Abstract 1947: Presence of Ventricular Dyssynchrony and Hemodynamic Impact of Right Ventricular Pacing in Adults with Tetralogy of Fallot and Right Bundle Branch Block
Introduction: Late after surgical repair, adults with Tetralogy of Fallot (TOF) are used to present with right ventricular (RV) dysfunction and right bundle branch block (RBBB). The aims of the present study were
to investigate whether this prolonged right ventricular conduction induced detrimental electromechanical right and left ventricular dyssynchrony
to determine the acute hemodynamic effects of atrio-synchronized RV pacing at different pacing sites.
We performed an echocardiography, coupled with tissue Doppler (TDI) and Strain rate (SRI) imaging, in 20 adults (mean age 24 ± 6 years) with TOF, sinus rhythm and RBBB. The interventricular dyssynchrony (IVD), the intra-RV dyssynchrony (IRVD), the intra-left ventricular dyssynchrony (ILVD) and the extent of RV myocardium displaying delayed longitudinal contraction (DLC) were assessed and compared with measurements of 30 healthy matched patients.
We performed an acute hemodynamic study in 6 patients (mean age 26 ± 3 years) with TOF, RV dysfunction, class NYHA 3 or 4 and RBBB. Cardiac output was measured during spontaneous ventricular rhythm and during atrio-synchronized ventricular pacing at 4 RV sites (infundibulum, apex, septal and lateral walls).
We observed higher IVD (45 ± 21 vs 18 ± 10 ms; p < 0.01), IRVD (41 ± 19 vs 13 ± 06 ms; p < 0.01), intra-RV DLC (31 ± 14vs 05 ± 01 %; p < 0.01) and a trend to a higher ILVD (29 ± 07 vs 18 ± 10 ms; p = 0.06) in TOF patients than in controls.
Atrio-synchronized ventricular pacing improved significantly (p < 0.05) the cardiac output as compared with the spontaneous rhythm. The lateral wall was the optimal pacing site in 83%.
Conclusion: TOF adults with RBBB and RV dysfunction exhibit major electromechanical dyssynchrony. In symptomatic patients, atrio-synchronized ventricular pacing improves hemodynamic performance. The lateral wall may be the optimal pacing site. RV resynchronization is a promising novel therapy for patients with RV failure.