Successful endovascular treatment for acute renal artery occlusion

Purpose: We report a case of revascularization for a totally occluded renal artery using endovascular renal thrombus aspiration followed by catheter-directed thrombolysis. Case Report: A 56 years old man presented with sudden onset of severe left-sided abdominal and loin pain for six hours. Urgent computed tomography angiogram showed total occlusion of left renal artery. Emergency selective left renal angiogram and thrombus aspiration using a 5-French Cobra catheter was performed. Catheter-directed thrombolysis with urokinase was initiated after aspiration thrombectomy. Angiogram 24 hours after thrombolysis showed the left renal artery and its segmental branches were successfully revascularized. Patient was on anticoagulation after operation and his renal function recovered well. Conclusion: Percutaneous aspiration thrombectomy combined with intra-arterial local brinolysis are effective in the salvage of renal function.


Introduction
Acute renal embolism (ARE) is an uncommon cause of abdominal and loin pain. Historically, the incidence of acute renal embolism was reported to be 1.4% in 14,411 autopsies. 1 The diagnosis of ARE is often delayed or ignored due to the rarity and unspeci c clinical manifestation of the disease. The treatment options include anticoagulation, 2 with or without thrombolysis, 3 catheter aspiration thrombectomy, 4 or surgical thrombectomy. 5 However, the optimal therapeutic treatment and timing of intervention remain controversial and challenging. This is a case report of a patient with atrial brillation who presented with acute loin pain, and underwent successful revascularization of a totally occluded renal artery with endovascular renal thrombus aspiration followed by catheter-directed thrombolysis.

Case Presentatoin
A 56 years old man presented to accident and emergency department with sudden onset severe left-sided abdominal and loin pain for six hours, associated with nausea and vomiting. The pain was persistent, non-radiating and without relieving factors. He denied any trauma, fever, chills, dysuria or hematuria.
There were no previous similar events or any other symptoms were noted. Past medical history was signi cant for atrial brillation and he was not on any anticoagulation.
He was hypertensive with blood pressure of 156/117mmHg, with an irregular heart rate of 112 beats per minutes on physical examination. There was tenderness in the left lower quadrant and left loin. All the peripheral pulses were palpable. Creatinine was elevated at 113umol/L (normal range, 62-106 umol/L).
Electrocardiogram showed atrial brillation with a heart rate of 112 beats per minute. Urgent computed tomography (CT) angiogram was performed showing hypodensities in the main trunk of the left renal artery, and malperfusion of the left kidney ( Figure 1). The size of the left kidney was the same as the right. Anticoagulation with heparin was used immediately after diagnosis of renal artery thromboembolism.
Emergency selective left renal angiogram via the right femoral access showed total occlusion of the left renal artery and its segmental branches ( Figure 2A). A 5-French Cobra catheter (Cook Medical, United States) was advanced into the left renal artery over a 0.035-inch guidewire. A 20ml syringe was connected to the Cobra catheter to aspirate blood clots from main trunk of the left renal artery. The Cobra catheter was then advanced to the segmental branches and repeated aspiration thrombectomy in the same maneuver was performed. Completion angiogram showed improvement of the blood ow in the main left renal artery with restoration of the majority of the ow to the segmental branches, but there were still some lling defects in the distal arteries ( Figure 2B). With the Cobra catheter placed in the left renal artery, catheter-directed thrombolysis was initiated. Urokinase was infused via the catheter at a rate of 20,000 units per hour using a perfusion pump. The plasma brinogen level, hemoglobin and platelet count were closely monitored during thrombolysis. The patient's left-sided abdominal and loin pain gradually resolved after the procedure. A total of 480,000 units of urokinase was used. No thrombolysis related bleeding was observed, and the patient did not develop haematuria. An angiogram 24 hours later after aspiration thrombectomy showed the left renal artery and its segmental branches were successfully revascularized (Figure 3), and the catheter was removed. Patient was put on anticoagulation using heparin after thrombolysis, and switched to warfarin with a target international normalized ratio of 2.0 to 3.0 upon discharge. Follow-up CT three weeks later showed left renal artery was patent (Figure 4). His renal function recovered well with a creatinine of 104 umol/L (normal range, 62-106 umol/L) at 3 months follow-up.

