Aortic growth after arch reconstruction with patch augmentation: a 2-decade experience

OBJECTIVES

Optimal aortic sizing during aortic arch reconstruction remains unknown. Negative effects of arch under- or oversizing are well-published. We aimed to characterize longitudinal aortic growth after patch-augmented arch reconstruction to identify the initial reconstructed arch size that results in normal mid-term arch dimensions.

METHODS

Single-centre, retrospective review of infants undergoing Damus-Kaye-Stansel (DKS) or non-DKS patch-augmented aortic arch reconstruction between 2000 and 2021. Ascending aorta, proximal and distal transverse arch, aortic isthmus (AIsth) and descending aorta dimensions were measured in postoperative echocardiograms (<3 months from index operation) and cross-sectional imaging (>12 months). Longitudinal changes to aortic dimensions and z-scores were analysed. Secondary outcomes included reintervention, valve and ventricular function, mortality and transplantation.

RESULTS

Fifty-four patients (16 DKS, 38 non-DKS) were included. At 6.3 [2.2, 12.0]-year follow-up, all aortic segments grew significantly in both groups, while z-scores remained unchanged except for non-DKS proximal and distal transverse arch z-scores, which significantly increased (P < 0.05 each). When stratified by initial postoperative z-score (z < -1, -1 ≤ z ≤ 1, z > 1), non-DKS patients with initial AIsth z-score <-1 had a final z-score significantly smaller than both the targeted z-score zero (P = 0.014) and final z-score in a group with initial postoperative z-score ±1 (P = 0.009). Valve and ventricular function remained stable. Eighteen patients required reintervention, 1 died and 1 underwent transplant.

CONCLUSIONS

Over mid-term follow-up, aortic growth after arch reconstruction with patch augmentation was proportional when repaired to normal z-score dimensions, aside from proximal transverse arch, which disproportionately dilated. AIsth undersizing prevailed mid-term and trended towards a higher reintervention rate. Initial reconstruction between z-score 0 and +1 resulted in maintenance of that z-score size at mid-term follow-up. Overall, it is crucial to achieve targeted aortic sizing at index operation to maintain appropriate aortic dimensions over time and reduce reintervention risk with specific focus on the AIsth.

Staged Ventricular Recruitment and Biventricular Conversion Following Single-ventricle Palliation in Unbalanced Atrioventricular Canal Defects

Objective

Restoration of biventricular circulation is an alternative management strategy in unbalanced atrioventricular canal defects (uAVCDs), especially in patients with risk factors for single-ventricle palliation (SVP) failure. When ventricular volume is inadequate for biventricular circulation, recruitment procedures may accommodate its growth. In this study, we review our uAVCD experience with biventricular conversion (BIVC) after prior SVP.

Methods

This is a single-institution, retrospective cohort study of uAVCD patients who underwent BIVC after SVP, with staged recruitment (staged) or primary BIVC (direct) between 2003 to 2018. Mortality, unplanned reinterventions, imaging, and catheterization data were analyzed.

Results

Sixty-five patients underwent BIVC from SVP (17 stage 1, 42 bidirectional Glenn, and 6 Fontan). Decision for conversion was based on poor SVP candidacy (n = 43) or 2 adequately sized ventricles (n = 22). Of the 65 patients, 20 patients underwent recruitment before conversion. The staged group had more severe ventricular hypoplasia than the direct group, reflected in prestaging end-diastolic volume z scores (-4.0 vs -2.6; P < .01), which significantly improved after recruitment (-4.0 to -1.8; P < .01). Median follow-up time was 1.0 years. Survival and recatheterizations were similar between both groups (hazard ratio, 0.9; 95% CI, 0.2-3.7; P = .95 and hazard ratio, 1.9; 95% CI, 0.9-4.1; P = .09), but more reoperations occurred with staged approach (hazard ratio, 3.1; 95% CI, 1.3-7.1; P = .01).

Conclusions

Biventricular conversion from SVP is an alternative strategy to manage uAVCD, particularly when risk factors for SVP failure are present. Severe forms of uAVCDs can be converted with staged BIVC with acceptable mortality, albeit increased reinterventions, when primary BIVC is not possible.

