The electrophysiology of atrioventricular nodal reentry tachycardia following the Mustard or Senning procedure and its radiofrequency ablation.

We describe the electrophysiological studies undertaken in four patients with atrioventricular nodal reentry tachycardia in the setting of concordant atrioventricular and discordant ventriculo-arterial connections (transposition). Radiofrequency ablation was attempted in three, all with success. Clear evidence of dual antegrade pathways through the atrioventricular node was present in only one of the four, but other characteristics of discrete fast and slow pathways into the atrioventricular node were present in all.

Targeted point mutagenesis of mouse Kcnq1: phenotypic analysis of mice with point mutations that cause Romano-Ward syndrome in humans.

Inherited long QT syndrome is most frequently associated with mutations in KCNQ1, which encodes the primary subunit of a potassium channel. Patients with mutations in KCNQ1 may show only the cardiac defect (Romano-Ward syndrome or RWS) or may also have severe deafness (Jervell and Lange-Nielsen syndrome or JLNS). Targeted disruption of mouse Kcnq1 models JLNS in that mice are deaf and show abnormal ECGs.

Transcutaneous implantation of an internal cardioverter defibrillator in a small infant with recurrent myocardial ischemia and cardiac arrest simulating sudden infant death syndrome.

This report describes the implantation of a transcutaneous ICD system using a small patch electrode in the subscapular position, and an active-can device in a 5.3-kg infant. The indication for ICD implantation was recurrent cardiac arrest in the presence of normal coronary anatomy.

Familial hypertrophic cardiomyopathy-linked mutant troponin T causes stress-induced ventricular tachycardia and Ca2+-dependent action potential remodeling.

The cardiac troponin T (TnT) I79N mutation has been linked to familial hypertrophic cardiomyopathy and high incidence of sudden death, despite causing little or no cardiac hypertrophy in patients. Transgenic mice expressing mutant human TnT (I79N-Tg) have increased cardiac contractility, but no ventricular hypertrophy or fibrosis. Enhanced cardiac function has been associated with myofilament Ca2+ sensitization, suggesting altered cellular Ca2+ handling.