What is hypertension?
Blood circulates throughout our bodies pumped along by the heart. With each beat of the heart the pressure rises and after each beat it falls. The maximum pressure after a beat of the heart is called the systolic pressure and the low point of pressure is called the diastolic pressure. There are many causes of high blood pressure. Systolic pressure greater than 140 mm Hg or a diastolic pressure greater than 90 mm Hg is considered hypertension.
Most people who develop hypertension have what is known as essential hypertension. This type of hypertension does not have a known cause and there is no cure. Fortunately, when detected early, this type of hypertension can be controlled with medications, and the serious effects of hypertension can be avoided. A small portion of the cases of hypertension are caused by narrowing of the arteries supplying blood to the kidneys. The kidneys play an important role in the regulation of blood pressure. If blood flow to the kidneys is slowed, the kidneys send out chemicals that raise the blood pressure dramatically. This situation is known as renovascular hypertension. Fortunately, this form of hypertension is treatable.
Since only a small fraction of the people with hypertension have the treatable form called renovascular hypertension, doctors perform careful screening for renovascular disease. If your doctor suspects you have renovascular disease he/she may have sent you for certain tests to determine if the blood flow to your kidneys is impaired. There are several tests that can be used to evaluate someone with hypertension for narrowing of the renal arteries. The most accurate test for this disease is an angiogram. An angiogram is an x-ray study used to study arteries. The test involves placing a small plastic tube into the arterial system. This small plastic tube, or catheter, is usually introduced into an artery at the top of the leg. The catheter is then advanced up into the arteries near the kidneys. There, x-ray contrast is injected into the arteries, and x-ray images of the arteries are taken.
If the renal angiogram reveals a narrowing of the renal arteries, a balloon-tipped catheter can be used to stretch open the narrowing. The technique of stretching arteries open with a balloon is called angioplasty. The technique is more formally known as percutaneous transluminal angioplasty or PTA for short. If the angioplasty is successful, normal blood flow to the kidney is restored.
Interventional radiologists developed small metal devices called stents that can be used to help keep a narrowed vessel open. These stents are deployed in the renal artery at the site of narrowing and provide support to keep the vessel open.
Patients usually need to lie flat
for approximately 6-8 hours after the catheter is removed from the
artery. After that, your interventional radiologist may also want to
observe you in the hospital for sudden changes in blood
For any questions or concerns:
Contact the Radiology and Medical Imaging department at 434-924-9400.