Successful Permanent Resynchronization for Failing Right Ventricle After Repair of Tetralogy of Fallot
Abstract
After repair of tetralogy of Fallot with significantly decreased exercise tolerance, a 17-year-old symptomatic boy underwent successful permanent resynchronization of a failing right ventricle (RV). The patient had surgical repair including pulmonary valvulotomy, infundibulectomy, and pericardial right ventricular outflow tract (RVOT) plasty at 1 year of age.
At 3 years of age, he underwent resection of RVOT aneurysm, pulmonary valvuloplasty, and patch enlargement of the left pulmonary artery. Finally, a balloon pulmonary valvuloplasty of a mild residual pulmonary valve stenosis was performed at 17 years of age, resulting in a gradient reduction from 18 to 4 mm Hg and mild (grade I) pulmonary and tricuspid regurgitation.
However, the patient continued to show significant RV dilation and systolic/diastolic dysfunction with signs of major RV dyssynchrony (right bundle-branch block; QRS duration of 200 ms and paradoxical interventricular septal motion with a late systolic right to left septal flash) by echocardiography and MRI.1 As a result of reports on successful acute subpulmonary RV resynchronization,2-4 the patient underwent resynchronization testing in the catheterization laboratory with the aim to identify the RV pacing site associated with maximum acute increase in RV dP/dt max (from 432 to 624 mm Hg/s) when pacing in complete fusion with spontaneous activation. One month later, an MRI-compatible permanent transvenous dual-chamber pacemaker was implanted, with ventricular pacing lead inserted as close as possible to the previously identified optimal site at the RV free wall (Figure 1), resulting in a Q-RV interval of 140 ms, proving late electric activation of this area.
Atrio-ventricular delay was programmed to achieve complete fusion with spontaneous ventricular depolarization, as subsequently confirmed by 24-hour Holter ECG.