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Ann Thorac Surg 2002;74:S1810-S1814
© 2002 The Society of Thoracic Surgeons


Session 2: Aortic and Endoluminal Stents

Aortic arch replacement using a trifurcated graft and selective cerebral antegrade perfusion

David Spielvogel, MDa*, Justus T. Strauch, MDa, Oktavijan P. Minanov, MDa, Steven L. Lansman, MD, PhDa, Randall B. Griepp, MDa

a Department of Cardiothoracic Surgery, Mount Sinai School of Medicine/New York University, New York, New York, USA

* Address reprint requests to Dr Spielvogel, Mount Sinai School of Medicine, Department of Cardiothoracic Surgery, One Gustave L. Levy Pl, PO Box 1028, New York NY, 10029, USA.
e-mail: david_spielvogel{at}msnyuhealth.edu

Presented at the Aortic Surgery Symposium VIII, May 2–3, 2002, New York, NY.

Abstract

BACKGROUND: Aortic arch aneurysm repair remains associated with considerable mortality and risk of cerebral complications. We present results of a technique utilizing a three-branched graft for arch replacement, deep hypothermic circulatory arrest (HCA), and selective antegrade cerebral perfusion (SCP).

METHODS: Between March 2000 and November 2001, 22 patients (11 female) aged 40 to 77 years (mean 64 ± 11.2) underwent arch replacement utilizing the trifurcated-graft technique. Serial anastomosis of the branched graft to individual cerebral vessels was carried out during HCA, followed by arch reconstruction during SCP through the graft. All 22 patients had surgery electively. Eight patients (36%) had undergone previous aortic surgery. In 19 patients, arch replacement was part of an elephant trunk procedure; 2 patients had Bentall operations and 1 had isolated arch replacement. Concomitant coronary artery bypass grafting was performed in 6 patients (27%). Mean HCA duration was 30 ± 6 minutes at a mean temperature of 11.4 ± 0.8°C. Mean duration of SCP was 52 ± 18 minutes.

RESULTS: Adverse outcome—death before hospital discharge or permanent stroke or both—occurred in 2 patients (9%). Two patients experienced transient neurologic dysfunction (9%). Two patients (9%) developed renal failure requiring short-term hemodialysis and pulmonary complications occurred in 2 patients.

CONCLUSIONS: Cerebral protection and prevention of atheroembolism remain challenges in aortic arch reconstruction. To reduce neurologic complications we developed an aortic arch reconstruction technique in which a trifurcated graft is anastomosed to the brachiocephalic vessels during HCA, reducing the risk of embolization while minimizing cerebral ischemia by permitting antegrade cerebral perfusion as arch repair is completed.

Cerebral damage is one of the major reasons for an adverse outcome after surgical repair of the transverse aortic arch. Neurologic injury may result from prolonged ischemia, embolization, or severe malperfusion [1]. Over the past 3 decades several techniques of repair or replacement have been developed to avoid embolization of artherosclerotic debris and to preserve cerebral function during arch reconstruction [27].

The accepted surgical approach to treatment of extensive thoracic aortic aneurysm or dissection involving the transverse aortic arch is graft replacement using deep hypothermic circulatory arrest (DHCA) with or without antegrade selective cerebral perfusion [8]. The technique of deep hypothermic circulatory arrest enhances the tolerance of cerebral tissue to prolonged ischemia but arrest times greater than 30 minutes are associated with subtle cognitive impairment; times exceeding 40 minutes are associated with increased stroke rates, and cerebral ischemia exceeding 60 minutes results in decreased survival [8]. To keep the period of hypothermic circulatory arrest as short as possible antegrade cerebral perfusion can be used to preserve neurologic integrity and to allow a longer time to finish the aortic arch repair [9].

We have developed a technique in which a three-branched arch graft is anastomosed to the brachiocephalic vessels under a period of HCA and selective antegrade cerebral perfusion is started before the performance of the distal aortic reconstruction. The aim is to reduce the risk of postoperative neurologic complications by lowering the risk of embolization and by minimizing the duration of HCA. In this retrospective study we evaluate the clinical and neurologic outcome utilizing this new technique for arch replacement.

Patients and methods

Patients
Between March 2000 and November 2001, 22 consecutive patients (11 female, 11 male) underwent elective surgical repair of the transverse aortic arch and various portions of the ascending and proximal descending aorta as well as the proximal part of the brachiocephalic branches utilizing the trifurcated-graft technique. Mean patient age was 64 ± 11.2 years (range 40 to 77).

