Another Step in the Right Direction: Resynchronizing the Dyssynchronous Right Ventricle Improves Its Efficiency and Function.

Abstract

Advances in the diagnosis, surgery, and management of patients with congenital heart disease (CHD) have vastly improved their survival. Of these, a representative example is tetralogy of Fallot (TOF)—a common and previously debilitating and lethal cyanotic CHD—where surgical repair in infancy or childhood has dramatically improved survival and quality of life. However, the residual anatomic and hemodynamic abnormalities associated with surgical repair of CHD, including TOF, lead to arrhythmias, exercise intolerance, heart failure, impaired quality of life, and death. The incidence of these sequelae sharply increases 3 decades after childhood repair.1,2 See Article by Janousek et al Right ventricular (RV) remodeling and failure underlie these complications and outcomes. Of the lesions created by surgical repair of CHD and TOF, long-standing, severe pulmonary regurgitation (PR) is currently considered a major cause of RV dilatation and failure. Consequently, most emphasis has been placed on the indications for, and development of, surgical and transcatheter pulmonary valve replacement for PR and outflow tract dysfunction.3 Although pulmonary valve replacement leads to improved RV remodeling and function, its beneficial effects on exercise intolerance, arrhythmias, and sudden death are inconclusive, and a considerable proportion of patients do not adequately improve.4 Hence, it is apparent that PR is not the only mechanism underlying RV dysfunction and that other pathophysiological mechanisms contribute to RV failure. Among these, RV electromechanical dyssynchrony, caused by right bundle branch block (RBBB) from surgery in the proximal right bundle of His during closure of the ventricular septal defect, or in the distal bundle of His, during relief of RV outflow obstruction, is important, with relatively well-characterized and treatable pathophysiology.5 However, although RV electromechanical dyssynchrony is common after repair of TOF and other CHD, and well recognized, it has been largely ignored as a cause of RV failure and …