Combined Surgical and Endovascular Treatment of Aortic Type A Dissection

Combined Surgical and Endovascular Treatment of Aortic Type A Dissection

Combined Surgical and Endovascular Treatment of Aortic Type A Dissection Aristotelis Panos, MD, Afksendiyos Kalangos, MD, Panayiotis Christofilopoulos...

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Combined Surgical and Endovascular Treatment of Aortic Type A Dissection Aristotelis Panos, MD, Afksendiyos Kalangos, MD, Panayiotis Christofilopoulos, MD, and Gregory Khatchatourian, MD

Purpose. We describe a combined approach for treatment of a type A aortic dissection with surgical repair of the ascending aorta and transluminal stenting of the descending aorta, therefore minimizing the consequences on the untreated aortic arch and descending aorta. Description. From December 2002 to June 2003, 5 consecutive patients (4 men, 1 woman) suffering from type A aortic dissection were treated with resection of the ascending aorta or aortic hemi-arch. Before the open distal aortic anastomosis the Endofit endovascular graft (Endomed Inc, Phoenix, AZ), was deployed under direct vision distally to the origin of the left subclavian artery. Evaluation. Intraoperative stent graft placement was successful in all patients. There was no hospital mortality. Early results were satisfactory with a completely thrombosed false lumen in 2 patients and a partially thrombosed false lumen in 3 patients, 10 days after operation. Follow-up computed tomographic scan showed a completely thrombosed false lumen in 4 patients and a partially thrombosed false lumen in 1 patient. Conclusions. This study shows that combined surgical and endovascular treatment of acute type A dissection is a feasible option, but further evaluation is necessary. (Ann Thorac Surg 2005;80:1087–90) © 2005 by The Society of Thoracic Surgeons

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tandard treatment for type A aortic dissection consists of replacing the ascending aorta and a variable portion of the aortic arch in order to prevent lethal complications such as aortic rupture, cardiac tamponade, aortic regurgitation, and myocardial infarction. Conventional surgical treatment, when limited to the ascending aorta, does not satisfactorily resolve the problem of chronic enlargement of residual dissection in the aortic arch and descending aorta. Previous studies demonstrated that patients operated on for type A dissection [1–3] had to undergo surgery of the aortic arch or the descending aorta, or both, because of secondary aneurysmal formation within 40 to 50 months after the initial surgical intervention. In an effort to reduce this risk and therefore improve long-term outcome, we adopted a more aggressive combined surgical approach with resection of the ascending aorta or hemi-arch and endovascular stent deployment within the proximal segment of the descending aorta.

Technology From December 2002 to June 2003, 5 consecutive patients (4 men, 1 woman), with type A acute aortic dissection were treated by the combined approach. All patients had operations on an emergency basis immediately after diagnosis. Mean age was 53.7 ⫾ 11.86 years. Four patients had a history of hypertension and 1 was diagnosed with Marfan’s syndrome. No patient had previously undergone cardiac surgery. Two patients were found to have severe aortic regurgitation and 1 patient presented cardiac tamponade. Preoperative evaluation included a computed tomographic (CT) scan and echocardiography. A CT scan revealed type A aortic dissection involving the descending aorta with circulating false lumen in all patients. In 2 patients the dissection extended into the right common carotid artery without any neurologic symptoms. All 5 patients had CT scans preoperatively and 10 days postoperatively. Follow-up CT scans was respectively done for these 5 patients at 15, 13, 13, 10, and 9 postoperative months.

Accepted for publication Sept 24, 2004.

Description of the Endograft

Address reprint requests to Dr Panos, Clinic for Cardiovascular Surgery, University Hospital of Geneva, 24, rue Micheli-du-Crest, 1211 Geneva 14, Switzerland; e-mail: [email protected].

