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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:

Renal infarction is a common autopsy finding in 1%, but rare diagnosed in patients (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: arising from 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:

Embolism of the renal artery branches leads to a wedge-shaped anemic infarct with a hemorrhagic rim. Over time, a scar-related parenchymal retraction develops. Thrombosis of the renal vein leads to a hemorrhagic infarction.

Signs and Symptoms

Most renal infarcts are not recognized as such, and the symptoms are mismatched:

• Flank pain or abdominal pain
• Hematuria
• Arterial hypertension
• Irregular heart rate
• Nausea, vomiting
• Oliguria, 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. Elevated creatinine if significant renal tissue is affected.

Ultrasonography:

Doppler ultrasonography of the kidney can quickly confirm the diagnosis of complete kidney infarction. After healing of segmental renal infarction, the affected region shrinks and a deep-drawn scar remains visible.

Abdominal CT:

Easy diagnosis in contrast CT scan with wedge-shaped areas without contrast enhancement [fig. partial renal infarction]. The cortical rim sign is seen in 50% of the patients after several hours or days of infarction: a thin rim of cortex enhances due to collateral capsular perfusion.

Computed tomography of a left-sided partial renal infarction. Additional finding: partial splenic infarction. With kind permission, 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 not available. 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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