Skip to main content
. Author manuscript; available in PMC: 2020 Oct 30.
Published in final edited form as: J Vis Exp. 2019 Nov 7;(153):10.3791/60472. doi: 10.3791/60472

Figure 3: Representative examples of lead II electrocardiogram recordings collected during sinus rhythm or in response to external pacing.

Figure 3:

(A) Normal sinus rhythm. (B) Example of epicardial pacing at cycle length of 400 ms (S1−S1), which was used for imaging experiments. (C) Top: Atrial pacing to identify WBCL; successful capture is observed at S1 = 250 ms wherein atrial to ventricular conduction is observed. Note that atrial pacing can be used to determine SNRT (time to sinus node discharge, after commencing external pacing). Bottom: As the S1 cycle length is decreased to 205 ms, the conduction to the ventricle fails. (D) Top: Epicardial pacing (S1−S2) to identify VERP; successful capture is observed at S1 = 450 ms, S2 = 300 ms. Bottom: As the S2 cycle length is decreased to 250 ms, the ventricular tissue fails to capture. (E) Atrial pacing (S1−S2) to identify AVNERP. Top: Successful capture is observed at S1 = 450 ms, S2 = 200 ms. Bottom: As the S2 cycle length is decreased to 199 ms, conduction to the ventricle fails. Blue arrows denote pacing spikes, red arrows denote capture (‘C’) or no capture (‘NC’). S1−S1 = dynamic pacing, S1−S2 = extrastimulus pacing.