Physiologic response to dobutamine infusion during cardiac stress testing of dogs.

OBJECTIVE

To evaluate response of various cardiovascular variables after administration of incremental doses of dobutamine in healthy conscious dogs, using standardized dobutamine stress echocardiography (DSE).

ANIMALS

8 healthy dogs.

PROCEDURE

A DSE was performed twice on each dog within 24 hours. Dobutamine was infused at a rate of 12.5 to 42.5 microg/kg/min, using incremental increases of 10 microg/kg/min. Doppler sphygmomanometry, electrocardiography, and echocardiography were performed. Left ventricular size, global ventricular performance, and left ventricular systolic myocardial function were measured by means of echocardiography.

RESULTS

At the highest dosage, dobutamine induced an increase of 20+/-3% and 109+/-12% in systolic blood pressure and cardiac index, respectively. The latter was associated with a significant increase in heart rate and stroke index. Fractional shortening of the left ventricle, fractional thickening of the left ventricular free wall and interventricular septum, ejection fraction, and mean velocity of fiber shortening had a progressive and significant increase during dobutamine infusion. Preejection period and left ventricular ejection time had a progressive and significative decrease during the stress test.

CONCLUSIONS

The technique used was feasable, safe, and repeatable in healthy conscious dogs. Control values were determined.

CLINICAL RELEVANCE

Data for these healthy dogs might be useful for comparison with results obtained from dogs with known or suspected cardiovascular disease.