Discussion

Interrupted aortic arch is a life-threatening congenital cardiovascular malformation with an incidence of 3 per million live births^{Reference Garcia, Rey, Lopez, Lamelas and Orozco-Sevilla2} and rarely occurs as an isolated lesion.^{Reference Firouzi, Mohebbi and Shafiei5,Reference Chen, Li and Pu8} Ventricular septal defect is the most common concomitant anomaly in these patients that is seen in 73% of the cases. The patent ductus arteriosus has to continue as descending aorta otherwise lower body perfusion is compromised.^{Reference Javadzadegan, Porhomayon, Sadighi, Yavarikia and Nader3,Reference Varghese, Saheed, Omoregbee, Ninan, Pavithran and Kothandam9} Bicuspid aortic valve and right subclavian artery abnormalities may also be seen in these patients.^{Reference Burbano-Vera, Zaleski, Latham and Nasr1} Other associated rare cardiovascular anomalies include truncus arteriosus, single-ventricle pathologies, atrioventricular canal defects and transposition of great arteries.^{Reference Jonas10} Various single-ventricle pathologies may be seen in 11% of patient with interrupted aortic arch.^{Reference LaPar and Baird11} An atrial septal defect or usually a patent foramen ovale is almost always present in all cases.^{Reference Jonas10} The subaortic stenosis based on subaortic fibrous membrane is not common in these patients; however, a subaortic membrane may occur in patients who receive neonatal interrupted aortic arch repair in 1 to 2 years.^{Reference LaPar and Baird11} Especially in the Type B interrupted aortic arch, genetic testing is suggested due to high association with DiGeorge Syndrome.^{Reference Javadzadegan, Porhomayon, Sadighi, Yavarikia and Nader3}

The affected patients rarely reach adulthood without surgical treatment. In these patients, the main factor of the survival is the extensive collateral vessels that provide distal blood flow.^{Reference Chen, Li and Pu8} In the neonatal period, the pathology is associated with severe congestive heart failure or lower body hypoperfusion, severe metabolic acidosis and multi-organ failure with the ductal closure.^{Reference Burbano-Vera, Zaleski, Latham and Nasr1,Reference Javadzadegan, Porhomayon, Sadighi, Yavarikia and Nader3} The mortality in the first days of life is generally due to the closure of the patent ductus arteriosus; and without treatment, 90% of the patients die at a median age of 4 days.^{Reference Javadzadegan, Porhomayon, Sadighi, Yavarikia and Nader3,Reference Firouzi, Mohebbi and Shafiei5}

The physical examination may reveal differential cyanosis and the gradient between lower and upper peripheral pulses in neonates^{Reference Javadzadegan, Porhomayon, Sadighi, Yavarikia and Nader3,Reference Singh and Singh4} which are clues for either aortic interruption or coarctation which may be confirmed with transthoracic echocardiography, initially.^{Reference Chen, Li and Pu8} CT angiography and MRI may also be used in challenging cases to confirm the exact pathology regarding the aortic arch and differential diagnosis between aortic coarctation, interrupted aortic arch and the exact type location of the stenosis/interruption at the aortic arch.^{Reference Chen, Li and Pu8}

Although in the preoperative period, prostaglandin E1 infusion is vital for the survival to provide ductal patency,^{Reference Burbano-Vera, Zaleski, Latham and Nasr1} early surgical therapy is the main treatment option for the babies with interrupted aortic arch.^{Reference Javadzadegan, Porhomayon, Sadighi, Yavarikia and Nader3,Reference Chen, Li and Pu8} Endovascular treatment may be considered when two parts of the aorta are very close or only separated with a membrane,^{Reference Firouzi, Mohebbi and Shafiei5,Reference Celebi, Sarıtaş, Demir, Akdeniz and Erdem12} treatment methods include end-to-end or end-to-side direct anastomosis, graft interposition^{Reference Chen, Li and Pu8} and extra-anatomic bypass using a graft.^{Reference Garcia, Rey, Lopez, Lamelas and Orozco-Sevilla2} End-to-end direct anastomosis or extended aortic arch anastomosis are the most common and relatively the most anatomical surgical techniques; however, direct anastomosis may cause stenosis and/or bronchial compression. The technique also requires extensive mobilisation of the descending aorta.^{Reference Nishioka, Fuchigami and Akashige13,Reference Cr, Aggarwal, Joshi and Joshi14} Thus, an anterior patch may be utilised at the anastomosis site to provide reduced anastomotic tension which may also decrease the risk of stenosis and tracheobronchial compression after the operation and in the long run.^{Reference Dodge-Khatami6} Pericardial materials or arterial allografts may also be used in reconstruction of the aorta.^{Reference LaPar and Baird11} Bechtold et al.^{Reference Bechtold, Purbojo and Schwitulla15} used various patch materials including autologous pericardium treated with 0.6% glutaraldehyde for 20 minutes, bovine pericardium and homograft patches. In their series, re-coarctation occurs in certain cases especially who received autologous pericardium during initial arch repair.^{Reference Bechtold, Purbojo and Schwitulla15} Bernabei et al.^{Reference Bernabei, Margaryan, Arcieri, Bianchi, Pak and Murzi16} used gluteraldehyde-treated autologous pericardium in their cases for aortic arch repair, and they faced with re-stenosis in some of their cases. Their attempt was to balloon dilate the stenosed arches primarily; however, unsuccessful cases were surgically treated. They detected an overgrowth of neo-intima to be responsible for the progressive lumen narrowing.^{Reference Bernabei, Margaryan, Arcieri, Bianchi, Pak and Murzi16} In our series, fresh or short-duration gluteraldehyde-treated autologous pericardial materials were used for the treatment of aortic interruption. We faced with pericardial roll dilatation in patients who received fresh tissues both of which presumed to result due to decreased strength of the material at the aortic position as well as additional proximal anastomosis stenosis in one (submitted elsewhere) who was further operated.^{Reference Ugurlucan, Yildiz and Ulukan7} The remaining living patients are followed uneventful in good conditions devoid of significant stenosis of the used materials.

