When you hear hoofbeats, think…

Patients with acute renal artery infarction most often present with flank pain, nausea, and vomiting.¹ Elevated blood pressure at the time of presentation may also be present.² Increased renin secretion from juxtaglomerular kidney cells, secondary to decreased renal perfusion, may cause an abrupt increase in blood pressure.

Renal infarction is rare, especially in patients who do not have typical risk factors. The overall incidence has been estimated between 0.004% to 0.007%.³ Atrial fibrillation is estimated to be present in 25% to 65% of cases.⁴ Other causes include renal artery injury or an underlying hypercoagulable state, whether autoimmune or malignancy-related, predisposing to thromboembolism. Emboli usually originate from the heart, but the aorta may also serve as a source. Renal infarctions have also been recently observed in COVID-19 patients, although studies are limited.⁵

Markers for kidney function, such as creatinine and GFR, may not be helpful in diagnosis and can be normal in cases of unilateral renal artery infarction due to compensation by the contralateral kidney. Elevated lactate dehydrogenase and leukocytosis may be present but are non-specific.⁶

CT abdomen/pelvis with IV contrast is the preferred imaging modality. Renal doppler ultrasound is not sensitive enough to detect segmental infarcts.⁷ In one study (n=44), ultrasound was only positive in 11% of cases or renal infarction.⁸ CT Angiogram (CTA) may be useful to evaluate for an intra-aortic thrombus or to determine the extent of the occlusion. An acute aortic dissection or mesenteric ischemia can also present similarly, and a CTA can help further distinguish between them. Surgical repair is necessary for dissections extending into the renal artery, and mesenteric ischemia may require anticoagulation. An echocardiogram may rule out thrombus or patent foramen ovale that may predispose to paradoxical emboli.

Treatment is based on etiology. For non-traumatic renal artery infarction, there are two options. Percutaneous endovascular therapy with early balloon-catheter thrombolysis/stenting has demonstrated successful return of renal perfusion.^9,10  

Vascular surgery or interventional radiology consultation should be obtained for patients that are candidates for thrombolysis, thrombectomy, or stenting. Patients with complete renal artery occlusion < 6 hours or partial occlusion < 24 hours might benefit from early endovascular intervention.¹¹

For all other patients, IV Heparin is the mainstay of therapy to prevent further thromboembolism. Patients without an underlying cause should be bridged to oral anticoagulation paired with antiplatelet therapy and remain on therapy for at least 6 months. In one retrospective study (n=438) of patients with acute renal infarction who received anticoagulation and antiplatelet therapy, 2.8% had recurrent infarction within 20 months without statistically significant differences between subgroups of underlying etiology (i.e. cardiogenic vs hypercoagulable state vs renal artery injury vs idiopathic).¹² 

Patients with renal infarction and atrial fibrillation may benefit from anticoagulation.¹³ However, in cases of idiopathic renal infarction, there are no studies demonstrating the benefit of long-term anticoagulation.

This patient underwent CTA which was significant for a thrombus in the descending aorta. Imaging was also significant for multifocal liver lesions and a right hilar lymph node with multiple pulmonary nodules, concerning for neoplastic disease. Transthoracic echocardiogram revealed mild concentric left ventricular hypertrophy without evidence of thrombus. The patient was heparinized and vascular surgery recommended transfer to a nearby hospital for further management and possible stenting.

Acute renal artery infarction should be considered in patients who present to the ED with acute flank pain, nausea, and vomiting. The presentation can mimic common diagnoses such as ureterolithiasis or pyelonephritis, but also life-threatening ones such as aortic dissection. Patients with elevated blood pressure and pain that is refractory to adequate analgesia should raise suspicion for renal infarction. Patients with atrial fibrillation and hypercoagulability are at higher risk and imaging should be obtained to expedite early endovascular intervention.

