Cyanotic nephropathy and use of non-ionic contrast agents during cardiac catherization in patients with cyanotic congenital heart disease.

Background: Chronic cyanosis with its associated rheologic changes is a known risk factor for glomerular nephropathy. Therefore, contrast-induced nephrotoxicity should be an important consideration for angiographers comparable to diabetics. On the other hand, progressions in diagnostic and interventional techniques have led to expanded indications and a more widespread use of x-ray contrast agents. The aim of this study was to investigate the risk of contrast-induced nephropathy in the small group of patients with cyanotic heart disease prior to surgical repair.
Methods: We investigated 23 cyanotic patients with an oxygen saturation of 82 (50-92)%, age 25 (5-63) years, and 13 control subjects with atrial septal defect, age 37 (20-66) years. Blood viscosity was measured before and after cardiac catherization. Renal damage was evaluated by selective analysis of urinary proteins and enzymes.
Results: Before cardiac catheterization, 48% of the cyanotic patients had a moderate glomerulopathy. Cardiac catherization was performed with 3.0 (1.2-6.8) mls/kg non ionic contrast medium. Only one of the 23 patients (4.3%) with normal urinary analysis before cardiac catheterization showed renal damage, which involved tubular and glomerular function. Elevated blood viscosity in cyanotic patients was slightly reduced by the contrast. None of the acyanotic controls had contrast-induced nephropathy.
Conclusions: The use of non-ionic contrast medium does not worsen cyanotic glomerulopathy. This finding may be due to the reduction of blood viscosity by the application of the contrast medium. The finding of contrast-induced nephropathy in one patient underlines the importance of monitoring renal function after cardiac catheterization.