Although the footprints of atrial and ventricular ectopy are similar, there are enough differences to justify ventricular ectopy having its own set of ECGs. Some of the ECGs have been covered previously and this may act as a refresher.Let us start with ventricular bigeminy:

Alternate complexes are ventricular ectopics (red highlight).Usually the coupling intervals are similar.When they are not, then ventricular ectopy may have a more sinister significance particularly if they are from the left ventricle (right bundle branch block). Interpolated ventricular bigeminy may create a kaleidoscope of findings.

Look before you read.

• The appearance is a bidirectional rhythm or tachycardia (>100 bpm). . (A topic for the future).
• Ventricular bigeminy (red highlight)
• Ventricular interpolation.
• Sinus cycles progressively increase (blue arrows)
• Coupling intervals differ.
• Wenckebach atrio-ventricular sequence without a dropped beat (red arrows).
• Ectopic R-R intervals identical suggesting parasystole (purple arrows).

Ventricular bigeminy with retrograde conduction

Embedded in the ectopic T wave are retrograde P waves (red highlight). These are premature and not sinus P waves.Late ventricular ectopics are referred to as end-diastolic ventricular ectopics and if they occur in bigeminy, ventricular fusion is likely.

In this example, the ventricular ectopic (red highlight) coupling intervals gradually lengthen exposing sinus P waves (red arrows). Thus the ectopics lie in the PR intervals of the next sinus beat. The first ectopic (VE) is early enough to completely depolarize the ventricles, whereas the next two; V fusion₁ and V fusion₂ are well into the PR interval allowing some sinus generated ventricular depolarization and consequently fusion beats.Note that fusion beats involving the sinus node often have a pseudo-Wolff-Parkinson-White appearance.Ventricular trigeminy are sequences of two sinus cycles (red dots) followed by an ectopic (red highlight) and the sequence commences again.

There are embedded, concealed, non-conducted sinus P waves (yellow dots).The ventricular ectopics may be interpolated.

In this example, the sinus and the ventricular ectopic cycles remain constant in timing and all of the P waves are conducted. Ventricular quadrigeminy are sequences of three sinus cycles (red dots) followed by an ectopic (red highlight) and the sequence commences again.

There are embedded, concealed, non-conducted sinus P waves (yellow dots).Once again, the ventricular ectopics may be interpolated (red highlight) and all sinus P waves conducted.

Remember, it’s all in the timingHarry Mond