 Transcaval access to the abdominal aorta from the neighboring inferior vena cava IVC has enabled transcatheter aortic valve replacement TAVR in a small number of patients who have no good options for standard percutaneous femoral access or for standard surgical access to the cardiac apex or to the ascending aorta. In this prospective registry we will collect data from multiple medical centers as they offer transcaval TAVR to patients with extreme or prohibitive risk of conventional TAVR. 