Bleeding Complications in Patients With Perioperative COVID-19 Infection Undergoing Cardiac Surgery: A Single-Center Matched Case-Control Study.

OBJECTIVE: Previous studies reported a poor outcome in patients with coronavirus 2019 (COVID-19) undergoing cardiac surgery. Complications most frequently described were respiratory failure, renal failure, and thromboembolic events. In their recent experience, the authors observed a very high incidence of bleeding complications. The purpose of the study was to investigate a possible significant correlation between perioperative COVID-19 infection and hemorrhagic complications compared to non-COVID-19 patients. DESIGN: Single-center, observational, retrospective, matched case-control (1:2) study involving patients who underwent open-heart cardiac surgery from February 2020 and March 2021 with positive perioperative diagnosis of COVID-19 infection, matched with patients without COVID-19 infection. SETTING: Cardiac surgery unit and intensive care unit of a university tertiary center in a metropolitan area. PARTICIPANTS: In the study period, 773 patients underwent cardiac surgery on cardiopulmonary bypass (CPB). Among them, 23 consecutive patients had perioperative diagnosis of COVID-19 infection (study group). These patients were compared with 46 corresponding controls (control group) that matched for age, sex, body mass index, and Society of Thoracic Surgeons score. INTERVENTIONS: Open-heart cardiac surgery on CPB. MEASUREMENTS AND MAIN RESULTS: In the study group, 2 patients (9%) died in the intensive care unit from severe respiratory failure, shock, and multiple organ failure. In the study group, patients showed a significantly higher incidence of bleeding complications (48% v 2%, p = 0.0001) and cases of surgical reexploration for bleeding (35% v 2%, p = 0.0001), a higher incidence of severe postoperative thrombocytopenia (39% v 6%, p = 0.0007), and a higher need of blood components transfusions (74% v 30%, p = 0.0006). Chest tubes blood loss and surgical hemostasis time were markedly prolonged (p = 0.02 and p = 0.003, respectively). CONCLUSIONS: A worrisome increased risk of early and late bleeding complications in COVID-19 patients was observed, and it should be considered when assessing the operative risk. CPB-related inflammatory reaction could exacerbate the deleterious effect of COVID-19 on the coagulation system and likely deviate it toward a hemorrhagic pattern.

Urgent desensitization in patients bridged to heart transplantation under extracorporeal membrane oxygenation support: A preliminary experience.

Antihuman leukocyte antigen (HLA) antibodies restrict the access to cardiac allografts. Desensitization therapy is a major challenge in patients with cardiogenic shock waiting for urgent heart transplantation (HT). We retrospectively reviewed six patients (mean age of 37.5 years [16-70]) who underwent plasmapheresis (PP) under extracorporeal membrane oxygenation (ECMO) before transplant between January 2017 and September 2018. The average duration of follow-up was 25 months [20-32]. Mean fluorescence intensity (MFI) of HLA-specific antibodies was reported as follows: score 4 for MFI < 1000, score 6 for 1000 < MFI < 3000 and score 8 for MFI > 3000. The mean duration of ECMO support was 29 days [1-74] and 6.8 [1-29] PP sessions were performed per patient before transplant. The mean number of HLA-specific antibodies before HT was 9.6 for score 6 [4-13] and 5.8 for score 8 [1-12]. Four patients had major complications after transplantation (2 hemorrhagic shocks, 5 infectious events). Mean MFI reduction rate was 94% [79-100] for Class I and 44.2% for Class II [0-83]. Hospital survival was 100%, and early antibody-mediated rejection was diagnosed in one patient at 7 days after HT. Plasmapheresis under ECMO support was associated with favorable early outcomes in highly sensitized candidates for urgent heart transplantation.

Modulation of the interaction between human P450 3A4 and B. megaterium reductase via engineered loops.

