS diagnosis was removed, beta-blocker therapy discontinued, and his ICD was explanted. He has been seizure-free for over 2 years. © 2013 Wiley Periodicals, Inc.

  11. Antiarrhythmic properties of ivabradine in an experimental model of Short-QT- Syndrome.

    PubMed

    Frommeyer, Gerrit; Weller, Jan; Ellermann, Christian; Kaese, Sven; Kochhäuser, Simon; Lange, Philipp S; Dechering, Dirk G; Eckardt, Lars

    2017-09-01

    The If channel inhibitor ivabradine is recommended for treatment of chronic heart failure. However, ivabradine also inhibits human ether-a-go-go (hERG) mediated potassium currents. The aim of the present study was to assess the electrophysiologic effects of ivabradine in an experimental model of short-QT-syndrome. Twelve rabbit hearts were isolated and Langendorff-perfused. After obtaining baseline data, pinacidil, an IK-ATP channel opener, was infused (1 μmol/L). Eight endo- and epicardial monophasic action potentials and a 12-lead ECG showed a significant abbreviation of QT interval (-32 ms, P<.05) and shortening of action potential duration at 90% of repolarization (APD90; -22 ms, P<.05). The shortening of ventricular repolarization was accompanied by a reduction of effective refractory period (ERP; -20 ms, P<.05). Thereafter, hearts were additionally treated with ivabradine (5 μmol/L) leading to an increase of QT interval (+31 ms, P<.05), APD90 (+15 ms, P<.05) as well as of ERP (+38 ms, P<.05) and post-repolarization refractoriness (PRR, +33 ms, P<.05) as compared with sole pinacidil infusion. Under baseline conditions, ventricular fibrillation (VF) was inducible by a standardized pacing protocol including programmed stimulation and burst stimulation in 3 of 12 hearts (6 episodes). After application of 1 μmol/L pinacidil, 6 of 12 hearts were inducible (22 episodes). Additional infusion of 5 μmol/L ivabradine led to a significant suppression of VF. Only two episodes could be induced in 1 of 12 hearts. In the present study ivabradine reversed the electrophysiologic effects of pharmacologically simulated short-QT syndrome. Ivabradine demonstrated antiarrhythmic properties based on an increase of both ERP and PRR. © 2017 John Wiley & Sons Australia, Ltd.

  12. Contribution of a KCNH2 variant in genotyped long QT syndrome: Romano-Ward syndrome under double mutations and acquired long QT syndrome under heterozygote.

    PubMed

    Fujii, Yusuke; Matsumoto, Yuichi; Hayashi, Kenshi; Ding, Wei-Guang; Tomita, Yukinori; Fukumoto, Daisuke; Wada, Yuko; Ichikawa, Mari; Sonoda, Keiko; Ozawa, Junichi; Makiyama, Takeru; Ohno, Seiko; Yamagishi, Masakazu; Matsuura, Hiroshi; Horie, Minoru; Itoh, Hideki

    2017-07-01

    Long QT syndrome (LQTS) presents two clinical phenotypes, congenital and acquired forms. This study aims to evaluate the genetic contribution of a KCNH2 variant for the two LQTS phenotypes. From 1996 to 2014, genetic screening for LQTS probands was performed for five major genes: KCNQ1, KCNH2, SCN5A, KCNE1, and KCNE2 and 389 probands were found to be mutation carriers. We analyzed the clinical phenotypes of p.His492Tyr carriers in KCNH2. Heterozygous p.His492Tyr variant was identified in 10 LQTS families. Six probands (mean age, 26±23 years) carried another mutation, and two of six had syncope associated with emotional stress or telephone ringing. The remaining four probands were significantly older at diagnosis (mean age, 42±33 years) and carried no other compound mutations. All the four probands had fatal arrhythmic events in the presence of additional precipitating factors such as culprit drugs in 2, hypokalemia in 1, and bradycardia in 1. The QTc interval of carriers with p.His492Tyr alone was 445±10ms and significantly shorter than that in double mutation carriers (481±40ms, p=0.041). KCNH2 p.His492Tyr variant presented Romano-Ward syndrome in the presence of another mutation and heterozygous carriers had mild phenotypes while even heterozygous carriers should be cared for not to encounter secondary factors because incidental factors could manifest "latent" form of p.His492Tyr heterozygous carriers. Copyright © 2016 Japanese College of Cardiology. Published by Elsevier Ltd. All rights reserved.

  13. Obstructive Sleep Apnea in Patients with Congenital Long QT Syndrome: Implications for Increased Risk of Sudden Cardiac Death

    PubMed Central

    Shamsuzzaman, Abu S.; Somers, Virend K.; Knilans, Timothy K.; Ackerman, Michael J.; Wang, Yu; Amin, Raouf S.

    2015-01-01

    Background: Congenital long QT syndrome (LQTS) is a familial arrhythmogenic cardiac channelopathy characterized by prolonged ventricular repolarization and increased risk of torsades de pointes-mediated syncope, seizures, and sudden cardiac death (SCD). QT prolongation corrected for heart rate (QTc) is an important diagnostic and prognostic feature in LQTS. Obstructive sleep apnea (OSA) has been increasingly implicated in the pathogenesis of cardiovascular disease, including arrhythmias and SCD. We tested the hypothesis that the presence of concomitant OSA in patients with LQTS is associated with increased QT intervals, both during sleep and while awake. Methods and Results: Polysomnography with simultaneous overnight 12-lead electrocardiography (ECG) was recorded in 54 patients with congenital LQTS and 67 control subjects. OSA was diagnosed as apnea-hypopnea index (AHI) ≥ 5 events/h for adults and AHI > 1 event/h for children. RR and QT intervals were measured from the 12-lead surface ECG. QTc was determined by the Bazett formula. Respiratory disturbance index, AHI, and arousal index were significantly increased in patients with LQTS and with OSA compared to those without OSA and control subjects. QTc during different sleep stages and while awake was also significantly increased in patients with LQTS and OSA compared to those without OSA. Severity of OSA in patients with LQTS was directly associated with the degree of QTc. Conclusions: The presence and severity of obstructive sleep apnea (OSA) in patients with congenital long QT syndrome (LQTS) is associated with increased QT prolongation corrected for heart rate, which is an important biomarker of sudden cardiac death (SCD). Treatment of OSA in LQTS patients may reduce QT prolongation, thus reducing the risk of LQT-triggered SCD. Citation: Shamsuzzaman AS, Somers VK, Knilans TK, Ackerman MJ, Wang Y, Amin RS. Obstructive sleep apnea in patients with congenital long QT syndrome: implications for increased risk of

  14. Automated external defibrillator rescues among children with diagnosed and treated long QT syndrome.

    PubMed

    Pundi, Kavitha N; Bos, J Martijn; Cannon, Bryan C; Ackerman, Michael J

    2015-04-01

    Long QT syndrome (LQTS) is a potentially lethal yet highly treatable cardiac channelopathy. A comprehensive LQTS-directed treatment program often includes an automated external defibrillator (AED). The purpose of this study was to determine the incidence of AED rescues among children evaluated, risk-stratified, and treated in an LQTS specialty center. We performed a retrospective review of the electronic medical records to identify 1665 patients evaluated in our Genetic Heart Rhythm Clinic (1999-2013). Subset analysis was performed on 291 children managed without an implantable cardioverter-defibrillator (ICD). The average age at diagnosis was 8.3 ± 5.7 years with an average. QTc of 463 ± 40 ms (17% ≥500 ms). The represented LQTS genotypes included type 1 (LQT1) in 52%, type 2 (LQT2) in 35%, and type 3 (LQT3) in 7%. During follow-up, 3 of 291 children (1%) had a cardiac arrest with an appropriate AED rescue (2/51 symptomatic, 1/240 asymptomatic). The first AED rescue occurred during exercise in a symptomatic 3-year-old boy with compound LQT1 treated with beta-blocker and videoscopic left cardiac sympathetic denervation (LCSD). The second AED rescue occurred in a remotely symptomatic 14-year-old boy with high-risk LQT2 (QTc >550 ms) on a beta-blocker who previously declined a prophylactic ICD. The third AED rescue involved an asymptomatic 17-year-old girl with LQT3 on mexiletine who collapsed in school. An AED should seldom be necessary in an appropriately treated child with LQTS. Nevertheless, despite only 3 AED rescues in more than 1700 patient-years, an AED can be a lifesaving and cost-effective part of an LQTS patient's comprehensive sudden death prevention program. Copyright © 2015 Heart Rhythm Society. Published by Elsevier Inc. All rights reserved.

  15. α-1-Syntrophin Mutation and the Long-QT Syndrome: A Disease of Sodium Channel Disruption

    PubMed Central

    Wu, Geru; Ai, Tomohiko; Kim, Jeffrey J.; Mohapatra, Bhagyalaxmi; Xi, Yutao; Li, Zhaohui; Abbasi, Shahrzad; Purevjav, Enkhsaikhan; Samani, Kaveh; Ackerman, Michael J; Qi, Ming; Moss, Arthur J.; Shimizu, Wataru; Towbin, Jeffrey A.; Cheng, Jie; Vatta, Matteo

    2009-01-01

    Background Long-QT syndrome (LQTS) is an inherited disorder associated with sudden cardiac death. The cytoskeletal protein syntrophin-α1 (SNTA1) is known to interact with the cardiac sodium channel (hNav1.5), and we hypothesized that SNTA1 mutations might cause phenotypic LQTS in patients with genotypically normal hNav1.5 by secondarily disturbing sodium channel function. Methods and Results Mutational analysis of SNTA1 was performed on 39 LQTS patients (QTc≥480 ms) with previously negative genetic screening for the known LQTS-causing genes. We identified a novel A257G-SNTA1 missense mutation, which affects a highly conserved residue, in 3 unrelated LQTS probands but not in 400 ethnic-matched control alleles. Only 1 of these probands had a preexisting family history of LQTS and sudden death with an additional intronic variant in KCNQ1. Electrophysiological analysis was performed using HEK-293 cells stably expressing hNav1.5 and transiently transfected with either wild-type or mutant SNTA1 and, in neonatal rat cardiomyocytes, transiently transfected with either wild-type or mutant SNTA1. In both HEK-293 cells and neonatal rat cardiomyocytes, increased peak sodium currents were noted along with a 10-mV negative shift of the onset and peak of currents of the current-voltage relationships. In addition, A257G-SNTA1 shifted the steady-state activation (Vh) leftward by 9.4 mV, whereas the voltage-dependent inactivation kinetics and the late sodium currents were similar to wild-type SNTA1. Conclusion SNTA1 is a new susceptibility gene for LQTS. A257G-SNTA1 can cause gain-of-function of Nav1.5 similar to the LQT3. PMID:19684871

  16. Sevoflurane-associated torsade de pointes in a patient with congenital long QT syndrome genotype 2.

    PubMed

    Kumakura, Mika; Hara, Koji; Sata, Takeyoshi

    2016-09-01

    Although patients with congenital long QT syndrome (c-LQTS) are considered to be at high risk for anesthesia, few reports describe c-LQTS genotype-specific considerations for anesthesia. We describe a case of torsade de pointes (TdP) caused by sevoflurane in a patient with c-LQTS genotype 2 (LQT2). A 39-year-old woman diagnosed with c-LQTS was scheduled for an elective therapeutic abortion. Immediately after starting the operation, the patient developed TdP. Since pulseless ventricular tachycardia was sustained despite intravenous injection of lidocaine, defibrillation was performed. Analysis of the electrocardiogram revealed that the corrected QT interval before anesthesia was 530 ms and 2.0% sevoflurane markedly prolonged the corrected QT interval to 693 ms. Postoperative studies revealed a mutation in the KCNH2 gene. Anesthesiologists should note that patients with LQT2 could be more susceptible to volatile anesthetics than are those with other major genotypes. Genotype-specific management of anesthesia may reduce the risk of developing TdP during the perioperative period. Copyright © 2016 Elsevier Inc. All rights reserved.

  17. Clinical presentation and course of long QT syndrome in Thai children

    PubMed Central

    Saprungruang, Ankavipar; Vithessonthi, Kanyalak; La-orkhun, Vidhavas; Lertsapcharoen, Pornthep; Khongphatthanayothin, Apichai

    2015-01-01

    Background Congenital long QT syndrome (LQTS) is a genetically transmitted cardiac channelopathy that can lead to lethal arrhythmia and sudden cardiac death in healthy young people. The clinical characteristics of LQTS are variable and depend on the subtype of long QT syndrome, which differ among populations. This single hospital-based case review study examined the clinical presentation of long QT syndrome and the outcomes of its treatment in 20 Thai children at King Chulalongkorn Memorial Hospital in Bangkok, Thailand. Methods Inpatient and outpatient records of children (aged 0–14 years) diagnosed with long QT syndrome from January 1, 1998, to September 30, 2013, were retrospectively reviewed. Presentation at diagnosis, treatments, and clinical courses were collected and analyzed. In the 20 subjects, total Schwartz scores totaled 5.2±0.9 points, and mean age at diagnosis was 7.6±4.4 years (range, 1 day–13.8 years). The patients were assigned to one of 3 groups based on trigger events: 50% of patients had events at rest (sleep or at rest), 35% experienced adrenergic-mediated events (e.g., stress, exercise, startle), and 15% were asymptomatic. Excluding the 3 patients who died at first presentation, 100% of patients received a beta blocker, and 47.1% were treated with an automatic implantable cardioverter-defibrillator (AICD). Results At follow-up (median=959 days; range, 1–4170 days), 4 patients (20%) were known to have died, 3 of whom died shortly after the diagnosis. Among patients who survived the initial event, 52.9% (9 of 17) experienced cardiac events (appropriate AICD shock, death, and/or syncope) during the follow-up period. The mean duration from diagnosis to cardiac event was 1420±759 days (range, 497–2499 days). Conclusions All 20 patients with LQTS were mostly symptomatic at presentation. Owing to the geographical region and ethnicity of the Thai population, we conclude that the ratio of patients who develop cardiac symptoms at rest or

  18. Influence of gender and types of sports training on QT variables in young elite athletes.

    PubMed

    Omiya, Kazuto; Sekizuka, Hiromitsu; Kida, Keisuke; Suzuki, Kengo; Akashi, Yoshihiro J; Ohba, Haruo; Musha, Haruki

    2014-01-01

    Influence of gender and sports training on QT variables such as QT interval and dispersion (QT dispersion: QTD) in young elite athletes were evaluated. Subjects included 104 male and 97 female Japanese elite athletes (mean age 21.6 years). Sports included basketball, fencing, gymnastics, judo, swimming, tennis, track and field and volleyball. Age-matched healthy non-athletes (32 men and 20 women) were enrolled as controls. QT measurements were manually obtained from a 12-lead resting electrocardiogram and QTD was calculated as the difference between the longest and shortest QT intervals. A corrected QT interval (QTc) was obtained using Bazett's formula. Subjects were divided into two groups; an endurance training group and a static training group on the basis of their training types. Maximum and minimum QTc were significantly longer in female athletes than in male athletes (max: 414.2 vs. 404.5 ms, min: 375.1 vs. 359.2 ms, p<0.0001 respectively), whereas QTc dispersion (QTcD) was shorter in female athletes than in male athletes (39.2 vs. 45.3 ms, p<0.0001). QTcD was significantly shorter in female athletes than in the female control group (39.2 vs. 45.2 ms, p<0.05). However, no statistically significant difference was observed between male athletes and the male control group. Male gymnasts exhibited significantly longer QTcD than the control group (p<0.01), but female gymnasts had significantly shorter QTcD than the control group (p<0.05). Maximum QTc intervals were prolonged in the male static training group compared with non-athletes, and QTcDs in the static training group were prolonged compared with the endurance training group. However, no significant difference was observed in the female group. In conclusion, both gender and different characteristics of sports training may affect QT variables even in young elite athletes. Vigorous static exercise training may independently prolong QT variables.

  19. Genetically induced dysfunctions of Kir2.1 channels: implications for short QT3 syndrome and autism–epilepsy phenotype

    PubMed Central

    Ambrosini, Elena; Sicca, Federico; Brignone, Maria S.; D'Adamo, Maria C.; Napolitano, Carlo; Servettini, Ilenio; Moro, Francesca; Ruan, Yanfei; Guglielmi, Luca; Pieroni, Stefania; Servillo, Giuseppe; Lanciotti, Angela; Valvo, Giulia; Catacuzzeno, Luigi; Franciolini, Fabio; Molinari, Paola; Marchese, Maria; Grottesi, Alessandro; Guerrini, Renzo; Santorelli, Filippo M.; Priori, Silvia; Pessia, Mauro

    2014-01-01

    Short QT3 syndrome (SQT3S) is a cardiac disorder characterized by a high risk of mortality and associated with mutations in Kir2.1 (KCNJ2) channels. The molecular mechanisms leading to channel dysfunction, cardiac rhythm disturbances and neurodevelopmental disorders, potentially associated with SQT3S, remain incompletely understood. Here, we report on monozygotic twins displaying a short QT interval on electrocardiogram recordings and autism–epilepsy phenotype. Genetic screening identified a novel KCNJ2 variant in Kir2.1 that (i) enhanced the channel's surface expression and stability at the plasma membrane, (ii) reduced protein ubiquitylation and degradation, (iii) altered protein compartmentalization in lipid rafts by targeting more channels to cholesterol-poor domains and (iv) reduced interactions with caveolin 2. Importantly, our study reveals novel physiological mechanisms concerning wild-type Kir2.1 channel processing by the cell, such as binding to both caveolin 1 and 2, protein degradation through the ubiquitin–proteasome pathway; in addition, it uncovers a potential multifunctional site that controls Kir2.1 surface expression, protein half-life and partitioning to lipid rafts. The reported mechanisms emerge as crucial also for proper astrocyte function, suggesting the need for a neuropsychiatric evaluation in patients with SQT3S and offering new opportunities for disease management. PMID:24794859

  20. Autre cause de mort subite du nourrisson: à propos d'un cas clinique de syndrome du QT long congenital

    PubMed Central

    Seka, Zena; Mols, Pierre; Gobin, Eric; Ngatchou, William

    2014-01-01

    Le syndrome du QT long congénital est une maladie rythmique liée à une mutation génétique et caractérisée par un espace QT allongé sur l’électrocardiogramme, des arythmies malignes type torsade de pointe et fibrillation ventriculaire entraînant une mort subite. Les gènes impliqués dans ces mutations codent pour des sous unités des canaux ioniques responsables de l'activité électrique cardiaque. Le diagnostic est basé sur l’électrocardiogramme, une enquête familiale et l’étude génétique. Le traitement repose sur les bêtabloquants, la sympathectomie et le stimulateur cardiaque. Nous rapportons le cas d'un nourrisson de 2 ans retrouvé en état de mort apparente. Nous discutons de sa prise en charge initiale, de l'enquête familiale et de son suivi ultérieur. PMID:25667708

  1. A splice site mutation in hERG leads to cryptic splicing in human long QT syndrome

    PubMed Central

    Gong, Qiuming; Zhang, Li; Moss, Arthur J.; Vincent, G. Michael; Ackerman, Michael J.; Robinson, Jeffrey C.; Jones, Melanie A.; Tester, David J.; Zhou, Zhengfeng

    2008-01-01

    Mutations in the human ether-a-go-go-related gene (hERG) cause type 2 long QT syndrome. In this study, we investigated the mechanism of the hERG splice site mutation 2398+1G>C and the genotype-phenotype relationship of mutation carriers in three unrelated kindreds with long QT syndrome. The effect of 2398+1G>C on mRNA splicing was studied by analysis of RNA isolated from lymphocytes of index patients and using minigenes expressed in HEK293 cells and neonatal rat ventricular myocytes. RT-PCR analysis revealed that the 2398+1G>C mutation disrupted the normal splicing and activated a cryptic splice donor site in intron 9, leading to the inclusion of 54 nt of the intron 9 sequence in hERG mRNA. The cryptic splicing resulted in an in-frame insertion of 18 amino acids in the middle of the cyclic nucleotide binding domain. In patch clamp experiments the splice mutant did not generate hERG current. Western blot and immunostaining studies showed that the mutant expressed an immature form of hERG protein that failed to reach the plasma membrane. Coexpression of the mutant and wild-type channels led to a dominant negative suppression of wild-type channel function by intracellular retention of heteromeric channels. Our results demonstrate that 2398+1G>C activates a cryptic site and generates a full-length hERG protein with an insertion of 18 amino acids, which leads to a trafficking defect of the mutant channel. PMID:18272172

  2. Genetic Testing for Long QT Syndrome - Distinguishing Pathogenic Mutations from Benign Variants

    PubMed Central

    Kapa, Suraj; Tester, David J.; Salisbury, Benjamin A.; Harris-Kerr, Carole; Pungliya, Manish S.; Alders, Marielle; Wilde, Arthur A. M.; Ackerman, Michael J.

    2010-01-01

    Background Genetic testing for long QT syndrome (LQTS) has diagnostic, prognostic, and therapeutic implications. Hundreds of causative mutations in 12 known LQTS-susceptibility genes have been identified. Genetic testing that includes the 3 most commonly mutated genes is available clinically. Distinguishing pathogenic mutations from innocuous rare variants is critical to the interpretation of test results. We sought to quantify the value of mutation type and gene/protein region in determining the probability of pathogenicity for mutations. Methods and Results Type, frequency, and location of mutations across KCNQ1 (LQT1), KCNH2 (LQT2) and SCN5A (LQT3) were compared between 388 unrelated “definite” (clinical diagnostic score > 4 and/or QTc > 480 ms) cases of LQTS and over 1300 healthy controls for each gene. From these data, estimated predictive values (EPV, meaning the percent of mutations found in definite cases that would be LQTS-causing) were determined according to mutation type and location. Mutations were 10× more common in cases than controls (0.58/case vs 0.06/control). Missense mutations were the most common, accounting for 78%, 67%, and 89% of mutations in KCNQ1, KCNH2, and SCN5A in cases and >95% in controls. Non-missense mutations have an EPV >99% regardless of location. In contrast, location appears to be critical for characterizing missense mutations. Relative frequency of missense mutations between cases and controls ranged from ~1:1 in the SCN5A interdomain linker (IDL) to infinity in KCNH2’s pore (P), transmembrane (TM), and linker (L). These correspond to EPVs ranging from 0% in the IDL of SCN5A to 100% in the TM/L/P regions of KCNH2. EPV is also high in KCNQ1’s L, P, TM, and C-terminus and the TM/L of SCN5A. Conclusions Distinguishing pathogenic mutations from rare variants is of critical importance in the interpretation of genetic testing in LQTS. Mutation type, mutation location, and ethnic specific background rates are critical

  3. Molecular biology and cellular mechanisms of Brugada and long QT syndromes in infants and young children.

    PubMed

    Antzelevitch, C

    2001-01-01

    Sudden cardiac death accounts for 19% of sudden deaths in children between 1 and 13 years of age and 30% of sudden deaths that occur between 14 and 21 years of age. The incidence of sudden cardiac death displays 2 peaks: one between 45 and 75 years of age, as a result of coronary artery disease, and the other between birth and 6 months of age, caused by sudden infant death syndrome. The role of cardiac arrhythmias in sudden infant death syndrome has long been a matter of debate and the role of cardiac arrhythmias in children in general is not well defined. Recent findings point to a contribution of primary electrical diseases of the heart including the Brugada and long QT syndromes to sudden death in infants and children. Mutations in SCN5A and HERG and KvLQT1 have been shown to be associated with life-threatening arrhythmias and long QT intervals in young infants. These mutations cause changes in sodium and potassium currents that amplify intrinsic electrical heterogeneities within the heart, thus providing a substrate as well as a trigger for the development of reentrant arrhythmias, including Torsade de Pointes (TdP), commonly associated with the long QT syndrome (LQTS). Mutations in SCN5A have also been shown to cause the sodium channel to turn off prematurely and thus to set the stage for the development of a rapid polymorphic ventricular tachycardia/ventricular fibrillation in patients with the Brugada Syndrome. In LQTS, ion channel mutations cause a preferential prolongation of the M cell action potential that contributes to the development of long QT intervals, wide-based or notched T waves, and a large transmural dispersion of repolarization, which provides the substrate for the development of TdP. An early afterdepolarization-induced triggered beat is thought to provide the extrasystole that precipitates TdP. In the Brugada syndrome, mutations in SCN5A reduce sodium current density, causing premature repolarization of the epicardial action potential due

  4. ATX-II-induced pulmonary vein arrhythmogenesis related to atrial fibrillation and long QT syndrome.

    PubMed

    Lu, Yen-Yu; Cheng, Chen-Chuan; Chen, Yao-Chang; Chen, Shih-Ann; Chen, Yi-Jen

    2012-08-01

    Long QT syndrome (LQTS) is associated with a high incidence of atrial fibrillation (AF), but the underlying mechanisms are unclear. Pulmonary veins (PVs) play a critical role in AF genesis. Type 3 LQTS increases late sodium current (I(Na,L) ), which may increase PV arrhythmogenesis and AF. Therefore, this study examines PV arrhythmogenesis in anemonia sulcata toxin II (ATX-II)-induced type 3 LQTS and evaluates whether the I(Na,L) inhibitor ranolazine can suppress PV arrhythmogenesis. Conventional microelectrodes were used to record the action potentials (AP) and contractility in isolated rabbit PV specimens before and after ATX-II administration with or without ranolazine. Anemonia sulcata toxin II (100 nM) increased the PV spontaneous rates from 2·0 ± 0·1 to 2·9 ± 0·2 Hz (n = 7), induced PV burst firing (100%) with the genesis of early afterdepolarization (EAD) (86%) and prolonged the AP duration. Ranolazine (0·1, 1 and 10 μM) dose dependently reduced the PV spontaneous rates from 2·5 ± 0·2 to 2·3 ± 0·2 Hz, 1·9 ± 0·2 and 1·5 ± 0·3 Hz (P < 0·05) and decreased the diastolic tension by 40 ± 19%, 87 ± 26% and 113 ± 28%. In the presence of ranolazine (10 μM), ATX-II (100 nM) further increased the AP duration. However, ATX-II neither increased the PV spontaneous rates (1·6 ± 0·1 vs. 1·7 ± 0·2 Hz, n = 7) nor induced PV burst firing or EAD. Moreover, ranolazine (10 μM) reduced ATX-II-induced PV acceleration and EAD. The I(Na,L) enhancer ATX-II can increase PV arrhythmogenesis, which can be attenuated or blocked by ranolazine. This suggests that AF may be related to type 3 LQTS through increased I(Na,L) . © 2012 The Authors. European Journal of Clinical Investigation © 2012 Stichting European Society for Clinical Investigation Journal Foundation.

  5. Long QT syndrome: how effective therapy in a single patient favorably influenced the long-term clinical course and genetic understanding of this hereditary disorder.

    PubMed

    Lowengrub, Katherine M; Moss, Deborah R; Moss, David A; Moss, Arthur J

    2015-01-01

    The story of the long QT syndrome involved a chance interaction that took place in 1957 when Dr. Moss was shown a unique series of ECGs with a prolonged QT interval in a young deaf boy whose recurrent syncope culminated in sudden death. Who could have predicted that this clinical experience would lead to innovative and effective new therapy for a patient with the long QT syndrome several years later and the subsequent formation of the International Long QT Registry? This Registry has stimulated interactions among and between patients and physicians and has enhanced collaborations involving clinical, genetic, and basic-science investigators. The net result has been a significant improvement in the diagnosis, treatment, and outcome of patients with the long QT syndrome and an overall advancement in the science of medicine - two of the many satisfactions that physicians can experience in the clinical practice of medicine.

  6. An interdomain KCNH2 mutation produces an intermediate long QT syndrome

    PubMed Central

    Osterbur, Marika L.; Zheng, Renjian; Marion, Robert; Walsh, Christine; McDonald, Thomas V.

    2015-01-01

    Hereditary Long QT Syndrome is caused by deleterious mutation in one of several genetic loci, including locus LQT2 that contains the KCNH2 gene (or hERG), causing faulty cardiac repolarization. Here, we describe and characterize a novel mutation, p.Asp219Val in the hERG channel, identified in an 11 year old male with syncope and prolonged QT interval. Genetic sequencing showed a non-synonymous variation in KCNH2 (c.656A>T: amino acid p.Asp219Val). p.Asp219Val resides in a region of the channel predicted to be unstructured and flexible, located between the PAS (Per-Arnt-Sim) domain and its interaction sites in the transmembrane domain. The p.Asp219Val hERG channel produced K+ current that activated with modest changes in voltage dependence. Mutant channels were also slower to inactivate, recovered from inactivation more readily and demonstrated a significantly accelerated deactivation rate compared to the slow deactivation of WT channels. The intermediate nature of the biophysical perturbation is consistent with the degree of severity in the clinical phenotype. The findings of this study demonstrate a previously unknown role of the proximal N-terminus in deactivation and support the hypothesis that the proximal N-terminal domain is essential in maintaining slow hERG deactivation. PMID:25914329

  7. [Diagnosis, sudden death risk stratification, and treatment of main long QT syndrome molecular-genetic variants].

    PubMed

    Shkol'nikova, M A; Kharlap, M S; Il'darova, R A; Bereznitskaia, V V; Kalinin, L A

    2011-01-01

    Inherited long QT syndrome (LQTS) refers to the primary electrical diseases of the heart. It is characterized by QT prolongation on resting ECG and syncope due to life-threatening ventricular arrhythmias. This review focuses on diagnosis, differential diagnosis, risk stratification of sudden cardiac death, and treatment strategy of patients with most prevalent genetic fOrms of LQTS - LQT1, LQT2 and LQT3, which accounted for about 90% of all genetically confirmed cases. Recent advances in understanding of relationship between clinical, electrocardiographic features (on ECG, body surface mapping, stress test) and genetic variants of LQT presented. Characteristics of syncopal events and ECG features of LQTl, LQT2 and LQT3 in the majority of cases are helpful to make an appropriate choice for therapy, even before positive result of molecular genetic testing. Management has focused on the use of beta blockers as first-line treatment and exclusion of triggers of life-threatening arrhythmia which are specific for each molecular-genetic variant. Implantation of cardioverter defibrillator for secondary prevention of sudden death in the high-risk patients or patients with insufficient effect of antiarrhythmic therapy is required.

  8. A computational model of Purkinje fibre single cell electrophysiology: implications for the long QT syndrome

    PubMed Central

    Sampson, K J; Iyer, V; Marks, A R; Kass, R S

    2010-01-01

    Computer modelling has emerged as a particularly useful tool in understanding the physiology and pathophysiology of cardiac tissues. Models of ventricular, atrial and nodal tissue have evolved and include detailed ion channel kinetics and intercellular Ca2+ handling. Purkinje fibre cells play a central role in the electrophysiology of the heart and in the genesis of cardiac arrhythmias. In this study, a new computational model has been constructed that incorporates the major membrane currents that have been isolated in recent experiments using Purkinje fibre cells. The model, which integrates mathematical models of human ion channels based on detailed biophysical studies of their kinetic and voltage-dependent properties, recapitulates distinct electrophysiological characteristics unique to Purkinje fibre cells compared to neighbouring ventricular myocytes. These characteristics include automaticity, hyperpolarized voltage range of the action potential plateau potential, and prolonged action potential duration. Simulations of selective ion channel blockade reproduce responses to pharmacological challenges characteristic of isolated Purkinje fibres in vitro, and importantly, the model predicts that Purkinje fibre cells are prone to severe arrhythmogenic activity in patients harbouring long QT syndrome 3 but much less so for other common forms of long QT. This new Purkinje cellular model can be a useful tool to study tissue-specific drug interactions and the effects of disease-related ion channel dysfunction on the cardiac conduction system. PMID:20498233

  9. Review and Management of the Dental Patient With Long QT Syndrome (LQTS)

    PubMed Central

    Rochford, Christopher; Seldin, R. David

    2009-01-01

    Long QT syndrome (LQTS) is a unique cardiovascular condition, with both congenital and acquired forms that afflict patients. These patients show a lengthening of the repolarization phase of the cardiac cycle, which can be best visualized on an electrocardiogram (ECG). The ECG changes can include QT interval (the time between the start of the Q wave and the end of the T wave, as seen on an ECG) and T wave abnormalities, as well as progression to torsades de pointes and ventricular fibrillation. The ECG changes are most commonly elicited by physical activity, emotional stress, and certain medications. This condition represents a challenge for the oral and maxillofacial surgeon. Patients with LQTS must receive proper medical management and a controlled and anxiety-free surgical environment. The purpose of this article was to present a review of LQTS and provide recommendations for effective surgical management. Additionally, a case report of a patient with LQTS, treated by one of the authors, has been included. PMID:19642718

  10. We Only Find What We Look For: Fetal Heart Rate and the Diagnosis of Long QT Syndrome

    PubMed Central

    Cuneo, Bettina F.; Strasburger, Janette F.

    2015-01-01

    Long QT syndrome (LQTS), an inherited channelopathy, is a common cause of arrhythmic death in infants, children and young adults. Although many LQTS genes have been identified, most (~75%) of LQTS mutations are found in KCNQ1, KCNH2 or SCN5A. In most cases, treatment for LQTS is successful and modifies the risk of life-threatening arrhythmias; thus, making the correct diagnosis is important. The diagnosis of LQTS is made by the measurement of a prolonged QT interval on the standard ECG; family history or characteristic arrhythmia features are used to strengthen the diagnosis and genetic testing confirms the diagnosis. PMID:26286300

  11. Role of QT interval prolongation in the creation of spiral wave type reentry.

    PubMed

    Shibata, N; Watanabe, H; Sakuma, I; Kodama, I; Niwa, R; Fukui, Y; Toyama, J; Hosoda, S

    1997-01-01

    The inducibility of reentry was compared for four QT patterns in a heart conduction simulation model. Local (L) and gradual (G) QT prolongation models are more susceptible to reentry induction than the no (N) QT prolongation model (reentry induced episodes for N, L, and G numbered 90, 120, and 122, respectively). This increased vulnerability was diminished when the QT interval was prolonged at all simulation sites (reentry induced episodes for the diffuse QT prolongation model, D model, numbered 82). Decreased QT dispersion might be important for the prevention of reentry induction regardless of whether the QT interval is increased.

  12. Identification of Genetic Alterations, as Causative Genetic Defects in Long QT Syndrome, Using Next Generation Sequencing Technology

    PubMed Central

    Mademont-Soler, Irene; Allegue, Catarina; Cesar, Sergi; Ferrer-Costa, Carles; Coll, Monica; Mates, Jesus; Iglesias, Anna; Brugada, Josep; Brugada, Ramon

    2014-01-01

    Background Long QT Syndrome is an inherited channelopathy leading to sudden cardiac death due to ventricular arrhythmias. Despite that several genes have been associated with the disease, nearly 20% of cases remain without an identified genetic cause. Other genetic alterations such as copy number variations have been recently related to Long QT Syndrome. Our aim was to take advantage of current genetic technologies in a family affected by Long QT Syndrome in order to identify the cause of the disease. Methods Complete clinical evaluation was performed in all family members. In the index case, a Next Generation Sequencing custom-built panel, including 55 sudden cardiac death-related genes, was used both for detection of sequence and copy number variants. Next Generation Sequencing variants were confirmed by Sanger method. Copy number variations variants were confirmed by Multiplex Ligation dependent Probe Amplification method and at the mRNA level. Confirmed variants and copy number variations identified in the index case were also analyzed in relatives. Results In the index case, Next Generation Sequencing revealed a novel variant in TTN and a large deletion in KCNQ1, involving exons 7 and 8. Both variants were confirmed by alternative techniques. The mother and the brother of the index case were also affected by Long QT Syndrome, and family cosegregation was observed for the KCNQ1 deletion, but not for the TTN variant. Conclusions Next Generation Sequencing technology allows a comprehensive genetic analysis of arrhythmogenic diseases. We report a copy number variation identified using Next Generation Sequencing analysis in Long QT Syndrome. Clinical and familiar correlation is crucial to elucidate the role of genetic variants identified to distinguish the pathogenic ones from genetic noise. PMID:25494010

  13. Electrophysiological studies of transgenic long QT type 1 and type 2 rabbits reveal genotype-specific differences in ventricular refractoriness and His conduction

    PubMed Central

    Odening, Katja E.; Kirk, Malcolm; Brunner, Michael; Ziv, Ohad; Lorvidhaya, Peem; Liu, Gong Xin; Schofield, Lorraine; Chaves, Leonard; Peng, Xuwen; Zehender, Manfred; Choi, Bum-Rak

    2010-01-01

    We have generated transgenic rabbits lacking cardiac slow delayed-rectifier K+ current [IKs; long QT syndrome type 1 (LQT1)] or rapidly activating delayed-rectifier K+ current [IKr; long QT syndrome type 2 (LQT2)]. Rabbits with either genotype have prolonged action potential duration and QT intervals; however, only LQT2 rabbits develop atrioventricular (AV) blocks and polymorphic ventricular tachycardia. We therefore sought to characterize the genotype-specific differences in AV conduction and ventricular refractoriness in LQT1 and LQT2 rabbits. We carried out in vivo electrophysiological studies in LQT1, LQT2, and littermate control (LMC) rabbits at baseline, during isoproterenol infusion, and after a bolus of dofetilide and ex vivo optical mapping studies of the AV node/His-region at baseline and during dofetilide perfusion. Under isoflurane anesthesia, LQT2 rabbits developed infra-His blocks, decremental His conduction, and prolongation of the Wenckebach cycle length. In LQT1 rabbits, dofetilide altered the His morphology and slowed His conduction, resulting in intra-His block, and additionally prolonged the ventricular refractoriness, leading to pseudo-AV block. The ventricular effective refractory period (VERP) in right ventricular apex and base was significantly longer in LQT2 than LQT1 (P < 0.05) or LMC (P < 0.01), with a greater VERP dispersion in LQT2 than LQT1 rabbits. Isoproterenol reduced the VERP dispersion in LQT2 rabbits by shortening the VERP in the base more than in the apex but had no effect on VERP in LQT1. EPS and optical mapping experiments demonstrated genotype-specific differences in AV conduction and ventricular refractoriness. The occurrence of infra-His blocks in LQT2 rabbits under isoflurane and intra-His block in LQT1 rabbits after dofetilide suggest differential regional sensitivities of the rabbit His-Purkinje system to drugs blocking IKr and IKs. PMID:20581090

  14. Prolonged QT Syndrome and Seizure Secondary to Alkaline Earth Metal Deficiency: A Case Report.

    PubMed

    McKinney, A; Keegan, B C

    2011-01-01

    Introduction. Alkaline earth metal deficiency is recognized as a cause of both seizure and long QT syndrome. Their deficiency can have significant repercussions on the function of cells, tissues, and organs of the body. An understanding of the role of electrolytes allows an appreciation of the significance of depleted levels on cell function. Case Report. A 65-year-old lady was admitted with symptoms of chest discomfort, vomiting, increased stoma output, and dizziness. Two days following admission she suffered a tonic-clonic seizure. ECG review demonstrated a prolonged QTc interval, raising the possibility of an underlying Torsades de Pointes as the precipitant. This was attributed to electrolyte disturbance arising as a result of multiple aetiologies. Discussion. This paper highlights the multisystem effects of electrolyte disturbance, with emphasis upon its role in precipitating cardiac arrhythmia and neurological symptoms.

  15. Malignant Perinatal Variant of Long-QT Syndrome Caused by a Profoundly Dysfunctional Cardiac Sodium Channel

    PubMed Central

    Wang, Dao W.; Crotti, Lia; Shimizu, Wataru; Pedrazzini, Matteo; Cantu', Francesco; De Filippo, Paolo; Kishiki, Kanako; Miyazaki, Aya; Ikeda, Tomoaki; Schwartz, Peter J.; George, Alfred L.

    2009-01-01

    Background Inherited cardiac arrhythmia susceptibility contributes to sudden death during infancy and may contribute to perinatal and neonatal mortality, but the molecular basis of this risk and the relationship to genetic disorders presenting later in life is unclear. We studied the functional and pharmacological properties of a novel de novo cardiac sodium channel gene (SCN5A) mutation associated with an extremely severe perinatal presentation of long-QT syndrome in unrelated probands of different ethnicity. Methods and Results Two subjects exhibiting severe fetal and perinatal ventricular arrhythmias were screened for SCN5A mutations and the functional properties of a novel missense mutation (G1631D) were determined by whole-cell patch clamp recording. In vitro electrophysiological studies revealed a profound defect in sodium channel function characterized by ~10-fold slowing of inactivation, increased persistent current, slowing of recovery from inactivation, depolarized voltage dependence of activation and inactivation. Single channel recordings demonstrated increased frequency of late openings, prolonged mean open time and increased latency to first opening for the mutant. Subjects carrying this mutation responded clinically to the combination of mexiletine with propranolol and survived. Pharmacologically, the mutant exhibited 2-fold greater tonic and use-dependent mexiletine block than wildtype channels. The mutant also exhibited enhanced tonic (2.4-fold) and use-dependent block (~5-fold) by propranolol, and we observed additive effects of the two drugs on the mutant. Conclusions Our study demonstrates the molecular basis for a malignant perinatal presentation of long-QT syndrome, illustrates novel functional and pharmacological properties of SCN5A-G1631D which caused the disorder, and reveals therapeutic benefits of propranolol block of mutant sodium channels in this setting. PMID:19808432

  16. When I go in to wake them ... I wonder: parental perceptions about congenital long QT syndrome.

    PubMed

    Farnsworth, Monica M; Fosyth, Diane; Haglund, Carla; Ackerman, Michael J

    2006-06-01

    Congenital long QT syndrome (LQTS) affects an estimated 1 in 5,000 persons, is characterized by QT interval prolongation, and has a clinical presentation ranging from asymptomatic longevity to sudden death in the young as the initial event. The purpose of this study was to describe the experiences of parents who have a child or children with LQTS. Information from parents of children with this diagnosis can provide insight to healthcare providers who care for these families. The literature reveals that very little is known about the psychosocial aspects of this potential sudden death syndrome. This was a secondary analysis of a 2002 qualitative phenomenological primary study done to explore fear of death and quality of life for 58 patients with LQTS. The secondary study analyzed responses derived from 31 parents of children with LQTS. We speculated this far-reaching clinical spectrum would arouse fear and uncertainty for a parent of a child with LQTS. Results of the study revealed that parents with young children described fear of their children dying and strategies they used to manage their fear, as well as frustrations about lack of knowledge of LQTS among healthcare providers. When the diagnosis of LQTS is established during adolescence, the impact on the lives of children and their families is more significant. In order to support families experiencing the stress of living daily with someone with LQTS, healthcare providers including nurse practitioners need a better understanding of the symptoms, diagnosis, management, and lifestyle implications of LQTS. Further studies are needed to understand the long-term psychosocial effects of children on beta-blockers, children with implantable cardioverter defibrillators, and children, adolescents, and young adults who survive a sudden death event.

  17. In silico screening of the impact of hERG channel kinetic abnormalities on channel block and susceptibility to acquired long QT syndrome

    PubMed Central

    Romero, Lucia; Trenor, Beatriz; Yang, Pei-Chi; Saiz, Javier; Clancy, Colleen E.

    2016-01-01

    Accurate diagnosis of predisposition to long QT syndrome is crucial for reducing the risk of cardiac arrhythmias. In recent years, drug-induced provocative tests have proved useful to unmask some latent mutations linked to cardiac arrhythmias. In this study we expanded this concept by developing a prototype for a computational provocative screening test to reveal genetic predisposition to acquired long-QT syndrome (aLQTS). We developed a computational approach to reveal the pharmacological properties of IKr blocking drugs that are most likely to cause aLQTS in the setting of subtle alterations in IKr channel gating that would be expected to result from benign genetic variants. We used the model to predict the most potentially lethal combinations of kinetic anomalies and drug properties. In doing so, we also implicitly predicted ideal inverse therapeutic properties of K channel openers that would be expected to remedy a specific defect. We systematically performed “in silico mutagenesis” by altering discrete kinetic transition rates of the Fink et al. Markov model of human IKr channels, corresponding to activation, inactivation, deactivation and recovery from inactivation of IKr channels. We then screened and identified the properties of IKr blockers that caused acquired long QT and therefore unmasked mutant phenotypes for mild, moderate and severe variants. Mutant IKr channels were incorporated into the O'Hara et al. human ventricular action potential (AP) model and subjected to simulated application of a wide variety of IKr–drug interactions in order to identify the characteristics that selectively exacerbate the AP duration (APD) differences between wild-type and IKr mutated cells. Our results show that drugs with disparate affinities to conformation states of the IKr channel are key to amplify variants underlying susceptibility to acquired long QT syndrome, an effect that is especially pronounced at slow frequencies. Finally, we developed a mathematical

  18. In silico screening of the impact of hERG channel kinetic abnormalities on channel block and susceptibility to acquired long QT syndrome

    PubMed Central

    Romero, Lucia; Trenor, Beatriz; Yang, Pei-Chi; Saiz, Javier; Clancy, Colleen E.

    2014-01-01

    Accurate diagnosis of predisposition to long QT syndrome is crucial for reducing the risk of cardiac arrhythmias. In recent years, drug-induced provocative tests have proved useful to unmask some latent mutations linked to cardiac arrhythmias. In this study we expanded this concept by developing a prototype for a computational provocative screening test to reveal genetic predisposition to acquired Long-QT Syndrome (aLTQS). We developed a computational approach to reveal the pharmacological properties of IKr blocking drugs that are most likely to cause aLQTS in the setting of subtle alterations in IKr channel gating that would be expected to result from benign genetic variants. We used the model to predict the most potentially lethal combinations of kinetic anomalies and drug properties. In doing so, we also implicitly predicted ideal inverse therapeutic properties of K channel openers that would be expected to remedy a specific defect. We systematically performed “in silico mutagenesis” by altering discrete kinetic transition rates of the Fink et al. Markov model of human IKr channels, corresponding to activation, inactivation, deactivation and recovery from inactivation of IKr channels. We then screened and identified the properties of IKr blockers that caused acquired Long QT and therefore unmasked mutant phenotypes for mild, moderate and severe variants. Mutant IKr channels were incorporated into the O’Hara et al. human ventricular action potential (AP) model and subjected to simulated application of a wide variety of IKr-drug interactions in order to identify the characteristics that selectively exacerbate the AP duration (APD) differences between wild-type and IKr mutated cells. Our results show that drugs with disparate affinities to conformation states of the IKr channel are key to amplify variants underlying susceptibility to acquired Long QT Syndrome, an effect that is especially pronounced at slow frequencies. Finally, we developed a mathematical

  19. In silico screening of the impact of hERG channel kinetic abnormalities on channel block and susceptibility to acquired long QT syndrome.

    PubMed

    Romero, Lucia; Trenor, Beatriz; Yang, Pei-Chi; Saiz, Javier; Clancy, Colleen E

    2015-10-01

    Accurate diagnosis of predisposition to long QT syndrome is crucial for reducing the risk of cardiac arrhythmias. In recent years, drug-induced provocative tests have proved useful to unmask some latent mutations linked to cardiac arrhythmias. In this study we expanded this concept by developing a prototype for a computational provocative screening test to reveal genetic predisposition to acquired long-QT syndrome (aLQTS). We developed a computational approach to reveal the pharmacological properties of I(Kr) blocking drugs that are most likely to cause aLQTS in the setting of subtle alterations in I(Kr) channel gating that would be expected to result from benign genetic variants.Weused themodel to predict themost potentially lethal combinations of kinetic anomalies and drug properties. In doing so, we also implicitly predicted ideal inverse therapeutic properties of K channel openers that would be expected to remedy a specific defect. We systematically performed “in silico mutagenesis” by altering discrete kinetic transition rates of the Fink et al. Markov model of human I(Kr) channels, corresponding to activation, inactivation, deactivation and recovery from inactivation of I(Kr) channels. We then screened and identified the properties of I(Kr) blockers that caused acquired long QT and therefore unmasked mutant phenotypes formild,moderate and severe variants. Mutant I(Kr) channels were incorporated into the O'Hara et al. human ventricular action potential (AP) model and subjected to simulated application of a wide variety of I(Kr)-drug interactions in order to identify the characteristics that selectively exacerbate the AP duration (APD) differences between wild-type and I(Kr) mutated cells. Our results show that drugs with disparate affinities to conformation states of the I(Kr) channel are key to amplify variants underlying susceptibility to acquired long QT syndrome, an effect that is especially pronounced at slow frequencies. Finally, we developed a

  20. In silico screening of the impact of hERG channel kinetic abnormalities on channel block and susceptibility to acquired long QT syndrome.

    PubMed

    Romero, Lucia; Trenor, Beatriz; Yang, Pei-Chi; Saiz, Javier; Clancy, Colleen E

    2014-07-01

    Accurate diagnosis of predisposition to long QT syndrome is crucial for reducing the risk of cardiac arrhythmias. In recent years, drug-induced provocative tests have proved useful to unmask some latent mutations linked to cardiac arrhythmias. In this study we expanded this concept by developing a prototype for a computational provocative screening test to reveal genetic predisposition to acquired long-QT syndrome (aLQTS). We developed a computational approach to reveal the pharmacological properties of IKr blocking drugs that are most likely to cause aLQTS in the setting of subtle alterations in IKr channel gating that would be expected to result from benign genetic variants. We used the model to predict the most potentially lethal combinations of kinetic anomalies and drug properties. In doing so, we also implicitly predicted ideal inverse therapeutic properties of K channel openers that would be expected to remedy a specific defect. We systematically performed "in silico mutagenesis" by altering discrete kinetic transition rates of the Fink et al. Markov model of human IKr channels, corresponding to activation, inactivation, deactivation and recovery from inactivation of IKr channels. We then screened and identified the properties of IKr blockers that caused acquired long QT and therefore unmasked mutant phenotypes for mild, moderate and severe variants. Mutant IKr channels were incorporated into the O'Hara et al. human ventricular action potential (AP) model and subjected to simulated application of a wide variety of IKr-drug interactions in order to identify the characteristics that selectively exacerbate the AP duration (APD) differences between wild-type and IKr mutated cells. Our results show that drugs with disparate affinities to conformation states of the IKr channel are key to amplify variants underlying susceptibility to acquired long QT syndrome, an effect that is especially pronounced at slow frequencies. Finally, we developed a mathematical

  1. Prevalence and Spectrum of Large Deletions or Duplications in the Major Long QT Syndrome-Susceptibility Genes and Implications for Long QT Syndrome Genetic Testing

    PubMed Central

    Tester, David J.; Benton, Amber J.; Train, Laura; Deal, Barbara; Baudhuin, Linnea M.; Ackerman, Michael J.

    2010-01-01

    Long QT Syndrome (LQTS) is a cardiac channelopathy associated with syncope, seizures, and sudden death. Approximately 75% of LQTS is due to mutations in genes encoding for three cardiac ion channel alpha-subunits (LQT1-3). However, traditional mutational analyses have limited detection capabilities for atypical mutations such as large gene rearrangements. Here, we set out to determine the prevalence and spectrum of large deletions/duplications in the major LQTS-susceptibility genes among unrelated patients who were mutation-negative following point mutation analysis of LQT1-12-susceptibility genes. Forty-two unrelated clinically strong LQTS patients were analyzed using multiplex ligation-dependent probe amplification (MLPA), a quantitative fluorescent technique for detecting multiple exon deletions and duplications. The SALSA-MLPA LQTS Kit from MRC-Holland was used to analyze the three major LQTS-associated genes: KCNQ1, KCNH2, and SCN5A and the two minor genes: KCNE1 and KCNE2. Overall, 2 gene rearrangements were found in 2/42 (4.8%, CI, 1.7–11%) unrelated patients. A deletion of KCNQ1 exon 3 was identified in a 10 year-old Caucasian boy with a QTc of 660 milliseconds (ms), a personal history of exercise-induced syncope, and a family history of syncope. A deletion of KCNQ1 exon 7 was identified in a 17 year-old Caucasian girl with a QTc of 480 ms, a personal history of exercise-induced syncope, and a family history of sudden cardiac death. In conclusion, since nearly 5% of patients with genetically elusive LQTS had large genomic rearrangements involving the canonical LQTS-susceptibility genes, reflex genetic testing to investigate genomic rearrangements may be of clinical value. PMID:20920651

  2. Therapeutic hypothermia after cardiac arrest in Long QT syndrome: Could it be an adjunctive treatment to prevent dysrhythmias?

    PubMed

    Jatti, Kumar; Prasad, Neeraj

    2015-01-01

    Therapeutic hypothermia has been used for neuroprotection following cardiac arrest presenting with ventricular tachycardia or ventricular fibrillation regardless of underlying cause. Long QT syndrome is a cause for polymorphic ventricular tachycardia, and we know that therapeutic hypothermia increases the QT interval. We managed a 27-year-old woman, who was 10 weeks post-partum, who collapsed secondary to ventricular fibrillation at home. Bystander cardiopulmonary resuscitation was started with successful resuscitation after a rescue shock from paramedics. On hospital admission, her computerised tomography head, computerised tomography pulmonary angiogram and echocardiography did not show any abnormality. Her baseline electrocardiogram showed prolonged QTc interval of 504 ms without ischaemic changes. After intubation and ventilation, she was treated with therapeutic hypothermia for 48 h. She had a further episode of polymorphic ventricular tachycardia requiring rescue shock just prior to starting therapeutic hypothermia in hospital. No dysrhythmias occurred during therapeutic hypothermia, although the QTc further increased. After stopping the therapeutic hypothermia, she had two further ventricular tachycardia episodes. After commencement of beta blockers, she remained free of arrhythmias, and an implantable cardioverter defibrillator was implanted, she has recovered without any neurological deficit. Ventricular dysrhythmias caused by prolongation of the QT interval during or after therapeutic hypothermia are not well understood. There has been a report of a patient also having ventricular dysrhythmia 2 h after re-warming post therapeutic hypothermia and also a report of arrhythmia free period during therapeutic hypothermia in a long QT syndrome patient; both these features are present in our patient. Re-warming is not usually known to cause any arrhythmias; however, it could be a problem in those with long QT syndrome. Whether therapeutic hypothermia has

  3. A Novel SCN5A Mutation Found in a Familial Case of Long QT Syndrome Complicated by Severe Left Ventricular Dysfunction.

    PubMed

    Kimura, Mai; Kohno, Takashi; Aizawa, Yoshiyasu; Inohara, Taku; Shiraishi, Yasuyuki; Katsumata, Yoshinori; Egashira, Toru; Fukushima, Hiroyuki; Kosaki, Kenjiro; Fukuda, Keiichi

    2017-04-01

    A 16-year-old boy with long QT syndrome type 3 (LQT3) was admitted for decompensated heart failure resulting from dilated cardiomyopathy (DCM). His brother was also diagnosed with LQT3 and DCM. A comprehensive genetic analysis identified a novel SCN5A missense mutation-p.Q371E-in these 2 affected living family members. It might be important to suspect the coexistence of DCM and LQT3 (which is rare according to previous articles) in cases with this novel SCN5A missense mutation.

  4. Functional interaction between DPI 201-106, a drug that mimics congenital long QT syndrome, and sevoflurane on the guinea-pig cardiac action potential.

    PubMed

    Kang, Jiesheng; Chen, Xiao-Liang; Reynolds, William P; Rampe, David

    2007-12-01

    1. Sevoflurane produces QT prolongation on the electrocardiogram, predominantly via inhibition of the slow delayed rectifier K(+) current. DPI 201-106 is an experimental drug that produces QT prolongation by reducing Na(+) channel inactivation, thereby mimicking congenital long QT syndrome type 3 (LQT3). The present study explores the electrophysiological consequences of administration of sevoflurane in the presence of impaired Na(+) channel activity. 2. We examined the effects of sevoflurane and DPI 201-106, alone and in combination, on the cardiac action potential of guinea-pig ventricular myocytes using standard microelectrode techniques. 3. Both sevoflurane and DPI-201-106 prolonged action potential duration, with the combination of the two drugs producing greater than additive effects. Similarly, instability and triangulation of the action potential waveform, measures of pro-arrhythmia, were more pronounced when both drugs were combined. 4. Sevoflurane treatment significantly alters cardiac action potential waveforms when administered in the presence of impaired Na(+) channel inactivation. These results indicate the potential for ventricular arrhythmia when sevoflurane is administered to LQT3 patients and suggests caution when using sevoflurane in this population.

  5. Localization of Romano-Ward long QT syndrome gene, LQTI, to the interval between tyrosine hydroxylase (TH) and D11S1349

    SciTech Connect

    Russell, M.W. |; Hulse, J.E.; Campbell, R.M.

    1995-08-01

    The Romano-Ward long-QT syndrome (RWLQTS) is an autosomal dominant disorder that is characterized by heritable prolongation of the QT interval, syncope, and sudden death. Identification of the gene responsible for this syndrome may aid the diagnosis, management, and treatment of patients with this disease. Furthermore, it may lead to improved understanding of and therapy for other sympathetic-dependent ventricular arrhythmias. 20 refs., 1 fig., 1 tab.

  6. Genetic analysis, in silico prediction, and family segregation in long QT syndrome.

    PubMed

    Riuró, Helena; Campuzano, Oscar; Berne, Paola; Arbelo, Elena; Iglesias, Anna; Pérez-Serra, Alexandra; Coll-Vidal, Mònica; Partemi, Sara; Mademont-Soler, Irene; Picó, Ferran; Allegue, Catarina; Oliva, Antonio; Gerstenfeld, Edward; Sarquella-Brugada, Georgia; Castro-Urda, Víctor; Fernández-Lozano, Ignacio; Mont, Lluís; Brugada, Josep; Scornik, Fabiana S; Brugada, Ramon

    2015-01-01

    The heritable cardiovascular disorder long QT syndrome (LQTS), characterized by prolongation of the QT interval on electrocardiogram, carries a high risk of sudden cardiac death. We sought to add new data to the existing knowledge of genetic mutations contributing to LQTS to both expand our understanding of its genetic basis and assess the value of genetic testing in clinical decision-making. Direct sequencing of the five major contributing genes, KCNQ1, KCNH2, SCN5A, KCNE1, and KCNE2, was performed in a cohort of 115 non-related LQTS patients. Pathogenicity of the variants was analyzed using family segregation, allele frequency from public databases, conservation analysis, and Condel and Provean in silico predictors. Phenotype-genotype correlations were analyzed statistically. Sequencing identified 36 previously described and 18 novel mutations. In 51.3% of the index cases, mutations were found, mostly in KCNQ1, KCNH2, and SCN5A; 5.2% of cases had multiple mutations. Pathogenicity analysis revealed 39 mutations as likely pathogenic, 12 as VUS, and 3 as non-pathogenic. Clinical analysis revealed that 75.6% of patients with QTc≥500 ms were genetically confirmed. Our results support the use of genetic testing of KCNQ1, KCNH2, and SCN5A as part of the diagnosis of LQTS and to help identify relatives at risk of SCD. Further, the genetic tools appear more valuable as disease severity increases. However, the identification of genetic variations in the clinical investigation of single patients using bioinformatic tools can produce erroneous conclusions regarding pathogenicity. Therefore segregation studies are key to determining causality.

  7. Use of a cardioselective beta-blocker for pediatric patients with prolonged QT syndrome.

    PubMed

    Moltedo, Jose M; Kim, Jeffrey J; Friedman, Richard A; Kertesz, Naomi J; Cannon, Bryan C

    2011-01-01

    The data on the efficacy of atenolol for long-QT syndrome (LQTS) are controversial. This study aimed to evaluate the efficacy of atenolol for pediatric patients with LQTS. A retrospective observational study investigating all patients who had LQTS treated with atenolol at two institutions was performed. The study identified 57 patients (23 boys and 34 girls) with a mean QT corrected for heart rate (QTc) of 521 ± 54 ms. The mean age of these patients at diagnosis was 9 ± 6 years. Their clinical manifestations included no symptoms (n = 33, 58%), ventricular tachycardia (n = 10, 18%), syncope (n = 6, 10%), resuscitated sudden cardiac death (n = 4, 7%), atrioventricular block (n = 2, 4%), and bradycardia or presyncope (n = 2, 3%). Of the 57 patients, 13 (22%) had a family history of sudden death. The follow-up period was 5.4 ± 4.5 years. Atenolol at a mean dose of 1.4 ± 0.5 mg/kg/day was administered twice a day for all the patients. The mean maximum heart rate was 132 ± 27 bpm on Holter monitors and 155 ± 16 bpm on exercise treadmill tests, with medication doses titrated up to achieve a maximum heart rate lower than 150 bpm on both tests. During the follow-up period, one patient died (noncompliant with atenolol at the time of death), and the remaining patients had no sudden cardiac death events. Four patients (8%) had recurrent ventricular arrhythmias, three of whom received an implantable cardioverter defibrillator (all symptomatic at the time of diagnosis). For three patients (6%), it was necessary to rotate to a different beta-blocker because of side effects or inadequate heart rate control. Atenolol administered twice daily constitutes a valid and effective alternative for the treatment of pediatric patients with LQTS.

