Electrical remodeling in a canine model of ischemic cardiomyopathy.

The nature of electrical remodeling in a canine model of ischemic cardiomyopathy (ICM; induced by repetitive intracoronary microembolizations) that exhibits spontaneous ventricular tachycardia is not entirely clear. We used the patch-clamp technique to record action potentials and ionic currents of left ventricular myocytes isolated from the region affected by microembolizations. We also used the immunoblot technique to examine channel subunit expression in adjacent affected tissue.

KCNE2 protein is expressed in ventricles of different species, and changes in its expression contribute to electrical remodeling in diseased hearts.

Background: Mutations in KCNE2 have been linked to long-QT syndrome (LQT6), yet KCNE2 protein expression in the ventricle and its functional role in native channels are not clear.

Methods And Results: We detected KCNE2 protein in human, dog, and rat ventricles in Western blot experiments. Immunocytochemistry confirmed KCNE2 protein expression in ventricular myocytes.

Characterization of sustained atrial tachycardia in dogs with rapid ventricular pacing-induced heart failure.

Introduction: Atrial arrhythmias often complicate congestive heart failure (CHF). We characterized inducible atrial tachyarrhythmias and electrophysiologic alterations in dogs with CHF and atrial enlargement produced by rapid ventricular pacing.

Methods And Results: Endocardial pacing leads were implanted in the right ventricle, right atrium, and coronary sinus in 18 dogs.

Swelling-activated chloride channels in cardiac physiology and pathophysiology.

Characteristics and functions of the cardiac swelling-activated Cl current (I(Cl,swell)) are considered in physiologic and pathophysiologic settings. I(Cl,swell) is broadly distributed throughout the heart and is stimulated not only by osmotic and hydrostatic increases in cell volume, but also by agents that alter membrane tension and direct mechanical stretch. The current is outwardly rectifying, reverses between the plateau and resting potentials (E(m)), and is time-independent over the physiologic voltage range.

Long-term outcome of patients after successful radiofrequency ablation for typical atrial flutter.

The aim of the study was to determine the long-term freedom from atrial arrhythmias after radiofrequency ablation of atrial flutter and to determine the factors associated with recurrent arrhythmias. Radiofrequency ablation has emerged as the preferred treatment for recurrent, typical atrial flutter. Although the short-term results after radiofrequency ablation of atrial flutter have been widely reported, there is insufficient data on long-term outcome with respect to the occurrence of atrial arrhythmias in patients after successful ablation.

Detection and management of an implantable cardioverter defibrillator lead failure: incidence and clinical implications.

Objectives: This study evaluated the long-term reliability of an implantable cardioverter defibrillator (ICD) lead to determine the incidence, clinical presentation, and management of lead failure.

Background: Despite recent advances in ICD technology, the long-term reliability of ICD leads remains a significant problem.

Methods: Concern about long-term reliability of coaxial polyurethane ICD leads caused us to systematically study all patients implanted with Medtronic (Minneapolis, Minnesota) 6936 lead at our institution.