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Ann Thorac Surg 2004;77:2029-2033
© 2004 The Society of Thoracic Surgeons

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Original article: cardiovascular

Circulatory arrest for repair of postcoarctation site aneurysm

^a Department of Cardiothoracic Surgery, Westmead Hospital, Sydney, Australia
^b Adolph Basser Cardiac Institute, The Children's Hospital at Westmead, Sydney, Australia

Accepted for publication November 20, 2003.

^* Address reprint requests to Dr Chard, Suite 8, Children's Hospital Medical Centre, Ainsworth St, Westmead, NSW 2145, Australia
e-mail: rchard{at}bigpond.net.au

	Abstract

Top Abstract Introduction Material and methods Results Comment References

 
BACKGROUND: Aneurysm at previous coarctation repair may be seen more frequently as children operated for this condition survive into adulthood. We use deep hypothermic circulatory arrest to repair these aneurysms.

METHODS: A case series was conducted using 12-year, single-institution, retrospective chart review.

RESULTS: Twenty-one patients underwent left thoracotomy and repair of aneurysm at the site of previous coarctation repair. Three cases presented emergently as aortobronchial fistulas. The age range was 16 to 73 years (median, 26 years). The median circulatory arrest time was 33 minutes (range, 22 to 55 minutes). Repair involved interposition graft replacement. Six patients required additional tube graft replacement of the left subclavian artery. There was 1 operative mortality in a patient having a hypoxic brain injury secondary to an anaphylactic reaction to a plasma expander. There were no embolic strokes or paraplegia. One patient had a recurrent laryngeal nerve paresis. There was 1 case of Horner's syndrome after subclavian artery replacement.

CONCLUSIONS: Circulatory arrest allows for the accurate repair of this difficult pathologic process and avoids the risk of clamp-related injuries. Follow-up out to 16 years demonstrates this technique of repair to be durable, with no late deaths or reoperations for recurrent aneurysm.

	Introduction

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Aneurysm formation at the site of previous coarctation repair is becoming increasingly recognized as a late complication of this condition. It is thought to result from changes in aortic compliance and increased wall strain and stress at the repair site [1]. It has mostly been associated with prosthetic patch-plasty repair [2], although aneurysms have been reported after all techniques of repair and even in unrepaired coarctations [3]. The aneurysms are usually very thin walled and demonstrate evidence of cystic medial necrosis histologically [4].

Surgical intervention for postcoarctation aneurysm poses difficulty related to cross-clamping the aortic arch such as stroke, bleeding, dissection, spinal cord ischemia, and recurrent laryngeal nerve injury. Furthermore, reoperative adhesions increase the technical difficulties. We have developed a method of "clampless" repair using deep hypothermic circulatory arrest. Our technique and results are presented.

	Material and methods

Top Abstract Introduction Material and methods Results Comment References

 
Patients and pathology
A retrospective chart review of 21 consecutive patients having postcoarctation aneurysm repairs by left thoracotomy using circulatory arrest from 1991 to 2003 was undertaken. There were 16 male and 5 female patients. The age range was 16 to 73 years (median, 26 years). All patients had post-coarctation-repair aneurysms. Three patients presented emergently as aortobronchial fistulas. One of these patients had a preoperative cardiac arrest due to massive hemoptysis. Two presented with recurrent obstruction and hypertension. The remainder were asymptomatic, with aneurysms detected on follow-up imaging.

Previous operations
Seventeen of the 21 original coarctation repairs were onlay Dacron patch-plasties (DuPont, Wilmington, DE). The other 4 repairs were extra-anatomical bypass grafting procedures (n = 2) and subclavian flap repairs (n = 2). Five patients had additional prior operations: 2 with recoarctation repairs (1 patch aortoplasty and 1 extra-anatomical bypass grafting procedure). One patient had repair of postcoarctation aneurysm (new aneurysm at proximal clamp site). One patient had 2 prior operations for recoarctation (patch aortoplasty, then extra-anatomical bypass tube grafting). One patient had 3 prior operations for recoarctation (2 patch aortoplasties, then extra-anatomical bypass tube grafting). The median time to last surgical procedure at the coarctation site was 12 years (range, 4 to 26 years).

