Renal artery stenosis medical therapy
Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1]; Associate Editor-In-Chief: Shivam Singla, M.D.[2]
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Overview
Patients with Renal artery stenosis require the widespread use of intensive medical therapy. The drugs responsible for the management of renal artery stenosis are ACE inhibitors or ARB's. These drugs inhibit the sympathetic and renin-angiotensin system resulting in controlling hypertension. In patients with bilateral renal artery stenosis, there is an associated decrease in renal function after using the ACE inhibitors and ARB, but it is neither a sensitive nor specific finding. Aggressive statin use, optimal glycemic regulation, and therapy for smoking abstinence are of vital significance. Other modalities used are renal artery revascularization, Percutaneous transluminal renal angioplasty, Renal artery stenting, brachytherapy and cutting balloon atherotomy, and surgery in complicated and nonresponding cases. Although morbidity and mortality are high in surgery vs stenting.
Treatment
Medical Therapy
The patients with Renal artery stenosis requires the wide spread use of intensive medical therapy. The drugs responsible for the management of renal artery stenosis are ACE inhibitors or ARB's. These drugs inhibit the sympathetic and renin-angiotensin system resulting in controlling the hypertension. In patients with bilateral renal artery stenosis there is associated decrease in the renal function after using the ACE inhibitors and ARB, but it is neither sensitive nor specific finding. Aggressive statin use, optimal glycemic regulation, and therapy for smoking abstinence are of vital significance.
Aggressive use of statins, optimal glycemic control, and smoking cessation counseling are of paramount importance. The results of various medical regimens on the treatment of ARAS-related hypertension were not analyzed in a randomized clinical trial because such patients frequently have refractory hypertension and need multiple antihypertensive medicines. Medical therapy is preferred to revascularization in patients with ARAS and progressive renal disease (i.e. chronic renal dysfunction, proteinuria[>1 g/d]), diffuse intrarenal vascular disease, and renal atrophy.
Renal Artery Revascularization
It is less obvious and much more contentious whether patients with ARAS and hypertension would undergo surgical revascularization. According to studies patients with extreme ostial renal artery stenosis who have been successfully revascularized percutaneously do not necessarily have therapeutic benefits.
The ACC/AHA description of RAS is as follows:
(1) visually approximate stenosis of 50 percent to 70 percent diameter with a translational peak gradient of at least 20 mm Hg or a mean gradient of at least 10 mm Hg
(2) angiographic stenosis of at least 70 percent diameter
(3) greater than 70% stenosis according to the measurement by intravascular ultrasounds.
Present ACC/AHA recommendations do not however, include these steps and prescribe revascularization of ARAS only when it is associated with certain medical conditions mentioned as follows:
1) Asymptomatic stenosis: Percutaneous revascularization can be considered for the treatment of:
- An asymptomatic bilateral
- Solitary viable kidney with hemodynamically significant ARAS (class Jib, degree of proof II.OF.I C),.
- The efficacy of percutaneous or asymptomatic unilateral hemodynamically significant ARAS in a viable kidney is not well known and clinically unrecognized (class 11b, LOE C)
2) Hypertension
- Percutaneous revascularization is used for the patients with
- Hemodynamically significant renal artery stenosis along with accelerated hypertension
- Malignant hypertension
- Resistant hypertension
- In cases with hypertension and associated unilateral small kidney.
3) Preservation of renal function
- Percutaneous revascularization is helpful in patients with ARAS + Chronic progressive kidney disease with bilateral renal artery stenosis or solitary functioning kidney. (Class IIa, LOE B)
- Also considered significant in patients with RAS and chronic renal insufficiency with unilateral renal artery stenosis. (Class IIb, LOE C)
4) Effects of renal artery stenosis on Congestive heart failure and unstable angina: Percutaneous revascularization is considered in patients with
- RAS + Recurrent congestive heart failure or sudden unexplained pulmonary edema. (Class I, LOE B)
- Patients with hemodynamically significant RAS along with unstable angina (Class IIa, LOE B)
Percutaneous Transluminal Renal Angioplasty
Dutch Renal Artery Stenosis Intervention Cooperative (DRASTIC) did a study to compare the effects of drug treatment and PTRA.
Despite the authors' claim that PTRA offered "little benefit" in comparison to pharmacological treatments, patients in the PTRA community were less likely over 12 months of follow-up to experience regression in their blood pressure regulation or renal artery occlusion.
Renal Artery Stenting
- Renal artery stenting is considered to be the safe and one of the effective procedures involved in the management of renal artery stenosis.
- In a meta analysis conducted in the past showed promising results with stent placement along with higher success rates (98% vs 77%) and less risk of restenosis (17% vs 26%) as compare to what with PTRA.
- A randomized analysis revealed the effectiveness of renal stenting versus PTRA for rapid procedural success (88% versus 57%) and lower rates of restenosis (14 percent vs 48 percent , respectively) 70.
- In patients with ARAS and progressive renal insufficiency, other studies have indicated recovery or stability of renal function after unilateral or bilateral renal stenting..71,72
- After therapy with at least 2 antihypertensive drugs, in patients with ARAS and hypertension (blood pressure >140/90 mm Hg), renal stenting resulted in a 20 mm Hg decrease in systolic blood pressure and 1 less antihypertensive drug.73
- The ASTRAL ( Angioplasty and Stenting for Renal Artery Lesions) and the STAR (Atherosclerotic Renal Artery Stenosis and Impaired Renal Function) trials, CORAL (Cardiovascular Outcomes in Renal Atherosclerotic Lesions) are the major trials conducted for analyzing the importance of renal artery stenting in the management of renal artery stenosis.
Additional Interventional Procedures
While brachytherapy and cutting balloon atherotomy for renal artery in-stent restenosis have been used successfully, long-term findings are uncertain.
Coronary drug-eluting stent usage has also been identified for narrow renal arteries, but there is a shortage of well-designed trials to evaluate the adequate eluting drug dosage for this vessel
The major drug eluting stent is just 3.5 mm in diameter, which is an inappropriate dimension for stenting of a renal artery (with a normal diameter of 4-7 mm). In order to trap atherosclerotic debris and avoid distal embolization during renal stenting, 80 distal embolic safety systems have also been used, which may help maintain renal function.
Surgery
Surgical revascularization is one of the effective modality involved in the management of Renal artery stenosis. But the morbidity and mortality are higher with surgery as compared to stenting.
In one of the few trials comparing ostial ARAS surgical revascularization with percutaneous revascularization, Balzer et al81 observed no substantial difference in long-term morbidity or mortality, and no significant difference in blood pressure reduction.
These findings show that surgical revascularization of ostial ARAS could be at least equal to PTRA.
References