Pre-Emptive LAVA-ECMO for Complex High-Risk TAVR

The goal of this clinical trial is to evaluate the feasibility, effectiveness, and safety of pre-emptive left atrial veno-arterial extracorporeal membrane oxygenation (LAVA-ECMO) in patients undergoing complex and high-risk transcatheter aortic valve replacement (TAVR). These patients include adults with severe aortic stenosis who are hemodynamically unstable or at risk of instability due to anatomical complexity. The main questions it aims to answer are: 1. Does pre-emptive LAVA-ECMO reduce the incidence of in-hospital death, intraprocedural cardiac arrest, or emergent cardiac surgery? 2. What are the safety outcomes related to LAVA-ECMO, including major vascular, bleeding, or cardiac structural complications? -This is a single-arm, prospective, multi-center study with no comparison group. Participants will: * Be screened for eligibility based on hemodynamic status and anatomical complexity * Undergo pre-emptive LAVA-ECMO cannulation prior to or during TAVR * Receive follow-up assessments at 30 days and 1 year, including clinical evaluation and echocardiography