Ann Thorac Surg 1998;65:1751-1754
© 1998 The Society of Thoracic Surgeons
Original articles: cardiovascular
Coarctation Repair: Modification of End-to-End Anastomosis With Subclavian Flap Angioplasty
Hagop Hovaguimian, MDa,
V. Senthilnathan, FRCSa,
John P. Iguidbashian, MDa,
David M. McIrvin, MDa,
Albert Starr, MDa
a Albert Starr Academic and Research Institute, Portland, Oregon, USA
Accepted for publication January 28, 1998.
Address reprint requests to Dr Senthilnathan, 10 First Main Rd, Sylvan Lodge Colony, Kilpauk, Chennai 600 010, India
e-mail: (sreesen{at}giasmd01.vsnl.net.in)
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Abstract
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Background. Subclavian angioplasty and resection and end-to-end anastomosis for coarctation repair carry a substantial risk of recurrence of coarctation. The combined technique using both these methods has shown good results but requires a longer period of continuous cross-clamping of the aorta.
Methods. A modified technique using intermittent cross-clamping with a period of reperfusion between cross-clamping periods was used. After the end-to-end anastomosis the clamps are released for 10 minutes and reapplied to do the subclavian angioplasty. Between 1991 and 1996 this was done in 26 infants (mean age, 5 weeks; range, 1 day to 6 months; median, 3 weeks). Mean weight was 3.85 kg (range, 1.5 to 8.4 kg). Mean length of follow-up was 23 months. Twenty-two patients (85%) had associated anomalies, excluding patent ductus arteriosus, and 5 patients (19%) had another procedure performed at the same time.
Results. There was no mortality. The mean echocardiographic gradient was 4 mm Hg in the immediate postoperative period and 2.9 mm Hg during follow-up. Residual or recurrent coarctation as detected by significant echocardiography or blood pressure gradient did not develop in any infant.
Conclusions. This modified technique of anastomosis is an effective way of relieving coarctation with excellent intermediate-term results.
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Introduction
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The choice of surgical treatment for coarctation of the aorta remains controversial. Among the techniques described, resection and end-to-end anastomosis, subclavian flap angioplasty, and prosthetic patch angioplasty have been the most widely reported [1–3]. When used in neonates and young infants, the subclavian flap and end-to-end techniques have resulted in varying degrees of recurrence of the coarctation, usually about 12% for end-to-end anastomosis [4, 5] and 3% to 25% in most series for the subclavian angioplasty [5, 6]. In 1987, Dietl and Torres [7] reported good results with a combined technique of resection and end-to-end anastomosis with subclavian angioplasty. This technique generally requires longer continuous cross-clamping of the aorta than either technique used alone. Since 1991 we have used with good results a modification of the combined technique with intermittent cross-clamping of the aorta and a period of reperfusion between cross-clamping periods. This article describes the modification and reports the results of a retrospective analysis of all our infant coarctation repairs done using this technique.
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Material and methods
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Patients
The clinical records of the 26 patients operated on for coarctation of the aorta using the modified dual technique between 1991 and 1996 were reviewed retrospectively. Preoperative diagnosis was confirmed in all patients by echocardiogram with 5 patients (19.2%) having an angiogram as well. Mean age of the patients was 5 weeks (range, 1 day to 6 months) with a median of 3 weeks. The mean weight was 3.85 kg (range, 1.5 to 8.4 kg). Coarctation locations as identified by echocardiography and confirmed later at operation were as follows: juxtaductal, 18 (69.2%); postductal, 6 (23%); and preductal, 2 (7.6%). Associated arch hypoplasia was identified as present when the preoperative echocardiogram demonstrated more than a 40% reduction in diameter of the proximal arch or more than a 50% reduction in diameter of the distal arch as compared with the ascending aorta. Hypoplasia of the distal arch (between the left carotid artery and the left subclavian artery) was noted in 5 patients (19.2%); both the distal and the proximal arch (between the innominate artery and the left carotid artery) were hypoplastic in 3 (11.5%); the isthmus alone in 3 (11.5%) and both the distal arch and the isthmus in 2 patients (7.6%) were also hypoplastic. In 1 patient (3.8%) all these segments were noted to be hypoplastic. Associated cardiac anomalies were present in 22 patients (85%), and 5 patients (19%) had another procedure done at the same time (Table 1). All patients were followed up as outpatients with two-dimensional echocardiography and Doppler assessment of pressure gradient across the repair site at varying intervals. The mean follow-up was 24.9 months, and no patients were lost to follow-up.