Discussion
The estimated incidence of ARE is of the range of 0.004-0.007% in the emergency setting. 5,6 The presenting symptom of ARE is usually nonspeci c, including abdominal or ank pain, fever, nausea, vomiting and hematuria. 2, 6 ARE is more frequently detected as incidental nding with the liberal use of contrast-enhanced CT. CT features of renal infarction include wedge-shaped hypodense area of renal parenchyma or global infarction of the kidney, depending on the arteries involved. 7,8 In addition, a rim of capsular enhancement surrounding the infarction area may present on CT, called "cortical rim sign", which is seen predominantly with global renal infarction. 7 In a study of 41 patients with renal artery embolism, the main artery was the most frequent location of embolism, 8 and atrial brillation is the most common etiology of ARE. 9 It was reported that the kidneys can tolerate complete ischemia for 60-90 minutes in human at normothermia. 10 However, in a study reporting 44 cases of renal infarction, more than 80% of the patients presented in excess of 24 hours from onset of symptom. 11 As the kidney receives collateral blood ow from suprarenal, lumbar and ureteral vessels, collateral circulation may be enough to allow the kidney to survive complete obstruction of the main renal artery. 12 To date, there is no consensus or guidelines on the treatment of choice for ARE as the rarity of this disease. The traditional treatment for renal thromboembolism and in situ thrombosis is anticoagulation, with or without thrombolysis and surgical embolectomy. Patients with renal embolism are at risk of recurrent embolic events, including cerebral infarction and superior mesenteric artery embolism. 2,11 The aim of systemic anticoagulation is to prevent further thrombosis or embolism and not to preserve the renal function. Yun et al. 2 reported the long-term results of 47 patients treated with anticoagulation, dialysis-free survival rates were 91%, 82%, and 64% at 1 year, 3 years, and 5 years follow-up. Fort et al. 8 reported their therapeutic protocol with surgery for main renal artery embolism and brinolytics for intrarenal embolism. Nowadays, open surgical thrombectomy has limited indications because of signi cant morbidity and mortality. Catheter directed thrombolysis is being increasing used with satisfactory results as it allows local perfusion of brinolytics, thus reduce the dosage of thrombolytic agents and decrease the risk of bleeding.
With the advances of endovascular technique and technology, new devices have been successfully used in the peripheral vascular territory. Aspiration and rheolytic thrombectomy with the AngioJet catheter (Boston Scienti c, United States) has been used in ARE with good results. 13,14 In our patient, the left main renal artery and its segmental branches were totally occluded. We used percutaneous aspiration thrombectomy to reduce the renal clot burden before catheter directed thrombolysis with urokinase for the treatment of in-situ thrombosis in the distal segmental branches. After 24 hours of thrombolysis, the occluded renal segmental branches were revascularized. The main renal artery and segmental branches remained patent on follow-up CT. Complications of aspiration thrombectomy and thrombolysis include access site complications, distal embolization and bleeding. Plasma brinogen level is often used for thrombolysis dose adjustment to reduce the risk of bleeding. A variety of distal protection devices used in coronary and carotid interventions maybe helpful to minimize distal embolization. 15 Emergent recanalization of the renal artery would theoretically reestablish perfusion to the kidney and therefore prevent renal loss. Early diagnosis is essential, and percutaneous aspiration thrombectomy combined with local brinolysis requires endovascular expertise and experience.

Conclusion
ARE is rare and associated with renal insu ciency. Despite the increasing diagnosis of ARE, the treatment remains challenging. Percutaneous aspiration thrombectomy combined with intra-arterial local brinolysis are effective in the salvage of renal function. Figure 1 Computed tomography angiogram showed obstruction of the left renal artery (White arrow, Figure 1A) and the left kidney was malperfused ( Figure 1B).

Figure 2
Angiogram con rmed total occlusion of the left renal artery (2A). The main trunk and most of the segmental branches were successfully recanalized after percutaneous aspiration thrombectomy, and some lling defects were noted in the distal arteries (2B). Angiogram after catheter directed thrombolysis revealed the left renal artery and its segmental branches were revascularized.