Asian Cardiovasc Thorac Ann 2002;10:318-321
© 2002 Asia Publishing EXchange Pte Ltd
Arch-First Technique for Aortic Arch Operation Using Branched Graft
Hiroyuki Tsukui, MD,
Shigeyuki Aomi, MD,
Hideyuki Tomioka, MD,
Masaki Nonoyama, MD,
Hitoshi Koyanagi, MD,
Chinami Nagasawa, MD1,
Minoru Nomura, MD1
Department of Cardiovascular Surgery The Heart Institute of Japan
1 Department of Anesthesiology Tokyo Women’s Medical University Tokyo, Japan
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For reprint information contact: Hiroyuki Tsukui, MD Tel: 81 3 3353 8111 Fax: 81 3 3356 0441 email: htsukui{at}jasmine.ocn.ne.jp Department of Cardiovascular Surgery, The Heart Institute of Japan, Tokyo Women’s Medical University, 8-1 Kawada, Shinjuku, Tokyo 162-8666, Japan.
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ABSTRACT
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To compare the arch-first technique with conventional aortic arch reconstruction 19 patients were randomly assigned to either procedure. Nine patients underwent the arch-first technique (group A) and 10 underwent the conventional technique (group B). There were no hospital deaths and no significant differences between groups in terms of intraoperative bleeding or the duration of operation cardiopulmonary bypass aortic crossclamping recovery from anesthesia or intensive care. The mean duration of retrograde cerebral perfusion via the superior vena cava was significantly shorter in group A (41.7 ± 10.4 min) than group B (63.9 ± 10 min). Transient neurologic dysfunction was noted in 4 (44%) patients in group A 6 (60%) in group B postoperatively but there was no permanent neurologic dysfunction in either group. The arch-first technique makes it possible to reduce the duration of cerebral ischemia retrograde cerebral perfusion via the superior vena cava reestablish antegrade cerebral perfusion earlier without damaging severely atheromatous arch vessels or conducting retrograde cerebral perfusion via a femoral artery. This technique has the potential to reduce the incidence of neurologic dysfunction.
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INTRODUCTION
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In surgery on the thoracic aorta, especially aortic arch reconstruction requiring deep hypothermia and circulatory arrest, neurologic dysfunction is a disastrous complication and a challenging problem. In the arch-first technique, reconstruction of the arch vessels is undertaken before distal aortic anastomosis.1 This alternative method addresses the need to reduce neurologic dysfunction by minimizing the duration of cerebral ischemia and retrograde cerebral perfusion (RCP) via the superior vena cava (SVC) and reestablishing antegrade cerebral perfusion (ACP) earlier without damaging severely atheromatous arch vessels or conducting RCP via a femoral artery. We compared patients who underwent the arch-first technique with a group undergoing the conventional method of aortic arch reconstruction.
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PATIENTS AND METHODS
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From October 1999 to September 2000, 19 patients underwent repair of the aortic arch and various lengths of ascending and descending thoracic aorta, in our institute. Patient details are summarized in Table 1
. Nine patients (mean age, 65.4 ± 8.4 years; range, 46 to 72 years: group A) underwent the arch-first technique, and 10 patients (mean age, 60.7 ± 11 years; range, 44 to 71 years: group B) underwent the conventional technique. Patients were randomly assigned to group A or B.
Most operations were performed through a median sternotomy. In 1 patient in group A who had undergone a Bentall operation previously, a 4th-intercostal left thoracotomy was used for repair of the arch and descending aorta. One patient (group B) with Kommerell’s diverticulum had an additional right thoracotomy to allow anastomosis to the right descending thoracic aorta. The femoral artery was cannulated for distal perfusion after circulatory arrest, and cardiopulmonary bypass was established with cannulation of the ascending aorta and both venae cavae, with a pulmonary artery vent. The no-touch technique was employed to prevent cerebral embolism.2 Meticulous cannulation guidance was ensured by direct echography. A retrograde cardioplegia cannula was positioned in the coronary sinus. In accordance with the no-touch principle, antegrade cardioplegia requiring aortic crossclamping was avoided to prevent aortic damage and consequent embolization. In a patient with aortic regurgitation, aortic crossclamping was necessary, but only retrograde cardioplegia was used to prevent coronary ostial injuries.
In group A, RCP via the SVC was initiated at a low flow rate of approximately 100 mL.min-1 to prevent cerebral edema. Distal perfusion was established with low flow (1.5 to 2 mL.min-1) via the femoral artery. The arch was reconstructed with a quadrifurcated collagen-impregnated woven Dacron graft (Hemashield; Meadox Medicals, Inc., Oakland, NJ, USA). The arch vessels, left subclavian artery, left common carotid artery, and brachiocephalic artery were anastomosed individually in that order (Figure 1). After all anastomoses were completed, the aortic graft was clamped just distal to the left subclavian artery anastomosis. Air was evacuated from the open proximal end of the graft by perfusing from the side arm of the branched grafts. The RCP via the SVC was discontinued, the aortic graft was clamped proximal to the brachiocephalic artery anastomosis, and ACP was employed at an approximate rate of 10 mL.min-1.kg-1 (Figure 2). Distal aortic anastomosis to a separate section of graft was performed by an open distal technique. The elephant-trunk technique was applied in all patients, except one who underwent concomitant graft replacement of the descending aorta. When graft-to-graft anastomosis was completed, antegrade perfusion was instituted via the side arm of the branched graft (Figure 3). The proximal end of the aortic graft was sutured end-to-end to the proximal ascending aorta.
