Apoptosis of Cardiomyocytes in Children with Right Ventricular Pressure Overload with and without Hypoxemia

BACKGROUND: Cardiomyocyte apoptosis has been implicated in ventricular remodeling and initiation of cardiac failure. We sought to determine the severity of right ventricular (RV) cardiomyocyte apoptosis in cyanotic and acyanotic children with RV pressure overload. METHODS: Fourteen patients, seven with tetralogy of Fallot (group I) and seven with pulmonary stenosis and ventricular septal defect (group II), undergoing open-heart surgery were studied. Right ventricular biopsies were examined for cardiomyocyte apoptosis by terminal deoxynucleotide transferase-mediated dUTP nick-end labeling. The magnitude of cardiomyocyte apoptosis was related to preoperative oxygen saturation and postoperative inotrope use and hospital stay. RESULTS: Compared with group I patients, group II patients were significantly older at operation (p = 0.002) and had a larger body size (p < 0.01) and higher preoperative oxygen saturation (p = 0.01). The prevalence of cardiomyocyte apoptosis in both group I and II patients as a whole was 0.24 ± 0.29% (range, 0% to 1.10%). The prevalence was similar between group I (median 0.30%, range 0% to 1.10%) and group II (median 0.20, range 0% to 0.40%, p = 0.65). The prevalence of cardiomyocyte apoptosis correlated positively with preoperative oxygen saturation on room air (r = -0.69, p < 0.005) and postoperative inotrope score (r = 0.67, p = 0.001). A higher postoperative inotrope score (r = 0.68, p = 0.001) was associated with a significant longer duration of postoperative stay in the hospital. CONCLUSIONS: The prevalence of cardiomyocyte apoptosis in the pressure-overloaded right ventricle is related to the severity of hypoxia and may have an impact on postoperative course in terms of early postoperative use of inotropes and duration of hospital stay.