Renal Artery Stenosis and Occlusion

The most common cause is thromboembolism. Emboli may originate in the heart (due to atrial fibrillation Atrial Fibrillation Atrial fibrillation is a rapid, irregularly irregular atrial rhythm. Symptoms include palpitations and sometimes weakness, effort intolerance, dyspnea, and presyncope. Atrial thrombi may form... read more , after myocardial infarction Acute Myocardial Infarction (MI) Acute myocardial infarction is myocardial necrosis resulting from acute obstruction of a coronary artery. Symptoms include chest discomfort with or without dyspnea, nausea, and/or diaphoresis... read more , or from vegetations due to bacterial endocarditis Infective Endocarditis Infective endocarditis is infection of the endocardium, usually with bacteria (commonly, streptococci or staphylococci) or fungi. It may cause fever, heart murmurs, petechiae, anemia, embolic... read more ) or the aorta (as atheroemboli Renal Atheroembolism Renal atheroembolism is occlusion of renal arterioles by atherosclerotic emboli, causing progressive chronic kidney disease. It results from rupture of atheromatous plaques. Symptoms are those... read more ); less often, fat or tumor emboli are the cause. Thrombosis may occur in a renal artery spontaneously or after trauma, surgery, angiography, or angioplasty. Other causes of acute occlusion include aortic dissection Aortic Dissection Aortic dissection is the surging of blood through a tear in the aortic intima with separation of the intima and media and creation of a false lumen (channel). The intimal tear may be a primary... read more and rupture of a renal artery aneurysm Aortic Branch Aneurysms Aneurysms may occur in any major aortic branch; such aneurysms are much less common than abdominal or thoracic aortic aneurysms. Symptoms vary depending on the location and artery affected but... read more .

Rapid, total occlusion of large renal arteries for 30 to 60 minutes results in infarction. The infarct is typically wedge-shaped, radiating outward from the affected vessel.

About 90% of cases are due to atherosclerosis Atherosclerosis Atherosclerosis is characterized by patchy intimal plaques (atheromas) that encroach on the lumen of medium-sized and large arteries. The plaques contain lipids, inflammatory cells, smooth muscle... read more , which is usually bilateral. Almost 10% of cases are due to fibromuscular dysplasia Fibromuscular Dysplasia Fibromuscular dysplasia includes a heterogenous group of nonatherosclerotic, noninflammatory arterial changes, causing some degree of vascular stenosis, occlusion, or aneurysm. Fibromuscular... read more (FMD), which is commonly unilateral. Less than 1% of cases result from Takayasu arteritis Takayasu Arteritis Takayasu arteritis is an inflammatory disease affecting the aorta, its branches, and pulmonary arteries. It occurs predominantly in young women. Etiology is unknown. Vascular inflammation may... read more , Kawasaki disease Kawasaki Disease Kawasaki disease is a vasculitis, sometimes involving the coronary arteries, that tends to occur in infants and children between the ages of 1 year and 8 years. It is characterized by prolonged... read more , neurofibromatosis type 1 Neurofibromatosis Neurofibromatosis refers to several related disorders that have overlapping clinical manifestations but that are now understood to have distinct genetic causes. It causes various types of benign... read more , aortic wall hematoma, or aortic dissection Aortic Dissection Aortic dissection is the surging of blood through a tear in the aortic intima with separation of the intima and media and creation of a false lumen (channel). The intimal tear may be a primary... read more .

Atherosclerosis develops primarily in patients > 45 (more often men) and usually affects the aortic orifice or proximal segment of the renal artery. Chronic progressive stenosis tends to become clinically evident after about 10 years of atherosclerosis, causing renal atrophy and chronic kidney disease Chronic Kidney Disease Chronic kidney disease (CKD) is long-standing, progressive deterioration of renal function. Symptoms develop slowly and in advanced stages include anorexia, nausea, vomiting, stomatitis, dysgeusia... read more .

FMD is pathologic thickening of the arterial wall, most often of the distal main renal artery or the intrarenal branches. The thickening tends to be irregular and can involve any layer (but most often the media). This disorder develops primarily in younger adults, particularly in women aged 20 to 50. It is more common among 1st-degree relatives of patients with FMD and among people with the ACE1 gene.

A renal thromboembolic disorder may be treated with a combination of anticoagulation, fibrinolytics, and surgical or catheter-based embolectomy. Treatment within 3 hours of symptom onset is likely to improve renal function. However, complete recovery is unusual, and early and late mortality rates are high because of extrarenal embolization or underlying atherosclerotic heart disease.

Patients presenting within 3 hours may benefit from fibrinolytic (thrombolytic) therapy Fibrinolytics Treatment of acute coronary syndromes (ACS) is designed to relieve distress, interrupt thrombosis, reverse ischemia, limit infarct size, reduce cardiac workload, and prevent and treat complications... read more (eg, streptokinase, alteplase) given IV or by local intra-arterial infusion. However, such rapid diagnosis and treatment are rare.

All patients with a thromboembolic disorder require anticoagulation Treatment Deep venous thrombosis (DVT) is clotting of blood in a deep vein of an extremity (usually calf or thigh) or the pelvis. DVT is the primary cause of pulmonary embolism. DVT results from conditions... read more with IV heparin, unless contraindicated. Long-term anticoagulation with oral warfarin can be initiated simultaneously with heparin if no invasive intervention is planned. Non–vitamin K oral anticoagulants (eg, dabigatran, apixaban, rivaroxaban) can be considered in appropriate patients. Anticoagulation should be continued for at least 6 to 12 months—indefinitely for patients with a recurrent thromboembolic disorder or a hypercoagulability disorder.

Surgery to restore vascular patency has a higher mortality rate than fibrinolytic therapy and has no advantage in recovery of renal function. However, surgery, particularly if done within the first few hours, is preferred for patients with traumatic renal artery thrombosis. If patients with nontraumatic, severe renal failure do not recover function after 4 to 6 weeks of drug therapy, surgical revascularization (embolectomy) can be considered, but it helps only a few.

If the cause is thromboemboli, the source should be identified and treated appropriately.

Revascularization may be considered for patients who meet one or more of the following criteria:

Revascularization is usually achieved by percutaneous transluminal angioplasty (PTA) Percutaneous Coronary Interventions (PCI) Percutaneous coronary interventions (PCI) include percutaneous transluminal coronary angioplasty (PTCA) with or without stent insertion. Primary indications are treatment of Angina pectoris... read more with stent placement or with surgical bypass of the stenotic segment. Surgery is usually more effective than PTA for atherosclerotic occlusion; it cures or attenuates hypertension in 60 to 70% of patients. However, surgery is considered only if patients have complex anatomic lesions or if PTA is unsuccessful, particularly with repeated in-stent restenosis. PTA is preferred for patients with fibromuscular dysplasia; risk is minimal, success rate is high, and restenosis rate is low.

For patients who do not meet one of the criteria above, medical therapy is recommended based on data from the randomized trials, which showed that renal-artery stenting plus medical therapy had no significant benefit over medical therapy alone for preventing adverse cardiovascular or renal events (1 Treatment reference Renal artery stenosis is a decrease in blood flow through one or both of the main renal arteries or their branches. Renal artery occlusion is a complete blockage of blood flow through one or... read more ). Angiotensin-converting enzyme (ACE) inhibitors or angiotensin II receptor blockers (ARBs) can be used in unilateral and, if glomerular filtration rate (GFR) is monitored closely, in bilateral renal artery stenosis. These medications can potentially reduce GFR and increase serum blood urea nitrogen and creatinine levels. Additional antihypertensive medications are frequently required.