Renal hypoperfusion results in renovascular hypertension Renovascular Hypertension Renovascular hypertension is blood pressure elevation due to partial or complete occlusion of one or more renal arteries or their branches. It is usually asymptomatic unless long-standing. A... read more , renal failure, and, if complete occlusion occurs, renal infarction and necrosis.
Etiology of Renal Artery Stenosis and Occlusion
Occlusion may be acute or chronic. Acute occlusion is usually unilateral. Chronic occlusion may be unilateral or bilateral.
Acute renal artery 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 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.
Chronic progressive renal artery stenosis
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 > 50 (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.
Symptoms and Signs
Manifestations depend on rapidity of onset, extent, whether unilateral or bilateral, and duration of renal hypoperfusion. Stenosis of one renal artery is often asymptomatic for a considerable time.
Acute complete occlusion of one or both renal arteries causes steady and aching flank pain, abdominal pain, fever, nausea, and vomiting. Gross hematuria, oliguria, or anuria may occur; hypertension is rare. After 24 hours, symptoms and signs of acute kidney injury Symptoms and Signs Acute kidney injury is a rapid decrease in renal function over days to weeks, causing an accumulation of nitrogenous products in the blood (azotemia) with or without reduction in amount of urine... read more may develop. If the cause was thromboembolic, features of thromboembolism at other sites (eg, blue toes, livedo reticularis, retinal lesions on funduscopic examination) also may be present.
Chronic progressive stenosis causes hypertension Hypertension Hypertension is sustained elevation of resting systolic blood pressure (≥ 130 mm Hg), diastolic blood pressure (≥ 80 mm Hg), or both. Hypertension with no known cause (primary; formerly, essential... read more , which may begin at an atypical age (eg, before age 30 or after age 50) and which may be refractory to control despite use of multiple antihypertensives. Physical examination may detect an abdominal bruit or signs of atherosclerosis. Symptoms and signs of chronic kidney disease Symptoms and Signs 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 develop slowly.
Diagnosis is suspected in patients with renal failure and who have
Symptoms of acute renal artery occlusion
Symptoms or signs of thromboembolism
Hypertension that begins before age 30 or is refractory to treatment with > 3 antihypertensive drugs
Blood and urine tests are done to confirm renal failure. Diagnosis is confirmed by imaging tests (see table Imaging Tests for Diagnosis of Renal Artery Stenosis or Occlusion Imaging Tests for Diagnosis of Renal Artery Stenosis or Occlusion 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 ). Which tests are done depends on the patient’s renal function and other characteristics and on test availability.
Some tests (CT angiography, arteriography, digital subtraction angiography) require an IV ionic radiocontrast agent, which may be nephrotoxic; this risk is lower with the nonionic hypo-osmolar or iso-osmolar contrast agents that are now in widespread use (see Radiographic Contrast Agents and Contrast Reactions Radiographic Contrast Agents and Contrast Reactions Radiopaque contrast agents are often used in radiography and fluoroscopy to help delineate borders between tissues with similar radiodensity. Most contrast agents are iodine based. Iodinated... read more ). Magnetic resonance angiography (MRA) requires the use of gadolinium contrast; in patients with severe 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 , gadolinium contrast carries the risk of nephrogenic systemic fibrosis, a condition that closely resembles systemic sclerosis Systemic Sclerosis Systemic sclerosis is a rare chronic disease of unknown cause characterized by diffuse fibrosis and vascular abnormalities in the skin, joints, and internal organs (especially the esophagus... read more and that has no satisfactory method of treatment.
When results of other tests are inconclusive or negative but clinical suspicion is strong, arteriography is necessary for definitive diagnosis. Arteriography may also be needed before invasive interventions.
When a thromboembolic disorder is suspected, electrocardiography (to detect atrial fibrillation) and hypercoagulability studies may be needed to identify treatable embolic sources. Transesophageal echocardiography is done to detect atheromatous lesions in the ascending and thoracic aorta and cardiac sources of thrombi or valvular vegetations.
Blood and urine tests are nondiagnostic but are done to confirm renal failure, indicated by elevated creatinine and blood urea nitrogen and by hyperkalemia. Leukocytosis, gross or microscopic hematuria, and proteinuria may also be present.
Restoration of vascular patency in acute occlusions and, if patients have refractory hypertension or potential for renal failure, in chronic stenosis
Treatment depends on the cause.
Acute renal artery occlusion
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.
Chronic progressive renal artery stenosis
Treatment is indicated for patients who meet one or more of the following 5 criteria:
Hypertension refractory to medical treatment with ≥ 3 drugs
Deterioration of renal function despite optimal medical therapy
A short duration of elevated blood pressure prior to the diagnosis of renovascular disease
Unexplained rapid progression of renal insufficiency
Treatment is with 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 plus 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.
Treatments may be ineffective unless vascular patency (see Renovascular Hypertension: Treatments Treatment Renovascular hypertension is blood pressure elevation due to partial or complete occlusion of one or more renal arteries or their branches. It is usually asymptomatic unless long-standing. A... read more ) is restored. However, the 2014 CORAL study 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, angiotensin II receptor blockers (ARBs), or renin inhibitors can be used in unilateral and, if glomerular filtration rate (GFR) is monitored closely, in bilateral renal artery stenosis. These drugs can reduce GFR and increase serum blood urea nitrogen and creatinine levels. If GFR decreases enough to increase serum creatinine, calcium channel blockers Calcium channel blockers A number of drug classes are effective for initial and subsequent management of hypertension: Adrenergic modifiers Angiotensin-converting enzyme (ACE) inhibitors Angiotensin II receptor blockers... read more (eg, amlodipine, felodipine) or vasodilators Direct vasodilators A number of drug classes are effective for initial and subsequent management of hypertension: Adrenergic modifiers Angiotensin-converting enzyme (ACE) inhibitors Angiotensin II receptor blockers... read more (eg, hydralazine, minoxidil) should be added or substituted.
Renal artery stenosis or occlusion may be acute (usually due to thromboembolism) or chronic (usually due to atherosclerosis or fibromuscular dysplasia).
Suspect acute occlusion if patients have steady, aching flank or abdominal pain, and sometimes fever, nausea and vomiting, and/or gross hematuria.
Suspect chronic occlusion in patients who develop unexplained severe or early-onset hypertension.
Confirm the diagnosis with vascular imaging.
Restore vascular patency for patients who have acute occlusion and for selected patients (eg, with severe complications or refractory disease) who have chronic occlusion.
Hypertension may be difficult to control until vascular patency is restored, but begin treatment with ACE inhibitors, ARBs, or renin inhibitors; closely monitor GFR; and substitute calcium channel blockers or vasodilators if GFR decreases.