Literature includes reports in which the main pulmonary artery was used for the reconstruction of the aortic arch as an autograft tube regarding growth potential of the graft.^{Reference Lee, Lee and Lee17} Additional procedures for the concomitant cardiac pathologies or for remote operations such as pulmonary bands should also be added to the aortic interruption repair. A modification of Norwood arch reconstruction in aortic arch repair was introduced by Urencio and associates for a tension-free repair in patients with interrupted aortic arch. The technique is called ascending aorta slide technique and uses the ascending aortic flap as a posterior bridge of the connection between proximal and distal parts of the interruption.^{Reference Urencio, Dodge-Khatami, Greenleaf, Aru and Salazar18} The small ascending aorta and bleeding risk as a result of long suture line are some of the disadvantages of the technique.^{Reference Takeuchi19}

All of these techniques require cardiopulmonary bypass. Following cardiopulmonary bypass, myocardial oedema and reduced cardiac output may occur in the post-operative period. Care of the critically ill patients during or after cardiopulmonary bypass may be highly complicated due to the side effects of the extracorporeal circulation.^{Reference Burbano-Vera, Zaleski, Latham and Nasr1} Additionally, the extensive mobilisation of the aortic arch may cause recurrent laryngeal and phrenic nerve injuries.^{Reference Burbano-Vera, Zaleski, Latham and Nasr1} The residual aortic arch obstruction is not an uncommon pathology and ends up with requirement of the re-intervention in approximately 20% to 40% of the patients who receive aortic interruption repair.^{Reference Burbano-Vera, Zaleski, Latham and Nasr1} Angioplasty may be considered in case of re-stenosis^{Reference Dodge-Khatami6,Reference Bechtold, Purbojo and Schwitulla15,Reference Bernabei, Margaryan, Arcieri, Bianchi, Pak and Murzi16} ; however, the results in the literature reveal that the technique did not reduce the need for surgical reoperation.^{Reference Burbano-Vera, Zaleski, Latham and Nasr1}

Respiratory complications are the other major complications most probably occur secondary to the external compression of the airways especially the left main bronchus most probably due to inadequate mobilisation of the descending aorta and aortic stretch afterwards.^{Reference Dodge-Khatami6,Reference Maddali, Kandachar, Mohsen, Arora and Lacour-Gayet20} A prosthetic interposition graft may also be utilised for the treatment but due to the inability of growth potential of the graft material re-intervention becomes mandatory in the growing patients. To overcome the re-interventions for the graft incompatibility, the native tissues are frequently preferred, such as subclavian rotational flap, but this technique sacrifices a major artery to the upper extremity.^{Reference Dodge-Khatami6}

Our technique with an autologous pericardial roll bypass eliminates the need for cardiopulmonary bypass; hence, the patients are protected against the negative effects of cardiopulmonary bypass and do not suffer from many post-operative complications during the myocardial recovery process; being vitally important especially in critically ill infants. The duration of the operation may be relatively shorter as it includes only two anastomosis and devoid of cardiopulmonary bypass. The pulmonary dysfunction both secondary to cardiopulmonary bypass and bronchial compression due to descending aortic proximal anastomosis may be prevented providing a less complicated pulmonary course and easier and faster extubation. During the growth period, depending on the use of a native tissue, re-intervention may not be required. However, use of fresh materials revealed graft dilatation in our two cases and gluteraldehyde-fixed materials have been relatively protected with certain degree of graft growth.