Chimerogenesis involving cytochromes P450 is a successful approach to generate catalytically self-sufficient enzymes. However, the connection between the different functional modules should allow a certain degree of flexibility in order to obtain functional and catalytically efficient proteins. We previously applied the molecular Lego approach to develop a chimeric P450 3A4 enzyme linked to the reductase domain of P450 BM3 (BMR). Three constructs were designed with the connecting loop containing no glycine, 3 glycine or 5 glycine residues and showed a different catalytic activity and coupling efficiency. Here we investigate how the linker affects the ability of P450 3A4 to bind substrates and inhibitors. We measure the electron transfer rates and the catalytic properties of the enzyme also in the presence of ketoconazole as inhibitor. The data show that the construct 3A4-5GLY-BMR with the longest loop better retains the binding ability and cooperativity for testosterone, compared to P450 3A4. In both 3A4-3GLY-BMR and 3A4-5GLY-BMR, the substrate induces an increase in the first electron transfer rate and a shorter lag phase related to a domain rearrangements, when compared to the construct without Gly. These data are consistent with docking results and secondary structure predictions showing a propensity to form helical structures in the loop of the 3A4-BMR and 3A4-3GLY-BMR. All three chimeras retain the ability to bind the inhibitor ketoconazole and show an IC50 comparable with those reported for the wild type protein. This article is part of a Special Issue entitled: Cytochrome P450 biodiversity and biotechnology, edited by Erika Plettner, Gianfranco Gilardi, Luet Wong, Vlada Urlacher, Jared Goldstone.

Outcomes of Minimally Invasive Aortic Valve Replacement in Obese Patients: A Propensity-Matched Study.

INTRODUCTION: Obese patients are at risk of complications after cardiac surgery. The aim of this study is to investigate safety and efficacy of a minimally invasive approach via upper sternotomy in this setting. METHODS: We retrospectively reviewed 203 obese patients who underwent isolated, elective aortic valve replacement between January 2014 and January 2023 - 106 with minimally invasive aortic valve replacement (MIAVR) and 97 with conventional aortic valve replacement (CAVR). To account for baseline differences, a propensity-matching analysis was performed obtaining two balanced groups of 91 patients each. RESULTS: The 30-day mortality rate was comparable between groups (1.1% MIAVR vs. 0% CAVR, P=0.99). MIAVR patients had faster extubation than CAVR patients (6 ± 2 vs. 9 ± 2 hours, P<0.01). Continuous positive airway pressure therapy was less common in the MIAVR than in the CAVR group (3.3% vs. 13.2%, P=0.03). Other postoperative complications did not differ significantly. Intensive care unit stay (1.8 ± 1.2 vs. 3.2 ± 1.4 days, P<0.01), but not hospital stay (6.7 ± 2.1 vs. 7.2 ± 1.9 days, P=0.09), was shorter for MIAVR than for CAVR patients. Follow-up survival was comparable (logrank P-value = 0.58). CONCLUSION: MIAVR via upper sternotomy has been shown to be a safe and effective option for obese patients. Respiratory outcome was promising with shorter mechanical ventilation time and reduced need for post-extubation support. The length of stay in the intensive care unit was reduced. These advantages might be important for the obese patient to whom minimally invasive surgery should not be denied.

Comparison of De-Kay repair versus De Vega suture for functional tricuspid regurgitation: a preliminary experience.

BACKGROUND: In patients undergoing mitral valve surgery, restrictive suture annuloplasty (De Vega) for less-than-severe functional tricuspid regurgitation has been proven to be safe and effective. The aim of this study is to determine whether the adjunct of the plication of the posterior tricuspid leaflet with the same running suture (bicuspidized De Vega or "De Kay") is equally safe and effective. METHODS: Single center, retrospective study on patients submitted to suture repair of the tricuspid valve during mitral valve surgery, with either conventional or De Kay, between January 2014 and December 2020. Comparison was based on degree of residual tricuspid valve regurgitation and right ventricular assessment at discharge. RESULTS: Over the course of the study period, 255 patients undergoing mitral valve surgery had a dilated (>40 mm or >20 mm/m2) tricuspid valve annulus, with less-than-severe tricuspid regurgitation. Conventional De Vega was employed in 166 patients (65.1%) and De Kay in the remaining 89 (34.9%). At discharge the adjunct of postero-septal commissure plication has similar outcomes to the classic De Vega repair. It seems to preserve right ventricular function. CONCLUSIONS: De Kay repair guarantees the same tricuspidal regurgitation reduction as compared with conventional De Vega early after surgery.

