EFFECTS OF CONTRAST-MEDIA ON CORONARY HEMODYNAMICS AND MYOCARDIAL-METABOLISM

RATIONALE AND OBJECTIVES. This study was designed to compare the effec ts of ionic contrast medium (CM), Renografin-76 (R76), and nonionic CM , Omnipaque-350 (OM350), on coronary hemodynamics and myocardial metab olism. METHODS. In 10 open-chest, atrial-paced dogs, 4 mi of R76 and O M350 were injected into the left anterior descending coronary artery. Coronary blood flow (CBF), myocardial oxygen consumption (MVO(2)), lac tate extraction (LE), left ventricular (LV) dp/dt, and aortic systolic pressure (AOP) were measured. RESULTS. The maximal CBF changes caused by OM350 and R76 were 23.7 +/- 3.3 mL/minute and 18.3 +/- 3.3 mL/minu te (NS), respectively. OM350 produced an increase in LV dp/dt by 378 /- 85 mm Hg/second, which was different from -244 +/- 65 mm Hg/second by R76 (P <.05). The changes in MVO(2) and LE after OM350 injection we re 2.6 +/- 0.6 mL/minute and 10.2 +/- 5 mu M/minute, respectively; tho se were different from -0.1 +/- 0.4 mL/minute, and -7.7 +/- 5.1 mu M/m inute after R76 injection (P <.05). CONCLUSION. Although both agents i ncreased CBF, they appeared to act by different mechanisms. That a dir ect coronary vasodilator effect is the main action of R76 on coronary vascular response is suggested by decreasing myocardial contractility and oxygen consumption. However, OM350, by enhancing both parameters, may augment CBF at least in part by autoregulation.