Sodium effects on the fibrillatory propensity of non-ionic contrast media
Piao, Z.E.; Murdock, D.K.; Hwang, M.H.; Wallock, M.; Raymond, R.M.; Scanlon, P.J.
Chinese Medical Journal 101(2): 117-124
1988
ISSN/ISBN: 0366-6999 PMID: 3136976 Document Number: 319075
Removing sodium from standard ionic contrast media markedly increases the incidence of ventricular fibrillation in patients undergoing coronary angiography. Newer nonionic contrast media, Iopamidol (IOP), Iohexol (IOH) and Ioversol (IOV), contain only trace amounts of sodium. To determine whether sodium influences the fibrillatory propensity of nonionic contrast media, we measured the prolongation in QT interval and performed programmed electrical stimulation with 1, 2 and 3 ventricular extra stimuli in 40 dogs during 4 ml intracoronary injections of IOP, IOH and IOV. Solutions of each contrast media with added NaCl at concentrations of 0.225%, 0.45% and 0.9% were compared to stock contrast media. The addition of NaCl markedly increased the amount of QT interval prolongation produced by each contrast media. With IOP, the amount of QT interval prolongation was 40.+-.11 msec with standard IOP but was 58.+-.11 msec with 0.225% NaCl/IOP, 84.+-.17 msec with 0.45% NaCl/IOP, and 132.+-.42 msec with 0.9% NaCl/IOP (P < 0.001). Similar results were seen with IOH and IOV. Ventricular fibrillation was difficult to induce with standard IOP, IOH and IOV (even with 3 extra stimuli), but became progressively easier to induce when NaCl was added. Three extra stimuli produced ventricular fibrillation in 0 of 11 dogs with standard IOP, 0 of 11 with 0.225% NaCl/IOP, 3 of 11 with 0.45% NaCl/IOP and 8 of 11 with 0.9% SaCl/IOP (P < 0.001). Similar results were observed with IOH and IOV. Unlike NaCl, the addition of choline chloride or dextrose did not increase ventricular fibrillation or QT interval prolongation. It is concluded that standard preparations of nonionic contrast media have a very low fibrillatory propensity. The addition of NaCl increases the amount of QT interval prolongation making ventricular fibrillation easier to induce. The detrimental effects of added NaCl are due to the addition of the Na+ rather than the CI-, an osmotic effect.