ABSTRACT
Tissue Doppler imaging (TDI) is effective in assessing right ventricular (RV) function, but the relationship between invasive measurements and RV-TDI remains unclear. We investigated the RV systolic function by using the TDI-derived systolic myocardial (Sa) velocity and myocardial performance index (MPI). Beagles (n = 7) were anesthetized in the right lateral recumbent position. A 3.5-Fr micromanometer-tipped catheter was placed in the RV to determine the hemodynamic changes. Dobutamine (5.0 and 10 microg.kg(-1).min(-1)) and esmolol (50 and 100 microg.kg(-1).min(-1)) were infused intravenously. Pulsed Doppler (PD) and TDI measurements were performed in the apical four-chamber view. Compared with baseline, the PD-MPI decreased significantly with the dobutamine infusion at 5 microg.kg(-1).min(-1) (P < 0.05). Both dobutamine infusions significantly decreased the TDI-MPI (P < 0.01, P < 0.05). Esmolol increased the PD- and TDI-MPI but not significantly. Dobutamine significantly increased the Sa velocity (both P < 0.001), whereas esmolol had no effect. The Sa velocity was strongly correlated with the peak positive derivative of the RV pressure (+dP/dt; r = 0.93). The negative correlation between the +dP/dt and TDI-MPI (r = -086) was greater that with the PD-MPI (r = -0.54). Stepwise regression analysis showed that the Sa velocity and PD-derived isovolumic contraction time were identified to predict the +dP/dt (r = 0.94, r(2) = 0.89; P < 0.001). We determined that the systolic myocardial velocity and TDI-MPI were strongly correlated with the RV contractility. These results suggest that the TDI-derived systolic myocardial velocity and MPI predict RV systolic function.
