CONTRAST-MEDIUM-INDUCED VENTRICULAR-FIBRILLATION - ARRHYTHMOGENIC MECHANISMS AND THE ROLE OF ANTIARRHYTHMIC DRUGS IN DOGS

Rationale and Objectives. Small electrolyte additions re, a nonionic c ontrast medium reduce the risk of ventricular fibrillation (VF) during wedged catheter injection of a contrast medium. The current study was designed to further investigate contrast-medium-induced VF by studyin g the effect of pretreatment with different antiarrhythmic drugs. Meth ods. During a simulated wedged catheter situation, iohexol was injecte d into the anterior descending branch of the left coronary artery in f ive open-chest, anesthetized dogs pretreated with lidocaine, propranol ol. amiodarone, almokalant, or verapamil. Results. Wedging the cathete r far 60 sec did not induce VF. However. all 15 wedged catheter inject ions with iohexol induced VF within 28 sec (19 +/- 1 [mean +/- standar d error of the mean]) despite pretreatment with antiarrhythmic drugs. Prior to VF. conduction was slowed and monophasic action potential dur ation lengthened in the contrast-medium-perfused myocardium. although no significant changes occurred in the control area. Conclusion. The c ombination of catheter wedging and long-lasting contrast medium inject ion has a high risk of causing VF. Although adding a small amount of e lectrolytes to nonionic contrast media can reduce the risk of VF, anti arrhythmic drug therapy may not have a protective effect.