Pacemaker & Native Escape-Capture Bigeminy

Report:

Sinus bradycardia 37/min

Junctional & pacemaker escape beats

Escape-capture bigeminy

Pseudofusion beats

Fusion beat

Ventricular conduction defect, unspecified

Comment:

The escape-capture phenomenon depends in this case on sinus bradycardia.

The escape moiety of the bigeminal pairs is of either junctional or electrical pacemaker origin. Some junctional complexes have a pacemaker spike superimposed on them without contributing to the ventricular activation - the pseudofusion beats. Although the QRS of these beats is somewhat distorted, the repolarisation morphology is identical to that of other junctional beats; this is a practical way of differentiating them from true fusion beats with "just a tad" of fusion. It is also easily seen in these examples that the pacemaker spike follows the onset of the QRS, while it initiates the QRS in the paced beats or the true fusion beat (5th complex in the bottom strip).[!xe "Pacemaker, electronic:pseudofusion beats" \t "See Pseudofusion"!]