  8. Genetic analysis, in silico prediction, and family segregation in long QT syndrome

    PubMed Central

    Riuró, Helena; Campuzano, Oscar; Berne, Paola; Arbelo, Elena; Iglesias, Anna; Pérez-Serra, Alexandra; Coll-Vidal, Mònica; Partemi, Sara; Mademont-Soler, Irene; Picó, Ferran; Allegue, Catarina; Oliva, Antonio; Gerstenfeld, Edward; Sarquella-Brugada, Georgia; Castro-Urda, Víctor; Fernández-Lozano, Ignacio; Mont, Lluís; Brugada, Josep; Scornik, Fabiana S; Brugada, Ramon

    2015-01-01

    The heritable cardiovascular disorder long QT syndrome (LQTS), characterized by prolongation of the QT interval on electrocardiogram, carries a high risk of sudden cardiac death. We sought to add new data to the existing knowledge of genetic mutations contributing to LQTS to both expand our understanding of its genetic basis and assess the value of genetic testing in clinical decision-making. Direct sequencing of the five major contributing genes, KCNQ1, KCNH2, SCN5A, KCNE1, and KCNE2, was performed in a cohort of 115 non-related LQTS patients. Pathogenicity of the variants was analyzed using family segregation, allele frequency from public databases, conservation analysis, and Condel and Provean in silico predictors. Phenotype-genotype correlations were analyzed statistically. Sequencing identified 36 previously described and 18 novel mutations. In 51.3% of the index cases, mutations were found, mostly in KCNQ1, KCNH2, and SCN5A; 5.2% of cases had multiple mutations. Pathogenicity analysis revealed 39 mutations as likely pathogenic, 12 as VUS, and 3 as non-pathogenic. Clinical analysis revealed that 75.6% of patients with QTc≥500 ms were genetically confirmed. Our results support the use of genetic testing of KCNQ1, KCNH2, and SCN5A as part of the diagnosis of LQTS and to help identify relatives at risk of SCD. Further, the genetic tools appear more valuable as disease severity increases. However, the identification of genetic variations in the clinical investigation of single patients using bioinformatic tools can produce erroneous conclusions regarding pathogenicity. Therefore segregation studies are key to determining causality. PMID:24667783

  9. Arrhythmia risk and β-blocker therapy in pregnant women with long QT syndrome.

    PubMed

    Ishibashi, Kohei; Aiba, Takeshi; Kamiya, Chizuko; Miyazaki, Aya; Sakaguchi, Heima; Wada, Mitsuru; Nakajima, Ikutaro; Miyamoto, Koji; Okamura, Hideo; Noda, Takashi; Yamauchi, Toshifumi; Itoh, Hideki; Ohno, Seiko; Motomura, Hideki; Ogawa, Yoshiharu; Goto, Hiroko; Minami, Takaomi; Yagihara, Nobue; Watanabe, Hiroshi; Hasegawa, Kanae; Terasawa, Akihiro; Mikami, Hitoshi; Ogino, Kayo; Nakano, Yukiko; Imashiro, Sato; Fukushima, Yosuke; Tsuzuki, Yoshimitsu; Asakura, Koko; Yoshimatsu, Jun; Shiraishi, Isao; Kamakura, Shiro; Miyamoto, Yoshihiro; Yasuda, Satoshi; Akasaka, Takashi; Horie, Minoru; Shimizu, Wataru; Kusano, Kengo

    2017-09-01

    Pregnancy is one of the biggest concerns for women with long QT syndrome (LQTS). This study investigated pregnancy-related arrhythmic risk and the efficacy and safety of β-blocker therapy for lethal ventricular arrhythmias in pregnant women with LQTS (LQT-P) and their babies. 136 pregnancies in 76 LQT-P (29±5 years old; 22 LQT1, 36 LQT2, one LQT3, and 17 genotype-unknown) were enrolled. We retrospectively analysed their clinical and electrophysiological characteristics and pregnancy outcomes in the presence (BB group: n=42) or absence of β-blocker therapy (non-BB group: n=94). All of the BB group had been diagnosed with LQTS with previous events, whereas 65% of the non-BB group had not been diagnosed at pregnancy. Pregnancy increased heart rate in the non-BB group; however, no significant difference was observed in QT and Tpeak-Tend intervals between the two groups. In the BB group, only two events occurred at postpartum, whereas 12 events occurred in the non-BB group during pregnancy (n=6) or postpartum period (n=6). The frequency of spontaneous abortion did not differ between the two groups. Fetal growth rate and proportion of infants with congenital malformation were similar between the two groups, but premature delivery and low birthweight infants were more common in those taking BB (OR 4.79, 95% CI 1.51 to 15.21 and OR 3.25, 95% CI 1.17 to 9.09, respectively). Early diagnosis and β-blocker therapy for high-risk patients with LQTS are important for prevention of cardiac events during pregnancy and the postpartum period, and β-blocker therapy may be tolerated for babies in LQT-P cases. © Article author(s) (or their employer(s) unless otherwise stated in the text of the article) 2017. All rights reserved. No commercial use is permitted unless otherwise expressly granted.

  10. Cardiovascular Effects of Energy Drinks in Familial Long QT Syndrome: A Randomized Cross-Over Study.

    PubMed

    Gray, Belinda; Ingles, Jodie; Medi, Caroline; Driscoll, Timothy; Semsarian, Christopher

    2017-03-15

    Caffeinated energy drinks may trigger serious cardiac effects. The aim of this study was to determine the cardiovascular effects of caffeinated energy drink consumption in patients with familial long QT syndrome (LQTS). From 2014-2016, 24 LQTS patients aged 16-50 years were recruited to a randomized, double-blind, cross-over study of energy drink (ED) versus control (CD) with participants acting as their own controls (one week washout). The primary study outcome was an increase in corrected QT interval (QTc) by >20ms. Secondary outcomes were changes in systolic and diastolic blood pressure. In 24 patients with LQTS (no dropout), mean age was 29±9 years, 13/24 (54%) were female, and 8/24 (33%) were probands. Intention to treat analysis revealed no significant change in QTc with ED compared with CD (12±28ms vs 16±27ms, 3% vs 4%, p=0.71). The systolic and diastolic blood pressure significantly increased with ED compared to CD (peak change 7±16mmHg vs 1±16mmHg, 6% vs 0.8%, p=0.046 and 8±10 vs 2±9mmHg, 11% vs 3% p=0.01 respectively). These changes correlated with significant increases in serum caffeine (14.6±11.3 vs 0.5±0.1μmol/L, p<0.001) and serum taurine (737±199 vs -59±22μmol/L, p<0.001). There were three patients with dangerous QTc prolongation of ≥50ms following energy drink consumption. Caffeinated energy drinks have significant haemodynamic effects in patients with LQTS, especifically an acute increase in blood pressure. Since dangerous QTc prolongation was seen in some LQTS patients, we recommend caution in young patients with LQTS consuming energy drinks. Copyright © 2016 Elsevier Ireland Ltd. All rights reserved.

  11. Beat-to-beat T-wave amplitude variability in the long QT syndrome.

    PubMed

    Extramiana, Fabrice; Tatar, Charif; Maison-Blanche, Pierre; Denjoy, Isabelle; Messali, Anne; Dejode, Patrick; Iserin, Frank; Leenhardt, Antoine

    2010-09-01

    Long QT syndrome (LQTS) is a primary electrical disease characterized by QT prolongation and increased repolarization dispersion leading to T-wave amplitude beat-to-beat changes. We aimed to quantify beat-to-beat T-wave amplitude variability from ambulatory Holter recordings in genotyped LQTS patients. Seventy genotyped LQTS patients (mean age 23 +/- 15 years, 42 males, 50% LQT1, 39% LQT2, and 11% LQT3) and 70 normal matched control subjects underwent a 24-h digital Holter recording. Using the Tvar software (Ela Medical, Sorin group), the beat-to-beat variance of the T-wave amplitude (TAV in microV) [corrected] was assessed on 50-ms consecutive clusters during three 1-h periods: one with around average diurnal heart rate (Day Fast), one nocturnal period (Night), and one diurnal period with around average nocturnal heart rate (Day Slow). TAV was increased in LQTS patients during the two diurnal periods but not at night (during the Day Fast period, mean TAV was 34 +/- 20 microV [corrected] in LQTS patients vs. 27 +/- 10 microV [corrected] in controls, P < 0.05). This effect depended on the genotype. In LQT1, TAV was larger when compared with controls for both Day Fast and Slow periods, but in LQT2 only Day Fast shows higher TAV. Oppositely, in LQT3 the TAV was higher than in the control group during the Day slow period (mean TAV = 34 +/- 20 vs. 25 +/- 8 microV [corrected] in controls, P < 0.05). In genotyped LQTS patients beat-to-beat T-wave amplitude variability was increased when compared with control subjects. That pattern was modulated by circadian influences in a gene-dependent manner.

  12. A fatal combination in an old lady: Tako-Tsubo cardiomyopathy, long QT syndrome, and cardiac hypertrophy.

    PubMed

    Wedekind, Horst; Müller, Joachim G; Ribbing, Michael; Skurzewski, Paul; Bozzetti, Christoph; Meyer-Krahmer, Hans-Joachim; Böcker, Dirk

    2009-06-01

    Tako-Tsubo cardiomyopathy (TT-CM), also called stress-induced cardiomyopathy or transient left ventricular (LV) apical ballooning syndrome, is characterized by transient apical or midventricular LV dysfunction that mimics myocardial infarction, but in the absence of significant coronary artery disease. The onset of TT-CM is typically triggered by an acute medical illness or by intense emotional, psychological, or physical stress. During the acute phase, a disturbed repolarization with QT prolongation in the surface ECG is frequently obvious. Despite the generally good prognosis of TT-CM, severe clinical courses have been reported due to the depressed LV function with cardiogenic shock or malignant tachyarrhythmias. We report an unusual presentation of a patient with TT-CM and recurrent episodes of torsades de pointes tachyarrhythmias. In this patient, we identified pre- and coexisting congenital long QT syndrome and severe cardiac hypertrophy--all of them associated with disturbed myocardial repolarization and predisposed the patient to malignant tachyarrhythmias.

  13. Allele-specific RNA interference rescues the long-QT syndrome phenotype in human-induced pluripotency stem cell cardiomyocytes

    PubMed Central

    Matsa, Elena; Dixon, James E.; Medway, Christopher; Georgiou, Orestis; Patel, Minal J.; Morgan, Kevin; Kemp, Paul J.; Staniforth, Andrew; Mellor, Ian; Denning, Chris

    2014-01-01

    Aims Long-QT syndromes (LQTS) are mostly autosomal-dominant congenital disorders associated with a 1:1000 mutation frequency, cardiac arrest, and sudden death. We sought to use cardiomyocytes derived from human-induced pluripotency stem cells (hiPSCs) as an in vitro model to develop and evaluate gene-based therapeutics for the treatment of LQTS. Methods and results We produced LQTS-type 2 (LQT2) hiPSC cardiomyocytes carrying a KCNH2 c.G1681A mutation in a IKr ion-channel pore, which caused impaired glycosylation and channel transport to cell surface. Allele-specific RNA interference (RNAi) directed towards the mutated KCNH2 mRNA caused knockdown, while leaving the wild-type mRNA unaffected. Electrophysiological analysis of patient-derived LQT2 hiPSC cardiomyocytes treated with mutation-specific siRNAs showed normalized action potential durations (APDs) and K+ currents with the concurrent rescue of spontaneous and drug-induced arrhythmias (presented as early-afterdepolarizations). Conclusions These findings provide in vitro evidence that allele-specific RNAi can rescue diseased phenotype in LQTS cardiomyocytes. This is a potentially novel route for the treatment of many autosomal-dominant-negative disorders, including those of the heart. PMID:23470493

  14. Gain-of-function mutations in the calcium channel CACNA1C (Cav1.2) cause non-syndromic long-QT but not Timothy syndrome.

    PubMed

    Wemhöner, Konstantin; Friedrich, Corinna; Stallmeyer, Birgit; Coffey, Alison J; Grace, Andrew; Zumhagen, Sven; Seebohm, Guiscard; Ortiz-Bonnin, Beatriz; Rinné, Susanne; Sachse, Frank B; Schulze-Bahr, Eric; Decher, Niels

    2015-03-01

    Gain-of-function mutations in CACNA1C, encoding the L-type Ca(2+) channel Cav1.2, cause Timothy syndrome (TS), a multi-systemic disorder with dysmorphic features, long-QT syndrome (LQTS) and autism spectrum disorders. TS patients have heterozygous mutations (G402S and G406R) located in the alternatively spliced exon 8, causing a gain-of-function by reduced voltage-dependence of inactivation. Screening 540 unrelated patients with non-syndromic forms of LQTS, we identified six functional relevant CACNA1C mutations in different regions of the channel. All these mutations caused a gain-of-function combining different mechanisms, including changes in current amplitude, rate of inactivation and voltage-dependence of activation or inactivation, similar as in TS. Computer simulations support the theory that the novel CACNA1C mutations prolong action potential duration. We conclude that genotype-negative LQTS patients should be investigated for mutations in CACNA1C, as a gain-of-function in Cav1.2 is likely to cause LQTS and only specific and rare mutations, i.e. in exon 8, cause the multi-systemic TS.

  15. Novel characteristics of a trafficking-defective G572R-hERG channel linked to hereditary long QT syndrome.

    PubMed

    Lian, Jiangfang; Huang, Na; Zhou, Junbo; Ge, Shijun; Huang, Xiaoyan; Huo, Jianhua; Liu, Liying; Xu, Weifeng; Zhang, Shun; Yang, Xi; Zhou, Jianqing; Huang, Chen

    2010-10-01

    HISTORIQUE : Le syndrome du QT long congénital est une maladie génétique hétérogène associée à un retard de la repolarisation cardiaque, à des intervalles QT prolongés, à l'apparition d'arythmies ventriculaires et à une mort subite. Le syndrome du QT long congénital de type 2 (QTL2) est causé par des mutations du gène KCNH2 ou hERG. Le gène hERG code la sous-unité alpha K11.1 du canal K+ redresseur retardé du cœur qui s'active rapidement. Des études des canaux hERG mutants indiquent que la plupart des mutations faux-sens QTL2 produisent des canaux K11.1 au trafic défectueux. OBJECTIF : Dépister les mécanismes sous-jacents du canal G572R-hERG au moyen d'analyses moléculaires et électrophysiologiques. MÉTHODOLOGIE ET RÉSULTATS : Afin d'établir les propriétés électrophysiologiques des canaux mutants G572R-hERG, les sous-unités mutantes hERG étaient exprimées de manière hétérologue dans des cellules HEK293, seules ou en combinaison avec des sous-unités hERG de type sauvage (WT). Les techniques du patch-clamp ont permis d'enregistrer les courants, tandis que le marquage des protéines par double immunofluorescence et le transfert Western ont permis d'examiner le trafic cellulaire des sous-unités mutantes. Exprimées seules, les sous-unités G572R-hERG étaient absentes de la membrane cellulaire et ne produisaient pas de courants décelables. Coexprimé avec les sous-unités WT-hERG, le canal G572R-hERG réduisait la densité du courant et modifiait les propriétés de synchronisation du canal WT-hERG. CONCLUSION : La mutation faux-sens du gène G572R associée au gène hERG, comme la plupart des mutations faux-sens QTL2, produit un phénotype au trafic défectueux. De plus, le canal G572R-hERG entraîne une perte de fonction du gène hERG par son puissant effet négatif dominant sur le canal WT-hERG.

  16. Nadolol block of Nav1.5 does not explain its efficacy in the long QT syndrome.

    PubMed

    Besana, Alessandra; Wang, Dao W; George, Alfred L; Schwartz, Peter J

    2012-03-01

    Beta-adrenergic receptor antagonists (β-blockers) are the therapy of choice for the long QT syndrome but their efficacy is not homogeneous: propranolol and nadolol are the most effective, whereas metoprolol is associated with more treatment failures. Propranolol has a blocking effect on the sodium current ("membrane-stabilizing" effect), and it has been hypothesized that the efficacy of nadolol might be due to a similar effect. Accordingly, we used whole-cell patch-clamp recording to assess propranolol, nadolol, and metoprolol block of wild-type or mutant cardiac sodium channels (Nav1.5) coexpressed with β1 subunit in tsA201 cells. Nadolol had a ∼20% non-use-dependent blocking effect on peak sodium current and no effect on the persistent current evoked by the LQT3 mutant A1330D, whereas propranolol blocked Nav1.5 in a use-dependent manner and reduced A1330D persistent current. Metoprolol had no effect on either the peak or persistent current. Analysis of the biophysical properties of the channel revealed that both nadolol and propranolol cause hyperpolarizing shifts on voltage dependence of activation and steady-state inactivation, whereas metoprolol shifts only the activation curve. These results provide partial explanation for the differences between nadolol and metoprolol but do not explain the similar clinical efficacy of nadolol and propranolol.

  17. Impact of Gene Patents and Licensing Practices on Access to Genetic Testing for Long QT Syndrome

    PubMed Central

    Angrist, Misha; Chandrasekharan, Subhashini; Heaney, Christopher; Cook-Deegan, Robert

    2010-01-01

    Genetic testing for Long QT syndrome (LQTS) exemplifies patenting and exclusive licensing with different outcomes at different times. Exclusive licensing from the University of Utah changed the business model from sole provider to two US providers of LQTS testing. LQTS is associated with mutations in many genes, ten of which are now tested by two competing firms in the United States, PGxHealth and GeneDx. Until 2009, PGxHealth was sole provider, based largely on exclusive rights to patents from the University of Utah and other academic institutions. University of Utah patents were initially licensed to DNA Sciences, whose patent rights were acquired by Gennaissance, and then by Clinical Data, Inc., which owns PGxHealth. In 2002, DNA Sciences “cleared the market” by sending cease and desist patent enforcement letters to university and reference laboratories offering LQTS genetic testing. There was no test on the market for a one- to two-year period. From 2005-2008, most LQTS-related patents were controlled by Clinical Data, Inc., and its subsidiary PGxHealth. BioReference Laboratories, Inc., secured countervailing exclusive patent rights starting in 2006, also from the University of Utah, and broke the PGxHealth monopoly in early 2009, creating a duopoly for genetic testing in the United States, and expanding the number of genes for which commercial testing is available from five to ten. PMID:20393304

  18. Maternal and neonatal outcomes in labor and at delivery when long QT syndrome is present.

    PubMed

    Tanaka, Hiroaki; Katsuragi, Shinji; Tanaka, Kayo; Sawada, Masami; Iwanaga, Naoko; Yoshimatsu, Jun; Ikeda, Tomoaki

    2016-01-01

    Women during labor may be susceptible to torsades de pointes (TdP), which may cause the fetal condition to deteriorate. The aim of the present investigation was to analyze maternal and fetal outcomes during labor when long QT syndrome (LQTS) was present. We examined the maternal and neonatal outcomes of 25 pregnancies (18 women) with LQT between 1995 and 2012 at the Department of Perinatology, National Cardiovascular Center, Japan. Maternal and neonatal outcomes including cardiovascular events, cardiovascular events within a week after delivery, caesarean delivery rate, still births, preterm births, and non-reassuring fetal heart rate pattern (NRFHR) during labor were investigated. All the mothers survived, and no cardiovascular events occurred in labor or postpartum due to LQTS in either vaginal delivery or caesarean delivery. A total of 23 women (92%) had used beta blockers in this study. Caesarean delivery was performed due to NRFHR during labor in 5 pregnancies (20%). Delivery when LQTS is present has a low likelihood of cardiovascular events, but pregnancy with LQTS had a higher caesarean delivery rate due to NRFHR in labor. Most women used beta blockers in this study, and it is possible that beta blocker use prevents cardiovascular events during labor. NRFHR during labor may be related with inherited LQT through the mother.

  19. Case Report: Direct Access Genetic Testing and A False-Positive Result For Long QT Syndrome.

    PubMed

    Predham, Sarah; Hamilton, Sara; Elliott, Alison M; T Gibson, William

    2016-02-01

    We report the case of a woman who pursued direct access genetic testing and then presented with concerns regarding a positive test result for Long-QT syndrome. Although the result ultimately proved to be a false positive, this case illustrates that costs associated with follow-up of direct access genetic testing results can be non-trivial for both the patient and for health care systems. Here we raise policy questions regarding the appropriate distribution of these costs. We also discuss the possibility that, when confronted by a direct access genetic test result that reports high risk for one or more actionable diseases, a family physician might feel compelled to act out of a desire to avoid liability, even when information regarding the accuracy and validity of the testing were not easily accessible. This case outlines lessons that can easily be translated into clinical practice, not only by genetic counselors, but also by family physicians, medical specialists and members of the public.

  20. Mapping of a gene for long QT syndrome to chromosome 4q25-27

    SciTech Connect

    Schott, J.J.; Charpentier, F.; Peltier, S.

    1995-11-01

    Long QT syndrome (LQTS) is a heterogeneous inherited disorder causing syncope and sudden death from ventricular arrhythmias. A first locus for this disorder was mapped to chromosome 11p15.5. However, locus heterogeneity has been demonstrated in several families, and two other loci have recently been located on chromosomes 7q35-36 and 3p21-24. We used linkage analysis to map the locus in a 65-member family in which LQTS was associated with more marked sinus bradycardia than usual, leading to sinus node dysfunction. Linkage to chromosome 11p15.5, 7q35-36, or 3p21-24 was excluded. Positive linkage was obtained for markers located on chromosome 4q25-27. A maximal LOD score of 7.05 was found for marker D4S402. The identification of a fourth locus for LQTS confirms its genetic heterogeneity. Locus 4q25-27 is associated with a peculiar phenotype within the LQTS entity. 42 refs., 4 figs., 3 tabs.

  1. Novel missense mutation in the cyclic nucleotide-binding domain of HERG causes long QT syndrome

    SciTech Connect

    Satler, C.A.; Walsh, E.P.; Vesely, M.R.

    1996-10-02

    Autosomal-dominant long QT syndrome (LQT) is an inherited disorder, predisposing affected individuals to sudden death from tachyarrhythmias. To identify the gene(s) responsible for LQT, we identified and characterized an LQT family consisting of 48 individuals. DNA was screened with 150 microsatellite polymorphic markers encompassing approximately 70% of the genome. We found evidence for linkage of the LQT phenotype to chromosome 7(q35-36). Marker D7S636 yielded a maximum lod score of 6.93 at a recombination fraction ({theta}) of 0.00. Haplotype analysis further localized the LQT gene within a 6-2-cM interval. HERG encodes a potassium channel which has been mapped to this region. Single-strand conformational polymorphism analyses demonstrated aberrant bands that were unique to all affected individuals. DNA sequencing of the aberrant bands demonstrated a G to A substitution in all affected patients; this point mutation results in the substitution of a highly conserved valine residue with a methionine (V822M) in the cyclic nucleotide-binding domain of this potassium channel. The cosegregation of this distinct mutation with LQT demonstrates that HERG is the LQT gene in this pedigree. Furthermore, the location and character of this mutation suggests that the cyclic nucleotide-binding domain of the potassium channel encoded by HERG plays an important role in normal cardiac repolarization and may decrease susceptibility to ventricular tachyarrhythmias. 38 refs., 7 figs., 2 tabs.

  2. Cost-effectiveness analysis of genetic testing for familial long QT syndrome in symptomatic index cases.

    PubMed

    Phillips, Kathryn A; Ackerman, Michael J; Sakowski, Julie; Berul, Charles I

    2005-12-01

    Genetic testing for long QT syndrome (LQTS) has been available in a research setting for the past decade, and a commercial test has recently become available. However, the costs and effectiveness of genetic testing have not been estimated. The purpose of this study was to conduct a cost-effectiveness analysis of genetic testing in the management of patients who have or are suspected to have familial LQTS. We examined the incremental cost-effectiveness of genetic testing compared with no genetic testing for symptomatic index cases and how this varied according to changes in assumptions and data inputs. Data were obtained from the published literature and a clinical cohort. We found that genetic testing is more cost-effective than not testing for symptomatic index cases at an estimated cost of 2,500 US dollar per year of life saved. These results were generally robust, although they were sensitive to some data inputs such as the cost of testing and the mortality rate among untreated individuals with LQTS. A genetic test for familial LQTS is cost-effective relative to no testing, given our assumptions about the population to be tested and the relevant probabilities and costs. The primary benefit of testing is to more accurately diagnose and treat individuals based on a combination of clinical scores and test results. Future economic analyses of testing for familial LQTS should consider the potential benefits of genetic testing of broader populations, including family members.

  3. Late sodium current block for drug-induced long QT syndrome: Results from a prospective clinical trial.

    PubMed

    Johannesen, L; Vicente, J; Mason, J W; Erato, C; Sanabria, C; Waite-Labott, K; Hong, M; Lin, J; Guo, P; Mutlib, A; Wang, J; Crumb, W J; Blinova, K; Chan, D; Stohlman, J; Florian, J; Ugander, M; Stockbridge, N; Strauss, D G

    2016-02-01

    Drug-induced long QT syndrome has resulted in many drugs being withdrawn from the market. At the same time, the current regulatory paradigm for screening new drugs causing long QT syndrome is preventing drugs from reaching the market, sometimes inappropriately. In this study, we report the results of a first-of-a-kind clinical trial studying late sodium (mexiletine and lidocaine) and calcium (diltiazem) current blocking drugs to counteract the effects of hERG potassium channel blocking drugs (dofetilide and moxifloxacin). We demonstrate that both mexiletine and lidocaine substantially reduce heart-rate corrected QT (QTc) prolongation from dofetilide by 20 ms. Furthermore, all QTc shortening occurs in the heart-rate corrected J-Tpeak (J-Tpeak c) interval, the biomarker we identified as a sign of late sodium current block. This clinical trial demonstrates that late sodium blocking drugs can substantially reduce QTc prolongation from hERG potassium channel block and assessment of J-Tpeak c may add value beyond only assessing QTc. Published 2015. This article is a U.S. Government work and is in the public domain in the USA.

  4. Mechanisms of pharmacological rescue of trafficking defective hERG mutant channels in human long QT syndrome

    PubMed Central

    Gong, Qiuming; Jones, Melanie A.; Zhou, Zhengfeng

    2006-01-01

    Long QT syndrome type 2 is caused by mutations in the human ether-a-go-go-related gene (hERG). We previously reported that the N470D mutation is retained in the endoplasmic reticulum (ER) but can be rescued to the plasma membrane by hERG channel blocker E-4031. The mechanisms of ER retention and how E-4031 rescues the N470D mutant are poorly understood. In this study, we investigated the interaction of hERG channels with ER chaperone protein calnexin. Using coimmunoprecipitation, we showed that the immature forms of both wild type hERG and N470D associated with calnexin. The association required N-linked glycosylation of hERG channels. Pulse-chase analysis revealed that N470D had a prolonged association with calnexin compared to wild type hERG, and E-4031 shortened the time course of calnexin association with N470D. To test whether the prolonged association of N470D with calnexin is due to defective folding of mutant channels, we studied hERG channel folding using trypsin digestion method. We found that N470D and the immature form of wild type hERG were more sensitive to trypsin digestion than the mature form of wild type hERG. In the presence of E-4031, N470D became more resistant to trypsin even in the conditions that its ER-to-Golgi transport was blocked by brefeldin A. These results suggest that defective folding of N470D contributes to its prolonged association with calnexin and ER retention, and that E-4031 may restore proper folding of the N470D channel leading to its cell surface expression. PMID:16361248

  5. A high-risk patient with long-QT syndrome with no response to cardioselective beta-blockers.

    PubMed

    Toyota, Naoki; Miyazaki, Aya; Sakaguchi, Heima; Shimizu, Wataru; Ohuchi, Hideo

    2015-09-01

    We present a case of a high-risk 19-year-old female with long-QT syndrome (LQTS) with compound mutations. She had a history of aborted cardiac arrest and syncope and had received treatment with propranolol for 15 years. However, because she developed adult-onset asthma we tried to switch propranolol, a nonselective beta-blocker, to beta-1-cardioselective agents, bisoprolol and metoprolol. These resulted in both a markedly prolonged corrected QT interval and the development of LQTS-associated arrhythmias. Eventually, propranolol was reinitiated at a higher dose with the addition of verapamil, and she has had no further cardiac or asthmatic events for 5 years.

  6. Long QT, syndactyly, joint contractures, stroke and novel CACNA1C mutation: expanding the spectrum of Timothy syndrome.

    PubMed

    Gillis, Jane; Burashnikov, Elena; Antzelevitch, Charles; Blaser, Susan; Gross, Gil; Turner, Lesley; Babul-Hirji, Riyana; Chitayat, David

    2012-01-01

    Timothy syndrome (TS) is an autosomal dominant condition with the constellation of features including prolonged QT interval, hand and foot abnormalities, and mental retardation or autism. Splawski et al. [2004] previously described two phenotypes associated with TS distinguished by two unique and different mutations within the CACNA1C gene. We report on a newborn who presented with prolonged QT interval and associated polymorphic ventricular tachycardia, dysmorphic facial features, syndactyly of the hands and feet, and joint contractures, suggestive of TS. He developed a stroke, subsequent intractable seizures, and was found to have cortical blindness and later profound developmental delay. Initial targeted mutation analysis did not identify either of the previously described TS associated mutations; however, full gene sequencing detected a novel CACNA1C gene mutation (p.Ala1473Gly). The clinical and genetic findings in our case expand both the clinical and molecular knowledge of TS.

  7. BAG3-related myopathy, polyneuropathy and cardiomyopathy with long QT syndrome.

    PubMed

    Kostera-Pruszczyk, Anna; Suszek, Małgorzata; Płoski, Rafał; Franaszczyk, Maria; Potulska-Chromik, Anna; Pruszczyk, Piotr; Sadurska, Elżbieta; Karolczak, Justyna; Kamińska, Anna M; Rędowicz, Maria Jolanta

    2015-12-01

    BAG3 belongs to BAG family of molecular chaperone regulators interacting with HSP70 and anti-apoptotic protein Bcl-2. It is ubiquitously expressed with strong expression in skeletal and cardiac muscle, and is involved in a panoply of cellular processes. Mutations in BAG3 and aberrations in its expression cause fulminant myopathies, presenting with progressive limb and axial muscle weakness, and respiratory insufficiency and neuropathy. Herein, we report a sporadic case of a 15-years old girl with symptoms of myopathy, demyelinating polyneuropathy and asymptomatic long QT syndrome. Genetic testing demonstrated heterozygous mutation Pro209Leu (c.626C > T) in exon 3 of BAG3 gene causing severe myopathy and neuropathy, often associated with restrictive cardiomyopathy. We did not find a mutation in any known LQT syndrome genes. Analysis of muscle biopsy revealed profound disintegration of Z-discs with extensive accumulation of granular debris and large inclusions within fibers. We demonstrated profound alterations in BAG3 distribution as the protein localized to long filamentous structures present across the fibers that were positively stained not only for α-actinin but also for desmin and filamin indicating that those disintegrated Z-disc regions contained also other sarcomeric proteins. The mutation caused a decrease in the content of BAG3 and HSP70, and also of α-actinin desmin, filamin and fast myosin heavy chain, confirming its severe effect on the muscle fiber morphology and thus function. We provide further evidence that BAG3 is associated with Z-disc maintenance, and the Pro209Leu mutation may occur worldwide. We also provide a summary of cases associated with this mutation reported so far.

  8. Genotype-based clinical manifestation and treatment of Chinese long QT syndrome patients with KCNQ1 mutations - R380S and W305L.

    PubMed

    Zhou, Hui; Lai, Wei; Zhu, Wengen; Xie, Jinyan; Liu, Xin; Shen, Yang; Yuan, Ping; Liu, Ying; Cao, Qin; He, Wenfeng; Hong, Kui

    2016-04-01

    Aim Most long QT syndrome patients are associated with genetic mutations. We aimed to investigate the clinical and biochemical characteristics and look for genotype-based preventive implications in Chinese long QT syndrome patients. Methods and results We identified two missense mutations of the KCNQ1 gene in two independent Chinese families, including a previously reported mutation R380S in the C-terminus and a novel mutation W305L in the P-loop domain of the Kv7.1 channel, respectively. The proband with R380S was an 11-year-old girl who suffered a prolonged corrected QT interval of 660 ms, recurrent syncope, and sudden cardiac death, whose father was an asymptomatic carrier. The mutation W305L was detected in a 36-year-old woman with long QT syndrome and her immediate family members including the proband's younger sister with an unexplained syncope, her son, and her elder daughter without symptoms. Metoprolol appeared to be effective in preventing arrhythmias and syncope in long QT syndrome patients with mutation W305L. Both R380S and W305L mutations led to "loss-of-function" of the Kv7.1 channel accounting for the clinical phenotypes. We first show two missense KCNQ1 mutations - R380S and W305L - in Chinese long QT syndrome patients, resulting in the loss of protein function. Mutation W305L in the P-loop domain of the Kv7.1 may derive a pronounced benefit from β-blocker therapy in symptomatic long QT syndrome patients, whereas mutation R380S located in the C-terminus may be associated with a high risk of sudden cardiac death.

  9. Divergent antiarrhythmic effects of resveratrol and piceatannol in a whole-heart model of long QT syndrome.

    PubMed

    Ellermann, Christian; Wolfes, Julian; Kochhäuser, Simon; Dechering, Dirk G; Reinke, Florian; Wasmer, Kristina; Eckardt, Lars; Frommeyer, Gerrit

    2017-09-15

    The polyphenol resveratrol and its metabolite piceatannol have beneficial health effects including antiarrhythmic properties in ischemia/reperfusion. The objective of this study was to determine potential antiarrhythmic effects in acquired long-QT-syndrome (LQTS). 26 rabbit hearts were isolated and Langendorff-perfused. The IKr-blocker sotalol (100μM) was infused to mimic LQTS-2. Hearts were assigned to two groups. Sotalol significantly prolonged action potential duration (APD90) and QT-interval in both groups (group 1:APD90: +18ms, p<0.01;QT: +59ms, p<0.01; group 2: APD90: +22ms, p<0.01; QT: +30ms, p<0.01) and also significantly increased dispersion of repolarization (group 1: +21ms, p<0.01; group 2: +23ms, p<0.01). Thereafter, hearts were additionally perfused either with resveratrol (50μM, group 1, n=14) or with piceatannol (10μM, group 2, n=12). Administration of resveratrol significantly reduced APD90 (-29ms, p<0.01), QT-interval(-60ms, p<0.01) and dispersion of repolarization (-26ms, p<0.01). In contrast, piceatannol did not significantly alter APD90 (±0ms) but shortened QT-interval (-19ms, p<0.01) and increased dispersion of repolarization (+15ms, p<0.01). With sotalol, 7 of 14 bradycardic, AV-blocked hearts in group 1 and 8 of 12 in group 2 showed early afterdepolarizations (EAD) after lowering potassium concentration (p<0.01each). Polymorphic ventricular tachycardia (PVT) occurred in 5 of 14 (p<0.05) and 4 of 12 hearts (p=0.09) with a total number of 42 (p<0.05) and 44 episodes (p=0.07), respectively. Additional infusion of resveratrol reduced EAD (2 of 14, p=0.11) and PVT (1 of 14 hearts, p=0.16, 3 episodes, p<0.05). Piceatannol did not suppress EAD or TdP (EAD in 9 of 12 and TdP in 7 of 12 hearts,50 episodes). Resveratrol showed beneficial antiarrhythmic properties in acquired LQTS. Underlying mechanism is a substantial decrease dispersion of repolarization leading to a suppression of triggered activity. Copyright © 2017 Elsevier B.V. All rights

  10. The Application of Root Mean Square Electrocardiography (RMS ECG) for the Detection of Acquired and Congenital Long QT Syndrome

    PubMed Central

    Lux, Robert L.; Sower, Christopher Todd; Allen, Nancy; Etheridge, Susan P.; Tristani-Firouzi, Martin; Saarel, Elizabeth V.

    2014-01-01

    Background Precise measurement of the QT interval is often hampered by difficulty determining the end of the low amplitude T wave. Root mean square electrocardiography (RMS ECG) provides a novel alternative measure of ventricular repolarization. Experimental data have shown that the interval between the RMS ECG QRS and T wave peaks (RTPK) closely reflects the mean ventricular action potential duration while the RMS T wave width (TW) tracks the dispersion of repolarization timing. Here, we tested the precision of RMS ECG to assess ventricular repolarization in humans in the setting of drug-induced and congenital Long QT Syndrome (LQTS). Methods RMS ECG signals were derived from high-resolution 24 hour Holter monitor recordings from 68 subjects after receiving placebo and moxifloxacin and from standard 12 lead ECGs obtained in 97 subjects with LQTS and 97 age- and sex-matched controls. RTPK, QTRMS and RMS TW intervals were automatically measured using custom software and compared to traditional QT measures using lead II. Results All measures of repolarization were prolonged during moxifloxacin administration and in LQTS subjects, but the variance of RMS intervals was significantly smaller than traditional lead II measurements. TW was prolonged during moxifloxacin and in subjects with LQT-2, but not LQT-1 or LQT-3. Conclusion These data validate the application of RMS ECG for the detection of drug-induced and congenital LQTS. RMS ECG measurements are more precise than the current standard of care lead II measurements. PMID:24454918

  11. The application of root mean square electrocardiography (RMS ECG) for the detection of acquired and congenital long QT syndrome.

    PubMed

    Lux, Robert L; Sower, Christopher Todd; Allen, Nancy; Etheridge, Susan P; Tristani-Firouzi, Martin; Saarel, Elizabeth V

    2014-01-01

    Precise measurement of the QT interval is often hampered by difficulty determining the end of the low amplitude T wave. Root mean square electrocardiography (RMS ECG) provides a novel alternative measure of ventricular repolarization. Experimental data have shown that the interval between the RMS ECG QRS and T wave peaks (RTPK) closely reflects the mean ventricular action potential duration while the RMS T wave width (TW) tracks the dispersion of repolarization timing. Here, we tested the precision of RMS ECG to assess ventricular repolarization in humans in the setting of drug-induced and congenital Long QT Syndrome (LQTS). RMS ECG signals were derived from high-resolution 24 hour Holter monitor recordings from 68 subjects after receiving placebo and moxifloxacin and from standard 12 lead ECGs obtained in 97 subjects with LQTS and 97 age- and sex-matched controls. RTPK, QTRMS and RMS TW intervals were automatically measured using custom software and compared to traditional QT measures using lead II. All measures of repolarization were prolonged during moxifloxacin administration and in LQTS subjects, but the variance of RMS intervals was significantly smaller than traditional lead II measurements. TW was prolonged during moxifloxacin and in subjects with LQT-2, but not LQT-1 or LQT-3. These data validate the application of RMS ECG for the detection of drug-induced and congenital LQTS. RMS ECG measurements are more precise than the current standard of care lead II measurements.

  12. Arrhythmia Phenotype during Fetal Life Suggests LQTS Genotype: Risk Stratification of Perinatal Long QT Syndrome

    PubMed Central

    Cuneo, Bettina F.; Etheridge, Susan P.; Horigome, Hitoshi; Sallee, Denver; Moon-Grady, Anita; Weng, Hsin-Yi; Ackerman, Michael J.; Benson, D. Woodrow

    2014-01-01

    Background Fetal arrhythmias characteristic of long QT syndrome (LQTS) include torsades de pointes (TdP) and/or 2° atrioventricular block (AVB), but sinus bradycardia, defined as fetal heart rate <3% for gestational age, is most common. We hypothesized that prenatal rhythm phenotype might predict LQTS genotype and facilitate improved risk stratification and management. Method and Results Records of subjects exhibiting LQTS fetal arrhythmias were reviewed. Fetal echocardiograms, neonatal ECG, and genetic testing were evaluated. We studied 43 subjects exhibiting fetal LQTS arrhythmias: TdP ± 2° AVB (Group 1, n=7), isolated 2° AVB (Group 2, n=4) and sinus bradycardia (Group 3, n=32). Mutations in known LQTS genes were found in 95% of subjects tested. SCN5A mutations occurred in 71% of Group 1 while 91% of subjects with KCNQ1 mutations were in Group 3. Small numbers of subjects with KCNH2 mutations (n=4) were scattered in all 3 groups. Age at presentation did not differ among groups, and most subjects (n=42) were live born with gestational ages of 37.5±2.8 wks (mean±SD). However, those with TdP were typically delivered earlier. Prenatal treatment in Group 1 terminated (n=2) or improved (n=4) TdP. The neonatal QTc (mean±SE) of Group 1 (664.7±24.9) was longer than neonatal QTc in both Group 2 (491.2±27.6, p=0.004) and Group 3 (483.1±13.7, p<0.001). Despite medical and pacemaker therapy, postnatal cardiac arrest (n=4) or sudden death (n=1) was common among subjects with fetal/neonatal TdP. Conclusions Rhythm phenotypes of fetal LQTS have genotype-suggestive features which, along with QTc duration, may risk stratify perinatal management. PMID:23995044

  13. Cost-effectiveness of genetic testing in family members of patients with long-QT syndrome.

    PubMed

    Perez, Marco V; Kumarasamy, Narmadan A; Owens, Douglas K; Wang, Paul J; Hlatky, Mark A

    2011-01-01

    Family members of patients with established long-QT syndrome (LQTS) often lack definitive clinical findings, yet may have inherited an LQTS mutation and be at risk of sudden death. Genetic testing can identify mutations in 75% of patients with LQTS, but genetic testing of family members remains controversial. We used a Markov model to assess the cost-effectiveness of 3 strategies for treating an asymptomatic 10-year-old, first-degree relative of a patient with clinically evident LQTS. In the genetic testing strategy, relatives undergo genetic testing only for the mutation identified in the index patient, and relatives who test positive for the mutation are treated with β-blockers. This strategy was compared with (1) empirical treatment of relatives with β-blockers and (2) watchful waiting, with treatment only after development of symptoms. The genetic testing strategy resulted in better survival and quality-adjusted life years at higher cost, with a cost-effectiveness ratio of $67 400 per quality-adjusted life year gained compared with watchful waiting. The cost-effectiveness of the genetic testing strategy improved to less than $50 000 per quality-adjusted life year gained when applied selectively either to (1) relatives with higher clinical suspicion of LQTS (pretest probability 65% to 81%), or to (2) families with a higher than average risk of sudden death, or to (3) larger families (2 or more first-degree relatives tested). Genetic testing of young first-degree relatives of patients with definite LQTS is moderately expensive, but can reach acceptable thresholds of cost-effectiveness when applied to selected patients.

  14. Early somatic mosaicism is a rare cause of long-QT syndrome.

    PubMed

    Priest, James Rush; Gawad, Charles; Kahlig, Kristopher M; Yu, Joseph K; O'Hara, Thomas; Boyle, Patrick M; Rajamani, Sridharan; Clark, Michael J; Garcia, Sarah T K; Ceresnak, Scott; Harris, Jason; Boyle, Sean; Dewey, Frederick E; Malloy-Walton, Lindsey; Dunn, Kyla; Grove, Megan; Perez, Marco V; Neff, Norma F; Chen, Richard; Maeda, Katsuhide; Dubin, Anne; Belardinelli, Luiz; West, John; Antolik, Christian; Macaya, Daniela; Quertermous, Thomas; Trayanova, Natalia A; Quake, Stephen R; Ashley, Euan A

    2016-10-11

    Somatic mosaicism, the occurrence and propagation of genetic variation in cell lineages after fertilization, is increasingly recognized to play a causal role in a variety of human diseases. We investigated the case of life-threatening arrhythmia in a 10-day-old infant with long QT syndrome (LQTS). Rapid genome sequencing suggested a variant in the sodium channel NaV1.5 encoded by SCN5A, NM_000335:c.5284G > T predicting p.(V1762L), but read depth was insufficient to be diagnostic. Exome sequencing of the trio confirmed read ratios inconsistent with Mendelian inheritance only in the proband. Genotyping of single circulating leukocytes demonstrated the mutation in the genomes of 8% of patient cells, and RNA sequencing of cardiac tissue from the infant confirmed the expression of the mutant allele at mosaic ratios. Heterologous expression of the mutant channel revealed significantly delayed sodium current with a dominant negative effect. To investigate the mechanism by which mosaicism might cause arrhythmia, we built a finite element simulation model incorporating Purkinje fiber activation. This model confirmed the pathogenic consequences of cardiac cellular mosaicism and, under the presenting conditions of this case, recapitulated 2:1 AV block and arrhythmia. To investigate the extent to which mosaicism might explain undiagnosed arrhythmia, we studied 7,500 affected probands undergoing commercial gene-panel testing. Four individuals with pathogenic variants arising from early somatic mutation events were found. Here we establish cardiac mosaicism as a causal mechanism for LQTS and present methods by which the general phenomenon, likely to be relevant for all genetic diseases, can be detected through single-cell analysis and next-generation sequencing.

  15. Clinical and genetic features of Australian families with long QT syndrome: A registry-based study.

    PubMed

    Burns, Charlotte; Ingles, Jodie; Davis, Andrew M; Connell, Vanessa; Gray, Belinda; Hunt, Lauren; McGaughran, Julie; Semsarian, Christopher

    2016-12-01

    Familial long QT syndrome (LQTS) is a primary arrhythmogenic disorder caused by mutations in ion channel genes. The phenotype ranges from asymptomatic individuals to sudden cardiac arrest and death. LQTS is a rare but significant health problem for which global data should exist. This study sought to provide the first clinical and genetic description of Australian families with LQTS. We performed a cross-sectional study to evaluate clinical and genetic features of families with LQTS. We recruited individuals from the Australian Genetic Heart Disease Registry and Genetic Heart Disease Clinic, in Sydney, Australia, and included those with a diagnosis of LQTS according to the most recent consensus statement. Among 108 families with LQTS, 173 individuals were affected. Twenty-five (32%) probands had a sudden cardiac death (SCD) event (including appropriate implantable cardioverter defibrillator [ICD] therapy, or resuscitated cardiac arrest). There were 64 (82%) probands who underwent genetic testing, and 34 (53%) had a pathogenic or likely pathogenic mutation in. Having a family history of LQTS was significantly associated with identification of a pathogenic result (79% versus 14%, p<0.0001). There were 16 (9%) participants who experienced delay to diagnosis of at least 12 months. This is the first clinical and genetic study in a large cohort of Australian families with LQTS. Findings from this study suggest that the clinical and genetic features in this population are not dissimilar to those described in North American, European, and Asian cohorts. Global-scale information about families with LQTS is an important initiative to ensure diagnostic and management approaches are applicable to different populations and ethnicities.

  16. In silico investigation of the short QT syndrome, using human ventricle models incorporating electromechanical coupling

    PubMed Central

    Adeniran, Ismail; Hancox, Jules C.; Zhang, Henggui

    2013-01-01

    Introduction: Genetic forms of the Short QT Syndrome (SQTS) arise due to cardiac ion channel mutations leading to accelerated ventricular repolarization, arrhythmias and sudden cardiac death. Results from experimental and simulation studies suggest that changes to refractoriness and tissue vulnerability produce a substrate favorable to re-entry. Potential electromechanical consequences of the SQTS are less well-understood. The aim of this study was to utilize electromechanically coupled human ventricle models to explore electromechanical consequences of the SQTS. Methods and Results: The Rice et al. mechanical model was coupled to the ten Tusscher et al. ventricular cell model. Previously validated K+ channel formulations for SQT variants 1 and 3 were incorporated. Functional effects of the SQTS mutations on [Ca2+]i transients, sarcomere length shortening and contractile force at the single cell level were evaluated with and without the consideration of stretch-activated channel current (Isac). Without Isac, at a stimulation frequency of 1Hz, the SQTS mutations produced dramatic reductions in the amplitude of [Ca2+]i transients, sarcomere length shortening and contractile force. When Isac was incorporated, there was a considerable attenuation of the effects of SQTS-associated action potential shortening on Ca2+ transients, sarcomere shortening and contractile force. Single cell models were then incorporated into 3D human ventricular tissue models. The timing of maximum deformation was delayed in the SQTS setting compared to control. Conclusion: The incorporation of Isac appears to be an important consideration in modeling functional effects of SQT 1 and 3 mutations on cardiac electro-mechanical coupling. Whilst there is little evidence of profoundly impaired cardiac contractile function in SQTS patients, our 3D simulations correlate qualitatively with reported evidence for dissociation between ventricular repolarization and the end of mechanical systole. PMID

  17. In silico investigation of the short QT syndrome, using human ventricle models incorporating electromechanical coupling.

    PubMed

    Adeniran, Ismail; Hancox, Jules C; Zhang, Henggui

    2013-01-01

    Genetic forms of the Short QT Syndrome (SQTS) arise due to cardiac ion channel mutations leading to accelerated ventricular repolarization, arrhythmias and sudden cardiac death. Results from experimental and simulation studies suggest that changes to refractoriness and tissue vulnerability produce a substrate favorable to re-entry. Potential electromechanical consequences of the SQTS are less well-understood. The aim of this study was to utilize electromechanically coupled human ventricle models to explore electromechanical consequences of the SQTS. The Rice et al. mechanical model was coupled to the ten Tusscher et al. ventricular cell model. Previously validated K(+) channel formulations for SQT variants 1 and 3 were incorporated. Functional effects of the SQTS mutations on [Ca(2+)] i transients, sarcomere length shortening and contractile force at the single cell level were evaluated with and without the consideration of stretch-activated channel current (I sac). Without I sac, at a stimulation frequency of 1Hz, the SQTS mutations produced dramatic reductions in the amplitude of [Ca(2+)] i transients, sarcomere length shortening and contractile force. When I sac was incorporated, there was a considerable attenuation of the effects of SQTS-associated action potential shortening on Ca(2+) transients, sarcomere shortening and contractile force. Single cell models were then incorporated into 3D human ventricular tissue models. The timing of maximum deformation was delayed in the SQTS setting compared to control. The incorporation of I sac appears to be an important consideration in modeling functional effects of SQT 1 and 3 mutations on cardiac electro-mechanical coupling. Whilst there is little evidence of profoundly impaired cardiac contractile function in SQTS patients, our 3D simulations correlate qualitatively with reported evidence for dissociation between ventricular repolarization and the end of mechanical systole.

  18. Early somatic mosaicism is a rare cause of long-QT syndrome

    PubMed Central

    Priest, James Rush; Gawad, Charles; Kahlig, Kristopher M.; Yu, Joseph K.; O’Hara, Thomas; Rajamani, Sridharan; Clark, Michael J.; Garcia, Sarah T. K.; Ceresnak, Scott; Harris, Jason; Boyle, Sean; Dewey, Frederick E.; Malloy-Walton, Lindsey; Dunn, Kyla; Grove, Megan; Neff, Norma F.; Chen, Richard; Maeda, Katsuhide; Dubin, Anne; Belardinelli, Luiz; West, John; Antolik, Christian; Macaya, Daniela; Quertermous, Thomas; Trayanova, Natalia A.; Quake, Stephen R.; Ashley, Euan A.

    2016-01-01

    Somatic mosaicism, the occurrence and propagation of genetic variation in cell lineages after fertilization, is increasingly recognized to play a causal role in a variety of human diseases. We investigated the case of life-threatening arrhythmia in a 10-day-old infant with long QT syndrome (LQTS). Rapid genome sequencing suggested a variant in the sodium channel NaV1.5 encoded by SCN5A, NM_000335:c.5284G > T predicting p.(V1762L), but read depth was insufficient to be diagnostic. Exome sequencing of the trio confirmed read ratios inconsistent with Mendelian inheritance only in the proband. Genotyping of single circulating leukocytes demonstrated the mutation in the genomes of 8% of patient cells, and RNA sequencing of cardiac tissue from the infant confirmed the expression of the mutant allele at mosaic ratios. Heterologous expression of the mutant channel revealed significantly delayed sodium current with a dominant negative effect. To investigate the mechanism by which mosaicism might cause arrhythmia, we built a finite element simulation model incorporating Purkinje fiber activation. This model confirmed the pathogenic consequences of cardiac cellular mosaicism and, under the presenting conditions of this case, recapitulated 2:1 AV block and arrhythmia. To investigate the extent to which mosaicism might explain undiagnosed arrhythmia, we studied 7,500 affected probands undergoing commercial gene-panel testing. Four individuals with pathogenic variants arising from early somatic mutation events were found. Here we establish cardiac mosaicism as a causal mechanism for LQTS and present methods by which the general phenomenon, likely to be relevant for all genetic diseases, can be detected through single-cell analysis and next-generation sequencing. PMID:27681629

  19. Value of the "Standing Test" in the Diagnosis and Evaluation of Beta-blocker Therapy Response in Long QT Syndrome.

    PubMed

    Muñoz-Esparza, Carmen; Zorio, Esther; Domingo Valero, Diana; Peñafiel-Verdú, Pablo; Sánchez-Muñoz, Juan J; García-Molina, Esperanza; Sabater, María; Navarro, Marina; San-Román, Irene; Pérez, Inmaculada; Santos, Juan J; Cabañas-Perianes, Valentín; Valdés, Mariano; Pascual, Domingo; García-Alberola, Arcadio; Gimeno Blanes, Juan R

    2017-02-21

    Patients with congenital long QT syndrome (LQTS) have an abnormal QT adaptation to sudden changes in heart rate provoked by standing. The present study sought to evaluate the standing test in a cohort of LQTS patients and to assess if this QT maladaptation phenomenon is ameliorated by beta-blocker therapy. Electrographic assessments were performed at baseline and immediately after standing in 36 LQTS patients (6 LQT1 [17%], 20 LQT2 [56%], 3 LQT7 [8%], 7 unidentified-genotype patients [19%]) and 41 controls. The corrected QT interval (QTc) was measured at baseline (QTcsupine) and immediately after standing (QTcstanding); the QTc change from baseline (ΔQTc) was calculated as QTcstanding - QTcsupine. The test was repeated in 26 patients receiving beta-blocker therapy. Both QTcstanding and ΔQTc were significantly higher in the LQTS group than in controls (QTcstanding, 528 ± 46ms vs 420 ± 15ms, P < .0001; ΔQTc, 78 ± 40ms vs 8 ± 13ms, P < .0001). No significant differences were noted between LQT1 and LQT2 patients. Typical ST-T wave patterns appeared after standing in LQTS patients. Receiver operating characteristic curves of QTcstanding and ΔQTc showed a significant increase in diagnostic value compared with the QTcsupine (area under the curve for both, 0.99 vs 0.85; P < .001). Beta-blockers attenuated the response to standing in LQTS patients (QTcstanding, 440 ± 32ms, P < .0001; ΔQTc, 14 ± 16ms, P < .0001). Evaluation of the QTc after the simple maneuver of standing shows a high diagnostic performance and could be important for monitoring the effects of beta-blocker therapy in LQTS patients. Copyright © 2017 Sociedad Española de Cardiología. Published by Elsevier España, S.L.U. All rights reserved.

  20. Loss-of-function KCNH2 mutation in a family with long QT syndrome, epilepsy, and sudden death.

    PubMed

    Partemi, Sara; Cestèle, Sandrine; Pezzella, Marianna; Campuzano, Oscar; Paravidino, Roberta; Pascali, Vincenzo L; Zara, Federico; Tassinari, Carlo Alberto; Striano, Salvatore; Oliva, Antonio; Brugada, Ramon; Mantegazza, Massimo; Striano, Pasquale

    2013-08-01

    There has been increased interest in a possible association between epilepsy channelopathies and cardiac arrhythmias, such as long QT syndrome (LQTS). We report a kindred that features LQTS, idiopathic epilepsy, and increased risk of sudden death. Genetic study showed a previously unreported heterozygous point mutation (c.246T>C) in the KCNH2 gene. Functional studies showed that the mutation induces severe loss of function. This observation provides further evidence for a possible link between idiopathic epilepsy and LQTS. Wiley Periodicals, Inc. © 2013 International League Against Epilepsy.

  1. Acquired long QT syndrome and monomorphic ventricular tachycardia after alternative treatment with cesium chloride for brain cancer.

    PubMed

    Dalal, Anuj K; Harding, John D; Verdino, Ralph J

    2004-08-01

    Individuals searching for symptomatic relief or a potential cure are increasingly seeking and using nontraditional therapies for their various diseases. Little is known about the potential adverse effects that patients may encounter while undergoing these alternative treatments. Cesium chloride is an unregulated agent that has been reported to have antineoplastic properties. Cesium chloride is advertised as an alternative agent for many different types of cancers and can be purchased easily on the Internet. Recently, QT prolongation and polymorphic ventricular tachycardia were reported in several patients taking cesium chloride as alternative treatment for cancer. We report acquired QT prolongation and sustained monomorphic ventricular tachycardia in a patient who self-initiated and completed a course of cesium chloride as adjunctive treatment for brain cancer.

  2. Effect of non-dipper and dipper blood pressure patterns on Tp-Te interval and Tp-Te/QT ratio in patients with metabolic syndrome.

    PubMed

    Karaagac, Kemal; Tenekecioglu, Erhan; Yontar, Osman Can; Kuzeytemiz, Mustafa; Vatansever, Fahriye; Tutuncu, Ahmet; Ozluk, Ozlem Arican; Yilmaz, Mustafa; Demir, Mehmet

    2014-01-01

    The purpose of this study was to evaluate the effect of blood pressure (BP) rhythm on the values of Tp-Te interval and Tp-Te/QT ratio in patients with metabolic syndrome. Seventy patients with newly diagnosed hypertension who fulfilled the metabolic syndrome criteria according to the Third Report of the National Cholesterol Education Program Expert Panel on Detection, Evaluation, and Treatment of High Blood Cholesterol in Adults (NCEP/ATP-III) were evaluated with 24-hour blood pressure holter monitoring. According to blood pressure rhythm, 35 patients with dipper blood pressure pattern and 35 patients with non-dipper blood pressure pattern were enrolled as two groups in our study. QT, corrected QT (QTc), Tp-Te interval and Tp-Te/QT ratio were measured from the 12-lead electrocardiogram. These parameters were compared between the groups. The nocturnal systolic and diastolic blood pressures were significantly higher in non-dipper patients than the dipper group. Baseline characteristics and QT, QTc intervals were similar in both groups. Tp-Te (91±12.24 vs 74±9.96; p < 0.001), Tp-Te/QT (0.24±0.027 vs 0.20±0.025; p < 0.001) and Tp-Te/QTc (0.22±0.023 vs 0.18±0.023; p < 0.001) were significantly increased in non-dipper group. These findings suggest that Tp-Te interval, Tp-Te/QT ratio end Tp-Te/QTc ratio were prominently increased in non-dipper hypertensive patients than dippers with metabolic syndrome.

  3. Increased Vulnerability of Human Ventricle to Re-entrant Excitation in hERG-linked Variant 1 Short QT Syndrome

    PubMed Central

    Adeniran, Ismail; McPate, Mark J.; Witchel, Harry J.; Hancox, Jules C.; Zhang, Henggui

    2011-01-01

    The short QT syndrome (SQTS) is a genetically heterogeneous condition characterized by abbreviated QT intervals and an increased susceptibility to arrhythmia and sudden death. This simulation study identifies arrhythmogenic mechanisms in the rapid-delayed rectifier K+ current (IKr)-linked SQT1 variant of the SQTS. Markov chain (MC) models were found to be superior to Hodgkin-Huxley (HH) models in reproducing experimental data regarding effects of the N588K mutation on KCNH2-encoded hERG. These ionic channel models were then incorporated into human ventricular action potential (AP) models and into 1D and 2D idealised and realistic transmural ventricular tissue simulations and into a 3D anatomical model. In single cell models, the N588K mutation abbreviated ventricular cell AP duration at 90% repolarization (APD90) and decreased the maximal transmural voltage heterogeneity (δV) during APs. This resulted in decreased transmural heterogeneity of APD90 and of the effective refractory period (ERP): effects that are anticipated to be anti-arrhythmic rather than pro-arrhythmic. However, with consideration of transmural heterogeneity of IKr density in the intact tissue model based on the ten Tusscher-Noble-Noble-Panfilov ventricular model, not only did the N588K mutation lead to QT-shortening and increases in T-wave amplitude, but δV was found to be augmented in some local regions of ventricle tissue, resulting in increased tissue vulnerability for uni-directional conduction block and predisposing to formation of re-entrant excitation waves. In 2D and 3D tissue models, the N588K mutation facilitated and maintained re-entrant excitation waves due to the reduced substrate size necessary for sustaining re-entry. Thus, in SQT1 the N588K-hERG mutation facilitates initiation and maintenance of ventricular re-entry, increasing the lifespan of re-entrant spiral waves and the stability of scroll waves in 3D tissue. PMID:22194679

  4. Is flecainide dangerous in long QT-3 patients?

    PubMed

    Beinart, Roy; Michailidis, Athanasios; Gurevitz, Osnat T; Glikson, Michael

    2009-01-01

    Mutations of the cardiac sodium channel gene, SCN5A, are present in both long-QT and Brugada syndromes. Flecainide is used as a provocative test to unmask the electrocardiogram (ECG) phenotype of the Brugada syndrome, as well as long-term treatment for long QT-3 syndrome, since it shortens the QT interval. We report a case where oral flecainide induced syncope with a Brugada ECG pattern in a patient with known long QT-3 syndrome.

  5. Pregbalin induced recurrent syncopal attacks with prolong QT interval.

    PubMed

    Adar, Adem; Cakan, Fahri; Önalan, Orhan

    2017-08-30

    Long QT syndrome may lead to fatal dysrhythmia. Prolongation of QT interval due to pregabalin has been shown in rats and no data is available in humans. We report a 80-year-old female patient using pregabalin. She was presented to emergency room with syncope attacks. Her admission electrocardiography demonstrated prolonged QT interval. After excluding the possible causes of the long QT syndrome, we attributed prolonged QT interval to pregabalin therapy. After discontinuation of pregabalin QT interval returned to normal range and patient experienced no further syncope attacks. It is first time for documentation of prolonged QT due to pregabalin in humans. © 2017 Wiley Periodicals, Inc.

  6. Potassium Channel Block and Novel Autoimmune-Associated Long QT Syndrome.

    PubMed

    Boutjdir, Mohamed; Lazzerini, Pietro Enea; Capecchi, Pier Leopoldo; Laghi-Pasini, Franco; El-Sherif, Nabil

    2016-06-01

    This article reviews advances in the pathogenesis of anti-SSA/Ro antibody-induced corrected QT (QTc) prolongation in patients with autoimmune diseases; particularly connective tissue disease (CTD). Evidence shows that anti-SSA/Ro antibody-positive patients with CTD show QTc prolongation and complex ventricular arrhythmias. Molecular and functional data provide evidence that the human ether-a-go-go-related gene potassium channel conducting the rapidly activating delayed rectifier potassium current is directly inhibited by anti-SSA/Ro antibodies, resulting in action potential duration prolongation leading to QT interval lengthening. Routine electrocardiogram screening in anti-SSA/Ro antibody-positive patients and counseling for patients with other QTc prolonging risk factors is recommended.

  7. Electro-mechanical dysfunction in long QT syndrome: Role for arrhythmogenic risk prediction and modulation by sex and sex hormones.

    PubMed

    Lang, C N; Menza, M; Jochem, S; Franke, G; Perez Feliz, S; Brunner, M; Koren, G; Zehender, M; Bugger, H; Jung, B A; Foell, D; Bode, C; Odening, K E

    2016-01-01

    Long QT syndrome (LQTS) is a congenital arrhythmogenic channelopathy characterized by impaired cardiac repolarization. Increasing evidence supports the notion that LQTS is not purely an "electrical" disease but rather an "electro-mechanical" disease with regionally heterogeneously impaired electrical and mechanical cardiac function. In the first part, this article reviews current knowledge on electro-mechanical (dys)function in LQTS, clinical consequences of the observed electro-mechanical dysfunction, and potential underlying mechanisms. Since several novel imaging techniques - Strain Echocardiography (SE) and Magnetic Resonance Tissue Phase Mapping (TPM) - are applied in clinical and experimental settings to assess the (regional) mechanical function, advantages of these non-invasive techniques and their feasibility in the clinical routine are particularly highlighted. The second part provides novel insights into sex differences and sex hormone effects on electro-mechanical cardiac function in a transgenic LQT2 rabbit model. Here we demonstrate that female LQT2 rabbits exhibit a prolonged time to diastolic peak - as marker for contraction duration and early relaxation - compared to males. Chronic estradiol-treatment enhances these differences in time to diastolic peak even more and additionally increases the risk for ventricular arrhythmia. Importantly, time to diastolic peak is particularly prolonged in rabbits exhibiting ventricular arrhythmia - regardless of hormone treatment - contrasting with a lack of differences in QT duration between symptomatic and asymptomatic LQT2 rabbits. This indicates the potential added value of the assessment of mechanical dysfunction in future risk stratification of LQTS patients. Copyright © 2015 Elsevier Ltd. All rights reserved.

  8. Long QT syndrome in a patient with allergic rhinoconjunctivitis and auto-immune diabetes: focus on the choice of anti-H1 drugs.

