Case report
A baby, prenatally diagnosed with hypoplastic left heart syndrome, was delivered through an emergency cesarean section due to fetal deceleration at 39 weeks and 4 days of gestational age, weighing 3.16 kg. Following birth, she exhibited bradycardia and desaturation; she was transferred to the neonatal ICU after intubation. Because meconium staining and aspiration were observed in the delivery room, empirical ampicillin and amikacin were initiated on the first day of life. On the third day of life, the infant developed a fever, wherein laboratory results indicated an elevated C-reactive protein level of 5 mg/dL. Therefore, the antibiotic regimen was escalated to vancomycin and meropenem. The postnatal diagnosis confirmed hypoplastic left heart syndrome, comprising mitral stenosis, aortic atresia, and a hypoplastic ascending aorta (2 mm), along with a muscular inlet-type ventricular septal defect and a large patent ductus arteriosus. Prostaglandin E1 infusion was initiated on the first day of life. Consequently, she underwent bilateral external pulmonary artery banding due to worsening cardiomegaly and pulmonary oedema at 6 days after birth.
After pulmonary artery banding, the infusion of prostaglandin E1 was continued. However, the size of the patent ductus arteriosus decreased abruptly at 24 days of life. Initially, the plan was to proceed with the Norwood procedure, which could create a neo-aorta and establish a reliable source of pulmonary artery flow with Blalock–Taussig shunt, for the next-stage operation of single-ventricle palliation. However, a severe surgical wound complication occurred after the pulmonary artery banding, resulting in exposure of the sternal bone. Additionally, the patient presented with left corneal opacity, ear malformation, a flat face with hypertelorism, a high-arched palate, and fifth finger shortening. A likely pathogenic heterozygote variant, c.15686del, p.Arg5229Profs*14, was identified in the KMT2D gene, leading to a diagnosis of Kabuki syndrome. This syndrome posed a high-risk factor for the Norwood procedure, Reference Alsoufi, Mori and Gillespie1 and it was anticipated that the patient’s general condition might not be conductive to undergo the Norwood procedure successfully. Therefore, the patient underwent a hybrid procedure consisting of ductal stenting using 8 mm-diameter and 17 mm-length balloon expandable stent (Visi-proTM, Medtronic Inc., Minneapolis, MN, USA) and reverse Blalock–Taussig shunt using a 4 mm vascular graft at the age of 28 days to maintain coronary and cerebral perfusion (Figures 1a and 2a). Reference Calderone, Benson, Holtby and Van Arsdell2 Twenty days after the hybrid procedure, sternal wound closure was performed in collaboration with a plastic surgeon using bilateral pectoralis major advancement flaps.
Figure 1. Operative procedures. ( a ) At 26 days of age, a hybrid procedure was performed with ductal stenting and reverse BT shunt. Previously performed bilateral pulmonary artery bands are also visible. ( b ) At 5 months of age, a Norwood procedure with modified arch reconstruction and bidirectional cavopulmonary shunt was performed. The aortic arch was reconstructed from partially resected stented ductal patch and the main pulmonary artery. The original ascending aorta was anastomosis with the main pulmonary artery. Superior vena cava was anastomosed to the divided branch pulmonary artery with angioplasty of the pulmonary artery with bovine pericardial patch. BCPS = bidirectional cavopulmonary shunt; BT = Blalock–Taussig; MPA = main pulmonary artery; SVC = superior vena cava; PA = pulmonary artery.
Figure 2. Cardiac CT. ( a ) Before the Norwood procedure, a ductal stent (red arrow) was positioned from the pulmonary end of patent ductus arteriosus to proximal descending thoracic aorta, which is jailing the ascending aorta and its branches. ( b ) The reverse BT shunt maintained blood flow to the ascending aorta and branches. ( c ) A CT scan performed 4 years after the Norwood procedure showed that the partially resected stent (red arrowhead) allows good retrograde flow to the ascending aorta and its branches. ( d ) There was no stenosis noted on the anastomosis of superior vena cava and pulmonary artery. Mild stenosis of the proximal left pulmonary artery is observed. BT = Blalock–Taussig; BCPS = bilateral cavopulmonary shunt.
At 5 months old and weighing 5.5 kg, following complete recovery from the wound complication, the next-stage procedure, Norwood procedure, and bilateral cavopulmonary shunt were planned. In the preoperative evaluation, the ductal stent extended from the pulmonary end of the patent ductus arteriosus to the proximal descending thoracic aorta, resulting in the jailing of the arch vessels (Figure 2a). The removal of the entire stent and ductal tissue would pose challenges for neo-aortic arch reconstruction, given the difficulty in managing the small remnant tissue. To address this, a modified aortic arch reconstruction was planned, involving the retention of the stented ductal patch, resected at the opening area of the arch vessels, which was modified from the previous report. Reference Caldarone, Honjo, Benson and Van Arsdell3 Before the Norwood procedure, we simulated operative plan using a three-dimensional (3D)-printed heart model based on the patient’s cardiac CT image to determine detailed process of the operation more precisely (Figure 3a–c). Regarding cardiopulmonary bypass, arterial cannulation was performed in the innominate artery through previous reverse Blalock–Taussig shunt graft after dividing it; venous cannulation was proceeded at the right atrium and inferior vena cava. Regional perfusion was started after snaring the left common carotid and left subclavian arteries. The left and right pulmonary arteries were divided with button formation from the transected main pulmonary artery. The resected branch pulmonary arteries were reconstructed using a bovine pericardial patch from the resected area to both hila, including a relatively narrow area due to previous pulmonary artery banding. Ductal stent was partially cut at the ostia of arch vessels, without distorting stent structure. Neo-aorta reconstruction using native tissue-to-tissue, end-to-end anastomosis was proceeded. After snaring of the arch vessels, aorta cross-clamp and cardioplegia were started right after the division of the ascending aorta from the aortic arch. Aorta cross-clamp was moved to the neo-aorta. Side-to-side anastomosis of the neo-aorta and ascending aorta was performed after longitudinal incision of the ascending aorta. Superior vena cava was divided and anastomosed at the reconstructed pulmonary artery to form bidirectional cavo-pulmonary shunt (Figure 1b).
