Renovascular hypertensionI15.00

Renovascular hypertension is a form of hypertension caused by reduced perfusion of one or both kidneys due to an obstruction in the flow in the supplying renal arteries (NAST) and activation of the renin-angiotensin system. Hemodynamically effective is a degree of stenosis from 65-75%.

Arteriosclerotic plaque formation with consecutive arteriosclerotic renal arteriostenosis (ANAST); is the most common form of renovascular hypertension, 75-80%; m>w; older age.

Fibromuscular stenosis; 20-25%, w>m; younger age.

Rare: arteritis(panarteritis nodosa, Takayasu arteritis); renal artery aneurysm; renal artery occlusion (thrombosis, emboli, dissection). Compression of the renal arteries from the outside (tumors, cysts, hydronephrosis).

0.2-0.5% of all forms of hypertension

Reduced blood supply to the kidneys (>60%) leads to gold-leaf hypertension (activation of the renin-angiotensin-aldosterone system) with increased release of renin from the juxtaglomerular cells of the renal parenchyma and ultimately to vasoconstriction and hypertension

The following findings indicate a moderate to high risk of renovascular hypertension:

• Diastolic hypertension develops abruptly in a patient < 30 or > 50 years
• New or previously stable hypertension worsens rapidly within 6 months
• Therapy resistance of hypertension in drug treatment with =/>3 different antihypertensive drugs of different antihypertensive classes.
• Occurrence of arterial hypertension in patients before the age of 25 and in patients >50 years of age
• Hypertension with confirmed arteriosclerosis (CHD, AVK, cerebrovascular disease)
• Unexpected stomach or flank pain
• Azotaemia of unclear genesis
• Acute increase in serum creatinine after taking an ACE inhibitor or an angiotensin II receptor blocker
• Hypertensive retinopathy grade III or IV
• Arterial occlusive diseases (AVK) of other organ systems.
• Abdominal flow sounds, young patient <30 years, with diastolic RR >110mm HG.

Colour Doppler method: the renal blood flow can be determined by duplex Doppler sonography. The method is a reliable non-invasive method for the determination of a significant stenosis (e.g. > 60%) in the main renal arteries. Sensitivity and specificity reach 90% when performed by an experienced examiner.

MRI angiography (Cave: use of gadolium; risk of nephrogenic systemic fibrosis)

Gold standard: intra-arterial digital subtraction angiography.

Percutaneous transluminal angioplasty (PTA):

In fibromuscular dysplasia (stenosis), the achievable results are better (in 70% of patients) than in patients with arteriosclerotic renal stenosis (ANAST).

For conservative therapy, the usual rules for the treatment of the causative renal disease apply. The treatment of hypertension goes in the direction of: lowering the extracellular fluid volume and the sodium pool (diet, saluretics). The endocrine disorders can be treated with hormone antagonists, e.g. Aldactone.

Percutaneous transluminal angioplasty (PTA) is recommended for most of the patients with renovascular hypertension. Stenting reduces the risk of restenosis; antiplatelet medications (aspirin, clopidogrel) are given subsequently.

Bypass (saphenous vein) is recommended only when significant extension of disease, including into the lateral branches of the renal artery, makes it technically impossible to perform PTA. Sometimes complete surgical revascularization requires microvascular techniques that can only be performed ex vivo with autografting of the kidney. The cure rate is 90% in patients suitable for this; surgical mortality is < 1%.

In arteriosclerotic renal artery stenosis (ANAST), blood pressure normalization can be achieved in only about 20% of patients (fixed nephrogenic hypertension).

1. Cooper CJ et al (2014) Stenting and medical therapy for atherosclerotic renal artery stenosis. N Engl J Med 370:13-