BackgroundThe arrhythmogenic effects of hyperthermia have been highlighted in the Brugada Syndrome, but remain largely unexplored in other arrhythmic syndromes. The present study examines the effect of hyperthermia on transmural dispersion of action potential duration (TD-APD), early afterdepolarization (EAD) activity, and Torsade de Pointes (TdP) under ...

Accentuated right ventricular (RV) gradients in action potential duration (APD) have been implicated in the arrhythmogenicity observed in Brugada syndrome in studies assuming that ventricular effective refractory periods (VERPs) vary in concert with APDs. The present experiments use a genetically modified mouse model to explore spatial heterogeneities in VERP that in turn ...

... Sertindole does not increase transmural dispersion in the LV wedge 240 260 280 300 ... Control (C) LV wedge (n= 3) / BCL= 2000 msec d: p<0.05 vs. Control (C) 240 ...

Torsades de pointes (TdP) is a potentially lethal arrhythmia that develops as a consequence of amplification of electrical heterogeneities intrinsic to the ventricular myocardium. These heterogeneities exist because of differences in the time course of repolarization of the three predominant cell types that make up the ventricular myocardium, giving rise to transmural voltage ...

Surfactants are adjuvants that facilitate and accentuate the emulsifying, dispersing, spreading, wetting, or other surface modifying properties of liquids. Many pesticides require the addition of a surfactant to improve pesticide performance in spray solution. Soils are one of the direct recipients ...

Theoretical and experimental evidence suggests that the dissipation of high frequency pressure waves in blood vessels is caused primarily by the viscoelastic behavior of the vessel wall. In this theoretical analysis the vessels are considered as fluid-filled circular cylindrical shells whose walls have isotropic and homogeneous viscoelastic properties and are subjected to an initial axial stretch ...

Spatial dispersion of repolarization in the form of transmural, trans-septal and apico-basal dispersion of repolarization creates voltage gradients that inscribe the J wave and T wave of the ECG. Amplification of this spatial dispersion of repolarization (SDR) underlies the development of life-threatening ...

Heterogeneity of transmural ventricular repolarization in the heart has been linked to a variety of arrhythmic manifestations. Electrical heterogeneity in ventricular myocardium is due to ionic distinctions among the three principal cell types: Endocardial, M and Epicardial cells. A reduction in net repolarizing current generally leads to a preferential prolongation of the M ...

IntroductionThere remains an unmet need for safe and effective antiarrhythmic drugs, especially for the treatment of atrial fibrillation. Vanoxerine is a drug that is free of adverse cardiac events in normal volunteers, yet is a potent blocker of the hERG (hK_v11.1) cardiac potassium channel. Consequently we hypothesized that vanoxerine might also be a potent blocker of ...

AimsStudies of arrhythmogenesis during ischemia have focused primarily on reentrant mechanisms manifested on the epicardial surface. The goal of this study was to use a physiologically-accurate model of acute regional ischemia phase 1A to determine the contribution of ischaemia-induced transmural electrophysiological heterogeneities to arrhythmogenesis following left anterior ...

) and the other single-mode fiber (SMF), and one short-period (1 km) dispersion managed soliton (DMS) system amplitude jitter. We analyzed the behavior of the DMS system and showed that the reduced pulse broadening impact of nonlinearities compared to quasi-linear propagation. The sensitivity of the DMS system

Gap junctions are critical to maintaining synchronized impulse propagation and repolarization. Heterogeneous expression of the principal ventricular gap junction protein connexin43 (Cx43) is associated with action potential duration (APD) dispersion across the anterior ventricular wall. Little is known about Cx43 expression patterns and their disparate impact on regional ...

Gap junctions are critical to maintaining synchronized impulse propagation and repolarization. Heterogeneous expression of the principal ventricular gap junction protein connexin43 (Cx43) is associated with action potential duration (APD) dispersion across the anterior ventricular wall. Little is known about Cx43 expression patterns and their disparate impact on regional ...

Resynchronization therapy involving right ventricular endocardial and left ventricular epicardial pacing improves cardiac output, quality of life, and New York Heart Association functional class in patients with congestive heart failure. Although a great deal of attention has been directed at showing the mechanical benefits and in fine-tuning the biventricular pacing configuration and protocol, ...

It is well established that cardiac resynchronisation therapy (CRT) using biventricular pacing prolongs survival by its effects on pump failure. The rate of sudden cardiac death in patients undergoing CRT, however, remains high. Animal and human studies have shown that reversal of normal sequence of myocardial activation during epicardial pacing, as applied during CRT, increases the ...

INTRODUCTION:: Some studies have shown that the defibrillation threshold (DFT) differs between short-duration ventricular fibrillation (SDVF, <1min) and long-duration ventricular fibrillation (LDVF > 1 min). The goal of this study is to evaluate the effects of acute intravenous amiodarone on SDVF-DFT and LDVF-DFT, and its possible mechanism as well. METHODS:: Twelve open-chest dogs were ...

Antzelevitch C, Oliva A (Masonic Medical Research Laboratory, Utica, NY, USA). Amplification of spatial dispersion of repolarization underlies sudden cardiac death associated with catecholaminergic polymorphic VT, long QT, short QT, and Brugada syndromes. J Intern Med 2006; 259: 48-58.This review examines the hypothesis that amplification of spatial ...

Dofetilide is a class-III drug that inhibits the rapid component of the delayed potassium current ( I(Kr)). Experimental studies have shown that the different layers of ventricular muscle present differences in action potential duration (APD) and different responses to class III agents. It has been suggested that it contributes to APD heterogeneity in the ventricles. However, in vivo studies ...

