Discussion
The surgical management of aortic arch hypoplasia with associated intracardiac anomalies is a challenge in neonates and infants. According to intracardiac anomalies, palliation or total repair in addition to arch repair is controversial. Moreover, significant proximal transverse aortic arch obstruction is rare than the distal arch and isthmus hypoplasia, but almost always requires a surgical approach via a sternotomy 1. In our cohort, all patients had tubular arch hypoplasia, so we performed all arch reconstructions via sternotomy and enlarged the aortic patches to the midportion of the ascending aorta. We attempted to perform total intracardiac repair in all biventricle patients, but in single ventricle patients and biventricle patients with preoperative comorbidities we performed pulmonary artery banding. From this point of view, BSA values during surgery were significantly lower in the palliation group and the number of patients weighing <2.5 kg was higher.
Several techniques and patch types have been proposed through the years for repair of aortic arch obstructions, and recurrent obstruction in the correspondence of the aortic arch surgery, is the most frequently reported complication, with a hugely variable incidence reported from 2 to 38% 5-7. Roussin and colleagues presented that aortic arch repair associated with pulmonary autograft patch augmentation resulted in superior midterm outcomes, thus reducing the risk of recorctation and tracheobronchial compression in comparison to patch aortoplasty with homograft and pericardial patch augmentation8.Morales and colleagues presented excellent results with 100% freedom from arch reintervention during a 5-year follow-up in neonates with interrupted aortic arch using aortic arch advancement technique 9. On the other hand, Gaynor and colleagues published no difference regarding the incidence of reintervention by patch reconstruction of the arch (20%) or resection with end-to-end anastomosis (25%)10. In our technique, distal descending aorta was anastomosed to the aortic arch to form a native posterior wall, and patch augmentation was extended to the midportion of the ascending aorta. In our opinion, it is safer not to use too long and wide patches, and to extend the patch like us. We preferred glutaraldehyde treated autologous pericardium in 21 patients, bovine pericardium in 19 patients, porcine pericardium in 20 patients as a patch. Rigit patches in particular such as grafts can cause stenosis by pushing the proximal and distal aorta.
All of our patients had tubular arch hypoplasia in this study, which was calculated to be a risk factor for recoarctation by Dodge-Khatami and colleagues in a 40-year review of patients undergoing coarctation repair11. Similarly, Bernabei and colleagues presented a higher incidence of restenosis rate with neonatal arch hypoplasia as compared with arch interruption or the hypoplastic left heart syndrome7. Interestingly, all patients in that study underwent arch reconstruction with autologous pericardium. One- and three-year freedom from recoarctation was 93 and 69%, respectively, and the authors concluded that the use of autologous pericardium in aortic arch reconstruction procedures is valid and associated with an acceptable incidence of recurrent arch obstruction 7. In our study, 10 (20.8%) patients required reintervention due to distal recoarctation, seven of them treated with successful aortic balloon angioplasty, but 3 required surgical reintervention. We performed resurgery via left thoracotomy in 3 patients using bovine or porcine pericardium. We observed only one (2%) proximal restenosis, probably due to the particular shape of the aortic arch, and we performed reoperation via median sternotomy. We believe that our low proximal restenosis rate depends on our technique that extends the patch to the middle of the ascending aorta. Furthermore, with the use of patch enlargement, we did not observe bronchi or trachea compression described as a possible complication of end-to-end anastomosis12.
The arch hypoplasia, interruption, or coarctation is efficiently dealt with at the time of the ASO while working through a median sternotomy. It is generally possible to perform a direct
anastomosis for interruption or coarctation with mild tension on the anastomosis. On the other hand, the aortic arch hypoplasia requires an additional longitudinal patch-plasty. This has the advantage of enlarging the size of the ascending aorta, thus facilitating a tension-free neoaortic anastomosis; it achieves an aortic arch of adequate size. Huber et al. conducted a study on 22 patients who underwent ASO and arch repair with 18,1 % overall mortality, and 3 patients required ECMO. Sixteen of 22 patients had arch hypoplasia, and remaining patients had coarctation or IAA, and Huber et al. reported a 44% rate of arch reintervention 13. Vouhe´’s group described a 76% actuarial survival rate in 38 patients who underwent ASO with arch repair, mentioning arch reinterventions in three patients (7.8%)14. By contrast, Planche´’s group conducted a study on 67 patients who underwent one-stage repair with either end-to-end (35 patients) or patch enlargement of (32 patients) for AAO relive. Overall, actuarial survival in this series was 94% in the 32 patients and 75% in the 35 patients over 10 years, and re-interventions required in 15 patients (22%) for recoarctation 15. In our cohort, 11 patients underwent ASO and arch repair with 18.8% overall mortality; one of them required ECMO, two patients died due to sepsis on the postoperative course, and only one patient (11%) required reintervention for recoarctation during the follow-up. Our mortality and reintervention rates were similar to the literature for this complicated group. We considered that the one-stage-repair of transposition complex and aortic arch hypoplasia showed good survival results for these highly complex congenital anomalies in high-volume hospitals.
