Effects of IMAGENT on pulmonary hemodynamics and gas exchange in dogs.

Imagent is an IV injected contrast echocardiography agent designed to image the left ventricle after traversing the pulmonary circulation. We examined the effect of Imagent on pulmonary function by injecting either Imagent (n = 8) or equivalent volume of saline (n = 7) IV in randomly ordered 1, 8 and 16 mg/kg doses in dogs with preexisting pulmonary hypertension. We found that Imagent had no effects on cardiac output, pulmonary gas exchange, lung wet:dry ratio or static compliance. However, the 16 mg/kg dose of Imagent increased both pulmonary artery pressure (PAP) transiently by an average of 5.7 mmHg (p < 0.05) 2 to 3 min after injection and pulmonary vascular resistance (PVR) by 5.9 mmHg per l/min (p < 0.05) 4 min after injection before returning to preinjection levels. The lower doses of Imagent did not affect PAP or PVR. These results imply that the approved clinical dose of Imagent (0.125 mg/kg) will not affect pulmonary hemodynamics, gas exchange or mechanical properties in dogs with preexisting pulmonary hypertension.