Abstract
Besides heart rate, contractility, preload, and afterload, mechanical atrioventricular (AV) and inter- and intraventricular synchrony are major determinants of cardiac output and cardiac contraction efficiency. Chronic intraventricular electromechanical dyssynchrony, as caused by an electrical activation delay, may lead to dyssynchronous heart failure accompanied by significant structural and cellular remodeling.
Electrical retiming of the heart using temporary or permanent cardiac resynchronization pacing (cardiac resynchronization therapy , CRT ) has been used both to acutely manipulate cardiac output in the postoperative setting as well as to chronically treat dyssynchronous heart failure. CRT has been shown to induce reverse cellular remodeling in experimental studies and to improve systolic ventricular function in both adults and children.
In large randomized adult trials, CRT also decreased heart failure -related morbidity and improved overall survival. Although published evidence on CRT efficacy in children lags behind studies on adult patients with idiopathic and ischemic cardiomyopathy, principal effects seem to be the same.
This chapter will summarize the knowledge on the electrophysiology of heart failure as well as on temporary and permanent cardiac resynchronization pacing in children.