Emergency Endovascular Treatment for Ruptured Type B Dissection in the Abdominal Aorta

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1 Brief Reports Emergency Endovascular Treatment for Ruptured Type B Dissection in the Abdominal Aorta Mikolaj Wojtaszek, MD, PhD, Krzysztof Milczarek, MD, PhD, Jacek Szmidt, MD, PhD, and Olgierd Rowinski, MD, PhD Despite successful endograft placement in the thoracic aorta, dissections remain problematic in the abdominal aorta. Herein, the authors describe two successful cases of endovascular treatment of ruptured abdominal aortic dissections. One patient, despite previously undergoing successful thoracic endograft placement, presented with a ruptured false channel and was treated by excluding major re-entries with a covered renal stent and stent-graft limb. A second patient, with a ruptured dissection superimposed on a preexisting abdominal aortic aneurysm, was treated with thoracic and abdominal stent-grafts. In both patients, progressive healing of the aorta occurred, with patients presenting no symptoms at an average follow-up of 20 months. J Vasc Interv Radiol 2009; 20: Abbreviations: AAA abdominal aortic aneurysm, DSA digital subtraction angiography From the 2nd Department of Clinical Radiology (M.W., K.M., O.R.) and the Department of General, Vascular, and Transplant Surgery (J.S.), Medical University of Warsaw, Banacha 1a St, Warsaw, Poland. Received March 20, 2008; final revision received February 19, 2009; accepted February 21, Address correspondence to M.W.; nwojtaszek@gmail.com None of the authors have identified a conflict of interest. SIR, 2009 DOI: /j.jvir ACUTE aortic dissection is a lifethreatening disease. The most important clinical problems associated with it include aneurysmal expansion of the false lumen and compression of the true lumen, which complicates aortic dissection by symptomatic peripheral organ ischemia. The main goal of endoluminal stent-graft placement for type B dissection is to seal the primary tear, re-establish the collapsed true lumen, and resolve end-organ ischemia due to dynamic branch vessel compromise if present. However, despite successful endograft placement in the thoracic aorta, in some cases the problem of dissection remains on the abdominal level of the aorta. Until now, few articles have been published that describe the use of stent-grafts in an emergency setting to treat the ruptured false lumen of the thoracic aorta in patients with type B dissection (1 3). Even less literature is available on endovascular repair of a ruptured false lumen in the infrarenal aorta. Herein, we report our unique experience with emergency endovascular repair in two patients presenting with a ruptured false lumen in the abdominal region of the aorta. CASE REPORTS This retrospect study was approved by the Medical University of Warsaw Review Board in accordance with the guidelines established by the Declaration of Helsinki on ethical principles for medical research involving human subjects. Patient 1 A 73-year-old woman was admitted to our department with acute, severe abdominal pain and signs of hypovolemia. Two and half years earlier, she had undergone stent-graft implantation in the descending thoracic aorta at the level of an entry tear of a type B aortic dissection. The postoperative period was uneventful, with no signs of false lumen expansion of the abdominal aorta at follow-up computed tomography (CT). Upon admission, emergency multidetector CT demonstrated rupture of the false lumen in the infrarenal portion of the aorta with a large retroperitoneal hematoma (Fig 1a, 1b). The right renal artery extended from the false lumen, with its detached ostium forming a substantial entry site (Fig 1c). The left renal artery was supplied exclusively by the true lumen. Distally, the false lumen remained patent throughout the infrarenal aorta and ended in the right external iliac artery at the level of the distal re-entry. The patient was immediately transferred to the operating theatre, where an endovascular procedure was performed with the patient under regional anesthesia with use of a mobile digital subtraction angiography (DSA) C-arm (OEC 9600; GE Medical Systems, GE International, Poland) by a team of interventional radiologists and vascular surgeons. 807

2 808 Endovascular Treatment for Ruptured Type B Aortic Dissection June 2009 JVIR Figure 1. (a,b) MRI images show a ruptured false lumen of the infrarenal aorta with retroperitoneal hematoma. (c) CT image shows a detached ostium with the right renal artery arising from the false lumen. For stent-graft insertion, a standard surgical arteriotomy was performed and a 9-F introducer sheath inserted into the right common femoral artery. For monitoring, device deployment a 5-F pig-tail catheter was positioned in the abdominal aorta at the level of the renal arteries through a left femoral percutaneous access. After initial DSA of the abdominal aorta, 5,000 units of heparin were administered intravenously. At first, a covered stent (Wallgraft 6/30 mm; Boston Scientific/ Meditech, Newton, Massachusetts) was advanced and deployed across the detached ostium of the right renal artery in such a way that its proximal end extended into the true lumen and the distal end was expanded in the healthy portion of the renal artery (Fig 2a). Angiography revealed incomplete sealing at the level of the detached ostium. The resulting inflow to the false lumen, however, was significantly de-

