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AORTA, June 2013, Volume 1, Issue 1:59-64
DOI: 10.12945/j.aorta.2013.13.015

Dr. Sun’s Procedure for Type A Aortic Dissection: Total Arch Replacement Using Tetrafurcate Graft With Stented Elephant Trunk Implantation

Wei-Guo Ma, Jun Zheng, Yong-Min Liu, Jun-Ming Zhu, Li-Zhong Sun*

Department of Cardiovascular Surgery, Beijing Anzhen Hospital, Beijing Aortic Disease Center, Capital Medical University, Beijing, China

Abstract

Sun’s procedure is a modified elephant trunk technique that integrates the advantages of open surgical and endovascular repairs as a treatment of type A aortic dissection. It is named after Dr. Li-Zhong Sun and refers to total arch replacement using a four-branched graft with implantation of a special stented endovascular graft. Since its introduction, it has produced excellent early and late clinical outcomes. We present a video of this procedure and make an overview regarding the technical aspects, surgical indications, and clinical outcomes of Sun’s procedure.

Introduction

Acute type A aortic dissection remains the most common of all aortic catastrophes and is associated with significant morbidity and mortality [1], and the time-honored dictum is that urgent surgery should be undertaken [2]. In 1983, Borst introduced the elephant trunk procedure [3], followed by a variety of modifications [46], with improved clinical outcomes over the years [79]. Recently, endovascular placement of stent grafts and hybrid repair have also emerged as new treatment options [10,11]. An ideal therapy should be able to replace the dissected aortic segment as long as possible and obliterate the false lumen, which is essential to minimizing operative risks and avoiding or reducing the need for reinterventions.

In our practice, we have been trying to find a new treatment option that integrates the advantages of open surgical and endovascular repairs. In 2002, the senior author (L.Z.S.), then the chief of Aortic Surgery in Fu Wai Hospital, designed a new stented graft and proposed a modified technique of total arch replacement using a four-branched graft with implantation of this stented elephant trunk as a treatment for type A aortic dissection [12], which has produced satisfactory early and long-term results [1317]. Owing to its ingenious design, widespread usage, and excellent outcomes, this technique was named after Dr. Sun by domestic and international colleagues in 2008, hence the term “Sun's procedure,” i.e., total arch replacement using a tetrafurcate graft with stented elephant trunk implantation [18]. In this paper, we briefly describe Sun's procedure with regard to operative techniques, surgical indications, and clinical outcomes. A video showing the technical details can be accessed at http://dx.doi.org/10.12945/j.aorta.2013.13.015.vid.01, for better understanding of the Sun's procedure.

Surgical Techniques

Sun's procedure encompasses several technical details in terms of cannulation, cardiopulmonary bypass, cerebral protection, and surgical skills [1216]. It is performed via a median sternotomy under total cardiopulmonary bypass (CPB) and selective cerebral perfusion (SCP) with cannulation of the right axillary artery (RAA). The arterial line is bifurcated for perfusing the brain through RAA and the descending, abdominal aorta and lower extremities through one branch of the tetrafurcate graft [12]. If indicated, root procedures are finished during cooling. Circulatory arrest is instituted as the nasopharyngeal temperature reaches 25°C. After the arch vessels are cross-clamped, antegrade SCP through RAA is started. The ascending aorta and transverse arch are opened, and the three arch vessels are transected at their origins from the arch. A stent endograft (Cronus®, Shanghai MicroPort Medical, China) (Fig. 1) is inserted into the true lumen of the descending aorta and deployed to compress the false lumen and, most importantly, to enlarge the true lumen. Then the stented endograft is anastomosed to a four-branched graft (Maquet Cardiovascular, Wayne, NJ) end-to-end. All anastomoses are completed with continuous 4–0 prolene suture without pledgets. The suture line should include the endograft, the native aorta, and the tetrafurcated graft so that all these structures are joined firmly together (Fig. 2). When the distal anastomosis is completed, perfusion of the lower body is resumed through one branch of the tetrafurcate graft, and the CPB flow is gradually returned to 2.0–2.4 L/m2/min.

Figure 1.

The stented elephant trunk, Cronus®, before (A) and after (B) implantation.

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Figure 2.

Schema of Sun's procedure. (A) Insertion of the stented elephant trunk into the descending aorta; (B) Deployment of the stented elephant trunk in the descending aorta; (C) Anastomosis of four-branched graft distally to stented elephant trunk and perfusion of descending aorta restarted; the suture line should include the endograft, native aorta, and tetrafurcated graft, joining all three layers firmly together; (D) Reconstruction of left common carotid artery, SCP continued through RAA and left common carotid artery, and rewarming begins; (E) Anastomosis of four-branched graft proximally to ascending aorta and perfusion to the heart resumed; (F) Reconstruction of the left subclavian artery; (G) Reconstruction of the innominate artery.

