Surgical Approach to Coarctation of the Aorta and Interrupted Aortic Arch Treatment & Management

The role of medical therapy in coarctation is limited. Medical therapy is confined to preoperative temporization to optimize the patient's hemodynamic status before surgery.

Since 1984, medical therapy of coarctation has revolved around the introduction of prostaglandin E1 (PGE1) therapy. PGE1 allows for reopening of the ductus arteriosus and perfusion to the lower body. When PGE1 therapy is effective, the severe acidosis and oliguria, which are often present, are corrected by reestablishing blood flow to the lower body. Optimizing the patient's hemodynamic status and converting an otherwise emergency procedure into an elective one can substantially reduce the mortality risk.

For additional information, please see Coarctation of the Aorta.

The European Society of Cardiology (ESC) updated their 2010 guidelines on the management of adult congenital heart disease (ACHD) in 2020. ^{[18, 19]}  Their class I recommendation is that repair of coarctation or recoarctation (surgically or catheter based) is indicated in hypertensive patients with an increased noninvasive gradient between the upper and lower limbs confirmed with invasive measurement (peak-to-peak ≥20 mmHg); catheter treatment (stenting) is preferred when technically feasible. ^{[18, 19]}

Several techniques are currently used to repair coarctation of the aorta. The method of repair is usually tailored to each patient. To help determine the operative approach, consider the length of the segment involved and whether associated anomalies are present. ^[20]

Several surgical methods of repair are used, including end-to-end reanastomosis, subclavian flap aortoplasty, prosthetic patch onlay grafts, and interposition grafts (see Intraoperative details), as well as sternotomy for an approach to the ascending aorta and aortic coarctation, and an ascending-to-descending aortic bypass.

Many variations of the described procedures have been used throughout the years, including modification of the subclavian flap that include reimplantation, end-to-end anastomosis using the subclavian to enlarge the anastomosis, and ascending aorta–to–descending aorta bypass grafts. All of these techniques may be useful depending on the individual anatomy and associated anomalies. ^{[21, 22, 23]}

Extra-anatomic correction, ascending-descending aorta via a median sternotomy with cardiopulmonary bypass support, seeks to provide additional blood flow to the distal aorta, but the stenosed aorta remains in place. ^[22]  Proximally, an anastomosis is created between a prosthetic conduit and the ascending aorta or the subclavian artery; distally, the prosthetic conduit is anastomosed to the descending aorta, bypassing the area of aortic coarctation. This technique is particularly valuable during concomitant cardiac procedures (aortic valve replacement, coronary artery bypass grafting). ^[22]

The repair of associated anomalies at the time of aortic coarctation repair remains controversial. Optimal management remains unclear. If concurrent repair of associated anomalies is to be attempted at the time of coarctation repair, the best approach is by means of a median sternotomy. ^[24] Coarctation repair is then carried out in a manner to that used to repair an interrupted aortic arch (IAA).

Current knowledge suggests ligation and division if a patent ductus is present. A bicuspid aortic valve can usually be left untreated. Strategy for concurrent ventricular septal defect (VSD) repair remains somewhat unclear. Previous studies indicated greatest survival in patients who underwent coarctation repair with pulmonary artery banding; but this has fallen out of favor due to the frequency of subsequent avoidable procedures and associated morbidities. If preoperative congestive heart failure (CHF) does not resolve, a second operation is required to close the VSD. If the VSD does spontaneously close, a debanding procedure is required.

Numerous VSDs associated with coarctation do spontaneously close, avoiding the need for cardiopulmonary bypass; this leads some to favor a 2-stage procedure. In 1992, Park et al demonstrated that this suggestion was a feasible option in 23 infants younger than 3 months, 9 of whom required no further treatment. ^[11] Six required early closure of the VSD, and 8 required late repair. Seven more were older than 3 months, and none required repair of the VSD.

More recent reports attempt to outline predictors of spontaneous VSD closure. Considerations in decision for simultaneous VSD repair include the magnitude of the shunt through the VSD, the likelihood of persistent symptoms in the postoperative period, and whether the VSD is a type likely to spontaneously close. Initial coarctation repair is ideal when the VSD is likely to close, a band is not required, and arch hypoplasia is not present. Large size defects, defined as those with diameter greater than 50% of the aortic valve annulus, and types other than muscular such as perimembranous, inlet, outlet, and malaligned are less likely to close.

