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ORIGINAL ARTICLE |
Division of Thoracic and Cardiovascular Surgery Department of Bioregulatory Medicine Faculty of Medicine, University of the Ryukyus Okinawa, Japan
Satoshi Yamashiro, MD Tel: +81 98 895 1168 Fax: +81 98 895 1422 Email: y3104{at}med.u-ryukyu.ac.jp, Thoracic and Cardiovascular Surgery Division, University of the Ryukyus, 207 Uehara, Nishihara, Okinawa 903-0215, Japan.
ABSTRACT
Prevention of cerebral injury is an important consideration during repair of aortic arch aneurysm, and the major goal of cerebral protection techniques. We describe our surgical strategy for treatment of extended thoracic aortic aneurysms. Between January 2001 and June 2008, 17 men and 6 women, with a mean age of 67.9 ± 8.3 years, underwent total replacement of the arch and descending aorta. Six (26.1%) patients required emergency surgery. A median sternotomy with a left anterolateral thoracotomy provided a good visual field, and bilateral axillary arteries were preferentially used for systemic as well as selective cerebral perfusion. Two (8.7%) patients died in hospital. Prolonged mechanical ventilation was required for 7.3 ± 8.4 days after surgery in 17 patients who all recovered uneventfully. Permanent neurological dysfunction developed in 1 (4.3%) patient who died of sepsis 2 years after the operation. Our results suggest that total arch replacement through a median sternotomy plus a left anterolateral thoracotomy is helpful for extended replacement of the thoracic aorta as well as distal reoperation for dissecting type A aortic aneurysm. Perfusion via bilateral axillary arteries may improve cerebral protection.
Key Words: Aortic Aneurysm • Axillary Artery • Brain Ischemia • Blood Vessel Prosthesis Implantation • Circulatory Arrest • Deep Hypothermia Induced
INTRODUCTION
Despite advances in surgical techniques, including anesthesia and cardiopulmonary bypass (CPB), brain injury after aortic arch surgery remains an important source of morbidity and mortality because of the advanced age of the patients and the presence of serious comorbidities.1–6 Extended thoracic aortic aneurysms involving the ascending aorta, arch, and descending aorta are often repaired in staged operations.7 However, single-stage replacement of the aortic arch and descending aorta might be a preferable surgical option for specific types of atherosclerotic aneurysm such as chronic type A or B dissection. We describe our experience of our current strategy for extended aortic replacement through a median sternotomy with a left anterolateral thoracotomy.
PATIENTS AND METHODS
Between January 2001 and June 2008, 23 consecutive patients with extended thoracic aortic aneurysms underwent total replacement of the arch and descending aorta at our institution; their characteristics are shown in Table 1
. Coronary angiography was performed before surgery in all cases, except those treated on an emergency basis.
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illustrates the surgical approach and method of cerebral protection. Distal anastomosis proceeded under crossclamping of the distal descending aorta, with distal perfusion via the femoral artery in 12 patients to prevent visceral ischemia. The other 11 patients underwent open distal anastomosis. After completion, the graft was drawn anteriorly into the isolated residual distal arch aorta. The left phrenic and left recurrent laryngeal nerves were identified, mobilized with the aneurysmal wall, and protected. Selective antegrade cerebral perfusion was terminated after reconstruction of the arch vessels, and the proximal side of the arch graft was sutured to the stump of the ascending aorta. The root of the left subclavian artery was ligated when an 8-mm diameter graft was anastomosed to the left axillary artery, and reconstructed by graft-graft anastomosis using a 5/0 polypropylene running suture.
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Table 2 gives the durations of surgery, CPB, cardiac arrest, and cerebral perfusion. These times were not significantly different to those recorded in patients who had total arch replacement through a median sternotomy only (data not shown). Two patients died in hospital: one who was in shock preoperatively and underwent emergency surgery for impending rupture of an arch aneurysm, died of multiple organ failure on postoperative day 70; the other who had a distal pseudoaneurysm after arch replacement for type A dissection and required simultaneous aortic and mitral valve replacement and coronary artery bypass grafting, died of multiple organ failure on postoperative day 17. However, neither of these patients had cerebral damage. Early morbidity included 17 patients with pulmonary failure, defined as requiring ventilatory support for >48 h. Two patients who had preoperative left recurrent laryngeal nerve palsy developed persistent hoarseness after the operation. No new phrenic or left recurrent laryngeal nerve palsy occurred as a result of surgery. Permanent neurological dysfunction, defined as permanent neurological deficits with localizing neurological signs and corresponding new defects on computed tomography, occurred in 1 (4.3%) patient who died of sepsis 2 years after the operation. The patients were followed up for 24.1 ± 23.7 months. The actuarial 5-year survival rate after surgery was 78.3% (Figure 2).
