Presence of ventricular dyssynchrony and haemodynamic impact of right ventricular pacing in adults with repaired Tetralogy of Fallot and right bundle branch block

Abstract

Some TOF adults with RBBB exhibit biventricular electromechanical dyssynchrony. However, in symptomatic patients with RV dysfunction, atrio-synchronized RV pacing does not induce significant acute haemodynamic improvement.

Mechanisms of Right Ventricular Electromechanical Dyssynchrony and Mechanical Inefficiency in Children After Repair of Tetralogy of Fallot

“…1,2 Similarly, right bundle branch block (RBBB) is common, and prolonged QRS duration conveys risk for adverse outcome. 3 Although electromechanical abnormalities are recognized in this population, 2,[4][5][6] specific patterns of regional mechanical abnormalities induced by abnormal electric activation associated with RBBB have not been studied. In left bundle branch block (LBBB), abnormal electric activation leads to a typical mechanical dyssynchrony pattern characterized by early septal activation, observed echocardiographically as a septal flash, with concomitant lateral wall prestretch and late contraction of the early-stretched lateral wall.…”

Validation of an animal model of right ventricular dysfunction and right bundle branch block to create close physiology to postoperative tetralogy of Fallot

“…Any additional contribution of the initial hypoxemia and genetic alterations to the development of late left and right ventricular dysfunction or arrhythmias are not accounted for in this condition [24,25]. The model, nevertheless, closely reproduced the electrophysiologic and mechanical abnormalities found in patients with this disorder, including the delayed development of the right bundle branch block [8,9,19]. The animals developed QRS widening as they aged as seen in humans.…”

“…The surgical repair of TOF is highly successful, though may be later complicated by right ventricular dysfunction due to volume and pressure overload and by late sudden death. The incompletely understood mechanisms of these delayed adverse developments may be partially due to the surgically-induced permanent right bundle branch block (BBB) and ventricular dyssynchrony [4][5][6][7][8][9]. Therapeutic options remain limited.…”

“…However, studies of the safety and efficacy of cardiac resynchronization in patients with congenital heart disease and RV dysfunction are limited to case reports, retrospective analyses of heterogeneous populations and small crossover trials conducted in the immediate postoperative period [10][11][12][13][14][15]. To identify risk factors leading to sudden death in TOF patients [16][17][18] and to define mechanisms involved in hemodynamic improvement induced by cardiac resynchronization [8,19], we aimed to develop a viable and reproducible swine model recapitulating the findings of right heart failure and right bundle branch block observed after prior surgical repair of TOF.…”

Pacing treatment for dilated cardiomyopathy: optimization of resynchronization pacing in pediatrics

“…Patients with QRS duration greater than 180 ms have been shown to have significant intraventricular delay and abnormal strain patterns by vector velocity imaging as well as decrease in left ventricular ejection fraction [34]. Attempts to optimize more traditional pacing modalities have shown that, if RV dysfunction has already become apparent, no acute hemodynamic benefit is seen with purely atrioventricular synchronized RV pacing [35]. It is possible, however, to normalize the QRS duration in some patients with Tetralogy of Fallot by adjusting the atrioventricular delay [36].…”