Doppler myocardial performance index in assessment of ventricular function in children with single ventricles

Background: Quantitative assessment of ventricular function in children with single ventricles is both difficult and subjective because of asymmetric ventricular geometry. The Doppler myocardial performance index (MPI) allows the assessment regardless of ventricular shape. This study was designed to evaluate the feasibility of MPI in assessing ventricular function in children with single ventricles before and after total cavopulmonary connection (TCPC). Methods: Subjects consisted of 161 pediatric patients with single ventricles and 80 normal children without heart disease. The maximum positive rate of ventricular pressure change (Max dp/dt) was obtained in 58 patients by cardiac catheterization. Sixty-eight children with single ventricles received TCPC. MPI was calculated from Doppler tracings of ventricular inflow and outflow, then MPI of single ventricles before and after surgery and normal heart were compared. Results: Normal MPI value was 0.30 +/- 0.08 in the left ventricle and 0.26 +/- 0.08 in the right ventricle. Compared to normal children, MPI was significantly higher in 161 children with single ventricles (0.54 +/- 0.11, P < 0.001). MPI correlated inversely with Max (dp/dt) (r=-0.77, P < 0.01), and was positively related to age (r=0.54, P < 0.01) in patients with single ventricles. MPI did not differ significantly before and after surgery in 68 patients with single ventricles (0.55 +/- 0.21 vs 0.51 +/- 0.20, P > 0.05). However, MPI in 48 patients of < 6 years old decreased significantly (0.55 +/- 0.21 vs 0.48 +/- 0.18, P < 0.05), suggesting improved ventricular function. Conclusions: Compared to normal children, ventricular function is impaired in patients with single ventricles and may worsen with age. MPI provides an accurate method for assessing ventricular function in children with single ventricles before and after TCPC.