Proximal arch hypoplasia is best addressed through a midline sternotomy to alleviate the risk of recurrent obstruction, thus a combined repair strategy is favored in this situation. ^[25] Despite the controversy, many surgeons simply prefer to repair a clinically significant VSD when the coarctation is addressed to avoid the obvious disadvantages of the two-stage approach.

Dutta et al reported on the results of a study of 31 patients who underwent repair of coarctation of aorta with associated cardiac defects, through a midline sternotomy; coarctation and when necessary, the distal arch, was repaired prior to cardiopulmonary bypass. The overall event-free survival rate was 88.5% at both 2 and 3 years of post-surgical follow-up. The investigators concluded that repair of coarctation and distal arch hypoplasia or type I arch interruption is feasible prior to cardiopulmonary bypass without the use of hypothermic circulatory arrest or regional cerebral perfusion, with acceptable results. ^[26]

In a retrospective analysis, Kanter et al described in detail the advantages and disadvantages of the 1-stage and 2-stage approaches and introduce the 1-stage 2-incision approach. ^[27] All approaches have similar survival and rates of recoarctation, but the 1-stage 2-incision method results in shorter lengths of stay and corrects all defects at once without palliation and without the use of circulatory arrest or regional perfusion. The study advocates strategy selection on an individual basis.

End-to-end reanastomosis

One of the most common methods of repair is resection of the involved segment with end-to-end reanastomosis. This repair is usually reserved for infants and small children because of the absence of enlarged collaterals and the short distance for reanastomosis. In adolescents and adults, direct anastomosis is challenging because of large collaterals and the length of the aorta necessary for adequate repair.

Note the following:

• Place the patient in the right lateral decubitus position. The arterial line should be placed in the right radial artery, and a blood pressure cuff is placed on the right arm and lower extremity.

• Make a left posterolateral thoracotomy incision.

• Retract the lung anteriorly and inferiorly to allow for identification and incision of the pleura that overlies the descending aorta.

• Perform careful dissection from the proximal aorta at the level of the innominate artery takeoff, to the ductus, and then as far distal as safely possible. This step includes mobilizing the intercostals arteries. The present authors prefer not to sacrifice the intercostal vessels if at all possible.

• Avoid damage to the left recurrent laryngeal nerve, the vagus nerve, and the phrenic nerve, all which lie in the dissection field.

• After the plane of dissection is developed, the critical component of the procedure is resection of the entire coarcted segment and ductal tissue, followed by reconstruction of the aorta without clinically significant tension on the anastomosis.

• In general, heparin 100 units/kg is systemically administered.

• The aorta is cross-clamped at the proximal aspect just beyond the innominate artery takeoff and at the distal aspect about 1 interspace below the coarctation. The intercostal vessels may be controlled with a vessel loop or clip.

• The ductus is then ligated and divided if necessary. Ligating the ductus before aortic clamping creates a possibility of a ductal tear, which may be catastrophic.

• The involved aortic segment is then resected.

• Using a continuous absorbable monofilament suture (eg, Maxon, PDS), create the anastomosis. Release the distal aortic clamp before tying the suture to avoid "purse-stringing" of the anastomosis.

• At the termination of the procedure, identify any residual gradient by measuring the patient's blood pressure in the lower extremity by comparing that pressure to the pressure in the right arm.

• Transesophageal echocardiography can be useful to estimate the gradients during surgery.

• Benefits of this particular technique include avoidance of prosthetic materials, excision of ductal tissue, preservation of the left subclavian artery, total relief of left ventricular outflow obstruction, and growth potential of the aortic anastomosis.

Subclavian-flap aortoplasty

A second commonly employed method is the subclavian-flap aortoplasty, as follows:

• For this procedure, perform a left thoracotomy. The initial dissection follows that of the end-to-end anastomosis.

• Identify the left subclavian and ligate it at the first branch. Ligate the vertebral artery to avoid subclavian steal.

• Make a lengthwise incision along the coarctation, continuing on to the subclavian and creating a flap.

