Ex vivo biomechanical characterization of umbilical vessels: Possible shunts in congenital heart palliation

Children born with congenital heart defects typically undergo staged palliative surgeries to reconstruct the circulation to improve transport of deoxygenated blood to the lungs. As part of the first surgery, a temporary shunt (Blalock-Thomas-Taussig) is often created in neonates to connect a systemic and a pulmonary artery. Standard-of-care shunts are synthetic, which can lead to thrombosis, and much stiffer than the two host vessels, which can cause adverse mechanobiological responses. Moreover, the neonatal vasculature can undergo significant changes in size and structure over a short period, thus constraining the use of a non-growing synthetic shunt. Recent studies suggest that autologous umbilical vessels could serve as improved shunts, but there has not been a detailed biomechanical characterization of the four primary vessels - subclavian artery, pulmonary artery, umbilical vein, and umbilical artery. Herein, we biomechanically phenotype umbilical veins and arteries from prenatal mice (E18.5) and compare them to subclavian and pulmonary arteries harvested at two critical postnatal developmental ages (P10, P21). Comparisons include age-specific physiological conditions and simulated 'surgical-like' shunt conditions. Results suggest that the intact umbilical vein is a better choice as a shunt than the umbilical artery due to concerns with lumen closure and constriction related intramural damage in the latter. Yet, decellularization of umbilical arteries may be a viable alternative, with the possibility of host cellular infiltration and subsequent remodeling. Given recent efforts using autologous umbilical vessels as Blalock-Thomas-Taussig shunts in a clinical trial, our findings highlight aspects of the associated biomechanics that deserve further investigation.

27 years of experience with the Fontan procedure: characteristics and clinical outcomes of children in a tertiary referral hospital

BACKGROUND

The Fontan operation has improved the survival of children born with congenital heart disease with single ventricle physiology. The most widely adopted variations of the Fontan procedure are the extracardiac conduit, the lateral tunnel ve the intra/extracardiac conduit with fenestration. Despite advances in the treatment and prevention of early and late complications that may develop after Fontan surgery, morbidity still remains an important problem.

METHODS

304 patients who underwent Fontan surgery in our center between 1995 and 2022 were included in our study. The complications that developed in patients who underwent primary Fontan or lateral tunnel surgery and extracardiac conduit Fontan application were compared.

RESULTS

Classic Fontan surgery and lateral tunnel surgery were performed in 26 of the patients, and extracardiac Fontan surgery was performed in 278 patients. 218 of 304 cases were patients with single ventricular pathology. 86 cases were patients with two ventricular morphologies but complex cardiac pathology. Fenestration was performed in only 6 patients, other patients did not require fenestration. The mean follow-up period of our patients was 12 years (3 months-27 years). When the complications between Fontan procedures were compared in our study, it was found that the length of hospital stay and mortality were statistically significantly reduced in patients who underwent extracardiac Fontan surgery. There was no significant difference in terms of complications that can be seen after Fontan surgery and the length of stay in the intensive care unit.

CONCLUSION

Fontan complex is a palliative surgery for children with complex heart disease. Palliative surgical operations aimed at the preparation of the Fontan circulation lead to the preparation of the pulmonary vascular bed and the preservation of ventricular function. The techniques applied in Fontan surgery affect the early and long-term complications and the survival of the patients. In our study, when we examined the patients who extracardiac conduit Fontan procedure for the non-cardiac route, we found that mortality and morbidity were minimal.

Novel technique of achieving hemodynamic stability during systemic to pulmonary artery shunt

Historically, the Blalock Taussig (BT) shunt has been an off-pump procedure. For the last two decades, the number of BT shunt operations has come down globally with the adoption of neonatal early corrective surgery. BT shunts are still performed for augmentation of pulmonary arterial (PA) growth or as a part of univentricular palliation. Many infants do not tolerate PA branch clamping while undergoing the graft to PA anastomosis, necessitating institution of cardiopulmonary bypass (CPB). Since the threshold to go on CPB for shunt placement is quite low at most institutions, our technical modification described can avoid deleterious effect of CPB. Our point of interest is to maintain lung perfusion by adopting few principles of off-pump coronary artery bypass surgery.

