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Sample records for mechanical prosthetic valve

  1. Mechanical Prosthetic Valves and Pregnancy

    PubMed Central

    Panduranga, Prashanth; El-Deeb, Mohammed; Jha, Chitra

    2014-01-01

    Choosing the best anticoagulant therapy for a pregnant patient with a mechanical prosthetic valve is controversial and the published international guidelines contain no clear-cut consensus on the best approach. This is due to the fact that there is presently no anticoagulant which can reliably decrease thromboembolic events while avoiding damage to the fetus. Current treatments include either continuing oral warfarin or substituting warfarin for subcutaneous unfractionated heparin or low-molecular-weight heparin (LMWH) in the first trimester (6–12 weeks) or at any point throughout the pregnancy. However, LMWH, while widely-prescribed, requires close monitoring of the blood anti-factor Xa levels. Unfortunately, facilities for such monitoring are not universally available, such as within hospitals in developing countries. This review evaluates the leading international guidelines concerning anticoagulant therapy in pregnant patients with mechanical prosthetic valves as well as proposing a simplified guideline which may be more relevant to hospitals in this region. PMID:25364545

  2. Guide to prosthetic cardiac valves

    SciTech Connect

    Morse, D.; Steiner, R.M.; Fernandez, J.

    1985-01-01

    This book contains 10 chapters. Some of the chapter titles are: The development of artificial heart valves: Introduction and historical perspective; The radiology of prosthetic heart valves; The evaluation of patients for prosthetic valve implantation; Pathology of cardiac valve replacement; and Bioengineering of mechanical and biological heart valve substitutes.

  3. Unusual mechanism of myocardial infarction in prosthetic valve endocarditis

    PubMed Central

    Atik, Fernando A; Campos, Vanessa G; da Cunha, Claudio R; de Oliveira, Felipe Bezerra Martins; Otto, Maria Estefânia Bosco; Monte, Guilherme U

    2015-01-01

    A 46-year-old man with bicuspid aortic valve and severe calcific aortic stenosis was submitted to aortic valve replacement with a stented bioprosthesis. He developed Staphylococcus epidermidis prosthetic valve endocarditis a month later, presenting in the emergency room with acute myocardial infarction. The mechanism of myocardial ischemia was a large aortic root abscess causing left main extrinsic compression. He was urgently taken to the operating room, and an aortic root replacement with cryopreserved homograft was performed, associated with autologous pericardium patch closure of aortic to right atrium fistula and coronary artery bypass grafting of the left anterior descending. After a difficult postoperative period with multiple problems, he was eventually discharged home. At 36-month follow-up, he is asymptomatic with no recurrent infection, and the left main coronary artery is widely patent on control chest computed tomography. PMID:26045678

  4. A global perspective on mechanical prosthetic heart valve thrombosis: Diagnostic and therapeutic challenges

    PubMed Central

    Gürsoy, Mustafa Ozan; Kalçık, Macit; Yesin, Mahmut; Karakoyun, Süleyman; Bayam, Emrah; Gündüz, Sabahattin; Özkan, Mehmet

    2016-01-01

    Prosthetic valve thrombosis is one of the major causes of primary valve failure, which can be life-threatening. Multimodality imaging is necessary for determination of leaflet immobilization, cause of underlying pathology (thrombus versus pannus or both), and whether thrombolytic therapy attempt in the patient would be successful or surgery is needed. Current guidelines for the management of prosthetic valve thrombosis lack definitive class I recommendations due to lack of randomized controlled trials, and usually leave the choice of treatment to the clinician’s experience. In this review, we aimed to summarize the pathogenesis, diagnosis, and management of mechanical prosthetic valve thrombosis. PMID:28005024

  5. Prosthetic valve endocarditis: an overview.

    PubMed

    Gnann, J W; Dismukes, W E

    1983-12-01

    Infection of an intracardiac prosthesis, the incidence of which is about 2.5% among patients having undergone valve replacement, is a serious complication with considerable morbidity and mortality. Early prosthetic valve endocarditis (PVE), with an onset within 60 days of valve replacement, accounts for approximately one-third of all cases, while the remaining two-thirds, occur more than two months postoperatively (late prosthetic valve endocarditis). Prosthetic valve endocarditis is most commonly caused by Staphylococcus epidermidis, less frequently by viridans streptococci, Staphylococcus aureus, and gram-negative bacilli. The most likely pathogenetic mechanisms in prosthetic valve endocarditis are intraoperative contamination and postoperative infections at extracardiac sites. Prominent clinical features include fever, new or changing heart murmurs, leukocytosis, anemia and hematuria. The etiologic microorganism can be isolated in more than 90% of all cases. Patients with proven prosthetic valve endocarditis should be examined daily to detect signs of congestive heart failure and changes in murmurs; electrocardiographic monitoring is essential for documentation of arrhythmias. With limitations, echocardiography, especially two-dimensional, may help to demonstrate vegetations or valvular dehiscence. Cinefluoroscopy may reveal loosening or dehiscence of the sewing ring or impaired motion of a radio-opaque poppet due to thrombus or vegetation. Cardiac catheterization, not always necessary even when surgical intervention is anticipated, may provide valuable information on the degree of dysfunction, multiple valve involvement, left ventricular function and extent of concomitant coronary artery disease. In patients with mechanical valves, prosthetic valve endocarditis may be associated with a high incidence of valve ring and myocardial abscesses; the reported frequency of valve ring abscesses is lower with porcine heterografts. Infections on mechanical valves

  6. The blower: a useful tool to complete thrombectomy of the mechanical prosthetic valve.

    PubMed

    Aroussi, Aziz Alami; Sami, Ibrahim Mohamed; Leguerrier, Alain; Verhoye, Jean Phillippe

    2006-05-01

    Thrombectomy could be an excellent approach on one condition (ie, that all parts of the thrombus are removed). We propose to use a tool (ie, the blower) to complete thrombectomy of the prosthetic mechanical valve. The blower is a vaporizer that mixes air and heparinized saline with regulator of flow and proportion used in beating heart surgery. For thrombectomy, we have modified the air-water mixing part and intensity until we obtained a jet that enabled us to remove the micro thrombus that covered the prosthetic valve and surrounding tissues. The blower completely cleaned the prosthetic valve. With this tool, thrombectomy seems easier, more complete, and more reliable with the advantages of short cross-clamping time.

  7. A rare case of prosthetic endocarditis and dehiscence in a mechanical valved conduit

    PubMed Central

    Kannan, Arun; Smith, Cristy; Subramanian, Sreekumar; Janardhanan, Rajesh

    2014-01-01

    A middle-aged adult patient with a history of aortic root replacement with a mechanical valved conduit and remote chest trauma was referred to our institution with prosthetic endocarditis. Transoesophageal echocardiogram at our institution confirmed a near-complete dehiscence of the prosthetic aortic valve from the conduit, with significant perivalvular flow forming a pseudoaneurysm. The patient underwent a high-risk re-operation, involving redo aortic root replacement with a homograft after extensive debridement of the infected tissue. The patient was discharged to an outside facility after an uncomplicated hospital course, and remains stable. PMID:24510692

  8. A rare case of prosthetic endocarditis and dehiscence in a mechanical valved conduit.

    PubMed

    Kannan, Arun; Smith, Cristy; Subramanian, Sreekumar; Janardhanan, Rajesh

    2014-02-07

    A middle-aged adult patient with a history of aortic root replacement with a mechanical valved conduit and remote chest trauma was referred to our institution with prosthetic endocarditis. Transoesophageal echocardiogram at our institution confirmed a near-complete dehiscence of the prosthetic aortic valve from the conduit, with significant perivalvular flow forming a pseudoaneurysm. The patient underwent a high-risk re-operation, involving redo aortic root replacement with a homograft after extensive debridement of the infected tissue. The patient was discharged to an outside facility after an uncomplicated hospital course, and remains stable.

  9. Mechanical prosthetic valve disease is related with an increase in depression and anxiety disorder.

    PubMed

    Turker, Yasemin; Ongel, Kurtulus; Ozaydin, Mehmet; Turker, Yasin; Yildirim Bas, Funda; Akkaya, Mehmet

    2015-02-01

    Patients with organic disease can present with psychiatric symptoms. We hypothesized that since patients with prosthetic heart valve require frequent hospital followup and are at higher risk for complications, the incidence of depression and anxiety is higher in these patients. This cross-sectional study prospectively studied 98 consecutive patients with mechanical prosthetic heart valve. All patients fulfilled prosthetic heart valve evaluation form, Beck Depression Inventory (BDI) and Hamilton Anxiety Scale (HAS). Complete blood count, basic metabolic panel and echocardiogram results were collected for all the patients. Using the BDI, there were 26 patients (27%) with no depression, 20 (20%) with mild depression, 38 (39%) with moderate, 4 (4%) with severe and 10 (10%) patients with very severe depression. Avarege score was 18.3±11.4 on BDI and 19.1±11.1 on HAS. The depression level was positively associated with prothrombin time (p les than 0.001) and international normalized ratio (INR) level (p les than 0.001). Hamilton Anxiety Scale was significantly correlated with comorbidities (r: 0.344; p=0.002), blood transfusion (r: 0.370; p les than 0.001), obesity (r: 0.319; p=0.007) and Beck Depression Scale was correlated with comorbidities (r: 0.328; p=0.002), in patients with prosthetic heart valve disease. Patients with prosthetic heart valve have higher prevalence of depression and higher scores of anxiety and depression. Early recognition and appropriate treatment of depression and anxiety may decrease the morbidity in prosthetic heart valve disease. Besides, use of new oral anticoagulant agents that do not need INR check, could decrease anxiety and depression in the future.

  10. [A rare case of two mechanisms of prosthetic valve dysfunction in the same patient].

    PubMed

    Cardoso, Gonçalo; Trabulo, Marisa; Andrade, Maria João; Ribeiras, Regina; Rodrigues, Rui; Neves, José Pedro; Queiróz e Melo, João; Mendes, Miguel

    2013-12-01

    Prosthetic valve dysfunction is a significant clinical event. Determining its etiological mechanism and severity can be difficult. The authors present the case of a 50-year-old man, with two mechanical valve prostheses in aortic and mitral positions, hospitalized for decompensated heart failure. He had a long history of rheumatic multivalvular disease and had undergone three heart surgeries. On admission, investigation led to a diagnosis of severe dysfunction of both mechanical prostheses with different etiologies and mechanisms: pannus formation in the prosthetic aortic valve and intermittent dysfunction of the mitral prosthesis due to interference of a ruptured chorda tendinea in closure of the disks. The patient was reoperated, leading to significant improvement in functional class. Copyright © 2013 Sociedade Portuguesa de Cardiologia. Published by Elsevier España. All rights reserved.

  11. When and how does nonstructural mechanical prosthetic heart valve dysfunction occur?

    PubMed

    Misawa, Yoshio; Saito, Tsutomu; Konishi, Hiroaki; Oki, Shin-ichi; Kaminishi, Yuichiro; Takahashi, Hideki; Aizawa, Kei; Kamisawa, Osamu; Kato, Morito; Fuse, Katsuo

    2003-08-01

    We discuss the clinical aspects related to mechanical valve dysfunction based upon 20 years' experience of our cases. Between January 1982 and December 2001, 21 patients underwent surgical interventions because of mechanical valve dysfunction. Thirteen men and 8 women (mean age 47 +/- 20, range 3-75 years-old), were included. Mitral valve dysfunction was observed in 12 patients. Prosthetic valve stenosis occurred in 6 patients between 2 and 224 months, and paravalvular leaks in 4 between 1 and 71 months after surgery. The other 2 patients suffered from hemolytic anemia with mild paravalvular leaks between 102 and 104 months after surgery. Aortic valve dysfunction was observed in 8 patients including 3 stenotic lesions between 48 and 97 months and 5 paravalvular leaks between 3 and 150 months after surgery. Tricuspid regurgitation was seen in 1 patient with a huge right atrium at 42 months after surgery. Early death was seen in 1 patient. Late death occurred in 1 patient, 17 years after operation. Survival, including early death, was 95.2%, at 10 and 15 years. One valve-related complication of bioprosthetic valve endocarditis at the mitral and tricuspid positions occurred 12 years after a reoperation. The freedom from complications was 95.2% at 10 years, and 76.2% at 15 years. Paravalvular leaks without overt endocarditis had latency periods of up to 12 years, and pannus formation was observed 20 years after surgery. Early and late clinical results after surgery for mechanical valve dysfunction were excellent.

  12. AB0 blood types: impact on development of prosthetic mechanical valve thrombosis.

    PubMed

    Astarcıoğlu, Mehmet Ali; Kalçık, Macit; Yesin, Mahmut; Gürsoy, Mustafa Ozan; Şen, Taner; Karakoyun, Süleyman; Gündüz, Sabahattin; Özkan, Mehmet

    2016-11-01

    The non-O alleles of the ABO genotype have been associated with an increased risk of thrombosis. We aimed to assess the association between blood group status and prosthetic valve thrombosis. The association between AB0 blood group status and prosthetic valve thrombosis was assessed in this retrospective study. Transesophageal echocardiography was performed in 149 patients with a diagnosis of prosthetic valve thrombosis and in 192 control subjects. Non-0 blood group type (p<0.001), presence of NYHA class III-IV status (p<0.001), and central nervous system (p<0.001) and non-central nervous system (p<0.001) emboli were significantly more prevalent in prosthetic valve thrombosis patients than in the control subjects. The incidence of ineffective anticoagulation was higher in patients with prosthetic valve thrombosis than in controls (p<0.001), as was the presence of moderate to severe left atrial spontaneous echo contrast (p<0.001). The non-0 blood prosthetic valve thrombosis subgroup had a higher incidence of obstructive thrombi and central nervous system thrombotic events than having 0 blood prosthetic valve thrombosis subgroup. Non-0 blood group, ineffective anticoagulation, left atrial spontaneous echo contrast, and a poor NYHA functional capacity were identified to be the predictors of prosthetic valve thrombosis. Our data demonstrate that patients with non-0 compared with 0 blood groups have higher incidence of prosthetic valve thrombosis and central nervous system embolism and similar rates of non-central nervous system embolism at presentation compared with 0 blood group type. Thus, non-O blood group may be a risk factor that may be prone to the development of prosthetic valve thrombosis in patients with prosthetic heart valves.

  13. Pulsatile prosthetic valve flows.

    PubMed

    Phillips, W M; Snyder, A; Alchas, P; Rosenberg, G; Pierce, W S

    1980-01-01

    The laser Doppler system has been established as a useful tool for eliciting the properties of simulated cardiovascular flows, and thus for comparative studies of flow properties of prosthetic valves. Significant differences among valve types and between models of one type have been documented. The complex variations of velocity profiles with time show that comparisons must be made for unsteady pulsatile rather than steady flow, despite the volume and complexity of the data required. Future studies will include methods of compacting the data presentation and improving the details of the experimental stimulation.

  14. Maternal and Fetal Outcomes in Pregnant Women with a Prosthetic Mechanical Heart Valve

    PubMed Central

    Ayad, Sherif W.; Hassanein, Mahmoud M.; Mohamed, Elsayed A.; Gohar, Ahmed M.

    2016-01-01

    BACKGROUND Pregnancy is associated with several cardiocirculatory changes that can significantly impact underlying cardiac disease. These changes include an increase in cardiac output, sodium, and water retention leading to blood volume expansion, and reductions in systemic vascular resistance and systemic blood pressure. In addition, pregnancy results in a hypercoagulable state that increases the risk of thromboembolic complications. OBJECTIVES The aim of this study is to assess the maternal and fetal outcomes of pregnant women with mechanical prosthetic heart valves (PHVs). METHODS This is a prospective observational study that included 100 pregnant patients with cardiac mechanical valve prostheses on anticoagulant therapy. The main maternal outcomes included thromboembolic or hemorrhagic complications, prosthetic valve thrombosis, and acute decompensated heart failure. Fetal outcomes included miscarriage, fetal death, live birth, small-for-gestational age, and warfarin embryopathy. The relationship between the following were observed: – Maternal and fetal complications and the site of the replaced valve (mitral, aortic, or double)– Maternal and fetal complications and warfarin dosage (≤5 mg, >5 mg)– Maternal and fetal complications and the type of anticoagulation administered during the first trimester RESULTS This study included 60 patients (60%) with mitral valve replacement (MVR), 22 patients (22%) with aortic valve replacement (AVR), and 18 patients (18%) with double valve replacement (DVR). A total of 65 patients (65%) received >5 mg of oral anticoagulant (warfarin), 33 patients (33%) received ≤5 mg of warfarin, and 2 patients (2%) received low-molecular-weight heparin (LMWH; enoxaparin sodium) throughout the pregnancy. A total of 17 patients (17%) received oral anticoagulant (warfarin) during the first trimester: 9 patients received a daily warfarin dose of >5 mg while the remaining 8 patients received a daily dose of ≤5 mg. Twenty

  15. [Thrombolysis in mechanical prosthetic valve thrombosis. Its management with streptokinase].

    PubMed

    Solorio, S; Sánchez, H; Madrid, R; Badui, E; Valdespino, A; Murillo, H; Rangel, A; Enciso, R

    1994-01-01

    We present the first experience in Mexico in 10 patients, 9 female and 1 male with an average age of 42.5 years. All patients had clinical, echocardiographic and fluoroscopic criteria of dysfunctioning mechanical valvular prosthesis due to thrombosis (9 Sorin type and 1 Starr-Edwards). None of the patients had contraindications for thrombolytic therapy. All cases were treated with intravenous streptokinase: 250,000 U in 30 minutes followed by an infusion of 100,000 U per hour, always under clinical, echocardiographic and fluoroscopic control every 2 and 24 hours respectively until the normalization of the clinical and hemodynamic parameters with a top limit of 72 hour. The average duration of the thrombolysis was 54 +/- 6.1 hours with an average total doses of 5' 200,000 U of streptokinase. In 90% of the cases there was an increase in the valvular area: mitral (n = 7), from 1.02 +/- 0.21 to 1.75 +/- 0.36 cm2 (p < 0.001), while the mean transvalvular gradient decreased from 10.42 +/- 3.77 to 3.42 +/- 0.975 mmHg (p < 0.001); the systolic pulmonary artery pressure also decreased from 53.7 +/- 15.29 to 35 +/- 2 mmHg (p < 0.001). In the tricuspid prosthesis (n = 2) the average valvular area was increased from 0.8 +/- 0.44 to 1.55 +/- 0.77 cm2, decreasing proportionally the mean transvalvular gradient from 12.5 +/- 2 to 4.5 +/- 3.5 mmHg with no changes in the systolic pressure of the pulmonary artery. In the Starr-Edwards prosthesis in aortic position (n = 1), no hemodynamic changes were observed.(ABSTRACT TRUNCATED AT 250 WORDS)

  16. Sixty-Four-Section Cardiac Computed Tomography in Mechanical Prosthetic Heart Valve Dysfunction: Thrombus or Pannus.

    PubMed

    Gündüz, Sabahattin; Özkan, Mehmet; Kalçik, Macit; Gürsoy, Ozan Mustafa; Astarcioğlu, Mehmet Ali; Karakoyun, Süleyman; Aykan, Ahmet Çağri; Biteker, Murat; Gökdeniz, Tayyar; Kaya, Hasan; Yesin, Mahmut; Duran, Nilüfer Ekşi; Sevinç, Deniz; Güneysu, Tahsin

    2015-12-01

    Distinguishing pannus and thrombus in patients with prosthetic valve dysfunction is essential for the selection of proper treatment. We have investigated the utility of 64-slice multidetector computed tomography (MDCT) in distinguishing between pannus and thrombus, the latter amenable to thrombolysis. Sixty-two (23 men, mean age 44±14 years) patients with suspected mechanical prosthetic valve dysfunction assessed by transesophageal echocardiography were included in this prospective observational trial. Subsequently, MDCT was performed before any treatment was started. Periprosthetic masses were detected by MDCT in 46 patients, and their attenuation values were measured as Hounsfield Units (HU). Patients underwent thrombolysis unless contraindicated, and those with a contraindication or failed thrombolysis underwent surgery. A mass which was completely lysed or surgically detected as a clot was classified as thrombus, whereas a mass which was surgically detected as tissue overgrowth was classified as pannus. A definitive diagnosis could be achieved in 37 patients with 39 MDCT masses (22 thrombus and 17 pannus). The mean attenuation value of 22 thrombotic masses was significantly lower than that in 17 pannus (87±59 versus 322±122; P<0.001). Area under the receiver operating characteristic curve was 0.96 (95% confidence interval: 0.91-0.99; P<0.001), and a cutoff point of HU≥145 provided high sensitivity (87.5%) and specificity (95.5%) in discriminating pannus from thrombus. Complete lysis was more common for masses with HU<90 compared with those with HU 90 to 145 (100% versus 42.1%; P=0.007). Sixty-four slice MDCT is helpful in identifying masses amenable to thrombolysis in patients with prosthetic valve dysfunction. A high (HU≥145) attenuation suggests pannus overgrowth, whereas a lower value is associated with thrombus formation. A higher attenuation (HU>90) is associated with reduced lysis rates. © 2015 American Heart Association, Inc.

  17. Prosthetic valve endocarditis. A survey.

    PubMed Central

    Ben Ismail, M; Hannachi, N; Abid, F; Kaabar, Z; Rougé, J F

    1987-01-01

    Fifty eight patients (aged 8-59 years, mean 27) treated for prosthetic valve endocarditis from January 1966 to January 1985 were studied retrospectively by review of case notes. There were 12 cases of early and 46 cases of late prosthetic valve endocarditis. These developed in 28 patients with an isolated aortic valve, in 26 with an isolated mitral valve, and in four with both aortic and mitral prosthetic valves. Streptococci were the most commonly isolated microorganisms, followed by staphylococci, Gram negative bacteria, and fungi. A surgical (34 cases) or a necropsy specimen (10 cases) from 44 cases was examined. Eighty two per cent of the patients had congestive heart failure. Twenty four of the 58 patients were medically treated and 17 died (70% mortality). Combined medical and surgical treatment was used in 34 patients; the main indication for surgery was congestive heart failure. Fourteen patients on combined treatment died (40% mortality). Persistent sepsis and prosthetic valve dehiscence were the most common early and late operative complications. The most important influences on outcome were congestive heart failure, the type of micro-organism, the severity and extent of anatomical lesions, the time of onset of prosthetic valve endocarditis, and the type of treatment. This survey indicates that only patients without congestive heart failure or embolic complications and with sensitive micro-organism should be treated medically. In view of the poor prognosis patients with prosthetic valve endocarditis associated with congestive heart failure, persistent sepsis, and repeat arterial emboli should be treated by early surgical intervention. PMID:3620246

  18. Prediction of thrombus-related mechanical prosthetic valve dysfunction using transesophageal echocardiography

    NASA Technical Reports Server (NTRS)

    Lin, S. S.; Tiong, I. Y.; Asher, C. R.; Murphy, M. T.; Thomas, J. D.; Griffin, B. P.

    2000-01-01

    Identification of thrombus-related mechanical prosthetic valve dysfunction (MPVD) has important therapeutic implications. We sought to develop an algorithm, combining clinical and echocardiographic parameters, for prediction of thrombus-related MPVD in a series of 53 patients (24 men, age 52 +/- 16 years) who had intraoperative diagnosis of thrombus or pannus from 1992 to 1997. Clinical and echocardiographic parameters were analyzed to identify predictors of thrombus and pannus. Prevalence of thrombus and diagnostic yields relative to the number of predictors were determined. There were 22 patients with thrombus, 19 patients with pannus, and 12 patients with both. Forty-two of 53 masses were visualized using transesophageal echocardiography (TEE), including 29 of 34 thrombi or both thrombi and panni and 13 of 19 isolated panni. Predictors of thrombus or mixed presentation include mobile mass (p = 0.009), attachment to occluder (p = 0.02), elevated gradients (p = 0.04), and an international normalized ratio of < or = 2.5 (p = 0.03). All 34 patients with thrombus or mixed presentation had > or = 1 predictor. The prevalence of thrombus in the presence of < or = 1, 2, and > or = 3 predictors is 14%, 69%, and 91%, respectively. Thus, TEE is sensitive in the identification of abnormal mass in the setting of MPVD. An algorithm based on clinical and transesophageal echocardiographic predictors may be useful to estimate the likelihood of thrombus in the setting of MPVD. In the presence of > or = 3 predictors, the probability of thrombus is high.

  19. Prediction of thrombus-related mechanical prosthetic valve dysfunction using transesophageal echocardiography.

    PubMed

    Lin, S S; Tiong, I Y; Asher, C R; Murphy, M T; Thomas, J D; Griffin, B P

    2000-11-15

    Identification of thrombus-related mechanical prosthetic valve dysfunction (MPVD) has important therapeutic implications. We sought to develop an algorithm, combining clinical and echocardiographic parameters, for prediction of thrombus-related MPVD in a series of 53 patients (24 men, age 52 +/- 16 years) who had intraoperative diagnosis of thrombus or pannus from 1992 to 1997. Clinical and echocardiographic parameters were analyzed to identify predictors of thrombus and pannus. Prevalence of thrombus and diagnostic yields relative to the number of predictors were determined. There were 22 patients with thrombus, 19 patients with pannus, and 12 patients with both. Forty-two of 53 masses were visualized using transesophageal echocardiography (TEE), including 29 of 34 thrombi or both thrombi and panni and 13 of 19 isolated panni. Predictors of thrombus or mixed presentation include mobile mass (p = 0.009), attachment to occluder (p = 0.02), elevated gradients (p = 0.04), and an international normalized ratio of < or = 2.5 (p = 0.03). All 34 patients with thrombus or mixed presentation had > or = 1 predictor. The prevalence of thrombus in the presence of < or = 1, 2, and > or = 3 predictors is 14%, 69%, and 91%, respectively. Thus, TEE is sensitive in the identification of abnormal mass in the setting of MPVD. An algorithm based on clinical and transesophageal echocardiographic predictors may be useful to estimate the likelihood of thrombus in the setting of MPVD. In the presence of > or = 3 predictors, the probability of thrombus is high.

  20. Prediction of thrombus-related mechanical prosthetic valve dysfunction using transesophageal echocardiography

    NASA Technical Reports Server (NTRS)

    Lin, S. S.; Tiong, I. Y.; Asher, C. R.; Murphy, M. T.; Thomas, J. D.; Griffin, B. P.

    2000-01-01

    Identification of thrombus-related mechanical prosthetic valve dysfunction (MPVD) has important therapeutic implications. We sought to develop an algorithm, combining clinical and echocardiographic parameters, for prediction of thrombus-related MPVD in a series of 53 patients (24 men, age 52 +/- 16 years) who had intraoperative diagnosis of thrombus or pannus from 1992 to 1997. Clinical and echocardiographic parameters were analyzed to identify predictors of thrombus and pannus. Prevalence of thrombus and diagnostic yields relative to the number of predictors were determined. There were 22 patients with thrombus, 19 patients with pannus, and 12 patients with both. Forty-two of 53 masses were visualized using transesophageal echocardiography (TEE), including 29 of 34 thrombi or both thrombi and panni and 13 of 19 isolated panni. Predictors of thrombus or mixed presentation include mobile mass (p = 0.009), attachment to occluder (p = 0.02), elevated gradients (p = 0.04), and an international normalized ratio of < or = 2.5 (p = 0.03). All 34 patients with thrombus or mixed presentation had > or = 1 predictor. The prevalence of thrombus in the presence of < or = 1, 2, and > or = 3 predictors is 14%, 69%, and 91%, respectively. Thus, TEE is sensitive in the identification of abnormal mass in the setting of MPVD. An algorithm based on clinical and transesophageal echocardiographic predictors may be useful to estimate the likelihood of thrombus in the setting of MPVD. In the presence of > or = 3 predictors, the probability of thrombus is high.

  1. Valvular Hemolysis Masquerading as Prosthetic Valve Stenosis.

    PubMed

    Sethi, Pooja; Murtaza, Ghulam; Rahman, Zia; Zaidi, Syed; Helton, Thomas; Paul, Timir

    2017-04-08

    The evaluation of prosthetic valves can provide a unique challenge, and a thoughtful approach is required. High output states like anemia should be kept in the differential when evaluating elevated gradients across prosthetic valves. We present the case of a 69-year-old man with a Starr-Edwards prosthetic aortic valve who presented with symptoms of congestive heart failure and high transvalvular pressure gradients. These symptoms indicate a potential prosthetic valve stenosis. His laboratory evaluation results were consistent with valve-related hemolysis. Resolving his anemia led to a resolution of the symptoms and lowered the pressure gradient on follow-up.

  2. Echocardiographic assessment of prosthetic heart valves.

    PubMed

    Blauwet, Lori A; Miller, Fletcher A

    2014-01-01

    Valvular heart disease is a global health problem. It is estimated that more than 280,000 prosthetic heart valves are implanted worldwide each year. As the world's population is aging, the incidence of prosthetic heart valve implantation and the prevalence of prosthetic heart valves continue to increase. Assessing heart valve prosthesis function remains challenging, as prosthesis malfunction is unpredictable but not uncommon. Transthoracic two-dimensional and Doppler echocardiography is the preferred method for assessing prosthetic valve function. Clinically useful Doppler-derived measures for assessing prosthetic valve hemodynamic profiles have been reported for aortic, mitral, and tricuspid valve prostheses, but echocardiographic data regarding pulmonary valve prostheses remain limited. Complete prosthetic valve evaluation by transthoracic echocardiography (TTE) is sometimes challenging due to acoustic shadowing and artifacts. In these cases, further imaging with transesophageal echocardiography, fluoroscopy and/or gated CT may be warranted, particularly if prosthetic valve dysfunction is suspected. Being able to differentiate pathologic versus functional obstruction of an individual prosthesis is extremely important, as this distinction affects management decisions. Transprosthetic and periprosthetic regurgitation may be difficult to visualize on TTE, so careful review of Doppler-derived data combined with a high index of suspicion is warranted, particularly in symptomatic patients. A baseline TTE soon after valve implantation is indicated in order to "fingerprint" the prosthesis hemodynamic profile. It remains unclear how frequently serial imaging should be performed in order to assess prosthetic valve function, as this issue has not been systematically studied.

  3. Time-resolved PIV technique for high temporal resolution measurement of mechanical prosthetic aortic valve fluid dynamics.

    PubMed

    Kaminsky, R; Morbiducci, U; Rossi, M; Scalise, L; Verdonck, P; Grigioni, M

    2007-02-01

    Prosthetic heart valves (PHVs) have been used to replace diseased native valves for more than five decades. Among these, mechanical PHVs are the most frequently implanted. Unfortunately, these devices still do not achieve ideal behavior and lead to many complications, many of which are related to fluid mechanics. The fluid dynamics of mechanical PHVs are particularly complex and the fine-scale characteristics of such flows call for very accurate experimental techniques. Adequate temporal resolution can be reached by applying time-resolved PIV, a high-resolution dynamic technique which is able to capture detailed chronological changes in the velocity field. The aim of this experimental study is to investigate the evolution of the flow field in a detailed time domain of a commercial bileaflet PHV in a mock-loop mimicking unsteady conditions, by means of time-resolved 2D Particle Image Velocimetry (PIV). The investigated flow field corresponded to the region immediately downstream of the valve plane. Spatial resolution as in "standard" PIV analysis of prosthetic valve fluid dynamics was used. The combination of a Nd:YLF high-repetition-rate double-cavity laser with a high frame rate CMOS camera allowed a detailed, highly temporally resolved acquisition (up to 10000 fps depending on the resolution) of the flow downstream of the PHV. Features that were observed include the non-homogeneity and unsteadiness of the phenomenon and the presence of large-scale vortices within the field, especially in the wake of the valve leaflets. Furthermore, we observed that highly temporally cycle-resolved analysis allowed the different behaviors exhibited by the bileaflet valve at closure to be captured in different acquired cardiac cycles. By accurately capturing hemodynamically relevant time scales of motion, time-resolved PIV characterization can realistically be expected to help designers in improving PHV performance and in furnishing comprehensive validation with experimental data

  4. Early mortality after aortic valve replacement with mechanical prosthetic vs bioprosthetic valves among Medicare beneficiaries: a population-based cohort study.

    PubMed

    Du, Dongyi Tony; McKean, Stephen; Kelman, Jeffrey A; Laschinger, John; Johnson, Chris; Warnock, Rob; Worrall, Chris M; Sedrakyan, Art; Encinosa, William; MaCurdy, Thomas E; Izurieta, Hector S

    2014-11-01

    Early mortality for patients who undergo aortic valve replacement (AVR) may differ between mechanical and biological prosthetic (hereinafter referred to as bioprosthetic) valves. Clinical trials may have difficulty addressing this issue owing to limited sample sizes and low mortality rates. To compare early mortality after AVR between the recipients of mechanical and bioprosthetic aortic valves. A retrospective analysis of patients 65 years or older in the Medicare databases who underwent AVR from July 1, 2006, through December 31, 2011. In the mixed-effects models adjusting for physician and hospital random effects, we estimated odds ratios (OR) of early mortality to compare mechanical vs bioprosthetic valves. Mechanical or bioprostheticaortic valve replacement. Early mortality was measured as death on the date of surgery, death within 1 to 30 or 31 to 365 days after the date of surgery, death within 30 days after the date of hospital discharge, and operative mortality (death within 30 days after surgery or at discharge, whichever is longer). Of the 66 453 Medicare beneficiaries who met inclusion criteria, 19 190 (28.88%) received a mechanical valve and 47 263 (71.12%) received a bioprosthetic valve. The risk for death on the date of surgery was 60% higher for recipients of mechanical valves than recipients of bioprosthetic valves (OR, 1.61 [95% CI, 1.27-2.04; P < .001]; risk ratio [RR], 1.60). The risk difference decreased to 16% during the 30 days after the date of surgery (OR, 1.18 [95% CI, 1.09-1.28; P < .001]; RR, 1.16). We found no differences within 31 to 365 days after the date of surgery and within the 30 days after discharge. The risk for operative mortality was 19% higher for recipients of mechanical compared with bioprosthetic valves (OR, 1.21 [95% CI, 1.13-1.30; P < .001]; RR, 1.19). The number needed to treat with mechanical valves to observe 1 additional death on the surgery date was 290; to observe 1 additional death within 30

  5. A rare case of spontaneous rectus sheath haematoma in a patient with mechanical prosthetic aortic and mitral valves.

    PubMed

    Aykan, Ahmet; Oguz, Ali; Yildiz, Mustafa; Özkan, Mehmet

    2012-07-12

    Every year nearly 300 000 patients have heart valve operations and mostly prosthetic valves are inserted. Coumadin is the mainstay of therapy in these individuals but it has many side effects, mostly related to its anticoagulant effect. Rectus sheath haematoma (RSH) is a rare complication of abdominal trauma, surgery and excessive strain, however, anticoagulant agents may predispose to this condition without any precipitating event. Reversal of anticoagulation and resuscitation with fluids and blood products are necessary but anticoagulation is crucial in patients with prosthetic valves, as they have acquired thrombotic diathesis. Herein we report on a case of spontaneous RSH in a patient with prosthetic mitral and aortic valves and a history of prosthetic valve thrombosis. He was successfully managed medically.

  6. [Surgical Treatment of Prosthetic Valve Endocarditis].

    PubMed

    Kaminishi, Yuichiro; Akutsu, Hirohiko; Sugaya, Akira; Kurumisawa, Soki; Takazawa, Ippei; Sato, Hirotaka; Muraoka, Arata; Aizawa, Kei; Ohki, Shinichi; Saito, Tsutomu; Kawahito, Koji; Misawa, Yoshio

    2015-11-01

    Between 2003 and 2014, at Jichi Medical University Hospital, 11 patients with prosthetic valve endocarditis (PVE) underwent re-operation. There was 1 in-hospital death and 2 late deaths. The cause of death was cirrhosis, heart failure and sepsis, respectively. Emergency surgery, previous double valve replacement (DVR) and Staphylococcus infection were common risk factors for all 3 cases. Two cases of patients that survived who underwent mitral valve replacement (MVR) and DVR for PVE after DVR were treated with multiple antibiotic courses for bacteremia associated with hemodialysis and colon cancer. One patient who underwent DVR after mitral valve plasty which was complicated with cerebral hemorrhage, had survived and was discharged. Of the aortic PVE patients, 2 cases of aortic valve replacement (AVR) using a mechanical valve, 1 case of aortic root replacement (ARR) using a mechanical valve, and 1 ARR using the homograft, were considered cured and never relapsed. A patient with aortic PVE, who underwent AVR after cesarean section for heart failure in birth period, has received ARR twice with the mechanical valve for recurrent pseudo-aneurysm of the left ventricular outflow tract. Since hemodialysis and colon cancer is a risk factor for recurrent PVE, it is necessary to consider the long-term administration of antibiotics after surgery.

  7. Prosthetic aortic heart valves: modeling and design.

    PubMed

    Mohammadi, Hadi; Mequanint, Kibret

    2011-03-01

    Although heart valve replacement is among the most common cardiovascular surgical procedures, their outcome is often difficult to predict. One of the reasons is the design and choice of the materials used for the fabrication of the prostheses. This review paper describes the use of modeling techniques in prosthetic heart valve (HV) design and aims at the justification and development of a polymer based trileaflet mechanical heart valve (MHV). The closing/opening phase behavior of the bileaflet MHV was investigated. The potential problem of valve failure due to crack propagation in the brittle pyrolytic carbon leaflet was also discussed. These studies suggest that although bileaflet MHV performs satisfactorily, there are justifications for improvement. Since the native aortic HV is trileaflet and made of anisotropic and hyperelastic tissue, one possible approach to a better MHV design is based on our ability to closely mimic the natural geometry and biomaterial properties.

  8. Horseshoe thrombus in a patient with mechanical prosthetic mitral valve: A case report and review of literature

    PubMed Central

    Mehra, Sanjay; Movahed, Assad; Espinoza, Carlos; Marcu, Constantin B

    2015-01-01

    Patients with prosthetic cardiac valves are at high risk for thromboembolic complications and need life long anticoagulation with warfarin, which can be associated with variable dose requirements and fluctuating level of systemic anticoagulation and may predispose to thromboembolic and or hemorrhagic complications. Prosthetic cardiac valve thrombosis is associated with high morbidity and mortality. A high index of suspicion is essential for prompt diagnosis. Transthoracic echocardiography, and if required transesophageal echocardiography are the main diagnostic imaging modalities. Medically stable patients can be managed with thrombolytic therapy and anticoagulation, while some patients may require surgical thrombectomy or valve replacement. We present a case report of a patient with prosthetic mitral valve and an unusually large left atrial thrombus with both thromboembolic and hemorrhagic complications. PMID:26380832

  9. [Mitral valve replacement for four times with three kinds of prosthetic valve dysfunction].

    PubMed

    Kojima, Nozomi; Ito, Satoshi; Sakano, Yasuhito; Konishi, Hiroaki; Misawa, Yoshio

    2011-03-01

    There are 2 major types of prosthetic valve replacement complications; structural valvular deterioration and nonstructural dysfunction. Nonstructural dysfunction includes valve thrombosis, paravalvular leak, prosthetic valve endocarditis and bleeding event. Primary tissue failure is the most common reason for mitral valve replacement (MVR) with tissue valves, and paravalvular leak is also a common factor of MVR in repeated MVR cases. We report a case of a woman who has undergone MVR for four times. She underwent the 1st MVR with a tissue valve 19 years ago because of mitral valve regurgitation. Nine years after the initial operation, structural valvular deterioration developed and she underwent the 2nd MVR with a mechanical prosthesis. Two years after the 2nd operation, she underwent the 3rd MVR because of repeated prosthetic valve thrombosis. Paravalvular leak was recognized 8 years after the 3rd operation and she underwent the 4th MVR. Her postoperative course was uneventful.

  10. Aortic valve insufficiency in the teenager and young adult: the role of prosthetic valve replacement.

    PubMed

    Bradley, Scott M

    2013-10-01

    The contents of this article were presented in the session "Aortic insufficiency in the teenager" at the congenital parallel symposium of the 2013 Society of Thoracic Surgeons (STS) annual meeting. The accompanying articles detail the approaches of aortic valve repair and the Ross procedure.(1,2) The current article focuses on prosthetic valve replacement. For many young patients requiring aortic valve surgery, either aortic valve repair or a Ross procedure provides a good option. The advantages include avoidance of anticoagulation and potential for growth. In other patients, a prosthetic valve is an appropriate alternative. This article discusses the current state of knowledge regarding mechanical and bioprosthetic valve prostheses and their specific advantages relative to valve repair or a Ross procedure. In current practice, young patients requiring aortic valve surgery frequently undergo valve replacement with a prosthetic valve. In STS adult cardiac database, among patients ≤30 years of age undergoing aortic valve surgery, 34% had placement of a mechanical valve, 51% had placement of a bioprosthetic valve, 9% had aortic valve repair, and 2% had a Ross procedure. In the STS congenital database, among patients 12 to 30 years of age undergoing aortic valve surgery, 21% had placement of a mechanical valve, 18% had placement of a bioprosthetic valve, 30% had aortic valve repair, and 24% had a Ross procedure. In the future, the balance among these options may be altered by design improvements in prosthetic valves, alternatives to warfarin, the development of new patch materials for valve repair, and techniques to avoid Ross autograft failure.

  11. Prosthetic aortic valve selection: current patient experience, preferences and knowledge

    PubMed Central

    Korteland, Nelleke M; Bras, Frans J; van Hout, Fabienne M A; Kluin, Jolanda; Klautz, Robert J M; Bogers, Ad J J C; Takkenberg, Johanna J M

    2015-01-01

    Objective Current clinical practice guidelines advocate shared decision-making (SDM) in prosthetic valve selection. This study assesses among adult patients accepted for aortic valve replacement (AVR): (1) experience with current clinical decision-making regarding prosthetic valve selection, (2) preferences for SDM and risk presentation and (3) prosthetic valve knowledge and numeracy. Methods In a prospective multicentre cohort study, AVR patients were surveyed preoperatively and 3 months postoperatively. Results 132 patients (89 males/43 females; mean age 67 years (range 23–86)) responded preoperatively. Decisional conflict was observed in 56% of patients, and in 25% to such an extent that it made them feel unsure about the decision. 68% wanted to be involved in decision-making, whereas 53% agreed that they actually were. 69% were able to answer three basic knowledge questions concerning prosthetic valves correctly. 56% were able to answer three basic numeracy questions correctly. Three months postsurgery, 90% (n=110) were satisfied with their aortic valve prosthesis, with no difference between mechanical and bioprosthetic valve recipients. Conclusions In current clinical practice, many AVR patients experience decisional conflict and suboptimal involvement in prosthetic valve selection, and exhibit impaired knowledge concerning prosthetic valves and numeracy. Given the broad support for SDM among AVR patients and the obvious need for understandable information, to-be-developed tools to support SDM in the setting of prosthetic valve selection will help to improve quality of decision-making, better inform and actively involve patients, and reduce decisional conflict. Trial registration number NTR3618. PMID:25893105

  12. Percutaneous management of prosthetic valve thrombosis.

    PubMed

    Hariram, Vuppaladadhiam

    2014-01-01

    Thrombosis of a prosthetic valve is a serious complication in patients with prosthetic heart valves. Thrombolysis is the initial choice of treatment. Patients who do not respond to thrombolysis are subjected to surgery which carries a high risk. We report a case series of 5 patients with prosthetic mitral valve thrombosis who did not respond to thrombolysis and were subjected to percutaneous manipulation of the prosthetic valves successfully and improved. Five patients who were diagnosed to have prosthetic mitral valve thrombosis and failed to respond to a minimum of 36 h of thrombolysis (persistent symptoms with increased gradients, abnormal findings on fluoroscopy),were subjected to percutaneous treatment after receiving proper consent. None of them had a visible thrombus on transthoracic echocardiogram. All patients underwent transseptal puncture following which a 6F JR4 guiding catheter was passed into the left atrium. The valve leaflets were repeatedly hit gently under fluoroscopic guidance till they regained their normal mobility. Mean age was 38.8 years. Average peak and mean gradients prior to the procedure were 38 and 25 and after the procedure were 12 and 6 mm of Hg respectively. All patients had successful recovery of valve motion on fluoroscopy with normalization of gradients and complete resolution of symptoms. None of the patients had any focal neurological deficits, embolic manifestations or bleeding complications. Percutaneous manipulation of prosthetic valves in selected patients with prosthetic valve thrombosis who do not respond to thrombolytic therapy is feasible and can be used as an alternative to surgery. Copyright © 2014 Cardiological Society of India. Published by Elsevier B.V. All rights reserved.

  13. 21 CFR 870.3945 - Prosthetic heart valve sizer.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... 21 Food and Drugs 8 2010-04-01 2010-04-01 false Prosthetic heart valve sizer. 870.3945 Section 870...) MEDICAL DEVICES CARDIOVASCULAR DEVICES Cardiovascular Prosthetic Devices § 870.3945 Prosthetic heart valve sizer. (a) Identification. A prosthetic heart valve sizer is a device used to measure the size of...

  14. 21 CFR 870.3945 - Prosthetic heart valve sizer.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... 21 Food and Drugs 8 2014-04-01 2014-04-01 false Prosthetic heart valve sizer. 870.3945 Section 870...) MEDICAL DEVICES CARDIOVASCULAR DEVICES Cardiovascular Prosthetic Devices § 870.3945 Prosthetic heart valve sizer. (a) Identification. A prosthetic heart valve sizer is a device used to measure the size of...

  15. 21 CFR 870.3945 - Prosthetic heart valve sizer.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... 21 Food and Drugs 8 2012-04-01 2012-04-01 false Prosthetic heart valve sizer. 870.3945 Section 870...) MEDICAL DEVICES CARDIOVASCULAR DEVICES Cardiovascular Prosthetic Devices § 870.3945 Prosthetic heart valve sizer. (a) Identification. A prosthetic heart valve sizer is a device used to measure the size of...

  16. 21 CFR 870.3945 - Prosthetic heart valve sizer.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... 21 Food and Drugs 8 2011-04-01 2011-04-01 false Prosthetic heart valve sizer. 870.3945 Section 870...) MEDICAL DEVICES CARDIOVASCULAR DEVICES Cardiovascular Prosthetic Devices § 870.3945 Prosthetic heart valve sizer. (a) Identification. A prosthetic heart valve sizer is a device used to measure the size of...

  17. 21 CFR 870.3945 - Prosthetic heart valve sizer.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... 21 Food and Drugs 8 2013-04-01 2013-04-01 false Prosthetic heart valve sizer. 870.3945 Section 870...) MEDICAL DEVICES CARDIOVASCULAR DEVICES Cardiovascular Prosthetic Devices § 870.3945 Prosthetic heart valve sizer. (a) Identification. A prosthetic heart valve sizer is a device used to measure the size of...

  18. Prosthetic mitral valve thrombosis in pregnancy: from thrombolysis to anticoagulation.

    PubMed

    Cardoso, Gonçalo; Aguiar, Carlos; Andrade, Maria João; Patrício, Lino; Freire, Isabel; Serrano, Fátima; Anjos, Rui; Mendes, Miguel

    2015-01-01

    Pregnant women with mechanical prosthetic heart valves are at increased risk for valve thrombosis. Management decisions for this life-threatening complication are complex. Open-heart surgery has a very high risk of maternal mortality and fetal loss. Bleeding and embolic risks associated with thrombolytic agents, the limited efficacy of thrombolysis in certain subgroups, and a lack of experience in the setting of pregnancy raise important concerns. We report a case of mitral prosthetic valve thrombosis in early pregnancy, which was successfully treated with streptokinase. Ten years later, the same patient had an uneventful pregnancy, throughout which acenocoumarol was maintained. With this case we review the prevention (with oral anticoagulant therapy) and treatment of prosthetic valve thrombosis during pregnancy, which is important for both obstetrician and cardiologist. Copyright © 2014 Sociedade Portuguesa de Cardiologia. Published by Elsevier España. All rights reserved.

  19. Geometry of aortic heart valves. [prosthetic design

    NASA Technical Reports Server (NTRS)

    Karara, H. M.

    1975-01-01

    Photogrammetric measurements of the surface topography of the aortic valves obtained from silicon rubber molds of freshly excised human aortic valves are presented. The data are part of an investigation into the design of a new prosthetic valve which will be a central-flow device, like the real valve and unlike previous central-occluding prostheses. Since the maximum stress on the heart valve is induced when the valve is closed and subject to diastolic back-pressure, it was decided to determine the valve geometry during diastole. That is, the molds were formed by pouring the rubber down the excised aortas, causing the valves to close. The molds were made under different pressures (20-120 torr); photogrammetry served as a vehicle for the assessment of the mold topography through the following outputs: digital models, surface profiles, and contour maps.

  20. Geometry of aortic heart valves. [prosthetic design

    NASA Technical Reports Server (NTRS)

    Karara, H. M.

    1975-01-01

    Photogrammetric measurements of the surface topography of the aortic valves obtained from silicon rubber molds of freshly excised human aortic valves are presented. The data are part of an investigation into the design of a new prosthetic valve which will be a central-flow device, like the real valve and unlike previous central-occluding prostheses. Since the maximum stress on the heart valve is induced when the valve is closed and subject to diastolic back-pressure, it was decided to determine the valve geometry during diastole. That is, the molds were formed by pouring the rubber down the excised aortas, causing the valves to close. The molds were made under different pressures (20-120 torr); photogrammetry served as a vehicle for the assessment of the mold topography through the following outputs: digital models, surface profiles, and contour maps.

  1. Computerized intraoperative calculation of instantaneous prosthetic aortic valve area.

    PubMed

    DiSesa, V J; Lachman, P; Collins, J J; Cohn, L H

    1988-01-01

    Improved assessment of valve area is essential to understanding the performance of prosthetic valves. The authors studied six patients undergoing aortic valve replacement using mechanical (ME) or porcine (PO) prostheses. Instantaneous cardiac output (CO) (L/min) was measured in the aorta using an ultrasonic flow probe. Left ventricular and aortic pressures (mmHg) were measured using Millar catheters. Data were analyzed using an IBM PC-AT. Valve area (cm2) was determined using Gorlin's formula (AG) and a new formula for instantaneous area derived mathematically and using a theoretic constant. AG, mean (AI) and peak (Apk) instantaneous areas were compared to geometric measures of area (Aactual) in vitro. Peak instantaneous area correlates best with measured area. Intraoperative assessment using the ultrasonic flow probe and computer analysis is helpful in understanding the dynamic properties of prosthetic valves in vivo.

  2. Processing of Prosthetic Heart Valve Sounds from Anechoic Tank Measurements

    SciTech Connect

    Candy, J V; Meyer, A W

    2001-03-20

    People with serious cardiac problems have had their life span extended with the development of the prosthetic heart valve. However, the valves operate continuously at approximately 39 million cycles per year and are therefore subject to structural failures either by faulty design or material fatigue. The development of a non-invasive technique using an acoustic contact microphone and sophisticated signal processing techniques has been proposed and demonstrated on limited data sets. In this paper we discuss an extension of the techniques to perform the heart valve tests in an anechoic like. Here the objective is to extract a ''pure'' sound or equivalently the acoustical vibration response of the prosthetic valves in a quiet environment. The goal is to demonstrate that there clearly exist differences between values which have a specific mechanical defect known as single leg separation (SLS) and non-defective valves known as intact (INT). We discuss the signal processing and results of anechoic acoustic measurements on 50 prosthetic valves in the tank. Finally, we show the results of the individual runs for each valve, point out any of the meaningful features that could be used to distinguish the SLS from INT and summarize the experiments.

  3. 21 CFR 870.3935 - Prosthetic heart valve holder.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... 21 Food and Drugs 8 2012-04-01 2012-04-01 false Prosthetic heart valve holder. 870.3935 Section... heart valve holder. (a) Identification. A prosthetic heart valve holder is a device used to hold a replacement heart valve while it is being sutured into place. (b) Classification. Class I. The device...

  4. 21 CFR 870.3935 - Prosthetic heart valve holder.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... 21 Food and Drugs 8 2014-04-01 2014-04-01 false Prosthetic heart valve holder. 870.3935 Section... heart valve holder. (a) Identification. A prosthetic heart valve holder is a device used to hold a replacement heart valve while it is being sutured into place. (b) Classification. Class I. The device...

  5. 21 CFR 870.3935 - Prosthetic heart valve holder.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... 21 Food and Drugs 8 2010-04-01 2010-04-01 false Prosthetic heart valve holder. 870.3935 Section... heart valve holder. (a) Identification. A prosthetic heart valve holder is a device used to hold a replacement heart valve while it is being sutured into place. (b) Classification. Class I. The device...

  6. 21 CFR 870.3935 - Prosthetic heart valve holder.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... 21 Food and Drugs 8 2011-04-01 2011-04-01 false Prosthetic heart valve holder. 870.3935 Section... heart valve holder. (a) Identification. A prosthetic heart valve holder is a device used to hold a replacement heart valve while it is being sutured into place. (b) Classification. Class I. The device...

  7. 21 CFR 870.3935 - Prosthetic heart valve holder.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... 21 Food and Drugs 8 2013-04-01 2013-04-01 false Prosthetic heart valve holder. 870.3935 Section... heart valve holder. (a) Identification. A prosthetic heart valve holder is a device used to hold a replacement heart valve while it is being sutured into place. (b) Classification. Class I. The device...

  8. Prosthetic heart valves: Objective Performance Criteria versus randomized clinical trial.

    PubMed

    Grunkemeier, Gary L; Jin, Ruyun; Starr, Albert

    2006-09-01

    The current Food and Drug Administration (FDA) heart valve guidance document uses an objective performance criteria (OPC) methodology to evaluate the clinical performance of prosthetic heart valves. OPC are essentially historical controls, but they have turned out to be an adequate, and perhaps optimal, study design in this situation. Heart valves have a simple open-and-close mechanism, device effectiveness is easy to document, and the common complications (thromboembolism, thrombosis, bleeding, leak, and infection) are well known and easily detected. Thus, randomized clinical trials (RCTs) have not been deemed necessary for the regulatory approval of prosthetic heart valves. The OPC are derived from the average complication rates of all approved heart valves. Studies based on OPC have been shown to work well; many different valve models have gained FDA market approval based on this methodology. Although heart valve RCTs are not required by the FDA, they have been done to compare valves or treatment regimens after approval. Recently, the Artificial Valve Endocarditis Reduction Trial (AVERT) was designed to compare a new Silzone sewing ring, designed to reduce infection, with the Standard sewing ring on a St. Jude Medical heart valve. This was the largest heart valve RCT ever proposed (4,400 valve patients, followed for as long as 4 years), but it was stopped prematurely because of a high leak rate associated with the Silzone valve. Examining the results showed that a much smaller, OPC-based study with 800 patient-years would have been sufficient to disclose this complication of the Silzone valve.

  9. Prosthetic valve endocarditis: clinical findings and management.

    PubMed

    Horstkotte, D; Körfer, R; Loogen, F; Rosin, H; Bircks, W

    1984-10-01

    Prosthetic valve endocarditis (PVE) was shown in 46 patients out of a group of 2163 carrying prosthetic heart valves. The cumulative rate of early PVE was 1.4% and 1.5% for PVE occurring between the 60th day and 10 years after surgery. In 37% of all cases this was caused by staphylococci, 20% by streptococci, and 13% Gram negative species. Fungi were found in 9% and mixed infections in 21%. The incidence of staphylococci, Gram negative pathogens and fungi was significantly higher in early PVE. In 5 patients, valve involvement consisted in echocardiographically shown vegetations and/or obstructive thromboendocarditis. In 90% of 37 patients who developed paravalvular leakages, there was high intravascular haemolysis uncharacteristic of the type of prosthesis implanted. In 70% fluoroscopy revealed disproportionate tilting of the prosthetic annulus, and in 75% there was a distinct echocardiographic pattern in the closing movement of the valve poppet. The cumulative survival rate after six months was 31% for the conservatively treated, and 66% for the medically plus surgically treated patients. Survival rates at the end of a maximum follow-up of 20 years was 15% with conservative treatment and 51% after primary surgical therapy. The prognosis was worse (P less than 0.01) in patients who, during aortic PVE, developed heart failure refractant to therapy due to haemodynamically significant prosthetic valve dysfunction, to sepsis that persisted for more than 72 h despite antibiotic therapy, to major septic embolism or to acute renal failure. The retrospective prognosis was more favourable for patients with early aortic (P less than 0.02) or mitral (P less than 0.05) valve re-replacement than for patients who had been treated medically only.

  10. Pannus-related prosthetic valve dysfunction. Case report.

    PubMed

    Moldovan, Maria-Sînziana; Bedeleanu, Daniela; Kovacs, Emese; Ciumărnean, Lorena; Molnar, Adrian

    2016-01-01

    Pannus-related prosthetic valve dysfunction, a complication of mechanical prosthetic valve replacement, is rare, with a slowly progressive evolution, but it can be acute, severe, requiring surgical reintervention. We present the case of a patient with a mechanical single disc aortic prosthesis, with moderate prosthesis-patient mismatch, minor pannus found on previous ultrasound examinations, who presented to our service with angina pain with a duration of 1 hour, subsequently interpreted as non-ST segment elevation myocardial infarction (NSTEMI) syndrome. Coronarography showed normal epicardial coronary arteries, an ample movement of the prosthetic disc, without evidence of coronary thromboembolism, and Gated Single-Photon Emission Computerized Tomography (SPECT) with Technetium (Tc)-99m detected no perfusion defects. Transthoracic echocardiography (TTE) evidenced a dysfunctional prosthesis due to a subvalvular mass; transesophageal echocardiography (TOE) showed the interference of this mass, with a pannus appearance, with the closure of the prosthetic disc. Under conditions of repeated angina episodes, under anticoagulant treatment, surgery was performed, with the intraoperative confirmation of pannus and its removal. Postoperative evolution was favorable. This case reflects the diagnostic and therapeutic management problems of pannus-related prosthetic valve dysfunction.

  11. Choice of prosthetic heart valve in a developing country

    PubMed Central

    Choudhary, Shiv Kumar; Talwar, Sachin; Airan, Balram

    2016-01-01

    Mechanical prostheses and stented xenografts (bioprosthesis) are most commonly used substitutes for aortic and mitral valve replacement. The mechanical valves have the advantage of durability but are accompanied with the risk of thromboembolism, problems of long-term anticoagulation, and associated risk of bleeding. In contrast, bioprosthetic valves do not require long-term anticoagulation, but carry the risk of structural valve degeneration and re-operation. A mechanical valve is favoured in young patients (<40 years) if reliable anticoagulation is ensured. In elderly patients (>60 years), a bioprosthesis is a suitable substitute. In middle-aged patients (40–60 years), risk of re-operation in a bioprosthesis is equal to that of bleeding in a mechanical valve. Traditionally, a bioprosthesis is opted in patients with limited life expectancy. Calculation of life expectancy, based solely upon chronological age, is erroneous. In developing countries, the calculated life expectancy is much lower than that of Western population, hence age related Western cut-offs are not valid in developing countries. Besides age, cardiac condition of the patient, systemic illnesses, socio-economic status, gender and geographical location also decide the life expectancy of the patients. Selection of the prosthetic valve substitute should be based on: aspiration of the patient, life expectancy, socio-economic and educational background, occupation of the patient, availability, cost, monitoring of anti-coagulation, monitoring of valve function and other valve related complications, and possibility of re-operation. PMID:27326237

  12. Bacillus licheniformis prosthetic aortic valve endocarditis.

    PubMed Central

    Santini, F; Borghetti, V; Amalfitano, G; Mazzucco, A

    1995-01-01

    A 73-year old man developed an acute prosthetic aortic valve dehiscence for which emergent operation was undertaken. The intraoperative evidence of an aortic annular disruption and of a subannular abscess led to the hypothesis that an endocarditis process was involved. The aortic valve was replaced with a stentless porcine bioprosthesis. Cultures taken intraoperatively from the aortic area had a pure growth of aerobic, spore-forming, gram-positive bacilli identified as Bacillus licheniformis. The patient responded to specific antibiotic therapy with no relapse at a 20-month follow-up. The potentiality of B. licheniformis as a pathogen should be reconsidered. PMID:8576381

  13. Processing of prosthetic heart valve sounds for classification. Revision 1

    SciTech Connect

    Candy, J.V.; Jones, H.E.

    1994-04-01

    People with serious heart conditions have had their expected life span extended considerably with the development of the prosthetic heart valve especially with the great strides made in valve design. Even though the designs are extremely reliable, the valves are mechanical and operating continuously over a long period, therefore, structural failures can occur due to fatigue. Measuring heart sounds non-invasively in a noisy environment puts more demands on the signal processing to extract the desired signals from the noise. In this paper the authors discuss acoustical signal processing techniques developed to process noisy heart valve sounds measured by a sensitive, surface contact microphone and used for the eventual classification of the valve.

  14. Homograft and prosthetic aortic valve replacement: a comparative study.

    PubMed

    Pine, M; Hahn, G; Paton, B; Pappas, G; Davies, H; Steele, P; Pryor, R; Blount, S G

    1976-12-01

    Homograft aortic valve replacement was done in 103 patients and prosthetic aortic valve replacement in 106 between January 1962 and December 1973. Patients who received homograft and prosthetic valves were compared with respect to age, sex, preoperative functional impairment, infection, dyspnea, angina, hemodynamics, chest X-ray, electrocardiogram, associated operations, early and late mortality, and valve failure. Combined total mortality was 28% (12% operative, 8% first postoperative year, 8% late). Ten percent of valve required replacement. One year after operation, 70% of survivors were asymptomatic, 27% were improved, and 3% were unchanged or between homograft and prosthetic valve replacement. Valve-related failure and infections were more common after homograft aortic valve replacement. Emboli, hemorrhage, and hemolysis were commoner after prosthetic valve replacement. Fungal infections occurred in five homograft patients but in no patient with a prosthetic aortic valve. Severe properative symptoms or recent endocarditis was associated with greater mortality and valve failure in both the homograft and the prosthetic series. Increased mortality and failure was also seen in patients with either preoperative aortic regurgitation with high left ventricular end-diastolic pressure and low cardiac index, or aortic stenosis with cardiomegaly or roentgenographic evidence of congestive heart failure. Therefore, in two series of patients at equal risk, mortality and valve failure were similar for homograft and prosthetic aortic valve replacement.

  15. Common cardiac prosthetic valves. Radiologic identification and associated complications.

    PubMed

    Chun, P K; Nelson, W P

    1977-08-01

    The development of prosthetic heart valves has been an important advance in the treatment of patients with serious valvular cardiac disease. Because there are many types of prosthetic valves, we have prepared a diagram of the valves currently or previously used and list their potential complications. Prosthetic valves were identified according to photographic and radiologic features, valve replacement location, and reported associated complications. Data have been compiled in tabular form for quick reference; valves have been identified according to valve base, cage, and poppet. They may be categorized as caged-ball or low-profile valves. Such information helps to provide recognition of the valve that has been inserted and permits the clinician or radiologist to be alert to possible complications with the various prosthetic devices.

  16. Surgery for fulminant prosthetic valve endocarditis after transapical transcatheter aortic valve-in-valve implantation.

    PubMed

    Wilbring, Manuel; Tugtekin, Sems Malte; Matschke, Klaus; Kappert, Utz

    2014-02-01

    We report the clinical course of a patient with a history of transapical aortic "valve-in-valve" transcatheter aortic valve implantation (TAVI), actually suffering from prosthetic valve endocarditis. The patient now underwent cardiac surgery as a salvage procedure. The procedure itself was uneventful, but the patient died several days postoperative due to persisting sepsis. The present case raises the question, how to deal with high-risk patients, once considered unsuitable for cardiac surgery in presence of prosthetic valve infection? Up to now, there exists only insufficient knowledge about incidence, clinical course, and effectiveness of treatment strategies for prosthetic valve endocarditis after TAVI. A review of the available literature is given. Georg Thieme Verlag KG Stuttgart · New York.

  17. Quality of life and prosthetic aortic valve selection in non-elderly adult patients.

    PubMed

    Korteland, Nelleke M; Top, Derya; Borsboom, Gerard J J M; Roos-Hesselink, Jolien W; Bogers, Ad J J C; Takkenberg, Johanna J M

    2016-06-01

    This study assesses quality of life in relation to prosthetic aortic valve selection and preferences for shared decision-making among non-elderly adult patients after aortic valve replacement (AVR). A single-centre consecutive cohort of 497 AVR patients who underwent AVR between the age of 18 and 60 years was cross-sectionally surveyed 1-10 years after AVR. Health-related quality of life (Short-Form Health Survey, SF-36), valve-specific quality of life, patient experience with and preferences for involvement and final decision in prosthetic valve selection were investigated. Two-hundred and forty patients (48%) responded. The median age was 57 years (range 26-70). Compared with the general age-matched Dutch population, AVR patients reported worse physical health, but better mental health. Biological valve recipients reported lower general health than mechanical valve recipients. Mechanical valve recipients had more doubts about the decision to undergo surgery, were more bothered by valve sound, the frequency of doctor visits and blood tests, and possible bleeding, but were less afraid of a possible reoperation. Eighty-nine percent were of the opinion that it is important to be involved in prosthetic valve selection, whereas 64% agreed that they actually had been involved. A better patient experience with involvement in prosthetic valve selection was associated with better mental health (P = 0.036). Given the observed suboptimal patient involvement in prosthetic valve selection, the broad patient support for shared decision-making, and the positive association between patient involvement in prosthetic valve selection and mental health, tools to support shared decision-making would be useful in the setting of heart valve replacement. © The Author 2016. Published by Oxford University Press on behalf of the European Association for Cardio-Thoracic Surgery. All rights reserved.

  18. Unsteady fluid dynamics of several mechanical prosthetic heart valves using a two component laser Doppler anemometer system.

    PubMed

    Akutsu, T; Modi, V J

    1997-10-01

    Five typical mechanical heart valves (Starr-Edwards, Björk-Shiley convexo-concave (c-c), Björk-Shiley monostrut, Bicer-Val, and St. Jude Medical) were tested in the mitral position under the pulsatile flow condition. The test program included measurements of velocity and turbulent stresses at 5 downstream locations. The study was carried out using a sophisticated cardiac simulator in conjunction with a highly sensitive 2 component laser Doppler anemometer (LDA) system. The continuous monitoring of parametric time histories revealed useful details about the complex flow and helped to establish the locations and times of the peak parameter values. Based upon the nondimensional presentation of data, the following general conclusions can be made. First, all the 5 valve designs created elevated turbulent stresses during the accelerating and peak flow phases, presenting the possibility of thromboembolism and perhaps hemolysis. Second, the difference in valve configuration seemed to affect the flow characteristics; third, the bileaflet design of the St. Jude valve appeared to create a lower turbulence stress level.

  19. Acute massive mitral regurgitation from prosthetic valve dysfunction.

    PubMed Central

    Cooper, D K; Sturridge, M F

    1976-01-01

    Two cases of prosthetic valve dysfunction resulting in acute massive mitral regurgitation are reported; emergency operation was successful in both cases. Survival following complete dislodgement of the occluder of a disc valve, as occurred in one case, does not appear to have been reported before. The diffculty in diagnosis of sudden cardiac decompensation in patients with prosthetic valves is stressed, as is the need for urgent operation. Images PMID:973894

  20. Risks and Challenges of Surgery for Aortic Prosthetic Valve Endocarditis.

    PubMed

    Grubitzsch, Herko; Tarar, Waharat; Claus, Benjamin; Gabbieri, Davide; Falk, Volkmar; Christ, Torsten

    2017-06-21

    Prosthetic valve endocarditis is the most severe form of infective endocarditis. This study assessed the risks and challenges of surgery for aortic prosthetic valve endocarditis. In total, 116 consecutive patients (98 males, age 65.2±12.7years), who underwent redo-surgery for active aortic prosthetic valve endocarditis between 2000 and 2014, were reviewed. Cox regression analysis was used to identify factors for aortic root destructions as well as for morbidity and mortality. Median follow-up was 3.8 years (0-13.9 years). Aortic root destructions (42 limited and 29 multiple lesions) were associated with early prosthetic valve endocarditis and delayed diagnosis (≥14 d), but not with mortality. There were 16 (13.8%) early (≤30 d) and 32 (27.6%) late (>30 days) deaths. Survival at 1, 5, and 10 years was 72±4.3%, 56±5.4%, and 46±6.4%, respectively. The cumulative incidence of death, reinfection, and reoperation was 19.0% at 30days and 36.2% at 1year. Delayed diagnosis, concomitant procedures, and EuroSCORE II >20% were predictors for early mortality and need for mechanical circulatory support, age >70years, and critical preoperative state were predictors for late mortality. In their absence, survival at 10 years was 70±8.4%. Reinfections and reoperations occurred more frequently if ≥1 risk factor for endocarditis and aortic root destructions were present. At 10 years, freedom from reinfection and reoperation was 89±4.2% and 91±4.0%. The risks of death, reinfection, and reoperation are significant within the first year after surgery for aortic prosthetic valve endocarditis. Early diagnosis and aortic root destructions are the most important challenges, but advanced age, critical preoperative state, and the need for mechanical circulatory support determine long-term survival. Copyright © 2017 Australian and New Zealand Society of Cardiac and Thoracic Surgeons (ANZSCTS) and the Cardiac Society of Australia and New Zealand (CSANZ). Published by Elsevier B

  1. Case Study and Review: Treatment of Tricuspid Prosthetic Valve Thrombosis

    PubMed Central

    Yi Zhang, David; Lozier, Jay; Chang, Richard; Sachdev, Vandana; Chen, Marcus Y.; Audibert, Jennifer L.; Horvath, Keith A.; Rosing, Douglas R.

    2011-01-01

    Prosthetic valve thrombosis (PVT) is a severe and life-threatening complication of heart valve replacement. Conventional therapy is surgical thrombectomy or valve replacement. Medical thrombolysis is another emerging option. We report the case of a 57 year old woman with a history of Ebstein anomaly who underwent successful treatment of a tricuspid prosthetic valve thrombosis with intra-atrial infusion of very low dose recombinant tissue plasminogen activator (tPA). We review the presentation, etiology, diagnosis, and treatment of the tricuspid PVT emphasizing a modified medical option as a safe, minimally invasive alternative to surgical intervention or conventional medical therapy for tricuspid valve thrombosis. PMID:22000268

  2. Major dehiscence of a prosthetic aortic valve: detection by echocardiography.

    PubMed

    Salem, B I; Pechacek, L W; Leachman, R D

    1979-04-01

    A 21-year-old man had acute aortic insufficiency three months after insertion of an aortic valve prosthesis. Chest roentgenography demonstrated abnormal orientation of the prosthesis. M-mode echocardiography showed dense, linear echoes from the prosthetic valve between the interventricular septum and the mitral valve, along with loss of normal poppet motion within the aortic root. At surgery, the prosthesis was found to be extensively disrupted, resulting in prolapse into the left ventricular outflow tract. Another valve replacement was performed with patient survival. Echocardiography appears to be a useful adjunct to established roentgenographic procedures in the diagnosis of major dehiscence of prosthetic aortic valves.

  3. Case report of Streptomyces endocarditis of a prosthetic aortic valve.

    PubMed Central

    Mossad, S B; Tomford, J W; Stewart, R; Ratliff, N B; Hall, G S

    1995-01-01

    We describe the first case of prosthetic valve endocarditis due to a Streptomyces sp. The patient presented with fever, cutaneous embolic lesions, and bacteremia 3 months after aortic valve replacement. Treatment required valve replacement and a long course of parenteral imipenem. PMID:8586732

  4. Acute inferior myocardial infarction in a patient with a prosthetic aortic valve and high international normalized ratio

    PubMed Central

    Sari, Ibrahim; Delil, Kenan; Ileri, Cigdem; Samadov, Fuad

    2014-01-01

    ST elevation acute myocardial infarction in patients with a mechanical prosthetic valve is rare and usually due to inadequate anticoagulation. We present a case of acute inferior myocardial infarction in a patient with a prosthetic aortic valve and high international normalized ratio, which has not been reported previously. PMID:24799934

  5. Triple prosthetic valve dysfunction 30 years after surgery.

    PubMed

    Bonou, Maria; Papadimitraki, Eva D; Skiadas, John; Barbetseas, John

    2015-03-01

    Triple prosthetic valve operation carries a high peri-procedural risk and is associated with decreased long-term survival. Herein is reported the case of a 59-year-old female with a 30-year history of successful triple-valve replacement for rheumatic heart disease, who presented with symptomatic valvular dysfunction and rhythm disturbances. The patient was one of the few who had survived more than 30 years after triple-valve surgery. Illustrative echocardiograms and cinefluoroscopic images are provided, and issues regarding prosthetic valve dysfunction and rhythm disturbance management in operated patients are briefly discussed.

  6. Corynebacterium CDC Group G Native and Prosthetic Valve Endocarditis.

    PubMed

    Sattar, Adil; Yu, Siegfried; Koirala, Janak

    2015-08-11

    We report the first case of native and recurrent prosthetic valve endocarditis with Corynebacterium CDC group G, a rarely reported cause of infective endocarditis (IE). Previously, there have been only two cases reported for prosthetic valve IE caused by these organisms. A 69-year-old female with a known history of mitral valve regurgitation presented with a 3-day history of high-grade fever, pleuritic chest pain and cough. Echocardiography confirmed findings of mitral valve thickening consistent with endocarditis, which subsequently progressed to become large and mobile vegetations. Both sets of blood cultures taken on admission were positive for Corynebacterium CDC group G. Despite removal of a long-term venous access port, the patient's presumed source of line associated bacteremia, mitral valve replacement, and aggressive antibiotic therapy, the patient had recurrence of vegetations on the prosthetic valve. She underwent replacement of her prosthetic mitral valve in the subsequent 2 weeks, before she progressed to disseminated intravascular coagulation and expired. Although they are typically considered contaminants, corynebacteria, in the appropriate clinical setting, should be recognized, identified, and treated as potentially life-threatening infections, particularly in the case of line-associated bacteremias, and native and prosthetic valve endocarditis.

