Ann Thorac Surg 2000;69:877-880
© 2000 The Society of Thoracic Surgeons
Original Articles
Modification of the subclavian patch aortoplasty for repair of aortic coarctation in neonates and infants
Bradley S. Allen, MDa,b,
Ari O. Halldorsson, MDa,b,
Mary Jane Barth, MDa,b,
Michel N. Ilbawi, MDa,b
a Division of Cardiothoracic Surgery, Heart Institute for Children, Hope Children’s Hospital, Oak Lawn, Illinois, USA
b The University of Illinois at Chicago, Chicago, Illinois, USA
Address reprint requests to Dr Allen, Heart Institute for Children, Hope Children’s Hospital, 4440 W 95th St, Oak Lawn, IL 60453
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Abstract
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Background. Coarctation repair in neonates or small infants, using a subclavian patch, has a relatively high risk of restenosis, especially if complicated by the presence of a short subclavian artery or long coarctation segment. We introduce a technical modification that facilitates the use of a subclavian flap, and decreases the restenosis rate in this subgroup of patients. It consists of a side-to-side transverse aortic anastomosis at the level of the coarctation, which widens the coarctation segment, shortens the isthmus, and pulls the distal end of the aortotomy proximally, allowing a tension-free subclavian flap aortoplasty.
Methods. Fifty-three consecutive neonates or infants less than 18 weeks old, with complex coarctation, underwent repair using this technique. Mean age was 26 ± 3 days and 36 patients (68%) were less than 28 days old. Weights ranged from 1.4 to 6.4 kg (mean 3.4 ± 0.2 kg), and 26 patients had other cardiac anomalies. Preoperative gradient by Doppler measurement ranged from 25 to 90 mm Hg (mean 49 ± 2 mm Hg).
Results. Mean aortic cross-clamp time was 27 ± 1 minutes (range 19 to 34 minutes). There were no deaths or surgical complications. Follow-up echocardiogram 4 to 52 months postoperatively (mean 25 ± 2 months) demonstrated no significant pressure gradient (less than 20 mm Hg) in 51 of 53 patients (96%), and a significant gradient in 2 patients (4%), which was subsequently corrected with balloon angioplasty.
Conclusions. The technical modification described shortens the isthmus, and thus allows for a longer aortotomy distal to the area of coarctation resulting in a tension-free repair especially in patients with a short subclavian artery. It also widens the area of coarctation, and as a result leads to a lower early recoarctation rate in this high-risk group. With increasing emphasis on the need for a longer aortotomy to prevent restenosis, this modification will have increasing application, especially in the neonatal population.
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Introduction
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Although the accepted treatment for symptomatic coarctation in neonates and small infants is surgical correction, the procedure of choice remains controversial. Currently, the most commonly used techniques for surgical management of infant coarctation are resection with end-to-end anastomosis, subclavian flap angioplasty, and extended aortoplasty [1–3]. Each technique has specific advantages and disadvantages, but a relatively high recoarctation rate remains a major problem. Recent reports comparing the various techniques have been inconclusive as to what constitutes the best approach [4–10]. Yet, they strongly indicate that the incidence of recoarctation may be higher if ductal tissue is either not completely removed, or the subclavian flap is not sufficiently long enough to bridge the coarctation segment without tension [2, 3, 9–14].
We have used the subclavian flap angioplasty for several years with good results. However, in infants with an unusually long coarctation segment, short subclavian artery, or a narrow isthmus, subclavian flap angioplasty may have an increased risk of recoarctation because of the inability of a short arterial flap to reach comfortably beyond the ductal tissue, while still being redundant enough to enlarge to area of coarctation. Therefore we have modified our technique in an attempt to minimize these problems.
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Patients and methods
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Between January 1993 and July 1998, 53 consecutive infants less than 18 weeks old underwent subclavian flap angioplasty using our new technique. Patients undergoing additional cardiac procedures, with the exception of pulmonary artery banding, were excluded. Age ranged from 2 to 126 days (mean 26 ± 3 days), and 36 (68%) were younger than 28 days. Weight ranged from 1.4 to 6.4 kilograms (mean 3.4 ± 0.2 kgs), and 41 patients (77%) were less than 4 kgs. All infants were symptomatic on medical treatment at the time of operation. Preoperative gradient across the coarctation by Doppler studies ranged from 25 to 90 mm Hg (mean 49 ± 2 mm Hg). Twenty-six patients had other cardiac anomalies, which included 14 ventricular septal defects, 6 aortic stenosis, 3 small atrial septal defects, 1 atrioventricular septal defect, 1 double-outlet right ventricle, and 1 mitral stenosis. Six patients had concomitant pulmonary artery banding. All values are expressed as mean ± standard error of the mean. A gradient of 20 mm Hg or more across the repair was considered significant for restenosis.
