Reinforcement of the pulmonary artery autograft with a polyglactin and polydioxanone mesh in the Ross operation: experimental study in growing lamb.

BACKGROUND AND AIM OF THE STUDY: Synthetic materials used for pulmonary autograft (PA) reinforcement in the Ross procedure fail to match the demand for structural growth, have only a limited longevity, and do not guarantee adequate vascular compliance in high-pressure load systems. The study aim was to develop a resorbable reinforcement of a PA, tailored to provide structural support and to guide the process of wall structure modification for the preservation of graft viability. METHODS: An experimental model of translocation of the pulmonary trunk as an autograft in the aortic position was developed and performed under cardiopulmonary bypass in young lambs. The PA was left without reinforcement, reinforced with standard commercially available mesh, or reinforced with resorbable mesh of polyglactin and polydioxanone. RESULTS: Based on vessel diameter measurements by transesophageal echography at day 0 and at six months postoperatively, only the PA with resorbable reinforcement showed a behavior similar to that of the normal aorta in a growing lamb. With the non-resorbable reinforcement, transmural migration of the mesh was observed, accompanied by a conspicuous inflammatory infiltrate and fibrosis. CONCLUSION: The resorbable mesh allowed for histological wall modification, characterized by the presence of highly organized smooth muscle cells and elastic lamellae in the media. The mechanical and histological features of this resorbable mesh-reinforced PA may be crucial to the clinical long-term success of the Ross procedure.

Limited diagnostic value of questionnaire-based pre-participation screening algorithms: a "risk-exposed" approach to sports activity.

BACKGROUND: Several pre-participation screening algorithms (PPSAs) have been proposed to assess sports eligibility in different populations. They are usually based on self-administered questionnaires, without further medical assessment if no risk factors are documented. The Med-Ex "Formula Benessere" worksite program includes a complete cardiovascular (CV) screening for all participants. The purpose of this study was to assess PPSAs accuracy in detecting medical and/or CV abnormalities in the general population, comparing the results with the date derived from Med-Ex program. METHODS: The Med-Ex medical evaluation, consisting of medical history, physical examination (including body composition), resting electrocardiogram (ECG) and exercise stress test in 464 male subjects (38.4 aged) was analyzed and matched to several PPSAs - Physical Activity Readiness Questionnaire (PAR-Q) (2002-2020), American Heart Association (AHA)/American College of Sport Medicine (ACSM) (1998-2009-2014-2015), European Association of Cardiovascular Prevention and Rehabilitation (EACPR) (2011) - retrospectively simulated. RESULTS: Five-hundred and 67 abnormalities were detected though Med-Ex medical evaluation, and one-fourth (24%) would have been undetected applying PPSA alone. In particular 28% of high blood pressure, 21% of impaired fasting glycaemia, 21% of high Body Mass Index (BMI) values and 19% of ECG abnormalities would have been missed, on average, by all PPSAs. CONCLUSIONS: The simulation analysis model performed in this study allowed to highlight the limits of PPSAs in granting sport eligibility, compared to a medical-guided CV screening. These findings emphasize the importance of a more balanced approach to pre-participation screening that includes a thorough evaluation of the cost/benefit ratio.

Surface functionalization of polyurethane scaffolds mimicking the myocardial microenvironment to support cardiac primitive cells.

Scaffolds populated with human cardiac progenitor cells (CPCs) represent a therapeutic opportunity for heart regeneration after myocardial infarction. In this work, square-grid scaffolds are prepared by melt-extrusion additive manufacturing from a polyurethane (PU), further subjected to plasma treatment for acrylic acid surface grafting/polymerization and finally grafted with laminin-1 (PU-LN1) or gelatin (PU-G) by carbodiimide chemistry. LN1 is a cardiac niche extracellular matrix component and plays a key role in heart formation during embryogenesis, while G is a low-cost cell-adhesion protein, here used as a control functionalizing molecule. X-ray photoelectron spectroscopy analysis shows nitrogen percentage increase after functionalization. O1s and C1s core-level spectra and static contact angle measurements show changes associated with successful functionalization. ELISA assay confirms LN1 surface grafting. PU-G and PU-LN1 scaffolds both improve CPC adhesion, but LN1 functionalization is superior in promoting proliferation, protection from apoptosis and expression of differentiation markers for cardiomyocytes, endothelial and smooth muscle cells. PU-LN1 and PU scaffolds are biodegraded into non-cytotoxic residues. Scaffolds subcutaneously implanted in mice evoke weak inflammation and integrate with the host tissue, evidencing a significant blood vessel density around the scaffolds. PU-LN1 scaffolds show their superiority in driving CPC behavior, evidencing their promising role in myocardial regenerative medicine.

A composite semiresorbable armoured scaffold stabilizes pulmonary autograft after the Ross operation: Mr Ross's dream fulfilled.

OBJECTIVES: Use of resorbable external reinforcement of the pulmonary autograft during the Ross operation has been suggested, but the differential regional potential for dilation of the aorta, mainly regarding the neo-root and the neo-Valsalva sinuses, represents an unresolved issue. Auxetic materials could be useful in preventing dilation given their favorable mechanical properties. We designed a composite semiresorbable armoured bioprosthesis constituted by polydioxanone and expanded polytetrafluoroethylene and evaluated its effectiveness as a pulmonary autograft reinforcement device in an animal model of the Ross procedure. METHODS: An experimental model of the Ross procedure was performed in 20 three-month-old growing lambs. The pulmonary autograft was alternatively nonreinforced (control group n = 10) or reinforced with composite bioprosthesis (reinforced group n = 10). Animals were followed up during growth for 6 months by angiography and echocardiography. Specific stainings for extracellular matrix and immunohistochemistry for metalloproteinase-9 were performed. RESULTS: Reference aortic diameter increased from 14 ± 1 mm to 19 ± 2 mm over 6 months of growth. In the control group, pulmonary autograft distension (28 ± 2 mm) was immediately noted, followed by aneurysm development at 6 months (40 ± 2 mm, P < .001 vs reference). In the reinforced group, an initial dilation to 18 ± 1 mm was detected and the final diameter was 27 ± 2 mm (42% increase). Two deaths due to pulmonary autograft rupture occurred in the control group. On histology, the control group showed medial disruption with connective fibrous replacement, whereas in the reinforced group compensatory intimal hyperplasia was present in the absence of intimal tears. The bioprosthesis promoted a positive matrix rearrangement process favoring neoarterialization and elastic remodeling as demonstrated on specific staining for elastin collagen and metalloproteinase-9. CONCLUSIONS: The device adapted and functionally compensated for the characteristics of autograft growth, guaranteeing a reasonable size of the autograft at 6 months, but more important, because the device is biocompatible, it did not disrupt the biological process of growth or cause inflammatory damage to the wall.