Successful Permanent Resynchronization for Failing Right Ventricle After Repair of Tetralogy of Fallot.
Kubus, P; Materna, O; Tax, P; Tomek, V; Janousek, J. Circulation. 2014 Nov 25;130(22):e186–90. doi: 10.1161/CIRCULATIONAHA.114.012205. IF: 14.948
MUDr. Peter Kubuš, Ph.D., Children's Heart Centre
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. As a result of reports on successful acute subpulmonary RV resynchronization, 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 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.
Six months later, a major decrease in RV size, along with improvement in RV as well as LV function, functional class, and exercise capacity were noted. We conclude that permanent resynchronization of a failing RV is an effective method to achieve hemodynamic improvement after repair of tetralogy of Fallot. Patients with right bundle-branch block and significant RV dilation and dysfunction might be considered for this procedure in isolation or along with other indicated surgical or transcatheter interventions. RV electromechanical dyssynchrony may be, in addition to volume overload, a major factor in RV failure development. The precise role and indications for this novel treatment option remain to be studied. This is, to our knowledge, the first report of successful permanent resynchronization of a failing subpulmonary RV in congenital heart disease.