Operative technique
The operative strategy has evolved over the study period, with modifications to cannulation technique, the choice of prosthetic materials, intraoperative monitoring, and adjunctive measures used for circulatory arrest and cerebral protection. The current technique is summarized in Table 1 and discussed in further detail in the following sections. Briefly, cardiopulmonary bypass is instituted by left femorofemoral cannulation, and cooling is commenced. Redo left thoracotomy is performed and adhesions dissected, avoiding the phrenic and recurrent laryngeal nerves. Monitoring for distension of the left ventricle when the heart begins to fibrillate is achieved using transesophageal echocardiography (TEE) and treated by gentle massage if observed. At 18°C, cardiopulmonary bypass is discontinued. With the patient in the Trendelenburg position and carbon dioxide in the field, the aneurysm is opened longitudinally. An appropriately sized interposition tube graft is selected, and the proximal anastomosis is performed adjacent to the left carotid/left subclavian ostia using an "endoaneurysmal" (inlay) technique; that is, the arch is not completely transected and the anastomosis done from within the aorta. The descending aorta at the distal limit of the aneurysm is transected and a direct end-to-end anastomosis performed. This distal anastomosis is performed under circulatory arrest because this anastomosis is generally straightforward and we believe can be constructed as rapidly as the time taken to reperfuse the upper body through the tube graft. After completion of the distal anastomosis, cardiopulmonary bypass is recommenced and rewarming begun. When the left subclavian artery is also aneurysmal, it is replaced with a separate tube graft. The distal subclavian anastomosis is performed during circulatory arrest because the fragile aneurysmal tissue often extents to the thoracic outlet. The proximal subclavian graft is anastomosed to the side of the aortic graft during rewarming. The completed reconstruction is illustrated in Figure 1. The aneurysm sac is closed where possible to cover the prosthetic graft material. After weaning from cardiopulmonary bypass, heparin is reversed and hemostasis checked. The lung is checked for air leak and the chest closed with 2 intercostal drains.

View larger version (124K): [in this window] [in a new window]   Fig 1. Operative photograph of completed graft replacement. Aneurysm sac is seen held to the left, with previous Dacron patch (arrow) visible in the wall of the aneurysm. The separate subclavian tube graft is seen arising from the proximal aortic tube graft.

	Results

Top Abstract Introduction Material and methods Results Comment References

Repair involved prosthetic tube graft replacement in all patients (median graft size, 18 mm; range, 16 to 26 mm) Six patients had additional tube graft replacements of the left subclavian artery (median size, 8 mm; range, 6 to 10 mm).

Early postoperative results
There was 1 operative mortality. This was a 21-year-old male patient who had had an aortic valve–sparing root replacement (David procedure) 4 months previously. During cooling on cardiopulmonary bypass, he had an anaphylactic reaction after receiving a plasma expander. Massive fluid extravasation and disseminated intravascular coagulation (DIC) developed. On returning to the intensive care unit, he had a 3-hour period of hypoxia (PaO₂ of 40 to 45 mm Hg), despite maximal ventilation, because of noncardiogenic pulmonary edema. He recovered from multisystem organ failure but was declared brain dead 1 week postoperatively. It was presumed that he had become sensitized to a plasma expander used at the previous David procedure.

There was no embolic strokes or paraplegia. There was 1 case of Horner's syndrome after subclavian artery replacement. In one patient with a partial vocal cord weakness preoperatively, a complete recurrent laryngeal nerve palsy developed postoperatively. In another patient, a new recurrent nerve paresis developed, which had improved at follow-up 4 months postoperatively. One patient with DIC required reexploration for bleeding.

Late results
At most recent follow-up 3 months to 16 years postoperatively (mean, 4 years), there had been no late deaths or reoperations. One patient with a bicuspid aortic valve had moderate aortic regurgitation under observation. All patients remain under review every 12 to 24 months with clinical examination and computed tomography or magnetic resonance imaging.

	Comment

Top Abstract Introduction Material and methods Results Comment References

 
This case series reports a surgical strategy for the approach to postcoarctation aortic aneurysms that we believe is safer and more accurate than previously described methods of repair that have involved clamping the distal arch, with or without some form of left heart or cardiopulmonary bypass. The extremely fragile nature of the aneurysm wall and the aortic arch proximal to the aneurysm, as well as the reoperative difficulties, makes the use of circulatory arrest an appropriate technique in the approach to this difficult lesion. Table 1 summarizes our current surgical strategy, discussed in further detail below.