  7. Fluid mechanics of heart valves.

    PubMed

    Yoganathan, Ajit P; He, Zhaoming; Casey Jones, S

    2004-01-01

    Valvular heart disease is a life-threatening disease that afflicts millions of people worldwide and leads to approximately 250,000 valve repairs and/or replacements each year. Malfunction of a native valve impairs its efficient fluid mechanic/hemodynamic performance. Artificial heart valves have been used since 1960 to replace diseased native valves and have saved millions of lives. Unfortunately, despite four decades of use, these devices are less than ideal and lead to many complications. Many of these complications/problems are directly related to the fluid mechanics associated with the various mechanical and bioprosthetic valve designs. This review focuses on the state-of-the-art experimental and computational fluid mechanics of native and prosthetic heart valves in current clinical use. The fluid dynamic performance characteristics of caged-ball, tilting-disc, bileaflet mechanical valves and porcine and pericardial stented and nonstented bioprostheic valves are reviewed. Other issues related to heart valve performance, such as biomaterials, solid mechanics, tissue mechanics, and durability, are not addressed in this review.

  8. Anesthetic management of a patient with prosthetic heart valve for non-cardiac surgery: A case report.

    PubMed

    Umesh, Goneppanavar; Verma, Swati; Jasvinder, Kaur

    2008-09-30

    Patients with prosthetic heart valves are a challenge to any anesthesiologist due to the risk of infective endocarditis, bleeding and thrombosis. We present anesthetic management of a 58-year-old Indian lady with a prosthetic (mechanical) heart valve who underwent hemireplacement arthroplasty. Patients with prosthetic heart valves, especially those with the mechanical valves are prone for thrombosis and resultant complications if anticoagulation is not maintained properly. However, when they are scheduled for major surgery, they can be best managed by normalising the coagulation profile immediately prior to surgery and restarting the anticoagulation as early as possible.

  9. Anesthetic management of a patient with prosthetic heart valve for non-cardiac surgery: A case report

    PubMed Central

    Umesh, Goneppanavar; Verma, Swati; Jasvinder, Kaur

    2008-01-01

    Background Patients with prosthetic heart valves are a challenge to any anesthesiologist due to the risk of infective endocarditis, bleeding and thrombosis. Case presentation We present anesthetic management of a 58-year-old Indian lady with a prosthetic (mechanical) heart valve who underwent hemireplacement arthroplasty. Conclusion Patients with prosthetic heart valves, especially those with the mechanical valves are prone for thrombosis and resultant complications if anticoagulation is not maintained properly. However, when they are scheduled for major surgery, they can be best managed by normalising the coagulation profile immediately prior to surgery and restarting the anticoagulation as early as possible. PMID:18826632

  10. Classification of prosthetic heart valve sounds. A parametric approach

    SciTech Connect

    Candy, J.V.; Jones, H.E. |

    1995-06-01

    People with heart problems have had their lives extended considerably with the development of the prosthetic heart valve. Great strides have been made in the development of the valves through the use of improved materials as well as efficient mechanical designs. However, since the valves operate continuously over a long period, structural failures can occur-even though they are relatively uncommon. Here the development of techniques to classify the valve either as having intact struts or as having a separated strut, commonly called single leg separation, is discussed. In this paper the signal processing techniques employed to extract the required signals/parameters are briefly reviewed and then it is shown how they can be used to simulate a synthetic heart valve database for eventual Monte Carlo testing. Next, the optimal classifier is developed under assumed conditions and its performance is compared to that of an adpative-type classifier implemented with a probabilistic neural network. Finally, the adaptive classifier is applied to a data set and its performance is analyzed. Based on synthetic data it is shown that excellent performance of the classifiers can be achieved implying a potentially robust solution to this classification problem. 21 refs., 11 figs., 1 tab.

  11. Early prosthetic valve endocarditis caused by Corynebacterium kroppenstedtii.

    PubMed

    Hagemann, Jürgen Benjamin; Essig, Andreas; Herrmann, Manuel; Liebold, Andreas; Quader, Mohamed Abo

    2015-12-01

    Corynebacterium (C.) kroppenstedtii is a rarely detected agent of bacterial infections in humans. Here, we describe the first case of prosthetic valve endocarditis caused by C. kroppenstedtii. Application of molecular methods using surgically excised valve tissue was a cornerstone for the establishment of the microbiological diagnosis, which is crucial for targeted antimicrobial treatment.

  12. Effect of a combined anti-thrombotic therapy of thrombosis on prosthetic heart valves

    PubMed Central

    Wei, Wei; Zheng, Zhichao; Huang, Shuping

    2015-01-01

    Objective To evaluate the curative effects and risks of a medical therapy with combined anti-thrombotic agents for thrombosis on prosthetic heart valves. Methods Twenty-two patients who suffered from thrombosis on prosthetic valves with stable hemodynamics were divided into the inpatient group and the outpatient group. Thrombosis on the valves were demonstrated by transesophageal echocardiographies (TEE). A combined anti-thrombotic therapy with clopidogrel and warfarin were prescribed for all the patients during the whole treatment. Low molecular weight heparin (LMWH) was given twice daily during the first 5 days for the inpatients. The patients accepted regular follow-ups for observation of the functions of prosthetic valves, changes of thrombi, coagulation status and general clinical status. Results There were 5 men and 17 women. Thirteen patients suffered from thrombosis on the mechanical mitral valves (MVs), five on the mechanical tricuspid valves (TVs), one on the mechanical aortic valve and tricuspid bio-prosthetic valve, one on the mechanical aortic valve, one on the mitral bio-prosthetic valve, and one on the tricuspid bio-prosthetic valve. After an average of 36.4±23.1 days’ observation, 16 (73%) patients’ valvular function recovered normal without TTE detectable thrombi, 6 (27%) patients’ valvular function remained abnormal including three patients without TTE detectable thrombi during follow-ups. No significant differences of thrombi changes and period of thrombi disappearance were observed between the inpatient group and the outpatient group. For patients with mitral thrombosis, sizes of the left atriums (LAs) decreased an average of 4.1 mm after treatment (95% CI, 1.2-6.9 mm). No significant changes of other chambers and left ventricular ejection fractions (LVEF) were observed. For patients with tricuspid thrombosis, LVEF improved an average of 10.5% after treatment (95% CI, 0.1-17.9%). No significant changes of chambers were observed. None

  13. Effect of a combined anti-thrombotic therapy of thrombosis on prosthetic heart valves.

    PubMed

    Wei, Wei; Dong, Taiming; Zheng, Zhichao; Huang, Shuping

    2015-03-01

    To evaluate the curative effects and risks of a medical therapy with combined anti-thrombotic agents for thrombosis on prosthetic heart valves. Twenty-two patients who suffered from thrombosis on prosthetic valves with stable hemodynamics were divided into the inpatient group and the outpatient group. Thrombosis on the valves were demonstrated by transesophageal echocardiographies (TEE). A combined anti-thrombotic therapy with clopidogrel and warfarin were prescribed for all the patients during the whole treatment. Low molecular weight heparin (LMWH) was given twice daily during the first 5 days for the inpatients. The patients accepted regular follow-ups for observation of the functions of prosthetic valves, changes of thrombi, coagulation status and general clinical status. There were 5 men and 17 women. Thirteen patients suffered from thrombosis on the mechanical mitral valves (MVs), five on the mechanical tricuspid valves (TVs), one on the mechanical aortic valve and tricuspid bio-prosthetic valve, one on the mechanical aortic valve, one on the mitral bio-prosthetic valve, and one on the tricuspid bio-prosthetic valve. After an average of 36.4±23.1 days' observation, 16 (73%) patients' valvular function recovered normal without TTE detectable thrombi, 6 (27%) patients' valvular function remained abnormal including three patients without TTE detectable thrombi during follow-ups. No significant differences of thrombi changes and period of thrombi disappearance were observed between the inpatient group and the outpatient group. For patients with mitral thrombosis, sizes of the left atriums (LAs) decreased an average of 4.1 mm after treatment (95% CI, 1.2-6.9 mm). No significant changes of other chambers and left ventricular ejection fractions (LVEF) were observed. For patients with tricuspid thrombosis, LVEF improved an average of 10.5% after treatment (95% CI, 0.1-17.9%). No significant changes of chambers were observed. None experienced major bleedings except

  14. Effect of the sinus of valsalva on the closing motion of bileaflet prosthetic heart valves.

    PubMed

    Ohta, Y; Kikuta, Y; Shimooka, T; Mitamura, Y; Yuhta, T; Dohi, T

    2000-04-01

    Conventional bileaflet prosthetic mechanical heart valves close passively with backflow. Naturally, the valve has problems associated with closure, such as backflow, water hammer effect, and fracture of the leaflet. On the other hand, in the case of the natural aortic valve, the vortex flow in the sinus of Valsalva pushes the leaflet to close, and the valve starts the closing motion earlier than the prosthetic valve as the forward flow decelerates. This closing mechanism is thought to decrease backflow at valve closure. In this study, we propose a new bileaflet mechanical valve resembling a drawbridge in shape, and the prototype valve was designed so that the leaflet closes with the help of the vortex flow in the sinus. The test valve was made of aluminum alloy, and its closing motion was compared to that of the CarboMedics (CM) valve. Both valves were driven by a computer controlled hydraulic mock circulator and were photographed at 648 frames/s by a high speed charge-coupled device (CCD) camera. Each frame of the valve motion image was analyzed with a personal computer, and the opening angles were measured. The flow rate was set as 5.0 L/min. The system was pulsed with 70 bpm, and the systolic/diastolic ratio was 0.3. Glycerin water was used as the circulation fluid at room temperature, and polystyrene particles were used to visualize the streamline. The model of the sinus of Valsalva was made of transparent silicone rubber. As a result, high speed video analysis showed that the test valve started the closing motion 41 ms earlier than the CM valve, and streamline analysis showed that the test valve had a closing mechanism similar to the natural one with the effect of vortex flow. The structure of the test valve was thought to be effective for soft closure and could solve problems associated with closure.

  15. [Redo Aortic and Mitral Valve Replacement by Manouguian's Procedure for Active Prosthetic Valve Infection].

    PubMed

    Kunitomo, Ryuji; Okamoto, Ken; Moriyama, Shuji; Sakaguchi, Hisashi; Tazume, Hirokazu; Yoshinaga, Takashi; Kawasuji, Michio

    2016-03-01

    The damage to the intervalvular fibrous trigone (IVFT) by infective endocarditis makes combined aortic and mitral valve replacement difficult. We performed Manouguian's double valve replacement for such a case and obtained a good result. A 81-year-old male underwent emergency operation due to active prosthetic valve endocarditis. He had a history of receiving combined aortic and mitral valve replacement because of active infective endocarditis at the age of 74 and redo aortic valve replacement 3 years after that. The infectious lesion extended from the mitral annulus to the IVFT and the aortic annulus, and it caused the prosthetic valve detachment from the aortic annulus. Manouguian's double valve replacement was required for radical resection and reconstruction of the IVFT. No recurrent infection or paravalvular leakage was observed during 49months follow up period. Manouguian's procedure is useful for complete resection of the infected IVFT and makes combined aortic and mitral valve replacement safer.

  16. Prosthetic aortic valves. Indications for and results of reoperation.

    PubMed

    Shemin, R J; Guadiani, V A; Conkle, D M; Morrow, A G

    1979-01-01

    During a 15-year period from January 1962 through December 1976, 42 patients who had undergone a previous aortic valve replacement underwent reoperation. The mean interval between operations was 4.4 years. The indications for reoperation were aortic regurgitation resulting from mechanical malfunction (12 patients), ball variance (15 patients), perivalvular leaks (five patients), prosthetic stenosis (eight patients), anemia (one patient), and recurrent emboli (one patient). The indications were characteristic of a specific valve series. The most common reoperation was aortic valve replacement (29/42), which had a 10.3% operative mortality. Poppet change (10/42) carried a 10% operative mortality and no operative deaths followed suture closure of perivalvular leaks. Eighty-eight percent of patients alive six months after reoperation were New York Heart Association functional class 1 or 2. At last follow-up, 95% of surviving patients were still functional class 1 or 2, with a mean cumulative survival of 4.7 years after reoperation. This experience demonstrates that those patients surviving long enough to undergo reoperation can expect a reasonable operative risk, long-term survival, and excellent clinical improvement.

  17. Do all patients with prosthetic valve endocarditis need surgery?

    PubMed Central

    Attaran, Saina; Chukwuemeka, Andrew; Punjabi, Prakash P.; Anderson, Jon

    2012-01-01

    A best evidence topic in cardiothoracic surgery was written according to a structured protocol. The question addressed was ‘do all patients with prosthetic valve endocarditis need surgery?’ Seventeen papers were found using the reported search that represented the best evidence to answer the clinical question. The authors, journal, date and country of publication, patient group studied, study type, relevant outcomes and results of these papers are tabulated. These studies compared the outcome and survival between surgically and non-surgically treated patients with prosthetic valve endocarditis. Of these studies, two were prospective observational studies and the rest were retrospective studies. The results of most of these papers were in accordance with the guidelines of the American College of Cardiology and American Heart association. These studies showed that unless a patient is not a surgical candidate, an operation is the treatment of choice in prosthetic valve endocarditis. Surgery should be performed as soon as possible, particularly in haemodynamically unstable patients and those who develop complications such as heart failure, valvular dysfunction, regurgitation/obstruction, dehiscence and annular abscess. In addition to the above indications and cardiac/valvularrelated complications of prosthetic valve endocarditis, infection with Staphylococcus aureus plays an important role in the outcome, and the presence of this micro-organism should be considered an urgent surgical indication in the treatment of prosthetic valve endocarditis. Surgery should be performed before the development of any cerebral or other complications. In contrast, in stable patients with other micro-organisms, particularly those with organisms sensitive to antibiotic treatment who have no structural valvular damage or cardiac complications, surgery can be postponed. The option of surgical intervention can also be revisited if there is a change in response to the treatment. This

  18. [Surgical treatment for prosthetic valve endocarditis after aortic root replacement].

    PubMed

    Kanamori, Taro; Ichihara, Tetsuya; Sakaguchi, Hidehito; Inoue, Takehiko

    2014-05-01

    Aorto-left ventricular continuity destruction due to prosthetic valve endocarditis is rare, but it is one of the fatal complications after aortic root operation. We report a case of surgical treatment for prosthetic valve endocarditis after aortic root replacement. A 47-year-old man, who had undergone aortic root replacement with a composite graft was transferred to our hospital with sudden chest pain and high fever. Enhanced computed tomography showed a large space with contrast enhancement suggesting perivalvular leakage around the artificial composite graft. Emergency operation including aortic root re-replacement and reconstruction of the left ventricular outflow tract was performed successfully. We focused on its technical aspect.

  19. Prosthetic heart valve selection in women of childbearing age with acquired heart disease: a case report.

    PubMed

    Barbarash, Leonid; Rutkovskaya, Natalya; Barbarash, Olga; Odarenko, Yuri; Stasev, Alexander; Uchasova, Evgenya

    2016-03-08

    The problem of prosthetic heart valve selection in fertile women with acquired heart defects remains crucial in modern cardiology. Mechanical heart valves require lifelong indirect anticoagulant therapy, which has significant fetal toxicity and is unacceptable for women planning pregnancy. Bioprosthetic heart valves are the best choice for fertile women; however, their durability is limited, and reoperations are required. We describe the clinical case of a 21-year-old Russian woman with infectious endocarditis who underwent heart valve replacement with an epoxy-treated mitral valve prosthesis. Epoxy-treated bioprosthetic heart valves can be used without long-term anticoagulant therapy because of their optimal hemodynamic functional parameters. Moreover, their high thromboresistance and resistance to infection improve patients' quality of life in their late postoperative period. We recommend these valves both in older persons and in young patients including women who are planning pregnancy.

  20. Treatment of Recurrent Prosthetic Mitral Valve Thrombosis with Reteplase: A Report of Four Cases.

    PubMed

    Behzadnia, Neda; Sharif Kashani, Babak; Kiani, Arda; Abedini, Atefe; Seyedi, Seyed Reza; Zargham Ahmadi, Hossein; Naghash Zadeh, Farah; Fakharian, Atefeh

    2016-01-01

    Thrombosis is a life threatening complications of prosthetic mitral valves and is associated with high morbidity and mortality. Even in presence of systemic anticoagulation prosthetic valve thrombosis has an incidence of 0.5% to 8%. Recurrent prosthetic valve thrombosis and the resulting thrombotic occlusion require re-establishment of blood flow across the valve. While surgical repair is considered the classic first line treatment option for prosthetic valve thrombosis, intravenous thrombolysis has emerged as an acceptable alternative for the first episode of prosthetic valve thrombosis. Due to the limitation of using streptokinase in recurrent thrombotic events, fibrin-specific tissue plasminogen activators have been successfully utilized to treat cases of recurrent prosthetic valve thrombosis. In this case-series, we have reported four cases of recurrent prosthetic valve thrombosis that were successfully treated with Reteplase at our hospital.

  1. Characterization of (18)F-Fluorodeoxyglucose Uptake Pattern in Noninfected Prosthetic Heart Valves.

    PubMed

    Mathieu, Cédric; Mikaïl, Nidaa; Benali, Khadija; Iung, Bernard; Duval, Xavier; Nataf, Patrick; Jondeau, Guillaume; Hyafil, Fabien; Le Guludec, Dominique; Rouzet, François

    2017-03-01

    (18)F-Fluorodeoxyglucose (FDG) positron emission tomography/computed tomography (PET/CT) has been recently acknowledged as a diagnostic tool for prosthetic valve endocarditis, but its specificity is limited by uptake on noninfected valves. The objective of this study was to outline the main features of FDG uptake on PET/CT in patients with noninfected prosthetic heart valve (PHV). Our institution's PET/CT database was reviewed to identify patients with PHV, excluding those suspected of infection or who had received antibiotic treatment. PET indication, valve location, and type (biological/mechanical) and time from implantation were collected for each patient. Images with and without attenuation correction were considered for interpretation. The pattern of FDG uptake (absent, homogeneous, or heterogeneous) was recorded. Fifty-four PHVs (51 patients) were identified, including 32 biological valves. Indications for PET were oncology (n=26), suspicion of prosthetic valve endocarditis subsequently excluded (n=17), and history of vasculitis (n=11). A periprosthetic FDG uptake was present in 47 (87%) and 30 (56%) PHVs with and without attenuation correction, respectively, and the pattern was homogeneous in all but 4 (7%) and 3 (6%) PHVs, respectively. On quantitative analysis, maximum standardized uptake values was greater in mechanical than in biological valves (4.0 [2.4-8.0] versus 3.3 [2.1-6.1]; P=0.01) and in patients with vasculitis than in those referred for other indications. The uptake intensity did not differ before and 3 months after valve replacement. Noninfected PHVs frequently display homogeneous FDG uptake, which remains steady over time. Caution is, therefore, needed when interpreting FDG PET/CT in suspected prosthetic valve endocarditis, with specific attention to uptake pattern. © 2017 American Heart Association, Inc.

  2. Prosthetic venous valve patient selection by validated physics-based computational models.

    PubMed

    Chen, Henry Y; Berwick, Zachary C; Kemp, Arika; Krieger, Joshua; Chambers, Sean; Lurie, Fedor; Kassab, Ghassan S

    2015-01-01

    There is significant interest in a venous prosthesis to replace insufficient valves. The aim of the current study was to select the patients with hemodynamic conditions most likely to benefit from a valve implant. The hypothesis is that the venous valve prosthesis is most suitable for patients with significant reflux, such as in chronic venous insufficiency (CVI), right heart hypertrophy (RHH), and right heart failure (RHF). Conversely, a prosthetic valve is likely to be of least benefit for deep venous thrombosis (DVT) patients with low flow. To address this hypothesis, fully coupled fluid and solid mechanics computational models were developed and validated in five acute canine implants. The animal-validated simulations were then carried out for the CVI, RHH, RHF, and DVT patients based on literature hemodynamic data. A mechanical stress ratio of leaflet wall stress to fluid wall shear stress was defined to combine the effects of both fluid mechanics and solid mechanics on leaflet function, for which a lower stress ratio is hemodynamically desirable. The simulation results of mean valve flow velocity and percentage valve opening were found to be within 10% of the measurements in canines. The simulations show that the patients in the CVI classes 4 to 6, RHH patients, and RHF patients may have a significant reduction in stress ratio with virtual implant of a prosthetic valve. The DVT patient simulations demonstrate a minimal reduction in the stress ratio. After thrombus removal where flow is restored, however, the prosthetic valve may be helpful for post-thrombotic patients. For patient selections of the venous valve prosthesis, the most suitable patients are the CVI classes 4 to 6, RHH, and RHF patients. The least suitable patients are the DVT patients because a valve is not effective under low-flow conditions. The present study demonstrates a physics-based approach to patient selection that can be tested in future clinical trials. Copyright © 2015 Society for

  3. Current Status of Prosthetic Cardiac Valves

    PubMed Central

    Huse, Wilfred M.; Wareham, Ellsworth E.

    1967-01-01

    The majority of patients with acquired valvular heart disease have severe damage to valves which is not amenable to repair but can now be treated by valve replacement with an acceptable mortality and morbidity. The caged ball or disc valve is widely used and is proving clinically satisfactory for cardiac valve replacement. Thromboembolism is the significant complication. With improvement in technique the incidence of infection, detachment and other complications has been reduced. ImagesFigure 1.Figure 2.Figure 4.Figure 5.Figure 6.Figure 7.Figure 8.Figure 9.Figure 10. PMID:6039188

  4. Prosthetic Valve Endocarditis Caused by Bartonella henselae: A Case Report of Molecular Diagnostics Informing Nonsurgical Management

    PubMed Central

    Bartley, Patricia; Angelakis, Emmanouil; Raoult, Didier; Sampath, Rangarajan; Bonomo, Robert A.

    2016-01-01

    Identifying the pathogen responsible for culture-negative valve endocarditis often depends on molecular studies performed on surgical specimens. A patient with Ehlers-Danlos syndrome who had an aortic graft, a mechanical aortic valve, and a mitral anulloplasty ring presented with culture-negative prosthetic valve endocarditis and aortic graft infection. Research-based polymerase chain reaction (PCR)/electrospray ionization mass spectrometry on peripheral blood samples identified Bartonella henselae. Quantitative PCR targeting the16S-23S ribonucleic acid intergenic region and Western immunoblotting confirmed this result. This, in turn, permitted early initiation of pathogen-directed therapy and subsequent successful medical management of B henselae prosthetic valve endocarditis and aortic graft infection. PMID:27844027

  5. Prosthetic aortic valve: a bone in the system.

    PubMed

    Pereira, Vitor Hugo; Guardado, Joana; Fernandes, Marina; Lourenço, Mário; Machado, Inocência; Quelhas, Isabel; Azevedo, Olga; Lourenço, António

    2015-02-01

    We report a case of a 73-year-old female patient admitted to the surgical department for a splenic abscess. She had a history of a mechanical aortic valve implanted two years earlier. During the diagnostic work-up, the patient underwent a transesophageal echocardiogram that revealed the presence of multiple paravalvular abscesses, establishing the diagnosis of prosthetic valve endocarditis. A few days later, the echocardiogram was repeated due to a new-onset systolic-diastolic murmur. A large pseudoaneurysm and significant periprosthetic regurgitation were now noted and the patient was referred for cardiac surgery. The microbiologic exam revealed the presence of Streptococcus milleri, usually found in the gastrointestinal flora and a known pathogenic agent of endocarditis. Interestingly, the patient had had a foreign body (bone fragment) removed from her esophagus a few weeks earlier, which was the probable portal of entry for this infective endocarditis. Copyright © 2014 Sociedade Portuguesa de Cardiologia. Published by Elsevier España. All rights reserved.

  6. Prosthetic valve endocarditis after transcatheter aortic valve implantation-diagnostic and surgical considerations

    PubMed Central

    Klaaborg, Kaj Erik; Hjortdal, Vibeke; Nørgaard, Bjarne Linde; Terkelsen, Christian Juhl; Jensen, Kaare; Christiansen, Evald Høj; Terp, Kim Allan; Andersen, Gratien; Hvitfeldt, Steen; Andersen, Henning Rud

    2016-01-01

    Prosthetic valve endocarditis (PVE) after transcatheter aortic valve implantation (TAVI) or surgical aortic valve replacement (SAVR) is a potential life threatening complication. Better understanding of the incidence, predictors, clinical presentation, diagnostic measures, complications and management of PVE may help improve TAVI long-term outcome. We report a case of TAVI-PVE in an 80-year-old high risk patient in whom SAVR was successfully performed. We have reviewed literature regarding TAVI-PVE. PMID:27867590

  7. Relationship between the physical size, incompetence, and stenosis of prosthetic mitral valves

    PubMed Central

    Wright, J. T. M.; Temple, L. J.

    1972-01-01

    One each of 17 commercially available prosthetic mitral valves has been subjected to in vitro testing using a pulse duplicator. Measurements of mean diastolic pressure difference, incompetence, dimensions, mechanical movements, and turbulence were made, and the quality of manufacture was examined. Although most valves would be effective in the treatment of incompetence, only those with large orifice diameters produced no significant stenosis. All the valves tested were in clinical use at some time in the period 1966-71. Most of the prostheses were obtained in 1968 or 1969. Many of this group showed a manufacturing standard which was less than impeccable. Images PMID:5039443

  8. In vitro evaluation of a novel hemodynamically optimized trileaflet polymeric prosthetic heart valve.

    PubMed

    Claiborne, Thomas E; Sheriff, Jawaad; Kuetting, Maximilian; Steinseifer, Ulrich; Slepian, Marvin J; Bluestein, Danny

    2013-02-01

    Calcific aortic valve disease is the most common and life threatening form of valvular heart disease, characterized by stenosis and regurgitation, which is currently treated at the symptomatic end-stages via open-heart surgical replacement of the diseased valve with, typically, either a xenograft tissue valve or a pyrolytic carbon mechanical heart valve. These options offer the clinician a choice between structural valve deterioration and chronic anticoagulant therapy, respectively, effectively replacing one disease with another. Polymeric prosthetic heart valves (PHV) offer the promise of reducing or eliminating these complications, and they may be better suited for the new transcatheter aortic valve replacement (TAVR) procedure, which currently utilizes tissue valves. New evidence indicates that the latter may incur damage during implantation. Polymer PHVs may also be incorporated into pulsatile circulatory support devices such as total artificial heart and ventricular assist devices that currently employ mechanical PHVs. Development of polymer PHVs, however, has been slow due to the lack of sufficiently durable and biocompatible polymers. We have designed a new trileaflet polymer PHV for surgical implantation employing a novel polymer-xSIBS-that offers superior bio-stability and durability. The design of this polymer PHV was optimized for reduced stresses, improved hemodynamic performance, and reduced thrombogenicity using our device thrombogenicity emulation (DTE) methodology, the results of which have been published separately. Here we present our new design, prototype fabrication methods, hydrodynamics performance testing, and platelet activation measurements performed in the optimized valve prototype and compare it to the performance of a gold standard tissue valve. The hydrodynamic performance of the two valves was comparable in all measures, with a certain advantage to our valve during regurgitation. There was no significant difference between the platelet

  9. Huge Left Atrium Accompanied by Normally Functioning Prosthetic Valve.

    PubMed

    Sabzi, Feridoun

    2015-01-01

    Giant left atria are defined as those measuring larger than 8 cm and are typically found in patients who have rheumatic mitral valve disease with severe regurgitation. Enlargement of the left atrium may create compression of the surrounding structures such as the esophagus, pulmonary veins, respiratory tract, lung, inferior vena cava, recurrent laryngeal nerve, and thoracic vertebrae and lead to dysphagia, respiratory dysfunction, peripheral edema, hoarse voice, or back pain. However, a huge left atrium is usually associated with rheumatic mitral valve disease but is very rare in a normally functioning prosthetic mitral valve, as was the case in our patient. A 46-year-old woman with a past medical history of mitral valve replacement and chronic atrial fibrillation was admitted to our hospital with a chief complaint of cough and shortness of breath, worsened in the last month. Physical examination showed elevated jugular venous pressure, respiratory distress, cardiac cachexia, heart failure, hepatomegaly, and severe edema in the legs. Chest radiography revealed an inconceivably huge cardiac sell-out. Transthoracic echocardiography demonstrated a huge left atrium, associated with thrombosis, and normal function of the prosthetic mitral valve. Cardiac surgery with left atrial exploration for the extraction of the huge thrombosis and De Vega annuloplasty for tricuspid regurgitation were carried out. The postoperative course was eventful due to right ventricular failure and low cardiac output syndrome; and after two days, the patient expired with multiple organ failure. Thorough literature review showed that our case was the largest left atrium (20 × 22 cm) reported thus far in adults with a normal prosthetic mitral valve function.

  10. Contemporary management of prosthetic valve endocarditis: principals and future outlook.

    PubMed

    O'Connor, Cormac T; Kiernan, Thomas J

    2015-05-01

    Infective endocarditis involving prosthetic valves accounts for 20% of all endocarditis cases. Rising in prevalence due to increasing placement of valvular prostheses, prosthetic valve endocarditis (PVE) is more difficult to diagnose by conventional methods, associated with more invasive infection and increased mortality. This report explores the existing literature in identifying a direct approach to the management of PVE; such as adjuncts to establishing a diagnosis (for instance positron emission tomography/computed tomography and radiolabeled leukocyte scintigraphy), the trends in specific pathogens associated with PVE and the recommended antimicrobials for each. The patterns of disease requiring surgical intervention are also highlighted and explored. In addition, a 5-year outlook offers consolidated knowledge on epidemiological trends of both culprit organisms and population subgroups suffering (and projected to suffer) from PVE.

  11. Brown-Pigmented Mycobacterium mageritense as a Cause of Prosthetic Valve Endocarditis and Bloodstream Infection.

    PubMed

    McMullen, Allison R; Mattar, Caline; Kirmani, Nigar; Burnham, Carey-Ann D

    2015-08-01

    Mycobacterium spp. are a rare cause of endocarditis. Herein, we describe a case of Mycobacterium mageritense prosthetic valve endocarditis. This organism produced an unusual brown pigment on solid media. Cultures of valve tissue for acid-fast bacilli might be considered in some cases of apparently culture-negative prosthetic valve endocarditis.

  12. Prosthetic valve endocarditis and bloodstream infection due to Mycobacterium chimaera.

    PubMed

    Achermann, Yvonne; Rössle, Matthias; Hoffmann, Matthias; Deggim, Vanessa; Kuster, Stefan; Zimmermann, Dieter R; Bloemberg, Guido; Hombach, Michael; Hasse, Barbara

    2013-06-01

    Prosthetic valve endocarditis (PVE) due to fast-growing nontuberculous mycobacteria (NTM) has been reported anecdotally. Reports of PVE with slowly growing NTM, however, are lacking. We present here one case of PVE and one case of bloodstream infection caused by Mycobacterium chimaera. Randomly amplified polymorphic DNA (RAPD)-PCR indicated a relatedness of the two M. chimaera strains. Both patients had heart surgery 2 years apart from each other. A nosocomial link was not detected.

  13. Prosthetic Valve Endocarditis and Bloodstream Infection Due to Mycobacterium chimaera

    PubMed Central

    Achermann, Yvonne; Rössle, Matthias; Hoffmann, Matthias; Deggim, Vanessa; Kuster, Stefan; Zimmermann, Dieter R.; Hombach, Michael; Hasse, Barbara

    2013-01-01

    Prosthetic valve endocarditis (PVE) due to fast-growing nontuberculous mycobacteria (NTM) has been reported anecdotally. Reports of PVE with slowly growing NTM, however, are lacking. We present here one case of PVE and one case of bloodstream infection caused by Mycobacterium chimaera. Randomly amplified polymorphic DNA (RAPD)-PCR indicated a relatedness of the two M. chimaera strains. Both patients had heart surgery 2 years apart from each other. A nosocomial link was not detected. PMID:23536407

  14. Polymeric trileaflet prosthetic heart valves: evolution and path to clinical reality

    PubMed Central

    Claiborne, Thomas E; Slepian, Marvin J; Hossainy, Syed; Bluestein, Danny

    2013-01-01

    Present prosthetic heart valves, while hemodynamically effective, remain limited by progressive structural deterioration of tissue valves or the burden of chronic anticoagulation for mechanical valves. An idealized valve prosthesis would eliminate these limitations. Polymeric heart valves (PHVs), fabricated from advanced polymeric materials, offer the potential of durability and hemocompatibility. Unfortunately, the clinical realization of PHVs to date has been hampered by findings of in vivo calcification, degradation and thrombosis. Here, the authors review the evolution of PHVs, evaluate the state of the art of this technology and propose a pathway towards clinical reality. In particular, the authors discuss the development of a novel aortic PHV that may be deployed via transcatheter implantation, as well as its optimization via device thrombogenicity emulation. PMID:23249154

  15. Tomographic PIV behind a prosthetic heart valve

    NASA Astrophysics Data System (ADS)

    Hasler, D.; Landolt, A.; Obrist, D.

    2016-05-01

    The instantaneous three-dimensional velocity field past a bioprosthetic heart valve was measured using tomographic particle image velocimetry. Two digital cameras were used together with a mirror setup to record PIV images from four different angles. Measurements were conducted in a transparent silicone phantom with a simplified geometry of the aortic root. The refraction indices of the silicone phantom and the working fluid were matched to minimize optical distortion from the flow field to the cameras. The silicone phantom of the aorta was integrated in a flow loop driven by a piston pump. Measurements were conducted for steady and pulsatile flow conditions. Results of the instantaneous, ensemble and phase-averaged flow field are presented. The three-dimensional velocity field reveals a flow topology, which can be related to features of the aortic valve prosthesis.

  16. Curved butterfly bileaflet prosthetic cardiac valve

    DOEpatents

    McQueen, David M.; Peskin, Charles S.

    1991-06-25

    An annular valve body having a central passageway for the flow of blood therethrough with two curved leaflets each of which is pivotally supported on an accentric positioned axis in the central passageway for moving between a closed position and an open position. The leaflets are curved in a plane normal to the eccentric axis and positioned with the convex side of the leaflets facing each other when the leaflets are in the open position. Various parameters such as the curvature of the leaflets, the location of the eccentric axis, and the maximum opening angle of the leaflets are optimized according to the following performance criteria: maximize the minimum peak velocity through the valve, maximize the net stroke volume, and minimize the mean forward pressure difference, thereby reducing thrombosis and improving the hemodynamic performance.

  17. Nuclear Medicine in Diagnosis of Prosthetic Valve Endocarditis: An Update

    PubMed Central

    Musso, Maria; Petrosillo, Nicola

    2015-01-01

    Over the past decades cardiovascular disease management has been substantially improved by the increasing introduction of medical devices as prosthetic valves. The yearly rate of infective endocarditis (IE) in patient with a prosthetic valve is approximately 3 cases per 1,000 patients. The fatality rate of prosthetic valve endocarditis (PVE) remains stable over the years, in part due to the aging of the population. The diagnostic value of echocardiography in diagnosis is operator-dependent and its sensitivity can decrease in presence of intracardiac devices and valvular prosthesis. The modified Duke criteria are considered the gold standard for diagnosing IE; their sensibility is 80%, but in clinical practice their diagnostic accuracy in PVE is lower, resulting inconclusively in nearly 30% of cases. In the last years, these new imaging modalities have gained an increasing attention because they make it possible to diagnose an IE earlier than the structural alterations occurring. Several studies have been conducted in order to assess the diagnostic accuracy of various nuclear medicine techniques in diagnosis of PVE. We performed a review of the literature to assess the available evidence on the role of nuclear medicine techniques in the diagnosis of PVE. PMID:25695043

  18. Limitations of multimodality imaging in the diagnosis of pannus formation in prosthetic aortic valve and review of the literature

    PubMed Central

    Soumoulou, Juan Bautista; Cianciulli, Tomás Francisco; Zappi, Andrea; Cozzarin, Alberto; Saccheri, María Cristina; Lax, Jorge Alberto; Guidoin, Robert; Zhang, Ze

    2015-01-01

    Pannus formation is a rare complication and occurs almost exclusively in mechanical prosthetic valves. It consists of fibrous tissue that covers the surface of the prosthesis either concentrically or eccentrically, resulting in valve dysfunction. The pathophysiology seems to be associated to a chronic inflammatory process that explains the late and insidious clinical presentation. This diagnosis should be considered in patients with high transvalvular gradients on transthoracic echo, and workup should be completed with fluoroscopy and transesophageal echocardiography. Treatment is always surgical and recurrence is rare. We present a case of pannus formation in a prosthetic aortic valve and a review of the literature regarding this disorder. PMID:25914791

  19. [Research status and development trends of the heart valve mechanical properties].

    PubMed

    Li, Yusheng; Zeng, Pei; Ren, Guorong

    2014-10-01

    The study of mechanical properties on heart valves can provide an important theoretical basis for doctors to repair heart valves and prosthetic valve materials research. In this paper, we present the current status of the mechanical property study methods of heart valve, expound the methods and special requirements about uniaxial tensile test and biaxial tensile test of the heart valve, and further discuss several establishment methods of heart valve constitutive models. We also discuss the development trend of heart valve mechanics.

  20. [Choice of temperature extracorporeal circulation regimen during prosthetic repair of the aortic valve].

    PubMed

    Petrishchev, Iu I; levit, A L

    2007-01-01

    Hypo- and normothermal perfusions were compared during prosthetic repair in two patient groups matched by demographic indices, baseline severity, surgical intervention volume, anesthetic regimen, extracorporeal procedure, and cardioplegia mode. The findings suggest that there are no significant differences in the changes in central hemodynamic parameters and oxygen transport during hypo- and normothermal perfusion. During extracorporeal circulation, hypothermia is an additional stressor that causes the strain of compensatory mechanisms in the postoperative period. This leads to a more significant hyperglycemia, increases the usage of adrenomimetics, and prolongs the time of artificial ventilation. Thus, normothermal perfusion is a more preferable option of intraoperative protection during prosthetic repair of the aortic valve.

  1. Development and validation of implantable sensors for monitoring function of prosthetic heart valves: in vitro studies.

    PubMed

    Lanning, C; Shandas, R

    2003-07-01

    The development of a 'smart' heart valve prosthesis, with the intrinsic ability to monitor thrombus formation, mechanical failure and local haemodynamics and to relay this information externally, would be of significant help to clinicians. The first step towards such a valve is development of the sensors and examination of whether sensor output provides predictive information on function. Custom-made piezo-electric sensors were mounted onto the housing of mechanical valves with various layers of simulated thrombus and bioprosthetic valves with normal and stiffened leaflets. Sensor output was examined using joint time-frequency analysis. Sensors were able to detect leaflet opening and closing with high fidelity for all types of valve. The frequency content of the closing sounds for the mechanical valves contained several peaks between 100 Hz and 10 kHz, whereas closing sounds for the bioprosthetic valve contained energy in a lower frequency range (<1 kHz). A frequency peak of 47 +/- 15 Hz was seen for the normal bioprosthetic valve; this peak increased to 115 +/- 12 Hz for the valve with visibly stiffened leaflets. Total low-frequency (80-3500 Hz) energy content diminished predictably with increasing levels of thrombus for the mechanical valves. Lastly, closing sound intensity correlated well with closing pressure dynamics (dp/dt) (y = 190x - 443; r = 0.90), indicating that the sensors also provide information on haemodynamics. These studies provide initial evidence regarding the use of embedded sensors to detect prosthetic valve function. Efforts to encapsulate these sensors with telemetry into a custom valve are currently underway.

  2. Variability of Doppler microembolic signal counts in patients with prosthetic cardiac valves.

    PubMed

    Georgiadis, D; Kaps, M; Siebler, M; Hill, M; König, M; Berg, J; Kahl, M; Zunker, P; Diehl, B; Ringelstein, E B

    1995-03-01

    The purpose of this study was the evaluation of intraobserver, interobserver, and intrasubject variability in the Doppler detection of microembolic signals in patients with mechanical prosthetic valves. Simultaneously, the feasibility of automated embolus detection by means of a neuronal network was investigated. From 25 patients with mechanical prosthetic heart valves, single transcranial Doppler monitoring sessions of 30 minutes' duration were recorded on videotape, randomized, and subsequently analyzed by eight independent trained observers from three centers. Three observers evaluated these tapes on three separate occasions, blinded to their previous results. An additional 48 patients with prosthetic heart valves were repetitively monitored with transcranial Doppler ultrasonography for 30 minutes three times within 1 year to examine the long-term variability in the occurrence of microembolic signals. Finally, in an effort to assess the short-term intrasubject variability, 20 patients were examined for 90 minutes, and the results of the three 30-minute periods were compared. The interobserver, intraobserver, and intrasubject (both short- and long-term) variability was evaluated. No significant differences in microembolic signal counts were found among the different observers, between the human observers and the neuronal network, or among the three separate evaluations of stored data by the same observer. The same was true for repeat examinations of the same patient (P > .05, Student's two-paired t test and Friedman's test). The detection of microembolic signals in patients with prosthetic cardiac valves is a reproducible technique. The reliable performance of the neuronal network argues for a broader use of this device. The intrasubject stability of the microembolic rate over 1 year supports the concept that the underlying emboligenic process is associated with intrinsic mechanical properties of the valve implant and not due to a thromboembolic process in the

  3. The CarboMedics prosthetic heart valve: experience with 180 implants.

    PubMed

    Saito, Tsutomu; Misawa, Yoshio; Fuse, Katsuo; Konishi, Hiroaki

    2005-01-01

    At Jichi Medical School Hospital, three types of mechanical prosthetic valves (CarboMedics, Omnicarbon, Bicarbon) were used without randomization from 1991 to 2000. A retrospective study of valve replacements done between June 1991 and November 2000 utilizing 180 CarboMedics valves in 145 patients who had not previously undergone prosthetic valve replacement or aortic root and/or arch replacement was conducted to evaluate midterm patient outcomes to assess the future continuous use of CarboMedics valves. Women made up 47.6% of the patients and the mean age was 57.5 years (range 12-80 years). Preoperative New York Heart Association functional class was III or IV in 92.4% (134/145) of patients. Mean follow-up of 4.5 years (range 0-10.0 years) was 95.9% complete, with a total of 628 patient-years (PY). Early (within 30 postoperative days) mortality was 5.5% (8 of 145): 3 from hemorrhage, 3 from nonvalve-related heart failure, 1 from infection, and 1 from arrhythmia. There were 16 late deaths (2.54%/PY): 1 from hemorrhage, 4 from unknown causes/sudden death, 4 from nonvalve-related heart failure, and 7 from other noncardiac causes. A total of 121 patients (83.0%) were alive at the last follow-up, done in November 2000. The linearized death rate was 3.82%/year (including 1.11%/year for valve-related deaths). Linearized death rates from various causes were: bleeding, 0.96%/year; thromboembolism, 1.11%/year; thrombosis, 0.39%/year; perivalvular leak, 0.96%/year; endocarditis, 0%/year; hemolysis, 0%/year; and reoperation, 0.63%/year. No structural valve failure was observed. Comparative early mortality rates of valve replacement without aortic root replacement or arch replacement, excluding repeat valve replacement operations, in our institute, were 3.5% (12/307) for all valve types used contemporaneously, 2.6% (2/76) for Omnicarbon valves, and 2.3% (2/86) for Bicarbon valves. Although the CarboMedics valve had a rather high mortality rate of 5.5% (8/145) compared with the

  4. Quantification and Analysis of Leaflet Flutter on Biological Prosthetic Cardiac Valves.

    PubMed

    Avelar, Artur H de F; Canestri, Jean A; Bim, Camila; Silva, Maíra G M; Huebner, Rudolf; Pinotti, Marcos

    2017-09-01

    The use of porcine or bovine pericardium biological cardiac valves has as its main disadvantage a relatively short lifespan, with failures due to calcification and fatigue. Increasing these valves' durability constitutes a great challenge. An understudied phenomenon is the effect of flutter, an oscillation of the leaflets that can cause regurgitation and accelerate calcification and fatigue. As a starting point to study how to reduce or prevent these oscillations, a method was developed to quantify the flutter frequencies occurring at the point of the valve's full opening. On a test bench that simulates the heart flow, the cusp behaviors of eight biological valves were filmed with a high speed camera at 2000 frames per second at different flow rates and motion capture software obtained the frequencies and amplitudes of the vibrations of each leaflet. Oscillations in the range of 200 Hz with average amplitudes of 0.4 mm were found; larger nominal diameter valves obtained lower values, and bovine pericardial valves had superior performance compared to porcine valves. A dimensionless analysis was performed to find a relationship between the geometric and mechanical properties of the valves with the critical speed of the onset of fluttering. This relationship inspired a method to predict whether flutter will occur in the bioprosthesis. This method is a new tool for the consideration of maximizing the life of prosthetic valves. © 2016 International Center for Artificial Organs and Transplantation and Wiley Periodicals, Inc.

  5. Topography of aortic heart valves. [applied to the development of a prosthetic heart valve

    NASA Technical Reports Server (NTRS)

    Karara, H. M.

    1974-01-01

    The cooperative effort towards the development of a tri-leaflet prosthetic heart valve is described. The photogrammetric studies were conducted on silicone rubber molds. Information on data acquisition and data reduction phases is given, and certain accuracy aspects of the project are explained. The various outputs which are discussed include digital models, profiles, and contour maps.

  6. Lagrangian coherent structures and turbulence characteristics downstream of prosthetic aortic valves

    NASA Astrophysics Data System (ADS)

    de Tullio, Marco D.

    2015-11-01

    The flowfield through prosthetic heart valves is investigated by means of direct numerical simulations, considering the fully coupled fluid-structure interaction problem. Two different aortic valve models are modeled: a bileaflet mechanical and a biological one. In order to reveal fluid flow structures and to better understand the transport mechanics, Lagrangian coherent structures (LCS) are used. LCS are distinguished material surfaces that can be identified as boundaries to regions with dynamically distinct behavior, and are revealed as hypersurfaces that locally maximize the finite-time Lyapunov exponent (FTLE) fields. Post-processing the flow simulation data, first FTLE fields are calculated integrating dense meshes of Lagrangian particles backward in time, and then attracting LCS are extracted. A three-jet configuration is distinctive of bi-leaflet mechanical valves, with higher turbulent shear stresses immediately distal to the valve leaflets, while a jet-like flow emerges from the central orifice of bio-prosthetic valves, with high turbulent shear stresses occurring at the edge of the jet. Details of the numerical methodology along with a thorough analysis of the different flow structures developing during the cardiac cycle for the two configurations will be provided.

  7. Prosthetic valve endocarditis caused by Bordetella holmesii, an Acinetobacter lookalike.

    PubMed

    Jonckheere, Stijn; De Baere, Thierry; Schroeyers, Pascal; Soetens, Oriane; De Bel, Annelies; Surmont, Ignace

    2012-06-01

    We report a case of fulminant endocarditis on a prosthetic homograft aortic valve caused by Bordetella holmesii, which was successfully managed by surgical valve replacement and antibiotic treatment. B. holmesii, a strictly aerobic, small, Gram-negative coccobacillus, has been implicated as an infrequent cause of a pertussis-like syndrome and other respiratory illnesses. However, B. holmesii is also a rare cause of septicaemia and infective endocarditis, mostly in immunocompromised patients. To our knowledge, this is the first report of B. holmesii endocarditis on a prosthetic aortic valve. Routine laboratory testing initially misidentified the strain as Acinetobacter sp. Correct identification was achieved by 16S rRNA gene and outer-membrane protein A (ompA) gene sequencing. Interestingly, matrix-assisted laser desorption/ionization time-of-flight mass spectrometry also produced an accurate species-level identification. Subsequent susceptibility testing and review of the literature revealed ceftazidime, cefepime, carbapenems, aminoglycosides, fluoroquinolones, piperacillin/tazobactam, tigecycline and colistin as possible candidates to treat infections caused by B. holmesii.

  8. Corynebacterium propinquum: A Rare Cause of Prosthetic Valve Endocarditis.

    PubMed

    Jangda, Umair; Upadhyay, Ankit; Bagheri, Farshad; Patel, Nilesh R; Mendelson, Robert I

    2016-01-01

    Nondiphtheria Corynebacterium species are often dismissed as culture contaminants, but they have recently become increasingly recognized as pathologic organisms. We present the case of a 48-year-old male patient on chronic prednisone therapy for rheumatoid arthritis with a history of mitral valve replacement with prosthetic valve. He presented with fever, dizziness, dyspnea on exertion, intermittent chest pain, and palpitations. Transesophageal echocardiography revealed two medium-sized densities along the inner aspect of the sewing ring and one larger density along the atrial surface of the sewing ring consistent with vegetation. Two separate blood cultures grew Corynebacterium propinquum, which were sensitive to ceftriaxone but highly resistant to vancomycin and daptomycin. The patient completed a course of ceftriaxone and repeat TEE study and after 6 weeks demonstrated near complete resolution of the vegetation. To our knowledge, this case represents the first in the literature of Corynebacterium propinquum causing prosthetic valve endocarditis. The ability of these organisms to cause deep-seated systemic infections should be recognized, especially in immune-compromised patients.

  9. Fungal prosthetic valve endocarditis with mycotic aneurysm: Case report.

    PubMed

    Brandão, Mariana; Almeida, Jorge; Ferraz, Rita; Santos, Lurdes; Pinho, Paulo; Casanova, Jorge

    2016-09-01

    Fungal prosthetic valve endocarditis is an extremely severe form of infective endocarditis, with poor prognosis and high mortality despite treatment. Candida albicans is the most common etiological agent for this rare but increasingly frequent condition. We present a case of fungal prosthetic valve endocarditis due to C. albicans following aortic and pulmonary valve replacement in a 38-year-old woman with a history of surgically corrected tetralogy of Fallot, prior infective endocarditis and acute renal failure with need for catheter-based hemodialysis. Antifungal therapy with liposomal amphotericin B was initiated prior to cardiac surgery, in which the bioprostheses were replaced by homografts, providing greater resistance to recurrent infection. During hospitalization, a mycotic aneurysm was diagnosed following an episode of acute arterial ischemia, requiring two vascular surgical interventions. Despite the complications, the patient's outcome was good and she was discharged on suppressive antifungal therapy with oral fluconazole for at least a year. The reported case illustrates multiple risk factors for fungal endocarditis, as well as complications and predictors of poor prognosis, demonstrating its complexity. Copyright © 2016 Sociedade Portuguesa de Cardiologia. Publicado por Elsevier España, S.L.U. All rights reserved.

  10. Prosthetic Tricuspid Valve Thrombosis: Three Case Reports and Literature Review

    PubMed Central

    Yaminisharif, Ahmad; Alemzadeh-Ansari, Mohammad Javad; Ahmadi, Seyed Hossein

    2012-01-01

    A common complication of prosthetic heart valves is thrombosis. Although the incidence of prosthetic valve thrombosis (PVT) in the tricuspid position is high, there are not enough data on the management of it, in contrast to left-sided PVT. Here, we describe three cases of tricuspid PVT with three different management approaches: thrombolytic therapy; close observation with oral anticoagulants; and surgery. The first case was a woman who suffered from recurrent PVT, for which we successfully used Tenecteplase for second and third episodes. We employed Tenecteplase in this case for the first time in the therapy of tricuspid PVT. The second case had fixed leaflets in open position while being symptomless. At six months' follow-up, with the patient having taken oral anticoagulants, the motion of the leaflets was restricted and she was symptomfree. The last case was a woman who had a large thrombus in the right atrium immediately after mitral and tricuspid valvular replacement. The patient underwent re-replacement surgery and a new biological valve was implanted in the tricuspid position. Also, we review the literature on the pathology, signs and symptoms, diagnosis, and management of tricuspid PVT. PMID:23323074

  11. Corynebacterium propinquum: A Rare Cause of Prosthetic Valve Endocarditis

    PubMed Central

    Bagheri, Farshad; Patel, Nilesh R.; Mendelson, Robert I.

    2016-01-01

    Nondiphtheria Corynebacterium species are often dismissed as culture contaminants, but they have recently become increasingly recognized as pathologic organisms. We present the case of a 48-year-old male patient on chronic prednisone therapy for rheumatoid arthritis with a history of mitral valve replacement with prosthetic valve. He presented with fever, dizziness, dyspnea on exertion, intermittent chest pain, and palpitations. Transesophageal echocardiography revealed two medium-sized densities along the inner aspect of the sewing ring and one larger density along the atrial surface of the sewing ring consistent with vegetation. Two separate blood cultures grew Corynebacterium propinquum, which were sensitive to ceftriaxone but highly resistant to vancomycin and daptomycin. The patient completed a course of ceftriaxone and repeat TEE study and after 6 weeks demonstrated near complete resolution of the vegetation. To our knowledge, this case represents the first in the literature of Corynebacterium propinquum causing prosthetic valve endocarditis. The ability of these organisms to cause deep-seated systemic infections should be recognized, especially in immune-compromised patients. PMID:27891149

  12. Practical tips and tricks for assessing prosthetic valves and detecting paravalvular regurgitation using cardiac CT.

    PubMed

    O'Neill, Ailbhe C; Martos, Ramon; Murtagh, Gillian; Ryan, Edmund Ronan; McCreery, Charles; Keane, David; Quinn, Martin; Dodd, Jonathan D

    2014-01-01

    Paravalvular leaks are an uncommon but serious complication of prosthetic valves. Transthoracic echocardiography is used in the assessment of prosthetic valves but can be limited by acoustic shadowing from the prosthesis and poor acoustic windowing. Small case series have previously shown cardiac CT to have promising results in detecting paravalvular leaks. We assessed 32 valves in our institution on cardiac CT using echocardiography results as standard and developed methods for improved evaluation of prosthetic valves. These include optimizing prescan drug therapy for heart rate control, optimum window and center adjustments, and carefully selected image planes to best demonstrate the valve ring and valve annulus. Recognition of surgical material is also important to recognize. In this review, we provide a detailed description of these techniques with imaging examples of prosthetic valve evaluation using cardiac CT. Copyright © 2014 Society of Cardiovascular Computed Tomography. Published by Elsevier Inc. All rights reserved.

  13. Antithrombotic management of patients with prosthetic heart valves: current evidence and future trends.

    PubMed

    Sun, Jack C J; Davidson, Michael J; Lamy, Andre; Eikelboom, John W

    2009-08-15

    Over 4 million people worldwide have received a prosthetic heart valve, and an estimated 300,000 valves are being implanted every year. Prosthetic heart valves improve quality of life and survival of patients with severe valvular heart disease, but the need for antithrombotic therapy to prevent thrombotic complications in valve recipients poses challenges for clinicians and patients. Here, we review antithrombotic therapies for patients with prosthetic heart valves and management of thromboembolic complications. Advances in antithrombotic therapy and valve technologies are likely to improve the management of patients with prosthetic heart valves in developed countries, but the most important unmet need and potential for benefit from these new therapies is in developing countries where a massive and rapidly increasing burden of valvular heart disease exists.

  14. Epidemic of prosthetic valve endocarditis caused by Staphylococcus epidermidis.

    PubMed Central

    van den Broek, P J; Lampe, A S; Berbée, G A; Thompson, J; Mouton, R P

    1985-01-01

    In an epidemic of prosthetic valve endocarditis caused by Staphylococcus epidermidis the surgeon was found to be the source of contamination. The probable route was accidental puncture of gloves during operation. During the epidemiological investigation a second cluster of patients contaminated with Staph epidermidis during open heart surgery was found also related to one surgeon. This strain caused no detectable signs or symptoms of infection. Carriage of virulent staph epidermidis has rarely been recognised as a hazard but may have serious consequences. PMID:3929975

  15. Treatment of Prosthetic Valve Thrombosis: Current Evidence and Future Directions

    PubMed Central

    Biteker, Murat; Altun, Ibrahim; Basaran, Ozcan; Dogan, Volkan; Yildirim, Birdal; Ergun, Gokhan

    2015-01-01

    Prosthetic heart valve thrombosis (PVT) is a rare but serious complication with high morbidity and mortality. The optimal treatment of the PVT is controversial and depends on thrombus location and size, the patient’s functional class, the risk of surgery or thrombolysis, and the clinician’s experience. Although surgical therapy has been the traditional therapeutic approach, studies with low-dose and slow-infusion rates of thrombolytic agents have revealed excellent results. This article reviews the various treatment options in patient with PVT. PMID:26566406

  16. A 3D velocimetry study of the flow through prosthetic heart valves

    NASA Astrophysics Data System (ADS)

    Ledesma, R.; Zenit, R.; Pulos, G.; Sanchez, E.; Juarez, A.

    2006-11-01

    Blood damage commonly appears in medical valve prothesis. It is a mayor concern for the designers and surgeons. It is well known that this damage and other complications result from the modified fluid dynamics through the replacement valve. To evaluate the performance of prosthetic heart valves, it is necessary to study the flow through them. To conduct this study , we have built a flow channel that emulates cardiac conditions and allows optical access such that a 3D-PIV velocimetry system could be used. The experiments are aimed to reconstruct the downstream structure of the flow through a mechanical and a bio-material tricuspid heart valve prothesis. Preliminary results show that the observed coherent structures can be related with haemolysis and trombosis, illnesses commonly found in valve prothesis recipients. The mean flow, the levels of strain rate and the turbulence intensity generated by the valves can also be directly related to blood damage. In general, bio-material made valves tend to reduce these complications.

  17. Identification of critical zones in the flow through prosthetic heart valves

    NASA Astrophysics Data System (ADS)

    Lopez, A.; Ledesma, R.; Zenit, R.; Pulos, G.

    2008-11-01

    The hemodynamic properties of prosthetic heart valves can cause blood damage and platelet activation due to the non- physiological flow patterns. Blood recirculation and elevated shear stresses are believed to be responsible for these complications. The objective of this study is to identify and quantify the conditions for which recirculation and high stress zones appear. We have performed a comparative study between a mechanical monoleaflet and biological valve. In order to generate the flow conditions to test the prosthesis, we have built a hydraulic circuit which reproduces the human systemic circulation, on the basis of the Windkessel model. This model is based on an electrical analogy which consists of an arterial resistance and compliance. Using PIV 3D- Stereo measurements, taken downstream from the prosthetic heart valves, we have reconstructed the full phase-averaged tridimensional velocity field. Preliminary results show that critical zones are more prominent in mechanical prosthesis, indicating that valves made with bio-materials are less likely to produce blood trauma. This is in accordance with what is generally found in the literature.

  18. Comparison of dysfunction with mechanical and porcine mitral valve prostheses.

    PubMed

    Magilligan, D J; Oyama, C; Alam, M

    1985-09-01

    We reviewed the incidence of dysfunction of the Smeloff-Cutter mechanical prosthetic valve and the Hancock porcine prosthetic valve in the mitral position. The Smeloff-Cutter valve was implanted from 1966 to 1972; 107 patients were discharged from the hospital and were at risk for dysfunction. Follow-up averaged 10 +/- 0.7 years SD. The Hancock valve was implanted from 1971 through 1984; 473 patients were at risk and follow-up averaged 4.7 +/- 3.4 years SD. Dysfunction of the Smeloff-Cutter valve occurred as thrombosis with incomplete poppet opening in 13 patients. Dysfunction of the Hancock valve occurred as primary tissue failure in 47 patients. At 10 years the freedom from dysfunction of the Smeloff-Cutter valve was 84 +/- 5% SE and that for the Hancock valve was 71 +/- 4% SE (p greater than .06). The mortality associated with dysfunction of the Smeloff-Cutter valve was 46%; mortality associated with dysfunction of the Hancock valve was 15% (p less than .02). At 10 years the Hancock valve had a greater incidence of dysfunction than the Smeloff-Cutter valve but this difference was not statistically significant. The mortality associated with dysfunction of the Smeloff-Cutter valve, however, was three times that associated with dysfunction of the Hancock valve.

  19. Prosthetic Aortic Valve Fixation Study: 48 Replacement Valves Analyzed Using Digital Pressure Mapping.

    PubMed

    Lee, Candice Y; Wong, Joshua K; Ross, Ronald E; Liu, David C; Khabbaz, Kamal R; Martellaro, Angelo J; Gorea, Heather R; Sauer, Jude S; Knight, Peter A

    Prostheses attachment is critical in aortic valve replacement surgery, yet reliable prosthetic security remains a challenge. Accurate techniques to analyze prosthetic fixation pressures may enable the use of fewer sutures while reducing the risk of paravalvular leaks (PVL). Customized digital thin film pressure transducers were sutured between aortic annulus models and 21-mm bioprosthetic valves with 15 × 4-mm, 12 × 4-mm, or 9 × 6-mm-wide pledgeted mattress sutures. Simulating open and minimally invasive access, 4 surgeons, blinded to data acquisition, each secured 12 valves using manual knot-tying (hand-tied [HT] or knot-pusher [KP]) or automated titanium fasteners (TFs). Real-time pressure measurements and times were recorded. Two-dimensional (2D) and 3D pressure maps were generated for all valves. Pressures less than 80 mm Hg were considered at risk for PVL. Pressures under each knot (intrasuture) fell less than 80 mm Hg for 12 of 144 manual knots (5/144 HT, 7/144 KP) versus 0 of 288 TF (P < 0.001). Pressures outside adjacent sutures (extrasuture) were less than 80 mm Hg in 10 of 60 HT, zero of 60 KP, and zero of 120 TF sites for 15 × 4-mm valves; 17 of 48 HT, 25 of 48 KP, and 12 of 96 TF for 12 × 4-mm valves; and 15 of 36 HT, 17 of 36 KP, and 9 and 72 TF for 9 × 6-mm valves; P < 0.001 all manual versus TF. Annular areas with pressures less than 80 mm Hg ranged from 0% of the sewing-ring area (all open TF) to 31% (12 × 4 mm, KP). The average time per manual knot, 46 seconds (HT, 31 seconds; KP, 61 seconds), was greater than TF, 14 seconds (P < 0.005). Reduced operative times and PVL risk would fortify the advantages of surgical aortic valve replacement. This research encourages continued exploration of technical factors in optimizing prosthetic valve security.

  20. Long-term survival after operations for native and prosthetic valve endocarditis.

    PubMed

    Edlin, Pearl; Westling, Katarina; Sartipy, Ulrik

    2013-05-01

    The objective was to compare long-term survival after operations for active infective endocarditis (IE) in native or prosthetic valves. We also investigated differences in early death and postoperative complications. We conducted a population-based cohort study including all patients who underwent operations for IE between January 2002 and July 2012. The SWEDEHEART (Swedish Web-system for Enhancement and Development of Evidence-based care in Heart disease Evaluated According to Recommended Therapies) registry and patients records were used to acquire information about patient characteristics, preoperative comorbidities, and postoperative complications. Date of death was ascertained by using the Swedish personal identity number and the Total Population Register at Statistics Sweden. We used multivariable Cox regression to analyze the association between prosthetic valve IE and survival. Of the 252 included patients, 22% underwent operations for prosthetic valve IE. There was no significant difference in unadjusted 5-year survival between patients who underwent operations for prosthetic valve IE compared with native valve IE (75% vs 65%; p = 0.34). We found no significant association between operations for prosthetic valve IE and death (multivariable adjusted hazard ratio, 0.83; 95% confidence interval, 0.46 to 1.49) compared with native valve IE. There was no significant difference in 30-day mortality between prosthetic and native valve IE (14% vs 12%; p = 0.61), with a multivariable adjusted odds ratio of 0.62 (95% confidence interval, 0.24 to 1.64). We found no significant difference in long-term survival between patients who underwent operations for prosthetic valve IE compared with native valve IE. Early death and morbidity were also similar between the groups. These results are promising because an increasing amount of patients with IE have prosthetic valve infections. Copyright © 2013 The Society of Thoracic Surgeons. Published by Elsevier Inc. All rights

  1. [Homografts for mitral valve replacement in florid endocarditis--an alternative to prosthetic replacement].

    PubMed

    Gulbins, H; Kreuzer, E; Haushofer, M; Uhlig, A; Reichart, B

    1999-05-01

    Homografts for valve replacement are indicated in acute valve endocarditis. It is assumed that they possess anti-infective properties. Homografts are an established indication in aortic valve replacement. We present our early results with homografts for mitral valve replacement in acute endocarditis. Between July 1996 and March 1998 we used cryopreserved homografts for mitral valve replacement in seven patients. In three cases (age 24, 42, and 34 years) the indication was an acute endocarditis with subsequent severe mitral valve insufficiency. The size of the required homograft was measured preoperatively using transesophageal echocardiography. For implantation the technique described by A. Carpentier was used; for stabilization of the mitral anulus a valvular ring (Physio) was implanted. Follow-up was done every six months including clinical and echocardiographical examinations. After the first postoperative year an Ultrafast-CT was done in addition. One patient had complete mitral valve replacement, in the other two cases the diseased parts of the valve were completely excised and the valve was repaired using a partial homograft. There were no perioperative deaths. In the follow-ups, up to 24 months of uneventful homograft function was documented by echocardiography; no insufficiency > degree I was seen on color Doppler echocardiography. At the last follow-up (mean follow-up 16 months, range 12 to 24 months) the average mitral valve orifice was 2.5 +/- 0.5 cm2, the mean pressure gradient 2.8 +/- 0.8 mm Hg. In Ultrafast-CT no morphological abnormalities of the mitral valves and no dilatation of the left ventricle were seen. There were no signs of a recurrence of the endocarditis in any patient during the follow-up period. Homografts for mitral valve replacement are an interesting alternative to prosthetic valve replacement, especially in younger patients. In cases with acute endocarditis, in which mechanical prosthesis should not be used, a reconstruction or

  2. A novel solution to prosthetic valve dehiscence after aortic valve surgery in Behçet's disease.

    PubMed

    Jung, Yochun; Ahn, Byoung Hee; Lee, Kyo Seon; Jeong, In Seok; Kim, Kye Hun; Na, Kook Joo; Ryu, Sang-Wan; Oh, Sang Gi

    2017-03-01

    Prosthetic valve dehiscence after aortic valve surgery in Behçet's disease patients is common. We aimed to validate the usefulness of our new technique 'subannular endomyocardial implantation of valve prosthesis' designed to prevent prosthetic valve dehiscence. Subannular endomyocardial implantation of valve prosthesis involves suturing the sewing cuff of the valve prosthesis in the endomyocardium below the aortic annulus, which is based on the idea that annular tissue should be excluded from the suture line in Behçet's disease patients. Medical records of 7 patients in whom the new technique was performed between 2002 and 2014 were reviewed. Five men and two women were included (median age, 44 years). Aortic root replacement was performed in 6 cases, and aortic valve replacement in 1. No operative mortality occurred. Postoperatively, complete atrioventricular block developed in 3 cases, and permanent pacemakers were implanted in 2. No reoperation was performed for prosthetic valve dehiscence during the median 7.8-year follow-up. One late death occurred due to sudden cardiac arrest 8.4 years after surgery. One additional permanent pacemaker was implanted for complete atrioventricular block, which developed at 4.2 years postoperatively. The last echocardiography (median, 6.7 years after surgery) revealed no paravalvular leakages. Subannular endomyocardial implantation of valve prosthesis seems useful for preventing prosthetic valve dehiscence after aortic valve surgery for Behçet's disease. It poses a risk of complete atrioventricular block, but considering the high reoperation rate and mortality due to prosthetic valve dehiscence after conventional aortic valve surgery, this risk seems reasonable.

  3. Prosthetic valve endocarditis 7 months after transcatheter aortic valve implantation diagnosed with 3D TEE.

    PubMed

    Sarı, Cenk; Durmaz, Tahir; Karaduman, Bilge Duran; Keleş, Telat; Bayram, Hüseyin; Baştuğ, Serdal; Özen, Mehmet Burak; Bayram, Nihal Akar; Bilen, Emine; Ayhan, Hüseyin; Kasapkara, Hacı Ahmet; Bozkurt, Engin

    2016-01-01

    Transcatheter aortic valve implantation (TAVI) was introduced as an alternative treatment for patients with severe symptomatic aortic stenosis for whom surgery would be high-risk. Prosthetic aortic valve endocarditis is a serious complication of surgical AVR (SAVR) with high morbidity and mortality. According to recent cases, post-TAVI prosthetic valve endocarditis (PVE) seems to occur very rarely. We present the case of a 75-year-old woman who underwent TAVI (Edwards Saphien XT) with an uneventful postoperative stay. She was diagnosed with endocarditis using three dimensional (3D) echocardiography on the TAVI device 7 months later and she subsequently underwent surgical aortic valve replacement. Little experience of the interpretation of transoesophageal echocardiography (TEE) and the clinical course and effectiveness of treatment strategies in post-TAVI endocarditis exists. We report a case of PVE in a TAVI patient which was diagnosed with three-dimensional transoesophageal echocardiography (3DTEE). Copyright © 2016 Hellenic Cardiological Society. Published by Elsevier B.V. All rights reserved.

  4. Prosthetic Valve Dysfunction 35 Years after Mitral Valve Replacement with a Starr-Edwards Caged-disc Valve.

    PubMed

    Yokokawa, Tetsuro; Ohara, Takahiro; Takashio, Seiji; Sakamoto, Mari; Wada, Yuko; Nakamura, Kenji; Takahama, Hiroyuki; Amaki, Makoto; Hasegawa, Takuya; Sugano, Yasuo; Kanzaki, Hideaki; Yasuda, Satoshi; Ogawa, Hisao; Fujita, Tomoyuki; Kobayashi, Junjiro; Okamoto, Yoko; Matsuyama, Taka-Aki; Ishibashi-Ueda, Hatsue; Anzai, Toshihisa

    2016-01-01

    A 49-year-old man was admitted to our hospital with a chief complaint of dyspnea. He had a history of mitral valve replacement (MVR) with a Starr-Edwards (SE) caged-disc valve at the age of 14. Echocardiography revealed elevated trans-valvular pressure gradient of the mitral prosthetic valve with neither disk motion abnormality nor abnormal structure. Catheterization confirmed an elevation of the mean diastolic gradient of the mitral valve to 12.3 mmHg. Re-MVR was performed, and abnormal tissue attached to the cage of the valve and proliferating beneath the valve was observed. Histologic examination revealed them as fibrinous tissue and mild pannus proliferation, respectively. This rare case report focuses on long-term follow-up and the complication of a SE caged-disc valve. A SE caged-disc valve may become stenotic, only detected with a trans-valvular pressure gradient without any disk motion abnormality or abnormal structure during a prolonged follow-up period.

  5. FFT Techniques for the Spectral Analysis of Prosthetic Heart Valve Sounds

    PubMed Central

    Durand, L.-G.; de Guise, J.; Guardo, R.

    1980-01-01

    Sounds produced by prosthetic heart valves are known to contain diagnostic information regarding the structural and functional integrity of their components. Analog techniques for processing prosthetic valve phonocardiograms have met with limited success in extracting this information, because of their poor spectral resolution and lack of versatility. Numerical methods of signal processing overcome most of these limitations, but the need for a computer to implement numerical methods raises the question of cost-effectiveness in many applications. Numerical analysis of prosthetic valve signals has therefore received very little attention outside the academic and laboratory context. Cost reductions in computer hardware arising from the use of micro-processors, make it possible to envisage dedicated clinical instruments for processing prosthetic valve sounds in view of assessing overall valve performance and detecting component degradation at an early stage. Basic spectral considerations for the design of such instruments are discusses in this paper.

  6. Laser Doppler anemometry measurements of steady flow through two bi-leaflet prosthetic heart valves.

    PubMed

    Bazan, Ovandir; Ortiz, Jayme Pinto; Vieira, Francisco Ubaldo; Vieira, Reinaldo Wilson; Antunes, Nilson; Tabacow, Fabio Bittencourt Dutra; Costa, Eduardo Tavares; Petrucci, Orlando

    2013-01-01

    In vitro hydrodynamic characterization of prosthetic heart valves provides important information regarding their operation, especially if performed by noninvasive techniques of anemometry. Once velocity profiles for each valve are provided, it is possible to compare them in terms of hydrodynamic performance. In this first experimental study using laser doppler anemometry with mechanical valves, the simulations were performed at a steady flow workbench. To compare unidimensional velocity profiles at the central plane of two bi-leaflet aortic prosthesis from St. Jude (AGN 21 - 751 and 21 AJ - 501 models) exposed to a steady flow regime, on four distinct sections, three downstream and one upstream. To provide similar conditions for the flow through each prosthesis by a steady flow workbench (water, flow rate of 17L/min.) and, for the same sections and sweeps, to obtain the velocity profiles of each heart valve by unidimensional measurements. It was found that higher velocities correspond to the prosthesis with smaller inner diameter and instabilities of flow are larger as the section of interest is closer to the valve. Regions of recirculation, stagnation of flow, low pressure, and flow peak velocities were also found. Considering the hydrodynamic aspect and for every section measured, it could be concluded that the prosthesis model AGN 21 - 751 (RegentTM) is superior to the 21 AJ - 501 model (Master Series). Based on the results, future studies can choose to focus on specific regions of the these valves.

