The kidneys filter blood and remove waste from your body through the form of urine, which collects in your bladder and exits your body when you urinate. The kidneys also help to control your blood pressure (BP) by secreting a hormone called renin into your bloodstream. The renal arteries and renal veins supply the kidneys. Renovascular disease is a condition that affects these blood vessels of your kidneys. The blood vessels may become narrow or blocked due to blood clots or plaque buildup and lead to renal vein thrombosis or renal artery stenosis respectively.
Renal vein thrombosis can result due to a blood clot, nephrotic syndrome (high levels of albumin protein excreted through urine), presence of a tumor, infection or injury to the vein. Renal artery stenosis is a condition characterized by hardening of the kidney arteries, which is caused due to the accumulation of a sticky substance (cholesterol, calcium or fibrous tissue) called plaque on the walls of the artery. Obesity, smoking, high cholesterol levels and diabetes are some of the risk factors that increase your chances of renovascular diseases.
Renovascular conditions progress slowly over time and may not cause noticeable symptoms initially. Symptoms may include elevated blood pressure, decreased kidney function and a whooshing sound in the abdomen heard with a stethoscope. Blood clots in the renal veins rarely affect the kidneys, but can travel to healthy blood vessels and block the flow of blood. The blood clot can travel to arteries that lead to the lungs, resulting in a serious condition called pulmonary embolism, or to other arteries. This may cause symptoms such as pain in legs, thighs and sides of your abdomen, protein or blood in urine, fever, vomiting, nausea, swelling in your legs and difficulty in breathing.
When you present to the clinic with any of these symptoms, your doctor may suggest the following imaging tests to help determine renovascular disease:
- Ultrasound : Uses sound waves to create images of the blood vessels
- CT scan : Uses X-rays to create images of cross-sections of the blood vessels
- MRA scan : Uses magnetic fields to image blood vessels
- Radionuclide scanning : Uses radioactive chemicals for imaging
- Angiography : Uses a special dye in the blood vessels, which can be detected by X-rays
- Venacavography : A form of angiography that takes images of the main abdominal veins
- Medication : You may be advised to take BP lowering medications to keep your BP under control.
- Thrombolysis : An anticoagulant or clot-dissolving medication may be directly injected into the blood clot through a catheter (a long, thin tube) inserted in the groin.
- Angioplasty and stenting : Your doctor inserts a catheter through a small incision in the groin and guides it through to your renal artery. The catheter carries a tiny balloon that is inflated at the site of the plaque blockage to flatten it against the walls of your artery. Your doctor may insert a stent (tiny metal-mesh) in the artery to hold the blood vessel open and prevent it from collapsing.
- Surgery : There are 2 surgical procedures to treat renovascular disease. Your surgeon may suggest renal endarterectomy, in which the plaque is removed from the inner wall of your renal artery leaving behind a wide-open artery. Bypass surgery is another procedure that may be recommended, in which your surgeon re-routes blood flow around the narrowed or blocked section of your renal artery by using a graft. The graft is attached above and below the block, creating a new path for the blood to flow through.
Based on the severity of your condition, your physician may recommend the following treatment options:
You can prevent renovascular diseases by eating a balanced diet, maintaining a healthy body weight, quitting smoking, exercising regularly and keeping cholesterol and blood pressure levels under control.