The Endofit endoluminal aortic stent graft (Endomed Inc, Phoenix, AZ) (Fig 1) consists of a single polytetrafluoroethylene graft encapsulating circumferential Z-shaped

© 2005 by The Society of Thoracic Surgeons Published by Elsevier Inc

0003-4975/05/$30.00 doi:10.1016/j.athoracsur.2004.09.056

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Clinic for Cardiovascular Surgery, Department of Surgery, University Hospital of Geneva, Geneva, Switzerland

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Fig 1. The EndoFit endoluminal stent-graft (Endomed, Inc, Phoenix, AZ) in one of the dimensions (length, 14 cm; internal diameter, 30 mm) was used in our study. NEW TECHNOLOGY

nitinol rings along its length. There is no longitudinal support along the length of the graft, as the Z-rings are not linked together. The Endofit graft (Endomed Inc) is supplied within a 22-French sheath. We have always used the same 14-cm length stent but in different diameters. The device has not yet qualified for Food and Drug Administration approval, but it bears the European Commission (EC) seal.

Technique Patients were immediately transferred to the operating room once diagnosed. A median sternotomy was performed, cardiopulmonary bypass was installed through the right axillary artery, and the right atrium and body temperature were cooled to a mean temperature of 26°C (range, 25°C to 27°C). During the process of body cooling, the aortic arch and neck vessels were prepared for control. The aorta was cross-clamped and cold blood cardioplegia was delivered in a retrograde manner to achieve cardiac arrest. The ascending aorta was incised and inspected for proximal extension of the dissection and presence of entry tears. The dissected aorta was transected proximally according to the lesions, and the diseased aortic wall was reinforced with Teflon felt strips (Bard Inc, Covington, GA) and biological glue. The aortic valve cusps were re-suspended, and the native valve was preserved in all patients. A gelatin-coated Dacron tube graft (InterVascular Inc, LaCiotat, France) was anastomosed proximally to the ascending aorta in the usual way with 4 – 0 polypropylene sutures. After completing the proximal anastomosis on the ascending aorta, and while body temperature had reached a mean of 26°C, the flow rate of the cardiopulmonary bypass was decreased. The three neck vessels were clamped individually and the aortic cross clamp was released. During this period of systemic circulatory arrest, the brain was continuously perfused through the right axillary artery to a rate flow of 10 mL/kg/min. At this time, the stent was deployed, irrespective of any re-entries into the descending aorta, under direct vision, to ensure that the proximal end of the stent was placed just distal to the origin of the left subclavian artery. For each patient, the selected stent diameter was determined by adding 30% to the diameter of the aorta at the intended level of placement measured on the CT scan or transesophageal echocardiography.

Fig 2. The operation completed with the Dacron tube (T) (InterVascular Inc, LaCiotat, France) replacing the ascending aorta and the stent graft (S) in place into the proximal descending aorta.

The inserted stent graft diameters were 30 mm in 2 patients, 28 mm in 1, and 26 mm in 2. In the first 2 patients, the cartridge containing the stent graft was introduced through the opened proximal descending aorta and the stent was deployed. Because the cartridge is rigid, the stent graft was loaded in an introducer of 24 French and was advanced through a previously inserted stiff guidewire at the intended site of deployment in the remaining 3 patients. After the stent graft was deployed, the distal anastomosis was performed between the Dacron tube graft and the native aorta without incorporating the endovascular stent into the suture line (Fig 2). The air was removed from a cannula that was placed on the anterior aspect of the tube graft; systemic perfusion resumed and the three clamps on the aortic arch vessels were released. The operation was completed in the usual way.

Clinical Experience There was no intraoperative deaths and no hospital deaths. All 5 patients had an uneventful postoperative course. No transitory or permanent neurologic deficit was observed. Mean intensive care unit stay was 2.4 days (range, 1 to 4 days). Mean cardiopulmonary bypass time was 203 ⫾ 76 minutes, with a mean circulatory arrest time of 30.8 ⫾ 12.67 minutes. The procedure of stent graft insertion and deployment during the period of hypother-

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the false lumen on echographic control at the time of hospital discharge.