  7. Laser Doppler anemometry measurements of steady flow through two bi-leaflet prosthetic heart valves

    PubMed Central

    Bazan, Ovandir; Ortiz, Jayme Pinto; Vieira Junior, Francisco Ubaldo; Vieira, Reinaldo Wilson; Antunes, Nilson; Tabacow, Fabio Bittencourt Dutra; Costa, Eduardo Tavares; Petrucci Junior, Orlando

    2013-01-01

    Introduction In vitro hydrodynamic characterization of prosthetic heart valves provides important information regarding their operation, especially if performed by noninvasive techniques of anemometry. Once velocity profiles for each valve are provided, it is possible to compare them in terms of hydrodynamic performance. In this first experimental study using laser doppler anemometry with mechanical valves, the simulations were performed at a steady flow workbench. Objective To compare unidimensional velocity profiles at the central plane of two bi-leaflet aortic prosthesis from St. Jude (AGN 21 - 751 and 21 AJ - 501 models) exposed to a steady flow regime, on four distinct sections, three downstream and one upstream. Methods To provide similar conditions for the flow through each prosthesis by a steady flow workbench (water, flow rate of 17L/min. ) and, for the same sections and sweeps, to obtain the velocity profiles of each heart valve by unidimensional measurements. Results It was found that higher velocities correspond to the prosthesis with smaller inner diameter and instabilities of flow are larger as the section of interest is closer to the valve. Regions of recirculation, stagnation of flow, low pressure, and flow peak velocities were also found. Conclusions Considering the hydrodynamic aspect and for every section measured, it could be concluded that the prosthesis model AGN 21 - 751 (RegentTM) is superior to the 21 AJ - 501 model (Master Series). Based on the results, future studies can choose to focus on specific regions of the these valves. PMID:24598950

  8. Thrombosis of A Prosthetic Mitral Valve After Withdrawal of Phenprocoumon Therapy

    PubMed Central

    Wilke, Andreas; Wende, Christian M.; Horst, Michael; Steverding, Dietmar

    2011-01-01

    Patients with prosthetic heart valves require lifelong oral anticoagulant therapy based on vitamin K antagonists. These patients may need interruption of their anticoagulant therapy if they have to undergo surgery. The clinical challenge is to identify patients who can safely undergo surgery while continuing their vitamin K antagonist treatment and those who have to take short-acting heparin as part of a bridging therapy. Here we present a case of a patient with a prosthetic mitral valve whose oral anticoagulant therapy was unnecessarily discontinued by the GP prior to an upcoming cataract surgery. As a result, the patient developed thrombosis of the prosthetic mitral valve which needed to be surgically replaced.

  9. Prosthetic Mitral Surgical Valve in Transcatheter Aortic Valve Replacement Recipients: A Multicenter Analysis.

    PubMed

    Amat-Santos, Ignacio J; Cortés, Carlos; Nombela Franco, Luis; Muñoz-García, Antonio J; Suárez De Lezo, Jose; Gutiérrez-Ibañes, Enrique; Serra, Vicenç; Larman, Mariano; Moreno, Raúl; De La Torre Hernandez, Jose M; Puri, Rishi; Jimenez-Quevedo, Pilar; Hernández García, José M; Alonso-Briales, Juan H; García, Bruno; Lee, Dae-Hyun; Rojas, Paol; Sevilla, Teresa; Goncalves, Renier; Vera, Silvio; Gómez, Itziar; Rodés-Cabau, Josep; San Román, José A

    2017-10-09

    The aim of this study was to determine the prognosis and specific complications of patients with prosthetic mitral valves (PMVs) undergoing transcatheter aortic valve replacement (TAVR). TAVR is performed relatively often in patients with PMVs, but specific risks are not well described. A multicenter analysis was conducted, including patients with severe symptomatic aortic stenosis who underwent TAVR at 10 centers. Patients' clinical characteristics and outcomes were evaluated according to the presence of a PMV. The mean age of the study population (n = 2,414) was 81 ± 8 years, and 48.8% were men. A total of 91 patients (3.77%) had PMVs. They were more commonly women, younger, and had higher surgical risk. PMVs were implanted a median of 14 years before TAVR, and most patients had mechanical prostheses (73.6%). Eighty-six patients (94.5%) were on long-term vitamin K inhibitor therapy, and bridging antithrombotic therapy was administered in 59 (64.8%). TAVR device embolization occurred in 6.7% (vs. 3.3% in the non-PMV group; p = 0.127), in all instances when distance between the PMV and the aortic annulus was <7 mm. Mortality rates did not show a difference, but the rate of bleeding was higher in patients with PMV (24.2% vs. 16.1%; p = 0.041), even in those treated via the transfemoral approach (22.2% vs. 13.9%; p = 0.048). Indeed, bleeding complications, prior atrial fibrillation, chronic obstructive pulmonary disease, surgical risk, and New York Heart Association functional class were independent predictors of mortality. TAVR presents similar mortality irrespective of the presence of a PMV. However, patients with PMVs had higher bleeding risk that was independently associated with higher mortality. Risk for valve embolization was relatively high, but it occurred only in patients with PMV-to-aortic annulus distances <7 mm. Copyright © 2017 American College of Cardiology Foundation. Published by Elsevier Inc. All rights reserved.

  10. Valve mechanism having variable valve timing

    SciTech Connect

    Oda, H.; Masuda, S.; Morita, Y.

    1986-04-08

    This patent describes a valve mechanism for an internal combustion engine which consists of a camshaft rotatable about a longitudinal axis and having a cam formed thereon, a swingable member mounted for swinging movement about the longitudinal axis of the camshaft and formed with a tappet receiving hole. A valve tapper is received in the tappet receiving hole for a slidable movement along the tappet receiving hole. The tappet has a cam which engages the surface at one end and a stem engages the surface at the other end. A valve stem is mounted for axial movement and engaged at one end with the stem engaging, surface of the tappet to be actuated thereby. A valve timing control swingably moves the swingable member and the tappet about the camshaft axis in accordance with predetermined engine operating conditions to thereby change valve opening and valve closing timing. The control includes means for holding the swingable member at a first position. The tappet and valve stem are in contact at a first position on the stem engaging surface of the tappet and the direction of the slidable movement of the tappet is aligned with the direction of the axial movement of the valve stem at least under heavy load, high speed engine operation, and for moving the swingable member from the first position to a second position. The tappet and valve stem are in contact at a second position on the stem engaging surface of the tappet at low speed engine operation to effect a change in valve opening and valve closing timing.

  11. [Usefulness of echocardiography for detecting prosthetic valve dysfunction; report of a case].

    PubMed

    Oyama, Shogo; Ohuchi, Shingo; Okubo, Tadashi; Kumagai, Kazuya

    2014-10-01

    A 78-year-old woman with a history of mitral valve stenosis underwent open mitral commissurotomy in 1976. In 1990, she underwent mitral valve replacement (Medtronic-Hall 29 mm), tricuspid annuloplasty(DeVega method), and pacemaker implantation for bradycardiac atrial fibrillation. However, in June 2012, she developed anemia of unknown cause. Prosthetic valve dysfunction was suspected, because intermittent changes in the left ventricular inflow was detected by echocardiography. Fluoroscopy actually confirmed the presence of prosthetic valve dysfunction. Therefore mitral valve re-replacement(ATS Medical, Inc. 29 mm) and tricuspid annuloplasty (Cosgrove ring 30 mm) were performed. Monitoring the changes in the left ventricular inflow is recommended when prosthetic valve dysfunction in a single leaflet is suspected.

  12. Lack of Accessible Data on Prosthetic Heart Valves.

    PubMed

    Frank, Michelle; Ganzoni, Giulia; Starck, Christoph; Grünenfelder, Jürg; Corti, Roberto; Gruner, Christiane; Hürlimann, David; Tanner, Felix C; Jenni, Rolf; Greutmann, Matthias; Biaggi, Patric

    2016-03-01

    Incomplete information on characteristics of prosthetic heart valves (PHV) may lead to inappropriate choices for PHV implantation (patient-prosthesis-mismatch) or erroneous interpretation of PHV function after implantation. No single and easy accessible source provides all relevant information on PHV. The aim of this study was to provide a comprehensive overview of available data for the majority of PHVs and annuloplasty rings. Information was collected by reviewing articles published on www.pubmed.org up to December 2014 and by written contact to all PHV manufacturers. Four areas of interest were defined: (1) PHV image, (2) in vivo transvalvular gradients, (3) effective orifice area (EOA) calculators and (4) PHV dimensions. Available information was classified as complete (all categories), partial (two or three categories) or minimal (one category). 108 PHV (including homografts) and 34 annuloplasty rings systems were identified. The information on PHV was complete, partial or minimal in 19.5, 61.0 and 19.5% of PHV, respectively. In 91.6% a picture of the valve could be obtained, whereas normative data for transvalvular gradients and EOA calculators were available in 63.0 and 25.0% of all PHV, respectively. The available data was summarized on a new open access webpage ( www.valveguide.ch ). There is a lack of accessible data on PHV dimensions, normal transvalvular gradients and effective orifice area calculators, although such information is of crucial importance for proper PHV assessment.

  13. Multidetector CT angiography in evaluation of prosthetic heart valve dysfunction.

    PubMed

    Habets, Jesse; Mali, Willem P T M; Budde, Ricardo P J

    2012-01-01

    Prosthetic heart valves (PHVs) are commonly implanted to replace diseased native heart valves. PHV dysfunction is an infrequent but potentially life-threatening condition. In daily clinical practice, transthoracic and transesophageal echocardiography and fluoroscopy are the imaging modalities used for diagnostic evaluation of suspected PHV dysfunction. These modalities may not allow determination of the cause of PHV dysfunction, mostly because of acoustic shadowing. Multidetector computed tomographic (CT) angiography is a promising complementary technique for evaluation of PHVs, especially in patients with PHV obstruction and endocarditis. The CT image quality of PHVs mainly depends on their composition, with most causing only limited artifacts. Retrospectively electrocardiographically gated acquisition is advisable for PHV imaging because it enables dynamic leaflet evaluation and anatomic assessment in both systole and diastole. For accurate image interpretation, dedicated reconstruction in plane with and perpendicular to the PHV leaflets is mandatory. Besides PHV assessment, CT also provides information on the coronary arteries, the location and patency of bypass grafts, the dimensions of the aorta, and the distance between the sternum and right ventricle, information valuable for planning repeat surgery. To achieve the optimal diagnostic yield in PHV imaging, multidisciplinary cooperation between the departments of cardiology, cardiothoracic surgery, and radiology is crucial.

  14. Doppler echocardiographic characteristics of normal and dysfunctioning prosthetic valves in the tricuspid and mitral position.

    PubMed Central

    Pye, M; Weerasana, N; Bain, W H; Hutton, I; Cobbe, S M

    1990-01-01

    The Doppler echocardiographic characteristics of 70 prosthetic valves in 35 patients are reported. Twenty nine patients had a Björk-Shiley prosthesis in both mitral and tricuspid positions and six had Carpentier-Edwards valves in both sites. Five of the patients had abnormal tricuspid prostheses on the basis of clinical and echocardiographic criteria. Pulsed wave Doppler echocardiography was used in all examinations. The pressure half times for the normal tricuspid prosthetic valves, 105 (40) ms (Björk-Shiley) and 97 (53) ms (Carpentier-Edwards), were significantly longer than those of normal mitral prosthetic valves, 75 (18) ms (Björk-Shiley) and 83 (15) ms (Carpentier-Edwards). The range of pressure half times for the abnormal tricuspid valves (237-530 ms) was distinct from that of the apparently normal tricuspid prosthetic valves (38-197 ms). There was an increase in the peak velocity of the obstructed tricuspid prosthetic valves (1.69 (0.12) m/s) in comparison with normal prostheses (1.06 (0.26) m/s). The normal range of pressure half times for the Björk-Shiley and Carpentier-Edwards valves in the mitral position is not applicable to the same valves in the tricuspid position. The valve appears to function well with very long pressure half times but a pressure half time of greater than 200 ms coupled with a peak velocity of greater than 1.60 ms without significant valve regurgitation indicates tricuspid obstruction of the tricuspid prosthetic valve. PMID:2310643

  15. Creative mechanism design for a prosthetic hand.

    PubMed

    Chang, Wen-Tung; Tseng, Ching-Huan; Wu, Long-Long

    2004-01-01

    In this paper, an auxiliary methodology called the creative mechanism design is introduced into the innovation of gripping devices for prosthetic hands. This methodology is a systematic approach based on modification of existing devices for the generation of all possible topological structures of mechanisms and mechanical devices. An existing gripping device (Teh Lin ATG-5F prosthetic hand) constructed by a planar six-bar linkage with one degree of freedom is dealt with by using this methodology. Through the processes of generalization, number synthesis, specialization and particularization for the existing design, five new mechanisms are created in this study to apply to anthropomorphic prosthetic hands. The results show that the methodology for creative mechanism design is a powerful tool for creating new categories of mechanisms to avoid existing designs that have patent protection and can help designers in the conceptual phase. Also, this methodology is validated as a useful way to improve prosthetic hands for amputees.

  16. Experimental Validation of a Cardiac Simulator for in vitro Evaluation of Prosthetic Heart Valves

    PubMed Central

    Bazan, Ovandir; Ortiz, Jayme Pinto

    2016-01-01

    Objective This work describes the experimental validation of a cardiac simulator for three heart rates (60, 80 and 100 beats per minute), under physiological conditions, as a suitable environment for prosthetic heart valves testing in the mitral or aortic position. Methods In the experiment, an aortic bileaflet mechanical valve and a mitral bioprosthesis were employed in the left ventricular model. A test fluid of 47.6% by volume of glycerin solution in water at 36.5ºC was used as blood analogue fluid. A supervisory control and data acquisition system implemented previously in LabVIEW was applied to induce the ventricular operation and to acquire the ventricular signals. The parameters of the left ventricular model operation were based on in vivo and in vitro data. The waves of ventricular and systemic pressures, aortic flow, stroke volume, among others, were acquired while manual adjustments in the arterial impedance model were also established. Results The acquired waves showed good results concerning some in vivo data and requirements from the ISO 5840 standard. Conclusion The experimental validation was performed, allowing, in future studies, characterizing the hydrodynamic performance of prosthetic heart valves. PMID:27556315

  17. Experimental Validation of a Cardiac Simulator for in vitro Evaluation of Prosthetic Heart Valves.

    PubMed

    Bazan, Ovandir; Ortiz, Jayme Pinto

    2016-04-01

    This work describes the experimental validation of a cardiac simulator for three heart rates (60, 80 and 100 beats per minute), under physiological conditions, as a suitable environment for prosthetic heart valves testing in the mitral or aortic position. In the experiment, an aortic bileaflet mechanical valve and a mitral bioprosthesis were employed in the left ventricular model. A test fluid of 47.6% by volume of glycerin solution in water at 36.5ºC was used as blood analogue fluid. A supervisory control and data acquisition system implemented previously in LabVIEW was applied to induce the ventricular operation and to acquire the ventricular signals. The parameters of the left ventricular model operation were based on in vivo and in vitro data. The waves of ventricular and systemic pressures, aortic flow, stroke volume, among others, were acquired while manual adjustments in the arterial impedance model were also established. The acquired waves showed good results concerning some in vivo data and requirements from the ISO 5840 standard. The experimental validation was performed, allowing, in future studies, characterizing the hydrodynamic performance of prosthetic heart valves.

  18. Mechanical heart valve cavitation in patients with bileaflet valves.

    PubMed

    Johansen, Peter; Andersen, Tina S; Hasenkam, J Michael; Nygaard, Hans; Paulsen, Peter K

    2014-01-01

    Today, the quality of mechanical heart valves is quite high, and implantation has become a routine clinical procedure with a low operative mortality (< 5%). However, patients still face the risks of blood cell damage, thromboembolic events, and material failure of the prosthetic device. One mechanism found to be a possible contributor to these adverse effects is cavitation. In vitro, cavitation has been directly demonstrated by visualization and indirectly in vivo by registering of high frequency pressure fluctuations (HFPF). Tilting disc valves are thought of having higher cavitation potential than bileaflet valves due to higher closing velocities. However, the thromboembolic potential seems to be the same. Further studies are therefore needed to investigate the cavitation potential of bileaflet valves in vivo. The post processing of HFPF have shown difficulties when applied on bileaflet vavles due to asynchronous closure of the two leaflets. The aim of this study was therefore to isolate the pressure signature from each leaflet closure and perform cavitation analyses on each component. Six patients were included in the study (St. Jude Medical (n=3) and CarboMedics (n=3); all aortic bileaflet mechanical heart valves). HFPFs were recorded intraoperatively through a hydrophone at the aortic root. The pressure signature relating to the first and second leaflet closure was isolated and cavitation parameters were calculated (RMS after 50 kHz highpass filtering and signal energy). Data were averaged over 30 heart cycles. For all patients both the RMS value and signal energy of the second leaflet closure were higher than for the first leaflet closure. This indicates that the second leaflet closure is most prone to cause cavitation. Therefore, quantifying cavitation based on the HFPF related to the second leaflet closure may suggest that the cavitation potential for bileaflet valves in vivo may be higher than previous studies have suggested.

  19. Real-time 3-dimensional echocardiography for prosthetic valve endocarditis: initial experience.

    PubMed

    Kort, Smadar

    2006-02-01

    Real-time 3-dimensional echocardiography is a relatively new technology with rapidly growing potential applications. Prosthetic valve endocarditis is still a challenging diagnosis despite improvements in image qualities obtained by both transthoracic and transesophageal echocardiograms. The purpose of this article is to present 4 cases of suggested prosthetic valve endocarditis, in which real-time 3-dimensional echocardiography was performed, and to discuss the potential use of real-time 3-dimensional echocardiography for this application.

  20. Successful surgical correction of an embolized prosthetic valve poppet: case report.

    PubMed

    Ansbro, J; Clark, R; Gerbode, F

    1976-07-01

    Embolization of a prosthetic valve poppet, a rare complication following valve replacement, has been, until recently, generally fatal. Immediate recognition followed by replacement of the poppet or valve and extraction of the embolized poppet is the only feasible approach. Recently, a patient was seen was seen shortly after the onset of acute pulmonary edema with wide-open mitral regurgitation. A diagnosis of extrusion of the poppet from a previously placed prosthetic valve was confirmed and a successful mitral valve replacement accomplished. The nonradiopaque poppet, subsequently localized by an ultrasound B-sac, was removed from the lower abdominal aorta at a later operation. We believe this to be the second reported case of survival following successful reoperation for embolization of a prosthetic poppet.

  1. Physiological vortices in the sinuses of Valsalva: An in vitro approach for bio-prosthetic valves.

    PubMed

    Toninato, Riccardo; Salmon, Jacob; Susin, Francesca Maria; Ducci, Andrea; Burriesci, Gaetano

    2016-09-06

    The physiological flow dynamics within the Valsalva sinuses, in terms of global and local parameters, are still not fully understood. This study attempts to identify the physiological conditions as closely as possible, and to give an explanation of the different and sometime contradictory results in literature. An in vitro approach was implemented for testing porcine bio-prosthetic valves operating within different aortic root configurations. All tests were performed on a pulse duplicator, under physiological pressure and flow conditions. The fluid dynamics established in the various cases were analysed by means of 2D Particle Image Velocimetry, and related with the achieved hydrodynamic performance. Each configuration is associated with substantially different flow dynamics, which significantly affects the valve performance. The configuration most closely replicating healthy native anatomy was characterised by the best hemodynamic performance, and any mismatch in size and position between the valve and the root produced substantial modification of the fluid dynamics downstream of the valve, hindering the hydrodynamic performance of the system. The worst conditions were observed for a configuration characterised by the total absence of the Valsalva sinuses. This study provides an explanation for the different vortical structures described in the literature downstream of bioprosthetic valves, enlightening the experimental complications in valve testing. Most importantly, the results clearly identify the fluid mechanisms promoted by the Valsalva sinuses to enhance the ejection and closing phases, and this study exposes the importance of an optimal integration of the valve and root, to operate as a single system. Copyright © 2016 The Authors. Published by Elsevier Ltd.. All rights reserved.

  2. Effect of the prosthetic mitral valve on vortex dynamics and turbulence of the left ventricular flow

    NASA Astrophysics Data System (ADS)

    Querzoli, G.; Fortini, S.; Cenedese, A.

    2010-04-01

    Mechanical heart valves implanted in mitral position have a great effect on the ventricular flow. Changes include alteration of the dynamics of the vortical structures generated during the diastole and the onset of turbulence, possibly affecting the efficiency of the heart pump or causing blood cell damage. Modifications to the hemodynamics in the left ventricle, when the inflow through the mitral orifice is altered, were investigated in vitro using a silicone rubber, flexible ventricle model. Velocity fields were measured in space and time by means of an image analysis technique: feature tracking. Three series of experiments were performed: one with a top hat inflow velocity profile (schematically resembling physiological conditions), and two with mechanical prosthetic valves of different design, mounted in mitral position—one monoleaflet and the other bileaflet. In each series of runs, two different cardiac outputs have been examined by changing the stroke volume. The flow was investigated in terms of phase averaged velocity field and second order moments of turbulent fluctuations. Results show that the modifications in the transmitral flow change deeply the interaction between the coherent structures generated during the first phase of the diastole and the incoming jet during the second diastolic phase. Top hat inflow gives the coherent structures which are optimal, among the compared cases, for the systolic function. The flow generated by the bileaflet valve preserves most of the beneficial features of the top hat inflow, whereas the monoleaflet valve generates a strong jet which discourages the permanence of large coherent structures at the end of the diastole. Moreover, the average shear rate magnitudes induced by the smoother flow pattern of the case of top hat inflow are nearly halved in comparison with the values measured with the mechanical valves. Finally, analysis of the turbulence statistics shows that the monoleaflet valves yield higher turbulence

  3. Selection of Prosthetic Valve and Evidence—Need for the Development of Japan’s Own Guidelines

    PubMed Central

    Shiono, Motomi

    2015-01-01

    Purpose: In 2014, the American Heart Association (AHA)/American College of Cardiology (ACC) guidelines were largely revised with regard to the selection of prosthetic valves. (1) A mechanical prosthesis is reasonable for aortic valve replacement (AVR) or mitral valve replacement (MVR) in patients less than 60 years of age, (2) A bioprosthesis is reasonable in patients more than 70 years of age, and (3) Either a bioprosthetic or mechanical valve is reasonable in patients between 60 and 70 years of age. Japan faces the unprecedented population aging, and moreover, the average life expectancy is longer among the Japanese than the Westerners. In Japan, whether this choice is appropriate seems questionable. Methods: This time, with the revision of the AHA/ACC guidelines, it might be necessary to take into consideration the average life expectancy of Japanese people and revise the Japanese guidelines accordingly. Results: We should consider whether 60–70 years should be set as a gray zone regarding the age criteria for choosing biological valves, or if the age should be set higher relative to that specified in the western guidelines, given the longer Japanese life expectancy. Conclusion: We believe that the development of unique, Japanese guidelines for the selection of prosthetic valves will allow us to provide appropriate selection and treatment for each patient. PMID:26062580

  4. Recurrent Prosthetic Mitral Valve Dehiscence due to Infective Endocarditis: Discussion of Possible Causes.

    PubMed

    Ercan, Suleyman; Altunbas, Gokhan; Deniz, Hayati; Gokaslan, Gokhan; Bosnak, Vuslat; Kaplan, Mehmet; Davutoglu, Vedat

    2013-08-01

    Prosthetic valves are being widely used in the treatment of heart valve disease. Prosthetic valve endocarditis (PVE) is one of the most catastrophic complications seen in these patients. In particular, prosthetic valve dehiscence can lead to acute decompensation, pulmonary edema, and cardiogenic shock. Here, we discuss the medical management of late PVE in a patient with a prior history of late and redo early PVE and recurrent dehiscence. According to the present case, we can summarize the learning points as follows. A prior history of infective endocarditis increases the risk of relapse or recurrence, and these patients should be evaluated very cautiously to prevent late complications. Adequate debridement of infected material is of paramount importance to prevent relapse. A history of dehiscence is associated with increased risk of relapse and recurrent dehiscence.

  5. Platelet reactivity in patients with a history of obstructive prosthetic valve thrombosis.

    PubMed

    Bouganim, Tal; Shapira, Yaron; Sagie, Alexander; Vaturi, Mordehay; Battler, Alexander; Kornowski, Ran; Lev, Eli I

    2009-06-15

    One of the most serious complications of mechanical valves is obstructive prosthetic valve thrombosis (OPVT or "stuck valve"). Some patients develop OPVT despite an international normalized ratio (INR) in the therapeutic recommended range. We hypothesized that patients who develop OPVT have hyper-reactive platelets. We, therefore, examined platelet reactivity in patients who developed OPVT, despite a therapeutic or near-therapeutic INR, compared with a matched control group. We compared platelet reactivity between patients who had had an OPVT episode, despite a therapeutic or near-therapeutic INR (n = 18), and a matched group of patients with mechanical valves who did not develop this complication (n = 18) from 1996 to 2007. Platelet reactivity was evaluated by platelet aggregation in response to various agonists, platelet deposition under flow conditions in the Impact-R system, and plasma levels of platelet activation markers (soluble CD40 ligand and P-selectin). In the OPVT group, the average INR during the index episode was 3.1 +/- 1.5, and 44.6 +/- 40 months had elapsed from the index episode to the present study. Both groups were matched for gender, age +/-10 years, valve position and type, active smoking, and diabetes. Patients with an OPVT history had a greater aggregation in response to collagen (p = 0.05), greater platelet deposition in the Impact-R system (p = 0.01), and tended to have higher levels of soluble P-selection and soluble CD40 ligand (p = 0.07) than their control counterparts. In conclusion, patients with a history of OPVT appear to have increased platelet reactivity, which might contribute to an increased risk of thrombotic complications. These patients would, therefore, likely benefit from the addition of antiplatelet therapy to their standard anticoagulant treatment.

  6. Real-time in vitro observation of cavitation in a prosthetic heart valve.

    PubMed

    Lamson, T C; Stinebring, D R; Deutsch, S; Rosenberg, G; Tarbell, J M

    1991-01-01

    A technique for real-time in vitro observation of cavitation on a prosthetic heart valve operating in a ventricular assist device under normal physiologic conditions has been developed. Considering the documented observation of cavitation erosion in heart valve components from human explants, and the potential risk of blood damage that cavitation presents, the technique developed in this study may prove useful in the design of prosthetic heart valves and ventricular assist devices. Cavitation of a glycerol blood analog fluid has been documented for a Medtronic/Hall prosthetic heart valve operating in a Penn State Electric Ventricular Assist Device. The ventricular assist device was operated in a mock circulatory system under normal physiologic conditions. The valve was located in the mitral position, with the cavitation occurring on the inlet side after valve closure. Bubble cavitation was seen on the valve occluder face, and vortex cavitation was observed at two locations in the vicinity of the valve occluder and housing. The cavity growth and collapse cycle for these forms of vaporous cavitation was less than 1 msec. Stroboscopic photography and stroboscopic videography with frame grabbing were used to document the cavity life cycle. With beat rate held constant, the cavity duration time was found to decrease with increasing mean venous return pressure.

  7. Compact valve actuation mechanism

    NASA Technical Reports Server (NTRS)

    Brogdon, James William (Inventor); Gill, David Keith (Inventor)

    2000-01-01

    A valve actuation device. The device may include a free floating valve bridge movably supported within a cavity in the engine housing. The bridge may be provided with a cavity and an orifice arrangement for pumping gases entrained with lubricating fluid toward the piston stems as the bridge reciprocates back and forth. The device may also include a rocker arm that has a U-shaped cross-sectional shape for receiving at least a portion of the valve bridge, valve stem valve spring and spring retainer therein. The rocker arm may be provided with lubrication passages for directing lubrication to the point wherein it is pivotally affixed to the engine housing.

  8. Transcatheter Pulmonary Valve Replacement by Hybrid Approach Using a Novel Polymeric Prosthetic Heart Valve: Proof of Concept in Sheep

    PubMed Central

    Xu, Tong-yi; Zhang, Zhi-gang; Li, Xin; Han, Lin; Xu, Zhi-yun

    2014-01-01

    Background Since 2000, transcatheter pulmonary valve replacement has steadily advanced. However, the available prosthetic valves are restricted to bioprosthesis which have defects like poor durability. Polymeric heart valve is thought as a promising alternative to bioprosthesis. In this study, we introduced a novel polymeric transcatheter pulmonary valve and evaluated its feasibility and safety in sheep by a hybrid approach. Methods We designed a novel polymeric trileaflet transcatheter pulmonary valve with a balloon-expandable stent, and the valve leaflets were made of 0.1-mm expanded polytetrafluoroethylene (ePTFE) coated with phosphorylcholine. We chose glutaraldehyde-treated bovine pericardium valves as control. Pulmonary valve stents were implanted in situ by a hybrid transapical approach in 10 healthy sheep (8 for polymeric valve and 2 for bovine pericardium valve), weighing an average of 22.5±2.0 kg. Angiography and cardiac catheter examination were performed after implantation to assess immediate valvular functionality. After 4-week follow-up, angiography, echocardiography, computed tomography, and cardiac catheter examination were used to assess early valvular function. One randomly selected sheep with polymeric valve was euthanized and the explanted valved stent was analyzed macroscopically and microscopically. Findings Implantation was successful in 9 sheep. Angiography at implantation showed all 9 prosthetic valves demonstrated orthotopic position and normal functionality. All 9 sheep survived at 4-week follow-up. Four-week follow-up revealed no evidence of valve stent dislocation or deformation and normal valvular and cardiac functionality. The cardiac catheter examination showed the peak-peak transvalvular pressure gradient of the polymeric valves was 11.9±5.0 mmHg, while that of two bovine pericardium valves were 11 and 17 mmHg. Gross morphology demonstrated good opening and closure characteristics. No thrombus or calcification was seen

  9. Dual prosthetic heart valve presented with chest pain: a case report of coronary thromboembolism.

    PubMed

    Wongrakpanich, Supakanya; Thamcharoen, Natanong; Chongsathidkiet, Pakawat; Siwamogsatham, Sarawut

    2015-01-01

    Coronary embolism from a prosthetic heart valve is a rare but remarkable cause of acute coronary syndrome. There is no definite management of an entity like this. Here we report a case of 54-year-old male with a history of rheumatic heart disease with dual prosthetic heart valve and atrial fibrillation who developed chest pain from acute myocardial infarction. The laboratory values showed inadequate anticoagulation. Cardiac catheterization and thrombectomy with the aspiration catheter were chosen to be the treatment for this patient, and it showed satisfactory outcome.

  10. Dual Prosthetic Heart Valve Presented with Chest Pain: A Case Report of Coronary Thromboembolism

    PubMed Central

    Siwamogsatham, Sarawut

    2015-01-01

    Coronary embolism from a prosthetic heart valve is a rare but remarkable cause of acute coronary syndrome. There is no definite management of an entity like this. Here we report a case of 54-year-old male with a history of rheumatic heart disease with dual prosthetic heart valve and atrial fibrillation who developed chest pain from acute myocardial infarction. The laboratory values showed inadequate anticoagulation. Cardiac catheterization and thrombectomy with the aspiration catheter were chosen to be the treatment for this patient, and it showed satisfactory outcome. PMID:25785203

  11. Longest Event-Free Survival without Anticoagulation in a Mechanical Aortic Valve Replacement

    PubMed Central

    Salmane, Chadi; Pandya, Bhavi; Lafferty, Kristen; Patel, Nileshkumar J; McCord, Donald

    2016-01-01

    Sixty percent of the patients going for valve replacement opt for mechanical valves and the remaining 40% choose bioprosthetics. Mechanical valves are known to have a higher risk of thrombosis; this risk further varies depending on the type of valve, its position, and certain individual factors. According to current guidelines, long-term anticoagulation is indicated in patients with metallic prosthetic valve disease. We report two unique cases of patients who survived 27 and 37 years event free, respectively, after mechanical aortic valve replacement (AVR) without being on any form of anticoagulation. The latter case described the longest survival in a human with a prosthetic aortic valve without anticoagulation. A review of literature demonstrated few cases of prosthetic valves with no anticoagulation in the long term without significant embolic events reported as case reports. These cases have been summarized in this article. Some cases of long-term survival (in the absence of anticoagulation) were attributed to good luck, and others as the result of genetic variations. New mechanical prosthetic valves can be promising, such as microporus-surfaced valves that may be used without full anticoagulation. The use of dual antiplatelet agents alone can be currently recommended only when a patient cannot take oral anticoagulation after AVR, and it should be followed with measuring and monitoring of platelet reactivity. PMID:27053922

  12. A pulsatile flow model for in vitro quantitative evaluation of prosthetic valve regurgitation.

    PubMed

    Giuliatti, S; Gallo, L; Almeida-Filho, O C; Schmidt, A; Marin-Neto, J A; Pelá, C A; Maciel, B C

    2000-03-01

    A pulsatile pressure-flow model was developed for in vitro quantitative color Doppler flow mapping studies of valvular regurgitation. The flow through the system was generated by a piston which was driven by stepper motors controlled by a computer. The piston was connected to acrylic chambers designed to simulate "ventricular" and "atrial" heart chambers. Inside the "ventricular" chamber, a prosthetic heart valve was placed at the inflow connection with the "atrial" chamber while another prosthetic valve was positioned at the outflow connection with flexible tubes, elastic balloons and a reservoir arranged to mimic the peripheral circulation. The flow model was filled with a 0.25% corn starch/water suspension to improve Doppler imaging. A continuous flow pump transferred the liquid from the peripheral reservoir to another one connected to the "atrial" chamber. The dimensions of the flow model were designed to permit adequate imaging by Doppler echocardiography. Acoustic windows allowed placement of transducers distal and perpendicular to the valves, so that the ultrasound beam could be positioned parallel to the valvular flow. Strain-gauge and electromagnetic transducers were used for measurements of pressure and flow in different segments of the system. The flow model was also designed to fit different sizes and types of prosthetic valves. This pulsatile flow model was able to generate pressure and flow in the physiological human range, with independent adjustment of pulse duration and rate as well as of stroke volume. This model mimics flow profiles observed in patients with regurgitant prosthetic valves.

  13. Modeling prosthetic heart valves for numerical analysis of blood flow in the heart

    SciTech Connect

    Peskin, C.S.; McQueen, D.M.

    1980-08-01

    This paper extends our previous work on numerical analysis of blood flow in the heart. In that work the boundary forces were evaluated by solving a fixed-point problem, which we now reformulate as a problem in optimization. This optimization problem, which involves the energy function from which the boundary forces are derived, is solved by Murray's modification of Newton's method. The energy function turns out to be an extremely useful tool in modeling prosthetic heart valves. To enforce a constraint on the valve, we use an energy function which is zero when the constraint is satisfied and positive other wise. The energy function must be invariant under translation and rotation so that convervation of momentum and angular momentum will be satisfied. We use this technique to construct computer models of several prosthetic valves, and we study the flow patterns of these valves in our computer test chamber.

  14. Systemic thrombolysis: cure for prosthetic mitral valve thrombosis in the comorbid, non-surgical candidate.

    PubMed

    Beckord, Brian; Berkowitz, Robert; Espinoza, Cholene; Anand, Neil

    2014-05-30

    Severe haemolytic anaemia is a rare complication of prosthetic valve thrombosis (PVT). Emergent surgical replacement of the affected valve is normally the treatment of choice unless contraindicated, such as in high surgical risk patients. Systemic thrombolysis is the alternative to surgical valve replacement. The purpose of this report is to highlight the unique case of an elderly man with New York Heart Association class IV heart failure, history of extensive cardiopulmonary surgeries and haemorrhagic stroke, who presented with severe haemolytic anaemia secondary to prosthetic mitral valve thrombosis. After weighing the risks and benefits, our decision was to use systemic thrombolytic therapy, even in light of the patient's previous intracranial haemorrhage. Pretreatment and post-treatment Doppler echocardiography showed markedly reduced regurgitant jetting that ultimately resolved completely, thereby eliminating the underlying cause of haemolysis and achieving symptom resolution. 2014 BMJ Publishing Group Ltd.

  15. Perivalvular pannus and valve thrombosis: two concurrent mechanisms of mechanical valve prosthesis dysfunction.

    PubMed

    Arnáiz-García, María Elena; González-Santos, Jose María; Bueno-Codoñer, María E; López-Rodríguez, Javier; Dalmau-Sorlí, María José; Arévalo-Abascal, Adolfo; Arribas-Jiménez, Antonio; Diego-Nieto, Alejandro; Rodríguez-Collado, Javier; Rodríguez-López, Jose María

    2015-02-01

    A 78-year-old woman was admitted to our institution with progressive dyspnea. She had previously been diagnosed with rheumatic heart disease and had undergone cardiac surgery for mechanical mitral valve replacement ten years previously. Transesophageal echocardiography revealed blockage of the mechanical prosthesis and the patient was scheduled for surgery, in which a thrombus was removed from the left atrial appendage. A partial thrombosis of the mechanical prosthesis and circumferential pannus overgrowth were concomitantly detected. Prosthetic heart valve blockage is a rare but life-threatening complication, the main causes of which are thrombosis and pannus formation. The two conditions are different but both are usually misdiagnosed. Two concurrent mechanisms of prosthesis blockage were found in this patient. Copyright © 2014 Sociedade Portuguesa de Cardiologia. Published by Elsevier España. All rights reserved.

  16. An improved method for determining the flow characteristics of prosthetic mitral heart valves

    PubMed Central

    Wright, J. T. M.; Temple, L. J.

    1971-01-01

    The flow characteristics of most prosthetic mitral valves recommended for clinical use have not been adequately investigated. As a result vital information about their performance is lacking and, until this is published, comparisons between different prostheses cannot easily be made. In this paper the design and construction of a suitable rig for the testing of such valves is described. The results obtained will be presented in a subsequent paper. Images PMID:5543821

  17. A Novel Technique for Prosthetic Valve Retrieval After Transcatheter Aortic Valve Embolization.

    PubMed

    Giannini, Francesco; Ruparelia, Neil; Del Furia, Francesca; Romano, Vittorio; Ancona, Marco; Mangieri, Antonio; Regazzoli, Damiano; Latib, Azeem; Godino, Cosmo; Ancona, Francesco; Candilio, Luciano; Jabbour, Richard; Colombo, Antonio; Montorfano, Matteo

    2017-07-01

    Although the rate of procedural complications during transcatheter aortic valve implantation has decreased because of technological advancement and increased operator experience, device embolization remains a rare but potentially fatal complication, even with new generation devices. We report, to our knowledge, the first case of Portico valve (St Jude Medical, Minneapolis, MN) migration despite apparent optimal initial implantation depth, which was retrieved using a novel strategy after failure of a traditional retrieval technique. We also describe a mechanism of left coronary artery systolic perfusion with diastolic backflow, which led to myocardial ischemia. Copyright © 2017 Canadian Cardiovascular Society. Published by Elsevier Inc. All rights reserved.

  18. Mechanical behavior of provisional implant prosthetic abutments

    PubMed Central

    Serra-Pastor, Blanca; Roig-Vanaclocha, Ana; Román-Rodriguez, Juan-Luis; Fons-Font, Antonio

    2015-01-01

    Introduction: Implant-supported prostheses have to overcome a major difficulty presented by the morphology and esthetics of peri-implant tissues in the anterior sector. Diverse therapeutic techniques are used for managing the mucosa adjacent to the implant and the most noteworthy is immediate/deferred fixed provisionalization. Objectives: In vitro testing of strength and deformation of implant prosthetic abutments made from different materials (Titanium/PEEK/methacrylate). Material and Methods: Forty Sweden&Martina® implant prosthetic abutments (n=40) were divided into five groups: Group MP: methacrylate provisional abutments with machined titanium base; Group PP: Poly ether ether ketone (PEEK) provisional abutments; Group TP: titanium provisional abutments; Group TAD: titanium anti-rotational definitive abutments; Group TRD: titanium rotational definitive abutments. Their mechanical behavior under static loading was analyzed. Samples were examined under a microscope to determine the type of fracture produced. Results and Conclusions: Definitive anti-rotational titanium abutments and definitive rotational titanium abutments achieved the best mean compression strength, while PEEK resin provisional abutments obtained the lowest. The group that showed the greatest elastic deformation was the group of titanium provisional abutments. Key words:Immediate loading, immediate provisionalization, implant prosthetic abutment, definitive implant prosthetic abutment. PMID:25129253

  19. Persistent immune thrombocytopenia heralds the diagnosis of Mycobacterium chimaera prosthetic valve endocarditis.

    PubMed

    Sacco, Keith A; Burton, M Caroline

    2017-01-01

    A 63 year old female was admitted for investigation of worsening renal insufficiency. During hospitalization she developed persistent immune thrombocytopenia refractory to supportive or immunosuppressive treatment. She was diagnosed with Mycobacterium chimaera prosthetic valve endocarditis and thrombocytopenia resolved with anti-mycobacterial therapy.

  20. A SECOND CASE OF LATE EMBOLIZATION OF PROSTHETIC MITRAL VALVE OCCLUDER WITH SURVIVAL FOLLOWING REOPERATION

    PubMed Central

    Sabbagh, Adib H.; O'Hare, James E.; Schocket, Lee I.; Pinckley, James N.

    1975-01-01

    A 51-year-old male with acute fulminating pulmonary edema and cardiogenic shock secondary to severe mitral insufficiency from dislodgment of the disc occluder in a Wada-Cutter valve was treated by immediate open heart procedure with a Bjork-Shiley mitral valve replacement. The patient survived and remains well. This is the second patient reported to survive operation and replacement of a malfunctioning prosthetic mitral valve from which the poppet escaped and embolized. The first case was reported by Hughes et al1 in February, 1975. Some striking similarities, as well as differences, in these two cases are discussed. Images PMID:15215920

  1. A SECOND CASE OF LATE EMBOLIZATION OF PROSTHETIC MITRAL VALVE OCCLUDER WITH SURVIVAL FOLLOWING REOPERATION.

    PubMed

    Sabbagh, Adib H.; O'Hare, James E.; Schocket, Lee I.; Pinckley, James N.

    1975-01-01

    A 51-year-old male with acute fulminating pulmonary edema and cardiogenic shock secondary to severe mitral insufficiency from dislodgment of the disc occluder in a Wada-Cutter valve was treated by immediate open heart procedure with a Bjork-Shiley mitral valve replacement. The patient survived and remains well. This is the second patient reported to survive operation and replacement of a malfunctioning prosthetic mitral valve from which the poppet escaped and embolized. The first case was reported by Hughes et al(1) in February, 1975. Some striking similarities, as well as differences, in these two cases are discussed.

  2. Are homografts superior to conventional prosthetic valves in the setting of infective endocarditis involving the aortic valve?

    PubMed

    Kim, Joon Bum; Ejiofor, Julius I; Yammine, Maroun; Camuso, Janice M; Walsh, Conor W; Ando, Masahiko; Melnitchouk, Serguei I; Rawn, James D; Leacche, Marzia; MacGillivray, Thomas E; Cohn, Lawrence H; Byrne, John G; Sundt, Thoralf M

    2016-05-01

    Surgical dogma suggests that homografts should be used preferentially, compared with conventional xenograft or mechanical prostheses, in the setting of infective endocarditis (IE), because they have greater resistance to infection. However, comparative data that support this notion are limited. From the prospective databases of 2 tertiary academic centers, we identified 304 consecutive adult patients (age ≥17 years) who underwent surgery for active IE involving the aortic valve (AV), in the period 2002 to 2014. Short- and long-term outcomes were evaluated using propensity scores and inverse-probability weighting to adjust for selection bias. Homografts, and xenograft and mechanical prostheses, were used in 86 (28.3%), 139 (45.7%), and 79 (26.0%) patients, respectively. Homografts were more often used in the setting of prosthetic valve endocarditis (58.1% vs 28.8%, P = .002) and methicillin-resistant Staphylococcus (25.6% vs 12.1%, P = .002), compared with conventional prostheses. Early mortality occurred in 17 (19.8%) in the homograft group, and 20 (9.2%) in the conventional group (P = .019). During follow-up (median: 29.4 months; interquartile-range: 4.7-72.6 months), 60 (19.7%) patients died, and 23 (7.7%) experienced reinfection, with no significant differences in survival (P = .23) or freedom from reinfection rates (P = .65) according to the types of prostheses implanted. After adjustments for baseline characteristics, using propensity-score analyses, use of a homograft did not significantly affect early death (odds ratio 1.61; 95% confidence interval [CI], 0.73-3.40, P = .23), overall death (hazard ratio 1.10; 95% CI, 0.62-1.94, P = .75), or reinfection (hazard ratio 1.04; 95% CI, 0.49-2.18, P = .93). No significant benefit to use of homografts was demonstrable with regard to resistance to reinfection in the setting of IE. The choice among prosthetic options should be based on technical and patient-specific factors. Lack of availability of homografts should

  3. Prosthetic valves in adult patients with congenital heart disease: Rationale and design of the Dutch PROSTAVA study.

    PubMed

    Freling, H G; van Slooten, Y J; van Melle, J P; Mulder, B J M; van Dijk, A P J; Hillege, H L; Post, M C; Sieswerda, G Tj; Jongbloed, M R M; Willems, T P; Pieper, P G

    2012-10-01

    Data on long-term complications in adult patients with congenital heart disease (ACHD) and a prosthetic valve are scarce. Moreover, the influence of prosthetic valves on quality of life (QoL) and functional outcome in ACHD patients with prosthetic valves has not been studied. The primary objective of the PROSTAVA study is to investigate the relation between prosthetic valve characteristics (type, size and location) and functional outcome as well as QoL in ACHD patients. The secondary objectives are to investigate the prevalence and predictors of prosthesis-related complications including prosthesis-patient mismatch. The PROSTAVA study, a multicentre cross-sectional observational study, will include approximately 550 ACHD patients with prosthetic valves. Primary outcome measures are maximum oxygen uptake during cardiopulmonary exercise testing and QoL. Secondary outcomes are the prevalence and incidence of valve-related complications including prosthesis-patient mismatch. Other evaluations are medical history, physical examination, echocardiography, MRI, rhythm monitoring and laboratory evaluation (including NT-proBNP). Identification of the relation between prosthetic valve characteristics in ACHD patients on one hand and functional outcome, QoL, the prevalence and predictors of prosthesis-related complications on the other hand may influence the choice of valve prosthesis, the indication for more extensive surgery and the indication for re-operation.

  4. Analysis of the acoustic spectral signature of prosthetic heart valves in patients experiencing atrial fibrillation

    SciTech Connect

    Scott, D.D.; Jones, H.E.

    1994-05-06

    Prosthetic heart valves have increased the life span of many patients with life threatening heart conditions. These valves have proven extremely reliable adding years to what would have been weeks to a patient`s life. Prosthetic valves, like the heart however, can suffer from this constant work load. A small number of valves have experienced structural fractures of the outlet strut due to fatigue. To study this problem a non-intrusive method to classify valves has been developed. By extracting from an acoustic signal the opening sounds which directly contain information from the outlet strut and then developing features which are supplied to an adaptive classification scheme (neural network) the condition of the valve can be determined. The opening sound extraction process has proved to be a classification problem itself. Due to the uniqueness of each heart and the occasional irregularity of the acoustic pattern it is often questionable as to the integrity of a given signal (beat), especially one occurring during an irregular beat pattern. A common cause of these irregular patterns is a condition known as atrial fibrillation, a prevalent arrhythmia among patients with prosthetic hear valves. Atrial fibrillation is suspected when the ECG shows no obvious P-waves. The atria do not contract and relax correctly to help contribute to ventricular filling during a normal cardiac cycle. Sometimes this leads to irregular patterns in the acoustic data. This study compares normal beat patterns to irregular patterns of the same heart. By analyzing the spectral content of the beats it can be determined whether or not these irregular patterns can contribute to the classification of a heart valve or if they should be avoided. The results have shown that the opening sounds which occur during irregular beat patterns contain the same spectral information as the opening which occur during a normal beat pattern of the same heart and these beats can be used for classification.

  5. The prognosis of infective endocarditis treated with biological valves versus mechanical valves: A meta-analysis.

    PubMed

    Tao, Ende; Wan, Li; Wang, WenJun; Luo, YunLong; Zeng, JinFu; Wu, Xia

    2017-01-01

    Surgery remains the primary form of treatment for infective endocarditis (IE). However, it is not clear what type of prosthetic valve provides a better prognosis. We conducted a meta-analysis to compare the prognosis of infective endocarditis treated with biological valves to cases treated with mechanical valves. Pubmed, Embase and Cochrane databases were searched from January 1960 to November 2016.Randomized controlled trials, retrospective cohorts and prospective studies comparing outcomes between biological valve and mechanical valve management for infective endocarditis were analyzed. The Newcastle-Ottawa Scale(NOS) was used to evaluate the quality of the literature and extracted data, and Stata 12.0 software was used for the meta-analysis. A total of 11 publications were included; 10,754 cases were selected, involving 6776 cases of biological valves and 3,978 cases of mechanical valves. The all-cause mortality risk of the biological valve group was higher than that of the mechanical valve group (HR = 1.22, 95% CI 1.03 to 1.44, P = 0.023), as was early mortality (RR = 1.21, 95% CI 1.02 to 1.43, P = 0.033). The recurrence of endocarditis (HR = 1.75, 95% CI 1.26 to 2.42, P = 0.001), as well as the risk of reoperation (HR = 1.79, 95% CI 1.15 to 2.80, P = 0.010) were more likely to occur in the biological valve group. The incidence of postoperative embolism was less in the biological valve group than in the mechanical valve group, but this difference was not statistically significant (RR = 0.90, 95% CI 0.76 to 1.07, P = 0.245). For patients with prosthetic valve endocarditis (PVE), there was no significant difference in survival rates between the biological valve group and the mechanical valve group (HR = 0.91, 95% CI 0.68 to 1.21, P = 0.520). The results of our meta-analysis suggest that mechanical valves can provide a significantly better prognosis in patients with infective endocarditis. There were significant differences in the clinical features of patients

  6. Cardiac crossroads: deciding between mechanical or bioprosthetic heart valve replacement

    PubMed Central

    Tillquist, Maggie N; Maddox, Thomas M

    2011-01-01

    Nearly 15 million people in the United States suffer from either aortic or mitral valvular disease. For patients with severe and symptomatic valvular heart disease, valve replacement surgery improves morbidity and mortality outcomes. In 2009, 90,000 valve replacement surgeries were performed in the United States. This review evaluates the advantages and disadvantages of mechanical and bioprosthetic prosthetic heart valves as well as the factors for consideration in deciding the appropriate valve type for an individual patient. Although many caveats exist, the general recommendation is for patients younger than 60 to 65 years to receive mechanical valves due to the valve’s longer durability and for patients older than 60 to 65 years to receive a bioprosthetic valve to avoid complications with anticoagulants. Situations that warrant special consideration include patient co-morbidities, the need for anticoagulation, and the potential for pregnancy. Once these characteristics have been considered, patients’ values, anxieties, and expectations for their lifestyle and quality of life should be incorporated into final valve selection. Decision aids can be useful in integrating preferences in the valve decision. Finally, future directions in valve technology, anticoagulation, and medical decision-making are discussed. PMID:21448466

  7. Design conception and experimental setup for in vitro evaluation of mitral prosthetic valves.

    PubMed

    Bazan, Ovandir; Ortiz, Jayme Pinto

    2011-01-01

    Since most complications related to the operation of prosthetic heart valves is due to disturbances of flow, its hydrodynamic characterization is a useful aid in the design of new prostheses. Simulations of pulsatile flow in cardiac prostheses began nearly 40 years ago, through the development of different mock human circulatory systems, improving the clinical results interpretation. A new design of a pulse duplicator system was developed at Polytechnic School of USP to study prosthetic heart valves. To present the conception of a new mock circulatory system for hydrodynamic simulations of cardiac prosthetic valves and the assembly plan of an experiment whose focus is the test of mitral prosthesis. Its conception is based on the state-of-art's review of these studies and the experience got with the previous mock circulatory systems, particularly the one used in the Instituto Dante Pazzanese de Cardiologia, São Paulo, SP, Brazil. In this design, an electric servomotor controlled by computer emits, through a hydraulic piston, a pulse to the left ventricular chamber model, where the heart valves are accomodated. To characterize, in the future, the dynamic operation of mitral prosthetic valves, an experimental setup was mounted to provide measurements of volumetric flow, instantaneous pressure and velocity fields on these valves. Optical access is conveniently provided on the design, making possible the use, in the future, of a LDA system. In order to improve the analysis of hydrodynamic shear stress and prediction of haemolysis, the experimental results may be used to regulate a numerical model using 'Computational Fluid Dynamics' (CFD).

  8. Total prosthetic replacement of atrioventricular valves in the dog

    PubMed Central

    Den Otter, G.

    1968-01-01

    The free-floating cone and cage valve, described in a previous study as being successful as a substitute for the right atrioventricular valve, does not perform well when it is inserted in the mitral ostium. A tilting cone or disc was constructed and tested in a series of 15 dogs. This prosthesis gave excellent results in 12 animals. The reasons for its failure in the remaining three is discussed. The prosthesis presented has advantages over any ball and cage valve, mainly because of its smaller volume. Images PMID:5654076

  9. Early-onset Streptomyces endocarditis in a prosthetic aortic valve.

    PubMed

    Shehatha, Jaffar S; Taha, Abdulsalam Y

    2017-02-01

    A 66-year-old Australian man underwent elective replacement of a severely stenotic aortic valve with a 22-mm Medtronic-Hall valve. Six weeks later, he was readmitted with worsening dyspnea, fever, and mild anemia. Investigations confirmed pulmonary edema and moderate periprosthetic aortic regurgitation. The pulmonary edema was managed conservatively, and a second 22-mm Medtronic-Hall valve was implanted. Infective endocarditis was suspected in the aortic annulus below the orifice of the right coronary artery. A bacteriological study revealed a rare bacteria of Streptomyces species. The patient received intensive antibiotic therapy over a 6-week period of hospitalization, and the aortic regurgitation disappeared one week postoperatively.

  10. A method for real-time in vitro observation of cavitation on prosthetic heart valves.

    PubMed

    Zapanta, C M; Liszka, E G; Lamson, T C; Stinebring, D R; Deutsch, S; Geselowitz, D B; Tarbell, J M

    1994-11-01

    A method for real-time in vitro observation of cavitation on a prosthetic heart valve has been developed. Cavitation of four blood analog fluids (distilled water, aqueous glycerin, aqueous polyacrylamide, and aqueous xanthan gum) has been documented for a Medtronic/Hall prosthetic heart valve. This method employed a Penn State Electrical Ventricular Assist Device in a mock circulatory loop that was operated in a partial filling mode associated with reduced atrial filling pressure. The observations were made on a valve that was located in the mitral position, with the cavitation occurring on the inlet side after valve closure on every cycle. Stroboscopic videography was used to document the cavity life cycle. Bubble cavitation was observed on the valve occluder face. Vortex cavitation was observed at two locations in the vicinity of the valve occluder and housing. For each fluid, cavity growth and collapse occurred in less than one millisecond, which provides strong evidence that the cavitation is vaporous rather than gaseous. The cavity duration time was found to decrease with increasing atrial pressure at constant aortic pressure and beat rate. The area of cavitation was found to decrease with increasing delay time at a constant aortic pressure, atrial pressure, and beat rate. Cavitation was found to occur in each of the fluids, with the most cavitation seen in the Newtonian fluids (distilled water and aqueous glycerin).

  11. New electromagnetic methods for the evaluation of prosthetic heart valves (invited)

    NASA Astrophysics Data System (ADS)

    Udpa, Satish

    2002-05-01

    Prosthetic devices are being implanted at record levels as the nation "ages" and advances in prosthetic science are made. Devices that are implanted range from artificial limbs and hips to devices such as heart valves. Periodic evaluation of the state of the devices is of significant interest particularly in the case of prosthetics whose failure can be fatal. An example of such a device is the artificial heart valve. Heart valves are usually replaced when stenosis or incompetence is indicated. This article presents a selection of some new techniques that are being developed for the detection of outlet strut failures in Bjork-Shiley heart valves. Methods that show particular promise include a noninvasive electromagnetic method that relies on the excitation and measurement of the resonant vibration modes of the strut. An alternate approach involves the induction of currents in the outlet strut using a pair of external excitation coils. The field generated by the current induced in the strut perturbs the field generated by the excitation coils. The field perturbations are measured using a catheter-mounted gradiometer. Test results obtained using an experimental rig designed to demonstrate the proof-of-concept are presented.

  12. The clinical significance of perivalvular pannus in prosthetic mitral valves: Can cardiac CT be helpful?

    PubMed

    Chang, Suyon; Suh, Young Joo; Han, Kyunghwa; Kim, Jin Young; Kim, Young Jin; Chang, Byung-Chul; Choi, Byoung Wook

    2017-09-21

    The clinical significance of pannus in the prosthetic mitral valve (MV) is not well documented. To investigate the clinical significance of pannus on cardiac computed tomography (CT) in patients with a prosthetic MV. A total of 130 patients with previous MV replacement who underwent cardiac CT were retrospectively included in this study. The presence of pannus, paravalvular leak (PVL) around the prosthetic MV and limitation of motion (LOM) of the MV were analyzed using CT. Between patients with MV pannus and those without pannus, CT, echocardiographic, and redo-surgery findings were compared. The diagnostic performance of CT and transesophageal echocardiography (TEE) for the detection of MV pannus was also compared, using surgical findings as a standard reference. MV pannus was observed on cardiac CT in 32.3% of the study population. Patients with MV pannus detected on CT more commonly had LOM (28.2% vs. 15.2%) and less frequently had PVL of the prosthetic MV (16.7% vs. 25%) than patients without MV pannus (P>0.05). Prosthetic valve obstruction (PVO) due prosthetic MV pannus requiring redo-surgery was present in only five patients (11.9%). Cardiac CT detected MV pannus with sensitivity of 65.2% and specificity of 80.9% and showed better diagnostic performance than TEE (P<0.05). Prosthetic MV pannus can frequently be seen on cardiac CT. However, its clinical significance should be assessed with careful consideration, because PVO due to MV pannus is relatively uncommon, and pannus can be seen in patients without any clinical problems. Copyright © 2017 Elsevier Ireland Ltd. All rights reserved.

  13. In vitro assessment of flow patterns and turbulence intensity in prosthetic heart valves using generalized phase-contrast MRI.

    PubMed

    Kvitting, John-Peder Escobar; Dyverfeldt, Petter; Sigfridsson, Andreas; Franzén, Stefan; Wigström, Lars; Bolger, Ann F; Ebbers, Tino

    2010-05-01

    To assess in vitro the three-dimensional mean velocity field and the extent and degree of turbulence intensity (TI) in different prosthetic heart valves using a generalization of phase-contrast MRI (PC-MRI). Four 27-mm aortic valves (Björk-Shiley Monostrut tilting-disc, St. Jude Medical Standard bileaflet, Medtronic Mosaic stented and Freestyle stentless porcine valve) were tested under steady inflow conditions in a Plexiglas phantom. Three-dimensional PC-MRI data were acquired to measure the mean velocity field and the turbulent kinetic energy (TKE), a direction-independent measure of TI. Velocity and TI estimates could be obtained up- and downstream of the valves, except where metallic structure in the valves caused signal void. Distinct differences in the location, extent, and peak values of velocity and TI were observed between the valves tested. The maximum values of TKE varied between the different valves: tilting disc, 100 J/m(3); bileaflet, 115 J/m(3); stented, 200 J/m(3); stentless, 145 J/m(3). The TI downstream from a prosthetic heart valve is dependent on the specific valve design. Generalized PC-MRI can be used to quantify velocity and TI downstream from prosthetic heart valves, which may allow assessment of these aspects of prosthetic valvular function in postoperative patients. Copyright 2010 Wiley-Liss, Inc.

  14. Successful treatment of Listeria monocytogenes prosthetic valve endocarditis using rifampicin and benzylpenicillin in combination with valve replacement

    PubMed Central

    Chik, William; Chen, Sharon; Kok, Jen

    2017-01-01

    Introduction. Listeria monocytogenes is an uncommon cause of prosthetic valve endocarditis (PVE). Recommended antimicrobial therapy typically includes intravenous β-lactams with or without synergistic aminoglycosides. In vitro studies have previously identified antagonism when rifampicin has been used in combination with β-lactams. However, in vivo data of rifampicin use are limited despite its enhanced anti-biofilm activity. Case presentation. A 63-year-old male presented with fever and back pain. L. monocytogenes bacteraemia and bioprosthetic aortic valve endocarditis was confirmed, along with spinal discitis and osteomyelitis. He was successfully treated with benzylpenicillin and rifampicin, in conjunction with valve replacement. Conclusion. Rifampicin remains an alternate agent to use, when there are contraindications to traditional aminoglycoside therapy. Further data on rifampicin use in L. monocytogenes PVE are awaited. PMID:28348807

  15. Potential inherited causes of recurrent prosthetic mitral valve thrombosis in a pregnant patient suffering from recurrent miscarriage.

    PubMed

    Kalcik, Macit; Gursoy, M Ozan; Karakoyun, Suleyman; Yesin, Mahmut; Astarcioglu, Mehmet Ali; Ozkan, Mehmet

    2014-07-01

    An effective anticoagulation is critical in pregnant patients with prosthetic heart valves. Inherited disorders may interfere with the coagulation cascade and may be associated with obstetrical complications as well as with prosthetic valve-derived complications. The patient in the present case had a history of recurrent prosthetic heart valve thrombosis (PHVT) despite an effective anticoagulation. She underwent a thrombolysis with low-dose prolonged infusion of tissue-type plasminogen activator for the management of her recurrrent prosthetic valve thrombosis. The genetic testing showed homozygous mutations of methylenetetrahydrofolate reductase (MTHFR) A 1298 C and heterozygous mutations of β-fibrinogen 455 G-A. Inherited disorders such as MTHFR A 1298 C and fibrinogen 455G/A polymorphisms may be involved in the pathogenesis of recurrent PHVT and/or pregnancy loss.

  16. 18F-FDG PET/CT in the diagnosis of prosthetic valve endocarditis.

    PubMed

    Fagman, Erika; van Essen, Martijn; Fredén Lindqvist, Johan; Snygg-Martin, Ulrika; Bech-Hanssen, Odd; Svensson, Gunnar

    2016-04-01

    Recent studies have shown promising results using (18)F-fluorodeoxyglucose positron emission tomography/computed tomography ((18)F-FDG PET/CT) in the diagnosis of prosthetic valve endocarditis (PVE). However, previous studies did not include negative controls. The aim of this study was to compare (18)F-FDG-uptake around prosthetic aortic valves in patients with and without PVE and to determine the diagnostic performance of (18)F-FDG PET/CT in the diagnosis of PVE. (18)F-FDG PET/CT examinations in patients with a prosthetic aortic valve performed 2008-2014 were retrieved. Eight patients with a final diagnosis of definite PVE were included in the analysis of the diagnostic performance of (18)F-FDG PET/CT. Examinations performed on suspicion of malignancy in patients without PVE (n = 19) were used as negative controls. Visual and semi-quantitative analysis was performed. Maximal standardized uptake value (SUVmax) in the valve area was measured and SUVratio was calculated by dividing valve SUVmax by SUVmax in the descending aorta. The sensitivity was 75 %, specificity 84 %, positive likelihood ratio [LR(+)] 4.8 and negative likelihood ratio [LR(-)] 0.3 on visual analysis. Both SUVmax and SUVratio were significantly higher in PVE patients [5.8 (IQR 3.5-6.5) and 2.4 (IQR 1.7-3.0)] compared to non-PVE patients [3.2 (IQR 2.8-3.8) and 1.5 (IQR 1.3-1.6)] (p < 0.001). ROC-curve analysis of SUVratio yielded an area under the curve of 0.90 (95 % CI 0.74-1.0). (18)F-FDG-uptake around non-infected aortic prosthetic valves was low. The level of (18)F-FDG-uptake in the prosthetic valve area showed a good diagnostic performance in the diagnosis of PVE.

  17. Accuracy of 3-Dimensional Transoesophageal Echocardiography in Assessment of Prosthetic Mitral Valve Dehiscence with Comparison to Anatomical Specimens

    PubMed Central

    Brown, Martin R.; Javorsky, George; Platts, David G.

    2010-01-01

    The evolution of echocardiography from 2-Dimensional Transthoracic Echo through to real time 3-Dimensional Transoesophageal Echo has enabled more accurate visualisation and quantification of valvular disorders especially prosthetic mitral valve paravalvular regurgitation. However, validation of accuracy is rarely confirmed by surgical or post-mortem specimens. We present a case directly comparing different echocardiographic modality images to post mortem specimens in a patient with prosthetic mitral valve paravalvular regurgitation. PMID:20886015

  18. Endometrial thermal balloon ablation under local anesthesia in patients with prosthetic heart valves: a pilot study.

    PubMed

    Soysal, M; Soysal, S K

    2000-01-01

    We treated eleven cases of high risk surgical candidate women with prosthetic heart valves, complaining of menorrhagia, by thermal balloon ablation under local anesthesia after pharmacological endometrial thinning. Menorrhagia was documented by a validated pad scoring system. All patients were severely anemic at presentation. Nine of them had one valve replaced among these cases, two were restenosic at presentation, one had twice mitral valve replacement. Two of them had two valves replaced. All procedures were performed under local anesthesia supplemented by analgesics, no complications were observed either intraoperatively or during the follow-up of at least 24 months. After two years, thermal balloon ablation proved to be statistically significantly effective in terms of pad score reduction; two patients reported spotting and the rest was hypomenorrheic, none of the group experienced amenorrhea. This technique proved to be safe, feasible and effective under this clinical circumstances.

  19. Prosthetic reconstruction of bicuspid pulmonary valve in tetralogy of Fallot.

    PubMed

    Sasikumar, Navaneetha; Ramanan, Sowmya; Rema, Krishna Manohar Soman; Kumar, Raghavannair Suresh; Subramanyan, Raghavan; Cherian, Kootturathu Mammen

    2014-05-01

    Various techniques have been described for preserving pulmonary valve function in tetralogy of Fallot repair. In selected substrates, the pulmonary valve can be bicuspidized and preserved using polytetrafluoroethylene pericardial membrane. This study was a retrospective review of 20 patients aged 11 months to 31 years with tetralogy of Fallot and a bicuspid pulmonary valve (with anteroposterior cusps) who underwent intracardiac repair from August 2010 to January 2013. The anterior cusp was augmented using polytetrafluoroethylene pericardial membrane to preserve the valve hinge. A transannular patch was used in all cases. Data relating to surgical outcome, intensive care unit course, pulmonary regurgitation, and right ventricular outflow tract gradient were collected. There was no mortality. Predischarge pulmonary regurgitation was ≤grade 2 in 18 (90%) patients. One patient had an outflow gradient >40 mm Hg. On follow-up of 3-24 months, there was no increase in outflow gradient; 18.7% had progression of pulmonary regurgitation. In selected substrates, this technique is associated with minimization of pulmonary regurgitation and an excellent functional outcome. The utility of this technique needs to be validated over a longer time scale in a larger series.

  20. Development and marketing of a prosthetic urinary control valve system

    NASA Technical Reports Server (NTRS)

    Tenney, J. B., Jr.; Rabinowitz, R.; Rogers, D. W.; Harrison, H. N.

    1983-01-01

    An implantable prosthetic for the control of urinary incontinence was developed and marketed. Three phases are presented: bench development studies, animal trials, and human clinical trials. This work was performed under the direction of a Research Team at Rochester General Hospital (RGH). Bench trials were completed on prototype hardware and provided early verification of the device's ability to withstand repeated cyclic testing. Configurational variants were evaluated and a preferred design concept was established. Silicone rubber (medical grade) was selected as the preferred material for the prosthesis.

  1. Indium-111 labeled platelet survival time studies in patients with prosthetic heart valves

    SciTech Connect

    Martinovitch, U.; Carrick, P.; Lieberman, L.M.

    1985-05-01

    Platelet survival time (PST) studies are useful to demonstrate whether or not patients with prosthetic heart valves have normal or shortened PST. During treatment for recurrent TIAs the PST will signal whether the patient is returning towards a normal PST. Using Indium-111 labeled platelets (ILP) the authors studied 10 patients suffering recurrent TIAs after prosthetic valve surgery to determine whether low dose aspirin increased their PST toward normal and whether the treatment had a beneficial effect on their TIA episodes. The authors conclude that low dose aspirin therapy as studied by ILP has no beneficial effect on PST or in preventing recurrent TIA. ILP is an important technique that allows the physician to identify those patients with shortened PST and to determine response to therapy.

  2. Intermittent stuck valve after aortic valve replacement with a mechanical valve

    PubMed Central

    Luo, Wenzong; Wang, Xinxin; Li, Jing; Mu, Yun; Ni, Yiming

    2017-01-01

    Abstract Background: Intermittent stuck valve after mechanical valve replacement surgery is a very rare and severe complication. Case summary: We present 1 case of a 53-year-old woman after aortic valve replacement for severe aortic valve stenosis combined with hypertrophy septum. She was diagnosed with intermittent stuck valve only 1 day after surgery by clinical symptoms, intraoperative transoesophageal echocardiogram, and intraoperative findings. Conclusions: Although indications for concomitant myectomy during aortic valve replacement are not clear, we recommend myectomy to prevent stuck valve after St Jude Medical Regent prosthesis replacement for severe aortic valve stenosis combined with hypertrophy septum. PMID:28248877

  3. Comparison of the occurrence of thromboembolic and bleeding complications in patients with mechanical heart valve prosthesis with one and two leaflets in the mitral position

    PubMed Central

    de Campos, Nelson Leonardo Kerdahi Leite

    2014-01-01

    Introduction Patients with mechanical heart valve prostheses must continuously be treated with oral anticoagulants to prevent thromboembolic events related to prosthetesis. These patients should be continually evaluated for the control of oral anticoagulation. Objective To compare the occurrence of thromboembolic and hemorragic complications in patients with mechanical heart valve prosthesis with one (mono) and two (bi) leaflets in the mitral position in anticoagulant therapy. Methods We studied the 10-year interval, 117 patients with prosthesis in the mitral position, 48 with prosthetic single leaflet and 69 with two leaflets. We evaluated the occurrence of thromboembolic and hemorrhagic major and minor degree under gravity. The results are presented in an actuarial study and the frequency of occurrence of linear events. Results The actuarial survival curves showed that over time, patients with prosthetic heart valve with one leaflet were less free of thromboembolic complications than patients with two leaflet prosthetic valve, while the latter (two leaflet) were less free of hemorrhagic accidents. The linearized frequency of occurrence of thromboembolism were higher in patients with mono leaflet prosthesis. Bleeding rates were higher for patients with bi leaflet prosthetic valve. Conclusion Patients with mono leaflet prosthetic heart valve showed that they are more prone to the occurrence of serious thromboembolic events compared to those with bi leaflet prosthetic valve. Patients with bi leaflet prosthetic valve had more bleeding than patients with mono leaflet prosthetic valve, however this difference was restricted to the bleeding of minor nature. PMID:24896164

  4. NT-proBNP and exercise capacity in adult patients with congenital heart disease and a prosthetic valve: a multicentre PROSTAVA study.

    PubMed

    Schoonbeek, R C; Pieper, P G; van Slooten, Y J; Freling, H G; Sieswerda, G T; van Dijk, A P J; Jongbloed, M R M; Post, M C; Bouma, B J; Berger, R M F; Ebels, T; van Melle, J P

    2016-11-01

    N-terminal B‑type natriuretic peptide (NT-proBNP) is an important biomarker for the detection of heart failure. Adults with congenital heart disease (ACHD) and a prosthetic heart valve are at risk for heart failure. This study aimed to determine the value of NT-proBNP in ACHD patients with a prosthetic valve and investigate its relationship with cardiac function and exercise capacity. In this multi-centre cross-sectional observational study, data regarding medical history, echocardiography, exercise testing (VO2peak) and laboratory blood evaluation (including NT-proBNP) were collected in ACHD patients with a single prosthetic valve (either homografts, heterografts or mechanical valves). A total of 306 ACHD patients with pulmonary valve replacement (PVR, n = 139), aortic valve replacement (n = 141), mitral valve replacement (n = 21) or tricuspid valve replacement (n = 5) were investigated. The majority of patients (77 %) were in NYHA class I or II. Elevated NT-proBNP levels (cut-off ≥125 pg/ml) were found in 50 % of the patients, with the highest levels in patients with mitral valve replacements. In this study population, NT-proBNP levels were associated with gender (p = 0.029) and VO2max (p < 0.001). In PVR patients, NT-proBNP levels were associated with lower VO2peak, also after adjustment for age, gender and age at valve replacement in a multivariate model (p = 0.015). In patients with ACHD and a prosthetic valve, elevated NT-proBNP levels are frequently observed despite preserved NYHA class. In PVR patients, a higher NT-proBNP level was associated with a lower VO2peak. These results may be of importance in the ongoing discussion about the timing of valve replacement in patients with CHD.

  5. Cytokine profiles linked to fatal outcome in infective prosthetic valve endocarditis.

    PubMed

    Bustamante, Juan; Arévalo, Adolfo; Tamayo, Eduardo; Sarria, Cristina; Aguilar-Blanco, Eva M; Heredia, Maria; Almansa, Raquel; Rico, Lucia; Iglesias, Verónica; Bermejo-Martin, Jesús F

    2014-06-01

    Infective endocarditis is a disease normally of bacterial cause which affects the endocardic tissue, specifically the valves (native or prosthetic). It is a serious illness and mortality rates remain high, ranging between 20% and 40%. Previous reports have evidenced the potential role of cytokines in the diagnosis of this disease, but no information is available on their relationship with outcome. We recruited 26 consecutive patients with late prosthetic valve endocarditis requiring surgical treatment according to Duke criteria. Eight cytokines were measured in plasma in the first 24 h following diagnosis by using a Bio-Rad multiplex assay. Levels of IL-6, IL-8 and interferon gamma (IFN-γ) were higher in non survivors. Receiver operating characteristic curve analysis evidenced that IL-6, IL-8 and IFN-γ behaved as good diagnostic tests for identifying those patients with fatal outcome (area under the curve, CI 95%, p): IL-6: [0.81 (0.61-1.00) 0.012]; IL-8 [0.76 (0.56-0.96) 0.035]; IFN-γ [0.79 (0.59-0.99) 0.021]. Levels of IL-6, IL-8 and IFN-γ correlated positively between them, indicating that they are produced as consequence of a simultaneous response to the infection. Our findings support the participation of IL-6, IL-8 and IFN-γ in the events linked to fatal outcome in infective prosthetic valve endocarditis.

