Transcatheter Aortic Valve Replacement (TAVR) Effects on Cardiac Conduction System

This is a prospective observational study, the purpose of which is to: 1. Characterize response of the AV conduction system to TAVR with various prostheses by recording continuous His bundle electrograms during valve placement. 2. Correlate preprocedure ECG features with changes in AV nodal and infranodal conduction during placement of the valve prosthesis. 3. Correlate changes in AV nodal and infranodal conduction during the procedure with risk of developing AV conduction block after TAVR. 4. Assess the contribution of stressing the conduction system by atrial pacing prior to and following TAVR to prediction of postprocedural heart block. Assess the correlation between new onset bundle branch block, site and degree of conduction block or delay and subsequent development of high-grade or complete AV block.