After 15 years of successive randomized, controlled trials, indications for transcatheter aortic valve replacement (TAVR) are rapidly expanding. In the coming years, this procedure could become the first line treatment for patients with a symptomatic severe aortic stenosis and a tricuspid aortic valve anatomy. However, randomized, controlled trials have excluded bicuspid aortic valve (BAV), which is the most frequent congenital heart disease occurring in 1% to 2% of the total population and representing at least 25% of patients 80 years of age or older referred for aortic valve replacement. The use of a less invasive transcatheter therapy in this elderly population became rapidly attractive, and approximately 10% of patients currently undergoing TAVR have a BAV. The U.S. Food and Drug Administration and the “European Conformity” have approved TAVR for low-risk patients regardless of the aortic valve anatomy whereas international guidelines recommend surgical replacement in BAV populations. Given this progressive expansion of TAVR toward younger and lower-risk patients, heart teams are encountering BAV patients more frequently, while the ability of this therapy to treat such a challenging anatomy remains uncertain. This review will address the singularity of BAV anatomy and associated technical challenges for the TAVR procedure. We will examine and summarize available clinical evidence and highlight critical knowledge gaps regarding TAVR utilization in BAV patients. We will provide a comprehensive overview of the role of computed tomography scans in the diagnosis, and classification of BAV and TAVR procedure planning. Overall, we will offer an integrated framework for understanding the current role of TAVR in the treatment of bicuspid aortic stenosis and for guiding physicians in clinical decision-making.

Objective: Whether endotheliopathy only mirrors coronavirus disease 2019 (COVID-19) severity or plays an intrinsic role in microvascular thrombosis and organ failure remains unanswered. We assessed whether markers of endothelial damage and immune dysregulation were associated with organ failure, thrombus formation, and death. Approach and Results: Markers of endothelial damage (VWF:Ag [von Willebrand factor antigen], PAI-1 [plasminogen activator inhibitor-1], syndecan-1, TFPI [tissue factor pathway inhibitor], and soluble thrombomodulin), complement activation (C5a and C5b-9), cytokines (IL [interleukin]-6, TNF [tumor necrosis factor]-α, and IL-2R), and neutrophil extracellular traps (cell-free DNA, nucleosomes, and myeloperoxidase-DNA) were measured at intensive care unit admission in 82 patients with COVID-19. We also analyzed the histological composition of thrombi collected in critically ill living patients successfully weaned from extracorporeal membrane oxygenation. Beside respiratory failure, VWF:Ag, PAI-1, TFPI, and syndecan-1 were independently associated with liver injury and multiorgan failure development, underlining the direct role of endotheliopathy in organ failure. Nucleosomes were also associated with liver injury, multiorgan failure, and death which occurred in 38%, 60%, and 27% of patients, respectively. Moreover, dysregulated immune response including cytokines, complement, and neutrophil extracellular traps was associated with markers of endothelial damage, respiratory failure, and liver injury. COVID-19 thrombi retrieved from extracorporeal membrane oxygenation circuitry contained accumulation of neutrophils, VWF, and significantly higher amount of neutrophil extracellular traps when compared with non-COVID-19 thrombi. Conclusions: We provide new associative data supporting that endotheliopathy and dysregulated immune responses are involved in respiratory and liver failure through microvascular damage in patients with severe COVID-19.

Intra‐device thrombosis remains one of the most common complications during extracorporeal membrane oxygenation (ECMO). Despite anticoagulation, approximately 35% of patients develop thrombi in the membrane oxygenator, pump heads, or tubing. The aim of this study was to describe the molecular and cellular features of ECMO thrombi and to study the main drivers of thrombus formation at different sites in the ECMO circuits. Thrombi (n = 85) were collected immediately after veno‐arterial‐(VA)‐ECMO circuit removal from 25 patients: 23 thrombi from the pump, 25 from the oxygenator, and 37 from the tubing. Quantitative histological analysis was performed for the amount of red blood cells (RBCs), platelets, fibrin, von Willebrand factor (VWF), leukocytes, and citrullinated histone H3 (H3Cit). ECMO thrombi consist of a heterogenous composition with fibrin and VWF being the major thrombus components. A clustering analysis of the four major histological parameters identified two typical thrombus types: RBC‐rich and RBC‐poor/fibrin‐rich thrombi with no significant differences in VWF and platelet content. Thrombus composition was not associated with the thrombus location, except for higher amounts of H3Cit that were found in pump and oxygenator thrombi compared to tubing samples. We observed higher blood leukocyte count and lactate dehydrogenase levels in patients with fibrin‐rich thrombi. We found that thrombus composition is heterogenous, independent of their location, consisting of two types: RBC‐rich and a fibrin‐rich types. We also found that NETs play a minor role. These findings are important to improve current anticoagulation strategies in ECMO.

