Abstract
Objective—To evaluate tissue Doppler imaging (TDI) of the left ventricular (LV) free wall (FW) and ventricular septum (VS) as an indicator of LV systolic function in dogs.
Animals—7 healthy Beagles.
Procedures—Doses of dobutamine (5 and 10 μg/kg/min) and esmolol (50 and 100 μg/kg/min) were infused into the LV of each dog. With each dose, heart rate; myocardial performance index (MPI); transmitral inflow and ejection time (determined via pulsed-wave Doppler [PWD] echocardiography); and FW and VS velocities of the mitral valve annulus (determined via TDI during systole [S’], early diastole [E’], and late diastole [A’]) were assessed.
Results—With each dose, dobutamine significantly increased heart rate and the first derivatives of LV pressure (+dP/dt and –dP/dt), whereas esmolol significantly decreased the +dP/dt and –dP/dt values, compared with baseline. Esmolol (100 μg/kg/min) significantly decreased the VS-TDI–derived S’ velocity and FW-TDI–derived E’ velocity; dobutamine significantly increased transmitral inflow and TDI velocities. Regression coefficient between VS-TDI–derived S’ velocity and +dP/dt was higher than that between FW-TDI–derived S’ velocity and +dP/dt. Compared with baseline, the PWD- and VS-TDI–derived MPI were significantly decreased by dobutamine and significantly increased by esmolol at each dose. Values of FW-TDI–derived MPI were higher than values derived via the other techniques. Correlation between +dP/dt and VS-TDI–derived MPI was greater than that between +dP/dt and FW-TDI– or PWD-derived MPI.
Conclusions and Clinical Relevance—In healthy dogs, the VS-TDI–derived S’ velocity and MPI appear to be reliable assessments for evaluating LV systolic function.