Fig 3. Computed tomographic scan at 15 months follow-up showing the two aspects of the combined treatment. The standard graft (A) and the endograft (B) fully expanded and an inexistent false lumen.

mic systemic circulatory arrest ranged from 7 to 14 minutes (mean, 10 minutes). In all patients, the aortic valve was preserved and the stent graft deployment was successful. Postoperative echocardiography showed only mild aortic regurgitation in 2 patients and no regurgitation in the other 3 patients. Follow-up period ranged from 9 to 15 months (mean, 12 months). A CT scan was performed on postoperative day 10 and revealed a completely thrombosed false lumen in 2 patients (40%) and a partially thrombosed false lumen in 3 patients (60%). For each of the 5 patients, a follow-up CT scan was done at 15, 13, 13, 10, and 9 months, respectively, and these scans subsequently showed a completely thrombosed false lumen (Fig 3) in 4 patients (80%) and a partially thrombosed false lumen in 1 patient (20%) (Fig 4). No patients demonstrated any enlargement of the descending aorta. The 2 patients who had presented with dissections extending to the right carotid artery showed thrombosis of

Fig 4. Computed tomographic scan at 13-month follow-up showing circulating false lumen (arrow) still and a partially expanded stent graft.

Despite successful repair of the ascending aorta and aortic arch, most patients with type A aortic dissection are left with a circulating false lumen in the aortic arch and descending aorta. Results have shown a persistent patent false lumen in 60% to 80% of patients treated by conventional methods [1–3]. Within 5 years of the acute event, 20% of these patients will require surgery for aneurysmal dilation of the aortic arch or descending thoracic aorta [4], or both, with significant morbidity and mortality rates [5, 6]. The purpose of this combined technique is to achieve both (complete closure of the entry sites in the ascending aorta and aortic arch by open repair) and to treat the remaining dissected aortic arch and proximal descending aorta with transluminal stent graft deployment. The false lumen is compressed by the expandable stent graft against the aortic wall, which may contribute to its thrombosis. Our results show that the combined surgical and endovascular treatment of acute type A dissection is feasible without added morbidity and mortality. It also provided good results, as 4 of 5 patients (80%) presented secondary thrombosis of the false lumen. However, extrapolating these results to a larger population is not safe and conclusions may be erroneous. Fleck and colleagues [7] achieved partial thrombosis of the false lumen in 4 patients and complete thrombosis in 2 patients. Jazayeri and colleagues [4] reported two successful cases. Kato and colleagues [8] reported 80% of completely thrombosed false lumen 6 months after surgery in a series of 15 patients. In our series we deliberately oversized the selected stent diameter by 30% with respect to the size of the proximal descending aorta as measured by CT scan or transesophageal echocardiography. We believe this oversizing is crucial to obtain the maximal expanding radial force against the wall of the dissected aorta, which we hope will minimize the circulation in the false lumen and promote healing of the aorta. In our study, we chose not to expand the stent graft with a balloon in fragile aortic tissues, which could be hazardous. Other authors have reported their experience with balloon dilation but did not achieve better results of long-term thrombosis rates of the false lumen [7]. The third patient in our series, who underwent a hemi-arch replacement, conserved a circulating false lumen (Fig 3). Two probable causes that have been proposed to explain this are a residual entry site in the arch, descending aorta or neck vessels, or leakage from the distal anastomosis irrigating the false lumen. These problems could be resolved by the use of stent grafts developing increased radial expansion force and modification in the way of clamping the diseased vessels. Indeed the cross clamping can create intimal tears that may continue to irrigate the false lumen preventing it from thrombosing. In our study, stent graft insertion and deployment was accomplished in 7 to 14 minutes (mean, 10 minutes) during the period of systemic circulatory

