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

Abstract

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.

Keywords: Aortic stenosis; Aortic valve replacement; Case report; Complete atrioventricular block; Syncope.

Figure 1

Time series of electrocardiograms. Vertical and horizontal bars denote 1 mV and 0.4 s, respectively. (A) Twelve-lead electrocardiogram of complete atrioventricular block 3 months before the present visit shows electrical atrioventricular dissociation. (B) Twelve-lead electrocardiogram of complete atrioventricular block at the present visit. (C) Twelve-lead electrocardiogram immediately after surgical aortic valve replacement shows spontaneous R waves following temporary atrial pacing. Atrial pacing spike to R-wave duration is 190 ms. (D) Twelve-lead electrocardiogram on post-operative Day 7 shows regular sinus rhythm with a PR interval of 154 ms.

Figure 2

Calcified aortic valve complex on computed tomography. (A) Left anterior oblique cross-sectional image reveals heavy aortic valve calcification extending to the interventricular membranous septum. Inset image shows a view parallel to the aortic valve. (B and C) 3D images reconstructed from computed tomography. White arrowheads indicate calcification attached to aortic valve. Ao, ascending aorta; LV, left ventricle; RV, right ventricle.

Figure 3

Intra-operative findings of the aortic valve. (A) Intra-operative image of the aortic valve from the aortic side. (B) Schema of the image. Asterisks indicate heavy calcifications. R + L, fused right and left cusps; N, non-coronary cusp.