This document discusses the role of echocardiography in assessing patients for and guiding transcatheter aortic valve implantation (TAVI). Echocardiography is used to evaluate aortic valve anatomy and geometry, assess suitability for different valve sizes, guide device positioning during the procedure, and evaluate complications. Key measurements include aortic annulus diameter, distance from the coronary ostia, and relationships to mitral valve and left ventricular outflow tract. Echocardiography provides real-time imaging during critical steps like valve deployment and balloon dilation to optimize positioning and identify paravalvular regurgitation. Follow up echos are important to evaluate prosthetic function and complications.