Tissue-engineered and autologous pericardium in congenital heart surgery: comparative histopathological study of human vascular explants.

OBJECTIVES: The goal of this histological study was to assess the biocompatibility of vascular patches used in the repair of congenital heart defects. METHODS: We examined tissue-engineered bovine (n = 7) and equine (n = 7) patches and autologous human pericardium (n = 7), all explanted due to functional issues or follow-up procedures. Techniques like Movat-Verhoeff, von Kossa and immunohistochemical staining were used to analyse tissue composition, detect calcifications and identify immune cells. A semi-quantitative scoring system was implemented to evaluate the biocompatibility aspects, thrombus formation, extent of pannus, inflammation of pannus, cellular response to patch material, patch degradation, calcification and neoadventitial inflammation. RESULTS: We observed distinct material degradation patterns among types of patches. Bovine patches showed collagen disintegration and exudate accumulation, whereas equine patches displayed edematous swelling and material dissolution. Biocompatibility scores were lower in terms of cellular response, degradation and overall score for human autologous pericardial patches compared to tissue-engineered types. The extent of pannus formation was not influenced by the type of patch. Bovine patches had notable calcifications causing tissue hardening, and foreign body giant cells were more frequently seen in equine patches. Plasma cells were frequently detected in the neointimal tissue of engineered patches. CONCLUSIONS: Our results confirm the superior biocompatibility of human autologous patches and highlight discernible variations in the changes of patch material and the cellular response to patch material between bovine and equine patches. Our approach implements the semi-quantitative scoring of various aspects of biocompatibility, facilitating a comparative quantitative analysis across all types of patches, despite their inherent differences.

Stenting of native right ventricular outflow tract obstructions in symptomatic infants: histological work-up of explanted specimen.

BACKGROUND: Stenting of stenotic right ventricular outflow tract is a palliative measure for severely impaired small babies with Tetralogy of Fallot or similar pathologies. Little is known about the histopathological fate of the stents in the right ventricular outflow tract. METHODS: Eight samples of surgically removed right ventricular outflow tract stents were histologically analysed according to a predefined protocol. RESULTS: The most frequent diagnosis was Tetralogy of Fallot in four patients, pulmonary atresia with ventricular septal defect in two patients, double outlet right ventricle with pulmonary obstruction in one patient, and muscular obstruction of the right ventricular outflow tract in one patient with a syndromic disease with hypertrophic cardiomyopathy. Stents mean implantation duration was 444 days ranging from 105 to 1117 days (median 305.5 days). Histology revealed a variable degree of pseudointima formation consisting of fibromuscular cells surrounded by extracellular matrix. Four of the specimen contained adjacent myocardial tissue fragments, which showed regressive changes. Neither myocardium nor pseudointima tissue or tissue parts locally related to stent struts were infiltrated by inflammatory cells. CONCLUSIONS: Histological analysis after explantation of early-in-life implanted right ventricular outflow tract stents revealed predominantly pronounced neo-intimal proliferation with a visible endothelial layer, no signs of inflammation, and no prolapse of muscular tissue through the stent struts. Thus, implantation of stents in early life seems to interfere little with the hosts' immune system and might help to open up the right ventricular outflow tract by mechanical forces and regressive changes in adjacent muscular tissue.

Pacemaker lead insertion sites contribute to abnormalities of myocardial function and histopathology.

BACKGROUND: Ventricular pacing can cause myocardial dysfunction, but how lead anchoring to the myocardium affects function has not been studied. OBJECTIVE: The purpose of this study was to evaluate patterns of regional and global ventricular function in patients with a ventricular lead using cine cardiac computed tomography (CCT) and histology. METHODS: This was a single-center retrospective study with 2 groups of patients with a ventricular lead: (1) those who underwent cine CCT from September 2020 to June 2021 and (2) those whose cardiac specimen was analyzed histologically. Regional wall motion abnormalities on CCT were assessed in relation to lead characteristics. RESULTS: For the CCT group, 122 ventricular lead insertion sites were analyzed in 43 patients (47% female; median age 19 years; range 3-57 years). Regional wall motion abnormalities were present at 51 of 122 lead insertion sites (42%) in 23 of 43 patients (53%). The prevalence of a lead insertion-associated regional wall motion abnormality was higher with active pacing (55% vs 18%; P < .001). Patients with lead insertion-associated regional wall motion abnormalities had a lower systemic ventricular ejection fraction (median 38% vs 53%; P < .001) than did those without regional wall motion abnormalities. For the histology group, 3 patients with 10 epicardial lead insertion sites were studied. Myocardial compression, fibrosis, and calcifications were commonly present directly under active leads. CONCLUSION: Lead insertion site-associated regional wall motion abnormalities are common and associated with systemic ventricular dysfunction. Histopathological alterations including myocardial compression, fibrosis, and calcifications beneath active leads may explain this finding.