  6. The performance of the Braunwald-Cutter aortic prosthetic valve.

    PubMed

    Blackstone, E H; Kirklin, J W; Pluth, J R; Turner, M E; Parr, G V

    1977-04-01

    Four hundred seventy-five patients underwent aortic valve replacement with the Braunwald-Cutter ball-valve prosthesis at two institutions. The early (30-day) hospital mortality was 4.7% for those with isolated aortic valve replacement and 6.9% for the entire group. For the former, 5-year actuarial survival of the hospital survivors was 72 +/- 5.7%; for the latter group it was 71 +/- 4.4%. Eleven patients (5 since the date of follow-up inquiry) have suffered poppet escape, 9 of whom died. The actuarial incidence of known poppet escape is 4 +/- 2.6% at 47 months; when the 5 patients suffering poppet escape since the date of follow-up inquiry are included, with certain assumptions, the incidence is 3.7 +/- 1.14%. The projected probability of poppet escape using all 11 patients is 12.2% at 5 years; the 70% confidence bands of projected probability of poppet escape separate from those of the risk of re-replacement at 61 months. This and other analyses indicate that in general, patients with the Braunwald-Cutter aortic prosthesis should have it replaced 4 1/2 to 5 years after its insertion.

  7. Twenty-two year experience with the omniscience prosthetic heart valve.

    PubMed

    Misawa, Yoshio; Taguchi, Masanobu; Aizawa, Kei; Takahashi, Hideki; Sakano, Yasuhito; Kaminishi, Yuichiro; Oki, Shin-Ichi; Konishi, Hiroaki; Saito, Tsutomu; Kato, Morito

    2004-01-01

    This study was designed to evaluate the long-term clinical results of the Omniscience tilting disc valve. Omniscience valves were implanted in 51 patients (mean age, 50 +/- 10 years); 18 had aortic valve, 24 had mitral valve, and 9 had both aortic and mitral valve replacements. Oral warfarin potassium and dipyridamole were prescribed as our anticoagulant therapy. Preoperatively, 42 patients were in New York Heart Association class III or IV, and 23 of 25 surviving patients were in class I or II after operation. There were 2 (3.9%) early deaths and 23 late deaths (3.5 +/- 0.7% per patient-year). Cardiac related mortality including congestive heart failure, sudden death, and thromboembolism, and hemorrhagic complications were seen in 16 patients. Overall survival at 10, 15, and 20 years was 77 +/- 6%, 62 +/- 7%, and 46 +/- 7%, respectively. Thromboembolic complications were seen in 5 patients, for a rate of 0.8 +/- 0.3% per patient-year; similarly, hemorrhagic complications were also seen in 5 patients. Nonstructural prosthetic valve dysfunction was seen in 4 patients, for a rate of 0.6 +/- 0.3% per patient-year, and sudden death was seen in 2, a rate of 0.3 +/- 0.2% per patient-year. The Omniscience prosthesis demonstrated excellent postoperative clinical status with low rates of valve related complications.

  8. Single-center experience with the bicarbon bileaflet prosthetic heart valve in Japan.

    PubMed

    Misawa, Yoshio; Saito, Tsutomu; Konishi, Hiroaki; Oki, Shin-ichi; Kaminishi, Yuichiro; Tezuka, Yasuhiro; Aizawa, Kei; Takahashi, Hideki; Hasegawa, Nobuyuki; Kamisawa, Osamu; Kato, Morito; Fuse, Katsuo

    2002-10-01

    We analyzed midterm results using the Bicarbon valve in a single center. Forty-four patients had aortic valve replacement (AVR), 48 had mitral valve replacement (MVR), and 13 had both aortic and mitral valve replacement (DVR). The mean age of the 105 patients was 61.2 +/- 11.3 years. The mean follow-up was 1.8 +/- 1.1 years with a cumulative follow-up of 188 patient-years. There were 5 early deaths (4.7%: 4 in the AVR group and 1 in the MVR group) and 5 late deaths (2.7% per patient-year: 3 malignancy, 1 cerebral hemorrhage, 1 myocardial infarction). Survival at 3 years was 91 +/- 4% in the AVR group, 92 +/- 5% in the MVR group, and 66 +/- 23% in the DVR group. The linearized incidence of thromboembolic complications, hemorrhagic complications, and paravalvular leaks in all patients was 1.06 +/- 2.34%, 1.60 +/- 2.53%, and 0.53 +/- 2.22% per patient-year, respectively. No other complications were observed. In conclusion, the Bicarbon prosthetic heart valve has shown excellent clinical results associated with a low incidence of valve-related complications.

  9. Comparison of different TEE-guided thrombolytic regimens for prosthetic valve thrombosis: the TROIA trial.

    PubMed

    Özkan, Mehmet; Gündüz, Sabahattin; Biteker, Murat; Astarcioglu, Mehmet Ali; Çevik, Cihan; Kaynak, Evren; Yıldız, Mustafa; Oğuz, Emrah; Aykan, Ahmet Çağrı; Ertürk, Emre; Karavelioğlu, Yusuf; Gökdeniz, Tayyar; Kaya, Hasan; Gürsoy, Ozan Mustafa; Çakal, Beytullah; Karakoyun, Süleyman; Duran, Nilüfer; Özdemir, Nihal

    2013-02-01

    The aim of this prospective study was to identify the most effective and safest regimen among different thrombolytic treatment strategies. The best treatment strategies for prosthetic valve thrombosis have been controversial. Transesophageal echocardiography-guided thrombolytic treatment was administered to 182 consecutive patients with prosthetic valve thrombosis in 220 different episodes (156 women; mean age, 43.2 ± 13.06 years) between 1993 and 2009 at a single center. These regimens chronologically included rapid (Group I), slow (Group II) streptokinase, high-dose (100 mg) tissue plasminogen activator (t-PA) (Group III), a half-dose (50 mg) and slow infusion (6 h) of t-PA without bolus (Group IV), and a low dose (25 mg) and slow infusion (6 h) of t-PA without bolus (Group V). The endpoints were thrombolytic success, in-hospital mortality, and nonfatal complication rates. The overall success rate in the whole series was 83.2%; it did not differ significantly among Groups I through V (68.8%, 85.4%, 75%, 81.5%, and 85.5%, respectively; p = 0.46). The overall complication rate in the whole series was 18.6%. Although the overall complication rate was similar among Groups I through IV (37.5%, 24.4 %, 33.3%, and 29.6%, respectively; p > 0.05 for each comparison), it was significantly lower in Group V (10.5%, p < 0.05 for each). The combined rates of mortality and nonfatal major complications were also lower in Group V than in the other groups, with all differences significant except for comparison of Groups IV and V. By multivariate analysis, the predictors of combined mortality plus nonfatal major complications were any thrombolytic therapy regimen other than Group V (odds ratios for Groups I through IV: 8.2, 3.8, 8.1, and 4.1, respectively; p < 0.05 for each) and a history of stroke/transient ischemic attack (odds ratio: 3.5, p = 0.011). In addition, there was no mortality in Group V. Low-dose slow infusion of t-PA repeated as needed without a bolus provides

  10. Systolic closure of aortic valve in patients with prosthetic mitral valves.

    PubMed Central

    Eldar, M; Motro, M; Rath, S; Schy, N; Neufeld, H N

    1982-01-01

    Systolic closure of the aortic valve was found in 10 of 36 patients who underwent mitral valve replacement. Eight patients had early systolic closure, and two had mid-systolic closure. The left ventricular outflow tract dimension on M-mode and two dimensional echocardiograms, left ventricular posterior wall and septal thickness, left ventricular dimensions in systole and diastole, aortic valve opening, and mitral to aortic valve distance were not significantly different between patients with and without systolic closure of the aortic valve. Two of the 10 patients with systolic aortic valve closure were catheterised and in neither was there a gradient between the left ventricle and the aorta. The two patients with mid-systolic closure, however, were the patients who had the narrowest left ventricular outflow tract which could cause significant distortion of blood flow. Systolic closure of the aortic valve in patients with mitral valve replacement is probably not caused by left ventricular outflow tract obstruction, though abnormalities in laminar flow from the left ventricular outflow tract may be involved. Images PMID:7082513

  11. Evaluation of prosthetic venous valves, fabricated by electrospinning, for percutaneous treatment of chronic venous insufficiency.

    PubMed

    Moriyama, Masaki; Kubota, Shinichiro; Tashiro, Hideo; Tonami, Hiroyuki

    2011-12-01

    Chronic venous insufficiency (CVI) remains a major health problem worldwide. Direct venous valve surgical repair and venous segment transplantation are clinical options; however, they are highly invasive procedures. The objectives of this study were to fabricate prosthetic venous valves (PVVs) by electrospinning, for percutaneous treatment of CVI, and evaluate their hydrodynamic characteristics in vitro at the same locations and under the same flow conditions. The PVVs consisted of polyurethane fiber scaffolds attached to a cobalt-chromium stent. PVVs with two different valve-leaflet configurations were compared: biomimetic PVV (bPVV) and open PVV (oPVV). A balloon catheter was used to implant the devices in a poly(vinyl chloride) tube and the column outlet was set at a height of 100 cm above the test valve to simulate the elevation of the heart above a distal vein valve while standing; 50 wt% glycerin solution was used as the test fluid. The devices were evaluated for antegrade flow, effect of ankle flexion, and stagnation zones around the valve leaflets. During sudden hydrostatic backpressure, little leakage and constant peripheral pressure were observed for the devices; under forward pulsatile pressure of 0-4 mmHg, to simulate the effect of breathing, the oPVV had a higher flow rate than the bPVV. With regard to the effect of ankle flexion, the oPVV was functionless. Moreover, the stagnation zone around the oPVV valve leaflets was larger than that around the bPVV valve leaflets. These results suggest that the bPVV would be clinically suitable for percutaneous treatment of CVI.

  12. The impact of imperfect frame deployment and rotational orientation on stress within the prosthetic leaflets during transcatheter aortic valve implantation.

    PubMed

    Bailey, Jonathon; Curzen, Nick; Bressloff, Neil W

    2017-02-28

    TAVI devices are manufactured with cylindrical frames. However, the frames are rarely cylindrical post-deployment since deformation due to localised under expansion can be induced by calcified material on the native valve leaflets exerting irregular forces upon the frame. Consequently, the leaflets within a deformed TAVI device may undergo elevated stress during operation, which may lead to premature device failure. Using computational analysis a complete TAVI device model was simulated undergoing deployment into an aortic root model derived from CT data for a patient with severe calcific aortic stenosis, followed by a pressure simulated cardiac cycle. The complete analysis was performed eight times, each with the device at a different rotational orientation relative to the native valve, with an increment spacing of 15°. The TAVI device frames consistently featured significant distortions associated with bulky calcified material at the base of the non-coronary sinus. It was found that the average von Mises stress in the prosthetic valves was only increased in one of the cases relative to an idealised device. However, the maximum von Mises stress in the prosthetic valves was elevated in the majority of the cases. Furthermore, it was found that there were preferable orientations to deploy the prosthetic device, in this case, when the prosthetic leaflets were aligned with the native leaflets. As device orientation deviated from this orientation, the stresses in the valve increased because the distance between the prosthetic commissures decreased. This potentially could represent a sufficient increase in stress to induce variation in device lifespan.

  13. [Prosthetic Valve Endocarditis using Immunosuppressive Agent for Atopic Dermatitis;Report of a Case].

    PubMed

    Tanioka, Hideki; Iwata, Keiji; Marumoto, Akira; Kaneko, Mitsunori

    2015-05-01

    A 26-year-old man had a history of severe atopic dermatitis. He was taking immunosuppressive drug. Mitral valve replacement (MVR) had been performed for infective endocarditis March 2008. He came to our hospital in July 2012 complaining of fever of 39 degrees Celsius. According to computed tomography (CT) and transesophageal echocardiography (TEE), we diagnosed that he had cerebral embolism and bacterial infection of prosthetic valve. Antibiotic treatment was performed for 2 weeks after the onset of cerebral infarction. Then we conducted re-MVR. The postoperative course was satisfactory. He showed a gradual improvement in the level of consciousness and was discharged. In patients with atopic dermatitis, bacteria can penetrate into the blood from the skin easily. So they are often affected by bacteremia. There are some reports that infective endocarditis is likely to occur in immunosuppressed patients. It is suggested that immunosuppressive drug was involved in the development of prosthetic valve endocarditis (PVE) in addition to atopic dermatitis in this patient.

  14. Novel method for the in vivo detection of single leg separation failures in prosthetic heart valves

    NASA Astrophysics Data System (ADS)

    Long, Jie; Udpa, Satish S.; Sun, Yushi

    2002-06-01

    This paper presents a novel technique for the in vivo detection of single strut failures in Bjork-Shiley convexo-concave prosthetic heart valves. The method makes use of Lorentz forces to excite the resonant modes of the strut. The forces are generated by immersing the valve in a static magnetic field and inducing eddy currents in the valve using an auxiliary coil excited by a tone burst. The tone frequency is set at a value that is close to the resonant frequency of an Intact Outlet Strut. The state of the strut is assessed by measuring the acoustic field generated in response to the excitation, using a hydrophone placed on the chest of the patient. An intact outlet strut is indicated if the excitation is able to excite the resonant modes, which correspond to those of a healthy outlet strut. The paper describes work done in simulating the BSCC heart valve using finite element methods to estimate the modal frequencies. Simulation results together with experimental data supporting the predictions are presented. This work was supported by the Trustees of the Bowling-Pfizer Heart Valve Settlement Funds.

  15. Legionella micdadei prosthetic valve endocarditis complicated by brain abscess: case report and review of the literature.

    PubMed

    Fukuta, Yuriko; Yildiz-Aktas, Isil Z; William Pasculle, A; Veldkamp, Peter J

    2012-06-01

    Legionella endocarditis is extremely uncommon, and embolic phenomena have never been reported. We report the first case of Legionella micdadei prosthetic valve endocarditis complicated by brain abscess. A 57-y-old immunocompromised woman with a history of mitral valve replacement developed confusion and left-sided weakness. Brain magnetic resonance imaging showed a 3-cm peripheral-enhancing mass. Transoesophageal echocardiography suggested a perivalvular abscess. Blood cultures and valve cultures were negative. She was diagnosed with 16S rRNA polymerase chain reaction and silver stain, and was discharged with levofloxacin after a redo mitral valve replacement. Twelve cases of Legionella endocarditis were reviewed. Only one case had a native valve, and her endocarditis occurred after pneumonia. All cases were cured. The duration of antibiotic therapy was variable. Legionella species should be considered in the differential diagnosis of culture-negative endocarditis in both immunocompetent and immunocompromised patients. Molecular techniques and silver impregnation stains are useful, especially when cultures using buffered charcoal-yeast extract agar are negative.

  16. Performance assessment of prosthetic heart valves using the energy index method.

    PubMed

    Souza-Campos, F; Schoephoerster, R T

    1996-01-01

    Traditional methods of characterizing valvular performance use some estimation of the effective opening area and the percent regurgitant volume. These methods are cumbersome because two parameters are used and their importance relative to one another is not revealed. The authors propose the use of a single parameter that is physically meaningful and accounts for characteristics of the valve throughout the cardiac cycle. The energy index, derived with use of a phase-by-phase analysis of the cardiac cycle, describes the energetic efficiency of the valve. The method's final form is: [Formula: see text] where Eps is the hydraulic energy available after systole, E+ is the energy dissipated in the valve while flow is positive, [Symbol: see text]_ and [Symbol: see text] are the regurgitant and forward volumes, respectively. Use of the El requires on-line measurement of valvular flow rate and pressure drop. The El was applied to a Medtronic-Hall (Minneapolis, MN), 25 mm prosthetic valve mounted in the aortic position of a cardiovascular simulator. Mild and severe degrees of valvular stenosis and regurgitance were simulated. Results indicate that the El is sensitive to either valvular condition and remains nearly constant, at 87%, for the normal valve tested over cardiac rates ranging from 50 to 100 beats per minute.

  17. Propionibacterium acnes prosthetic valve endocarditis with abscess formation: a case report

    PubMed Central

    2014-01-01

    Background Endocarditis due to Propionibacterium acnes is a rare disease. Scant data on treatment of these infections is available and is based on case reports only. If the disease is complicated by abscess formation, surgical intervention combined with an antibiotic therapy might improve clinical outcome. In some cases, cardiac surgeons are reluctant to perform surgery, since they consider the intervention as high risk. Therefore, a conservative therapy is required, with little, if any evidence to choose the optimal antibiotic. We report the first case of a successfully treated patient with P. acnes prosthetic valve endocarditis without surgery. Case presentation We report the case of a 29-year-old patient with a prosthetic valve endocarditis and composite graft infection with abscess formation of the left ventricular outflow tract due to P. acnes. Since cardiac surgery was considered as high risk, the patient was treated intravenously with ceftriaxone 2 g qd and rifampin 600 mg bid for 7 weeks and was switched to an oral therapy with levofloxacin 500 mg bid and rifampin 600 mg bid for an additional 6 months. Two sets of blood cultures collected six weeks after completion of treatment remained negative. The patient is considered to be cured based on absence of clinical signs and symptoms, normal laboratory parameters, negative radiology scans and negative blood cultures, determined at site visits over two years after completion of treatment. Conclusion To our knowledge, this is the first successfully managed patient with P. acnes prosthetic valve endocarditis with abscess formation of the left ventricular outflow tract who was treated with antibiotics alone without a surgical intervention. A six month treatment with a rifampin and levofloxacin combination was chosen, based on the excellent activity against stationary-phase and adherent bacteria. PMID:24568204

  18. FLUID MECHANICS OF ARTIFICIAL HEART VALVES

    PubMed Central

    Dasi, Lakshmi P; Simon, Helene A; Sucosky, Philippe; Yoganathan, Ajit P

    2009-01-01

    SUMMARY 1. Artificial heart valves have been in use for over five decades to replace diseased heart valves. Since the first heart valve replacement performed with a caged-ball valve, more than 50 valve designs have been developed, differing principally in valve geometry, number of leaflets and material. To date, all artificial heart valves are plagued with complications associated with haemolysis, coagulation for mechanical heart valves and leaflet tearing for tissue-based valve prosthesis. For mechanical heart valves, these complications are believed to be associated with non-physiological blood flow patterns. 2. In the present review, we provide a bird’s-eye view of fluid mechanics for the major artificial heart valve types and highlight how the engineering approach has shaped this rapidly diversifying area of research. 3. Mechanical heart valve designs have evolved significantly, with the most recent designs providing relatively superior haemodynamics with very low aerodynamic resistance. However, high shearing of blood cells and platelets still pose significant design challenges and patients must undergo life-long anticoagulation therapy. Bioprosthetic or tissue valves do not require anticoagulants due to their distinct similarity to the native valve geometry and haemodynamics, but many of these valves fail structurally within the first 10–15 years of implantation. 4. These shortcomings have directed present and future research in three main directions in attempts to design superior artificial valves: (i) engineering living tissue heart valves; (ii) development of advanced computational tools; and (iii) blood experiments to establish the link between flow and blood damage. PMID:19220329

  19. Late embolization of prosthetic mitral valve occluder with survival following reoperation.

    PubMed

    Hughes, D A; Leatherman, L L; Norman, J C; Cooley, D A

    1975-02-01

    Embolization of the occluder from a prosthetic mitral valve is an extremely rare event. Previous reports in the literature have described the uniformly fatal outcome of this complication. A case in which the occluder from a Wada-Cutter mitral prosthesis embolized five years following implantation is presented. The patient survived following emergency reoperation. Several unique features of escaped mitral poppet are discussed. Depending upon cardiac reserves, patients who have this complication may live long enough to allow emergency operative intervention and eventual recovery.

  20. In-vitro Measurements of the Synoptic Velocity Generated by a Prosthetic Aortic Valve

    NASA Astrophysics Data System (ADS)

    Spellings, K.; Lourenco, L.

    1997-11-01

    The objective of this study is to provide a precise means of evaluating the hydrodynamic performance of prosthetic aortic and mitral valves. Particle Image Velocimetry is used to measure the in-plane velocity components in selected planes of the flow, from which the turbulent shear stress is derived. The experimental facility used in this study is made of plexiglas tube, and has a circular cross section with a diameter that matches that of the valve. To ensure optical access the test fluid used matches the refractive index of plexiglas and the test section incorporates a square housing filled with the same fluid. The fluid used in this experiment is a mixture of glycerol, water and sodium iodide. Pulsatile flow is achieved by means of a pump and monitored in real time by means of an electronic flowmeter. Dynamic similarity is ensured in these experiments as the viscosity of the fluid mixture closely approximates that of blood.

  1. Prosthetic heart valves in pregnancy: a systematic review and meta-analysis protocol

    PubMed Central

    2014-01-01

    Background Advances in surgical technique, prosthetic heart valve design, and anticoagulation have contributed to an overall improvement in morbidity and mortality in women with heart valve prostheses as well as increased feasibility of pregnancy. Previous work investigating the pregnancies of women with prosthetic valves has been directed largely toward understanding the influence of anticoagulation regimen. There has been little investigation on maternal and infant outcomes. The objective of this systematic review will be to assess the outcomes of pregnancy in women with heart valve prostheses in contemporary populations. Methods/Design A systematic search of Medline, Embase, Cumulative Index to Nursing and Allied Health Literature (CINAHL), and the Cochrane Library will be undertaken. Article titles and abstracts will be evaluated by two reviewers for potential relevance. Studies that include pregnancies occurring from 1995 onwards and where there are six or more pregnancies in women with heart valve prostheses included in the study population will be reviewed for potential inclusion. Primary outcomes of interest will be mortality (maternal and perinatal). Secondary outcomes will include other pregnancy outcomes. No language restrictions will be applied. Methodological quality and heterogeneity of studies will be assessed. Data extraction from identified articles will be undertaken by two independent reviewers using a uniform template. Meta-analyses will be performed to ascertain risk of adverse events and, where numbers are sufficient, by type of prosthesis and location as well as other subgroup analyses. Discussion Estimates of the risk of adverse events in recent pregnancies of women with heart valve prosthesis will provide better information for counselling and decision making. Given the improvements in prognosis of heart valve prosthesis recipients and the paucity of definitive data regarding optimal pregnancy management for these women, review of this

  2. Are anticoagulant independent mechanical valves within reach—fast prototype fabrication and in vitro testing of innovative bi-leaflet valve models

    PubMed Central

    Siegel, Rolland

    2015-01-01

    Background Exploration for causes of prosthetic valve thrombogenicity has frequently focused on forward or post-closure flow detail. In prior laboratory studies, we uncovered high amplitude flow velocities of short duration close to valve closure implying potential for substantial shear stress with subsequent initiation of blood coagulation pathways. This may be relevant to widely accepted clinical disparity between mechanical and tissue valves vis-à-vis thrombogenicity. With a series of prototype bi-leaflet mechanical valves, we attempt reduction of closure related velocities with the objective of identifying a prototype valve with thrombogenic potential similar to our tissue valve control. This iterative design approach may find application in preclinical assessment of valves for anticoagulation independence. Methods Tested valves included: prototype mechanical bi-leaflet BVs (n=56), controls (n=2) and patented early prototype mechanicals (n=2) from other investigators. Pulsatile and quasi-steady flow systems were used for testing. Projected dynamic valve area (PDVA) was measured using previously described novel technology. Flow velocity over the open and closing periods was determined by volumetric flow rate/PDVA. For the closed valve interval, use was made of data obtained from quasi-steady back pressure/flow tests. Performance was ranked by a proposed thrombogenicity potential index (TPI) relative to tissue and mechanical control valves. Results Optimization of the prototype valve designs lead to a 3-D printed model (BV3D). For the mitral/aortic site, BV3D has lower TPI (1.10/1.47) relative to the control mechanical valve (3.44/3.93) and similar to the control tissue valve (ideal TPI ≤1.0). Conclusions Using unique technology, rapid prototyping and thrombogenicity ranking, optimization of experimental valves for reduced thrombogenic potential was expedited and simplified. Innovative mechanical valve configurations were identified that merit consideration

  3. Successful management of multiple permanent pacemaker complications – infection, 13 year old silent lead perforation and exteriorisation following failed percutaneous extraction, superior vena cava obstruction, tricuspid valve endocarditis, pulmonary embolism and prosthetic tricuspid valve thrombosis

    PubMed Central

    Kaul, Pankaj; Adluri, Krishna; Javangula, Kalyana; Baig, Wasir

    2009-01-01

    A 59 year old man underwent mechanical tricuspid valve replacement and removal of pacemaker generator along with 4 pacemaker leads for pacemaker endocarditis and superior vena cava obstruction after an earlier percutaneous extraction had to be abandoned, 13 years ago, due to cardiac arrest, accompanied by silent, unsuspected right atrial perforation and exteriorisation of lead. Postoperative course was complicated by tricuspid valve thrombosis and secondary pulmonary embolism requiring TPA thrombolysis which was instantly successful. A review of literature of pacemaker endocarditis and tricuspid thrombosis along with the relevant management strategies is presented. We believe this case report is unusual on account of non operative management of right atrial lead perforation following an unsuccessful attempt at percutaneous removal of right sided infected pacemaker leads and the incidental discovery of the perforated lead 13 years later at sternotomy, presentation of pacemaker endocarditis with a massive load of vegetations along the entire pacemaker lead tract in superior vena cava, right atrial endocardium, tricuspid valve and right ventricular endocardium, leading to a functional and structural SVC obstruction, requirement of an unusually large dose of warfarin postoperatively occasioned, in all probability, by antibiotic drug interactions, presentation of tricuspid prosthetic valve thrombosis uniquely as vasovagal syncope and isolated hypoxia and near instantaneous resolution of tricuspid prosthetic valve thrombosis with Alteplase thrombolysis. PMID:19239701

  4. Does the Use of a Decision Aid Improve Decision Making in Prosthetic Heart Valve Selection? A Multicenter Randomized Trial.

    PubMed

    Korteland, Nelleke M; Ahmed, Yunus; Koolbergen, David R; Brouwer, Marjan; de Heer, Frederiek; Kluin, Jolanda; Bruggemans, Eline F; Klautz, Robert J M; Stiggelbout, Anne M; Bucx, Jeroen J J; Roos-Hesselink, Jolien W; Polak, Peter; Markou, Thanasie; van den Broek, Inge; Ligthart, Rene; Bogers, Ad J J C; Takkenberg, Johanna J M

    2017-02-01

    A Dutch online patient decision aid to support prosthetic heart valve selection was recently developed. A multicenter randomized controlled trial was conducted to assess whether use of the patient decision aid results in optimization of shared decision making in prosthetic heart valve selection. In a 5-center randomized controlled trial, patients were allocated to receive either standard preoperative care (control group) or additional access to the patient decision aid (intervention group). Legally capable adult patients accepted for elective isolated or combined aortic and mitral valve replacement were included. Primary outcome was preoperative decisional conflict (Decisional Conflict Scale); secondary outcomes included patient knowledge, involvement in valve selection, anxiety and depression, (valve-specific) quality of life, and regret. Out of 306 eligible patients, 155 were randomized (78 control and 77 intervention). Preoperative decisional conflict did not differ between the groups (34% versus 33%; P=0.834). Intervention patients felt better informed (median Decisional Conflict Scale informed subscore: 8 versus 17; P=0.046) and had a better knowledge of prosthetic valves (85% versus 68%; P=0.004). Intervention patients experienced less anxiety and depression (median Hospital Anxiety and Depression Scale score: 6 versus 9; P=0.015) and better mental well-being (mean Short Form Health Survey score: 54 versus 50; P=0.032). Three months postoperatively, valve-specific quality of life and regret did not differ between the groups. A patient decision aid to support shared decision making in prosthetic heart valve selection does not lower decisional conflict. It does result in more knowledgeable, better informed, and less anxious and depressed patients, with a better mental well-being. http://www.trialregister.nl. Unique identifier: NTR4350. © 2017 American Heart Association, Inc.

  5. Mechanical valves in the pulmonary position: An international retrospective analysis.

    PubMed

    Pragt, Hanna; van Melle, Joost P; Javadikasgari, Hoda; Seo, Dong Man; Stulak, John M; Knez, Igor; Hörer, Jürgen; Muñoz-Guijosa, Christian; Dehaki, Mahyar G; Shin, Hong Ju; Dearani, Joseph A; Dehaki, Maziar G; Pieper, Petronella G; Eulenburg, Christine; Dos, Laura; Ebels, Tjark

    2017-10-01

    Life expectancy of patients with congenital heart disease has improved over the past decades, increasing the need for a durable pulmonary prosthetic valve. Biological valves in various forms have become the valve of choice for pulmonary valve replacement (PVR), but structural valve deterioration is unavoidable in the long term. Use of a mechanical valve could be an alternative, but data on long-term outcomes are sparse. We retrospectively collected and analyzed data on 364 patients with mechanical valves implanted in the pulmonary position between 1965 and 2014. The data originate from medical centers in Barcelona (Spain), Graz (Austria), Groningen (the Netherlands), Munich (Germany), Rochester (United States), Seoul (Republic of Korea), and Tehran (Iran). Median follow-up duration was 4.26 years (range, 0-27 years), mean age at implantation was 27.16 ± 12.2 years. Tetralogy of Fallot was the most common primary cardiac diagnosis, with a subgroup of 69.8%. Freedom from valvular thrombosis was 91% (95% confidence interval [CI], 87%-94%) at 5 years and 86% (95% CI, 81%-91%) at 10 years post-PVR. With a success rate up to 88%, thrombolysis was a successful therapy. Freedom from reoperation was 97% (95% CI, 94%-99%) at 5 years post-PVR and 91% (95% CI, 85%-95%) at 10 years. Mechanical PVR is associated with a limited risk of valvular thrombosis. Thrombolysis was an effective treatment in the majority. Copyright © 2017 The American Association for Thoracic Surgery. Published by Elsevier Inc. All rights reserved.

  6. Disseminated mycobacteriosis affecting a prosthetic aortic valve: first case of Mycobacterium peregrinum type III reported in Colombia.

    PubMed

    Torres-Duque, Carlos A; Díaz, Claudia; Vargas, Leslie; Serpa, Elsa María; Mosquera, Walter; Garzón, María Consuelo; Mejía, Graciela; García, Luz Mary; González, Liliana Andrea; Castro, Claudia Marcela; Ribón, Wellman

    2010-01-01

    Rapidly growing mycobacteria are non-tuberculous mycobacteria amply present in the environment. Although they are not usually pathogenic for humans, they are opportunistic in that they can cause disease in people with disadvantageous conditions or who are immunocompromised. Mycobacterium peregrinum, an opportunistic, rapidly growing mycobacteria, belongs to the M. fortuitum group and has been reported as responsible for human cases of mycobacteriosis. A case of M. peregrinum type III is herein reported as the first in Colombia. It presented as a disseminated disease involving a prosthetic aortic valve (endocarditis) in a seventeen-year-old girl with a well-established diagnosis of prosthetic aortic valve endocarditis who was referred for a surgical replacement. Due to a congenital heart disease (subaortic stenosis with valve insufficiency), she had two previous aortic valve implantation surgeries. One year after the second implantation, the patient presented with respiratory symptoms and weight lost indicative of lung tuberculosis. A chest X-ray did not show parenchymal compromise but several Ziehl-Neelsen stains were positive. An echocardiography showed a vegetation on the prosthetic aortic valve. In blood and sputum samples, M. peregrinum type III was identified through culture, biochemical tests and hsp65 gene molecular analysis (PRA). The patient underwent a valve replacement and received a multidrug antimycobacterial treatment. Progressive recovery ensued and further samples from respiratory tract and blood were negative for mycobacteria.

  7. Valve operating mechanism for internal combustion engine

    SciTech Connect

    Nagahiro, K.; Ajiki, Y.; Katoh, M.; Inoue, K.

    1988-03-01

    A valve operating mechanism for operating a pair of valves of an internal combustion engine is described, comprising: a camshaft rotatable in synchronism with rotation of the internal combustion engine an having cams of different cam profiles; rocker arms held in sliding contact with the cams, respectively, for operating the valves according to the cam profiles of the cams; and means for independently selectively interconnecting and disconnecting selected of the rocker arms to operate the valves at different valve timings in low, medium and high speed ranges of the internal combustion engine.

  8. Valve operating mechanism for internal combustion engine

    SciTech Connect

    Inoue, K.; Nagahiro, K.; Ajiki, Y.; Katoh, M.

    1988-12-27

    A valve operating mechanism for operating a single valve of a particular cylinder of an internal combustion engine is described comprising: a camshaft rotatable in synchronism with rotation of the internal combustion engine; a plurality of cams on the camshaft with each of the cams bearing a different cam profile; a plurality of cam followers, each of which slidably engages one of the cams for selectively operating the valve according to the profile of the selected cam and one of which engages the valve; and means for selectively interconnecting and disconnecting the respective cam followers to operate the valve differently in different speed ranges of the internal combustion engine.

  9. Valve operating mechanism for internal combustion engine

    SciTech Connect

    Inoue, K.; Nagahiro, K.; Ajiki, Y.; Katoh, M.

    1988-12-13

    This patent describes a valve operating mechanism for operating valves of a particular cylinder of an internal combustion engine, comprising: a camshaft rotatable in synchronism with rotation of the internal combustion engine and having at least one cam; cam followers, one of which slidably engages with the cam for selectively operating the valves according to a cam profile of the cam; and means for selectively interconnecting and disconnecting the cam followers to operate the valves differently in different speed ranges of the internal combustion engine, the speed ranges including a range in which all of the valves remain inoperative.

  10. Long-term results after operations for active infective endocarditis in native and prosthetic valves.

    PubMed

    Meszaros, Katharina; Nujic, Sladjan; Sodeck, Gottfried H; Englberger, Lars; König, Tobias; Schönhoff, Florian; Reineke, David; Roost-Krähenbühl, Eva; Schmidli, Jürg; Czerny, Martin; Carrel, Thierry P

    2012-10-01

    The objective of this study was to evaluate the midterm results of patients who underwent operations for active infective endocarditis. Within a 10-year period, 141 patients with active infective endocarditis received surgical therapy. We assessed outcome, freedom from reinfection, and freedom from reintervention. Prosthetic valve endocarditis was included in this series. Surgical strategies included valve replacement with a tissue valve in 62% of patients and valve repair in 29% of patients. In 29% of patients, reconstruction of the aortomitral continuity, left ventricular outflow tract, or sinus of Valsalva was preferably performed with 1 or more bovine pericardial patches. In-hospital mortality was 11% and postoperative stroke rate was 7%. Multivariate logistic regression revealed multivalve involvement (p=0.052; odds ratio [OR], 5.84; 95% confidence interval [CI], 0.98-34.57), preoperative neurologic impairment (p=0.006; OR, 9.71; 95% CI, 1.92-49.09), and European system for cardiac operative risk evaluation (EuroSCORE) in quartiles (p=0.023; OR, 2.88; 95% CI, 1.15-7.17) to be independent predictors for in-hospital death. One-year and 5-year actuarial survival was 77% and 69%, respectively. One-year and 5-year actuarial freedom from reinfection was 100% and 90%, respectively. Freedom from reoperation at 5 years was 100%. Five-year survival was 74% for single-valve endocarditis and 46% for multivalve endocarditis (p<0.001). One-year freedom from reinfection was 100% for both single-valve and multivalve endocarditis; 5-year freedom from reinfection was 95% for single-valve endocarditis versus 67% for multivalve endocarditis (p=0.049). Despite a high early mortality during the first year, surgical intervention for active infective endocarditis provided excellent results with regard to freedom from reinfection and reoperation. A strategy of extensive debridement, reconstruction of destroyed cardiac structures using xenopericardium, followed by valve replacement or

  11. In-hospital and 1-year mortality in patients undergoing early surgery for prosthetic valve endocarditis.

    PubMed

    Lalani, Tahaniyat; Chu, Vivian H; Park, Lawrence P; Cecchi, Enrico; Corey, G Ralph; Durante-Mangoni, Emanuele; Fowler, Vance G; Gordon, David; Grossi, Paolo; Hannan, Margaret; Hoen, Bruno; Muñoz, Patricia; Rizk, Hussien; Kanj, Souha S; Selton-Suty, Christine; Sexton, Daniel J; Spelman, Denis; Ravasio, Veronica; Tripodi, Marie Françoise; Wang, Andrew

    2013-09-09

    There are limited prospective, controlled data evaluating survival in patients receiving early surgery vs medical therapy for prosthetic valve endocarditis (PVE). To determine the in-hospital and 1-year mortality in patients with PVE who undergo valve replacement during index hospitalization compared with patients who receive medical therapy alone, after controlling for survival and treatment selection bias. Participants were enrolled between June 2000 and December 2006 in the International Collaboration on Endocarditis-Prospective Cohort Study (ICE-PCS), a prospective, multinational, observational cohort of patients with infective endocarditis. Patients hospitalized with definite right- or left-sided PVE were included in the analysis. We evaluated the effect of treatment assignment on mortality, after adjusting for biases using a Cox proportional hazards model that included inverse probability of treatment weighting and surgery as a time-dependent covariate. The cohort was stratified by probability (propensity) for surgery, and outcomes were compared between the treatment groups within each stratum. Valve replacement during index hospitalization (early surgery) vs medical therapy. In-hospital and 1-year mortality. Of the 1025 patients with PVE, 490 patients (47.8%) underwent early surgery and 535 individuals (52.2%) received medical therapy alone. Compared with medical therapy, early surgery was associated with lower in-hospital mortality in the unadjusted analysis and after controlling for treatment selection bias (in-hospital mortality: hazard ratio [HR], 0.44 [95% CI, 0.38-0.52] and lower 1-year mortality: HR, 0.57 [95% CI, 0.49-0.67]). The lower mortality associated with surgery did not persist after adjustment for survivor bias (in-hospital mortality: HR, 0.90 [95% CI, 0.76-1.07] and 1-year mortality: HR, 1.04 [95% CI, 0.89-1.23]). Subgroup analysis indicated a lower in-hospital mortality with early surgery in the highest surgical propensity quintile (21

  12. Role of cine-fluoroscopy, transthoracic, and transesophageal echocardiography in patients with suspected prosthetic heart valve thrombosis.

    PubMed

    Montorsi, P; De Bernardi, F; Muratori, M; Cavoretto, D; Pepi, M

    2000-01-01

    Prosthetic heart valve thrombosis (PVT) is a rare but potentially life-threatening complication of heart valve replacement. An effective, quick, and easy diagnostic method is highly desirable. We evaluated the diagnostic efficacy of cine-fluoroscopy (CF), transthoracic (TTE), and transesophageal (TEE) echocardiography in 82 consecutive patients with mechanical valves and suspected PVT. Criteria for PVT were: leaflet(s) motion restriction at CF, increased Doppler gradients at TTE, and evidence of thrombi at TEE. Patients were divided in 4 groups (A, B, C, and D) according to results of CF and TTE. Group A was composed of 24 patients with positive CF and TTE. Thrombi were detected by TEE in all cases, suggesting that when both are positive, CF and TTE correctly identified PVT in all patients so that TEE may be deferred. Group B was composed of 12 patients with positive CF and negative TTE; TEE showed PVT in 4 patients (33%). These patients had very slight leaflet motion restriction as in the case of initial PVT. This suggests that CF compared with Doppler may identify patients with "hemodynamically significant" PVT. The remaining 8 patients in this group had monocuspid prostheses with negative TEE, suggesting that abnormal leaflet motion at CF may be due to functional changes. Therefore, TEE should always be performed in case of monocuspid prostheses with isolated CF abnormalities. Group C was composed of 18 asymptomatic patients with small-sized aortic prostheses and very high Doppler gradients on routine TTE. CF showed normal leaflet motion and TEE ruled out PVT in all cases outlining the diagnostic role of CF in this particular subset. Finally, group D was composed of 28 patients with negative CF and TTE. TEE did not show thrombi in 24 of 28 patients (86%), confirming that, when both yield negative results, CF and TTE are reliable methods to rule out valve thrombosis in most cases. However, in 4 of 28 patients (14%) TEE showed "nonobstructive" prosthetic

  13. DNA Persistence and Relapses Questions on the Treatment Strategies of Enterococcus Infections of Prosthetic Valves

    PubMed Central

    Casalta, Jean-Paul; Thuny, Franck; Fournier, Pierre-Edouard; Lepidi, Hubert; Habib, Gilbert; Grisoli, Dominique; Raoult, Didier

    2012-01-01

    We used amplification of the 16S rRNA gene followed by sequencing to evaluate the persistence of bacterial DNA in explanted heart valve tissue as part of the routine work of a clinical microbiology laboratory, and we analyzed the role of this persistence in the relapses observed in our center. We enrolled 286 patients treated for infective endocarditis (IE) who had valve replacement surgery and were diagnosed according to the modified Duke’s criteria described by Li et al. from a total of 579 IE cases treated in our center. The patients were grouped based on the infecting bacteria, and we considered the 4 most common bacterial genus associated with IE separately (144 were caused by Streptococcus spp., 52 by Enterococcus spp., 58 by Staphylococcus aureus and 32 by coagulase-negative Staphylococcus). Based on our cohort, the risk of relapse in patients with enterococcal prosthetic valve infections treated with antibiotics alone was 11%. Bacterial DNA is cleared over time, but this might be a very slow process, especially with Enterococcus spp. Based on a comprehensive review of the literature performed on Medline, most reports still advise combined treatment with penicillin and an aminoglycoside for as long as 4–6 weeks, but there has been no consensus for the treatment of enterococcal infection of prostheses in IE patients. PMID:23300913

  14. Role of anticardiolipin antibodies in the pathogenesis of prosthetic valve thrombosis: An observational study.

    PubMed

    Aykan, A Ç; Gökdeniz, T; Kalçık, M; Astarcıoğlu, M A; Gündüz, S; Karakoyun, S; Gürsoy, M O; Oğuz, A E; Ertürk, E; Çakal, B; Bayram, Z; Özkan, M

    2015-05-01

    Prosthetic valve thrombosis (PVT) is serious complication of valvular replacement surgery, and increased levels of anticardiolipin antibodies (aCL) are associated with thrombosis. The aim of this study was to evaluate the role of aCL in the development of PVT. We studied the aCL IgM and IgG levels in 114 patients with PVT and 80 healthy patients with prosthetic valves without PVT or a history of thrombosis. All patients underwent detailed transthoracic, transesophageal echocardiographic and clinical examinations. Blood samples were obtained after transesophageal echocardiography. Tests were repeated 12 weeks apart in patients with aCL IgM or IgG positivity. The mean age, sex, presence of atrial fibrillation and cardiovascular risk factors, elapsed time after surgery, and prosthetic valve type and location were similar between patients with PVT and those without. Ineffective anticoagulation was significantly higher among patients with PVT (p < 0.001). The aCL IgM values were significantly higher and positive (> 40 MPL) in the PVT group compared with the control group (10.58 ± 15.90 MPL to 3.70 ± 2.30 MPL, p < 0.001; 7.0 to 0 %, p = 0.016, respectively). The aCL IgG values were significantly higher and positive (> 40 GPL) in the PVT group compared with the control group (12.04 ± 17.58 GPL to 3.83 ± 2.56 GPL, p < 0.001 and 7.9 to 0 %, p = 0.01, respectively). According to international consensus documents, 16 patients had antiphospholipid syndrome. Ineffective anticoagulation and aCL IgM and IgG positivity were independent predictors of PVT in logistic regression analysis (multivariate r(2)= 0.648; p < 0.001, OR= 21.405, 95 %CI= 8.201-55.872; p = 0.008, OR= 1.322, % 95CI= 1.076-1.626; p = 0.005, OR= 1.288, 95 %CI= 1.079-1.538). Since the presence of aCL IgM and IgG positivity may cause a tendency toward PVT, these values should be examined in all patients with PVT.

  15. Valve mechanism lubrication system for an overhead valve engine

    SciTech Connect

    Kronich, P.G.

    1986-07-22

    In an internal combustion engine, including a crankcase, an oil sump, push rods for operating the valves of the engine, a rocker box for housing the valve actuating mechanism, a lubrication system for lubricating the valve actuating mechanism is described which consists of: a first hollow tube for housing a first of the push rods, and first tube having one end open to the crankcase, and an opposite end open to the rocker box, for conducting oil mist from the crankcase to the rocker box to lubricate the valve rocker mechanism; a second hollow tube for housing a second push rod, the second tube having one end open to the rocker box and an opposite end open to a breather chamber for conducting liquid oil and oil mist from the rocker box to the breather chamber, the breather chamber being vented to the atmosphere; an oil drain passage for conducting liquid oil from the breather chamber to the oil sump; and baffle means in the rocker box for causing the oil mist entering the rocker box from the first tube to flow past the valve actuating mechanism for lubrication thereof before flowing from the rocker box into the second tube.

  16. [The assessment of mechanical heart valves stenosis in adults after aortic valve replacement: the advantage of full-flow design of mechanical valve].

    PubMed

    Bokeria, L A; Bokeria, O L; Fadeev, A A; Makhachev, O A; Kosareva, T I; Averina, I I

    2013-01-01

    The analysis of transprosthetic hemodynamics in adults after aortic valve replacement in the Bakoulev Center for Cardiovascular Surgery in 2007-2010 demonstrated the hemodynamic advantage of the concept of new full-flow mechanical aortic valve prosthesis "CorBeat". Having the same size of internal orifice and tissue annulus diameters, the values of transprosthetic parameters (peak and mean gradients, blood flow velocities) through "CorBeat" were close to physiological values of transvalvular native aortic parameters and had a tendency to be not dependent on the size of prosthesis (p = 0.63). In the article for the first time a morphometric database of geometric values of internal orifice area of normal native aortic valves in adults was used taking into account both the gender and the body surface area's of a patient. There was also used the standardized prosthesis size Z-score which represents the number of SDs by which the internal prosthesis area differs from the mean normal native aortic valve area for the patient's body surface area. The article emphasizes the need of the personal selection of the size and the type of prosthesis for any patient as well as the need for new design development of prosthetic heart valves.

  17. Variation in artificial heart acceleration and sound production with prosthetic valve selection in vitro.

    PubMed

    Pantalos, G M; Kim, C H; Flatau, A

    1996-03-01

    In an attempt to explore methods to reduce total artificial heart (TAH) acceleration and sound production, in vitro measurements of TAH acceleration and sound were made when using a variety of prosthetic valves in a test ventricle. A miniature, uniaxial, high fidelity accelerometer was glued to the housing of a UTAH-100 left ventricle adjacent to the inflow and outflow ports and parallel to the axis of diaphragm excursion. A miniature, high fidelity contact microphone was glued to the opposite side of the ventricular housing between the inflow and outflow ports. Data was collected over a range of heart rates, ventricular filling volumes and control modes while using tilting disc valves (TDV) and polymer trileaflet valves (PTV). For both valve types, the peak systolic acceleration impulse was lower (approximately equal to 50%) when the ventricle was fully rather than partially filled and the peak diastolic acceleration impulse was lower (approximately equal to 50%) when the ventricle was fully rather than partially ejected. The magnitude of the acceleration with PTVs was approximately equal to 20x less than the TDVs (0.5 to 2.2 g vs. 10 to 49g). The magnitude of the sound production was also considerably less with the PTVs (28 to 49 db vs. 50 to 64 db). Diastolic acceleration and sound production was approximately twice the systolic value for the TDVs; the reserse was true for PTV sound production. These data demonstrate the substantial reduction in TAH impulse acceleration and sound production by selecting PTVs over TDSs. With PTVs, the TAH impulse acceleration is the same as the natural heart. Consequently, this ability to lower TAH acceleration and sound production to the level of the natural heart may lead to a reduction in component wear, patient discomfort and other undesirable consequences of TAH implantation.

  18. Predictors of In-hospital Adverse Events in Patients with Prosthetic Valve Infective Endocarditis.

    PubMed

    Tan, Hwee-Leong; Chai, Louis Y A; Yeo, Tiong-Cheng; Chia, Boon-Lock; Tambyah, Paul A; Poh, Kian-Keong

    2015-07-01

    We aimed to study patients with prosthetic valve endocarditis (PVE) and analyse factors associated with in-hospital adverse events. A review of all patients who underwent echocardiography at a local university hospital with definite PVE (modified Duke's criteria) was performed. Adverse events of in-hospital mortality and redo valve surgery were identified. There were 23 patients with PVE (median age 53 years (IQR:38-66), 12 males (52%)). Twelve adverse events occurred including seven (30%) in-hospital mortalities and five (21%) redo valve surgery. Factors associated with in-hospital mortality include Staphylococcus aureus-PVE (86% vs 31%, p=0.027), presence of shock (86% vs 19%, p=0.005) and intensive care unit admission (72% vs 19%, p=0.026). Factors associated with the need for redo valve surgery include a younger median age (37 vs 61 years, p=0.012), longer median length of stay (58 vs 17 days, p=0.004), history of intravenous drug abuse (IVDA) (60% vs 6%, p=0.021) and right-sided valvular involvement (40% vs 0%, p=0.040). Using a composite endpoint of both outcomes, factors associated with in-hospital adverse events were a history of IVDA (36% vs 0%, p=0.037) and presence of shock (64% vs 17%, p=0.036). PVE carries a high risk of poor clinical outcome in terms of in-hospital mortality and the need for redo surgery. Copyright © 2015 Australian and New Zealand Society of Cardiac and Thoracic Surgeons (ANZSCTS) and the Cardiac Society of Australia and New Zealand (CSANZ). Published by Elsevier B.V. All rights reserved.

  19. In vivo degradation of silicone rubber poppets in prosthetic heart valves.

    PubMed

    Cuddihy, E F; Moacanin, J; Roschke, E J; Harrison, E C

    1976-05-01

    Dynamic shear modulus G' was measured throughout the volume of three nonvariant silicone rubber poppets which were recovered from aortic prosthetic heart valves that had been implanted for 4 days, 52 days, and 8 years. Similar measurements were obtained for two unused silicone rubber poppets. Although the recovered poppets exhibited no obvious physical evidence of damage, the silicone rubber had undergone in vivo degradation throughout the poppet volume as indicated by decreases in modulus. The measurements also indicate that the poppet surface degrades at a rate faster than the core. Further, comparison with data reported in the literature suggests that the surfaces of variant poppets degrade at a rate faster than the surfaces of nonvariant poppets.

  20. Fibrinolytic therapy in left side-prosthetic valve acute thrombosis. In depth systematic review.

    PubMed

    Reyes-Cerezo, Esteban; Jerjes-Sánchez, Carlos; Archondo-Arce, Tamara; García-Sosa, Anabel; Garza-Ruiz, Angel; Ramírez-Rivera, Alicia; Ibarra-Pérez, Carlos

    2008-01-01

    Limited data are available on the impact and safety of fibrinolytic therapy (FT) in left - side prosthetic valve acute thrombosis (PVAT). To improve our knowledge about the FT role in left -side PVAT. Bibliographic search and analysis. MEDLINE search from January 1970 to January 2007. Studies were classified according to the evidence level recommendations of the American College of Chest Physicians and included if they had objective diagnosis of left-side PAVT and FT efficacy assessment (hemodynamic, echocardiographic or fluoroscopic improvement). New York Heart Association class was used to establish functional state. Data on clinical characteristics, diagnosis strategy, anticoagulation status, fibrinolytic and heparin regimens, cardiovascular adverse events, outcome, and follow-up were also required. A systematic search produced a total of 900 references. Each abstract was analyzed according to the predetermined criteria. Thirty-two references with 904 patients constitute the subject of this analysis. Only one trial had evidence III and thirty-one evidence V. FT was more used in young female patients (64%) with prosthetic mitral valve thrombosis (77%), and clinical instability (82%). Transesophageal echocardiogram had a higher thrombus detection rate (100%). Although several fibrinolytic regimens were used in a first or second course, streptokinase was the most frequent agent (61%). Clinical improvement was observed in 86% of the patients, objective success in 78%, and failure in 14%. Rescue fibrinolysis was done in 17%. peripheral and cerebral embolism rate was 5% and 4%, respectively. Major bleeding 4% and intracranial hemorrhage 1%. The available evidence demonstrates that in PVAT fibrinolytic therapy improves the outcome in younger, more ill patients, especially females, independently of the fibrinolytic regimen used with a low complications rate.

  1. Methods for characterization of mechanical and electrical prosthetic vacuum pumps.

    PubMed

    Komolafe, Oluseeni; Wood, Sean; Caldwell, Ryan; Hansen, Andrew; Fatone, Stefania

    2013-01-01

    Despite increasingly widespread adoption of vacuum-assisted suspension systems in prosthetic clinical practices, there remain gaps in the body of scientific knowledge guiding clinicians' choices of existing products. In this study, we identified important pump-performance metrics and developed techniques to objectively characterize the evacuation performance of prosthetic vacuum pumps. The sensitivity of the proposed techniques was assessed by characterizing the evacuation performance of two electrical (Harmony e-Pulse [Ottobock; Duderstadt, Germany] and LimbLogic VS [Ohio Willow Wood; Mt. Sterling, Ohio]) and three mechanical (Harmony P2, Harmony HD, and Harmony P3 [Ottobock]) prosthetic pumps in bench-top testing. Five fixed volume chambers ranging from 33 cm(3) (2 in.(3)) to 197 cm(3) (12 in.(3)) were used to represent different air volume spaces between a prosthetic socket and a liner-clad residual limb. All measurements were obtained at a vacuum gauge pressure of 57.6 kPa (17 inHg). The proposed techniques demonstrated sensitivity to the different electrical and mechanical pumps and, to a lesser degree, to the different setting adjustments of each pump. The sensitivity was less pronounced for the mechanical pumps, and future improvements for testing of mechanical vacuum pumps were proposed. Overall, this study successfully offers techniques feasible as standards for assessing the evacuation performance of prosthetic vacuum pump devices.

  2. Dynamic tracking of prosthetic valve motion and deformation from bi-plane x-ray views: feasibility study

    NASA Astrophysics Data System (ADS)

    Hatt, Charles R.; Wagner, Martin; Raval, Amish N.; Speidel, Michael A.

    2016-03-01

    Transcatheter aortic valve replacement (TAVR) requires navigation and deployment of a prosthetic valve within the aortic annulus under fluoroscopic guidance. To support improved device visualization in this procedure, this study investigates the feasibility of frame-by-frame 3D reconstruction of a moving and expanding prosthetic valve structure from simultaneous bi-plane x-ray views. In the proposed method, a dynamic 3D model of the valve is used in a 2D/3D registration framework to obtain a reconstruction of the valve. For each frame, valve model parameters describing position, orientation, expansion state, and deformation are iteratively adjusted until forward projections of the model match both bi-plane views. Simulated bi-plane imaging of a valve at different signal-difference-to-noise ratio (SDNR) levels was performed to test the approach. 20 image sequences with 50 frames of valve deployment were simulated at each SDNR. The simulation achieved a target registration error (TRE) of the estimated valve model of 0.93 +/- 2.6 mm (mean +/- S.D.) for the lowest SDNR of 2. For higher SDNRs (5 to 50) a TRE of 0.04 mm +/- 0.23 mm was achieved. A tabletop phantom study was then conducted using a TAVR valve. The dynamic 3D model was constructed from high resolution CT scans and a simple expansion model. TRE was 1.22 +/- 0.35 mm for expansion states varying from undeployed to fully deployed, and for moderate amounts of inter-frame motion. Results indicate that it is feasible to use bi-plane imaging to recover the 3D structure of deformable catheter devices.

  3. Cellular Mechanisms of Aortic Valve Calcification

    PubMed Central

    Leopold, Jane A.

    2012-01-01

    Acquired aortic valve disease and valvular calcification is highly prevalent in adult populations worldwide and is associated with significant cardiovascular morbidity and mortality. At present, there are no medical therapies that will prevent or regress aortic valve calcification or stenosis and surgical or transcatheter aortic valve replacement remain the only effective therapies for treating this disease. In the setting of valve injury as a result of exposure to biochemical mediators or hemodynamic forces, normal homeostatic processes are disrupted resulting in extracellular matrix degradation, aberrant matrix deposition and fibrosis, inflammatory cell infiltration, lipid accumulation, and neoangiogenesis of the valve tissue and, ultimately, calcification of the valve. Calcification of the aortic valve is now understood to be an active process that involves the coordinated actions of resident valve endothelial and interstitial cells, circulating inflammatory and immune cells, and bone marrow-derived cells. These cells may undergo a phenotype transition to become osteoblast-like cells and elaborate bone matrix, endothelial-to-mesenchymal transition, and form matrix vesicles that serve as a nidus for microcalcifications. Each of these mechanisms has been shown to contribute to aortic valve calcification suggesting that strategies that target these cellular events may lead to novel therapeutic interventions to halt the progression or reverse aortic valve calcification. PMID:22896576

  4. Surgery for prosthetic valve endocarditis: associations between morbidity, mortality and costs.

    PubMed

    Grubitzsch, Herko; Christ, Torsten; Melzer, Christoph; Kastrup, Marc; Treskatsch, Sascha; Konertz, Wolfgang

    2016-06-01

    Surgery for prosthetic valve endocarditis (PVE) is associated with significant morbidity and mortality as well as with increased resource utilization and costs. For risk and cost reduction, an understanding of contributing factors and interrelations is essential. Out of 1080 heart valve procedures performed between January 2010 and December 2012, 41 patients underwent surgery for PVE. Complete economic data were available for 30 of them (study cohort). The patients' mean age was 64 ± 12 years (range 37-79 years), and 73% were men. The clinical course was reviewed and morbidity, mortality and costs as well as associations between them were analysed. The cost matrix for each individual patient was obtained from the Institute for the Hospital Remuneration System (InEK GmbH, Germany). The median follow-up was 2.6 years [interquartile range (IQR) 3.7 years; 100% complete]. Preoperative status was critical (EuroSCORE II >20%) in 43% of patients. Staphylococci were the most common infecting micro-organisms (27%). The operative mortality rate (≤30 days) was 17%. At 1 year, the overall survival rate was 71 ± 9%. At least one disease- or surgery-related complication affected 21 patients (early morbidity 70%), >1 complication affected 12 patients (40%). There was neither a recurrence of endocarditis, nor was a reoperation required. The mean total hospital costs were 42.6 ± 37.4 Thousand Euro (T€), median 25.7 T€, IQR 28.4 T€ and >100 T€ in 10% of cases. Intensive care unit/intermediate care (ICU/IMC) and operation accounted for 40.4 ± 18.6 and 25.7 ± 12.1% of costs, respectively. There was a significant correlation (Pearson's sample correlation coefficient) between total costs and duration of hospital stay (r = 0.83, P < 0.001) and between ICU/IMC costs and duration of ICU/IMC stay (r = 0.97, P < 0.001). The median daily hospital costs were 1.8 T€/day, but >2.4 T€/day in 25% of patients (upper quartile). The following pattern of associations was identified

  5. Valve operating mechanism for internal combustion engine

    SciTech Connect

    Inoue, K.; Nagahiro, K.; Ajiki, Y.; Katoh, M.

    1988-12-06

    This patent describes a valve operating mechanism of operating valves of an internal combustion engine, comprising: a camshaft rotatable in synchronism with rotation of the internal combustion engine and having an array of three cams each having a different cam profile and including a high-speed cam position at one end of the array; three cam followers held in sliding contact with the cams, respectively, for operating the valves according to the cam profiles of the cams; and means for selectively interconnecting and disconnecting the cam followers to operate the valves at different valve timings in different speed ranges of the internal combustion engine, the speed ranges including a high-speed range in which all of the valves are controlled by the cam profile of the high-speed cam.

  6. Electro-Mechanical Coaxial Valve

    NASA Technical Reports Server (NTRS)

    Patterson, Paul R (Inventor)

    2004-01-01

    Coaxial valves usually contain only one moving part. It has not been easy, then, to provide for electric motor actuation. Many actuators being proposed involve designs which lead to bulky packages. The key facing those improving coaxial valves is the provision of suitable linear actuation. The valve herein indudes a valve housing with a flow channel there-through. Arranged in the flow channel is a closing body. In alignment with the closing body is a ball screw actuator which includes a ball nut and a cylindrical screw. The ball nut sounds a threaded portion of the cylindrical screw. The cylindrical screw is provided with a passageway there-through through which fluid flows. The cylindrical screw is disposed in the flow channel to become a control tube adapted to move toward and away from the valve seat. To rotate the ball nut an actuating drive is employed driven by a stepper motor.

  7. Haemolysis with Björk-Shiley and Starr-Edwards prosthetic heart valves: a comparative study

    PubMed Central

    Slater, S. D.; Sallam, I. A.; Bain, W. H.; Turner, M. A.; Lawrie, T. D. V.

    1974-01-01

    Slater, S. D., Sallam, I. A., Bain, W. H., Turner, M. A., and Lawrie, T. D. V. (1974).Thorax, 29, 624-632. Haemolysis with Björk-Shiley and Starr-Edwards prosthetic heart valves: a comparative study. A comparison was made of the haemolytic complications in 85 patients with two different types of Starr-Edwards cloth-covered ball and cage prosthesis with those in 44 patients with the Björk-Shiley tilting disc valve. Intravascular haemolysis, as detected by the presence of haemosiderinuria, occurred significantly less often with the Björk-Shiley than with the Starr-Edwards valve, the overall incidence with aortic, mitral or multiple replacements being 31%, 15%, and 20% for Björk-Shiley and 94%, 92%, and 88% for Starr-Edwards valves respectively. There was no significant difference in the frequency of haemolysis between each of the two types of Starr-Edwards prosthesis studied at either the aortic (2300 versus 2310 model) or mitral (6300 versus 6310) site. Haemolytic anaemia developed in only one patient with a Björk-Shiley valve but was common though usually mild with Starr-Edwards prostheses, particularly aortic valve replacements with the 2300 model and in aortic plus mitral (± tricuspid) replacements. The greater severity of haemolysis produced by Starr-Edwards valves, again especially of the latter types, was further demonstrated by higher serum lactate dehydrogenase and 24-hour urinary iron levels. It is concluded that the Björk-Shiley tilting disc valve represents a significant advance in the amelioration of the haemolytic complications of prosthetic valves. PMID:4450173

  8. Long term follow up of prosthetic valve endocarditis: what characteristics identify patients who were treated successfully with antibiotics alone?

    PubMed Central

    Truninger, K; Jost, C; Seifert, B; Vogt, P; Follath, F; Schaffner, A; Jenni, R

    1999-01-01

    OBJECTIVE—To identify predictors for the safe use of antibiotic treatment without reoperation in patients with prosthetic valve endocarditis.
SETTING—Retrospective study in a tertiary care centre.
SUBJECTS AND DESIGN—All 49 episodes of definite prosthetic valve endocarditis (Duke criteria) diagnosed at one institution between 1980 to 1997 were analysed. Ten episodes (20%) were treated with antibiotics only (antibiotic group) and 39 episodes (80%) with combined antibiotic and surgical treatment (surgery group). The analysis included detailed study of hospital records and data on long term follow up which were obtained in all patients by a questionnaire or telephone contact with physician or patient. The length of follow up (mean (SD)) was 41 (32) months in the antibiotic group and 45 (24) months in the surgery group (NS). Long term survival was estimated by the Kaplan-Meier method and compared by the log-rank test.
RESULTS—There was no significant difference in age, history of previous endocarditis, number of previous heart operations, vegetations, emboli, type of prosthesis, or percentage of early prosthetic valve endocarditis and positive blood cultures between the two groups. In the antibiotic group, there were more enterococcal (50%; p = 0.005) and in the surgery group more staphylococcal infections (55%; p = 0.048). Annular abscesses (p < 0.0001) and aortoventricular dehiscence (p = 0.02) were more common in the surgery group. No patient in the antibiotic group had heart failure. Long term follow up showed no significant difference between the surgery and antibiotic groups regarding late mortality (14% v 18%) and five year rates of recurrent endocarditis (14% v 16%), event related mortality (14% v 3%, log-rank test), and the need for reoperation (14% v 19%; log-rank test). The only patient with conservatively treated staphylococcal prosthetic valve endocarditis died after reoperation for recurrence

  9. Brucella-mediated prosthetic valve endocarditis with brachial artery mycotic aneurysm.

    PubMed

    Cakalagaoglu, C; Keser, N; Alhan, C

    1999-09-01

    A 39-year-old female with a Hall-Kaster mitral prosthesis developed fever, general malaise and arthralgia 15 years after valve replacement for rheumatic mitral valve disease. Prosthetic valve endocarditis was identified after serial laboratory, clinical and echocardiographic examinations. Penicillin G (40 x 106 units/day, i.v.) + gentamicin (240 mg/day, i.v.) was started as initial therapy. The patient showed no signs of recovery, and penicillin G was replaced with vancomycin (1,000 mg/day, i.v.). There was a gradual reduction in spiking fever, and prominent reductions in erythrocyte sedimentation rate and white cell count. Meanwhile, a tender and pulsatile mass developed in the anterior surface of the left arm; peripheral angiography yielded a diagnosis of brachial artery aneurysm. A successful aneurysmectomy with saphenous vein interposition was performed. Histopathology of the lesion revealed mycotic aneurysm. An initial control SAT for Brucella of 1/80(+) was found to increase. A detailed history showed the patient to have consumed unpasteurized dairy products. Doxycyline (200 mg/day, oral) + co-trimoxazole (2,700 mg/day, oral) + rifampicin (600 mg/day, oral) was administered to treat brucellosis. Later, doxycyline caused intolerable gastrointestinal side effects and was replaced by ciprofloxacin (1,000 mg/day, oral). Subsequently, the patient made an uneventful recovery within one week. Antibiotic treatment was continued for 12 months, with complete resolution of vegetation and paravalvular leakage. During a four-year follow up, the patient showed no signs of relapse.

  10. Management of patients with prosthetic heart valves during non-cardiac surgery.

    PubMed

    Prendergast, Bernard D

    2004-01-01

    Non-cardiac surgery in patients with prosthetic heart valves poses the particular hazards of infective endocarditis, increased bleeding risk and the possibility of acute/subacute valve thrombosis or systemic thromboembolism associated with interrupted anticoagulation. Management is complicated by the absence of randomised trials examining peri-operative anticoagulation management. Thromboembolic risk increases substantially when oral anticoagulation is discontinued and valve thrombosis may be inapparent for 1-2 months. This delayed diagnosis makes it difficult to identify the inciting event, either clinically or in experimental trials. Furthermore, the absence of early post-operative events may falsely suggest that peri-operative anticoagulation was safe and adequate. The approach to management therefore remains controversial. Seamless oral anticoagulation is preferred whenever possible and this is safe for a range of minor procedures, including cardiac catheterisation, dental and ophthalmic surgery. Major surgical procedures require withdrawal of oral anticoagulation before surgery to lower the international normalised ratio (INR) to <1.5 and maintained anticoagulation with unfractionated heparin which should be started when the INR is <2.5 in high risk patients and <2.0 in those at lower risk. The evidence to support the safety of low molecular weight heparins in this situation is scanty and despite its widespread promulgation this approach is NOT recommended. Oral anticoagulation is then resumed post-operatively, though therapeutic levels are not achieved for several days. The determination of which patients require prolonged overlap of heparin and oral anticoagulants is difficult. Clinical judgement is required but these regimes are strongly recommended for those at highest risk of thromboembolism. With strict adherence to these guidelines, the incidence of major complications is low.

  11. Mitral valve disease—morphology and mechanisms

    PubMed Central

    Levine, Robert A.; Hagége, Albert A.; Judge, Daniel P.; Padala, Muralidhar; Dal-Bianco, Jacob P.; Aikawa, Elena; Beaudoin, Jonathan; Bischoff, Joyce; Bouatia-Naji, Nabila; Bruneval, Patrick; Butcher, Jonathan T.; Carpentier, Alain; Chaput, Miguel; Chester, Adrian H.; Clusel, Catherine; Delling, Francesca N.; Dietz, Harry C.; Dina, Christian; Durst, Ronen; Fernandez-Friera, Leticia; Handschumacher, Mark D.; Jensen, Morten O.; Jeunemaitre, Xavier P.; Le Marec, Hervé; Le Tourneau, Thierry; Markwald, Roger R.; Mérot, Jean; Messas, Emmanuel; Milan, David P.; Neri, Tui; Norris, Russell A.; Peal, David; Perrocheau, Maelle; Probst, Vincent; Pucéat, Michael; Rosenthal, Nadia; Solis, Jorge; Schott, Jean-Jacques; Schwammenthal, Ehud; Slaugenhaupt, Susan A.; Song, Jae-Kwan; Yacoub, Magdi H.

    2016-01-01

    Mitral valve disease is a frequent cause of heart failure and death. Emerging evidence indicates that the mitral valve is not a passive structure, but—even in adult life—remains dynamic and accessible for treatment. This concept motivates efforts to reduce the clinical progression of mitral valve disease through early detection and modification of underlying mechanisms. Discoveries of genetic mutations causing mitral valve elongation and prolapse have revealed that growth factor signalling and cell migration pathways are regulated by structural molecules in ways that can be modified to limit progression from developmental defects to valve degeneration with clinical complications. Mitral valve enlargement can determine left ventricular outflow tract obstruction in hypertrophic cardiomyopathy, and might be stimulated by potentially modifiable biological valvular–ventricular interactions. Mitral valve plasticity also allows adaptive growth in response to ventricular remodelling. However, adverse cellular and mechanobiological processes create relative leaflet deficiency in the ischaemic setting, leading to mitral regurgitation with increased heart failure and mortality. Our approach, which bridges clinicians and basic scientists, enables the correlation of observed disease with cellular and molecular mechanisms, leading to the discovery of new opportunities for improving the natural history of mitral valve disease. PMID:26483167

  12. Mitral valve disease--morphology and mechanisms.

    PubMed

    Levine, Robert A; Hagége, Albert A; Judge, Daniel P; Padala, Muralidhar; Dal-Bianco, Jacob P; Aikawa, Elena; Beaudoin, Jonathan; Bischoff, Joyce; Bouatia-Naji, Nabila; Bruneval, Patrick; Butcher, Jonathan T; Carpentier, Alain; Chaput, Miguel; Chester, Adrian H; Clusel, Catherine; Delling, Francesca N; Dietz, Harry C; Dina, Christian; Durst, Ronen; Fernandez-Friera, Leticia; Handschumacher, Mark D; Jensen, Morten O; Jeunemaitre, Xavier P; Le Marec, Hervé; Le Tourneau, Thierry; Markwald, Roger R; Mérot, Jean; Messas, Emmanuel; Milan, David P; Neri, Tui; Norris, Russell A; Peal, David; Perrocheau, Maelle; Probst, Vincent; Pucéat, Michael; Rosenthal, Nadia; Solis, Jorge; Schott, Jean-Jacques; Schwammenthal, Ehud; Slaugenhaupt, Susan A; Song, Jae-Kwan; Yacoub, Magdi H

    2015-12-01

    Mitral valve disease is a frequent cause of heart failure and death. Emerging evidence indicates that the mitral valve is not a passive structure, but--even in adult life--remains dynamic and accessible for treatment. This concept motivates efforts to reduce the clinical progression of mitral valve disease through early detection and modification of underlying mechanisms. Discoveries of genetic mutations causing mitral valve elongation and prolapse have revealed that growth factor signalling and cell migration pathways are regulated by structural molecules in ways that can be modified to limit progression from developmental defects to valve degeneration with clinical complications. Mitral valve enlargement can determine left ventricular outflow tract obstruction in hypertrophic cardiomyopathy, and might be stimulated by potentially modifiable biological valvular-ventricular interactions. Mitral valve plasticity also allows adaptive growth in response to ventricular remodelling. However, adverse cellular and mechanobiological processes create relative leaflet deficiency in the ischaemic setting, leading to mitral regurgitation with increased heart failure and mortality. Our approach, which bridges clinicians and basic scientists, enables the correlation of observed disease with cellular and molecular mechanisms, leading to the discovery of new opportunities for improving the natural history of mitral valve disease.

  13. [Right-sided prosthetic cardiac valve thrombosis: value of cinefluoroscopy in the diagnosis and follow-up of thrombolytic treatment].

    PubMed

    Hobbach, H-P; Mall, K; Schaeffer, C; Schuster, P

    2009-10-01

    A 33-year-old woman (Pt. A) with a prosthetic cardiac valve in the pulmonary position [CarboMedics bileaflet valve, diameter 23 mm] as part of the repair of a tetralogy of Fallot 4 years previously, and a 51-year-old woman (Pt. B) with a prosthetic cardiac valve [St. Jude Medical bileaflet valve, diameter 31 mm] inserted in tricuspid position as replacement of a degenerated Hancock bioprosthetic valve inserted 15 years previously, 10 years after an episode of endocarditis, were admitted to hospital with dyspnea and chest pain and dyspnea and tachycardia, respectively. Pt. A had a 3 - 4/6 crescendo-decrescendo systolic murmur and a 2/6 early diastolic decrescendo murmur over the 2nd to 4th right intercostal space (ICS), while Pt. B had a 3/6 holosystolic murmur and a 2 - 3/6 diastolic murmur over the 4th right ICS. Closing click was missing in both patients. Blood tests demonstrated an elevated LDH (404 U/l) in Pt. A and an elevated GGT (108 U/l) and fibrinogen (449 mg/dl) in Pt. B. Anticoagulation was below the therapeutic level, with an INR value of 1,65 and 1,93, respectively. The electrocardiogram showed sinus rhythm, right bundle branch block and an isoelectric ST-segment (Pt. A) and a typical high-frequency atrial flutter with a 2:1 block, right bundle branch block and terminal T-wave inversions in leads V1 to V5 (Pt. B). Cinefluoroscopy showed rigid and hypomobile leaflets as a result of prosthetic cardiac valve thrombosis. Doppler echocardiography confirmed the stenosis of the prosthetic valve in the pulmonary position (peak gradient 73 mm Hg, mean gradient 34 mm Hg) and the tricuspid position (mean gradient 8.48 mm Hg, peak gradient 16.73 mm Hg). Both patients were treated with unfractionated heparin and urokinase single-bolus injection of 4400 U/kg over 10 min followed by an infusion of 4400 U/kg/h over 12 h. Both patients had an abnormal opening angle, which improved to a normal opening and closing angle. Doppler echocardiography demonstrated decreased

  14. Prospective ECG triggering reduces prosthetic heart valve-induced artefacts compared with retrospective ECG gating on 256-slice CT.

