Renal Artery Induced Hypertension (Renal Artery Stenosis)
What is Renal Artery Stenosis?
Although the cause of most
cases of hypertension goes undiagnosed, it is estimated that 20%
of hypertension may be caused by renal artery stenosis. As is seen in atherosclerotic changes in the vasculature throughout the body which causes reduced blood flow, the arteries that supply the two kidneys can also be involved in this atherosclerotic process. While the deprivation of sufficient blood flow to any part of the body will place that particular area at risk in terms of its viability, the renal arteries are designed to maintain the proper function of the kidneys. The kidneys play another important role in maintaining proper blood pressure dynamics. If there is an atherosclerotic plaque in the artery that leads to the kidney there is reduced blood flow to that kidney. In this scenario the kidney attempts to maintain the blood pressure and blood flow and a series of hormonal changes begins which leads to the kidney secreting angiotensin II, which is the body's attempt to maintain proper perfusion of the kidney. While "well meaning", the angiotensin II continuously elevates the blood pressure throughout the body in order to maintain this proper perfusion of the kidney. Thus the well known problem of hypertension develops. As might be expected, the atherosclerotic plaque that is involved in renal artery
is seen in the older age population and is usually located at the beginning of the renal artery where it arises from the aorta (the body's main blood vessel). However, not uncommonly renal artery stenosis can be a feature of excessive thickening of the renal artery which causes a decrease in the internal diameter of the vessel. The end result is the sam
e, where the kidney sees a reduced "perfusion pressure" and that sets off the same hormonal cascade which leads to elevated blood pressure. This situation is seen typically in middle aged females and is referred to as "fibromuscular hyperplasia". By no means however is it restricted to this patient population as it can be seen in both sexes and in younger and older age patients.
How is this condition diagnosed and treated?
The simplest, leas
t invasive and least expensive technique is what is known as a renal duplex scan of the kidneys and their arteries. With this test ultrasonography can be used to visualize these body parts. In addition the doppler technique of measuring the velocity of blood flow is combined with visualizing these areas and arriving at a conclusion if there is evidence to suggest renal artery stenosis. Should this be the case, different treatment protocols extending from simple blood pressure medication to stenting of the renal arteries or rarely surgical intervention will be employed. In our practice we are very attuned to arrive at a diagnosis in all patients who carry a diagnosis of hypertension, especially if controlling the blood pressure is not fully effective or requires multiple medications. We are one of the few cardiology practices in the area that performs this type of testing as it is technically challenging and needs to be read by a cardiologist with experience in this area. This is done in our office so it is not time consuming and does not involve any radiation.
Please feel free to call our office to gain further information about this testing or to schedule it at your convenience.