• Then, resect the posterior shelf and turn down and place the subclavian flap to enlarge the constricted area, ensuring an adequate length.

• Benefits of this technique include avoidance of prosthetic materials, decreased cross-clamp time, and the possibility that the anastomosis may grow as the child ages.

Prosthetic-patch onlay graft

First performed in 1957, this technique has fallen out of favor because of the need for prosthetic implants and the risk of aneurysms and pseudoaneurysms. ^[28] The differential elasticity of the often-rigid grafts (historically made of Dacron) in relation to the supple aorta is believed to increase the rate of aneurysmal formation. Literature from more recent experience with homograft patch material (used extensively in arch reconstruction for hypoplastic left-heart syndrome) has not shown an increased rate of aneurysmal formation.

Note the following:

• With the prosthetic patch onlay graft, perform a left thoracotomy and make a longitudinal incision along the coarcted segment.

• In this case, do not resect the posterior shelf.

• Sew a prosthetic patch into place, thereby enlarging the lumen.

Interposition grafts

Interposition grafts are most often used in older patients who have exceeded their growth potential. Interposition grafts are also useful when the narrowed segment cannot be completely excised without making primary reanastomosis impossible. In 1951, Gross used aortic homografts as interposition grafts and reported no clinically significant complications in 70 patients other than graft calcification, which was present in less than 50%. Aneurysmal dilatation has not been reported. The technique of interposition graft is selectively used in individuals with complex coarctation, recurrence, or aneurysmal formation.

Always measure the arm and/or leg gradient after surgery to differentiate inadequate repair from true recoarctation. In the optimal case, perform exercise testing for best accuracy because some patients do not have a gradient except during and after exercise. Although exercise testing is not a feasible option in infants and neonates, it is an excellent test for follow-up observation of adolescent patients.

Follow-up care of the patient with coarctation can range from an office visit with physical examination and the measurement of arm and/or leg gradients to repeat aortography to directly measure any residual gradients and to identify any anatomic problems.

With the advent of advanced echocardiography, physicians are increasingly willing to rely on the noninvasive results obtained with this technique. Echocardiography can enable a good approximation of the anatomy, and it provides a good estimation of gradients.

Causes implicated in recoarctation include inadequate resection of ductal tissue, failure of anastomotic growth, and suture-line thrombosis.

Given the technical complexity of coarctation repair, the list of complications is remarkably short. Many of the complications are not specific to coarctation but are common with other cardiac procedures; these include hemorrhage, infection, chylothorax (from injuries to the thoracic duct), suture line thrombosis, and suboptimal repair or recurrence.

Numerous complications are unique to both aortic surgery and coarctation. A 2-phased phenomenon of paradoxic hypertension can occur after coarctation repair. During the first phase, systolic blood pressure rises throughout the first 24-36 hours after the operation. This rise is believed to result from activation of the sympathetic nervous system with elevation of serum catecholamine levels. A rise in diastolic blood pressure occurs later and is a result of activation of the renin-angiotensin system.

Another complication unique to coarctation repair is the postcoarctectomy syndrome of abdominal pain and distension that Sealy first described in 1957. As many as 20% of patients have this complication, and laparotomy may be necessary. In 1985, Kawauchi et al noted that mesenteric ischemia secondary to acute necrotizing arteritis appeared to be the cause. ^[29] Relatively recent data suggest that aggressive control of postoperative hypertension usually prevents the full-blown syndrome. In addition, this phenomenon appears to be associated with coarctation in older patients, as this complication is rarely seen with infants and small children.

The most worrisome complication after coarctation repair continues to be paraplegia, which occurring in 0.1-1% of neonates after coarctation repair. No definitive predisposing factors are known. Current data suggest that poor collaterals, anomalies of the origin of the right subclavian artery, distal hypertension during cross-clamp, reoperation, or relative hyperthermia during the operation may all contribute to the incidence of paraplegia. The incidence in the adult population undergoing coarctation repair rises proportionately with age and is as high as 2.6%.

