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MMCTS
(March 28, 2008). doi:10.1510/mmcts.2007.002691 Copyright © 2008 European Association for Cardio-thoracic Surgery Procedure Neonatal coarctation repair using extended end-to-end anastomosisPediatric Cardiac Surgery Unit, S. Orsola-Malpighi Hospital, University of Bologna Medical School, Via Massarenti n. 9, 40138 Bologne, Italy * Corresponding author: Tel.: +39-051-6363156; fax: +39-051-6363157 gaetano.gargiulo{at}aosp.bo.it
Aortic coarctation without associated intracardiac lesions, with or without posterior arch hypoplasia referred as simple coarctation, is safely and effectively repaired via left posterolateral thoracotomy, whereas median sternotomy and cardiopulmonary bypass are necessary for aortic arch reconstruction in case of complete aortic arch hypoplasia, or coarctation with associated cardiac lesions. There is a wide variety of techniques currently proposed to repair neonatal coarctation, all reported associated with very low operative mortality, nevertheless which one would be the best technique in terms of minimal rate of residual or recurrent obstruction or late complications is still under debate.
Key Words: Aortic arch hypoplasia • Aortic coarctation • Coarctation repair • Neonatal
Coarctation of the aorta is a narrowing in the descending thoracic aorta distal to the origin of the left subclavian artery in the region, named isthmus, where the ductus arteriosus is attached. It can be either as a localized stenosis or as a tubular hypoplastic segment; aetiology is unknown and it occurs between 5% and 10% of all congenital heart disease. Isolated aortic coarctation has a male to female predominance that has been reported between 2:1 and 4:1 and it is extremely common in Turner's syndrome patients. Aortic coarctation can occur as an isolated lesion or more frequently in association with other cardiac anomalies such as: bicuspid aortic valve, ventricular septal defect, atrial septal defect, or it can be part of a complex congenital malformation: Taussig Bing anomaly, hypoplastic left heart syndrome, tricuspid atresia with transposition or other ‘single ventricle’ variants. It can be associated with multiple left heart structures hypoplasia in the Shone's syndrome. Aortic arch hypoplasia is frequently associated with aortic coarctation so that the aortic arch can be: entirely hypoplastic (anterior and posterior arch hypoplasia: from the innominate artery to the isthmus) or partially hypoplastic (posterior arch hypoplasia: between the left carotid artery and the isthmus). Aortic coarctation without associated intracardiac lesions (except for bicuspid aortic valve), with or without posterior arch hypoplasia, is generally regarded as ‘simple’ coarctation and it is preferably approached via left posterolateral thoracotomy. The term complex coarctation refers to the combination of aortic coarctation and other intracardiac lesions and is very often approached via median sternotomy and repaired under cardiopulmonary bypass and deep hypothermic circulatory arrest or selective cerebral perfusion. In selected situations complex coarctation can be treated via thoracotomy by a staged approach with associated banding of the pulmonary artery. Natural history of untreated simple coarctation is indeed poor with a mortality rate of 25%, 50%, 75% and 92% by the age of 20, 32, 46 and 60 years, respectively [1]. Surgical repair is nowadays regularly performed in the first days of life with very low mortality, even though long-term complications, such as recoarctation or aneurysms formation, are still reported to be quite frequent. The ideal technique of repair, particularly in consideration of minimizing long-term sequelae is still controversial.
Pathophysiology Two embryologic reasons have been advocated to explain the occurrence of arch hypoplasia and aortic coarctation.
However, aortic coarctation and transverse arch hypoplasia may coexist, thus indicating that an intracardiac lesion promoting a left to right shunt in the intrauterine life may result in both underdevelopment of the aortic arch and ductal cells migration to the aortic isthmus.
Indications Other inconstant symptoms can be: shortness of breath, especially during exercise, headache, muscle weakness, leg cramps or cold feet, nosebleeds. More frequently the coarctation is severe and the systemic circulation may be in some extent ductus-dependent after birth. Patients may show sudden low output symptoms at the time of ductal closure, with low urine output, systemic acidosis and high skin to core temperature gradient. Hypo perfusion of the abdominal organs can cause necrotizing enterocolitis or liver dysfunction. Nevertheless, symptoms of congestive heart failure due to the severe systemic obstruction may also be present, with left ventricle dilatation and dysfunction, high left atrial and left ventricular end diastolic pressures, paleness, irritability and sweat and difficulty breathing. The absence of lower limbs pulse may suggest the diagnosis. Surgery is indicated, in case of severe coarctation, within the first few days of life and a prostaglandin E2 infusion should be promptly started at the time of diagnosis.
