Yet again I’m indebted to Arron Pearce for my ECG of the month. This one was recorded from a 72-year-old male with chest pain. What I’m interested in is the rhythm and any possible conduction disturbances. Please provide as much detail as you can.
The format of the recording is such that every group of three leads shows the same 2.5 seconds of ECG. The lead II strip at the bottom is a 10-second serial recording.
Dr Dave Richley
Lovely rhythm challenge, again.
Looks to me like a bigeminal rhythm — sinus beats followed by PACs and PVCs, in an alternating pattern.
R1, 5, 9, 13, 17 = PACs
R2, 4, 6, 8, 10, 12, 14, 16 = sinus beats
R3, 7, 11, 15 = PVCs
The PACs conduct with LAFB — maybe due to phase 3 block in the LAFB. We can tell these are atrial beats due to the slight distortion of the T waves of the preceding sinus beat. I cannot reliably see any such distortion preceding what I think are PVCs, so I can reasonably assume they are not supraventricular.
The PVCs are not very wide (QRSd ≈ 120-130 ms) and have RBBB + LAFB morphology, with a rS in V4-6, suggestive of a left posterior fascicle origin.
Thanks, Onyinye. Some great comments there. I’m not sure I agree with you 100% but then I’m not completely certain that I’ve got it right either. I think I’ll need to study it very closely.
I’m pretty sure that we have p-waves hidden in the t-waves of the aberrant complexes, making this is sinus/atrial tachycardia with 3:2 conduction (atrial rate around 150bpm). I haven’t worked out the mechanism causing alternating aberration of each 2nd complex yet though.
Thanks, Scott. I hadn’t considered what you suggest and I’m not sure that the timing of the clearly visible P waves supports it but I’m certainly going to study the ECG again and in more detail before I make up my mind.
It is particularly hard for me to be 100% sure because of the configuration of the ECG — the same 2.5 seconds reproduced in all 12 leads, except the rhythm strip…
I would like to modify my initial assessment by saying it could possibly be simply sinus rhythm with atrial bigeminy with alternating aberrancy of the ectopic atrial beats — LAFB aberrancy and RBBB+LAFB aberrancy.