Nongeometric quantitative assessment of right and left ventricular function: myocardial performance index in normal children and patients with Ebstein anomaly.

Assessment of ventricular systolic function has been based on the geometric models of ventricular shape. This study was designed to define normal values for a nongeometric myocardial performance index (MPI) in children and to evaluate the utility of MPI in congenital heart disease. The MPI measures the ratio of total time spent in isovolumic activity (isovolumic contraction time and isovolumic relaxation time) to the ejection time. The right ventricular (RV) and left ventricular (LV) MPI were measured in 152 normal children (ages 3 to 18 years) and 45 preoperative patients with Ebstein anomaly (age 1 week to 52 years). In normal children, the RV MPI was 0.32+/-0.03 and the LV MPI was 0.35+/-0.03. In the Ebstein group, both RV and LV MPI were abnormally increased compared with age-matched normal subjects (Ebstein group: RV MPI=0.49+/-0.12, LV MPI=0.42+/-0.09, P < .001). Increasing RV dysfunction was associated with progressively increasing (abnormal) values of RV MPI (P < .001). The myocardial performance index quantitatively reflects ventricular performance in patients with complex ventricular geometry (ie, Ebstein anomaly). In the absence of a geometric solution, this nongeometric index is particularly appealing for the assessment of RV or LV performance.