Parasystole

Report:

Sinus rhythm

Ventricular parasystole

Ventricular fusion beats

Comment:

Identical VEBs with different coupling intervals but a constant interectopic interval (or an exact multiple thereof) constitute parasystole.

The protected ventricular focus keeps firing at a fixed rate and captures the ventricle whenever the latter is not refractory. It behaves like a fixed-rate electronic pacemaker. The 6th complex in the second strip and the first one in the third are obvious fusion beats.

The sheet as a whole illustrates the well-known tendency of parasystole, once suspected, to consume large quantities of the ECG paper.

219. 52 year old man uncomfortable with “butterflies” in his chest. There is no significant medical history.

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