Preliminary Results with Aminophylline as Smooth-Muscle Relaxant in Percutaneous Renal Surgery

Aminophylline a methylxanthine and phosphodiesterase inhibitor, can relax smooth muscle in the upper urinary tract. A 3-ml amount of 0.5% aminophylline was applied topically to the intrarenal collecting system of 11 patients in whom access to a stone was limited by ureteral or infundibular spasm (three patients) or in whom spasm of the ureteropelvic junction could not be differentiated from stricture (eight patients). This facilitated access in two of the three patients with caliceal stones and differentiated spasm of the ureteropelvic junction from stricture associated with stones in six patients. In two cases of apparent ureteropelvic junction occlusion, one following endopyelotomy and one following dismembered pyeloplasty, topical aminophylline failed to demonstrate that the junction was indeed patent. Methylxanthine-induced smooth-muscle relaxation may be of value in differentiating spasm secondary to a stone from ureteral scarring and may improve access to peripherally placed renal stones.