Restriction of Atrial Septal Defect Leads to Growth of Hypoplastic Ventricle in Patients with Borderline Right or Left Heart

Patients with borderline hypoplastic right or left ventricle and VSD may be candidates for either single ventricle palliation or staged ventricular recruitment (SVR) followed by eventual biventricular conversion. Components of SVR include restriction of atrial septal defects (ASD) without ventricular septal defects (VSD) closure and addition of accessory pulmonary blood flow. This study evaluated the impact of ASD restriction on ventricular growth and function. We retrospectively reviewed patients with borderline ventricular hypoplasia and VSD who underwent a staged ventricular recruitment (SVR) procedure from 2012 to June 2019. Pre- and post-recruitment MRI and echocardiogram data were compared and analyzed. We excluded cases in which we intentionally restricted VSD with simultaneous ASD restriction. Forty-six patients (41 with right-dominant ventricle, 25 with risk factors for Fontan procedure) underwent SVR at a median age of 15.1 months' (interquartile range (IQR), 7.2-37.2 months'). The median indexed ventricular end-diastolic volume, end-systolic volume, and stroke volume according to cardiac MRI significantly increased at median 11.0 months' (IQR:7.8~14.1 months') after recruitment. Among them, except 2 operative mortalities after SVR, 26 patients underwent bi-ventricular repair (56.5% including one and a half ventricle repair) at a median of 8.0 months' (IQR: 6.2-12.2 months') after recruitment. Fifteen patients await biventricular completion, and 3 patients underwent single ventricle palliation. Pulmonary blood flow (Qp) tended to increase after recruitment regardless of type of pulmonary blood flow modification without statistical significance. Six patients died at a median duration of 6.5 months' (IQR: 2.9-11.7) after SVR; 3 patients died after biventricular completion, 2 after recruitment, and 1 after returning to single ventricle palliation. All of them were considered poor Fontan candidates due to severe atrioventricular valve regurgitation, pulmonary hypertension, pulmonary vein stenosis, or airway stenosis. Restriction of the atrial septum leads to the growth of hypoplastic ventricle in patients with ventricular septal defects who undergo SVR regardless of the preoperative characteristics, and eventual biventricular repair can be performed in a subgroup of these patients. Future work is necessary to optimize timing of SVR and method of accessory pulmonary blood flow.

Super Glenn for staged biventricular repair: impact on left ventricular growth?

 

OBJECTIVES

The Super Glenn procedure involves targeted increased in blood flow to left sided heart structures with fenestrated atrial septation. The objective of this study was to examine the outcomes of patients who had this procedure as a part of biventricular staging and specifically evaluate the effect on dimensions of left heart structures.

METHODS

Data for patients who had this procedure between 2005 and 2019 were retrospectively identified.

RESULTS

Thirty-seven patients were identified. Most common diagnosis was hypoplastic left heart syndrome in 40% (n = 15). On echocardiography, the median mitral valve z score was -2.26. On cardiac magnetic resonance imaging, median indexed left ventricular end-diastolic volume was 31.5 ml/m2 and mitral/tricuspid inflow ratio was 0.35. The median age at Super Glenn was 2.3 years (interquartile range 1.5-3.6) while median weight was 12 kg (interquartile range 9.8-14). There were no early/hospital deaths. The median intensive care unit length of stay was 4 days, and median hospital length of stay was 10 days. Median follow-up for the entire cohort was 3 years (range 15 days to 13.2 years). There was a statistically significant increase in indexed left ventricular dimensions. There were 5 deaths (14%). Three patients (8%) underwent heart transplant. Freedom from death/transplant was 79% at 5 years. Seven patients (19%) needed a reoperation. Twenty-three patients (62%) underwent biventricular conversion after a median of 11.3 months after Super Glenn.

CONCLUSIONS

The Super Glenn procedure achieves consistent increase in left ventricular dimensions. This may be a useful strategy to help achieve a successful biventricular circulation in patients with borderline left ventricle. The superiority/non-inferiority of this approach over the conventional Fontan pathway is unclear.