    PubMed

    Moneret-Vautrin, D A; de Chillou, C; Codreanu, A

    2006-12-01

    The long QT syndrome is a rare disease. The prevalence is estimated at 1/5 000 to 1/20,000. Numerous drugs are contra-indicated because they can lengthen the QT interval. A case of pollen allergy in an adolescent with LQTS is described. The possibility to prescribe anti-H1 drugs is reviewed since cases of torsades de pointe and even deaths have been reported for terfenadine and astemizole. Diphenhydramine, orphenadrine and hydroxyzine are contra-indicated. No accidents and no effects on the QT interval have been published for ebastine, fexofenadine, desloratadine and levocetirizine. These anti-H1 drugs could be used with great care, without any association with drugs resulting in low serum potassium level. Azelastine eye drops have been authorized and a routine protection by inhaled corticosteroids during the pollinic period has been advised in this adolescent treated by betablockers.

  9. How do sex hormones modify arrhythmogenesis in long QT syndrome? Sex hormone effects on arrhythmogenic substrate and triggered activity.

    PubMed

    Odening, Katja E; Koren, Gideon

    2014-11-01

    Gender differences in cardiac repolarization and the arrhythmogenic risk of patients with inherited and acquired long QT syndromes are well appreciated clinically. Enhancing our knowledge of the mechanisms underlying these differences is critical to improve our therapeutic strategies for preventing sudden cardiac death in such patients. This review summarizes the effects of sex hormones on the expression and function of ion channels that control cardiac cell excitation and repolarization as well as key proteins that regulate Ca(2+) dynamics at the cellular level. Moreover, it examines the role of sex hormones in modifying the dynamic spatiotemporal (regional and transmural) heterogeneities in action potential duration (eg, the arrhythmogenic substrate) and the susceptibility to (sympathetic) triggered activity at the tissue, organ, and whole animal levels. Finally, it explores the implications of these effects on the management of patients with LQTS.

  10. Genetic variants for long QT syndrome among infants and children from a statewide newborn hearing screening program cohort.

    PubMed

    Chang, Ruey-Kang R; Lan, Yueh-Tze; Silka, Michael J; Morrow, Hallie; Kwong, Alan; Smith-Lang, Janna; Wallerstein, Robert; Lin, Henry J

    2014-03-01

    Autosomal recessive long QT syndrome (LQTS), or Jervell and Lange-Nielsen syndrome (JLNS), can be associated with sensorineural hearing loss. We aimed to explore newborn hearing screening combined with electrocardiograms (ECGs) for early JLNS detection. In California, we conducted statewide, prospective ECG screening of children ≤ 6 years of age with unilateral or bilateral, severe or profound, sensorineural or mixed hearing loss. Families were identified through newborn hearing screening and interviewed about medical and family histories. Twelve-lead ECGs were obtained. Those with positive histories or heart rate corrected QT (QTc) intervals ≥ 450 ms had repeat ECGs. DNA sequencing of 12 LQTS genes was performed for repeat QTc intervals ≥ 450 ms. We screened 707 subjects by ECGs (number screened/number of responses = 91%; number of responses/number of families who were mailed invitations = 54%). Of these, 73 had repeat ECGs, and 19 underwent gene testing. No subject had homozygous or compound heterozygous LQTS mutations, as in JLNS. However, 3 individuals (with QTc intervals of 472, 457, and 456 ms, respectively) were heterozygous for variants that cause truncation or missplicing: 2 in KCNQ1 (c.1343dupC or p.Glu449Argfs*14; c.1590+1G>A or p.Glu530sp) and 1 in SCN5A (c.5872C>T or p.Arg1958*). In contrast to reports of JLNS in up to 4% of children with sensorineural hearing loss, we found no examples of JLNS. Because the 3 variants identified were unrelated to hearing, they likely represent the prevalence of potential LQTS mutations in the general population. Further studies are needed to define consequences of such mutations and assess the overall prevalence. Published by Mosby, Inc.

  11. Heterogeneous Phenotype of Long QT Syndrome Caused by the KCNH2-H562R Mutation: Importance of Familial Genetic Testing.

    PubMed

    Muñoz-Esparza, Carmen; García-Molina, Esperanza; Salar-Alcaraz, Mariela; Peñafiel-Verdú, Pablo; Sánchez-Muñoz, Juan J; Martínez Sánchez, Juan; Cabañas-Perianes, Valentín; Valdés Chávarri, Mariano; García Alberola, Arcadio; Gimeno-Blanes, Juan R

    2015-10-01

    Long QT syndrome is an inherited ion channelopathy that leads to syncope and sudden death. Because of the heterogeneous phenotype of this disease, genetic testing is fundamental to detect individuals with concealed long QT syndrome. In this study, we determined the features of a family with 13 carriers of the KCNH2-H562R missense mutation, which affects the pore region of the HERG channel. We identified the KCNH2-H562R mutation in a 65-year-old man with a prolonged QTc interval who had experienced an episode of torsade de pointes. Subsequently, a total of 13 mutation carriers were identified in the family. Carriers (age 48 [26] years; 46% males) underwent clinical evaluation, electrocardiography and echocardiography. The mean (standard deviation) QTc in carriers was 493 (42) ms (3 [23%] showed normal QTc); 6 (46%) had symptoms (4, syncope; 1, sudden death; 1, aborted sudden death [proband]). While under treatment with beta-blockers, 11 of 12 carriers (92%) remained asymptomatic at 5 years of follow-up (1 patient required left cardiac sympathectomy). The QTc shortening with beta-blockers was 50 (37) ms. There was 1 sudden death in a patient who refused treatment. Family study is essential in the interpretation of a genetic testing result. This article describes the heterogeneous and variable phenotype of a large family with the KCNH2-H562R mutation and highlights the role of genetic study for the appropriate identification of at-risk individuals who would benefit from treatment. Copyright © 2014 Sociedad Española de Cardiología. Published by Elsevier España, S.L.U. All rights reserved.

  12. High-risk Long QT Syndrome Mutations in the Kv7.1 (KCNQ1) Pore Disrupt the Molecular Basis for Rapid K+ Permeation

    PubMed Central

    Burgess, Don E.; Bartos, Daniel C.; Reloj, Allison R.; Campbell, Kenneth S.; Johnson, Jonathan N.; Tester, David J.; Ackerman, Michael J.; Fressart, Véronique; Denjoy, Isabelle; Guicheney, Pascale; Moss, Arthur J.; Ohno, Seiko; Horie, Minoru; Delisle, Brian P.

    2012-01-01

    Type 1 long QT syndrome (LQT1) syndrome is caused by loss-of-function mutations in the KCNQ1, which encodes the K+ channel (Kv7.1) that underlies the slowly activating delayed rectifier K+ current in the heart. Intragenic risk stratification suggests LQT1 mutations that disrupt conserved amino acid residues in the pore are an independent risk factor for LQT1-related cardiac events. The purpose of this study is to determine possible molecular mechanisms that underlie the loss-of-function for these high-risk mutations. Extensive genotype-phenotype analyses of LQT1 patients showed that T322M-, T322A-, or G325R-Kv7.1 confer a high risk for LQT1-related cardiac events. Heterologous expression of these mutations with KCNE1 revealed they generated non-functional channels and caused dominant negative suppression of WT-Kv7.1 current. Molecular dynamic simulations (MDS) of analogous mutations in KcsA (T85M-, T85A-, and G88R-KcsA) demonstrated that they disrupted the symmetrical distribution of the carbonyl oxygen atoms in the selectivity filter, which upset the balance between the strong attractive and K+-K+ repulsive forces required for rapid K+ permeation. We conclude high-risk LQT1 mutations in the pore likely disrupt the architectural and physical properties of the K+ channel selectivity filter. PMID:23092362

  13. Multiplex ligation-dependent probe amplification copy number variant analysis in patients with acquired long QT syndrome.

    PubMed

    Williams, Victoria S; Cresswell, Carl J; Ruspi, Gerhard; Yang, Tao; Atak, Thomas C; McLoughlin, Matthew; Ingram, Christiana D; Ramirez, Andrea H; Roden, Dan; Armstrong, Martin

    2015-04-01

    Thirteen genetic loci map to families with congenital long QT syndrome (cLQT) and multiple single nucleotide mutations have been functionally implicated in cLQT. Studies have investigated copy number variations (CNVs) in the cLQT genes to ascertain their involvement in cLQT. In these studies 3-12% of cLQT patients who were mutation negative by all other methods carried CNVs in cLQT genes. Prolongation of the QT interval can also be acquired after exposure to certain drugs [acquired LQT (aLQT)]. Single nucleotide mutations in cLQT genes have also been associated with and functionally implicated in aLQT, but to date no studies have explored CNVs as an additional susceptibility factor in aLQT. The aim of this study was to explore the contribution of CNVs in determining susceptibility to aLQT. In this study we screened the commonest cLQT genes (KCNQ1; KCNH2; SCN5A; KCNE1, and KCNE2) in a general population of healthy volunteers and in a cohort of subjects presenting with aLQT for CNVs using the multiplex ligation-dependent probe amplification method. Copy number variants were detected and confirmed in 1 of 197 of the healthy volunteers and in 1 of 90 subjects with aLQT. The CNV in the aLQT subject was functionally characterized and demonstrated impaired channel function. Copy number variation is a possible additional risk factor for aLQT and should be considered for incorporation into pharmacogenetic screening of LQTS genes in addition to mutation detection to improve the safety of medication administration. Published on behalf of the European Society of Cardiology. All rights reserved. © The Author 2015. For permissions please email: journals.permissions@oup.com.

  14. Some legal, social, and ethical issues related to the genetic testing revolution, as exemplified in the long QT syndrome.

    PubMed

    Liebman, J

    2001-01-01

    Molecular Biology is revolutionizing medicine. There are a number of conditions, particularly exemplified by the long QT syndrome, where there is no structural abnormality but where a subset of patients is prone to sudden death. The issues of appropriate care are very complex, because there is tremendous overlap between patients with prolongation of the QT who remain asymptomatic and those with prolongation who are very symptomatic. Furthermore, even those who are prone to have one of the abnormal genes, may be asymptomatic. A large literature has developed, from both legal and ethical aspects, related to the fact that in genetic disease per se, not only is the person at risk, but so are many members of his or her family. A large literature has also developed as to which should be prime, the patient's privacy or the responsibility to make sure the entire family is knowledgeable and perhaps tested. At the present moment our care is based upon the fact that the precise identification of the gene is not yet available on a routine basis. This of course, may soon change. But we will still have difficult decisions to make. Obviously, we have a responsibility as physicians to be as precise as our discipline allows, but we have a responsibility to be flexible. Relief of anxiety, as an example, has to be a prime issue. This is certainly the case now when any information related to infants with potential sudden death is still incomplete. We must not approach the care of the patient in such a way that protection of the physician may interfere with appropriate care. The discussion necessarily includes a variety of aspects.

  15. Syntrophin mutation associated with long QT syndrome through activation of the nNOS-SCN5A macromolecular complex.

    PubMed

    Ueda, Kazuo; Valdivia, Carmen; Medeiros-Domingo, Argelia; Tester, David J; Vatta, Matteo; Farrugia, Gianrico; Ackerman, Michael J; Makielski, Jonathan C

    2008-07-08

    Mutations in 11 genes that encode ion channels or their associated proteins cause inherited long QT syndrome (LQTS) and account for approximately 75-80% of cases (LQT1-11). Direct sequencing of SNTA1, the gene encoding alpha1-syntrophin, was performed in a cohort of LQTS patients that were negative for mutations in the 11 known LQTS-susceptibility genes. A missense mutation (A390V-SNTA1) was found in a patient with recurrent syncope and markedly prolonged QT interval (QTc, 530 ms). SNTA1 links neuronal nitric oxide synthase (nNOS) to the nNOS inhibitor plasma membrane Ca-ATPase subtype 4b (PMCA4b); SNTA1 also is known to associate with the cardiac sodium channel SCN5A. By using a GST-fusion protein of the C terminus of SCN5A, we showed that WT-SNTA1 interacted with SCN5A, nNOS, and PMCA4b. In contrast, A390V-SNTA1 selectively disrupted association of PMCA4b with this complex and increased direct nitrosylation of SCN5A. A390V-SNTA1 expressed with SCN5A, nNOS, and PMCA4b in heterologous cells increased peak and late sodium current compared with WT-SNTA1, and the increase was partially inhibited by NOS blockers. Expression of A390V-SNTA1 in cardiac myocytes also increased late sodium current. We conclude that the A390V mutation disrupted binding with PMCA4b, released inhibition of nNOS, caused S-nitrosylation of SCN5A, and was associated with increased late sodium current, which is the characteristic biophysical dysfunction for sodium-channel-mediated LQTS (LQT3). These results establish an SNTA1-based nNOS complex attached to SCN5A as a key regulator of sodium current and suggest that SNTA1 be considered a rare LQTS-susceptibility gene.

  16. Semiconductor Whole Exome Sequencing for the Identification of Genetic Variants in Colombian Patients Clinically Diagnosed with Long QT Syndrome.

    PubMed

    Burgos, Mariana; Arenas, Alvaro; Cabrera, Rodrigo

    2016-08-01

    Inherited long QT syndrome (LQTS) is a cardiac channelopathy characterized by a prolongation of QT interval and the risk of syncope, cardiac arrest, and sudden cardiac death. Genetic diagnosis of LQTS is critical in medical practice as results can guide adequate management of patients and distinguish phenocopies such as catecholaminergic polymorphic ventricular tachycardia (CPVT). However, extensive screening of large genomic regions is required in order to reliably identify genetic causes. Semiconductor whole exome sequencing (WES) is a promising approach for the identification of variants in the coding regions of most human genes. DNA samples from 21 Colombian patients clinically diagnosed with LQTS were enriched for coding regions using multiplex polymerase chain reaction (PCR) and subjected to WES using a semiconductor sequencer. Semiconductor WES showed mean coverage of 93.6 % for all coding regions relevant to LQTS at >10× depth with high intra- and inter-assay depth heterogeneity. Fifteen variants were detected in 12 patients in genes associated with LQTS. Three variants were identified in three patients in genes associated with CPVT. Co-segregation analysis was performed when possible. All variants were analyzed with two pathogenicity prediction algorithms. The overall prevalence of LQTS and CPVT variants in our cohort was 71.4 %. All LQTS variants previously identified through commercial genetic testing were identified. Standardized WES assays can be easily implemented, often at a lower cost than sequencing panels. Our results show that WES can identify LQTS-causing mutations and permits differential diagnosis of related conditions in a real-world clinical setting. However, high heterogeneity in sequencing depth and low coverage in the most relevant genes is expected to be associated with reduced analytical sensitivity.

  17. Cardiac arrest during laparoscopic Roux-en-Y gastric bypass in a bariatric patient with drug-associated long QT syndrome.

    PubMed

    Woodard, Gavitt; Brodsky, Jay B; Morton, John M

    2011-01-01

    Obese patients often may demonstrate an acquired prolonged QTc interval due to alteration in cardiac physiology, electrolyte disturbances, and/or medication use. Intraoperatively, bariatric surgery may further contribute additional cardiac stressors to obese patients with long QT syndrome (LQTS). We present a case report of an obese woman with LQTS who underwent laparoscopic Roux-en-Y gastric bypass surgery and sustained an intraoperative cardiac arrest. We discuss identification, prevention, and treatment strategies for LQTS in the bariatric surgery patient.

  18. QT variability.

    PubMed

    Berger, Ronald D

    2003-01-01

    We hypothesized that temporal lability in ventricular repolarization is a marker for, and is mechanistically related to, increased risk of malignant ventricular arrhythmias. To assess repolarization lability in the surface electrocardiogram, we developed an automated algorithm, based on template matching, to measure beat-to-beat changes in QT interval. We calculate a QT variability index (QTVI) to quantify the relative magnitude of QT interval changes compared to heart rate variability. We found that QTVI is a reproducible measure. It is elevated in patients with ischemic and nonischemic dilated cardiomyopathy compared with age-matched controls (P<.00001). We have also shown that QTVI is elevated in patients with malignant beta-myosin heavy-chain mutations associated with hypertrophic cardiomyopathy. In a study of patients undergoing electrophysiologic testing, QTVI identified patients with cardiac arrest better than electrophysiologic test result and better than other risk stratifiers included in the analysis. QT variability is a marker of electrical disease in the ventricle and may be associated with enhanced risk of life-threatening arrhythmias.

  19. QT/RR relationship in patients after remote anterior myocardial infarction with left ventricular dysfunction and different types of ventricular arrhythmias.

    PubMed

    Szydlo, Krzysztof; Trusz-Gluza, Maria; Wita, Krystian; Filipecki, Artur; Orszulak, Witold; Urbanczyk, Dagmara; Krauze, Jolanta; Kolasa, Jaroslaw; Tabor, Zbigniew

    2008-01-01

    QT/RR relationship was found to be both rate-dependent and rate-independent, what suggests the influence of autonomic drive and other not-autonomic related factors on it. The steeper QT/RR slope in patients after acute myocardial infarction (MI) was described, but the relationship to ventricular arrhythmias is unknown. The purpose of this study was to calculate differences in QT/RR relationship in patients after remote anterior MI with left ventricular dysfunction and different types of ventricular arrhythmias. The cohort of 95 patients (age: 63 +/- 11 years, LVEF: 35 +/- 9%) with previous anterior MI (mean 1.1 years) was divided into two well-matched groups-50 patients without episodes of ventricular tachycardia (VT) or ventricular fibrillation (VF) (NoVT/VF: 39 males, 64 +/- 12 years, LVEF 37 +/- 8%) and 45 patients with VT and/or VF (all with ICD implanted) (VT/VF: 35 males, 62 +/- 10 years, LVEF 34 +/- 10%). No true antiarrhythmics were used. QT/RR slope was calculated from 24-hour Holter ECG for the entire recording (E), daytime (D) and nighttime (N) periods. Groups did not differ in basic clinical data (age, LVEF, treatment). QT/RR slopes were steeper in VT/VF than in NoVT/VF group in all analyzed periods: E - 0.195 +/- 0.03 versus 0.15 +/- 0.03 (P < 0.001), N - 0.190 +/- 0.03 versus 0.138 +/- 0.03 (P < 0.001) and D - 0.200 +/- 0.04 versus 0.152 +/- 0.03 (P < 0.001). No significant day-to-night differences were found in both groups. Steeper QT/RR slope and complete lack of day-to-night differences in VT/VF patients show inappropriate QT adaptation to the heart rate changes. The prognostic significance of this parameter needs prospective studies.

  20. Griscelli syndrome type-3

    PubMed Central

    Shah, Bela J.; Jagati, Ashish K.; Katrodiya, Nilesh K.; Patel, Sonal M.

    2016-01-01

    Griscelli syndrome (GS) is a rare autosomal recessive multisystem disorder of pigmentary dilution of skin, silver gray hair, variable immunodeficiency, neurological impairment, and abnormal accumulation of melanosomes in melanocytes. GS type 3 is characterized by hypomelanosis with no immunological and neurological manifestation. Prognosis is very good in type 3 GS and usually require no active intervention, as opposed to type 1 and 2 where early diagnosis and treatment plays a crucial role in patient's survival. The characteristic phenotypic appearance, especially the pigment dilution of the patient's hair, is emphasized here. PMID:27990386

  1. Impediments to DNA testing and cascade screening for hypertrophic cardiomyopathy and Long QT syndrome: a qualitative study of patient experiences.

    PubMed

    Smart, Andrew

    2010-12-01

    This paper reports data from a qualitative study of patient experiences of DNA testing and cascade screening for hypertrophic cardiomyopathy and long QT syndrome, cardiac conditions that place sufferers at risk of sudden death. The paper particularly focuses on potential impediments to testing and screening. Semi-structured interviews were undertaken with a purposive sample of 27 people in the UK who had undergone testing. In the context of the uncertainties that can characterize experiences of these disorders, the majority of participants in this sample embraced testing and screening as a way of providing health information for themselves or their relatives (particularly children). There was nevertheless evidence of ambivalence about the value and impact of the DNA test information which could influence participants' dispositions toward testing, and play into dilemmas about family communication. Other concerns arose in relation to communicating about these disorders, decisions to involve elderly relatives and pressures relating to family responsibility. The evidence of ambivalence provides insight into why some people may be resistant to testing, screening and sharing information. The findings about communication processes indicate potential areas of concern for the cascading process.

  2. Cryo-EM Structure of a KCNQ1/CaM Complex Reveals Insights into Congenital Long QT Syndrome.

    PubMed

    Sun, Ji; MacKinnon, Roderick

    2017-06-01

    KCNQ1 is the pore-forming subunit of cardiac slow-delayed rectifier potassium (IKs) channels. Mutations in the kcnq1 gene are the leading cause of congenital long QT syndrome (LQTS). Here, we present the cryoelectron microscopy (cryo-EM) structure of a KCNQ1/calmodulin (CaM) complex. The conformation corresponds to an "uncoupled," PIP2-free state of KCNQ1, with activated voltage sensors and a closed pore. Unique structural features within the S4-S5 linker permit uncoupling of the voltage sensor from the pore in the absence of PIP2. CaM contacts the KCNQ1 voltage sensor through a specific interface involving a residue on CaM that is mutated in a form of inherited LQTS. Using an electrophysiological assay, we find that this mutation on CaM shifts the KCNQ1 voltage-activation curve. This study describes one physiological form of KCNQ1, depolarized voltage sensors with a closed pore in the absence of PIP2, and reveals a regulatory interaction between CaM and KCNQ1 that may explain CaM-mediated LQTS. Copyright © 2017 Elsevier Inc. All rights reserved.

  3. Cardiac late Na⁺ current: proarrhythmic effects, roles in long QT syndromes, and pathological relationship to CaMKII and oxidative stress.

    PubMed

    Belardinelli, Luiz; Giles, Wayne R; Rajamani, Sridharan; Karagueuzian, Hrayr S; Shryock, John C

    2015-02-01

    Myocyte sodium channel current that persists throughout the plateau of the cardiac action potential is referred to as late sodium current (I(Na-L)). The magnitude of I(Na-L) is normally small, but can increase significantly in common acute and chronic pathological settings as a result of inherited and/or acquired Na(+) channelopathies that alter channel opening and closing (ie, gating), location (trafficking), or anchoring and interactions with cytoskeletal proteins. An increase in I(Na-L) reduces repolarization reserve in atrial and ventricular myocytes and prolongs the action potential duration and the QT interval. An enhanced I(Na-L) is a cause of long QT syndrome 3. I(Na-L) may be a cause of afterdepolarizations, triggered arrhythmias, and spontaneous diastolic depolarization-induced automaticity. In addition, enhancement of I(Na-L) increases both the temporal and the spatial dispersion of repolarization in the myocardium and may lead to spatially discordant action potential duration alternans, wavebreak, and reentrant arrhythmias. Positive feedback loops between increases in I(Na-L) and the activity of Ca(2+)/calmodulin-dependent protein kinase II appear to contribute to the genesis of arrhythmias and to certain abnormalities of the ischemic heart. In this review, we discuss some of the more relevant experimental results, clinical findings, and insights from cellular and animal models that highlight the role of I(Na-L) in the genesis of arrhythmias, long QT syndromes, and intracellular Ca(2+) homeostasis.

  4. The role of M cells and the long QT syndrome in cardiac arrhythmias: Simulation studies of reentrant excitations using a detailed electrophysiological model

    NASA Astrophysics Data System (ADS)

    Henry, Hervé; Rappel, Wouter-Jan

    2004-03-01

    In this numerical study, we investigate the role of intrinsic heterogeneities of cardiac tissue due to M cells in the generation and maintenance of reentrant excitations using the detailed Luo-Rudy dynamic model. This model has been extended to include a description of the long QT 3 syndrome, and is studied in both one dimension, corresponding to a cable traversing the ventricular wall, and two dimensions, representing a transmural slice. We focus on two possible mechanisms for the generation of reentrant events. We first investigate if early-after-depolarizations occurring in M cells can initiate reentry. We find that, even for large values of the long QT strength, the electrotonic coupling between neighboring cells prevents early-after-depolarizations from creating a reentry. We then study whether M cell domains, with their slow repolarization, can function as wave blocks for premature stimuli. We find that the inclusion of an M cell domain can result in some cases in reentrant excitations and we determine the lifetime of the reentry as a function of the size and geometry of the domain and of the strength of the long QT syndrome.

  5. De subitaneis mortibus. XXX. Observations on the pathophysiology of the long QT syndromes with special reference to the neuropathology of the heart.

    PubMed

    James, T N; Froggatt, P; Atkinson, W J; Lurie, P R; McNamara, D G; Miller, W W; Schloss, G T; Carroll, J F; North, R L

    1978-06-01

    Eight patients (different families) with syncopal attacks and a long QT interval in the ECG died suddenly. Five heard normally and three were born deaf. At postmortem examination of all eight hearts the single consistent abnormality was focal neuritis and neural degeneration within the sinus node, A-V node, His bundle and ventricular myocardium. Although the etiology of this intracardiac neural disease is uncertain, a chronic viral infection or some noninfectious degenerative process are among the plausible causes discussed. If intracardiac neuritis and neural degeneration prove to be a prevalent finding among other victims dying from the long QT syndromes, further consideration should be given to whether there is any genuine hereditary component in the pathogenesis. Because of the asymmetrical and focal distribution of the cardioneural lesions, the response to present forms of medical or surgical treatment of the lung QT syndromes may vary from benefit to harm. Until more is known of the true etiology of the neural disease, treatment will probably remain empirical in nature and should be conducted with cautious clinical observation.

  6. Founder mutations characterise the mutation panorama in 200 Swedish index cases referred for Long QT syndrome genetic testing

    PubMed Central

    2012-01-01

    Background Long QT syndrome (LQTS) is an inherited arrhythmic disorder characterised by prolongation of the QT interval on ECG, presence of syncope and sudden death. The symptoms in LQTS patients are highly variable, and genotype influences the clinical course. This study aims to report the spectrum of LQTS mutations in a Swedish cohort. Methods Between March 2006 and October 2009, two hundred, unrelated index cases were referred to the Department of Clinical Genetics, Umeå University Hospital, Sweden, for LQTS genetic testing. We scanned five of the LQTS-susceptibility genes (KCNQ1, KCNH2, SCN5A, KCNE1, and KCNE2) for mutations by DHPLC and/or sequencing. We applied MLPA to detect large deletions or duplications in the KCNQ1, KCNH2, SCN5A, KCNE1, and KCNE2 genes. Furthermore, the gene RYR2 was screened in 36 selected LQTS genotype-negative patients to detect cases with the clinically overlapping disease catecholaminergic polymorphic ventricular tachycardia (CPVT). Results In total, a disease-causing mutation was identified in 103 of the 200 (52%) index cases. Of these, altered exon copy numbers in the KCNH2 gene accounted for 2% of the mutations, whereas a RYR2 mutation accounted for 3% of the mutations. The genotype-positive cases stemmed from 64 distinct mutations, of which 28% were novel to this cohort. The majority of the distinct mutations were found in a single case (80%), whereas 20% of the mutations were observed more than once. Two founder mutations, KCNQ1 p.Y111C and KCNQ1 p.R518*, accounted for 25% of the genotype-positive index cases. Genetic cascade screening of 481 relatives to the 103 index cases with an identified mutation revealed 41% mutation carriers who were at risk of cardiac events such as syncope or sudden unexpected death. Conclusion In this cohort of Swedish index cases with suspected LQTS, a disease-causing mutation was identified in 52% of the referred patients. Copy number variations explained 2% of the mutations and 3 of 36 selected

  7. Genetic variants for long QT syndrome among infants and children from a statewide newborn hearing screening program cohort

    PubMed Central

    Chang, Ruey-Kang R.; Lan, Yueh-Tze; Silka, Michael J.; Morrow, Hallie; Kwong, Alan; Smith-Lang, Janna; Wallerstein, Robert; Lin, Henry J.

    2014-01-01

    Objectives Autosomal recessive long QT syndrome (LQTS), or Jervell and Lange-Nielsen syndrome (JLNS), can be associated with sensorineural hearing loss (SNHL). We aimed to explore newborn hearing screening combined with ECGs for early JLNS detection. Study design We conducted California statewide, prospective ECG screening of children ≤6 years of age with unilateral or bilateral, severe or profound, sensorineural or mixed hearing loss. Families were identified through newborn hearing screening and interviewed about medical and family histories. Twelve-lead ECGs were obtained. Those with positive histories or QTc intervals ≥450 ms had repeat ECGs. DNA sequencing of 12 LQTS genes was performed for repeat QTc intervals ≥450 ms. Results We screened 707 subjects by ECGs (number screened/number of responses = 91%; number of responses/number of families who were mailed invitations = 54%). Of these, 73 had repeat ECGs, and 19 underwent gene testing. No subject had homozygous or compound heterozygous LQTS mutations, as in JLNS. However, 3 individuals (with QTc intervals of 472, 457, and 456 ms, respectively) were heterozygous for variants that cause truncation or missplicing: 2 in KCNQ1 (c.1343dupC or p.Glu449Argfs*14; c.1590+1G>A or p.Glu530sp) and 1 in SCN5A (c.5872C>T or p.Arg1958*). Conclusions In contrast to reports of JLNS in up to 4% of children with SNHL, we found no examples of JLNS. Because the 3 variants identified were unrelated to hearing, they likely represent the prevalence of potential LQTS mutations in the general population. Further studies are needed to define consequences of such mutations and assess the overall prevalence. PMID:24388587

  8. Homozygous/Compound Heterozygous Triadin Mutations Associated With Autosomal-Recessive Long-QT Syndrome and Pediatric Sudden Cardiac Arrest: Elucidation of the Triadin Knockout Syndrome.

    PubMed

    Altmann, Helene M; Tester, David J; Will, Melissa L; Middha, Sumit; Evans, Jared M; Eckloff, Bruce W; Ackerman, Michael J

    2015-06-09

    Long-QT syndrome (LQTS) may result in syncope, seizures, or sudden cardiac arrest. Although 16 LQTS-susceptibility genes have been discovered, 20% to 25% of LQTS remains genetically elusive. We performed whole-exome sequencing child-parent trio analysis followed by recessive and sporadic inheritance modeling and disease-network candidate analysis gene ranking to identify a novel underlying genetic mechanism for LQTS. Subsequent mutational analysis of the candidate gene was performed with polymerase chain reaction, denaturing high-performance liquid chromatography, and DNA sequencing on a cohort of 33 additional unrelated patients with genetically elusive LQTS. After whole-exome sequencing and variant filtration, a homozygous p.D18fs*13 TRDN-encoded triadin frameshift mutation was discovered in a 10-year-old female patient with LQTS with a QTc of 500 milliseconds who experienced recurrent exertion-induced syncope/cardiac arrest beginning at 1 year of age. Subsequent mutational analysis of TRDN revealed either homozygous or compound heterozygous frameshift mutations in 4 of 33 unrelated cases of LQTS (12%). All 5 TRDN-null patients displayed extensive T-wave inversions in precordial leads V1 through V4, with either persistent or transient QT prolongation and severe disease expression of exercise-induced cardiac arrest in early childhood (≤3 years of age) and required aggressive therapy. The overall yield of TRDN mutations was significantly greater in patients ≤10 years of age (5 of 10, 50%) compared with older patients (0 of 24, 0%; P=0.0009). We identified TRDN as a novel underlying genetic basis for recessively inherited LQTS. All TRDN-null patients had strikingly similar phenotypes. Given the recurrent nature of potential lethal arrhythmias, patients fitting this phenotypic profile should undergo cardiac TRDN genetic testing. © 2015 American Heart Association, Inc.

  9. Evaluation of QT Dispersion in Children with Breath Holding Spells.

    PubMed

    Movahedian, Amir Hosein; Heidarzadeh Arani, Marzieh; Motaharizad, Davood; Mousavi, Gholam Abbas; Mosayebi, Ziba

    2016-01-01

    Breath holding spells (BHS) are common involuntary reflexes in infancy and early childhood. Differential diagnosis should embrace Long QT Syndrome (LQTS) and paroxysmal abnormalities of rhythm. The aim of this study was to compare QT dispersion (QTd) in children with breath holding spells and normal controls. QT dispersion and Corrected QT(QTc) dispersion were measured in 12 lead surface electrocardiograms in 56 patients with BHS and compared with healthy children of the same age referred to the clinic for regular checkup visits. The most common type of BHS was cyanotic (83.9%). Seven patients (12.5%) had pallid and two patients (3.5%) had mixed spells. There was a history of breath holding spells in 33.9% of the children. QT dispersion was 61.6± 22.5 and 47.1±18.8 ms in patient and control groups, respectively. QTc dispersion (QTcd) was 104 ± 29.6 and 71.9 ±18.2 ms, respectively. There was a significant difference between patient and control groups in terms of QTd and QTcd (P<0.001). QTd and QTcd were increased in children with BHS. Therefore, the evaluation of EKG for early diagnosis of rhythm abnormalities seems reasonable in these children.

  10. Long QT Syndrome Leading to Multiple Cardiac Arrests After Posaconazole Administration in an Immune-Compromised Patient with Sepsis: An Unusual Case Report.

    PubMed

    Panos, George; Velissaris, Dimitrios; Karamouzos, Vasilios; Matzaroglou, Charalampos; Tylianakis, Minos

    2016-04-29

    We present the case of a septic patient with severe immunodeficiency, who developed QT interval prolongation followed by episodes of lethal cardiac arrhythmia. Cardiac events occurred after posaconazole administration, incriminating posaconazole use, alone or in combination with voriconazole, as the culpable agent. A 26-year-old female patient underwent orthopedic surgery to remove ectopic calcifications in her left hip joint. On the first post-operative day she became septic due to a surgical wound infection. Despite being treated according to the therapeutic protocols for sepsis, no clinical improvement was noticed and further assessment revealed an underlying immunodeficiency. Considering the underlying immunodeficiency and to that point poor clinical response, an antifungal agent was added to the antibiotic regiment. Following discontinuation of multiple antifungal agents due to adverse effects, posaconazole was administered. Posaconazole oral intake was followed by episodes of bradycardia and QT interval prolongation. The patient suffered continuous incidents of cardiac arrest due to polymorphic ventricular tachycardia (torsades des pointes) that degenerated to lethal ventricular fibrillation. Posaconazole was immediately discontinued and a temporary pacemaker was installed. The patient finally recovered without any neurological deficit, and was discharged in a good clinical status. Close cardiac monitoring is recommended in cases where posaconazole administration is combined with coexisting risk factors, as they may lead to severe ECG abnormalities and cardiac arrhythmias such as long QT interval syndrome and torsades de pointes. Posaconazole interactions with medications metabolized via the CYP3A4 pathway should be considered an additional risk factor for lethal cardiac incidents.

  11. Re-trafficking of hERG reverses long QT syndrome 2 phenotype in human iPS-derived cardiomyocytes.

    PubMed

    Mehta, Ashish; Sequiera, Glen Lester; Ramachandra, Chrishan J A; Sudibyo, Yuliansa; Chung, Yingying; Sheng, Jingwei; Wong, Keng Yean; Tan, Teng Hong; Wong, Philip; Liew, Reginald; Shim, Winston

    2014-06-01

    Long QT syndrome 2 (LQTS2) caused by missense mutations in hERG channel is clinically associated with abnormally prolonged ventricular repolarization and sudden cardiac deaths. Modelling monogenic arrhythmogenic diseases using human-induced pluripotent stem cells (hiPSCs) offers unprecedented mechanistic insights into disease pathogenesis. We utilized LQTS2-hiPSC-derived cardiomyocytes (CMs) to elucidate pathological changes and to demonstrate reversal of LQTS2 phenotype in a therapeutic intervention using a pharmacological agent, (N-[N-(N-acetyl-l-leucyl)-l-leucyl]-l-norleucine) (ALLN). We generated LQTS2-specific CMs (A561V missense mutation in KCNH2) from iPSCs using the virus-free reprogramming method. These CMs recapitulate dysfunction of hERG potassium channel with diminished IKr currents, prolonged repolarization durations, and elevated arrhythmogenesis due to reduced membrane localization of glycosylated/mature hERG. Dysregulated expression of folding chaperones and processing proteasomes coupled with sequestered hERG in the endoplasmic reticulum confirmed trafficking-induced disease manifestation. Treatment with ALLN, not only increased membrane localization of mature hERG but also reduced repolarization, increased IKr currents and reduced arrhythmogenic events. Diverged from biophysical interference of hERG channel, our results show that modulation of chaperone proteins could be therapeutic in LQTS2 treatment. Our in vitro study shows an alternative approach to rescue diseased LQTS2 phenotype via corrective re-trafficking therapy using a small chemical molecule, such as ALLN. This potentially novel approach may have ramifications in other clinically relevant trafficking disorders. Published on behalf of the European Society of Cardiology. All rights reserved. © The Author 2014. For permissions please email: journals.permissions@oup.com.

  12. The link between abnormal calcium handling and electrical instability in acquired long QT syndrome--Does calcium precipitate arrhythmic storms?

    PubMed

    Němec, Jan; Kim, Jong J; Salama, Guy

    2016-01-01

    Release of Ca(2+) ions from sarcoplasmic reticulum (SR) into myocyte cytoplasm and their binding to troponin C is the final signal form myocardial contraction. Synchronous contraction of ventricular myocytes is necessary for efficient cardiac pumping function. This requires both shuttling of Ca(2+) between SR and cytoplasm in individual myocytes, and organ-level synchronization of this process by means of electrical coupling among ventricular myocytes. Abnormal Ca(2+) release from SR causes arrhythmias in the setting of CPVT (catecholaminergic polymorphic ventricular tachycardia) and digoxin toxicity. Recent optical mapping data indicate that abnormal Ca(2+) handling causes arrhythmias in models of both repolarization impairment and profound bradycardia. The mechanisms involve dynamic spatial heterogeneity of myocardial Ca(2+) handling preceding arrhythmia onset, cell-synchronous systolic secondary Ca(2+) elevation (SSCE), as well as more complex abnormalities of intracellular Ca(2+) handling detected by subcellular optical mapping in Langendorff-perfused hearts. The regional heterogeneities in Ca(2+) handling cause action potential (AP) heterogeneities through sodium-calcium exchange (NCX) activation and eventually overwhelm electrical coupling of the tissue. Divergent Ca(2+) dynamics among different myocardial regions leads to temporal instability of AP duration and - on the patient level - in T wave lability. Although T-wave alternans has been linked to cardiac arrhythmias, non-alternans lability is observed in pre-clinical models of the long QT syndrome (LQTS) and CPVT, and in LQTS patients. Analysis of T wave lability may provide a real-time window on the abnormal Ca(2+) dynamics causing specific arrhythmias such as Torsade de Pointes (TdP).

  13. Cellular mechanisms underlying the increased disease severity seen for patients with long QT syndrome caused by compound mutations in KCNQ1.

    PubMed

    Harmer, Stephen C; Mohal, Jagdeep S; Royal, Alice A; McKenna, William J; Lambiase, Pier D; Tinker, Andrew

    2014-08-15

    The KCNQ1 (potassium voltage-gated channel, KQT-like subfamily, member 1) gene encodes the Kv7.1 potassium channel which forms a complex with KCNE1 (potassium voltage-gated channel Isk-related family member 1) in the human heart to produce the repolarizing IKs (slow delayed rectifier potassium current). Mutations in KCNQ1 can perturb IKs function and cause LQT1 (long QT syndrome type 1). In LQT1, compound mutations are relatively common and are associated with increased disease severity. LQT1 compound mutations have been shown to increase channel dysfunction, but whether other disease mechanisms, such as defective channel trafficking, contribute to the increase in arrhythmic risk has not been determined. Using an imaging-based assay we investigated the effects of four compound heterozygous mutations (V310I/R594Q, A341V/P127T, T391I/Q530X and A525T/R518X), one homozygous mutation (W248F) and one novel compound heterozygous mutation (A178T/K422fs39X) (where fs denotes frameshift) on channel trafficking. By analysing the effects in the equivalent of a homozygous, heterozygous and compound heterozygous condition, we identify three different types of behaviour. A341V/P127T and W248F/W248F had no effect, whereas V310I/R594Q had a moderate, but not compound, effect on channel trafficking. In contrast, T391I/Q530X, A525T/R518X and A178T/K422fs39X severely disrupted channel trafficking when expressed in compound form. In conclusion, we have characterized the disease mechanisms for six LQT1 compound mutations and report that, for four of these, defective channel trafficking underlies the severe clinical phenotype.

  14. Trafficking-deficient hERG K⁺ channels linked to long QT syndrome are regulated by a microtubule-dependent quality control compartment in the ER.

    PubMed

    Smith, Jennifer L; McBride, Christie M; Nataraj, Parvathi S; Bartos, Daniel C; January, Craig T; Delisle, Brian P

    2011-07-01

    The human ether-a-go-go related gene (hERG) encodes the voltage-gated K(+) channel that underlies the rapidly activating delayed-rectifier current in cardiac myocytes. hERG is synthesized in the endoplasmic reticulum (ER) as an "immature" N-linked glycoprotein and is terminally glycosylated in the Golgi apparatus. Most hERG missense mutations linked to long QT syndrome type 2 (LQT2) reduce the terminal glycosylation and functional expression. We tested the hypothesis that a distinct pre-Golgi compartment negatively regulates the trafficking of some LQT2 mutations to the Golgi apparatus. We found that treating cells in nocodazole, a microtubule depolymerizing agent, altered the subcellular localization, functional expression, and glycosylation of the LQT2 mutation G601S-hERG differently from wild-type hERG (WT-hERG). G601S-hERG quickly redistributed to peripheral compartments that partially colocalized with KDEL (Lys-Asp-Glu-Leu) chaperones but not calnexin, Sec31, or the ER golgi intermediate compartment (ERGIC). Treating cells in E-4031, a drug that increases the functional expression of G601S-hERG, prevented the accumulation of G601S-hERG to the peripheral compartments and increased G601S-hERG colocalization with the ERGIC. Coexpressing the temperature-sensitive mutant G protein from vesicular stomatitis virus, a mutant N-linked glycoprotein that is retained in the ER, showed it was not restricted to the same peripheral compartments as G601S-hERG at nonpermissive temperatures. We conclude that the trafficking of G601S-hERG is negatively regulated by a microtubule-dependent compartment within the ER. Identifying mechanisms that prevent the sorting or promote the release of LQT2 channels from this compartment may represent a novel therapeutic strategy for LQT2.

  15. Mutations in Danish patients with long QT syndrome and the identification of a large founder family with p.F29L in KCNH2

    PubMed Central

    2014-01-01

    Background Long QT syndrome (LQTS) is a cardiac ion channelopathy which presents clinically with palpitations, syncope or sudden death. More than 700 LQTS-causing mutations have been identified in 13 genes, all of which encode proteins involved in the execution of the cardiac action potential. The most frequently affected genes, covering > 90% of cases, are KCNQ1, KCNH2 and SCN5A. Methods We describe 64 different mutations in 70 unrelated Danish families using a routine five-gene screen, comprising KCNQ1, KCNH2 and SCN5A as well as KCNE1 and KCNE2. Results Twenty-two mutations were found in KCNQ1, 28 in KCNH2, 9 in SCN5A, 3 in KCNE1 and 2 in KCNE2. Twenty-six of these have only been described in the Danish population and 18 are novel. One double heterozygote (1.4% of families) was found. A founder mutation, p.F29L in KCNH2, was identified in 5 “unrelated” families. Disease association, in 31.2% of cases, was based on the type of mutation identified (nonsense, insertion/deletion, frameshift or splice-site). Functional data was available for 22.7% of the missense mutations. None of the mutations were found in 364 Danish alleles and only three, all functionally characterised, were recorded in the Exome Variation Server, albeit at a frequency of < 1:1000. Conclusion The genetic etiology of LQTS in Denmark is similar to that found in other populations. A large founder family with p.F29L in KCNH2 was identified. In 48.4% of the mutations disease causation was based on mutation type or functional analysis. PMID:24606995

  16. Type 4 cardiorenal syndrome.

    PubMed

    Pinheiro da Silva, Ana Luísa; Vaz da Silva, Manuel Joaquim

    2016-11-01

    The Acute Dialysis Quality Initiative consensus conference proposed a classification of cardiorenal syndrome (CRS), aiming for a better delineation of each subtype. Although the exact pathophysiology of type 4 CRS is not completely understood, the mechanisms involved are probably multifactorial. There is growing evidence that oxidative stress is a major connector in the development and progression of type 4 CRS. Giving its complexity, poor prognosis and increasing incidence, type 4 CRS is becoming a significant public health problem. Patients with chronic kidney disease are particularly predisposed to cardiac dysfunction, due to the high prevalence of traditional cardiovascular risk factors in this population, but the contribution of risk factors specific to chronic kidney disease should also be taken into account. Much remains to be elucidated about type 4 CRS: despite progress over the last decade, there are still significant questions regarding its pathophysiology and there is as yet no specific therapy. A better understanding of the mechanisms involved may provide potential targets for intervention. The present review will provide a brief description of the definition, epidemiology, diagnosis, prognosis, biomarkers and management strategies of type 4 CRS, and the pathophysiological mechanisms and risk factors presumably involved in its development will be particularly highlighted. Copyright © 2016 Sociedade Portuguesa de Cardiologia. Publicado por Elsevier España, S.L.U. All rights reserved.

  17. Ion channel mechanisms related to sudden cardiac death in phenotype-negative long-QT syndrome genotype-phenotype correlations of the KCNQ1(S349W) mutation.

    PubMed

    Horr, Samuel; Goldenberg, Ilan; Moss, Arthur J; O-Uchi, Jin; Barsheshet, Alon; Connelly, Heather; Gray, Daniel A; Zareba, Wojciech; Lopes, Coeli M B

    2011-02-01

      Data regarding possible ion channel mechanisms that predispose to ventricular tachyarrhythmias in patients with phenotype-negative long-QT syndrome (LQTS) are limited. We carried out cellular expression studies for the S349W mutation in the KCNQ1 channel, which was identified in 15 patients from the International LQTS Registry who experienced a high rate of cardiac events despite lack of significant QTc prolongation. The clinical outcome of S349W mutation carriers was compared with that of QTc-matched carriers of haploinsufficient missense (n = 30) and nonsense (n = 45) KCNQ1 mutations. The channels containing the mutant S349W subunit showed a mild reduction in current (<50%), in the haploinsuficient range, with an increase in maximal conductance compared with wild-type channels. In contrast, expression of the S349W mutant subunit produced a pronounced effect on both the voltage dependence of activation and the time constant of activation, while haploinsuficient channels showed no effect on either parameter. The cumulative probability of cardiac events from birth through age 20 years was significantly higher among S349W mutation carriers (58%) as compared with carriers of QTc-matched haploinsufficent missense (21%, P = 0.004) and nonsense (25%, P = 0.01) mutations. The S349W mutation in the KCNQ1 potassium channel exerts a relatively mild effect on the ion channel current, whereas an increase in conductance compensates for impaired voltage activation of the channel. The changes observed in voltage activation of the channel may underlie the mechanisms predisposing to arrhythmic risk among LQTS patients with a normal-range QTc. © 2010 Wiley Periodicals, Inc.

  18. Physiological Properties of hERG 1a/1b Heteromeric Currents and a hERG 1b-specific Mutation Associated with Long QT Syndrome

    PubMed Central

    Sale, Harinath; Wang, Jinling; O'Hara, Thomas J.; Tester, David J.; Phartiyal, Pallavi; He, Jia-Qiang; Rudy, Yoram; Ackerman, Michael J.; Robertson, Gail A.

    2009-01-01

    Cardiac IKr is a critical repolarizing current in the heart and a target for inherited and acquired long QT syndrome (LQTS). Biochemical and functional studies have demonstrated that IKr channels are heteromers composed of both hERG 1a and 1b subunits, yet our current understanding of IKr functional properties derives primarily from studies of homo-oligomers of the original hERG 1a isolate. Here we examine currents produced by hERG 1a and 1a/1b channels expressed in HEK-293 cells at near-physiological temperatures. We find that heteromeric hERG 1a/1b currents are much larger than hERG 1a currents and conduct 80% more charge during an action potential. This surprising difference corresponds to a two-fold increase in the apparent rates of activation and recovery from inactivation, thus reducing rectification and facilitating current rebound during repolarization. Kinetic modeling shows these gating differences account quantitatively for the differences in current amplitude between the two channel types. Drug sensitivity was also different. Compared to homomeric 1a channels, heteromeric 1a/1b channels were inhibited by E-4031 with a slower time course and a corresponding four-fold shift in the IC50. The importance of hERG 1b in vivo is supported by the identification of a 1b-specific A8V missense mutation in 1/269 unrelated genotype-negative LQTS patients and absent in 400 control alleles. Mutant 1bA8V expressed alone or with hERG 1a in HEK-293 cells dramatically reduced 1b protein levels. Thus, mutations specifically disrupting hERG 1b function are expected to reduce cardiac IKr and enhance drug sensitivity, and represent a potential mechanism underlying inherited or acquired LQTS. PMID:18776039

  19. Vagal Reflexes Following an Exercise Stress Test: a Simple Clinical Tool for Gene-Specific Risk Stratification in the Long QT Syndrome

    PubMed Central

    Crotti, Lia; Spazzolini, Carla; Porretta, Alessandra P.; Dagradi, Federica; Taravelli, Erika; Petracci, Barbara; Vicentini, Alessandro; Pedrazzini, Matteo; Rovere, Maria Teresa La; Vanoli, Emilio; Goosen, Althea; Heradien, Marshall; Brink, Paul A.; George, Alfred L.; Schwartz, Peter J.

    2012-01-01

    Objectives To assess whether heart rate (HR) reduction following an exercise stress test (ExStrT), an easily quantifiable marker of vagal reflexes, might identify high and low risk long QT syndrome (LQTS) type 1 (LQT1) patients. Background Identification of LQTS patients more likely to be symptomatic remains elusive. We have previously shown that depressed baroreflex sensitivity (BRS), an established marker of reduced vagal reflexes, predicts low probability of symptoms among LQT1. Methods We studied 169 LQTS genotype-positive patients below age 50 who performed an ExStrT with the same protocol, on and off β-blockers including 47 South African LQT1 patients all harboring the KCNQ1-A341V mutation and 122 Italian LQTS patients with impaired (IKs−, LQT1, n=66) or normal (IKs+, 50 LQT2 and 6 LQT3) IKs current. Results Despite similar maximal HR and workload, by the first minute after cessation of exercise the symptomatic patients in both IKs− groups had a greater HR reduction compared to the asymptomatic (19±7 vs 13±5 and 27±10 vs 20±8 bpm, both p=0.009). By contrast, there was no difference between the IKs+ symptomatic and asymptomatic patients (23±9 vs 26±9 bpm, p=0.47). LQT1 patients in the upper tertile for HR reduction had a higher risk of being symptomatic (OR 3.28, 95% CI 1.3–8.3, p=0.012). Conclusions HR reduction following exercise identifies LQT1 patients at high or low arrhythmic risk, independently of β-blocker therapy, and contributes to risk stratification. Exercise training, which potentiates vagal reflexes, should be avoided by LQT1 patients. PMID:23158531

  20. The effect of 25-hydroxyvitamin D levels on QT interval duration and dispersion in type 2 diabetic patients

    PubMed Central

    Yetkin, Demet Ozgil; Kucukkaya, Belgin; Turhan, Mehtap; Oren, Merve

    2015-01-01

    Aim To assess the relationship between corrected QT (QTc) interval and vitamin 25-hydroxyvitamin D levels (25-OHD) deficiency in type 2 diabetic patients. Methods The study included 253 patients with type 2 diabetes and 170 age-matched controls treated between October and December 2013. QTc duration and QTc dispersion were measured on ECG recordings and 25-OHD, calcium, phosphorus, and blood glucose levels were determined. Results Patients with diabetes had significantly longer QTc duration and QTc dispersion than controls (P < 0.001 and P < 0.001 respectively). Diabetic patients with prolonged QTc duration were older and had longer diabetes duration and higher HbA1c levels than patients with normal QTc interval. They significantly more frequently had 25-OHD deficiency (P < 0.001), but had similar calcium and phosphorus levels. Diabetic patients with prolonged QTc dispersion were of similar age and had similar diabetes duration and HbA1c levels as patients with normal QTc dispersion. They significantly more frequently had 25-OHD deficiency (P = 0.010), but had similar calcium and phosphorus levels. Conclusion This study showed prolonged QTc duration and QTc dispersion in patients with type 2 diabetes, especially those with 25-OHD deficiency. PMID:26718758

  1. Prolonged Tp-e Interval, Tp-e/QT Ratio and Tp-e/QTc Ratio in Patients with Type 2 Diabetes Mellitus.

    PubMed

    Tokatli, Alptug; Kiliçaslan, Fethi; Alis, Metin; Yiginer, Omer; Uzun, Mehmet

    2016-03-01

    Type 2 diabetes mellitus (T2DM) is associated with increased risk of malignant ventricular arrhythmias. Cardiac electrical inhomogeneity may be the leading cause of the increased arrhythmic risk in patients with T2DM. The peak and the end of the T wave (Tp-e) interval and associated Tp-e/QT ratio are promising measures of ventricular repolarization indicating transmural dispersion of repolarization. The aim of this study was to assess ventricular repolarization in patients with T2DM by using Tp-e interval, Tp-e/QT ratio and Tp-e/corrected QT interval (QTc) ratio. Forty-three patients with T2DM and 43 healthy control subjects, matched by gender and age, were studied. All participants underwent electrocardiography (ECG) recording. PR, RR and QT intervals represents the ECG intervals. These are not abbreviations. In all literature these ECG intervals are written like in this text. Tp-e intervals were measured from 12-lead ECG. Rate QTc was calculated by using the Bazett's formula. Tp-e/QT ratio and Tp-e/QTc ratio were also calculated. Mean Tp-e interval was significantly prolonged in patients with T2DM compared to controls (79.4±10.3, 66.4±8.1 ms, respectively; P<0.001). We also found significantly higher values of Tp-e/QT ratio and Tp-e/QTc ratio in patients with diabetes than controls (0.21±0.03, 0.17±0.02 and 0.19±0.02, 0.16±0.02, respectively; P<0.001). There was no difference in terms of the other ECG parameters between the groups. Tp-e interval, Tp-e/QT ratio and Tp-e/QTc ratio were prolonged in patients with T2DM. We concluded that T2DM leads to augmentation of transmural dispersion of repolarization suggesting increased risk for ventricular arrhythmogenesis.

  2. Electrophysiological effects of cetirizine, astemizole and D-sotalol in a canine model of long QT syndrome.

    PubMed

    Weissenburger, J; Noyer, M; Cheymol, G; Jaillon, P

    1999-07-01

    Observations of torsades de pointes during therapy with terfenadine and astemizole has raised concern about the cardiac safety of non-sedating H1-antagonist agents. We compared cetirizine, another compound of that class, to D-sotalol and to astemizole in a model of acquired long QT syndrome. Open-chest surgery was performed in adult beagle dogs anaesthetized with halothane and thiopental. Bradycardia was produced with beta-adrenergic blockade and sinus node crush. Four left ventricular intramyocardial unipolar monophasic action potentials (MAP) were recorded during atrial pacing at basic cycle lengths (BCL) 400-1500 msec, before and during three successive 1-h drug infusions (0.14, 0.45 and 1.4 mg/kg/h for astemizole and cetirizine and 1.1, 2.2 and 4.5 mg/kg/h for D-sotalol). Dose- and bradycardia-dependent prolongations of MAP duration (MAPD) were produced by D-sotalol (P < 0.001) and astemizole (P < 0.001) but not by cetirizine. At BCL 1500 ms, the three infusions of astemizole prolonged endocardial MAPD from 323 +/- 8 msec (mean +/- SE) at baseline to 343 +/- 10, 379 +/- 13 and 468 +/- 26 msec, respectively (n = 9). Sotalol prolonged that MAPD from 339 +/- 6 msec to 377 +/- 7, 444 +/- 15 and 485 +/- 24 msec (n = 7). In contrast, cetirizine did not prolong MAPD: 341 +/- 8 msec at baseline Vs 330 +/- 8, 324 +/- 9 and 323 +/- 11 msec (n = 9). Drug-induced increase in transmural dispersion reached +79 +/- 19 msec after astemizole, +59 +/- 21 msec after D-sotalol and only +7 +/- 11 msec after cetirizine. Runs of ventricular tachycardias and torsades de pointes occurred during dose three of astemizole (5/9 dogs) and D-sotalol (4/7 dogs) but never during cetirizine. In the present model, astemizole and D-sotalol but not cetirizine prolonged MAPD and transmural dispersions of repolarization and produced torsades de pointes. These results suggest that the halothane-anaesthetized bradycardic dog could be a valuable model to discriminate drugs for their class III effects

  3. Improved Clinical Risk Stratification in Patients with Long QT Syndrome? Novel Insights from Multi-Channel ECGs

    PubMed Central

    Samol, Alexander; Gönes, Mehmet; Zumhagen, Sven; Bruns, Hans-Jürgen; Paul, Matthias; Vahlhaus, Christian; Waltenberger, Johannes; Schulze-Bahr, Eric; Eckardt, Lars; Mönnig, Gerold

    2016-01-01

    Background We investigated whether multichannel ECG-recordings are useful to risk-stratify patients with congenital long-QT syndrome (LQTS) for risk of sudden cardiac death under optimized medical treatment. Methods In 34 LQTS-patients (11 male; age 31±13 years, QTc 478±51ms; LQT1 n = 8, LQT2 n = 15) we performed a standard 12-channel ECG and a 120-channel body surface potential mapping. The occurrence of clinical events (CE; syncope, torsade de pointes (TdP), sudden cardiac arrest (SCA)) was documented and correlated with different ECG-parameters in all lead positions. Results Seven patients developed TdP, four survived SCA and 12 experienced syncope. 12/34 had at least one CE. CE was associated with a longer QTc-interval (519±43ms vs. 458±42ms; p = 0.001), a lower T-wave integral (TWI) on the left upper chest (-1.2±74.4mV*ms vs. 63.0±29.7mV*ms; p = 0.001), a lower range of T-wave amplitude (TWA) in the region of chest lead V8 (0.10±0.08mV vs. 0.18±0.07mV; p = 0.008) and a longer T-peak-T-end time (TpTe) in lead V1 (98±23ms vs. 78±26ms; p = 0.04). Receiver-operating-characteristic (ROC) analyses revealed a sensitivity of 96% and a specificity of 75% (area under curve (AUC) 0.89±0.06, p = 0.001) at a cut-off value of 26.8mV*ms for prediction of CE by TWI, a sensitivity of 86% and a specificity of 83% at a cut-off value of 0.11mV (AUC 0.83±0.09, p = 0.002) for prediction of CE by TWA and a sensitivity of 83% and a specificity of 73% at a cut-off value of 87ms (AUC 0.80±0.07, p = 0.005) for prediction of CE by TpTe. Conclusions Occurrence of CE in LQTS-patients seems to be associated with a prolonged, low-amplitude T-wave. PMID:27379800

  4. Role of Sarcoplasmic Reticulum Calcium in Development of Secondary Calcium Rise and Early Afterdepolarizations in Long QT Syndrome Rabbit Model

    PubMed Central

    Chang, Po-Cheng; Wo, Hung-Ta; Lee, Hui-Ling; Lin, Shien-Fong; Wen, Ming-Shien; Chu, Yen; Yeh, San-Jou; Chou, Chung-Chuan

    2015-01-01

    Background L-type calcium current reactivation plays an important role in development of early afterdepolarizations (EADs) and torsades de pointes (TdP). Secondary intracellular calcium (Cai) rise is associated with initiation of EADs. Objective To test whether inhibition of sarcoplasmic reticulum (SR) Ca2+ cycling suppresses secondary Cai rise and genesis of EADs. Methods Langendorff perfusion and dual voltage and Cai optical mapping were conducted in 10 rabbit hearts. Atrioventricular block (AVB) was created by radiofrequency ablation. After baseline studies, E4031, SR Ca2+ cycling inhibitors (ryanodine plus thapsigargin) and nifedipine were then administrated subsequently, and the protocols were repeated. Results At baseline, there was no spontaneous or pacing-induced TdP. After E4031 administration, action potential duration (APD) was significantly prolonged and the amplitude of secondary Cai rise was enhanced, and 7 (70%) rabbits developed spontaneous or pacing-induced TdP. In the presence of ryanodine plus thapsigargin, TdP inducibility was significantly reduced (2 hearts, 20%, p = 0.03). Although APD was significantly prolonged (from 298 ± 30 ms to 457 ± 75 ms at pacing cycle length of 1000 m, p = 0.007) by ryanodine plus thapsigargin, the secondary Cai rise was suppressed (from 8.8 ± 2.6% to 1.2 ± 0.9%, p = 0.02). Nifedipine inhibited TdP inducibility in all rabbit hearts. Conclusion In this AVB and long QT rabbit model, inhibition of SR Ca2+ cycyling reduces the inducibility of TdP. The mechanism might be suppression of secondary Cai rise and genesis of EADs. PMID:25875599

  5. Delineation of the phenotype associated with 7q36.1q36.2 deletion: long QT syndrome, renal hypoplasia and mental retardation.

    PubMed

    Caselli, Rossella; Mencarelli, Maria Antonietta; Papa, Filomena Tiziana; Ariani, Francesca; Longo, Ilaria; Meloni, Ilaria; Vonella, Giuseppina; Acampa, Maurizio; Auteri, Alberto; Vicari, Stefano; Orsi, Alessandra; Hayek, Giuseppe; Renieri, Alessandra; Mari, Francesca

    2008-05-01

    Terminal deletions of the long arm of chromosome 7 are well known and are frequently associated with hypotelorism or holoprosencephaly due to the involvement of the SHH gene located in 7q36.3. These deletions are easily detectable with routine subtelomeric MLPA analysis. Deletions affecting a more proximal part of 7q36, namely bands 7q36.1q36.2 are less common, and may be missed by subtelomeric MLPA analysis. We report a 9-year-old girl with a 5.27 Mb deletion in 7q36.1q36.2, and compare her to literature patients proposing a phenotype characterized by mental retardation, unusual facial features, renal hypoplasia and long QT syndrome due to loss of the KCNH2 gene. These characteristics are sufficiently distinct that the syndrome may be diagnosed on clinical grounds.

  6. QT Prolongation Following Ectopic Beats: Initial Data Regarding The Upper Limit Of Normal With Possible Implications For Antiarrhythmic Therapy And Concealed (Unexpressed) Long QT.

