Heart-Lung machine may shield High-Risk patients during valve procedure

Copied word for word from the study's registry entry, so the wording is the study team's rather than ours.

Inclusion Criteria: \- Patients are required to have either a Class III hemodynamic status OR type B or type C anatomical complexity with Class II (at risk) hemodynamics (Figure 2). * Hemodynamic Criteria * Major Criteria (Class III) * Systolic blood pressure \<90 mmHg or MAP\<60 mmHg * Need for vasopressors or inotropes to maintain MAP\>60 mmHg * Evidence of end-organ damage including: acute kidney injury, liver dysfunction, elevated lactate or altered mentation * Minor Criteria (Class II) * Left ventricular ejection fraction \<35% * Pulmonary hypertension (pulmonary artery systolic pressure \>60 mmHg) with right ventricular dysfunction * Pulmonary capillary wedge pressure \>30 mmHg * Anatomic criteria * Major Criteria (Type C) * Native or valve-in-valve TAVR requiring single-leaflet modification for a large area of myocardium at risk (e.g. patients with large or dominant left circulation) * Native or valve-in-valve TAVR requiring dual-leaflet modification * Severe bioprosthetic aortic regurgitation * Severe 3-vessel coronary artery disease not amenable to revascularization (SYNTAX score \>33) * Minor Criteria (Type B) * Native or valve-in-valve TAVR requiring single-leaflet modification * Severe commissural misalignment requiring leaflet modification * High-risk for coronary occlusion not amenable to leaflet modification * Critical low-flow low-gradient aortic stenosis (defined as an estimated aortic valve area ≤0.5 cm2) Exclusion Criteria: * Age \<18 or pregnant * General absolute contraindications to TAVR * Severe peripheral artery disease with infeasibility for veno-arterial extracorporeal membrane oxygenation implantation. * Contraindications to transeptal cannulation (e.g. pre-existing interatrial septum occluder device). * Pre-existing Impella treatment. * Onset of shock \>12 hours. * Preceding cardiac arrest with prolonged resuscitation (\>40 minutes). * Other severe concomitant disease with life expectancy \<6 months. * Participation in another trial with an intervention. * Any class I hemodynamic status * Type A anatomical complexity with class I or II hemodynamic status