Relationship of initial coarctation repair to aneurysm formation
As in other series [2, 3, 5], prosthetic patch-plasty was the most common initial repair leading to subsequent aneurysm formation, at an average of 14 years postoperatively in this series. Nevertheless, 7 patients in our series had other techniques of coarctation repair, including 2 subclavian flap aortoplasties. Only 7 other cases of aneurysm after subclavian flap repair have been reported in the literature [6–10], suggesting that this may be the method least likely to predispose to aneurysm formation, possibly because of the avoidance of prosthetic material and a noncircumferential suture line. Aneurysms developed in 5 patients in this series between 2 and 10 years after extra-anatomical bypass tube grafts. There were 3 false aneurysms and 3 true aneurysms (1 patient having true aneurysms at proximal and distal suture lines). Some authors have recommended extra-anatomical bypass grafting for recurrent aortic coarctation [11, 12]. Their follow-up, however, has been short. We have experienced a high incidence of aneurysm formation at a median of 6 years postoperatively and now avoid this technique for recoarctation. Four different surgeons performed extra-anatomical bypass grafting procedures, and therefore, aneurysm formation is unlikely to be a single-operator technical problem. We believe that the etiologic process behind aneurysm formation with this technique is twofold. First, the anastomotic site proximally and distally is spatulated, producing a bigger orifice than the native aorta. By the law of Laplace, this area experiences greater wall tension and therefore may tend to dilate. Second, having an interface between the native aorta and a noncompliant Dacron tube, like the experience with Dacron patches for aortic coarctation, puts greater shear forces on the anastomotic area, with the potential for aneurysm formation or anastomotic dehiscence and false aneurysm formation.

Peripheral nerve injury
In avoiding recurrent nerve injuries, we have found the "endoaneurysmal" technique of proximal tube graft anastomosis to be helpful. During the period of circulatory arrest, the aneurysm is opened and interposition tube graft replacement performed. The proximal anastomosis is constructed adjacent to the left common carotid artery from within the aneurysm, without transecting the aorta or externally dissecting it ("endoaneurysmal technique"). The distal end of the tube graft is anastomosed to the transected descending aorta. The nerve often cannot be found at reoperation, and in this situation, we have not sought to dissect it out but rather to avoid it altogether by not cross-clamping the arch and by placing sutures from within the aorta. In the 6 patients who required the replacement of the subclavian artery, however, we had 1 case of Horner's syndrome, presumably due to injury to the ansa subclavia.

Prosthetic materials
We previously used flexible standard wall thickness Gore-Tex tube grafts (W. L. Gore and Associates, Flagstaff, AZ) for aortic replacement because of excellent handling properties and plasticity to conform to the curve required for this position. Because of problems with prolonged suture hole bleeding associated with Gore-Tex grafts, we changed to gel-filled Dacron tube grafts. We believe that the hemostatic properties of this graft, when supplemented with Bioglue (Cryolife, Inc, Kennesaw, GA) on suture lines, is superior to the Gore-Tex tube grafts. Fine sutures (5-0 polypropylene) are used to reduce the risk of tearing the delicate aortic tissue.

Cardiopulmonary bypass
Early in our institutional experience, patients were placed on cardiopulmonary bypass using descending aortic and pulmonary artery cannulation. Pulmonary artery cannulation increased the risk for right heart dilation when hypothermic fibrillation occurred and often provided poor drainage. Early in this series, we found femorofemoral cannulation using Medtronic Biomedicus cannulas (Medtronic Inc, Minneapolis, MN) and vacuum-assisted drainage to be highly effective in providing excellent flows on bypass. The 19 F and 21 F arterial cannulas were useful for the coarctation patients, who often had small femoral arteries. Cannulation of the left groin in the semidecubitus position was readily achieved using a direct cutdown onto the femoral vessels followed by an incision within a pursestring and a Seldinger technique of insertion over a guidewire. Using intraoperative TEE, the tip of the venous cannula was positioned into the midright atrium to provide good venous return, augmented by the use of vacuum.

Intraoperative TEE was also helpful in monitoring for ventricular distension when the heart fibrillated during cooling. Gentle massaging was used if distension was observed. We did not have to use a left ventricular vent, but this may be necessary in the presence of significant aortic regurgitation.

During anastomotic construction in circulatory arrest, we kept the patient in a steep Trendelenburg position, suctioning only blood in the immediate surgical field. The arch and cerebral vessels were allowed to continually fill up to the level of the surgical anastomosis. With this technique, we did not have problems with entrained air in the cardiac chambers or cerebral vessels. No embolic strokes in our series confirmed the merits of this approach.