    PubMed

    Reiffel, Alyssa J; Reiffel, James A

    2009-01-01

    Background: Ectopic beats are frequently associated with morphologic repolarization alterations of ensuing sinus beats. Less is known about repolarization duration alterations of post-ectopic sinus beats. In one patient who developed long QT and torsades de pointes upon exposure to a class III antiarrhythmic drug, and was later genotyped as being a carrier for long QT syndrome (LQTS) type 1, review of a pre-drug Holter monitor study revealed marked QT prolongation of post-ectopic sinus beats. In wondering whether this might be a common clue to "concealed" unexpressed LQTS, we realized that we must first characterize the range of post-ectopic QT prolongation present in normals. Prolongation beyond the upper limit of this range might then raise suspicion of possible LQTS and alter the antiarrhythmic drug selection process for the suppression of atrial fibrillation or other arrhythmias. Methods: Accordingly, we assessed the presence/degree of repolarization prolongation following premature ectopic impulses in 166 subjects with normal conduction intervals and normal repolarization on their resting 12-lead ECG, 75 of whom had no known associated cardiovascular disorder of any kind. That is, in our subjects, the maximal prolongation of the QT interval of the sinus beat following isolated ventricular and atrial premature complexes was characterized. Results: QT prolongation is common in post ectopic sinus beats. However, in our subjects the uncorrected QT interval of post-ectopic sinus beats never exceeded 480 ms in duration [which was much shorter than that seen (510-590 ms) in our gene carrier]. The QT interval in normal subjects may prolong following premature complexes but not to a value in excess of 480 ms.

  7. A novel transgenic rabbit model with reduced repolarization reserve: long QT syndrome caused by a dominant‐negative mutation of the KCNE1 gene

    PubMed Central

    Major, Péter; Baczkó, István; Hiripi, László; Odening, Katja E.; Juhász, Viktor; Kohajda, Zsófia; Horváth, András; Seprényi, György; Kovács, Mária; Virág, László; Jost, Norbert; Prorok, János; Ördög, Balázs; Doleschall, Zoltán; Nattel, Stanley; Varró, András

    2016-01-01

    Background and purpose The reliable assessment of proarrhythmic risk of compounds under development remains an elusive goal. Current safety guidelines focus on the effects of blocking the KCNH2/HERG ion channel‐in tissues and animals with intact repolarization. Novel models with better predictive value are needed that more closely reflect the conditions in patients with cardiac remodelling and reduced repolarization reserve. Experimental Approach We have developed a model for the long QT syndrome type‐5 in rabbits (LQT5 ) with cardiac‐specific overexpression of a mutant (G52R) KCNE1 β‐subunit of the channel that carries the slow delayed‐rectifier K+‐current (IKs). ECG parameters, including short‐term variability of the QT interval (STVQT), a biomarker for proarrhythmic risk, and arrhythmia development were recorded. In vivo, arrhythmia susceptibility was evaluated by i.v. administration of the IKr blocker dofetilide. K+ currents were measured with the patch‐clamp technique. Key Results Patch‐clamp studies in ventricular myocytes isolated from LQT5 rabbits revealed accelerated IKs and IKr deactivation kinetics. At baseline, LQT5 animals exhibited slightly but significantly prolonged heart‐rate corrected QT index (QTi) and increased STVQT. Dofetilide provoked Torsade‐de‐Pointes arrhythmia in a greater proportion of LQT5 rabbits, paralleled by a further increase in STVQT. Conclusion and Implications We have created a novel transgenic LQT5 rabbit model with increased susceptibility to drug‐induced arrhythmias that may represent a useful model for testing proarrhythmic potential and for investigations of the mechanisms underlying arrhythmias and sudden cardiac death due to repolarization disturbances. PMID:27076034

  8. Fluconazole-induced long QT syndrome via impaired human ether-a-go-go-related gene (hERG) protein trafficking in rabbits.

    PubMed

    Wang, Jinli; Wang, Guan; Quan, Xiaoqing; Ruan, Lei; Liu, Yang; Ruan, Yanfei; Liu, Nian; Zhang, Cuntai; Bai, Rong

    2017-07-01

    hERG protein trafficking deficiency has long been known in drug-induced long QT syndrome (LQTS). However, validated evidence from in vivo data kept scanty. Our goal was to investigate the proarrhythmic action of fluconazole and its underlying mechanism in an animal model. Twenty female Japanese long-eared white rabbits were randomly distributed into a control group and a fluconazole group for a chronic 2-week treatment. The control group was treated with 0.5% sodium carboxymethylcellulose (CMCNa), and the fluconazole group was treated with fluconazole. Electrocardiograms (ECGs) were recorded during the experimental period. Isolated arterially perfused left ventricular wedge preparations from the rabbits were made 2 weeks after treatment, and the arrhythmia events, the transmural ECG, and action potential from both the endocardium and epicardium were recorded. The changes in hERG protein expression were measured by western blot. The fluconazole group showed a longer QT interval 1 week after treatment (P < 0.05) and a higher arrhythmia occurrence 2 weeks after treatment (P < 0.05) than the control group. The fluconazole group also showed a longer transmural dispersion of repolarization and a higher occurrence of life-threatening torsades de pointes in arterially perfused left ventricular preparations. Furthermore, western blot analysis showed that the density of mature hERG protein was lower in the fluconazole group than that in the control group. Fluconazole can prolong the QT interval and possess proarrhythmic activity due to its inhibition of hERG protein trafficking in our experimental model. These findings may impact the clinical potential of fluconazole in humans.

  9. Long QT Syndrome

    MedlinePlus

    ... each heart muscle cell are tiny pores called ion channels. Ion channels open and close to let electrically charged sodium, ... electrical activity. In people who have LQTS, the ion channels may not work well, or there may be ...

  10. Time-to-Onset Analysis of Drug-Induced Long QT Syndrome Based on a Spontaneous Reporting System for Adverse Drug Events

    PubMed Central

    Sasaoka, Sayaka; Matsui, Toshinobu; Hane, Yuuki; Abe, Junko; Ueda, Natsumi; Motooka, Yumi; Hatahira, Haruna; Fukuda, Akiho; Naganuma, Misa; Hasegawa, Shiori; Kinosada, Yasutomi

    2016-01-01

    Long QT syndrome (LQTS) is a disorder of the heart’s electrical activity that infrequently causes severe ventricular arrhythmias such as a type of ventricular tachycardia called torsade de pointes (TdP) and ventricular fibrillation, which can be fatal. There have been no previous reports on the time-to-onset for LQTS based on data from spontaneous reporting systems. The aim of this study was to assess the time-to-onset of LQTS according to drug treatment. We analyzed the association between 113 drugs in 37 therapeutic categories and LQTS including TdP using data obtained from the Japanese Adverse Drug Event Report database. For signal detection, we used the reporting odds ratio (ROR). Furthermore, we analyzed the time-to-onset data and assessed the hazard type using the Weibull shape parameter. The RORs (95% confidence interval) for bepridil, amiodarone, pilsicainide, nilotinib, disopyramide, arsenic trioxide, clarithromycin, cibenzoline, donepezil, famotidine, sulpiride, and nifekalant were 174.4 (148.6–204.6), 17.3 (14.7–20.4), 52.0 (43.4–62.4), 13.9 (11.5–16.7), 69.3 (55.3–86.8), 54.2 (43.2–68.0), 4.7 (3.8–5.8), 19.9 (15.9–25.0), 8.1 (6.5–10.1), 3.2 (2.5–4.1), 7.1 (5.5–9.2), and 254.8 (168.5–385.4), respectively. The medians and quartiles of time-to-onset for aprindine (oral) and bepridil were 20.0 (11.0–35.8) and 18.0 (6.0–43.0) days, respectively. The lower 95% confidence interval of the shape parameter β of bepridil was over 1 and the hazard was considered to increase over time.Our study indicated that the pattern of LQTS onset might differ among drugs. Based on these results, careful long-term observation is recommended, especially for specific drugs such as bepridil and aprindine. This information may be useful for the prevention of sudden death following LQTS and for efficient therapeutic planning. PMID:27723808

  11. Familial qt prolongation and risk of sudden death.

    PubMed

    Furberg, C; Hörnell, H

    1975-09-01

    Two sisters with the syndrome of familial QT prolongation in the ECG and syncope are presented. A recently suggested mechanism of the syndrome is presented and preventive measures to reduce the risk of sudden death associated with it are proposed.

  12. Predictors of heart-focused anxiety in patients undergoing genetic investigation and counseling of long QT syndrome or hypertrophic cardiomyopathy: a one year follow-up.

    PubMed

    Hamang, Anniken; Eide, Geir Egil; Rokne, Berit; Nordin, Karin; Bjorvatn, Cathrine; Øyen, Nina

    2012-02-01

    Since Long QT syndrome and Hypertrophic cardiomyopathy are inherited cardiac disorders that may cause syncope, palpitations, serious arrhythmias, and sudden cardiac death, at-risk individuals may experience heart-focused anxiety. In a prospective multi-site study, 126 Norwegian patients attending genetic counseling were followed 1 year with multiple administration of questionnaires, including the Cardiac Anxiety Questionnaire, measuring three distinct symptoms of heart-focused anxiety- avoidance, attention, and fear-in mixed linear analyses. Overall, at 1-year follow-up, patients with clinical diagnosis as compared to patients at genetic risk had significantly higher scores of avoidance (p < .002), attention (p < .005), and fear (p < .007). Sudden cardiac death in close relatives, uncertainty whether other relatives previously had undergone genetic testing, patients' perceived general health, self-efficacy expectations and procedural satisfaction with genetic counseling were influential in predicting the different symptoms of heart-focused anxiety over time.

  13. Upgrade from ICD to CRT-D: clinical and haemodynamic impact of biventricular pacing in a patient with acquired long QT syndrome

    PubMed Central

    Kawecki, Damian; Jacheć, Wojciech; Wojciechowska, Celina; Morawski, Stanisław; Tomasik, Andrzej; Nowalany-Kozielska, Ewa

    2015-01-01

    Long QT syndrome (LQTS) is characterised by both the depolarisation and repolarisation disorder of cardiac muscle cells. Cardiac resynchronising therapy (CRT) is an important treatment option for patients with chronic heart failure (CHF) when echocardiographic and electrocardiographic criteria are met. Although CRT was introduced in clinical practice 10 years ago, doubts related to application of this treatment method persist because of its potential proarrhythmogenic effect. This is a case describing a 66-year-old Caucasian female with LQTS coexisting with a left bundle branch branch block (LBBB) and an implantable single-cavity cardioverter-defibrillator (ICD VR), who had repeated appropriate high-energy treatments. The upgrade to resynchronisation therapy defibrillator (CRT-D) significantly reduced frequency of ventricular tachycardia and the need for electrical therapies. The normalisation of the left ventricle size, as seen on echo examination, and the improvement of heart failure symptoms were also observed. PMID:28352686

  14. A Framework of Knowledge Integration and Discovery for Supporting Pharmacogenomics Target Predication of Adverse Drug Events: A Case Study of Drug-Induced Long QT Syndrome

    PubMed Central

    Jiang, Guoqian; Wang, Chen; Zhu, Qian; Chute, Christopher G.

    2013-01-01

    Knowledge-driven text mining is becoming an important research area for identifying pharmacogenomics target genes. However, few of such studies have been focused on the pharmacogenomics targets of adverse drug events (ADEs). The objective of the present study is to build a framework of knowledge integration and discovery that aims to support pharmacogenomics target predication of ADEs. We integrate a semantically annotated literature corpus Semantic MEDLINE with a semantically coded ADE knowledgebase known as ADEpedia using a semantic web based framework. We developed a knowledge discovery approach combining a network analysis of a protein-protein interaction (PPI) network and a gene functional classification approach. We performed a case study of drug-induced long QT syndrome for demonstrating the usefulness of the framework in predicting potential pharmacogenomics targets of ADEs. PMID:24303306

  15. Vagal reflexes following an exercise stress test: a simple clinical tool for gene-specific risk stratification in the long QT syndrome.

    PubMed

    Crotti, Lia; Spazzolini, Carla; Porretta, Alessandra P; Dagradi, Federica; Taravelli, Erika; Petracci, Barbara; Vicentini, Alessandro; Pedrazzini, Matteo; La Rovere, Maria Teresa; Vanoli, Emilio; Goosen, Althea; Heradien, Marshall; George, Alfred L; Brink, Paul A; Schwartz, Peter J

    2012-12-18

    The study assessed whether heart rate (HR) reduction following an exercise stress test (ExStrT), an easily quantifiable marker of vagal reflexes, might identify high- and low-risk long QT syndrome (LQTS) type 1 (LQT1) patients. Identification of LQTS patients more likely to be symptomatic remains elusive. We have previously shown that depressed baroreflex sensitivity, an established marker of reduced vagal reflexes, predicts low probability of symptoms among LQT1. We studied 169 LQTS genotype-positive patients < 50 years of age who performed an ExStrT with the same protocol, on and off β-blockers including 47 South African LQT1 patients all harboring the KCNQ1-A341V mutation and 122 Italian LQTS patients with impaired (I(Ks)-, 66 LQT1) or normal (I(Ks)+, 50 LQT2 and 6 LQT3) I(Ks) current. Despite similar maximal HR and workload, by the first minute after cessation of exercise the symptomatic patients in both I(Ks)- groups had a greater HR reduction compared with the asymptomatic (19 ± 7 beats/min vs. 13 ± 5 beats/min and 27 ± 10 beats/min vs. 20 ± 8 beats/min, both p = 0.009). By contrast, there was no difference between the I(Ks)+ symptomatic and asymptomatic patients (23 ± 9 beats/min vs. 26 ± 9 beats/min, p = 0.47). LQT1 patients in the upper tertile for HR reduction had a higher risk of being symptomatic (odds ratio: 3.28, 95% confidence interval: 1.3 to 8.3, p = 0.012). HR reduction following exercise identifies LQT1 patients at high or low arrhythmic risk, independently of β-blocker therapy, and contributes to risk stratification. Intense exercise training, which potentiates vagal reflexes, should probably be avoided by LQT1 patients. Copyright © 2012 American College of Cardiology Foundation. Published by Elsevier Inc. All rights reserved.

  16. The relationship between insulin sensitivity and heart rate-corrected QT interval in patients with type 2 diabetes.

    PubMed

    Yang, Xiao-Hua; Su, Jian-Bin; Zhang, Xiu-Lin; Zhao, Li-Hua; Xu, Feng; Wang, Xue-Qin; Cheng, Xing-Bo

    2017-01-01

    Reduced insulin sensitivity not only contributes to the pathogenesis of type 2 diabetes but is also linked to multiple metabolic risk factors and cardiovascular diseases (CVD). A prolonged heart rate-corrected QT interval (QTc interval) is related to ventricular arrhythmias and CVD mortality and exhibits a high prevalence among type 2 diabetes patients. The aim of the study was to investigate the relationship between insulin sensitivity and the QTc interval in patients with type 2 diabetes. This cross-sectional observational study recruited 2927 patients with type 2 diabetes who visited the Affiliated Haian Hospital and Second Affiliated Hospital of Nantong University. The insulin sensitivity index (Matsuda index, ISIMatsuda) derived from 75-g OGTT and other metabolic risk factors were examined in all patients. The QTc interval was estimated using a resting 12-lead electrocardiogram, and an interval longer than 440 ms was considered abnormally prolonged. The QTc interval was significantly and negatively correlated with the ISIMatsuda (r = -0.296, p < 0.001), and when the multiple linear regression analysis was adjusted for anthropometric parameters, metabolic risk factors, and current antidiabetic treatments, the QTc interval remained significantly correlated with the ISIMatsuda (β = -0.23, t = -12.63, p < 0.001). The proportion of patients with prolonged QTc interval significantly increased from 12.1% to 17.9%, 25.6% and 37.9% from the fourth to third, second and first quartile of the ISIMatsuda, respectively. After adjusting for anthropometric parameters by multiple logistic regression analysis, the corresponding odd ratios (ORs) for prolonged QTc interval of the first, second and third quartiles versus the fourth quartile of ISIMatsuda were 3.11 (95% CI 2.23-4.34), 2.09 (1.51-2.88) and 1.53 (1.09-2.14), respectively, and p for trend was <0.001. Reduced insulin sensitivity is associated with an increase in the QTc interval in patients with type 2

  17. Comparison of QT peak and QT end interval responses to autonomic adaptation in asymptomatic LQT1 mutation carriers

    PubMed Central

    Haapalahti, Petri; Viitasalo, Matti; Perhonen, Merja; Väänänen, Heikki; Mäkijärvi, Markku; Swan, Heikki; Toivonen, Lauri

    2011-01-01

    Background LQT1 subtype of long QT syndrome is characterized by defective IKs, which is intrinsically stronger in the epicardium than in the midmyocardial region. Electrocardiographic QT peak and QT end intervals may reflect complete repolarization of epicardium and midmyocardial region of the ventricular wall, respectively. Repolarization abnormalities in LQT1 carriers may therefore be more easily detected in the QT peak intervals. Methods Asymptomatic KCNQ1 mutation carriers (LQT1, n = 9) and unaffected healthy controls (n = 8) were studied during Valsalva manoeuvre, mental stress, handgrip and supine exercise. Global QT peak and QT end intervals derived from 25 simultaneous electrocardiographic leads were measured beat to beat with an automated method. Results In unaffected subjects, the percentage shortening of QT peak was greater than that of QT end during mental stress and during the recovery phases of Valsalva and supine exercise. In LQT1 carriers, the percentage shortening of the intervals was similar. At the beginning of Valsalva strain under abrupt endogenous sympathetic activation, QT peak shortened in LQT1 but not in control patients yielding increased electrocardiographic transmural dispersion of repolarization in LQT1. Conclusions In asymptomatic KCNQ1 mutation carriers, repolarization abnormalities are more evident in the QT peak than in the QT end interval during adrenergic adaptation, possibly related to transmural differences in the degree of IKs block. PMID:21138517

  18. Inaccurate electrocardiographic interpretation of long QT: the majority of physicians cannot recognize a long QT when they see one.

    PubMed

    Viskin, Sami; Rosovski, Uri; Sands, Andrew J; Chen, Edmond; Kistler, Peter M; Kalman, Jonathan M; Rodriguez Chavez, Laura; Iturralde Torres, Pedro; Cruz F, Fernando E S; Centurión, Osmar A; Fujiki, Akira; Maury, Philippe; Chen, Xiaomin; Krahn, Andrew D; Roithinger, Franz; Zhang, Li; Vincent, G Michael; Zeltser, David

    2005-06-01

    Physicians in all fields of medicine may encounter patients with long QT syndrome (LQTS). It is important to define the percentage of physicians capable of distinguishing QT intervals that are long from those that are normal because LQTS can be lethal when left untreated. The purpose of this study was to define the percentage of physicians in the different disciplines of medicine who can recognize a long QT when they see one. We presented the ECGs of two patients with LQTS and two healthy females to 902 physicians (25 world-renowned QT experts, 106 arrhythmia specialists, 329 cardiologists, and 442 noncardiologists) from 12 countries. They were asked to measure the QT, calculate the QTc (the QT interval corrected for the heart rate), and determine whether the QT is normal or prolonged. For patients with LQTS, >80% of arrhythmia experts but <50% of cardiologists and <40% of noncardiologists calculated the QTc correctly. Underestimation of the QTc of patients with LQTS and overestimation of the QTc of healthy patients were common. Interobserver agreement was excellent among QT experts, moderate among arrhythmia experts, and low among cardiologists and noncardiologists (kappa coefficient = 0.82, 0.44, and < 0.3, respectively). Correct classification of all QT intervals as either "long" or "normal" was achieved by 96% of QT experts and 62% of arrhythmia experts, but by only <25% of cardiologists and noncardiologists. Most physicians, including many cardiologists, cannot accurately calculate a QTc and cannot correctly identify a long QT.

  19. Spectrum and Prevalence of CALM1-, CALM2-, and CALM3-Encoded Calmodulin (CaM) Variants in Long QT Syndrome (LQTS) and Functional Characterization of a Novel LQTS-Associated CaM Missense Variant, E141G

    PubMed Central

    Calvert, Melissa L.; Tester, David J.; Kryshtal, Dmytro; Hwang, Hyun Seok; Johnson, Christopher N.; Chazin, Walter J.; Loporcaro, Christina G.; Shah, Maully; Papez, Andrew L.; Lau, Yung R.; Kanter, Ronald; Knollmann, Bjorn C.; Ackerman, Michael J.

    2016-01-01

    Background Calmodulin (CaM) is encoded by three genes, CALM1, CALM2, and CALM3, all of which harbor pathogenic variants linked to long QT syndrome (LQTS) with early and severe expressivity. These LQTS-causative variants reduce CaM affinity to Ca2+ and alter the properties of the cardiac L-type calcium channel (CaV1.2). CaM also modulates NaV1.5 and the ryanodine receptor, RyR2. All of these interactions may play a role in disease pathogenesis. Here, we determine the spectrum and prevalence of pathogenic CaM variants in a cohort of genetically elusive LQTS, and functionally characterize the novel variants. Methods and Results Thirty-nine genetically elusive LQTS cases underwent whole exome sequencing to identify CaM variants. Non-synonymous CaM variants were overrepresented significantly in this heretofore LQTS cohort (15.4%) compared to exome aggregation consortium (0.04%; p<0.0001). When the clinical sequelae of these 6 CaM-positive cases was compared to the 33 CaM-negative cases, CaM-positive cases had a more severe phenotype with an average age of onset of 8 months, an average QTc of 679 ms, and a high prevalence of cardiac arrest. Functional characterization of one novel variant, E141G-CaM, revealed an 11-fold reduction in Ca2+ binding affinity and a functionally-dominant loss of inactivation in CaV1.2, mild accentuation in NaV1.5 late current, but no effect on intracellular RyR2-mediated calcium release. Conclusions Overall, 15% of our genetically elusive LQTS cohort harbored non-synonymous variants in CaM. Genetic testing of CALM1-3 should be pursued for individuals with LQTS, especially those with early childhood cardiac arrest, extreme QT prolongation, and a negative family history. PMID:26969752

  20. Increased persistent sodium current due to decreased PI3K signaling contributes to QT prolongation in the diabetic heart.

    PubMed

    Lu, Zhongju; Jiang, Ya-Ping; Wu, Chia-Yen C; Ballou, Lisa M; Liu, Shengnan; Carpenter, Eileen S; Rosen, Michael R; Cohen, Ira S; Lin, Richard Z

    2013-12-01

    Diabetes is an independent risk factor for sudden cardiac death and ventricular arrhythmia complications of acute coronary syndrome. Prolongation of the QT interval on the electrocardiogram is also a risk factor for arrhythmias and sudden death, and the increased prevalence of QT prolongation is an independent risk factor for cardiovascular death in diabetic patients. The pathophysiological mechanisms responsible for this lethal complication are poorly understood. Diabetes is associated with a reduction in phosphoinositide 3-kinase (PI3K) signaling, which regulates the action potential duration (APD) of individual myocytes and thus the QT interval by altering multiple ion currents, including the persistent sodium current INaP. Here, we report a mechanism for diabetes-induced QT prolongation that involves an increase in INaP caused by defective PI3K signaling. Cardiac myocytes of mice with type 1 or type 2 diabetes exhibited an increase in APD that was reversed by expression of constitutively active PI3K or intracellular infusion of phosphatidylinositol 3,4,5-trisphosphate (PIP3), the second messenger produced by PI3K. The diabetic myocytes also showed an increase in INaP that was reversed by activated PI3K or PIP3. The increases in APD and INaP in myocytes translated into QT interval prolongation for both types of diabetic mice. The long QT interval of type 1 diabetic hearts was shortened by insulin treatment ex vivo, and this effect was blocked by a PI3K inhibitor. Treatment of both types of diabetic mouse hearts with an INaP blocker also shortened the QT interval. These results indicate that downregulation of cardiac PI3K signaling in diabetes prolongs the QT interval at least in part by causing an increase in INaP. This mechanism may explain why the diabetic population has an increased risk of life-threatening arrhythmias.

  1. Mild Beckwith-Wiedemann and severe long-QT syndrome due to deletion of the imprinting center 2 on chromosome 11p.

    PubMed

    Gurrieri, Fiorella; Zollino, Marcella; Oliva, Antonio; Pascali, Vincenzo; Orteschi, Daniela; Pietrobono, Roberta; Camporeale, Antonella; Coll Vidal, Monica; Partemi, Sara; Brugada, Ramon; Bellocci, Fulvio; Neri, Giovanni

    2013-09-01

    We report on a young woman admitted to our Cardiology Unit because of an episode of cardiac arrest related to a long-QT syndrome (LQTS). This manifestation was part of a broader phenotype, which was recognized as a mild form of Beckwith-Wiedemann syndrome (BWS). Molecular analysis confirmed the diagnosis of BWS owing to a maternally inherited deletion of the centromeric imprinting center, or ICR2, an extremely rare genetic mechanism in BWS. The deletion interval (198 kb) also included exons 11-16 of the KCNQ1 gene, known to be responsible for LQTS at locus LQT1. No concomitant mutations were found in any other of the known LQT genes. The proposita's mother carries the same deletion in her paternal chromosome and shows manifestations of the Silver-Russell syndrome (SRS). This report describes the smallest BWS-causing ICR2 deletion and provides the first evidence that a paternal deletion of ICR2 leads to a SRS-like phenotype. In addition, our observation strongly suggests that in cases of LQTS due to mutation of the KCNQ1 gene (LQT1), an accurate clinical genetic evaluation should be done in order to program the most appropriate genetic tests.

  2. Types of Myelodysplastic Syndromes

    MedlinePlus

    ... the bone marrow have at least one certain chromosome abnormality that is only seen in MDS or leukemia. The number of blasts in the bone marrow is less than 5%. Because this type ... this type of MDS, the chromosomes of the bone marrow cells are normal except ...

  3. Cellular basis for QT dispersion.

    PubMed

    Antzelevitch, C; Shimizu, W; Yan, G X; Sicouri, S

    1998-01-01

    The cellular basis for the dispersion of the QT interval recorded at the body surface is incompletely understood. Contributing to QT dispersion are heterogeneities of repolarization time in the three-dimensional structure of the ventricular myocardium, which are secondary to regional differences in action potential duration (APD) and activation time. While differences in APD occur along the apicobasal and anteroposterior axes in both epicardium and endocardium of many species, transitions are usually gradual. Recent studies have also demonstrated important APD gradients along the transmural axis. Because transmural heterogeneities in repolarization time are more abrupt than those recorded along the surfaces of the heart, they may represent a more onerous substrate for the development of arrhythmias, and their quantitation may provide a valuable tool for evaluation of arrhythmia risk. Our data, derived from the arterially perfused canine left ventricular wedge preparation, suggest that transmural gradients of voltage during repolarization contribute importantly to the inscription of the T wave. The start of the T wave is caused by a more rapid decline of the plateau, or phase 2 of the epicardial action potential, creating a voltage gradient across the wall. The gradient increases as the epicardial action potential continues to repolarize, reaching a maximum with full repolarization of epicardium; this juncture marks the peak of the T wave. The next region to repolarize is endocardium, giving rise to the initial descending limb of the upright T wave. The last region to repolarize is the M region, contributing to the final segment of the T wave. Full repolarization of the M region marks the end of the T wave. The time interval between the peak and the end of the T wave therefore represents the transmural dispersion of repolarization. Conditions known to augment QTc dispersion, including acquired long QT syndrome (class IA or III antiarrhythmics) lead to augmentation

  4. Measurement and interpretation of QT dispersion.

    PubMed

    Batchvarov, V; Malik, M

    2000-01-01

    QT dispersion was proposed as an index of the spatial inhomogeneity of ventricular recovery times. The results of studies that found significant correlation between dispersion of ventricular recovery times measured with monophasic action potentials and QT dispersion were interpreted as proof of the direct link between QT dispersion and the dispersion of ventricular recovery times. Later it was shown that QT dispersion is not a direct reflection of the spatial variation of the recovery times and cannot be used for quantification of this variation. The interlead variability of the QT intervals is a result of different projections of the spatial T-wave loop into the various electrocardiographic leads. The reliability of both manual and automatic measurement of QT dispersion is low and is often of the order of the differences of Qt dispersion between different patient groups. The measurement reliability is influenced by intrinsic factors (e.g., amplitude of the T wave) and extrinsic factors (e.g., noise, paper speed of recording, instruments for manual measurements, and type of algorithm and interalgorithmic settings for automatic measurement). There is very little to choose between the different indices of expression of QT dispersion, as well as between the different lead configurations used for its measurement. QT dispersion is not simply a result of measurement error, but a crude measure of abnormalities during the whole course of repolarization. Only grossly prolonged QT dispersion (e.g., > or =100 ms), must be interpreted simply as a sign of the abnormal course of the repolarization, and inferences about the actual dispersion of the ventricular recovery times should not be made. Newer concepts of assessment of the morphology of the T wave are already emerging and will probably be of higher clinical value.

  5. The human Nav1.5 F1486 deletion associated with long QT syndrome leads to impaired sodium channel inactivation and reduced lidocaine sensitivity

    PubMed Central

    Song, Weihua; Xiao, Yucheng; Chen, Hanying; Ashpole, Nicole M; Piekarz, Andrew D; Ma, Peilin; Hudmon, Andy; Cummins, Theodore R; Shou, Weinian

    2012-01-01

    The deletion of phenylalanine 1486 (F1486del) in the human cardiac voltage-gated sodium channel (hNav1.5) is associated with fatal long QT (LQT) syndrome. In this study we determined how F1486del impairs the functional properties of hNav1.5 and alters action potential firing in heterologous expression systems (human embryonic kidney (HEK) 293 cells) and their native cardiomyocyte background. Cells expressing hNav1.5-F1486del exhibited a loss-of-function alteration, reflected by an 80% reduction of peak current density, and several gain-of-function alterations, including reduced channel inactivation, enlarged window current, substantial augmentation of persistent late sodium current and an increase in ramp current. We also observed substantial action potential duration (APD) prolongation and prominent early afterdepolarizations (EADs) in neonatal cardiomyocytes expressing the F1486del channels, as well as in computer simulations of myocyte activity. In addition, lidocaine sensitivity was dramatically reduced, which probably contributed to the poor therapeutic outcome observed in the patient carrying the hNav1.5-F1486del mutation. Therefore, despite the significant reduction in peak current density, the F1486del mutation also leads to substantial gain-of-function alterations that are sufficient to cause APD prolongation and EADs, the predominant characteristic of LQTs. These data demonstrate that hNav1.5 mutations can have complex functional consequences and highlight the importance of identifying the specific molecular defect when evaluating potential treatments for individuals with prolonged QT intervals. PMID:22826127

  6. Prevalence and Risk Factors of Drug-Associated Corrected QT Prolongation in Elderly Hospitalized Patients: Results of a Retrospective Analysis of Data Obtained Over 6 Months.

    PubMed

    Maison, Ophélie; de la Gastine, Blandine; Dayot, Laurent; Goutelle, Sylvain

    2017-07-01

    Little information exists on the frequency and determinants of drug-associated long QT syndrome in older adults. The objectives of this study were to assess the prevalence and identify risk factors of drug-associated long QT syndrome in a population of elderly hospitalized patients. This was a retrospective study performed over 6 months in hospital geriatric medicine. Various QT-correction equations were fitted to the individual QT-RR data to evaluate the most appropriate equation. Long QT syndrome was defined as corrected QT ≥450 ms. Available data were compared in patients with and without long QT syndrome. Logistic regression and classification and regression tree analysis were performed to identify determinants of long QT syndrome. Thirty-three of 152 patients (22%) exhibited corrected QT ≥450 ms. The different QT correction equations provided similar results, except the Bazett equation. In patients with long QT syndrome, there was a higher proportion of male subjects (58 vs. 33%, p = 0.009) and a higher number of QT-prolonging drugs than in patients without long QT syndrome. Male sex (odds ratio, 3.25) and the number of prescribed QT-prolonging agents (odds ratio, 1.77) were significantly associated with the probability of long QT syndrome. The number of QT-prolonging drugs had a stronger influence on the risk of long QT syndrome in men than in women. Male sex was found to be a significant risk factor of corrected QT prolongation in elderly hospitalized patients. The risk also increased with the number of QT-prolonging agents, especially in men. Those findings may help to mitigate the risk of long QT syndrome in elderly patients in clinical practice.

  7. The Evaluation of a Borderline Long QT Interval in an Asymptomatic Patient.

    PubMed

    Obeyesekere, Manoj N; Leong-Sit, Peter; Gula, Lorne J; Yee, Raymond; Skanes, Allan C; Klein, George J; Krahn, Andrew D

    2012-06-01

    QT prolongation on resting electrocardiography (ECG) is common, and the clinician is often challenged by the dilemma of excluding acquired causes and recognizing potential congenital long QT syndrome (LQTS). The hallmark of LQTS is an abnormally long QT interval. However, a normal or borderline long QT interval may be observed in up to 50% of patients with LQTS because of the intermittent nature of QT prolongation. This review presents an approach to evaluating the asymptomatic patient with a borderline long QT interval, which incorporates a comprehensive clinical assessment, rest and provocative ECG testing, and genetic testing when appropriate.

  8. Providers' Response to Clinical Decision Support for QT Prolonging Drugs.

    PubMed

    Sharma, Sunita; Martijn Bos, J; Tarrell, Robert F; Simon, Gyorgy J; Morlan, Bruce W; Ackerman, Michael J; Caraballo, Pedro J

    2017-09-02

    Commonly used drugs in hospital setting can cause QT prolongation and trigger life-threatening arrhythmias. We evaluate changes in prescribing behavior after the implementation of a clinical decision support system to prevent the use of QT prolonging medications in the hospital setting. We conducted a quasi-experimental study, before and after the implementation of a clinical decision support system integrated in the electronic medical record (QT-alert system). This system detects patients at risk of significant QT prolongation (QTc>500ms) and alerts providers ordering QT prolonging drugs. We reviewed the electronic health record to assess the provider's responses which were classified as "action taken" (QT drug avoided, QT drug changed, other QT drug(s) avoided, ECG monitoring, electrolytes monitoring, QT issue acknowledged, other actions) or "no action taken". Approximately, 15.5% (95/612) of the alerts were followed by a provider's action in the pre-intervention phase compared with 21% (228/1085) in the post-intervention phase (p=0.006). The most common type of actions taken during pre-intervention phase compared to post-intervention phase were ECG monitoring (8% vs. 13%, p=0.002) and QT issue acknowledgment (2.1% vs. 4.1%, p=0.03). Notably, there was no significant difference for other actions including QT drug avoided (p=0.8), QT drug changed (p=0.06) and other QT drug(s) avoided (p=0.3). Our study demonstrated that the QT alert system prompted a higher proportion of providers to take action on patients at risk of complications. However, the overall impact was modest underscoring the need for educating providers and optimizing clinical decision support to further reduce drug-induced QT prolongation.

  9. Electrocardiogram in Andersen-Tawil syndrome. New electrocardiographic criteria for diagnosis of type-1 Andersen-Tawil syndrome.

    PubMed

    Kukla, Piotr; Biernacka, Elzbieta K; Baranchuk, Adrian; Jastrzebski, Marek; Jagodzinska, Michalina

    2014-08-01

    Andersen - Tawil syndrome (ATS) is an autosomal - dominant or sporadic disorder characterized by ventricular arrhythmias, periodic paralysis, and distinctive facial and skeletal dysmorphism. Mutations in KCNJ2, which encodes the α-subunit of the potassium channel Kir2.1, were identified in patients with ATS. This genotype has been designated as type-1 ATS (ATS1). KCNJ2 mutations are detectable in up to 60 % of patients with ATS. Cardiac manifestations of ATS include frequent premature ventricular contractions (PVC), Q-U interval prolongation, prominent U-waves, and a special type of polymorphic ventricular tachycardia (PMVT) called bidirectional ventricular tachycardia (BiVT). The presence of frequent PVCs at rest are helpful in distinguishing ATS from typical catecholaminergic polymorphic ventricular tachycardia (CPVT). In typical CPVT, rapid PMVT and BiVT usually manifest during or after exercising. Additionally, CPVT or torsade de pointes in LQTS are faster, very symptomatic causing syncope or often deteriorate into VF resulting in sudden cardiac death. PVCs at rest are quite frequent in ATS1 patients, however, in LQTS patients, PVCs and asymptomatic VT are uncommon which also contributes to differentiating them. The article describes the new electrocardiographic criteria proposed for diagnosis of type-1 Andersen-Tawil syndrome. A differential diagnosis between Andersen-Tawil syndrome, the catecholamine polymorphic ventiruclar tachycardia and long QT syndrome is depicted. Special attention is paid on the repolarization abnormalities, QT interval and the pathologic U wave. In this article, we aim to provide five new electrocardiographic clues for the diagnosis of ATS1.

  10. Electrocardiogram in Andersen-Tawil Syndrome. New Electrocardiographic Criteria for Diagnosis of Type-1 Andersen-Tawil Syndrome

    PubMed Central

    Kukla, Piotr; Biernacka, Elżbieta K; Baranchuk, Adrian; Jastrzębski, Marek; Jagodzińska, Michalina

    2014-01-01

    Andersen - Tawil syndrome (ATS) is an autosomal - dominant or sporadic disorder characterized by ventricular arrhythmias, periodic paralysis, and distinctive facial and skeletal dysmorphism. Mutations in KCNJ2, which encodes the α-subunit of the potassium channel Kir2.1, were identified in patients with ATS. This genotype has been designated as type-1 ATS (ATS1). KCNJ2 mutations are detectable in up to 60 % of patients with ATS. Cardiac manifestations of ATS include frequent premature ventricular contractions (PVC), Q-U interval prolongation, prominent U-waves, and a special type of polymorphic ventricular tachycardia (PMVT) called bidirectional ventricular tachycardia (BiVT). The presence of frequent PVCs at rest are helpful in distinguishing ATS from typical catecholaminergic polymorphic ventricular tachycardia (CPVT). In typical CPVT, rapid PMVT and BiVT usually manifest during or after exercising. Additionally, CPVT or torsade de pointes in LQTS are faster, very symptomatic causing syncope or often deteriorate into VF resulting in sudden cardiac death. PVCs at rest are quite frequent in ATS1 patients, however, in LQTS patients, PVCs and asymptomatic VT are uncommon which also contributes to differentiating them. The article describes the new electrocardiographic criteria proposed for diagnosis of type-1 Andersen-Tawil syndrome. A differential diagnosis between Andersen-Tawil syndrome, the catecholamine polymorphic ventiruclar tachycardia and long QT syndrome is depicted. Special attention is paid on the repolarization abnormalities, QT interval and the pathologic U wave. In this article, we aim to provide five new electrocardiographic clues for the diagnosis of ATS1. PMID:24827800

  11. Patients With Long-QT Syndrome Caused by Impaired hERG-Encoded Kv11.1 Potassium Channel Have Exaggerated Endocrine Pancreatic and Incretin Function Associated With Reactive Hypoglycemia.

    PubMed

    Hyltén-Cavallius, Louise; Iepsen, Eva W; Wewer Albrechtsen, Nicolai J; Svendstrup, Mathilde; Lubberding, Anniek F; Hartmann, Bolette; Jespersen, Thomas; Linneberg, Allan; Christiansen, Michael; Vestergaard, Henrik; Pedersen, Oluf; Holst, Jens J; Kanters, Jørgen K; Hansen, Torben; Torekov, Signe S

    2017-05-02

    Loss-of-function mutations in hERG (encoding the Kv11.1 voltage-gated potassium channel) cause long-QT syndrome type 2 (LQT2) because of prolonged cardiac repolarization. However, Kv11.1 is also present in pancreatic α and β cells and intestinal L and K cells, secreting glucagon, insulin, and the incretins glucagon-like peptide-1 (GLP-1) and GIP (glucose-dependent insulinotropic polypeptide), respectively. These hormones are crucial for glucose regulation, and long-QT syndrome may cause disturbed glucose regulation. We measured secretion of these hormones and cardiac repolarization in response to glucose ingestion in LQT2 patients with functional mutations in hERG and matched healthy participants, testing the hypothesis that LQT2 patients have increased incretin and β-cell function and decreased α-cell function, and thus lower glucose levels. Eleven patients with LQT2 and 22 sex-, age-, and body mass index-matched control participants underwent a 6-hour 75-g oral glucose tolerance test with ECG recording and blood sampling for measurements of glucose, insulin, C-peptide, glucagon, GLP-1, and GIP. In comparison with matched control participants, LQT2 patients had 56% to 78% increased serum insulin, serum C-peptide, plasma GLP-1, and plasma GIP responses (P=0.03-0.001) and decreased plasma glucose levels after glucose ingestion (P=0.02) with more symptoms of hypoglycemia (P=0.04). Sixty-three percent of LQT2 patients developed hypoglycemic plasma glucose levels (<70 mg/dL) versus 36% control participants (P=0.16), and 18% patients developed serious hypoglycemia (<50 mg/dL) versus none of the controls. LQT2 patients had defective glucagon responses to low glucose, P=0.008. β-Cell function (Insulin Secretion Sensitivity Index-2) was 2-fold higher in LQT2 patients than in controls (4398 [95% confidence interval, 2259-8562] versus 2156 [1961-3201], P=0.03). Pharmacological Kv11.1 blockade (dofetilide) in rats had similar effect, and small interfering RNA inhibition

  12. QT Prolongation and Clinical Outcomes in Patients with Takotsubo Cardiomyopathy.

    PubMed

    Imran, Tasnim F; Rahman, Ifad; Dikdan, Sean; Shah, Rashesh; Niazi, Osama T; Thirunahari, Nandan; Alhaj, Eyad; Klapholz, Marc; Gaziano, J Michael; Djousse, Luc

    2016-06-01

    Takotsubo cardiomyopathy (TCM) has been associated with repolarization abnormalities including QT prolongation and acquired long QT syndrome. However, the association between QT prolongation and clinical outcomes in patients with TCM remains unclear. The aim of this study is to examine the association between QT prolongation and ventricular arrhythmias, cardiogenic shock, and death in patients with TCM. Forty-six patients with TCM met our inclusion criteria in an ongoing prospective cohort database from 2010 to May 2015. We assigned the patients to a long QT group or a normal QT group, and created a composite outcome consisting of ventricular arrhythmias, cardiogenic shock, or death. The mean age of the participants was 59.7 ± 16 years, 67% were women, and 63% had hypertension. Median follow-up time was 3.1 years (interquartile range: 2.0-3.8), with a total of 133.8 person-years. The mean left ventricular ejection fraction at diagnosis was 27.2% ± 1.4%. The mean QTc on diagnosis was 484 ms ± 10.2 ms for men, and 488 ms ± 8.6 ms for women. The long QT group had a 4.1-times higher odds of having the composite clinical outcome as compared to the normal QT group (95% confidence interval: 1.1, 16.1, P = 0.04) after adjusting for age and race in logistic regression. Patients with TCM who have a long QT interval or develop acquired long QT syndrome due to TCM may be more likely to be intubated; require vasopressors; and develop shock, ventricular arrhythmias, and death than those with a normal QT interval. ©2016 Wiley Periodicals, Inc.

  13. Phase-contrast magnet resonance imaging reveals regional, transmural, and base-to-apex dispersion of mechanical dysfunction in patients with long QT syndrome.

    PubMed

    Brado, Johannes; Dechant, Markus J; Menza, Marius; Komancsek, Adriana; Lang, Corinna N; Bugger, Heiko; Foell, Daniela; Jung, Bernd A; Stiller, Brigitte; Bode, Christoph; Odening, Katja E

    2017-09-01

    Regional dispersion of prolonged repolarization is a hallmark of long QT syndrome (LQTS). We have also revealed regional heterogeneities in mechanical dysfunction in transgenic rabbit models of LQTS. In this clinical pilot study, we investigated whether patients with LQTS exhibit dispersion of mechanical/diastolic dysfunction. Nine pediatric patients with genotyped LQTS (12.2 ± 3.3 years) and 9 age- and sex-matched healthy controls (10.6 ± 1.5 years) were subjected to phase-contrast magnetic resonance imaging to analyze radial (Vr) and longitudinal (Vz) myocardial velocities during systole and diastole in the left ventricle (LV) base, mid, and apex. Twelve-lead electrocardiograms were recorded to assess the heart rate-corrected QT (QTc) interval. The QTc interval was longer in patients with LQTS than in controls (469.1 ± 39.4 ms vs 417.8 ± 24.4 ms; P < .01). Patients with LQTS demonstrated prolonged radial and longitudinal time-to-diastolic peak velocities (TTP), a marker for prolonged contraction duration, in the LV base, mid, and apex. The longer QTc interval positively correlated with longer time-to-diastolic peak velocities (correlation coefficient 0.63; P < .01). Peak diastolic velocities were reduced in LQTS in the LV mid and apex, indicating impaired diastolic relaxation. In patients with LQTS, regional (TTPmax-min) and transmural (TTPVz-Vr) dispersion of contraction duration was increased in the LV apex (TTPVz_max-min: 38.9 ± 25.5 ms vs 20.2 ± 14.7 ms; P = .07; TTPVz-Vr: -21.7 ± 14.5 ms vs -8.7 ± 11.3 ms; P < .05). The base-to-apex longitudinal relaxation sequence was reversed in patients with LQTS compared with controls (TTPVz_base-apex: 14.4 ± 14.9 ms vs -10.1 ± 12.7 ms; P < .01). Patients with LQTS exhibit diastolic dysfunction with reduced diastolic velocities and prolonged contraction duration. Mechanical dispersion is increased in LQTS with an increased regional and transmural dispersion of contraction duration and altered apicobasal

  14. Antimicrobials and QT prolongation.

    PubMed

    Mason, Jay W

    2017-05-01

    Solithromycin, a ketolide/macrolide antibiotic, has recently been reported to be free of the expected QT-prolonging effect of macrolides. It appears that its keto substitution provides a structural basis for this observation, as the other two tested ketolides also have minimal QT effect.Among non-cardiovascular therapies, antimicrobials probably carry the greatest potential to cause cardiac arrhythmias. This is a result of their propensity to bind to the delayed rectifier potassium channel, IKr, inducing QT prolongation and risk of torsades de pointes ventricular tachycardia, their frequent interference with the metabolism of other QT prolongers and their susceptibility to metabolic inhibition by numerous commonly used drugs.Unfortunately, there is evidence that medical practitioners do not take account of the QT/arrhythmia risk of antimicrobials in their prescribing practices. Education on this topic is sorely needed. When a macrolide is indicated, a ketolide should be considered in patients with a QT risk. © The Author 2017. Published by Oxford University Press on behalf of the British Society for Antimicrobial Chemotherapy. All rights reserved. For Permissions, please email: journals.permissions@oup.com.

  15. A KCNQ1 mutation contributes to the concealed type 1 long QT phenotype by limiting the Kv7.1 channel conformational changes associated with protein kinase A phosphorylation.

    PubMed

    Bartos, Daniel C; Giudicessi, John R; Tester, David J; Ackerman, Michael J; Ohno, Seiko; Horie, Minoru; Gollob, Michael H; Burgess, Don E; Delisle, Brian P

    2014-03-01

    Type 1 long QT syndrome (LQT1) is caused by loss-of-function mutations in the KCNQ1-encoded Kv7.1 channel that conducts the slowly activating component of the delayed rectifier K(+) current (IKs). Clinically, the diagnosis of LQT1 is complicated by variable phenotypic expressivity, whereby approximately 25% of genotype-positive individuals present with concealed LQT1 (resting corrected QT [QTc] interval ≤460 ms). To determine whether a specific molecular mechanism contributes to concealed LQT1. We identified a multigenerational LQT1 family whereby 79% of the patients genotype-positive for p.Ile235Asn-KCNQ1 (I235N-Kv7.1) have concealed LQT1. We assessed the effect I235N-Kv7.1 has on IKs and the ventricular action potential (AP) by using in vitro analysis and computational simulations. Clinical data showed that all 10 patients with I235N-Kv7.1 have normal resting QTc intervals but abnormal QTc interval prolongation during the recovery phase of an electrocardiographic treadmill stress test. Voltage-clamping HEK293 cells coexpressing wild-type Kv7.1 and I235N-Kv7.1 (to mimic the patients' genotypes) showed that I235N-Kv7.1 generated relatively normal functioning Kv7.1 channels but were insensitive to protein kinase A (PKA) activation. Phosphomimetic and quinidine sensitivity studies suggest that I235N-Kv7.1 limits the conformational changes in Kv7.1 channels, which are necessary to upregulate IKs after PKA phosphorylation. Computational ventricular AP simulations predicted that the PKA insensitivity of I235N-Kv7.1 is primarily responsible for prolonging the AP with β-adrenergic stimulation, especially at slower cycle lengths. KCNQ1 mutations that generate relatively normal Kv7.1 channels, but limit the upregulation of IKs by PKA activation, likely contribute to concealed LQT1. Copyright © 2014 Heart Rhythm Society. Published by Elsevier Inc. All rights reserved.

  16. Compound Mutations Cause Increased Cardiac Events in Children with Long QT Syndrome: Can the Sequence Homology-Based Tools be Applied for Prediction of Phenotypic Severity?

    PubMed

    Izumi, Gaku; Hayama, Emiko; Yamazawa, Hirokuni; Inai, Kei; Shimada, Mitsuyo; Furutani, Michiko; Nishizawa, Tsutomu; Furutani, Yoshiyuki; Matsuoka, Rumiko; Nakanishi, Toshio

    2016-06-01

    Long QT syndrome (LQTS) can cause syncope, ventricular fibrillation, and death. Recently, several disease-causing mutations in ion channel genes have been identified, and compound mutations have also been detected. It is unclear whether children who are carriers of compound mutations exhibit a more severe phenotype than those with single mutations. Although predicting phenotypic severity is clinically important, the availability of prediction tools for LQTS is unknown. To determine whether the severity of the LQTS phenotype can be predicted by the presence of compound mutations in children is needed. We detected 97 single mutations (Group S) and 13 compound mutations (Group C) between 1998 and 2012, age at diagnosis ranging 0-19 years old (median age is 9.0) and 18.0 years of follow-up period. The phenotypes and Kaplan-Meier event-free rates of the two groups were compared for cardiac events. This study investigated phenotypic severity in relation to the location of mutations in the protein sequence, which was analyzed using two sequence homology-based tools. In results, compound mutations in children were associated with a high incidence of syncope within the first decade (Group S: 32 % vs. Group C: 61 %), requiring an ICD in the second decade (Group S: 3 % vs. Group C: 56 %). Mortality in these patients was high within 5 years of birth (23 %). Phenotypic prediction tools correctly predicted the phenotypic severity in both Groups S and C, especially by using their coupling method. The coupling prediction method is useful in the initial evaluation of phenotypes both with single and compound mutations of LQTS patients. However, it should be noted that the compound mutation makes more severe phenotype.

  17. Spectrum and prevalence of mutations from the first 2,500 consecutive unrelated patients referred for the FAMILION® long QT syndrome genetic test

    PubMed Central

    Kapplinger, Jamie D.; Tester, David J.; Salisbury, Benjamin A.; Carr, Janet L.; Harris-Kerr, Carole; Pollevick, PhD, Guido D.; Wilde, Arthur A. M.; Ackerman, Michael J.

    2011-01-01

    BACKGROUND Long QT syndrome (LQTS) is a potentially lethal, highly treatable cardiac channelopathy for which genetic testing has matured from discovery to translation and now clinical implementation. OBJECTIVES Here we examine the spectrum and prevalence of mutations found in the first 2,500 unrelated cases referred for the FAMILION® LQTS clinical genetic test. METHODS Retrospective analysis of the first 2,500 cases (1,515 female patients, average age at testing 23 ± 17 years, range 0 to 90 years) scanned for mutations in 5 of the LQTS-susceptibility genes: KCNQ1 (LQT1), KCNH2 (LQT2), SCN5A (LQT3), KCNE1 (LQT5), and KCNE2 (LQT6). RESULTS Overall, 903 referral cases (36%) hosted a possible LQTS-causing mutation that was absent in >2,600 reference alleles; 821 (91%) of the mutation-positive cases had single genotypes, whereas the remaining 82 patients (9%) had >1 mutation in ≥1 gene, including 52 cases that were compound heterozygous with mutations in >1 gene. Of the 562 distinct mutations, 394 (70%) were missense, 428 (76%) were seen once, and 336 (60%) are novel, including 92 of 199 in KCNQ1, 159 of 226 in KCNH2, and 70 of 110 in SCN5A. CONCLUSION This cohort increases the publicly available compendium of putative LQTS-associated mutations by >50%, and approximately one-third of the most recently detected mutations continue to be novel. Although control population data suggest that the great majority of these mutations are pathogenic, expert interpretation of genetic test results will remain critical for effective clinical use of LQTS genetic test results. PMID:19716085

  18. A Systematic Review on the Cost-Effectiveness of Genetic and Electrocardiogram Testing for Long QT Syndrome in Infants and Young Adults.

    PubMed

    Gonzalez, Fernando Matias; Veneziano, Maria Assunta; Puggina, Anna; Boccia, Stefania

    2015-07-01

    Recent improvements in the identification of the genetic basis of long QT syndrome (LQTS) have led to significant changes in the diagnosis and management of this life-threatening condition. Genetic and electrocardiogram (ECG) tests are the most relevant examples among testing strategies for LQTS, yet their cost-effectiveness remains controversial. The aim of this work was to review the available evidence on the cost-effectiveness of genetic and ECG testing strategies for the diagnosis of LQTS. We performed a systematic review of the literature on the cost-effectiveness of genetic and ECG screening strategies for the early detection of LQTS using MEDLINE, EMBASE, and CRD databases between 2000 and 2013. A weighted version of Drummond checklist was instrumental in further assessing the quality of the included studies. We identified four eligible articles. Among them, genetic testing in the early detection of LQTS was cost-effective compared with no testing in symptomatic cases and not cost-effective when compared with watchful waiting in asymptomatic first-degree relatives of patients with established LQTS although it reached cost-effectiveness in higher risk subgroups, whereas ECG testing in neonates was highly cost-effective when compared with any screening strategy. LQTS profiling and patients' stratification have the potential to improve the disease management. Because of the limited current knowledge in this field, the present review recommends to perform further cost-effectiveness evaluations of the genetic and ECG screening alternatives, especially within European health care systems, which are still not available in the literature on genetic testing. Copyright © 2015 International Society for Pharmacoeconomics and Outcomes Research (ISPOR). Published by Elsevier Inc. All rights reserved.

  19. Assessment of ventricular repolarization variability with the DeltaT50 method improves identification of patients with congenital long QT syndromes.

    PubMed

    Abrahamsson, Christina; Dota, Corina; Skallefell, Bo; Carlsson, Leif; Frison, Lars; Berggren, Anders; Edvardsson, Nils; Duker, Göran

    2013-05-01

    We analyzed ventricular repolarization variability in genotyped long QT syndrome (LQTS) patients and in healthy volunteers (HV). The deltaT50, that is, the temporal variability of ventricular repolarization at 50% of the T-wave downslope, was analyzed every 15th minute on 175 and 390 Holter electrocardiogram (ECG) recordings from HV and genotyped LQTS patients, respectively. The average deltaT50 and QTcF were calculated in each subject. DeltaT50 was 2.26 ± 0.71 ms (mean ± SD) in the HV and 5.74 ± 2.30 ms in the LQTS population (P < 0.0001). The sensitivity and specificity of QTcF (cutoff value 450 ms) to discriminate between the LQTS patients and the HV were 51.5% and 98.9%, and for deltaT50 (cutoff value 3 ms) 93.9% and 88.6%, respectively. The combination of both variables improved the diagnosis of the LQTS patients even further. Subgroups of LQTS patients at higher risk of cardiac events (with LQTS3, JLN, QTc > 500 ms or symptoms) had higher deltaT50 than subgroups at lower risk (with LQTS1, QTc < 450 ms or without symptoms). The variation in deltaT50 between day and night was concordant with the risk of symptoms; patients with LQTS1 had higher deltaT50 in the daytime and patients with LQTS3 had higher deltaT50 during the night. DeltaT50 more accurately distinguished between LQTS patients and HV than QTcF and was higher in LQTS patients with a higher risk of cardiac events. DeltaT50 can be used together with QTcF to improve the diagnosis in patients with the LQTS phenotype and tentatively also be of value for risk assessment in such patients. ©2012, Wiley Periodicals, Inc.

  20. Post-mortem pathologic and genetic studies in "dead in bed syndrome" cases in type 1 diabetes mellitus.

    PubMed

    Tu, Emily; Bagnall, Richard D; Duflou, Johan; Lynch, Matthew; Twigg, Stephen M; Semsarian, Christopher

    2010-03-01

    Dead in bed syndrome is a poorly understood cause of sudden death in young people with type 1 diabetes. The underlying cause remains unknown. One possible explanation may involve prolongation of the QT interval followed by a terminal malignant arrhythmia. Risk factors associated with QT interval prolongation include hypoglycemia and cardiac autonomic neuropathy. We sought to identify myocardial cellular changes and genetic influences that may contribute to the pathogenesis of dead in bed syndrome. Post-mortem reports between 1994 and 2006 from the 2 largest Departments of Forensic Medicine in Australia were reviewed for dead in bed syndrome cases. Post-mortem heart sections were immunohistochemically stained for collagen types I and III and connective tissue growth factor (CTGF). Genomic DNA was prepared from post-mortem samples, and genetic analysis was performed in the SCN5A, G6PC, PHOX2B, and CTGF genes. Twenty-two dead in bed syndrome cases were identified and staining of heart sections for collagen I and III, and CTGF showed no differences between dead in bed syndrome cases and controls. Genetic screening of SCN5A revealed 3 silent polymorphisms A29A, E1061E, and D1819D and 1 protein-changing variant H558R. No genetic variants were found in G6PC, PHOX2B, and CTGF, and dead in bed syndrome cases were not associated with the G-945C CTGF promoter polymorphism. In conclusion, this study is the first to investigate potential pathogenic mechanisms underlying the dead in bed syndrome in type 1 diabetes with the results substantially adding to knowledge of this condition. Understanding the causes and triggers of dead in bed syndrome will be critical in facilitating the identification of patients with type 1 diabetes at highest risk of developing sudden death. Copyright 2010 Elsevier Inc. All rights reserved.

  1. ADPKD: Prototype of Cardiorenal Syndrome Type 4

    PubMed Central

    Virzì, Grazia Maria; Corradi, Valentina; Panagiotou, Anthi; Gastaldon, Fiorella; Cruz, Dinna N.; de Cal, Massimo; Clementi, Maurizio; Ronco, Claudio

    2011-01-01

    The cardiorenal syndrome type 4 (Chronic Renocardiac Syndrome) is characterized by a condition of primary chronic kidney disease (CKD) that leads to an impairment of the cardiac function, ventricular hypertrophy, diastolic dysfunction, and/or increased risk of adverse cardiovascular events. Clinically, it is very difficult to distinguish between CRS type 2 (Chronic Cardiorenal Syndrome) and CRS type 4 (Chronic Renocardiac Syndrome) because often it is not clear whether the primary cause of the syndrome depends on the heart or the kidney. Autosomal dominant polycystic kidney disease (ADPKD), a genetic disease that causes CKD, could be viewed as an ideal prototype of CRS type 4 because it is certain that the primary cause of cardiorenal syndrome is the kidney disease. In this paper, we will briefly review the epidemiology of ADPKD, conventional and novel biomarkers which may be useful in following the disease process, and prevention and treatment strategies. PMID:21234092

  2. Neurofibromatosis type II: a rare neurocutaneous syndrome.

    PubMed

    Sultan, Tipu; Khan, Ashfa Ameer; Malik, Muhammad Akbar; Nadeem, Malik Muhammad; Rahman, Mahfooz-Ur-; Khan, Malik Muhammad Nazir

    2007-06-01

    Neurocutaneous syndromes are heterogeneous group of disorders with abnormalities of central as well as peripheral nervous system. Neurofibromatosis type II (NF-II) is an autosomal dominant neurocutaneous syndrome rarely diagnosed in pediatric population. Diagnosis is based on clinical history and radioimaging. We present a 14 years old boy with headache and decreased hearing, who turned to be a case of neurofibromatosis type II.

  3. Comprehensive Open Reading Frame Mutational Analysis of the RYR2-Encoded Ryanodine Receptor/Calcium Channel in Patients Diagnosed Previously with Either Catecholaminergic Polymorphic Ventricular Tachycardia or Genotype Negative, Exercise-Induced Long QT Syndrome

    PubMed Central

    Medeiros-Domingo, Argelia; Bhuiyan, Zahurul A.; Tester, David J.; Hofman, Nynke; Bikker, Hennie; van Tintelen, J Peter; Mannens, Marcel M.A.M; Wilde, Arthur A.M.; Ackerman, Michael J.

    2010-01-01

    Objective To determine the spectrum and prevalence of mutations in the RYR2-encoded the cardiac ryanodine receptor in cases with exertional syncope and normal QTc. Background Mutations in the RYR2 cause type 1 catecholaminergic polymorphic ventricular tachycardia (CPVT1), a cardiac channelopathy with increased propensity for lethal ventricular dysrhythmias. Most RYR2 mutational analyses target 3 canonical domains encoded by < 40% of the translated exons. The extent of CPVT1-associated mutations localizing outside of these domains remains unknown as RYR2 has not been examined comprehensively in most patient cohorts. Methods Mutational analysis of all RYR2 exons was performed using PCR, DHPLC, and DNA sequencing on 155 unrelated patients (49% females, 96% white, age at diagnosis 20 ± 15 years, mean QTc 428 ± 29 ms), with either clinical diagnosis of CPVT (n = 110) or an initial diagnosis of exercise-induced long QT syndrome (LQTS) but with QTc < 480 ms and a subsequent negative LQTS genetic test (n = 45). Results Sixty-three (34 novel) possible CPVT1-associated mutations, absent in 400 reference alleles, were detected in 73 unrelated patients (47%). Thirteen new mutation-containing exons were identified. Two thirds of the CPVT1-positive patients had mutations that localized to one of 16 exons. Conclusions Possible CPVT1 mutations in RYR2 were identified in nearly half of this cohort. 45 of the 105 translated exons are now known to host possible mutations. Considering that ~65% of CPVT1-positive cases would be discovered by selective analysis of 16 exons, a tiered targeting strategy for CPVT genetic testing should be considered. PMID:19926015

  4. Ionic, molecular, and cellular bases of QT-interval prolongation and torsade de pointes

    PubMed Central

    Antzelevitch, Charles

    2008-01-01

    Torsade de pointes (TdP) is a life-threatening arrhythmia that develops as a consequence of a reduction in the repolarization reserve of cardiac cells leading to amplification of electrical heterogeneities in the ventricular myocardium as well as to the development of early after depolarization-induced triggered activity. Electrical heterogeneities within the ventricles are due to differences in the time course of repolarization of the three predominant cell types that make up the ventricular myocardium, giving rise to transmural voltage gradients and a dispersion of repolarization that contributes to the inscription of the electrocardiographic T wave. A number of non-antiarrhythmic drugs and antiarrhythmic agents with class III actions and/or the various mutations and cardiomyopathies associated with the long QT syndrome reduce net repolarizing current and amplify spatial dispersion of repolarization, thus creating the substrate for re-entry. This results in a prolongation of the QT interval, abnormal T waves, and development of TdP. Agents that prolong the QT interval but do not cause an increase in transmural dispersion of repolarization (TDR) do not induce TdP, suggesting that QT prolongation is not the sole or optimal determinant for arrhythmogenesis. This article reviews recent advances in our understanding of these mechanisms, particularly the role of TDR in the genesis of drug-induced TdP, and examines how these may guide us towards development of safer drugs. PMID:17766323

  5. A mouse model to study the link between hypoxia, long QT interval and sudden infant death syndrome.

    PubMed

    Neary, Marianne T; Mohun, Timothy J; Breckenridge, Ross A

    2013-03-01

    The pathology of sudden infant death syndrome (SIDS) is poorly understood. Many risk factors, including hypoxia, have been identified. Prolongation of the ECG QTc interval is associated with elevated risk of SIDS but its aetiology in most cases remains unknown. We have characterised ECG changes in the newborn mouse in the hours and days following birth. There was a steady increase in heart rate alongside significant decreases in QTc interval, QRS duration and QTc dispersion over the first 10 postnatal days. Birth into hypoxia (10% FiO2) prevented electrocardiac maturation, downregulated cardiac ion-channel expression and led to neonatal death. We found that risk of death decreased with increasing age of exposure to hypoxia. Genetic elevation of cardiac hypoxia-signalling after birth in αMHC-Cre::VHL(fl/fl) mice also prevented electrocardiographic maturation, leading to arrhythmia and death before weaning. Immunohistochemistry and western blotting revealed internalisation and dephosphorylation of Connexin43. We conclude that increased ambient oxygen concentration after birth drives maturation of the cardiac electrical conduction system, failure of which leads to aberrant ion channel and Connexin43 expression and predisposes to arrhythmia and sudden death. This is consistent with known risk factors of SIDS and provides a link between neonatal hypoxia, ECG abnormalities and sudden death.