Surgical technique
The patient is positioned for a standard left posterolateral thoracotomy after intubation and placement of a right radial artery line for blood pressure measurement. The chest is entered through the third intercostal space. Dissection is done with diathermy and bluntly to mobilize the distal arch, isthmus, descending aorta, and left subclavian artery. The ductus/ligamentum is ligated close to the pulmonary artery. Vascular clamps are applied, the proximal one occluding the distal arch proximal to the left subclavian artery and the distal one beyond the coarctation segment (Fig 1). The coarctation segment is then resected and an end-to-end anastomosis carried out using 7-0 monofilament polypropylene continuous suture; when the circular anastomosis is nearly completely constructed, suturing is stopped leaving a gap of about 2 mm and the untied ends of the sutures are snared down together; at this time the aortic clamps are removed. A 10-minute reperfusion is allowed and during this period more dissection of the left subclavian artery is carried out. The vertebral artery and its distal subclavian artery are ligated separately. After 10 minutes the clamps are reapplied, with the proximal one on the distal arch, leaving the subclavian free; the subclavian artery is then transected as far distally as possible and opened longitudinally carrying the incision onto the isthmus across the incomplete anastomosis distally (Fig 2). Subclavian flap angioplasty is carried out using 7-0 monofilament polypropylene continuous suture tying the ends onto the loose ends of the previous suture line (Fig 3). The clamps are released again. After hemostasis is confirmed, the pleura is closed, followed by chest closure.
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Fig 2. During the second period of cross-clamping the subclavian artery is incised longitudinally; the incision is extended below the level of the previous anastomosis.
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Fig 3. The subclavian flap is used to reinforce the end-to-end anastomosis; inset shows the completed anastomosis.
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Results
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There was no mortality postoperatively; 3 patients required prolonged ventilation but the final recovery was complete. There was no significant morbidity. The mean initial cross-clamp time was 8.8 minutes (range, 5 to 14 minutes); the mean time for the second period of clamping was 14.6 minutes (range, 11 to 21 minutes); the mean total clamp time was 23.5 minutes (range, 18 to 34 minutes). The mean follow-up period was 24.9 months. Evidence of recurrent coarctation was considered to be present if either an arm-to-leg gradient or Doppler echocardiographic gradient of more than 20 mm Hg was detected; on the basis of this criterion no recurrence of coarctation was detected at follow-up. The mean follow-up echocardiographic gradient in the early postoperative period was 4 mm Hg (range, 0 to 16 mm Hg) and the mean late gradient was 2.9 mm Hg (range, 0 to 15 mm Hg). The mean late blood pressure gradient was low as well, 3.6 mm Hg (range, 0 to 10 mm Hg).
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Comment
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The commonly used methods of coarctation repair, namely resection and end-to-end anastomosis and subclavian angioplasty, have a substantial incidence of recurrence of coarctation [4–6]. Recurrent coarctation can be caused by ingrowth or contraction of ductal tissue or by the lack of growth of arch tissue. The ductal tissue distribution is unpredictable and can extend far down into the aorta, well away from the ductus [8, 9]. It is impossible to differentiate between the ductal tissue and the aortic intima with the naked eye. If incompletely excised, as can easily happen with the end-to-end technique, the abnormal intimal and medial ductal tissue at the anastomotic site may contract and induce secondary intimal proliferation and cause recoarctation [6, 8, 9]. If the excision is too aggressive it creates tension on the suture line; these complications and the turbulence created by the frequently present hypoplastic isthmus contribute to scarring and recurrence. Hence, in spite of the advantages of the end-to-end technique as compared with the subclavian angioplasty, namely excision of the bulk of the ductal tissue along with the coarctation ledge and avoidance of subclavian artery sacrifice, this is not the ideal method. With the subclavian flap technique the advantages are no loss of endogenous tissue enabling tension-free anastomosis reinforced with the flap; autogenous tissue with potential for growth; more definitive repair of the narrowed isthmus and also the avoidance of circular suture line. The suitability of subclavian flap to adapt to the increased wall stress by increasing the wall thickness and function as living aortic tissue in adult life is well documented [10]. Although the subclavian artery sacrifice has been suggested as a causative factor in the development of the subclavian artery steal syndrome and the shortening and claudication of the left arm, these are quite rare [11, 12]. Arguments against the subclavian flap repair are well discussed by Jonas [13]; these include leaving of the ductal tissue with the risk of an unpredictable degree of remodeling; possible secondary coarctation shelf in the distal arch; increased risk of late aneurysm formation in the abnormal tissue, especially if there is a need for balloon dilation; and the rare but documented sequelae of the loss of subclavian artery blood supply to the arm. The other commonly reported technique of prosthetic patch angioplasty avoids circular constrictive anastomosis, provides tension-free anastomosis, requires little or no mobilization of the aorta, and can be performed easily and rapidly. But it has the potential hazards of implanted foreign material, including degeneration and aneurysm formation, found in as high as 67% of patients with follow-up [14].
