Prosthetic valve leaflet perforation resulting in critical aortic insufficiency: A rare late complication after use of Cor-knot®.

The implementation of automatic fasteners such as the Cor-knot® device (LSI Solutions, Inc.) has revolutionized the field of minimally invasive valvular surgery. Nonetheless, paravalvular regurgitation, valvular embolization, and early leaflet perforation are all potential complications which may occur. Late manifestations of leaflet perforation (>5-year postimplantation) are rare. Herein, we discuss a patient who underwent remote Trifecta® (St. Jude, Inc.) surgical aortic valve replacement presenting with symptomatic critical aortic regurgitation secondary to leaflet perforation from automatically fastened metallic Cor-knot® sutures.

Synchronous Type 3 EVAR Endoleaks at Multiple Sites Following Transfemoral Transcatheter Aortic Valve Replacement.

We describe a complication following transfemoral transcatheter aortic valve replacement in a patient who underwent remote endovascular abdominal aortic aneurysm repair. This report highlights technical complications to be vigilant of when using intravascular catheterization in patients with previous aneurysm repair while also showcasing synchronous type 3 endoleaks at multiple sites. (Level of Difficulty: Advanced.).

Uninterrupted Continuation of VV-ECMO Without Anticoagulation for 44 Days in COVID-19 ARDS: A Precarious Quandary.

Venovenous extracorporeal membrane oxygenation (VV-ECMO) has become a mainstay treatment modality for a select patient population who do not respond to conventional medical therapy suffering from severe acute respiratory distress syndrome (ARDS) due to COVID-19. This therapy necessitates the utilization of anticoagulation, whether unfractionated heparin or bivalirudin, to prevent thrombotic complications. Scarce are reports of VV-ECMO implementation leading to acute hemorrhage mandating cessation of anticoagulation in a patient suffering from COVID-19 ARDS. Herein, the authors report a case of a successful outcome in a COVID-19 ARDS patient who suffered an acute hemorrhagic complication leading to pre-emptive termination of systemic anticoagulation. The authors believe this to be one of the first such cases in the literature.

Right Ventricular Failure Manifesting in Corona Virus Disease 2019 Acute Respiratory Distress Syndrome: A Call to Transition from Venovenous Extracorporeal Membranous Oxygenation to Right Ventricular Assist Device Extracorporeal Membranous Oxygenation.

Often labeled the forgotten ventricle, the right ventricle's (RV) importance has been magnified over the last 2 years as providers witnessed how severe acute respiratory syndrome coronavirus 2 infection has a predilection for exacerbating RV failure. Venovenous extracorporeal membranous oxygenation (VV-ECMO) has become a mainstay treatment modality for a select patient population suffering from severe COVID-19 acute respiratory distress syndrome. Concomitant early implementation of a right ventricular assist device with ECMO (RVAD-ECMO) may confer benefit in patient outcomes. The underlying mechanism of RV failure in COVID-19 has a multifactorial etiopathogenesis; nonetheless, clinical evaluation of a patient necessitating RV support remains unchanged. Herein, the authors report the case of a critically ill patient who was transitioned from a conventional VV-ECMO Medtronic Crescent cannula to RVAD-ECMO, with the insertion of the LivaNova ProtekDuo dual-lumen RVAD cannula.

Enhancing stability and expression of recombinant human hemoglobin in E. coli: Progress in the development of a recombinant HBOC source.

The commercial feasibility of recombinant human Hb (rHb) as an O(2) delivery pharmaceutical is limited by the production yield of holoprotein in E. coli. Currently the production of rHb is not cost effective for use as a source in the development of third and fourth generation Hb-based oxygen carriers (HBOCs). The major problems appear to be aggregation and degradation of apoglobin at the nominal expression temperatures, 28-37 degrees C, and the limited amount of free heme that is available for holohemoglobin assembly. One approach to solve the first problem is to inhibit apoglobin precipitation by a comparative mutagenesis strategy to improve apoglobin stability. alpha Gly15 to Ala and beta Gly16 to Ala mutations have been constructed to increase the stability of the alpha helices of both subunits of HbA, based on comparison with the sequences of the more stable sperm whale hemoglobin subunits. Fetal hemoglobin is also known to be more stable than human HbA, and sequence comparisons between human beta and gamma (fetal Hb) chains indicate several substitutions that stabilize the alpha1beta1 interface, one of which, beta His116 to Ile, increases resistance to denaturation and enhances expression in E. coli. These favorable effects of enhanced globin stability can be augmented by co-expression of bacterial membrane heme transport systems to increase the rate and extent of heme uptake through the bacterial cell membranes. The combination of increased apoglobin stability and active heme transport appear to enhance holohemoglobin production to levels that may make rHb a plausible starting material for all extracellular Hb-based oxygen carriers.