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Comment

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arrest. This method did not markedly prolong the circulatory arrest time of 30.8 ⫾ 12.67 minutes. In our opinion, easier deployment of the stent graft could be achieved if the stent graft was pre-loaded in a flexible, short introducer sheath. Deploying the stent graft within the true lumen of the descending aorta is facilitated by direct vision from the open aorta. Inserting the stent under direct vision also minimizes the risk of aortic perforation. Other authors [4, 7, 8] have not reported this type of complication either. With our approach, there may be some risk of intimal trauma because of the continuous compression of the stent graft on the dissected and weakened intimal wall, but in the small number of recent reports of stent graft placement for acute aortic dissection; there was no report about this concern. However, one may argue the value of this procedure, which serves as prophylactic treatment while adding a supplementary risk to an already complex procedure with a high mortality rate. Fortunately, we did not experience any aortic perforation or malperfusion syndrome, but this cannot be taken for granted with such a small number of patients. Indeed, as with the conventional surgical treatment of aortic dissection, an eventual malperfusion syndrome during the operation is unfortunately unpredictable. Further studies are necessary to evaluate the risk of these complications. In conclusion, our preliminary experience suggests that the combined surgical and endovascular treatment of acute type A dissection is a feasible option and that this procedure may provide a potential benefit in terms of false lumen thrombosis. These results are encouraging, but long-term and large scale studies are necessary to demonstrate the effectiveness of this combined treatment.

Phoenix, AZ) is completely reimbursed by the patient’s insurance company. The authors had full control of the design of the study, methods used, outcome measurements, analysis of data, and production of the written report.

Disclosures and Freedom of Investigation None of the authors nor the institution were linked in any way to Endomed, Inc. The Endofit device (Endomed, Inc,

References 1. Juvonen T, Ergin M, Galla JD et al. Risk factors for rupture of chronic type B dissections. J Thorac Cardiovasc Surg 1999;117: 776 – 86. 2. Genoni M, Paul M, Jenn R, Gravcs K, Seifert B, Turina M. Chronic beta blocker therapy improves outcome and reduces treatment costs in chronic type B dissection. Eur J Cardiothorac Surg 2001;19:606 –10. 3. Fann J, Smith J, Miller D, Mitchell RS, Moore KA, Grunkemeier G. Surgical mamagement of aortic dissection during a 30-year period. Circulation 1995;92 (Suppl II):113–21. 4. Jazayeri S, Tatou E, Gomez M, et al. Combined treatment of aortic type A dissection: ascending aorta repair and placement of a stent in the descending aorta. Heart Surg Forum 2003;6(5):387–9. 5. Genoni M, Kunzli A, Niederhauser U. Early results in the treatment of type B aortic dissection. Schweiz Med Wochenschr 1997;127:208 –13. 6. Juvonen T, Ergin A, Galla J, et al. Prospective study of the natural history of thoracic aortic aneurysms. Ann Thorac Surg 1997;63:1533– 45. 7. Fleck T, Hutschala M, Czerny M, Erlich M, et al. Combined surgical and endovascular treatment of acute aortic dissection type A: preliminary results. Ann Thorac Surg 2002;74: 761– 6. 8. Kato M, Kuratani T, Kaneko M, Kyo S, Ohnishi K. The results of total arch graft implantation with open stent-graft placement for type A aortic dissection. J Thorac Cardiovasc Surg 2002;124(3):531– 40.

Disclaimer The Society of Thoracic Surgeons, the Southern Thoracic Surgical Association, and The Annals of Thoracic Surgery neither endorse nor discourage use of the new technology described in this article.

INVITED COMMENTARY This is an interesting article that suggests a policy change in the surgical treatment of type A dissections [1]. As the majority of cardiovascular surgeons use the “open distal” anastomotic technique, this prophylactic approach to close distal tears with endovascular stents in descending aorta seems reasonable. For type B dissections with retrograde dissection to the ascending aorta, this technique is appropriate and unique. The practical problems with routine use of this procedure are the necessity to identify true and false lumens and to know if there are visceral vessels arising from the false lumen. Closure of descending tears could exclude flow to false lumen and cause ischemia.

© 2005 by The Society of Thoracic Surgeons Published by Elsevier Inc

Enio Buffolo, MD, PhD São Paulo Federal University R. Borges Lagoa, 1080-CJ 701 São Paulo SP Cep 04038-002, Brazil e-mail: [email protected]

Reference 1. Panos A, Kalangos A, Christofilopoulos P, Khatchatourian G. Combined surgical and endovascular treatment of aortic type A dissection. Ann Thorac Surg 2005;80:1087–90.

0003-4975/05/$30.00 doi:10.1016/j.athoracsur.2004.11.053