    PubMed

    Symersky, Petr; Habets, Jesse; Westers, Paul; de Mol, Bas A J M; Prokop, Mathias; Budde, Ricardo P J

    2012-06-01

    Multidetector computed tomography (MDCT) has diagnostic value for the evaluation of prosthetic heart valve (PHV) dysfunction but it is hampered by artefacts. We hypothesised that image acquisition using prospective triggering instead of retrospective gating would reduce artefacts related to pulsating PHV. In a pulsatile in vitro model, a mono- and bileaflet PHV were imaged using 256 MDCT at 60, 75 and 90 beats per minute (BPM) with either retrospective gating (120 kV, 600 mAs, pitch 0.2, CTDI(vol) 39.8 mGy) or prospective triggering (120 kV, 200 mAs, CTDI(vol) 13.3 mGy). Two thresholds (>175 and <-45HU), derived from the density of surrounding structures, were used for quantification of hyper- and hypodense artefacts. Image noise and artefacts were compared between protocols. Prospective triggering reduced hyperdense artefacts for both valves at every BPM (P = 0.001 all comparisons). Hypodense artefacts were reduced for the monoleaflet valve at 60 (P = 0.009), 75 (P = 0.016) and 90 BPM (P = 0.001), and for the bileaflet valves at 60 (P = 0.001), 90 (P = 0.001) but not at 75 BPM (P = 0.6). Prospective triggering reduced image noise at 60 (P = 0.001) and 75 (P < 0.03) but not at 90 BPM. Compared with retrospective gating, prospective triggering reduced most artefacts related to pulsating PHV in vitro. • Computed tomographic images are often degraded by prosthetic heart valve-induced artefacts • Prospective triggering reduces prosthetic heart valve-induced artefacts in vitro • Artefact reduction at 90 beats per minute occurs without image noise reduction • Prospective triggering may improve CT image quality of moving hyperdense structures.

  15. Posterior thoracic echocardiography for assessment of native and prosthetic aortic valves in the presence of pleural effusion.

    PubMed

    Lee, Ming-Sum; Naqvi, Tasneem Z

    2014-04-01

    Many patients with aortic stenosis have difficult imaging windows due to advanced age, kyphosis, prior chest surgeries, radiation-induced skin changes, or hyperinflated lungs from pulmonary disease. Here we describe 4 cases to illustrate that in a subset of patients with pleural effusion, a posterior imaging approach can be used to obtain diagnostic images for native and prosthetic aortic valves. In these cases, nondiagnostic transthoracic echocardiographic images were obtained from conventional imaging windows, leading to inaccurate or incomplete assessment of the aortic valve. In all cases, images obtained from a posterior thoracic approach provided important additional diagnostic information.

  16. Valve operating mechanism for internal combustion engine

    SciTech Connect

    Fujii, N.; Iwata, T.; Takahara, N.

    1988-12-27

    This patent describes a valve operating mechanism in an internal combustion engine comprising: a single camshaft rotatably disposed above the cylinder head, a single rocker arm shaft rotatably disposed above the cylinder head; an intake-valve rocker arm swingably supported on the rocker arm shaft and operatively engaging the intake valve; an exhaust-valve rocker arm swingably supported on the rocker arm shaft and operatively engaging the exhaust valve, a camshaft holder disposed above the cylinder bore, the camshaft being rotatably supported by the camshaft holder; a rocker arms shaft holder disposed above the cylinder bore, the rocker arm shaft being rotatably supported by the rocker arm shaft holder; and a plug insertion tube having a plug insertion hole for insertion of the spark plug therethrough, the plug insertion tube being integrally formed with the camshaft holder and the rocker arm shaft holder in a holder block means.

  17. Usefulness of live/real time three-dimensional transthoracic echocardiography in evaluation of prosthetic valve function.

    PubMed

    Singh, Preeti; Inamdar, Vatsal; Hage, Fadi G; Kodali, Visali; Karakus, Gultekin; Suwanjutah, Thouantosaporn; Hsiung, Ming C; Nanda, Navin C

    2009-11-01

    We studied 31 patients with prosthetic valves (PVs) using two-dimensional and three-dimensional transthorathic echocardiography (2DTTE and 3DTTE, respectively) in order to determine whether 3DTTE provides an incremental value on top of 2DTTE in the evaluation of these patients. With 3DTTE both leaflets of the St. Jude mechanical PV can be visualized simultaneously, thereby increasing the diagnostic confidence in excluding valvular abnormalities and overcoming the well-known limitations of 2DTTE in the examination of PVs, which heavily relies on Doppler. Three-dimensional transthorathic echocardiography provides a more comprehensive evaluation of PV regurgitation than 2DTTE with its ability to more precisely quantify PV regurgitation, in determining the mechanism causing regurgitation, and in localizing the regurgitant defect. Furthermore, 3DTTE is superior in identifying, quantifying, and localizing PV thrombi and vegetations, in addition to the unique feature of providing a look inside mass lesions by serial sectioning. These preliminary results suggest the superiority of 3DTTE over 2DTTE in the evaluation of PVs and that it provides incremental knowledge to the echocardiographer.

  18. Risk Factors for Prosthetic Pulmonary Valve Failure in Patients With Congenital Heart Disease.

    PubMed

    Oliver, Jose Maria; Garcia-Hamilton, Diego; Gonzalez, Ana Elvira; Ruiz-Cantador, Jose; Sanchez-Recalde, Angel; Polo, Maria Luz; Aroca, Angel

    2015-10-15

    The incidence and risk factors for prosthetic pulmonary valve failure (PPVF) should be considered when determining optimal timing for pulmonary valve replacement (PVR) in asymptomatic patients with congenital heart disease (CHD). The cumulative freedom for reintervention due to PPVF after 146 PVR in 114 patients with CHD was analyzed. Six potential risk factors (underlying cardiac defect, history of palliative procedures, number of previous cardiac interventions, hemodynamic indication for PVR, type of intervention, and age at intervention) were analyzed using Cox proportional hazard modeling. Receiver operating characteristic (ROC) curves were used for discrimination. Internal validation in patients with tetralogy of Fallot was also performed. Median age at intervention was 23 years. There were 60 reinterventions due to PPVF (41%). Median event-free survival was 14 years (95% confidence interval [CI] 12 to 16 years). The only independent risk factor was the age at intervention (hazard ratio [HR] 0.93, 95% CI 0.90 to 0.97; p = 0.001; area under the ROC curve 0.95, 95% CI 0.92 to 0.98; p <0.001). The best cut-off point was 20.5 years. Freedom from reintervention for PPVF 15 years after surgery was 70% when it was performed at age >20.5 years compared with 33% when age at intervention was <20.5 years (p = 0.004). Internal validation in 102 PVR in patient cohort with tetralogy of Fallot (ROC area 0.98, 95% CI 0.96 to 1.0; p <0.001) was excellent. In conclusion, age at intervention is the main risk factor of reintervention for PPVF. The risk of reintervention is 2-fold when PVR is performed before the age of 20.5 years.

  19. Cost of vitamin K antagonist anticoagulant treatment in patients with metallic prosthetic valve in mitral position

    PubMed Central

    Ene, Gabriela; Garcia Raso, Aránzazu; Gonzalez-Dominguez Weber, Almudena; Hidalgo-Vega, Álvaro; Llamas, Pilar

    2016-01-01

    Background: The initiation of oral anticoagulation therapy after valve replacement surgery requires strict monitoring because these patients are at high risk for the development of thrombotic complications and present an increased risk of bleeding. Objectives: The aim of this study was to examine the total healthcare costs of oral anticoagulant treatment with vitamin K antagonists in patients with metallic prosthetic valves in the mitral position. Methods: Data from clinical records were used in the study including international normalized ratio results, number of medical visits, type of anticoagulant, use of rescue medication and hospital admissions from related complications. The drug cost was calculated based on the official Spanish Ministry of Health price list. Monitoring expenses were included in the cost of the medical supplies used in the procedures. Hospitalization costs were calculated using the diagnosis-related group price for each case. Results: We collected data from 151 patients receiving oral anticoagulation therapy with vitamin K antagonist who were diagnosed with mitral prosthesis (n = 90), mitro-aortic prosthesis (n = 57), and mitral and tricuspid prosthesis (n = 4). The total direct healthcare cost was €15302.59, with a mean total cost per patient per year of €1558.15 (±2774.58) consisting of 44.38 (±42.30) for drug cost, €71.41 (±21.43) for international normalized ratio monitoring, €429.52 (±126.87) for medical visits, €26.31 (±28.38) for rescue medication and €986.53 (±2735.68) for related complications. Conclusion: Most direct healthcare costs associated with the sampled patients arose from the specialist-care monitoring required for treatment. Good monitoring is inversely related to direct healthcare costs. PMID:27579168

  20. CardiaMed mechanical valve: mid-term results of a multicenter clinical trial.

    PubMed

    Nazarov, Vladimir M; Zheleznev, Sergey I; Bogachev-Prokophiev, Alexandr V; Afanasyev, Alexandr V; Nemchenko, Eugene V; Jeltovskiy, Yuri V; Lavinyukov, Sergey O

    2014-01-01

    Prosthesis choice is a major concern in valvular surgery. A multicenter clinical trial was performed to assess the efficacy and safety of the CardiaMed prosthetic heart valve. The study enrolled 420 patients who underwent mitral (209) or aortic (211) valve replacement from 2003 to 2004 at 7 institutions in Russia, and who were followed up from 2006 to 2011. The mean age was 52.2 ± 10.2 years (range, 12-78 years), 47.4% were female, and 99.05% completed the study. The maximum observation term was 7.5 years (2188.5 patient-years); 1081.6 patient-years for aortic and 1106.9 patient-years for mitral valve replacement. The overall 7-year survival rate was 85.1%  ± 3.7%; 86.1%  ± 4.8% and 84.4%  ± 5.4% for aortic and mitral valve replacement, respectively. The 7-year freedom from valve-related death was 93.9%  ± 3.7% and 94.5%  ± 3.2% for aortic and mitral valve replacement, respectively. When early mortality (<30 days) was excluded, these rates were 94.8%  ± 3.1% and 93.8%  ± 3.82%, respectively. Linearized valve-dependent complication rates were determined for structural valve failure (0%/patient-year overall), thrombosis (0.63%/patient-year, all for mitral valve replacement), thromboembolic complications including transient neurologic deficits (0.13%/patient-year overall, 0.5%/patient-year for aortic valve replacement, 0.8%/patient-year for mitral valve replacement), hemorrhagic bleeding (0.64%/patient-year overall, 0.55%/patient-year for aortic valve replacement, 0.09%/patient-year for mitral valve replacement), prosthetic endocarditis (0.28%/patient-year overall, 0.28%/patient-year for aortic valve replacement, 0%/patient-year for mitral valve replacement), and hemolysis (0%/patient-year overall). The CardiaMed mechanical heart valve prostheses meets world standards of safety and efficacy.

  1. Valve mechanisms for at least two simultaneously actuable valves

    SciTech Connect

    Heimburg, F.

    1989-02-21

    This patent describes a valve gear for at least two valves of an internal combustion engine to be operated simultaneously on longitudinal axes, wherein the valve gear comprises a thrust device which is common to all valves and displaceable on an axis by a cam shaft and against which the valves abut by their valve stems to that displacement of the thrust device causes corresponding displacement of the valves, characterized in that the camshaft includes a single cam that is seated on the thrust device eccentrically relative to its axis causing rotation of the thrust device about its axis. When the thrust device is displaced, the thrust device is axially symmetrical, and the valve stems each abut against the thrust device at positions centered on points offset from the longitudinal axes of the valves causing rotation of the valves about their longitudinal axis when the valves are displaced.

  2. Role of radionuclide imaging for diagnosis of device and prosthetic valve infections.

    PubMed

    Sarrazin, Jean-François; Philippon, François; Trottier, Mikaël; Tessier, Michel

    2016-09-26

    Cardiovascular implantable electronic device (CIED) infection and prosthetic valve endocarditis (PVE) remain a diagnostic challenge. Cardiac imaging plays an important role in the diagnosis and management of patients with CIED infection or PVE. Over the past few years, cardiac radionuclide imaging has gained a key role in the diagnosis of these patients, and in assessing the need for surgery, mainly in the most difficult cases. Both (18)F-fluorodeoxyglucose positron emission tomography/computed tomography ((18)F-FDG PET/CT) and radiolabelled white blood cell single-photon emission computed tomography/computed tomography (WBC SPECT/CT) have been studied in these situations. In their 2015 guidelines for the management of infective endocarditis, the European Society of Cardiology incorporated cardiac nuclear imaging as part of their diagnostic algorithm for PVE, but not CIED infection since the data were judged insufficient at the moment. This article reviews the actual knowledge and recent studies on the use of (18)F-FDG PET/CT and WBC SPECT/CT in the context of CIED infection and PVE, and describes the technical aspects of cardiac radionuclide imaging. It also discusses their accepted and potential indications for the diagnosis and management of CIED infection and PVE, the limitations of these tests, and potential areas of future research.

  3. Role of radionuclide imaging for diagnosis of device and prosthetic valve infections

    PubMed Central

    Sarrazin, Jean-François; Philippon, François; Trottier, Mikaël; Tessier, Michel

    2016-01-01

    Cardiovascular implantable electronic device (CIED) infection and prosthetic valve endocarditis (PVE) remain a diagnostic challenge. Cardiac imaging plays an important role in the diagnosis and management of patients with CIED infection or PVE. Over the past few years, cardiac radionuclide imaging has gained a key role in the diagnosis of these patients, and in assessing the need for surgery, mainly in the most difficult cases. Both 18F-fluorodeoxyglucose positron emission tomography/computed tomography (18F-FDG PET/CT) and radiolabelled white blood cell single-photon emission computed tomography/computed tomography (WBC SPECT/CT) have been studied in these situations. In their 2015 guidelines for the management of infective endocarditis, the European Society of Cardiology incorporated cardiac nuclear imaging as part of their diagnostic algorithm for PVE, but not CIED infection since the data were judged insufficient at the moment. This article reviews the actual knowledge and recent studies on the use of 18F-FDG PET/CT and WBC SPECT/CT in the context of CIED infection and PVE, and describes the technical aspects of cardiac radionuclide imaging. It also discusses their accepted and potential indications for the diagnosis and management of CIED infection and PVE, the limitations of these tests, and potential areas of future research. PMID:27721936

  4. Does positron emission tomography/computed tomography aid the diagnosis of prosthetic valve infective endocarditis?

    PubMed

    Balmforth, Damian; Chacko, Jacob; Uppal, Rakesh

    2016-10-01

    A best evidence topic was constructed according to a structured protocol. The question addressed was whether (18)F-fluorodeoxyglucose positron emission tomography/computed tomography (PET/CT) aids the diagnosis of prosthetic valve endocarditis (PVE)? A total of 107 publications were found using the reported search, of which 6 represented the best evidence to answer the clinical question. The authors, journal, date and country of publication, patient group studied, study type, relevant outcomes and results of these papers are tabulated. The reported outcome of all studies was a final diagnosis of confirmed endocarditis on follow-up. All the six studies were non-randomized, single-centre, observational studies and thus represented level 3 evidence. The diagnostic capability of PET/CT for PVE was compared with that of the modified Duke Criteria and echocardiography, and reported in terms of sensitivity, specificity and positive and negative predictive values. All studies demonstrated an increased sensitivity for the diagnosis of PVE when PET/CT was combined with the modified Duke Criteria on admission. A higher SUVmax on PET was found to be significantly associated with a confirmed diagnosis of endocarditis and an additional diagnostic benefit of PET/CT angiography over conventional PET/non-enhanced CT is reported due to improved anatomical resolution. However, PET/CT was found to be unreliable in the early postoperative period due to its inability to distinguish between infection and residual postoperative inflammatory changes. PET/CT was also found to be poor at diagnosing cases of native valve endocarditis. We conclude that PET/CT aids in the diagnosis of PVE when combined with the modified Duke Criteria on admission by increasing the diagnostic sensitivity. The diagnostic ability of PET/CT can be potentiated by the use of PET/CTA; however, its use may be unreliable in the early postoperative period or in native valve endocarditis. © The Author 2016. Published by

  5. Mechanical haemolytic anaemia after valve repair operations for non-rheumatic mitral regurgitation.

    PubMed Central

    Warnes, C; Honey, M; Brooks, N; Davies, J; Gorman, A; Parker, N

    1980-01-01

    Two cases are described in which severe mechanical haemolytic anaemia developed shortly after operation for repair of non-rheumatic mitral regurgitation. One patient had a "floppy" valve and the other cleft mitral leaflets, and both had chordal rupture. In both there was residual regurgitation after repair though in one this was initially only trivial. Clinically manifest haemolysis ceased after replacement of the valve by a frame-mounted xenograft. There are two previously reported cases in which haemolytic anaemia followed an unsuccessful mitral valve repair operation. Subclinical haemolysis or mild haemolytic anaemia may occur with unoperated valve lesions, but hitherto frank haemolytic anaemia has been observed only when turbulent blood flow is associated with the presence of a prosthetic valve or patch of prosthetic fabric. In these four cases, however, polyester or Teflon sutures were the only foreign material, and it is suggested that when these are used for the repair of leaflets, particularly in non-rheumatic mitral valve disease, they may increase the damaging effect of turbulence on circulating red blood cells. PMID:7426198

  6. A computerized physiologic pulse duplicator for in-vitro hydrodynamic and ultrasonic studies of prosthetic heart valves.

    PubMed

    Arabia, F A; Talbot, T L; Stewart, S F; Nast, E P; Clark, R E

    1989-01-01

    A physiologic pulse duplicator for the simultaneous in-vitro hydrodynamic and ultrasonic evaluation of aortic prosthetic heart valves is described. The system is interfaced to a personal computer, which provides greater efficiency over manual techniques in system calibration, data acquisition, and analysis. The data analysis program aids selection of start and end systole and calculates pressure difference across the valve, the closing and regurgitant volumes, flow rates, and the Gabbay and Swanson performance indices. The pulse duplicator is designed to accommodate the ultrasonic measurement of fluid velocities, including pressure difference via the Bernoulli equation, and color-flow imaging. In tests of 19-mm, 23-mm, and 27-mm Bjork-Shiley spherical occluder valves, continuous-wave Doppler ultrasound was found to overestimate by about 50% the pressure difference measured directly by pressure transducers, a finding that is clinically important.

  7. Validation of a numerical 3-D fluid-structure interaction model for a prosthetic valve based on experimental PIV measurements.

    PubMed

    Guivier-Curien, Carine; Deplano, Valérie; Bertrand, Eric

    2009-10-01

    A numerical 3-D fluid-structure interaction (FSI) model of a prosthetic aortic valve was developed, based on a commercial computational fluid dynamics (CFD) software program using an Arbitrary Eulerian Lagrangian (ALE) formulation. To make sure of the validity of this numerical model, an equivalent experimental model accounting for both the geometrical features and the hydrodynamic conditions was also developed. The leaflet and the flow behaviours around the bileaflet valve were investigated numerically and experimentally by performing particle image velocimetry (PIV) measurements. Through quantitative and qualitative comparisons, it was shown that the leaflet behaviour and the velocity fields were similar in both models. The present study allows the validation of a fully coupled 3-D FSI numerical model. The promising numerical tool could be therefore used to investigate clinical issues involving the aortic valve.

  8. Cavitation dynamics of mechanical heart valve prostheses.

    PubMed

    Lee, C S; Chandran, K B; Chen, L D

    1994-10-01

    Nine different mechanical mitral heart valves were chosen in order to study cavitation dynamics in detail in an in vitro flow system simulating a single event of mitral valve closure. The transvalvular pressure (ventricular minus atrial pressure) rise rate averaged during the valve closing period was used as an index of the loading rate. A series of photographs in the vicinity of the inflow surface of the valve were attempted during the bubble appearance period using a stroboscopic visualization technique. The in vitro study revealed three sources of cavitation initiation in the design of the mechanical heart valves tested: stop (seat stop or seating lip), inflow strut, and clearance (gap formed between the occluder and the housing or between the two occluders in the closed position). Among these, the occluder stop design was the most critical to cavitation since all valves having the stop at the edge of the major orifice area showed a higher intensity of cavitation and threshold loading rates below the estimated normal physiological value. The analysis of bubble locations and dynamics led us to propose that the fluid squeezing effect between the occluder and the stop in the housing and the streamline contraction effect along the clearance are factors responsible for cavitation incipience.

  9. A laboratory investigation of the flow in the left ventricle of a human heart with prosthetic, tilting-disk valves

    NASA Astrophysics Data System (ADS)

    Cenedese, A.; del Prete, Z.; Miozzi, M.; Querzoli, G.

    2005-08-01

    The understanding of the phenomena involved in ventricular flow is becoming more and more important because of two main reasons: the continuous improvements in the field of diagnostic techniques and the increasing popularity of prosthetic devices. On one hand, more accurate investigation techniques gives the chance to better diagnose diseases before they become dangerous to the health of the patient. On the other hand, the diffusion of prosthetic devices requires very detailed assessment of the modifications that they introduce in the functioning of the heart. The present work is focussed on the experimental investigation of the flow in the left ventricle of the human heart with the presence of a tilting-disk valve in the mitral position, as this kind of valve is known to change deeply the structure of such a flow. A laboratory model has been built up, which consists of a cavity able to change its volume, representing the ventricle, on which two prosthetic valves are mounted. The facility is designed to be able to reproduce any arbitrarily assigned law of variation of the ventricular volume with time. In the present experiment, a physiologically shaped curve has been used. Velocity was measured using a feature-tracking (FT) algorithm; as a consequence, the particle trajectories are known. The flow has been studied by changing both the beat rate and the stroke volume. The flow was studied both kinematically, examining velocity and vorticity fields, and dynamically, evaluating turbulent and viscous shear stresses, and inertial forces exerted on fluid elements. The analysis of the results allows the identification of the main features of the ventricular flow, generated by a mitral, tilting-disk valve, during the whole cardiac cycle and its dependence on the frequency and the stroke volume.

  10. Crossed four-bar mechanism for improved prosthetic grasp.

    PubMed

    Ramirez, Issa A; Lusk, Craig P; Dubey, Rajiv; Highsmith, M Jason; Maitland, Murray E

    2009-01-01

    Passive linkages were developed to improve grasp functionality and minimize a prosthetic terminal device's number of user-controlled inputs. The linkages act to stabilize grasped objects and substitute for the palp of normal anatomical fingers. The Southampton Hand Assessment Procedure was used to compare the normal anatomical hand, this prototype, and a commercially available (Hosmer) hook. In testing, prosthetic terminal devices took three times as long as the normal anatomical hand to perform tasks. Nevertheless, heavyweight power and spherical grasps were improved with the use of the new mechanism compared with the commercial hook. Conversely, precision grasps were worsened because of the lack of a high-friction surface on the distal end of the prototype.

  11. The additional value of three-dimensional transesophageal echocardiography in complex aortic prosthetic heart valve endocarditis.

    PubMed

    Tanis, Wilco; Teske, Arco J; van Herwerden, Lex A; Chamuleau, Steven; Meijboom, Folkert; Budde, Ricardo P J; Cramer, Maarten-Jan

    2015-01-01

    Two-dimensional transthoracic and transesophageal echocardiography (2DTTE and 2DTEE) may fail to detect signs of prosthetic heart valve (PHV) endocarditis due to acoustic shadowing. Three-dimensional (3D) TEE may have additional value; however, data are scarce. This study was performed to investigate the additional value of 3DTEE for the detection of aortic PHV endocarditis and the extent of the disease process. Retrospective analysis of complex aortic PHV endocarditis cases that underwent 2DTTE, 2DTEE, and 3DTEE before surgery. Echocardiograms were individually assessed by 2 cardiologists blinded for the outcome. Surgical and pathological inspection served as the reference standard for vegetations and peri-annular extensions (abscesses/mycotic aneurysms). To determine if the proximal coronary arteries were involved in the inflammatory process as well, computed tomography angiography findings were added to reference standard. Fifteen aortic PHV endocarditis cases were identified. According to the reference standard, all 15 cases had peri-annular extensions, 13 of which had a close relationship with the proximal right and/or left coronary artery. In 6 of 15 patients, a vegetation was present. Combined 2DTTE/TEE missed 1/6 vegetations and 1/15 peri-annular extensions. After addition of 3DTEE, all vegetations (6/6) and peri-annular extensions (15/15) were detected, without adding false positives. Compared to 2DTEE, in 3/15 cases, 3DTEE resulted in better delineation of the anatomical relationship of the proximal coronary arteries to the peri-annular extensions. As a result, 3DTEE had an additional value in 5/15 cases. In complex aortic, PHV endocarditis 3DTEE may have additional value compared to 2D echocardiography. © 2014, Wiley Periodicals, Inc.

  12. Direct Numerical Simulation of turbulent flow induced by prosthetic heart valves

    NASA Astrophysics Data System (ADS)

    Cristallo, Antonio; Verzicco, Roberto

    2005-11-01

    The complex turbulent flow patterns downstream of mechanical bileaflet valves are to a large extend responsible for the thromboembolic complications that remain a major concern after surgery. To illuminate the detailed dynamics of flow in the vicinity of such valves we performed Direct Numerical Simulations in a simplified configuration. The selected shape and size of the leaflets roughly mimics the SJM Standard bi-leaflet. Also, the housing was a straight pipe with rigid walls which expands and then contracts to mimic the geometry of the aortic root. The overall set-up resembles the one commonly used in in-vitro experiments. The computation of the fluid structure interaction problem is performed using a fully coupled, embedded boundary formulation at physiologic flowrates. The valves open at the beginning of the systole and close before the start of the diastole. The interaction of vortices originating from the leaflets and the housing dominate the flow in the downstream proximal area and are responsible for most of the production of turbulent stress.

  13. Valve mechanism of internal combustion engine

    SciTech Connect

    Morita, S.; Sato, K.; Asaoka, Y.; Harada, I.; Hirano, T.

    1987-02-24

    This patent describes a valve mechanism of an internal combustion engine, the valve mechanism comprising: a hydraulic valve lifter assembled in a recess of a rocker arm pivotably connected to a rocker shaft, the shaft extending through a hole in the rocker arm. The hydraulic valve lifter has a lifter body slidably inserted in the recess, a plunger slidably inserted in the lifter body, an oil chamber formed between the recess and the plunger, an oil pressure chamber communicating with the oil chamber through a passage and formed between the lifter body and the plunger. A check valve located in the passage for providing selective communication between the oil chamber and the oil pressure chamber; an oil supply path formed in the rocker arm and extending from an oil path formed in the rocker shaft to the oil chamber; and a return path formed in the rocker arm and communicating with the oil path in the rocker shaft. The return path extends from the top of the oil chamber to a clearance between an inside of the hole of the rocker arm and an outside of the rocker shaft, the return path providing constant communication between the oil chamber and the clearance.

  14. Integrated strategy for in vitro characterization of a bileaflet mechanical aortic valve.

    PubMed

    Susin, Francesca Maria; Espa, Stefania; Toninato, Riccardo; Fortini, Stefania; Querzoli, Giorgio

    2017-02-16

    Haemodynamic performance of heart valve prosthesis can be defined as its ability to fully open and completely close during the cardiac cycle, neither overloading heart work nor damaging blood particles when passing through the valve. In this perspective, global and local flow parameters, valve dynamics and blood damage safety of the prosthesis, as well as their mutual interactions, have all to be accounted for when assessing the device functionality. Even though all these issues have been and continue to be widely investigated, they are not usually studied through an integrated approach yet, i.e. by analyzing them simultaneously and highlighting their connections. An in vitro test campaign of flow through a bileaflet mechanical heart valve (Sorin Slimline 25 mm) was performed in a suitably arranged pulsatile mock loop able to reproduce human systemic pressure and flow curves. The valve was placed in an elastic, transparent, and anatomically accurate model of healthy aorta, and tested under several pulsatile flow conditions. Global and local hydrodynamics measurements and leaflet dynamics were analysed focusing on correlations between flow characteristics and valve motion. The haemolysis index due to the valve was estimated according to a literature power law model and related to hydrodynamic conditions, and a correlation between the spatial distribution of experimental shear stress and pannus/thrombotic deposits on mechanical valves was suggested. As main and general result, this study validates the potential of the integrated strategy for performance assessment of any prosthetic valve thanks to its capability of highlighting the complex interaction between the different physical mechanisms that govern transvalvular haemodynamics. We have defined an in vitro procedure for a comprehensive analysis of aortic valve prosthesis performance; the rationale for this study was the belief that a proper and overall characterization of the device should be based on the

  15. Basic mechanisms of calcific aortic valve disease.

    PubMed

    Mathieu, Patrick; Boulanger, Marie-Chloé

    2014-09-01

    Calcific aortic valve disease (CAVD) is the most common heart valve disorder. There is no medical treatment to prevent and/or promote the regression of CAVD. Hence, it is of foremost importance to delineate and understand the key basic underlying mechanisms involved in CAVD. In the past decade our comprehension of the underpinning processes leading to CAVD has expanded at a fast pace. Hence, our understanding of the basic pathobiological processes implicated in CAVD might lead eventually to the development of novel pharmaceutical therapies for CAVD. In this review, we discuss molecular processes that are implicated in fibrosis and mineralization of the aortic valve. Specifically, we address the role of lipid retention, inflammation, phosphate signalling and osteogenic transition in the development of CAVD. Interplays between these different processes and the key regulation pathways are discussed along with their clinical relevance.

  16. Percutaneous implantation of CoreValve aortic prostheses in patients with a mechanical mitral valve.

    PubMed

    Bruschi, Giuseppe; De Marco, Federico; Oreglia, Jacopo; Colombo, Paola; Fratto, Pasquale; Lullo, Francesca; Paino, Roberto; Frigerio, Maria; Martinelli, Luigi; Klugmann, Silvio

    2009-11-01

    Concerns exist in the field of transcatheter aortic valve implantation regarding the treatment of patients with mechanical mitral valve for possible interference between the percutaneous aortic valve and the mechanical mitral prosthesis. We report our experience with percutaneous aortic valve implantation in 4 patients with severe aortic stenosis, previously operated on for mitral valve replacement with a mechanical prosthesis. All patients underwent uneventful percutaneous retrograde CoreValve implantation (CoreValve Inc, Irvine, CA). No deformation of the nitinol tubing of the prostheses (ie, neither distortion nor malfunction of the mechanical valve in the mitral position) occurred in any of the patients. All patients are alive and asymptomatic at a mean follow-up of 171 days.

  17. Risk-adjusted survival after tissue versus mechanical aortic valve replacement: a 23-year assessment.

    PubMed

    Gaca, Jeffrey G; Clare, Robert M; Rankin, J Scott; Daneshmand, Mani A; Milano, Carmelo A; Hughes, G Chad; Wolfe, Walter G; Glower, Donald D; Smith, Peter K

    2013-11-01

    Detailed analyses of risk-adjusted outcomes after mitral valve surgery have documented significant survival decrements with tissue valves at any age. Several recent studies of prosthetic aortic valve replacement (AVR) also have suggested a poorer performance of tissue valves, although analyses have been limited to small matched series. The study aim was to test the hypothesis that AVR with tissue valves is associated with a lower risk-adjusted survival, as compared to mechanical valves. Between 1986 and 2009, primary isolated AVR, with or without coronary artery bypass grafting (CABG), was performed with currently available valve types in 2148 patients (1108 tissue valves, 1040 mechanical). Patients were selected for tissue valves to be used primarily in the elderly. Baseline and operative characteristics were documented prospectively with a consistent variable set over the entire 23-year period. Follow up was obtained with mailed questionnaires, supplemented by National Death Index searches. The average time to death or follow up was seven years, and follow up for survival was 96.2% complete. Risk-adjusted survival characteristics for the two groups were evaluated using a Cox proportional hazards model with stepwise selection of candidate variables. Differences in baseline characteristics between groups were (tissue versus mechanical): median age 73 versus 61 years; non-elective surgery 32% versus 28%; CABG 45% versus 35%; median ejection fraction 55% versus 55%; renal failure 6% versus 1%; diabetes 18% versus 7% (p<0.01). Unadjusted Kaplan-Meier survival was significantly lower with tissue than mechanical valves; however, after risk adjustment for the adverse profiles of tissue valve patients, no significant difference was observed in survival after tissue or mechanical AVR. Thus, the hypothesis did not hold, and risk-adjusted survival was equivalent, of course qualified by the fact that selection bias was evident. With selection criteria that employed tissue AVR

  18. Anticoagulation in pregnant women with mechanical heart valve prostheses

    PubMed Central

    Meschengieser, S; Fondevila, C; Santarelli, M; Lazzari, M

    1999-01-01

    OBJECTIVE—To evaluate the outcome of pregnancy in women with mechanical heart valve prostheses in relation to the anticoagulant treatment used in the first trimester and the incidence of thrombotic and bleeding complications.
METHODS—92 pregnancies in 59 women were followed between 1986 and 1997. In 31 pregnancies, oral anticoagulants were discontinued when pregnancy was diagnosed and subcutaneous heparin was started (12 500 U every 12 hours) adjusted to prolong the adjusted partial thromboplastin time to twice the control level. In the second trimester oral anticoagulants were resumed but changed to heparin again 15 days before the expected delivery date. In 61 pregnancies oral anticoagulants were continued during the first trimester. The same regimen of heparin was used for delivery.
RESULTS—Abortion or fetal losses were similar (p = 0.5717) in women exposed to oral anticoagulants in the first trimester (13/61; 25%) compared with those who received adjusted subcutaneous heparin (6/31; 19%). Embolic episodes were more common (p = 0.0029) in women who received heparin (4.92%) compared with those on oral anticoagulants (0.33%). Embolic episodes were cerebral and transient. No valve thromboses were observed. No malformations appeared in the 71 newborns, except for one case of hydrocephalus. There were no maternal deaths secondary to thrombotic complications. The only death was the result of major bleeding after the delivery of a premature stillborn.
CONCLUSIONS—Oral anticoagulants seem to be safer for the mother than adjusted subcutaneous heparin. Heparin does not offer a clear advantage over oral anticoagulation in the pregnancy outcome.


Keywords: pregnancy; oral anticoagulants; heparin; prosthetic valves PMID:10377303

  19. Prosthetic mitral valve thrombosis: can fluoroscopy predict the efficacy of thrombolytic treatment?

    PubMed

    Montorsi, Piero; Cavoretto, Dario; Alimento, Marina; Muratori, Manuela; Pepi, Mauro

    2003-09-09

    Thrombolysis (T) is an effective therapy for prosthetic valve thrombosis (PVT). Debate still exists as to which clinical or noninvasive finding best predict the result of T. The aim of the study was to investigate the role of fluoroscopy (F) to predict efficacy of T in pts with mitral PVT. We evaluated 17 consecutive pts with bileaflet mitral PVT. F criteria for PVT were: abnormal disc motion and calculated opening angle >25 degrees. T was carried out with tissue-type plasminogen activator (tPA; 100 mg over 3 hours followed by heparin infusion for 24 hours) and was considered successful when normalization of leaflet motion and opening angle occurred. Results were evaluated according to symptom duration (<21 days, early PVT; >21 days, late PVT) and to F pattern of PVT (blocked leaflet versus hypomobile leaflet). F showed disc motion alteration in 24 of 34 leaflets: 8 leaflets were blocked, whereas 16 were hypomobile. Early (12.7+/-6.1 days, range 3-21) and late (113+/-114 days, range 28-365) PVT was present in 8 and 7 pts, respectively. Thrombolysis was successful in 20 of 24 leaflets. Blocked leaflet fully recovered only in early PVT (n=4) pts, whereas they remained blocked in late PVT (n=4). On the contrary, in all of the cases with hypomobile leaflet, disc motion normalized regardless duration of symptoms and extent of disc motion reduction. Interestingly, 4 leaflets with late PVT was diagnosed as blocked by trans-thoracic (TTE). F showed a residual disc movement in all: they fully recovered after T. Two pts with late PVT had both leaflets affected (1 blocked +1 hypomobile); although blocked leaflet did not respond to T, the normalization of hypomobile significantly improved clinical condition. F can predict result of T in mitral PVT. PVT with F evidence of hypomobile leaflet always recovers regardless of symptom duration and extent of disc motion reduction, suggesting that the small amount of thrombus needed to interfere with discs motion in bileaflet prostheses

  20. Two-component laser Doppler anemometer for measurement of velocity and turbulent shear stress near prosthetic heart valves.

    PubMed

    Woo, Y R; Yoganathan, A P

    1985-01-01

    The velocity and turbulent shear stress measured in the immediate vicinity of prosthetic heart valves play a vital role in the design and evaluation of these devices. In the past hot wire/film and one-component laser Doppler anemometer (LDA) systems were used extensively to obtain these measurements. Hot wire/film anemometers, however, have some serious disadvantages, including the inability to measure the direction of the flow, the disturbance of the flow field caused by the probe, and the need for frequent calibration. One-component LDA systems do not have these problems, but they cannot measure turbulent shear stresses directly. Since these measurements are essential and are not available in the open literature, a two-component LDA system for measuring velocity and turbulent shear stress fields under pulsatile flow conditions was assembled under an FDA contract. The experimental methods used to create an in vitro data base of velocity and turbulent shear stress fields in the immediate vicinity of prosthetic heart valves of various designs in current clinical use are also discussed.

  1. Effects of a 3D segmental prosthetic system for tricuspid valve annulus remodelling on the right coronary artery: a human cadaveric coronary angiography study.

    PubMed

    Riki-Marishani, Mohsen; Gholoobi, Arash; Sazegar, Ghasem; Aazami, Mathias H; Hedjazi, Aria; Sajjadian, Maryam; Ebrahimi, Mahmoud; Aghaii-Zade Torabi, Ahmad

    2017-09-01

    A prosthetic system to repair secondary tricuspid valve regurgitation was developed. The conceptual engineering of the current device is based on 3D segmental remodelling of the tricuspid valve annulus in lieu of reductive annuloplasty. This study was designed to investigate the operational safety of the current prosthetic system with regard to the anatomical integrity of the right coronary artery (RCA) in fresh cadaveric human hearts. During the study period, from January to April 2016, the current prosthetic system was implanted on the tricuspid valve annulus in fresh cadaveric human hearts that met the study's inclusion criteria. The prepared specimens were investigated via selective coronary angiography of the RCA in the catheterization laboratory. The RCA angiographic anatomies were categorized as normal, distorted, kinked or occluded. Sixteen specimens underwent implantation of the current prosthetic system. The mean age of the cadaveric human hearts was 43.24 ± 15.79 years, with vehicle accident being the primary cause of death (59%). A dominant RCA was noticed in 62.5% of the specimens. None of the specimens displayed any injury, distortion, kinking or occlusion in the RCA due to the implantation of the prostheses. In light of the results of the present study, undertaken on fresh cadaveric human heart specimens, the current segmental prosthetic system for 3D remodelling of the tricuspid valve annulus seems to be safe vis-à-vis the anatomical integrity of the RCA. Further in vivo studies are needed to investigate the functional features of the current prosthetic system with a view to addressing the complex pathophysiology of secondary tricuspid valve regurgitation.

  2. Conserved transcriptional regulatory mechanisms in aortic valve development and disease

    PubMed Central

    Wirrig, Elaine E.; Yutzey, Katherine E.

    2014-01-01

    There is increasing evidence for activation of developmental transcriptional regulatory pathways in heart valve disease. Here we review molecular regulatory mechanisms involved in heart valve progenitor development, leaflet morphogenesis, and extracellular matrix organization that also are active in diseased aortic valves. These include regulators of endothelial-to-mesenchymal transitions, such as the Notch pathway effector RBPJ, and the valve progenitor markers Twist1, Msx1/2, and Sox9. Little is known of the potential reparative or pathological functions of these developmental mechanisms in adult aortic valves, but it is tempting to speculate that valve progenitor cells could contribute to repair in the context of disease. Likewise, loss of either RBPJ or Sox9 leads to aortic valve calcification in mice, supporting a potential therapeutic role in prevention of disease. During aortic valve calcification, transcriptional regulators of osteogenic development are activated in addition to valve progenitor regulatory programs. Specifically, the transcription factor Runx2 and its downstream target genes are induced in calcified valves. Runx2 and osteogenic genes also are induced with vascular calcification, but activation of valve progenitor markers and the cellular context of expression are likely to be different for valve and vascular calcification. Additional research is necessary to determine if developmental mechanisms contribute to valve repair or if these pathways can be harnessed for new treatments of heart valve disease. PMID:24665126

  3. Healthcare-associated prosthetic heart valve, aortic vascular graft, and disseminated Mycobacterium chimaera infections subsequent to open heart surgery.

    PubMed

    Kohler, Philipp; Kuster, Stefan P; Bloemberg, Guido; Schulthess, Bettina; Frank, Michelle; Tanner, Felix C; Rössle, Matthias; Böni, Christian; Falk, Volkmar; Wilhelm, Markus J; Sommerstein, Rami; Achermann, Yvonne; Ten Oever, Jaap; Debast, Sylvia B; Wolfhagen, Maurice J H M; Brandon Bravo Bruinsma, George J; Vos, Margreet C; Bogers, Ad; Serr, Annerose; Beyersdorf, Friedhelm; Sax, Hugo; Böttger, Erik C; Weber, Rainer; van Ingen, Jakko; Wagner, Dirk; Hasse, Barbara

    2015-10-21

    We identified 10 patients with disseminated Mycobacterium chimaera infections subsequent to open-heart surgery at three European Hospitals. Infections originated from the heater-cooler unit of the heart-lung machine. Here we describe clinical aspects and treatment course of this novel clinical entity. Interdisciplinary care and follow-up of all patients was documented by the study team. Patients' characteristics, clinical manifestations, microbiological findings, and therapeutic measures including surgical reinterventions were reviewed and treatment outcomes are described. The 10 patients comprise a 1-year-old child and nine adults with a median age of 61 years (range 36-76 years). The median duration from cardiac surgery to diagnosis was 21 (range 5-40) months. All patients had prosthetic material-associated infections with either prosthetic valve endocarditis, aortic graft infection, myocarditis, or infection of the prosthetic material following banding of the pulmonary artery. Extracardiac manifestations preceded cardiovascular disease in some cases. Despite targeted antimicrobial therapy, M. chimaera infection required cardiosurgical reinterventions in eight patients. Six out of 10 patients experienced breakthrough infections, of which four were fatal. Three patients are in a post-treatment monitoring period. Healthcare-associated infections due to M. chimaera occurred in patients subsequent to cardiac surgery with extracorporeal circulation and implantation of prosthetic material. Infections became clinically apparent after a time lag of months to years. Mycobacterium chimaera infections are easily missed by routine bacterial diagnostics and outcome is poor despite long-term antimycobacterial therapy, probably because biofilm formation hinders eradication of pathogens. Published on behalf of the European Society of Cardiology. All rights reserved. © The Author 2015. For permissions please email: journals.permissions@oup.com.

  4. Gallium-SPECT in the detection of prosthetic valve endocarditis and aortic ring abscess

    SciTech Connect

    O'Brien, K.; Barnes, D.; Martin, R.H.; Rae, J.R. )

    1991-09-01

    A 52-yr-old man who had a bioprosthetic aortic valve developed Staphylococcus aureus bacteremia. Despite antibiotic therapy he had persistent pyrexia and developed new conduction system disturbances. Echocardiography did not demonstrate vegetations on the valve or an abscess, but gallium scintigraphy using SPECT clearly identified a focus of intense activity in the region of the aortic valve. The presence of valvular vegetations and a septal abscess was confirmed at autopsy. Gallium scintigraphy, using SPECT, provided a useful noninvasive method for the demonstration of endocarditis and the associated valve ring abscess.

  5. Mechanical design of a shape memory alloy actuated prosthetic hand.

    PubMed

    De Laurentis, Kathryn J; Mavroidis, Constantinos

    2002-01-01

    This paper presents the mechanical design for a new five fingered, twenty degree-of-freedom dexterous hand patterned after human anatomy and actuated by Shape Memory Alloy artificial muscles. Two experimental prototypes of a finger, one fabricated by traditional means and another fabricated by rapid prototyping techniques, are described and used to evaluate the design. An important aspect of the Rapid Prototype technique used here is that this multi-articulated hand will be fabricated in one step, without requiring assembly, while maintaining its desired mobility. The use of Shape Memory Alloy actuators combined with the rapid fabrication of the non-assembly type hand, reduce considerably its weight and fabrication time. Therefore, the focus of this paper is the mechanical design of a dexterous hand that combines Rapid Prototype techniques and smart actuators. The type of robotic hand described in this paper can be utilized for applications requiring low weight, compactness, and dexterity such as prosthetic devices, space and planetary exploration.

  6. Radi pressurewire rupture and embolization to the right common carotid artery after crossing a bjork-shiley mechanical aortic valve.

    PubMed

    Marmagkiolis, Konstantinos; Cilingiroglu, Mehmet

    2013-10-01

    Direct measurement of the left ventricular pressure in patients with mechanical prosthetic aortic valve is an important technical challenge. In the past, transseptal puncture or direct left ventricular accesses were the only available methods. The use of a pressure wire through mechanical aortic prosthesis has been described to be feasible and safe. We report the first case report of pressure guidewire entrapment through a single tilting disk valve (Bjork-Shiley), which resulted in hemodynamic collapse, rupture, and embolization of the pressure wire tip to the right common carotid artery and its successful snaring.

  7. Check valve with poppet damping mechanism

    NASA Technical Reports Server (NTRS)

    Morris, Brian G. (Inventor)

    1993-01-01

    An inline check valve for a flow line is presented where the valve element is guided for inline travel forward and rearward of a valve sealing member and is spring biased to a closed sealing condition. One of the guides for the valve element includes a dashpot bore and plunger member to control the rate of travel of the valve element in either direction as well as provided a guiding function. The dashpot is not anchored to the valve body so that the valve can be functional even if the plunger member becomes jammed in the dashpot.

  8. Check valve with poppet damping mechanism

    NASA Astrophysics Data System (ADS)

    Morris, Brian G.

    1993-08-01

    An inline check valve for a flow line is presented where the valve element is guided for inline travel forward and rearward of a valve sealing member and is spring biased to a closed sealing condition. One of the guides for the valve element includes a dashpot bore and plunger member to control the rate of travel of the valve element in either direction as well as provided a guiding function. The dashpot is not anchored to the valve body so that the valve can be functional even if the plunger member becomes jammed in the dashpot.

  9. Check valve with poppet damping mechanism

    NASA Astrophysics Data System (ADS)

    Morris, Brian G.

    1992-06-01

    An inline check valve for a flow line is presented where the valve element is guided for inline travel forward and rearward of a valve sealing member and is spring biased to a closed sealing condition. One of the guides for the valve element includes a dashpot bore and plunger member to control the rate of travel of the valve element in either direction as well as provided a guiding function. The dashpot is not anchored to the valve body so that the valve can be functional even if the plunger member becomes jammed in the dashpot.

  10. Successful application of a PressureWire retrogradely across an ATS prosthetic aortic valve to diagnose constrictive pericarditis.

    PubMed

    Palmer, Sonny; Mariani, Justin A; Newcomb, Andrew; Stokes, Michael B; Burns, Andrew T

    2012-01-01

    Assessment of the left ventricular pressure measured across an aortic valve prosthesis is occasionally necessary when noninvasive imaging and Doppler echocardiographic data are inconclusive or differ from the clinical findings for specific scenarios, such as diagnosing constrictive or restrictive physiology. We present a case in which we safely and effectively replicate the previous successful application of a PressureWire in diagnosing constrictive pericarditis in a patient with a bileafltet mechanical aortic and mitral valves.

  11. Development of Overflow-Prevention Valve with Trigger Mechanism.

    NASA Astrophysics Data System (ADS)

    Ishino, Yuji; Mizuno, Takeshi; Takasaki, Masaya

    2016-09-01

    A new overflow-prevention valve for combustible fluid is developed which uses a trigger mechanism. Loading arms for combustible fluid are used for transferring oil from a tanker to tanks and vice versa. The loading arm has a valve for preventing overflow. Overflow- prevention valves cannot use any electric component to avoid combustion. Therefore, the valve must be constructed only by mechanical parts. The conventional overflow-prevention valve uses fluid and pneumatic forces. It consists of a sensor probe, a cylinder, a main valve for shutting off the fluid and a locking mechanism for holding an open state of the main valve. The proposed overflow-prevention valve uses the pressure due to the height difference between the fluid level of the tank and the sensor probe. However, the force of the cylinder produced by the pressure is too small to release the locking mechanism. Therefore, a trigger mechanism is introduced between the cylinder and the locking mechanism. The trigger mechanism produces sufficient force to release the locking mechanism and close the main valve when the height of fluid exceeds a threshold value. A trigger mechanism is designed and fabricated. The operation necessary for closing the main valve is conformed experimentally.

  12. Quantitative assessment of the presence of a single leg separation in Björk-Shiley convexoconcave prosthetic heart valves.

    PubMed

    Vrooman, H A; Maliepaard, C; van der Linden, L P; Jessurun, E R; Ludwig, J W; Plokker, H W; Schalij, M J; Weeda, H W; Laufer, J L; Huysmans, H A; Reiber, J H

    1997-09-01

    The authors developed an analytic software package for the objective and reproducible assessment of a single leg separation (SLS) in the outlet strut of Björk-Shiley convexoconcave (BSCC) prosthetic heart valves. The radiographic cinefilm recordings of 18 phantom valves (12 intact and 6 SLS) and of 43 patient valves were acquired. After digitization of regions of interest in a cineframe, several processing steps were carried out to obtain a one-dimensional corrected and averaged density profile along the central axis of each strut leg. To characterize the degree of possible separation, two quantitative measures were introduced: the normalized pit depth (NPD) and the depth-sigma ratio (DSR). The group of 43 patient studies was divided into a learning set (25 patients) and a test set (18 patients). All phantom valves with an SLS were detected (sensitivity, 100%) at a specificity of 100%. The threshold values for the NPD and the DSR to decide whether a fracture was present or not were 3.6 and 2.5, respectively. On the basis of the visual interpretations of the 25 patient studies (learning set) by an expert panel, it was concluded that none of the patients had an SLS. To achieve a 100% specificity by quantitative analysis, the threshold values for the NPD and the DSR were set at 5.8 and 2.5, respectively, for the patient data. Based on these threshold values, the analysis of patient data from the test set resulted in one false-negative detection and three false-positive detections. An analytic software package for the detection of an SLS was developed. Phantom data showed excellent sensitivity (100%) and specificity (100%). Further research and software development is needed to increase the sensitivity and specificity for patient data.

  13. Mechanical design and performance specifications of anthropomorphic prosthetic hands: a review.

    PubMed

    Belter, Joseph T; Segil, Jacob L; Dollar, Aaron M; Weir, Richard F

    2013-01-01

    In this article, we set forth a detailed analysis of the mechanical characteristics of anthropomorphic prosthetic hands. We report on an empirical study concerning the performance of several commercially available myoelectric prosthetic hands, including the Vincent, iLimb, iLimb Pulse, Bebionic, Bebionic v2, and Michelangelo hands. We investigated the finger design and kinematics, mechanical joint coupling, and actuation methods of these commercial prosthetic hands. The empirical findings are supplemented with a compilation of published data on both commercial and prototype research prosthetic hands. We discuss numerous mechanical design parameters by referencing examples in the literature. Crucial design trade-offs are highlighted, including number of actuators and hand complexity, hand weight, and grasp force. Finally, we offer a set of rules of thumb regarding the mechanical design of anthropomorphic prosthetic hands.

  14. Can marine mammals be a reliable source for the manufacture of prosthetic heart valves for percutaneous surgery?

    PubMed

    Guidoin, Robert; Reed, Robert R; Lagaude, Antoine; Bes, Taniela Marli; Li, Bin; Klein, Julianne; Gauvin, Robert; Guzman, Randolph; Germain, Lucie; Zhang, Ze

    2012-01-01

    Marine mammals experience unique physiological conditions when diving. Myocardial function is sustained despite a 90% reduction of the blood flow in the coronaries. Therefore, their heart valves and pericardium could serve as a unique source of tissue for the manufacture of prosthetic heart valves. The pericardium of a stillborn pup sea lion was investigated to determine its morphology using gross observation, scanning electron microscopy (SEM), light microscopy, and transmission electron microscopy (TEM). Depending upon the site of sampling, the structure of the pericardium varied significantly. The atrial sample was well structured with wavy bundles of collagen fibers. The thickness in the atrial sample was regular with a smooth serous surface. The fibrous side of the pericardium of the auricular sample was irregular and incorporated microcapillaries. Both the sternoperitoneal ligament and the phrenoperitoneal ligament section were irregular and incorporated various amounts of adipocytes. Because of the increased amount of adipocytes, the fibrils of the collagen fibers were also observed to be occasionally agglutinated. Practically, the harvesting of pericardium would have to be restricted to the atrial surface. The presence of adipocytes in the pericardium wall makes the selection of this tissue a poor choice compared to alternative existing tissue sources.

  15. Processing of prosthetic heart valve sounds for single leg separation classification

    SciTech Connect

    Candy, J.V.; Jones, H.E.

    1995-06-01

    Efforts are concentrated on the sounds corresponding to the heart valve opening cycle. Valve opening and closing acoustics present additional information about the outlet strut condition---the structural component implicated in valve failure. The importance of the opening sound for single leg separation detection/classification is based on the fact that as the valve opens, the disk passively hits the outlet strut. The opening sounds thus yield direct information about outlet strut condition with minimal amount of disturbance caused by the energy radiated from the disk. Hence the opening sound is a very desirable acoustic signal to extract. Unfortunately, the opening sounds have much lower signal levels relative to the closing sounds and therefore noise plays a more significant role than during the closing event. Because of this it is necessary to screen the sounds for outliers in order to insure a high sensitivity of classification. Because of the sharp resonances appearing in the corresponding spectrum, a parametric processing approach is developed based on an autoregressive model which was selected to characterize the sounds emitted by the Bjork--Shiley convexo--concave (BSCC) valve during opening cycle. First the basic signals and the extraction process used to create an ensemble of heart valve sounds are briefly discussed. Next, a {ital beat} {ital monitor} capable of rejecting beats that fail to meet an acceptance criteria based on their spectral content is developed. Various approaches that have been utilized to enhance the screened data and produce a reliable {ital heart} {ital valve} {ital spectrogram} which displays the individual sounds (power) as a function of beat number and temporal frequency are discussed. Once estimated, the spectrogram and associated parameters are used to develop features supplied to the various classification schemes. Finally, future work aimed at even further signal enhancement and improved classifier performance is discussed.

  16. Mitigation of Shear-Induced Blood Damage of Mechanical Bileaflet Heart Valves using Embedded Vortex Generators

    NASA Astrophysics Data System (ADS)

    Hidalgo, Pablo; Arjunon, Sivakkumar; Saikrishnan, Neelakantan; Yoganathan, Ajit; Glezer, Ari

    2012-11-01

    The strong transitory shear stress generated during the time-periodic closing of the mechanical prosthetic bileaflet aortic heart valve, is considered to be one of the main factors responsible for complications, associated with thrombosis and thromboembolism. These flow transients are investigated using phase and time-averaged PIV in a low-volume (about 150 ml) test setup that simulates the pulsatile physiological conditions associated with a 23 mm St. Jude Medical valve. The PIV measurements are accompanied by continuous monitoring of the ventricular and aortic pressures and valve flow rate. Following the valve closure, the leakage flow between the valve leaflets is caused by the pressure buildup across the leaflets, leading to the formation of a regurgitation jet starting from the BMHV B-datum line. As in a typical starting jet, a counter-rotating vortex pair is formed along each leaflet edge and the vorticity sheet is associated with high shear stress that may be result in blood platelet activation. The present investigation demonstrates that the placement of arrays of mm-scale vortex generators near the edges of the leaflets diffuses the vortex sheet and suppresses the formation of these vortices, weakening the local velocity gradients and small-scale vortical structures. Supported by NIH and NSF.

  17. Percutaneous stent-mounted valve for treatment of aortic or pulmonary valve disease.

    PubMed

    Webb, John G; Munt, Bradley; Makkar, Raj R; Naqvi, Tasneem Z; Dang, Ninh

    2004-09-01

    The objective of this study was to develop a prosthetic cardiac valve designed for percutaneous transcatheter implantation. Percutaneous catheter-based therapies play a limited role in the management of cardiac valve disease. Surgical implantation of prosthetic valves usually requires thoracotomy and cardiopulmonary bypass. The stent-valve is constructed of a rolled sheet of heat-treated nitinol. Although malleable when cooled, once released from a restraining sheath at body temperature the stent unrolls, becomes rigid, and assumes its predetermined cylindrical conformation. A ratcheting lock-out mechanism prevents recoil and external protrusions facilitate anchoring. Valve leaflets are constructed of bovine pericardium. The feasibility of catheter implantation, prosthetic valve function, and survival were investigated in an animal model. In vitro and pulse duplicator testing documented valve durability. Endovascular delivery of the prototype stent-valve to the aortic or pulmonary position was feasible. Accurate positioning was required to ensure exclusion of the native valve leaflets and, in the case of the aortic valve, to avoid compromise of the coronary ostia or mitral apparatus. Oversizing of the stent in relation to the valve annulus was desirable to facilitate anchoring and prevent paravalvular insufficiency. Stent-valve implantation proved feasible and compatible with survival in an animal model. Transcatheter implantation of prosthetic valves is possible. Further evolution of this technology will involve lower-profile devices with design features that facilitate vascular delivery, visualization, positioning, deployment, and valvular function.

  18. Valve mechanism for an automotive engine

    SciTech Connect

    Ishii, N.

    1988-02-16

    A valve mechanism for an automotive engine having a rocker arm comprising a rocker arm member rocked by a cam and an actuating arm member operatively engaged with the rocker arm member for operating a stem of a valve is described comprising: a sleeve rotatably and slidably mounted on a rocker-arm shaft and having splines on a periphery thereof and a cylindrical portion adjacent the splines. The rocker arm member has splines and slidably engaged with the splines of the sleeve. The actuating arm member has splines corresponding to the splines of the sleeve and slidably engaged with the cylindrical portion of the sleeve at a disengagement position. A piston is slidably mounted on the rocker-arm shaft adjacent the sleeve; and hydraulic means are for applying oil to the piston so as to shift the sleeve to an engagement position to engage the splines thereof with the actuating arm member. A spring is provided between the cylindrical portion and a shaft holder for shifting the sleeve from the engagement position to the disengagement position; and stopping means hold the sleeve at the disengagement position and the engagement position respectively.

  19. Cardiac rehabilitation after transcatheter versus surgical prosthetic valve implantation for aortic stenosis in the elderly.

    PubMed

    Russo, Nicola; Compostella, Leonida; Tarantini, Giuseppe; Setzu, Tiziana; Napodano, Massimo; Bottio, Tomaso; D'Onofrio, Augusto; Isabella, Gianbattista; Gerosa, Gino; Iliceto, Sabino; Bellotto, Fabio

    2014-11-01

    Transcatheter aortic valve implantation plays a leading role in the management of aortic stenosis in patients with comorbidities but no data are available about cardiac rehabilitation in these subjects. This study aimed to compare safety and efficacy of an early, exercise-based, cardiac rehabilitation programme in octogenarians after a traditional surgical aortic valve replacement versus transcatheter aortic valve implantation. Seventy-eight consecutive transcatheter aortic valve implantation patients were studied in order to evaluate the effect of an exercise-based cardiac rehabilitation programme in comparison to 80 of a similar age having surgical aortic valve replacement. Functional capacity was assessed by a 6 min walking test on admission and at the end of the programme. When possible, a cardiopulmonary exercise test was also performed before discharge. The two groups were similar in terms of gender and length of stay in cardiac rehabilitation; as expected, the transcatheter aortic valve implantation group had more comorbidities but no major complications occurred in either group during rehabilitation. All patients enhanced autonomy and mobility and were able to walk at least with the assistance of a stick. In those patients who were able to perform the 6 min walking test, the distance walked at discharge did not significantly differ between the groups (272.7 ± 108 vs. 294.2 ± 101 m, p = 0.42), neither did the exercise capacity assessed by cardiopulmonary exercise test (peak-VO2 12.5 ± 3.6 vs. 13.9 ± 2.7 ml/kg/min, p = 0.16). Cardiac rehabilitation is feasible, safe and effective in octogenarian patients after transcatheter aortic valve implantation as well as after traditional surgery. An early cardiac rehabilitation programme enhances independence, mobility and functional capacity and should be highly encouraged. © The Author(s) 2013 Reprints and permissions: sagepub.co.uk/journalsPermissions.nav.

  20. Five-year echocardiographic follow-up after TAVI: structural and functional changes of a balloon-expandable prosthetic aortic valve.

    PubMed

    Muratori, Manuela; Fusini, Laura; Tamborini, Gloria; Gripari, Paola; Ghulam Ali, Sarah; Mapelli, Massimo; Fabbiocchi, Franco; Trabattoni, Piero; Roberto, Maurizio; Agrifoglio, Marco; Alamanni, Francesco; Bartorelli, Antonio L; Pepi, Mauro

    2017-03-30

    Scarce data are available on the long-term structural and functional changes of prosthetic valves after transcatheter aortic valve implantation (TAVI). The objective was to evaluate with echocardiography the long-term structural and functional changes of prosthetic valves after TAVI. Structural valve deterioration (SVD) was defined as leaflet thickening ≥3mm, presence of calcification and abnormal leaflet motion. Five-year echocardiographic follow-up was available in 96 out of 318 patients who underwent TAVI with a balloon-expandable device between April 2008 and December 2011. At 1-year follow-up, no patient showed SVD. At 5-year follow-up, SVD were observed in 29 (30%) patients who showed also a significant reduction of aortic valve area (AVA) together with an increase of mean and peak aortic pressure gradients at the latest echocardiography evaluation. Moreover, rate of central aortic valve regurgitation ≥2 was higher in SVD patients as compared to those without SVD, while there was no difference in terms of paravalvular regurgitation. Despite SVD, one patient only reached the criteria for severe stenosis and no reintervention was needed at 5-year follow-up. Variables independently associated with SVD were female sex, small body surface area, use of a 23 mm valve, and small AVA at pre-discharge echocardiogram. At 5-year follow-up, 30% of patients who underwent TAVI with a balloon-expandable valve showed initial SVD. However, SVD was not associated with severe stenosis in most of the patients and had no significant impact on and clinical outcome.

  1. Valves and other mechanical components and equipment: A compilation

    NASA Technical Reports Server (NTRS)

    1976-01-01

    The articles in this Compilation will be of interest to mechanical engineers, users and designers of machinery, and to those engineers and manufacturers specializing in fluid handling systems. Section 1 describes a number of valves and valve systems. Section 2 contains articles on machinery and mechanical devices that may have applications in a number of different areas.

  2. Safety-Valve Mechanism For Pressure-Vessel Window

    NASA Technical Reports Server (NTRS)

    Mccoomb, E. J.

    1994-01-01

    Pressure-activated valve mechanism seals small window in pressure chamber if window cracks or breaks, thereby preventing continued leakage or sudden decompression. Window used in experiments involving optical observation of processes in chamber. Valve mechanism activated by pressure from gas leaking through window.

  3. Effect of heart rate on the hemodynamics of bileaflet mechanical heart valves' prostheses (St. Jude Medical) in the aortic position and in the opening phase: A computational study.

    PubMed

    Jahandardoost, Mehdi; Fradet, Guy; Mohammadi, Hadi

    2016-03-01

    To date, to the best of the authors' knowledge, in almost all of the studies performed around the hemodynamics of bileaflet mechanical heart valves, a heart rate of 70-72 beats/min has been considered. In fact, the heart rate of ~72 beats/min does not represent the entire normal physiological conditions under which the aortic or prosthetic valves function. The heart rates of 120 or 50 beats/min may lead to hemodynamic complications, such as plaque formation and/or thromboembolism in patients. In this study, the hemodynamic performance of the bileaflet mechanical heart valves in a wide range of normal and physiological heart rates, that is, 60-150 beats/min, was studied in the opening phase. The model considered in this study was a St. Jude Medical bileaflet mechanical heart valve with the inner diameter of 27 mm in the aortic position. The hemodynamics of the native valve and the St. Jude Medical valve were studied in a variety of heart rates in the opening phase and the results were carefully compared. The results indicate that peak values of the velocity profile downstream of the valve increase as heart rate increases, as well as the location of the maximum velocity changes with heart rate in the St. Jude Medical valve model. Also, the maximum values of shear stress and wall shear stresses downstream of the valve are proportional to heart rate in both models. Interestingly, the maximum shear stress and wall shear stress values in both models are in the same range when heart rate is <90 beats/min; however, these values significantly increase in the St. Jude Medical valve model when heart rate is >90 beats/min (up to ~40% growth compared to that of the native valve). The findings of this study may be of importance in the hemodynamic performance of bileaflet mechanical heart valves. They may also play an important role in design improvement of conventional prosthetic heart valves and the design of the next generation of prosthetic valves, such as

  4. Impact of Early Valve Surgery on Outcome of Staphylococcus aureus Prosthetic Valve Infective Endocarditis: Analysis in the International Collaboration of Endocarditis–Prospective Cohort Study

    PubMed Central

    Chirouze, Catherine; Alla, François; Fowler, Vance G.; Sexton, Daniel J.; Corey, G. Ralph; Chu, Vivian H.; Wang, Andrew; Erpelding, Marie-Line; Durante-Mangoni, Emanuele; Fernández-Hidalgo, Nuria; Giannitsioti, Efthymia; Hannan, Margaret M.; Lejko-Zupanc, Tatjana; Miró, José M.; Muñoz, Patricia; Murdoch, David R.; Tattevin, Pierre; Tribouilloy, Christophe; Hoen, Bruno; Clara, Liliana; Sanchez, Marisa; Nacinovich, Francisco; Oses, Pablo Fernandez; Ronderos, Ricardo; Sucari, Adriana; Thierer, Jorge; Casabé, José; Cortes, Claudia; Altclas, Javier; Kogan, Silvia; Spelman, Denis; Athan, Eugene; Harris, Owen; Kennedy, Karina; Tan, Ren; Gordon, David; Papanicolas, Lito; Eisen, Damon; Grigg, Leeanne; Street, Alan; Korman, Tony; Kotsanas, Despina; Dever, Robyn; Jones, Phillip; Konecny, Pam; Lawrence, Richard; Rees, David; Ryan, Suzanne; Feneley, Michael P.; Harkness, John; Jones, Phillip; Ryan, Suzanne; Jones, Phillip; Ryan, Suzanne; Jones, Phillip; Post, Jeffrey; Reinbott, Porl; Ryan, Suzanne; Gattringer, Rainer; Wiesbauer, Franz; Andrade, Adriana Ribas; de Brito, Ana Cláudia Passos; Guimarães, Armenio Costa; Grinberg, Max; Mansur, Alfredo José; Siciliano, Rinaldo Focaccia; Strabelli, Tania Mara Varejao; Vieira, Marcelo Luiz Campos; de Medeiros Tranchesi, Regina Aparecida; Paiva, Marcelo Goulart; Fortes, Claudio Querido; de Oliveira Ramos, Auristela; Ferraiuoli, Giovanna; Golebiovski, Wilma; Lamas, Cristiane; Santos, Marisa; Weksler, Clara; Karlowsky, James A.; Keynan, Yoav; Morris, Andrew M.; Rubinstein, Ethan; Jones, Sandra Braun; Garcia, Patricia; Cereceda, M; Fica, Alberto; Mella, Rodrigo Montagna; Barsic, Bruno; Bukovski, Suzana; Krajinovic, Vladimir; Pangercic, Ana; Rudez, Igor; Vincelj, Josip; Freiberger, Tomas; Pol, Jiri; Zaloudikova, Barbora; Ashour, Zainab; El Kholy, Amani; Mishaal, Marwa; Rizk, Hussien; Aissa, Neijla; Alauzet, Corentine; Alla, Francois; Campagnac, Catherine; Doco-Lecompte, Thanh; Selton-Suty, Christine; Casalta, Jean-Paul; Fournier, Pierre-Edouard; Habib, Gilbert; Raoult, Didier; Thuny, Franck; Delahaye, François; Delahaye, Armelle; Vandenesch, Francois; Donal, Erwan; Donnio, Pierre Yves; Michelet, Christian; Revest, Matthieu; Tattevin, Pierre; Violette, Jérémie; Chevalier, Florent; Jeu, Antoine; Sorel, Claire; Tribouilloy, Christophe; Bernard, Yvette; Chirouze, Catherine; Hoen, Bruno; Leroy, Joel; Plesiat, Patrick; Naber, Christoph; Neuerburg, Carl; Mazaheri, Bahram; Naber, Christoph; Neuerburg, Carl; Athanasia, Sofia; Giannitsioti, Efthymia; Mylona, Elena; Paniara, Olga; Papanicolaou, Konstantinos; Pyros, John; Skoutelis, Athanasios; Sharma, Gautam; Francis, Johnson; Nair, Lathi; Thomas, Vinod; Venugopal, Krishnan; Hannan, Margaret; Hurley, John; Gilon, Dan; Israel, Sarah; Korem, Maya; Strahilevitz, Jacob; Rubinstein, Ethan; Strahilevitz, Jacob; Casillo, Roberta; Cuccurullo, Susanna; Dialetto, Giovanni; Durante-Mangoni, Emanuele; Irene, Mattucci; Ragone, Enrico; Tripodi, Marie Françoise; Utili, Riccardo; Cecchi, Enrico; De Rosa, Francesco; Forno, Davide; Imazio, Massimo; Trinchero, Rita; Tebini, Alessandro; Grossi, Paolo; Lattanzio, Mariangela; Toniolo, Antonio; Goglio, Antonio; Raglio, Annibale; Ravasio, Veronica; Rizzi, Marco; Suter, Fredy; Carosi, Giampiero; Magri, Silvia; Signorini, Liana; Baban, Tania; Kanafani, Zeina; Kanj, Souha S.; Yasmine, Mohamad; Abidin, Imran; Tamin, Syahidah Syed; Martínez, Eduardo Rivera; Soto Nieto, Gabriel Israel; van der Meer, Jan T.M.; Chambers, Stephen; Holland, David; Morris, Arthur; Raymond, Nigel; Read, Kerry; Murdoch, David R.; Dragulescu, Stefan; Ionac, Adina; Mornos, Cristian; Butkevich, O.M.; Chipigina, Natalia; Kirill, Ozerecky; Vadim, Kulichenko; Vinogradova, Tatiana; Edathodu, Jameela; Halim, Magid; Lum, Luh-Nah; Tan, Ru-San; Lejko-Zupanc, Tatjana; Logar, Mateja; Mueller-Premru, Manica; Commerford, Patrick; Commerford, Anita; Deetlefs, Eduan; Hansa, Cass; Ntsekhe, Mpiko; Almela, Manuel; Armero, Yolanda; Azqueta, Manuel; Castañeda, Ximena; Cervera, Carlos; del Rio, Ana; Falces, Carlos; Garcia-de-la-Maria, Cristina; Fita, Guillermina; Gatell, Jose M.; Marco, Francesc; Mestres, Carlos A.; Miró, José M.; Moreno, Asuncion; Ninot, Salvador; Paré, Carlos; Pericas, Joan; Ramirez, Jose; Rovira, Irene; Sitges, Marta; Anguera, Ignasi; Font, Bernat; Guma, Joan Raimon; Bermejo, Javier; Bouza, Emilio; Fernández, Miguel Angel Garcia; Gonzalez-Ramallo, Victor; Marín, Mercedes; Muñoz, Patricia; Pedromingo, Miguel; Roda, Jorge; Rodríguez-Créixems, Marta; Solis, Jorge; Almirante, Benito; Fernandez-Hidalgo, Nuria; Tornos, Pilar; de Alarcón, Arístides; Parra, Ricardo; Alestig, Eric; Johansson, Magnus; Olaison, Lars; Snygg-Martin, Ulrika; Pachirat, Orathai; Pachirat, Pimchitra; Pussadhamma, Burabha; Senthong, Vichai; Casey, Anna; Elliott, Tom; Lambert, Peter; Watkin, Richard; Eyton, Christina; Klein, John L.; Bradley, Suzanne; Kauffman, Carol; Bedimo, Roger; Chu, Vivian H.; Corey, G. Ralph; Crowley, Anna Lisa; Douglas, Pamela; Drew, Laura; Fowler, Vance G.; Holland, Thomas; Lalani, Tahaniyat; Mudrick, Daniel; Samad, Zaniab; Sexton, Daniel; Stryjewski, Martin; Wang, Andrew; Woods, Christopher W.; Lerakis, Stamatios; Cantey, Robert; Steed, Lisa; Wray, Dannah; Dickerman, Stuart A.; Bonilla, Hector; DiPersio, Joseph; Salstrom, Sara-Jane; Baddley, John; Patel, Mukesh; Peterson, Gail; Stancoven, Amy; Afonso, Luis; Kulman, Theresa; Levine, Donald; Rybak, Michael; Cabell, Christopher H.; Baloch, Khaula; Chu, Vivian H.; Corey, G. Ralph; Dixon, Christy C.; Fowler, Vance G.; Harding, Tina; Jones-Richmond, Marian; Pappas, Paul; Park, Lawrence P.; Redick, Thomas; Stafford, Judy; Anstrom, Kevin; Athan, Eugene; Bayer, Arnold S.; Cabell, Christopher H.; Chu, Vivian H.; Corey, G. Ralph; Fowler, Vance G.; Hoen, Bruno; Karchmer, A. W.; Miró, José M.; Murdoch, David R.; Sexton, Daniel J.; Wang, Andrew; Bayer, Arnold S.; Cabell, Christopher H.; Chu, Vivian; Corey, G. Ralph; Durack, David T.; Eykyn, Susannah; Fowler, Vance G.; Hoen, Bruno; Miró, José M.; Moreillon, Phillipe; Olaison, Lars; Raoult, Didier; Rubinstein, Ethan; Sexton, Daniel J.

