Predictive value of exercise renography for presurgical evaluation of nephrogenic hypertension.

Functional omicron-iodohippurate scintigrams were obtained in 18 hypertensive patients. Each patient was examined in the prone position and during exercise. An exercise-induced transient, bilateral, hippurate transport disturbance was sought as an expression of an exercise-mediated cortical perfusion abnormality. The study sought to test the hypothesis that patients who present evidence for an exercise-induced renal perfusion disturbance would have stabilized hypertension that was no longer surgically curable because of morphological changes of the peripheral vasculature. All 18 patients continued on to therapy: 13 proceeded to renovascular reconstructive surgery, 2 had a unilateral nephrectomy, and 3 were treated with percutaneous transluminal renal angioplasty. During preoperative exercise renography, evidence of bilateral renal dysfunction developed in 10 of 18 hypertensive patients during ergometric stress (abnormal exercise response). Following surgical therapy nine of these patients with abnormal exercise scintigrams continued to have hypertensive disease, while one patient was cured. The exercise renograms of eight hypertensive patients were not influenced by the exercise protocol, and operation cured seven of these eight patients. The results suggest that an accentuated vascular response to exercise occurs in the maintenance phase of renovascular hypertension, a disturbance not observed while the hypertension is curable by surgical therapy.