After positioning a jugular trilumen venous line, a peripheral vein and a right radial or brachial artery catheter, the patient is turned on his/her right lateral decubitus on a towel roll and a posterolateral thoracotomy in the 3rd intercostal space is done. Stay sutures are placed on the pleura interposing a wet gauze to keep the lung retracted. Extensive dissection and mobilization of the descending aorta aortic arch and branches, up to the innominate artery is performed (Video 1).
The ductus arteriosus is ligated. Two clamps are positioned at the aortic arch and descending thoracic aorta (Schematic 1). If a more proximal extension of the anastomosis is needed, the left common carotid artery can be safely occluded as well with the first clamp, thus allowing flow into the innominate artery only (Video 2).
The aortic isthmus is divided just above and below the ductus and the ductal tissue is completely excised (Video 3).
A longitudinal incision is made in the posterior wall of the descending aorta and a second generous incision is made in the arch concavity up to the base of the left carotid artery (or beyond). An equal circumference of the two aortic ends is obtained (Video 4).
The anastomosis is completed with a 7/0 PDS reabsorbable running suture (Videos 5, 6, 7).
Residual pressure gradient across the anastomosis, considered significant when more than 10 mmHg, is routinely ruled out by direct needling the descending aorta before chest closure.
Several problems may persist or develop early or late after coarctation repair.
Early complications Postoperative systemic hypertension known as paradoxical hypertension can occur in up to 1/3 of the patients for imbalances in sympathetic discharge, increased sensitivity of aortic and carotid baroreceptors and increase levels of circulating renin and angiotensin. Nevertheless paradoxical hypertension should be transient most of the time, in patients with no residual gradient in the aortic isthmus and it is probably related to the age at the time of repair. Post coarctation syndrome is a life threatening but fortunately rare complication; its cause is not actually well understood: it may be due to mesenteric arteritis secondary to acute inflammation or to splanchnic vasospasm secondary to the increased blood perfusion causing gastrointestinal bleeding and diffuse necrosis. Paraplegia is very rare in the neonatal population; few cases have been reported in association with aberrant right subclavian artery and very long clamping time.
Late complications Late aneurysms formation is reported in patients who have been treated with patch aortoplasty, particularly those with residual posterior aortic arch hypoplasia or those who have had resection of the aortic shelf. Persistent hypertension has been shown to occur particularly in patients operated at older ages.
Between January 1990 and April 2007, 116 patients <6 months of age with aortic coarctation underwent coarctation repair via left postero-lateral thoracotomy. Eighty-nine underwent end-to-end extended anastomosis, 15 underwent end-to-end anastomosis and subclavian flap turn up enlargement of the posterior arch and 12 had patch reconstruction. Median age was 13.5 days (range 1–180 days), 88 (76%) patients were neonates and 110 (95%) patients were younger than 3 months. Median weight was 3.1 kg (range 1–6.6 kg), 29 (25%) patients weighed <2.5 kg at the time of surgery. Patients with complex coarctation who underwent repair through median sternotomy under cardiopulmonary bypass are not included in this chapter, as well as patients older than 6 months at the time of surgery. Sixteen patients (only one after the introduction of selective cerebral perfusion in our practice) had a pulmonary artery banding at the same time of the coarctation repair for associated ventricular septal defects (n=14) or atrio-ventricular septal defect (n=2). The ventricular septal defects were muscular, single or multiple in 11 patients and large cono-ventricular in three. None of the patients died before hospital discharge. Post coartectomy syndrome or neurological complications were not observed; systemic paradox hypertension occurred in 15% of the patients and was transient in all. Median follow-up time was 8.3 years (range 1 month to 17.5 years). During this time none of the patients died and nine patients (8%) underwent balloon aortoplasty for recurrent coarctation between 3.7 and 39.5 months after the primary coarctation repair (median 6.7 months); seven had received an end-to-end extended anastomosis (7/89) (8%) and two a PTFE patch repair 2/12 (17%). Indication to balloon dilatation was for trans-isthmus peak gradient above 20 mmHg at echocardiogram. Surgical reintervention on the aortic arch and isthmus was never required. Actuarial freedom from surgical or catheter re-operation was 92%±2.7 at 10 years (Graph 1).
