A decrease in blood pressure following pyelolithotomy but not extracorporeal lithotripsy

Our aim was to evaluate the hypothesis that relief of renal obstruction lowers the arterial blood pressure if the procedure of stone removal does not injure the kidney itself. Sixty patients with unilateral renal stone were evaluated at baseline and 3 months after electrical shockwave lithotripsy (ESWL, n=30) or Gil-Vernet intrasinus pyelolithotomy (n=30). Blood pressures were measured noninvasively and renal vascular resistances were obtained from radionuclide measurements of renal blood flow. At baseline, the renal vascular resistance of the obstructed kidney was 2 and 2.5 times greater than of the unobstructed kidney in the ESWL and pyelolithotomy groups, respectively. After 3 months in operated patients, the blood pressure decreased (from 87 to 81 mm Hg, P=0.002, in case of diastolic, and from 140 to 132 mm Hg, P < 0.0001, in case of systolic pressure), while the vascular resistances of both kidneys were equal and normal. In contrast, in the ESWL group the blood pressures and vascular resistances of the treated kidney did not differ from the baseline values. Surgical relief of renal obstruction chronically lowers the arterial blood pressure, possibly by normalizing the renal vascular resistance. ESWL does not change the blood pressure or renal vascular resistance, which could reflect a balance between the relief of obstruction and kidney lesions induced by shock waves.