What are those intermittent "S" waves?

Laszlo Littmann

doi:10.1016/j.jelectrocard.2024.03.010

What are those intermittent "S" waves?

J Electrocardiol. 2024 Mar 28:84:100-102. doi: 10.1016/j.jelectrocard.2024.03.010. Online ahead of print.

Author

Laszlo Littmann¹

Affiliation

¹ Department Internal Medicine, Atrium Health Carolinas Medical Center, Charlotte, NC, USA. Electronic address: Laszlo.Littmann@gmail.com.

PMID: 38581752
DOI: 10.1016/j.jelectrocard.2024.03.010

Abstract

A 69-year-old woman had three syncopal events while flying on an airplane. She was found to be profoundly bradycardic. Two 12‑lead electrocardiograms (ECGs) showed ventricular rates in the thirties. In one, the QRS complexes were narrow. In the second ECG, there were wide negative deflections following the QRS complexes. Analysis of telemetry recordings revealed the underlying mechanism and helped establish appropriate programing of an implanted pacemaker.

Keywords: Pacemaker-mediated tachycardia; Syncope; Third-degree AV block; Unidirectional block.