  6. Genetics Home Reference: type A insulin resistance syndrome

    MedlinePlus

    ... Conditions type A insulin resistance syndrome type A insulin resistance syndrome Enable Javascript to view the expand/ ... PDF Open All Close All Description Type A insulin resistance syndrome is a rare disorder characterized by ...

  7. Drug-induced QT-interval shortening following antiepileptic treatment with oral rufinamide

    PubMed Central

    Schimpf, Rainer; Veltmann, Christian; Papavassiliu, Theano; Rudic, Boris; Göksu, Turgay; Kuschyk, Jürgen; Wolpert, Christian; Antzelevitch, Charles; Ebner, Alois; Borggrefe, Martin; Brandt, Christian

    2012-01-01

    BACKGROUND The arrhythmogenic potential of short QT intervals has recently been highlighted in patients with a short QT syndrome. Drug-induced QT-interval prolongation is a known risk factor for ventricular tachyarrhythmias. However, reports on drug-induced QT-interval shortening are rare and proarrhythmic effects remain unclear. OBJECTIVE Recently, rufinamide, a new antiepileptic drug for the add-on treatment of Lennox-Gastaut syndrome, was approved in the European Union and the United States. Initial trials showed drug-induced QT-interval shortening. The aim of our study was to evaluate the effects of rufinamide on QT intervals in patients with difficult-to-treat epilepsies. METHODS Nineteen consecutive patients with Lennox-Gastaut syndrome and other epilepsy syndromes were included (n = 12 men; mean age 41 ± 12 years). QRS, QT, and Tpeak-Tend intervals were analyzed before and during rufinamide treatment. RESULTS The mean QT interval shortened significantly following rufinamide administration (QT interval 349 ± 23 ms vs 327 ± 17 ms; corrected QT interval 402 ± 22 ms vs 382 ± 16 ms; P = .002). Tpeak-Tend intervals were 79 ± 17 ms before and 70 ± 20 ms on treatment (P = .07). The mean reduction of the corrected QT interval was 20 ± 18 ms. During follow-up (3.04 ± 1.09 years), no adverse events including symptomatic cardiac arrhythmias or sudden cardiac deaths were observed. CONCLUSION QTc-interval shortening following oral rufinamide administration in a small patient group was not associated with significant clinical adverse effects. These observations nothwithstanding, the ability of rufinamide to significantly shorten the QT interval portends a potential arrhythmogenic risk that may best be guarded against by periodic electrocardiographic recordings. PMID:22245794

  8. Drug-induced QT-interval shortening following antiepileptic treatment with oral rufinamide.

    PubMed

    Schimpf, Rainer; Veltmann, Christian; Papavassiliu, Theano; Rudic, Boris; Göksu, Turgay; Kuschyk, Jürgen; Wolpert, Christian; Antzelevitch, Charles; Ebner, Alois; Borggrefe, Martin; Brandt, Christian

    2012-05-01

    The arrhythmogenic potential of short QT intervals has recently been highlighted in patients with a short QT syndrome. Drug-induced QT-interval prolongation is a known risk factor for ventricular tachyarrhythmias. However, reports on drug-induced QT-interval shortening are rare and proarrhythmic effects remain unclear. Recently, rufinamide, a new antiepileptic drug for the add-on treatment of Lennox-Gastaut syndrome, was approved in the European Union and the United States. Initial trials showed drug-induced QT-interval shortening. The aim of our study was to evaluate the effects of rufinamide on QT intervals in patients with difficult-to-treat epilepsies. Nineteen consecutive patients with Lennox-Gastaut syndrome and other epilepsy syndromes were included (n = 12 men; mean age 41 ± 12 years). QRS, QT, and T(peak)-T(end) intervals were analyzed before and during rufinamide treatment. The mean QT interval shortened significantly following rufinamide administration (QT interval 349 ± 23 ms vs 327 ± 17 ms; corrected QT interval 402 ± 22 ms vs 382 ± 16 ms; P = .002). T(peak)-T(end) intervals were 79 ± 17 ms before and 70 ± 20 ms on treatment (P = .07). The mean reduction of the corrected QT interval was 20 ± 18 ms. During follow-up (3.04 ± 1.09 years), no adverse events including symptomatic cardiac arrhythmias or sudden cardiac deaths were observed. QTc-interval shortening following oral rufinamide administration in a small patient group was not associated with significant clinical adverse effects. These observations notwithstanding, the ability of rufinamide to significantly shorten the QT interval portends a potential arrhythmogenic risk that may best be guarded against by periodic electrocardiographic recordings. Copyright © 2012 Heart Rhythm Society. Published by Elsevier Inc. All rights reserved.

  9. Genetics Home Reference: otopalatodigital syndrome type 1

    MedlinePlus

    ... of a group of related conditions called otopalatodigital spectrum disorders, which also includes otopalatodigital syndrome type 2 , ... 1 is usually the mildest of the otopalatodigital spectrum disorders. People with this condition usually have characteristic ...

  10. Genetics Home Reference: otopalatodigital syndrome type 2

    MedlinePlus

    ... of a group of related conditions called otopalatodigital spectrum disorders, which also includes otopalatodigital syndrome type 1 , ... Diagnosis and Management Resources (1 link) GeneReview: Otopalatodigital Spectrum Disorders General Information from MedlinePlus (5 links) Diagnostic ...

  11. The Response of the QT Interval to the Brief Tachycardia Provoked by Standing

    PubMed Central

    Viskin, Sami; Postema, Pieter G.; Bhuiyan, Zahurul A.; Rosso, Raphael; Kalman, Jonathan M.; Vohra, Jitendra K.; Guevara-Valdivia, Milton E.; Marquez, Manlio F.; Kogan, Evgeni; Belhassen, Bernard; Glikson, Michael; Strasberg, Boris; Antzelevitch, Charles; Wilde, Arthur A. M.

    2010-01-01

    Objectives This study was undertaken to determine whether the short-lived sinus tachycardia that occurs during standing will expose changes in the QT interval that are of diagnostic value. Background The QT interval shortens during heart rate acceleration, but this response is not instantaneous. We tested whether the transient, sudden sinus tachycardia that occurs during standing would expose abnormal QT interval prolongation in patients with long QT syndrome (LQTS). Methods Patients (68 with LQTS [LQT1 46%, LQT2 41%, LQT3 4%, not genotyped 9%] and 82 control subjects) underwent a baseline electrocardiogram (ECG) while resting in the supine position and were then asked to get up quickly and stand still during continuous ECG recording. The QT interval was studied at baseline and during maximal sinus tachycardia, maximal QT interval prolongation, and maximal QT interval stretching. Results In response to brisk standing, patients and control subjects responded with similar heart rate acceleration of 28 ± 10 beats/min (p = 0.261). However, the response of the QT interval to this tachycardia differed: on average, the QT interval of controls shortened by 21 ± 19 ms whereas the QT interval of LQTS patients increased by 4 ± 34 ms (p < 0.001). Since the RR interval shortened more than the QT interval, during maximal tachycardia the corrected QT interval increased by 50 ± 30 ms in the control group and by 89 ± 47 ms in the LQTS group (p < 0.001). Receiver-operating characteristic curves showed that the test adds diagnostic value. The response of the QT interval to brisk standing was particularly impaired in patients with LQT2. Conclusions Evaluation of the response of the QT interval to the brisk tachycardia induced by standing provides important information that aids in the diagnosis of LQTS. PMID:20116193

  12. Living with Long QT Syndrome

    MedlinePlus

    ... level in your blood. These conditions include the eating disorders anorexia nervosa and bulimia, excessive vomiting or diarrhea, ... This Content: NEXT >> Updated: September 21, 2011 Twitter Facebook YouTube Google+ SITE INDEX ACCESSIBILITY PRIVACY STATEMENT FOIA ...

  13. Prenatal diagnosis of type 2 Pfeiffer syndrome.

    PubMed

    Bernstein, P S; Gross, S J; Cohen, D J; Tiller, G R; Shanske, A L; Bombard, A T; Marion, R W

    1996-12-01

    Pfeiffer syndrome is an autosomal dominantly inherited disorder consisting of craniosynostosis, a flattened midface with a beaked nose and ocular proptosis, and broad and medially deviated thumbs and great toes. Recently, based on clinical findings, the disorder has been divided into three subtypes: type 1, characterized by mild expression; type 2, in which clover leaf skull deformity and multiple congenital anomalies are present at birth; and type 3, which is similar to type 2, but lacks the presence of the clover leaf skull at birth. We describe a fetus in whom sonographic findings of clover leaf skull deformity, ocular hypertelorism, and varus deformity of the great toe led to the prenatal diagnosis of Pfeiffer syndrome type 2. We believe this is the second prenatal diagnosis of Pfeiffer syndrome, and the first time type 2 has been definitely identified in the second trimester of pregnancy.

  14. Genetic heterogeneity of Usher syndrome type II.

    PubMed Central

    Pieke Dahl, S; Kimberling, W J; Gorin, M B; Weston, M D; Furman, J M; Pikus, A; Möller, C

    1993-01-01

    Usher syndrome is an autosomal recessive disorder characterised by retinitis pigmentosa and congenital sensorineural hearing loss. A gene for Usher syndrome type II (USH2) has been localised to chromosome 1q32-q41. DNA from a family with four of seven sibs affected with clinical characteristics of Usher syndrome type II was genotyped using markers spanning the 1q32-1q41 region. These included D1S70 and D1S81, which are believed to flank USH2. Genotypic results and subsequent linkage analysis indicated non-linkage of this family to these markers. The A test analysis for heterogeneity with this family and 32 other Usher type II families was statistically significant at p < 0.05. Further clinical evaluation of this family was done in light of the linkage results to determine if any phenotypic characteristics would allow for clinical identification of the unlinked type. No clear phenotypic differences were observed; however, this unlinked family may represent a previously unreported subtype of Usher type II characterised by a milder form of retinitis pigmentosa and mild vestibular abnormalities. Heterogeneity of Usher syndrome type II complicates efforts to isolate and clone Usher syndrome genes using linkage analysis and limits the use of DNA markers in early detection of Usher type II. Images PMID:7901420

  15. Dilated cardiomyopathy with short QT interval: is it a new clinical entity?

    PubMed

    Bohora, Shomu; Namboodiri, Narayanan; Tharakan, Jaganmohan; Vk, Ajit Kumara; Nayyar, Sachin

    2009-05-01

    Short QT syndrome is a rare autosomal dominant channelopathy of structurally normal hearts characterized by atrial fibrillation, ventricular arrhythmias, and sudden cardiac death. We report a case having short QT, dilated ventricles, and severe ventricular dysfunction, an unreported association so far.

  16. Baseline-Corrected QT (QTc) Interval Is Associated with Prolongation of QTc during Severe Hypoglycemia in Patients with Type 2 Diabetes Mellitus

    PubMed Central

    Cha, Seon-Ah; Yun, Jae-Seung; Lim, Tae-Seok; Kang, Yoon-Goo; Lee, Kang-Min; Song, Ki-Ho; Yoo, Ki-Dong; Park, Yong-Moon; Ko, Seung-Hyun

    2016-01-01

    Background We investigated an association between baseline heart rate-corrected QT (QTc) interval before severe hypoglycemia (SH) and prolongation of QTc interval during SH in patients with type 2 diabetes mellitus (T2DM). Methods Between January 2004 and June 2014, 208 patients with T2DM, who visited the emergency department because of SH and underwent standard 12-lead electrocardiography within the 6-month period before SH were consecutively enrolled. The QTc interval was analyzed during the incidence of SH, and 6 months before and after SH. QTc intervals of 450 ms or longer in men and 460 ms or longer in women were considered abnormally prolonged. Results The mean age and diabetes duration were 68.1±12.1 and 14.1±10.1 years, respectively. The mean QTc intervals at baseline and SH episodes were 433±33 and 460±33 ms, respectively (P<0.001). One hundred and fourteen patients (54.8%) had a prolonged QTc interval during SH. There was a significant decrease in the prolonged QTc interval within 6 months after SH (QTc interval prolongation during SH vs. after recovery, 54.8% vs. 33.8%, P<0.001). The prolonged QTc interval was significantly associated with baseline QTc interval prolongation (odds ratio, 2.92; 95% confidence interval, 1.22 to 6.96; P=0.016) after adjusting for multiple confounders. Conclusion A prolonged QTc interval at baseline was significantly associated with prolongation of the QTc interval during SH in patients with T2DM, suggesting the necessity of QTc interval monitoring and attention to those with a prolonged QTc interval to prevent SH. PMID:27766792

  17. Genetic association study of QT interval highlights role for calcium signaling pathways in myocardial repolarization

    PubMed Central

    Arking, Dan E.; Pulit, Sara L.; Crotti, Lia; van der Harst, Pim; Munroe, Patricia B.; Koopmann, Tamara T.; Sotoodehnia, Nona; Rossin, Elizabeth J.; Morley, Michael; Wang, Xinchen; Johnson, Andrew D.; Lundby, Alicia; Gudbjartsson, Daníel F.; Noseworthy, Peter A.; Eijgelsheim, Mark; Bradford, Yuki; Tarasov, Kirill V.; Dörr, Marcus; Müller-Nurasyid, Martina; Lahtinen, Annukka M.; Nolte, Ilja M.; Smith, Albert Vernon; Bis, Joshua C.; Isaacs, Aaron; Newhouse, Stephen J.; Evans, Daniel S.; Post, Wendy S.; Waggott, Daryl; Lyytikäinen, Leo-Pekka; Hicks, Andrew A.; Eisele, Lewin; Ellinghaus, David; Hayward, Caroline; Navarro, Pau; Ulivi, Sheila; Tanaka, Toshiko; Tester, David J.; Chatel, Stéphanie; Gustafsson, Stefan; Kumari, Meena; Morris, Richard W.; Naluai, Åsa T.; Padmanabhan, Sandosh; Kluttig, Alexander; Strohmer, Bernhard; Panayiotou, Andrie G.; Torres, Maria; Knoflach, Michael; Hubacek, Jaroslav A.; Slowikowski, Kamil; Raychaudhuri, Soumya; Kumar, Runjun D.; Harris, Tamara B.; Launer, Lenore J.; Shuldiner, Alan R.; Alonso, Alvaro; Bader, Joel S.; Ehret, Georg; Huang, Hailiang; Kao, W.H. Linda; Strait, James B.; Macfarlane, Peter W.; Brown, Morris; Caulfield, Mark J.; Samani, Nilesh J.; Kronenberg, Florian; Willeit, Johann; Smith, J. Gustav; Greiser, Karin H.; zu Schwabedissen, Henriette Meyer; Werdan, Karl; Carella, Massimo; Zelante, Leopoldo; Heckbert, Susan R.; Psaty, Bruce M.; Rotter, Jerome I.; Kolcic, Ivana; Polašek, Ozren; Wright, Alan F.; Griffin, Maura; Daly, Mark J.; Arnar, David O.; Hólm, Hilma; Thorsteinsdottir, Unnur; Denny, Joshua C.; Roden, Dan M.; Zuvich, Rebecca L.; Emilsson, Valur; Plump, Andrew S.; Larson, Martin G.; O'Donnell, Christopher J.; Yin, Xiaoyan; Bobbo, Marco; D'Adamo, Adamo P.; Iorio, Annamaria; Sinagra, Gianfranco; Carracedo, Angel; Cummings, Steven R.; Nalls, Michael A.; Jula, Antti; Kontula, Kimmo K.; Marjamaa, Annukka; Oikarinen, Lasse; Perola, Markus; Porthan, Kimmo; Erbel, Raimund; Hoffmann, Per; Jöckel, Karl-Heinz; Kälsch, Hagen; Nöthen, Markus M.; consortium, HRGEN; den Hoed, Marcel; Loos, Ruth J.F.; Thelle, Dag S.; Gieger, Christian; Meitinger, Thomas; Perz, Siegfried; Peters, Annette; Prucha, Hanna; Sinner, Moritz F.; Waldenberger, Melanie; de Boer, Rudolf A.; Franke, Lude; van der Vleuten, Pieter A.; Beckmann, Britt Maria; Martens, Eimo; Bardai, Abdennasser; Hofman, Nynke; Wilde, Arthur A.M.; Behr, Elijah R.; Dalageorgou, Chrysoula; Giudicessi, John R.; Medeiros-Domingo, Argelia; Barc, Julien; Kyndt, Florence; Probst, Vincent; Ghidoni, Alice; Insolia, Roberto; Hamilton, Robert M.; Scherer, Stephen W.; Brandimarto, Jeffrey; Margulies, Kenneth; Moravec, Christine E.; Fabiola Del, Greco M.; Fuchsberger, Christian; O'Connell, Jeffrey R.; Lee, Wai K.; Watt, Graham C.M.; Campbell, Harry; Wild, Sarah H.; El Mokhtari, Nour E.; Frey, Norbert; Asselbergs, Folkert W.; Leach, Irene Mateo; Navis, Gerjan; van den Berg, Maarten P.; van Veldhuisen, Dirk J.; Kellis, Manolis; Krijthe, Bouwe P.; Franco, Oscar H.; Hofman, Albert; Kors, Jan A.; Uitterlinden, André G.; Witteman, Jacqueline C.M.; Kedenko, Lyudmyla; Lamina, Claudia; Oostra, Ben A.; Abecasis, Gonçalo R.; Lakatta, Edward G.; Mulas, Antonella; Orrú, Marco; Schlessinger, David; Uda, Manuela; Markus, Marcello R.P.; Völker, Uwe; Snieder, Harold; Spector, Timothy D.; Ärnlöv, Johan; Lind, Lars; Sundström, Johan; Syvänen, Ann-Christine; Kivimaki, Mika; Kähönen, Mika; Mononen, Nina; Raitakari, Olli T.; Viikari, Jorma S.; Adamkova, Vera; Kiechl, Stefan; Brion, Maria; Nicolaides, Andrew N.; Paulweber, Bernhard; Haerting, Johannes; Dominiczak, Anna F.; Nyberg, Fredrik; Whincup, Peter H.; Hingorani, Aroon; Schott, Jean-Jacques; Bezzina, Connie R.; Ingelsson, Erik; Ferrucci, Luigi; Gasparini, Paolo; Wilson, James F.; Rudan, Igor; Franke, Andre; Mühleisen, Thomas W.; Pramstaller, Peter P.; Lehtimäki, Terho J.; Paterson, Andrew D.; Parsa, Afshin; Liu, Yongmei; van Duijn, Cornelia; Siscovick, David S.; Gudnason, Vilmundur; Jamshidi, Yalda; Salomaa, Veikko; Felix, Stephan B.; Sanna, Serena; Ritchie, Marylyn D.; Stricker, Bruno H.; Stefansson, Kari; Boyer, Laurie A.; Cappola, Thomas P.; Olsen, Jesper V.; Lage, Kasper; Schwartz, Peter J.; Kääb, Stefan; Chakravarti, Aravinda; Ackerman, Michael J.; Pfeufer, Arne; de Bakker, Paul I.W.; Newton-Cheh, Christopher

    2014-01-01

    The QT interval, an electrocardiographic measure reflecting myocardial repolarization, is a heritable trait. QT prolongation is a risk factor for ventricular arrhythmias and sudden cardiac death (SCD) and could indicate the presence of the potentially lethal Mendelian Long QT Syndrome (LQTS). Using a genome-wide association and replication study in up to 100,000 individuals we identified 35 common variant QT interval loci, that collectively explain ∼8-10% of QT variation and highlight the importance of calcium regulation in myocardial repolarization. Rare variant analysis of 6 novel QT loci in 298 unrelated LQTS probands identified coding variants not found in controls but of uncertain causality and therefore requiring validation. Several newly identified loci encode for proteins that physically interact with other recognized repolarization proteins. Our integration of common variant association, expression and orthogonal protein-protein interaction screens provides new insights into cardiac electrophysiology and identifies novel candidate genes for ventricular arrhythmias, LQTS,and SCD. PMID:24952745

  18. The clinical significance of QT prolongation associated with tamoxifen: A review of the literature.

    PubMed

    Fung, Katherine; Imeson, Julia; Cusano, Frances

    2017-01-01

    Objective To review the literature discussing QT prolongation associated with the use of tamoxifen in order to evaluate the clinical significance. Data sources A search of PubMed (1946 to 2017), MEDLINE (1946 to 2017) and EMBASE (1947 to 2017) was performed using a combination of the following search terms: tamoxifen, estrogen antagonist, selective estrogen receptor modulator, QT prolongation, QT interval, long QT syndrome and torsades de pointes. All searches were limited to human subjects. Reference lists of the literature found were also reviewed but did not reveal any further articles. Study selection Articles reviewed were relating to humans only and included clinical trials and case reports that mentioned QT prolongation in association with the use of tamoxifen. Data synthesis It can be common for patients on tamoxifen to also be on a number of different medications being used to treat comorbid medical conditions. Such combinations of medications increase the potential risk for drug interactions, such as drug-induced QT prolongation. Tamoxifen is often flagged by tertiary drug information sources as a drug with indeterminate effects on the QT interval. However, the risk may be elevated when combined with other QT-prolonging agents. A total of five publications were identified, including two phase I clinical trials and three case reports, which discussed the association between tamoxifen and QT prolongation. Conclusions Tertiary drug information sources identify tamoxifen as an agent that may cause QT prolongation when used in combination with other QT-prolonging agents. However, based on the limited number of published reports found, it would suggest that the use of tamoxifen concurrently with other agents known to prolong the QT interval is likely to be of low risk for causing a clinically significant QT-prolonging event, especially at a dose of 20 mg daily.

  19. Prenatal diagnosis of Pfeiffer syndrome type II.

    PubMed

    Blaumeiser, Bettina; Loquet, Philip; Wuyts, Wim; Nöthen, Markus M

    2004-08-01

    Pfeiffer syndrome is an autosomal dominant disorder characterized by coronal craniosynostosis, midface hypoplasia, broad thumbs and great toes. On the basis of clinical findings, three subtypes have been delineated. The clinical variability of Pfeiffer syndrome as well as other causes of craniosynostosis can make a prenatal diagnosis based on sonography alone difficult. We describe a fetus in whom sonographic findings (including 3D ultrasound) suggested a Pfeiffer syndrome type II and in which subsequent molecular analysis verified the diagnosis by identifying a de novo mutation in the FGFR2 gene. To the best of our knowledge, this is the first report of a prenatal molecular diagnosis of Pfeiffer syndrome in a patient without family history.

  20. Fluconazole-Induced Type 1 Kounis Syndrome.

    PubMed

    Singh Mahal, Hardeep

    2016-01-01

    The administration of fluconazole is commonly used in both inpatient and outpatient settings for the management of candidiasis infection. Although it is associated with a relatively safe side effect profile, some patients experience adverse effects associated with increased morbidity. We describe 1 such patient, a 42-year-old woman with a history of severe eczema who developed fluconazole-induced type 1 Kounis syndrome. Review of literature indicates that this as the first case reported of fluconazole-induced type 1 Kounis syndrome.

  1. Pronounced effects of HERG-blockers E-4031 and erythromycin on APD, spatial APD dispersion and triangulation in transgenic long-QT type 1 rabbits.

    PubMed

    Ziupa, David; Beck, Julia; Franke, Gerlind; Perez Feliz, Stefanie; Hartmann, Maximilian; Koren, Gideon; Zehender, Manfred; Bode, Christoph; Brunner, Michael; Odening, Katja E

    2014-01-01

    Prolongation of action potential duration (APD), increased spatial APD dispersion, and triangulation are major factors promoting drug-induced ventricular arrhythmia. Preclinical identification of HERG/IKr-blocking drugs and their pro-arrhythmic potential, however, remains a challenge. We hypothesize that transgenic long-QT type 1 (LQT1) rabbits lacking repolarizing IKs current may help to sensitively detect HERG/IKr-blocking properties of drugs. Hearts of adult female transgenic LQT1 and wild type littermate control (LMC) rabbits were Langendorff-perfused with increasing concentrations of HERG/IKr-blockers E-4031 (0.001-0.1 µM, n=9/7) or erythromycin (1-300 µM, n=9/7) and APD, APD dispersion, and triangulation were analyzed. At baseline, APD was longer in LQT1 than in LMC rabbits in LV apex and RV mid. Erythromycin and E-4031 prolonged APD in LQT1 and LMC rabbits in all positions. However, erythromycin-induced percentaged APD prolongation related to baseline (%APD) was more pronounced in LQT1 at LV base-lateral and RV mid positions (100 µM, LQT1, +40.6 ± 9.7% vs. LMC, +24.1 ± 10.0%, p<0.05) and E-4031-induced %APD prolongation was more pronounced in LQT1 at LV base-lateral (0.01 µM, LQT1, +29.6 ± 10.6% vs. LMC, +19.1 ± 3.8%, p<0.05) and LV base-septal positions. Moreover, erythromycin significantly increased spatial APD dispersion only in LQT1 and increased triangulation only in LQT1 in LV base-septal and RV mid positions. Similarly, E-4031 increased triangulation only in LQT1 in LV apex and base-septal positions. E-4031 and erythromycin prolonged APD and increased triangulation more pronouncedly in LQT1 than in LMC rabbits. Moreover, erythromycin increased APD dispersion only in LQT1, indicating that transgenic LQT1 rabbits could serve as sensitive model to detect HERG/IKr-blocking properties of drugs.

  2. Pronounced Effects of HERG-Blockers E-4031 and Erythromycin on APD, Spatial APD Dispersion and Triangulation in Transgenic Long-QT Type 1 Rabbits

    PubMed Central

    Franke, Gerlind; Perez Feliz, Stefanie; Hartmann, Maximilian; Koren, Gideon; Zehender, Manfred; Bode, Christoph; Brunner, Michael; Odening, Katja E.

    2014-01-01

    Background Prolongation of action potential duration (APD), increased spatial APD dispersion, and triangulation are major factors promoting drug-induced ventricular arrhythmia. Preclinical identification of HERG/IKr-blocking drugs and their pro-arrhythmic potential, however, remains a challenge. We hypothesize that transgenic long-QT type 1 (LQT1) rabbits lacking repolarizing IKs current may help to sensitively detect HERG/IKr-blocking properties of drugs. Methods Hearts of adult female transgenic LQT1 and wild type littermate control (LMC) rabbits were Langendorff-perfused with increasing concentrations of HERG/IKr-blockers E-4031 (0.001–0.1 µM, n = 9/7) or erythromycin (1–300 µM, n = 9/7) and APD, APD dispersion, and triangulation were analyzed. Results At baseline, APD was longer in LQT1 than in LMC rabbits in LV apex and RV mid. Erythromycin and E-4031 prolonged APD in LQT1 and LMC rabbits in all positions. However, erythromycin-induced percentaged APD prolongation related to baseline (%APD) was more pronounced in LQT1 at LV base-lateral and RV mid positions (100 µM, LQT1, +40.6±9.7% vs. LMC, +24.1±10.0%, p<0.05) and E-4031-induced %APD prolongation was more pronounced in LQT1 at LV base-lateral (0.01 µM, LQT1, +29.6±10.6% vs. LMC, +19.1±3.8%, p<0.05) and LV base-septal positions. Moreover, erythromycin significantly increased spatial APD dispersion only in LQT1 and increased triangulation only in LQT1 in LV base-septal and RV mid positions. Similarly, E-4031 increased triangulation only in LQT1 in LV apex and base-septal positions. Conclusions E-4031 and erythromycin prolonged APD and increased triangulation more pronouncedly in LQT1 than in LMC rabbits. Moreover, erythromycin increased APD dispersion only in LQT1, indicating that transgenic LQT1 rabbits could serve as sensitive model to detect HERG/IKr-blocking properties of drugs. PMID:25244401

  3. Sudden death in type 1 diabetes: the mystery of the 'dead in bed' syndrome.

    PubMed

    Tu, Emily; Twigg, Stephen M; Semsarian, Christopher

    2010-01-07

    Sudden cardiac death is an unpredictable and devastating event, particularly in the young. A significant proportion of sudden deaths in the young are unexplained-no cause is identified either during life or at post-mortem. This is seen in a subgroup of young patients with type 1 diabetes who have dead in bed syndrome, where these victims are in good health, retire to bed, only to be found dead the following morning in a bed which is undisturbed, suggesting no terminal struggle or seizure. The underlying cause of dead in bed syndrome remains unknown, but is likely to be due to a terminal malignant arrhythmia. A plausible hypothesis is that it may be secondary to QT interval prolongation (followed by a degenerate ventricular tachycardia), caused by a number of factors including acute hypoglycaemia, on a background of cardiac autonomic neuropathy, and possible genetic influences. It is envisaged that understanding the causes and triggers of dead in bed syndrome will allow appropriate therapeutic interventions to be initiated in high-risk patients with type 1 diabetes, with the ultimate goal to prevent sudden death.

  4. Quinine and the ABCs of Long QT: A Patient's Misfortune with Arthritis, (Alcoholic) Beverages, and Cramps.

    PubMed

    Sheehan, Elyce T; Frizzell, Jarrod D; Gabaldon, Jude; West, Michael B

    2016-10-01

    A 91-year-old woman presented to the emergency department by ambulance after her family found her minimally responsive. Telemetry monitoring demonstrated episodes of non-sustained polymorphic ventricular tachycardia (PMVT) associated with significantly prolonged repolarization. Her medical history revealed that she was taking quinine or a derivative in three different forms: hydroxychloroquine, quinine sulfate (for leg cramps), and her gin mixed with tonic water (containing quinine). The present case is illustrative of classic etiologies and findings of acquired long QT syndrome, and serves as an important reminder for providers to take a complete medication history, including use of duplicative and alternative medicines and type of alcohol consumption.

  5. Moyamoya syndrome and neurofibromatosis type 1

    PubMed Central

    2014-01-01

    Neurofibromatosis type 1 (NF1) is the most prevalent autosomal dominant genetic disorder among humans. NF1 vasculopathy is a significant but underrecognized complication of the disease, affecting both arterial and venous blood vessels of all sizes. Moyamoya syndrome is a cerebral vasculopathy that is only rarely observed in association with NF1, particularly in the pediatric age range. Herein, we report of a 5-year-old female with NF1 and moyamoya syndrome and we briefly review the existing literature. PMID:24952383

  6. [Type 1 diabetes and autoimmune polyendocrine syndromes].

    PubMed

    Queiroz, Márcia S

    2008-03-01

    Type 1 diabetes (T1D) is associated with autoimmune thyroid disease (AIT), celiac disease (CD), Addison's disease (AD), and other autoimmune diseases. These diseases can occur simultaneously in defined syndromes with distinct pathophysiology and characteristics: autoimmune polyendocrine syndromes (APSs) and the immunodysregulation polyendocrinopathy enteropathy X-linked syndrome (IPEX). APSs were initially defined as a multiple endocrine gland insufficiency associated to an autoimmune disease in a patient. APS-1 is characterized by the evidence of chronic candidiasis, chronic hypoparathyroidism, AD and T1D could be present as part of this syndrome. The combination of autoimmune adrenal insufficiency with AIT and/or type 1 autoimmune diabetes mellitus defines APS-2. AIT associated to other autoimmune diseases (excluding AD and/or hypoparathyroidism) are the main characteristics of APS-3. Different clinical combinations of autoimmune diseases which were not included in the previous groups are the characteristics of APS-4. IPEX is a recessive disorder characterized by the neonatal onset of T1D, infections, enteropathy, thrombocytopenia and anemia, as well as endocrinopathy, eczema and cachexia. These disorders are not common, but their consequences can be life threatening when the diagnosis is overlooked, and the treatment is the same prescribed for isolated disease presentation.

  7. Bartter's syndrome with type 2 diabetes mellitus.

    PubMed

    See, Ting-Ting; Lee, Siu-Pak

    2009-02-01

    We report a rare case of Bartter's syndrome in a 35-year-old woman with type 2 diabetes mellitus. The patient presented with leg weakness, fatigue, polyuria and polydipsia. Hypokalemia, metabolic alkalosis, and high renin and aldosterone concentrations were present, but the patient was normotensive. Gitelman's syndrome was excluded because of the presence of hypercalciuria, secondary hyperparathyroidism and bilateral nephrocalcinosis. The patients condition improved upon administration of a prostaglandin synthetase inhibitor (acemetacin), oral potassium chloride and potassium-sparing diuretics. Five months later, the patient discontinued acemetacin because of epigastric discomfort; at the same time, severe hypokalemia and hyperglycemia developed. Glucagon stimulation and water deprivation tests were performed. Type 2 diabetes mellitus with nephrogenic diabetes insipidus was diagnosed. To avoid further gastrointestinal complications, the patient was treated with celecoxib, a selective cyclooxygenase 2 inhibitor. This case serves as a reminder that Bartter's syndrome is associated with various metabolic derangements including nephrogenic diabetes insipidus, nephrocalcinosis and diabetes mellitus. When treating Bartter's syndrome, it is also prudent to remember that the long-term use of nonsteroidal anti-inflammatory drugs and potassium-sparing diuretics may result in serious adverse reactions.

  8. Waardenburg Syndrome type 1: A case report.

    PubMed

    Demirci, Gulsen Tukenmez; Atıs, Guldehan; Altunay, Ilknur Kıvanc

    2011-11-15

    Waardenburg Syndrome (WS) is a rare hereditary disorder that is characterized by the clinical manifestations of oculocutaneous anomalies of pigmentation, congenital deafness, dystopia canthorum, and broad nasal root. It demonstrates both genetically and clinically heterogenous characteristics. In this article, we report an 11-month-old boy with WS1, one of four clinicat types of WS. He exhibited white forelock, hypopigmented macules and patches, heterochromia irides, and dystopia canthorum.

  9. Genetics Home Reference: Jervell and Lange-Nielsen syndrome

    MedlinePlus

    ... KCNQ1 or KCNE1 mutation have a long QT interval with related heart abnormalities, but their hearing is ... disease Jervell-Lange Nielsen syndrome JLNS prolonged QT interval in EKG and sudden death surdo-cardiac syndrome ...

  10. The development and validation of an easy to use automatic QT-interval algorithm.

    PubMed

    Hermans, Ben J M; Vink, Arja S; Bennis, Frank C; Filippini, Luc H; Meijborg, Veronique M F; Wilde, Arthur A M; Pison, Laurent; Postema, Pieter G; Delhaas, Tammo

    2017-01-01

    To evaluate QT-interval dynamics in patients and in drug safety analysis, beat-to-beat QT-interval measurements are increasingly used. However, interobserver differences, aberrant T-wave morphologies and changes in heart axis might hamper accurate QT-interval measurements. To develop and validate a QT-interval algorithm robust to heart axis orientation and T-wave morphology that can be applied on a beat-to-beat basis. Additionally to standard ECG leads, the root mean square (ECGRMS), standard deviation and vectorcardiogram were used. QRS-onset was defined from the ECGRMS. T-wave end was defined per individual lead and scalar ECG using an automated tangent method. A median of all T-wave ends was used as the general T-wave end per beat. Supine-standing tests of 73 patients with Long-QT syndrome (LQTS) and 54 controls were used because they have wide ranges of RR and QT-intervals as well as changes in T-wave morphology and heart axis orientation. For each subject, automatically estimated QT-intervals in three random complexes chosen from the low, middle and high RR range, were compared with manually measured QT-intervals by three observers. After visual inspection of the randomly selected complexes, 21 complexes were excluded because of evident noise, too flat T-waves or premature ventricular beats. Bland-Altman analyses of automatically and manually determined QT-intervals showed a bias of <4ms and limits of agreement of ±25ms. Intra-class coefficient indicated excellent agreement (>0.9) between the algorithm and all observers individually as well as between the algorithm and the mean QT-interval of the observers. Our automated algorithm provides reliable beat-to-beat QT-interval assessment, robust to heart axis and T-wave morphology.

  11. [Type 2 autoimmune polyendocrine syndromes (APS-2)].

    PubMed

    Vialettes, Bernard; Dubois-Leonardon, Noémie

    2013-01-01

    Type 2 autoimmune polyendocrine syndromes (APS-2) are the most frequent disorders associating several organ-specific autoimmune diseases. Their high prevalence is due to the fact that the main manifestations of APS-2, such as thyroidal autoimmunity, type 1 diabetes, autoimmune gastric atrophy and vitiligo, are common diseases. APS-2 represents a clinical model that can serve to help unravel the mechanisms underlying autoimmunity. Diagnosis of APS-2 is a challenge for the clinician, especially in poorly symptomatic forms, and may require systematic screening based on measurement of autoantibodies and functional markers.

  12. Effect of mood states on QT interval and QT dispersion in eating disorder patients.

    PubMed

    Takimoto, Yoshiyuki; Yoshiuchi, Kazuhiro; Akabayashi, Akira

    2008-04-01

    Prolonged QT interval and QT dispersion have been reported in patients with eating disorders. Although the factors that cause prolongation remain unclear, mood states such as anxiety have been reported to influence QT interval and dispersion, probably via the autonomic nervous system. Therefore the aim of the present paper was to investigate mood effect on prolonged QT interval and QT dispersion. The subjects were 47 female anorexia nervosa (AN) and 48 female bulimia nervosa (BN) patients. In all of the patients, serum electrolyte levels were normal. QT interval and QT dispersion were measured from 12-lead electrocardiographic recordings. Mood states in each patient were measured using a Profile of Mood States (POMS) evaluation, and the patients were divided into high- and low-score groups for each POMS subscale. The differences in QT variables were compared between the two groups for each subscale. In the BN group, QT interval and QT dispersion in the high depression score group were significantly longer than those in the low depression score group, and QT dispersion was significantly greater in the high anxiety score group than in the low anxiety score group. In addition, QT interval and QT dispersion were significantly correlated with depression scores. In the AN group there were no significant differences in QT interval or QT dispersion between the high- and low-score groups for any POMS subscale. BN patients with worse states of depression or anxiety had longer QT intervals and larger QT dispersion. In BN patients, mood disturbance might increase the risk of arrhythmias.

  13. Cardiorenal syndrome type 4: a review.

    PubMed

    Clementi, Anna; Virzì, Grazia Maria; Goh, Ching Yan; Cruz, Dinna N; Granata, Antonio; Vescovo, Girogio; Ronco, Claudio

    2013-04-01

    There is a bidirectional and complex relationship between the heart and kidneys. This interaction is physical, chemical as well as biological and is also reflected in a strong connection between renal and cardiovascular diseases. Cardiorenal syndrome type 4 (CRS type 4) is characterized by primary chronic kidney disease (CKD) leading to an impairment of cardiac function, with ventricular hypertrophy, diastolic dysfunction, and/or increased risk of adverse cardiovascular events. The incidence of CKD is increasing, and CRS type 4 is becoming a major public health problem associated with a high morbidity and mortality. In this study, we briefly review the epidemiology and pathophysiology of CRS type 4, the role of biomarkers in its early identification, and its management.

  14. Type 3 Pfeiffer syndrome with normal thumbs.

    PubMed

    Kerr, N C; Wilroy, R S; Kaufman, R A

    1996-12-11

    We report on a male infant with extremely shallow orbits, spontaneous luxation of the eyes out of the eyelids, hypoplastic midface, broad, medially rotated great toes, and respiratory distress due to severe bilateral posterior choanal stenosis. At 4 days he had open cranial sutures (both by palpation and radiological examination). Subsequent radiologic studies demonstrated: thickening of the skull base, vertebral anomalies, flattening of the olecranon fossae with dislocated radii, and triangular shape of the proximal phalanx of the first toes. Our patient had manifestations of type 3 Pfeiffer syndrome (PS). However, the finding of normal thumbs has not been reported in type 3 PS. Point mutations in fibroblast growth factor receptor-1 (FGFR1) and fibroblast growth factor receptor-2 (FGFR2) have been reported in familial and sporadic cases of PS, but were not found in this patient. Recognizing type 3 PS, despite variability in expression, is important for genetic counseling, prognosis, and decision-making regarding craniofacial surgery.

  15. Antipsychotic agents and QT changes.

    PubMed Central

    Welch, R; Chue, P

    2000-01-01

    Recently, antipsychotic medications of the novel or atypical classes have received increased attention because of concerns with respect to potential lengthening of the QT interval, yet the currently available and commonly prescribed conventional antipsychotics are significantly more cardiotoxic, particularly agents in the butyrophenone and phenothiazine classes. Lengthening of the QT interval can be associated with a fatal paroxysmal ventricular arrhythmia known as torsades de pointes. The specific duration of the QT interval at which the risk of an adverse cardiac event is greatest, is not established. There is not only significant variation in the applied definition of an abnormal interval, but the maximal QT interval in healthy volunteers is greater than the currently accepted standards. The QT interval is influenced by normal physiological and pathologic factors, but the mechanisms remain unclear. Using recombinant technology, haloperidol and sertindole have been demonstrated to be high-affinity antagonists of a human cardiac potassium channel encoded by the human ether-a-go-go-related gene. Pimozide, however, has been shown to act principally through calcium channel antagonism, and chlorpromazine may affect sodium channels. Nevertheless, it is possible that these effects are significant only in the presence of predisposing factors, either genetic or acquired. Despite proven efficacy in clinical trials and subsequent supervised use in Europe, a number of recently developed antipsychotic medications are not available to patients in North America. Yet, conventional antipsychotic medications that would not be approved by current safety standards continue to be widely used. PMID:10740988

  16. The Measurement of the QT Interval

    PubMed Central

    Postema, Pieter G; Wilde, Arthur A.M

    2014-01-01

    The evaluation of every electrocardiogram should also include an effort to interpret the QT interval to assess the risk of malignant arrhythmias and sudden death associated with an aberrant QT interval. The QT interval is measured from the beginning of the QRS complex to the end of the T-wave, and should be corrected for heart rate to enable comparison with reference values. However, the correct determination of the QT interval, and its value, appears to be a daunting task. Although computerized analysis and interpretation of the QT interval are widely available, these might well over- or underestimate the QT interval and may thus either result in unnecessary treatment or preclude appropriate measures to be taken. This is particularly evident with difficult T-wave morphologies and technically suboptimal ECGs. Similarly, also accurate manual assessment of the QT interval appears to be difficult for many physicians worldwide. In this review we delineate the history of the measurement of the QT interval, its underlying pathophysiological mechanisms and the current standards of the measurement of the QT interval, we provide a glimpse into the future and we discuss several issues troubling accurate measurement of the QT interval. These issues include the lead choice, U-waves, determination of the end of the T-wave, different heart rate correction formulas, arrhythmias and the definition of normal and aberrant QT intervals. Furthermore, we provide recommendations that may serve as guidance to address these complexities and which support accurate assessment of the QT interval and its interpretation. PMID:24827793

  17. Which QT Correction Formulae to Use for QT Monitoring?

    PubMed

    Vandenberk, Bert; Vandael, Eline; Robyns, Tomas; Vandenberghe, Joris; Garweg, Christophe; Foulon, Veerle; Ector, Joris; Willems, Rik

    2016-06-17

    Drug safety precautions recommend monitoring of the corrected QT interval. To determine which QT correction formula to use in an automated QT-monitoring algorithm in our electronic medical record, we studied rate correction performance of different QT correction formulae and their impact on risk assessment for mortality. All electrocardiograms (ECGs) in patients >18 years with sinus rhythm, normal QRS duration and rate <90 beats per minute (bpm) in the University Hospitals of Leuven (Leuven, Belgium) during a 2-month period were included. QT correction was performed with Bazett, Fridericia, Framingham, Hodges, and Rautaharju formulae. In total, 6609 patients were included (age, 59.8±16.2 years; 53.6% male and heart rate 68.8±10.6 bpm). Optimal rate correction was observed using Fridericia and Framingham; Bazett performed worst. A healthy subset showed 99% upper limits of normal for Bazett above current clinical standards: men 472 ms (95% CI, 464-478 ms) and women 482 ms (95% CI 474-490 ms). Multivariate Cox regression, including age, heart rate, and prolonged QTc, identified Framingham (hazard ratio [HR], 7.31; 95% CI, 4.10-13.05) and Fridericia (HR, 5.95; 95% CI, 3.34-10.60) as significantly better predictors of 30-day all-cause mortality than Bazett (HR, 4.49; 95% CI, 2.31-8.74). In a point-prevalence study with haloperidol, the number of patients classified to be at risk for possibly harmful QT prolongation could be reduced by 50% using optimal QT rate correction. Fridericia and Framingham correction formulae showed the best rate correction and significantly improved prediction of 30-day and 1-year mortality. With current clinical standards, Bazett overestimated the number of patients with potential dangerous QTc prolongation, which could lead to unnecessary safety measurements as withholding the patient of first-choice medication. © 2016 The Authors. Published on behalf of the American Heart Association, Inc., by Wiley Blackwell.

  18. QT interval in children with sensory neural hearing loss.

    PubMed

    El Habbal, Magdi H; Mahoney, C O

    2002-04-01

    Long QT syndrome was first described in children with congenital sensory neural hearing loss (SNHL). The deafness was attributed to abnormalities in potassium ion channels of the inner ear. Similar channels are present in the heart and its dysfunction causes long QT syndrome. Whether congenital SNHL is associated with prolonged QT is unknown. This study examined 52 patients (median age 8.35 years, range 0.21-17.42 years) with SNHL and compared them to 63 healthy children (median age 10.2 years; range 0.67-19 years). An observer, who was blinded from the presence or absence of SNHL, measured QT, QTc intervals and dispersions from a standard 12-lead electrocardiogram. To assess the cardiac autonomic enervation, power spectral analysis of heart rate variability was determined using a 24-hour ambulatory heart rate monitor and was expressed as high (HF) to low frequency (LF) ratio. Left ventricular size and functions were evaluated by using two-dimensional echocardiography. The medians (and ranges) of QT intervals were 340 ms (230-420 ms) in patients and 320 ms (240-386 ms) in the control group (P < 0.01). The QTc was longer in patients with SNHL (median 417 ms, range 384-490 ms) than in controls (median 388 ms, range 325-432 ms, P < 0.001). QT dispersions in SNHL were higher (median .038 ms, range 00-11 ms) than controls (median 27 ms, range 00-52 ms, P < 0.001). T wave inversion (n = 16) and alternans (n = 3) occurred in patients with SNHL. Heart rates were similar in both groups. Some deaf patients (n = 8) had dizzy episodes with a QTc > 440 ms. The HF:LF ratio was 1.32 (0.516-2.33) in deaf patients and 1.428 (0.67-2.3) in the control group (P > 0.1). Left ventricular size and functions were similar and normal in deaf patients and controls. In children, congenital SNHL is associated with a prolonged QT interval.

  19. Cardiac sodium channel mutation associated with epinephrine-induced QT prolongation and sinus node dysfunction.

    PubMed

    Chen, Jiarong; Makiyama, Takeru; Wuriyanghai, Yimin; Ohno, Seiko; Sasaki, Kenichi; Hayano, Mamoru; Harita, Takeshi; Nishiuchi, Suguru; Yuta Yamamoto; Ueyama, Takeshi; Shimizu, Akihiko; Horie, Minoru; Kimura, Takeshi

    2016-01-01

    Long-QT syndrome (LQTS) is an inherited arrhythmia characterized by prolonged ventricular repolarization and malignant tachyarrhythmias. LQT1, LQT2, and LQT3 are caused by mutations in KCNQ1 (LQT1), KCNH2 (LQT2), and SCN5A (LQT3), which account for approximately 90% of genotyped LQTS patients. Most cardiac events in LQT1 patients occur during exercise, whereas patients with LQT3 tend to have arrhythmic events during rest or asleep. The study aimed to identify a genetic mutation in a Japanese man who presented with sinus node dysfunction and prolonged QT interval on exercise and epinephrine stress tests, as well as to clarify the electrophysiological properties of mutant channels. LQTS-related genes were screened in this patient. Electrophysiological functional assays were conducted with a heterologous expression system. We identified a heterozygous missense SCN5A mutation, V2016M, which changes the last amino acid of the cardiac sodium channel. Electrophysiological analyses revealed that the mutant channels exhibited a loss-of-function feature, decreased peak sodium current densities (wild type 175.2 ± 17.6 pA/pF; V2016M 97.2 ± 16.0 pA/pF; P < .01). In addition, the mutant channels showed gain-of-function features: increased late sodium currents by protein kinase A activation (wild type 0.07 ± 0.01%; V2016M 0.17 ± 0.03%; P < .05) and impaired inactivation of sodium channels by protein kinase A or C activation. We identified an SCN5A mutation in a patient with sinus node dysfunction and epinephrine-induced QT prolongation, which was an atypical phenotype for LQT3. The electrophysiological properties of the mutant channels might be associated with the overlapping clinical features of the patient. Copyright © 2016. Published by Elsevier Inc.

  20. Current Understanding of Usher Syndrome Type II

    PubMed Central

    Yang, Jun; Wang, Le; Song, Hongman; Sokolov, Maxim

    2012-01-01

    Usher syndrome is the most common deafness-blindness caused by genetic mutations. To date, three genes have been identified underlying the most prevalent form of Usher syndrome, the type II form (USH2). The proteins encoded by these genes are demonstrated to form a complex in vivo. This complex is localized mainly at the periciliary membrane complex in photoreceptors and the ankle-link of the stereocilia in hair cells. Many proteins have been found to interact with USH2 proteins in vitro, suggesting that they are potential additional components of this USH2 complex and that the genes encoding these proteins may be the candidate USH2 genes. However, further investigations are critical to establish their existence in the USH2 complex in vivo. Based on the predicted functional domains in USH2 proteins, their cellular localizations in photoreceptors and hair cells, the observed phenotypes in USH2 mutant mice, and the known knowledge about diseases similar to USH2, putative biological functions of the USH2 complex have been proposed. Finally, therapeutic approaches for this group of diseases are now being actively explored. PMID:22201796

  1. Other drugs acting on nervous system associated with QT-interval prolongation.

    PubMed

    Keller, Guillermo Alberto; Ponte, Marcelo L; Di Girolamo, Guillermo

    2010-01-01

    Several drugs acting on the nervous system have been implicated in the prolongation of the QT interval. Leaving aside the antidepressant and antipsychotic drugs, some have shown to prolong the QT interval in vivo. These include opioids, particularly methadone, inhalational anesthetics, and some preparations used for treatment of cough. These drugs have a narrow therapeutic interval or possible drug interactions that lead to clinical toxicity manifested by arrhythmias. They share the ability to block potassium channels (HERG), prolong the action potential and QT interval, and generate arrhythmias and Torsades de Pointes like other typicality recognized like antiarrhythmics, antihistamines, prokinetics, psychotropics and anti-infectives agents. Muscle relaxants like alcuronium, pancuronium and atracurium associated with or without atropine prolong significantly the QT interval. Methadone is the opiod most tightly associated with QTc prolongation; with much lesser potency buprenorphine and oxycodone can block HERG channels and depress the IKr current in vitro.Antineoplastic chemotherapy like anthracyclines, alkylating drugs, alkilants and cisplatin are associated with electrocardiographic alterations including prolongation of QT and emesis of different grades. It's very important take in account the synergic effects over the QT prolongation when effective antiemetics like 5-HT3 receptor antagonist (granisetron, ondansetron, and dolasetron) are administered. The Knowledge of their pharmacological properties is of vital importance to avoid exposing particularly vulnerable individuals as those with congenital long QT syndrome, and even the general public to unnecessary risk of potentially fatal arrhythmias.

  2. Preliminary research on syndrome types of Chinese medicine in children with primary nephrotic syndrome.

    PubMed

    Sun, Wen; Yu, Jian; Zeng, Gu-Lan; Zhang, Bing-Feng

    2017-08-17

    To provide an objective reference for the syndrome types of Chinese medicine (CM) associated with pediatric primary nephrotic syndrome (PNS). A cross-sectional study was performed. Data on clinical symptoms, CM syndrome types, biochemical indices, and medications used were collected from 98 children with PNS. Then, the correlation between CM syndromes and biochemical indices, as well as medications used, was analyzed. The four most common symptoms in children with PNS were brown urine, red tongue, excessive sweating, and swelling of the face and limbs. The syndromes of qi deficiency of Fei (Lung) and Shen (Kidney) (FSQD) and yin deficiency of Gan (Liver) and Shen (GSYD) were the most common main CM syndrome types. FSQD syndrome score correlated significantly with the total cholesterol level, urine protein/creatinine ratio, and urine IgG and albumin levels (P<0.01 or P<0.05). The use of maintenance glucocorticoids combined with immunosuppressive agents correlated with FSQD syndrome, and the use of maintenance glucocorticoids alone correlated with GSYD syndrome (P<0.05). Two of the most common CM syndrome types were FSQD and GSYD syndromes. FSQD syndrome may be caused by some factors related to lipid levels, protein loss, and the use of immunosuppressive agents. The use of maintenance glucocorticoids may cause GSYD syndrome.

  3. Neurofibromatosis type 1 with overlap Turner syndrome and Klinefelter syndrome.

    PubMed

    Hatipoglu, Nihal; Kurtoglu, Selim; Kendirci, Mustafa; Keskin, Mehmet; Per, Hüseyin

    2010-02-01

    Turner's syndrome is a sex chromosome disorder. Klinefelter's syndrome is one of the most severe genetic diseases. Neurofibromatosis is an autosomal dominant disorder characterized by cafe-au-lait spots and fibromatous tumors of the skin. In this article, we report the overlap of neurofibromatosis-1 with Turner and Klinefelter syndromes. Thus, these disorders might overlap within the same patient. Due to these cases, we suggest that each patient with Turner-like symptoms or Klinefelter's-like syndrome, be carefully examined for café au lait macules before the initiation of hormone replacement treatment.

  4. Autoimmune Polyglandular Syndrome Type 3 with Anorexia

    PubMed Central

    Kahara, Toshio; Wakakuri, Hitomi; Takatsuji, Juri; Motoo, Iori; Shima, Kosuke R.; Ishikura, Kazuhide; Usuda, Rika; Noda, Yatsugi

    2012-01-01

    A 71-year-old man with diabetes mellitus visited our hospital with complaints of anorexia and weight loss (12 kg/3 months). He had megaloblastic anemia, cobalamin level was low, and autoantibody to intrinsic factor was positive. He was treated with intramuscular cyanocobalamin, and he was able to consume meals. GAD autoantibody and ICA were positive, and he was diagnosed with slowly progressive type 1 diabetes mellitus (SPIDDM). Thyroid autoantibodies were positive. According to these findings, he was diagnosed with autoimmune polyglandular syndrome type 3 with SPIDDM, pernicious anemia, and Hashimoto's thyroiditis. Extended periods of cobalamin deficiency can cause serious complications such as ataxia and dementia, and these complications may not be reversible if replacement therapy with cobalamin is delayed. Although type 1 diabetes mellitus with coexisting pernicious anemia is very rare in Japan, physicians should consider the possibility of pernicious anemia when patients with diabetes mellitus have cryptogenic anorexia with the finding of significant macrocytosis (MCV > 100 fL). PMID:23304573

  5. Mechanisms of zolpidem-induced long QT syndrome: acute inhibition of recombinant hERG K+ channels and action potential prolongation in human cardiomyocytes derived from induced pluripotent stem cells

    PubMed Central

    Jehle, J; Ficker, E; Wan, X; Deschenes, I; Kisselbach, J; Wiedmann, F; Staudacher, I; Schmidt, C; Schweizer, PA; Becker, R; Katus, HA; Thomas, D

    2013-01-01

    Background and Purpose Zolpidem, a short-acting hypnotic drug prescribed to treat insomnia, has been clinically associated with acquired long QT syndrome (LQTS) and torsade de pointes (TdP) tachyarrhythmia. LQTS is primarily attributed to reduction of cardiac human ether-a-go-go-related gene (hERG)/IKr currents. We hypothesized that zolpidem prolongs the cardiac action potential through inhibition of hERG K+ channels. Experimental Approach Two-electrode voltage clamp and whole-cell patch clamp electrophysiology was used to record hERG currents from Xenopus oocytes and from HEK 293 cells. In addition, hERG protein trafficking was evaluated in HEK 293 cells by Western blot analysis, and action potential duration (APD) was assessed in human-induced pluripotent stem cell (hiPSC)-derived cardiomyocytes. Key Results Zolpidem caused acute hERG channel blockade in oocytes (IC50 = 61.5 μM) and in HEK 293 cells (IC50 = 65.5 μM). Mutation of residues Y652 and F656 attenuated hERG inhibition, suggesting drug binding to a receptor site inside the channel pore. Channels were blocked in open and inactivated states in a voltage- and frequency-independent manner. Zolpidem accelerated hERG channel inactivation but did not affect I–V relationships of steady-state activation and inactivation. In contrast to the majority of hERG inhibitors, hERG cell surface trafficking was not impaired by zolpidem. Finally, acute zolpidem exposure resulted in APD prolongation in hiPSC-derived cardiomyocytes. Conclusions and Implications Zolpidem inhibits cardiac hERG K+ channels. Despite a relatively low affinity of zolpidem to hERG channels, APD prolongation may lead to acquired LQTS and TdP in cases of reduced repolarization reserve or zolpidem overdose. PMID:23061993

  6. Cavotricuspid isthmus ablation and subcutaneous monitoring device implantation in a 2-year-old baby with 2 SCN5A mutations, sinus node dysfunction, atrial flutter recurrences, and drug induced long-QT syndrome: a tricky case of pediatric overlap syndrome?

    PubMed

    De Filippo, Paolo; Ferrari, Paola; Iascone, Maria; Racheli, Marco; Senni, Michele

    2015-03-01

    We describe the case of 2-year-old baby with compound heterozygosity for paternal and maternal alleles mutation of α-subunit of the cardiac sodium channel (SCN5A), sinus node dysfunction, atrial flutter recurrences, and drug induced long-QT syndrome. In this setting, we chose at first to perform linear ablation of cavotricuspid isthmus resulting in a bidirectional isthmus block. As a second step, we decided to implant a miniaturized loop recorder that, with a minimally invasive procedure, permits us to follow the development of the disease in order to define the future strategy. After 8 months follow-up, automatic daily loop-recorder transmissions disclose the complete absence of any arrhythmia along with asymptomatic ventricular pauses due to sinus node dysfunction. Echocardiography shows normal findings, in particular no left ventricular dysfunction. © 2014 Wiley Periodicals, Inc.

  7. Hyperglycemia and subsequent torsades de pointes with marked QT prolongation during refeeding.

    PubMed

    Nakashima, Takashi; Kubota, Tomoki; Takasugi, Nobuhiro; Kitagawa, Yuichiro; Yoshida, Takahiro; Ushikoshi, Hiroaki; Kawasaki, Masanori; Nishigaki, Kazuhiko; Ogura, Shinji; Minatoguchi, Shinya

    2017-01-01

    A fatal cardiac complication can occasionally present in malnourished patients during refeeding; this is known as refeeding syndrome. However, to our knowledge, hyperglycemia preceding torsades de pointes with QT prolongation during refeeding has not been reported. In the present study, we present a case in which hyperglycemia preceded torsades de pointes with QT prolongation during refeeding. The aim of this study was to determine the possible mechanism underlying QT prolongation during refeeding and indicate how to prevent it. A 32-y-old severely malnourished woman (body mass index 14.57 kg/m(2)) was admitted to the intensive care unit of our institution after resuscitation from cardiopulmonary arrest due to ventricular fibrillation. She was diagnosed with anorexia nervosa. Although no obvious electrolyte abnormalities were observed, her blood glucose level was 11 mg/dL. A 12-lead electrocardiogram at admission showed sinus rhythm with normal QT interval (QTc 0.448). Forty mL of 50% glucose (containing 20 g of glucose) was intravenously injected, followed by a drip infusion of glucose to maintain blood glucose level within normal range. After 9 h, the patient's blood glucose level increased to 569 mg/dL. However, after 38 h, an episode of marked QT prolongation (QTc 0.931) followed by torsades de pointes developed. Hyperglycemia during refeeding can present with QT prolongation; consequently, monitoring blood glucose levels may be useful in avoiding hyperglycemia, which can result in QT prolongation. Furthermore, additional monitoring of QT intervals using a 12-lead electrocardiogram should allow the early detection of QT prolongation when glucose solution is administered to a malnourished patient with (severe) hypoglycemia. Copyright © 2016 Elsevier Inc. All rights reserved.

  8. What Are the Types and Phases of Rett Syndrome?

    MedlinePlus

    ... are the types? What are common symptoms? How many people are affected/at risk? ... are the types & phases of Rett syndrome? Skip sharing on social media links Share this: Page Content There are two ...

  9. Waardenburg syndrome type 2: an orthodontic perspective.

    PubMed

    Şuhani, Raluca Diana; Şuhani, Mihai Flaviu; Muntean, Alexandrina; Mesaroş, Michaela Florica; Badea, Mîndra Eugenia

    2015-01-01

    Waardenburg syndrome is a rare form of neurocristopathy. It is a disorder in the development of neural crest cells, caused by an altered cellular migration during the embryonic phase. That alteration causes an association of different abnormalities such as pigmentary disturbances of the hair, iris, skin, stria vascularis of the cochlea, dystopia canthorum and sensorineural hearing loss. We report a case of a 14-year-old Romanian male, with a family history of Waardenburg syndrome (mother) and Usher syndrome (father - congenitally sensorineural hearing loss and retinal degeneration). The case particularities are: the correlation between malocclusion and Waardenburg syndrome due to hypoplastic alae nasi and also factors that produced hearing loss, which could be Waardenburg syndrome, Usher syndrome or the presence of the connexin 26 (W24X) gene mutation.