Assessment of Nit-Occlud atrial septal defect occluder device healing process using micro-computed tomography imaging.

After percutaneous implantation of a cardiac occluder, a complex healing process leads to the device coverage within several months. An incomplete device coverage increases the risk of device related complications such as thrombosis or endocarditis. We aimed to assess the device coverage process of atrial septal defect (ASD) occluders in a chronic sheep model using micro-computed tomography (micro-CT). After percutaneous creation of an ASD, 8 ewes were implanted with a 16-mm Nit-Occlud ASD-R occluder (PFM medical, Cologne, Germany) and were followed for 1 month (N = 3) and 3 months (N = 5). After heart explant, the device coverage was assessed using micro-CT (resolution of 41.7 µm) and was compared to histological analysis. The micro-CT image reconstruction was performed in 2D and 3D allowing measurement of the coverage thickness and surface for each device. Macroscopic assessment of devices showed that the coverage was complete for the left-side disk in all cases. Yet incomplete coverage of the right-side disk was observed in 5 of the 8 cases. 2D and 3D micro-CT analysis allowed an accurate evaluation of device coverage of each disk and was overall well correlated to histology sections. Surface calculation from micro-CT images of the 8 cases showed that the median surface of coverage was 93±8% for the left-side disk and 55±31% for the right-side disk. The assessment of tissue reactions, including endothelialisation, after implantation of an ASD occluder can rely on in vitro micro-CT analysis. The translation to clinical practice is challenging but the potential for individual follow-up is shown, to avoid thrombotic or infective complications.

EGFR and MMP-9 are associated with neointimal hyperplasia in systemic-to-pulmonary shunts in children with complex cyanotic heart disease.

Systemic-to-pulmonary shunt malfunction contributes to morbidity in children with complex congenital heart disease after palliative procedure. Neointimal hyperplasia might play a role in the pathogenesis increasing risk for shunt obstruction. The aim was to evaluate the role of epidermal growth factor receptor (EGFR) and matrix-metalloproteinase 9 (MMP-9) in the formation of neointimal within shunts. Immunohistochemistry was performed with anti-EGFR and anti-MMP-9 on shunts removed at follow-up palliative or corrective procedure. Whole-genome single-nucleotide polymorphisms genotyping was performed on DNA extracted from patients´ blood samples and allele frequencies were compared between the group of patients with shunts displaying severe stenosis (≥ 40% of lumen) and the remaining group. Immunohistochemistry detected EGFR and MMP-9 in 24 of 31 shunts, located mainly in the luminal area. Cross-sectional area of EGFR and MMP-9 measured in median 0.19 mm2 (IQR 0.1-0.3 mm2) and 0.04 mm2 (IQR 0.03-0.09 mm2), respectively, and correlated positively with the area of neointimal measured on histology (r = 0.729, p < 0.001 and r = 0.0479, p = 0.018, respectively). There was a trend of inverse correlation between the dose of acetylsalicylic acid and the degree of EGFR, but not MMP-9, expression within neointima. Certain alleles in epidermal growth factor (EGF) and tissue inhibitor of metalloproteinases 1 (TIMP-1) were associated with increased stenosis and neointimal hyperplasia within shunts. EGFR and MMP-9 contribute to neointimal proliferation in SP shunts of children with complex cyanotic heart disease. SP shunts from patients carrying certain risk alleles in the genes encoding for EGF and TIMP-1 displayed increased neointima.

Mid-term performance of decellularized equine pericardium in congenital heart surgery.