Figure 3. Three-dimensional printed heart model before the Norwood procedure. ( a ) Anterior–posterior view. ( b ) Lateral view. Stented ductus arteriosus is indicated with white arrow. ( c ) Posterior–anterior view. Each part of the heart was distinguished with different colour. (Purple: pulmonary artery, red: aorta and arch vessels, yellow: reverse Blalock–Taussig shunt). A = anterior; F = foot; H = head; L = left; P = posterior; R = right.
Post-operative echocardiography and cardiac CT revealed no significant arch stenosis, sufficient aortopulmonary space, good ascending aorta and arch vessel flow, good superior vena cava flow, and increased size of branch pulmonary arteries. The patient was transferred to the general ward on post-operative day 9 and discharged on post-operative day 25 without any acute complication. Three months following the Norwood procedure, she underwent balloon pulmonary angioplasty for left pulmonary artery stenosis. Currently, at the age of 4 and weighing 13.7 kg, she underwent cardiac catheterisation as a part of the pre-Fontan operation work-up, which revealed 16 mmHg pressure gradient at the site of the aortic stent. Balloon angioplasty was performed on the aortic stent using an Armada35 12 mm diameter-20 mm length balloon dilatation catheter (Abbott Medical New Zealand Ltd, Auckland, New Zealand), after which the pressure gradient decreased to 7 mmHg. Three months after the balloon angioplasty, a cardiac CT showed no significant stenosis in the aortic arch, but mild left pulmonary artery stenosis was observed (Figure 2c,d). The patient is scheduled to undergo additional balloon angioplasty for left pulmonary artery stenosis, followed by the Fontan procedure.
Discussion
While performing neo-aorta reconstruction in Norwood procedure after hybrid palliation procedure, we utilised a modified reconstruction technique presented by Caldarone et al. Reference Caldarone, Honjo, Benson and Van Arsdell3 which uses retained stented ductal patch. They suggested several advantages of modified technique over traditional reconstruction. First, the shape and size of the stent is fitted with the contour of the aortic arch, and stented ductal tissue is sturdy enough to endure surgical handlings such as suture after 4 to 6 months from stent insertion. Furthermore, some serious complications such as bleeding and recurrent laryngeal nerve injury can be avoided using a modified technique because there is no need to dissect and resect all ductal tissue.
Post-operative airway and branch pulmonary artery stenosis after aortic arch reconstruction in Norwood procedure occasionally happens, and sometimes it becomes a serious complication and even requires reoperation. Hasegawa et al. Reference Hasegawa, Oshima and Maruo4 investigated the geometric change in the aortic arch after Norwood procedure and suggested augmentation of arch angle will be helpful for preventing such complications by widening the aortopulmonary space. Therefore, modified arch reconstruction with retained stented patch preserves original aortic arch geometry well, preventing narrowing of the aortopulmonary space which may cause stenosis of the branch pulmonary artery or bronchus. In this patient, as shown in Figure 2d, there was sufficient space for the branch pulmonary artery. However, the stenosis appeared to be residual from the previous pulmonary artery banding.
Additionally, in this case, we used open-cell-type stent for ductal stenting. A previous study has shown the possibility of overdilation of the side strut of these stents by ballooning or stent fracture. Reference Krasemann, Kruit, van der Mark, Zeggelaar, Dalinghaus and van Beynum5 As described by Danon et al., Reference Danon, Gray and Crystal6 serial dilation of stents in CHD can allow for expansion to almost twice the original diameter. Therefore, if necessary, interventional procedure such as balloon angioplasty can be applied according to the growth of the patient.
Several recent articles have shown that the 3D printing technology gives patients-matched models of complex CHD. This technique may be helpful for several clinical situations, particularly planning and rehearsing procedure. Reference Batteux, Haidar and Bonnet7,Reference Hermsen, Roldan-Alzate and Anagnostopoulos8 We could determine the very precise extent of patent ductus arteriosus stent cutting and detailed plan of neo-aorta reconstruction with 3D-printed heart model.
In conclusion, modified neo-aorta reconstruction with retained stented patch in Norwood procedure can be a considerable surgical option after hybrid palliation therapy in case of hypoplastic left heart syndrome with high-risk features. And driven utilisation of 3D printing technology can be helpful for planning surgical procedure of complex CHD.
Competing interests
None.