    2015-01-01

    Background. The impact of early valve surgery (EVS) on the outcome of Staphylococcus aureus (SA) prosthetic valve infective endocarditis (PVIE) is unresolved. The objective of this study was to evaluate the association between EVS, performed within the first 60 days of hospitalization, and outcome of SA PVIE within the International Collaboration on Endocarditis–Prospective Cohort Study. Methods. Participants were enrolled between June 2000 and December 2006. Cox proportional hazards modeling that included surgery as a time-dependent covariate and propensity adjustment for likelihood to receive cardiac surgery was used to evaluate the impact of EVS and 1-year all-cause mortality on patients with definite left-sided S. aureus PVIE and no history of injection drug use. Results. EVS was performed in 74 of the 168 (44.3%) patients. One-year mortality was significantly higher among patients with S. aureus PVIE than in patients with non–S. aureus PVIE (48.2% vs 32.9%; P = .003). Staphylococcus aureus PVIE patients who underwent EVS had a significantly lower 1-year mortality rate (33.8% vs 59.1%; P = .001). In multivariate, propensity-adjusted models, EVS was not associated with 1-year mortality (risk ratio, 0.67 [95% confidence interval, .39–1.15]; P = .15). Conclusions. In this prospective, multinational cohort of patients with S. aureus PVIE, EVS was not associated with reduced 1-year mortality. The decision to pursue EVS should be individualized for each patient, based upon infection-specific characteristics rather than solely upon the microbiology of the infection causing PVIE. PMID:25389255

  5. Impact of early valve surgery on outcome of Staphylococcus aureus prosthetic valve infective endocarditis: analysis in the International Collaboration of Endocarditis-Prospective Cohort Study.

    PubMed

    Chirouze, Catherine; Alla, François; Fowler, Vance G; Sexton, Daniel J; Corey, G Ralph; Chu, Vivian H; Wang, Andrew; Erpelding, Marie-Line; Durante-Mangoni, Emanuele; Fernández-Hidalgo, Nuria; Giannitsioti, Efthymia; Hannan, Margaret M; Lejko-Zupanc, Tatjana; Miró, José M; Muñoz, Patricia; Murdoch, David R; Tattevin, Pierre; Tribouilloy, Christophe; Hoen, Bruno

    2015-03-01

    The impact of early valve surgery (EVS) on the outcome of Staphylococcus aureus (SA) prosthetic valve infective endocarditis (PVIE) is unresolved. The objective of this study was to evaluate the association between EVS, performed within the first 60 days of hospitalization, and outcome of SA PVIE within the International Collaboration on Endocarditis-Prospective Cohort Study. Participants were enrolled between June 2000 and December 2006. Cox proportional hazards modeling that included surgery as a time-dependent covariate and propensity adjustment for likelihood to receive cardiac surgery was used to evaluate the impact of EVS and 1-year all-cause mortality on patients with definite left-sided S. aureus PVIE and no history of injection drug use. EVS was performed in 74 of the 168 (44.3%) patients. One-year mortality was significantly higher among patients with S. aureus PVIE than in patients with non-S. aureus PVIE (48.2% vs 32.9%; P = .003). Staphylococcus aureus PVIE patients who underwent EVS had a significantly lower 1-year mortality rate (33.8% vs 59.1%; P = .001). In multivariate, propensity-adjusted models, EVS was not associated with 1-year mortality (risk ratio, 0.67 [95% confidence interval, .39-1.15]; P = .15). In this prospective, multinational cohort of patients with S. aureus PVIE, EVS was not associated with reduced 1-year mortality. The decision to pursue EVS should be individualized for each patient, based upon infection-specific characteristics rather than solely upon the microbiology of the infection causing PVIE. © The Author 2014. Published by Oxford University Press on behalf of the Infectious Diseases Society of America. All rights reserved. For Permissions, please e-mail: journals.permissions@oup.com.

  6. Relapse of enterococcal prosthetic valve endocarditis with aortic root abscess following treatment with daptomycin in a patient not fit for surgery.

    PubMed

    Enoch, D A; Phillimore, N; Karas, J A; Horswill, L; Mlangeni, D A

    2010-04-01

    Daptomycin is a novel lipopeptide with activity against Gram-positive organisms including enterococci. It is licensed for the treatment of Staphylococcus aureus bacteraemia and right-sided endocarditis, but not endocarditis due to Enterococcus spp. We report a case of enterococcal prosthetic valve endocarditis with an aortic root abscess in an elderly patient who was not fit for surgery. The patient's endocarditis relapsed 9 weeks after a 6 week course of daptomycin.

  7. Design and Evaluation of a Prosthetic Knee Joint Using the Geared Five-Bar Mechanism.

    PubMed

    Sun, Yuanxi; Ge, Wenjie; Zheng, Jia; Dong, Dianbiao

    2015-11-01

    This paper presents the mechanical design, dynamics analysis and ankle trajectory analysis of a prosthetic knee joint using the geared five-bar mechanism. Compared with traditional four-bar or six-bar mechanisms, the geared five-bar mechanism is better at performing diverse movements and is easy to control. This prosthetic knee joint with the geared five-bar mechanism is capable of fine-tuning its relative instantaneous center of rotation and ankle trajectory. The centrode of this prosthetic knee joint, which is mechanically optimized according to the centrode of human knee joint, is better in the bionic performance than that of a prosthetic knee joint using the four-bar mechanism. Additionally, the stability control of this prosthetic knee joint during the swing and stance phase is achieved by a motor. By adjusting the gear ratio of this prosthetic knee joint, the ankle trajectories of both unilateral and bilateral amputees show less deviations from expected than that of the four-bar knee joint.

  8. Atypical Early Aspergillus Endocarditis Post Prosthetic Mitral Valve Repair: A Case Report

    PubMed Central

    Abuzaid, Ahmed AbdulAziz; Zaki, Mahmood; Tarif, Habib

    2015-01-01

    A 64-year-old female operated 1 month previous for mitral valve repair presented with acute respiratory distress and dyspnea. Echocardiography showed large echogenic valvular mass measuring 2.3 × 1.3 cm with severe mitral regurgitation and dehiscence of the mitral ring posteriorly. The mass was attached subvalvularly to the ventricular septal-free wall and eroding through it, which required complete aggressive dissection of the infected tissues. Diagnosis was confirmed after resection of the valve by multiple negative blood cultures and positive valvular tissue for Aspergillus fumigatus endocarditis. She was treated with high dose of voriconazole for 3 months. Her postoperative period was complicated by acute-on-chronic renal failure. She responded very well to the management. PMID:25838877

  9. Current status of the mechanical valve and bioprosthesis in Japan.

    PubMed

    Tokunaga, Shigehiko; Tominaga, Ryuji

    2008-01-01

    The American College of Cardiology/American Heart Association guidelines for the management of patients with valvular heart disease were revised in 2006. These guidelines are introduced in this review, and the current status of the mechanical valve, bioprosthesis, and treatment of valvular heart disease are described based on the new guidelines as compared with the guidelines of 1998. The trend in valve selection in aortic valve replacement in the United States has been toward bioprosthesis, away from the mechanical valve. The reasons are: 1) current bioprostheses appear to have lower rates of structural valve deterioration, 2) the risks of reoperation have continued to decrease, 3) patients undergoing AVR today represent an older population than those in studies in randomized trials, 4) young patients undergoing AVR are often reluctant to accept warfarin therapy, 5) some large comparative trials have shown apparent survival benefit for patients receiving bioprostheses. In Japan, the use of tissue valves has been increasing and may continue to increase owing to the nation's aging population and to the reasons mentioned above. However, more patients received mechanical valves than bioprostheses for mitral valve replacement both in the United States and in Japan. The number of mitral valve repair cases has increased more than that of valve replacement. In selection of valve prosthesis for valve surgery, it is important that patients should decide by themselves based on mutual respect and trust between patient and doctor, with thorough discussion of the possibility of redo surgery and its risks, life-long warfarin intake, quality of life, and the patient's lifestyle and outlook on life.

  10. 18-Fluoro-2-deoxyglucose positron emission tomography-computed tomography: an additional tool in the diagnosis of prosthetic valve endocarditis.

    PubMed

    Ricciardi, Alessandra; Sordillo, Pasquale; Ceccarelli, Laura; Maffongelli, Gaetano; Calisti, Giorgio; Di Pietro, Barbara; Caracciolo, Cristiana Ragano; Schillaci, Orazio; Pellegrino, Antonio; Chiariello, Luigi; Andreoni, Massimo; Sarmati, Loredana

    2014-11-01

    To evaluate the role of 18-fluoro-2-deoxyglucose positron emission tomography-computed tomography ((18)F-FDG-PET-CT) in the diagnosis of infectious endocarditis (IE). We retrospectively examined 27 consecutive patients who were admitted to the Infectious Diseases Department of Tor Vergata University Hospital between 2009 and 2013 with a suspicion of IE. The final IE diagnosis was defined according to the modified Duke criteria, and the microbiological and diagnostic results were collected for each patient. Twenty out of 27 patients had a suspected prosthetic valve endocarditis (PVE) and seven had a suspected native valve endocarditis (NVE). Twenty-five out of 27 patients (92%) had a confirmed diagnosis of IE (18/25 PVE and 7/25 NVE); 16 had a positive echocardiography evaluation and 16 had positive (18)F-FDG-PET-CT findings. Echocardiography showed a higher sensitivity as a diagnostic tool for the detection of IE compared to (18)F-FDG-PET-CT (80% vs. 55%). However, a greater number of PVE had positive (18)F-FDG-PET-CT results compared to those with positive echocardiography findings (11/13 vs. 9/13), and overall 89% (16/18) of confirmed PVE resulted (18)F-FDG-PET-CT positive. Analyzing only the cases who underwent transoesophageal echocardiography, (18)F-FDG-PET-CT showed a sensitivity of 85% in PVE (vs. 69% for echocardiography and 77% for the Duke criteria). All seven patients with NVE had a positive echocardiography and negative (18)F-FDG-PET-CT findings (p<0.001). The results of this study further highlight the limitations of echocardiography in the diagnosis of PVE and the potential advantages of (18)F-FDG-PET-CT in these cases.

  11. Apicoaortic conduit for severe hemolytic anemia after aortic valve replacement.

    PubMed

    Hatori, Kyohei; Ohki, Satoshi; Obayashi, Tamiyuki; Koyano, Tetsuya; Yasuhara, Kiyomitsu; Hirai, Hanako

    2015-06-01

    We describe the case of an 82-year-old woman who had undergone aortic mechanical valve replacement for aortic stenosis with a small annulus, and coronary artery bypass grafting. Four years after the operation, she began to experience hemolysis. Prosthetic valve obstruction was observed but there was no paravalvular leakage or aortic regurgitation through the mechanical valve. We elected to perform apicoaortic bypass in this patient with severe hemolytic anemia secondary to a mechanical valve malfunction.

  12. Valve actuating mechanism for internal combustion engine

    SciTech Connect

    Kuroda, Y.

    1987-01-20

    This patent describes an internal combustion engine comprising a cylinder having a bore, a cylinder head fixed relative to the cylinder, and three poppet type valves supported by the cylinder head for reciprocation about respective axes all positioned on the same side of a plane containing the axis of the cylinder bore. It also comprises a single camshaft having three respective cam lobes each associated with a respective of the valves, the camshaft being rotatable about an axis extending parallel to the plane and lying on the same side thereof as the valve axes. A rocker arms means is associated with one of the cam lobes for operating its associated valve, and means is included for directly operating the remainder of the valves from the remaining cam lobes.

  13. [Doppler echocardiography in assessing mechanical and biological heart valve prostheses].

    PubMed

    Minardi, G; Di Segni, M; Boccardi, L; Ferrari, O; Giovannini, E

    1988-02-01

    The study was performed to assess Doppler echocardiographic features of mitral and aortic prosthetic valves of different types with both normal and abnormal function. Two hundred and twenty-three patients with 250 prostheses were studied. Two hundred eight valves (111 mitral, 95 aortic and 2 tricuspid) were considered to be functioning normally after clinical examination, phonocardiography and M-mode and 2D echocardiography. This group enabled us to define normal Doppler echocardiographic findings for different types of prosthesis. In mitral position, peak (p) and mean (m) gradients were lower for disc prostheses and higher for ball and biological prosthetic valves; values of effective orifice area (A), calculated by pressure half-time method, were lower for biological and ball prostheses and higher in disc valves. Results were as follows: St. Jude (p 10.6 mmHg, m 3.9 mmHg, A 2.7 cm2), Duromedics (p 10.6, m 4.3, A 2.8), Björk-Shiley (p 10.4, m 4, A 2.3), Omniscience (p 14.2, m 6.2, A 2.1), Starr-Edwards (p 15.9, m 5.4, A 2.1), Hancock (p 14.7, m 6, A 2), Carpentier (p 13.2, m 5.4, A 1.9). Mild regurgitation, considered "physiological", was found in 2/8 Carpentier valves and in 3/34 St. Jude prostheses. In aortic valves lower peak gradients were found in Lillehei (18.3 mmHg), St. Jude (23.8 mmHg), Björk-Shiley (26 mmHg), Duromedics (27 mmHg) and higher values in Starr-Edwards (30.2 mmHg), Hancock (30 mmHg) and Omniscience (35.5 mmHg) prostheses. Mild regurgitation, considered "physiological", was found in 17% of Omniscience valves, 21% of Hancock, 33% of Duromedics, 45% of St. Jude, 60% of Björk-Shiley prostheses. Hancock mitral valves implanted for over 7 years had a mean gradient higher than valves with a shorter period of implantation (7.6 vs 4.85 mmHg, p less than 0.1), whereas the effective orifice area was similar. Hancock aortic valves implanted for over 7 years had a peak gradient slightly higher than the other group (implantation less than 7 years

  14. [Related research on mechanical property of valve membrane in transcatheter bioprosthesis valve based on the chemical modification and cutting technology].

    PubMed

    Chen, Dakai; Li, Yu; Luo, Qiyi; Liu, Baolin; Chen, Kangmin

    2014-08-01

    The aim of this research is to investigate the preparation method of valve membrane in transcatheter bio- prosthetic valve, and to study the effect of chemical modification and cutting technology to tensile property and suture force property of valve membrane. We carried out a series of processes to perform the tests, such as firstly to test the crosslinking degree of valve membrane using ninhydrin method, then to test the tensile property and suture force property by using Instron's biomechanicAl testing equipment, and then to observe the collagen fiber orientation in valve membrane using Instron's biomechanical testing equipment and using field emission scanning electron microscopy. The study indicated that after the chemical modification, the crosslinking degree, tensile strength and suture force strength increasing rate of valve membrane were 93.78% ± 3. 2%, (8.24 ± 0.79) MPa, 102%, respectively. The valve membrane had a better biomechanical property and would be expected to become valve membrane in transcatheter bioprosthesis valve.

  15. [Related research on mechanical property of valve membrane in transcatheter bioprosthesis valve based on the chemical modification and cutting technology].

    PubMed

    Chen, Dakai; Li, Yu; Luo, Qiyi; Liu, Baolin; Chen, Kangmin

    2014-08-01

    The aim of this research is to investigate the preparation method of valve membrane in transcatheter bio- prosthetic valve, and to study the effect of chemical modification and cutting technology to tensile property and suture force property of valve membrane. We carried out a series of processes to perform the tests, such as firstly to test the crosslinking degree of valve membrane using ninhydrin method, then to test the tensile property and suture force property by using Instron's biomechanicAl testing equipment, and then to observe the collagen fiber orientation in valve membrane using Instron's biomechanical testing equipment and using field emission scanning electron microscopy. The study indicated that after the chemical modification, the crosslinking degree, tensile strength and suture force strength increasing rate of valve membrane were 93.78% ± 3. 2%, (8.24 ± 0.79) MPa, 102%, respectively. The valve membrane had a better biomechanical property and would be expected to become valve membrane in transcatheter bioprosthesis valve.

  16. A rare case of Mycobacterium abscessus subspecies abscessus prosthetic valve endocarditis and the clinical importance of inducible erm(41) gene testing.

    PubMed

    Beatty, Norman; Brown, Craig; Zangeneh, Tirdad; Al Mohajer, Mayar

    2017-06-13

    A 56-year-old man with a history of injection drug use and two prior episodes of native valve infective endocarditis presented with dyspnoea on exertion. Our preliminary work-up revealed bacteraemia with reported growth of 'Mycobacterium abscessus group' on multiple blood cultures. The patient was later found to have eustachian valve and prosthetic pulmonic valve endocarditis. Initially, he responded to standard antimycobacterial therapy for rapidly growing mycobacteria (RGM) with supporting laboratory susceptibilities. However, he later developed refractory disease and persistent bacteraemia in the setting of these alleged susceptible antibiotics. Further molecular testing revealed a functional and inducible erm(41) gene which confers macrolide resistance. A subspecies analysis of the M abscessus group revealed the subspecies to be abscessus We present a challenging case of M abscessus subsp. abscessus bacteraemia and prosthetic valve endocarditis with further discussion on treatment and management of this infection along with the taxonomic complexity of this ubiquitous RGM. © BMJ Publishing Group Ltd (unless otherwise stated in the text of the article) 2017. All rights reserved. No commercial use is permitted unless otherwise expressly granted.

  17. Valve actuating mechanism for internal combustion engine

    SciTech Connect

    Tsuchida, N.

    1986-06-03

    A valve train for an internal combustion engine is described having a cylinder head assembly, a first poppet valve supported by the cylinder head assembly for reciprocation along an axis defined by its stem, a second poppet valve supported by the cylinder head assembly for reciprocation along an axis defined by its stem, a camshaft supported by the cylinder head assembly for rotation about a rotational axis intersected by the first poppet valve stem axis, cam means on the camshaft, a tappet slidably supported by the cylinder head assembly and associated with the cam means and the first valve for opening directly the first valve, a rocker arm supported for pivotal movement and associated with the cam means for pivoting the rocker arm, and means on the rocker arm operative to actuate the second valve upon pivotal movement of the rocker arm. The improvement described here consists of the rocker arm being pivotally supported by a rocker arm shaft carried by the cylinder head assembly and lubricant passage means extending through the cylinder head assembly and through the rocker arm shaft for lubricating the pivotal support for the rocker arm and the sliding support for the tappet.

  18. Cardiovascular prosthetic surgery: an analysis of cellular and molecular patterns underlying valve implantation failure.

    PubMed

    Mazzarella, Gennaro; Bianco, Andrea; Lucariello, Angela; Savarese, Leonilde; Fiumarella, Angelamaria; Cerasuolo, Flavio; Ferraraccio, Franca; De Luca, Antonio

    2012-01-01

    Cardiac valves have a very complex microscopic architecture, this is due to the presence of many cell types and to the variegated stroma. From a morphological point of view, both physiological and pathological processes clearly show there to be an anatomic continuity between valve leaflets and perivalvular tissues; indeed, both component should be taken into consideration during thrombotic processes and in fibrous tissue formation. At present, morphological features are well known and classified, while little is known about histogenetic features: fibrous tissue formation and the role of the various types of adhesion molecules and cells which participate in this process still have to be fully elucidated. In the current study, we focused on the histological analysis of the pannus. In particular, we demonstrated that the true connective nature of the exuberant fibrous tissue was entirely composed of collagen/fibronectin fibre bundles and fibroblasts. Moreover we observed that the phlogistic infiltrates were composed of immune cells, mainly represented by CD4(+) and CD8(+) T lymphocytes. Finally we also tried to assess not only the degree of endothelial layer loss, but also the extent of revascularization in the exuberant fibrous tissue.

  19. Diagnostic approach to assessment of valvular heart disease using magnetic resonance imaging, part II: a practical approach for native and prosthetic heart valve stenosis

    PubMed Central

    Chaothawee, Lertlak

    2012-01-01

    MRI is already an established diagnostic modality for assessing valvular stenosis although it is not usually used as the initial non-invasive test. The preferred diagnostic modality for valvular stenosis is currently echocardiography. However, MRI has been offered as a good alternative test in the event of inconclusive echocardiography results. During the course of valvular stenosis, the valve orifice area decreases and the pressure gradient across the diseased valve increases. Valvular orifice area is the major core indicator for valvular stenosis severity grading. Compared with valvular regurgitation, assessment with MRI for valvular stenosis is less complicated. The aim of this article is to detail the MRI techniques in assessing native and prosthetic heart valve stenosis. PMID:27326061

  20. Valve operating mechanism for internal combustion and like-valved engines

    SciTech Connect

    Moloney, P.J.

    1986-06-10

    A valve operating mechanism is described for an internal combustion engine comprising of a piezo-electric actuating device arranged to drive an engine valve opening directly into a combustion chamber by the expansion of the piezo-electric actuating device such that expansion of the piezo-electric actuating device provides the sole motive force for opening the valve and control means to control an electrical feed to the piezo-electric actuating device in accordance with parameters of engine operation fed to it.

  1. Pinch-force-magnification mechanism of low degree of freedom EMG prosthetic hand for children.

    PubMed

    Ye, Hesong; Sakoda, Shintaro; Jiang, Yinlai; Morishita, Soichiro; Yokoi, Hiroshi

    2015-01-01

    EMG prosthetic hands are being extensively studied for the disabled who need them not only for cosmesis but also for the functions to help them with basic daily activities. However, most EMG prosthetic hands are developed for adults. Since the early use of prosthetic hands is important for the children to accept and adapt to them, we are developing low degrees of freedom (DoF) prosthetic hand that is suitable for children. Due to the limited size of a child's hand, the servo motor which drives the MP joint are small-sized and low-power. Hence, a pinch-force-magnification mechanism is required to improve the pinch force of the EMG prosthetic hand. In this paper we designed a wire-driven mechanism which can magnify pinch force by increasing the length of the MP joint's moment arm. Pinch force measurement experiment validated that the pinch force of the prosthetic hand with the mechanism is more than twice of that of the hand with direct drive.

  2. A mechanical heart valve is the best choice

    PubMed Central

    Jaffer, Iqbal H; Whitlock, Richard P

    2016-01-01

    The choice of prosthesis type in patients with valvular heart disease should always be individualised. The treating heart team must weigh the concerns surrounding durability of bioprosthetic valves compared with mechanical valves and the need for lifelong anticoagulation required with mechanical valves. In general, guidelines recommend that patients under the age of 60 would benefit from a mechanical valve, and those over 70 would benefit from a bioprosthetic valve. We would argue, in this context, that the most appropriate choice for this patient would be undertaking a mitral valve replacement with a mechanical prosthesis. This recommendation is based on two considerations: first, there is a high likelihood of failure of a bioprosthesis within an unacceptably short period of time, which would then necessitate a higher risk reoperation. Second, there is high likelihood of needing long-term anticoagulation in a patient with severe mitral stenosis due to the development of atrial fibrillation. While we do acknowledge the difficulty in managing long-term anticoagulation of patients in rural settings, there have nonetheless been significant advancements in this realm with the use of pharmacist-led thrombosis clinics and point of care international normalised ratio (INR) devices in the treatment of rural patients in low-income and middle-income countries. For these reasons, therefore, we would strongly advocate for a mechanical valve in this 44-year-old patient from a rural setting. PMID:27326236

  3. Bioprosthetic versus mechanical prostheses for valve replacement in end-stage renal disease patients: systematic review and meta-analysis

    PubMed Central

    Zhao, Dong Fang; Zhou, Jessie J.; Karagaratnam, Aran; Phan, Steven; Yan, Tristan D.

    2016-01-01

    Background Patients with end-stage renal disease (ESRD) indicated for dialysis are increasingly requiring cardiac valve surgery. The choice of bioprosthetic or mechanic valve prosthesis for such patients requires careful risk assessment. A systematic review and meta-analysis was performed to assess current evidence available. Methods A comprehensive search from six electronic databases was performed from their inception to February 2015. Results from patients with ESRD undergoing cardiac surgery for bioprosthetic or mechanical valve replacement were identified. Results Sixteen studies with 8,483 patients with ESRD undergoing cardiac valve replacement surgery were included. No evidence of publication bias was detected. Prior angioplasty by percutaneous coronary intervention (PCI) or coronary artery bypass graft (CABG) surgery was significantly higher in the bioprosthetic group compared to the mechanical group (16.0% vs. 12.0%, P=0.04); all other preoperative baseline patient characteristics were similar. There was no significant difference in 30-day mortality or all-cause mortality between the two comparisons. Compared with the mechanical group, the frequency of bleeding (5.2% vs. 6.4%, P=0.04) and risk of thromboembolism (2.7% vs. 12.8%, P=0.02) were significantly lower in the bioprosthetic group. There were similar rates of reoperation and valve endocarditis. Conclusions The present study demonstrated that patients with ESRD undergoing bioprosthetic or mechanical valve replacement had similar mid-long term survival. The bioprosthetic group had lower rates of bleeding and thromboembolism. Further studies are required to differentiate the impact of valve location. The presented results may be applicable for ESRD patients requiring prosthetic valve replacement. PMID:27162649

  4. Risks and benefits of adding anti-platelet therapy to warfarin among patients with prosthetic heart valves: a meta-analysis.

    PubMed

    Massel, D; Little, S H

    2001-02-01

    The objective of this study was to compare the effectiveness and safety of adding dipyridamole or aspirin to warfarin among patients with prosthetic heart valves using meta-analytic techniques. Patients with prosthetic heart valves are at increased risk for valve thrombosis and arterial thromboembolism. Oral anticoagulation alone, or the addition of antiplatelet drugs, has been used to minimize this risk. An important issue is the effectiveness and safety of the latter strategy. A combined MEDLINE and manual search was made for relevant articles from 1966 to November 1999. Standard meta-analysis techniques were used. Ten studies involving 2,199 subjects met the inclusion criteria. Compared with anticoagulation alone, the addition of an antiplatelet agent reduced the risk of thromboembolic events (odds ratio [OR]: 0.41, p < 0.001) and total mortality (OR: 0.49, p < 0.001). The risk of major bleeding was increased when antiplatelet agents were added (OR: 1.50, p = 0.033). For major bleeding, the comparison of trials performed before and after 1990 (OR: 2.23 and 0.88, respectively) showed that the chi-square test for heterogeneity was significant (p = 0.025). The latter trials used low-dose aspirin, suggesting that the risk of bleeding may be lower with contemporary low-dose (100 mg daily) aspirin. Adding antiplatelet therapy, especially low-dose aspirin, to warfarin decreases the risk of systemic embolism or death among patients with prosthetic heart valves. The risk of major bleeding is slightly increased with antiplatelet therapy. Nonetheless, the risk of bleeding appears to have diminished with the lower doses of aspirin used in the more recent trials, resulting in a favorable risk-to-benefit profile.

  5. Achromobacter xylosoxidans, an emerging pathogen in catheter-related infection in dialysis population causing prosthetic valve endocarditis: a case report and review of literature.

    PubMed

    Ahmed, M S; Nistal, C; Jayan, R; Kuduvalli, M; Anijeet, H K I

    2009-03-01

    Dialysis catheter-related infection is a major cause of morbidity and mortality in patients on dialysis. In recent years, there have been reported cases of infections with opportunistic environmental organism, Achromobacter xylosoxidans (AX) causing bacteremia in patients on dialysis. However, no previous such reports on prosthetic valve endocarditis in a dialysis patient with Achromobacter xylosoxidans were found after a Medline search. We report such a case and review the literature. A 69-year-old diabetic man with bioprosthetic aortic valve replacement developed end-stage renal disease following infective endocarditis with Staphylococcus epidermidis. Even though he was treated successfully for his endocarditis, he developed further bacteremia with AX from his peripherally inserted central catheter (PICC) and the line was removed. He had further episodes of bacteremia with AX while having dialysis with tunneled line and the line was also removed. He was re-admitted with pyrexia and vegetations both in mitral and prosthetic aortic valve confirmed with transesophageal echo. His antimicrobial therapy with etrapenum, tigecycline and cotrimoxazole failed. He had both mitral and prosthetic aortic valve replacements but postoperatively developed multiorgan failure and died despite the intensive support. Achromobacter xylosoxidans is an aerobic, Gram-negative bacillus and considered to be an opportunistic pathogen with low virulence. Infective endocarditis is a potentially lethal complication of bacteremia. The choice of appropriate antibiotic is crucial in these cases. AX strains are highly resistant to antibiotics. The organism is usually susceptible to antipseudomonal penicillins, carbapenems and trimethoprim-sulfamethoxazole. AX is an emerging pathogen in catheter-related infection in the dialysis population and, therefore, needs vigilance and prompt treatment. Antimicrobial treatment should include susceptibility and synergy testing. Removal of central intravenous

  6. Detail view of valve mechanisms and goverenor on high pressure ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    Detail view of valve mechanisms and goverenor on high pressure stage engine of unit 43. - Burnsville Natural Gas Pumping Station, Saratoga Avenue between Little Kanawha River & C&O Railroad line, Burnsville, Braxton County, WV

  7. Detail view of steam chest and valve mechanisms for high ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    Detail view of steam chest and valve mechanisms for high pressure stage of unit 40. - Burnsville Natural Gas Pumping Station, Saratoga Avenue between Little Kanawha River & C&O Railroad line, Burnsville, Braxton County, WV

  8. Numerical simulation of flow in mechanical heart valves: grid resolution and the assumption of flow symmetry.

    PubMed

    Ge, Liang; Jones, S Casey; Sotiropoulos, Fotis; Healy, Timothy M; Yoganathan, Ajit P

    2003-10-01

    A numerical method is developed for simulating unsteady, 3-D, laminar flow through a bileaflet mechanical heart valve with the leaflets fixed. The method employs a dual-time-stepping artificial-compressibility approach together with overset (Chimera) grids and is second-order accurate in space and time. Calculations are carried out for the full 3-D valve geometry under steady inflow conditions on meshes with a total number of nodes ranging from 4 x 10(5) to 1.6 x 10(6). The computed results show that downstream of the leaflets the flow is dominated by two pairs of counter-rotating vortices, which originate on either side of the central orifice in the aortic sinus and rotate such that the common flow of each pair is directed away from the aortic wall. These vortices intensify with Reynolds number, and at a Reynolds number of approximately 1200 their complex interaction leads to the onset of unsteady flow and the break of symmetry with respect to both geometric planes of symmetry. Our results show the highly 3-D structure of the flow; question the validity of computationally expedient assumptions of flow symmetry; and demonstrate the need for highly resolved, fully 3-D simulations if computational fluid dynamics is to accurately predict the flow in prosthetic mechanical heart valves.

  9. Limited dose warfarin throughout pregnancy in patients with mechanical heart valve prosthesis: a meta-analysis.

    PubMed

    Hassouna, Ahmed; Allam, Hemat

    2014-06-01

    The continuation of warfarin throughout pregnancy in patients with a mechanical valve prosthesis is a valid anticoagulation regimen, provided that warfarin dose does not exceed 5 mg/day. Two decades after being introduced, the efficacy and safety of this regimen merit evaluation. We performed a systematic review for cases published between January 1991 and January 2013. We compiled our prospective data on 55 pregnancies and calculated pooled estimates (95% confidence interval) of adverse foetal and maternal outcomes. Events were expressed as proportions of total pregnancies, except embryopathy and maternal death, which were related to the number of live births and number of patients, respectively. There were 494 eligible pregnancies reported in 11 studies. The rate of embryopathy was 0.9% (0.4-2.4%) and most of the 13.4% (8.4-24.7%) foetal losses were due to the 12.8% (7.7-22.7%) rate of spontaneous abortion. No maternal mortality was encountered (0-1.3%) but 0.6% (0.3-2%) prosthetic valve thrombosis, 1.8% (1.1-3.6%) total thromboembolic events and 3.4% (2-5.1%) major maternal bleeding events were recorded. Foetal loss, spontaneous abortions and foetal embryopathy dropped to 8.1% (2.9-13.7%), 7.3% (3.1-11.8%) and 0.6% (0.1-2.1%) among the 344 pregnancies (69.6%) observed in the 6 prospective studies (54.5%). Prosthetic valve thrombosis (0.6%; 01-2%), total thromboembolic (2.3%; 1.2-4.6%) and major bleeding events (2.9%; 1.8-6%) remained comparable with overall results. Foetal embryopathy and prosthetic valve thrombosis were not robust on sensitivity analysis, regardless of the study design. A prospective subgroup of 96 patients (19.4%) received smaller warfarin dose, through targeting a lower international normalized ratio (INR) between 1.5 and 2.5. The associated rate of foetal loss (2.1%; 0.5-6.9%) was significantly lower than that observed in the remaining patients targeting a higher INR between 2.5 and 3.5 (16.1%; 13.1-34.4%). Adverse maternal outcomes were

  10. Laser induced periodic surface structures on pyrolytic carbon prosthetic heart valve

    NASA Astrophysics Data System (ADS)

    Stepak, Bogusz D.; Łecka, Katarzyna M.; Płonek, Tomasz; Antończak, Arkadiusz J.

    2016-12-01

    Laser-induced periodic surface structures (LIPSS) can appear in different forms such as ripples, grooves or cones. Those highly periodic wavy surface features which are frequently smaller than incident light wavelength bring possibility of nanostructuring of many different materials. Furthermore, by changing laser parameters one can obtain wide spectrum of periodicities and geometries. The aim of this research was to determine possibility of nanostructuring pyrolytic carbon (PyC) heart valve leaflets using different irradiation conditions. The study was performed using two laser sources with different pulse duration (15 ps, 450 fs) as well as different wavelengths (1064, 532, 355 nm). Both low and high spatial frequency LIPSS were observed for each set of irradiation parameters. In case femtosecond laser pulses we obtained deep subwavelength ripple period which was even ten times smaller than applied wavelength. Obtained ripple period was ranging from 90 up to 860 nm. Raman spectra revealed the increase of disorder after laser irradiation which was comparable for both pico- and femtosecond laser.

  11. Combination of a Giant Dissected Ascending Aortic Aneurysm with Multiple Fistulae into the Cardiac Chambers Caused by Prosthetic Aortic Valve Endocarditis.

    PubMed

    Sabzi, Feridoun; Faraji, Reza

    2016-02-01

    The combination of a dissected ascending aortic aneurysm (AA) with multiple fistulae to the periaortic root structures is a life-threatening complication that occurs rarely after infective endocarditis of the prosthetic aortic valve. Many risk factors are potentially associated with this complication, including aortic diameter, connective tissue disease of the aortic wall, hypertension and infection. We report a rare case of dissected ascending AA with fistulae to the left atrium and pulmonary artery and a paravalvular leak in a 47-year-old woman with a history of an aortic valve replacement. The patient had presented to the Imam Ali Hospital, Kermanshah, Iran, in January 2015 with clinical features of heart failure. After initially being treated for congestive heart failure, she underwent open-heart surgery via a classic Bentall procedure and double fistula closure. She was discharged 23 days after the operation in good condition. A six-month follow-up showed normal functioning of the composite conduit prosthetic valve and no fistulae recurrence.

  12. A Study on the Mechanism for Cavitation in the Mechanical Heart Valves with an Electrohydraulic Total Artificial Heart

    NASA Astrophysics Data System (ADS)

    Lee, Hwansung; Tsukiya, Tomonori; Homma, Akihiko; Kamimura, Tadayuki; Tatsumi, Eisuke; Taenaka, Yoshiyuki; Kitamura, Soichiro

    It has been conceived that the mechanical heart valves mounted in an artificial heart close much faster than in vivo use, resulting in cavitation bubbles formation. In this study, the mechanisms for cavitation in mechanical heart valves (MHVs) is investigated with monoleaflet and bileaflet valves in the mitral position with an electrohydraulic total artificial heart (EHTAH). The valve-closing velocity and pressure-drop through the valve were done, and a high-speed video camera was employed to investigate the mechanism for MHVs cavitation. The valve-closing velocity and pressure-drop of the bileaflet valves were less than that of the monoleaflet valves. Most of the cavitation bubbles in the monoleaflet valves were observed next to the edge of the valve stop and the inner side of the leaflet. With the bileaflet valves, cavitation bubbles were concentrated along the leaflet tip. Also, the number density of cavitation bubbles in the bileaflet valves was less than that of the monoleaflet valves. The number density of cavitation bubbles increased with an increase in the valve-closing velocity and the valve stop area. It is established that squeeze flow holds the key to cavitation in the mechanical heart valve. In a viewpoint of squeeze flow, the bileaflet valve with slow valve-closing velocity and small valve stop area, is safer to prevent of blood cell damage than the monoleaflet valves.

  13. Aortic root replacement using a homograft for recurrent valve endocarditis.

    PubMed

    Bashar, Abul Hasan Muhammad; Kazui, Teruhisa; Washiyama, Naoki; Yamashita, Katsushi; Terada, Hitoshi; Ohkura, Kazuhiro

    2002-09-01

    Prosthetic valve endocarditis is a relatively rare condition associated with high mortality. Endocarditis affecting 2 successive mechanical valves at the aortic position has not, to the best of our knowledge, been described. We reported such a patient whose condition was further complicated by mitral regurgitation, pulmonary hypertension, worsening heart failure, and cardiac conduction abnormalities. Considering the failure of 2 previous mechanical valves, we conducted a homograft replacement of the aortic root with coronary reattachment. Mitral regurgitation was treated by annuloplasty. The patient's early postoperative course was uneventful and he was doing well 16 months after surgery. We discuss the overall treatment strategy for recurrent prosthetic valve endocarditis and potential homograft advantages.

  14. Mechanism of piezoelectric micropump with four flexible valves

    NASA Astrophysics Data System (ADS)

    Wei, Changzhi; Wei, Shoushui; Ren, Xiaofei

    2017-06-01

    A piezoelectric micropump with four flexible valves is proposed and its mechanism is researched. In the micropump chamber four asymmetric flexible valves are used to achieve single direction flow. The instantaneous velocities are analyzed and the peak input and output velocities are 0.14 m/s and 0.2 m/s respectively. The net flow rate is calculated, which is about 2.5×10-11m3/s. Due to the low operating frequency, flexible valves structure, no heat and no restriction on transport fluid type, this kind of micropump can be used for liquid transport and other biological sample containing DNA.

  15. Superimposition of a Mechanical Valve on an Impacted Aortic Bioprosthesis

    PubMed Central

    Raffa, Hassan; Al-Ibrahim, K.; Sorefan, A. Aniff; Narayanan, Lakshmi

    1991-01-01

    During reoperation for replacement of a regurgitant aortic bioprosthesis (a 23-mm bovine pericardial valve), it was judged that total removal of the valve would be difficult, and hazardous to the patient. Therefore, its leaflets were excised and its sewing ring left in situ. A 21-mm Carbomedics bileaflet mechanical valve was sutured to the bioprosthetic sewing ring and implanted in the orifice of the bioprosthesis, resulting in excellent hemodynamic performance. We report this new technique to illustrate its feasibility, safety, and efficiency, as an alternative to complete removal of defective prostheses in the aortic position. (Texas Heart Institute Journal 1991;18:199-201) Images PMID:15227480

  16. Valve operating and interrupting mechanism for internal combustion engine

    SciTech Connect

    Ajiki, Y.; Kajiwara, S.

    1986-09-23

    A valve operating mechanism is described for an internal combustion engine having a pair of intake or exhaust valves for each engine cylinder, comprising, a camshaft having high speed and low speed cams thereon, a rocker arm shaft having first second and third rocker arms pivotally mounted thereon in mutually adjacent relationship. The first and third rocker arms engage pair of valves, the first and second rocker arms engaging the low speed and high speed cams, respectively. The piston means in the rocker arms is electively shiftable between positions connecting the rocker arms for pivotal movement in unison and disconnecting the rocker arms for independent movement.

  17. Dental procedures, antibiotic prophylaxis, and endocarditis among people with prosthetic heart valves: nationwide population based cohort and a case crossover study.

    PubMed

    Tubiana, Sarah; Blotière, Pierre-Olivier; Hoen, Bruno; Lesclous, Philippe; Millot, Sarah; Rudant, Jérémie; Weill, Alain; Coste, Joel; Alla, François; Duval, Xavier

    2017-09-07

    Objective To assess the relation between invasive dental procedures and infective endocarditis associated with oral streptococci among people with prosthetic heart valves.Design Nationwide population based cohort and a case crossover study.Setting French national health insurance administrative data linked with the national hospital discharge database.Participants All adults aged more than 18 years, living in France, with medical procedure codes for positioning or replacement of prosthetic heart valves between July 2008 and July 2014.Main outcome measures Oral streptococcal infective endocarditis was identified using primary discharge diagnosis codes. In the cohort study, Poisson regression models were performed to estimate the rate of oral streptococcal infective endocarditis during the three month period after invasive dental procedures compared with non-exposure periods. In the case crossover study, conditional logistic regression models calculated the odds ratio and 95% confidence intervals comparing exposure to invasive dental procedures during the three month period preceding oral streptococcal infective endocarditis (case period) with three earlier control periods.Results The cohort included 138 876 adults with prosthetic heart valves (285 034 person years); 69 303 (49.9%) underwent at least one dental procedure. Among the 396 615 dental procedures performed, 103 463 (26.0%) were invasive and therefore presented an indication for antibiotic prophylaxis, which was performed in 52 280 (50.1%). With a median follow-up of 1.7 years, 267 people developed infective endocarditis associated with oral streptococci (incidence rate 93.7 per 100 000 person years, 95% confidence interval 82.4 to 104.9). Compared with non-exposure periods, no statistically significant increased rate of oral streptococcal infective endocarditis was observed during the three months after an invasive dental procedure (relative rate 1.25, 95% confidence interval 0.82 to 1

  18. Culture-negative prosthetic valve endocarditis with concomitant septicemia due to a nontoxigenic Corynebacterium diphtheriae biotype gravis isolate in a patient with multiple risk factors.

    PubMed

    Clinton, Lani Kai; Bankowski, Matthew J; Shimasaki, Teppei; Sae-Ow, Wichit; Whelen, A Christian; O'Connor, Norman; Kim, Wesley; Young, Royden

    2013-11-01

    A 54-year-old female with a prosthetic mitral valve presented with a 3-day history of dizziness, subjective fever, and chills. Blood cultures were positive for a pleomorphic Gram-positive rod. Initial phenotypic testing could only support the identification of a Corynebacterium species. Nucleic acid sequencing (16S rRNA) and matrix-assisted laser desorption ionization-time of flight mass spectrometry (MALDI-TOF MS) were conclusive for Corynebacterium diphtheriae. Definitive phenotypic testing classified the strain as nontoxigenic C. diphtheriae biotype Gravis.

  19. Effects of bileaflet mechanical heart valve orientation on coronary flow

    NASA Astrophysics Data System (ADS)

    Haya, Laura; Tavoularis, Stavros

    2015-11-01

    The aortic sinus is approximately tri-radially symmetric, but bileaflet mechanical heart valves (BMHVs), which are commonly used to replace diseased aortic valves, are bilaterally symmetric. This mismatch in symmetry suggests that the orientation in which a BMHV is implanted within the aortic sinus affects the flow characteristics downstream of it. This study examines the effect of BMHV orientation on the flow in the coronary arteries, which originate in the aortic sinus and supply the heart tissue with blood. Planar particle image velocimetry measurements were made past a BMHV mounted at the inlet of an anatomical aorta model under physiological flow conditions. The complex interactions between the valve jets, the sinus vortex and the flow in the right coronary artery were elucidated for three valve orientations. The coronary flow rate was directly affected by the size, orientation, and time evolution of the vortex in the sinus, all of which were sensitive to the valve's orientation. The total flow through the artery was highest when the valve was oriented with its axis of symmetry intersecting the artery's opening. The findings of this research may assist surgeons in choosing the best orientation for BMHV implantation. The bileaflet valve was donated by St. Jude Medical. Financial support was provided by the Natural Sciences and Engineering Research Council of Canada.

  20. [Mechanic valve prosthesis and pregnancy: Is Phenprocoumon replaceable?].

    PubMed

    Klee, Katharina; Gawaz, Meinrad; Meyer-Zürn, Christine Stefanie

    2016-03-01

    We report the case of a 30-year-old pregnant patient with mechanical valve replacement in mitral and aortic position. She had discontinued Phenprocoumon-treatment in the 5+4 week of pregnancy by herself. Because of rheumatic fever she had undergone a mechanical aortic and mitral valve replacement 12 years ago. Due to a thrombosis of the mitral valve, an acute reoperation had to be done 5 years later. 2 years ago, a partially re-thrombosis of the mechanical mitral valve was treated by intravenous thrombolysis. These complications had been probably due to incomplicance. The patient had experienced 3 abortions before. The vaginal sonography determined an intact gestation. The laboratory test revealed an INR of 1.2. The transesophageal echocardiography showed a partially thrombosed mechanical mitral valve. The abdominal ultrasonography detected an embolic splenic infarction. These findings were consistent with partially thrombosed mechanical mitral valve with thromboembolic splenic infarction among incompetent oral anticoagulation. After initial heparinization with under twice daily control of the partial thromboplastin time the joint decision was made to restart Phenprocoumon (target INR 2.5 to 3.5, and additional ASS 100 mg /day). 9 days later the patient had a missed abortion. An uncomplicated curettage was performed under therapeutic i.v. heparinization. The use of coumarins in pregnancy carries a fetal risk. But it is the most secure anticoagulation after a mechanical valve replacement, especially in high-risk patients. Alternatives are heparins. They don't cross the placenta but are associated with a slightly elevated risk of thromboembolism. © Georg Thieme Verlag KG Stuttgart · New York.

  1. Experimental Investigation of Flow trough a Mechanical Heart Valve

    NASA Astrophysics Data System (ADS)

    Haji-Esmaeili, Farida; Oshkai, Peter

    2006-11-01

    Turbulent flow trough a model of a mechanical heart valve is investigated using digital particle image velocimetry. The valve leaflets are represented by flat plates mounted in a duct. The emphasis is on the effect of the valve design on the platelet activation state associated with the resulting flow field. Global quantitative images corresponding to multiple planes of data acquisition provide insight into the three-dimensional nature of the flow. Turbulent flow structures including jet-like regions and shed vortices are characterized in terms of patterns of instantaneous and time-averaged velocity, vorticity, and streamline topology. Potential of bileaflet heart valves for being thrombogenic is assessed by quantitative comparison of the associated flow fields in terms of maximum values of turbulent stresses and platelet activation states.

  2. Fluid Mechanics of Heart Valves and Their Replacements

    NASA Astrophysics Data System (ADS)

    Sotiropoulos, Fotis; Le, Trung Bao; Gilmanov, Anvar

    2016-01-01

    As the pulsatile cardiac blood flow drives the heart valve leaflets to open and close, the flow in the vicinity of the valve resembles a pulsed jet through a nonaxisymmetric orifice with a dynamically changing area. As a result, three-dimensional vortex rings with intricate topology emerge that interact with the complex cardiac anatomy and give rise to shear layers, regions of recirculation, and flow instabilities that could ultimately lead to transition to turbulence. Such complex flow patterns, which are inherently valve- and patient-specific, lead to mechanical forces at scales that can cause blood cell damage and thrombosis, increasing the likelihood of stroke, and can trigger the pathogenesis of various life-threatening valvular heart diseases. We summarize the current understanding of flow phenomena induced by heart valves, discuss their linkage with disease pathways, and emphasize the research advances required to translate in-depth understanding of valvular hemodynamics into effective patient therapies.

  3. Treatment of mechanical aortic valve thrombosis with heparin and eptifibatide.

    PubMed

    Vora, Amit N; Gehrig, Thomas; Bashore, Thomas M; Kiefer, Todd L

    2014-07-01

    A 75-year old woman with a history of coronary disease status post 3-vessel coronary artery bypass grafting (CABG) 8 years ago and a repeat one-vessel CABG 2 years ago in the setting of aortic valve replacement with a #19 mm St. Jude bileaflet mechanical valve for severe aortic stenosis presented with two to three weeks of progressive dyspnea and increasing substernal chest discomfort. Echocardiography revealed a gradient to 31 mmHg across her aortic valve, increased from a baseline of 13 mmHg five months previously. Fluoroscopy revealed thrombosis of her mechanical aortic valve. She was not a candidate for surgery given her multiple comorbidities, and fibrinolysis was contraindicated given a recent subdural hematoma 1 year prior to presentation. She was treated with heparin and eptifibatide and subsequently demonstrated resolution of her aortic valve thrombosis. We report the first described successful use of eptifibatide in addition to unfractionated heparin for the management of subacute valve thrombosis in a patient at high risk for repeat surgery or fibrinolysis.

  4. Prosthetic urinary sphincter

    NASA Technical Reports Server (NTRS)

    Helms, C. R.; Smyly, H. M. (Inventor)

    1981-01-01

    A pump/valve unit for controlling the inflation and deflation of a urethral collar in a prosthetic urinary sphincter device is described. A compressible bulb pump defining a reservoir was integrated with a valve unit for implantation. The valve unit includes a movable valve member operable by depression of a flexible portion of the valve unit housing for controlling fluid flow between the reservoir and collar; and a pressure sensing means which operates the valve member to relieve an excess pressure in the collar should too much pressure be applied by the patient.

  5. Interface mechanics in lower-limb external prosthetics: a review of finite element models.

    PubMed

    Zachariah, S G; Sanders, J E

    1996-12-01

    The distribution of mechanical stress at the interface between a residual limb and prosthetic socket is an important design consideration in lower-limb prosthetics. Stresses must be distributed so that the amputee is stable and comfortable, while avoiding trauma to the tissues of the residual limb. Numerical estimation of the stresses at the interface through finite element (FE) modeling can potentially provide researchers and prosthetists with a tool to aid in the design of the prosthetic socket. This review addresses FE modeling of interface stresses in lower-limb external prosthetics. The modeling methodologies adopted by analysts are described. Verification of FE estimates of interface stress against experimental data by different analysts is presented and the likely sources of error discussed. While the performance of the models is encouraging, there are definite limitations to all of them, necessitating further improvements. Parametric analysis of the sensitivity of interface stress to model parameters provides a tool to identify model weaknesses and to suggest possible refinements. Parametric analyses by different analysts are also presented and potential refinements discussed. Finally, directions for future work in prosthetic FE modeling are suggested.

  6. Hemocompatibility of styrenic block copolymers for use in prosthetic heart valves.

    PubMed

    Brubert, Jacob; Krajewski, Stefanie; Wendel, Hans Peter; Nair, Sukumaran; Stasiak, Joanna; Moggridge, Geoff D

    2016-02-01

    Certain styrenic thermoplastic block copolymer elastomers can be processed to exhibit anisotropic mechanical properties which may be desirable for imitating biological tissues. The ex-vivo hemocompatibility of four triblock (hard-soft-hard) copolymers with polystyrene hard blocks and polyethylene, polypropylene, polyisoprene, polybutadiene or polyisobutylene soft blocks are tested using the modified Chandler loop method using fresh human blood and direct contact cell proliferation of fibroblasts upon the materials. The hemocompatibility and durability performance of a heparin coating is also evaluated. Measures of platelet and coagulation cascade activation indicate that the test materials are superior to polyester but inferior to expanded polytetrafluoroethylene and bovine pericardium reference materials. Against inflammatory measures the test materials are superior to polyester and bovine pericardium. The addition of a heparin coating results in reduced protein adsorption and ex-vivo hemocompatibility performance superior to all reference materials, in all measures. The tested styrenic thermoplastic block copolymers demonstrate adequate performance for blood contacting applications.

  7. Measurements of flow past a bileaflet mechanical heart valve

    NASA Astrophysics Data System (ADS)

    Haya, Laura; Tavoularis, Stavros

    2013-11-01

    A bileaflet mechanical heart valve has been inserted in an axisymmetric model of the aorta within a mock circulation apparatus with physiological pressure and flow variations. The velocity field behind the valve has been measured with laser Doppler velocimetry and particle image velocimetry. The results closely match those reported by similar studies. A triple jet emanated from the valve's orifices and regions of reverse flow formed in the sinus region. Velocity fluctuations were greatest in the shear layers of the jets. The average r.m.s. streamwise velocity fluctuation over the turbulent period was 0.22 m/s; its maximum value was 0.53 m/s and occurred at the onset of deceleration. Measurements with the valve inserted in an anatomical model of the aorta are planned for the near future. The present and future measurements will be compared to determine the effects of the aorta anatomy on the characteristics of flow through bileaflet valves. In particular, measurements of the viscous and turbulent shear stresses will be analyzed to identify possible locations of blood element damage, and regions of recirculation and stagnation will be identified as locations favourable to thrombus growth. The effects of flows in branching arteries and valve orientation will also be investigated. Supported by NSERC.

  8. Ventricular pressure slope and bileaflet mechanical heart valve closure.

    PubMed

    Wu, Z J; Hwang, N H

    1995-01-01

    The maximum left ventricular pressure slope (dP/dt) value has been used by several investigators as the criterion for studying mitral valve closure. In this article, the relationship between the ventricular pressure slope (dP/dt) and the leaflet closing behavior of bileaflet mechanical heart valves (BMV) is investigated. Two current BMVs, the St. Jude Medical 29 mm and CarboMedics 29 mm, installed in the mitral position of a mock circulatory pulsatile flow loop were used as the study model. Under simulated physiologic pressures and flow conditions, the experiment was conducted at 70, 90, and 120 beats/min with corresponding flow rates of 5.0, 6.0, and 7.5 liters/min, respectively. A laser sweeping technique was used to monitor the leaflet closing motion within the last 3 degrees excursion at valve closure. A modified dual beam laser sweeping technique system was used to register the difference of leaflet/housing impact time between the two BMV closing leaflets in asynchronous closure. Common BMV asynchronous closures were found in both BMVs at all three heart rates tested. The second closing leaflet was found to always close at higher velocity than the first. Simultaneous measurements of the ventricular pressure (Pv) and the leaflet closing time showed that Pv exhibited three stage characteristics. In the first stage, Pv gradually increased as the ventricle was filled. A sudden rise of Pv occurred immediately after closing of the first leaflet. The maximum dp/dt occurred in the third stage after closure of both BMV leaflets. The BMV closing behavior and the corresponding Pv pattern were found to depend strongly upon valve type and heart rate. The time averaged ventricular pressure slope (dp/dt) values at 70, 90, and 120 beats/min were about 40, 70, and 150 mmHg/sec for the St. Jude Medical valve and 40, 105, and 205 for the CarboMedics valve during the first closing stage. The maximum dp/dt values were 2670, 4350, and 5000 mmHg/sec for the St. Jude Medical valve

  9. A mechanism to compensate undesired stiffness in joints of prosthetic hands.

    PubMed

    Smit, Gerwin; Plettenburg, Dick; Van der Helm, Frans

    2014-04-01

    Cosmetic gloves that cover a prosthetic hand have a parasitic positive stiffness that counteracts the flexion of a finger joint. Reducing the required input torque to move a finger of a prosthetic hand by compensating the parasitic stiffness of the cosmetic glove. Experimental, test bench. The parasitic positive stiffness and the required input torques of a polyvinyl chloride glove and a silicone glove were measured when flexing a metacarpophalangeal finger joint for 90°. To compensate this positive stiffness, an adjustable compensation mechanism with a negative stiffness was designed and built. A MATLAB model was created to predict the optimal settings of the mechanism, based on the measured stiffness, in order to minimize the required input torque of the total system. The mechanism was tested in its optimal setting with an applied glove. The mechanism reduced the required input torque by 58% for the polyvinyl chloride glove and by 52% for the silicone glove. The total energy dissipation of the joint did not change significantly. This study shows that the undesired positive stiffness in the joint can be compensated with a relatively simple negative stiffness mechanism, which fits inside a finger of a standard cosmetic glove. Clinical relevance This study presents a mechanism that compensates the undesired stiffness of cosmetic gloves on prosthetic hands. As a result, it requires less input force, torque and energy to move the fingers. Application of this mechanism in body-powered hands will reduce the control effort of the user.

  10. 21 CFR 870.3925 - Replacement heart valve.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ...) MEDICAL DEVICES CARDIOVASCULAR DEVICES Cardiovascular Prosthetic Devices § 870.3925 Replacement heart... of the heart's natural valves. This device includes valves constructed of prosthetic materials, biologic valves (e.g., porcine valves), or valves constructed of a combination of prosthetic and biologic...

  11. [Influence of pivot distance on the performance of a mechanic heart valve].

    PubMed

    Zhang, Yong; Wu, Liangliang; Huang, Nan

    2014-10-01

    Based on the analysis of the influence of the valve pivot distance on the performance of mechanical heart valve (MHV), such as the valve opening and closing features, flow field characteristics and the valve assembly properties, value constraints of the valve pivot distance were established, and the reasonable valve was obtained by means of the finite element method. It can be shown that the central flow characteristics of the valve could be enhanced with the increasing of the ratio of pivot distance to valve inner diameter, but the plastic deformation of the ring could be liable to occur in the MHV assembly process. It is proved that the valve of specifications can be designed in similar ratio of pivot distance to valve inner diameter according to the result of the valve performance experiment.

  12. Operating mechanism for dual valves in an internal combustion engine

    SciTech Connect

    Nagahiro, K.; Ishida, A.; Kajiwara, S.

    1987-04-14

    A valve operating mechanism is described for an internal combustion engine having a camshaft, a pair of intake or exhaust valves for each engine cylinder and a rocker shaft, comprising: first and second rocker arms pivotally mounted on the rocker shaft in adjacent relationship and engaging the pair of valves. The first rocker arm engages the camshaft; and piston means in the rocker arms selectively shiftable between positions connecting the rocker arms for pivotal movement in unison and disconnecting the rocker arms for independent movement. The piston means includes two pistons slidably mounted in the first rocker arm with one piston slidable into the second rocker arm for connecting the first and second rocker arms.

  13. Effect of valsalva in the pulmonary prosthetic conduit valve on hemodynamic function in a mock circulatory system.

    PubMed

    Tsuboko, Yusuke; Shiraishi, Yasuyuki; Yamada, Akihiro; Yambe, Tomoyuki; Matsuo, Satoshi; Saiki, Yoshikatsu; Yamagishi, Masaaki

    2015-01-01

    Pulmonary conduit valves are used as one of the surgical treatment methods of congenital heart diseases. We have been designing a sophisticated pulmonary conduit valve for the right ventricular outflow tract reconstruction in pediatric patients. In this study, two types of polyester grafts with or without bulging structures for the conduit valves were used and evaluated from the hemodynamic point of view focusing on the application of these conduit valves in the grown-up congenital heart failure patients. We examined valvular function in the originally developed pulmonary mock circulatory system, which consisted of a pneumatic driven right ventricular model, a pulmonary valve chamber, and an elastic pulmonary compliance model with peripheral vascular resistance units. Prior to the measurement, a bileaflet valve was sutured in each conduit. Each conduit valve was installed in the mock right ventricular outflow portion, and its leaflet motion was obtained by using a high-speed camera synchronously with pressure and flow waveforms. As a result, we could obtain hemodynamic changes in two different types of conduits for pulmonary valves, and it was indicated that the presence of the Valsalva shape might be effective for promoting valvular response in the low cardiac output condition.

  14. [Left Ventricular Rupture during Both Mitral and Aortic Valve Replacements].

    PubMed

    Kurumisawa, Soki; Aizawa, Kei; Takazawa, Ippei; Sato, Hirotaka; Muraoka, Arata; Ohki, Shinnichi; Saito, Tsutomu; Kawahito, Koji; Misawa, Yoshio

    2015-05-01

    A 73-year-old woman on hemodialysis was transferred to our hospital for surgical treatment of heart valve disease. She required both mitral and aortic valve replacement with mechanical valves, associated with tricuspid annuloplasty. After aortic de-clamping, a massive hemorrhage from the posterior atrioventricular groove was observed. Under repeated cardiac arrest, the left atrium was reopened, the implanted mitral prosthetic valve was removed and a type I left ventricular rupture (Treasure classification) was diagnosed. The lesion was directly repaired with mattress stitches and running sutures, using reinforcement materials such as a glutaraldehyde-treated bovine pericardium. To avoid mechanical stress by the prosthetic valve on the repaired site, a mechanical valve was implanted using a translocation method. The patient suffered from aspiration pneumonia and disuse atrophy for 3 months. However, she was doing well at 1 year post-operation.

  15. Mid-term results of small-sized St. Jude Medical Regent prosthetic valves (21 mm or less) for small aortic annulus.

    PubMed

    Mizoguchi, Hiroki; Sakaki, Masayuki; Inoue, Kazushige; Iwata, Takashi; Tei, Keikou; Miura, Takuya

    2013-11-01

    Prosthesis-patient mismatch (PPM) is always of concern when performing aortic valve replacement (AVR) in patients with a small aortic annulus. Although bioprosthetic AVR is preferred in patients older than 65 years, we have experienced cases in elderly patients with a small aortic annulus whereby we could not implant small-sized bioprosthetic valves. We have implanted St. Jude Medical Regent (SJMR) mechanical valves (St. Jude Medical, St. Paul, MN, USA) as necessary, even in elderly patients with no aortic annulus enlargement. We investigated our experiences of AVR with SJMR mechanical valves of 21 mm or less in size. Between January 2006 and December 2009, 40 patients underwent AVR with SJMR mechanical valves ≤21 mm in size: 9 patients received 21-mm valves, 19 received 19-mm valves, and 12 received 17-mm valves. The mean age was 65.9 ± 9.5 years, and 25 patients (62.5 %) were 65 years or older. We evaluated the clinical outcome and the echocardiographic data for each valve size. There was no operative or hospital mortality. The mean duration of clinical follow-up was 31.2 ± 17.6 months. During follow-up, there were no hospitalizations due to heart failure. The cumulative valve-related event-free survival was 93 % at 33 months, and the cumulative hemorrhagic event-free survival was 93 % at 33 months and 84 % at 43 months, using the Kaplan-Meier method. At follow-up, the mean values of the measured effective orifice area (EOA) for the 21-, 19-, and 17-mm prostheses were 2.00 ± 0.22, 1.74 ± 0.37, and 1.25 ± 0.26 cm(2), and the mean measured EOA index (EOAI) were 1.17 ± 0.12, 1.11 ± 0.21 and 0.90 ± 0.22 cm(2)/m(2), respectively. A PPM (EOAI ≤0.85) was documented in 5 patients, all of whom had received a 17-mm SJMR valve. AVR with SJMR valves of 21 mm or less in size appears to show satisfactory clinical and hemodynamic results.

  16. Percutaneous Transcatheter Aortic Disc Valve Prosthesis Implantation: A Feasibility Study

    SciTech Connect

    Sochman, Jan

    2000-09-15

    Purpose: Over the past 30 years there have been experimental efforts at catheter-based management of aortic valve regurgitation with the idea of extending treatment to nonsurgical candidates. A new catheter-based aortic valve design is described.Methods: The new catheter-delivered valve consists of a stent-based valve cage with locking mechanism and a prosthetic flexible tilting valve disc. The valve cage is delivered first followed by deployment and locking of the disc. In acute experiments, valve implantation was done in four dogs.Results: Valve implantation was successful in all four animals. The implanted valve functioned well for the duration of the experiments (up to 3 hr).Conclusion: The study showed the implantation feasibility and short-term function of the tested catheter-based aortic disc valve. Further experimental studies are warranted.

  17. Particle image velocimetry study of pulsatile flow in bi-leaflet mechanical heart valves with image compensation method.

    PubMed

    Shi, Yubing; Yeo, Tony Joon Hock; Zhao, Yong; Hwang, Ned H C

    2006-12-01

    Particle Image Velocimetry (PIV) is an important technique in studying blood flow in heart valves. Previous PIV studies of flow around prosthetic heart valves had different research concentrations, and thus never provided the physical flow field pictures in a complete heart cycle, which compromised their pertinence for a better understanding of the valvular mechanism. In this study, a digital PIV (DPIV) investigation was carried out with improved accuracy, to analyse the pulsatile flow field around the bi-leaflet mechanical heart valve (MHV) in a complete heart cycle. For this purpose a pulsatile flow test rig was constructed to provide the necessary in vitro test environment, and the flow field around a St. Jude size 29 bi-leaflet MHV and a similar MHV model were studied under a simulated physiological pressure waveform with flow rate of 5.2 l/min and pulse rate at 72 beats/min. A phase-locking method was applied to gate the dynamic process of valve leaflet motions. A special image-processing program was applied to eliminate optical distortion caused by the difference in refractive indexes between the blood analogue fluid and the test section. Results clearly showed that, due to the presence of the two leaflets, the valvular flow conduit was partitioned into three flow channels. In the opening process, flow in the two side channels was first to develop under the presence of the forward pressure gradient. The flow in the central channel was developed much later at about the mid-stage of the opening process. Forward flows in all three channels were observed at the late stage of the opening process. At the early closing process, a backward flow developed first in the central channel. Under the influence of the reverse pressure gradient, the flow in the central channel first appeared to be disturbed, which was then transformed into backward flow. The backward flow in the central channel was found to be the main driving factor for the leaflet rotation in the valve

  18. Transfemoral implantation of CoreValve Evolut-R aortic prosthesis in patient with prior ball-cage mechanical mitral valve prosthesis.

    PubMed

    Maluenda, Gabriel; Caorsi, Carlos; Baeza, Cristian

    2016-06-01

    Transcatheter aortic valve replacement remains challenge in patients with ball-cage-type mechanical valve in mitral position. Potential under-expansion of the percutaneous valve and interaction between the mitral ball-cage mechanical valve tilted towards the left ventricular outflow tract and the percutaneous valve adds risk during and after implantation. We report a successful implantation of the novel CoreValve Evolut-R self-expanding in a patient with severe aortic stenosis and a mitral Starr-Edwards mechanical valve implanted 28years ago.

  19. Three-Dimensional Fluid-Structure Interaction Simulation of Bileaflet Mechanical Heart Valve Flow Dynamics

    PubMed Central

    Cheng, Rui; Lai, Yong G.; Chandran, Krishnan B.

    2005-01-01

    The wall shear stress induced by the leaflet motion during the valve-closing phase has been implicated with thrombus initiation with prosthetic valves. Detailed flow dynamic analysis in the vicinity of the leaflets and the housing during the valve-closure phase is of interest in understanding this relationship. A three-dimensional unsteady flow analysis past bileaflet valve prosthesis in the mitral position is presented incorporating a fluid-structure interaction algorithm for leaflet motion during the valve-closing phase. Arbitrary Lagrangian–Eulerian method is employed for incorporating the leaflet motion. The forces exerted by the fluid on the leaflets are computed and applied to the leaflet equation of motion to predict the leaflet position. Relatively large velocities are computed in the valve clearance region between the valve housing and the leaflet edge with the resulting relatively large wall shear stresses at the leaflet edge during the impact-rebound duration. Negative pressure transients are computed on the surface of the leaflets on the atrial side of the valve, with larger magnitudes at the leaflet edge during the closing and rebound as well. Vortical flow development is observed on the inflow (atrial) side during the valve impact-rebound phase in a location central to the leaflet and away from the clearance region where cavitation bubbles have been visualized in previously reported experimental studies. PMID:15636108

  20. Haemodynamic improvement of older, previously replaced mechanical mitral valves by removal of the subvalvular pannus in redo cardiac surgery.

    PubMed

    Kim, Jong Hun; Kim, Tae Youn; Choi, Jong Bum; Kuh, Ja Hong

    2017-01-01

    Patients requiring redo cardiac surgery for diseased heart valves other than mitral valves may show increased pressure gradients and reduced valve areas of previously placed mechanical mitral valves due to subvalvular pannus formation. We treated four women who had mechanical mitral valves inserted greater than or equal to 20 years earlier and who presented with circular pannus that protruded into the lower margin of the valve ring but did not impede leaflet motion. Pannus removal improved the haemodynamic function of the mitral valve.

  1. Multidetector-row computed tomography for prosthetic heart valve dysfunction: is concomitant non-invasive coronary angiography possible before redo-surgery?

    PubMed

    Tanis, Wilco; Suchá, Dominika; Laufer, Ward; Habets, Jesse; van Herwerden, Lex A; Symersky, Petr; Chamuleau, Steven; Budde, Ricardo P J

    2015-06-01

    Retrospective ECG-gated multidetector-row computed tomography (MDCT) is increasingly used for the assessment of prosthetic heart valve (PHV) dysfunction, but is also hampered by PHV-related artefacts/cardiac arrhythmias. Furthermore, it is performed without nitroglycerine or heart rate correction. The purpose was to determine whether MDCT performed before potential redo-PHV surgery is feasible for concomitant coronary artery stenosis assessment and can replace invasive coronary angiography (CAG). PHV patients with CAG and MDCT were identified. Based on medical history, two groups were created: (I) patients with no known coronary artery disease (CAD), (II) patients with known CAD. All images were scored for the presence of significant (>50 %) stenosis. CAG was the reference test. Fifty-one patients were included. In group I (n = 38), MDCT accurately ruled out significant stenosis in 19/38 (50 %) patients, but could not replace CAG in the remaining 19/38 (50 %) patients due to non-diagnostic image quality (n = 16) or significant stenosis (n = 3) detection. In group II (n = 13), MDCT correctly found no patients without significant stenosis, requiring CAG imaging in all. MDCT assessed patency in 16/19 (84 %) grafts and detected a hostile anatomy in two. MDCT performed for PHV dysfunction assessment can replace CAG (100 % accurate) in approximately half of patients without previously known CAD. • Retrospective MDCT is increasingly used for prosthetic heart valve dysfunction assessment • In case of PHV reoperation, invasive coronary angiography is also required • MDCT can replace CAG in 50 % of patients without coronary artery disease • When conclusive for coronary assessment, MDCT stenosis rule out is highly accurate • Replacing CAG saves associated risks of distant embolization of thrombi or vegetations.

  2. Intro to Valve Guide Reconditioning. Automotive Mechanics. Valves. Instructor's Guide [and] Student Guide.

    ERIC Educational Resources Information Center

    Horner, W.

    This instructional package, one in a series of individualized instructional units on tools and techniques for repairing worn valve guides in motor vehicles, provides practical experience for students in working on cylinder heads. Covered in the module are reaming valve guides that are oversized to match a new oversized valve, reaming valve guides…

  3. Noninvasive evaluation of cardiac valve prostheses.

    PubMed

    Kotler, M N; Goldman, A; Parry, W R

    1986-01-01

    Noninvasive techniques are particularly helpful in evaluating the function of mechanical prostheses and tissue valves. Combined phonocardiography with M-mode echocardiography, cinefluoroscopy, and Doppler echocardiography are the most useful noninvasive techniques in differentiating normal from abnormal metallic prosthetic valve function. The intensity of the opening and closing clicks and associated murmurs will depend on the type of prosthetic valve, the heart rate and rhythm, and the underlying hemodynamic status. Arrhythmias and/or conduction disturbances may produce motion patterns that mimic the echocardiographic signs of malfunctioning prosthetic valves. Two-dimensional echocardiography is of limited help in assessing patients with metallic prosthetic valves because of reverberating artifacts and side lobe echoes. However, 2-D echo is extremely useful in excluding underlying left ventricular dysfunction. In addition, 2-D echo allows the determination of the precise alignment of the prosthetic valves so that optimal M-mode evaluation of the disc or poppet motion can be undertaken. Two-dimensional echocardiography also allows diagnosis of pericardial effusion and exclusion of other valvular abnormalities. Differentiation of thrombus formation or tissue ingrowth from paravalvular regurgitation or dehiscence is possible by echophonocardiography, Doppler echocardiography, and cinefluoroscopy. Doppler echocardiography is the most sensitive noninvasive technique in diagnosing paravalvular leaks. In addition, significant obstruction across a prosthetic valve can be determined by calculation of maximal gradient across the obstructed orifice using Doppler echocardiography. The differentiation between "benign physiological regurgitation" from true "pathological regurgitation" by Doppler is not always possible. Disc variance is a potentially serious and lethal problem with the older Beall valves and can be detected readily by a combination of echophonocardiography

  4. The mechanism of action of phenylalanine ammonia-lyase: the role of prosthetic dehydroalanine.

    PubMed Central

    Schuster, B; Rétey, J

    1995-01-01

    Phenylalanine ammonia-lyase (EC 4.3.1.5) from parsley is posttranslationally modified by dehydrating its Ser-202 to the catalytically essential dehydroalanine prosthetic group. The codon of Ser-202 was changed to those of alanine and threonine by site-directed mutagenesis. These mutants and the recombinant wild-type enzyme, after treatment with sodium borohydride, were virtually inactive with L-phenylalanine as substrate but catalyzed the deamination of L-4-nitrophenylalanine, which is also a substrate for the wild-type enzyme. Although the mutants reacted about 20 times slower with L-4-nitrophenylalanine than the wild-type enzyme, their Vmax for L-4-nitrophenylalanine was two orders of magnitude higher than for L-phenylalanine. In contrast to L-tyrosine, which was a poor substrate, DL-3-hydroxyphenylalanine (DL-m-tyrosine) was converted by phenylalanine ammonia-lyase at a rate comparable to that of L-phenylalanine. These results suggest a mechanism in which the crucial step is an electrophilic attack of the prosthetic group at position 2 or 6 of the phenyl group. In the resulting carbenium ion, the beta-HSi atom is activated in a similar way as it is in the nitro analogue. Subsequent elimination of ammonia, concomitant with restoration of both the aromatic ring and the prosthetic group, completes the catalytic cycle. Images Fig. 1 PMID:7667307

  5. Improved technique of transapical aortic valve implantation: "the Berlin addition".

    PubMed

    Pasic, Miralem; Dreysse, Stephan; Drews, Thorsten; Buz, Semih; Unbehaun, Axel; Kukucka, Marian; Mladenow, Alexandar; Hetzer, Roland

    2010-06-01

    Transapical aortic valve implantation carries some degree of uncertainty regarding the definitive valve position. We added angiographic visualization of the aortic root while the prosthetic valve is being slowly deployed. It enables easy correction of the position of the valve so that perfect alignment can be achieved of the relationships between the prosthetic valve, aortic valve annulus, aortic cusps, and the coronary arteries.

