Two for the Price of One

Report:

Sinus rhythm 80/min (top) & 91/min (bottom)

VEBs, two couplets

Fully compensatory pauses (top)

Comment:

Depending on the sinus rate and the timing of the VEBs, a couplet may replace one or two sinus beats; usually it replaces two, as in the bottom strip. In the top strip, the couplet has strategically sandwiched a blocked P wave, and the sinus rate is slower: the couplet causes the same compensatory pause as the single VEB at the beginning of the strip.

Below (on this page) is another couplet (from a 74 year old on digoxin + verapamil, in neighbouring bed) having two VEBs for the price of one. In his case, the second P wave is only partially blocked, through concealed retrograde conduction. The next sinus cycle is foreshortened accordingly, mimicking a SVEB.

170. 81 year old man with dizzy spells for the past fortnight. Some broad complexes are closely followed by normal ones; why? Also, what is happening to the sinus node?

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