Recovery of Left Ventricular Systolic Function After Biventricular Resynchronization Pacing in a Child With Repaired Tetralogy of Fallot and Severe Biventricular Dysfunction
A 5-year-old child had undergone surgical repair of a ventricular septal defect and pulmonary stenosis at the age of 4 months. The repair required a total of 3 episodes of cardiopulmonary bypass and was complicated by complete atrioventricular block. Subsequently, a permanent dual-chamber pacemaker was implanted, with epicardial leads on the right atrium and the right ventricular outflow tract. Late postoperative complications included atrial ectopic tachycardia, controlled with amiodarone, and progressive left ventricular systolic dysfunction, treated with increasing doses of digoxin, captopril, furosemide, and hydrochlorothiazide-spironolactone.
The patient was referred to our center for ongoing management and consideration for heart transplantation. Medical therapy was optimized, including the addition of carvedilol, but by 5 years of age, the patient was severely symptomatic (New York Heart Association class III). His echocardiogram demonstrated severely impaired left ventricular systolic function (ejection fraction, 24%) with evidence of a thinned and dyskinetic interventricular septum (Figure, A and B; Movie I and Movie II in the online Data Supplement).
The patient underwent diagnostic cardiac catheterization with assessment of the physiological response to multiple pacing sites. Because of the patient’s small size and anatomy, coronary sinus pacing could not be achieved. There was a quantitative improvement in both cardiac index (by direct Fick) and left ventricular performance (dP/dt by micromanometer), optimally with right ventricular apical stimulation. In view of demonstrable interventricular dyssynchrony, the pacing system was revised to an atrial-biventricular system (Insync III, Medtronic Inc, Minneapolis, Minn), with new epicardial leads in the right atrium, right ventricular apex, and left ventricular free wall. Optimization of atrioventricular and interventricular delays (atrioventricular, 110 ms; right ventricular–left ventricular, 48 ms) was achieved by simultaneous transmitral velocity time integral and tissue Doppler analysis in the immediate postoperative period, which confirmed the benefit of biventricular pacing over right ventricular apical pacing alone.
At follow-up 4 months after resynchronization, the patient’s symptoms had improved significantly (New York Heart Association class I). Repeat echocardiography demonstrated increased left ventricular systolic function (ejection fraction, 60%) with marked improvement of interventricular septal motion and thickening (Figure, C and D; Movie III and Movie IV).
Although there are widespread reports of the effectiveness of biventricular pacing in adults with acquired left ventricular dysfunction, there is little published experience as to the utility of this pacing modality in children with congenital heart disease. Tetralogy of Fallot may be complicated by significant biventricular dysfunction1 that, when present, is associated with an increased risk of sudden death.2 This patient demonstrated dramatic symptomatic and physiological improvement, which suggests that this technique may be of benefit in carefully selected patients.
The online-only Data Supplement can be found at http://circ.ahajournals.org/cgi/content/full/113/14/e691/DC1.