Pacemaker-Induced Reverse Wenckebach

Report:

Sinus rhythm 56 – 58/min 1

Reverse Wenckebach AV conduction 5

Demand pacemaker rhythm 60/min 1

Left atrial abnormality (LAA) 1

LVH with ST/T changes/incomplete LBBB 2

Comment:

This may be the first reported case of reverse Wenckebach in a 12-lead ECG60.

The tracing starts with four paced complexes followed by somewhat slower sinus P waves; the fourth P wave is far enough from the preceding paced QRS to capture the ventricle, albeit with a PR interval of 0.52”. For the ensuing four cycles the P-R intervals decrease as the R-R intervals increase. This is opposite of what happens in classical AV nodal Wenckebach conduction. It reflects the R-P and P-R reciprocity announced by Marriott61. The last beat is a fusion beat; it has two pseudofusion predecessors.

The tracing below Fig 118a, taken on admission, shows profound sinus bradycardia 28/min. Of the three visible P waves (there are four here), the first two also illustrate P-R – R-P reciprocity; the last one is blocked, being to close to the preceding escape beat.