A novel cardiac pacing paradigm for atrial fibrillation and heart failure patients

It has been estimated that 4.6 million persons have heart failure, and 400,000 to 700,000 new cases develop each year and the U.S. Hospital discharges for HF rose from 399,000 in 1979 to 1,099,000 in 2004 according to the National Hospital Discharge Survey. Atrial fibrillation is the most common sustained cardiac arrhythmia in the United States. Recent studies have demonstrated that ventricular rate control is a viable treatment strategy for patients in atrial fibrillation.;In a number of cases, despite the electrical resynchronization of the ventricles using biventricular pacing (cardiac resynchronization therapy), heart failure patients in sinus rhythm do not respond to cardiac resynchronization therapy as with other heart failure patients. These non-responders may respond to our pacing paradigm which is the combined use of cardiac resynchronization therapy which is commonly designated as CRT and coupled pacing (CP) which will be referred to as CRT+CP.;Using a custom "Y"-lead adapter, an unmodified dual chamber clinical pacemaker can be used to achieve almost any combination of an experimental stimulation paradigm. And by using the asynchronous mode of a dual chamber pacemaker, the ventricles can be paced at rates sufficient to produce heart failure (180 to 240 beats per minute) which had been successfully accomplished as part of the research protocol in our coupled pacing paradigm studies. These specially designed Y connectors facilitated our coupled pacing and biventricular pacing paradigm studies, i.e. allowed us to induce AF and apply CP under experimental conditions.;My research on this novel pacing paradigm (CRT+CP) has shown that it slowed the contractile rate by half (116+/-16 cycles per minute vs. 259+/-15 cycles per minute). And CRT+CP as compared with CRT at a similar contractile rate (CRT-vagal stimulation at 103+/-14 cycles per minute) also dramatically increased both the diastolic period (48+/-6% vs. 27+/-3%, p=0.02) and the left ventricular ejection fraction (51+/-10% vs. 25+/-4%, p<0.001) as well.;This research has further demonstrated that the addition of a coupled paced beat significantly increased the left ventricular strain. The addition of coupled pacing to biventricular pacing also improved the left ventricular ejection (51+/-10%) to that of sinus rhythm despite the continual acute atrial fibrillation. CP may be combined with biventricular pacing (CRT+CP) to slow the ventricular rate of mechanical contractions and further improve contractility to a greater extent than what has been observed by CRT alone in patients with dyssynchronized heart failure and atrial fibrillation.