Two innovative aortic bioprostheses evaluated in the real-world setting. First results from a two-center study.

BACKGROUND: The increasing use of biological substitutes for surgical aortic valve replacement (AVR), has led to the development of new bioprostheses with improved hemodynamics and expected durability. METHODS: In this observational retrospective two-center cohort study, two innovative bioprostheses, INSPIRIS Resilia and AVALUS were analyzed. We analyzed early and 2.4-year follow-up results in terms of safety, clinical outcome and hemodynamic performance. RESULTS: From November 2017 to February 2021, 148 patients underwent AVR with INSPIRIS Resilia (N.=74) or AVALUS (N.=74) bioprosthesis. The 30-day and mid-term mortality was comparable (1% vs. 3%, P=0.1 and 7% vs. 4%, P=0.4, respectively). Valve-related mortality was observed in one AVALUS patient. Three (4%) patients of the AVALUS group developed prosthetic endocarditis and two of them died after reoperation. No other cases of prosthetic endocarditis were observed. No cases of structural valve degeneration or significant paravalvular leak were detected at follow-up. Median follow-up peak pressure gradient was 21 vs. 23 mmHg (P=0.4) and the mean pressure gradient was 12 vs. 13 mmHg (P=0.9) for Inspiris and AVALUS, respectively. The effective orifice area (EOA) and indexed EOA were 1.5 cm2 vs. 1.4 cm2 (P=0.4) and 0.8 vs. 0.7 cm2/m2 (P=0.5), respectively. Indexed left ventricular mass regression was -33 vs. -52 g/m2 for the Inspiris and AVALUS groups, respectively, (R2-adjusted =0.14; P<0.01). CONCLUSIONS: INSPIRIS Resilia and AVALUS bioprostheses were reliable with comparable results in safety, clinical outcome and hemodynamic performance. After statistical adjustment, AVALUS was associated with better left ventricular mass reduction. Long-term follow-up would provide definitive comparative results.

Human Cytochrome P450 3A4 as a Biocatalyst: Effects of the Engineered Linker in Modulation of Coupling Efficiency in 3A4-BMR Chimeras.

Human liver cytochrome P450 3A4 is the main enzyme involved in drug metabolism. This makes it an attractive target for biocatalytic applications, such as the synthesis of pharmaceuticals and drug metabolites. However, its poor solubility, stability and low coupling have limited its application in the biotechnological context. We previously demonstrated that the solubility of P450 3A4 can be increased by creating fusion proteins between the reductase from Bacillus megaterium BM3 (BMR) and the N-terminally modified P450 3A4 (3A4-BMR). In this work, we aim at increasing stability and coupling efficiency by varying the length of the loop connecting the two domains to allow higher inter-domain flexibility, optimizing the interaction between the domains. Starting from the construct 3A4-BMR containing the short linker Pro-Ser-Arg, two constructs were generated by introducing a 3 and 5 glycine hinge (3A4-3GLY-BMR and 3A4-5GLY-BMR). The three fusion proteins show the typical absorbance at 450 nm of the reduced heme-CO adduct as well as the correct incorporation of the FAD and FMN cofactors. Each of the three chimeric proteins were more stable than P450 3A4 alone. Moreover, the 3A4-BMR-3-GLY enzyme showed the highest NADPH oxidation rate in line with the most positive reduction potential. On the other hand, the 3A4-BMR-5-GLY fusion protein showed a Vmax increased by 2-fold as well as a higher coupling efficiency when compared to 3A4-BMR in the hydroxylation of the marker substrate testosterone. This protein also showed the highest rate value of cytochrome c reduction when this external electron acceptor is used to intercept electrons from BMR to P450. The data suggest that the flexibility and the interaction between domains in the chimeric proteins is a key parameter to improve turnover and coupling efficiency. These findings provide important guidelines in engineering catalytically self-sufficient human P450 for applications in biocatalysis.