Human endothelial colony-forming cells provide trophic support for pluripotent stem cell-derived cardiomyocytes via distinctively high expression of neuregulin-1

The search for a source of endothelial cells (ECs) with translational therapeutic potential remains crucial in regenerative medicine. Human blood-derived endothelial colony-forming cells (ECFCs) represent a promising source of autologous ECs due to their robust capacity to form vascular networks in vivo and their easy accessibility from peripheral blood. However, whether ECFCs have distinct characteristics with translational value compared to other ECs remains unclear. Here, we show that vascular networks generated with human ECFCs exhibited robust paracrine support for human pluripotent stem cell-derived cardiomyocytes (iCMs), significantly improving protection against drug-induced cardiac injury and enhancing engraftment at ectopic (subcutaneous) and orthotopic (cardiac) sites. In contrast, iCM support was notably absent in grafts with vessels lined by mature-ECs. This differential trophic ability was due to a unique high constitutive expression of the cardioprotective growth factor neuregulin-1 (NRG1). ECFCs, but not mature-ECs, were capable of actively releasing NRG1, which, in turn, reduced apoptosis and increased the proliferation of iCMs via the PI3K/Akt signaling pathway. Transcriptional silencing of NRG1 abrogated these cardioprotective effects. Our study suggests that ECFCs are uniquely suited to support human iCMs, making these progenitor cells ideal for cardiovascular regenerative medicine.

Intraoperative localization of cardiac conduction tissue regions using real-time fibre-optic confocal microscopy: first in human trial

OBJECTIVES

The aim of this study was to evaluate the feasibility and safety of fibre-optic confocal microscopy (FCM) using fluorescein sodium dye for the intraoperative location of conduction tissue regions during paediatric heart surgery.

METHODS

The pilot study included 6 patients undergoing elective surgery for the closure of isolated secundum atrial septal defect aged 30 days to 21 years. FCM imaging was integrated within the normal intraoperative protocol for atrial septal defect repair. Fluorescein sodium dye was applied on the arrested heart. FCM images were acquired at the atrioventricular node region, sinus node region and right ventricle (RV). Total imaging time was limited to 3 min. Any adverse events related to the study were recorded and analysed. Subjects received standard postoperative care. Trained reviewers (n = 9) classified, de-identified and randomized FCM images (n = 60) recorded from the patients as presenting striated, reticulated or indistinguishable microstructures. The reliability of reviewer agreement was assessed using Fleiss' kappa.

RESULTS

The FCM imaging instruments were integrated effectively into the cardiac surgery operating room. All adverse events found in the study were deemed expected and not related to FCM imaging. Reticulated myocardial microstructures were found during FCM imaging at atrioventricular node and sinus node regions, while striated microstructures were observed in RV. Reliability of agreement of reviewers classifying the FCM images was high (Fleiss' kappa: 0.822).

CONCLUSIONS

FCM using fluorescein sodium dye was found to be safe for use during paediatric heart surgery. The study demonstrates the potential for FCM to be effective in identifying conduction tissue regions during congenital heart surgery.

CLINICAL TRIAL REGISTRATION NUMBER

NCT03189134.

Repair of double outlet right ventricle: Midterm outcomes

OBJECTIVE

Double outlet right ventricle (DORV) is a complex cardiac malformation with many anatomic variations and various approaches for surgical repair. This study aimed to describe the clinical outcomes of biventricular (BiV) repair for DORV.

METHODS

Patients with DORV, who underwent BiV repair between January 2000 and December 2017 were retrospectively reviewed. Group 1 underwent primary BiV repair, whereas group 2 underwent staged BiV repair over a series of operations. The decision to pursue staged approach included complexity of intracardiac anatomy, age of the patient, and the size and function of the ventricles and the atrioventricular valves. Time-dependent surgical reintervention for LVOTO and mortality were evaluated using Kaplan-Meier survival analysis.

RESULTS

A total of 238 patients with DORV underwent BiV repair at a median age of 6.2 months (range, 1.1 month-27.5 years) (158 in group 1, 80 in group 2). Twenty-two patients (7.8%) required surgical reintervention within 30 days of BiV repair. Overall survival at 5 years was 89.0%. Freedom from LVOTO reoperation at 5 years was 84%. Primary outcomes were not significantly different between groups. CAVC repair and right ventricle to pulmonary artery conduit at BiV repair were associated with higher surgical reintervention (hazard ratio, 2.9 and 1.75, respectively).