In 1987, Dietl and Torres [7] described the technique of combined resection and end-to-end anastomosis with subclavian flap angioplasty. It involves the resection of the bulk of the ductal tissue with the coarctation ledge and the augmentation of the isthmus with a live arterial wall flap. The dual technique seems to have many advantages over other methods. It has the sound basis of combining the benefits of both of the classic procedures. As described by Dietl and colleagues [15], the advantages of the dual technique would be that the coarctation segment is completely excised, excising most of the ductal tissue along with any posterior shelf in the aortic wall with it; the anastomotic diameter is 1:1.5 to 2 times larger than it is usually obtained with a simple end-to-end anastomosis; the suture line is noncircumferential; the viable flap of subclavian artery has growth potential; and this procedure is applicable in the presence of a long narrow isthmus, which is frequently present in neonatal coarctation.
In spite of these advantages this method is not commonly used; this technique usually requires a longer continuous cross-clamping of the aorta to construct the dual anastomosis than with either technique used alone. It is probably believed that the longer clamp time decreases the safety margin for potential morbidity, especially ischemic injury of the spinal cord. The suggestion of Dietl and colleagues [15] of using an intraaortic shunt seems too cumbersome and possibly dangerous.
The intermittent clamp technique described in this article eliminates the undesirable component of the combined technique, namely the danger of prolonged continuous clamp time. Our modification with a period of reperfusion in between probably decreases the potential complications, compared with one long continuous period of ischemia; the principle of ischemic preconditioning, well established in the case of the myocardium [16], might apply to the neural tissue of the spinal cord. The recovery time of 10 minutes between the two clamp times has been selected empirically. Earlier on few of our operations were done with spinal-evoked potential monitoring, which showed complete recovery of the potentials in approximately 5 minutes after the release of the aortic cross-clamp after completion of the final anastomosis. In this series we did not detect any morbidity related to two separate periods of aortic cross-clamping, although the overall cross-clamp time was longer than with either technique used alone. The modification also does away with the need for an intravascular shunt during the construction of the anastomosis [15].
Our follow-up results have been very satisfying with no cases of recurrent or residual coarctation, with only negligible gradients noted by echocardiogram and arm–leg blood pressure measurements. In this series evidence of recurrent coarctation was considered to be present if either an arm–leg gradient or echocardiographic gradient of more than 20 mm Hg was detected. The most important risk factor for recoarctation has been shown to be younger age at the time of operation [17]; the mean age of our group was 5 weeks and we found no recurrences. This technique can be used successfully in the smallest of patients. Also, although half the patients in the study required the operation in an urgent manner we found no significant morbidity or mortality related to the longer cross-clamp times; the same was true for patients requiring a concomitant procedure at the time of the coarctation repair. This technique deals effectively with isthmic hypoplasia; admittedly it does not specifically counter the hypoplasia of the proximal and distal arches. The hypoplasia seems to improve once the obstructive coarctation is relieved and the blood flow pattern through the aorta is restored to normal, especially in younger patients [18]. No significant gradient across the aortic arch was noted in the follow-up studies in our group, although 11 of the 26 patients were noted to have some degree of hypoplasia of either the proximal or the distal arch, or both, preoperatively. Persisting hypertension requiring medication was seen in 2 patients; both did not have any significant gradient on echocardiographic examination. Our mean follow-up period was 23 months; although this is limited, a number of studies have shown that the majority of recoarctations occur within the first year of life regardless of the type of repair used [6, 19]. Thus, the technique we have used combines the advantages of both the resection and end-to-end anastomosis and the subclavian flap techniques with no obvious added morbidity.
In conclusion, the perfect technique of coarctation repair suited for all patients has not yet been devised. One has to keep in mind the necessity to tailor the choice of procedure according to the inherent anatomic variables of coarctation. To this end, some type of surgical classification as suggested by Amato and colleagues [20] may be useful. Probably the most critical issue is tension-free apposition of normal tissue ensuring growth at the site of anastomosis. The dual technique combines many of the advantages of resection and end-to-end anastomosis and subclavian flap angioplasty. Our modification increases the safety margin and should diminish the potential morbidity of a long continuous cross-clamp time; we believe it could be applied successfully in a large number of patients with coarctation. The initial follow-up results have been excellent and we recommend this approach, especially in neonates and young infants, where there is an increased risk of recoarctation.
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Acknowledgments
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We thank Ms Joannie Livermore for helping with the illustrations.
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References
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Abstract
Introduction