  6. Platelet activation through a Bi-leaflet mechanical heart valve

    NASA Astrophysics Data System (ADS)

    Hedayat, Mohammadali; Borazjani, Iman

    2016-11-01

    Platelet activation is one of the major drawbacks of the Mechanical Heart Valves (MHVs) which can increase the risk of thrombus formation in patients. The platelet activation in MHVs can be due to the abnormal shear stress during the systole, the backward leakage flow during the diastole, and the flow through the hinge region. We investigate the contribution of each of the above mechanism to the activation of platelets in MHVs by performing simulations of the flow through the MHV and in the hinge region. The large scale heart valve simulations are performed in a straight aorta using a sharp interface curvilinear immersed boundary method along with a strong-coupling algorithm under physiological flow conditions. In addition, in order to perform the simulation of hinge region the flow field boundary conditions are obtained from the largescale simulations during a whole cardiac cycle. In order to investigate the role of hinge flow on platelet activation in MHVs, a 23mm St. Jude Medical Regent valve hinge with three different gap sizes is tested along with different platelet activation models to ensure the consistency of our results with different activation models. We compare the platelet activation of the hinge region against the bulk of the flow during one cardiac cycle. This work is supported by the American Heart Association Grant 13SDG17220022, and the computational resources were partly provided by Center for Computational Research (CCR) at University at Buffalo.

  7. Actuating mechanism for multiple valve internal combustion engine

    SciTech Connect

    Aoi, K.; Tsuchida, N.

    1986-10-21

    A valve train is described for an internal combustion engine. The valve train has cylinder bore having a bore axis, a first poppet valve supported for reciprocation along a valve axis defined by its stem, and a second poppet valve supported for reciprocation about a valve axis defined by its stem. The valve train also has a camshaft supported for rotation about a rotational axis intersected by the first poppet valve stem axis and extending parallel to a plane containing the bore axis. A cam means of the camshaft is for opening directly the first valve and a rocker arm is supported for pivotal movement. The cam means of the camshaft is for pivoting the rocker arm, and means on the rocker arm is operative to actuate the second valve upon pivotal movement of the rocker arm. The valve axes lies on the same side of the plane as the rotational axis.

  8. VALVE

    DOEpatents

    Arkelyan, A.M.; Rickard, C.L.

    1962-04-17

    A gate valve for controlling the flow of fluid in separate concentric ducts or channels by means of a single valve is described. In one position, the valve sealing discs engage opposed sets of concentric ducts leading to the concentric pipes defining the flow channels to block flow therethrough. In another position, the discs are withdrawn from engagement with the opposed ducts and at the same time a bridging section is interposed therebetween to define concentric paths coextensive with and connecting the opposed ducts to facilitate flow therebetween. A wedge block arrangement is employed with each sealing disc to enable it to engage the ducts. The wedge block arrangement also facilitates unobstructcd withdrawal of the discs out of the intervening space between the sets of ducts. (AEC)

  9. Valve

    DOEpatents

    Cho, Nakwon

    1980-01-01

    A positive acting valve suitable for operation in a corrosive environment is provided. The valve includes a hollow valve body defining an open-ended bore for receiving two, axially aligned, spaced-apart, cylindrical inserts. One insert, designated the seat insert, terminates inside the valve body in an annular face which lies within plane normal to the axis of the two inserts. An elastomeric O-ring seal is disposed in a groove extending about the annular face. The other insert, designated the wedge insert, terminates inside the valve body in at least two surfaces oppositely inclined with respect to each other and with respect to a plane normal to the axis of the two inserts. An elongated reciprocable gate, movable between the two inserts along a path normal to the axis of the two inserts, has a first flat face portion disposed adjacent and parallel to the annular face of the seat insert. The gate has a second face portion opposite to the first face portion provided with at least two oppositely inclined surfaces for mating with respective inclined surfaces of the wedge insert. An opening is provided through the gate which registers with a flow passage through the two inserts when the valve is open. Interaction of the respective inclined surfaces of the gate and wedge insert act to force the first flat face portion of the gate against the O-ring seal in the seat insert at the limits of gate displacement where it reaches its respective fully open and fully closed positions.

  10. Star GK Bileaflet Mechanical Valve Prosthesis-Patient Mismatch After Mitral Valve Replacement: A Chinese Multicenter Clinical Study

    PubMed Central

    Cao, Hua; Qiu, Zhihuang; Chen, Liangwan; Chen, Daozhong; Chen, Qiang

    2015-01-01

    Background The aim of this study was to investigate the incidence and immediate and mid-term effects of heart valve prosthesis-patient mismatch (PPM) after mitral valve replacement using the GK bileaflet mechanical valve. Material/Methods A total of 493 cases of mechanical mitral valve replacement were performed in the departments of cardiac surgery in 7 hospitals from January 2000 to January 2008. The patients included 142 men and 351 women ages 21 to 67 (average age, 48.75). The patients were followed for 3 years after surgery. The effective orifice area index (EOAI), ≤1.2 cm2/m2, was detected during the follow-up period and was defined as PPM. The patients were assigned to either the PPM group or the non-PPM group. Finally, the preoperative, perioperative and postoperative indexes of the 2 groups of patients were compared. Results A total of 157 patients had PPM 3 years after surgery. The incidence of PPM was 31.84%. Sixty-three patients in the PPM group received a 25-mm GK bileaflet valve (40.13%), 82 received a 27-mm valve (52.23%), and 12 (7.64%) received a 29-mm valve. There were significant differences in length of intensive care unit stay, duration of ventilator use, length of hospitalization, body surface area, EOAI, mean transmitral pressure gradient, and pulmonary artery pressure between the PPM and non-PPM group (P<0.05). There was a significant difference between preoperative and postoperative pulmonary artery pressures among non-PPM patients (P<0.05); however, there was no statistical difference in preoperative and postoperative pulmonary artery pressures among patients with PPM (P>0.05). Conclusions PPM after mitral valve replacement influences postoperative hemodynamics. Thus, larger-sized GK bileaflet mechanical valves are often used to reduce the risk of PPM. PMID:26313311

  11. Nuclear Technology. Course 30: Mechanical Inspection. Module 30-3, Valve Inspection.

    ERIC Educational Resources Information Center

    Wasil, Ed; Espy, John

    This third in a series of eight modules for a course titled Mechanical Inspection describes all the major types of valves utilized in a nuclear power plant and the purposes of the preinstallation and installation inspections; also describes the valve testing required for particular valves. The module follows a typical format that includes the…

  12. Nuclear Technology. Course 30: Mechanical Inspection. Module 30-3, Valve Inspection.

    ERIC Educational Resources Information Center

    Wasil, Ed; Espy, John

    This third in a series of eight modules for a course titled Mechanical Inspection describes all the major types of valves utilized in a nuclear power plant and the purposes of the preinstallation and installation inspections; also describes the valve testing required for particular valves. The module follows a typical format that includes the…

  13. Anticoagulant independent mechanical heart valves: viable now or still a distant holy grail

    PubMed Central

    Gray, Richard J.; Stupka, Jonathan C.; Emken, Michael R.; Scotten, Lawrence N.; Siegel, Rolland

    2016-01-01

    Valvular heart disease remains a large public health problem for all societies; it attracts the attention of public health organizations, researchers and governments. Valve substitution is an integral part of the treatment for this condition. At present, the choice of valve prosthesis is either tissue or mechanical. Tissue valves have become increasingly popular in spite of unresolved problems with durability, hemodynamics, cost and need for anticoagulation therapy. As a consequence, mechanical valve innovation has virtually ceased; the last successful mechanical design is 25 years old. We postulate that with improved technology, knowledge and experience gained over the last quarter century, the best possible solution to the problem of valve substitution can be achieved with a mechanical valve that is anticoagulant independent, durable, hemodynamically and cost efficient. At present, it is possible to design, test and produce a valve that can accomplish these goals. PMID:28149886

  14. Anticoagulant independent mechanical heart valves: viable now or still a distant holy grail.

    PubMed

    Chaux, Aurelio; Gray, Richard J; Stupka, Jonathan C; Emken, Michael R; Scotten, Lawrence N; Siegel, Rolland

    2016-12-01

    Valvular heart disease remains a large public health problem for all societies; it attracts the attention of public health organizations, researchers and governments. Valve substitution is an integral part of the treatment for this condition. At present, the choice of valve prosthesis is either tissue or mechanical. Tissue valves have become increasingly popular in spite of unresolved problems with durability, hemodynamics, cost and need for anticoagulation therapy. As a consequence, mechanical valve innovation has virtually ceased; the last successful mechanical design is 25 years old. We postulate that with improved technology, knowledge and experience gained over the last quarter century, the best possible solution to the problem of valve substitution can be achieved with a mechanical valve that is anticoagulant independent, durable, hemodynamically and cost efficient. At present, it is possible to design, test and produce a valve that can accomplish these goals.

  15. Quantification and comparison of the mechanical properties of four human cardiac valves.

    PubMed

    Pham, Thuy; Sulejmani, Fatiesa; Shin, Erica; Wang, Di; Sun, Wei

    2017-05-01

    Although having the same ability to permit unidirectional flow within the heart, the four main valves-the mitral valve (MV), aortic (AV), tricuspid (TV) and pulmonary (PV) valves-experience different loading conditions; thus, they exhibit different structural integrity from one another. Most research on heart valve mechanics have been conducted mainly on MV and AV or an individual valve, but none quantify and compare the mechanical and structural properties among the four valves from the same aged patient population whose death was unrelated to cardiovascular disease. A total of 114 valve leaflet samples were excised from 12 human cadavers whose death was unrelated to cardiovascular disease (70.1±3.7years old). Tissue mechanical and structural properties were characterized by planar biaxial mechanical testing and histological methods. The experimental data were then fitted with a Fung-type constitutive model. The four valves differed substantially in thickness, degree of anisotropy, and stiffness. The leaflets of the left heart (the AV leaflets and the anterior mitral leaflets, AML) were significantly stiffer and less compliant than their counterparts in the right heart. TV leaflets were the most extensible and isotropic, while AML and AV leaflets were the least extensible and the most anisotropic. Age plays a significant role in the reduction of leaflet stiffness and extensibility with nearly straightened collagen fibers observed in the leaflet samples from elderly groups (65years and older). Results from 114 human leaflet samples not only provided a baseline quantification of the mechanical properties of aged human cardiac valves, but also offered a better understanding of the age-dependent differences among the four valves. It is hoped that the experimental data collected and the associated constitutive models in this study can facilitate future studies of valve diseases, treatments and the development of interventional devices. Most research on heart valve

  16. Robotic hand with locking mechanism using TCP muscles for applications in prosthetic hand and humanoids

    NASA Astrophysics Data System (ADS)

    Saharan, Lokesh; Tadesse, Yonas

    2016-04-01

    This paper presents a biomimetic, lightweight, 3D printed and customizable robotic hand with locking mechanism consisting of Twisted and Coiled Polymer (TCP) muscles based on nylon precursor fibers as artificial muscles. Previously, we have presented a small-sized biomimetic hand using nylon based artificial muscles and fishing line muscles as actuators. The current study focuses on an adult-sized prosthetic hand with improved design and a position/force locking system. Energy efficiency is always a matter of concern to make compact, lightweight, durable and cost effective devices. In natural human hand, if we keep holding objects for long time, we get tired because of continuous use of energy for keeping the fingers in certain positions. Similarly, in prosthetic hands we also need to provide energy continuously to artificial muscles to hold the object for a certain period of time, which is certainly not energy efficient. In this work we, describe the design of the robotic hand and locking mechanism along with the experimental results on the performance of the locking mechanism.

  17. Integrating bio-prosthetic valves in the Fontan operation - Novel treatment to control retrograde flow in caval veins

    NASA Astrophysics Data System (ADS)

    Vukicevic, Marija; Conover, Timothy; Zhou, Jian; Hsia, Tain-Yen; Figliola, Richard

    2012-11-01

    For a child born with only one functional heart ventricle, the sequence of palliative surgeries typically culminates in the Fontan operation. This procedure is usually successful initially, but leads to later complications, for reasons not fully understood. Examples are respiratory-dependent retrograde flows in the caval and hepatic veins, and increased pulmonary vascular resistance (PVR), hypothesized to be responsible for elevated pressure in the liver and disease of the liver and intestines. Here we study the parameters responsible for retrograde flows in the inferior vena cava (IVC) and hepatic vein (HV), and investigate two novel interventions to control retrograde flow: implanting either a Medtronic Contegra valved conduit or an Edwards lifescience pericardial aortic valve in the IVC or HV. We performed the experiments in a multi-scale, patient specific mock circuit, with normal and elevated PVR, towards the optimization of the Fontan circulation. The results show that both valves can significantly reduce retrograde flows in the veins, suggesting potential advantages in the treatment of the patients with congenital heart diseases. Fondation Leducq

  18. Transcatheter valve-in-valve implantation for failed mitral prosthesis: the first experience in Japan.

    PubMed

    Tada, Norio; Enta, Yusuke; Sakurai, Mie; Ootomo, Tatsushi; Hata, Masaki

    2017-01-01

    An 82-year-old woman had a history of mitral valve replacement with a 25-mm MOSAIC (Medtronic, USA) for severe mitral regurgitation (MR) 8 years previously. Recently, she developed heart failure due to MR secondary to prosthetic valve failure. She underwent transcatheter valve-in-valve implantation with a 23-mm SAPIEN XT (Edwards Lifesciences, USA) to the prosthetic mitral valve by transapical approach. To our knowledge, this is the first reported case of transcatheter valve implantation for failed mitral prosthetic valve using valve-in-valve technique in Japan.

  19. Comparison of in vitro flows past a mechanical heart valve in anatomical and axisymmetric aorta models

    NASA Astrophysics Data System (ADS)

    Haya, Laura; Tavoularis, Stavros

    2017-06-01

    Flow characteristics past a bileaflet mechanical heart valve were measured under physiological flow conditions in a straight tube with an axisymmetric expansion, similar to vessels used in previous studies, and in an anatomical model of the aorta. We found that anatomical features, including the three-lobed sinus and the aorta's curvature affected significantly the flow characteristics. The turbulent and viscous stresses were presented and discussed as indicators for potential blood damage and thrombosis. Both types of stresses, averaged over the two axial measurement planes, were significantly lower in the anatomical model than in the axisymmetric one. This difference was attributed to the lower height-to-width ratio and more gradual contraction of the anatomical aortic sinus. The curvature of the aorta caused asymmetries in the velocity and stress distributions during forward flow. Secondary flows resulting from the aorta's curvature are thought to have redistributed the fluid stresses transversely, resulting in a more homogeneous stress distribution in the anatomical aortic root than in the axisymmetric root. The results of this study demonstrate the importance of modelling accurately the aortic geometry in experimental and computational studies of prosthetic devices. Moreover, our findings suggest that grafts used for aortic root replacement should approximate as closely as possible the shape of the natural sinuses.

  20. Mechanical properties of elastomers for artificial leaflet heart valves

    NASA Astrophysics Data System (ADS)

    Parfeev, V. M.; Grushetskii, I. V.; Smurova, E. V.

    1983-01-01

    Biaxial tension is the usual type of stress on prosthesis parts made from polymer sheets. The chemical characteristics of medical elastomers in static and cyclic biaxial tension are poorer than in monaxial tension. These indices may be used for a realistic evaluation of the feasibility of using a given material for prostheses. Biaxial tension produced by a punch in conjunction with light transmission measurements may yield information on the production process and the condition of the material. Static and cyclic liquid pressure measurements are irreplaceable for medical elastomers and products, since they reveal the specific mechanisms for rupture, which may not be noted using other types of stressing. This study revealed the danger zones for leaflet AHV and provides sufficient methods for mechanical testing. In the future, the design of prostheses should be improved by placing major attention on the zones of cusp attachment. The mechanical testing results indicated that isotropic silicone and fluorosilicone rubbers may be used in valve prostheses for the pulmonary artery. Aortic valve prostheses should be made with reinforced rubber and polyurethane.

  1. Cavitation damage of pyrolytic carbon in mechanical heart valves.

    PubMed

    Kafesjian, R; Howanec, M; Ward, G D; Diep, L; Wagstaff, L S; Rhee, R

    1994-04-01

    A summary of the observations of cavitation-related damage is presented for over a hundred mechanical heart valves (MHV) containing pyrolytic carbon components. Valves were obtained from several types of simulators, animal studies and clinical explantations, and were primarily of the bileaflet type. Damage on these valves was documented as to location, type, and severity. This report focuses on the damage location where cavitation bubbles have been observed in vitro. Pitting and microcracking are the forms of damage observed that can be associated with cavitation. The pitting is primarily of a focal nature and is thought to be due to cavitation bubble collapse or, possibly, initiation. Certain features of the deposited material appear to be important relative to cavitation damage resistance and the so-called cavitation threshold of a MHV. A highly polished surface with few micropores provides few nucleation sites for cavitation bubbles and will better withstand cavitation forces. Attributing certain observations of in vivo damage to cavitation is done by inference from; 1. the similarity of the damage features observed on explants to those produced by cavitation in vitro, and 2. the identity of the location of this damage with the location of cavitation as observed by high speed video (HSV). In addition, confirmation was obtained in a number of instances by in vitro observation of cavitation coinciding with a specific damage location on the same explanted MHV. In most of the fractures, a focal pit was usually present on the fracture line at or near the fracture origin, indicating pitting as a primary damage mechanism.(ABSTRACT TRUNCATED AT 250 WORDS)

  2. Quality of life after aortic valve repair is similar to Ross patients and superior to mechanical valve replacement: a cross-sectional study.

    PubMed

    Zacek, Pavel; Holubec, T; Vobornik, M; Dominik, J; Takkenberg, J; Harrer, J; Vojacek, J

    2016-04-02

    In patients after aortic valve surgery, the quality of life is hypothesized to be influenced by the type of the valve procedure. A cross-sectional study on the postoperative quality of life was carried out in patients after aortic valve-sparing surgery (with regards to the age of the patient), Ross procedure and mechanical aortic valve replacement. Quality of life was studied in 139 patients after aortic valve surgery divided into four study groups (Y - aortic valve-sparing procedure at the age below 50 years, mean age 36.2 years; O - aortic valve-sparing procedure at the age 50 years and over, mean age 59.2 years; R - Ross procedure, mean age 37.8 years and M - mechanical aortic valve replacement at the age below 50 years, mean age 39.2 years). SF-36 Short Form and valve-specific questionnaires were mailed to the patients after 6 months or later following surgery (median 26.9 months). In SF-36, the younger aortic valve repair patients and the Ross patients scored significantly better in 4 of 4 physical subscales and in 2 of 4 mental subscales than the older aortic valve repair and mechanical valve replacement patients. In the valve-specific questionnaire; however, all 3 groups free of anticoagulation (Y, O, and R) displayed greater freedom from negative valve-related concerns. Postoperative quality of life is influenced by the type of aortic valve procedure and is negatively linked with mechanical prosthesis implantation and long-term anticoagulation. Aortic valve-sparing strategy should be considered in cases with suitable valve morphology due to favorable clinical results and beneficial impact on the long-term quality of life.

  3. Mechanisms of Spin-Dependent Heat Generation in Spin Valves

    NASA Astrophysics Data System (ADS)

    Zhang, Xiao-Xue; Zhu, Yao-Hui; He, Pei-Song; Li, Bao-He

    2017-06-01

    The extra heat generation in spin transport is usually interpreted in terms of the spin relaxation. By reformulating the heat generation rate, we found alternative current-force pairs without cross effects, which enable us to interpret the product of each pair as a distinct mechanism of heat generation. The results show that the spin-dependent part of the heat generation includes two terms. One of them is proportional to the square of the spin accumulation and arises from the spin relaxation. However, the other is proportional to the square of the spin-accumulation gradient and should be attributed to another mechanism, the spin diffusion. We illustrated the characteristics of the two mechanisms in a typical spin valve with a finite nonmagnetic spacer layer.

  4. The comparative influence of prophylactic antibiotics on the prothrombin response to warfarin in the postoperative prosthetic cardiac valve patient. Cefamandole, cefazolin, vancomycin.

    PubMed Central

    Angaran, D M; Dias, V C; Arom, K V; Northrup, W F; Kersten, T G; Lindsay, W G; Nicoloff, D M

    1987-01-01

    A prospective randomized trial was conducted comparing the effect of three antibiotics: cefamandole (CM), cefazolin (CZ), and vancomycin (V), used as prophylaxis for prosthetic valve surgery, on the prothrombin (PT) response to warfarin (W) on the third day of anticoagulant therapy. Twenty patients, with normal preoperative PTs, were randomized to each antibiotic. Their PTs were not significantly different at 2 hours after operation and the morning before W was begun. The three groups received similar W doses for 2 days, and the PT, as percentage of activity, on the morning of the third day demonstrated that V (51 +/- 18%) was significantly greater (p less than 0.005) than CM (29 +/- 14%) or CZ (38 +/- 18%). CM had a significantly greater percentage of change in PT (64 +/- 14%, p less than 0.0001) from the first to third day than either CZ (51.1 +/- 18%) or V (44.6 +/- 19%). CM also had a greater number of patients (6) with PTs greater than or equal to 30 seconds on day 3 than either CZ (1) or V (1). The antibiotic influence on the PT response to W in this study is ranked as CM greater than CZ greater than V. PMID:3300580

  5. The comparative influence of prophylactic antibiotics on the prothrombin response to warfarin in the postoperative prosthetic cardiac valve patient. Cefamandole, cefazolin, vancomycin.

    PubMed

    Angaran, D M; Dias, V C; Arom, K V; Northrup, W F; Kersten, T G; Lindsay, W G; Nicoloff, D M

    1987-08-01

    A prospective randomized trial was conducted comparing the effect of three antibiotics: cefamandole (CM), cefazolin (CZ), and vancomycin (V), used as prophylaxis for prosthetic valve surgery, on the prothrombin (PT) response to warfarin (W) on the third day of anticoagulant therapy. Twenty patients, with normal preoperative PTs, were randomized to each antibiotic. Their PTs were not significantly different at 2 hours after operation and the morning before W was begun. The three groups received similar W doses for 2 days, and the PT, as percentage of activity, on the morning of the third day demonstrated that V (51 +/- 18%) was significantly greater (p less than 0.005) than CM (29 +/- 14%) or CZ (38 +/- 18%). CM had a significantly greater percentage of change in PT (64 +/- 14%, p less than 0.0001) from the first to third day than either CZ (51.1 +/- 18%) or V (44.6 +/- 19%). CM also had a greater number of patients (6) with PTs greater than or equal to 30 seconds on day 3 than either CZ (1) or V (1). The antibiotic influence on the PT response to W in this study is ranked as CM greater than CZ greater than V.

  6. Systematic variation of prosthetic foot spring affects center-of-mass mechanics and metabolic cost during walking.

    PubMed

    Zelik, Karl E; Collins, Steven H; Adamczyk, Peter G; Segal, Ava D; Klute, Glenn K; Morgenroth, David C; Hahn, Michael E; Orendurff, Michael S; Czerniecki, Joseph M; Kuo, Arthur D

    2011-08-01

    Lower-limb amputees expend more energy to walk than non-amputees and have an elevated risk of secondary disabilities. Insufficient push-off by the prosthetic foot may be a contributing factor. We aimed to systematically study the effect of prosthetic foot mechanics on gait, to gain insight into fundamental prosthetic design principles. We varied a single parameter in isolation, the energy-storing spring in a prototype prosthetic foot, the controlled energy storage and return (CESR) foot, and observed the effect on gait. Subjects walked on the CESR foot with three different springs. We performed parallel studies on amputees and on non-amputees wearing prosthetic simulators. In both groups, spring characteristics similarly affected ankle and body center-of-mass (COM) mechanics and metabolic cost. Softer springs led to greater energy storage, energy return, and prosthetic limb COM push-off work. But metabolic energy expenditure was lowest with a spring of intermediate stiffness, suggesting biomechanical disadvantages to the softest spring despite its greater push-off. Disadvantages of the softest spring may include excessive heel displacements and COM collision losses. We also observed some differences in joint kinetics between amputees and non-amputees walking on the prototype foot. During prosthetic push-off, amputees exhibited reduced energy transfer from the prosthesis to the COM along with increased hip work, perhaps due to greater energy dissipation at the knee. Nevertheless, the results indicate that spring compliance can contribute to push-off, but with biomechanical trade-offs that limit the degree to which greater push-off might improve walking economy. © 2011 IEEE

  7. Systematic variation of prosthetic foot spring affects center-of-mass mechanics and metabolic cost during walking

    PubMed Central

    Zelik, Karl E.; Collins, Steven H.; Adamczyk, Peter G.; Segal, Ava D.; Klute, Glenn K.; Morgenroth, David C.; Hahn, Michael E.; Orendurff, Michael S.; Czerniecki, Joseph M.; Kuo, Arthur D.

    2014-01-01

    Lower-limb amputees expend more energy to walk than non-amputees and have an elevated risk of secondary disabilities. Insufficient push-off by the prosthetic foot may be a contributing factor. We aimed to systematically study the effect of prosthetic foot mechanics on gait, to gain insight into fundamental prosthetic design principles. We varied a single parameter in isolation, the energy-storing spring in a prototype prosthetic foot, the Controlled Energy Storage and Return (CESR) foot, and observed the effect on gait. Subjects walked on the CESR foot with three different springs. We performed parallel studies on amputees and on non-amputees wearing prosthetic simulators. In both groups, spring characteristics similarly affected ankle and body center-of-mass (COM) mechanics and metabolic cost. Softer springs led to greater energy storage, energy return and prosthetic limb COM push-off work. But metabolic energy expenditure was lowest with a spring of intermediate stiffness, suggesting biomechanical disadvantages to the softest spring despite its greater push-off. Disadvantages of the softest spring may include excessive heel displacements and COM collision losses. We also observed some differences in joint kinetics between amputees and non-amputees walking on the prototype foot. During prosthetic push-off, amputees exhibited reduced energy transfer from the prosthesis to the COM along with increased hip work, perhaps due to greater energy dissipation at the knee. Nevertheless, the results indicate that spring compliance can contribute to push-off, but with biomechanical trade-offs that limit the degree to which greater push-off might improve walking economy. PMID:21708509

  8. Biological versus prosthetic ring in mitral-valve repair: enhancement of mitral annulus dynamics and left-ventricular function with pericardial annuloplasty at long term.

    PubMed

    Borghetti, V; Campana, M; Scotti, C; Domenighini, D; Totaro, P; Coletti, G; Pagani, M; Lorusso, R

    2000-04-01

    The effects of different annuloplasty rings on mitral annulus dynamics and left-ventricular (LV) function after mitral-valve repair (MVR) are still controversial. This study sought to compare biological versus prosthetic rigid rings for annular remodelling in MVR at long term. Forty-four consecutive patients were retrospectively enrolled. All patients had isolated posterior-leaflet prolapse and underwent identical surgical mitral-valve reconstruction (quadrangular resection of the posterior leaflet associated with annuloplasty). Twenty-three patients underwent mitral annuloplasty with an autologous pericardial ring (group I), whereas 21 patients had MVR with a Carpentier-Edwards rigid ring (group II). No differences existed between the groups in terms of pre-operative patient profile. Post-operative LV systolic indices have been assessed by two-dimensional echocardiography at rest and during supine bicycle exercise. Mitral annular motion has been examined by means of the extent of mitral annulus systolic excursion (MASE), as measured in four longitudinal LV segments (anterior, inferior, septal and lateral). Mean and peak trans-mitral flow velocities (TMFV) have been also evaluated by continuous-wave Doppler. The mean follow-up did not differ between the groups, those being 41+/-12 months in group I (range17-65 months) and 46+/-15 months in group II (range 23-83 months), respectively. Post-operative echocardiographic study did not show significant mitral regurgitation at rest or at peak exercise in any patient. ANOVA analysis for repeated measures showed a significant interaction in peak TMFV (F((1,42))=5.23; P=0.03), and in left-ventricular ejection fraction (LVEF; F((1,42))=7.61, P=0.01). The analysis of contrasts showed a significant increase in TMFV in both groups (group I from 1.22+/-0.22 to 1.79+/-0.32 m/s, t=-8.8, P<0.0001; and group II from 1.19+/-0.17 to 1.96+/-0.33 m/s, t=-12.8, P<0.0001). Recruitment of LVEF reserve during exercise was observed only in

  9. Wear and wear mechanism simulation of heavy-duty engine intake valve and seat inserts

    NASA Astrophysics Data System (ADS)

    Wang, Y. S.; Narasimhan, S.; Larson, J. M.; Schaefer, S. K.

    1998-02-01

    A silicon-chromium alloy frequently used for heavy-duty diesel engine intake valves was tested against eight different insert materials with a valve seat wear simulator. Wear resistance of these combinations was ranked. For each test, the valve seat temperature was controlled at approximately 510 °C, the number of cycles was 864,000 (or 24 h), and the test load was 17,640 N. The combination of the silicon-chromium valve against a cast iron insert produced the least valve seat wear, whereas a cobalt-base alloy insert produced the highest valve seat wear. In the overall valve seat recession ranking, however, the combination of the silicon-chromium valve and an iron-base chromium-nickel alloy insert had the least total seat recession, whereas the silicon-chromium valve against cobalt-base alloy, cast iron, and nickel-base alloy inserts had significant seat recession. Hardness and microstructure compatibility of valve and insert materials are believed to be significant factors in reducing valve and insert wear. The test results indicate that the mechanisms of valve seat and insert wear are a complex combination of adhesion and plastic deformation. Adhesion was confirmed by material transfer, while plastic deformation was verified by shear strain (or radial flow) and abrasion. The oxide films formed during testing also played a significant role. They prevented direct metal-to-metal contact and reduced the coefficient of friction on seat surfaces, thereby reducing adhesive and deformation-controlled wear.

  10. Fluid dynamic characterization of a polymeric heart valve prototype (Poli-Valve) tested under continuous and pulsatile flow conditions.

    PubMed

    De Gaetano, Francesco; Serrani, Marta; Bagnoli, Paola; Brubert, Jacob; Stasiak, Joanna; Moggridge, Geoff D; Costantino, Maria Laura

    2015-11-01

    Only mechanical and biological heart valve prostheses are currently commercially available. The former show longer durability but require anticoagulant therapy; the latter display better fluid dynamic behavior but do not have adequate durability. New Polymeric Heart Valves (PHVs) could potentially combine the hemodynamic properties of biological valves with the durability of mechanical valves. This work presents a hydrodynamic evaluation of 2 groups of newly developed supra-annular, trileaflet prosthetic heart valves made from styrenic block copolymers (SBC): Poli-Valves. 2 types of Poli-Valves made of SBC and differing in polystyrene fraction content were tested under continuous and pulsatile flow conditions as prescribed by ISO 5840 Standard. A pulse duplicator designed ad hoc allowed the valve prototypes to be tested at different flow rates and frequencies. Pressure and flow were recorded; pressure drops, effective orifice area (EOA), and regurgitant volume were computed to assess the behavior of the valve. Both types of Poli-Valves met the minimum requirements in terms of regurgitation and EOA as specified by the ISO 5840 Standard. Results were compared with 5 mechanical heart valves (MHVs) and 5 tissue heart valves (THVs), currently available on the market. Based on these results, PHVs based on styrenic block copolymers, as are Poli-Valves, can be considered a promising alternative for heart valve replacement in the near future.

  11. Fluid Dynamic Characterization of a Polymeric Heart Valve Prototype (Poli-Valve) tested under Continuous and Pulsatile Flow Conditions

    PubMed Central

    De Gaetano, Francesco; Serrani, Marta; Bagnoli, Paola; Brubert, Jacob; Stasiak, Joanna; Moggridge, Geoff D.; Costantino, Maria Laura

    2016-01-01

    Introduction Only mechanical and biological heart valve prostheses are currently commercially available. The former show longer durability but require anticoagulant therapy, the latter display better fluid dynamic behaviour but do not have adequate durability. New Polymeric Heart Valves (PHVs) could potentially combine the haemodynamic properties of biological valves with the durability of mechanical valves. This work presents a hydrodynamic evaluation of two groups of newly developed supra-annular tri-leaflet prosthetic heart valves made from styrenic block copolymers (SBC): Poli-Valves. Methods Two types of Poli-Valves made of SBC differing in polystyrene fraction content were tested under continuous and pulsatile flow conditions as prescribed by ISO 5840 Standard. An ad - hoc designed pulse duplicator allowed the valve prototypes to be tested at different flow rates and frequencies. Pressure and flow were recorded; pressure drops, effective orifice area (EOA), and regurgitant volume were computed to assess the valve’s behaviour. Results Both types Poli-Valves met the minimum requirements in terms of regurgitation and EOA as specified by ISO 5840 Standard. Results were compared with five mechanical heart valves (MHVs) and five tissue heart valves (THVs), currently available on the market. Conclusion Based on these results, polymeric heart valves based on styrenic block copolymers, as Poli-Valves are, can be considered as promising alternative for heart valve replacement in near future. PMID:26689146

  12. Statistical characteristics of mechanical heart valve cavitation in accelerated testing.

    PubMed

    Wu, Changfu; Hwang, Ned H C; Lin, Yu-Kweng M

    2004-07-01

    Cavitation damage has been observed on mechanical heart valves (MHVs) undergoing accelerated testing. Cavitation itself can be modeled as a stochastic process, as it varies from beat to beat of the testing machine. This in-vitro study was undertaken to investigate the statistical characteristics of MHV cavitation. A 25-mm St. Jude Medical bileaflet MHV (SJM 25) was tested in an accelerated tester at various pulse rates, ranging from 300 to 1,000 bpm, with stepwise increments of 100 bpm. A miniature pressure transducer was placed near a leaflet tip on the inflow side of the valve, to monitor regional transient pressure fluctuations at instants of valve closure. The pressure trace associated with each beat was passed through a 70 kHz high-pass digital filter to extract the high-frequency oscillation (HFO) components resulting from the collapse of cavitation bubbles. Three intensity-related measures were calculated for each HFO burst: its time span; its local root-mean-square (LRMS) value; and the area enveloped by the absolute value of the HFO pressure trace and the time axis, referred to as cavitation impulse. These were treated as stochastic processes, of which the first-order probability density functions (PDFs) were estimated for each test rate. Both the LRMS value and cavitation impulse were log-normal distributed, and the time span was normal distributed. These distribution laws were consistent at different test rates. The present investigation was directed at understanding MHV cavitation as a stochastic process. The results provide a basis for establishing further the statistical relationship between cavitation intensity and time-evolving cavitation damage on MHV surfaces. These data are required to assess and compare the performance of MHVs of different designs.

  13. Transient pressure signals in mechanical heart valve cavitation.

    PubMed

    Wu, Z J; Slonin, J H; Hwang, N H

    1996-01-01

    The purpose of this investigation was to establish a correlation between mechanical heart valve (MHV) cavitation and transient pressure (TP) signals at MHV closure. This correlation may suggest a possible method to detect in vivo MHV cavitation. In a pulsatile mock flow loop, a study was performed to measure TP and observe cavitation bubble inception at MHV closure under simulated physiologic ventricular and aortic pressures at heart rates of 70, 90, 120, and 140 beats/min with corresponding cardiac outputs of 5.0, 6.0, 7.5, and 8.5 L/min, respectively. The experimental study included two bileaflet MHV prostheses: 1) St. Jude Medical 31 mm and 2) Carbomedics 31 mm. High fidelity piezo-electric pressure transducers were used to measure TP immediately before and after the valve leaflet/housing impact. A stroboscopic lighting imaging technique was developed to capture cavitation bubbles on the MHV inflow surfaces at selected time delays ranging from 25 microseconds to 1 ms after the leaflet/housing impact. The TP traces measured 10 mm away from the valve leaflet tip showed a large pressure reduction peak at the leaflet/housing impact, and subsequent high frequency pressure oscillations (HPOs) while the cavitation bubbles were observed. The occurrence of cavitation bubbles and HPO bursts were found to be random on a beat by beat basis. However, the amplitude of the TP reduction, the intensity of the cavitation bubble (size and number), and the intensity of HPO were found to increase with the test heart rate. A correlation between the MHV cavitation bubbles and the HPO burst was positively established. Power spectrum analysis of the TP signals further showed that the frequency of the HPO (cavitation bubble collapse pressures) ranged from 100 to 450 kHz.

  14. The effects of common footwear on stance-phase mechanical properties of the prosthetic foot-shoe system.

    PubMed

    Major, Matthew J; Scham, Joel; Orendurff, Michael

    2017-05-01

    Prosthetic feet are prescribed based on their mechanical function and user functional level. Subtle changes to the stiffness and hysteresis of heel, midfoot, and forefoot regions can influence the dynamics and economy of gait in prosthesis users. However, the user's choice of shoes may alter the prosthetic foot-shoe system mechanical characteristics, compromising carefully prescribed and rigorously engineered performance of feet. Observe the effects of footwear on the mechanical properties of the prosthetic foot-shoe system including commonly prescribed prosthetic feet. Repeated-measures, Mechanical characterization. The stiffness and energy return was measured using a hydraulic-driven materials test machine across combinations of five prosthetic feet and four common shoes as well as a barefoot condition. Heel energy return decreased by an average 4%-9% across feet in all shoes compared to barefoot, with a cushioned trainer displaying the greatest effect. Foot designs that may improve perceived stability by providing low heel stiffness and rapid foot-flat were compromised by the addition of shoes. Shoes altered prosthesis mechanical characteristics in the sagittal and frontal planes, suggesting that shoe type should be controlled or reported in research comparing prostheses. Understanding of how different shoes could alter certain gait-related characteristics of prostheses may aid decisions on footwear made by clinicians and prosthesis users. Clinical relevance Shoes can alter function of the prosthetic foot-shoe system in unexpected and sometimes undesirable ways, often causing similar behavior across setups despite differences in foot design, and prescribing clinicians should carefully consider these effects on prosthesis performance.

  15. Testing of elastomeric liners used in limb prosthetics: classification of 15 products by mechanical performance.

    PubMed

    Sanders, Joan E; Nicholson, Brian S; Zachariah, Santosh G; Cassisi, Damon V; Karchin, Ari; Fergason, John R

    2004-03-01

    The mechanical properties of 15 elastomeric liner products used in limb prosthetics were evaluated under compressive, frictional, shear, and tensile loading conditions. All testing was conducted at load levels comparable to interface stress measurements reported on transtibial amputee subjects. For each test configuration, materials were classified into four groups based on the shapes of their response curves. For the 15 liners tested, there were 10 unique classification sets, indicating a wide range of unique materials. In general, silicone gel liners classified within the same groups thus were quite similar to each other. They were of lower compressive, shear, and tensile stiffness than the silicone elastomer products, consistent with their lightly cross-linked, high-fluid content structures. Silicone elastomer products better spanned the response groups than the gel liners, demonstrating a wide range of compressive, shear, and tensile stiffness values. Against a skin-like material, a urethane liner had the highest coefficient of friction of any liner tested, although coefficients of friction values for most of the materials were higher than interface shear:pressure ratios measured on amputee subjects using Pelite liners. The elastomeric liner material property data and response groupings provided here can potentially be useful to prosthetic fitting by providing quantitative information on similarities and differences among products.

  16. Combined biaxial and uniaxial mechanical characterization of prosthetic meshes in a rabbit model.

    PubMed

    Röhrnbauer, B; Ozog, Y; Egger, J; Werbrouck, E; Deprest, J; Mazza, E

    2013-06-21

    The present experimental study is aimed at a combined uniaxial and biaxial mechanical characterization of the deformation behavior of two types of prosthetic meshes, SPMM (heavy-weight) and Gynemesh M (light-weight, partly absorbable), after integration in the host tissue. Explants from a full-thickness-abdominal-wall-defect-rabbit-model were tested in the two loading conditions. Corresponding protocols and data analysis procedures for biaxial inflation tests and uniaxial tensile tests were developed. Biaxial responses were observed to be by factor 2-4 stiffer compared to corresponding uniaxial experiments, depending on the material tested. In biaxial loading conditions, SPMM explants were stiffest. Gynemesh M explants and native tissue were similarly compliant at low membrane tensions (<5N/cm) (abdominal wall: 40±23N/cm, Gynemesh M: 59±44N/cm, SPMM: 145±36N/cm). At high membrane tensions (>5N/cm), there were distinct differences in the stiffness of the three groups, SPMM explants being the stiffest, followed by Gynemesh M explants and native tissue being the most compliant. In uniaxial loading conditions, the two explants were similarly stiff and distinctly stiffer than native tissue at low membrane tensions (<5N/cm) (abdominal wall: 9±1N/cm, Gynemesh M: 21±5N/cm, and SPMM: 24±5N/cm). At high membrane tension (>5N/cm), differences between all groups vanished. Biaxial and uniaxial tests yield different results with respect to the mechanical behavior of mesh explants. These findings demonstrate that an evaluation of the mechanical biocompatibility of prosthetic meshes should be based on an experimental configuration (uniaxial or biaxial tension) which reproduces the expected in vivo conditions of mechanical loading and deformation. Copyright © 2013 Elsevier Ltd. All rights reserved.

  17. Platelet activation of mechanical versus bioprosthetic heart valves during systole.

    PubMed

    Hedayat, Mohammadali; Asgharzadeh, Hafez; Borazjani, Iman

    2017-03-11

    Thrombus formation is a major concern for recipients of mechanical heart valves (MHVs), which requires them to take anticoagulant drugs for the rest of their lives. Bioprosthetic heart valves (BHVs) do not require life-long anticoagulant therapy but deteriorate after 10-15years. The thrombus formation is initiated by the platelet activation which is thought to be mainly generated in MHVs by the flow through the hinge and the leakage flow during the diastole. However, our results show that the activation in the bulk flow during the systole phase might play an essential role as well. This is based on our results obtained by comparing the thrombogenic performance of a MHV and a BHV (as control) in terms of shear induced platelet activation under exactly the same conditions. Three different mathematical activation models including linear level of activation, damage accumulation, and Soares model are tested to quantify the platelet activation during systole using the previous simulations of the flow through MHV and BHV in a straight aorta under the same physiologic flow conditions. Results indicate that the platelet activation in the MHV at the beginning of the systole phase is slightly less than the BHV. However, at the end of the systole phase the platelet activation by the bulk flow for the MHV is several folds (1.41, 5.12, and 2.81 for linear level of activation, damage accumulation, and Soares model, respectively) higher than the BHV for all tested platelet activation models.

  18. Fluid-Structure Interaction Simulation of Prosthetic Aortic Valves: Comparison between Immersed Boundary and Arbitrary Lagrangian-Eulerian Techniques for the Mesh Representation.

    PubMed

    Bavo, Alessandra M; Rocatello, Giorgia; Iannaccone, Francesco; Degroote, Joris; Vierendeels, Jan; Segers, Patrick

    2016-01-01

    In recent years the role of FSI (fluid-structure interaction) simulations in the analysis of the fluid-mechanics of heart valves is becoming more and more important, being able to capture the interaction between the blood and both the surrounding biological tissues and the valve itself. When setting up an FSI simulation, several choices have to be made to select the most suitable approach for the case of interest: in particular, to simulate flexible leaflet cardiac valves, the type of discretization of the fluid domain is crucial, which can be described with an ALE (Arbitrary Lagrangian-Eulerian) or an Eulerian formulation. The majority of the reported 3D heart valve FSI simulations are performed with the Eulerian formulation, allowing for large deformations of the domains without compromising the quality of the fluid grid. Nevertheless, it is known that the ALE-FSI approach guarantees more accurate results at the interface between the solid and the fluid. The goal of this paper is to describe the same aortic valve model in the two cases, comparing the performances of an ALE-based FSI solution and an Eulerian-based FSI approach. After a first simplified 2D case, the aortic geometry was considered in a full 3D set-up. The model was kept as similar as possible in the two settings, to better compare the simulations' outcomes. Although for the 2D case the differences were unsubstantial, in our experience the performance of a full 3D ALE-FSI simulation was significantly limited by the technical problems and requirements inherent to the ALE formulation, mainly related to the mesh motion and deformation of the fluid domain. As a secondary outcome of this work, it is important to point out that the choice of the solver also influenced the reliability of the final results.

  19. Fluid-Structure Interaction Simulation of Prosthetic Aortic Valves: Comparison between Immersed Boundary and Arbitrary Lagrangian-Eulerian Techniques for the Mesh Representation

    PubMed Central

    Iannaccone, Francesco; Degroote, Joris; Vierendeels, Jan; Segers, Patrick

    2016-01-01

    In recent years the role of FSI (fluid-structure interaction) simulations in the analysis of the fluid-mechanics of heart valves is becoming more and more important, being able to capture the interaction between the blood and both the surrounding biological tissues and the valve itself. When setting up an FSI simulation, several choices have to be made to select the most suitable approach for the case of interest: in particular, to simulate flexible leaflet cardiac valves, the type of discretization of the fluid domain is crucial, which can be described with an ALE (Arbitrary Lagrangian-Eulerian) or an Eulerian formulation. The majority of the reported 3D heart valve FSI simulations are performed with the Eulerian formulation, allowing for large deformations of the domains without compromising the quality of the fluid grid. Nevertheless, it is known that the ALE-FSI approach guarantees more accurate results at the interface between the solid and the fluid. The goal of this paper is to describe the same aortic valve model in the two cases, comparing the performances of an ALE-based FSI solution and an Eulerian-based FSI approach. After a first simplified 2D case, the aortic geometry was considered in a full 3D set-up. The model was kept as similar as possible in the two settings, to better compare the simulations’ outcomes. Although for the 2D case the differences were unsubstantial, in our experience the performance of a full 3D ALE-FSI simulation was significantly limited by the technical problems and requirements inherent to the ALE formulation, mainly related to the mesh motion and deformation of the fluid domain. As a secondary outcome of this work, it is important to point out that the choice of the solver also influenced the reliability of the final results. PMID:27128798

  20. Check valve with poppet dashpot/frictional damping mechanism

    NASA Astrophysics Data System (ADS)

    Morris, Brian G.

    1993-08-01

    An inline check valve for a flow line where the valve element is guided for inline travel forward and rearward of a valve sealing member and is spring biased to a closed sealing condition is presented. One of the guides for the valve element includes a dashpot housing with a bore and plunger member to control the rate of travel of the valve element in either direction, providing a guiding function. The plunger member is arranged with a dashpot ring to frictionally contact the dashpot bore and has an interior tortuous flow path from one side to the other side of the dashpot ring. The dashpot housing is not anchored to the valve body so that the valve can be functional even if the dashpot ring becomes jammed in the dashpot housing.

  1. Check valve with poppet dashpot/frictional damping mechanism

    NASA Technical Reports Server (NTRS)

    Morris, Brian G. (Inventor)

    1993-01-01

    An inline check valve for a flow line where the valve element is guided for inline travel forward and rearward of a valve sealing member and is spring biased to a closed sealing condition is presented. One of the guides for the valve element includes a dashpot housing with a bore and plunger member to control the rate of travel of the valve element in either direction, providing a guiding function. The plunger member is arranged with a dashpot ring to frictionally contact the dashpot bore and has an interior tortuous flow path from one side to the other side of the dashpot ring. The dashpot housing is not anchored to the valve body so that the valve can be functional even if the dashpot ring becomes jammed in the dashpot housing.

  2. Check valve with poppet dashpot/frictional damping mechanism

    NASA Astrophysics Data System (ADS)

    Morris, Brian G.

    1992-06-01

    An inline check valve for a flow line where the valve element is guided for inline travel forward and rearward of a valve sealing member and is spring biased to a closed sealing condition is presented. One of the guides for the valve element includes a dashpot housing with a bore and plunger member to control the rate of travel of the valve element in either direction, providing a guiding function. The plunger member is arranged with a dashpot ring to frictionally contact the dashpot bore and has an interior tortuous flow path from one side to the other side of the dashpot ring. The dashpot housing is not anchored to the valve body so that the valve can be functional even if the dashpot ring becomes jammed in the dashpot housing.

  3. Surgery for rheumatic mitral valve disease in sub-saharan African countries: why valve repair is still the best surgical option.

    PubMed

    Mvondo, Charles Mve; Pugliese, Marta; Giamberti, Alessandro; Chelo, David; Kuate, Liliane Mfeukeu; Boombhi, Jerome; Dailor, Ellen Marie

    2016-01-01

    Rheumatic valve disease, a consequence of acute rheumatic fever, remains endemic in developing countries in the sub-Saharan region where it is the leading cause of heart failure and cardiovascular death, involving predominantly a young population. The involvement of the mitral valve is pathognomonic and mitral surgery has become the lone therapeutic option for the majority of these patients. However, controversies exist on the choice between valve repair or prosthetic valve replacement. Although the advantages of mitral valve repair over prosthetic valve replacement in degenerative mitral disease are well established, this has not been the case for rheumatic lesions, where the use of prosthetic valves, specifically mechanical devices, even in poorly compliant populations remains very common. These patients deserve more accurate evaluation in the choice of the surgical strategy which strongly impacts the post-operative outcomes. This report discusses the factors supporting mitral repair surgery in rheumatic disease, according to the patients' characteristics and the effectiveness of the current repair techniques compared to prosthetic valve replacement in developing countries.

  4. Analysis of velocity fluctuations downstream of a bileaflet mechanical heart valve

    NASA Astrophysics Data System (ADS)

    Forleo, Marcio; Dasi, Lakshmi

    2010-11-01

    Bileaflet mechanical heart valves are widely used to replace diseased aortic heart valves. The stresses induced by the rich and unsteady non-physiological flow structures have been the focus to evaluate red blood cells damage and platelet activation, develop flow control strategies, or improve valve designs. In this study, we analyzed the flow fields obtained downstream of a bileaflet mechanical heart valve using time-resolved particle image velocimetry under pulsatile and steady flow conditions. Our study demonstrates the rich dynamics downstream of the valve and weighs the relevance of unsteady effects vs inertia effects on the different flow structures. Power spectrum analyses of the turbulent fluctuations highlight the highly anisotropic influence and the limited applicability of classical self-similar turbulence theory in describing the small-scale structures in the immediate vicinity of the valve.

  5. Evaluation of function, performance, and preference as transfemoral amputees transition from mechanical to microprocessor control of the prosthetic knee.

    PubMed

    Hafner, Brian J; Willingham, Laura L; Buell, Noelle C; Allyn, Katheryn J; Smith, Douglas G

    2007-02-01

    To evaluate differences in function, performance, and preference between mechanical and microprocessor prosthetic knee control technologies. A-B-A-B reversal design. Home, community, and laboratory environments. Twenty-one unilateral, transfemoral amputees. Mechanical control prosthetic knee versus microprocessor control prosthetic knee (Otto Bock C-Leg). Stair rating, hill rating and time, obstacle course time, divided attention task accuracy and time, Amputee Mobility Predictor score, step activity, Prosthesis Evaluation Questionnaire score, Medical Outcomes Study 36-Item Short-Form Health Survey score, self-reported frequency of stumbles and falls, and self-reported concentration required for ambulation. Stair descent score, hill descent time, and hill sound-side step length showed significant (P<.01) improvement with the C-Leg. Users reported a significant (P<.05) decrease in frequency of stumbles and falls, frustration with falling, and difficulty in multitasking while using the microprocessor knee. Subject satisfaction with the C-Leg was significantly (P<.001) greater than the mechanical control prosthesis. The study population showed improved performance when negotiating stairs and hills, reduced frequency of stumbling and falling, and a preference for the microprocessor control C-Leg as compared with the mechanical control prosthetic knee.

  6. [Noise origin and noise-induced complaints after heart valve replacement with mechanical prostheses].

    PubMed

    Moritz, A; Kobinia, G; Steinseifer, U; Neuwirth-Riedl, K; Reul, H; Windisch, A; Föger, A; Wolner, E

    1991-01-01

    143 patients were investigated in order to determine whether there is a difference in the intensity of the closing click between different mechanical heart valve prostheses. 35 had St. Jude Medical (SJM), 38 Duromedics Edwards (DE), 36 Björk Shiley Monostrut (BSM) and 34 had Carbomedics prostheses implanted. Sound pressure level determined at 1 meter distance was significantly higher for the DE 33.5 +/- 6 dB(A) and BSM 31 +/- 4 dB(A) than for the SJM 24 +/- 4 dB(A) and CM 25 +/- 6 dB(A) prostheses (p = 0.0001). Valves developing higher sound pressures were more frequently audible for the patients (p = 0.0012), caused more sleep disturbances (p = 0.024) and more complaints during daytime (p = 0.07). Significantly more patients carrying such valves wished to have a less noisy valve implanted (0.0047). Symptomatic patients wear louder valves, were younger, had better hearing and were more frequently in sinus rhythm. Valve diameter correlated with the developed sound pressure level. 349 patients answered a questionnaire after valve replacement with DE (256) or BSM (93) prostheses. 5% registered their noise-related complaints as being severe, but more than one third wished to have a less noisy valve implanted. The noise created by the closing click of mechanical prostheses causes significant complaints and this factor should be considered when a mechanical valve is selected.

  7. Two-dimensional FSI simulation of closing dynamics of a tilting disc mechanical heart valve

    PubMed Central

    Govindarajan, V.; Udaykumar, H.S.; Herbertson, L. H.; Deutsch, S.; Manning, K. B.; Chandran, K.B.

    2010-01-01

    The fluid dynamics during valve closure resulting in high shear flows and large residence times of particles has been implicated in platelet activation and thrombus formation in mechanical heart valves. Our previous studies with bi-leaflet valves have shown that large shear stresses induced in the gap between the leaflet edge and the valve housing results in relatively high platelet activation levels whereas flow between the leaflets results in shed vortices not conducive to platelet damage. In this study we compare the result of closing dynamics of a tilting disc valve with that of a bi-leaflet valve. The two-dimensional fluid-structure interaction analysis of a tilting disc valve closure mechanics is performed with a fixed grid Cartesian mesh flow solver with local mesh refinement, and a Lagrangian particle dynamic analysis for computation of potential for platelet activation. Throughout the simulation the flow remains in the laminar regime and the flow through the gap width is marked by the development of a shear layer which separates from the leaflet downstream of the valve. Zones of re-circulation are observed in the gap between the leaflet edge and the valve housing on the major orifice region of the tilting disc valve and are seen to be migrating towards the minor orifice region. Jet flow is observed at the minor orifice region and a vortex is formed which sheds in the direction of fluid motion as observed in experiments using PIV measurements. The activation parameter computed for the tilting disc valve, at the time of closure was found to be 2.7 times greater than that of the bi-leaflet mechanical valve and was found to be in the vicinity of the minor orifice region mainly due to the migration of vortical structures from the major to the minor orifice region during the leaflet rebound of the closing phase. PMID:20209095

  8. A detailed fluid mechanics study of tilting disk mechanical heart valve closure and the implications to blood damage.

    PubMed

    Manning, Keefe B; Herbertson, Luke H; Fontaine, Arnold A; Deutsch, Steven

    2008-08-01

    Hemolysis and thrombosis are among the most detrimental effects associated with mechanical heart valves. The strength and structure of the flows generated by the closure of mechanical heart valves can be correlated with the extent of blood damage. In this in vitro study, a tilting disk mechanical heart valve has been modified to measure the flow created within the valve housing during the closing phase. This is the first study to focus on the region just upstream of the mitral valve occluder during this part of the cardiac cycle, where cavitation is known to occur and blood damage is most severe. Closure of the tilting disk valve was studied in a "single shot" chamber driven by a pneumatic pump. Laser Doppler velocimetry was used to measure all three velocity components over a 30 ms period encompassing the initial valve impact and rebound. An acrylic window placed in the housing enabled us to make flow measurements as close as 200 microm away from the closed occluder. Velocity profiles reveal the development of an atrial vortex on the major orifice side of the valve shed off the tip of the leaflet. The vortex strength makes this region susceptible to cavitation. Mean and maximum axial velocities as high as 7 ms and 20 ms were recorded, respectively. At closure, peak wall shear rates of 80,000 s(-1) were calculated close to the valve tip. The region of the flow examined here has been identified as a likely location of hemolysis and thrombosis in tilting disk valves. The results of this first comprehensive study measuring the flow within the housing of a tilting disk valve may be helpful in minimizing the extent of blood damage through the combined efforts of experimental and computational fluid dynamics to improve mechanical heart valve designs.

  9. Biological and mechanical evaluation of a Bio-Hybrid scaffold for autologous valve tissue engineering.

    PubMed

    Jahnavi, S; Saravanan, U; Arthi, N; Bhuvaneshwar, G S; Kumary, T V; Rajan, S; Verma, R S

    2017-04-01

    Major challenge in heart valve tissue engineering for paediatric patients is the development of an autologous valve with regenerative capacity. Hybrid tissue engineering approach is recently gaining popularity to design scaffolds with desired biological and mechanical properties that can remodel post implantation. In this study, we fabricated aligned nanofibrous Bio-Hybrid scaffold made of decellularized bovine pericardium: polycaprolactone-chitosan with optimized polymer thickness to yield the desired biological and mechanical properties. CD44(+), αSMA(+), Vimentin(+) and CD105(-) human valve interstitial cells were isolated and seeded on these Bio-Hybrid scaffolds. Subsequent biological evaluation revealed interstitial cell proliferation with dense extra cellular matrix deposition that indicated the viability for growth and proliferation of seeded cells on the scaffolds. Uniaxial mechanical tests along axial direction showed that the Bio-Hybrid scaffolds has at least 20 times the strength of the native valves and its stiffness is nearly 3 times more than that of native valves. Biaxial and uniaxial mechanical studies on valve interstitial cells cultured Bio-Hybrid scaffolds revealed that the response along the axial and circumferential direction was different, similar to native valves. Overall, our findings suggest that Bio-Hybrid scaffold is a promising material for future development of regenerative heart valve constructs in children. Copyright © 2016 Elsevier B.V. All rights reserved.

  10. [Thrombolysis in left mechanical prosthetic heart valve obstruction by thrombus. Following and results].

    PubMed

    Valencia-Sánchez, Jesús Salvador; Arriaga-Nava, Roberto

    2014-01-01

    INTRODUCCIÓN: la obstrucción de la válvula mecánica cardiaca izquierda por trombo es una complicación grave. Los factores relacionados con la mortalidad son clase funcional, tipo de prótesis valvular y urgencia de la cirugía. La trombólisis representa una opción terapéutica a la cirugía cardiaca. El objetivo de esta investigación fue analizar el papel de la trombólisis en el manejo de la válvula mecánica cardiaca izquierda obstruida por trombo. MÉTODOS: se estudiaron 22 casos consecutivos sometidos a trombólisis en el Hospital de Cardiología del Centro Médico Nacional Siglo XXI, bajo dos diferentes circunstancias: con edema agudo pulmonar y estado de choque en clase funcional IV y con clases funcionales I y II. Se realizó monitoreo clínico, ecocardiográfico y fluoroscopia.

  11. Recommendations for the imaging assessment of prosthetic heart valves: a report from the European Association of Cardiovascular Imaging endorsed by the Chinese Society of Echocardiography, the Inter-American Society of Echocardiography, and the Brazilian Department of Cardiovascular Imaging.

    PubMed

    Lancellotti, Patrizio; Pibarot, Philippe; Chambers, John; Edvardsen, Thor; Delgado, Victoria; Dulgheru, Raluca; Pepi, Mauro; Cosyns, Bernard; Dweck, Mark R; Garbi, Madalina; Magne, Julien; Nieman, Koen; Rosenhek, Raphael; Bernard, Anne; Lowenstein, Jorge; Vieira, Marcelo Luiz Campos; Rabischoffsky, Arnaldo; Vyhmeister, Rodrigo Hernández; Zhou, Xiao; Zhang, Yun; Zamorano, Jose-Luis; Habib, Gilbert

    2016-06-01

    Prosthetic heart valve (PHV) dysfunction is rare but potentially life-threatening. Although often challenging, establishing the exact cause of PHV dysfunction is essential to determine the appropriate treatment strategy. In clinical practice, a comprehensive approach that integrates several parameters of valve morphology and function assessed with 2D/3D transthoracic and transoesophageal echocardiography is a key to appropriately detect and quantitate PHV dysfunction. Cinefluoroscopy, multidetector computed tomography, cardiac magnetic resonance imaging, and to a lesser extent, nuclear imaging are complementary tools for the diagnosis and management of PHV complications. The present document provides recommendations for the use of multimodality imaging in the assessment of PHVs. Published on behalf of the European Society of Cardiology. All rights reserved. © The Author 2016. For permissions please email: journals.permissions@oup.com.

  12. Mitral Valve Mechanics Following Posterior Leaflet Patch Augmentation

    PubMed Central

    Rahmani, Azadeh; Rasmussen, Ann Q.; Honge, Jesper L.; Ostli, Bjorn; Levine, Robert A.; Hagège, Albert; Nygaard, Hans; Nielsen, Sten L.; Jensen, Morten O.

    2013-01-01

    Background and aim of the study Attention towards the optimization of mitral valve repair methods is increasing. Patch augmentation is one strategy used to treat functional ischemic mitral regurgitation (FIMR). The study aim was to investigate the force balance changes in specific chordae tendineae emanating from the posterior papillary muscle in a FIMR-simulated valve, following posterior leaflet patch augmentation. Methods Mitral valves were obtained from 12 pigs (body weight 80 kg). An in vitro test set-up simulating the left ventricle was used to hold the valves. The left ventricular pressure was regulated with water to simulate different static pressures during valve closure. A standardized oval pericardial patch (17 × 29 mm) was introduced into the posterior leaflet from mid P2 to the end of the P3 scallop. Dedicated miniature transducers were used to record the forces exerted on the chordae tendineae. Data were acquired before and after 12 mm posterior and 5 mm apical posterior papillary muscle displacement to simulate the effect from one of the main contributors of FIMR, before and after patch augmentation. Results The effect of displacing the posterior papillary muscle induced tethering on the intermediate chordae tendineae to the posterior leaflet, and resulted in a 39.8% force increase (p = 0.014). Posterior leaflet patch augmentation of the FIMR valve induced a 31.1% force decrease (p = 0.007). There was no difference in force between the healthy and the repaired valve simulations (p = 0.773). Conclusion Posterior leaflet patch augmentation significantly reduced the forces exerted on the intermediate chordae tendineae from the posterior papillary muscle following FIMR simulation. As changes in chordal tension lead to a redistribution of the total stress exerted on the valve, patch augmentation may have an adverse long-term influence on mitral valve function and remodeling. PMID:23610985

  13. Mechanism utilizing a single rocker arm for controlling an internal combustion engine valve

    SciTech Connect

    Burandt, C.O.

    1988-02-09

    This patent describes in combination with an internal combustion engine having a rotatable camshaft, a cam on the camshaft, a combustion chamber and a reciprocable valve member for opening and closing a valve port in communication with the combustion chamber, a mechanism for operating the valve member comprising a rocker arm having first and second angularly disposed and integrally connected legs. The first leg having a cam follower suface thereon having a first section thereof extending in the same general direction that the valve member reciprocates and having a second section thereof curving toward the valve member and toward the direction in which the valve member reciprocates, means mounting the rocker arm for rocking movement about a first axis, and means for shifting the first axis relative to the camshaft in also the same general direction the valve member reciprocates so that various portions of the first and second sections of the cam follower surface on the first leg are relatively engageable with the cam, sufficient shifting of the first axis in the same general direction producing a desmodromic action, and the second leg including a single portion thereof engaging the valve member so that only the single portion acts on the valve member.

  14. A low-volume tester for the thrombogenic potential of mechanical heart valve prostheses.

    PubMed

    Linde, Torsten; Hamilton, Kathrin F; Timms, Daniel L; Schmitz-Rode, Thomas; Steinseifer, Ulrich

    2011-09-01

    During the development of a mechanical heart valve prosthesis, many studies are conducted to guarantee its correct function. Currently, investigations into the thrombogenic potential of a valve after its replacement are conducted with expensive and time-consuming chronic animal trials. Hence, the study aim was to develop and test an alternative system to resolve such thrombogenic issues. The Thrombosis Tester of the Helmholtz Institute Aachen (THIA II) has a reasonably small priming volume (220-270 ml) that allows analysis of the thrombogenic potential of two valves, using one human blood bottle. Hydrodynamic evaluation demonstrated an absolutely stable physiological pressure and flow progression at the aortic and pulmonary positions. A sinus geometry of the human aortic root is implemented downstream of the valve in order to guarantee physiological leaflet motion. The tester remained absolutely thrombus-free during several tests carried out with minimally anticoagulated porcine blood, while the valves showed reproducible thrombus formation in reasonable locations. Tests with fully heparinized porcine blood showed that a soft silicon fixture for the valve could reduce hemolysis in the THIA II. This in-vitro test protocol can enable the optimization of a valve design during the early stages of its research and development. The system can provide a unique and suitable supplement to animal trials for testing thrombogenic performance, under constant and reproducible boundary conditions, including considerable physiological and pathological circumstances such as the influence of valve position (aortic, pulmonic), and a comparison of different valve types.

  15. Mechanism of valve failure and efficacy of reintervention through catheterization in patients with bioprosthetic valves in the pulmonary position

    PubMed Central

    Callahan, Ryan; Bergersen, Lisa; Baird, Christopher W; Porras, Diego; Esch, Jesse J; Lock, James E; Marshall, Audrey C

    2017-01-01

    Background: Surgical and transcatheter bioprosthetic valves (BPVs) in the pulmonary position in patients with congenital heart disease may ultimately fail and undergo transcatheter reintervention. Angiographic assessment of the mechanism of BPV failure has not been previously described. Aims: The aim of this study was to determine the mode of BPV failure (stenosis/regurgitation) requiring transcatheter reintervention and to describe the angiographic characteristics of the failed BPVs and report the types and efficacy of reinterventions. Materials and Methods: This is a retrospective single-center review of consecutive patients who previously underwent pulmonary BPV placement (surgical or transcatheter) and subsequently underwent percutaneous reintervention from 2005 to 2014. Results: Fifty-five patients with surgical (41) and transcutaneous pulmonary valve (TPV) (14) implantation of BPVs underwent 66 catheter reinterventions. The surgically implanted valves underwent fifty reinterventions for indications including 16 for stenosis, seven for regurgitation, and 27 for both, predominantly associated with leaflet immobility, calcification, and thickening. Among TPVs, pulmonary stenosis (PS) was the exclusive failure mode, mainly due to loss of stent integrity (10) and endocarditis (4). Following reintervention, there was a reduction of right ventricular outflow tract gradient from 43 ± 16 mmHg to 16 ± 10 mmHg (P < 0.001) and RVp/AO ratio from 0.8 ± 0.2 to 0.5 ± 0.2 (P < 0.001). Reintervention with TPV placement was performed in 45 (82%) patients (34 surgical, 11 transcatheter) with no significant postintervention regurgitation or paravalvular leak. Conclusion: Failing surgically implanted BPVs demonstrate leaflet calcification, thickness, and immobility leading to PS and/or regurgitation while the mechanism of TPV failure in the short- to mid-term is stenosis, mainly from loss of stent integrity. This can be effectively treated with a catheter-based approach

  16. The measurement of opening angle and orifice area of a bileaflet mechanical valve using multidetector computed tomography.

    PubMed

    Lee, Dong-Hyeon; Youn, Ho-Joong; Shim, Sung-Bo; Lee, Sun-Hee; Jung, Jung-Im; Jung, Seung-Eun; Choi, Yun-Seok; Park, Chul-Soo; Oh, Yong-Seog; Chung, Wook-Sung; Kim, Jae-Hyung

    2009-04-01

    The aim of this study was to assess mechanical valve function using 64-slice multidetector computed tomography (MDCT). In 20 patients (mean age, 50+/-12 years; male-to-female ratio, 10:10), 30 St. Jude bileaflet mechanical valves (15 aortic and 15 mitral valves) were evaluated using MDCT. We selected images vertical and parallel to the mechanical valve. The valve orifice area (OA) and valve length were determined by manual tracing and the opening and closing angles were measured using a protractor. The OA and length of the mechanical valves were compared with the manufacturer's values. The geometric orifice areas (GOAs) based on the manufacturer's values and the OAs determined by MDCT were 3.4+/-0.2 cm(2) and 3.4+/-0.3 cm(2) for the mitral valves and 2.1+/-0.3 cm(2) and 2.1+/-0.4 cm(2) for the aortic valves, respectively. The correlation coefficients between the OA measures were 0.433 for the mitral valves and 0.874 for the aortic valves (both p<0.001). The lengths based on the manufacturer's values and determined by MDCT were 29.3+/-1.99 mm and 29.6+/-1.65 mm for the mitral valves and 21.5+/-2.1 mm and 20.7+/-2.3 mm for the aortic valves, respectively. The correlation coefficients between the measures were 0.651 for the mitral valve and 0.846 for the aortic valve (both p<0.001). The opening and closing angles determined by MDCT were 10.9+/-0.6 degrees and 131.1+/-3.2 degrees for the mitral valves and 11.1+/-0.9 degrees and 120.6+/-1.7 degrees for the aortic valves, respectively. MDCT is an accurate modality with which to assess the function and morphology of bileaflet mechanical valves.

  17. [Selection of the prosthesis for aortic valve replacement: mechanical or bio?].

    PubMed

    Tokunaga, Shigehiko; Tominaga, Ryuji

    2007-03-01

    To clarify the effect of the valve selection on the patients' prognosis, long-term outcome of the patients undergone isolated aortic valve replacement (AVR) with the mechanical or bioprosthetic valve in our institution were investigated. In protocol 1, patients of all ages with isolated AVR (n = 472, composed of 166 who received a bioprosthesic valve [group B] and 306 who received a mechanical valve [Group MI) between 1975 and 2004 were investigated. In protocol 2, primary AVR patients aged 50-65 years (n = 184, composed of 47 in group B and 137 in group M) were compared. There were no significant differences in freedom from cardiac death, freedom from bleeding, and freedom from endocarditis in Protocols 1 and 2. Significantly fewer redo AVRs were required in group M in both protocols 1 and 2. However, group M was significantly worse in terms of freedom from thromboembolism in protocol 2. As a result, group M was superior to group B in freedom from valve-related events when redo AVR included. When redo AVR was excluded, there was no difference between the two groups in freedom from valve-related events in both protocols 1 and 2. There may thus be an advantage in selecting bioprosthetic valves in young adult patients who required AVR if they accepts the possibility of redo AVR in future.

  18. Novel differential mechanism enabling two DOF from a single actuator: application to a prosthetic hand.

    PubMed

    Belter, Joseph T; Dollar, Aaron M

    2013-06-01

    There will always be a drive to reduce the complexity, weight, and cost of mobile platforms while increasing their inherent capabilities. This paper presents a novel method of increasing the range of achievable grasp configurations of a mechatronic hand controlled by a single actuator. By utilizing the entire actuator space, the hand is able to perform four grasp types (lateral, precision, precision/power, and power) with a single input resulting in a potentially lighter and simpler hand design. We demonstrate this strategy in a prototype hand that is evaluated to determine the benefit of this method over the addition of a second actuator. Results show a decrease in weight but a 0.8 sec transition time between grasp types with the proposed method. The prototype hand can be controlled by a single EMG signal that can command a change in grasp type or an opening/closing of the hand. We discuss the potential of this mechanism to improve prosthetic hand design as compared to current myoelectric systems.

  19. [Study of physical-mechanic characteristics of prosthetic construction after their adjustment with the use of laser welding and hot metal adding].

    PubMed

    Gvetadze, R Sh; Rusanov, F S; Mikhas'kov, S V

    2011-01-01

    Study of physical-mechanic characteristics of connecting joints of beam construction after laser welding and hot metal adding was performed. Increase of microhardness of joints as well as small reduction of bending strength of prosthetic constructions was established.

  20. Transient, three-dimensional flow field simulation through a mechanical, trileaflet heart valve prosthesis.

    PubMed

    Kaufmann, Tim A S; Linde, Torsten; Cuenca-Navalon, Elena; Schmitz, Christoph; Hormes, Marcus; Schmitz-Rode, Thomas; Steinseifer, Ulrich

    2011-01-01

    Thromboembolic complications are one of the major challenges faced by designers and researchers in development of artificial organs with blood-contacting devices such as heart valve prostheses, especially mechanical valves. Besides increasing the thrombogenic potential, these valves change the hydrodynamic performance of the heart. In this study, the flow through a trileaflet, mechanical heart valve prosthesis was modeled with transient computational fluid dynamics to analyze flow patterns causing thrombus formations on valves. The valve was simulated under conditions of a test rig (THIA II), which was specially designed to analyze different valves with respect to thrombosis. The main goal of this study was to mimic the exact conditions of the test rig to be able to compare numerical and experimental results. The boundary conditions were obtained from experimental data as leaflet kinematics and pressure profiles. One complete cycle of the valve was simulated. Numerical flow and pressure results were analyzed and compared with experimental results. Shear stress and shear rates were determined with respect to thrombogenic potential, especially in the pivot regions, which seem to be the main influence for activation and deposition of thrombocytes. Approximately 0.7% of the blood volume moving through the fluid domain of the valve was exposed to shear rates high enough to cause platelet activation. However, shear rates of up to 20,000 s⁻¹ occurred in pivot regions. The pressure differences between the simulation and experimental data were approximately 2.5% during systole and increased up to 25% during diastole. The presented method, however, can be used to gain more information about the flow through different heart valve prostheses and, thus, improve the development process.

