Paradoxical restoration from complete and persistent atrioventricular block after surgical aortic valve replacement: a case report.

Background: One of the most important and relatively frequent complications of aortic valve replacement is atrioventricular block. It typically occurs by direct injury of the infranodal conduction system due to intra-operative manipulation and persists post-operatively, necessitating permanent pacemaker implantation in many cases.

Case summary: A 66-year-old man presented to our hospital after experiencing syncope while walking after drinking. He had experienced two episodes of alcohol-induced syncope several years earlier. His electrocardiogram (ECG) and transthoracic echocardiogram revealed complete atrioventricular block and severe aortic stenosis, respectively. He received a temporary pacemaker on the day of admission and underwent surgical aortic valve replacement on hospital Day 9. The native aortic valve was bicuspid. Unexpectedly, the ECG immediately after aortic valve replacement showed complete restoration of atrioventricular conduction during temporary atrial pacing. The atrioventricular block did not recur, and he was discharged to home on post-operative Day 13.

Discussion: This remarkably rare clinical course, complete restoration from complete and persistent atrioventricular block after surgical aortic valve replacement, can be explained by multifactorial mechanisms: (i) surgical removal of the aortic annulus calcification directly hindering the infranodal conduction system; (ii) relief from the ventricular pressure overload stressing the conduction system within the septum; and (iii) improvement of substantial autonomic dysregulation as manifested by alcohol-sensitive syncope in the present patient, which was a result of unloading of the intraventricular pressure affecting the left ventricular mechanoreceptor.