The pathophysiology of renovascular hypertension.

Renovascular hypertension, comprising a small percentage of the total hypertensive population, stands out as remarkably important, being the most common cause of surgically correctable hypertension. Its precise diagnosis can be accomplished by judicious application of recently available sophisticated laboratory methods and correct prediction of curability is now possible. Careful selection of cases among the vast numbers of hypertensives by routine screening procedures is essential. The selected few deserve more complete studies including bilateral renal vein renin measurements. Rapid sequence pyelography, split function studies, radioisotope renorgram, and renal arteriography accurately define the presence of a significant structural abnormality involving the renal circulation on either side. Significant bilateral renal vein plasma renin differential, done under appropriate conditions of volume depletion and upright posture, in the absence of interference by concurrent antihypertensive drug therapy, establishes a causal relationship between the structural abnormality and the high blood pressure. A thorough knowledge of the normal physiology of the renin-angiotensin-aldosterone system and its inappropriate response in renovascular hypertension and other related clinical conditions is clearly necessary if one is to plan diagnostic studies intelligently and interpret the results correctly.