Background: Access site vascular and bleeding complications remain problematic for patients undergoing transcatheter aortic valve replacement (TAVR). Ultrasound-guided transfemoral access approach has been suggested as a technique to reduce access site complications, but there is wide variation in adoption in TAVR. We performed a systematic review and meta-analysis to compare access site vascular and bleeding complications according to the Valve Academic Research Consortium-2 classification following the use of either ultrasound- or conventional fluoroscopy-guided transfemoral TAVR access. Methods: Medline, Embase, Web of Science, and The Cochrane Library were searched to November 2020 for studies comparing ultrasound- and fluoroscopy-guided access for transfemoral TAVR. A priori defined primary outcomes were extracted: (1) major, (2) minor, and (3) major and minor (total) access site vascular complications and (4) life-threatening/major, (5) minor, and (6) life-threatening, major, and minor (total) access site bleeding complications. Results: Eight observational studies (n=3875) were included, with a mean participant age of 82.8 years, STS score 5.81, and peripheral vascular disease in 23.5%. An ultrasound-guided approach was significantly associated with a reduced risk of total (Mantel-Haenszel odds ratio [MH-OR], 0.50 [95% CI, 0.35–0.73]), major (MH-OR, 0.51 [95% CI, 0.35–0.74]), and minor (MH-OR, 0.59 [95% CI, 0.38–0.91]) access site vascular complications. Ultrasound guidance was also significantly associated with total access site bleeding complications (MH-OR, 0.59 [95% CI, 0.39–0.90]). The association remained significant in sensitivity analyses of maximally adjusted minor and total vascular access site complications (MH-OR, 0.51 [95% CI, 0.29–0.90]; MH-OR, 0.44 [95% CI, 0.20–0.99], respectively). Conclusions: In the absence of randomized studies, our data suggests a potential benefit for ultrasound guidance to obtain percutaneous femoral access in TAVR. Registration: URL: https://www.crd.york.ac.uk/PROSPERO/ ; Unique identifier: CRD42020218259.

BACKGROUND: Thrombocytopenia has been consistently described in patients with extracorporeal membrane oxygenation (ECMO) and associated with poor outcome. However, the prevalence and underlying mechanisms remain largely unknown, and a device-related role of ECMO in thrombocytopenia has been hypothesized. This study aimed to investigate the mechanisms underlying thrombocytopenia in ECMO patients. METHODS: In a prospective cohort of 107 ECMO patients, we investigated platelet count, functions, and glycoprotein shedding. In an ex vivo mock circulatory ECMO loop, we assessed platelet responses and VWF (von Willebrand factor)–GP Ibα (glycoprotein Ibα) interactions at low- and high-flow rates, in the presence or absence of red blood cells. The clearance of human platelets subjected or not to ex vivo perfusion was studied using an in vivo transfusion model in NOD/SCID (nonobese diabetic/severe combined Immunodeficient) mice. RESULTS: In ECMO patients, we observed a time-dependent decrease in platelet count starting 1 hour after device onset, with a mean drop of 7%, 35%, and 41% at 1, 24, and 48 hours post-ECMO initiation ( P =0.00013, P <0.0001, and P <0.0001, respectively), regardless of the type of ECMO. This drop in platelet count was associated with a decrease in platelet GP Ibα expression (before: 47.8±9.1 versus 24 hours post-ECMO: 42.3±8.9 mean fluorescence intensity; P =0.002) and an increase in soluble GP Ibα plasma levels (before: 5.6±3.3 versus 24 hours post-ECMO: 10.8±4.1 µg/mL; P <0.0001). GP Ibα shedding was also observed ex vivo and was unaffected by (1) red blood cells, (2) the coagulation potential, (3) an antibody blocking VWF–GP Ibα interaction, (4) an antibody limiting VWF degradation, and (5) supraphysiological VWF plasma concentrations. In contrast, GP Ibα shedding was dependent on rheological conditions, with a 2.8-fold increase at high- versus low-flow rates. Platelets perfused at high-flow rates before being transfused to immunodeficient mice were eliminated faster in vivo with an accelerated clearance of GP Ibα–negative versus GP Ibα–positive platelets. CONCLUSIONS: ECMO-associated shear forces induce GP Ibα shedding and thrombocytopenia due to faster clearance of GP Ibα–negative platelets. Inhibiting GP Ibα shedding could represent an approach to reduce thrombocytopenia during ECMO.