The paired renal arteries arise from either side of the abdominal aorta just below the diaphragm. They carry one quarter of the total cardiac output to the kidneys for filtration of metabolic wastes. In this way, an equivalent of the entire blood volume is processed by the kidneys every four minutes. The renal arteries contain auto-regulatory mechanisms including the hormone renin to adjust the blood pressure and thus maintain adequate blood flow to the kidneys despite variables such as changes in fluid volume, physical activity, disease states, etc.
The kidneys play a critical role in regulating arterial blood pressure. When the kidneys aren’t getting enough blood flow, they secrete renin, which works to increase the arterial blood pressure. Any narrowing or stenosis of the renal arteries will abnormally decrease blood flow to the kidneys and trigger them to release excessive amounts of renin. Because renin so effectively increases arterial blood pressure, any narrowing or stenosis of the renal arteries can result in persistent or severe arterial hypertension.
Renal artery stenosis should be ruled out in cases of severe hypertension or hypertension that is resistant to standard treatment. Renal artery stenosis is not an uncommon condition that usually arises from atherosclerosis or fibromuscular dysplasia. Because renin is so effective at increasing arterial blood pressure, renal artery stenosis can trigger hypertension with very high pressures that can be resistant to many blood pressure medications.
The presence or absence of renal artery stenosis can be critical information for a doctor that is diagnosing or treating a patient with severe hypertension or hypertension that is resistant to standard treatment. Severe or long-lasting renal artery stenosis can lead to kidney failure.
When a patient be diagnosed with renal artery stenosis, they may be treated expectantly or operatively, depending on the cause, location, and severity of the stenosis, as well as the overall health of the patient and how symptomatic the stenosis may be. Possible treatments include balloon angioplasty, placement of a stent, or open arterial bypass.
Duplex ultrasound examination is the ideal technique for examining the renal arteries in most patients. Because duplex ultrasound provides real-time hemodynamic information (flow velocities, volumes, distal resistance, etc.) as well as static information (an atomic anomalies, lumen diameters, plaque characteristics, etc), it is much more able to ascertain the presence or absence of clinically-significant renal artery stenosis. Because it is more convenient, non-invasive, and uses sound waves rather than ionizing radiation, duplex ultrasound is much more cost-effective than competing modalities such as CT and MRI. Patients should be NPO overnight.
Common indications for a renal artery ultrasound evaluation include:
- Severe Hypertension
- Hypertension resistant to standard medications
- Hypertension with advanced age, h/o tobacco abuse, or diabetes mellitus
- Atherosclerosis in other arteries such as coronaries, carotids, aorta, lower extremities
- Abdominal Bruit
- Small Kidney(s)
- Chronic Renal Insufficiency
- Renal Artery Stenosis
- Chronic Renal Failure
- Renal Cysts / Masses / Cancer
- Renal Vein Occlusion
- Causes of Kidney Failure
- Small Kidneys
- 93975 – Duplex scan of arterial inflow and venous outflow of abdominal, pelvic, scrotal contents and or retroperitoneal organs; complete study
- 93976 – Duplex scan of arterial inflow and venous outflow of abdominal, pelvic, scrotal contents and or retroperitoneal organs; limited study
Common ICD-10 CODES