A case of complete heart block secondary to rheumatoid involvement of the conduction system is presented. The same patient died after infarction of the colon as a consequence of arterial spasm superimposed upon pre-existing rheumatoid changes in the mesenteric arteries. The coexistence of rheumatoid involvement of the heart and of the bowel vasculature has not previously been reported.

Bundle branch reentrant (BBR) tachycardia is an uncommon form of ventricular tachycardia (VT) incorporating both bundle branches into the reentry circuit. The arrhythmia is usually seen in patients with an acquired heart disease and significant conduction system impairment, although patients with structurally normal heart have been described. Surface ECG in sinus rhythm (SR) characteristically ...

The explosion of stem cell research in cardiology has yielded an increasing recognition that understanding developmental cell fate decisions is critical for everything from disease models to cellular therapeutics. However, the biology is particularly rich and complex and has not yielded easily to traditional investigative methods. One area of intense focus is the study of the cues responsible f...

The cardiac conduction system (CCS) transmits electrical activity from the atria to the ventricles to coordinate heartbeats. Atrioventricular conduction diseases are often associated with defects in the central ventricular conduction system comprising the atrioventricular bundle (AVB) and right and left branches (BBs). Conducting and contractile working myocytes share common cardiomyogenic prog...

During development, the ventricular conduction system (VCS) arises from the trabecular or spongy myocardium. VCS and trabecular myocytes proliferate at a significantly slower rate than compact zone myocardial cells, establishing a transmural cell cycle gradient. The molecular determinants of VCS/trabecular myocyte cell cycle arrest are not known. Given the importance of pocket proteins (Rb, p10...

It is critical for interventional electrophysiologists to thoroughly appreciate the topographic and developmental anatomy of the heart and its conduction system. Not only is understanding cardiac anatomy important to prevent complications from collateral damage and to help guide catheter placement, but developmental anatomy allows a deeper appreciation of the arrhythmogenic substrate. In this a...

background: potassium, as an extracellular ion, plays an important role in the electrophysiologic function of the myocardium and any change in extracellular concentration of this ion might have a marked impression upon myocyte electrophysiologic gain. high serum potassium levels are thought to impair pulse conduction in purkinje fibers and ventricles more than that in the atrioventricular (av) ...

A recent clinical report demonstrated facilitation of conduction in both the A-V node and HisPurkinje system with intravenous isoproterenol.' Despite this facilitation of conduction, it was anticipated that paradoxic worsening of conduction could occur in patients with bilateral bundle branch disease, due to increase in atrial rate with this agent.' In this report, we document paradoxic worseni...