From Other Journals: A Review of Recent Articles by Our Editorial Team

In this review, we provide a brief description of recently published articles addressing topics relevant to pediatric cardiologists. Our hope is to provide a summary of the latest articles published recently in other journals in our field. The articles reviewed in this manuscript address (1) long-term fate of the truncal valve, (2) comparison of combined heart‒liver vs heart-only transplantation in pediatric and young adult Fontan recipients showing non-inferior survival of heart-liver transplant in a small sample, (3) impact of palliation strategy on interstage feeding and somatic growth for infants with ductal-dependent pulmonary blood flow showing no difference in growth between ductal stenting and Blalock-Taussig shunt, (4) biventricular repair in interrupted aortic arch and ventricular septal defect with a small left ventricular outflow tract, (5) a randomized controlled trial comparing controlled reoxygenation and standard cardiopulmonary bypass in pediatric cardiac surgery, and (6) tricuspid valve and right ventricular function throughout the hybrid palliation strategy for hypoplastic left heart syndrome and variants.

Contralateral Pulmonary Hypertension Following Resuscitation of Unilateral Ductal Origin of a Pulmonary Artery: A Multi-institutional Review

In isolated unilateral ductal origin of a pulmonary artery (DOPA), intervention to establish reperfusion of the affected lung without direct re-anastomosis may lead to pulmonary hypertension (PH) in the contralateral lung. Multicenter retrospective review of patients with unilateral DOPA, who underwent palliation with a ductal stent (DS) or Blalock-Taussig (BT) shunt with subsequent development of PH in the contralateral lung, was conducted. Ten patients (4 females; median weight 3.2 kg, range 2.1-5.2) who underwent DS or BT shunt and developed contralateral PH were identified. Eight infants had right-sided DOPA. Stents/shunt used had a median diameter of 3.5 mm (range 2.5-5.2). After DS in 9 patients, 7 patients were exclusively treated with medical therapies, whereas 2 patients received intermediate procedures: one received an additional contralateral DS and other underwent surgical banding of the DS prior to PA reimplantation. Seven patients who underwent DS and one patient with BT shunt underwent PA reimplantation at median of 3.3 (0.6-18) months. PA pressure was documented to be normal in 5 patients immediately following PA reimplantation, 1 year later in 2 patients, and 1 patient is on Tadalafil with elevated PVR of 5.5 indexed Wood units. One patient died and one patient is awaiting surgery with normal PA pressure. We describe the development of severe contralateral PH following DS or BT shunt as the initial intervention for unilateral DOPA. Pulmonary hypertension resolved in 7/8 patients who underwent surgical PA reimplantation. The cause of PH in the normally connected lung in these cases remains unclear.

Perforation and right ventricular outflow tract stenting: Alternative palliation for infants with pulmonary atresia/ventricular septal defect

BACKGROUND

Right ventricular outflow tract (RVOT) stents have been used as palliation in patients with severe tetralogy of Fallot (TOF). Radiofrequency perforation of the RVOT has also been described in patients with pulmonary atresia (PA)/ventricular septal defect (VSD). However, RVOT stenting in conjunction with radiofrequency perforation as a means for establishing reliable pulmonary blood flow in patients with PA/VSD has not previously been reported.

OBJECTIVES

Our aim is to report our experience with using perforation of plate-like pulmonary valve atresia combined with stenting of RVOT as an alternative and equally efficacious intervention for infants with PA/VSD, as compared to a surgical pulmonary artery shunt (SPS).

METHODS

A retrospective review of patients with PA/VSD at our institution from Jan 2006 to October 2015 was performed.

RESULTS

Twenty-seven patients received palliation for PA/VSD. Five (median 2.5 kg, 2.1-4.1 kg) underwent RVOT stenting and 22 (3.5 kg, 2.1-4.6 kg) underwent surgical SPS. Of the patients who received an RVOT stent, 3 underwent guidewire perforation and balloon dilation of the plate-like pulmonary valve, and 2 underwent radiofrequency perforation of the pulmonary plate, followed by balloon dilation. Postprocedure saturations averaged 93% in the stent group and 89% in the shunt group. One of the patients who underwent RVOT stenting required additional stenting of the PDA for isolation of the LPA, but none required re-intervention. Four patients in the SPS cohort required re-intervention (18%). Two required stenting of the shunt, and 2 required surgical revision of the shunt. There was one death in the stent group, however this was secondary to withdrawal of support given an underlying genetic diagnosis (trisomy 13). There was one fatality in the SPS cohort prior to hospital discharge.

CONCLUSIONS

Perforation followed by RVOT stenting may be a safe and effective alternative to surgical SPS in infants with PA/VSD.