Dynamic intraventricular obstruction during dobutamine stress echocardiography. A new observation.

BACKGROUND: The implications of hypotension occurring during dobutamine stress echocardiography have not been elucidated. We observed in some patients that hyperdynamic left ventricular function developed during dobutamine stress echocardiography and hypothesized that intracavitary obstruction was occurring and might account for hypotension in some patients. METHODS AND RESULTS: Fifty-seven consecutive patients undergoing dobutamine stress echocardiography underwent pulsed-wave and continuous-wave Doppler examination of the left ventricular cavity at rest and at peak dobutamine infusion. The development of an intraventricular gradient with dobutamine stress was defined as a late-peaking left ventricular Doppler velocity profile that exceeded basal velocity by at least 1 m/sec. During dobutamine stress testing, left ventricular outflow velocity or intracavitary velocity increased in all patients. Obstruction occurred in 12 patients (21%, group 1). Group 2 was the remaining 45 patients. Peak velocities in group 1 ranged from 2.0 to 5.0 m/sec (mean, 3.5 m/sec), and the mean increase from velocity at rest was 2.3 m/sec. The mean change in systolic blood pressure was significantly lower in patients in group 1 (-15 versus 4 mm Hg, p = 0.02). When the 18 patients with an ischemic response to stress testing (evidenced by new or worsening wall motion abnormalities) were excluded from analysis, systolic blood pressure response was still significantly different for the two groups (-19 versus 2 mm Hg, p = 0.03). CONCLUSIONS: Dynamic left ventricular obstruction is a new observation; it may develop frequently in patients undergoing dobutamine stress echocardiography. Obstruction rather than ischemia may explain a decrease in blood pressure during dobutamine stress echocardiography.