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The choice of surgical approach in patients with arch aneurysms is controversial because the results of extended arch replacement are suboptimal. The combined surgical approach (median sternotomy with a left anterolateral thoracotomy) to treat thoracic aortic aneurysms has been considered too invasive.3 We found that the durations of surgery and CPB were substantially prolonged, and there was an adverse effect on respiratory function, with 73.9% of patients requiring prolonged respiratory support, although they gradually recovered. On the other hand, Ohata and colleagues4 found no significant differences in respiratory function or inflammatory response between patients who underwent total arch replacement through a median sternotomy and those who also had a left anterolateral thoracotomy. Especially in the situation of distal reoperation for dissecting type A aneurysm, the retrosternal space can be excised easily via a left thoracotomy, despite dense adhesions. The cannulas are conveniently situated anteriorly, away from the main operative field, which improves access to the aortic arch and descending aorta. Moreover, the ability to visualize and protect the phrenic and recurrent laryngeal nerves enhances the recovery of patients with impaired respiratory function.
Prevention of cerebral embolism is an important consideration during repair of aortic arch or ascending aortic aneurysms. The arterial cannulation site for CPB is crucial in this respect. The ascending aorta or femoral artery is usually selected for arterial cannulation.1,5 However, cerebral embolism can occur because of severe atherosclerotic changes in the ascending aorta or retrograde perfusion via the femoral artery.3,8 Important factors in postoperative stroke, related to the method of cannulation, include the presence of clots and atheroma in the aorta, and dissection as the etiology of the aneurysm. Svensson and colleagues9 started using subclavian or axillary artery cannulation with deep hypothermic circulatory arrest and antegrade cerebral perfusion in 1995, and found it to be a safe approach for aortic arch surgery because the stroke risk was <2%. The theoretical advantages of using the subclavian or axillary artery for inflow in complex cardiac and aortic operations have recently become apparent.10 These include decreased likelihood of stroke from embolization, avoidance of malperfusion due to aortic dissection, reduced disruption of atheroma, and the ability to administer antegrade cerebral perfusion. Only one patient who had undergone ascending aortic perfusion in our series developed cerebral infarction, which we suspected was due to emboli from atheroma in the aortic arch. Since 2000, we have preferentially used bilateral axillary arteries for perfusion during total arch replacement, except in this patient. No other patient developed neurologic injury subsequently.
Ergin and colleagues11 regarded temporary neurological dysfunction as a clinical marker of an insidious but significant neurological injury associated with measurable long-term deficits in cerebral function. We used selective cerebral perfusion in aortic arch repair because of the extended duration of cerebral safety and low incidence of temporary neurological dysfunction. However, atheromatous debris, considered to be the main cause of permanent neurological dysfunction, remains a serious concern during selective cerebral perfusion. Selective antegrade cerebral perfusion is physiological and prolongs cerebral safety, but requires arch vessel cannulation. Potential sources of emboli arise from systemic CPB perfusion via the ascending aorta with an arch aneurysm, retrograde CPB perfusion via the femoral artery, or cannulation of the arch vessels for selective cerebral perfusion. The need to cannulate arteries and manipulate often severely atherosclerotic aneurysms increases the risk of embolization in the cerebral circulation. Direct cannulation of the subclavian or axillary arteries is associated with a risk of local complications, including dissection of the artery, inadequate flow, abutment of the cannula tip against the carotid artery wall, and tears that are difficult to repair because the arterial tissue is fragile and often traumatized.10 Thus we switched arterial inflow to a side-graft sewn to the vessel; the side-graft can be simply oversewn and tied off or clipped. The best approach for cerebral protection remains debatable. Although the procedure is continually undergoing refinement with improved results, brain injury can still arise. We doubted whether whole brain perfusion was sufficient via the right axillary artery only; thus left-sided brain perfusion was added, and bilateral axillary arteries were used in last 15 patients. Vertebral perfusion via the left axillary artery is also important for spinal protection. Simultaneously sewing grafts to bilateral axillary arteries takes 20–30 min. Axillary artery is always less atherosclerotic than the ascending aorta or femoral artery, and it is easily exposed.12–14 Furthermore, during left subclavian artery reconstruction, a graft can be simply sewn onto the side-graft anastomosed to the left axillary artery.
Recently, the feasibility of totally endovascular treatment of aortic arch aneurysm using a branched stent graft or fenestrated device has been reported.15 Kawaguchi and colleagues16 noted that thoracic endovascular repair tends to have a lower rate of serious complications than open surgery; the cerebral infarction rate in patients who received a fenestrated device was 5.5%. Thoracic endovascular repair does not require CPB, so patients do not experience low cerebral perfusion during the procedure. We consider that endovascular treatment of the ascending aorta and aortic arch is feasible in a limited group patients, but it cannot be considered a well-established method just yet, especially for the aortic arch, as technical difficulties with graft design and deployment persist.17 Extensive surgery was unavoidable in this series, especially in patients with dissection and those requiring concomitant procedures. Our results show that total arch replacement through a median sternotomy plus a left anterolateral thoracotomy allowed expeditious and extended replacement of the thoracic aorta and distal reoperation for dissecting type A aneurysm. Although this study was limited by its relatively small size, our experience of the combined approach with bilateral axillary cannulation indicates that the procedure was safe and effective in these severe cases.
REFERENCES
Asian Cardiovasc Thorac Ann 2009;
17:373-377
© 2009 by SAGE Publications
DOI: 10.1177/0218492309343260
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  I. A Borisov, A. N Bletkin, and D. D Savichev Median Sternotomy with Left Anterolateral Thoracotomy: An Interesting Option Asian Cardiovasc Thorac Ann, February 1, 2010; 18(1): 92 - 93. [Full Text] [PDF]
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