Objective—To determine whether dobutamine stress
tests (DST) can be used to detect cardiac dysfunction
in dogs with early left ventricular dysfunction (ELVD)
induced by rapid right ventricular pacing (RRVP).
Animals—7 adult male Beagles.
Procedure—A pacemaker was surgically implanted
in each dog at the level of the right ventricular apex.
Electrocardiography, Doppler sphygmomanometry,
and Doppler echocardiography were performed
before and during a DST prior to activation of the
pacemaker and every 3 to 4 days during the period of
RRVP. Dobutamine stress tests were performed by
infusing dobutamine at incremental dosages ranging
from 12.5 to 42.5 µg/kg of body weight/min.
Results—Clinical signs of congestive heart failure
were not observed during the pacing period. However,
all dogs developed ELVD associated with significant
changes in values for most Doppler echocardiographic
variables obtained prior to DST. Adverse cardiac
effects were not detected during DST. Most Doppler
echocardiographic indices of cardiac function were significantly
altered in response to dobutamine infusion
during the pacing period, compared with prepacing values.
However, a dobutamine-induced 2-fold increase
in cardiac output was maintained.
Conclusions and Clinical Relevance—Dobutamine
stress tests can be safely performed in dogs with
experimentally induced ELVD. Dobutamine stress
tests may be a sensitive, noninvasive diagnostic
method, complementary to standard clinical examinations,
for detection of early cardiac dysfunction in
dogs asymptomatic for dilated cardiomyopathy. (Am J
Vet Res 2001;62:448–455)