BOSTON, MASSACHUSETTS. CT (CAT) scanning often involves the prior injection of a contrast agent (drug) in order to get sharper "pictures". It is known that contrast agents can cause acute renal failure, particularly in patients who already have impaired kidney function (renal insufficiency). Cardiac catheterization (angiocardiography), a diagnostic procedure where a catheter is threaded through a major vein into the heart, also makes use of contrast agents in order to obtain an enhanced image of the heart. This procedure uses larger amounts of contrast agents than does CT scanning and therefore involves a substantially greater risk of acute or permanent kidney damage.
Researchers at Tufts University School of Medicine now report that kidney damage (nephropathy) after cardiac catheterization can largely be avoided if patients are given n-acetylcysteine (NAC) prior to and after the procedure. NAC, a precursor of the antioxidant glutathione, is available in health food stores. The double-blind, placebo-controlled clinical trial involved 54 patients with stable chronic renal insufficiency who were scheduled for cardiac catheterization. The patients were randomized to receive four doses of either 600 mg NAC diluted in 30 mg of ginger ale or 3 ml of saline solution diluted in ginger ale (placebo). One dose was given before and three after catheterization. Acute kidney damage (nephropathy), defined as a 25 per cent or greater increase in creatinine was observed in 8 per cent of the patients who had been given NAC and in 45 per cent of patients who had been given a placebo. The researchers conclude that NAC should routinely be given to patients with chronic renal insufficiency prior to cardiac catheterization in order to prevent further kidney damage during the procedure.
Diaz-Sandoval, Larry J., et al. Acetylcysteine to prevent angiography-related renal tissue injury (The APART Trial), American Journal of Cardiology, Vol. 89, February 1, 2002, pp. 356-58