Value of the New Doppler-Derived Myocardial Performance Index for the Evaluation of Right and Left Ventricular Function Following Repair of Tetralogy of Fallot

Abstract

The systolic and diastolic function in both ventricles may be altered even after successful corrective surgery of tetralogy of Fallot. The aim of this study was to assess the combined diastolic and systolic function of both ventricles using the Doppler-derived myocardial performance index (MPI) in patients with operated tetralogy of Fallot (TOF). We performed a prospective analysis of 51 patients following corrective surgery of TOF: 21 had a subannular patch, 20 had a homograft implantation at initial operation, and 10 were reoperated with secondary homograft implantation. Patients were examined with Doppler echocardiography, and the MPI, which incorporates ejection and isovolumetric relaxation and contraction times and is an index of global ventricular function, was calculated 10.2 ± 8.0 (0.89–36) years after surgery. In 86.4% of the examined patients the right ventricular isovolumetric relaxation time was shortened compared to the normal published range or even did not exist (negative value) (p <0.01). The right ventricular MPI was paradoxically below the normal published range in 76.5% of the examined patients. The left ventricle global function was impaired in 23.5% of the examined patients, mainly due to altered systolic function with a prolonged left ventricular isovolumetric contraction time. The z score of the comparison between patients' left ventricular isovolumetric contraction time and the normal published values was 3.03. Patients with severe pulmonary regurgitation also had a prolongation of the isovolumetric relaxation time compared to patients with mild to moderate pulmonary regurgitation. The noncompliant right ventricle may shorten the right ventricular isovolumetric relaxation time, resulting in a paradoxically low right MPI. This may reduce the sensitivity of the index in recognizing patients with right ventricular dysfunction following corrective surgery of TOF. Additional diastolic impairment occurs in patients with right ventricular volume overload.