All the survivors are currently asymptomatic with no medications and no significant isthmus gradient or systemic chronic hypertension; the sixteen patients who had undergone a staged approach have all completed the repair successfully.
Since the first repair by Crafoord and Gross, the surgical treatment of coarctation has been shifted progressively towards the very early period of life. Mortality has been dramatically reduced since the introduction of PGE2 [4], which allows a preoperative complete stabilization of the patient conditions [5]. Since operative mortality has become very low over the last two decades, surgical attention has been shifted to minimize the early and late complications which have been reported to be still consistent such as: residual or recurrent obstruction, aneurysm formation, systemic hypertension and aortic dissection. The ideal surgical repair should minimize the rate of residual obstruction and coarctation recurrence without long-term sequelae such as systemic hypertension and aneurysm formation. Balloon angioplasty which has become the treatment of choice for recoarctation with up to 90% of successful results and minimal rate of complications has been shown to be little effective with neonatal native coarctation [6] with an unacceptable recoarctation rate: 83% for neonates and 39% for infants, respectively [7]. Moreover, late aneurysm formation was found in about 12% of the patients [8]. The ideal technique of repair, particularly in regard to minimizing long-term complications is therefore still controversial. The following surgical techniques have been proposed and compared [9] so far: (1) Patch aortoplasty introduced by Vossschulte [10] is an easy technique which can be useful in case of a long tubular coarctation, to avoid extensive dissection, collaterals sacrifice and high tension on the anastomosis particularly in older infants, moreover, it cannot be very useful if simultaneous hypoplastic posterior arch repair is needed. However, it has been reported to be associated with aneurysm formation of the opposite wall or on the patch material [11,12,13,14], particularly when associated with residual arch hypoplasia. (2) Subclavian flap turn down aortoplasty is a simple technique but it requires left arm artery sacrifice and it has been reported to carry a high rate of recoarctation [15] possibly due to the incomplete elimination of the ductal tissue and the intraluminal shelf. (3) Resection with simple end-to-end anastomosis has become the technique of choice particularly in neonates due to the avoidance of prosthetic materials. An extensive dissection and mobilization of the aorta and branches is required to achieve a tension- free anastomosis, however, a high rate of recoarctation is reported [16, 17]. Use of absorbable monofilament suture can help in minimizing the recurrence of obstruction due to the circular suture scar. (4) End-to-side anastomosis could be a valid alternative and it has been shown effective in reducing the risk of residual or recurrent obstruction resolving the posterior arch hypoplasia and avoiding incorporation of any abnormal tissue which is believed to be responsible for recoarctation [18]. (5) Resection with extended end-to-end anastomosis is nowadays the most worldwide spread technique, since the larger anastomosis has shown to be particularly effective in minimizing the recoarctation [19, 20] while simultaneously addressing the posterior arch hypoplasia [19]. To solve the residual obstruction and enlarge the posterior arch also composite techniques have also been suggested in association with the end-to-end anastomosis: (6) subclavian flap turn up (described by Amato et al. [21] and after utilized by others [22]), (7) subclavian reimplantation, which avoids the arm blood supply sacrifice, (8) patch enlargement, and (9) elevation of the ‘roof’ of the posterior arch connecting the bases of the left common carotid and subclavian arteries [23]. Graft interposition and bypass graft repair should be avoided in neonates and infants because of the need for future re-operations due to patient's outgrowth.
Simple aortic coarctation with or without posterior arch hypoplasia is successfully repaired via thoracotomy with minimal operative mortality but still a high rate of complications (Table 1).
Coarctation with ventricular septal defect is nowadays repaired in a single stage via median sternotomy even though coarctation repair and pulmonary artery banding in thoracotomy may still be preferred in rare selected cases when the repair can be challenging, such as in the presence of multiple ventricular septal defects or apical ventricular septal defect. End-to-end extended anastomosis [24,25,26] is effective to address simultaneously the coarctation and the posterior arch tubular hypoplasia with very low incidence of both residual and recurrent obstruction and with no need for prosthetic materials (Schematic 2; Video 8; Graph 1).
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Introduction