OBJECTIVE: The aim was to report mid-term performance of decellularized equine pericardium used for repair of various congenital heart defects in the pediatric population. METHODS: A retrospective review of all patients undergoing patch implantation between 2016 - 2020 was performed. Patch quality, surgical handling, hemostasis and early patch-related complications were studied on all patients. Mid-term performance was observed in patients with ≥12 months follow-up and intact patch at discharge (without reoperation/stent implantation). RESULTS: A total of 201 patients with median age of 2.5 years [interquartile range (IQR): 0.6-6.5] underwent 207 procedures at 314 implant locations. The patch was used in following numbers/locations: 171 for pulmonary artery (PA) augmentation, 36 for aortic repair, 35 for septal defect closure, 22 for valvular repair and 50 at other locations. Early/30-day mortality was 6.5%. Early patch-related reoperations/stent implantations occurred in 28 locations (8.9%). No patch-related complications were noted except for bleeding from implant site in three locations (1%). Follow-up ≥ 12 months was available for 132 patients/200 locations. During a median follow-up of 29.7 months [IQR: 20.7-38.3], 53 patch-related reoperations/catheter reinterventions occurred (26.5%) with the majority in PA position (88.7%, 47/53). Overall 12- and 24-months freedom from patch-related reoperation/catheter reintervention per location was 91.5% (95% CI: 86.7%-94.6%) and 85.2% (95% CI: 78.9%-89.6%) respectively. CONCLUSION: Decellularized equine pericardium used for repair of various congenital heart defects showed acceptable mid-term performance. Reoperation/reintervention rates were in a range as observed with other xenogeneic materials previously reported articles, occurring most frequently after PA augmentation.

Neointimal hyperplasia in systemic-to-pulmonary shunts of children with complex cyanotic congenital heart disease.

OBJECTIVES: Neointimal hyperplasia might affect systemic-to-pulmonary shunt failure in infants with complex cyanotic congenital heart disease. The aim of this study was to elucidate histopathologic changes in polytetrafluoroethylene shunts and to determine whether increased neointimal formation is associated with early interventions comprising balloon dilatation, stent implantation and shunt revision. Furthermore, we intended to identify clinical factors associated with increased neointimal proliferation. METHODS: Removed shunts were processed for histopathological analysis. Slides were stained with hematoxylin/eosin and Richardson. Immunohistochemistry was performed with anti-alpha-smooth muscle actin and anti-CD68. Non-parametric analysis and univariable regressions were performed to identify clinical factors associated with neointimal hyperplasia and shunt stenosis. RESULTS: Fifty-seven shunts (39 modified Blalock-Taussig anastomosis, 8 right ventricle-to-pulmonary artery anastomosis, 10 central shunts) were analysed. Area of neointimal proliferation within the shunt was in median 0.75 mm2 (interquartile range, 0.3-1.57 mm2) and relative shunt stenosis in median 16.7% (interquartile range, 6.7-30.8%). Neointimal hyperplasia and shunt stenosis correlated with each other and were significantly greater in the group that required early interventions and shunt revision. Univariable linear regression identified smaller shunt size and lower acetylsalicylic acid dosage as factors to be associated with greater neointimal proliferation and shunt stenosis. CONCLUSIONS: In infants with complex cyanotic congenital heart disease, neointimal hyperplasia in systemic-to-pulmonary shunts is associated with early interventions comprising balloon dilatation, stent implantation and shunt revision. Smaller shunt size and lower aspirin dosage are associated with increased neointimal proliferation.

Stereophotogrammetry can feasibly assess 'physiological' longitudinal three-dimensional head development of very preterm infants from birth to term.

Head development is a surrogate for brain development in infants and is related to neurocognitive outcome. There is only limited knowledge on early extra-uterine head shape and size assessment in very preterm infants. Here, 26 very preterm infants with a mean gestational age of 29.1 ± 2.2 weeks and a mean birth weight of 1273.8 ± 427.7 g underwent serial stereophotogrammetric 3D head imaging in weekly intervals from birth to term-equivalent age. The main outcome was the longitudinal assessment of the 'physiological' preterm head development with cephalometric size (head circumference, cranial volume) and shape parameters (cranial index, cranial vault asymmetry index) according to chronological and postmenstrual age (PMA). Potential clinical risk factors for the development of an abnormal low cranial index (dolichocephaly) were analysed. In serial measurements of 26 infants, the estimated head volume (95% confidence interval) increased from 244 (226-263) cm3 at 28 weeks PMA to 705 (688-721) cm3 at 40 weeks PMA. Moderate or severe dolichocephaly occurred in 21/26 infants (80.8%). Cranial index decreased over time (72.4%; 70.7-74 95% confidence interval). Brachycephaly and plagiocephaly were uncommon. No risk factors for severe dolichocephaly were identified. Our study shows that early detection of head shape and size anomalies utilizing 3D stereophotogrammetry is feasible and safe even in very preterm infants < 1500 g and/or < 32 weeks. 3D stereophotogrammetry could be used for timely identification of infants at risk for head shape anomalies. No specific risk factors for head shape anomalies were identified, especially not mode and duration of respiratory support.