  1. Bridge Therapy Outcomes in Patients With Mechanical Heart Valves.

    PubMed

    Delate, Thomas; Meisinger, Stephanie M; Witt, Daniel M; Jenkins, Daniel; Douketis, James D; Clark, Nathan P

    2016-01-01

    Bridge therapy is associated with an increased risk of major bleeding in patients with atrial fibrillation and venous thromboembolism (TE) without a corresponding reduction in TE. The benefits of bridge therapy in patients with mechanical heart valve (MHV) prostheses interrupting warfarin for invasive procedures are not well described. A retrospective cohort study was conducted at an integrated health-care delivery system. Anticoagulated patients with MHV interrupting warfarin for invasive diagnostic or surgical procedures between January 1, 2006, and March 31, 2012, were identified. Patients were categorized according to exposure to bridge therapy during the periprocedural period and TE risk (low, medium, and high). Outcomes validated via manual chart review included clinically relevant bleeding, TE, and all-cause mortality in the 30 days following the procedure. There were 547 procedures in 355 patients meeting inclusion criteria. Mean cohort age was 65.2 years, and 38% were female. Bridge therapy was utilized in 466 (85.2%) procedures (95.2%, 77.3%, and 65.8% of high, medium, and low TE risk category procedures, respectively). The 30-day rate of clinically relevant bleeding was numerically higher in bridged (5.8%; 95% confidence interval [CI], 3.9%-8.3%) versus not bridged procedures (1.2%; 95% CI, <0.1%-6.7%; P = .102). No TEs or deaths were identified. The use of bridge therapy is common among patients with MHV and may be associated with increased bleeding risk. Further research is needed to determine whether bridge therapy reduces TE in patients with MHV interrupting warfarin for invasive procedures.

  2. Early postpartum mitral valve thrombosis requiring extra corporeal membrane oxygenation before successful valve replacement.

    PubMed

    Halldorsdottir, H; Nordström, J; Brattström, O; Sennström, M M; Sartipy, U; Mattsson, E

    2016-05-01

    Pregnancy is associated with an increased risk of thrombosis in women with mechanical prosthetic heart valves. We present the case of a 29-year-old woman who developed early postpartum mitral valve thrombus after an elective cesarean delivery. The patient had a mechanical mitral valve and was treated with warfarin in the second trimester, which was replaced with high-dose dalteparin during late pregnancy. Elective cesarean delivery was performed under general anesthesia at 37weeks of gestation. The patient was admitted to the intensive care unit for postoperative care and within 30min she developed dyspnea and hypoxia requiring mechanical ventilation. She deteriorated rapidly and developed pulmonary edema, worsening hypoxia and severe acidosis. Urgent extra corporeal membrane oxygenation was initiated. Transesophageal echocardiography revealed a mitral valve thrombus. The patient underwent a successful mitral valve replacement after three days on extra corporeal membrane oxygenation. This case highlights the importance of multidisciplinary care and frequent monitoring of anticoagulation during care of pregnant women with prosthetic heart valves.

  3. Fiber-reinforced hydrogel scaffolds for heart valve tissue engineering.

    PubMed

    Eslami, Maryam; Vrana, Nihal Engin; Zorlutuna, Pinar; Sant, Shilpa; Jung, Sungmi; Masoumi, Nafiseh; Khavari-Nejad, Ramazan Ali; Javadi, Gholamreza; Khademhosseini, Ali

    2014-09-01

    Heart valve-related disorders are among the major causes of death worldwide. Although prosthetic valves are widely used to treat this pathology, current prosthetic grafts cannot grow with the patient while maintaining normal valve mechanical and hemodynamic properties. Tissue engineering may provide a possible solution to this issue through using biodegradable scaffolds and patients' own cells. Despite their similarity to heart valve tissue, most hydrogel scaffolds are not mechanically suitable for the dynamic stresses of the heart valve microenvironment. In this study, we integrated electrospun poly(glycerol sebacate) (PGS)-poly(ɛ-caprolactone) (PCL) microfiber scaffolds, which possess enhanced mechanical properties for heart valve engineering, within a hybrid hydrogel made from methacrylated hyaluronic acid and methacrylated gelatin. Sheep mitral valvular interstitial cells were encapsulated in the hydrogel and evaluated in hydrogel-only, PGS-PCL scaffold-only, and composite scaffold conditions. Although the cellular viability and metabolic activity were similar among all scaffold types, the presence of the hydrogel improved the three-dimensional distribution of mitral valvular interstitial cells. As seen by similar values in both the Young's modulus and the ultimate tensile strength between the PGS-PCL scaffolds and the composites, microfibrous scaffolds preserved their mechanical properties in the presence of the hydrogels. Compared to electrospun or hydrogel scaffolds alone, this combined system may provide a more suitable three-dimensional structure for generating scaffolds for heart valve tissue engineering. © The Author(s) 2014 Reprints and permissions: sagepub.co.uk/journalsPermissions.nav.

  4. Characterization of small microfluidic valves for studies of mechanical properties of bacteria

    SciTech Connect

    Yang, Da; Greer, Clayton M.; Jones, Branndon P.; Jennings, Anna D.; Retterer, Scott T.; Männik, Jaan

    2015-09-02

    Lab-on-a-chip platforms present many new opportunities to study bacterial cells and cellular assemblies. Here, the authors describe a new platform that allows us to apply uniaxial stress to individual bacterial cells while observing the cell and its subcellular assemblies using a high resolution optical microscope. The microfluidic chip consists of arrays of miniature pressure actuated valves. By placing a bacterium under one of such valves and partially closing the valve by externally applied pressure, the cell can be deformed. Although large pressure actuated valves used in integrated fluidic circuits have been extensively studied previously, here the authors downsize those microfluidic valves and use flow channels with rectangular cross-sections to maintain the bacteria in contact with cell culture medium during the experiments. The closure of these valves has not been characterized before. First, these valves are modeled using finite element analysis, and then compared the modeling results with the actual closing profiles of the valves, which is determined from absorption measurements. The measurements and modeling show with good agreement that the deflection of valves is a linear function of externally applied pressure and the deflection scales proportionally to the width of the flow channel. In addition to characterizing the valve, the authors show at a proof-of-principle level that it can be used to deform a bacterial cell at considerable magnitude. They found the largest deformations in 5 μm wide channels where the bacterial width and length increase by 1.6 and 1.25 times, respectively. Narrower and broader channels are less optimal for these studies. Finally, the platform presents a promising approach to probe, in a quantitative and systematic way, the mechanical properties of not only bacterial cells but possibly also yeast and other single-celled organisms.

  5. Rapid 3D printing of anatomically accurate and mechanically heterogeneous aortic valve hydrogel scaffolds.

    PubMed

    Hockaday, L A; Kang, K H; Colangelo, N W; Cheung, P Y C; Duan, B; Malone, E; Wu, J; Girardi, L N; Bonassar, L J; Lipson, H; Chu, C C; Butcher, J T

    2012-09-01

    The aortic valve exhibits complex three-dimensional (3D) anatomy and heterogeneity essential for the long-term efficient biomechanical function. These are, however, challenging to mimic in de novo engineered living tissue valve strategies. We present a novel simultaneous 3D printing/photocrosslinking technique for rapidly engineering complex, heterogeneous aortic valve scaffolds. Native anatomic and axisymmetric aortic valve geometries (root wall and tri-leaflets) with 12-22 mm inner diameters (ID) were 3D printed with poly-ethylene glycol-diacrylate (PEG-DA) hydrogels (700 or 8000 MW) supplemented with alginate. 3D printing geometric accuracy was quantified and compared using Micro-CT. Porcine aortic valve interstitial cells (PAVIC) seeded scaffolds were cultured for up to 21 days. Results showed that blended PEG-DA scaffolds could achieve over tenfold range in elastic modulus (5.3±0.9 to 74.6±1.5 kPa). 3D printing times for valve conduits with mechanically contrasting hydrogels were optimized to 14 to 45 min, increasing linearly with conduit diameter. Larger printed valves had greater shape fidelity (93.3±2.6, 85.1±2.0 and 73.3±5.2% for 22, 17 and 12 mm ID porcine valves; 89.1±4.0, 84.1±5.6 and 66.6±5.2% for simplified valves). PAVIC seeded scaffolds maintained near 100% viability over 21 days. These results demonstrate that 3D hydrogel printing with controlled photocrosslinking can rapidly fabricate anatomical heterogeneous valve conduits that support cell engraftment.

  6. Characterization of small microfluidic valves for studies of mechanical properties of bacteria

    DOE PAGES

    Yang, Da; Greer, Clayton M.; Jones, Branndon P.; ...

    2015-09-02

    Lab-on-a-chip platforms present many new opportunities to study bacterial cells and cellular assemblies. Here, the authors describe a new platform that allows us to apply uniaxial stress to individual bacterial cells while observing the cell and its subcellular assemblies using a high resolution optical microscope. The microfluidic chip consists of arrays of miniature pressure actuated valves. By placing a bacterium under one of such valves and partially closing the valve by externally applied pressure, the cell can be deformed. Although large pressure actuated valves used in integrated fluidic circuits have been extensively studied previously, here the authors downsize those microfluidicmore » valves and use flow channels with rectangular cross-sections to maintain the bacteria in contact with cell culture medium during the experiments. The closure of these valves has not been characterized before. First, these valves are modeled using finite element analysis, and then compared the modeling results with the actual closing profiles of the valves, which is determined from absorption measurements. The measurements and modeling show with good agreement that the deflection of valves is a linear function of externally applied pressure and the deflection scales proportionally to the width of the flow channel. In addition to characterizing the valve, the authors show at a proof-of-principle level that it can be used to deform a bacterial cell at considerable magnitude. They found the largest deformations in 5 μm wide channels where the bacterial width and length increase by 1.6 and 1.25 times, respectively. Narrower and broader channels are less optimal for these studies. Finally, the platform presents a promising approach to probe, in a quantitative and systematic way, the mechanical properties of not only bacterial cells but possibly also yeast and other single-celled organisms.« less

  7. Valve timing adjusting mechanism for internal combustion engine for adjusting timing of intake valve and/or exhaust valve corresponding to engine operating conditions

    SciTech Connect

    Akassaka, A.; Suga, S.; Sawada, T.

    1989-03-14

    A valve timing adjusting mechanism for an internal combustion engine is described, comprising: a camshaft carrying a cam for driving one of an intake valve and an exhaust valve, the camshaft having a section formed with first helical gear teeth; a cam pulley engaging a timing belt driven by the engine for rotation in synchronism with engine revolution, the cam pulley having second helical gear teeth; a ring gear having inner and outer helical gear teeth engageable with the first and second gear teeth of the camshaft and the cam pulley; first means for defining an enclosed chamber facing one planar face of the ring gear and connected with a fluid pressure source to receive pressurized fluid therefrom; a spring means associated with the other planar face of the ring gear for exerting an initial biasing force on the ring gear in opposition to the force due to the pressure on the ring gear from the enclosed chamber; and second means for controlling the fluid pressure introduced into the enclosed chamber in accordance with engine operating conditions so as to shift the ring gear between two positions.

  8. Consequence of patient substitution of nattokinase for warfarin after aortic valve replacement with a mechanical prosthesis

    PubMed Central

    Elahi, Maqsood M.; Choi, Charles H.; Konda, Subbareddy

    2015-01-01

    This report describes a patient's self-substitution of nattokinase for the vitamin K antagonist warfarin after aortic valve replacement with a mechanical prosthesis. Nattokinase is an enzyme derived from a popular fermented soybean preparation in Japan (natto), which has fibrinolytic properties and is gaining popularity in nontraditional health journals and nonmedical health websites as an over-the-counter thrombolytic. After nearly a year of use of nattokinase without warfarin, the patient developed thrombus on the mechanical valve and underwent successful repeat valve replacement. We believe this is the first documented case of nattokinase being used as a substitute for warfarin after valve replacement, and we strongly discourage its use for this purpose. PMID:25552810

  9. Consequence of patient substitution of nattokinase for warfarin after aortic valve replacement with a mechanical prosthesis.

    PubMed

    Elahi, Maqsood M; Choi, Charles H; Konda, Subbareddy; Shake, Jay G

    2015-01-01

    This report describes a patient's self-substitution of nattokinase for the vitamin K antagonist warfarin after aortic valve replacement with a mechanical prosthesis. Nattokinase is an enzyme derived from a popular fermented soybean preparation in Japan (natto), which has fibrinolytic properties and is gaining popularity in nontraditional health journals and nonmedical health websites as an over-the-counter thrombolytic. After nearly a year of use of nattokinase without warfarin, the patient developed thrombus on the mechanical valve and underwent successful repeat valve replacement. We believe this is the first documented case of nattokinase being used as a substitute for warfarin after valve replacement, and we strongly discourage its use for this purpose.

  10. Rocker arm spring for a valve actuating mechanism of an internal combustion engine

    SciTech Connect

    Nouno, Y.

    1987-06-30

    A rocker arm spring is described for use in a valve actuating mechanism of an internal combustion engine having a cylinder head, an overhead camshaft mounted on the cylinder head, and a valve stem extending through the cylinder head. The valve actuating mechanism includes a rocker arm having a first end and a second end, a universal pivot swingably supporting the first end of the rocker arm on the cylinder head of the engine, the second end of the rocker arm in contact with the valve stem, and a cam on the overhead camshaft engaging from above a portion of the rocker arm intermediate the first and second ends to cause the rocker arm to swing about.

  11. The effects of prosthetic foot stiffness on transtibial amputee walking mechanics and balance control during turning.

    PubMed

    Shell, Courtney E; Segal, Ava D; Klute, Glenn K; Neptune, Richard R

    2017-08-15

    Little evidence exists regarding how prosthesis design characteristics affect performance in tasks that challenge mediolateral balance such as turning. This study assesses the influence of prosthetic foot stiffness on amputee walking mechanics and balance control during a continuous turning task. Three-dimensional kinematic and kinetic data were collected from eight unilateral transtibial amputees as they walked overground at self-selected speed clockwise and counterclockwise around a 1-meter circle and along a straight line. Subjects performed the walking tasks wearing three different ankle-foot prostheses that spanned a range of sagittal- and coronal-plane stiffness levels. A decrease in stiffness increased residual ankle dorsiflexion (10-13°), caused smaller adaptations (<5°) in proximal joint angles, decreased residual and increased intact limb body support, increased residual limb propulsion and increased intact limb braking for all tasks. While changes in sagittal-plane joint work due to decreased stiffness were generally consistent across tasks, effects on coronal-plane hip work were task-dependent. When the residual limb was on the inside of the turn and during straight-line walking, coronal-plane hip work increased and coronal-plane peak-to-peak range of whole-body angular momentum decreased with decreased stiffness. Changes in sagittal-plane kinematics and kinetics were similar to those previously observed in straight-line walking. Mediolateral balance improved with decreased stiffness, but adaptations in coronal-plane angles, work and ground reaction force impulses were less systematic than those in sagittal-plane measures. Effects of stiffness varied with the residual limb inside versus outside the turn, which suggests that actively adjusting stiffness to turn direction may be beneficial. Copyright © 2017 Elsevier Ltd. All rights reserved.

  12. Mechanical biocompatibility of prosthetic meshes: a comprehensive protocol for mechanical characterization.

    PubMed

    Maurer, M M; Röhrnbauer, B; Feola, A; Deprest, J; Mazza, E

    2014-12-01

    This study is aimed at a comprehensive and extensive characterization of the mechanical biocompatibility of mesh prostheses. A robust and simple experimental protocol and a set of parameters is proposed, addressing stiffness under uniaxial and biaxial loading conditions, anisotropy, influence of prior deformation history, local mismatch of deformation mechanisms, and changes in mechanical properties when embedded in a homogeneous matrix. These parameters can form the basis for comparison of different mesh types and for evaluation of their mechanical biocompatibility. Measurements were performed on nine mesh types used for hernia and/or pelvic repair, including heavier as well as lighter implants and covering a wide range of mechanical responses. A total of 93 experiments were performed and all parameters are represented for each mesh in a single diagram to facilitate the quantitative assessment of implant characteristics and their comparison. The mechanics of implants is a critical factor determining clinical performance which should be accounted for in mesh selection and for development of future implants.

  13. Thrombolytic Therapy for Right-Sided Mechanical Pulmonic and Tricuspid Valves: The Largest Survival Analysis to Date

    PubMed Central

    Taherkhani, Maryam; Hashemi, Seyed Reza; Hekmat, Manouchehr; Safi, Morteza; Taherkhani, Adineh

    2015-01-01

    Data regarding thrombolytic treatment of right-sided mechanical valve thrombosis are almost nonexistent, and all current guidelines arise from very small case series. We retrospectively studied the in-hospital and long-term outcome data of a larger series of patients who had received, from September 2005 through June 2012, thrombolytic therapy for right-sided mechanical pulmonary valve or tricuspid valve thrombosis. We identified 16 patients aged 8–67 years who had undergone thrombolytic therapy for definite thrombotic mechanical valve obstruction in the tricuspid or pulmonary valve position (8 in each position). All study patients except one had subtherapeutic international normalized ratios. The 8 patients with pulmonary mechanical valve thrombosis had a 100% response rate to thrombolytic therapy, and their in-hospital survival rate was also 100%. The 8 patients with tricuspid mechanical valve thrombosis had a 75% response rate to thrombolytic therapy, with an in-hospital survival rate of 87.5%. The one-year survival rate for mechanical valve thrombosis treated with thrombolytic therapy (whether pulmonary or tricuspid) was 87.5%. On the basis of our data, we recommend that thrombolytic therapy remain the first-line therapy for right-sided mechanical valve thrombosis in adults or children—including children with complex congenital heart disease and patients with mechanical pulmonary valve thrombosis. Surgery should be reserved for patients in whom this treatment fails. PMID:26664307

  14. Thrombolytic Therapy for Right-Sided Mechanical Pulmonic and Tricuspid Valves: The Largest Survival Analysis to Date.

    PubMed

    Taherkhani, Maryam; Hashemi, Seyed Reza; Hekmat, Manouchehr; Safi, Morteza; Taherkhani, Adineh; Movahed, Mohammad Reza

    2015-12-01

    Data regarding thrombolytic treatment of right-sided mechanical valve thrombosis are almost nonexistent, and all current guidelines arise from very small case series. We retrospectively studied the in-hospital and long-term outcome data of a larger series of patients who had received, from September 2005 through June 2012, thrombolytic therapy for right-sided mechanical pulmonary valve or tricuspid valve thrombosis. We identified 16 patients aged 8-67 years who had undergone thrombolytic therapy for definite thrombotic mechanical valve obstruction in the tricuspid or pulmonary valve position (8 in each position). All study patients except one had subtherapeutic international normalized ratios. The 8 patients with pulmonary mechanical valve thrombosis had a 100% response rate to thrombolytic therapy, and their in-hospital survival rate was also 100%. The 8 patients with tricuspid mechanical valve thrombosis had a 75% response rate to thrombolytic therapy, with an in-hospital survival rate of 87.5%. The one-year survival rate for mechanical valve thrombosis treated with thrombolytic therapy (whether pulmonary or tricuspid) was 87.5%. On the basis of our data, we recommend that thrombolytic therapy remain the first-line therapy for right-sided mechanical valve thrombosis in adults or children-including children with complex congenital heart disease and patients with mechanical pulmonary valve thrombosis. Surgery should be reserved for patients in whom this treatment fails.

  15. Classification of heart valve condition using acoustic measurements

    SciTech Connect

    Clark, G.

    1994-11-15

    Prosthetic heart valves and the many great strides in valve design have been responsible for extending the life spans of many people with serious heart conditions. Even though the prosthetic valves are extremely reliable, they are eventually susceptible to long-term fatigue and structural failure effects expected from mechanical devices operating over long periods of time. The purpose of our work is to classify the condition of in vivo Bjork-Shiley Convexo-Concave (BSCC) heart valves by processing acoustic measurements of heart valve sounds. The structural failures of interest for Bscc valves is called single leg separation (SLS). SLS can occur if the outlet strut cracks and separates from the main structure of the valve. We measure acoustic opening and closing sounds (waveforms) using high sensitivity contact microphones on the patient`s thorax. For our analysis, we focus our processing and classification efforts on the opening sounds because they yield direct information about outlet strut condition with minimal distortion caused by energy radiated from the valve disc.

  16. Cavitation behavior observed in three monoleaflet mechanical heart valves under accelerated testing conditions.

    PubMed

    Lo, Chi-Wen; Liu, Jia-Shing; Li, Chi-Pei; Lu, Po-Chien; Hwang, Ned H

    2008-01-01

    Accelerated testing provides a substantial amount of data on mechanical heart valve durability in a short period of time, but such conditions may not accurately reflect in vivo performance. Cavitation, which occurs during mechanical heart valve closure when local flow field pressure decreases below vapor pressure, is thought to play a role in valve damage under accelerated conditions. The underlying flow dynamics and mechanisms behind cavitation bubble formation are poorly understood. Under physiologic conditions, random perivalvular cavitation is difficult to capture. We applied accelerated testing at a pulse rate of 600 bpm and transvalvular pressure of 120 mm Hg, with synchronized videographs and high-frequency pressure measurements, to study cavitation of the Medtronic Hall Standard (MHS), Medtronic Hall D-16 (MHD), and Omni Carbon (OC) valves. Results showed cavitation bubbles between 340 and 360 micros after leaflet/housing impact of the MHS, MHD, and OC valves, intensified by significant leaflet rebound. Squeeze flow, Venturi, and water hammer effects each contributed to cavitation, depending on valve design.

  17. Risk factors for valve-related complications after mechanical heart valve replacement in 505 patients with long-term follow up.

    PubMed

    Bourguignon, Thierry; Bergöend, Eric; Mirza, Alain; Ayegnon, Grégoire; Neville, Paul; Aupart, Michel R; Marchand, Michel

    2011-11-01

    Currently, valve thrombosis, thromboembolic events and bleeding events account for 75% of all complications that occur after mechanical heart valve replacement. The study aim was to determine the main risk factors for valve-related complications in patients undergoing mechanical heart valve replacement. Data were available from the systematic follow up of patients who had received a CarboMedics bileaflet mechanical heart valve replacement at the authors' institution. Follow up examinations were conducted prospectively at two-year intervals, via questionnaires sent to the patients' general practitioners, or by telephone calls. Between January 1988 and December 2005, a total of 505 consecutive patients (300 males, 205 females; mean age 52 years; range: 5 to 77 years) underwent heart valve replacement using a CarboMedics mechanical prosthesis. Aortic valve replacement (AVR) was performed in 308 patients, mitral valve replacement (MVR) in 134 patients, and double-valve replacement (DVR) in 62 patients. The follow up was 95.4% complete; the mean follow up was 7.5 years, and the total follow up 3,718 patient-years. Thromboembolic and bleeding complications represented the leading cause of valve-related events (104/195), of valve-related mortality (15/25), and of the need for repeat surgery (9/16). Valve thrombosis occurred in 12 patients. Implantation in the mitral position was identified as a risk factor (HR = 15.07; CI: 8.41-23.07; p 0.0001). Thromboembolism occurred in 32 patients; the use of antiplatelet agents was found to be a protective factor (HR = 0.23; CI: 0.08-0.70; p = 0.01). Bleeding events occurred in 52 patients; risk factors for bleeding events included a history of thromboembolic or bleeding complications (HR = 2.70; CI: 1.33-5.26; p = 0.006) and an unstable International Normalized Ratio (INR) (HR = 2.86; CI: 1.01-8.08; p = 0.05). After mechanical heart valve replacement, the only risk factors for bleeding complications were an unstable INR and a

  18. Relationships between melanocytes, mechanical properties and extracellular matrix composition in mouse heart valves.

    PubMed

    Carneiro, Flavia; Kruithof, Boudewijn Pt; Balani, Kanthesh; Agarwal, Arvind; Gaussin, Vinciane; Kos, Lidia

    2015-01-01

    Heart valves are complex structures composed of organized layers of extracellular matrix, and interstitial and overlying endothelial cells. In this article, we present the specific localization of a population of melanocytes within the murine heart valves at ages important for their post-natal development. In all stages analyzed in our study, melanocytes were found in high numbers populating the atrial aspect of the tricuspid and mitral leaflets. The pulmonary valve did not present melanocytes. To characterize a putative role for the valve melanocytes, the dynamic nanomechanical properties of tricuspid leaftets containing large numbers or no melanocytes were measured. The stiffness coefficient of hyperpigmented leaflets was higher (11.5 GPa) than the ones from wild-type (7.5 GPa) and hypopigmented (5.5 GPa) leaflets. These results suggest that melanocytes may contribute to the mechanical properties of the heart valves. The arrangement of extracellular matrix molecules such as Collagen I and Versican B is responsible for the mechanical characteristics of the leaflets. Melanocytes were found to reside primarily in areas of Versican B expression. The patterns of expression of Collagen I and Versican B were not, however, disrupted in hyper or hypopigmented leaflets. Melanocytes may affect other extracellular matrix molecules to alter the valves' microenvironment.

  19. Oval housing for the St. Jude Medical bileaflet mechanical heart valve.

    PubMed

    Mohammadi, Hadi; Fradet, Guy

    2017-10-01

    The St. Jude Medical bileaflet mechanical heart valve was approved by the Food and Drug Administration in late 1970s. The basic idea for the design of the valve is simply two semicircular flat plates pivoting on hinges. The overall performance of St. Jude Medical valves such as blood flow being central, the leaflets opening completely, and the pressure drop across the valve being trivial is satisfactory. St. Jude Medical valves provide an improved hemodynamics compared to the other mechanical heart valve models; however, their non-physiological hemodynamics which may lead to red blood cells lysis and thrombogenicity still remains a major issue. In this study, we hypothesize that applying ovality to the housing might improve their hemodynamics significantly which is based on the fact that the native annulus is oval by nature. A quick but precise numerical model based on the finite strip method was developed by which the regurgitation flow volume and velocity of the proposed design were assessed in the closing phase. The results are satisfactory and an improved hemodynamics is observed. The proposed design can be considered for further numerical and experimental studies and shows promise and merits further development.

  20. Diagnosis and surgical strategy for sacral meningeal cysts with check-valve mechanism: technical note.

    PubMed

    Asamoto, Shunji; Fukui, Yasuyuki; Nishiyama, Makoto; Ishikawa, Masayuki; Fujita, Nobuyuki; Nakamura, Satoshi; Muto, Jun; Shiono, Yuta; Doi, Hiroshi; Kubota, Motoo; Ishii, Kazuhiko

    2013-02-01

    There is agreement that symptomatic sacral meningeal cysts with a check-valve mechanism and/or large cysts representing space-occupying lesions should be treated surgically. This study investigated factors indicating a need for surgical intervention and surgical techniques for sacral meningeal cysts with a check-valve mechanism. In ten patients presenting with sciatica and neurological deficits, myelography, computed tomography (CT) myelography, and magnetic resonance imaging (MR imaging) detected sacral meningeal cysts with a check-valve mechanism. One patient had two primary cysts. Ten cysts were type 2 and one cyst was type 1. Nine of the ten patients had not undergone previous surgery, while the remaining case involved recurrent cyst. For the seven patients with normal (i.e., not huge or recurrent) type 2 cysts and no previous surgery (eight cysts), suture after collapse of the cyst wall was performed. For the recurrent type 2 cyst, duraplasty and suture with collapse of the cyst wall were performed to eliminate the check-valve mechanism. For the remaining type 2 cyst, a primary root was sacrificed because of the huge size of the cyst. For the type 1 cyst, the neck of the cyst was ligated. In all cases, chief complaints disappeared immediately postoperatively and no deterioration of clinical symptoms has been seen after a mean follow-up of 27 months. The presence or absence of a check-valve mechanism is very important in determining the need for surgical intervention for sacral meningeal cysts.

  1. Tricuspid valve chordal rupture due to airbag injury and review of pathophysiological mechanisms.

    PubMed

    Thekkudan, Joyce; Luckraz, Heyman; Ng, Alex; Norell, Mike

    2012-09-01

    Blunt trauma to the chest is associated with significant morbidity and mortality. The latter is usually due to an aortic transection, whereas the former is related to myocardial contusion, cardiac valve injury, coronary artery disruption and intracardiac shunts due to the formation of septal defects. The main mechanisms causing these injuries are due to the sudden deceleration force and compression within the chest cavity. Moreover, there is also the sudden increase in intravascular pressure due to a mechanical compression effect and a hormonal adrenergic surge during the event. We report a case of a tricuspid valve injury caused by the deployment of the airbag during a high-speed impact car accident and the subsequent damage to the tricuspid valve chordal mechanism. The patient's management and the pathophysiological mechanisms involved in the injury are reviewed.

  2. Multi-scale mechanical characterization of scaffolds for heart valve tissue engineering.

    PubMed

    Argento, G; Simonet, M; Oomens, C W J; Baaijens, F P T

    2012-11-15

    Electrospinning is a promising technology to produce scaffolds for cardiovascular tissue engineering. Each electrospun scaffold is characterized by a complex micro-scale structure that is responsible for its macroscopic mechanical behavior. In this study, we focus on the development and the validation of a computational micro-scale model that takes into account the structural features of the electrospun material, and is suitable for studying the multi-scale scaffold mechanics. We show that the computational tool developed is able to describe and predict the mechanical behavior of electrospun scaffolds characterized by different microstructures. Moreover, we explore the global mechanical properties of valve-shaped scaffolds with different microstructural features, and compare the deformation of these scaffolds when submitted to diastolic pressures with a tissue engineered and a native valve. It is shown that a pronounced degree of anisotropy is necessary to reproduce the deformation patterns observed in the native heart valve. Copyright © 2012 Elsevier Ltd. All rights reserved.

  3. Development of an experimental test bench for the measurement of fluid dynamic behavior of mechanical heart valve

    NASA Astrophysics Data System (ADS)

    Castellini, Paolo; Pinotti, Marcos; Scalise, Lorenzo

    2001-06-01

    In this paper an experimental test bench for mechanical heart valve and the procedure for non-invasive optical measurement are reported. Fluidynamic behaviour of a bileafleat mechanical valve in steady state and pulsed flow conditions has been studied. Laser Doppler Anemometry (LDA) is used to access velocity and turbulence values at different distances before and after the mechanical valve. Data obtained can be related, according to the literature, to typical pathologies affecting patients who underwent surgical procedures to implant mechanical heart valves. In particular thrombosis and hemolysis can be related to high levels of shear stress affecting blood cells. Measurements of velocity, turbulence and shear stresses have been performed.

  4. Fibrocalcific aortic valve disease: Opportunity to understand disease mechanisms using mouse models

    PubMed Central

    Weiss, Robert M.; Miller, Jordan D.; Heistad, Donald D.

    2013-01-01

    Studies in vitro and in vivo continue to identify complex regulated mechanisms leading to overt fibrocalcific aortic valve disease (FCAVD). Assessment of the functional impact of those processes requires careful studies of models of FCAVD in vivo. Although the genetic basis for FCVAD is unknown for most patients with FCAVD, several disease-associated genes have been identified in humans and mice. Some gene products which regulate valve development in utero also protect against fibro-calcific disease during postnatal aging. Valve calcification can occur via processes that resemble bone formation. But valve calcification can also occur by non-osteogenic mechanisms, such as formation of calcific apoptotic nodules. Anti-calcific interventions might preferentially target either osteogenic or non-osteogenic calcification. Although FCAVD and atherosclerosis share several risk factors and mechanisms, there are fundamental differences between arteries and the aortic valve, with respect to disease mechanisms and responses to therapeutic interventions. Both innate and acquired immunity are likely to contribute to FCAVD. Angiogenesis is a feature of inflammation, but may also contribute independently to progression of FCAVD, possibly by actions of pericytes that are associated with new blood vessels. Several therapeutic interventions appear to be effective in attenuating development of FCAVD in mice. Therapies which are effective early in the course of FCAVD, however, are not necessarily effective in established disease. PMID:23833295

  5. Fibrocalcific aortic valve disease: opportunity to understand disease mechanisms using mouse models.

    PubMed

    Weiss, Robert M; Miller, Jordan D; Heistad, Donald D

    2013-07-05

    Studies in vitro and in vivo continue to identify complex-regulated mechanisms leading to overt fibrocalcific aortic valve disease (FCAVD). Assessment of the functional impact of those processes requires careful studies of models of FCAVD in vivo. Although the genetic basis for FCAVD is unknown for most patients with FCAVD, several disease-associated genes have been identified in humans and mice. Some gene products which regulate valve development in utero also protect against fibrocalcific disease during postnatal aging. Valve calcification can occur via processes that resemble bone formation. But valve calcification can also occur by nonosteogenic mechanisms, such as formation of calcific apoptotic nodules. Anticalcific interventions might preferentially target either osteogenic or nonosteogenic calcification. Although FCAVD and atherosclerosis share several risk factors and mechanisms, there are fundamental differences between arteries and the aortic valve, with respect to disease mechanisms and responses to therapeutic interventions. Both innate and acquired immunity are likely to contribute to FCAVD. Angiogenesis is a feature of inflammation, but may also contribute independently to progression of FCAVD, possibly by actions of pericytes that are associated with new blood vessels. Several therapeutic interventions seem to be effective in attenuating the development of FCAVD in mice. Therapies which are effective early in the course of FCAVD, however, are not necessarily effective in established disease.

  6. Peri-prosthetic humeral non-union: Where biology meets bio-mechanic. A case report.

    PubMed

    Emanuele, Ciurlia; Leonardo, Puddu; Gianfilippo, Caggiari; Matteo, Andreozzi; Doria, Carlo

    2017-08-05

    The worldwide incidence of traumatic fractures has been growing over the last years due to the progressive aging of the population. Today, the increase of arthroplasty procedures in orthopaedic surgery is related to a high rate of peri-prosthetic fractures. Healing of the fracture is a multifactorial metabolic process; if these factors are impaired, healing process could be interrupted resulting in non-union. We report our experience about a case of a humeral diaphysis non-union secondary to peri-prosthetic fracture (reverse shoulder arthroplasty) treated by conservative approach. We treated this patient using a multilevel approach, consisting of revision surgery and drug therapy. We assume that an aggressive revision surgery done with bone autograft implant and a bone healing therapy administering teriparatide off-label can reduce the convalescence in non-unions and can improve prognosis. Copyright © 2017. Published by Elsevier Ltd.

  7. Percutaneous Transcatheter One-Step Mechanical Aortic Disc Valve Prosthesis Implantation: A Preliminary Feasibility Study in Swine

    SciTech Connect

    Sochman, Jan Peregrin, Jan H.; Rocek, Miloslav; Timmermans, Hans A.; Pavcnik, Dusan; Roesch, Josef

    2006-02-15

    Purpose. To evaluate the feasibility of one-step implantation of a new type of stent-based mechanical aortic disc valve prosthesis (MADVP) above and across the native aortic valve and its short-term function in swine with both functional and dysfunctional native valves. Methods. The MADVP consisted of a folding disc valve made of silicone elastomer attached to either a nitinol Z-stent (Z model) or a nitinol cross-braided stent (SX model). Implantation of 10 MADVPs (6 Z and 4 SX models) was attempted in 10 swine: 4 (2 Z and 2 SX models) with a functional native valve and 6 (4 Z and 2 SX models) with aortic regurgitation induced either by intentional valve injury or by MADVP placement across the native valve. MADVP function was observed for up to 3 hr after implantation. Results. MADVP implantation was successful in 9 swine. One animal died of induced massive regurgitation prior to implantation. Four MADVPs implanted above functioning native valves exhibited good function. In 5 swine with regurgitation, MADVP implantation corrected the induced native valve dysfunction and the device's continuous good function was observed in 4 animals. One MADVP (SX model) placed across native valve gradually migrated into the left ventricle. Conclusion. The tested MADVP can be implanted above and across the native valve in a one-step procedure and can replace the function of the regurgitating native valve. Further technical development and testing are warranted, preferably with a manufactured MADVP.

  8. Percutaneous transcatheter one-step mechanical aortic disc valve prosthesis implantation: a preliminary feasibility study in swine.

    PubMed

    Sochman, Jan; Peregrin, Jan H; Rocek, Miloslav; Timmermans, Hans A; Pavcnik, Dusan; Rösch, Josef

    2006-01-01

    To evaluate the feasibility of one-step implantation of a new type of stent-based mechanical aortic disc valve prosthesis (MADVP) above and across the native aortic valve and its short-term function in swine with both functional and dysfunctional native valves. The MADVP consisted of a folding disc valve made of silicone elastomer attached to either a nitinol Z-stent (Z model) or a nitinol cross-braided stent (SX model). Implantation of 10 MADVPs (6 Z and 4 SX models) was attempted in 10 swine: 4 (2 Z and 2 SX models) with a functional native valve and 6 (4 Z and 2 SX models) with aortic regurgitation induced either by intentional valve injury or by MADVP placement across the native valve. MADVP function was observed for up to 3 hr after implantation. MADVP implantation was successful in 9 swine. One animal died of induced massive regurgitation prior to implantation. Four MADVPs implanted above functioning native valves exhibited good function. In 5 swine with regurgitation, MADVP implantation corrected the induced native valve dysfunction and the device's continuous good function was observed in 4 animals. One MADVP (SX model) placed across native valve gradually migrated into the left ventricle. The tested MADVP can be implanted above and across the native valve in a one-step procedure and can replace the function of the regurgitating native valve. Further technical development and testing are warranted, preferably with a manufactured MADVP.

  9. Acoustic and visual characteristics of cavitation induced by mechanical heart valves.

    PubMed

    Sohn, Kwanghyun; Manning, Keefe B; Fontaine, Arnold A; Tarbell, John M; Deutsch, Steven

    2005-07-01

    A sudden pressure drop and recovery can induce cavitation in liquids. Mechanical heart valves (MHVs) generate such a pressure drop at closure, and cavitation generation around MHVs has been demonstrated many times. Cavitation is suspected as being a cause of blood and valve material damage. In this in-vitro experiment, visual images and acoustic signals associated with MHV cavitation were studied to reveal cavitation characteristics. Björk-Shiley Convex-Concave valves, one with a pyrolytic carbon occluder and one with a Delrin occluder, were installed in a single-shot valve chamber. Cavitation intensity was controlled by load (dP/dt) and air content of water. The acoustic signal was measured using a hydrophone and visual images recorded with a high-speed digital camera system. Cavitation images showed that 10 ppm water rarely developed cavitation, unlike the 16 ppm water. A distinct peak pressure was observed at cavitation collapse that was a good indicator of MHV cavitation intensity. The average of the peak pressures revealed that cavitation intensity increased faster with increasing load for the 16 ppm water. The use of the peak pressure may be the preferred method for correlating cavitation intensity in structures for which the separation of valve closure noise and cavitation signal is difficult, as for the valves studied here.

  10. Exhaled flow monitoring can detect bronchial flap-valve obstruction in a mechanical lung model.

    PubMed

    Breen, P H; Serina, E R; Barker, S J

    1995-08-01

    Flap-valve obstruction to expiratory flow (V) in a major bronchus can result from inspissated secretions, blood, or foreign body. During inhalation, increasing airway caliber preserves inspired V past the obstruction; during exhalation, decreasing airway diameter causes airflow obstruction and even frank gas trapping. We reasoned that the resultant sequential, biphasic exhalation of the lungs would be best detected by measuring exhaled V versus time. Accordingly, we designed an airway obstruction element in a mechanical lung model to examine flap-valve bronchial obstruction. A mechanical lung simulator was ventilated with a pressure-limited flow generator, where f = 10/min, tidal volume = 850 mL, and respiratory compliance = 40 mL/cm H2O. Airway V (pneumotachometer) and pressure (P) were digitally sampled for 1 min. Then, the circumference of the diaphragm in a respiratory one-way valve was trimmed to generate unidirectional resistance to expiratory V. Measurement sequences were repeated after this flap-valve was interposed in the right "main-stem bronchus." Integration of airway V versus time generated changes in lung volume. During flap-valve obstruction of the right bronchus, the V-time plot revealed preservation of peak expired flow from the normal lung, followed by retarded and decreased flow from the obstructed right lung. Gas trapping of the obstructed lung occurred during conditions of decreased expiratory time and increased expiratory resistance. Airway P could not differentiate between bronchial and tracheal flap-valve obstruction because P decreased abruptly in both conditions. The flow-volume loop displayed less distinctive changes than the flow-time plot, in part because the flow-volume loop was data (flow) plotted against its time integral (volume), with loss of temporal data. In this mechanical lung model, we conclude that bronchial flap-valve obstruction was best detected by the flow-time plot, which could measure the sequential emptying of the

  11. Dissection of the atrial wall after mitral valve replacement.

    PubMed Central

    Lukács, L; Kassai, I; Lengyel, M

    1996-01-01

    We describe an unusual sequela of mitral valve replacement in a 50-year-old woman who had undergone a closed mitral commissurotomy in 1975. She was admitted to our hospital because of mitral restenosis in November 1993, at which time her mitral valve was replaced with a mechanical prosthesis. On the 8th postoperative day, the patient developed symptoms of heart failure; transesophageal echocardiography revealed dissection and rupture of the left atrial wall. At prompt reoperation, we found an interlayer dissection and rupture of the atrial wall into the left atrium. We repaired the ruptured atrial wall with a prosthetic patch. The postoperative course was uneventful, and postoperative transesophageal echocardiography showed normal prosthetic valve function and no dissection. Images PMID:8680278

  12. Valve-in-Valve Replacement Using a Sutureless Aortic Valve

    PubMed Central

    Dohmen, Pascal M.; Lehmkuhl, Lukas; Borger, Michael A.; Misfeld, Martin; Mohr, Friedrich W.

    2016-01-01

    Patient: Female, 61 Final Diagnosis: Tissue degeneration Symptoms: Dyspnea Medication: — Clinical Procedure: Redo valve replacement Specialty: Surgery Objective: Rare disease Background: We present a unique case of a 61-year-old female patient with homograft deterioration after redo surgery for prosthetic valve endocarditis with root abscess. Case Report: The first operation was performed for type A dissection with root, arch, and elephant trunk replacement of the thoracic aorta. The present re-redo surgery was performed as valve-in-valve with a sutureless aortic biopros-thesis. The postoperative course was uneventful and the patient was discharged on day 6. Conclusions: The current case report demonstrates that sutureless bioprostheses are an attractive option for surgical valve-in-valve procedures, which can reduce morbidity and mortality. PMID:27694795

  13. Valve selection in aortic valve endocarditis

    PubMed Central

    Zubrytska, Yana

    2016-01-01

    Aortic prosthetic valve endocarditis (PVE) is a potentially life-threatening disease. Mortality and incidence of infective endocarditis have been reduced in the past 30 years. Medical treatment of aortic PVE may be successful in patients who have a prompt response after antibiotic treatment and who do not have prosthetic dysfunction. In advanced stages, antibiotic therapy alone is insufficient to control the disease, and surgical intervention is necessary. Surgical treatment may be lifesaving, but it is still associated with considerable morbidity and mortality. The aim of surgery is to perform a radical excision of all infected and necrotic tissue, reconstruction of the left ventricle outflow tract, and replacement of the aortic valve. There is no unanimous consensus on which is the optimal prosthesis to implant in this context, and several surgical techniques have been suggested. We aim to analyze the efficacy of the surgical treatment and discuss the issue of valve selection in patients with aortic valve endocarditis. PMID:27785132

  14. Characteristics of mechanical heart valve cavitation in a pneumatic ventricular assist device.

    PubMed

    Lee, Hwansung; Taenaka, Yoshiyuki

    2008-06-01

    In previous studies, we investigated the mechanism of mechanical heart valve (MHV) cavitation and cavitation intensity with a nonsynchronized experiment system. Our group is currently developing a pneumatic ventricular assist device (PVAD), and in this study we investigated MHV cavitation intensity in the PVAD using a synchronized analysis of the cavitation images and the acoustic signal of cavitation bubbles. A 23-mm Medtronic Hall valve with an opening angle of 70 degrees was mounted in the mitral position of the PVAD after removing the sewing ring. A function generator provided a square signal, which used the trigger signal of the electrocardiogram R wave (ECG-R) mode of the control-drive console for circulatory support. This square signal was delayed by a delay circuit and was then used as the trigger signal for a pressure sensor and a high-speed video camera. The data were stored using a digital oscilloscope at a 1-MHz sampling rate, and then the pressure signal was band-pass filtered between 35 and 200 kHz using a digital filter. The band-pass filtered root mean squared (RMS) pressure and cavitation cycle duration were used as an index of cavitation intensity. The cavitation bubbles were concentrated at the valve stop, and the cavitation cycle duration and RMS pressure increased as the heart rate and driving pressure increased. At the low valve-closing velocity, bubble cavitation was observed near the valve stop. However, at the fast valve-closing velocity, cloud cavitation was observed. A high-frequency signal wave was generated when the bubbles collapsed. The cavitation cycle duration and RMS pressure increased as the valve-closing velocity increased linearly.

  15. Mechanical characteristics of stability-bleed valves for a supersonic inlet. [for the YF-12 aircraft

    NASA Technical Reports Server (NTRS)

    Neiner, G. H.; Dustin, M. O.; Cole, G. L.

    1977-01-01

    Mechanical characteristics of a set of direct-operated relief valves used in a throat-bypass stability-bleed system designed for the YF-12 aircraft inlet are described. A comparison of data taken before and after the windtunnel tests (at room temperature) showed that both the effective spring rate and the piston friction had decreased during the wind tunnel tests. In neither the effective spring rate nor the piston friction was the magnitude of change great enough to cause significant impairment of overall system effectiveness. No major valve mechanical problems were encountered in any of the tests. During high temperature bench tests, piston frictional drag increased. The friction returned to its initial room temperature value when the stability-bleed valve was disassembled and reassembled. The problem might be solved by using a different material for the piston sleeve bearing and the piston rings.

  16. The Best Anticoagulation Therapy in Multiple-Trauma Patients with Mechanical Heart Valves: Evaluation of Latest Guidelines and Studies.

    PubMed

    Moeinipour, Aliasghar; Zarifian, Ahmadreza; Sheikh Andalibi, Mohammad Sobhan; Shamloo, Alireza Sepehri; Ahmadabadi, Ali; Amouzeshi, Ahmad; Hoseinikhah, Hamid

    2015-12-22

    It is common practice for patients with prosthetic cardiac devices, especially heart valve prosthesis, arterial stents, defibrillators, and pacemaker devices, to use anticoagulation treatment. When these patients suffer from multiple trauma after motor vehicle accidents, the best medical management for this challenging position is mandatory. This strategy should include a rapid diagnosis of all possible multiple organ injuries, with special attention to anticoagulation therapy so as to minimize the risk of thromboembolism complication in prosthetic devices. In this review, we describe the best medical management for patients with multiple trauma who use anticoagulants after heart valve replacement. We searched electronic databases PubMed/Medline, Scopus, Embase, and Google Scholar using the following terms: anticoagulant, warfarin, heparin, and multiple trauma. Also, similar studies suggested by the databases were included. Non-English articles were excluded from the review. For patients who use anticoagulation therapy, teamwork between cardiac surgeons, general surgeons, anesthesiologists, and cardiologists is essential. For optimal medical management, multiple consults between members of this team is mandatory for rapid diagnosis of all possible damaged organs, with special attention to the central nervous system, chest, and abdominal traumas. With this strategy, it is important to take note of anticoagulation drugs to minimize the risk of thromboembolism complications in cardiac devices. The best anticoagulant agents for emergency operations in patients with multiple trauma who are using an anticoagulant after heart valve replacement are fresh frozen plasma (FFP) and prothrombin complex concentrates (PCC).

  17. Increased catheter-related bloodstream infection rates after the introduction of a new mechanical valve intravenous access port.

    PubMed

    Maragakis, Lisa L; Bradley, Karen L; Song, Xiaoyan; Beers, Claire; Miller, Marlene R; Cosgrove, Sara E; Perl, Trish M

    2006-01-01

    The technology of intravenous catheter access ports has evolved from open ports covered by removable caps to more-sophisticated, closed versions containing mechanical valves. We report a significant increase in catheter-related bloodstream infections after the introduction of a new needle-free positive-pressure mechanical valve intravenous access port at our institution.

  18. Recurrent stuck mitral valve: eosinophilia an unusual pathology.

    PubMed

    Awasthy, Neeraj; Bhat, Yasser; Radhakrishnan, S; Sharma, Rajesh

    2015-03-01

    Eosinophilia is a very unusual and rare cause of thrombosis of prosthetic mitral valve. We report a 10-year-old male child of recurrent stuck prosthetic mitral valve. The child underwent mitral valve replacement for severe mitral regurgitation secondary to Rheumatic heart disease. He had recurrent prosthetic mitral valve thrombosis, despite desired INR levels. There was associated eosinophilia. The child was treated on the lines of tropical eosinophilia with oral prednisolone and diethylcarbamazine, the eosinophil count dropped significantly with no subsequent episode of stuck mitral valve. We discuss the management of recurrent stuck mitral valve and also eosinophilia as a causative factor for the same.

  19. Can the Flutter Valve improve respiratory mechanics and sputum production in mechanically ventilated patients? A randomized crossover trial.

    PubMed

    Chicayban, Luciano M; Zin, Walter A; Guimarães, Fernando S

    2011-01-01

    The Flutter Valve (Varioraw SARL, Scandipharm Inc, Birmingham, AL) has proven efficacy in hypersecretive spontaneously ventilated patients. This study was designed to evaluate whether an airway clearance protocol using the Flutter Valve can affect the therapeutic and physiologic outcomes in mechanically ventilated patients with pulmonary infection. In a randomized crossover study, sputum production, respiratory mechanics, hemodynamics, and gas exchange were evaluated from 20 mechanically ventilated patients submitted to 2 interventions. FLUTTER intervention consisted of connecting the Flutter Valve to the exhalation port of the mechanical ventilator. Control intervention (CTRL) was normal ventilation in pressure controlled mode. Compared with CTRL, FLUTTER improved sputum production (P < .001), respiratory system static compliance (P = .02), peak expiratory flow (P = .048), expiratory flow at 75% of tidal volume (P = .005), and arterial PO(2)-to-inspired oxygen concentration ratio (P < .001). Respiratory resistance, heart rate, and mean arterial pressure remained unaltered during the interventions (P > .05). The Flutter Valve improves lung secretion removal, mucus production, respiratory mechanics, and arterial oxygenation in mechanically ventilated patients with respiratory infection, without causing clinically relevant hemodynamic repercussions. Copyright © 2011 Elsevier Inc. All rights reserved.

  20. Automatic shutoff valve

    NASA Technical Reports Server (NTRS)

    Hawkins, S. F.; Overbey, C. W.

    1980-01-01

    Cellulose-sponge disk absorbs incoming water and expands with enough force to shut valve. When water recedes, valve opens by squeezing sponge dry to its original size. This direct mechanical action is considered more reliable than solenoid valve.

  1. Automatic shutoff valve

    NASA Technical Reports Server (NTRS)

    Hawkins, S. F.; Overbey, C. W.

    1980-01-01

    Cellulose-sponge disk absorbs incoming water and expands with enough force to shut valve. When water recedes, valve opens by squeezing sponge dry to its original size. This direct mechanical action is considered more reliable than solenoid valve.

  2. Mechanics of mitral valve edge-to-edge-repair and MitraClip procedure.

    PubMed

    Bhattacharya, Shamik; He, Zhaoming

    2015-01-01

    The edge-to-edge repair (ETER) technique has been used as a stand-alone procedure, or as a secondary procedure with ring annuloplasty for degenerative, functional mitral regurgitation, or for mitral regurgitation of other kinds of valvular etiologies. The percutaneous MitraClip technique based on ETER has been used in patients who are inoperable or at high surgical risk. However, adverse events such as residual mitral regurgitation, and clip detachment or fracture indicate that the mechanics underlying these procedures is not well understood. Therefore, current studies on mitral valve functionality and mechanics related to the ETER and MitraClip procedures are reviewed to improve the efficacy and safety of both procedures. Extensive in vivo, in vitro, and in silico studies related to ETER and MitraClip procedures along with MitraClip clinical trial results are presented and discussed herein. The ETER suture force and the mitral valve tissue mechanics and hemodynamics of each procedure are discussed. A quantitative understanding of the interplay of mitral valve components and as to biological response to the procedures remains challenging. Based on mitral valve mechanics, ETER or MitraClip therapy can be optimized to enhance repair efficacy and durability.

  3. The Work by Giulio Ceradini in Explaining the Mechanism of Semilunar Cardiac Valve Function

    ERIC Educational Resources Information Center

    Troiani, Diana; Manni, Ermanno

    2011-01-01

    Using an excised pig heart preparation with tubes, a manometer, and a visualizing apparatus, Giulio Ceradini, an Italian physiologist working in the years of 1871-1872 in Carl Ludwig's famous laboratory in Leipzig, Germany, illustrated the mechanism of closure of the semilunar valves. He was the first to conceive that the closure of the heart…

  4. Euler force actuation mechanism for siphon valving in compact disk-like microfluidic chips.

    PubMed

    Deng, Yongbo; Fan, Jianhua; Zhou, Song; Zhou, Teng; Wu, Junfeng; Li, Yin; Liu, Zhenyu; Xuan, Ming; Wu, Yihui

    2014-03-01

    Based on the Euler force induced by the acceleration of compact disk (CD)-like microfluidic chip, this paper presents a novel actuation mechanism for siphon valving. At the preliminary stage of acceleration, the Euler force in the tangential direction of CD-like chip takes the primary place compared with the centrifugal force to function as the actuation of the flow, which fills the siphon and actuates the siphon valving. The Euler force actuation mechanism is demonstrated by the numerical solution of the phase-field based mathematical model for the flow in siphon valve. In addition, experimental validation is implemented in the polymethylmethacrylate-based CD-like microfluidic chip manufactured using CO2 laser engraving technique. To prove the application of the proposed Euler force actuation mechanism, whole blood separation and plasma extraction has been conducted using the Euler force actuated siphon valving. The newly introduced actuation mechanism overcomes the dependence on hydrophilic capillary filling of siphon by avoiding external manipulation or surface treatments of polymeric material. The sacrifice for highly integrated processing in pneumatic pumping technique is also prevented by excluding the volume-occupied compressed air chamber.

  5. The Work by Giulio Ceradini in Explaining the Mechanism of Semilunar Cardiac Valve Function

    ERIC Educational Resources Information Center

    Troiani, Diana; Manni, Ermanno

    2011-01-01

    Using an excised pig heart preparation with tubes, a manometer, and a visualizing apparatus, Giulio Ceradini, an Italian physiologist working in the years of 1871-1872 in Carl Ludwig's famous laboratory in Leipzig, Germany, illustrated the mechanism of closure of the semilunar valves. He was the first to conceive that the closure of the heart…

  6. Prosthetic Engineering

    MedlinePlus

    ... torque adapter in the pylons of transtibial amputees. Energy Storage & Release Many ambulatory lower limb amputees exhibit ... Future Directions Current Project Summaries Development of Controlled Energy Storage and Release Prosthetic Foot Development of Inverting- ...

  7. Prosthetic Feet

    MedlinePlus

    ... lightweight materials such as plastic, metal alloys and carbon-fiber composites. Prosthetic feet can be basic (unmoving), ... feet: store and release energy during the walking cycle give a sense of push-off, a more ...

  8. Ultrananocrystalline Diamond Integration with Pyrolytic Carbon Components of Mechanical Heart Valves

    PubMed Central

    Zeng, Hongjun; Yin, Wei; Catausan, Grace; Moldovan, Nicolaie; Carlisle, John

    2015-01-01

    In this report, an idea of integrating ultrananocrystalline diamond (UNCD) with pyrolytic carbon (PyC) –based mechanical heart valves, has been demonstrated. The report addresses the strategies to avoid graphitization and film delamination during the diamond coating. Raman and scratch tests showed that a UNCD film with high purity could adhere to the PyC substrate strongly. A thrombin generation study demonstrated an excellent biocompatibility of UNCD towards fresh human platelets. These results suggest that UNCD could be a good candidate of surface material for next generation heart valves and other implantable devices. PMID:26705376

  9. Myocardial remodeling with aortic stenosis and after aortic valve replacement: mechanisms and future prognostic implications.

    PubMed

    Yarbrough, William M; Mukherjee, Rupak; Ikonomidis, John S; Zile, Michael R; Spinale, Francis G

    2012-03-01

    Aortic valve stenosis is a common cause of left ventricular pressure overload, a pathologic process that elicits myocyte hypertrophy and alterations in extracellular matrix composition, both of which contribute to increases in left ventricular stiffness. However, clinical and animal studies suggest that increased myocardial extracellular matrix fibrillar collagen content occurs later in the time course of left ventricular pressure overload at a time coincident with severe abnormalities in diastolic function followed by the development of symptomatic heart failure. Aortic valve replacement remains the most effective treatment for elimination of chronic pressure overload secondary to aortic stenosis but has traditionally been recommended only after the onset of clinical symptoms. Long-term follow-up of patients with symptomatic aortic stenosis after aortic valve replacement suggests that valve replacement may not result in complete reversal of the maladaptive changes that occur within the myocardial extracellular matrix secondary to the pressure overload state. To the contrary, residual left ventricular extracellular matrix abnormalities such as these are likely responsible for persistent abnormalities in diastolic function and increased morbidity and mortality after aortic valve replacement. Defining the mechanisms and pathways responsible for regulating the myocardial extracellular matrix during the natural history of aortic stenosis may provide a means by which to detect crucial structural milestones and thereby permit more precise identification of the development of maladaptive left ventricular remodeling. Published by Mosby, Inc.

  10. Hemodynamic Performance and Thrombogenic Properties of a Superhydrophobic Bileaflet Mechanical Heart Valve.

    PubMed

    Bark, David L; Vahabi, Hamed; Bui, Hieu; Movafaghi, Sanli; Moore, Brandon; Kota, Arun K; Popat, Ketul; Dasi, Lakshmi P

    2017-02-01

    In this study, we explore how blood-material interactions and hemodynamics are impacted by rendering a clinical quality 25 mm St. Jude Medical Bileaflet mechanical heart valve (BMHV) superhydrophobic (SH) with the aim of reducing thrombo-embolic complications associated with BMHVs. Basic cell adhesion is evaluated to assess blood-material interactions, while hemodynamic performance is analyzed with and without the SH coating. Results show that a SH coating with a receding contact angle (CA) of 160° strikingly eliminates platelet and leukocyte adhesion to the surface. Alternatively, many platelets attach to and activate on pyrolytic carbon (receding CA = 47), the base material for BMHVs. We further show that the performance index increases by 2.5% for coated valve relative to an uncoated valve, with a maximum possible improved performance of 5%. Both valves exhibit instantaneous shear stress below 10 N/m(2) and Reynolds Shear Stress below 100 N/m(2). Therefore, a SH BMHV has the potential to relax the requirement for antiplatelet and anticoagulant drug regimens typically required for patients receiving MHVs by minimizing blood-material interactions, while having a minimal impact on hemodynamics. We show for the first time that SH-coated surfaces may be a promising direction to minimize thrombotic complications in complex devices such as heart valves.

  11. Comparison of the hemodynamic and thrombogenic performance of two bileaflet mechanical heart valves using a CFD/FSI model.

    PubMed

    Dumont, Kris; Vierendeels, Jan; Kaminsky, Rado; van Nooten, Guido; Verdonck, Pascal; Bluestein, Danny

    2007-08-01

    The hemodynamic and the thrombogenic performance of two commercially available bileaflet mechanical heart valves (MHVs)--the ATS Open Pivot Valve (ATS) and the St. Jude Regent Valve (SJM), was compared using a state of the art computational fluid dynamics-fluid structure interaction (CFD-FSI) methodology. A transient simulation of the ATS and SJM valves was conducted in a three-dimensional model geometry of a straight conduit with sudden expansion distal the valves, including the valve housing and detailed hinge geometry. An aortic flow waveform (60 beats/min, cardiac output 4 l/min) was applied at the inlet. The FSI formulation utilized a fully implicit coupling procedure using a separate solver for the fluid problem (FLUENT) and for the structural problem. Valve leaflet excursion and pressure differences were calculated, as well as shear stress on the leaflets and accumulated shear stress on particles released during both forward and backward flow phases through the open and closed valve, respectively. In contrast to the SJM, the ATS valve opened to less than maximal opening angle. Nevertheless, maximal and mean pressure gradients and velocity patterns through the valve orifices were comparable. Platelet stress accumulation during forward flow indicated that no platelets experienced a stress accumulation higher than 35 dyne x s/cm2, the threshold for platelet activation (Hellums criterion). However, during the regurgitation flow phase, 0.81% of the platelets in the SJM valve experienced a stress accumulation higher than 35 dyne x s/cm2, compared with 0.63% for the ATS valve. The numerical results indicate that the designs of the ATS and SJM valves, which differ mostly in their hinge mechanism, lead to different potential for platelet activation, especially during the regurgitation phase. This numerical methodology can be used to assess the effects of design parameters on the flow induced thrombogenic potential of blood recirculating devices.

  12. Mitral disc-valve variance

    PubMed Central

    Berroya, Renato B.; Escano, Fernando B.

    1972-01-01

    This report deals with a rare complication of disc-valve prosthesis in the mitral area. A significant disc poppet and struts destruction of mitral Beall valve prostheses occurred 20 and 17 months after implantation. The resulting valve incompetence in the first case contributed to the death of the patient. The durability of Teflon prosthetic valves appears to be in question and this type of valve probably will be unacceptable if there is an increasing number of disc-valve variance in the future. Images PMID:5017573

  13. Calcific Aortic Valve Stenosis: Methods, Models, and Mechanisms

    PubMed Central

    Miller, Jordan D.; Weiss, Robert M.; Heistad, Donald D.

    2011-01-01

    Calcific aortic valve stenosis (CAVS) is a major health problem facing aging societies. The identification of osteoblast-like and osteoclast-like cells in human tissue has led to a major paradigm shift in the field. CAVS was thought to be a passive, degenerative process, whereas now the progression of calcification in CAVS is considered to be actively regulated. Mechanistic studies examining the contributions of true ectopic osteogenesis, non-osseous calcification, and ectopic osteoblast-like cells (that appear to function differently from skeletal osteoblasts) to valvular dysfunction have been facilitated by the development of mouse models of CAVS. Recent studies also suggest that valvular fibrosis, as well as calcification, may play an important role in restricting cusp movement, and CAVS may be more appropriately viewed as a fibrocalcific disease. High resolution echocardiography and magnetic resonance imaging have emerged as useful tools for testing the efficacy of pharmacological and genetic interventions in vivo. Key studies in humans and animals are reviewed that have shaped current paradigms in the field of CAVS, and suggest promising future areas for research. PMID:21617136

  14. Two-dimensional dynamic simulation of platelet activation during mechanical heart valve closure.

    PubMed

    Krishnan, S; Udaykumar, H S; Marshall, J S; Chandran, K B

    2006-10-01

    A major drawback in the operation of mechanical heart valve prostheses is thrombus formation in the near valve region. Detailed flow analysis in this region during the valve closure phase is of interest in understanding the relationship between shear stress and platelet activation. A fixed-grid Cartesian mesh flow solver is used to simulate the blood flow through a bi-leaflet mechanical valve employing a two-dimensional geometry of the leaflet with a pivot point representing the hinge region. A local mesh refinement algorithm allows efficient and fast flow computations with mesh adaptation based on the gradients of the flow field in the leaflet-housing gap at the instant of valve closure. Leaflet motion is calculated dynamically based on the fluid forces acting on it employing a fluid-structure interaction algorithm. Platelets are modeled and tracked as point particles by a Lagrangian particle tracking method which incorporates the hemodynamic forces on the particles. A platelet activation model is included to predict regions which are prone to platelet activation. Closure time of the leaflet is validated against experimental studies. Results show that the orientation of the jet flow through the gap between the housing and the leaflet causes the boundary layer from the valve housing to be drawn in by the shear layer separating from the leaflet. The interaction between the separating shear layers is seen to cause a region of intensely rotating flow with high shear stress and high residence time of particles leading to high likelihood of platelet activation in that region.

  15. Rocker arm spring for a valve actuating mechanism of an internal combustion engine

    SciTech Connect

    Nono, Y.; Sasaki, Y.

    1986-07-08

    A rocker arm spring is described for use in a valve actuating mechanism of an internal combustion engine having a cylinder head, an overhead camshaft mounted on the cylinder head and a valve having a valve stem extending through the cylinder head, the valve actuating mechanism including a rocker arm having a first end and a second end, a universal pivot swingably supporting the first end of the rocker arm on the cylinder head of the engine. The second end of the rocker arm is in contact with the valve stem, and a cam on the overhead camshaft engaging from above a portion of the rocker arm intermediate the first and second ends to cause the rocker arm to swing about the universal pivot, the universal pivot including a support socket mounted on the cylinder head. The support socket has a part-spherical concave bearing surface and a circumferential groove with a fixed predetermined groove width, and a pivotable shaft mounted on the first end of the rocker arm, the pivotable shaft having a part-spherical convex lower end mating with and received in the concave bearing surface, and the rocker arm spring being in the form of a leaf spring made of an elongated strip of resilient material thinner than the predetermined groove width, the strip being bent to a substantially U-shape having an upper arm and a lower arm, the lower arm having a forked end engageable within the circumferential groove in the support socket. The upper arm is engageable with the rocker arm for urging the lower end of the pivotable shaft into contact with the bearing surface of the support socket as well as for biasing the second end of the rocker arm into contact with the valve stem.

  16. Risk of breast cancer among patients with bioprosthetic or mechanical valve replacement: a population-based study in Sweden.

    PubMed

    Ji, Jianguang; Zöller, Bengt; Giaccia, Amato; Haile, Robert; Sundquist, Jan; Sundquist, Kristina

    2015-11-01

    The association between breast cancer and warfarin is inconclusive as most previous studies examined their association using patients with thromboembolism, whereas thromboembolism itself is a risk factor for cancer. We explored this issue using patients received mechanical heart valves replacement as a proxy for warfarin exposure as these patients need a lifelong warfarin treatment, and compared them with patients received bioprosthesis valves replacement (short-term warfarin treatment) in Sweden between 1987 and 2010. Patients who were operated on for valve replacement were identified from the Swedish Hospital Discharge Registry and linked to the Swedish Cancer Registry to examine the hazard ratios of subsequent breast cancer. A total of 12,242 women were operated on for valve replacement (5481 with mechanical valve and 6401 with bioprosthetic valve). For the entire cohort, the HR of breast cancer was 1.49 (95 % CI 1.09-2.02) among patients with mechanical valve replacement compared to those with bioprosthetic valve replacement. After controlling for a number of confounding factors using propensity score weighting, the HR was 1.69 (95 % CI 1.15-2.47). Our study found that patients with mechanical valve replacement have an increased risk of breast cancer compared to those with bioprosthetic valve replacement. If confirmed, this increased risk should be considered when recommending breast cancer screening for women with mechanical valve replacement. Long-term use of warfarin may explain the observed increase. If so, patients who have used warfarin long-term for other reasons should be studied for a possible increased risk of breast cancer.

  17. Quality of Life and Anxiety in Younger Patients after Biological versus Mechanical Aortic Valve Replacement.

    PubMed

    Kottmaier, Marc; Hettich, Ina; Deutsch, Marcus-André; Badiu, Catalin; Krane, Markus; Lange, Ruediger; Bleiziffer, Sabine

    2017-04-01

    Background Since biological valve recipients are likely to need a redo procedure in the future for valve deterioration, we hypothesized patients might be more fearful about the progression of their disease than patients after aortic valve replacement (AVR) with a mechanical valve. The aim of this study is to compare the quality of life (QOL) and anxiety in patients who have undergone biological versus mechanical AVR. Method A total of 56 patients after mechanical AVR (mean age: 64.4 ± 8.17 years) and 66 patients after biological AVR (mean age: 64.8 ± 11.05 years) received three questionnaires 5.66 (± 2.68) years after surgery, including: The short form-36 (SF-36) to assess QOL, the fear of progression questionnaire (FOP), and the cardiac anxiety questionnaire (CAQ) to assess general anxiety, anxiety related to cardiac symptoms, and anxiety about progression of heart disease and valve and anticoagulation-specific questions. Results No significant differences were found for all categories of the SF-36. The FOP showed significantly favorable values for the biological AVR group. The CAQ showed a tendency in the subscale "avoidance" (i.e., avoidance of pulse increase) and "attention" towards more favorable values for the biological AVR group. Conclusions In contrast to our hypothesis, patients after mechanical AVR show significantly higher anxiety values for the FOP, and a tendency toward higher values for "avoidance" (i.e., avoidance of pulse increase). Partnership concerns, especially in terms of sexuality can be explained by factors that are recognizable for the partner, such as valve sound. These data provide evidence that factors that are continuously present after mechanical AVR, such as valve sound or anticoagulation might affect wellbeing stronger than the certainty of reoperation in the future after biological AVR. We conclude that implantation of a biological prosthesis can be justified in younger patients with regards to QOL. Georg Thieme

  18. One-year outcome following biological or mechanical valve replacement for infective endocarditis.

    PubMed

    Delahaye, F; Chu, V H; Altclas, J; Barsic, B; Delahaye, A; Freiberger, T; Gordon, D L; Hannan, M M; Hoen, B; Kanj, S S; Lejko-Zupanc, T; Mestres, C A; Pachirat, O; Pappas, P; Lamas, C; Selton-Suty, C; Tan, R; Tattevin, P; Wang, A

    2015-01-15

    Nearly half of patients require cardiac surgery during the acute phase of infective endocarditis (IE). We describe the characteristics of patients according to the type of valve replacement (mechanical or biological), and examine whether the type of prosthesis was associated with in-hospital and 1-year mortality. Among 5591 patients included in the International Collaboration on Endocarditis Prospective Cohort Study, 1467 patients with definite IE were operated on during the active phase and had a biological (37%) or mechanical (63%) valve replacement. Patients who received bioprostheses were older (62 vs 54years), more often had a history of cancer (9% vs 6%), and had moderate or severe renal disease (9% vs 4%); proportion of health care-associated IE was higher (26% vs 17%); intracardiac abscesses were more frequent (30% vs 23%). In-hospital and 1-year death rates were higher in the bioprosthesis group, 20.5% vs 14.0% (p=0.0009) and 25.3% vs 16.6% (p<.0001), respectively. In multivariable analysis, mechanical prostheses were less commonly implanted in older patients (odds ratio: 0.64 for every 10years), and in patients with a history of cancer (0.72), but were more commonly implanted in mitral position (1.60). Bioprosthesis was independently associated with 1-year mortality (hazard ratio: 1.298). Patients with IE who receive a biological valve replacement have significant differences in clinical characteristics compared to patients who receive a mechanical prosthesis. Biological valve replacement is independently associated with a higher in-hospital and 1-year mortality, a result which is possibly related to patient characteristics rather than valve dysfunction. Copyright © 2014 Elsevier Ireland Ltd. All rights reserved.

  19. Mechanical energy profiles of the combined ankle-foot system in normal gait: insights for prosthetic designs.

    PubMed

    Takahashi, Kota Z; Stanhope, Steven J

    2013-09-01

    Over the last half-century, the field of prosthetic engineering has continuously evolved with much attention being dedicated to restoring the mechanical energy properties of ankle joint musculatures during gait. However, the contributions of 'distal foot structures' (e.g., foot muscles, plantar soft tissue) have been overlooked. Therefore, the purpose of this study was to quantify the total mechanical energy profiles (e.g., power, work, and work-ratio) of the natural ankle-foot system (NAFS) by combining the contributions of the ankle joint and all distal foot structures during stance in level-ground steady state walking across various speeds (0.4, 0.6, 0.8 and 1.0 statures/s). The results from eleven healthy subjects walking barefoot indicated ankle joint and distal foot structures generally performed opposing roles: the ankle joint performed net positive work that systematically increased its energy generation with faster walking speeds, while the distal foot performed net negative work that systematically increased its energy absorption with faster walking speeds. Accounting for these simultaneous effects, the combined ankle-foot system exhibited increased work-ratios with faster walking. Most notably, the work-ratio was not significantly greater than 1.0 during the normal walking speed of 0.8 statures/s. Therefore, a prosthetic design that strategically exploits passive-dynamic properties (e.g., elastic energy storage and return) has the potential to replicate the mechanical energy profiles of the NAFS during level-ground steady-state walking. Copyright © 2013 Elsevier B.V. All rights reserved.

  20. Reflection photoelasticity: a new method for studies of clinical mechanics in prosthetic dentistry.

    PubMed

    Fernandes, Cláudio P; Glantz, Per Olof J; Svensson, Stig A; Bergmark, Anders

    2003-03-01

    This research was conducted to demonstrate the effectiveness of reflective photoelasticity as an in vivo technique for monitoring the strain/stress distribution in prosthetic devices during function. Seven subjects were selected for this study and divided into three groups according to the design of the prostheses. The buccal surfaces of the experimental prostheses were coated with a birefringent resin 2mm thick. Using a reflection polariscope, fringe patterns were documented on video tape during standardized in vivo loadings. Strain and stress levels (gamma(max) and tau(max)) were calculated from isochromatic fringe order determinations. The intra-observer variability in counting fringe orders and the accuracy level of reflective photoelasticity as compared to strain gauge results were also studied. The strain results of in vivo loading of the prostheses were analyzed with ANOVA and Scheffés tests. The intra-observer variability was analyzed with the Friedman nonparametric test. Comparisons of photoelastic data and strain gauges were tested with Pearson's correlation. Coated areas accessible to normally incident light, produced comprehensive maps of strain distribution. Significant differences were found in the in vivo gamma(max) values for the prostheses designs (p<0.05). The test for intra-observer variability showed that no significant differences occurred in counting fringe orders. Strain values obtained with reflective photoelasticity showed a high correlation r=0.98 and 0.99) with values obtained at the same areas using strain gauges. Reflective photoelasticity is a valid, reliable and accurate technique to be used for in vivo studies on the biomechanical behavior of prosthetic devices.

  1. Long-term survival with a stentless free-hand Batista pericardial aortic valve prosthesis: A case report

    PubMed Central

    Becerra, Valentina; Labbé, Javier; Cataldo, Anthony; Becerra, Eduardo

    2014-01-01

    INTRODUCTION Stented bovine pericardial prosthetic valves