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Figure 1. The arch vessels, left subclavian artery, left common carotid artery, and brachiocephalic artery were anastomosed individually in that order.
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Figure 3. After graft-to-graft anastomosis, antegrade perfusion was established from the side arm of the branched graft.
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In group B, after cooling was initiated, the circulation was arrested as in group A, and RCP via the SVC was established at a low flow rate. Distal anastomosis was performed to the branched grafts by an open distal technique. After crossclamping the anastomosed graft, perfusion to the lower body was reestablished via the femoral artery. All arch vessels were anastomosed individually to the branched grafts. Perfusion was instituted to the head and lower body via the side arm of the branched grafts. Finally, the proximal end of the aortic graft was sutured end-to-end to the proximal ascending aorta.
To analyze neurologic dysfunction, outcome was classified as: type I, defined as death due to stroke or hypoxic encephalopathy, nonfatal stroke, transient ischemic attack, or stupor or coma at the time of discharge; or type II, defined as new deterioration in intellectual function, confusion, agitation, disorientation, memory deficit, or seizure without evidence of focal injury.3
Data were expressed as mean ± standard deviation. Student’s t test was used for comparison of means, and p values < 0.05 were considered significant. All statistical analyses were performed using the StatView version 5.0 statistical software program (SAS Institute, Cary, NC, USA).
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RESULTS
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There were no hospital deaths. Group data are summarized in Table 2. There was no significant difference between groups A and B in terms of the duration of the operation, cardiopulmonary bypass, aortic crossclamping, recovery from anesthesia, or intensive care unit stay, or in the incidence of intraoperative bleeding. The duration of RCP via the SVC was significantly shorter in group A than group B. Four patients (44%) in group A and 6 (60%) in group B had postoperative transient neurologic dysfunction (Table 1
). A patient in group B who had suffered a previous cerebral infarction had a postoperative convulsion, but there was no case of type I neurologic dysfunction in either group.
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DISCUSSION
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Neurologic dysfunction continues to be the most important cause of morbidity and mortality in thoracic aortic surgery. In operations requiring deep hypothermia and circulatory arrest, especially those that include aortic arch reconstruction, neurologic dysfunction is related to the duration of cerebral ischemia and to the presence of severely atheromatous arch vessels with calcification.3 Transient neurologic dysfunction is related to the duration of cerebral ischemia, whereas permanent neurologic dysfunction is the result of embolic strokes.4 Use of RCP via the SVC at a low flow rate during deep hypothermia is effective in protecting the brain not only by maintaining cerebral perfusion, but also by avoiding debris and air emboli.2 At our institute, RCP via the SVC has been the method of choice to protect the brain in aortic arch reconstruction since 1990. However, 25% of patients developed transient neurologic dysfunction postoperatively, which precludes fast-track recovery, especially in elderly patients.2 Ergin and colleagues4 reported that inadequate cerebral protection with RCP via the SVC resulted in postoperative transient neurologic dysfunction, such as delirium.
On the other hand, ACP is associated a high incidence of neurologic dysfunction in patients with severely atheromatous arch vessels with calcification, which is attributed to catheter-induced arch vessel damage and resultant embolization.5,6 We have employed the no-touch technique with direct echography since 1997, and there has been no permanent neurologic dysfunction in 80 consecutive patients.2 Aortic arch reconstruction using a branched graft is useful in preventing cerebral infarction because it avoids leaving atheromatous arch vessels with calcification. However, it requires approximately 60 minutes of circulatory arrest for individual anastomoses to the arch vessels. Despite RCP via the SVC during aortic arch reconstruction, hypoxia may induce mild neurologic dysfunction.
Reducing the duration of cerebral ischemia and RCP via the SVC, and avoiding damage to severely atheromatous vessels are the keys to preventing transient or permanent neurologic dysfunction.7 The arch-first technique reduces the period of cerebral ischemia by more than 15 minutes, allowing earlier reestablishment of cerebral perfusion without damaging severely atheromatous arch vessels or employing RCP via the femoral artery. However, the arch-first technique reduces exposure of the distal anastomotic site, and makes it difficult to perform distal aortic anastomosis of a graft with branches anastomosed to arch vessels, which might increase the duration of operation and the extent of intraoperative bleeding. This problem can be resolved by performing distal aortic anastomosis by the elephant-trunk technique using a separate piece of graft. There was no significant difference between groups in terms of the duration of any stage of the procedure or the amount of intraoperative bleeding, in spite of the extra graft-to-graft anastomosis with the arch-first technique.
This experience indicates that the arch-first technique reduced the duration of cerebral ischemia and RCP via the SVC, and reestablished ACP earlier without damaging severely atheromatous arch vessels or employing RCP via the femoral artery. Although this alternative technique has the potential to markedly reduce neurologic dysfunction, we were unable to demonstrate a statistically significant difference in this small series of patients. With continued refinement of this technique and accumulation of a larger series, it may be possible to clarify the benefits of the arch-first technique.
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REFERENCES
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ABSTRACT
INTRODUCTION