Surgical technique
The operation is performed through a standard left posteriolateral thoracotomy. The mediastinal pleura over the aorta and subclavian artery is dissected and the anatomy carefully accessed. The aorta is mobilized and all intercostal arteries are preserved. The ductus is then ligated and the aorta is cross-clamped proximally between the left subclavian and left common carotid arteries, and distally far enough on the descending aorta to allow for a long aortotomy (Fig 1). The intercostals are usually controlled with the same vascular clamp. The ligated subclavian artery is divided as distally as possible and a lateral arteriotomy, extending along the whole length of the subclavian artery through the coarctation segment and into the distal descending aorta, is performed. The arteriotomy is carried distally for a sufficient length, well beyond the area of ductal tissue (Fig 2A). The proximal and distal aortic walls at the level of the coarctation are joined together in a transverse fashion using running 7.0 Prolene suture (Ethicon, Somerville, NJ) (Fig 2B, C). This maneuver widens the coarctation, shortens the isthmus, and pulls the descending aorta proximally, thus allowing a tension-free anastomosis of the subclavian flap, even with a long aortotomy or short subclavian artery. If further shortening of the aorta is necessary to prevent flap tension, a second side-to-side aortic anastomosis is performed on the other side of the coarctation using running Prolene suture (Fig 2D). The subclavian flap is then sutured to the aorta in the standard fashion using running 7.0 Prolene suture (Fig 3A, B). The clamps are removed at the completion of the anastomosis.
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Fig 1. Discrete aortic coarctation in an infant with a small ductus arteriosus, seen through left thoracotomy exposure. The pleura has been dissected off the aorta and ligatures have been placed around the small ductus or ligamentum arteriosum and distal left subclavian artery. The dotted line indicates the planned aortic and left subclavian incision.
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Fig 2. (A) Vascular clamps have been placed on the aortic arch and descending aorta, and intercostal branches controlled. The aorta and left subclavian have been opened and the left subclavian artery divided just proximal to the ligature. (Note: The aortotomy is carried distally for sufficient length to be well outside the area of ductal tissue to help prevent recoarctation.) (B) Starting at the level of the coarctation, the anterior-medial wall of the descending aorta is sutured to the aortic isthmus in a transverse fashion using running 7-0 Prolene (Ethicon, Somerville, NJ) suture. (C) The completed plication. (Note: This maneuver widens the coarctation, shortens the isthmus, and pulls the aortotomy proximally, thus allowing for a tension-free anastomosis of the subclavian flap, even with a long aortotomy or short subclavian artery.) (D) If further shortening of the aorta is necessary to prevent flap tension, the opposite aortic wall is also sutured to the isthmus with another running Prolene suture.
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Fig 3. (A) The subclavian flap is sutured to the aorta in the standard fashion using running 7-0 Prolene (Ethicon, Somerville, NJ) suture. (B) At the level of the enlargement, the two sutures are tied and the remaining repair of the coarctation with the subclavian flap is finished.
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Results
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There were no operative deaths or major complications related to the surgical procedure. Aortic cross-clamp time ranged from 19 to 34 minutes (mean 27 ± 1 minutes). Three patients developed minor wound separation. All patients were asymptomatic at the time of follow-up. Echocardiogram with Doppler studies, performed 4 to 52 months postoperatively (mean 25 ± 2 months), demonstrated no significant gradient (mean 5 ± 1 mm Hg, range 0 to 16 mm Hg) in 51 patients (96%). Two patients (4%) had a significant gradient (40 and 48 mm Hg) across the repair, which was successfully relieved with a balloon angioplasty. These recurrences occurred early in both patients, becoming evident at 5 and 9 months postoperatively. Review of these 2 patients revealed no anatomic or technical differences compared to the rest of the study population.
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Comment
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Recoarctation remains a significant problem after repair of aortic coarctation in infancy. Although results are improving, recent studies still show a recoarctation rate of 11% to 43% in this age group [4–11, 15]. The etiology of this restenosis is not fully understood, but residual ductal tissue in the aortic wall definitely plays a role. Several pathologic studies have shown, that in patients with coarctation the ductal tissue extends much further into the aortic wall, both circumferentially and longitudinally, than normal [16–19]. Russell and associates examined resected coarctation segments and found that, in addition to the circumferential sling of ductal tissue, 15 to 22 specimens had extension into the distal aorta [18]. In 11 of these 15 patients, the resection of the ductal tissue was incomplete, leaving a residual island of ductal tissue in the aorta. This occurred despite total resection of all ductal tissue during operation as judged by the naked eye. Thus, if during subclavian flap angioplasty the aortotomy is not carried far enough distally to extend beyond the prolongation of ductal tissue, the potential for restenosis exists. This theory is supported by the facts that: (1) recurrence of recoarctation after the subclavian flap angioplasty is much more likely to occur in neonates and young infants in whom maturation and growth potential of the ductal tissue is retained; (2) the restenosis often occurs at the distal end of the flap; and (3) that restenosis is usually seen relatively early (within 12 to 24 months), after operation [2–15, 20, 21]. Therefore, a long aortotomy, sufficiently distal to the coarctation must be carried out to insure that the circumferential or longitudinal extension of ductal tissues has been sufficiently interrupted or bridged [2, 3, 11–13].