More complex pathologies or functional single ventricle with arch hypoplasia showed high morbidity or mortality rates16. Historic outcomes of PAB + COA repair have been unfavorable and associated with high hospital death, reduced progression toward subsequent palliative stages, and overall low survival17,18. Franklin and colleagues found that
survival after PAB + COA repair was 44% at 1 year and 22% at 5 years, and in another study, they found that Fontan candidacy was only 8%17,18. In our study, in Group 1 (PAB +arch repair), mortality rate was 34.8% (8/27), and 62,5% (5/8) of them had functional single ventricle. On the other hand, Poirier et al. conducted a study on 37 children who had arch hypoplasia and biventricular hearts, and they reported no postoperative deaths with isolated aortic arch hypoplasia patients. However, the operative mortality for their total cohort of patients was 13.5% 19. Karl and associates have reported similar results of the combined arch and intra-cardiac repair with a 13% operative mortality rate in a group of 15 infants who underwent a single-stage repair 20. These mortality rates were similar to our single-stage repair group, with a mortality rate of 10.8%. In our study, only 6 cases with biventricular heart underwent isolated arch reconstruction with no operative mortality. Although the duration of cardiopulmonary bypass time and cross clamp time were significantly higher in the single-stage repair group, postoperative mortality, delayed sternal closure time, VAC treatment usage rate, sudden cardiac arrest rate, and postoperative low cardiac output rates were significantly higher in the palliation group. In our perspective, these results shows the importance of single stage total repair, and the adverse effect of the pallation to the outcomes.
In neonates and some infants, low cardiac output can persist after coarctation repair due to
preoperative LV dysfunction 21. Lim et al. conducted a study on 69 neonates or infants who underwent single-stage total repair of the aortic arch anomaly using regional perfusion. They reported only four patients (5.7%) had postoperative low cardiac output syndrome, and all of them had poor preoperative conditions 21. In our study, 8 patients (13.3%) had postoperative low cardiac output syndrome, and this was significantly higher in our palliation group (p=0.022). Among 8 patients, 7 require mechanical ventilatory support, and 3 of them had poor ventricular function requiring inotropic in the preoperative period. Only one patient did not need any support preoperatively, but he was also premature.
We only used a direct cannulation method through the innominate artery, even in the small neonates, instead of using a polytetrafluoroethylene graft. We considered it a basic and applicable method which did not conceal the surgical area. Moreover, there was no cannulation-related complication, such as stenosis or intimal injury in our cohort. Usually, the size of the innominate artery was adequate for cannulation, and we easily advanced the 8Fr arterial cannula. We used ACP perfusion during the repair of aortic arch hypoplasia with a flow rate of 40-50 ml/kg/min in order to maintain a perfusion pressure of 50-60 mmHg, and all patients were monitored by near-infrared spectroscopy (NIRS). In our series, early postoperative minor neurologic complications as seizures occurred in three patients (5%), which is better than the reported rates (4-25%) in total circulatory arrest groups 22. Any abnormality was not detected in these patients on CT and electroencephalogram, and fortunately, all patients recovered entirely by anti-epileptic therapy, but the long-term complications such as neuro-developmental abnormalities need to be evaluated further.
Some reports suggested that the higher hematocrit level would be beneficial on neurologic outcomes after the TCA or low flow bypass23. But there was some controversy on the optimal hematocrit level, and there has been no gold standard. In our cohort, we maintained a hematocrit level at around 30 %, and we believe that this is one of the reasons for not seeing a major neurological complication.
Pigula et al. reported that the somatic perfusion through various collaterals was maintained during low flow regional perfusion with a flow rate of 30– 40 ml/kg per min and suggested that the support of the subdiaphragmatic viscera should improve the ability of neonates to survive the postoperative period 24. Lim et al. conducted a study on 48 neonates who underwent aortic arch reconstruction operation using regional perfusion without circulatory arrest. Their mean radial artery perfusion pressure was about 40-50 mmHg, the mean duration of regional perfusion time was 33±16 min, and renal insufficiency occurred in only 4.2% (2/48) of patients in the postoperative course 16. In our cohort, the mean radial artery perfusion pressure was about 50-60 mmHg, the mean duration of antegrade cerebral perfusion time was 22.4 ±7.4 min, and renal insufficiency occurred in only 5% (3/60) of patients in the early postoperative period. On the other hand, Kreuzer et al. and Hammel et al. reported that 1,7% and 5% of postoperative acute renal failure rate, respectively, with double arterial cannulation, and they reported lower adverse events were observed by additional descending aorta cannulation 25,26. We believe that the direct comparison of the results for renal complications was inappropriate because of the various preoperative conditions, but we considered that such a high flow rate would be beneficial in the functional recovery of somatic organs besides cerebral protection.
The retrospective and single-center study design aspects are the main limitation of this study. Studies with multiple centers, including various types of congenital heart disease and long-term outcomes, are needed to demonstrate the surgical results of aortic arch hypoplasia.
In conclusion, aortic arch reconstruction for tubular arch hypoplasia in neonates and infants with or without associated intracardiac lesions can be repaired by single-stage repair with acceptable early and mid-term results. On the other hand, palliation with arch repair should be considered in biventricular neonates with significant preoperative comorbid conditions, and in single ventricle neonates.