Effect of preload and heart rate on the Doppler and tissue Doppler-derived myocardial performance index

Doppler-derived myocardial performance index (MPI) has been described as a noninvasive measurement of LV function. Our aim was to investigate the effect of hemodialysis related volume reduction and heart rate changes on the Doppler-derived LV MPI, and Doppler tissue imaging (DTI) derived left and right ventricular MPI. Method: The study group comprised 32 consecutive patients (mean age: 43 ± 18 yrs) undergoing hemodialysis. Patients underwent echocardiography before and immediately after hemodialysis session. Left and right ventricular MPI derived from conventional pulsed-wave Doppler and DTI was calculated. The difference in MPI, heart rate and body weight was calculated before and after hemodialysis. Results: Doppler-derived LV MPI, and right ventricular MPI obtained by DTI were increased (p = 0.05) but the LV MPI obtained by DTI was unchanged after hemodialysis. There is a significant positive correlation between the Doppler-derived LV MPI difference and volume reduction (r = 0.38, p = 0.032). The heart rate difference was correlated with Doppler-derived LV MPI difference, and DTI derived right ventricular MPI difference (r = 0.38, p = 0.034; r = 0.48, p = 0.006, respectively). Whereas, DTI derived LV MPI difference was not correlated with heart rate difference. By the multivariate analysis, there was no correlation between Doppler-derived LV MPI difference with heart rate difference, and volume reduction. Right ventricular MPI difference correlated with heart rate difference (r = 0.41, p = 0.021) but not with volume reduction. Doppler-derived MPI is partially influenced by preload and heart rate changes. However, DTI derived LV MPI is not influenced by preload and heart rate changes.