Etiology of the aneurysm was arteriosclerosis in 16 patients (73%), chronic dissection in 5 (23%), and Marfan disease in 1 patient (4%). Eight patients (36%) had previous aortic surgery including Bentall procedure and replacement of the proximal ascending aorta for acute type A dissection (n = 6), total aortic arch replacement (n = 1), and thoracoabdominal aortic repair (n = 1). Seventeen patients (77%) presented with arterial hypertension, 16 patients (73%) had a history of smoking, and 5 patients (23%) had chronic obstructive pulmonary disease. Six patients (27%) had a history of ischemic coronary heart disease, 1 patient (4%) had chronic renal insufficiency (creatinine > 1.5 mg/dL).

Mean diameter of the aorta was 6.6 ± 1.5 cm (range 5.4 to 10 cm). The extent of the aortic replacement varied: in 19 patients (86%), arch replacement was part of an elephant trunk procedure; 2 patients (9%) had Bentall operations and 1 (4%) had isolated arch replacement. Concomitant coronary artery bypass grafting was performed in 6 patients (27%). Two patients (9%) had concomitant aortic valve replacement and 1 patient (4%) had aortic valve annuloplasty.

Surgical technique
A median sternotomy was performed with extension of the incision superiorly along the medial border of the left sternocleidomastoid muscle. The right axillary artery was exposed through a small infraclavicular incision separating a portion of the pectoralis minor muscle from the clavicle. The axillary artery was cannulated with a right angle wire-reinforced arterial catheter (Edwards Lifesciences, Irvine, CA) and secured. Extracorporeal circulation and cooling were started after cannulation of the right atrium with a two-stage catheter. The perfusate temperature was kept at 10°C. The aorta was cross-clamped and cardioplegic solution was administered through the aortic root or, if necessary in case of aortic insufficiency, directly into the coronary ostia. After carefully sizing the innominate, left carotid, and left subclavian arteries a trifurcation graft was constructed. Generally 14 mm and 10 mm Hemashield grafts (Boston Scientific, Natick, MA) or 12 mm and 8 mm Hemashield grafts were selected. The smaller graft was divided and bevelled and sewn to openings constructed in the side of the large graft in a sequential manner with a 3-0 or 4-0 polypropylene suture (Fig 1). The completion of this phase of the operation usually coincided with the end of core cooling. At this time point the esophageal temperature was lowered to between 11°C to 14°C and the jugular bulb oxygen saturation increased to above 95%, indicating that maximum metabolic suppression had been achieved. The patient was readied for circulatory arrest. The head was packed in ice for topical cooling.



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Fig 1. Construction of the trifurcated graft with cut and beveled Dacron grafts.

 
At the beginning of circulatory arrest the patient was placed in slight Trendelenburg position and the innominate artery was transected just distal to its origin at the aortic arch (Fig 2, A). The end of the 12 mm or 14 mm graft previously constructed was trimmed and anastomosed to the brachiocephalic trunk with a 4-0 polypropylene suture. Next, the first of the 8 mm or 10 mm limbs was trimmed to the appropriate length and anastomosed in a similar fashion to the transected left common carotid artery. Finally the second side branch of the trifurcated graft was sutured to the left subclavian artery. The order of the reconstruction can be reversed, as this may provide better exposure to the left subclavian artery in some patients. The graft limbs were gently aspirated into the individual brachiocephalic vessels. Perfusion through the right axillary artery was temporarily resumed at 500 mL/min, flushing air and any possible embolic material retrograde. Perfusion was stopped again, aspiration repeated, and flow resumed. The trifurcation graft was carefully deaired and the proximal portion, ie, the 12 mm to 14 mm portion, was clamped, restoring perfusion to the head and upper extremities (Fig 2, B). Perfusion pressure was maintained at about 50 mm Hg, requiring flows between 600 to 1000 mL/min. Blood temperature was allowed to drift upward.



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Fig 2. (A) Transection of the brachiocephalic vessels just distal to their origin during hypothermic circulatory arrest. (B) Anastomosis of the limbs of the trifurcated graft to the brachiocephalic arteries followed by selective antegrade cerebral perfusion through the right axillary artery.

