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Kidney Infarction

Definition of Renal Artery Embolism and Kidney Infarction

A renal infarction is an acute ischemic injury of the renal parenchyma caused by inadequate blood flow (ischemia) in the renal artery, its main branches, or the renal vein.

Epidemiology

A healed renal infarction is a common autopsy finding (1%), but acute clinical renal infarction is rare (0.02/1000 emergency department patients) (Lopez et al., 2010).

Etiology (Causes) of Kidney Infarction

• Thromboembolic event: 90% of renal infarctions are caused by an embolic occlusion of the renal artery or its main branches. Risk factors include atrial fibrillation, mitral valve disease, endocarditis, cardiac surgery, PTA or PTCA, aortic aneurysm, and aneurysm or atherosclerosis of the renal arteries
• Renal artery thrombosis: caused by an unstable plaque in renal artery atherosclerosis. Rare causes include renal trauma, vasculitis, fibromuscular dysplasia, and iatrogenic injury (accidental ligation, traumatic manipulation of the renal artery, or injury during PTA)
• Hemorrhagic renal infarction in renal vein thrombosis

Pathology

Occlusion of renal artery branches causes a wedge-shaped anemic infarct with a hemorrhagic rim. Over time, scar-related parenchymal retraction develops. Renal vein thrombosis causes hemorrhagic infarction.

Signs and Symptoms

Most renal infarctions are not recognized as such, and their symptoms are often misattributed:

• Flank pain
• Hematuria
• Arterial hypertension
• Irregular pulse
• Fever
• Nausea and vomiting
• Oliguria or anuria

Diagnostic Workup

Urine

Proteinuria, microhematuria, or hematuria.

Laboratory Tests

Typical findings include an elevated LDH level as a marker of tissue necrosis, often accompanied by leukocytosis and an elevated CRP level. Creatinine or cystatin C may be elevated if a significant portion of the kidney is affected.

Ultrasonography

Doppler ultrasonography of the kidney can quickly confirm complete occlusion but is less reliable for partial infarctions. After a segmental renal infarction heals, a deeply retracted scar remains visible in the renal parenchyma. A complete infarction leads to an atrophic kidney.

Abdominal CT

CT shows absent contrast enhancement of the entire kidney or wedge-shaped areas in partial infarctions on contrast-enhanced images [fig. partial renal infarction]. In 50% of patients, a thin rim of renal cortex enhances several hours to days after infarction because of collateral perfusion from the perirenal capsule (cortical rim sign).

Computed tomography of a left-sided partial renal infarction. An additional finding is a partial splenic infarction. Reproduced with permission from Prof. Dr. K. Bohndorf, Augsburg.

Digital Subtraction Angiography (DSA)

Allows precise determination of the location and extent of the vascular occlusion as part of interventional treatment.

Additional Diagnostic Evaluation

ECG and echocardiography to identify a cardiac or aortic source of embolism.

Treatment of Kidney Infarction

Conservative Therapy

Basic measures include analgesics, blood pressure control, and prompt therapeutic anticoagulation. Thrombolytic therapy may be considered if endovascular treatment is unavailable. The decision depends on the extent of the infarction and the remaining renal function.

Endovascular Therapy

Catheter-based revascularization with local thrombolysis, aspiration thrombectomy, mechanical thrombectomy, angioplasty, or stent implantation may be considered when the diagnosis is made early, particularly in cases of main renal artery occlusion, bilateral ischemia, a solitary kidney, a large area of threatened renal parenchyma, or persistent severe symptoms. The time window for successful intervention is not clearly defined. Open surgical revascularization is rarely required when endovascular treatment is not feasible.

References

V. M. Lopez and J. Glauser, “A case of renal artery thrombosis with renal infarction.,” J Emerg Trauma Shock, vol. 3, no. 3, p. 302, 2010.

  Deutsche Version: Niereninfarkt

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