Click Valvar Academy #712 - A fisiologia dos bloqueios no TAVI
·7 min
The episode opens by stating that atrioventricular blockade remains a frequent complication of TAVI, posing three main questions about its timing and risk factors. It describes an electrophysiological study that monitored over 400 patients before, during, and after TAVI for up to a year. The first key finding is that late blockades occurring after the fifth day are more common than intra-procedure blockades, with 10% of patients needing permanent pacemakers. Historically, it was assumed all TAVI-related blockades were infra-Hessian due to direct mechanical injury from prosthesis expansion near the membrane septum. This assumption was reinforced by early electrocardiogram records showing characteristics like wide QRS. The study used continuous electrophysiological recording to objectively assess blockade levels, revealing that AV nodal blockades related to TAVI are real, with five patients experiencing them. This breaks the paradigm that all post-TAVI AV blockades are infra-nodal. The episode then explores practical applications, detailing risk factors for intra-procedure blockades such as previous right branch blockade, higher aortic ring calcium load, longer membranous septum, or prosthesis oversizing. For late blockades, risk factors include HV interval >80 ms, PR >300 ms, VENCA cycle >500 ms, shorter membranous septum in elderly, coronary disease, or deeper prosthesis implant. The final message is that blockade location and timing depend on pre-procedure patient characteristics, anatomy, and prosthesis expansion. This has clinical relevance for treating high-risk patients and avoiding unnecessary pacemaker implants. The episode notes that the rate of potentially avoidable blockades is not yet well defined, with ongoing studies. It concludes by mentioning the episode is part of the Valve Club Academy program, guided by Dr. Gabriel Doreto, with text by Gabriela Nobiger on changes in conduction after TAVI.
