Power loss and right ventricular efficiency in patients after tetralogy of Fallot repair with pulmonary insufficiency: clinical implications.

OBJECTIVES: To quantify right ventricular output power and efficiency and correlate these to ventricular function in patients with repaired tetralogy of Fallot. This might aid in determining the optimal timing for pulmonary valve replacement. METHODS: We reviewed the cardiac catheterization and magnetic resonance imaging data of 13 patients with tetralogy of Fallot (age, 22 ± 17 years). Using pressure and flow measurements in the main pulmonary artery, cardiac output and regurgitation fraction, right ventricular (RV) power output, loss, and efficiency were calculated. The RV function was evaluated using cardiac magnetic resonance imaging. RESULTS: The RV systolic power was 1.08 ± 0.62 W, with 20.3% ± 8.6% power loss owing to 41% ± 14% pulmonary regurgitation (efficiency, 79.7% ± 8.6%; 0.84 ± 0.73 W), resulting in a net cardiac output of 4.24 ± 1.82 L/min. Power loss correlated significantly with the indexed RV end-diastolic and end-systolic volume (R = 0.78, P = .002 and R = 0.69, P = .009, respectively). The normalized RV power output had a significant negative correlation with RV end-diastolic and end-systolic volumes (both R = -0.87, P = .002 and R = -0.68, P = .023, respectively). A rapid decrease occurred in the RV power capacity with an increasing RV volume, with the curve flattening out at an indexed RV end-diastolic and end-systolic volume threshold of 139 mL/m(2) and 75 mL/m(2), respectively. CONCLUSIONS: Significant power loss is present in patients with repaired tetralogy of Fallot and pulmonary regurgitation. A rapid decrease in efficiency occurs with increasing RV volume, suggesting that pulmonary valve replacement should be done before the critical value of 139 mL/m(2) and 75 mL/m(2) for the RV end-diastolic and end-systolic volume, respectively, to preserve RV function.

Role of high-pressure balloon valvotomy for resistant pulmonary valve stenosis.

BACKGROUND: Pulmonary valve (PV) balloon valvotomy (BV) is considered the treatment of choice for isolated pulmonary valve stenosis (IPVS). While immediate and long-term results of PVBV are usually excellent, the reported results in dysplastic valves are variable. High-pressure (HP) PVBV in dysplastic valves that fail low-pressure (LP) PVBV may increase success rate, reducing the need for surgical interventions. METHODS: We reviewed all cases of IPVS in patients <3 years old, who underwent PVBV between August 1999 and March 2004. Study outcomes were initial success rate (gradient post PVBV < 30 mm Hg) and freedom from reintervention. Possible predictors of failure to LP-PVBV were explored (age, hemodynamic data, PV leaflet maximal thickness, diameter/z-scores for PV annulus, sinotubular junction, and subvalvar area). RESULTS: All 35 patients (16 neonates, 5 with critical IPVS) underwent LP-PVBV with immediate success in 27 (80%). All eight patients who failed LP-PVBV successfully underwent HP-PVBV. Upon follow-up (27 +/- 24 months), two patients (6.9%) required reintervention after LP-PVBV (LP-PVBV at 3 months, HP-PVBV at 2 months with success, both reintervention free thereafter), and one patient (12.5%) after HP-PVBV (surgical right ventricular outflow tract patch at 33 months) (Fisher's exact test = 0.5). There were no major immediate or long-term complications. After nonparametric median regression, age (2 vs. 11 months, P < .001) and PV maximal thickness (0.13 vs. 0.24 cm, P= .026) were the only predictors of failure to LP-PVBV. CONCLUSION: HP-PVBV can be performed safely in patients with IPVS that fail LP-PVBV, with high success rate and acceptable long-term results. Failure to LP-PVBV is difficult to predict.