Cerebral protection and circulatory arrest
We did not note any major adverse neurologic outcomes with the use of hypothermic circulatory arrest employing a pH stat strategy. Aprotinin was used in the last 10 cases, with appropriate regulation of the activated clotting time using kaolin rather than celite tube testing. We believe that packing the head in ice, the use of a steep Trendelenburg position, and carbon dioxide in the operative field are all important adjuncts in preventing neurologic injury, as well as avoiding clamping the aortic arch. Clearly, the risk for cerebral injury is also time related. The mean arrest time in this series was 32 minutes, with no patient requiring greater than 60 minutes, which reassures us that circulatory arrest can be safely used for this lesion. We did not use retrograde cerebral perfusion strategies in our series, because we believe that the current body of literature does not demonstrate this technique to significantly contribute to cerebral protection [13]. The risk for stroke with the use of aprotinin in deep hypothermic circulatory arrest may have been overstated in the past because of the measurement of the activated clotting time using celite rather than kaolin activation [14, 15]. In our series, only 1 patient returned to the theater for postoperative bleeding. This patient had a preoperative hypovolemic cardiac arrest due to massive hemoptysis, resulting in a gross coagulopathy, and was operated on before the use of aprotinin at our institution. Therefore, we believe that the benefits of aprotinin outweigh any possible thrombotic risk.

Aortobronchial fistula
Massive hemoptysis in the setting of prior coarctation repair should raise suspicion of aortobronchial fistula. In these cases, emergent rigid bronchoscopy and the simultaneous institution of femorofemoral bypass is indicated. The use of a bronchial blocker in the left main bronchus and the aspiration of the right bronchial tree may be required while establishing cardiopulmonary bypass.

In 2 such cases, pleural flaps were used to protect the prosthetic aortic graft from bronchial contamination. In the third case, an omental flap was employed where the fistula was large and the contamination gross.

Comparison with other surgical series
Other surgical series have noted significant morbidity and mortality after aneurysm repair. In the largest series of 30 cases, Knyshov and colleagues [5] reported a 13% mortality and 13% incidence of recurrent laryngeal nerve palsy. Other authors have also reported a high rate of recurrent nerve injury, ranging from 22% to 36% [2, 16, 17], as well as significant rates of bleeding and paraplegia [16, 17].

Endoluminal repair
The endovascular repair of an isolated thoracic aneurysm was first reported in 1988 [18]. Since then, experience has grown. More recently, the deployment of endoluminal stent grafts in post-coarctation-repair aneurysms has been described in a small series [19]. Although good early results were reported, we have a number of concerns about this technique. First, given the young age of these patients, the durability of stents remains a concern. Early experience with prototype stents for infrarenal aneurysms has shown problems with long-term durability [20]. As yet, no long-term data are available on commercially available stents. Second, in our series, we often found that the aneurysm was in close proximity to the left common carotid artery and in 6 of our cases involved the left subclavian artery. Although covering the left subclavian artery with endovascular stent grafts is a recognized technique, we believe that antegrade perfusion is preferable in this group of young patients. Aneurysmal involvement at the base of the left common carotid precludes the use of endoluminal repair in our opinion. Last, if there is persistence of transverse arch hypoplasia, the presence of a deployed endoluminal devise may produce unacceptable intraluminal obstruction.

Conclusions
Given the reoperative difficulties and fragile nature of these aneurysms, we believe that circulatory arrest using the technique described offers the best approach to this difficult pathology. Our results suggest that safe periods of deep hypothermic circulatory arrest can be used with a low rate of bleeding, paraplegia, recurrent nerve injury, and other neurologic sequelae. As more and more children operated for coarctation survive into adulthood, aneurysms at the repair site may be seen with increasing frequency, calling for a surgical strategy that can offer young adult patients the lowest risk for major morbidity.

	References

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This Article Abstract Full Text (PDF) Alert me when this article is cited Alert me if a correction is posted Citation Map Services Email this article to a friend Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Add to Personal Folders Download to citation manager Author home page(s): Nicholas Kang Andrew J. B. Clarke Ian A. Nicholson Richard B. Chard Permission Requests Citing Articles Citing Articles via HighWire Citing Articles via Google Scholar Google Scholar Articles by Kang, N. Articles by Chard, R. B. Search for Related Content PubMed PubMed Citation Articles by Kang, N. Articles by Chard, R. B. Related Collections Great vessels