Cardiac resynchronization therapy for adult congenital heart disease patients with a systemic right ventricle: analysis of feasibility and review of early experience

Mechanical right ventricular dyssynchrony in patients after atrial switch operation for transposition of the great arteries

Recent data suggest potential benefits of cardiac resynchronization therapy in the management of right ventricular (RV) dysfunction in congenital heart disease. The aim of this study was to determine the nature, prevalence, and functional implications of mechanical RV dyssynchrony in patients after Senning or Mustard procedures for transposition of the great arteries. Twenty-eight patients (mean age 21.1 +/- 3.5 years) at 19.9 +/- 3.2 years after atrial switch operations and 29 healthy controls were studied. The times from the onset of QRS to peak systolic strain (T epsilon) at the base of and the mid RV free wall, the ventricular septum (VS), and the left ventricular (LV) free wall were determined using tissue Doppler echocardiography. Intraventricular mechanical delay was defined as Delta T epsilon(RV-VS) and interventricular mechanical delay as Delta T epsilon(RV-LV). In patients, the magnitude of RV intra- and interventricular mechanical delay was correlated with cardiac magnetic resonance-derived RV volumes and ejection fractions (n = 26) and treadmill exercise testing parameters (n = 20). Compared with controls, patients had significantly longer Delta T epsilon(RV-VS) (48.1 +/- 50.9 vs 17.0 +/- 16.1 ms, p <0.001) and Delta T epsilon(RV-LV) (63.1 +/- 49.5 vs 19.0 +/- 12.9, p <0.001). Nine patients (32%) exhibited RV dyssynchrony (Delta T epsilon(RV-VS) >49 ms, control mean +/- 2SD), and 16 patients (57%) showed interventricular dyssynchrony (Delta T epsilon(RV-LV) >45 ms). In patients, RV intra- and interventricular mechanical delay was correlated negatively with the RV ejection fraction (both r = -0.42, p = 0.03) and percentage predicted maximum oxygen consumption (r = -0.50, p = 0.03, and r = -0.52, p = 0.02, respectively) and positively with minute ventilation/carbon dioxide production slope (r = 0.49, p = 0.03, and r = 0.56, p = 0.01, respectively). In conclusion, RV dyssynchrony is common in young adults after atrial switch operations and is associated with RV systolic dysfunction and impaired exercise performance.

Triplane Tissue Doppler Imaging to Evaluate Mechanical Dyssynchrony Before and After Cardiac Resynchronization in a Patient with Congenitally Corrected Transposition of the Great Arteries

We report the case of a 13-year-old girl with congenitally corrected transposition of the great arteries. Since the implantation of a conventional pacemaker for acquired complete atrioventricular block, the patient experienced increased heart failure symptoms. Using triplane tissue Doppler imaging, significant intraventricular dyssynchrony induced by unilateral pacing and associated with diminished exercise capacity was demonstrated. A biventricular pacemaker was successfully implanted transvenously, leading to synchronous activation of the systemic ventricle and improved exercise capacity.