  10. Sex is a moderator of the association between NOS1AP sequence variants and QTc in two long QT syndrome founder populations: a pedigree-based measured genotype association analysis.

    PubMed

    Winbo, Annika; Stattin, Eva-Lena; Westin, Ida Maria; Norberg, Anna; Persson, Johan; Jensen, Steen M; Rydberg, Annika

    2017-07-18

    Sequence variants in the NOS1AP gene have repeatedly been reported to influence QTc, albeit with moderate effect sizes. In the long QT syndrome (LQTS), this may contribute to the substantial QTc variance seen among carriers of identical pathogenic sequence variants. Here we assess three non-coding NOS1AP sequence variants, chosen for their previously reported strong association with QTc in normal and LQTS populations, for association with QTc in two Swedish LQT1 founder populations. This study included 312 individuals (58% females) from two LQT1 founder populations, whereof 227 genotype positive segregating either Y111C (n = 148) or R518* (n = 79) pathogenic sequence variants in the KCNQ1 gene, and 85 genotype negatives. All were genotyped for NOS1AP sequence variants rs12143842, rs16847548 and rs4657139, and tested for association with QTc length (effect size presented as mean difference between derived and wildtype, in ms), using a pedigree-based measured genotype association analysis. Mean QTc was obtained by repeated manual measurement (preferably in lead II) by one observer using coded 50 mm/s standard 12-lead ECGs. A substantial variance in mean QTc was seen in genotype positives 476 ± 36 ms (Y111C 483 ± 34 ms; R518* 462 ± 34 ms) and genotype negatives 433 ± 24 ms. Female sex was significantly associated with QTc prolongation in all genotype groups (p < 0.001). In a multivariable analysis including the entire study population and adjusted for KCNQ1 genotype, sex and age, NOS1AP sequence variants rs12143842 and rs16847548 (but not rs4657139) were significantly associated with QT prolongation, +18 ms (p = 0.0007) and +17 ms (p = 0.006), respectively. Significant sex-interactions were detected for both sequent variants (interaction term r = 0.892, p < 0.001 and r = 0.944, p < 0.001, respectively). Notably, across the genotype groups, when stratified by sex neither rs12143842 nor rs16847548 were significantly associated with

  11. Meretoja's Syndrome: Lattice Corneal Dystrophy, Gelsolin Type

    PubMed Central

    Abreu, C.; Neves, M.; Oliveira, L.; Beirão, M.

    2017-01-01

    Lattice corneal dystrophy gelsolin type was first described in 1969 by Jouko Meretoja, a Finnish ophthalmologist. It is caused by an autosomal dominant mutation in gelsolin gene resulting in unstable protein fragments and amyloid deposition in various organs. The age of onset is usually after the third decade of life and typical diagnostic triad includes progressive bilateral facial paralysis, loose skin, and lattice corneal dystrophy. We report a case of a 53-year-old female patient referred to our Department of Ophthalmology by severe dry eye and incomplete eyelid closure. She had severe bilateral facial paresis, significant orbicularis, and perioral sagging as well as hypoesthesia of extremities and was diagnosed with Meretoja's syndrome at the age of 50, confirmed by the presence of gelsolin mutation. At our observation she had bilateral diminished tear film break-up time and Schirmer test, diffuse keratitis, corneal opacification, and neovascularization in the left eye. She was treated with preservative-free lubricants and topical cyclosporine, associated with nocturnal complete occlusion of both eyes, and underwent placement of lacrimal punctal plugs. Ocular symptoms are the first to appear and our role as ophthalmologists is essential for the diagnosis, treatment, and monitoring of ocular alterations in these patients. PMID:28250773

  12. Neurofibromatosis type 1 associated with moyamoya syndrome in children.

    PubMed

    Duat-Rodríguez, Anna; Carceller Lechón, Fernando; López Pino, Miguel Ángel; Rodríguez Fernández, Cristina; González-Gutiérrez-Solana, Luis

    2014-01-01

    Vascular abnormalities in neurofibromatosis type 1 may arise anywhere in the cardiovascular system, and cerebrovascular involvement is the predominant feature of moyamoya syndrome. Because neurofibromatosis type 1 is a neurocutaneous disorder and routine follow-up with cranial MRI is not standard practice in asymptomatic children, accurate epidemiologic data are lacking. On follow-up, clinical and radiologic progression is often found in patients with moyamoya syndrome. We performed a retrospective analysis on children with neurofibromatosis type 1 who had been diagnosed with moyamoya syndrome on cranial MRI. Of the 197 children diagnosed with neurofibromatosis type 1, 168 had undergone a cranial MRI, and four (2.3%) of them had moyamoya syndrome. At diagnosis, one child had headache and vomiting related to a right frontal hematoma and the other three children were asymptomatic, including one child with a previous history of renal arteriopathy. In two children moyamoya syndrome was unilateral. The association between moyamoya syndrome and neurofibromatosis type 1 is rare, but it poses a potential risk of clinicoradiologic progression. Targeted monitoring of children with neurofibromatosis type 1 ensures an early diagnosis of moyamoya syndrome. Copyright © 2014 Elsevier Inc. All rights reserved.

  13. Genome-wide Association Study of Susceptibility to Particulate Matter-Associated QT Prolongation.

    PubMed

    Gondalia, Rahul; Avery, Christy L; Napier, Melanie D; Méndez-Giráldez, Raúl; Stewart, James D; Sitlani, Colleen M; Li, Yun; Wilhelmsen, Kirk C; Duan, Qing; Roach, Jeffrey; North, Kari E; Reiner, Alexander P; Zhang, Zhu-Ming; Tinker, Lesley F; Yanosky, Jeff D; Liao, Duanping; Whitsel, Eric A

    2017-06-08

    Ambient particulate matter (PM) air pollution exposure has been associated with increases in QT interval duration (QT). However, innate susceptibility to PM-associated QT prolongation has not been characterized. To characterize genetic susceptibility to PM-associated QT prolongation in a multi-racial/ethnic, genome-wide association study (GWAS). Using repeated electrocardiograms (1986-2004), longitudinal data on in diameter (), and generalized estimating equations methods adapted for low-prevalence exposure, we estimated approximately interactions among nine Women's Health Initiative clinical trials and Atherosclerosis Risk in Communities Study subpopulations (), then combined subpopulation-specific results in a fixed-effects, inverse variance-weighted meta-analysis. A common variant (rs1619661; coded allele: T) significantly modified the association (). At concentrations percentile, QT increased 7 ms across the CC and TT genotypes: 397 (95% confidence interval: 396, 399) to 404 (403, 404) ms. However, QT changed minimally across rs1619661 genotypes at lower concentrations. The rs1619661 variant is on chromosome 10, 132 kilobase (kb) downstream from CXCL12, which encodes a chemokine, stromal cell-derived factor 1, that is expressed in cardiomyocytes and decreases calcium influx across the L-type channel. The findings suggest that biologically plausible genetic factors may alter susceptibility to -associated QT prolongation in populations protected by the U.S. Environmental Protection Agency's National Ambient Air Quality Standards. Independent replication and functional characterization are necessary to validate our findings. https://doi.org/10.1289/EHP347.

  14. Genetic association study of QT interval highlights role for calcium signaling pathways in myocardial repolarization.

    PubMed

    Arking, Dan E; Pulit, Sara L; Crotti, Lia; van der Harst, Pim; Munroe, Patricia B; Koopmann, Tamara T; Sotoodehnia, Nona; Rossin, Elizabeth J; Morley, Michael; Wang, Xinchen; Johnson, Andrew D; Lundby, Alicia; Gudbjartsson, Daníel F; Noseworthy, Peter A; Eijgelsheim, Mark; Bradford, Yuki; Tarasov, Kirill V; Dörr, Marcus; Müller-Nurasyid, Martina; Lahtinen, Annukka M; Nolte, Ilja M; Smith, Albert Vernon; Bis, Joshua C; Isaacs, Aaron; Newhouse, Stephen J; Evans, Daniel S; Post, Wendy S; Waggott, Daryl; Lyytikäinen, Leo-Pekka; Hicks, Andrew A; Eisele, Lewin; Ellinghaus, David; Hayward, Caroline; Navarro, Pau; Ulivi, Sheila; Tanaka, Toshiko; Tester, David J; Chatel, Stéphanie; Gustafsson, Stefan; Kumari, Meena; Morris, Richard W; Naluai, Åsa T; Padmanabhan, Sandosh; Kluttig, Alexander; Strohmer, Bernhard; Panayiotou, Andrie G; Torres, Maria; Knoflach, Michael; Hubacek, Jaroslav A; Slowikowski, Kamil; Raychaudhuri, Soumya; Kumar, Runjun D; Harris, Tamara B; Launer, Lenore J; Shuldiner, Alan R; Alonso, Alvaro; Bader, Joel S; Ehret, Georg; Huang, Hailiang; Kao, W H Linda; Strait, James B; Macfarlane, Peter W; Brown, Morris; Caulfield, Mark J; Samani, Nilesh J; Kronenberg, Florian; Willeit, Johann; Smith, J Gustav; Greiser, Karin H; Meyer Zu Schwabedissen, Henriette; Werdan, Karl; Carella, Massimo; Zelante, Leopoldo; Heckbert, Susan R; Psaty, Bruce M; Rotter, Jerome I; Kolcic, Ivana; Polašek, Ozren; Wright, Alan F; Griffin, Maura; Daly, Mark J; Arnar, David O; Hólm, Hilma; Thorsteinsdottir, Unnur; Denny, Joshua C; Roden, Dan M; Zuvich, Rebecca L; Emilsson, Valur; Plump, Andrew S; Larson, Martin G; O'Donnell, Christopher J; Yin, Xiaoyan; Bobbo, Marco; D'Adamo, Adamo P; Iorio, Annamaria; Sinagra, Gianfranco; Carracedo, Angel; Cummings, Steven R; Nalls, Michael A; Jula, Antti; Kontula, Kimmo K; Marjamaa, Annukka; Oikarinen, Lasse; Perola, Markus; Porthan, Kimmo; Erbel, Raimund; Hoffmann, Per; Jöckel, Karl-Heinz; Kälsch, Hagen; Nöthen, Markus M; den Hoed, Marcel; Loos, Ruth J F; Thelle, Dag S; Gieger, Christian; Meitinger, Thomas; Perz, Siegfried; Peters, Annette; Prucha, Hanna; Sinner, Moritz F; Waldenberger, Melanie; de Boer, Rudolf A; Franke, Lude; van der Vleuten, Pieter A; Beckmann, Britt Maria; Martens, Eimo; Bardai, Abdennasser; Hofman, Nynke; Wilde, Arthur A M; Behr, Elijah R; Dalageorgou, Chrysoula; Giudicessi, John R; Medeiros-Domingo, Argelia; Barc, Julien; Kyndt, Florence; Probst, Vincent; Ghidoni, Alice; Insolia, Roberto; Hamilton, Robert M; Scherer, Stephen W; Brandimarto, Jeffrey; Margulies, Kenneth; Moravec, Christine E; del Greco M, Fabiola; Fuchsberger, Christian; O'Connell, Jeffrey R; Lee, Wai K; Watt, Graham C M; Campbell, Harry; Wild, Sarah H; El Mokhtari, Nour E; Frey, Norbert; Asselbergs, Folkert W; Mateo Leach, Irene; Navis, Gerjan; van den Berg, Maarten P; van Veldhuisen, Dirk J; Kellis, Manolis; Krijthe, Bouwe P; Franco, Oscar H; Hofman, Albert; Kors, Jan A; Uitterlinden, André G; Witteman, Jacqueline C M; Kedenko, Lyudmyla; Lamina, Claudia; Oostra, Ben A; Abecasis, Gonçalo R; Lakatta, Edward G; Mulas, Antonella; Orrú, Marco; Schlessinger, David; Uda, Manuela; Markus, Marcello R P; Völker, Uwe; Snieder, Harold; Spector, Timothy D; Ärnlöv, Johan; Lind, Lars; Sundström, Johan; Syvänen, Ann-Christine; Kivimaki, Mika; Kähönen, Mika; Mononen, Nina; Raitakari, Olli T; Viikari, Jorma S; Adamkova, Vera; Kiechl, Stefan; Brion, Maria; Nicolaides, Andrew N; Paulweber, Bernhard; Haerting, Johannes; Dominiczak, Anna F; Nyberg, Fredrik; Whincup, Peter H; Hingorani, Aroon D; Schott, Jean-Jacques; Bezzina, Connie R; Ingelsson, Erik; Ferrucci, Luigi; Gasparini, Paolo; Wilson, James F; Rudan, Igor; Franke, Andre; Mühleisen, Thomas W; Pramstaller, Peter P; Lehtimäki, Terho J; Paterson, Andrew D; Parsa, Afshin; Liu, Yongmei; van Duijn, Cornelia M; Siscovick, David S; Gudnason, Vilmundur; Jamshidi, Yalda; Salomaa, Veikko; Felix, Stephan B; Sanna, Serena; Ritchie, Marylyn D; Stricker, Bruno H; Stefansson, Kari; Boyer, Laurie A; Cappola, Thomas P; Olsen, Jesper V; Lage, Kasper; Schwartz, Peter J; Kääb, Stefan; Chakravarti, Aravinda; Ackerman, Michael J; Pfeufer, Arne; de Bakker, Paul I W; Newton-Cheh, Christopher

    2014-08-01

    The QT interval, an electrocardiographic measure reflecting myocardial repolarization, is a heritable trait. QT prolongation is a risk factor for ventricular arrhythmias and sudden cardiac death (SCD) and could indicate the presence of the potentially lethal mendelian long-QT syndrome (LQTS). Using a genome-wide association and replication study in up to 100,000 individuals, we identified 35 common variant loci associated with QT interval that collectively explain ∼8-10% of QT-interval variation and highlight the importance of calcium regulation in myocardial repolarization. Rare variant analysis of 6 new QT interval-associated loci in 298 unrelated probands with LQTS identified coding variants not found in controls but of uncertain causality and therefore requiring validation. Several newly identified loci encode proteins that physically interact with other recognized repolarization proteins. Our integration of common variant association, expression and orthogonal protein-protein interaction screens provides new insights into cardiac electrophysiology and identifies new candidate genes for ventricular arrhythmias, LQTS and SCD.

  15. Oro-facial-digital syndrome type II with otolaryngological manifestations.

    PubMed

    Havle, A; Shedge, S; Malashetti, S; Jain, V

    2015-01-01

    We present a case of oro-facial-digital syndrome type II (Mohr's syndrome) which is characterized by malformations of the oral cavity, face and digits. The facial and oral features include tongue nodules, cleft or high-arched palate, missing teeth, broad nose; cleft lip. The digital features include clinodactyly, polydactyly, syndactyly, brachydactyly and duplication of the hallux.

  16. Cholesterol and Alzheimer Type Dementia among Adults with Down Syndrome

    ERIC Educational Resources Information Center

    Buckley, Frank

    2008-01-01

    This article reports a summary of research by Warren Zigman and colleagues investigating the link between cholesterol levels and Alzheimer type dementia among adults with Down syndrome. Warren Zigman and colleagues followed 123 adults with Down syndrome between May 1998 and April 2006. The participants were aged between 41 and 78 years at the…

  17. Cholesterol and Alzheimer Type Dementia among Adults with Down Syndrome

    ERIC Educational Resources Information Center

    Buckley, Frank

    2008-01-01

    This article reports a summary of research by Warren Zigman and colleagues investigating the link between cholesterol levels and Alzheimer type dementia among adults with Down syndrome. Warren Zigman and colleagues followed 123 adults with Down syndrome between May 1998 and April 2006. The participants were aged between 41 and 78 years at the…

  18. Intestinal malrotation in a patient with Pfeiffer syndrome type 2.

    PubMed

    Zarate, Yuri A; Putnam, Philip E; Saal, Howard M

    2010-11-01

    Pfeiffer syndrome is a pleiotropic disorder characterized by multiple suture craniosynostosis, broad and medially deviated thumbs and great toes, and variable cutaneous syndactyly. We present the case of a 16-month-old boy with Pfeiffer syndrome type 2 who presented with intestinal malrotation for which the diagnosis was delayed. This is a rare complication of Pfeiffer syndrome, with few reported cases in the literature. This case illustrates the importance of recognizing gastrointestinal malrotation as a possible cause of feeding intolerance and persistent vomiting in patients with the severe forms of Pfeiffer syndrome.

  19. Sudden cardiac arrest during anesthesia in a 30-month-old boy with syndactyly: a case of genetically proven Timothy syndrome.

    PubMed

    An, Hyo Soon; Choi, Eun Young; Kwon, Bo Sang; Kim, Gi Beom; Bae, Eun Jung; Noh, Chung Il; Choi, Jung Yun; Park, Sung Sup

    2013-05-01

    Timothy syndrome, long QT syndrome type 8, is highly malignant with ventricular tachyarrhythmia. A 30-month-old boy had sudden cardiac arrest during anesthesia induction before plastic surgery for bilateral cutaneous syndactyly. After successful resuscitation, prolonged QT interval (QTc, 0.58-0.60 sec) and T-wave alternans were found in his electrocardiogram. Starting β-blocker to prevent further tachycardia and collapse event, then there were no more arrhythmic events. The genes KCNQ1, KCNH2, KCNE1 and 2, and SCN5A were negative for long QT syndrome. The mutation p.Gly406Arg was confirmed in CACNA1C, which maintains L-type calcium channel depolarization in the heart and other systems.

  20. Reckless administration of QT interval-prolonging agents in elderly patients with drug-induced torsade de pointes.

    PubMed

    Jackobson, Galia; Carmel, Narin Nard; Lotan, Dor; Kremer, Anjelika; Justo, Dan

    2016-11-22

    A systematic review was conducted for all published case reports on drug-induced torsade de pointes (TdP) in elderly (≥80 years) patients to study if the administration of the offending agent was reckless. Overall, 61 reports on drug-induced TdP in patients aged 80-97 years were included in the analysis. Non-modifiable risk factors for drug-induced TdP (e.g. acute coronary syndrome, female gender and congestive heart failure), modifiable risk factors (e.g. hypokalemia, severe hypomagnesemia and digitalis toxicity) and reckless administration of a QT interval-prolonging agent (e.g. despite a known QT interval prolongation or a history of TdP, together with other QT interval prolonging agents in higher than recommended doses) were recorded in each case. Overall, 54 (88.5%) patients had non-modifiable risk factors for drug-induced TdP and 21 (34.4%) patients had modifiable risk factors. The administration of the offending agent was reckless in one half (n = 31; 50.8%) of the patients. The most prevalent reckless administration of a QT interval-prolonging agent was together with other QT interval-prolonging agents (n = 16; 51.6%) or despite QT interval prolongation (n = 8; 25.8%). In conclusion, although risk factors for drug-induced TdP are prevalent in elderly patients with drug-induced TdP, in approximately 50% of patients it appeared following a reckless administration of a QT interval-prolonging agent. In this population physicians should particularly avoid administration of two or more QT interval-prolonging agents simultaneously or administration of a QT interval-prolonging agent despite QT interval prolongation.

  1. Type 2 diabetes mellitus: An unusual association with Down's syndrome

    PubMed Central

    Kota, Sunil Kumar; Tripathy, Prabhas Ranjan; Kota, Siva Krishna; Jammula, Sruti

    2013-01-01

    Down's syndrome (DS) is known to be associated with autoimmune disease including type 1 diabetes. To the best of our knowledge, there are no reports of DS with type 2 diabetes mellitus in the literature. We hereby report two cases of DS with type 2 diabetes. PMID:24339554

  2. Type 2 diabetes mellitus: An unusual association with Down's syndrome.

    PubMed

    Kota, Sunil Kumar; Tripathy, Prabhas Ranjan; Kota, Siva Krishna; Jammula, Sruti

    2013-07-01

    Down's syndrome (DS) is known to be associated with autoimmune disease including type 1 diabetes. To the best of our knowledge, there are no reports of DS with type 2 diabetes mellitus in the literature. We hereby report two cases of DS with type 2 diabetes.

  3. Gait Strategy in Patients with Ehlers-Danlos Syndrome Hypermobility Type and Down Syndrome

    ERIC Educational Resources Information Center

    Rigoldi, Chiara; Galli, Manuela; Cimolin, Veronica; Camerota, Filippo; Celletti, Claudia; Tenore, Nunzio; Albertini, Giorgio

    2012-01-01

    People suffering from Ehlers-Danlos syndrome (EDS) hypermobility type present a severe ligament laxity that results in difficulties in muscle force transmission. The same condition is present in people suffering from Down syndrome (DS) even if their clumsy movements are due to cerebral and cognitive impairments. The aim of this study was to…

  4. Sturge-Weber syndrome in association with Klippel-Trenaunay syndrome and phakomatosis pigmentovascularis type IIb.

    PubMed

    Mandal, Rajesh Kumar; Ghosh, Sudip Kumar; Koley, Sankha; Roy, Asit Chandra

    2014-01-01

    Phakomatosis pigmentovascularis (PPV) is a rare combination of pigmentary and vascular components with or without systemic involvement. We report here a rare association of Sturge-Weber syndrome, Klippel-Trenaunay syndrome, and PPV type IIb in a 15-year-old boy who had right upper limb monoparesis along with a history of recurrent convulsions.

  5. Gait Strategy in Patients with Ehlers-Danlos Syndrome Hypermobility Type and Down Syndrome

    ERIC Educational Resources Information Center

    Rigoldi, Chiara; Galli, Manuela; Cimolin, Veronica; Camerota, Filippo; Celletti, Claudia; Tenore, Nunzio; Albertini, Giorgio

    2012-01-01

    People suffering from Ehlers-Danlos syndrome (EDS) hypermobility type present a severe ligament laxity that results in difficulties in muscle force transmission. The same condition is present in people suffering from Down syndrome (DS) even if their clumsy movements are due to cerebral and cognitive impairments. The aim of this study was to…

  6. QT Dispersion after Thrombolytic Therapy

    PubMed Central

    Oni Heris, Saeed; Rahimi, Behzad; Faridaalaee, Gholamreza; Hajahmadi, Mojgan; Sayyadi, Hojjat; Naghipour, Bahman

    2014-01-01

    Background: QT dispersion (QTd) is equal to longer QTc minus shorter QTc measured by 12-lead electrocardiogram (ECG). QTd reflects inhomogeneity in repolarization of ventricular myocardium and because of easy and fast measurement of QTd, it can be used to predict high-risk patients for dysrhythmia after Acute Myocardial Infarction (AMI). Objectives: This study aimed to assess the effect of thrombolytic therapy on QTd before and 1 hour and 4 days after beginning of thrombolytic therapy. Patients and Methods: The patients with chest pain and ST Elevated Myocardial Infarction (STEMI) that underwent thrombolytic therapy were enrolled into this study. Streptokinase was the thrombolytic agent in all the patients. Standard 12-lead (ECG) was evaluated before beginning of thrombolytic therapy (QTd 1) and 1 hour (QTd2) and 4 days (QTd3) after thrombolytic therapy. First, ECG was magnified × 10 for exact calculation of QT and QTd. After all, the variables were compared using one–way analysis of variance (ANOVA). Besides, P ≤ 0.05 was considered as statistically significant. Results: This study was conducted on 160 patients. The results revealed no significant differences among QTd 1, QTd 2, and QTd 3 (P > 0.05). At inferior AMI, however, a significant difference was observed among QTd1, QTd2, and QTd3 (P = 0.031). Conclusions: Thrombolytic therapy had no significant effects on QTd. Thus, thrombolytic therapy does not increase the risk of arrhythmia. PMID:25614860

  7. The risk for type B aortic dissection in Marfan syndrome.

    PubMed

    den Hartog, Alexander W; Franken, Romy; Zwinderman, Aeilko H; Timmermans, Janneke; Scholte, Arthur J; van den Berg, Maarten P; de Waard, Vivian; Pals, Gerard; Mulder, Barbara J M; Groenink, Maarten

    2015-01-27

    Aortic dissections involving the descending aorta are a major clinical problem in patients with Marfan syndrome. The purpose of this study was to identify clinical parameters associated with type B aortic dissection and to develop a risk model to predict type B aortic dissection in patients with Marfan syndrome. Patients with the diagnosis of Marfan syndrome and magnetic resonance imaging or computed tomographic imaging of the aorta were followed for a median of 6 years for the occurrence of type B dissection or the combined end point of type B aortic dissection, distal aortic surgery, and death. A model using various clinical parameters as well as genotyping was developed to predict the risk for type B dissection in patients with Marfan syndrome. Between 1998 and 2013, 54 type B aortic dissections occurred in 600 patients with Marfan syndrome (mean age 36 ± 14 years, 52% male). Independent variables associated with type B aortic dissection were prior prophylactic aortic surgery (hazard ratio: 2.1; 95% confidence interval: 1.2 to 3.8; p = 0.010) and a proximal descending aorta diameter ≥27 mm (hazard ratio: 2.2; 95% confidence interval: 1.1 to 4.3; p = 0.020). In the risk model, the 10-year occurrence of type B aortic dissection in low-, moderate-, and high-risk patients was 6%, 19%, and 34%, respectively. Angiotensin II receptor blocker therapy was associated with fewer type B aortic dissections (hazard ratio: 0.3; 95% confidence interval: 0.1 to 0.9; p = 0.030). Patients with Marfan syndrome with prior prophylactic aortic surgery are at substantial risk for type B aortic dissection, even when the descending aorta is only slightly dilated. Angiotensin II receptor blocker therapy may be protective in the prevention of type B aortic dissections. Copyright © 2015 American College of Cardiology Foundation. Published by Elsevier Inc. All rights reserved.

  8. Drug induced QT prolongation: the measurement and assessment of the QT interval in clinical practice

    PubMed Central

    Isbister, Geoffrey K; Page, Colin B

    2013-01-01

    There has been an increasing focus on drug induced QT prolongation including research on drug development and QT prolongation, following the removal of drugs due to torsades de pointes (TdP). Although this has improved our understanding of drug-induced QT prolongation there has been much less research aimed at helping clinicians assess risk in individual patients with drug induced QT prolongation. This review will focus on assessment of drug-induced QT prolongation in clinical practice using a simple risk assessment approach. Accurate measurement of the QT interval is best done manually, and not using the measurement of standard ECG machines. Correction for heart rate (HR) using correction formulae such as Bazett's is often inaccurate. These formulae underestimate and overestimate the duration of cardiac repolarization at low and high heart rates, respectively. Numerous cut-offs have been suggested as an indicator of an abnormal QT, but are problematic in clinical practice. An alternative approach is the QT nomogram which is a plot of QT vs. HR. The nomogram has an ‘at risk’ line and QT-HR pairs above this line have been shown in a systematic study to be associated with TdP and the line is more sensitive and specific than Bazett's QTc of 440 ms or 500 ms. Plotting the QT-HR pair for patients on drugs suspected or known to cause QT prolongation allows assessment of the QT interval based on normal population QT variability. This risk assessment then allows the safer commencement of drugs therapeutically or management of drug induced effects in overdose. PMID:23167578

  9. Drug induced QT prolongation: the measurement and assessment of the QT interval in clinical practice.

    PubMed

    Isbister, Geoffrey K; Page, Colin B

    2013-07-01

    There has been an increasing focus on drug induced QT prolongation including research on drug development and QT prolongation, following the removal of drugs due to torsades de pointes (TdP). Although this has improved our understanding of drug-induced QT prolongation there has been much less research aimed at helping clinicians assess risk in individual patients with drug induced QT prolongation. This review will focus on assessment of drug-induced QT prolongation in clinical practice using a simple risk assessment approach. Accurate measurement of the QT interval is best done manually, and not using the measurement of standard ECG machines. Correction for heart rate (HR) using correction formulae such as Bazett's is often inaccurate. These formulae underestimate and overestimate the duration of cardiac repolarization at low and high heart rates, respectively. Numerous cut-offs have been suggested as an indicator of an abnormal QT, but are problematic in clinical practice. An alternative approach is the QT nomogram which is a plot of QT vs. HR. The nomogram has an 'at risk' line and QT-HR pairs above this line have been shown in a systematic study to be associated with TdP and the line is more sensitive and specific than Bazett's QTc of 440 ms or 500 ms. Plotting the QT-HR pair for patients on drugs suspected or known to cause QT prolongation allows assessment of the QT interval based on normal population QT variability. This risk assessment then allows the safer commencement of drugs therapeutically or management of drug induced effects in overdose. © 2012 The Authors. British Journal of Clinical Pharmacology © 2012 The British Pharmacological Society.

  10. Secondly ECG recordings in the emergency room revealed Garenoxacin-induced abnormal QT interval prolongation in a patient with multiple syncopal attacks.

    PubMed

    Tagawa, Minoru; Ochiai, Sachie; Nakamura, Yuichi; Sato, Akinori; Chinushi, Masaomi

    2016-07-01

    A 73-year-old woman first visited our emergency room with multiple syncopal attacks. Before admission, she had received an antibiotic (Garenoxacin) for 3 days from a local clinic. First electrocardiogram (ECG) showed no ST-segment deviation but mild QT interval prolongation with a positive U wave. Second ECG recording 3 h later showed slightly slower heart rate and revealed marked QTU interval prolongation suggesting the cause of her syncopal attacks. After cessation of Garenoxacin, the QTU interval prolongation shortened. However, both epinephrine infusion and treadmill exercise test reproduced similar QTU interval prolongation and T wave deformities. Later, genetic analysis demonstrated that this patient had a mutation in KCNH2 gene, and she was diagnosed as a type-2 long-QT syndrome which was accentuated by use of garenoxacin. At the emergency out-patient clinic, repetitive ECG recordings can be useful and should be considered in order to identify the cause of syncopal attacks in patients who were prescribed antibiotics and had mild QT interval abnormalities.

  11. Type I interferons in Sjögren's syndrome.

    PubMed

    Yao, Yihong; Liu, Zheng; Jallal, Bahija; Shen, Nan; Rönnblom, Lars

    2013-03-01

    Sjögren's syndrome is a chronic autoimmune disease characterized by lymphocytic infiltration of the salivary and lachrymal glands resulting in dry eyes and mouth. Genetic predisposition, pathogenic infections and hormones have been implicated in the pathogenesis of the disease. Studies in the last several years have revealed marked over-expression of the type I interferon (IFN)-inducible genes in the peripheral blood and salivary glands of patients with Sjögren's syndrome. The expression of the type I IFN-inducible genes in Sjögren's syndrome also positively correlates to titers of anti-Ro and anti-La autoantibodies, which are typical for this disease. Plasmacytoid dendritic cells (pDC) are the major source of type I IFN production and activated pDC are detected in minor salivary gland biopsies from patients with primary Sjögren's syndrome. In addition, polymorphisms in genes important both for the production and response to type I IFN are associated to increased risk for Sjögren's syndrome. Because type I IFN bears a variety of biological functions, such as defense against viral infections and activation of the immune system, these results suggest that the type I IFN system has an important role in the pathogenesis of Sjögren's syndrome. A variety of mechanisms causing an activation of the type I IFN system are discussed in this review. Given the pivotal role of type I IFN in the disease process, therapeutic interventions targeting the type I IFN signaling pathway have the potential to benefit the patients with elevated type I IFN status and such hypothesis needs to be carefully evaluated in clinical development.

  12. How Is Long QT Syndrome Treated?

    MedlinePlus

    ... cholesterol , depression, and arrhythmias . Take medicines such as beta-blockers, which reduce the risk of symptoms by slowing ... as bananas) or taking potassium supplements daily. Medicines Beta blockers are medicines that prevent the heart from beating ...

  13. Outlet type of interventricular septal defect in SanFilippo type-B syndrome.

    PubMed

    Kourouklis, S; Chatzis, D; Skafida, M; Liagkas, K; Paradellis, G; Kyriakides, Z

    2007-11-15

    Mucopolysaccharidoses (MPS) are a heterogeneous group of lysosomal storage disorders, due to deficiency of glycosaminoglycans breakdown enzymes. MPS type III is also known as SanFilippo syndrome, which is further subdivided into four distinct forms--A, B, C and D--caused by different enzyme deficiencies, but with similar clinical characteristics. Cardiac involvement in SanFilippo syndrome is less common compared with the other MPS types. In our case report, outlet type of interventricular septal defect was echocardiographically diagnosed in a fifteen year-old boy with known history of SanFilippo type-B syndrome, which, to our knowledge, has not yet been reported.

  14. Oral Contraceptive Use and the ECG: Evidence of an Adverse QT Effect on Corrected QT Interval

    PubMed Central

    Sedlak, Tara; Shufelt, Chrisandra; Iribarren, Carlos; Lyon, Liisa L; Merz, C. Noel Bairey

    2013-01-01

    Background A prolonged corrected QT (QTc) interval is a marker for an increased risk of sudden cardiac death. We evaluated the relationship between oral contraceptive (OC) use, type of OC, and QTc interval. Methods We identified 410,782 ECGs performed at Northern California Kaiser Permanente on female patients between 15–53 years from January, 1995 to June, 2008. QT was corrected for heart rate using log-linear regression. OC generation (first, second and third) was classified by increasing progestin androgenic potency, while the fourth generation was classified as anti-androgenic. Results Among 410,782 women, 8.4% were on OC. In multivariate analysis after correction for comorbidities, there was an independent shortening effect of OCs overall (slope = −0.5ms; SE = 0.12, p<0.0002). Users of first and second generation progestins had a significantly shorter QTc than non-users (p<0.0001), while users of fourth generation had a significantly longer QTc than non-users (slope = 3.6ms, SE = 0.35, p<0.0001). Conclusion Overall, OC use has a shortening effect on the QTc. Shorter QTc is seen with first and second generation OC while fourth generation OC use has a lengthening effect on the QTc. Careful examination of adverse event rates in fourth generation OC users is needed. PMID:23879279

  15. [Types of dislipidemia in children with metabolic syndrome].

    PubMed

    Hromnats'ka, N M

    2014-01-01

    To study dyslipidemia types in children with metabolic syndrome. From 1520 children of total population 155 children aged from 9 to 18 years were selected, who formed 2 groups: 1 group--85 children with metabolic syndrome, 2 group--54 children with normal body mass. Anthropometry, blood pressure measurement, estimation of total cholesterol, low density cholesterol, very low density cholesterol, high density cholesterol, tryglicerides in blood were done. The total cholesterol level was 1,1 times higher (p = 0.001), low density cholesterol 1,4 times higher (p = 0.001), very low density cholesterol 1,1 times higher (p= 0.015), tryglicerides 1,1 times higher (p = 0.020) in children with metabolic syndrome than in children of control group. In children with metabolic syndrome sensitively more often IIa, IV dislipidemia types and isolated hypercholesterolemia and less often IIb, III dislipidemia types and high density cholesterol isolated decrease were diagnosed. So children with metabolic syndrome were characterized by atherogenic types of dislipidemias which determine early atherosclerosis development. Children with metabolic syndrome must be examined on the lipid metabolism violation with the aim of its prevention and correction.

  16. Model averaging for robust assessment of QT prolongation by concentration-response analysis.

    PubMed

    Dosne, A G; Bergstrand, M; Karlsson, M O; Renard, D; Heimann, G

    2017-07-13

    Assessing the QT prolongation potential of a drug is typically done based on pivotal safety studies called thorough QT studies. Model-based estimation of the drug-induced QT prolongation at the estimated mean maximum drug concentration could increase efficiency over the currently used intersection-union test. However, robustness against model misspecification needs to be guaranteed in pivotal settings. The objective of this work was to develop an efficient, fully prespecified model-based inference method for thorough QT studies, which controls the type I error and provides satisfactory test power. This is achieved by model averaging: The proposed estimator of the concentration-response relationship is a weighted average of a parametric (linear) and a nonparametric (monotonic I-splines) estimator, with weights based on mean integrated square error. The desired properties of the method were confirmed in an extensive simulation study, which demonstrated that the proposed method controlled the type I error adequately, and that its power was higher than the power of the nonparametric method alone. The method can be extended from thorough QT studies to the analysis of QT data from pooled phase I studies. Copyright © 2017 John Wiley & Sons, Ltd.

  17. Natal molars in Pfeiffer syndrome type 3: a case report.

    PubMed

    Alvarez, M P; Crespi, P V; Shanske, A L

    1993-01-01

    The following report is the first documented case of natal teeth associated with a recently described new entity, Pfeiffer syndrome type 3. The clinical manifestations consistent with the spectrum of this rare disorder are described with an emphasis on the concomitant natal teeth. Pfeiffer syndrome type 3 is one of the craniosynostosis syndromes and has been described in only two patients to date. Both mandibular incisors and maxillary molar natal teeth were found. Natal teeth are teeth, which are present in the oral cavity at birth. They are often associated with developmental abnormalities and recognized syndromes. Their incidence ranges from 1 in 2,000 to 3,500 births. The natal teeth found in this infant included both the mandibular primary incisors and maxillary primary first molars bilaterally. The clinical and histological considerations of natal teeth and their management are discussed. The presence of multiple natal teeth is extremely rare.

  18. Burning mouth syndrome due to herpes simplex virus type 1.

    PubMed

    Nagel, Maria A; Choe, Alexander; Traktinskiy, Igor; Gilden, Don

    2015-04-01

    Burning mouth syndrome is characterised by chronic orofacial burning pain. No dental or medical cause has been found. We present a case of burning mouth syndrome of 6 months duration in a healthy 65-year-old woman, which was associated with high copy numbers of herpes simplex virus type 1 (HSV-1) DNA in the saliva. Her pain resolved completely after antiviral treatment with a corresponding absence of salivary HSV-1 DNA 4 weeks and 6 months later.

  19. The analysis of QT interval and repolarization morphology of the heart in chronic exposure to lead.

    PubMed

    Kiełtucki, J; Dobrakowski, M; Pawlas, N; Średniawa, B; Boroń, M; Kasperczyk, S

    2017-10-01

    There are no common recommendations regarding electrocardiographic monitoring in occupationally exposed workers. Therefore, the present study was designed to investigate whether exposure to lead results in an increase of selected electrocardiography (ECG) pathologies, such as QT interval prolongation and repolarization disorders, in occupationally exposed workers. The study group included 180 workers occupationally exposed to lead compounds. The exposed group was divided according to the median of the mean blood lead level (PbBmean) calculated based on a series of measurements performed during 5-year observation period (35 µg/dl) into two subgroups: low exposure (LE, PbBmean = 20.0-35.0 µg/dl) and high exposure (HE, PbBmean = 35.1-46.4 µg/dl). The control group consisted of 69 healthy workers without occupational exposure to lead. ECG evaluation included the analysis of heart rate (HR), QT interval and repolarization abnormalities. Mean QT interval was significantly greater in the exposed population than in the control group by 2%. In the HE group, mean QT interval was significantly greater than in the control group by 4% and significantly different from those noted in the LE group. Positive correlations between QT interval and lead exposure indices were also reported. Besides, there was a negative correlation between HR and blood lead level. Increased concentration of lead in the blood above 35 μg/dl is associated with the QT interval prolongation, which may trigger arrhythmias when combined with other abnormalities, such as long QT syndrome. Therefore, electrocardiographic evaluation should be a part of a routine monitoring of occupationally exposed populations.

  20. QT Prolongation and Life Threatening Ventricular Tachycardia in a Patient Injected With Intravenous Meperidine (Demerol®).

    PubMed

    Song, Mi Kyoung; Bae, Eun Jung; Baek, Jae Suk; Kwon, Bo Sang; Kim, Gi Beom; Noh, Chung Il; Choi, Jung Yun; Park, Sung Sup

    2011-06-01

    QT prolongation is a serious adverse drug effect, which is associated with an increased risk of Torsade de pointes and sudden death. Many drugs, including both cardiac and non-cardiac drugs, have been reported to cause prolongation of QT interval. Although meperidine has not been considered proarrhythmic, we present a unique case of a 16-year-old boy without an underlying cardiac disease, who developed polymorphic ventricular tachycardia, ventricular fibrillation and QT prolongation after an intravenous meperidine injection. He had no mutation in long QT syndrome genes (KCNQ1, KCNH2, and SCN5A), but single nucleotide polymorphisms were reported, including H558R in SCNA5A and K897T in KCNH2.

  1. [Coexistence of autoimmune polyglandular syndrome type 3 with diabetes insipidus].

    PubMed

    Krysiak, Robert; Okopień, Bogusław

    2015-01-01

    Autoimmune polyglandular syndromes are conditions characterized by the combination of two or more organ-specific disorders. The underestimation oftheir real frequency probable results from physicians' inadequate knowledge of these clinical entities and sometimes their atypical clinical presentation. Because they comprise a wide spectrum of autoimmune disorders, autoimmune polyglandular syndromes are divided into four types, among which type-3 is the most common one. In this article, we report the case of a young female, initially diagnosed with diabetes mellitus who several years later developed full-blown autoimmune polyglandular syndrome type 3 consisting of autoimmune thyroid disorder and latent autoimmune diabetes in adults.The discussed case suggests that in selected patients diabetes insipidus may coexist with autoimmune endocrinopathies and nonendocrine autoimmunopathies, as well as that in some patients idiopathic diabetes insipidus may be secondary to lymphocytic infiltration and destruction of the hypothalamic supraoptic and paraventricular nuclei and/or the supraoptic-hypophyseal tract

  2. Type 2 leprosy reaction with Sweet's syndrome-like presentation*

    PubMed Central

    Chiaratti, Francielle Chiavelli; Daxbacher, Egon Luiz Rodrigues; Neumann, Antonielle Borges Faria; Jeunon, Thiago

    2016-01-01

    Leprosy is a chronic disease characterized by manifestations in the peripheral nerves and skin. The course of the disease may be interrupted by acute phenomena called reactions. This article reports a peculiar case of type 2 leprosy reaction with Sweet's syndrome-like features as the first clinical manifestation of leprosy, resulting in a delay in the diagnosis due to unusual clinical presentation. The patient had clinical and histopathological features reminiscent of Sweet's syndrome associated with clusters of vacuolated histiocytes containing acid-fast bacilli isolated or forming globi. Herein, it is discussed how to recognize type 2 leprosy reaction with Sweet's syndrome features, the differential diagnosis with type 1 leprosy reaction and the treatment options. When this kind of reaction is the first clinical presentation of leprosy, the correct diagnosis might be not suspected clinically, and established only with histopathologic evaluation. PMID:27438203

  3. Calmodulin is essential for cardiac IKS channel gating and assembly: impaired function in long-QT mutations.

    PubMed

    Shamgar, Liora; Ma, Lijuan; Schmitt, Nicole; Haitin, Yoni; Peretz, Asher; Wiener, Reuven; Hirsch, Joel; Pongs, Olaf; Attali, Bernard

    2006-04-28

    The slow IKS K+ channel plays a major role in repolarizing the cardiac action potential and consists of the assembly of KCNQ1 and KCNE1 subunits. Mutations in either KCNQ1 or KCNE1 genes produce the long-QT syndrome, a life-threatening ventricular arrhythmia. Here, we show that long-QT mutations located in the KCNQ1 C terminus impair calmodulin (CaM) binding, which affects both channel gating and assembly. The mutations produce a voltage-dependent macroscopic inactivation and dramatically alter channel assembly. KCNE1 forms a ternary complex with wild-type KCNQ1 and Ca(2+)-CaM that prevents inactivation, facilitates channel assembly, and mediates a Ca(2+)-sensitive increase of IKS-current, with a considerable Ca(2+)-dependent left-shift of the voltage-dependence of activation. Coexpression of KCNQ1 or IKS channels with a Ca(2+)-insensitive CaM mutant markedly suppresses the currents and produces a right shift in the voltage-dependence of channel activation. KCNE1 association to KCNQ1 long-QT mutants significantly improves mutant channel expression and prevents macroscopic inactivation. However, the marked right shift in channel activation and the subsequent decrease in current amplitude cannot restore normal levels of IKS channel activity. Our data indicate that in healthy individuals, CaM binding to KCNQ1 is essential for correct channel folding and assembly and for conferring Ca(2+)-sensitive IKS-current stimulation, which increases the cardiac repolarization reserve and hence prevents the risk of ventricular arrhythmias.

  4. Trichorhinophalangeal syndrome type 1: A case report with literature review

    PubMed Central

    Candamourty, Ramesh; Venkatachalam, Suresh; Karthikeyan, B.; Babu, M. R. Ramesh

    2012-01-01

    Trichorhinophalangeal syndrome is a very rare genetic disorder, where damage and mutation to the number 8 chromosome affects sufferers in numerous ways. The syndrome has three types, all characterized by abnormally short stature, sparse hair, short deformed fingers with cone-shaped epiphyses visible in radiographs. Type I is the most common. Type II is characterized by the development of multiple bony exostoses and frequently, mental disability. Type III is a more severe form of type I and is associated with short stature. This report presents a 28-year-old man who had the characteristic features of type I with the presence of multiple erupted supernumerary teeth with normal mentation and karyotyping with high resolution G banding displayed normal chromosomal complements. PMID:23225991

  5. Perry Syndrome: A Distinctive Type of TDP-43 Proteinopathy.

    PubMed

    Mishima, Takayasu; Koga, Shunsuke; Lin, Wen-Lang; Kasanuki, Koji; Castanedes-Casey, Monica; Wszolek, Zbigniew K; Oh, Shin J; Tsuboi, Yoshio; Dickson, Dennis W

    2017-08-01

    Perry syndrome is a rare atypical parkinsonism with depression, apathy, weight loss, and central hypoventilation caused by mutations in dynactin p150glued (DCTN1). A rare distal hereditary motor neuropathy, HMN7B, also has mutations in DCTN1. Perry syndrome has TAR DNA-binding protein of 43 kDa (TDP-43) inclusions as a defining feature. Other TDP-43 proteinopathies include amyotrophic lateral sclerosis (ALS) and frontotemporal lobar degeneration (FTLD) with and without motor neuron disease (FTLD-MND). TDP-43 forms aggregates in neuronal cytoplasmic inclusions (NCIs), neuronal intranuclear inclusions, dystrophic neurites (DNs), as well as axonal spheroids, oligodendroglial cytoplasmic inclusions, and perivascular astrocytic inclusions (PVIs). We performed semiquantitative assessment of these lesions and presence of dynactin subunit p50 lesions in 3 cases of Perry syndrome and one of HMN7B. We compared them with 3 cases of FTLD-MND, 3 of ALS, and 3 of hippocampal sclerosis (HpScl). Perry syndrome had NCIs, DNs, and frequent PVIs and spheroids. Perry syndrome cases were similar, but different from ALS, FTLD-MND, and HpScl. TDP-43 pathology was not detected in HMN7B. Dynactin p50 inclusions were observed in both Perry syndrome and HMN7B, but not in the other conditions. These results suggest that Perry syndrome may be distinctive type of TDP-43 proteinopathy. © 2017 American Association of Neuropathologists, Inc. All rights reserved.

  6. [Acute coronary syndrome after hornet bite, type II Kounis syndrome - a case report].

    PubMed

    Alihodzić, Hajriz; Ilić, Boris; Mladina, Nada; Mrsić, Denis

    2013-01-01

    Kounis syndrome is an accidental occurrence of acute coronary syndrome associated with anaphylaxis, where acute inflammatory mediators cause the spasm of coronary arteries with the erosion and rupture of atheromatous plaque. We present a 53-year-old male who during the treatment of anaphylaxis after a hornet bite developed acute anteroseptal myocardial infarction. The diagnosis of type II Kounis syndrome was proven by electrocardiographic abnormalities and biochemical markers with clinical manifestation of acute coronary syndrome, and was associated with anaphylaxis which demanded prehospital treatment of the patient after the hornet bite. Anaphylaxis after a hornet bite requires consideration of acute coronary syndrome if patients have chest pain and hemodynamic impairment, as these conditions occur infrequently but demand additional diagnostics and adequate treatment.

  7. Clinical and morphological features of Waardenburg syndrome type II.

    PubMed

    Mullaney, P B; Parsons, M A; Weatherhead, R G; Karcioglu, Z A

    1998-01-01

    Evaluation of 4-month-old girl who presented with congenital cataracts revealed heterochromia iridis, fundus hypopigmentation, residual white forelock and sensory neural hearing loss--findings consistent with Waardenburg syndrome type II. Bilateral peripheral iridectomies performed at lensectomy provided tissue for evaluation. Light microscopy revealed fewer melanocytes in the blue iris than in the brown. Electron microscopic examination showed a significant (p = 0.0001) reduction in melanosome size in the blue iris, and the nerve endings contained fewer vesicles. A defect in neural crest cell migration and melanin synthesis may be responsible for the heterochromia iridis seen in Waardenburg syndrome type II.

  8. Use of in vitro methods to predict QT prolongation

    SciTech Connect

    Hammond, T.G. . E-mail: tim.hammond@astrazeneca.com; Pollard, C.E.

    2005-09-01

    The inhibition of the hERG-encoded potassium channel can lead to prolongation of the cardiac action potential-manifested as a prolongation of the QT interval on the ECG. Although QT interval prolongation is not dangerous per se, in a small percentage of cases, it is associated with a potentially fatal arrhythmia: Torsades de Pointes (TdP). This channel type is pharmacologically promiscuous, so many compounds have caused QT interval prolongation in man and this has led to drugs being withdrawn from the market following evidence of TdP. From a drug discovery perspective, focusing as early as possible on screening out hERG activity is important. Retrospective analysis of hERG potency versus clinical incidence of TdP suggests provisional safety margins that could be used as target values by medicinal chemists. Large safety margins will not always be possible; however, and in such circumstances, if the risk-benefit ratio still favours developing the compound, a pre-clinical assessment of the likelihood that any QT interval prolongation will or will not lead to TdP in man may be important. An isolated rabbit heart model of arrhythmia shows promise in this respect, based on a comparison of clinical data with that obtained from this assay. Specific regulatory guidance on this topic is still in the draft form but the pre-clinical document (ICH S7B) contains a largely useful perspective on how an integrated risk assessment could be formed using in vitro and in vivo assays. The role of this document is evolving however, since the draft clinical guideline (E14) suggests that irrespective of the pre-clinical data, a thorough clinical ECG study will be required at some point during development.

  9. Treatment of Frey's syndrome with botulinum toxin type B.

    PubMed

    Cantarella, Giovanna; Berlusconi, Alessandra; Mele, Vincenzo; Cogiamanian, Filippo; Barbieri, Sergio

    2010-08-01

    Frey's syndrome is a frequent sequela of parotidectomy, causing facial sweating and flushing because of gustatory stimuli. Although botulinum toxin type A has become first-line therapy for Frey's syndrome, some patients become resistant. In this study, we investigated whether another serotype, botulinum toxin type B, might be an effective alternative. Case series with planned data collection. Otolaryngology department in a university hospital. Seven patients aged 30 to 68 years, with severe Frey's syndrome, underwent the Minor test and had 80 U of botulinum toxin type B per cm(2) (mean total dose, 2354 U) injected intracutaneously in the mapped area of gustatory sweating. All patients were followed up for 12 months. One month after treatment, six of the seven patients reported that gustatory sweating and flushing had resolved, and, in the remaining patient, these symptoms had decreased. The Minor test confirmed a significant improvement. The subjective benefits remained stable for six months in four patients and for nine months in the remaining three patients; 12 months after treatment, all patients still reported some improvement. Botulinum toxin type B afforded symptomatic relief in a small sample of patients with Frey's syndrome and might be considered a potential alternative to botulinum toxin type A. Copyright (c) 2010 American Academy of Otolaryngology-Head and Neck Surgery Foundation. Published by Mosby, Inc. All rights reserved.

  10. Cardiovascular profile in postural orthostatic tachycardia syndrome and Ehlers-Danlos syndrome type III.

    PubMed

    Cheng, Jem L; Au, Jason S; Guzman, Juan C; Morillo, Carlos A; MacDonald, Maureen J

    2016-12-22

    The cardiovascular profile of postural orthostatic tachycardia syndrome + Ehlers-Danlos syndrome hypermobility type (POTS + EDSIII) has not been described, despite suggestions that it plays a role in orthostatic intolerance. We studied nine individuals diagnosed with POTS + EDSIII and found that the arterial stiffness and cardiac profiles of patients with POTS + EDSIII were comparable to those of age- and sex-matched controls, suggesting an alternate explanation for orthostatic intolerance.

  11. Neurologic consequences of autoimmune polyglandular syndrome type 1.

    PubMed

    Berger, Joseph R; Weaver, Allison; Greenlee, John; Wahlen, George E

    2008-06-03

    Autoimmune polyglandular syndrome type 1 (APS-1) is a rare autosomal recessive disorder that is chiefly characterized by polyendocrinopathy, chronic mucocutaneous candidiasis, and ectodermal dystrophy. The neurologic complications of this disorder have not been well characterized. The authors report a patient with a previously undescribed autoimmune cerebellar degeneration occurring in association with APS-1 and review the literature regarding the neurologic complications of this disorder. This 24-year-old woman with APS-1 presented with gait ataxia associated with band-like hyperintense signal abnormalities of both cerebellar hemispheres and a unique antibody to cerebellar Purkinje cells and brainstem neurons. At age 9, she had C. Miller Fisher syndrome, from which she had fully recovered. Autoimmune neurologic disease may develop with autoimmune polyglandular syndrome type 1. Neurologic disease may also result from the associated endocrinopathies (hypoparathyroidism, hypothyroidism, diabetes mellitus), vitamin deficiency (vitamins B12 and E), and celiac sprue.

  12. Free flap transfer for complex regional pain syndrome type II

    PubMed Central

    Matsuda, Ken; Kikuchi, Mamoru; Murase, Tsuyoshi; Hosokawa, Ko; Shibata, Minoru

    2014-01-01

    Abstract A patient with complex regional pain syndrome type II was successfully treated using free anterolateral thigh flap transfer with digital nerve coaptation to the cutaneous nerve of the flap. Release of the scarred tissue and soft tissue coverage with targeted sensory nerve coaptation were useful in relieving severe pain. PMID:27252946

  13. Nocturnal hyperglycaemia in type 2 diabetes with sleep apnoea syndrome.

    PubMed

    Fendri, Salha; Rose, Dominique; Myambu, Sonia; Jeanne, Sandrine; Lalau, Jean-Daniel

    2011-01-01

    We assessed glycaemic status in 26 overweight or obese people with type 2 diabetes suspected of having sleep apnoea syndrome (SAS). In people with SAS (n=13), nocturnal glycaemia was 38% higher, independent of body mass index (particularly during rapid eye movement sleep) compared with non-SAS subjects (p<0.008).

  14. [Familial partial lipodystrophy type 1. A rare or underdiagnosed syndrome?].

    PubMed

    Soutelo, Jimena; Grüneisen, Mariana; Fritz, Clara; Sordo, Laura; Powazniak, Yanina; Lutfi, Rubén

    2015-01-01

    Familial partial lipodystrophy (FPL) type 1 is a syndrome characterized by loss of subcutaneous fat in arms and legs and an excess of body fat in face, neck, and torso. This rare syndrome is usually diagnosed when patients present cardiovascular complications or pancreatitis due to the severe metabolic abnormalities. Here we present the case of a 45 year old diabetic female without any pathological family history, a poor glycemic control (HbA1c 11.7%), hypertriglideridemia (3000 mg/dl), a body mass index (BMI) of 38, thin limbs, subcutaneous fat loss in gluteal area and ledge of fat above them, prominent veins in lower extremities, moon face, and acanthosis nigricans; as well as hypertension (150/100 mmHg) and subcutaneous folds measuring less than average were observed. Hypercortisolism was discarded and leptin levels were measured (16.8 mg/ml, VR: BMI > 30: 50 mg/ml). Due to these clinical and biochemical manifestations, and low leptin levels (16.8 mg/ml), Kobberling syndrome was suspected; however, LMNA mutation analysis was negative. Changes in lifestyle and treatment with fenofibrate, biphasic insulin 50/50, and enalapril were initiated showing a a significant metabolic improvement: HbA1c (7.8%) and TG (243 mg/dl). FPL type 1 is a familial disease, although there are spontaneous cases. No specific mutation is responsible for this syndrome. Due to its clinical manifestations, Cushing syndrome must be discarded.

  15. [Clinical literature based statistical analysis of common Chinese medical syndrome types].

    PubMed

    Li, Bing; Wang, Zhong; Zhang, Ying-Ying; Yu, Ya-Nan; Liu, Jun; Shen, Chun-Ti; Zhang, Lei; Wang, Yong-Yan

    2014-08-01

    According to the principle of evidence-based medicine (EBM), Chinese medical literatures based descriptive statistical analysis of common Chinese medical syndrome types were performed. By data extraction, standardization, and frequency calculation of disease names and syndrome types from 286 literatures in line with the inclusion criteria, the frequencies of diseases and syndromes were obtained to analyze common syndrome types in clinical practice, to analyze the distribution features of disease related syndromes and syndrome related diseases, to analyze the distribution of basic Chinese medical syndrome types in clinical common diseases as a whole, thus providing reference for clinical and basic researches.

  16. Multicenter comparison of Roche COBAS AMPLICOR MONITOR version 1.5, Organon Teknika NucliSens QT with Extractor, and Bayer Quantiplex version 3.0 for quantification of human immunodeficiency virus type 1 RNA in plasma.

    PubMed

    Murphy, D G; Côté, L; Fauvel, M; René, P; Vincelette, J

    2000-11-01

    The performance and characteristics of Roche COBAS AMPLICOR HIV-1 MONITOR version 1.5 (CA MONITOR 1.5) UltraSensitive (usCA MONITOR 1. 5) and Standard (stCA MONITOR 1.5) procedures, Organon Teknika NucliSens HIV-1 RNA QT with Extractor (NucliSens), and Bayer Quantiplex HIV RNA version 3.0 (bDNA 3.0) were compared in a multicenter trial. Samples used in this study included 460 plasma specimens from human immunodeficiency virus (HIV) type 1 (HIV-1)-infected persons, 100 plasma specimens from HIV antibody (anti-HIV)-negative persons, and culture supernatants of HIV-1 subtype A to E isolates diluted in anti-HIV-negative plasma. Overall, bDNA 3.0 showed the least variation in RNA measures upon repeat testing. For the Roche assays, usCA MONITOR 1.5 displayed less variation in RNA measures than stCA MONITOR 1.5. NucliSens, at an input volume of 2 ml, showed the best sensitivity. Deming regression analysis indicated that the results of all three assays were significantly correlated (P < 0.0001). However, the mean difference in values between CA MONITOR 1.5 and bDNA 3.0 (0.274 log(10) RNA copies/ml; 95% confidence interval, 0.192 to 0.356) was significantly different from 0, indicating that CA MONITOR 1.5 values were regularly higher than bDNA 3.0 values. Upon testing of 100 anti-HIV-negative plasma specimens, usCA MONITOR 1.5 and NucliSens displayed 100% specificity, while bDNA 3.0 showed 98% specificity. NucliSens quantified 2 of 10 non-subtype B viral isolates at 1 log(10) lower than both CA MONITOR 1.5 and bDNA 3.0. For NucliSens, testing of specimens with greater than 1,000 RNA copies/ml at input volumes of 0.1, 0.2, and 2.0 ml did not affect the quality of results. Additional factors differing between assays included specimen throughput and volume requirements, limit of detection, ease of execution, instrument work space, and costs of disposal. These characteristics, along with assay performance, should be considered when one is selecting a viral load assay.

  17. Congenital Chylous Ascites and Ehlers-Danlos Syndrome Type VI

    PubMed Central

    Pohl, John; Esty, Brittany; Sempler, Jessica K.; Carey, John C.; O’Gorman, Molly A.

    2016-01-01

    We report the first observation of a patient with contgenital chylous ascites (CCA) and Ehlers-Danlos syndrome type VI due to primary lymphatic defect with additional vascular anomaly. CCA is a rare condition, and there is limited understanding of its pathophysiology and treatment options. We also review the patient’s treatment course mitigated with octreotide and total parenteral nutritional support, as there are no current established guidelines for CCA. Early recognition of possible association with Ehlers-Danlos syndrome is important for quick intervention and successful management of pediatric patients. PMID:28119937

  18. Terson Syndrome Associated With Acute Macular Neuropathy Type 2.

    PubMed

    Vujosevic, Stela; Testi, Ilaria; Nacci, Elisabetta; Midena, Edoardo

    2017-09-01

    Terson syndrome is defined as the incidence of intraocular hemorrhage in patients following a subarachnoid or intracranial bleed. A 38-year-old female with both intraretinal and subretinal hemorrhages secondary to Terson syndrome underwent repair of a ruptured cerebral aneurysm. One month following resolution of the macular hemorrhages, a paracentral scotoma persisted. Multimodal imaging (morphological and functional) confirmed the presence of acute macular neuroretinopathy Type 2 associated with deep retinal capillary ischemia. Optical coherence tomography angiography illustrated the selective involvement of the deep retinal capillary plexus. [Ophthalmic Surg Lasers Imaging Retina. 2017;48:764-767.]. Copyright 2017, SLACK Incorporated.

  19. Mauriac syndrome: growth failure and type 1 diabetes mellitus.

    PubMed

    Kim, Mimi S; Quintos, J B

    2008-08-01

    Growth failure in Type 1 Diabetes Mellitus (T1DM) can occur for several reasons. Mauriac syndrome is a rare cause of severe growth failure in T1DM. There may be different forms and etiologies involved in Mauriac syndrome. However, there are common features noted in these patients. We have compiled a review of cases reported in English in the last 30 years. With adequate insulin treatment there is reversal of growth failure and hepatomegaly if present. However, overly aggressive insulin delivery could result in rapid deterioration of diabetic retinopathy and nephropathy. Close monitoring of growth and pubertal maturation in children with T1DM is essential.

  20. Adult presentation of Bartter syndrome type IV with erythrocytosis

    PubMed Central

    Heilberg, Ita Pfeferman; Tótoli, Cláudia; Calado, Joaquim Tomaz

    2015-01-01

    Abstract Bartter syndrome comprises a group of rare autosomal-recessive salt-losing disorders with distinct phenotypes, but one unifying pathophysiology consisting of severe reductions of sodium reabsorption caused by mutations in five genes expressed in the thick ascending limb of Henle, coupled with increased urinary excretion of potassium and hydrogen, which leads to hypokalemic alkalosis. Bartter syndrome type IV, caused by loss-of-function mutations in barttin, a subunit of chloride channel CLC-Kb expressed in the kidney and inner ear, usually occurs in the antenatal-neonatal period. We report an unusual case of late onset presentation of Bartter syndrome IV and mild phenotype in a 20 years-old man who had hypokalemia, deafness, secondary hyperparathyroidism and erythrocytosis. PMID:26537508

  1. Genetics of Multiple Endocrine Neoplasia Type 1/Multiple Endocrine Neoplasia Type 2 Syndromes.

    PubMed

    Hyde, Samuel M; Cote, Gilbert J; Grubbs, Elizabeth G

    2017-06-01

    Multiple endocrine neoplasia syndromes types 1 and 2 represent well-characterized yet clinically heterogeneous hereditary conditions for which diagnostic and management recommendations exist; genetic testing for these inherited endocrinopathies is included in these guidelines and is an important part of identifying affected patients and their family members. Understanding of these mature syndromes is challenged as more individuals undergo genetic testing and genetic data are amassed, with the potential to create clinical conundrums that may have an impact on individualized approaches to management and counseling. Clinicians who diagnose and treat patients with MEN syndromes should be aware of these possibilities. Copyright © 2017 Elsevier Inc. All rights reserved.

