Diagnosis
Especially in slim people, renal artery stenosis can be heard with the stethoscope: During the physical examination by the doctor, a flow noise over the abdomen and flanks is noticeable, which suggests changes in the renal vessels. The detection of this vascular change is initially carried out with an ultrasound examination of the kidneys and their vessels. The flow velocity of the blood through the vessels and the vessel width can be measured.
If a significant constriction with a low flow rate can be detected, a therapy becomes necessary. This procedure does not use X-rays and is particularly gentle on the patient. A very precise image of the renal vessels can be obtained with a magnetic resonance tomography examination, a so-called MRI angiography. The patient receives a contrast medium through the vein, with the help of which the renal vessels can be made clearly visible.
Therapy
For the therapy of renal artery stenosis, catheter procedures (therapeutic tubes) and surgical procedures as well as drug treatment options are available: Using a catheter, a balloon can be pushed up to the renal artery in a similar way to a cardiac catheter for narrowed or blocked coronary arteries. This balloon is expanded to widen the vessel: The artery becomes continuous again. If necessary, a stent, a vascular support, can be inserted.
The stent is designed to keep the vessel open. This procedure is performed when drug treatment of high blood pressure does not result in sufficient pressure reduction or when the artery is blocked to more than 70% and therefore an improvement of the blood pressure situation cannot be expected. If the catheter treatment is not successful, a therapy with several antihypertensive drugs is necessary to normalize high blood pressure in the patient. Less frequently, surgery is necessary in which the narrowed vessel section must be removed and, if necessary, bridged with a vascular prosthesis.
Prognosis
The balloon dilatation of the narrowed renal vessel is of particular benefit in the fibromuscular form of renal artery stenosis. Normalization of blood pressure can be achieved in the majority of cases.Normal blood pressure is achieved in only 20% of cases of arteriosclerotic renal artery stenosis. The longer the stenosis was untreated and high blood pressure persisted, the lower the chance that the blood pressure will drop again.
Persistent high blood pressure is referred to as fixed hypertension. If no treatment is given to patients with renal artery stenosis, there is a risk of a gradual loss of function and shrinkage of the kidney. The unaffected kidney can then enlarge, which is known as hypertrophy of the kidney.