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To minimize the time of cerebral and cardiac ischemia, the left common carotid artery is reconstructed first. On completion of anastomosis, rewarming begins, and SCP is continued through the RAA and left common carotid artery. Then, continuity between the tetrafurcate graft and the distal ascending aorta is established. The ascending aorta is declamped and heart beat returns. Finally, the left subclavian and innominate arteries are, in turn, anastomosed to the four-branched graft end-to-end (Fig. 2).

Difficulties may occur during the dissection and immobilization of the left subclavian artery. Great caution must be taken when suturing the distal anastomosis, because bleeding at this site may be very difficult to control afterward.

The core technique of Sun's procedure lies in its unique stented graft, which has the following advantages. First, it can be deployed very quickly, often within seconds, which decreases the technical difficulty and makes the implantation easier, compared with delivery in endovascular and other open repairs. Second, this stented endograft has an extra centimeter of attached regular vascular graft, proximally and distally, to which a conventional hand-sewn anastomosis can be performed. This minimizes the risk of proximal endoleak, eliminates residual dissections in and beyond the arch, and facilitates manipulations in second-stage operations. Third, the stent graft implanted in the descending aorta is 10–12 cm in length. It is strong enough to compress the false lumen and obliterate the intimal tear in the arch and proximal descending aorta, as is the case in the majority of type A dissections. Implantation of this elephant trunk is not associated with paraplegia or malperfusion syndromes and promotes false lumen thrombosis for the length of the stent graft and thrombosis of the entire thoracic aortic false lumen. This may obviate the necessity for surgical reintervention in a substantial proportion of these problematic patients. Finally, with inherently high mechanical strength and long-term durability, this stent graft can tolerate the forces of clamping and all manipulations during second-stage operations very well.

Operative Indications

As our team has gained vast experience since its introduction, the indications of Sun's procedure have evolved considerably [1217,1924]. This, in part, may be ascribed to an algorithm dictating the surgical strategies based on our subcategorization of the Stanford system that divides type A dissections into subtypes according to the aortic root diameter, degree of aortic insufficiency, competency of the sinotubular junction, and the dissection process in the arch and beyond [17].

In our practice, Sun's procedure is chiefly indicated in patients with extensive dilating aortic pathologies (aneurysm and dissection) affecting the ascending aorta, aortic arch, descending aorta, and beyond. Listed below are the most common indications [1217,1924]:

  • (1) type A dissections with the primary entry locating in the arch and descending aorta

  • (2) type A dissections severely involving the arch vessels

  • (3) type A dissections with extensive intimal intussusception

  • (4) Marfan syndrome complicated with type A dissection

  • (5) thoracic aortic aneurysms involving the ascending aorta, arch, and descending aorta

  • (6) some type B dissections, such as those involving the arch, or with concomitant cardiac disease requiring surgical treatment; and complications of endovascular repair for type B dissections, including retrograde type A dissection, endoleak, etc.

Clinical Outcomes

As of January 2013, our team has performed more than 1,000 cases of Sun's procedure, with an in-hospital mortality rate of 4.6% (6% in acute cases versus 2% in chronic cases) and an incidence of second-stage operation of 4% (most seen in Marfan patients). This is one of the lowest recorded in the literature, three- to four-fold lower than most contemporary reports [25]. Complete thrombus formation around the stented graft is observed in 93% of patients, extending to the diaphragmatic level in 70% [16].

At present, nearly 8,000 patients in China have received Sun's procedure as a treatment of aortic dissection or aneurysm (Z.H. Miao, pers. comm., e-mail on February 19, 2013). Cardiac surgeons in South American countries, including Argentina, Brazil, Chile, Ecuador, Uruguay, and Venezuela have successfully treated nearly 200 patients with this procedure. Since 2004, our team has trained over 600 Chinese physicians on Sun's procedure, and spread this technique to more than 70 cardiac centers across China. Between 2009 and 2012, four workshops on Sun's procedure were successfully launched for 117 South American colleagues engaged in the care of patients with aortic disease. Now Sun's procedure is gaining wider acknowledgment in international cardiac surgical community, and “may become the next standard treatment in patients with type A aortic dissection involving repair of the aortic arch” [16].

Acknowledgements

The authors are deeply indebted to Drs. John A. Elefteriades and Bulat A. Ziganshin for their invaluable assistance in narrating and editing the video of Sun's procedure.

