Atrial fibrosis and conduction slowing in the left atrial appendage of patients undergoing thoracoscopic surgical pulmonary vein isolation for atrial fibrillation.

Background: Atrial fibrosis is an important component of the arrhythmogenic substrate in patients with atrial fibrillation (AF). We studied the effect of interstitial fibrosis on conduction velocity (CV) in the left atrial appendage of patients with AF.

Methods And Results: Thirty-five left atrial appendages were obtained during AF surgery.

Early repolarization in mice causes overestimation of ventricular activation time by the QRS duration.

Aims: Transgenic mice are frequently used to investigate the role of genes involved in cardiac conduction. The QRS duration calculated from the electrocardiogram (ECG) is a commonly used measure for ventricular conduction time. However, the relation between ventricular activation and QRS duration calculated from a mouse surface ECG is not well understood.

The Driving Force of the Na/Ca-Exchanger during Metabolic Inhibition.

Objective: Metabolic inhibition causes a decline in mechanical performance and, if prolonged, myocardial contracture and cell death. The decline in mechanical performance is mainly due to altered intracellular calcium handling, which is under control of the Na(+)/Ca(2+)-exchanger (NCX) The driving force of the NCX (ΔG(ncx)) determines the activity of NCX. The aim of this study was to describe the relation between ΔG(ncx) and calcium homeostasis during metabolic inhibition.

Acute administration of fish oil inhibits triggered activity in isolated myocytes from rabbits and patients with heart failure.

Background: Fish oil reduces sudden death in patients with prior myocardial infarction. Sudden death in heart failure may be due to triggered activity based on disturbed calcium handling. We hypothesized that superfusion with omega3-polyunsaturated fatty acids (omega3-PUFAs) from fish inhibits triggered activity in heart failure.

Dietary fish oil reduces the incidence of triggered arrhythmias in pig ventricular myocytes.

Background: Fish oil reduces the incidence of sudden cardiac death in postmyocardial infarction patients. Triggered activity is the principal mechanism of arrhythmogenesis under these conditions.

Objective: The purpose of this study was to test whether dietary fish oil in pigs inhibits Ca2+ overload-induced triggered activity.

Incorporated sarcolemmal fish oil fatty acids shorten pig ventricular action potentials.

Background: Omega-3 polyunsaturated fatty acids (omega3-PUFAs) from fish oil reduce the risk of sudden death presumably by preventing life-threatening arrhythmias. Acutely administered omega3-PUFAs modulate the activity of several cardiac ion channels, but the chronic effects of a diet enriched with fish oil leading to omega3-PUFA-incorporation into the sarcolemma on membrane currents are unknown.

Methods: Pigs received a diet either rich in omega3-PUFAs or in omega9-fatty acids for 8 weeks.

Intrinsic heterogeneity in repolarization is increased in isolated failing rabbit cardiomyocytes during simulated ischemia.

Objective: Myocardial ischemia and ventricular arrhythmias often complicate congestive heart failure. Ischemia-induced dispersion in repolarization is an important arrhythmogenic factor that might be caused by intrinsic cellular differences in response to simulated ischemia (SI) or by changed coupling of myocytes. We hypothesized that intrinsic heterogeneity in action potential duration (APD) or the occurrence of rigor is larger in failing than in normal rabbit myocytes during SI.

SR calcium handling and calcium after-transients in a rabbit model of heart failure.

Objective: After-depolarization associated arrhythmias are frequently observed in heart failure and associated with spontaneous calcium release from sarcoplasmic reticulum (SR), calcium after-transients. We hypothesize that disturbed SR calcium handling underlies calcium after-transients in heart failure (HF).

Methods: We measured the stimulation rate dependence (0.