CARDIAC ELECTROPHYSIOLOGY, ARRHYTHMOGENIC MECHANISMS AND ROENTGEN CONTRAST-MEDIA

Contrast media (CM) affect normal cardiac electrophysiology when injec ted into the coronary arteries. High-osmolality CM cause more pronounc ed electrophysiological effects than do low-osmolality CM. Further, bo th high- and low-osmolality ionic CM have more pronounced effects than the nonionic CM. The CM-induced electrophysiological effects involve regional disturbances of depolarization and repolarization, thereby ca using disturbances of impulse conduction as well as dispersion of refr actoriness. Recent experimental studies have demonstrated that the add ition of sodium or a balanced electrolyte supplement to nonionic CM re duces the risk of ventricular fibrillation (VF), particularly when the CM is injected in a wedged catheter situation. The reduced risk of VF may be due to the small and transient lengthening of repolarization s een in the CM-perfused area of the myocardium. Iodixanol, which is an isotonic nonionic dimer supplemented with NaCl and CaCl2, is as well t olerated as iohexol during free coronary flow. However, when flow is r estricted, such as when CM is injected through a wedged catheter, the risk of VF is less with iodixanol than with iopamidol, iohexol and iox aglate.