Catheter-delivered Transducer-tipped Ultrasound Thrombolysis of a Chronically Occluded Aortic Stentgraft Limb
Article Outline
Abstract
Endovascular aneurysm repair (EVAR) is increasingly used to treat infrarenal abdominal aortic aneurysm. EVAR is almost exclusively accomplished by using bifurcated, bi-iliac stentgrafts. Nevertheless, it is accompanied with a considerable incidence of stentgraft limb occlusion. In case of acute occlusion endovascular revascularization options are plentiful, but for chronically occluded stentgraft limbs such consensus is lacking. Catheter-delivered transducer-tipped ultrasound (US) thrombolysis is a new technique specifically coined for the treatment of (sub)acute peripheral arterial occlusions and deep venous thrombosis. We describe a unique case of successful treatment of a chronically occluded stentgraft limb after EVAR with catheter-delivered transducer-tipped US thrombolysis.
Keywords: EVAR, Limb occlusion, Thrombolysis, Ultrasound, EKOS
Introduction
Endovascular aneurysm repair is rapidly becoming the standard treatment for infrarenal abdominal aortic aneurysm (AAA). Follow-up studies are recommended however, since there are a substantial number of graft-related complications. One of such adverse events, graft limb occlusion, has been reported to occur in 3.1–7.2% of patients, mostly within one year after EVAR.1 Endovascular revision, consisting of catheter-directed thrombolysis or thrombosuction in combination with percutaneous transluminal angioplasty (PTA) with or without stent placement, has become the preferred treatment in case of acute arterial occlusions.2 If the time of onset is unknown or the occlusion has existed for more than 14 days surgical thrombectomy and/or revision has been recommended.2 If attempted, standard thrombolysis in case of chronic occlusion most likely will require several days of infusion of the thrombolytic agent at high dosage. This treatment carries a significant risk of bleeding complications and probability of incomplete thrombolysis. Catheter-delivered transducer-tipped ultrasound (US) thrombolysis is a new technique that adds a mechanical component to chemical thrombolysis and therefore conceivably could fragment and lyse older thrombi. We present a unique case of a patient with a chronically occluded stentgraft limb after EVAR who was successfully treated by a combination of thrombolysis and US.
Case report
A 55-year old male with a medical history of myocardial infarction, hypertension and coronary artery bypass grafting, underwent an uncomplicated EVAR procedure (Cook, Zenith®) for an asymptomatic infrarenal AAA of 5.6
cm. The stentgraft limbs were placed in non-stenotic common iliac arteries and there was no peripheral arterial occlusive disease. Seven months after EVAR the patient complained of pain in his left foot during walking. Physical examination did not show signs of leg ischemia and all peripheral arterial pulsations were palpable. Furthermore, preoperative CT-scanning and routine postoperative CT-scanning 4 weeks after EVAR had not shown any signs of central or peripheral arterial occlusive disease and therefore a vascular cause of the complaints was not suspected. A neurological cause of the pain was excluded as well. Nine months after EVAR the pain had suddenly worsened and now involved the whole leg and the painfree walking distance had fallen to 50m. However, the patient sought medical attention for this new problem only after another 4 months. Physical examination now revealed absence of arterial pulsations of the left leg. Contrast enhanced CT-scanning showed occlusion of the left limb of the aortic stentgraft (Fig. 1) without signs of migration or kinking. In light of the chronic nature (>4 months) of the occlusion, reopening of the stentgraft limb with standard catheter-directed thrombolysis was not considered a realistic option. Therefore US enhanced thrombolysis was performed. After retrograde access was gained, recanalization of the left thrombosed stentgraft limb was performed with a 0.035-inch angled guidewire (Terumo, Leuven, Belgium) and a 5 Fr. PIER catheter (Cordis, Miami Lakes, FL, USA) and a 5 Fr. C2 Cobra catheter (COOK, Bloomington, IN, USA). Then a 12cm EKOS® drug delivery catheter with a multi-transducer US core wire was inserted in the thrombus (EKOS Corporation, Bothell, WA, USA). A 500,000 IE urokinase bolus was administered followed by a continuous infusion of 100,000IE/h combined with 2.1MHz US. Four hours after initiation of treatment partial dissolution of the thrombus was seen on angiography. After another 16h, angiography showed complete dissolution of the thrombus. Three significant stenotic lesions in the affected stentgraft limb remained, which were all treated by PTA with 12.0×40mm Smash balloons (Boston Scientific, Galway, Ireland). The most proximal stenosis was treated with a kissing balloon technique. The stenoses might have been caused by stentgraft folding due to oversizing, or they might be residual thrombus. Kinking of the stentgraft limb was not found and there were no stenotic lesions in the iliac artery. Completion angiography demonstrated no residual thrombosis or stenosis and therefore no additional stents were inserted (Fig. 2). Total urokinase infusion time was 20h and 34min. Antiplatelet therapy was continued and during follow-up the symptoms had disappeared.
Figure 1
CT-angiography demonstrating occlusion of the left limb of the aortic stentgraft.
Figure 2
Completion angiography after US enhanced thrombolysis and PTA demonstrating no residual thrombosis or stenosis.
Discussion
Treatment of chronic native arterial or graft occlusions with thrombolysis is questionable. Catheter-directed thrombolysis for chronic limb ischemia has a lower success rate and longer duration of infusion than for acute occlusions.3 Incomplete thrombolysis, as well as a high bleeding rate, related to overall dose of the thrombolytic agent and duration of therapy, stimulated research on alternative therapies. The use of US energy to enhance thrombolysis dates back to 1976.4 The exposure to US causes reversible disaggregation of uncrosslinked fibrin bundles into smaller fibres and microcavity formation in the thrombus. This increases penetration of fibrinolytic drugs into the clot and creates additional binding sites for fibrinolytic components, which in turn leads to residual flow enhancement with microstreaming and vessel dilation as well as improvement of fibrinolytic efficacy.5 US energy can be applied by a transcutaneous approach, however catheter-delivered transducer-tipped US thrombolysis is a more innovative method. A number of studies have been published on the effects of transducer-tipped US combined with thrombolysis for lower limb ischemia, deep venous thrombosis and stroke. A reduction of total infusion time of the thrombolytic agent, a greater incidence of complete lysis and a reduction in bleeding rates compared with conventional thrombolysis have been demonstrated.4
We showed that even in the case of chronic occlusion of a stentgraft limb after EVAR, rapid dissolution and reopening of the graft can be achieved with the use of US enhanced thrombolysis.
Conflict of interest
The authors have no conflict of interest.
References
- Limb graft occlusion following EVAR: clinical pattern, outcomes and predictive factors of occurrence. Eur J Vasc Endovasc Surg. 2007;34:59–65
- . Results of a prospective randomized trial evaluating surgery versus thrombolysis for ischemia of the lower extremity: the STILE trial. Ann Surg. 1994;220:251–268
- Comparison of thrombolytic therapy of lower-extremity acute, subacute, and chronic arterial occlusions. Cathet Cardiovasc Diagn. 1998;44:159–169
- . Ultrasound thrombolysis. Ultrasonics. 2008;48:312–320
- . Ultrasound reversibly disaggregates fibrin fibers. Thromb Haemost. 1997;78(3):1063–1068
PII: S1533-3167(10)00002-6
doi:10.1016/j.ejvsextra.2009.12.001
© 2010 European Society for Vascular Surgery. Published by Elsevier Inc. All rights reserved.
Refers to article:
- Catheter-delivered Transducer-tipped Ultrasound Thrombolysis of a Chronically Occluded Aortic Stentgraft Limb , 26 February 2010
