Doppler echocardiographic study of left and right ventricular function during dobutamine stress testing in conscious healthy dogs

Objective-To evaluate left and right ventricular filling and ejection perfo rmances by use of Doppler echocardiography in healthy, conscious dogs submi tted to dobutamine stress testing. Animals-10 unsedated, healthy adult Beagles. Procedure-Doppler echocardiography was performed during cardiac stress test ing on each dog twice at 24-hour intervals. Dobutamine was infused in 10 mu g/kg of body weight/min incremental dosages, from 12.5 to 42.5 mu g/kg/min . Duration of each step was 15 minutes. Doppler measurements were recorded at baseline and at each stage of dobutamine infusion, whereas aortic diamet er was measured at baseline and at peak dosage by use of two-dimensional ec hocardiography. Results-Dobutamine infusion induced a significant increase in velocity lime integrals and in peak flow velocities at the aortic, pulmonic, mitral, and tricuspid valves, Acceleration time-to-deceleration time ratio at the aort ic wave also was increased significantly. On the other hand, ejection time, acceleration lime, and deceleration time at the aortic and pulmonic valves and peak flow velocity of the E wave-to-peak flow velocity of the A wave r atio at the mitral and tricuspid valves decreased significantly during the test. The acceleration time-to-deceleration time ratio at the pulmonic wave was unchanged. A significant, progressive increase in cardiac index also w as observed during dobutamine infusion, with a maximal increase of 104% fro m baseline. This was mediated initially by an increase in stroke index and, at higher dosages, by an increase in heart rate. Conclusions and Clinical Relevance-Doppler echocardiography performed durin g dobutamine stress testing may be a reliable method of assessing myocardia l function in dogs with cardiovascular disease.