Cardiac resynchronization therapy in pediatric heart failure

Abstract

Heart failure is implicated in nearly 300,000 deaths annually, and is the leading cause of death or disability in adults in the United States [1,2]. Patients with heart failure often demonstrate mechanical dyssynchrony, characterized by dyskinetic ventricular contraction, regional myocardial hypokinesis, and perturbations in the natural ventricular geometry. Mechanical dyssynchrony may be associated with electrical dyssynchrony, an abnormal ventricular depolarization pattern, which is often accompanied by a bundle branch block on ECG. Such alterations in the normal contraction pattern of the left ventricle can lead to poor hemodynamics, altered ventricular function, and even changes in myocyte structure. Cardiac resynchronization therapy, which involves the individual pacing of the right atrium as well as both ventricles to provide a more physiologic atrio-ventricular (AV) delay and a more synchronous contraction of the left and right ventricles, re-establishes a more normal contraction pattern and has been shown to be an effective treatment for heart failure due to left ventricular dysfunction in adults. In children, the role of cardiac resynchronization therapy is less well understood. Given the diverse etiologies of dilated cardiomyopathy in children as well as the individual anatomic and physiologic considerations of patients with congenital heart disease, re-establishing physiologic synchrony and improving ventricular function are considerable challenges in pediatric cardiology. This manuscript describes the more recent exploration of cardiac resynchronization therapy in the pediatric population, with emphasis on its emerging use in patients with heart failure associated with congenital heart disease, including the situation of the single ventricle.