Split-Graft Technique in Neonatal Heart Transplant for Aortic Atresia

Technique

A 3.2 kg male neonate was delivered with the diagnosis of aortic atresia, ventricular septal defect, balanced ventricles, hypoplastic ascending aorta (1.5 mm), and severe hypoplastic aortic arch. On day two he underwent bilateral pulmonary banding. Twelve hours later he collapsed and was resuscitated with ECMO (neck vessels cannulation). The ductus was stented prior to ECMO retrieval and he was decannulated after six days of circulatory support. Since the contractility was grossly affected, a Norwood technique was ruled out and the patient was listed for heart transplant on priority 1 (weight 3.2 kg, height 49 cm, body surface 0.2 m2). He remained on intravenous inotropic support and after 30 days, a heart from a 12 kg donor became available.

The patient was cannulated through the pulmonary artery for the arterial return (the first supra-aortic vessel was discarded because of the previous neck ECMO approach) and both vena cava for venous return, and cooled down to 18 degrees Celsius. When the harvest team arrived, the graft was checked and a segment of the ascending aorta including the entire arch was removed. The heart was kept in a cold solution to maintain the cold ischemia period.

In the surgical field there was a brief period of circulatory arrest. The arterial cannula was removed and the ascending aorta, ductus, and descending aorta were transected. The isolated arch was split open and the arterial cannula was advanced through the left carotid artery and fastened with a tourniquet before re-starting circulation. Ductal tissue surrounding the origin of the left subclavian artery was completely removed, keeping an aberrant right subclavian vessel rising from the descending aorta.

An end-to-end anastomosis between the donor graft-arch and the recipient descending aorta was carried out. An oval mouth was fashioned in the graft-arch. The second and third vessels were trimmed in order to match the opened arch in the recipient for the next anastomosis (graft-arch to recipient-arch).

Finally, the arterial cannula was again removed from inside the “new” arch and secured to the first aortic-graft vessel, which happened to be a side-arm for cannulation. A cross-clamp was applied to the base of the new ascending aorta and circulation resumed. The heart was removed and the transplant followed in a routine fashion, with sequential anastomoses of the left atrium, inferior vena cava, and ascending aorta. Pulmonary artery and superior vena cava anastomoses were completed after releasing the aortic clamp. Total cardiopulmonary bypass time was 372 minutes and total ischemia time 157 minutes.

Due to the mismatch between donor and recipient weight, the chest was left open and finally closed after five days. The patient was extubated on the 25th postoperative day and discharged two months following heart transplant. At the 1-year follow-up, the patient was progressing well on standard inmunosuppressive therapy with no signs of rejection.

Commentary

Transplants in univentricular patients pose a unique challenge with regard to reconstructing vascular structures, either after Norwood, Glenn, or Fontan procedures (1, 2). Several strategies have been described to overcome these hurdles which, undoubtedly, add technical difficulty and ischemia time to the procedure.

This patient presented with a severe hypoplastic aorta, ductal stenting, left subclavian artery arising from the coarctation site, and aberrant right subclavian artery as a fourth supra-aortic vessel coming off the descending aorta. The brachiocephalic artery had been previously handled (neck ECMO) and a Norwood procedure was ruled out due to poor ejection fraction.

A standard anastomosis between the donor aorta and the recipient in a Norwood-like fashion would have been a time-consuming, circulatory-arrest procedure, sacrificing both subclavian arteries. Instead, a graft-arch to recipient-arch without circulatory arrest strategy respected the anatomy, albeit two anastomoses were necessary. Attention was paid to the ischemia time, leaving the graft in cold bag while addressing the arch, in order to keep the ischemia cold rather than hot (3, 4). Again, the standard approach (left atrial first, aorta second, and anastomosis third) would have rendered the whole period of ischemia on the hot rather than on the cold side.

The Melbourne group has reported three patients with arch reconstruction simultaneous to heart transplant after failed Fontan (5). They replaced the whole arch by synthetic material in two patients and with donor tissue in the third one. Their two-fold message was addressing the anatomical reconstruction prior to transplantation, and keeping the ischemic time as accurate as possible. This case fits nicely in this philosophy because the authors could manage the arch before the transplant and kept the cold ischemia time short. In addition, the growth potential is guaranteed because of the same donor graft, and arch distortions are less likely to develop in an end-to-end anastomosis rather than a long-spatulated Norwood-like suture.

The authors believe that the split-graft technique for addressing the hypoplastic and stented arch is simple and reproducible in neonates and infants, saves cold ischemia time, and can yield good results in the short-medium term.

References

1. Kanter KR, Mahle WT, Vincent RN, Berg AM, Kogon BE, Kirshbom PM. Heart transplantation in children with a Fontan procedure. Ann Thorac Surg 2011;91:823-9
2. Murtuza B, Dedieu N, Vázquez A, Fenton M, Burch M, Hsia T-Y et al. Results of orthotopic heart transplantation for failed palliation of hypoplastic left heart. Eur J Cardiothorac Surg 2013;43(3):597-603
3. Banner NR, Thomas HL, Curnow E, Hussey JC, Rogers CA, Bonser RS. The importance of cold and warm cardiac ischemia for survival after heart transplantation. Transplantation 2008;86(4):542-7
4. Marco SF, Kras A, Schulberg E, Vale M, Lee G. Impact of warm ischemia time on survival after heart transplantation. Transplant Proc 2012;44(5):1385-9
5. Iyengar AJ, Sharma VJ, Weintraub RG, Shipp A, Brizard CP, d´Udekem Y et al. Surgical strategies to facilitate heart transplantation in children after failed univentricular palliations: the role of advanced intraoperative surgical preparation. Eur J Cardiothorac Surg 2014;46(3):480-5