Uni-ventricular palliation vs. bi-ventricular repair: differential inflammatory response.

BACKGROUND: To examine whether uni-ventricular palliation (UVP) and bi-ventricular repair (BVR) result in a different pattern of systemic inflammatory response to pediatric cardiac surgery with extra-corporeal circulation (ECC). METHODS: In 20 children (median age 39.5 months) undergoing either UVP (n = 12) or BVR (n = 8), plasma levels of the inflammatory cytokines TNF-α, IL-6, IL-10, and IL-12 and of procalcitonin (PCT), were measured before, during and after open cardiac surgery up to postoperative day (POD) 10. RESULTS: Epidemiologic, operative- and outcome variables were similar in both groups but post-operative central venous pressure that was higher in UVP. In the whole cohort, the inflammatory response was characterized by an early important, significant and parallel increase of IL-6 and IL-10 that reached their peak values either at the end of ECC (IL-10) or 4 h postoperatively (IL-6), respectively and by a significant and parallel decrease of TNF-α and IL-12 levels after connection to ECC, followed by a bi-phasic significant increase with a first peak 4 h after ECC and a second at POD 10, respectively. Patients after UVP showed a shift of the cytokine balance with lower IL-6- (p = 0.01) after connection to ECC, lower early post-operative TNF-α - (p = 0.02) and IL-12- (p = 0.04) concentrations and lower TNF-α/IL-10-ratio (p = 0.03) as compared with patients with BVR. Levels of PCT were similar in both groups. CONCLUSIONS: UVP is associated with an anti-inflammatory shift of the inflammatory response to cardiac surgery that might be related to the particular hemodynamic situation of patients with UVP.

Transcatheter mitral valve repair using the Cardioband® system: Histopathological insights in device ingrowth and biocompatibility.

Surgical implantation of a complete or incomplete ring to reduce the valve annulus and improve leaflet coaptation is the mainstay of mitral valve surgery. The Cardioband® system (Edwards Lifesciences) was designed to address the pathophysiological mechanism of annular dilatation through a catheter-based approach. We present the histopathological workup of a Cardioband® device, which had been implanted 21 months earlier in a 34-year-old male with ischemic cardiomyopathy. Device examination demonstrate a well-positioned and securely anchored device. The described tissue reactions may have an impact on choice of device and timing in case of re-do surgery.

Pulmonary artery augmentation using decellularized equine pericardium (Matrix Patch™): initial single-centre experience.

OBJECTIVES: The aim of this study was to report our initial experience when using Matrix Patch™ a cell-free equine-derived pericardium for the augmentation of branch pulmonary arteries (PAs) in children. METHODS: Between September 2016 and September 2019, Matrix Patch was used for the augmentation of branch PAs in 96 patients and implanted in 147 separate locations. The median age at implantation was 3.2 years (interquartile range: 0.9-8.4), and 33% of patients were infants. The patch was used mainly in redo surgeries (89.6%). Intra-procedural feasibility and reinterventions were analysed. Primary end points were death or patch-related reoperation/stent implantation. Explanted patches were stained for recellularization/calcification, or to reveal proliferation/inflammation. RESULTS: A total of 81 patients, who received patches in 119 separate locations, were followed within a median of 20 months (interquartile range: 10.2-30.2). Patients with early reoperation/stent implantation were excluded from follow-up. No patch-related death was noted. Survival at last follow-up was 88% (95% CI: 78.8-93.7%). Overall probability of freedom from reoperation/stent implantation per location, 12 and 24 months after initial surgery was 85.8% (95% CI: 76.2-91.7%) and 78.7 (95% CI: 65.9-87.2%), respectively. At 20 months, superficial proliferation with discrete macrophage activity was seen in explants; however, no signs of calcification are observed. CONCLUSIONS: The initial experience with the Matrix Patch in PAs showed comparable results to other xenogeneic patch materials. Long-term follow-up data are needed to prove the desired durability of the patch in different locations.