CONCLUSIONS

Patients with DORV and complex anatomy may undergo staged BiV repair with acceptable outcomes. Although LVOTO is a potential complication in these patients, the rate of surgical reintervention for LVOTO does not differ significantly from patients undergoing primary BiV repair.

Photo-oxidized bovine pericardium in congenital cardiac surgery: single-centre experience

Objectives

Dye-mediated photo-oxidation of pericardium is an alternative method to chemical treatment with glutaraldehyde for cross-linking collagen, providing biostability of the patch material while avoiding late calcification and cytotoxicity. There are few data available, on using photo-oxidation-treated pericardium, in congenital cardiac surgery. This study reports the outcomes using Photofix™ bovine pericardium in neonates, infants, children and young adults undergoing paediatric cardiac surgery.

Methods

A total of 490 patches in 383 consecutive operations (364 patients) were used in the surgical repair of congenital heart defects at our institution from October 2008 to October 2011. Recorded variables included demographic data, age at operation, primary cardiac diagnosis, associated complications and number, type and location of patches placed and patch-related reintervention.

Results

Median age at operation was 5.3 years, ranging from <1 month to 56 years. The overall survival rate at late follow-up was 92%, and no deaths were related to failure of the tissue substitute. Two patients (0.5%) underwent reintervention late due to patch material failure: one for residual shunt after Rastelli repair and one for aneurysmal dilatation of a right ventricular outflow tract patch. The patch material was explanted in 8 patients at a mean of 20 months (range, 1-72 months) following implantation. Histological examination revealed mild to moderate inflammation with variable calcification.

Conclusions

Photo-oxidized bovine pericardium demonstrated excellent performance when used as a patch material in cardiovascular repair in children. Its handling characteristics and biocompatibility are consistent with a wide range of applications.

Host non-inflammatory neutrophils mediate the engraftment of bioengineered vascular networks

Notwithstanding remarkable progress in vascular network engineering, implanted bioengineered microvessels largely fail to form anastomoses with the host vasculature. Here, we demonstrate that implants containing assembled human vascular networks (A-Grafts) fail to engraft due to their inability to engage non-inflammatory host neutrophils upon implantation into mice. In contrast, unassembled vascular cells (U-Grafts) readily engage alternatively polarized neutrophils, which in turn serve as indispensable mediators of vascular assembly and anastomosis. The depletion of host neutrophils abrogated vascularization in U-Grafts, whereas an adoptive transfer of neutrophils fully restored vascularization in myeloid-depleted mice. Neutrophil engagement was regulated by secreted factors and was progressively silenced as the vasculature matured. Exogenous addition of factors from U-Grafts reengaged neutrophils and enhanced revascularization in A-Grafts, a process that was recapitulated by blocking Notch signaling. Our data suggest that the pro-vascularization potential of neutrophils can be harnessed to improve the engraftment of bioengineered tissues.

Study of PZT Film Stress in Multilayer Structures for MEMS Devices

Residual stress in the multilayer Si/Dielectric/Pt/PZT/Pt stack was measured as a function of annealing conditions, sol-gel derived PZT (Lead Zirconate Titanate -52/48) thickness, SiO2 and/or Si3N4 dielectric films thickness. Residual stress in the Si3N4 layer varied from -201 to +1275 MPa and from -430 to + 511 MPa in the Si02 layer. Furnace annealing of the bottom Pt film reduced the stress over rapid thermal annealing (RTA). Stress due to PZT films was the controlling factor for the final stress of the stack. Upon increasing PZT thickness, stress became less tensile for Si3N4 dielectric and more tensile for Si02. The deposition of the top Pt on PZT followed by RTA at 300°C in nitrogen had a minimal effect on the final stress of the stack. The average tensile stress for the Si/Si02 /Pt/PZT/Pt and Si/Si3N4/Pt/PZT/Pt stacks was 140 ± 25 and 476±235 MPa respectively.