Idioventricular Rhythm

Idioventricular rhythm refers to an intrinsic rhythm that starts in the ventricles (Figure 31-4). It originates in the ventricular area and the depolarization wave spreads either partially through the electrical conduction system or completely via direct cell-to-cell transmission. The intrinsic rate in idioventricular rhythm is most commonly between 30 and 50 beats per minute (BPM), but the rhythm can be anywhere from 20 to 50 BPM. The idioventricular complexes will have the morphologic characteristics of the ectopic ventricular complexes (wider than 0.12 seconds, bizarre appearance, ST-segment and T-wave abnormalities).

The ECG complex for idioventricular rhythm shows a sharp dip, a curved peak, and a curved dip occurring at regular intervals.

Figure 31-4 Idioventricular rhythm.

© Jones & Bartlett Learning.

An idioventricular rhythm may develop because of increased automaticity of a ventricular escape focus. An idioventricular rhythm may also develop as an escape mechanism if the supraventricular pacemakers fail, in order to overcome a very slow supraventricular bradycardia, or if there is a block of AV conduction (Figure 31-5).

The ECG complex shows idioventricular rhythm with P waves buried at different points in the complexes. P-P intervals are regular.

Figure 31-5 Idioventricular rhythm with AV dissociation.

© Jones & Bartlett Learning.