Interaction between verapamil and contrast media in coronary arteriography: comparison of standard ionic and new nonionic media.

Coronary arteriography is frequently performed in patients receiving verapamil ther- apy. Since verapamil and contrast media both cause depression in electrophysiologic and contractile function of the heart and since both may exert these effects by actions on ionic calcium, the interaction of verapamil and intracoronary contrast media was assessed in 16 anesthetized dogs. Before verapamil, ionic contrast medium (Renografin 76, 3 ml) caused significant (p < .01) decreases in left ventricular peak systolic pressure, left ventricular dP/dt, extent of segment length shortening, and rate of change of segment length (dL/dt). The hemodynamic effects of verapamil and Renografin were additive, but the severity of the hemodynamic changes in response to Renografin in the presence of verapamil were not significantly different from those produced before verapamil. On the other hand, PR interval prolongation by Renografin 76 was significantly greater in the presence of verapamil (p < .001); most of the animals developed second-degree heart block in response to Renografin 76 in the presence of verapamil. Both before and in the presence of verapamil, Renografin 76 induced a similar decline in Na+ and Ca"+ levels and an increase in Na+/Ca"+ of coronary sinus blood. Nonionic contrast medium (iohexol) caused small but significant increases in peak dP/dt and dL/dt both before and in the presence of verapamil. This contrast medium caused no significant changes in the PR interval before or in the presence of verapamil. The changes in Na+, Ca" , and Na+/Ca+ + were significantly (p < .01) less marked than those caused by Renografin 76 and were not significantly different before or in the presence of verapamil. The major finding of this study is that the effect of ionic contrast media on atrioventricular conduction is markedly enhanced in the presence of verapamil. On the other hand, nonionic media cause no deleterious inotropic or dromotropic effects, either in the presence or absence of verapamil. Circulation 68, No. 3, 628-635, 1983. VERAPAMIL and other calcium antagonists were ini- tially used in the treatment of coronary arterial spasm and have subsequently been effective in the management of other forms of ischemic heart disease.1"2 Con- sequently, many patients are now undergoing coronary arteriography while being treated with calcium antagonists. In addition to a potent vasodilatory action, some antagonists have important cardiac effects. Verapamil, in particular, has actions on the heart.3 4 The cardiac effects and cellular mechanism involved in these ac-