Theoretical and experimental studies have shown that restitution of the cardiac action potential (AP) duration (APD) plays a major role in predisposing ventricular tachycardia to degenerate to ventricular fibrillation, whereas its role in atrial fibrillation is unclear. We used the Courtemanche human atrial cell model and the Luo-Rudy guinea pig ventricular model to compare the roles of electri...

Tissue Doppler, an echocardiographic modality measuring velocities of solid cardiac structures by pulsed-wave or colour Doppler, after very early experiments was introduced clinically in the early 1990s and is one of the very few recent technical innovations in echocardiography to gain quick and near-ubiquitous clinical implementation. The most widely adopted application is the registration of ...

To characterize age-related changes in beta-adrenergic responsiveness and to test the hypothesis that an increase in the effects of adenosine contribute to impaired beta-adrenergic responsiveness, Fischer 344 rat right atria (RA), left atria (LA), and left ventricular trabeculae carnae were exposed to the beta-receptor agonist isoproterenol (ISO), followed by four doses of the selective adenosi...

Significant tissue structures exist in cardiac ventricular tissue that are of supracellular dimension. It is hypothesized that these tissue structures contribute to the discontinuous spread of electrical activation, may contribute to arrhymogenesis and also provide a substrate for effective cardioversion. However, the influences of these mesoscale tissue structures in intact ventricular tissue ...

The short QT syndrome (SQTS) is a genetically heterogeneous condition characterized by abbreviated QT intervals and an increased susceptibility to arrhythmia and sudden death. This simulation study identifies arrhythmogenic mechanisms in the rapid-delayed rectifier K(+) current (I(Kr))-linked SQT1 variant of the SQTS. Markov chain (MC) models were found to be superior to Hodgkin-Huxley (HH) mod...

introduction: cardiac remodeling after myocardial infarction, is associated with progressive ventricular dysfunction and cardiovascular death. the purpose of this study was to examine the effect of endurance exercise training on morphological changes in rat heart tissue following experimental myocardial infarction. materials and methods: rats used in this experiment (8-10 weeks old, 235 ± 5 g b...

BackgroundIncreased metabolic rate of hyperglycemia in gestational diabetes causes macrosomia, which can also affect the fetal heart. The thickness of the walls of the heart and its function in women with gestational diabetes mellitus (GDM) can change over time before treatment. We aimed to evaluate fetal cardiac structure in terms of ventricular wall thickness and its function in women w...

BACKGROUND Pulmonary arterial hypertension is usually fatal due to right ventricular failure and is frequently associated with co-existing left ventricular dysfunction. Endothelin-1 is a powerful pro-fibrotic mediator and vasoconstrictor that is elevated in pulmonary arterial hypertension. Endothelin receptor blockers are commonly used as pulmonary vasodilators, however their effect on biventri...

INTRODUCTION AND OBJECTIVES To evaluate ventricular function using Doppler echocardiography in patients with an atrial septal defect (ASD). METHODS The study involved 158 children, who were divided into two groups: Group 1 comprised 111 children with an ASD, and Group 2, 47 healthy children. Left ventricular systolic function was evaluated by measuring the ejection fraction, the shortening fr...

Magnetic Resonance Imaging (MRI) is currently considered as the noninvasive modality of choice for evaluation of patients with suspected Arrhythmogenic Right Ventricular Dysplasia (i.e., right ventricular dysplasia). As arrhythmogenic right ventricular cardiomyopathy/dysplasia (ARVC/D) it is included in the WHO classification of cardiomyopathies. It has the unique ability to provide tissue char...