Performing a long aortotomy that extends a significant distance past the area of coarctation may not be technically feasible in some infants because the subclavian artery is not always long enough to comfortably bridge the gap. Under these circumstances, a long aortotomy results in tension on the subclavian flap which may increase the rate of restenosis. In contrast, the modification described pulls the descending aorta proximally by suturing it transversely to the isthmus, thus increasing the diameter of the vessel at the coarctation site, as well as providing a tension-free closure even in the presence of a short subclavian artery or long aortotomy.
The frequent association of aortic isthmus hypoplasia with coarctation is quite important in the surgical decision making. In a study of 43 autopsy specimens of patients younger than 3 months who had aortic coarctation, only 7 had an isolated short shelf-like coarctation whereas 36 of 43 had a long narrow segment (narrow isthmus), with or without a shelf [16]. Therefore, special attention must be paid to bridging the often long coarctation segment, as well as making sure the isthmus is adequately enlarged when it is found to be narrowed. Several studies have echoed this view, and several surgical procedures have been introduced to address these concerns [1, 2, 22–24]. The two most common procedures, resection with subclavian flap angioplasty and extended end-end anastomosis, have not gained wide acceptance because of their complexity, the need for extensive mobilization of the aorta, or possible injury to intercostal arteries. Our technique solves these anatomic problems with a much simpler approach. By plicating one (Fig 2B, C), and sometimes two sides of the aorta at the level of the coarctation (Fig 2D), the coarctation is widened and the isthmus shortened. This approach therefore accomplishes the same goals as resection with subclavian flap angioplasty but avoids the complexity of a circumferential suture line, more extensive mobilization, and longer cross-clamp time. It does not however, address the issue of aortic arch hypoplasia frequently associated with coarctation. In the majority of cases (96%, unpublished data) such hypoplasia disappears over time, as the normal portion of the cardiac output now flows through the arch. Hence, no surgical intervention is needed for small aortic arches in most infants and newborns.
Patients with complex coarctations, ie those with hemodynamically significant lesions amenable to concomitant repair, have been excluded in this report to preserve the homogenicity of patient population. The technique described is quite applicable to the anterior transmediastinal approach needed for simultaneous repair of these anomalies. However, it loses its advantage when used in this setting, since most of these complex coarctations can be repaired by resection of ductal tissue and patch enlargement of the narrowed aorta.
General aspects of our technique warrant discussion. First, this modification is easily performed and because it adds very little to the cross-clamp time, the morbidity should be the same. No added dissection is required, and a circumferential suture line is avoided. Based on our knowledge of recoarctation pathology, it is likely that these modifications will decrease the incidence of restenosis. In this series, the rate of restenosis was only 4%, which is low for this young (68% of patients less than 28 days old) patient population. This compares favorably with results reported using other techniques [1–8, 10, 20]. Moreover, it is also unlikely the restenosis rate will significantly increase overtime because our mean follow-up was 25 months, and most restenosis occurs in the first two years. Indeed, the 2 patients who developed recurrent stenosis did so within the first 9 months, probably as a result of retained ductal tissue. Although the ductal tissue can be resected using a variety of techniques, these procedures increase the complexity of the operation without improving the rate of restenosis [2–4, 8, 10, 12]. Our technique does sacrifice the subclavian artery, which has been associated with reduced limb growth in a small percentage of patients. This reduction however, is usually imperceptible to the patient, and is less likely to occur when performed in very young infants [3]. Our technique may not be appropriate when there is severe arch hypoplasia. However, we use it routinely in patients with mild to moderately severe arch hypoplasia, since the majority of patients will have normal arch growth over time.
In summary, the ideal operation for coarctation is one that completely relieves the obstruction without morbidity, has no early or late restenosis, and can be done safely early enough in life to avoid systemic hypertension in asymptomatic patients. With more emphasis being placed on early operation to prevent late onset systemic hypertension it is likely more patients with coarctation will come to operation in the first year. The described method is very promising, as there was minimal morbidity and a low early restenosis rate. This modification is especially useful in very young patients who have a narrow isthmus, long coarctation segment, or shortened subclavian artery. Its use can also be extended to almost all infants independent of the coarctation pathology, as it adds very little complexity to the repair.
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Footnotes
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This article has been selected for the open discussion forum on the STS Web site: http://www.sts.org/section/atsdiscussion/
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Accepted for publication August 14, 1999.
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Abstract
Introduction