3 Volume 20 Number 6 Wojtaszek et al 809 Figure 2. (a,b) CT images show contained rupture and persistent minute inflow to the false lumen after placement of two covered stents across the detached ostium of the right renal artery (a) and in the right iliac artery (b). (Available in color online at creased. To close the second prominent entry site, the distal re-entry, a standard Zenith stent-graft limb extension (Cook Medical, Bloomington, Indiana) was used. The stent-graft was advanced over a Lunderquist Extra Stiff guide wire (Cook Medical) and deployed, covering the entire common iliac artery, the internal iliac artery ostium, and a proximal portion of the external iliac artery. Final DSA showed complete exclusion of the distal re-entry and good stent-graft patency. The patient recovered uneventfully. A follow-up CT scan obtained before discharge demonstrated the contained rupture and limited inflow to the false lumen at a level beneath the right renal artery, which appeared to arise from incomplete sealing of the covered stent and/or a very discrete entry at the level of a right lumbar artery (Fig 2b). Three months later, a control CT scan demonstrated near-complete regression of the retroperitoneal hematoma despite persistent minute inflow into the false lumen. The patient was lost to follow-up after coming in for CT 16 months after the procedure. She was free from pain, and the scan revealed stable aortic disease. Patient 2 A 78-year-old man with a chronic history of abdominal aortic aneurysm (AAA) less than 5 cm in diameter was admitted to our hospital with acute abdominal pain and signs of hypovolemic shock. Emergency multidetector CT revealed an acute aortic dissection superimposed on a pre-existing abdominal aneurysm with a ruptured infrarenal false lumen and retroperitoneal extravasation of contrast medium (Fig 3a, 3b). The dissection extended from the left subclavian artery to the right common iliac artery, sparing the extremely tortuous left iliac arteries. There were two major entry sites: distally to the origin of left subclavian artery and in the right iliac artery. Both renal arteries arose from the true lumen. The patient was immediately referred to the operating theatre equipped with a mobile DSA C-arm (OEC 9600). The procedure was performed with the patient under general anesthesia with use of a bilateral surgical femoral access. Heparin (5,000 units) was used to ensure intraoperative anticoagulation. The right femoral access was used to insert both the thoracic and abdominal stent-graft. A straight tube Zenith TX2 endovascular graft (Cook) was advanced and deployed just distally to the origin of the left subclavian artery, and a second unilateral abdom-

4 810 Endovascular Treatment for Ruptured Type B Aortic Dissection June 2009 JVIR Figure 3. (a) Volume-rendered CT image shows acute aortic dissection superimposed on a preexisting AAA with rupture of the false lumen in the infrarenal region. (b) CT image shows retroperitoneal hematoma with contrast medium extravasation. There was complete exclusion of the major entry sites with thoracic (not shown) and unilateral abdominal stent-grafts. (c) CT image shows inflow to the true lumen of the AAA via the inferior mesenteric artery, corresponding with a type II endoleak. (Available in color online at inal Zenith stent-graft with suprarenal fixation and limb extension was advanced and deployed with a standard technique. Dilation was performed with a latex balloon at the fixation sites to obtain optimal sealing. The final DSA showed complete exclusion of the dissection in the infrarenal aorta, albeit revealing a discrete endoleak at the level of the right iliac arteries that was left for observation. Blood perfusion to the left limb was restored with a femorofemoral bypass graft (Gore-Tex Stretch Vascular Graft, 5 mm; W. L. Gore and Associates, Flagstaff, Ari-