Long-duration ventricular fibrillation (LDVF) in the globally ischemic heart is a common setting of cardiac arrest. Electrical heterogeneities during LDVF may affect outcomes of defibrillation and resuscitation. Previous studies in large mammalian hearts have investigated the role of Purkinje fibers and electrophysiological gradients between the endocardium (Endo) and epicardium (Epi). Much less ...

Torsade de pointes (TdP) is a life-threatening arrhythmia that develops as a consequence of a reduction in the repolarization reserve of cardiac cells leading to amplification of electrical heterogeneities in the ventricular myocardium as well as to the development of early after depolarization-induced triggered activity. Electrical heterogeneities within the ventricles are due to differences in ...

This review examines the role of spatial electrical heterogeneity within ventricular myocardium on the function of the heart in health and disease. The cellular basis for transmural dispersion of repolarization (TDR) is reviewed and the hypothesis that amplification of spatial dispersion of repolarization underlies the development of ...

1. QT interval prolongation is associated with a risk of life-threatening cardiac arrhythmias. We examined whether reversible adrenergic blockade of the heart obtained through thoracic epidural anaesthesia influences cardiac repolarisation and thus confers an antiarrhythmic effect. 2. Fifty-two males between 28 and 65 years of age were included in the study: 28 patients were scheduled for thoracic ...

... Title : Propranolol Accentuates the Cold Induced Fall in Skin Temperature and Elevation in Blood Pressure in 12 Normotensive Men: A Role for the ...

In this paper, treating the artery as a thick walled cylindrical shell made of an incompressible, elastic and isotropic material and the blood as an incompressible inviscid fluid, by taking the inertia of the wall into account, the propagation of harmonic waves in an initially stressed tube, filled with an inviscid fluid, is studied. Utilizing inner-pressure-inner-cross-sectional-area relation in ...

This lecture examines the hypothesis that amplification of spatial dispersion of repolarization in the form of transmural dispersion of repolarization (TDR) underlies the development of life?threatening ventricular arrhythmias associated with inherited ion channelopathies including the long QT, short QT and Brugada syndromes as well as ...

Data are presented on polymorphic genetic markers of 84 Welsh gypsies, members of an inbred population characterised by a high incidence of phenylketonuria and other recessively inherited diseases. Sixteen polymorphic loci were studied: the ABO blood group distribution was comparable to that of the surrounding population, the B gene frequency being 7-5%, a lower frequency than most earlier studies ...

Cardiovascular magnetic resonance (CMR) using contrast enhancement allows exact determination of the site and transmural extent of myocardial infarction (MI). We evaluated whether 12-lead electrocardiography can differentiate transmural from non-transmural MI or determine the site of MI by comparing the findings with those of ...

Many cardiac diseases cause transmural differences in myofiber function. With the Magnetic Resonance Imaging Tagging technique a grid of magnetic tags was attached to the heart. Using a model of cardiac mechanics the motion of these tags was analyzed to d...

Optical properties of the fluorocarbon (FC) films plasma deposited on Si substrates are evaluated in this work using multiple sample analysis (MSA)-based spectroscopic ellipsometry (SE) with representing the film optical constants by the Forouhi-Bloomer (FB) and Tauc-Lorentz (TL) optical dispersions. This SE analysis supported also with other film investigations results in a ...

This review analyzes recent data concerning the molecular determinants of repolarization time (RT) in normal and disease conditions. Considerations concerning the prognostic significance of RT were excluded. On a single normal cell, the duration of the action potential is the result of a balance between different ion currents. In vivo or on a multicellular preparation, the QT duration is modified ...

Ventricular myocardium in larger mammals has been shown to be comprised of three distinct cell types: epicardial, M, and endocardial. Epicardial and M cell action potentials differ from endocardial cells with respect to the morphology of phase 1. These cells possess a prominent I_to-mediated notch responsible for the �spike and dome� morphology of the epicardial and M ...

Despite the commonly accepted notion that action potential duration (APD) is distributed heterogeneously throughout the ventricles and that the associated dispersion of repolarization is mainly responsible for the shape of the T-Wave, its concordance and exact morphology are still not completely understood. This study evaluated the T-Waves for different, previously measured ...

BackgroundLQT1 subtype of long QT syndrome is characterized by defective I_Ks, which is intrinsically stronger in the epicardium than in the midmyocardial region. Electrocardiographic QT peak and QT end intervals may reflect complete repolarization of epicardium and midmyocardial region of the ventricular wall, respectively. Repolarization abnormalities in LQT1 carriers may ...

BACKGROUND Andersen-Tawil syndrome, a skeletal muscle syndrome associated with periodic paralysis and long QT intervals on the ECG, has been linked to defects in KCNJ2, the gene encoding for the inward rectifier potassium channel (I_K1.)OBJECTIVES The purpose of this study was to examine the cellular mechanisms underlying the ECG and arrhythmic manifestations of ...

... Departments of 2Cardiothoracal Surgery and 3Radiology, Academic Hospital Maastricht, Maastricht ... grid of magnetic tags was attached to the heart. ...

It can be shown that an increase in transmural pressure while astronauts are in space may help with the vasoconstriction response. ...

Action potential duration (APD) changes increasing repolarization time (RT) dispersion are potentially arrhythmogenic. A repolarization model developed from electrocardiographic data of 5376 healthy men and women was used to derive parameter estimates for APD and RT and their transmural gradients (RT(grad) and APD(grad), respectively) in myocardial ...

... it may occur elsewhere on the body. The roughness is accentuated by dry skin and the condition ...

Isolation, confinement, and the characteristics of microgravity will accentuate the need for privacy

... Massive nugratlon and &slocatlon fueled by pohtlcal and ethmc confhct accentuated deforestation, erosion, and desertlficanon ...