 
The aortic arch was reconstructed in a variety of ways depending upon the pathology. For ascending and arch disease with aortic valve involvement a modified Bentall or Yacoub procedure preceded arch reconstruction. If aneurysmal disease involved additional aortic segments an elephant trunk was constructed. The graft was stretched and measured to the appropriate length and sutured to the sinotubular junction or to a previous graft used for aortic reconstruction. Graft-to-graft anastomoses were performed with 2-0 polypropylene sutures.

At this point, the dacron graft was distended with cardioplegic solution to facilitate choosing the ideal site for the brachiocephalic graft end-to-side anastomosis to the ascending portion of the aortic reconstruction. An elliptical opening was fashioned and the trifurcation graft was bevelled and trimmed. Cerebral and upper extremity perfusion was not interrupted. On completion of this final anastomosis, the patient was actively rewarmed (Fig 3).



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Fig 3. Completion of the aortic arch repair with a final graft-to-graft anastomosis.

 
Results

All patients underwent complete aortic arch replacement with the trifurcated graft technique. Mean duration of hypothermic circulatory arrest was 30 ± 6 minutes (range 17 to 42) at a mean temperature of 11.4 ± 0.8°C (range 10.3°C to 13.1°C). Mean duration of selective cerebral perfusion was 52 ± 18 minutes (range 21 to 78) and the duration of cardiopulmonary bypass was 189 ± 36 minutes (range 168 to 253).

Adverse outcomes—death before hospital discharge or permanent stroke—occurred in 2 patients (9%). There were no intraoperative deaths. One patient died on postoperative day 36 owing to multiple organ failure without severe neurologic injury, confirmed by computed tomography scan. The other patient died on postoperative day 11 owing to diffuse neurologic injury with computed tomography evidence of multiple cerebral infarction and hemorrhage.

Two patients experienced transient neurologic dysfunction (9%). There was no patient discharged with permanent stroke. Two patients (9%) developed renal failure requiring short-term hemodialysis. Pulmonary failure requiring ventilatory support for more than 48 hours after surgery occurred in 2 patients (9%). There were no cases of reoperation for bleeding or mediastinitis. Mean intensive care unit stay was 4.4 ± 3.8 days (range 1 to 42) and mean duration of hospital stay was 16.3 ± 11.4 days (range 8 to 42).

Comment

Mortality and morbidity associated with transverse aortic arch replacement has decreased over the past decades as various modifications of surgical technique have been introduced [3, 5, 6, 8, 10]. Despite these recent advances, however, providing adequate cerebral protection and preventing cerebral embolization during reconstruction of the calcified and atherosclerotic aorta remain challenges.

Deep hypothermia is the most accepted method of cerebral protection during replacement of the aortic arch [9, 12]. With the current technique, the anastomosis of all three arch vessels can be carried out during a single period of HCA or the vessels can be perfused sequentially as each anastomosis is done and the corresponding branch is opened, reducing the interval of HCA. Thus, separate arch vessel graft techniques result in shorter total pump [1, 4] and circulatory arrest times. Kazui and associates [14], in 220 consecutive patients with total arch replacement utilizing a similar branch graft technique and selective cerebral perfusion, reported a 12.7% mortality rate, a 3.3% stroke rate, and an incidence of temporary neurologic dysfunction (TND) of 6%. A more contemporary series of 50 patients resulted in reduction of mortality to 2%, a stroke rate of 4%, and a 4% incidence of TND [15]. In this series cardiopulmonary bypass time and a history of cerebrovascular disease were the only risk factors for neurologic injury. Our permanent stroke rate of 5% and 9% incidence of TND compare favorably with the results of other groups [2, 7].

Cerebral protection has evolved based on clinical and laboratory studies. Periods of hypothermic arrest less than 30 minutes are well tolerated even by elderly patients and patients with cerebral vascular disease. Sufficient periods of core cooling—greater than 30 minutes—are utilized. Esophageal temperatures are lowered to between 11°C and 14°C. The jugular bulb saturation is consistently measured and circulatory arrest is not implemented until the saturation is greater than 95%, indicating maximal metabolic suppression [16]. These guides establish a uniform benchmark to insure adequate cerebral protection when periods of DHCA may be prolonged. But with current reconstructive techniques the period of DHCA is often quite brief and controversy exists over whether shorter intervals of core cooling, and higher temperatures before cerebral ischemia—with associated shorter cardiopulmonary bypass times—can provide the same degree of cerebral protection [2]. Our philosophy is still to utilize more profound hypothermia in order to maximize cerebral metabolic suppression and increase the safety margin even during short periods of DHCA and antegrade cerebral perfusion [17].