References

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    Uchida N, Shibamura H, Katayama A, Sutoh M, Kuraoka M, Ishihara H. Long-term results of the frozen elephant trunk technique for the extensive arteriosclerotic aneurysm. J Thorac Cardiovasc Surg. 2010;139:913–917. DOI: 10.1016/j.jtcvs.2009.08.018
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    Kato M, Matsuda T, Kaneko M, Kuratani T, Mizushima T, Seo Y, et al. Outcomes of stent-graft treatment of false lumen in aortic dissection. Circulation. 1998;98:II305-II311; discussion II11-2.
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    Sun LZ, Qi R, Zhu JM, Liu YM, Zheng J. Total arch replacement combined with stented elephant trunk implantation: A new “standard” therapy for type a dissection involving repair of the aortic arch?Circulation. 2011;123:971–978.
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    Zhu XD. Preface. In: Sun LZ, Zhu JM, Liu YM, Fan ZM, Huang LJ, eds. Surgery of the Aorta. 1st ed. Beijing: People's Medical Publishing House. 2012;5.
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    Sun LZ, Qi R, Chang Q, Zhu JM, Liu YM, Yu CT, et al. Surgery for Marfan patients with acute type A dissection using a stented elephant trunk procedure. Ann Thorac Surg. 2008;86:1821–1825. DOI: 10.1016/j.athoracsur.2008.08.026
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Editor's Comments And Questions

The Sun's technique described in the paper by Ma and colleagues reflects an innovative and imaginative enhancement of surgical options for the dissected (or aneurysmal) ascending aorta and arch. This procedure, described clearly in this article by the originators, is becoming increasingly widely applied globally.

Questions

  1. Congratulations on this important, innovative addition to our surgical armamentarium. The list of potential indications you provide encompasses almost all ascending and arch pathologies. Do you do a simple ascending replacement for any patients?

In our practice, we subcategorize type A dissections into simple and complex subtypes. Complex subtype refers to either of the following conditions: 1) the primary tear is located in the transverse arch or descending aorta; 2) dilatation of the arch or distal aorta (diameter >50 mm); 3) involvement or dilation of the arch vessels; 4) Marfan syndrome. We would recommend the Sun's procedure for patients with complex type A dissections. Other conditions belong to the simple subtype, which is treated with root or ascending replacement procedures. A detailed description of our subcategorization system was published in the April issue of the Annals of Thoracic Surgery in 2011 [Repair of acute type A dissection: Our experiences and results. Ann Thorac Surg. 2011;91(4):1147–1152].

In cases when we do simple ascending aortic replacements for patients with type A dissections, the selection criteria should include the following conditions simultaneously: 1) the tear is located in the ascending aorta; 2) the arch vessels are not involved; 3) the aortic arch is not dilated; and 4) non-Marfan etiology.

  1. For a type A dissection in a non-Marfan patient with the tear located in the ascending aorta, do you still perform your more extensive procedure?

Based on the reasoning stated above, for a type A dissection in a non-Marfan patient with the tear located in the ascending aorta, we will not perform this more extensive procedure. Instead, we will perform an ascending aortic replacement as long as the arch is not dilated.

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Cite this article as: Ma W, Zheng J, Liu Y, Zhu J, Sun L. Dr. Sun’s Procedure for Type A Aortic Dissection: Total Arch Replacement Using Tetrafurcate Graft With Stented Elephant Trunk Implantation. AORTA (Stamford). 2013;1(1):59-64. DOI: 10.12945/j.aorta.2013.13.015

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All comments will be screened and reviewed before posting. Statements, opinions, and results of studies published in AORTA Journal are those of the authors and do not reflect the policy or position of The Journal and Science International and the Editorial Board and provides no warranty as to their accuracy or reliability. Material is copyrighted and owned by Science International and cannot be used without expressed permission.
abdallah alameddine — Aug 1, 2013 12:31 PM
baystate medical center — cardiac surgery — springfield, ma  us
How much time (range) does it take for the Cabrol fistula to close? How difficult is doing a reop after such a procedure?
Wei-Guo Ma — Aug 4, 2013 4:05 AM
Yale University School of Medicine — Aortic Institute — New Haven, CT  United States
Dear Dr. Alameddine, Thank you for your interest and inquiry. Our answer to your first question is that, as a routine, every patient we operate on will have a CTA scan before discharge, mostly at 7-10 days postoperatively. In more than 90% of patients, the Cabrol fistula closes at this time, as evidenced by the fact that no contrast can be found in the perigraft space on CT scan. Your second question raises an important point. The mean age of our patients is 45 years, and the Sun’s procedure is aimed at eliminating the need of redo operations on the aortic arch, its branches and the descending aorta through a repeat median sternotomy. We have achieved this goal to a large extent, and as a result, the incidence of reoperation after the Sun’s procedure is low. Most patients requiring a reoperation are Marfan in etiology and need mitral or aortic valve replacement. We would perform these redo operations through a repeat median sternotomy or a right thoracotomy, with cannulation of the femoral artery and the superior vena cava, or the femoral or internal jugular veins. Our limited experience in less than 20 patients has shown that doing a reoperation after the Sun’s procedure is not more technically difficult and does not carry higher surgical risks than ordinary redo cardiac procedures. Thank you again for your questions.