urografin-76 and Hypertension--Pulmonary

Clinical studies have shown pulmonary and right ventricular hypertension to be important factors increasing the risk to patients during pulmonary angiography. This experiment was undertaken to define the hemodynamic changes induced by the administration of contrast material into the pulmonary arteries of dogs with embolic pulmonary hypertension, and to compare the effects of ionic and nonionic agents. Ten closed-chest dogs under light halothan anesthesia were subjected to pulmonary embolization with sephadex microspheres until severe pulmonary hypertension occurred and the cardiac output decreased to 50%-60% of the pre-embolization baseline. Intra-pulmonary injections of contrast material were performed in eight animals while hemodynamic indices were measured. Sodium methylglucamine diatrizoate induced severe, transient, hypotension associated with a large decrease in systemic vascular resistance and little change in the cardiac output. Hypotension is especially undesirable in the presence of pulmonary hypertension because it worsens the preexisting coronary ischemia and compromised right ventricular function. No elevation in mean pulmonary artery pressure was seen, and pulmonary vascular resistance decreased. Iohexol induced milder effects, perhaps because it exerts a less severe systemic vasodilatory effect and is not a negative inotrope. These findings suggest iohexol may be safer in the high risk patient, however, these data may not be directly applied to unanesthetized humans.

Topics: Acute Disease; Animals; Contrast Media; Diatrizoate; Diatrizoate Meglumine; Dogs; Drug Combinations; Hemodynamics; Hypertension, Pulmonary; Injections, Intra-Arterial; Iohexol; Pulmonary Artery; Radiography

The cardiovascular response produced during pulmonary angiography performed with the standard ionic agent diatrizoate (Renografin 76) and a new non-ionic agent iopamidol was compared. Nine dogs were evaluated while ventilated on room air and on 10% O2 which significantly elevated pulmonary arterial pressure. Iopamidol produced similar changes in mean aortic and pulmonary arterial pressures compared with normal saline (less than 20% change). Renografin 76, however, produced a significantly greater elevation in mean pulmonary arterial pressure (a 41% increase) and depression in mean aortic pressure (a 40% reduction) than either saline or iopamidol (p less than 0.01). These results were similar for dogs being ventilated with room air and oxygen. The results indicate that iopamidol should be better tolerated and therefore a safer contrast agent for pulmonary angiography than diatrizoate.

Topics: Animals; Aorta; Blood Pressure; Cardiovascular System; Contrast Media; Coronary Circulation; Diatrizoate; Diatrizoate Meglumine; Dogs; Drug Combinations; Heart Rate; Hypertension, Pulmonary; Iopamidol; Iothalamic Acid; Pulmonary Circulation; Radiography