Nit-Occlud atrial septal defect occluder device: Histological characterisation of the healing process.

We describe the healing process following transcatheter implantation of the Nit-Occlud ASD-R occluder (PFM medical, Cologne, Germany) for atrial septal defect closure in a sheep model with histological confirmation of neotissue formation covering the device.

Screening for potential targets to reduce stenosis in bioprosthetic heart valves.

Progressive stenosis is one of the main factors that limit the lifetime of bioprosthetic valved conduits. To improve long-term performance we aimed to identify targets that inhibit pannus formation on conduit walls. From 11 explanted, obstructed, RNAlater presevered pulmonary valved conduits, we dissected the thickened conduit wall and the thin leaflet to determine gene expression-profiles using ultra deep sequencing. Differential gene expression between pannus and leaflet provided the dataset that was screened for potential targets. Promising target candidates were immunohistologically stained to see protein abundance and the expressing cell type(s). While immunostainings for DDR2 and FGFR2 remained inconclusive, EGFR, ErbB4 and FLT4 were specifically expressed in a subset of tissue macrophages, a cell type known to regulate the initiation, maintenance, and resolution of tissue repair. Taken toghether, our data suggest EGFR, ErbB4 and FLT4 as potential target candidates to limit pannus formation in bioprosthestic replacement valves.

Surgically placed radiopaque markers: Proof-of-concept of a novel technique to facilitate percutaneous interventions in neonates and infants.

OBJECTIVES: Aim of this study was to evaluate feasibility and benefit of self-designed, radiopaque markers as a novel technique in neonates and infants with shunt- or duct-dependent lesions. BACKGROUND: Surgically placed radiopaque markers have the potential to facilitate postoperative percutaneous interventions. METHODS: All consecutive children with surgically placed radiopaque markers involving systemic-to-pulmonary artery connections or arterial ducts in the context of hybrid palliation and subsequent cardiac catheterization between January 2013 and March 2019 were included in this analysis. Our primary endpoint was our concept's feasibility, which we defined as a combination of surgical feasibility and the percutaneous intervention's success. Secondary endpoint was the rate of complications resulting from the surgical procedure or during catheterization. RESULTS: Radiopaque markers that reveal the proximal entry of a surgical shunt or the arterial duct proved to be a feasible and beneficial approach in 25 postoperative catheterizations. The markers' high accuracy enabled easy probing and proper stent positioning in 13 neonates with a median age and weight of 121 days (range 9-356) and 4.7 kg (1.6-9.4) at the intervention. No procedural complications or unanticipated events associated with the radiopaque marker occurred. The markers were never lost, never migrated, and caused no local obstructive lesion. Surgical removal was straightforward in all patients. CONCLUSIONS: Radiopaque markers are a promising and refined technique to substantially facilitate target vessel access and enabling the accurate positioning of stents during postoperative percutaneous procedures.

Expectoration of bronchial casts in association with Ramipril treatment.

We report of a 26-year-old female patient who was referred to our centre with congestive heart failure (CHF). Acute myocarditis with a high Parvovirus B19 virus load was diagnosed by myocardial biopsy. CHF improved after start of ramipril 5 mg/d, metoprolol, diuretics, immunoglobins, and a 24-hour infusion of levosimendan. Soon after initiation of medical therapy, the patient started to expectorate bronchial casts with varying frequencies (three times per week to five times daily). Thorough pneumological workup, including histology of the casts, microbiology, and a CT scan of the lungs, did not reveal any cause for bronchial cast formation. Inhalative corticoids were started without any benefit. Two years later, cardiac catheterisation demonstrated normalised left ventricular function. LV end-diastolic pressure, however, was still elevated at 14 mmHg. Endomyocardial biopsies at this time were negative for virus genome. Finally, we changed afterload reduction therapy from ramipril to candesartan. Within 24 hours, expectoration of bronchial casts terminated. Four weeks later, re-exposition to ramipril prompted immediate re-appearance of cast formation, which again stopped with switching back to candesartan. Finally, we were to prove that treatment with ramipril resulted in bronchial cast formation in this patient.