5 Volume 20 Number 6 Wojtaszek et al 811 zona) with the proximal left common femoral artery ligated above the anastomosis. A control CT scan, obtained the following day, demonstrated a type III endoleak due to incomplete sealing between the abdominal stentgraft and the extension limb. The patient underwent a secondary procedure, during which an additional short segment was expanded to exclude the type III endoleak. Three months later, a control CT scan showed regression of the retroperitoneal hematoma and a type II endoleak into the true lumen of the AAA through a patent inferior mesenteric artery (Fig 3c). Signs of aortic remodelling were present, with adequate sealing below the renal arteries and complete exclusion of the false lumen in the infrarenal aorta. After 25 months of follow-up, there is no increase in aneurysm diameter and the patient remains free of pain. DISCUSSION It is widely accepted that only complicated or unstable type B dissections require intervention (4 6). Other cases are usually managed conservatively with hypotensive medical therapy consisting of -blockers, followed by vasodilators such as nitroglycerin or nitroprusside, and analgesics to control pain. Surgery is reserved for patients who fail aggressive medical therapy or those who present with complications such as organ or limb ischemia, rupture, impending rupture, or progression of aneurysmal dilatation. Open surgery in these cases is burdened with a very high mortality rate ranging from 35% to 69% in patients with acute disease and end-organ ischemia (7). Due to the ineffectiveness of open repair, endovascular treatment is rapidly gaining popularity, offering a substantially lower mortality rate of 3% 9% (8). The main goal of endovascular repair is to exclude the primary dissection tear and, optimally, allow the dissected aorta to heal and the false lumen to thrombose and retract. However, thrombosis of the false lumen will usually extend only to the next major re-entry tear. In most cases, the dissected aorta remains unchanged distally to this major re-entry with the false lumen patent and prone to dilatation and rupture (9 11). The co-occurrence of dissections and dilatation of the thoracic aorta is well recognized, but few comparable clinical data exist regarding dilatation of the abdominal aorta. There is every reason to assume that risk factors involved are the same as those for aneurysmal dilatation of the dissected descending thoracic aorta. These include older age and uncontrolled hypertension. According to different authors (12,13), the estimated risk of false lumen expansion with formation of an aneurysm in the descending aorta ranges from 14% to 30%. Mohr-Kahaly et al (14) suggest that the diameter of the affected aorta will increase by 5 20 mm every 3 years. Unfortunately, no studies have been published comparing the expansion rates in the thoracic and abdominal aorta. Herein, we presented two unique cases of endovascular treatment of ruptured dissections in the abdominal aorta. Patient 1 had chronic type B dissection and poorly controlled hypertension and had undergone thoracic stent-graft implantation 32 months before rupture. Patient 2 presented with a ruptured aortic dissection superimposed on a pre-existing uncomplicated AAA. The use of an abdominal stentgraft to treat the ruptured false lumen in the setting of the infrarenal aorta is challenging and requires a proximal neck sufficient to permit sealing. Such treatment is possible when both renal arteries are supplied exclusively from the true lumen, and reattachment of the dissection membrane in the infrarenal portion of the aorta is feasible. A thin membrane in an acute dissection is more likely to reattach, as in patient 2. In patient 1, the right renal artery arose from the false lumen and the detached ostium caused significant communication between the two lumens. Such morphology disqualified the use of an abdominal stent-graft due to high probability of inflow to the false lumen through this entry site. In this case, the treatment goal was to exclude the major entry tear at the level of the renal arteries and the distal re-entry tear at the level of the iliac arteries to prevent retrograde filling of the false lumen. A covered stent was deployed and satisfactory sealing across the detached renal artery ostium was achieved, probably due to the rigid membrane of the chronic aortic dissection. However, the minute yet persistent filling of the false lumen could in the long term have led to secondary aortic rupture and patient loss on follow-up. Even though endovascular therapy is now the method of choice in the treatment of complicated aortic dissections, it remains largely untested when dealing with such complications as false lumen rupture in the abdominal region of the aorta. In such cases, most patients present with multiple re-entry points in the visceral region, meaning that complete endovascular repair is seldom easy and often nigh on impossible (15). Until longer-term follow-up data are available for a greater number of patients, total surgical reconstruction or hybrid procedures should be recommended whenever possible, leaving endovascular procedures as a last resort for patients whose comorbidities are too grave for open surgery. References 1. Caronno R, Piffaretti G, Tozzi M, et al. Emergency endovascular stent-graft treatment for acute thoracic aortic syndromes. Surgery 2006; 140: Duebener LF, Lorenzen P, Richardt G, et al. Emergency endovascular stent grafting for life threatening acute type B aortic dissection. Ann Thorac Surg 2004; 78: Doss M, Balzer J, Martens S, et al. Emergent endovascular stent grafting for perforated acute type B dissections and ruptured thoracic aortic aneurysms. 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