• 1. Consider renal artery infarction in the setting of undiagnosed flank pain and hypertension.
• 2. CT abdomen/pelvis with IV contrast may confirm the diagnosis; CTA can rule out mimicking diagnoses.
• 3. Obtain an ECG to assess for dysrhythmias; consider bedside echocardiogram
• 4. Treatment consists of percutaneous endovascular therapy plus IV anticoagulation or IV anticoagulation alone for patients with interventional contraindications or complete occlusion > 6 hours.

1. 1. Chu, P., Wei, Y., Huang, J., Chen, S., Chu, T. and Wu, K., 2020. Clinical Characteristics Of Patients With Segmental Renal Infarction.
2. 2. Long, Brit emDOCs.net – Emergency Medicine Education. 2020. Renal Infarction: Pearls And Pitfalls – Emdocs.Net – Emergency Medicine Education. [online]Availableat:<http://www.emdocs.net/renal-infarction-pearls-and-pitfalls/> [Accessed 29 July 2020].
3. 3. Huang, C., Lo, H., Huang, H., Kao, W., Yen, D., Wang, L., Huang, C. and Lee, C., 2007. ED presentations of acute renal infarction. The American Journal of Emergency Medicine, 25(2), pp.164-169.
4. 4. Post, A., den Deurwaarder, E., Bakker, S., de Haas, R., van Meurs, M., Gansevoort, R. and Berger, S., 2020. Kidney Infarction in Patients With COVID-19. American Journal of Kidney Diseases,.
5. 5. Antopolsky, M., Simanovsky, N., Stalnikowicz, R., Salameh, S. and Hiller, N., 2012. Renal infarction in the ED: 10-year experience and review of the literature. The American Journal of Emergency Medicine, 30(7), pp.1055-1060.
6. 6. Eltawansy, S., Patel, S., Rao, M., Hassanien, S. and Maniar, M., 2014. Acute Renal Infarction Presenting with Acute Abdominal Pain Secondary to Newly Discovered Atrial Fibrillation: A Case Report and Literature Review. Case Reports in Emergency Medicine, 2014, pp.1-5.
7. 7. Hazanov, N., Somin, M., Attali, M., Beilinson, N., Thaler, M., Mouallem, M., Maor, Y., Zaks, N. and Malnick, S., 2004. Acute Renal Embolism. Medicine, 83(5), pp.292-299.
8. 8. Piffaretti, G., Riva, F., Tozzi, M., Lomazzi, C., Rivolta, N., Carrafiello, G. and Castelli, P., 2008. Catheter-Directed Thrombolysis for Acute Renal Artery Thrombosis: Report of 4 Cases. Vascular and Endovascular Surgery, 42(4), pp.375-379.
9. 9. Salam, T., Lumsden, A. and Martin, L., 1993. Local Infusion of Fibrinolytic Agents for Acute Renal Artery Thromboembolism: Report of Ten Cases. Annals of Vascular Surgery, 7(1), pp.21-26.
10. 10. Ganju, N., Sondhi, S. and Kandoria, A., 2018. Acute renal artery embolisation: role of local catheter-based intra-arterial thrombolysis. BMJ Case Reports, pp.bcr-2018-224767.
11. 11. Koivuviita, N., Tertti, R., Heiro, M., Manner, I. and Metsärinne, K., 2014. Thromboembolism as a Cause of Renal Artery Occlusion and Acute Kidney Injury: The Recovery of Kidney Function after Two Weeks. Case Reports in Nephrology and Dialysis, 4(1), pp.82-87.
12. 12. Oh, Y., Yang, C., Kim, Y., Kang, S., Park, C., Kim, Y., Lee, E., Han, B., Lee, S., Kim, S., Lee, H. and Lim, C., 2016. Clinical Characteristics and Outcomes of Renal Infarction. American Journal of Kidney Diseases, 67(2), pp.243-250.
13. 13. Hazanov, N., Somin, M., Attali, M., Beilinson, N., Thaler, M., Mouallem, M., Maor, Y., Zaks, N. and Malnick, S., 2004. Acute Renal Embolism. Medicine, 83(5), pp.292-299.