Pre-operative renal function and selective renal vein renin levels as markers of favourable outcome in renovascular hypertension
Objective: To evaluate factors that affect outcome following revascularization in patients with renovascular hypertension.Methods: This study was conducted at the Aga Khan University Hospital. It included all the patients diagnosed to have Renovascular hypertension confirmed by renal angiography between July 1996 to September 2000. Using ANOVA (Analysis of variance) and paired-sample t-test, several preoperative factors were evaluated for their ability to predict postoperative improvement of blood pressure and renal function. For descriptive purpose patients were divided into cured, improved and failure groups.Results: Of the total 15 patients, 9 were males and 6 were females. Before the surgical procedure, 13 patients were on 3 or more antihypertensive drugs. Eleven patients received vein grafts, three patients had PTFE (polytetraflouroethyline) grafts while one patient underwent angioplasty and stenting. The patients had a median follow-up period of nine months with a range of 2 to 84 months. Five were completely cured, as they became normotensive without antihypertensive therapy after operation, whereas four showed marked improvement in BP control postoperatively, requiring two antihypertensive drugs. Six patients showed no improvement requiring 3 or more drugs. Extended cure or improvement of renovascular hypertension was achieved in nine patients. Normal preoperative serum creatinine level, high preoperative unstimulated peripheral renin levels and renal vein renin ratio of at least 1.75:1 were the most significant predictive factors for favorable outcome.CONCLUSION: This study confirms the long term effectiveness and safety of renovascular reconstruction in the relief of severe hypertension. The results further suggest that normal preoperative renal function, high renal vein renin ratio and high preoperative unstimulated peripheral renin levels are associated with the most favourable postoperative outcome (p <0.01). Preoperative severity and duration of hypertension and degree of disparity in kidney sizes do not affect the overall results in terms of postoperative improvement in renal function and blood pressure control (p=0.734).