Atheromatous plaque rupture usually results from manipulation of the aorta or other large arteries during vascular surgery, angioplasty, or arteriography. Spontaneous plaque rupture, which occurs most often in patients who have diffuse erosive atherosclerosis or who are being treated with anticoagulants or fibrinolytics, is rare.
Atheroemboli tend to cause incomplete occlusion with secondary ischemic atrophy rather than renal infarction. A foreign body immune reaction often follows embolization, leading to continued deterioration in renal function for 3 to 8 weeks. Acute renal impairment may also result from massive or recurrent episodes of embolization.
Symptoms and Signs of Renal Atheroembolism
Symptoms are usually those of acute or chronic renal dysfunction with uremia (see Acute Kidney Injury [AKI]: Symptoms 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 ). Abdominal pain, nausea, and vomiting can result from concomitant compromised arterial microcirculation of abdominal organs (eg, pancreas, gastrointestinal tract). Sudden blindness and formation of bright yellow retinal plaques (Hollenhorst plaques) can result from emboli in retinal arterioles.
Signs of widespread peripheral embolism (eg, livedo reticularis, painful muscle nodules, overt gangrene, which is often referred to as the trash syndrome) are sometimes present.
Diagnosis of Renal Atheroembolism
Sometimes, renal biopsy
Location of source of emboli
Diagnosis is suggested by worsening renal function in a patient with recent manipulation of the aorta, particularly if there are signs of atheroemboli. Differential diagnosis includes contrast-induced and drug-induced nephropathy.
If suspicion of atheroembolism remains high, percutaneous renal biopsy is done; it has a sensitivity of about 75%. Diagnosis is important because there may be treatable causes of emboli in the absence of vascular obstruction. Cholesterol crystals in the emboli dissolve during tissue fixation, leaving pathognomonic biconcave, needle-shaped clefts in the occluded vessel. Sometimes skin, muscle, or gastrointestinal biopsy can provide the same information and indirectly help establish the diagnosis.
Blood and urine tests can confirm the diagnosis of acute kidney injury Acute Kidney Injury (AKI) 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 or 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 but do not establish cause. Urinalysis typically shows microscopic hematuria and minimal proteinuria; however, proteinuria is occasionally in the nephrotic range (> 3 g/day). Eosinophilia, eosinophiluria, and transient hypocomplementemia may be present.
If renal or systemic emboli recur and their source is unclear, transesophageal echocardiography is done to detect atheromatous lesions in the ascending and thoracic aorta and cardiac sources of emboli; dual helical CT may help characterize the ascending aorta and aortic arch.
Treatment of Renal Atheroembolism
Treatment of embolic source when possible
Modification of risk factors
Sometimes the source of emboli can be treated (eg, anticoagulation for patients with emboli from a cardiac source and atrial fibrillation and for patients in whom a clot becomes a source of new emboli). However, no direct treatment of existing renal emboli is effective. Corticosteroids, antiplatelet medications, vasodilators, and plasma exchange are not helpful. There is no demonstrated benefit of anticoagulation and, according to most experts, its use may actually enhance atheroembolism.
Treatment of renal dysfunction includes control of hypertension and management of electrolytes and fluid status; sometimes dialysis Hemodialysis In hemodialysis, a patient’s blood is pumped into a dialyzer containing 2 fluid compartments configured as bundles of hollow fiber capillary tubes or as parallel, sandwiched sheets of semipermeable... read more is required. Modifying risk factors for 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 may slow its progression and induce regression. Strategies include management of hypertension, hyperlipidemia, and diabetes; smoking cessation Smoking Cessation Most smokers want to quit and have tried doing so with limited success. Effective interventions include cessation counseling and drug treatment, such as varenicline, bupropion, or a nicotine... read more ; and encouragement of regular aerobic exercise and good nutrition (Atherosclerosis: Treatment Treatment 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 ).
Prognosis for Renal Atheroembolism
Patients with renal atheroemboli have a poor overall prognosis.
Renal atheroembolism usually results from manipulation of the aorta during vascular surgery, angioplasty, or arteriography, and rarely from spontaneous atherosclerotic embolization.
Suspect the diagnosis if renal function deteriorates after the aorta or another large artery is manipulated.
Confirm the diagnosis based on clinical findings and occasionally with percutaneous renal biopsy.
Treat supportively, correcting modifiable risk factors and, when possible, treating the embolic source; however, the overall prognosis remains poor.