In addition to concerns regarding global cerebral injury, prevention of cerebral embolization requires constant attention and may be of even greater importance in preventing cerebral sequelae in aortic arch operations. Currently cannulation for arterial perfusion is through direct access to the right or left axillary arteries and rarely the ascending aorta: the femoral artery is avoided as the atherosclerotic process is often diffuse and retrograde embolization is a constant threat [7]. The right axillary artery is cannulated directly with a manufactured right-angle wire-reinforced catheter: this has been done in more than 300 patients in our institution. It is anticipated that this central cannulation technique and retrograde flushing of the aortic arch may reduce particulate and air embolization while still providing an uncluttered operative field during the completion of the arch repair.

More relevant to the current branched graft technique is the observation, made during previous arch reconstructions using a patch graft of the brachiocephalic vessels, that the cerebral vessels themselves are often free of severe atherosclerotic disease [15, 17]. Just a centimeter beyond the origins of these vessels from the arch the severe atheromatous process dissipates, allowing individual grafting of cerebral vessels without fear of distal embolization of atherosclerotic debris. Occasionally atherosclerotic disease of the arch continues cephalad but healthy vessels can almost always be reached by extending the sternotomy incision.

This branched graft technique is exceptionally well suited for contained ruptures and infected pseudoaneurysms. In the case of a contained rupture the aorta itself may be badly damaged and friable but dissection of the brachiocephalic vessels reveals healthy tissue. In reoperations for pseudoaneurysms the previously operated-on field prevents rapid dissection of structures and subsequent repair under acceptable periods of DHCA. Identification of the brachiocephalic vessels, use of branch grafting, and establishment of selective cerebral perfusion permit safe and accurate arch reconstruction.

Conclusions

Our favorable experience in this small initial series will require confirmation with a larger number of patients. Our continued strategy features liberal use of axillary cannulation, avoiding manipulation of atherosclerotic vessels before HCA, careful removal of loose debris, trifurcated branch grafting of the brachiocephalic vessels, restricting the duration of HCA to less than 30 minutes, and use of selective hypothermic antegrade cerebral perfusion during the completion of the arch repair. ([11,13])

References

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  2. Jacobs M.J., de Mol B.A., Veldman D.J. Aortic arch and proximal supraortic arterial repair under continuous antegrade cerebral perfusion and moderate hypothermia. Cardiovasc Surg 2001;9:396-402.[Medline]
  3. Schepens M.A., Dossche K.M., Morshuis W.J., van den Barselaar P.J., Heijmen R.H., Vermeulen F.E. The elephant trunk technique: operative results in 100 consecutive patients. Eur J Cardiothoracic Surg 2002;21:276-281.[Abstract/Free Full Text]
  4. Bednarkiewicz M., Khatchatourian G., Christenson J.T., Faidutti B. Aortic arch replacement using a four-branched aortic arch graft. Eur J Cardiothoracic Surg 2002;21:89-91.[Abstract/Free Full Text]
  5. Griepp R.B., Stinson E.B., Hollingsworth J.F., Buehler D. Prosthetic replacement of the aortic arch. J Thorac Cardiovasc Surg 1975;70:1051-1063.[Abstract]
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  7. Westaby S., Katsumata T. Proximal aortic perfusion for complex arch and descending aortic disease. J Thorac Cardiovasc Surg 1998;115:162-167.[Abstract/Free Full Text]
  8. Ergin M.A., Galla J.D., Lansman S.L., et al. Hypothermic circulatory arrest in operations of the thoracic aorta: determinants of operative mortality and neurological outcome. J Thorac Cardiovasc Surg 1993;107:788-799.
  9. Bachet J., Guilmet D., Goudout B., et al. Antegrade cerebral perfusion in operations on the proximal thoracic aorta. Ann Thorac Surg 1999;67:1874-1878.[Abstract/Free Full Text]
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  11. Rokkas C.K., Kouchoukos N.T. Single-stage extensive replacement of the thoracic aorta: the arch-first technique. J Thorac Cardiovasc Surg 1999;117:99-105.[Abstract/Free Full Text]
  12. Griepp R.B., Ergin M.A., McCullough J.N., et al. Use of hypothermic circulatory arrest for cerebral protection during aortic surgery. J Card Surg 1997;12(suppl):312-321.[Medline]
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