Renal artery embolization is rare and there is a lack of scientific studies on which to base clinical decisions. In this report, a case of bilateral renal artery embolism with a single embolus traversing the aortic lumen is presented for a discussion of the current knowledge and routines for the treatment of renal embolization.

A 58-year-old sedentary man presented to the emergency department with abdominal pain, shortness of breath and swelling of the lower legs. An electrocardiogram showed atrial fibrillation with a frequency of 150-180 beats/min and an echocardiogram showed heart failure with an estimated ejection fraction of 10-15 %.A CT-angiogram of the thorax and abdomen was performed in which the arterial phase showed three segmental lung emboli as well as a single embolus present in both the left and right renal arteries traversing the aortic lumen. The venous phase showed a marked decrease in signal intensity in several parts of the left kidney compared to the right (fig. 1). A diagnosis of acute heart failure, atrial fibrillation, pulmonary and bilateral renal artery embolization was made. Digital subtraction aortography, performed via punction of the right femoral artery, confirmed an embolic occlusion of the main stem of the left and right renal arteries, with some remaining flow in the right renal artery.

A thrombolysis catheter was introduced into the left renal artery and an infusion of recombinant tissue plasminogen activator was started. 24 hours later, a follow up aortography showed dislocation of the catheter into the aortic lumen, no change of the left renal artery occlusion but resolution of the right renal artery sub-occlusion. The catheter was reintroduced into the left renal artery and the infusion was continued. 24 hours later, a follow up aortography showed resolution of the left renal artery occlusion the infusion was discontinued (fig. 2). Systemic treatment with LMWH, dose adjusted using to anti-factor-X activity monitoring, continued until discharge at which point the patient was switched over to an oral anticoagulant. Over the subsequent days the patient was administered diuretics as well as full dose metoprolol and digoxin but the frequency of the atrial fibrillation remained above 100 beats/min. An oesophageal echocardiogram performed under general anaesthesia showed an absence of thrombus in the atria and the patient was successfully electro-converted to sinus rhythm in the same setting and started on a regimen of amiodarone. A subsequent echocardiogram showed an improvement in heart function with an ejection fraction of 25 - 30 %. At discharge, the patient was pain-free and in good spirits. Over the following months the serum creatinine levels decreased but remained elevated at and around 180 mol/L. At a follow up arterial duplex ultrasound, the renal arteries could not be visualized due to the patient's obesity, but bilateral parenchymal flow of the interlobar arteries was normal.

Renal artery embolism (RAE) is considered a rare event and occurs most often in the setting of atrial fibrillation (1). The embolus may completely or partially occlude the renal artery and thus give rise to varying degrees of infarction. The period of occlusion after which renal function can be preserved has often passed by the time the diagnosis is made (2). Yet sometimes renal function can be restored even after longstanding impairment of renal artery flow. Some remaining flow through the main artery, alternative inflow via accessory or capsular arteries are plausible explanations and it has further been observed that a low perfusion pressure, below the requirement for glomerular filtration, can preserve nephron viability due to sub-total occlusion and/or collateral circulation (3-6). Under what flow conditions, collateral or sub-occluded, and how long a kidney can remain viable in an anuric yet "hibernating" state, is an open field of inquiry awaiting further clinical and animal studies.

1. Kansal S, Feldman M, Cooksey S, Patel S. Renal Artery Embolism. J Gen Intern Med. 2008 May;23(5):644-7. 2. Ouriel K, Andrus CH, Ricotta JJ, DeWeese JA, Green RM. Acute renal artery occlusion: When is revascularization justified? J Vasc Surg. 1987 Feb 1;5(2):348-55. 3. Abrams HL, Cornell SH. Patterns of Collateral Flow in Renal Ischemia. Radiology. 1965 Jun 1;84(6):1001-12. 4. Yune HY, Klatte EC. Collateral Circulation to an Ischemic Kidney. Radiology. 1976 Jun;119(3):539-46. 5. Zinman L, Libertino JA. Revascularization of the Chronic Totally Occluded Renal Artery with Restoration of Renal Function. J Urol. 1977 Oct 1;118(4):517-21. 6. Williams B, Feehally J, Attard AR, Bell PRF. Recovery of renal function after delayed revascularisation of acute occlusion of the renal artery. BMJ. 1988 Jun 4;296(6636):1591-2.