  2. [The QT interval: standardization, limits and interpretation].

    PubMed

    Ouali, S; Ben Salem, H; Gribaa, R; Kacem, S; Hammas, S; Fradi, S; Neffeti, E; Remedi, F; Boughzela, E

    2012-02-01

    Despite clinical importance of ventricular repolarisation, it remains difficult to analyse. Conventionally, quantification of the electrocardiographic ventricular repolarization is usually performed with reference to axis of the T wave and QT interval duration. A variety of factors can prolong the QT interval, such as drug effects, electrolyte imbalances, and myocardial ischemia. The biggest risk with prolongation of the QT interval is the development of torsades de pointes. Commonly accepted reference ranges for the electrocardiogram (ECG) have been in use, with little change, for many years. Populations throughout the world present several differences: age, ethnic compositions, and are exposed to different environmental factors. Recent studies have reported reference data for QT interval in healthy population and have evaluated the influence of age, gender, QRS duration and heart rate on this interval. In this review, we address several issues relative to the measurement, and interpretation of QT interval and its adjustment for rate, age, gender and QRS duration. Copyright © 2010 Elsevier Masson SAS. All rights reserved.

  3. No Untoward Effect of Long-Term Ketoconazole Administration on Electrocardiographic QT Interval in Patients with Cushing's Disease.

    PubMed

    De Martin, Martina; Toja, Paola Maria; Goulene, Karine; Radaelli, Piero; Cavagnini, Francesco; Stramba-Badiale, Marco; Pecori Giraldi, Francesca

    2016-04-01

    Ketoconazole is listed among drugs that prolong QT interval and may increase the risk of torsade de pointes, a severe ventricular arrhythmia. This compound has recently been approved for treatment of Cushing's syndrome, a severe endocrine disorder. These patients harbour several risk factors for prolonged QT interval, for example hypokalaemia and left ventricular hypertrophy, but no study has evaluated whether administration of ketoconazole affects their QT interval. The aim of this study was to assess the QT interval in patients with Cushing's disease during long-term administration of ketoconazole. Electrocardiograms from 15 patients with Cushing's disease (12 women, 3 men, age: 37.8 ± 2.66 years) on ketoconazole treatment (100 mg-800 mg qd) for 1 month to 12 years were reviewed retrospectively. QT interval was measured and corrected for heart rate (QTc). Measurements before and during ketoconazole treatment were compared and any abnormal QTc value recorded. Concurrent medical therapies were also documented. On average, QTc was superimposable before and during ketoconazole treatment (393.2 ± 7.17 versus 403.3 ± 6.05 msec. in women; 424.3 ± 23.54 versus 398.0 ± 14.93 msec. in men, N.S.). QTc normalized on ketoconazole in one man with prolonged QTc prior to treatment; no abnormal QTc was observed in any other patient during the entire observation period, even during concurrent treatment with other QT-prolonging drugs. In conclusion, long-term ketoconazole administration does not appear to be associated with significant prolongation of QT interval in patients with Cushing's disease. ECG monitoring can follow recommendations drawn for other low-risk QT-prolonging drugs with attention to specific risk factors, for example hypokalaemia and drug interactions.

  4. Chronic Arsenic Exposure and Cardiac Repolarization Abnormalities with QT Interval Prolongation in a Population-based Study

    PubMed Central

    Mumford, Judy L.; Wu, Kegong; Xia, Yajuan; Kwok, Richard; Yang, Zhihui; Foster, James; Sanders, William E.

    2007-01-01

    Background Chronic arsenic exposure is associated with cardiovascular abnormalities. Prolongation of the QT (time between initial deflection of QRS complex to the end of T wave) interval and profound repolarization changes on electrocardiogram (ECG) have been reported in patients with acute promyelocytic leukemia treated with arsenic trioxide. This acquired form of long QT syndrome can result in life-threatening arrhythmias. Objective The objective of this study was to assess the cardiac effects of arsenic by investigating QT interval alterations in a human population chronically exposed to arsenic. Methods Residents in Ba Men, Inner Mongolia, have been chronically exposed to arsenic via consumption of water from artesian wells. A total of 313 Ba Men residents with the mean arsenic exposure of 15 years were divided into three arsenic exposure groups: low (≤ 21 μg/L), medium (100–300 μg/L), and high (430–690 μg/L). ECGs were obtained on all study subjects. The normal range for QTc (corrected QT) interval is 0.33–0.44 sec, and QTc ≥ 0.45 sec was considered to be prolonged. Results The prevalence rates of QT prolongation and water arsenic concentrations showed a dose-dependent relationship (p = 0.001). The prevalence rates of QTc prolongation were 3.9, 11.1, 20.6% for low, medium, and high arsenic exposure, respectively. QTc prolongation was also associated with sex (p < 0.0001) but not age (p = 0.486) or smoking (p = 0.1018). Females were more susceptible to QT prolongation than males. Conclusions We found significant association between chronic arsenic exposure and QT interval prolongation in a human population. QT interval may potentially be useful in the detection of early cardiac arsenic toxicity. PMID:17520054

  5. Chronic arsenic exposure and cardiac repolarization abnormalities with QT interval prolongation in a population-based study.

    PubMed

    Mumford, Judy L; Wu, Kegong; Xia, Yajuan; Kwok, Richard; Yang, Zhihui; Foster, James; Sanders, William E

    2007-05-01

    Chronic arsenic exposure is associated with cardiovascular abnormalities. Prolongation of the QT (time between initial deflection of QRS complex to the end of T wave) interval and profound repolarization changes on electrocardiogram (ECG) have been reported in patients with acute promyelocytic leukemia treated with arsenic trioxide. This acquired form of long QT syndrome can result in life-threatening arrhythmias. The objective of this study was to assess the cardiac effects of arsenic by investigating QT interval alterations in a human population chronically exposed to arsenic. Residents in Ba Men, Inner Mongolia, have been chronically exposed to arsenic via consumption of water from artesian wells. A total of 313 Ba Men residents with the mean arsenic exposure of 15 years were divided into three arsenic exposure groups: low (< or = 21 microg/L), medium (100-300 microg/L), and high (430-690 microg/L). ECGs were obtained on all study subjects. The normal range for QTc (corrected QT) interval is 0.33-0.44 sec, and QTc > or = 0.45 sec was considered to be prolonged. The prevalence rates of QT prolongation and water arsenic concentrations showed a dose-dependent relationship (p = 0.001). The prevalence rates of QTc prolongation were 3.9, 11.1, 20.6% for low, medium, and high arsenic exposure, respectively. QTc prolongation was also associated with sex (p < 0.0001) but not age (p = 0.486) or smoking (p = 0.1018). Females were more susceptible to QT prolongation than males. We found significant association between chronic arsenic exposure and QT interval prolongation in a human population. QT interval may potentially be useful in the detection of early cardiac arsenic toxicity.

  6. Ehlers-Danlos syndrome, classical type.

    PubMed

    Bowen, Jessica M; Sobey, Glenda J; Burrows, Nigel P; Colombi, Marina; Lavallee, Mark E; Malfait, Fransiska; Francomano, Clair A

    2017-02-13

    Classical EDS is a heritable disorder of connective tissue. Patients are affected with joint hypermobility, skin hyperextensibilty, and skin fragility leading to atrophic scarring and significant bruising. These clinical features suggest consideration of the diagnosis which then needs to be confirmed, preferably by genetic testing. The most recent criteria for the diagnosis of EDS were devised in Villefranche in 1997. [Beighton et al. (1998); Am J Med Genet 77:31-37]. The aims set out in the Villefranche Criteria were: to enable diagnostic uniformity for clinical and research purposes, to understand the natural history of each subtype of EDS, to inform management and genetic counselling, and to identify potential areas of research. The authors recognized that the criteria would need updating, but viewed the Villefranche nosology as a good starting point. Since 1997, there have been major advances in the molecular understanding of classical EDS. Previous question marks over genetic heterogeneity have been largely surpassed by evidence that abnormalities in type V collagen are the cause. Advances in molecular testing have made it possible to identify the causative mutation in the majority of patients. This has aided the further clarification of this diagnosis. The aim of this literature review is to summarize the current knowledge and highlight areas for future research. © 2017 Wiley Periodicals, Inc.

  7. Linearly scaled, rate-invariant normal limits for QT interval: eight decades of incorrect application of power functions.

    PubMed

    Rautaharju, Pentti M; Zhang, Zhu-Ming

    2002-12-01

    Normal limits for QT traditionally are derived as mean +/- 2*SD, with rate adjustment done by dividing QT values by power functions such as RR 1/2 (proportional scaling). We evaluated procedures for deriving normal limits by comparing adjusted QT distributions versus heart rate using ECG data of 11,739 normal men and women aged > or = 40 years. QT decreased as predicted by many power functions with heart rate but its SD remained relatively unchanged. Consequently, proportional scaling induced rate-dependent distortion of normal limits. Furthermore, QT distributions by heart rate were variably skewed and non-normal. Therefore, normal limits expressed as mean +/- 2*SD were misleading. Omission of regression intercept was an additional reason for failure of Bazett's and Fridericia's formulas. Regularized normal limits for adjusted QT (Qta) were obtained with linear instead of proportional scaling of type QTa = QT + k1*(1 - RR(k2)), for instance, with k2 = 0.5, k1 = 0.360 for males and 0.353 for females, or with k2 = 0.42, k1 = 0.414 for males and 0.420 for females. With linear scaling, QTa = 460 msec was established as the upper 2% normal limit, with 32 msec as the limit for a significant QTa increase from reference ECG in serial comparison. Traditional procedures for establishment of normal limits failed because of proportional scaling, assumption of normal QT distribution, or omission of regression intercept. Percentile distributions of linearly scaled adjusted QT produced regularized rate invariant normal limits within normal sinus rates.

  8. Embryonic type Na+ channel β-subunit, SCN3B masks the disease phenotype of Brugada syndrome

    PubMed Central

    Okata, Shinichiro; Yuasa, Shinsuke; Suzuki, Tomoyuki; Ito, Shogo; Makita, Naomasa; Yoshida, Tetsu; Li, Min; Kurokawa, Junko; Seki, Tomohisa; Egashira, Toru; Aizawa, Yoshiyasu; Kodaira, Masaki; Motoda, Chikaaki; Yozu, Gakuto; Shimojima, Masaya; Hayashiji, Nozomi; Hashimoto, Hisayuki; Kuroda, Yusuke; Tanaka, Atsushi; Murata, Mitsushige; Aiba, Takeshi; Shimizu, Wataru; Horie, Minoru; Kamiya, Kaichiro; Furukawa, Tetsushi; Fukuda, Keiichi

    2016-01-01

    SCN5A is abundant in heart and has a major role in INa. Loss-of-function mutation in SCN5A results in Brugada syndrome (BrS), which causes sudden death in adults. It remains unclear why disease phenotype does not manifest in the young even though mutated SCN5A is expressed in the young. The aim of the present study is to elucidate the timing of the disease manifestation in BrS. A gain-of-function mutation in SCN5A also results in Long QT syndrome type 3 (LQTS3), leading to sudden death in the young. Induced pluripotent stem cells (iPSCs) were generated from a patient with a mixed phenotype of LQTS3 and BrS with the E1784K SCN5A mutation. Here we show that electrophysiological analysis revealed that LQTS3/BrS iPSC-derived cardiomyocytes recapitulate the phenotype of LQTS3 but not BrS. Each β-subunit of the sodium channel is differentially expressed in embryonic and adult hearts. SCN3B is highly expressed in embryonic hearts and iPSC-derived cardiomyocytes. A heterologous expression system revealed that INa of mutated SCN5A is decreased and SCN3B augmented INa of mutated SCN5A. Knockdown of SCN3B in LQTS3/BrS iPSC-derived cardiomyocytes successfully unmasked the phenotype of BrS. Isogenic control of LQTS3/BrS (corrected-LQTS3/BrS) iPSC-derived cardiomyocytes gained the normal electrophysiological properties. PMID:27677334

  9. Waardenburg syndrome type II: phenotypic findings and diagnostic criteria.

    PubMed

    Liu, X Z; Newton, V E; Read, A P

    1995-01-02

    The Waardenburg syndrome (WS) consists of at least two distinct autosomal dominant hereditary disorders. WS Type I has been mapped to the distal part of chromosome 2q and the gene identified as PAX3. Other gene(s) are responsible for WS Type II. Mapping WS Type II requires accurate diagnosis within affected families. To establish diagnostic criteria for WS Type II, 81 individuals from 21 families with Type II WS were personally studied, and compared with 60 personally studied patients from 8 families with Type I and 253 cases of WS (Type I or II) from the literature. Sensorineural hearing loss (77%) and heterochromia iridum (47%) were the two most important diagnostic indicators for WS Type II. Both were more common in Type II than in Type I. Other clinical manifestations, such as white forelock and skin patches, were more frequent in Type I. We estimate the frequency of phenotypic traits and propose diagnostic criteria for WS Type II. In practice, a diagnosis of WS Type II can be made with confidence given a family history of congenital hearing loss and pigmentary disorders, where individuals have been accurately measured for ocular distances to exclude dystopia canthorum.

  10. Combining QT and small-x resummations

    NASA Astrophysics Data System (ADS)

    Marzani, Simone

    2016-03-01

    We analyze transverse momentum (QT) resummation of a colorless final state, e.g. Higgs production in gluon fusion or the production of a lepton pair via the Drell-Yan mechanism, in the limit where the invariant mass of the final state is much less than the center-of-mass energy, i.e. Q2≪s . We show how the traditional resummation of logarithms of QT/Q can be supplemented with the resummation of the leading logarithmic contributions at small x =Q2/s and we compute the necessary ingredients to perform such joint resummation.

  11. Nutrition in Type 2 Diabetes and the Metabolic Syndrome.

    PubMed

    Via, Michael A; Mechanick, Jeffrey I

    2016-11-01

    For individuals at risk for type 2 diabetes mellitus or the metabolic syndrome, adherence to an idealized dietary pattern can drastically alter the risk and course of these chronic conditions. Target levels of carbohydrate intake should approximate 30% of consumed calories. Healthy food choices should include copious fruits, vegetables, and nuts while minimizing foods with high glycemic indices, especially processed foods. Copyright © 2016 Elsevier Inc. All rights reserved.

  12. Hypermobile Ehlers-Danlos syndrome (a.k.a. Ehlers-Danlos syndrome Type III and Ehlers-Danlos syndrome hypermobility type): Clinical description and natural history.

    PubMed

    Tinkle, Brad; Castori, Marco; Berglund, Britta; Cohen, Helen; Grahame, Rodney; Kazkaz, Hanadi; Levy, Howard

    2017-03-01

    The hypermobile type of Ehlers-Danlos syndrome (hEDS) is likely the most common hereditary disorder of connective tissue. It has been described largely in those with musculoskeletal complaints including joint hypermobility, joint subluxations/dislocations, as well as skin and soft tissue manifestations. Many patients report activity-related pain and some go on to have daily pain. Two undifferentiated syndromes have been used to describe these manifestations-joint hypermobility syndrome and hEDS. Both are clinical diagnoses in the absence of other causation. Current medical literature further complicates differentiation and describes multiple associated symptoms and disorders. The current EDS nosology combines these two entities into the hypermobile type of EDS. Herein, we review and summarize the literature as a better clinical description of this type of connective tissue disorder. © 2017 Wiley Periodicals, Inc.

  13. Clinical and Genetic Spectrum of Bartter Syndrome Type 3.

    PubMed

    Seys, Elsa; Andrini, Olga; Keck, Mathilde; Mansour-Hendili, Lamisse; Courand, Pierre-Yves; Simian, Christophe; Deschenes, Georges; Kwon, Theresa; Bertholet-Thomas, Aurélia; Bobrie, Guillaume; Borde, Jean Sébastien; Bourdat-Michel, Guylhène; Decramer, Stéphane; Cailliez, Mathilde; Krug, Pauline; Cozette, Paul; Delbet, Jean Daniel; Dubourg, Laurence; Chaveau, Dominique; Fila, Marc; Jourde-Chiche, Noémie; Knebelmann, Bertrand; Lavocat, Marie-Pierre; Lemoine, Sandrine; Djeddi, Djamal; Llanas, Brigitte; Louillet, Ferielle; Merieau, Elodie; Mileva, Maria; Mota-Vieira, Luisa; Mousson, Christiane; Nobili, François; Novo, Robert; Roussey-Kesler, Gwenaëlle; Vrillon, Isabelle; Walsh, Stephen B; Teulon, Jacques; Blanchard, Anne; Vargas-Poussou, Rosa

    2017-08-01

    Bartter syndrome type 3 is a clinically heterogeneous hereditary salt-losing tubulopathy caused by mutations of the chloride voltage-gated channel Kb gene (CLCNKB), which encodes the ClC-Kb chloride channel involved in NaCl reabsorption in the renal tubule. To study phenotype/genotype correlations, we performed genetic analyses by direct sequencing and multiplex ligation-dependent probe amplification and retrospectively analyzed medical charts for 115 patients with CLCNKB mutations. Functional analyses were performed in Xenopus laevis oocytes for eight missense and two nonsense mutations. We detected 60 mutations, including 27 previously unreported mutations. Among patients, 29.5% had a phenotype of ante/neonatal Bartter syndrome (polyhydramnios or diagnosis in the first month of life), 44.5% had classic Bartter syndrome (diagnosis during childhood, hypercalciuria, and/or polyuria), and 26.0% had Gitelman-like syndrome (fortuitous discovery of hypokalemia with hypomagnesemia and/or hypocalciuria in childhood or adulthood). Nine of the ten mutations expressed in vitro decreased or abolished chloride conductance. Severe (large deletions, frameshift, nonsense, and essential splicing) and missense mutations resulting in poor residual conductance were associated with younger age at diagnosis. Electrolyte supplements and indomethacin were used frequently to induce catch-up growth, with few adverse effects. After a median follow-up of 8 (range, 1-41) years in 77 patients, chronic renal failure was detected in 19 patients (25%): one required hemodialysis and four underwent renal transplant. In summary, we report a genotype/phenotype correlation for Bartter syndrome type 3: complete loss-of-function mutations associated with younger age at diagnosis, and CKD was observed in all phenotypes. Copyright © 2017 by the American Society of Nephrology.

  14. Coupling Data Mining and Laboratory Experiments to Discover Drug Interactions Causing QT Prolongation.

    PubMed

    Lorberbaum, Tal; Sampson, Kevin J; Chang, Jeremy B; Iyer, Vivek; Woosley, Raymond L; Kass, Robert S; Tatonetti, Nicholas P

    2016-10-18

    -DDIs. Combination therapy of ceftriaxone and lansoprazole is associated with increased risk of acquired long QT syndrome. Copyright © 2016 American College of Cardiology Foundation. Published by Elsevier Inc. All rights reserved.

  15. Autoimmune polyglandular syndrome type 2: a rare condition in childhood.

    PubMed

    Kırmızıbekmez, Heves; Yeşiltepe Mutlu, Rahime Gül; Demirkıran Urgancı, Nafiye; Öner, Ayşe

    2015-03-01

    Autoimmune polyglandular syndrome type 2 is defined as the occurrence of Addison's disease concomitantly with autoimmune thyroid disease and/or type 1 diabetes mellitus. An 11-year-old boy with Hashimoto's disease, Addison's disease, celiac disease and Langerhans islet cell autoimmunity is described in this case report. Treatment of an endocrine disease may also trigger the onset of another endocrine disease. This case report underlines the importance of early recognition and treatment of critical endocrine diseases as well as the necessity to investigate pediatric patients with autoimmune diseases for coexisting conditions. Furthermore, the role of psychological stress as an inducer of autoimmunity was also discussed.

  16. DRESS syndrome associated with type 2 diabetes in a child

    PubMed Central

    Erdem, Semiha Bahceci; Bag, Ozlem; Karkiner, Canan Sule Unsal; Korkmaz, Huseyin Anil; Can, Demet

    2016-01-01

    Drug rash with eosinophilia and systemic symptoms (DRESS) syndrome is an uncommon, life-threatening drug reaction. The basic findings are skin rash, multiorgan involvement, and eosinophilia. Most of the aromatic anticonvulsants, such as phenytoin, phenobarbital and carbamazepine can induce DRESS. Herein we report a 14-year-old patient with DRESS syndrome related to carbamazepine use. The patient presented with signs of involvement of the skin, lungs, liver, and microscopic hematuria. Carbamazepine treatment was discontinued; antihistamines and steroids were started. Hyperglycemia, commencing on the first dose of the steroid given, persisted even after the discontinuation of steroids and improvement of other signs. There were no signs of pancreatitis or type 1 diabetes clinically in laboratory tests. Her blood glucose levels were regulated at first with insulin and later with metformin. Within 1 year of follow-up, still regulated with oral antidiabetics, she has been diagnosed with type 2 diabetes. Formerly, long-term sequelae related to “drug rash with eosinophilia and systemic symptoms syndrome” such as hepatic and renal failure, type 1 diabetes mellitus, Grave's disease, autoimmune hemolytic anemia, and lupus have also been reported. However, up to date, no cases with type 2 diabetes have been reported as long-term sequelae. To our knowledge, this is the first case in the literature presenting with type 2 diabetes as long-term sequelae. PMID:26862317

  17. [Syndrome of blue sclerae and keratoglobus (ocular type of Ehlers-Danlos syndrome (author's transl)].

    PubMed

    Behrens-Baumann, W; Gebauer, H J; Langenbeck, U

    1977-12-31

    Two children born on Crete of consanguinous parents presented the following manifestations of the ocular type of Ehlers-Danlos syndrome (EDS): blue sclerae, keratoglobus and rupture of cornea following minor trauma. In cultivated fibroblasts of one of the patients there was no evidence of defective lysine hydroxylation. The possible relation of our case to a recent similar report by Judisch et al. (1976) is discussed. The ocular type of EDS may be genetically heterogenous. Provisionally, we propose for cases with normal lysyl hydroxylation in vitro the term 'type VIII of EDS'.

  18. [Oral-facial-digital syndrome type I. A case report].

    PubMed

    Leonardi, R; Gallone, M; Sorge, G; Greco, F

    2004-04-01

    Oral-facial-digital syndrome type I (OFDI) is a congenital X-linked dominant disorder characterized by anomalies of the oral cavity, face and digits sometimes associated to cerebral malformations and polycystic kidney disease. The gene, responsible for this syndrome, is ofd1. Clinically it is seen only in females. Lesions of the mouth include median pseudoclefting of the upper lip, clefts of the palate and tongue, and dental anomalies (missing or supernumerary teeth, enamel hypoplasia, and teeth malpositions). Dysmorphic features affecting the head include hypertelorism, frontal bossing, micrognathia, facial asymmetry and broadened nasal ridge. The digital abnormalities are syndactyly, clinodactyly, brachydactyly and, rarely, pre or post-axial polydactyly. Less frequently ex-pressed phenotypic anomalies include skin milia, alopecia, deafness and trembling. Sometimes the diagnosis of OFDI can be difficult because there is an overlap with other types of oral-facial-digital syndromes. A sporadic case of OFDI, with 7 lower incisors, both in the primary and permanent dentition, is reported. This dental anomaly is very unusual because in literature only supernumerary cuspids are reported. In the light of this case, the authors discuss the oral phenotypic expression of ofd1 gene and its role in human odontogenesis.

  19. Ectopic Cushing syndrome secondary to metastatic medullary thyroid cancer in a child with multiple endocrine neoplasia syndrome type 2B: clues to early diagnosis of the paraneoplastic syndromes.

    PubMed

    Singer, Kanakadurga; Heiniger, Nicholas; Thomas, Inas; Worden, Francis P; Menon, Ram K; Chen, Ming

    2014-09-01

    We describe a 13-year-old male with multiple endocrine neoplasia syndrome type 2B with medullary thyroid carcinoma who was diagnosed with ectopic adrenocorticotropin-dependent Cushing syndrome. This report highlights the importance of monitoring for paraneoplastic syndrome in MEN and clues to the diagnosis of this complication provided by growth patterns.

  20. Acquired prolongation of QT interval as a risk factor for torsade de pointes ventricular tachycardia: a narrative review for the anesthesiologist and intensivist.

    PubMed

    Uvelin, Arsen; Pejaković, Jasmina; Mijatović, Vesna

    2017-06-01

    More than 70% of intensive care unit (ICU) patients experience heart rhythm disturbances, and these patients have correspondingly higher mortality rates. Consequently, one of the standards of care in ICUs is continuous electrocardiography monitoring. One of the potentially preventable dysrhythmic events is the occurrence of torsade de pointes ventricular tachycardia in the setting of acquired prolonged QT interval. This type of ventricular tachycardia can be malignant because it often progresses to ventricular fibrillation. Many factors predispose to lengthening of the QT interval, the most important of which are electrolyte abnormalities and the administration of specific medications. In this review, we discuss the pathophysiology of acquired long QT interval, stressing the medication-induced acquired long QT-interval and factors present in ICU patients that promote prolongation of the QT interval. We also propose guidelines to avoid the occurrence of torsade de pointes ventricular tachycardia.

  1. Drug-induced Inhibition and Trafficking Disruption of ion Channels: Pathogenesis of QT Abnormalities and Drug-induced Fatal Arrhythmias.

    PubMed

    Cubeddu, Luigi X

    2016-01-01

    Risk of severe and fatal ventricular arrhythmias, presenting as Torsade de Pointes (TdP), is increased in congenital and acquired forms of long QT syndromes (LQTS). Drug-induced inhibition of K+ currents, IKs, IKr, IK1, and/or Ito, delay repolarization, prolong QT, and increase the risk of TdP. Drug-induced interference with IKr is the most common cause of acquired LQTS/TdP. Multiple drugs bind to KNCH2-hERG-K+ channels affecting IKr, including antiarrythmics, antibiotics, antivirals, azole-antifungals, antimalarials, anticancer, antiemetics, prokinetics, antipsychotics, and antidepressants. Azithromycin has been recently added to this list. In addition to direct channel inhibition, some drugs interfere with the traffic of channels from the endoplasmic reticulum to the cell membrane, decreasing mature channel membrane density; e.g., pentamidine, geldalamicin, arsenic trioxide, digoxin, and probucol. Other drugs, such as ketoconazole, fluoxetine, norfluoxetine, citalopram, escitalopram, donepezil, tamoxifen, endoxifen, atazanavir, and roxitromycin, induce both direct channel inhibition and impaired channel trafficking. Although many drugs prolong the QT interval, TdP is a rare event. The following conditions increase the risk of drug-induced TdP: a) Disease states/electrolyte levels (heart failure, structural cardiac disease, bradycardia, hypokalemia); b) Pharmacogenomic variables (presence of congenital LQTS, subclinical ion-channel mutations, history of or having a relative with history of drug-induced long QT/TdP); c) Pharmacodynamic and kinetic factors (high doses, women, elderly, metabolism inhibitors, combining two or more QT prolonging drugs, drugs that prolong the QT and increase QT dispersion, and drugs with multiple actions on ion channels). Because most of these conditions are preventable, careful evaluation of risk factors and increased knowledge of drug use associated with repolarization abnormalities are strongly recommended.

  2. Drug-induced Inhibition and Trafficking Disruption of ion Channels: Pathogenesis of QT Abnormalities and Drug-induced Fatal Arrhythmias

    PubMed Central

    Cubeddu, Luigi X.

    2016-01-01

    Risk of severe and fatal ventricular arrhythmias, presenting as Torsade de Pointes (TdP), is increased in congenital and acquired forms of long QT syndromes (LQTS). Drug-induced inhibition of K+ currents, IKs, IKr, IK1, and/or Ito, delay repolarization, prolong QT, and increase the risk of TdP. Drug-induced interference with IKr is the most common cause of acquired LQTS/TdP. Multiple drugs bind to KNCH2-hERG-K+ channels affecting IKr, including antiarrythmics, antibiotics, antivirals, azole-antifungals, antimalarials, anticancer, antiemetics, prokinetics, antipsychotics, and antidepressants. Azithromycin has been recently added to this list. In addition to direct channel inhibition, some drugs interfere with the traffic of channels from the endoplasmic reticulum to the cell membrane, decreasing mature channel membrane density; e.g., pentamidine, geldalamicin, arsenic trioxide, digoxin, and probucol. Other drugs, such as ketoconazole, fluoxetine, norfluoxetine, citalopram, escitalopram, donepezil, tamoxifen, endoxifen, atazanavir, and roxitromycin, induce both direct channel inhibition and impaired channel trafficking. Although many drugs prolong the QT interval, TdP is a rare event. The following conditions increase the risk of drug-induced TdP: a) Disease states/electrolyte levels (heart failure, structural cardiac disease, bradycardia, hypokalemia); b) Pharmacogenomic variables (presence of congenital LQTS, subclinical ion-channel mutations, history of or having a relative with history of drug-induced long QT/TdP); c) Pharmacodynamic and kinetic factors (high doses, women, elderly, metabolism inhibitors, combining two or more QT prolonging drugs, drugs that prolong the QT and increase QT dispersion, and drugs with multiple actions on ion channels). Because most of these conditions are preventable, careful evaluation of risk factors and increased knowledge of drug use associated with repolarization abnormalities are strongly recommended. PMID:26926294

  3. Clinical presentations of Ehlers Danlos syndrome type IV.

    PubMed Central

    Pope, F M; Narcisi, P; Nicholls, A C; Liberman, M; Oorthuys, J W

    1988-01-01

    Ehlers Danlos syndrome type IV is an often lethal disease caused by various mutations of type III collagen genes. It presents in infancy and childhood in several ways, and the symptoms and signs include low birth weight, prematurity, congenital dislocation of the hips, easy inappropriate bruising (sometimes suspected as child battering), and a diagnostic facial phenotype. These features predict a lethal adult disease often complicated by fatal arterial rupture in early or middle adult life. Most affected patients can be diagnosed from radiolabelled collagen protein profiles by polyacrylamide gel electrophoresis. Prenatal diagnosis by specific type III collagen restriction fragment length polymorphisms is possible in some families, and will become increasingly important. Prenatal diagnosis and prevention of the disease in selected families is already possible and will be widely available in the future. Images Fig 1 Fig 2 Fig 3 Fig 4 Fig 5 Fig 6 Fig 7 Fig 8 Fig 9 Fig 10 Fig 11 PMID:3178263

  4. Type I lepra reaction presenting as immune reconstitution inflammatory syndrome.

    PubMed

    Kharkar, Vidya; Bhor, Urmila H; Mahajan, Sunanda; Khopkar, Uday

    2007-01-01

    Immune reconstitution inflammatory syndrome (IRIS) is an unusual inflammatory reaction due to infectious and non-infectious causes occurring in human Immunodeficiency virus (HIV)-infected patients. IRIS occurs after the initiation of antiretroviral therapy. There are no reports of type I lepra reaction due to IRIS in published literature from India. We report two cases of HIV-infected males who presented with borderline tuberculoid leprosy in type 1 reaction after the initiation of highly active antiretroviral treatment (HAART). Case 1 presented with multiple, tender, erythematous and hypoesthetic plaques on the trunk and extremities after 3 months of antiretroviral therapy. In case 2, type I lepra reaction was observed 2 months after the initiation of HAART.

  5. Advances in the pathogenesis of cardiorenal syndrome type 3.

    PubMed

    Clementi, Anna; Virzì, Grazia Maria; Brocca, Alessandra; de Cal, Massimo; Pastori, Silvia; Clementi, Maurizio; Granata, Antonio; Vescovo, Giorgio; Ronco, Claudio

    2015-01-01

    Cardiorenal syndrome (CRS) type 3 is a subclassification of the CRS whereby an episode of acute kidney injury (AKI) leads to the development of acute cardiac injury or dysfunction. In general, there is limited understanding of the pathophysiologic mechanisms involved in CRS type 3. An episode of AKI may have effects that depend on the severity and duration of AKI and that both directly and indirectly predispose to an acute cardiac event. Experimental data suggest that cardiac dysfunction may be related to immune system activation, inflammatory mediators release, oxidative stress, and cellular apoptosis which are well documented in the setting of AKI. Moreover, significant derangements, such as fluid and electrolyte imbalance, metabolic acidosis, and uremia, which are typical features of acute kidney injury, may impair cardiac function. In this review, we will focus on multiple factors possibly involved in the pathogenesis issues regarding CRS type 3.

  6. Association Between ACE Gene Polymorphism and QT Dispersion in Patients with Acute Myocardial Infarction.

    PubMed

    Karahan, Zulkuf; Ugurlu, Murat; Ucaman, Berzal; Veysel Ulug, Ali; Kaya, Ilyas; Cevik, Kemal; Sahin Adiyaman, Mehmet; Oztürk, Onder; Iyem, Hikmet; Ozdemir, Ferit

    2016-01-01

    Angiotensin converting enzyme (ACE) gene polymorphism is associated with high renin-angiotensin system causing myocardial fibrosis and ventricular repolarization abnormality. Based on these findings, this study was designed to determine the association between ACE gene insertion/deletion (I/D) polymorphism and QT dispersion after acute myocardial infarction (MI). The study included 108 patients with acute MI. Blood samples were obtained from all the patients for genomic DNA analysis. ECGs were recorded at baseline and at the end of a 6-month follow up. The OT dispersion was manually calculated. The mean age of the patients was 57.5 ±9.9 years (ranging from 36 to 70). The patients with DD genotype showed longer QT dispersion than patients with II or DI genotype at the baseline, while at the end of the six-month follow up the patients with DI genotype showed longer QT dispersion than patients with DD or II genotypes. However, the magnitude of the QT dispersion prolongation was higher in patients carrying the ACE D allele than patients who were not carrying it, at baseline and at the end of six-month follow up (52.5 ±2.6 msn vs. 47.5±2.1 msn at baseline, 57±3.2 msn vs. 53±2.6 msn in months, P: 0.428 and P: 0.613, respectively). Carriers of the D allele of ACE gene I/D polymorphism may be associated with QT dispersion prolongation in patients with MI.An interaction of QT dispersion and ACE gene polymorphism may be associated with an elevation of serum type I-C terminal pro-collagen concentration, possibly leading to myocardial fibrosis, and increased action potential duration.

  7. Type 1 diabetes and polyglandular autoimmune syndrome: A review

    PubMed Central

    Hansen, Martin P; Matheis, Nina; Kahaly, George J

    2015-01-01

    Type 1 diabetes (T1D) is an autoimmune disorder caused by inflammatory destruction of the pancreatic tissue. The etiopathogenesis and characteristics of the pathologic process of pancreatic destruction are well described. In addition, the putative susceptibility genes for T1D as a monoglandular disease and the relation to polyglandular autoimmune syndrome (PAS) have also been well explored. The incidence of T1D has steadily increased in most parts of the world, especially in industrialized nations. T1D is frequently associated with autoimmune endocrine and non-endocrine diseases and patients with T1D are at a higher risk for developing several glandular autoimmune diseases. Familial clustering is observed, which suggests that there is a genetic predisposition. Various hypotheses pertaining to viral- and bacterial-induced pancreatic autoimmunity have been proposed, however a definitive delineation of the autoimmune pathomechanism is still lacking. In patients with PAS, pancreatic and endocrine autoantigens either colocalize on one antigen-presenting cell or are expressed on two/various target cells sharing a common amino acid, which facilitates binding to and activation of T cells. The most prevalent PAS phenotype is the adult type 3 variant or PAS type III, which encompasses T1D and autoimmune thyroid disease. This review discusses the findings of recent studies showing noticeable differences in the genetic background and clinical phenotype of T1D either as an isolated autoimmune endocrinopathy or within the scope of polyglandular autoimmune syndrome. PMID:25685279

  8. Clinical findings in obligate carriers of type I Usher syndrome

    SciTech Connect

    Wagenaar, M.; Rahe, B. ter; Aarem, A. van; Huygen, P.; Admiraal, R.

    1995-11-20

    Seventeen obligate carriers from nine families with autosomal recessive Usher syndrome type I underwent otological, audiological, vestibular, and ophthalmological examination in order to identify possible manifestations of heterozygosity. Linkage studies were performed and six families showed linkage to chromosome region 11q13.5 while 3 families have so far failed to show linkage to the candidate regions. Eight obligate carriers had an abnormal puretone audiogram. Two different audiometric patterns could be distinguished when hearing loss was corrected for age and sex. Four carriers (24%) had significant sensorineural hearing loss (SNHL) which increased at higher frequencies. The other 13 carriers had SNHL of about 10 dB at 0.25 and 0.5 kHz, but less at higher frequencies. Vestibular findings were generally normal. Electrooculography demonstrated a significant lower mean light peak/dark trough ratio in Usher type I carriers compared to normal control individuals. The methods used in this study were found not to be specific enough to clinically identify carriers of Usher type I syndrome. Nevertheless it is remarkable that a number of obligate carriers showed significant audiological and ophthalmological abnormalities. 29 refs., 1 fig., 3 tabs.

  9. Corneal abnormalities in Ehlers-Danlos syndrome type VI.

    PubMed

    Cameron, J A

    1993-01-01

    Eleven patients with blue sclera, limbus-to-limbus corneal thinning, hypermobile joints, and consanguineous parents were examined between January 1983 and September 1991. The clinical diagnosis was consistent with the Ehlers-Danlos syndrome type VI phenotype in all patients. A "halo" sign at the limbus was present in all patients. Corneal rupture occurred in seven patients (nine eyes) either spontaneously or following minimal trauma. Acute hydrops occurred in three patients. Bilateral microcornea was present in one patient and two patients had a unilateral increased corneal diameter as a result of secondary glaucoma after trauma. Peripheral sclerocornea was present bilaterally in five patients. Curvature abnormalities included cornea plana, keratoconus, and keratoglobus.

  10. Griscelli syndrome type 2: A rare and fatal syndrome in a South Indian boy.

    PubMed

    Rajyalakshmi, R; Chakrapani, R N B

    2016-01-01

    Griscelli syndrome (GS) is a rare autosomal recessive disorder caused by mutation in the MYO5A (GS1), RAB27A (GS2), and MLPH (GS3) genes, characterized by a common feature, partial albinism. The common variant of three, GS type 2, in addition, shows primary immunodeficiency which leads to recurrent infections and hemophagocytic lymphohistiocytosis. We, herewith, describe a case of GS type 2, in a 4-year-old male child who presented with chronic and recurrent fever, lymphadenopathy, hepatosplenomegaly, and secondary neurological deterioration; highlighting the cytological and histopathological features of lymph nodes. Hair shaft examination of the child confirmed the diagnosis.

  11. Impact of age on QT interval and QT dispersion in healthy subjects: a regression analysis.

    PubMed

    Mangoni, Arduino A; Kinirons, Mark T; Swift, Cameron G; Jackson, Stephen H D

    2003-05-01

    although the isolated effects of age on QT interval and QT dispersion (QTd) have been previously investigated, no data are available on the simultaneous effects of age and other physiological or lifestyle factors on QT interval and QTd in healthy subjects. We studied the effects of age, gender, body mass index, smoking status, and blood pressure on these electrocardiographic parameters. observational study. academic medical centre. age, gender, body mass index, smoking status, and blood pressure were obtained from 191 consecutive healthy subjects (101 males and 90 females, age range 19-89 years). The subjects were divided into three groups according to their age: <30 (n=56), 30-65 (n=49), and >65 years (n=86). heart-rate corrected QT interval (QTc, Bazett's formula) progressively increased with advancing age (389+/-3 vs. 411+/-4 vs. 418+/-3 ms, means+/-SEM; P<0.01). By contrast, no differences in QTd were observed across the three groups (36+/-2 vs. 35+/-3 vs. 40+/-2 ms, P=NS). A multivariate regression analysis showed that age (P<0.01) and body mass index (P=0.04) independently predicted QT interval while gender was a weak (P=0.09) predictor of QTd. after adjusting for gender, smoking status, and blood pressure, age and body mass index independently predicted QT interval in healthy subjects. By contrast, age is not a predictor of QTd. The increase of QT interval associated with ageing and body mass index might be secondary to cardiac hypertrophy and myocardial action potential prolongation.

  12. Jervell and Lange-Nielsen Syndrome (Long QT Syndrome).

    ERIC Educational Resources Information Center

    Hulbert, T. P.

    1994-01-01

    Clinical features, pathogenetic hypotheses, and symptoms of the cardio-auditory or surdo-cardiac disorder first reported by Jervell and Lange-Nielsen are described, and methods of diagnosis and treatment are presented, to alert teachers and other professionals to potentially life-threatening symptoms they may observe when working with deaf and…

  13. Jervell and Lange-Nielsen Syndrome (Long QT Syndrome).

    ERIC Educational Resources Information Center

    Hulbert, T. P.

    1994-01-01

    Clinical features, pathogenetic hypotheses, and symptoms of the cardio-auditory or surdo-cardiac disorder first reported by Jervell and Lange-Nielsen are described, and methods of diagnosis and treatment are presented, to alert teachers and other professionals to potentially life-threatening symptoms they may observe when working with deaf and…

  14. Changes in QT interval before and after hemodialysis

    PubMed Central

    Khosoosi Niaki, Mohammad Reza; Saravi, Mehrdad; Oliaee, Farshid; Akbari, Roghayeh; Noorkhomami, Sepideh; Bozorgi Rad, Seyed Hassan; Fallahpoor, Kobra; Ramezani, Mir Saeed

    2013-01-01

    Background: Cardiovascular mortality and morbidity are high in chronic renal failure (CRF) patients. Increased dispersion of QT intervals is known to predispose to ventricular arrhythmias and sudden cardiac death. This study was conducted to assess the effect of hemodialysis (HD) on corrected QT (QTc) intervals and their dispersions (QTd) in chronic hemodialyzed patients. Methods: Fifty-eight patients ( mean age 54.2±15.8 years) with chronic renal disease on chronic hemodialysis (HD) were assessed by standard examination including blood pressure, body weight, heart rate, 12–lead electrocardiography and laboratory tests like electrolytes (Na +, K +, Ca ++, phosphate), urea, and creatinine 30 minutes before and after HD. The QT intervals and QTc QTc= QT √R-R/ (in milli seconds [ms]) for each lead were measured manually by one observer using calipers. The difference between the maximum and the minimum of QT interval was noted as QT dispersion (QT d). Results: The mean of pre and post dialysis R-R intervals was 859.22±96.85 ms and 870.43±91.45 ms, respectively (p>0.05). The mean of corrected QT cmax intervals increased significantly from 423.45±24.10 to 454.41±30.25 ms (p<0.05). The mean of QT dispersions and the corrected QT interval dispersions changed from 51.56±12.45 to 63.21±14.43 ms (p<0.05) from 59.40±13.58 to 68.33±14.55 ms (p<0.05), respectively. The changes in serum potassium and calcium levels were related with QT interval prolongation. Conclusion: QT and QTc interval and dispersion increase in HD patients. Prolonged QT interval indices had relation with K+ and Ca++ ions before but not after HD. PMID:24009942

  15. Long QT Syndrome–Associated Mutations in Intrauterine Fetal Death

    PubMed Central

    Crotti, Lia; Tester, David J.; White, Wendy M.; Bartos, Daniel C.; Insolia, Roberto; Besana, Alessandra; Kunic, Jennifer D.; Will, Melissa L.; Velasco, Ellyn J.; Bair, Jennifer J.; Ghidoni, Alice; Cetin, Irene; Van Dyke, Daniel L.; Wick, Myra J.; Brost, Brian; Delisle, Brian P.; Facchinetti, Fabio; George, Alfred L.; Schwartz, Peter J.; Ackerman, Michael J.

    2013-01-01

    Importance Intrauterine fetal death or stillbirth occurs in approximately 1 out of every 160 pregnancies and accounts for 50% of all perinatal deaths. Postmortem evaluation fails to elucidate an underlying cause in many cases. Long QT syndrome (LQTS) may contribute to this problem. Objective To determine the spectrum and prevalence of mutations in the 3 most common LQTS susceptible genes (KCNQ1, KCNH2, and SCN5A) for a cohort of unexplained cases. Design, Setting, and Patients In this case series, retrospective postmortem genetic testing was conducted on a convenience sample of 91 unexplained intrauterine fetal deaths (mean [SD] estimated gestational age at fetal death, 26.3 [8.7] weeks) that were collected from 2006-2012 by the Mayo Clinic, Rochester, Minnesota, or the Fondazione IRCCS Policlinico San Matteo, Pavia, Italy. More than 1300 ostensibly healthy individuals served as controls. In addition, publicly available exome databases were assessed for the general population frequency of identified genetic variants. Main Outcomes and Measures Comprehensive mutational analyses of KCNQ1 (KV7.1, LQTS type 1), KCNH2 (HERG/KV11.1, LQTS type 2), and SCN5A (NaV1.5, LQTS type 3) were performed using denaturing high-performance liquid chromatography and direct DNA sequencing on genomic DNA extracted from decedent tissue. Functional analyses of novel mutations were performed using heterologous expression and patch-clamp recording. Results The 3 putative LQTS susceptibility missense mutations (KCNQ1, p.A283T; KCNQ1, p.R397W; and KCNH2[1b], p.R25W), with a heterozygous frequency of less than 0.05% in more than 10000 publicly available exomes and absent in more than 1000 ethnically similar control patients, were discovered in 3 intrauterine fetal deaths (3.3% [95% CI, 0.68%-9.3%]). Both KV7.1-A283T (16-week male) and KV7.1-R397W (16-week female) mutations were associated with marked KV7.1 loss-of-function consistent with in utero LQTS type 1, whereas the HERG1b-R25W mutation

  16. Circadian rhythm in QT interval is preserved in mice deficient of potassium channel interacting protein 2.

    PubMed

    Gottlieb, Lisa A; Lubberding, Anniek; Larsen, Anders Peter; Thomsen, Morten B

    2017-01-01

    Potassium Channel Interacting Protein 2 (KChIP2) is suggested to be responsible for the circadian rhythm in repolarization duration, ventricular arrhythmias, and sudden cardiac death. We investigated the hypothesis that there is no circadian rhythm in QT interval in the absence of KChIP2. Implanted telemetric devices recorded electrocardiogram continuously for 5 days in conscious wild-type mice (WT, n = 9) and KChIP2(-/-) mice (n = 9) in light:dark periods and in complete darkness. QT intervals were determined from all RR intervals and corrected for heart rate (QT100 = QT/(RR/100)(1/2)). Moreover, QT intervals were determined from complexes within the RR range of mean-RR ± 1% in the individual mouse (QTmean-RR). We find that RR intervals are 125 ± 5 ms in WT and 123 ± 4 ms in KChIP2(-/-) (p = 0.81), and QT intervals are 52 ± 1 and 52 ± 1 ms, respectively(p = 0.89). No ventricular arrhythmias or sudden cardiac deaths were observed. We find similar diurnal (light:dark) and circadian (darkness) rhythms of RR intervals in WT and KChIP2(-/-) mice. Circadian rhythms in QT100 intervals are present in both groups, but at physiological small amplitudes: 1.6 ± 0.2 and 1.0 ± 0.3 ms in WT and KChIP2(-/-), respectively (p = 0.15). A diurnal rhythm in QT100 intervals was only found in WT mice. QTmean-RR intervals display clear diurnal and circadian rhythms in both WT and KChIP2(-/-). The amplitude of the circadian rhythm in QTmean-RR is 4.0 ± 0.3 and 3.1 ± 0.5 ms in WT and KChIP2(-/-), respectively (p = 0.16). In conclusion, KChIP2 expression does not appear to underlie the circadian rhythm in repolarization duration.

  17. [Research on the correlation between Chinese medical syndrome types and objective indices of Wilson's disease].

    PubMed

    Wang, Gong-qiang; Ma, Xin-feng; Wang, Wei; Sun, Quan; Zhou, Zhi-hua; Han, Yong-zhu

    2013-11-01

    To explore the correlation between Chinese medical syndrome types of Wilson's disease (WD) and clinical materials as well as physical and chemical indices. Totally 116 WD patients were typed by Chinese medical syndrome. The correlation between Chinese medical syndrome types and clinical materials as well as physical and chemical indices were analyzed using binary stepwise Logistic regression by SPSS 19.0 Software, taking the common Chinese medical syndrome types as the dependent variable and clinical materials as well as physical and chemical indices as the independent variables. Gan-Galibladder dampness-heat syndrome (GGDHS, 35.3%). Gan-stagnation and Pi-deficiency syndrome (GSPDS, 13.8%), Gan-Shen yin deficiency syndrome (GSYDS, 13.8%), and phlegm-dampness retention syndrome (PDRS, 12.1%) were most often seen. GGDHS was positively correlated with grade of K-F ring, total bilirubin (TBIL), alanine transaminase (ALT), laminin (LN) (P < 0.01). GSYDS was positively correlated with TBIL (P < 0.01). PDRS was positively correlated with clinical types, ceruloplasmin (CP), aspartate aminotransferase (AST), and total protein (TP) (P < 0.01, P < 0.05). Qi blood deficiency syndrome was positively correlated with disease course, blood ammonia, blood urea nitrogen (BUN), and LN (P < 0.01, P < 0.05). Chinese medical syndrome types were correlated with clinical materials, physical and chemical indices in WD patients, which could provide experimental reference for Chinese medical syndrome typing. GGDHS, GSPDS, GSYDS, and PDRS were most often seen.

  18. Anisometropic amblyopia in a case of type 2 Waardenburg syndrome

    PubMed Central

    Akal, Ali; Göncü, Tugba; Boyaci, Nurefsan; Yılmaz, Ömer Faruk

    2013-01-01

    This study presents a case of an 8-year-old boy with iris heterochromia and anisometropic amblyopia who was diagnosed with Waardenburg syndrome (WS) type 2. An ophthalmic examination revealed iris heterochromia and anisometropic amblyopia in our patient. In the systemic examination, a white forelock and vitiligo on the arms and body were observed and neurosensory hearing loss was revealed, for which the patient used hearing aids. Identification and typing of patients with WS is crucial to address neurosensory hearing loss, glaucoma and fundus changes. While it might be challenging to communicate with a patient with speech and hearing problems, visual acuity should be examined carefully and probable amblyopia should be identified. Anterior segment changes and signs of glaucoma should also be evaluated in detail. PMID:24351514

  19. Autoimmune Polyglandular Syndrome Type 2: A Rare Condition in Childhood

    PubMed Central

    Kırmızıbekmez, Heves; Yeşiltepe Mutlu, Rahime Gül; Demirkıran Urgancı, Nafiye; Öner, Ayşe

    2015-01-01

    Autoimmune polyglandular syndrome type 2 is defined as the occurrence of Addison’s disease concomitantly with autoimmune thyroid disease and/or type 1 diabetes mellitus. An 11-year-old boy with Hashimoto’s disease, Addison’s disease, celiac disease and Langerhans islet cell autoimmunity is described in this case report. Treatment of an endocrine disease may also trigger the onset of another endocrine disease. This case report underlines the importance of early recognition and treatment of critical endocrine diseases as well as the necessity to investigate pediatric patients with autoimmune diseases for coexisting conditions. Furthermore, the role of psychological stress as an inducer of autoimmunity was also discussed. PMID:25800482

  20. Anisometropic amblyopia in a case of type 2 Waardenburg syndrome.

    PubMed

    Akal, Ali; Göncü, Tugba; Boyaci, Nurefsan; Yılmaz, Ömer Faruk

    2013-12-18

    This study presents a case of an 8-year-old boy with iris heterochromia and anisometropic amblyopia who was diagnosed with Waardenburg syndrome (WS) type 2. An ophthalmic examination revealed iris heterochromia and anisometropic amblyopia in our patient. In the systemic examination, a white forelock and vitiligo on the arms and body were observed and neurosensory hearing loss was revealed, for which the patient used hearing aids. Identification and typing of patients with WS is crucial to address neurosensory hearing loss, glaucoma and fundus changes. While it might be challenging to communicate with a patient with speech and hearing problems, visual acuity should be examined carefully and probable amblyopia should be identified. Anterior segment changes and signs of glaucoma should also be evaluated in detail.

  1. Ehlers-Danlos Syndrome Type IV: A Case Report.

    PubMed

    Soo-Hoo, Sarah; Porten, Brandon R; Engstrom, Bjorn I; Skeik, Nedaa

    2016-04-01

    Ehlers-Danlos syndrome (EDS) encompasses a group of rare genetic connective tissue disorders. The vascular type (type IV) poses the most serious risk to patients. Diagnosis is usually difficult, especially if patients lack a family history. Life-threatening vascular emergency such as dissection or rupture can be the first presenting symptom. Management of the disease can pose a clinical challenge due to the emergency of presentation, tissue friability, and lack of clear management recommendations. We report a unique case of a 40-year-old man who presented with a ruptured celiac artery and a strong family history of EDS. This case highlights the difficulties and complications associated with treating this uncommon and serious disease.

  2. Recurrent takotsubo with prolonged QT and torsade de pointes and left ventricular thrombus.

    PubMed

    Ahmed, Alaa Eldin K; Serafi, Abdulhalim; Sunni, Nadia S; Younes, Hussein; Hassan, Walid

    2017-01-01

    Takotsubo cardiomyopathy, also known as "takotsubo syndrome," refers to transient apical ballooning syndrome, stress cardiomyopathy, or broken heart syndrome and is a recently recognized syndrome typically characterized by transient and reversible left ventricular dysfunction that develops in the setting of acute severe emotional or physical stress. Increased catecholamine levels have been proposed to play a central role in the pathogenesis of the disease, although the specific pathophysiology of this condition remains to be fully determined. At present, there have been very few reports of recurrent takotsubo cardiomyopathy. In this case report, we present a patient with multiple recurrences of takotsubo syndrome triggered by severe emotional stress that presented with recurrent loss of consciousness, QT prolongation, and polymorphic ventricular tachycardia (torsade de pointes) and left ventricular apical thrombus.

  3. Drug-induced QT interval prolongation: mechanisms and clinical management

    PubMed Central

    Nachimuthu, Senthil; Assar, Manish D.

    2012-01-01

    The prolonged QT interval is both widely seen and associated with the potentially deadly rhythm, Torsades de Pointes (TdP). While it can occur spontaneously in the congenital form, there is a wide array of drugs that have been implicated in the prolongation of the QT interval. Some of these drugs have either been restricted or withdrawn from the market due to the increased incidence of fatal polymorphic ventricular tachycardia. The list of drugs that cause QT prolongation continues to grow, and an updated list of specific drugs that prolong the QT interval can be found at www.qtdrugs.org. This review focuses on the mechanism of drug-induced QT prolongation, risk factors for TdP, culprit drugs, prevention and monitoring of prolonged drug-induced QT prolongation and treatment strategies. PMID:25083239

  4. QT interval and dispersion in primary autonomic failure.

    PubMed Central

    Lo, S. S.; Mathias, C. J.; Sutton, M. S.

    1996-01-01

    OBJECTIVE: To investigate the role of the autonomic nervous system in determining QT interval and dispersion. PATIENTS AND METHODS: 32 patients with chronic primary (idiopathic) autonomic failure (19 men, mean age 60 years) and 21 normal controls (11 men, mean age 59) without symptoms of ischaemic heart disease were studied retrospectively. Autonomic failure was diagnosed by a combination of symptomatic postural hypotension, subnormal plasma noradrenaline response to head-up tilt, and abnormal cardiovascular responses to standing, Valsalva manoeuvre, mental stress, cutaneous cold, isometric exercise, and deep breathing. QT intervals were measured from surface electrocardiograms and QT dispersion was defined as maximum QT--minimum QT occurring in any of the 12 leads. RESULTS: Mean heart rate (RR intervals) was similar in patients with autonomic failure and controls (S2 lead: 865 (132) v 857 (108) ms, P = NS; V2 lead: 865 (130) v 868 (113) ms, P = NS). QT intervals measured from electrocardiogram leads S2 and V2 were significantly longer in patients than in controls (401 (40) v 376 (16) ms, P < 0.01; and 403 (41) v 381 (20) ms, P < 0.05 respectively). The mean maximum QT interval in any lead, which is the best estimate of the maximum duration of electrical systole, was significantly longer in the patients than in controls (417 (48) v 388 (23) ms, P < 0.005). Linear regression analysis of QT and RR intervals for both groups showed a significant difference between the slopes of the two regression lines (F = 8.4, P < 0.001). However, QT dispersions were similar between patients and controls. CONCLUSIONS: Patients with primary autonomic failure have prolongation of QT intervals, indicating that the autonomic nervous system is an important determinant of QT interval. However, QT dispersion does not seem to be affected by chronic primary autonomic denervation. PMID:8665344

  5. Mutations in PIEZO2 Cause Gordon Syndrome, Marden-Walker Syndrome, and Distal Arthrogryposis Type 5

    PubMed Central

    McMillin, Margaret J.; Beck, Anita E.; Chong, Jessica X.; Shively, Kathryn M.; Buckingham, Kati J.; Gildersleeve, Heidi I.S.; Aracena, Mariana I.; Aylsworth, Arthur S.; Bitoun, Pierre; Carey, John C.; Clericuzio, Carol L.; Crow, Yanick J.; Curry, Cynthia J.; Devriendt, Koenraad; Everman, David B.; Fryer, Alan; Gibson, Kate; Giovannucci Uzielli, Maria Luisa; Graham, John M.; Hall, Judith G.; Hecht, Jacqueline T.; Heidenreich, Randall A.; Hurst, Jane A.; Irani, Sarosh; Krapels, Ingrid P.C.; Leroy, Jules G.; Mowat, David; Plant, Gordon T.; Robertson, Stephen P.; Schorry, Elizabeth K.; Scott, Richard H.; Seaver, Laurie H.; Sherr, Elliott; Splitt, Miranda; Stewart, Helen; Stumpel, Constance; Temel, Sehime G.; Weaver, David D.; Whiteford, Margo; Williams, Marc S.; Tabor, Holly K.; Smith, Joshua D.; Shendure, Jay; Nickerson, Deborah A.; Bamshad, Michael J.

    2014-01-01

    Gordon syndrome (GS), or distal arthrogryposis type 3, is a rare, autosomal-dominant disorder characterized by cleft palate and congenital contractures of the hands and feet. Exome sequencing of five GS-affected families identified mutations in piezo-type mechanosensitive ion channel component 2 (PIEZO2) in each family. Sanger sequencing revealed PIEZO2 mutations in five of seven additional families studied (for a total of 10/12 [83%] individuals), and nine families had an identical c.8057G>A (p.Arg2686His) mutation. The phenotype of GS overlaps with distal arthrogryposis type 5 (DA5) and Marden-Walker syndrome (MWS). Using molecular inversion probes for targeted sequencing to screen PIEZO2, we found mutations in 24/29 (82%) DA5-affected families and one of two MWS-affected families. The presence of cleft palate was significantly associated with c.8057G>A (Fisher’s exact test, adjusted p value < 0.0001). Collectively, although GS, DA5, and MWS have traditionally been considered separate disorders, our findings indicate that they are etiologically related and perhaps represent variable expressivity of the same condition. PMID:24726473

  6. Mutations in PIEZO2 cause Gordon syndrome, Marden-Walker syndrome, and distal arthrogryposis type 5.

    PubMed

    McMillin, Margaret J; Beck, Anita E; Chong, Jessica X; Shively, Kathryn M; Buckingham, Kati J; Gildersleeve, Heidi I S; Aracena, Mariana I; Aylsworth, Arthur S; Bitoun, Pierre; Carey, John C; Clericuzio, Carol L; Crow, Yanick J; Curry, Cynthia J; Devriendt, Koenraad; Everman, David B; Fryer, Alan; Gibson, Kate; Giovannucci Uzielli, Maria Luisa; Graham, John M; Hall, Judith G; Hecht, Jacqueline T; Heidenreich, Randall A; Hurst, Jane A; Irani, Sarosh; Krapels, Ingrid P C; Leroy, Jules G; Mowat, David; Plant, Gordon T; Robertson, Stephen P; Schorry, Elizabeth K; Scott, Richard H; Seaver, Laurie H; Sherr, Elliott; Splitt, Miranda; Stewart, Helen; Stumpel, Constance; Temel, Sehime G; Weaver, David D; Whiteford, Margo; Williams, Marc S; Tabor, Holly K; Smith, Joshua D; Shendure, Jay; Nickerson, Deborah A; Bamshad, Michael J

    2014-05-01

    Gordon syndrome (GS), or distal arthrogryposis type 3, is a rare, autosomal-dominant disorder characterized by cleft palate and congenital contractures of the hands and feet. Exome sequencing of five GS-affected families identified mutations in piezo-type mechanosensitive ion channel component 2 (PIEZO2) in each family. Sanger sequencing revealed PIEZO2 mutations in five of seven additional families studied (for a total of 10/12 [83%] individuals), and nine families had an identical c.8057G>A (p.Arg2686His) mutation. The phenotype of GS overlaps with distal arthrogryposis type 5 (DA5) and Marden-Walker syndrome (MWS). Using molecular inversion probes for targeted sequencing to screen PIEZO2, we found mutations in 24/29 (82%) DA5-affected families and one of two MWS-affected families. The presence of cleft palate was significantly associated with c.8057G>A (Fisher's exact test, adjusted p value < 0.0001). Collectively, although GS, DA5, and MWS have traditionally been considered separate disorders, our findings indicate that they are etiologically related and perhaps represent variable expressivity of the same condition. Copyright © 2014 The American Society of Human Genetics. Published by Elsevier Inc. All rights reserved.

