The renal artery stenosis describes a single, but also occurring on both sides narrowing of the renal artery supplying (renal artery). Consequence of this narrowing may be a by the gold leaf effect (activation of the renin-angiotensin-aldosterone system) induced high blood pressure (hypertension).
Causes and frequency - renal artery stenosis
As a cause of hypertension, renal artery stenosis with approximately 1% is relatively rare. Causes of the renal artery stenosis include:
-Arteriosclerosis (most common cause with 60-90%, especially on the transition of the aorta to the A. localized renal)
-Fibromuscular dysplasia (10-30%, this change of connective tissue is the cause, especially in young patients, most likely in the middle third of localized renal artery)
-Arteritides, such as Takayasu Arteritis
-Other rare causes are: renal thrombosis, injury or an aneurysm of the A.
Pathophysiology (gold leaf effect) - renal artery stenosis
The pathophysiology of renal artery stenosis is based to a large extent in the so-called gold leaf effect. A reduction of the renal artery diameter to less than 40% cause a decrease in blood flow to the kidney. The kidney responds with an increased secretion of Renin, which leads to vasoconstriction (tight position of vessels) and an increased re-absorption of sodium and water via the Renin-angiotensin-aldosterone system. Result of both processes is the typical of the disease increase of in systemic blood pressure. The diseased kidney tried to improve their own restricted blood circulation, increases the pressure in the systemic circulation to pathological values however. This mechanism is named after the American pathologist Harry Goldblatt.
Clinic - renal artery stenosis
High blood pressure (particularly diastolic blood pressure value)
Reversed circadian rhythm in long-term blood pressure measurement
often rapid during development of high blood pressure
Blood pressure can not be or is difficult to set (> 2 drugs)
Diagnostics - renal artery stenosis
*History (atypical age, rapid progression, hypertensive emergencies in the history)
*Physical examination: blood pressure measurement (often diastolic hypertension), Stenosegeräusch in the *Area of the navel and / or flanks (in 30% using stethoscope audible)
*Classical testing in connection with high blood pressure
*Ultrasonography (duplex and color Doppler)
*Magnetic resonance imaging (MRI)
*Renogram
*Digital subtraction angiography
Therapy - renal artery stenosis
*Drug therapy: ACE-inhibitors combined with beta-blockers (but under close control). Are achieved so that no improvement, interventional and surgical procedures come into question. (In bilateral renal artery stenosis to a solitary kidney or the therapy, however, can lead to an ACE inhibitor for acute renal failure and is therefore not recommended.)
*Interventional therapy: Percutaneous transluminal angioplasty (PTA): 80% success rate, often with subsequent stent implantation.
*Surgical therapy: Aortorenale (anatomical) or extra-anatomic bypass surgery.