The tremendous variation in spinal-cord blood supply, including the elusive artery of Adamkiewicz, makes predicting adequate collateral flow extraordinarily difficult. Some theories suggest that maintaining a distal aortic pressure of more than 60 mm Hg may help to prevent cord ischemia (as measured by means of maintenance of somatosensory evoked potentials), and some have suggested using a shunt to achieve this if necessary. In 1987, Cunningham demonstrated that distal hypertension with loss of somatosensory evoked potentials for more than 30 minutes resulted in a more than 70% incidence of paraplegia. ^[30]

Other complications include temporary or permanent hoarseness from recurrent injury to the laryngeal nerve. The nerve can be directly injured by transection or indirectly by retraction. Careful identification of the anatomy and knowledge of the course of the recurrent laryngeal nerve is critical to avoid this complication.

Outcomes from coarctation repair depend on several factors, most notably the patient's age at the time of operation, the method of repair, and the presence of associated anomalies.

The recoarctation rate with the end-to-end repair has historically approached 60%, with somewhat lower rates for subclavian-flap aortoplasty and prosthetic graft repair. However, recent studies have demonstrated that end-to-end repair favorably compares with other techniques, with recoarctation rates of only 5-10%. ^[9]

Some suggested reasons for this dramatic change are improved neonatal intensive care units and advances in vascular surgical technique and suture materials. Improved preoperative conditioning and increased use of prostaglandins have also contributed to lowered mortality rates. Circumferential suture lines were initially blamed for high rates of recoarctation; however, because this technique was perfected with the arterial switch operation, they should likely prove effective for coarctation as well. At this time, the current authors know of no prospective randomized trials that are being conducted to compare the repair techniques.

Overall mortality rates are still 2-10% in neonates, which includes those with intracardiac anomalies as well as those with coarctation.

A 1998 retrospective study of 176 patients by Seirafi and associates demonstrated an overall mortality rate of 7.4%. ^[31] Nine of 13 deaths were in patients with associated complex intracardiac anomalies. No mortality occurred in the 113 patients with isolated coarctation. A 15% incidence of residual or recurrent coarctation was reported, although neither the patient's age at operation nor the type of repair appeared to influence recurrence. The other major complication was persistent hypertension, which was associated with repair in patients older than 1 year (27% vs 4.2%).

In the same year, Backer and associates reported a series of 55 infants who underwent repair by using extended resection with end-to-end reanastomosis. ^[32] They reported a 5.4% mortality rate and a 3.6% rate of recurrence. The median age at surgery was 21 days. A total of 62% of surgeries performed through a left thoracotomy and the others through a median sternotomy with concurrent repair of associated anomalies. About 47% of patients had isolated coarctation, and 53% had at least 1 associated intracardiac anomaly, with ventricular septal defect (VSD) comprising 69% of those anomalies. Total resection of all ductal tissue was achieved.

In 2000, Allen and associates described a modified subclavian patch aortoplasty. ^[33] They demonstrated excellent results in 53 infants with no mortality and only a 4% incidence of clinically significant recoarctation. Of these instances, 49% were associated with cardiac anomalies. As with all techniques, the key features to this technique are a tension-free repair and a long aortotomy to help prevent restenosis.

A report from the Society of Thoracic Surgeons Congenital Heart Surgery Database looked at early outcomes in a large 95 center cohort of 5025 patients undergoing repair of coarctation of the aorta or hypoplastic aortic arch repair between 2006 and 2010. ^[34] Patients were divided into three groups with Group 1 consisting of coarctation or hypoplastic aortic arch without ventricular septal defect (VSD); Group 2, coarctation or hypoplastic aortic arch with ventricular septal defect; and Group 3, coarctation or hypoplastic aortic arch with other major cardiac diagnoses. Overall mortality was 2.4%; it was 1% for Group 1, 2.5% for Group 2, and 4.8% for group 3.  In 211 patients undergoing VSD closure, mortality was 4%; it was 1% for those undergoing pulmonary artery banding as a management strategy for the VSD; and it was 2% for those not underdoing intervention for the VSD mortality.  There were postoperative complications in 36% of patients. No injury to the spinal cord was noted. The investigators were unable to measure the recurrence rate or how it related to surgical technique. ^[34]

Despite some excellent outcomes, controversy remains over the use of flap aortoplasty in infants younger than 3 months. Potential pitfalls are associated with early use of this technique, most notably concern over the loss of the major vascular supply to the left upper extremity. Complications are rare (the left subclavian was historically divided for pulmonary systemic shunts, with complications occurring rarely); however, decreased growth and rare reports of ischemia and gangrene have been documented. ^[35] In addition, neonates most often have associated arch hypoplasia, which is better addressed with resection and end-to-end anastomosis than with other methods. Complete hypoplasia of the aortic arch is best addressed by means of arch reconstruction performed through a median sternotomy.