  7. Drug-induced QT interval prolongation: does ethnicity of the thorough QT study population matter?

    PubMed Central

    Shah, Rashmi R

    2013-01-01

    Inter-ethnic differences in drug responses have been well documented. Drug-induced QT interval prolongation is a major safety concern and therefore, regulatory authorities recommend a clinical thorough QT study (TQT) to investigate new drugs for their QT-prolonging potential. A positive study, determined by breach of a preset regulatory threshold, significantly influences late phase clinical trials by requiring intense ECG monitoring. A few studies that are currently available, although not statistically conclusive at present, question the assumption that ethnicity of the study population may not influence the outcome of a TQT study. Collective consideration of available pharmacogenetic and clinical information suggests that there may be inter-ethnic differences in QT-prolonging effects of drugs and that Caucasians may be more sensitive than other populations. The information also suggest s that (a) these differences may depend on the QT-prolonging potency of the drug and (b) exposure–response (E–R) analysis may be more sensitive than simple changes in QTc interval in unmasking this difference. If the QT response in Caucasians is generally found to be more intense than in non-Caucasians, there may be significant regulatory implications for domestic acceptance of data from a TQT study conducted in foreign populations. However, each drug will warrant an individual consideration when extrapolating the results of a TQT studyfrom one ethnic population to another and the ultimate clinical relevance of any difference. Further adequately designed and powered studies, investigating the pharmacologic properties and E–R relationships of additional drugs with different potencies, are needed in Caucasians, Oriental/Asian and African populations before firm conclusions can be drawn. PMID:22882246

  8. Newer QT Correction Formulae to Correct QT for Heart Rate Changes During Exercise.

    PubMed

    Rabkin, Simon W; Cheng, XinBo Justin

    2016-02-01

    The QT interval is a marker for drug-induced cardiac toxicity, electrolyte abnormalities and genetic mutations with a high risk of sudden death. The objective was to determine the optimal QT-heart rate correction when heart rate is increased. A total of 40 persons had QT interval measured before at the end of each stage of a Bruce protocol. Currently used heart rate correction formulae (QTc) were compared to recently proposed QTc formulae derived from large population studies. Comparing the data at each stage of exercise found that QTc using the Bazett formula (QTcBZT) increased with exercise while the QTc proposed by Fridericia (QTcFRD) and by Framingham (QTcFRM) decreased with exercise. In contrast QTc proposed by Dmitrienko (QTcDMT) and Rautaharju (QTcRTHa) were relatively constant despite the increase in heart rate during exercise, whereas QTc proposed by Hodges (QTcHDG) was more variable. With exercise, the differences between QTcBZT or QTcFRD and the other correction formulae became greater and highly significant. Next, the slope of QTc or RR regression was calculated for each individual during the exercise test. The rank order of the slopes (from the smallest to largest absolute value) was QTcRTHa, QTcDMT, QTcBZT, QTcHDG, QTcFRD and QTcFRM. Furthermore the slope of the QT/heart rate relationship was significantly (P < 0.0001) different between the older formulae proposed by Bazett or Fridericia compared to the newer formulae QTcDMT or QTcRTHa. The 2 newer QT-heart rate correction formula should be used when evaluating QT interval at faster heart rates especially those associated with exercise. Copyright © 2016 Southern Society for Clinical Investigation. Published by Elsevier Inc. All rights reserved.

  9. Creation of a knowledge management system for QT analyses.

    PubMed

    Tornøe, Christoffer W; Garnett, Christine E; Wang, Yaning; Florian, Jeffry; Li, Michael; Gobburu, Jogarao V

    2011-07-01

    An increasing number of thorough QT (TQT) reports are being submitted to the US Food and Drug Administration's interdisciplinary review team for QT (IRT-QT), requiring time-intensive quantitative analyses by a multidisciplinary review team within 45 days. This calls for systematic learning to guide future trials and policies by standardizing and automating the QT analyses to improve review efficiency, provide consistent advice, and enable pooled data analyses to answer key regulatory questions. The QT interval represents the time from initiation of ventricular depolarization to completion of ventricular repolarization recorded by electrocardiograph (ECG) and is used in the proarrhythmic risk assessment. The developed QT knowledge management system is implemented in the R package "QT." Data from 11 crossover TQT studies including time-matched ECGs and pharmacokinetic measurements following single doses of 400 to 1200 mg moxifloxacin were used for the QT analysis example. The automated workflow was divided into 3 components (data management, analysis, and archival). The generated data sets, scripts, tables, and graphs are automatically stored in a queryable repository and summarized in an analysis report. More than 100 TQT studies have been analyzed using the system since 2007. This has dramatically reduced the time needed to review TQT studies and has made the IRT-QT reviews consistent across reviewers. Furthermore, the system enables leveraging prior knowledge through pooled data analyses to answer policy-related questions and to understand the various effects that influence study results.

  10. Chronic pain in hypermobility syndrome and Ehlers–Danlos syndrome (hypermobility type): it is a challenge

    PubMed Central

    Scheper, Mark C; de Vries, Janneke E; Verbunt, Jeanine; Engelbert, Raoul HH

    2015-01-01

    Generalized joint hypermobility (GJH) is highly prevalent among patients diagnosed with chronic pain. When GJH is accompanied by pain in ≥4 joints over a period ≥3 months in the absence of other conditions that cause chronic pain, the hypermobility syndrome (HMS) may be diagnosed. In addition, GJH is also a clinical sign that is frequently present in hereditary diseases of the connective tissue, such as the Marfan syndrome, osteogenesis imperfecta, and the Ehlers–Danlos syndrome. However, within the Ehlers–Danlos spectrum, a similar subcategory of patients having similar clinical features as HMS but lacking a specific genetic profile was identified: Ehlers–Danlos syndrome hypermobility type (EDS-HT). Researchers and clinicians have struggled for decades with the highly diverse clinical presentation within the HMS and EDS-HT phenotypes (Challenge 1) and the lack of understanding of the pathological mechanisms that underlie the development of pain and its persistence (Challenge 2). In addition, within the HMS/EDS-HT phenotype, there is a high prevalence of psychosocial factors, which again presents a difficult issue that needs to be addressed (Challenge 3). Despite recent scientific advances, many obstacles for clinical care and research still remain. To gain further insight into the phenotype of HMS/EDS-HT and its mechanisms, clearer descriptions of these populations should be made available. Future research and clinical care should revise and create consensus on the diagnostic criteria for HMS/EDS-HT (Solution 1), account for clinical heterogeneity by the classification of subtypes within the HMS/EDS-HT spectrum (Solution 2), and create a clinical core set (Solution 3). PMID:26316810

  11. Chronic pain in hypermobility syndrome and Ehlers-Danlos syndrome (hypermobility type): it is a challenge.

    PubMed

    Scheper, Mark C; de Vries, Janneke E; Verbunt, Jeanine; Engelbert, Raoul Hh

    2015-01-01

    Generalized joint hypermobility (GJH) is highly prevalent among patients diagnosed with chronic pain. When GJH is accompanied by pain in ≥4 joints over a period ≥3 months in the absence of other conditions that cause chronic pain, the hypermobility syndrome (HMS) may be diagnosed. In addition, GJH is also a clinical sign that is frequently present in hereditary diseases of the connective tissue, such as the Marfan syndrome, osteogenesis imperfecta, and the Ehlers-Danlos syndrome. However, within the Ehlers-Danlos spectrum, a similar subcategory of patients having similar clinical features as HMS but lacking a specific genetic profile was identified: Ehlers-Danlos syndrome hypermobility type (EDS-HT). Researchers and clinicians have struggled for decades with the highly diverse clinical presentation within the HMS and EDS-HT phenotypes (Challenge 1) and the lack of understanding of the pathological mechanisms that underlie the development of pain and its persistence (Challenge 2). In addition, within the HMS/EDS-HT phenotype, there is a high prevalence of psychosocial factors, which again presents a difficult issue that needs to be addressed (Challenge 3). Despite recent scientific advances, many obstacles for clinical care and research still remain. To gain further insight into the phenotype of HMS/EDS-HT and its mechanisms, clearer descriptions of these populations should be made available. Future research and clinical care should revise and create consensus on the diagnostic criteria for HMS/EDS-HT (Solution 1), account for clinical heterogeneity by the classification of subtypes within the HMS/EDS-HT spectrum (Solution 2), and create a clinical core set (Solution 3).

  12. Expanding the allelic disorders linked to TCTN1 to include Varadi syndrome (Orofaciodigital syndrome type VI).

    PubMed

    Al-Qattan, Mohammad M; Shaheen, Ranad; Alkuraya, Fowzan S

    2017-09-01

    Varadi syndrome is a subtype of orofaciodigital syndrome (OFDS) that combines the typical features of OFDS and the posterior fossa features of Joubert syndrome. The only gene known to be mutated in Varadi syndrome is C5ORF42. In this report, we describe the phenotype of a patient with Varadi syndrome who is homozygous for a previously reported mutation in TCTN1 (NM_001082538.2:c.342-2A>G, p.Gly115Lysfs*8) and suggest that allelic disorders linked to TCTN1 include Varadi syndrome, in addition to Joubert syndrome and Meckel-Gruber syndrome. © 2017 Wiley Periodicals, Inc.

  13. [Clinical practice guideline 'Complex regional pain syndrome type I'].

    PubMed

    Perez, R S G M; Zollinger, P E; Dijkstra, P U; Thomassen-Hilgersom, I L; Zuurmond, W W A; Rosenbrand, C J G M; Geertzen, J H B

    2007-07-28

    The development and treatment ofthe complex regional pain syndrome type I (CRPS-I) are a subject of much discussion. Using the method for the development ofevidence-based guidelines, a multidisciplinary guideline for the diagnosis and treatment of this syndrome has been drawn up. The diagnosis of CRPS-I is based on the clinical observation of signs and symptoms. For pain treatment, the WHO analgesic ladder is advised up to step z. In case of pain ofa neuropathic nature, anticonvulsants and tricyclic antidepressants may be considered. For the treatment ofinflammatory symptoms, free-radical scavengers (dimethylsulphoxide or acetylcysteine) are advised. In order to enhance peripheral blood flow, vasodilatory medication may be considered. Percutaneous sympathetic blockades may be used for a cold extremity ifvasodilatory medication produces insufficient effect. To decrease functional limitations, standardised physiotherapy and occupational therapy are advised. To prevent the occurrence of CRPS-I after wrist fractures, the use of vitamin C is recommended. Adequate perioperative analgesia, limitation of operation time and limited use of bloodlessness are advised for the secondary prevention of CRPS-I. Use of regional anaesthetic techniques can also be considered in this connection.

  14. Targeted Exon Sequencing in Usher Syndrome Type I

    PubMed Central

    Bujakowska, Kinga M.; Consugar, Mark; Place, Emily; Harper, Shyana; Lena, Jaclyn; Taub, Daniel G.; White, Joseph; Navarro-Gomez, Daniel; Weigel DiFranco, Carol; Farkas, Michael H.; Gai, Xiaowu; Berson, Eliot L.; Pierce, Eric A.

    2014-01-01

    Purpose. Patients with Usher syndrome type I (USH1) have retinitis pigmentosa, profound congenital hearing loss, and vestibular ataxia. This syndrome is currently thought to be associated with at least six genes, which are encoded by over 180 exons. Here, we present the use of state-of-the-art techniques in the molecular diagnosis of a cohort of 47 USH1 probands. Methods. The cohort was studied with selective exon capture and next-generation sequencing of currently known inherited retinal degeneration genes, comparative genomic hybridization, and Sanger sequencing of new USH1 exons identified by human retinal transcriptome analysis. Results. With this approach, we were able to genetically solve 14 of the 47 probands by confirming the biallelic inheritance of mutations. We detected two likely pathogenic variants in an additional 19 patients, for whom family members were not available for cosegregation analysis to confirm biallelic inheritance. Ten patients, in addition to primary disease–causing mutations, carried rare likely pathogenic USH1 alleles or variants in other genes associated with deaf-blindness, which may influence disease phenotype. Twenty-one of the identified mutations were novel among the 33 definite or likely solved patients. Here, we also present a clinical description of the studied cohort at their initial visits. Conclusions. We found a remarkable genetic heterogeneity in the studied USH1 cohort with multiplicity of mutations, of which many were novel. No obvious influence of genotype on phenotype was found, possibly due to small sample sizes of the genotypes under study. PMID:25468891

  15. Ehlers-Danlos Syndrome Type VIIC: A Mexican Case Report

    PubMed Central

    Rincón-Sánchez, Ana Rosa; Arce, Irma Elia; Tostado-Rabago, Enrique Alejandro; Vargas, Alberto; Padilla-Gómez, Luis Alfredo; Bolaños, Alejandro; Barrios-Guyot, Selenne; Anguiano-Alvarez, Víctor Manuel; Ledezma-Rodríguez, Víctor Chistian; Islas-Carbajal, María Cristina; Rivas-Estilla, Ana María; Feria-Velasco, Alfredo; Dávalos, Nory Omayra

    2012-01-01

    Ehlers-Danlos syndrome (EDS) is a heterogeneous group of heritable connective tissue disorders whose primary clinical features include soft and extensible skin, articular hypermobility and tissue fragility. EDS type VIIC or ‘human dermatosparaxis’ is an autosomal recessive disease characterized by severe skin fragility and sagging redundant skin (major criteria) with a soft, doughy texture, easy bruising, premature rupture of fetal membranes and large hernias (minor criteria). Dermatosparaxis (meaning ‘tearing of skin’), which has been described in several non-human species, is a disorder of the connective tissue resulting from a deficiency of the enzyme that cleaves the registration peptide off the N-terminal end of collagen after it has been secreted from fibroblasts. We describe a Mexican case from consanguineous parents with all the phenotypical characteristics previously described, plus skeletal abnormalities. PMID:22787447

  16. Type III mixed cryoglobulinemia and antiphospholipid syndrome in a patient with partial DiGeorge syndrome.

    PubMed

    Chang, Alice D; Tachdjian, Raffi; Gallagher, Kerry; McCurdy, Deborah K; Lassman, Charles; Stiehm, E Richard; Yadin, Ora

    2006-01-01

    We studied a 14 year-old boy with partial DiGeorge syndrome (DGS), status post complete repair of Tetralogy of Fallot, who developed antiphospholipid syndrome (APS) and type III mixed cryoglobulinemia. He presented with recurrent fever and dyspnea upon exertion secondary to right pulmonary embolus on chest computed tomography (CT). Coagulation studies revealed homozygous methylene tetrahydrofolate reductase 677TT mutations, elevated cardiolipin IgM antibodies, and elevated beta(2)-glycoprotein I IgM antibodies. Infectious work-up revealed only positive anti-streptolysin O (ASO) and anti-DNAse B titers. Autoimmune studies showed strongly positive anti-platelet IgM, elevated rheumatoid factor (RF), and positive cryocrit. Renal biopsy for evaluation of proteinuria and hematuria showed diffuse proliferative glomerulonephritis (DPGN) with membranoproliferative features consistent with cryoglobulinemia. Immunofixation showed polyclonal bands. Our patient was treated successfully with antibiotics, prednisone, and mycophenolate mofetil (MMF). This is the first report of a patient with partial DGS presenting with APS and type III mixed cryoglobulinemia possibly due to Streptococcal infection.

  17. Type III Mixed Cryoglobulinemia and Antiphospholipid Syndrome in a Patient With Partial DiGeorge Syndrome

    PubMed Central

    Chang, Alice D.; Tachdjian, Raffi; Gallagher, Kerry; McCurdy, Deborah K.; Lassman, Charles; Stiehm, E. Richard; Yadin, Ora

    2006-01-01

    We studied a 14 year-old boy with partial DiGeorge syndrome (DGS), status post complete repair of Tetralogy of Fallot, who developed antiphospholipid syndrome (APS) and type III mixed cryoglobulinemia. He presented with recurrent fever and dyspnea upon exertion secondary to right pulmonary embolus on chest computed tomography (CT). Coagulation studies revealed homozygous methylene tetrahydrofolate reductase 677TT mutations, elevated cardiolipin IgM antibodies, and elevated β2-glycoprotein I IgM antibodies. Infectious work-up revealed only positive anti-streptolysin O (ASO) and anti-DNAse B titers. Autoimmune studies showed strongly positive anti-platelet IgM, elevated rheumatoid factor (RF), and positive cryocrit. Renal biopsy for evaluation of proteinuria and hematuria showed diffuse proliferative glomerulonephritis (DPGN) with membranoproliferative features consistent with cryoglobulinemia. Immunofixation showed polyclonal bands. Our patient was treated successfully with antibiotics, prednisone, and mycophenolate mofetil (MMF). This is the first report of a patient with partial DGS presenting with APS and type III mixed cryoglobulinemia possibly due to Streptococcal infection. PMID:17162366

  18. Prevalence of metabolic syndrome in type 2 diabetes mellitus patients.

    PubMed

    Nsiah, Kwabena; Shang, V Owusua; Boateng, K Agyenim; Mensah, F O

    2015-01-01

    The diabetic condition is influenced by several factors, some of which can accelerate the disease's progression to various complications that aggravate the morbidity. This study aimed at determining the prevalence of metabolic syndrome (MetS) and its individual components and the most critical predictive risk factors of MetS in type 2 diabetic patients. This cross-sectional study involved 150 type 2 diabetes mellitus patients and was conducted at the Diabetes Centre of the Komfo Anokye Teaching Hospital in Kumasi, the Ashanti Region of Ghana, from February, 2013 to April, 2013. The study involved the use of a questionnaire to obtain some information on the diabetics, undertaking anthropometric measurements, as well as collecting blood samples for the measurement of some biochemical parameters; fasting blood glucose and lipid profile. MetS was defined according to the National Cholesterol Education Program/Adult Treatment Panel III criteria. The prevalence of MetS was 58% in the studied Ghanaian population. Hypertension was the commonest risk factor (60%), followed by central obesity (48.67%) and dyslipidemia (37%). Female type 2 diabetics had a higher prevalence of MetS, and carried more components than their male counterparts. Regression analysis showed three factors; femininity, high body mass index and low educational status were the most critical predictive risk factors of MetS, according to this study. With hypertension being the commonest component, future cardiovascular disease prevention strategies should focus attention on its management and prevention, through education.

  19. Altered sinoatrial node function and intra-atrial conduction in murine gain-of-function Scn5a+/ΔKPQ hearts suggest an overlap syndrome

    PubMed Central

    Wu, Jingjing; Zhang, Yanmin; Zhang, Xinzhao; Cheng, Longxian; Lammers, Wim J.; Grace, Andrew A.; Fraser, James A.; Zhang, Henggui; Huang, Christopher L. -H.

    2012-01-01

    Mutations in SCN5A, the gene encoding the pore-forming subunit of cardiac Na+ channels, cause a spectrum of arrhythmic syndromes. Of these, sinoatrial node (SAN) dysfunction occurs in patients with both loss- and gain-of-function SCN5A mutations. We explored for corresponding alterations in SAN function and intracardiac conduction and clarified possible mechanisms underlying these in an established mouse long QT syndrome type 3 model carrying a mutation equivalent to human SCN5A-ΔKPQ. Electrophysiological characterizations of SAN function in living animals and in vitro sinoatrial preparations were compared with cellular SAN and two-dimensional tissue models exploring the consequences of Scn5a+/ΔKPQ mutations. Scn5a+/ΔKPQ mice showed prolonged electrocardiographic QT and corrected QT intervals confirming long QT phenotypes. They showed frequent episodes of sinus bradycardia, sinus pause/arrest, and significantly longer sinus node recovery times, suggesting compromised pacemaker activity compared with wild-type mice. Electrocardiographic waveforms suggested depressed intra-atrial, atrioventricular node, and intraventricular conduction in Scn5a+/ΔKPQ mice. Isolated Scn5a+/ΔKPQ sinoatrial preparations similarly showed lower mean intrinsic heart rates and overall slower conduction through the SAN to the surrounding atrium than did wild-type preparations. Computer simulations of both single SAN cells as well as two-dimensional SAN-atrial models could reproduce the experimental observations of impaired pacemaker and sinoatrial conduction in terms of changes produced by both augmented tail and reduced total Na+ currents, respectively. In conclusion, the gain-of-function long QT syndrome type 3 murine Scn5a+/ΔKPQ cardiac system, in overlap with corresponding features reported in loss-of-function Na+ channel mutations, shows compromised SAN pacemaker and conduction function explicable in modeling studies through a combination of augmented tail and reduced peak Na

  20. QT dynamics early after exercise as a predictor of mortality

    PubMed Central

    Johnson, Nils P.; Holly, Thomas A.; Goldberger, Jeffrey J.

    2010-01-01

    Background Exercise and QT dynamics during ambulatory monitoring impact mortality in a variety of populations. Heart rate recovery (HRR) after exercise is a known strong predictor of mortality. Objective We assessed the independent, prognostic significance of the QT response to changing heart rate (QT dynamics) during recovery from exercise. Methods The cohort included patients referred for treadmill exercise stress over a 5 year period. Patients had to have at least 4 ECG tracings within 5 minutes of peak exercise. One had to be recorded 60 seconds into recovery to calculate the HRR. Linear regression of the QT-RR relation during recovery was used to predict QT interval at cycle lengths of 500 and 600 ms (QT-500 and QT-600). Only studies with an R2≥0.9 (72%) were retained. Optimal binary cutpoints were chosen. All-cause mortality was determined from either the Social Security death index or hospital records. Results 2,994 patients met inclusion criteria. 228 (7.6%) died during an average follow-up of 7.6±1.9 years. Abnormal QT-500 (>316 ms) was the strongest univariate QT dynamics predictor in a Cox proportional hazards model (hazard ratio=2.13, p<0.001). It remained an independent predictor of mortality after adjustment for age, exercise capacity, medications, SPECT defects, and abnormal (<12 bpm) HRR (hazard ratio=1.46, p=0.014). Conclusions An abnormal predicted QT interval at 500 ms (120 beats/min) during recovery from exercise independently predicts all-cause mortality. Because QT dynamics in recovery incorporates information on both repolarization and autonomic responsiveness, its role in risk prediction for sudden cardiac death should be further explored. PMID:20478405

  1. Automated QT analysis that learns from cardiologist annotations.

    PubMed

    Strachan, Iain Guy David; Hughes, Nicholas Peter; Poonawala, Mustafa Hashim; Mason, Jay W; Tarassenko, Lionel

    2009-01-01

    Reliable, automated QT analysis would allow the use of all the ECG data recorded during continuous Holter monitoring, rather than just intermittent 10-second ECGs. BioQT is an automated ECG analysis system based on a Hidden Markov Model, which is trained to segment ECG signals using a database of thousands of annotated waveforms. Each sample of the ECG signal is encoded by its wavelet transform coefficients. BioQT also produces a confidence measure which can be used to identify unreliable segmentations. The automatic generation of templates based on shape descriptors allows an entire 24 hours of QT data to be rapidly reviewed by a human expert, after which the template annotations can automatically be applied to all beats in the recording. The BioQT software has been used to show that drug-related perturbation of the T wave is greater in subjects receiving sotalol than in those receiving moxifloxacin. Chronological dissociation of T-wave morphology changes from the QT prolonging effect of the drug was observed with sotalol. In a definitive QT study, the percentage increase of standard deviation of QT(c) for the standard manual method with respect to that obtained with BioQT analysis was shown to be 44% and 30% for the placebo and moxifloxacin treatments, respectively. BioQT provides fully automated analysis, with confidence values for self-checking, on very large data sets such as Holter recordings. Automatic templating and expert reannotation of a small number of templates lead to a reduction in the sample size requirements for definitive QT studies.

  2. Type III Polyglandular Autoimmune Syndromes in children with type 1 diabetes mellitus.

    PubMed

    Ben-Skowronek, Iwona; Michalczyk, Aneta; Piekarski, Robert; Wysocka-Łukasik, Beata; Banecka, Bożena

    2013-01-01

    Type III Polyglandular Autoimmune Syndrome (PAS III) is composed of autoimmune thyroid diseases associated with endocrinopathy other than adrenal insufficiency. This syndrome is associated with organ-specific and organ-nonspecific or systemic autoimmune diseases. The frequency of PAS syndromes in diabetic children is unknown. The aim of the study was to evaluate the incidence of PAS III in children with diabetes mellitus type 1. The study consisted of 461 patients with diabetes mellitus type 1(T1DM), who were 1-19 years of age. TSH, free thyroxin, TPO autoantibodies, and thyroglobulin autoantibodies were determined annually. Autoimmune Hashimoto's thyroiditis was diagnosed in children with positive tests for TPO Ab and Tg Ab and thyroid parenchymal hypogenicity in the ultrasound investigation. Elevated TSI antibodies were used to diagnose Graves' disease. Additionally, Anti-Endomysial Antibodies IgA class were determined every year as screening for celiac disease. During clinical control, other autoimmune diseases were diagnosed. Adrenal function was examined by the diurnal rhythm of cortisol. PAS III was diagnosed in 14.5% children: PAS IIIA (T1DM and autoimmune thyroiditis) was recognized in 11.1 % and PAS III C (T1DM and other autoimmune disorders: celiac disease, and JIA, psoriasis and vitiligo) in 3.5% children. PAS IIIA was more prevalent in girls than in boys - 78.4% versus 21.6% (p<0.05). PAS III was observed between 1-5 years of life in 66.6% children; the frequency decreased in consecutive years and successively increased in the adolescence period to 22.7%. PAS III occurs in 14.5% of children with DM type1 and the incidence is positively correlated with patients' age and female gender. Children with PAS III should be carefully monitored as a group at risk for the development of other autoimmune diseases.

  3. Realtime Multichannel System for Beat to Beat QT Interval Variability

    NASA Technical Reports Server (NTRS)

    Starc, Vito; Schlegel, Todd T.

    2006-01-01

    The measurement of beat-to-beat QT interval variability (QTV) shows clinical promise for identifying several types of cardiac pathology. However, until now, there has been no device capable of displaying, in real time on a beattobeat basis, changes in QTV in all 12 conventional leads in a continuously monitored patient. While several software programs have been designed to analyze QTV, heretofore, such programs have all involved only a few channels (at most) and/or have required laborious user interaction or offline calculations and postprocessing, limiting their clinical utility. This paper describes a PC-based ECG software program that in real time, acquires, analyzes and displays QTV and also PQ interval variability (PQV) in each of the eight independent channels that constitute the 12lead conventional ECG. The system also processes certain related signals that are derived from singular value decomposition and that help to reduce the overall effects of noise on the realtime QTV and PQV results.

  4. Endovascular repair of multiple infrageniculate aneurysms in a patient with vascular type Ehlers-Danlos syndrome.

    PubMed

    Domenick, Natalie; Cho, Jae S; Abu Hamad, Ghassan; Makaroun, Michel S; Chaer, Rabih A

    2011-09-01

    Patients with vascular type Ehler-Danlos syndrome can develop aneurysms in unusual locations. We describe the case of a 33-year-old woman with vascular type Ehlers-Danlos syndrome who developed metachronous tibial artery aneurysms that were sequentially treated with endovascular means.

  5. Gastrointestinal and nutritional issues in joint hypermobility syndrome/Ehlers-Danlos syndrome, hypermobility type.

    PubMed

    Castori, Marco; Morlino, Silvia; Pascolini, Giulia; Blundo, Carlo; Grammatico, Paola

    2015-03-01

    Gastrointestinal involvement is a well known complication of Ehlers-Danlos syndromes (EDSs), mainly in form of abdominal emergencies due to intestinal/abdominal vessels rupture in vascular EDS. In the last decade, a growing number of works investigated the relationship between a wide spectrum of chronic gastrointestinal complaints and various EDS forms, among which the hypermobility type (a.k.a. joint hypermobility syndrome; JHS/EDS-HT) was the most studied. The emerging findings depict a major role for gastrointestinal involvement in the health status and, consequently, management of JHS/EDS-HT patients. Nevertheless, fragmentation of knowledge limits its impact on practice within the boundaries of highly specialized clinics. In this paper, literature review on gastrointestinal manifestations in JHS/EDS-HT was carried out and identified papers categorized as (i) case-control/cohort studies associating (apparently non-syndromic) joint hypermobility and gastrointestinal involvement, (ii) case-control/cohort studies associating JHS/EDS-HT and gastrointestinal involvement, (iii) case reports/series on various gastrointestinal complications in (presumed) JHS/EDS-HT, and (iv) studies reporting gastrointestinal features in heterogeneous EDS patients' cohorts. Gastrointestinal manifestations of JHS/EDS-HT were organized and discussed in two categories, including structural anomalies (i.e., abdominal/diaphragmatic hernias, internal organ/pelvic prolapses, intestinal intussusceptions) and functional features (i.e., dysphagia, gastro-esophageal reflux, dyspepsia, recurrent abdominal pain, constipation/diarrhea), with emphasis on practice and future implications. In the second part of this paper, a summary of possible nutritional interventions in JHS/EDS-HT was presented. Supplementation strategies were borrowed from data available for general population with minor modifications in the light of recent discoveries in the pathogenesis of selected JHS/EDS-HT features.

  6. Type 1 diabetes and autoimmune polyglandular syndrome: a clinical review.

    PubMed

    Van den Driessche, A; Eenkhoorn, V; Van Gaal, L; De Block, C

    2009-12-01

    Type 1 diabetes mellitus (T1DM) results from autoimmune destruction of insulin-producing beta cells and is characterised by the presence of insulitis and &and beta-cell autoantibodies. Up to one third of patients develop an autoimmune polyglandular syndrome. Fifteen to 30% of T1DM subjects have autoimmune thyroid disease (Hashimoto's or Graves' disease), 5 to 10% are diagnosed with autoimmune gastritis and/or pernicious anaemia (AIG /PA), 4 to 9% present with coeliac disease (CD), 0.5% have Addison's disease (AD), and 2 to 10% show vitiligo. These diseases are characterised by the presence of autoantibodies against thyroid peroxidase (for Hashimoto's thyroiditis), TSH receptor (for Graves' disease), parietal cell or intrinsic factor (for AIG /PA), tissue transglutaminase (for CD), and 21-hydroxylase (for AD). Early detection of antibodies and latent organ-specific dysfunction is advocated to alert physicians to take appropriate action in order to prevent full-blown disease. Hashimoto's hypothyroidism may cause weight gain, hyperlipidaemia, goitre, and may affect diabetes control, menses, and pregnancy outcome. In contrast, Graves' hyperthyroidism may induce weight loss, atrial fibrillation, heat intolerance, and ophthalmopathy. Autoimmune gastritis may manifest via iron deficiency or vitamin B12 deficiency anaemia with fatigue and painful neuropathy. Clinical features of coeliac disease include abdominal discomfort, growth abnormalities, infertility, low bone mineralisation, and iron deficiency anaemia. Adrenal insufficiency may cause vomiting, anorexia, hypoglycaemia, malaise, fatigue, muscular weakness, hyperkalaemia, hypotension, and generalised hyperpigmentation. Here we will review prevalence, pathogenetic factors, clinical features, and suggestions for screening, follow-up and treatment of patients with T1DM and/or autoimmune polyglandular syndrome.

  7. Racial Susceptibility for QT Prolongation in Acute Drug Overdoses Authors

    PubMed Central

    Manini, Alex F.; Stimmel, Barry; Vlahov, David

    2014-01-01

    Background and Purpose QT prolongation independently predicts adverse cardiovascular events in suspected poisoning. We aimed to evaluate the association between race and drug-induced QT prolongation for patients with acute overdose. Methods This was a cross-sectional observational study at two urban teaching hospitals. Consecutive adult ED patients with acute drug overdose were prospectively enrolled over a two year period. The primary outcome, long-QT, was defined using standard criteria: QTc >470ms in females and >460ms in males. The association between race and drug-induced QT prolongation was tested, considering several confounding variables. Results In 472 patients analyzed (46% female, mean age 42.3), QT prolongation occurred in 12.7%. Blacks had two-fold increased odds of drug-induced QT prolongation (OR 2.01, CI 1.03-3.91) and Hispanics had 48% decreased odds of drug-induced QT prolongation (OR 0.52, CI 0.29-0.94). Conclusions We found significant racial susceptibility to drug-induced QT prolongation in this large urban study of acute overdoses. PMID:24438862

  8. The Complex QT/RR Relationship in Mice

    PubMed Central

    Roussel, Julien; Champeroux, Pascal; Roy, Jérôme; Richard, Sylvain; Fauconnier, Jérémy; Le Guennec, Jean-Yves; Thireau, Jérôme

    2016-01-01

    The QT interval reflects the time between the depolarization of ventricles until their repolarization and is usually used as a predictive marker for the occurrence of arrhythmias. This parameter varies with the heart rate, expressed as the RR interval (time between two successive ventricular depolarizations). To calculate the QT independently of the RR, correction formulae are currently used. In mice, the QT-RR relationship as such has never been studied in conscious animals, and correction formulas are mainly empirical. In the present paper we studied how QT varies when the RR changes physiologically (comparison of nocturnal and diurnal periods) or after dosing mice with tachycardic agents (norepinephrine or nitroprusside). Our results show that there is significant variability of QT and RR in a given condition, resulting in the need to average at least 200 consecutive complexes to accurately compare the QT. Even following this method, no obvious shortening of the QT was observed with increased heart rate, regardless of whether or not this change occurs abruptly. In conclusion, the relationship between QT and RR in mice is weak, which renders the use of correction formulae inappropriate and misleading in this species. PMID:27138175

  9. Cetirizine and loratadine: minimal risk of QT prolongation.

    PubMed

    2010-02-01

    Some antihistamines, such as mizolastine and ebastine, can prolong the QT interval and provoke severe cardiac arrhythmias. This review examines the effects of two widely used antihistamines, cetirizine and loratadine, on the QT interval. As of mid 2009 very few clinical data had been published on the risk of QT prolongation with cetirizine or loratadine. The very rare reported cases of torsades de pointes linked to loratadine mainly appear to involve drug interactions, especially with amiodarone and enzyme inhibitors. We found no reports of QT prolongation attributed to desloratadine, the main metabolite of loratadine. Two cases of QT prolongation with cetirizine have been published, one of which involved overdose and renal failure. The reports are too vague to conclude that cetirizine was implicated. We found no reports of QT prolongation attributed to levocetirizine. Cetirizine is a metabolite of hydroxyzine, another antihistamine. In the 1960s, a study of patients with psychosis showed a risk of QT prolongation. A case of recurrent syncope with QT prolongation has since been reported, along with rare cases of cardiac arrhythmia. In practice, cetirizine and loratadine are first-line antihistamines. However, caution is needed in certain circumstances. In particular, it is best that patients who have risk factors for torsades de pointes or who are taking certain enzyme inhibitors avoid using loratadine. It is best to avoid using cetirizine in cases of renal failure.

  10. QT dispersion and P wave dispersion in patients with fibromyalgia

    PubMed Central

    Yolbaş, Servet; Yıldırım, Ahmet; Düzenci, Deccane; Karakaya, Bülent; Dağlı, Mustafa Necati; Koca, Süleyman Serdar

    2016-01-01

    Objective Fibromyalgia (FM) is a chronic disease characterized by widespread pain. Somatic complaints associated with the cardiovascular system, such as chest pain and palpitations, are frequently seen in FM patients. P and QT dispersions are simple and inexpensive measurements reflecting the regional heterogeneity of atrial and ventricular repolarization, respectively. QT dispersion can cause serious ventricular arrhythmias. The aim of the present study was to evaluate QT dispersion and P wave dispersion in patients with FM. Material and Methods The study involved 48 FM patients who fulfilled the established criteria and 32 healthy controls (HC). A standard 12-lead electrocardiogram was performed on all participants. QT dispersion was defined as the difference between the longest and the shortest QT intervals. Similarly, the differences between the shortest and longest P waves were defined as P wave dispersion. Results The QT dispersion and corrected QT dispersion were shorter in the FM group compared with the HC group (p<0.001 for both). In terms of the P wave dispersion value, there was no significant difference between the FM and HC groups (p=0.088). Conclusion Longer QT and P wave dispersions are not problems in patients with FM. Therefore, it may be concluded that fibromyalgia does not include an increased risk of atrial and/or ventricular arrhythmias. PMID:28149660

  11. QT dispersion and P wave dispersion in patients with fibromyalgia.

    PubMed

    Yolbaş, Servet; Yıldırım, Ahmet; Düzenci, Deccane; Karakaya, Bülent; Dağlı, Mustafa Necati; Koca, Süleyman Serdar

    2016-12-01

    Fibromyalgia (FM) is a chronic disease characterized by widespread pain. Somatic complaints associated with the cardiovascular system, such as chest pain and palpitations, are frequently seen in FM patients. P and QT dispersions are simple and inexpensive measurements reflecting the regional heterogeneity of atrial and ventricular repolarization, respectively. QT dispersion can cause serious ventricular arrhythmias. The aim of the present study was to evaluate QT dispersion and P wave dispersion in patients with FM. The study involved 48 FM patients who fulfilled the established criteria and 32 healthy controls (HC). A standard 12-lead electrocardiogram was performed on all participants. QT dispersion was defined as the difference between the longest and the shortest QT intervals. Similarly, the differences between the shortest and longest P waves were defined as P wave dispersion. The QT dispersion and corrected QT dispersion were shorter in the FM group compared with the HC group (p<0.001 for both). In terms of the P wave dispersion value, there was no significant difference between the FM and HC groups (p=0.088). Longer QT and P wave dispersions are not problems in patients with FM. Therefore, it may be concluded that fibromyalgia does not include an increased risk of atrial and/or ventricular arrhythmias.

  12. The Complex QT/RR Relationship in Mice.

    PubMed

    Roussel, Julien; Champeroux, Pascal; Roy, Jérôme; Richard, Sylvain; Fauconnier, Jérémy; Le Guennec, Jean-Yves; Thireau, Jérôme

    2016-05-03

    The QT interval reflects the time between the depolarization of ventricles until their repolarization and is usually used as a predictive marker for the occurrence of arrhythmias. This parameter varies with the heart rate, expressed as the RR interval (time between two successive ventricular depolarizations). To calculate the QT independently of the RR, correction formulae are currently used. In mice, the QT-RR relationship as such has never been studied in conscious animals, and correction formulas are mainly empirical. In the present paper we studied how QT varies when the RR changes physiologically (comparison of nocturnal and diurnal periods) or after dosing mice with tachycardic agents (norepinephrine or nitroprusside). Our results show that there is significant variability of QT and RR in a given condition, resulting in the need to average at least 200 consecutive complexes to accurately compare the QT. Even following this method, no obvious shortening of the QT was observed with increased heart rate, regardless of whether or not this change occurs abruptly. In conclusion, the relationship between QT and RR in mice is weak, which renders the use of correction formulae inappropriate and misleading in this species.

  13. A mouse model for Meckel syndrome type 3.

    PubMed

    Cook, Susan A; Collin, Gayle B; Bronson, Roderick T; Naggert, Jürgen K; Liu, Dong P; Akeson, Ellen C; Davisson, Muriel T

    2009-04-01

    Meckel-Gruber syndrome type 3 (MKS3; OMIM 607361) is a severe autosomal recessive disorder characterized by bilateral polycystic kidney disease. Other malformations associated with MKS3 include cystic changes in the liver, polydactyly, and brain abnormalities (occipital encephalocele, hydrocephalus, and Dandy Walker-type cerebellar anomalies). The disorder is hypothesized to be caused by defects in primary cilia. In humans, the underlying mutated gene, TMEM67, encodes transmembrane protein 67, also called meckelin (OMIM 609884), which is an integral protein of the renal epithelial cell and membrane of the primary cilium. Here, we describe a spontaneous deletion of the mouse ortholog, Tmem67, which results in polycystic kidney disease and death by 3 wk after birth. Hydrocephalus also occurs in some mutants. We verified the mutated gene by transgenic rescue and characterized the phenotype with microcomputed tomography, histology, scanning electron microscopy, and immunohistochemistry. This mutant provides a mouse model for MKS3 and adds to the growing set of mammalian models essential for studying the role of the primary cilium in kidney function.

  14. Fabry's disease: an example of cardiorenal syndrome type 5.

    PubMed

    Sharma, Aashish; Sartori, Marco; Zaragoza, Jose J; Villa, Gianluca; Lu, Renhua; Faggiana, Elena; Brocca, Alessandra; Di Lullo, Luca; Feriozzi, Sandro; Ronco, Claudio

    2015-11-01

    Cardiorenal syndrome type 5 (CRS-5) includes conditions where there is a simultaneous involvement of the heart and kidney from a systemic disorder. This is a bilateral organ cross talk. Fabry's disease (FD) is a devastating progressive inborn error of metabolism with lysosomal glycosphingolipid deposition in variety of cell types, capillary endothelial cells, renal, cardiac and nerve cells. Basic effect is absent or deficient activity of lysosomal exoglycohydrolase a-galactosidase A. Renal involvement consists of proteinuria, isosthenuria, altered tubular function, presenting in second or third decade leading to azotemia and end-stage renal disease in third to fifth decade mainly due to irreversible changes to glomerular, tubular and vascular structures, especially highlighted by podocytes foot process effacement. Cardiac involvement consists of left ventricular hypertrophy, right ventricular hypertrophy, arrhythmias (sinus node and conduction system impairment), diastolic dysfunction, myocardial ischemia, infarction, transmural replacement fibrosis, congestive heart failure and cardiac death. Management of FD is based on enzymatic replacement therapy and control of renal (with anti-proteinuric agents such as angiotensin-converting enzyme inhibitors-and/or angiotensin II receptor blockers), brain (coated aspirin, clopidogrel and statin to prevent strokes) and heart complications (calcium channel blockers for ischemic cardiomyopathy, warfarin and amiodarone or cardioverter device for arrhythmias).

  15. Rules for distinguishing toxicants that cause type I and type II narcosis syndromes

    SciTech Connect

    Veith, G.D.; Broderius, S.J. )

    1990-07-01

    Narcosis is a nonspecific reversible state of arrested activity of protoplasmic structures caused by a wide variety of organic chemicals. The vast majority of industrial organic chemicals can be characterized by a baseline structure-toxicity relationship as developed for diverse aquatic organisms, using only the n-octanol/water partition coefficient as a descriptor. There are, however, many apparent narcotic chemicals that are more toxic than baseline narcosis predicts. Some of these chemicals have been distinguished as polar narcotics. Joint toxic theory and isobole diagrams were used to show that chemicals strictly additive with phenol were generally more toxic than predicted by narcosis I models and characterized by a different mode of action called narcosis II syndrome. This type of toxicity is exemplified by certain amides, amines, phenols, and nitrogen heterocycles. Evidence is provided that suggests that narcosis II syndrome may result from the presence of a strong hydrogen bonding group on the molecule, and narcosis I syndrome results from hydrophobic bonding of the chemical to enzymes and/or membranes. This shift in toxic action is apparently indistinguishable for narcotic chemicals with log P greater than about 2.7. General rules for selecting the appropriate models are proposed.

  16. Neurodevelopmental attributes of joint hypermobility syndrome/Ehlers-Danlos syndrome, hypermobility type: Update and perspectives.

    PubMed

    Ghibellini, Giulia; Brancati, Francesco; Castori, Marco

    2015-03-01

    In the last decade, increasing attention has been devoted to the extra-articular and extra-cutaneous manifestations of joint hypermobility syndrome, also termed Ehlers-Danlos syndrome, hypermobility type (i.e., JHS/EDS-HT). Despite the fact that the current diagnostic criteria for both disorders remain focused on joint hypermobility, musculoskeletal pain and skin changes, medical practice and research have started investigating a wide spectrum of visceral, neurological and developmental complications, which represent major burdens for affected individuals. In particular, children with generalized joint hypermobility often present with various neurodevelopmental issues and can be referred for neurological consultation. It is common that investigations in these patients yield negative or inconsistent results, eventually leading to the exclusion of any structural neurological or muscle disorder. In the context of specialized clinics for connective tissue disorders, a clear relationship between generalized joint hypermobility and a characteristic neurodevelopmental profile affecting coordination is emerging. The clinical features of these patients tend to overlap with those of developmental coordination disorder and can be associated with learning and other disabilities. Physical and psychological consequences of these additional difficulties add to the chief manifestations of the pre-existing connective tissue disorder, affecting the well-being and development of children and their families. In this review, particular attention is devoted to the nature of the link between joint hypermobility, coordination difficulties and neurodevelopmental issues in children. Presumed pathogenesis and management issues are explored in order to attract more attention on this association and nurture future clinical research.

  17. Genetic heterogeneity of usher syndrome type 1 in French families

    SciTech Connect

    Larget-Piet, D.; Gerber, S.; Rozet, J.M. ); Bonneau, D. ); Marc, S.; Weissenbach, J. ); Ghazi, I.; Dufier, J.L. ); David, A. ); Bitoun, P. )

    1994-05-01

    Usher syndrome type 1 (US1) is an autosomal recessive disease characterized by profound congenital hearing impairment with unintelligible speech, early retinitis pigmentosa, and constant vestibular dysfunction. Three localizations have been described in US1: USH1A, 14q32; USH1B, 11q13.5; and USH1C, 11p15. Studying a series of 33 affected individuals belonging to 20 US1 pedigrees of French ancestry, the authors found that none of the three localizations accounted for all US1 families in the series. However, when the sample was split into two groups according to the geographic origin of the probands' grandparents, they were able to confirm the presence of a gene for US1 on chromosome 14q32 (USH1A) in 9 families originating from the Poitou region in Western France. Moreover, they refined the genetic mapping of USH1A by showing that the disease gene maps to the D14S13 locus, within the genetic interval defined by loci D14S78 and D14S250 (location score in log base 10 = 4.90). Consistent with this, nonsignificant lod score values for linkage to either USH1B or USH1C were found in this group. With regard to US1 families of other geographic origin (Normandy and Northern France, 11 families), nonsignificant lod scores for linkage to chromosome 11q13.5 were observed. However, the HOMOG test suggested that USH1B might account for the disease in 9/11 families in the series (families 10-19), the latter two families possibly being accounted for by USH1C (maximum likelihood for heterogeneity = 7.91 in lnL; heterogeneity versus homogeneity, P = 0.01; heterogeneity versus nonlinkage, P < 0.01). The present study supports the view that Usher syndrome type 1 is a genetically heterogeneous condition that is caused by at least three genes and possibly many more. 16 refs., 4 figs., 3 tabs.

  18. Interrupted aortic arch type B in A patient with cat eye syndrome.

    PubMed

    Belangero, Sintia Iole Nogueira; Bellucco, Fernanda Teixeira da Silva; Cernach, Mirlene C S P; Hacker, April M; Emanuel, Beverly S; Melaragno, Maria Isabel

    2009-05-01

    We report a patient with cat eye syndrome and interrupted aortic arch type B, a typical finding in the 22q11.2 deletion syndrome. Chromosomal analysis and fluorescent in situ hybridization (FISH) showed a supernumerary bisatellited isodicentric marker chromosome derived from chromosome 22. The segment from 22pter to 22q11.2 in the supernumerary chromosome found in our patient does not overlap with the region deleted in patients with the 22q11.2 deletion syndrome. However, the finding of an interrupted aortic arch type B is unusual in CES, although it is a frequent heart defect in the 22q11 deletion syndrome.

  19. Analysis of HLA and disease susceptibility: Chromosome 6 genes and sex influence long-QT phenotype

    SciTech Connect

    Weitkamp, L.R.; Moss, A.J.; Hall, W.J.; Robinson, J.L.; Guttormsen, S.A.; Lewis, R.A.; MacCluer, J.W.; Schwartz, P.J.; Locati, E.H.; Tzivoni, D.

    1994-12-01

    The long-QT (LQT) syndrome is a genetically complex disorder that is characterized by syncope and fatal ventricular arrhythmias. LQT syndrome, as defined by a prolonged electrocardiographic QT interval, has a higher incidence in females than in males and does not exhibit Mendelian transmission patterns in all families. Among those families that are nearly consistent with Mendelian transmission, linkage between a locus for LQT syndrome and the H-ras-1 locus on the short arm of chromosome 11 has been reported in some families but not in others. Earlier analyses suggesting that LQT syndrome might be caused by a gene in the HLA region of chromosome 6 were not confirmed by standard linkage analyses. Here, we present an analysis of HLA haplotype sharing among affected pedigree members, showing an excess of haplotype sharing in a previously published Japanese pedigree and possibly also in 15 families of European descent. The haplotypes shared by affected individuals derive from both affected and unaffected parents. In an analysis of independent (unrelated) HLA haplotypes, we also found a nonrandom distribution of HLA-DR genes in LQT syndrome patients compared with controls, suggesting an association between the LQT phenotype and specific HLA-DR genes. Our data indicate that DR2 has a protective effect and, particularly in males, that DR7 may increase susceptibility to the LQT syndrome. Thus, LQT syndrome may be influenced by genes on chromosomes 11 and 6, possibly with a sex-specific effect. These results provide a model for an effect of HLA-region genes inherited from either parent on the expression of an illness that may be determined principally by alleles at loci not linked to HLA.

  20. Brain imaging in cerebellar ataxia associated with autoimmune polyglandular syndrome type 2.

    PubMed

    Manto, Mario; Jissendi, P

    2012-07-01

    Autoimmune polyglandular syndrome (APS) type 2 (Schmidt syndrome) is a disorder characterized by a combination of autoimmune adrenal insufficiency, autoimmune thyroid disease, and type 1 autoimmune diabetes mellitus. We describe the first case of subacute cerebellar syndrome associated with APS type 2. Brain magnetic resonance imaging showed atrophy of the cerebellum and the vermis, as well as of the anterior pituitary gland. Magnetic resonance spectroscopy showed decreased N-acetylaspartate/creatine ratio in the cerebellum and in the pons. Our findings expand the spectrum of neurological deficits in APS type 2 and underlines that cerebellar pathways may be a main target of the disorder. © 2010 by the American Society of Neuroimaging.

  1. Midodrine in the prevention of hepatorenal syndrome type 2 recurrence: a case-control study.

    PubMed

    Alessandria, C; Debernardi-Venon, W; Carello, M; Ceretto, S; Rizzetto, M; Marzano, A

    2009-04-01

    Hepatorenal syndrome is a severe complication of cirrhosis. Treatment with terlipressin has currently the best efficacy pedigree, inducing hepatorenal syndrome reversal in a high proportion of patients. However, hepatorenal syndrome recurrence after terlipressin withdrawal is very common, especially in type 2 hepatorenal syndrome. Midodrine, an oral adrenergic vasoconstrictor, has been suggested to be an effective therapy in hepatorenal syndrome. To analyse the impact of treatment with midodrine after hepatorenal syndrome type 2 reversal induced by terlipressin on the prevention of hepatorenal syndrome recurrence. A case-control design was used. The outcome of 10 patients with hepatorenal syndrome type 2 treated successfully with terlipressin and then with midodrine (7.5-12.5mg/tid) was compared with that of an historical control group of hepatorenal syndrome type 2 patients responders to treatment with terlipressin. Patients and controls were matched by age, plasma renin activity (PRA) levels and severity of renal and liver failure. Cases and controls were similar with respect to pre-treatment with terlipressin. The hepatorenal syndrome recurrence probability was the same in the two groups (cases and control: 9/10, 90%, p=ns). No significant differences were found between cases and controls with respect to serum creatinine (1.9+/-0.1mg/dl vs. 2+/-0.2mg/dl), blood creatinine clearance (28+/-5ml/min vs. 24+/-5ml/min), urinary sodium excretion (12+/-6mequiv./d vs. 19+/-4mequiv./d) and PRA levels (17+/-3ng/ml/h) vs. 20+/-3ng/ml/h) after terlipressin withdrawal (p=ns). These results show that in patients responders to terlipressin hepatorenal syndrome recurrence is not different between patients treated with midodrine and subjects who did not receive vasoconstrictor treatment after terlipressin withdrawal. These data suggest that midodrine is not effective in preventing hepatorenal syndrome type 2 recurrence.

  2. Anti-Interferon Autoantibodies in Autoimmune Polyendocrinopathy Syndrome Type 1

    PubMed Central

    Meager, Anthony; Visvalingam, Kumuthini; Peterson, Pärt; Möll, Kaidi; Murumägi, Astrid; Krohn, Kai; Eskelin, Petra; Perheentupa, Jaakko; Husebye, Eystein; Kadota, Yoshihisa; Willcox, Nick

    2006-01-01

    Background The autoimmune regulator (AIRE) gene influences thymic self-tolerance induction. In autoimmune polyendocrinopathy syndrome type 1 (APS1; OMIM 240300), recessive AIRE mutations lead to autoimmunity targetting endocrine and other epithelial tissues, although chronic candidiasis usually appears first. Autoimmunity and chronic candidiasis can associate with thymomas as well. Patients with these tumours frequently also have high titre immunoglobulin G autoantibodies neutralising type I interferon (IFN)–α and IFN-ω, which are secreted signalling proteins of the cytokine superfamily involved in both innate and adaptive immunity. Methods and Findings We tested for serum autoantibodies to type I IFNs and other immunoregulatory cytokines using specific binding and neutralisation assays. Unexpectedly, in 60/60 Finnish and 16/16 Norwegian APS1 patients with both AIRE alleles mutated, we found high titre neutralising immunoglobulin G autoantibodies to most IFN-α subtypes and especially IFN-ω (60% homologous to IFN-α)—mostly in the earliest samples. We found lower titres against IFN-β (30% homologous to IFN-α) in 23% of patients; two-thirds of these (from Finland only) also had low titres against the distantly related “type III IFN” (IFN-λ1; alias interleukin-29). However, autoantibodies to the unrelated type II IFN, IFN-γ, and other immunoregulatory cytokines, such as interleukin-10 and interleukin-12, were much rarer and did not neutralise. Neutralising titres against type I IFNs averaged even higher in patients with APS1 than in patients with thymomas. Anti–type I IFN autoantibodies preceded overt candidiasis (and several of the autoimmune disorders) in the informative patients, and persisted for decades thereafter. They were undetectable in unaffected heterozygous relatives of APS1 probands (except for low titres against IFN-λ1), in APS2 patients, and in isolated cases of the endocrine diseases most typical of APS1, so they appear to be APS1

  3. Molecular defects in Sanfilippo syndrome type B (mucopolysaccharidosis IIIB).

    PubMed

    Beesley, C E; Jackson, M; Young, E P; Vellodi, A; Winchester, B G

    2005-01-01

    Sanfilippo syndrome type B (mucopolysaccharidosis IIIB) is an autosomal recessive disease that is caused by the deficiency of the lysosomal enzyme alpha-N-acetylglucosaminidase (NAGLU). NAGLU is involved in the degradation of the glycosaminoglycan (GAG) heparan sulphate, and a deficiency results in the accumulation of partially degraded GAGs inside lysosomes. Early clinical symptoms include hyperactivity, aggressiveness and delayed development, followed by progressive mental deterioration, although there are a small number of late-onset attenuated cases. The gene for NAGLU has been fully characterized and we report the molecular analysis of 18 Sanfilippo B families. In total, 34 of the 36 mutant alleles were characterized in this study and 20 different mutations were identified including 8 novel changes (R38W, V77G, 407-410del4, 703delT, A246P, Y335C, 1487delT, E639X). The four novel missense mutations were transiently expressed in Chinese hamster ovary cells and all were shown to decrease the NAGLU activity markedly, although A246P did produce 12.7% residual enzyme activity.

  4. [Oral diseases in auto-immune polyendocrine syndrome type 1].

    PubMed

    Proust-Lemoine, Emmanuelle; Guyot, Sylvie

    2017-07-03

    Auto-immune polyendocrine syndrome type 1 (APS1) also called Auto-immune Polyendocrinopathy Candidiasis Ectodermal Dystrophy (APECED) is a rare monogenic childhood-onset auto-immune disease. This autosomal recessive disorder is caused by mutations in the auto-immune regulator (AIRE) gene, and leads to autoimmunity targeting peripheral tissues. There is a wide variability in clinical phenotypes in patients with APSI, with auto-immune endocrine and non-endocrine disorders, and chronic mucocutaneous candidiasis. These patients suffer from oral diseases such as dental enamel hypoplasia and candidiasis. Both are frequently described, and in recent series, enamel hypoplasia and candidiasis are even the most frequent components of APS1 together with hypoparathyroidism. Both often occur during childhood (before 5 years old for canrdidiasis, and before 15 years old for enamel hypoplasia). Oral candidiasis is recurrent all life long, could become resistant to azole antifungal after years of treatment, and be carcinogenic, leading to severe oral squamous cell carcinoma. Oral components of APS1 should be diagnosed and rigorously treated. Dental enamel hypoplasia and/or recurrent oral candidiasis in association with auto-immune diseases in a young child should prompt APS1 diagnosis. Copyright © 2017 Elsevier Masson SAS. All rights reserved.

  5. [Fabry's disease: an example of cardiorenal syndrome type 5].

    PubMed

    Villa, Gianluca; Romagnoli, Stefano; Sharma, Aashish; Ronco, Claudio

    2017-03-01

    Fabry's disease (FD) is a severe congenital metabolic disorder characterized by the deficient activity of lysosomal exoglycohydrolase alpha-galactosidase, characterized by glycosphingolipid deposition in several cells, such as capillary endothelial cells, renal, cardiac, and nerve cells. As a systemic disease leading to a contemporaneous myocardial and renal dysfunction, FD might be an example of cardiorenal syndrome type 5 (CRS-5). Kidney damage is commonly characterized by proteinuria, isosthenuria and altered tubular function when occurs at the second-third decade, azotemia and end-stage renal disease in third-fifth decade. Beyond the irreversible glomerular, tubular and vascular damages, the podocytes foot process effacement is the major cause of kidney dysfunction. Myocardial damage is usually observed with right and left ventricular hypertrophy, arrhythmias (due to sinus node and conduction system impairment), diastolic dysfunction, congestive heart failure, myocardial ischemia, fibrosis and cardiac death. The enzymatic replacement therapy is essential for the management of FD, as well as the control of renal (with anti-proteinuric agents such as angiotensin-converting enzyme inhibitors- and/or angiotensin II receptor blockers), brain (coated aspirin, clopidogrel and statins to prevent strokes) and heart complications (calcium channel blockers for ischemic cardiomyopathy, warfarin and amiodarone or cardioverter device for arrhythmias). Copyright by Società Italiana di Nefrologia SIN, Rome, Italy.

  6. Evidence based guidelines for complex regional pain syndrome type 1

    PubMed Central

    2010-01-01

    Background Treatment of complex regional pain syndrome type I (CRPS-I) is subject to discussion. The purpose of this study was to develop multidisciplinary guidelines for treatment of CRPS-I. Method A multidisciplinary task force graded literature evaluating treatment effects for CRPS-I according to their strength of evidence, published between 1980 to June 2005. Treatment recommendations based on the literature findings were formulated and formally approved by all Dutch professional associations involved in CRPS-I treatment. Results For pain treatment, the WHO analgesic ladder is advised with the exception of strong opioids. For neuropathic pain, anticonvulsants and tricyclic antidepressants may be considered. For inflammatory symptoms, free-radical scavengers (dimethylsulphoxide or acetylcysteine) are advised. To promote peripheral blood flow, vasodilatory medication may be considered. Percutaneous sympathetic blockades may be used to increase blood flow in case vasodilatory medication has insufficient effect. To decrease functional limitations, standardised physiotherapy and occupational therapy are advised. To prevent the occurrence of CRPS-I after wrist fractures, vitamin C is recommended. Adequate perioperative analgesia, limitation of operating time, limited use of tourniquet, and use of regional anaesthetic techniques are recommended for secondary prevention of CRPS-I. Conclusions Based on the literature identified and the extent of evidence found for therapeutic interventions for CRPS-I, we conclude that further research is needed into each of the therapeutic modalities discussed in the guidelines. PMID:20356382

  7. Cognitive development in patients with Mucopolysaccharidosis type III (Sanfilippo syndrome)

    PubMed Central

    2011-01-01

    Background Mucopolysaccharidosis type III (MPS III, Sanfilippo syndrome) is a lysosomal storage disorder caused by a deficiency of one of the enzymes involved in the degradation of heparan sulfate. MPS III is characterized by progressive mental deterioration resulting in severe dementia. A number of potentially disease-modifying therapies are studied. As preservation of cognitive function is the ultimate goal of treatment, assessment of cognitive development will be essential in order to evaluate treatment efficacy. However, no large scale studies on cognitive levels in MPS III patients, using formal psychometric tests, have been reported. Methods We aimed to assess cognitive development in all 73 living patients with MPS III in the Netherlands. Results Cognitive development could be assessed in 69 patients. In 39 of them developmental level was estimated > 3 months and formal psychometric testing was attempted. A remarkable variation in the intellectual disability was detected. Conclusions Despite special challenges encountered, testing failed in only three patients. The observed broad variation in intellectual disability, should be taken into account when designing therapeutic trials. PMID:21689409

  8. Fatty acid analogue N-arachidonoyl taurine restores function of IKs channels with diverse long QT mutations

    PubMed Central

    Liin, Sara I; Larsson, Johan E; Barro-Soria, Rene; Bentzen, Bo Hjorth; Larsson, H Peter

    2016-01-01

    About 300 loss-of-function mutations in the IKs channel have been identified in patients with Long QT syndrome and cardiac arrhythmia. How specific mutations cause arrhythmia is largely unknown and there are no approved IKs channel activators for treatment of these arrhythmias. We find that several Long QT syndrome-associated IKs channel mutations shift channel voltage dependence and accelerate channel closing. Voltage-clamp fluorometry experiments and kinetic modeling suggest that similar mutation-induced alterations in IKs channel currents may be caused by different molecular mechanisms. Finally, we find that the fatty acid analogue N-arachidonoyl taurine restores channel gating of many different mutant channels, even though the mutations are in different domains of the IKs channel and affect the channel by different molecular mechanisms. N-arachidonoyl taurine is therefore an interesting prototype compound that may inspire development of future IKs channel activators to treat Long QT syndrome caused by diverse IKs channel mutations. DOI: http://dx.doi.org/10.7554/eLife.20272.001 PMID:27690226

  9. Understanding vascular-type Ehlers-Danlos syndrome and avoiding vascular complications

    PubMed Central

    Fenves, Andrew Z.

    2017-01-01

    Vascular-type Ehlers-Danlos syndrome (EDS) is a rare inherited connective tissue disorder caused by a mutation in type III procollagen. It has the highest mortality rate among the six types of EDS. Patients with this syndrome often have typical medical histories and a characteristic physical examination. We present two patients with this rare disorder and highlight the diagnostic and treatment challenges. PMID:28127132

  10. Influence of Meals and Glycemic Changes on QT Interval Dynamics.

    PubMed

    Cirincione, Brenda; Sager, Philip T; Mager, Donald E

    2017-08-01

    Thorough QT/QTc studies have become an integral part of early drug development programs, with major clinical and regulatory implications. This analysis expands on existing pharmacodynamic models of QT interval analysis by incorporating the influence of glycemic changes on the QT interval in a semimechanistic manner. A total of 21 healthy subjects enrolled in an open-label phase 1 pilot study and provided continuous electrocardiogram monitoring and plasma glucose and insulin concentrations associated with a 24-hour baseline assessment. The data revealed a transient decrease in QTc, with peak suppression occurring approximately 3 hours after the meal. A semimechanistic modeling approach was applied to evaluate temporal delays between meals and subsequent changes that might influence QT measurements. The food effect was incorporated into a model of heart rate dynamics, and additional delayed effects of the meal on QT were incorporated using a glucose-dependent hypothetical transit compartment. The final model helps to provide a foundation for the future design and analysis of QT studies that may be confounded by meals. This study has significant implications for QT study assessment following a meal or when a cohort is receiving a medication that influences postprandial glucose concentrations. © 2017, The Authors. The Journal of Clinical Pharmacology published by Wiley Periodicals, Inc. on behalf of American College of Clinical Pharmacology.

  11. Frequency and cause of transient QT prolongation after surgery.

    PubMed

    Joyce, Daniel D; Bos, J Martijn; Haugaa, Kristina H; Tarrell, Robert F; Morlan, Bruce W; Caraballo, Pedro J; Ackerman, Michael J