Sinus Bradycardia: Escape-Capture Bigeminy

Report:

Sinus bradycardia 38/min 3

Ventricular pacemaker escape beats 2

Escape-capture bigeminy 4

Nonspecific ST/T changes 1

Comment:

A precondition for escape-capture bigeminy is a very long effective supraventricular cycle, created in this instance by sinus bradycardia (sinus rhythm with, e.g., 2:1 block would have done as well). Another precondition is the absence of retrograde conduction from the subsidiary (escape) pacemaker – or else the slow rhythm would be wiped out altogether.

Before Marriott’s classical description29 this rhythm was called “pseudoreciprocal”, because of the P wave between the complexes. It maintenance is, as Marriott aptly put it, “an arithmetic caprice” – a coincidental relationship between the two cycle lengths.

Incidentally, the rhythm strip is mislabelled as I instead of II. Lead II is not a good one for ventricular conduction, as shown in this example.

Fig 47. 88 year old man, confused and hypotensive.

If you have any suggestions for or feedback on this report, please let us know.