The prosthetic-path onlay technique has the advantages of a relatively short operating time, minimal dissection, maximal augmentation of the stenosed area, and maintenance of normal vascular anatomy. However, this technique has been associated with an aneurysmal-development rate of as much as 35%, and repeat operation is required in almost 20% of patients. ^[28]

Balloon angioplasty has been performed for more than 20 years; however, its use in coarctation remains controversial because of the formation of pseudoaneurysms and concerns about long-term patency. The surgical literature shows a high restenosis rate for neonatal (< 40 d) balloon angioplasty; 57% need surgical intervention. However, in the population with surgically treated restenosis (18%), secondary angioplasty is the treatment of choice, and no repeat interventions were necessary. ^[36]

A long-term randomized study of angioplasty versus surgery in children (3-10 y) showed that only 50% of patients treated with balloon angioplasty remained free of both aneurysmal formation and repeat intervention compared with 87.5% of surgically treated subjects. ^[37]

At present, the optimal timing and mode of treatment for patients with coarctation remains controversial. In neonates and young children, surgical intervention remains the criterion standard. It is well-tolerated, with excellent long-term efficacy due to an 88-96% 5 years freedom from reintervention. Balloon angioplasty carries a higher risk of complication and suboptimal outcome in as many as 19% of native coarctation cases. Stents overcome some of the problems inherent to simple dilation but are not without serious complications related to materials and biomechanics.

No evidence suggests superiority of an endovascular therapy over surgery for treatment of primary coarctation. ^[38] However, for patients with hemodynamic instability or for those who have undergone surgery for restenosis, angioplasty can be a palliative and potentially curative procedure. Al-Ata et al studied a series of infants with complex aortic coarctations and relative contraindications to surgery who underwent palliative stent implantation as a nondefinitive procedure. ^[39] Three of the four improved and eventually underwent definitive repair.

Stent placement in infants has also been studied, although (to the authors' knowledge) no long-term results have been reported. A report published in 2000 by Thanopoulos et al suggests that stent implantation can be performed with low morbidity and mortality rates and that no recoarctation was noted in any of the 17 patients who were examined at the age of 33 months. ^[7] Peak systolic gradients were reduced to just 2.1 mm Hg from 50 mm Hg. A report of retrospective study by Marshall et al in 2000 suggested that, although stent implantation was a feasible option for challenging cases, it was not without a risk of serious complications. ^[40]

Stent placement is still under investigation in adolescents and adults, and long-term data is still being released. A nonrandomized selection-biased case series describes initial and 5-year outcomes for stent placement to treat adult aortic coarctation. Complications included a single incidence of stent migration requiring percutaneous intervention and a femoral pseudoaneurysm requiring surgical correction. Complete relief of coarctation was achieved with no recoarctation. ^[41] A retrospective review of endovascular stent placement to treat thoracic aortic aneurysm following repair of aortic coarctation in a select few patients revealed promising, yet nondefinitive results. ^[42]

Fiszer et al implanted a new type of extra-large stent, the AndraStent XL/XXL, in 38 patients with native coarctation of the aorta (CoA) and 8 patients with recurrent coarctation of the aorta following prior surgery (ReCoA). The outcome was successful for all procedures, and the systolic gradient across the aorta decreased from 40.6 mmHg pre-procedure to 11.6 mmHg post-procedure (p< 0.001). The procedural outcome remained favorable during a mean of 2.4 years of follow-up, and at follow-up neither stent fracture nor dislocation was found in any patients. ^[43]

The future of aortic coarctation repair may include direct genetic intervention or in utero therapy, which may decrease the growth of ductal tissue into the main aorta or which may help alter neonatal blood flow in such a way to prevent coarctation completely. Until that time, surgical techniques will continue to improve, and the use of angioplasty should continue as studies continue to find the subset of patients in whom it will prove most useful.