Renal artery stenosis
Definition
The renal artery stenosis is a constriction of the artery that provides the kidney- that can also occur on both sides- caused by arteriosclerosis or e.g. by a change of the connective tissue (fibromuscular dysplasia). This causes a reduction of the blood flow to the kidney. The reaction of the kidney is an increased production of the hormone (Renin) which raises the blood pressure by difficult mechanisms. As a result, the sickened kidney tries to improve circulation of the blood on its own but by doing so it increases the pressure of the greater circulation up to pathological values. The consequence of this constriction will be a difficult or not fine-tuneable hypertension.
However, the renal artery stenosis causes in very rare cases high blood pressure (1%).
Symptoms
There will be a higher blood pressure especially an increase of the diastolic blood pressure value (2. value). Often there is also no rhythm of day and night anymore. Noticeable is the quick increase of the blood pressure value and the slow or non-existing reaction to the medication with blood pressure preparation.
Diagnosis
In most cases the kidney artery can be illustrated and evaluated free of side effects by an ultra-sound examination (duplex- and colour-double-sonography). If there is a serious suspicion of a renal artery stenosis the diagnosis can be completed with a kidney function szintigraphy as well as a nuclear spin tomography. In case the suspicion can be confirmed or a therapy will be necessary the kidney artery will be illustrated with a contrast medium within a X-ray examination (angiography, DSA).
Therapy
In such cases there is no need for a therapy. But if there is a need for therapy nowadays the narrowed kidney arteries are widened by a catheter treatment with a balloon catheter or a shunt. A removal by surgery is also possible but is only applied in rare cases.