Electrocardiogram — Trigeminy

🥼 Practice and Clinical
1

This article was transcoded by SimpRead, original address mp.weixin.qq.com

Figure 1

Figure 2

Electrocardiogram Diagnosis:

  1. Sinus rhythm,

  2. Ventricular premature contraction.

Analysis:

Figure 1: The R5,6 wave groups are wide and malformed, appear prematurely, coupling interval < 0.6s, with no related P wave before them, indicating ventricular premature contractions.

Figure 2: The R3,6,9,12 are wide and malformed, appear prematurely, coupling interval < 0.6s, with no related P wave before them, indicating ventricular premature contractions.

Two sinus beats + one ventricular premature beat repeat to form a trigeminy.

I. General characteristics of ventricular premature contraction electrocardiogram:

  1. Wide and malformed QRS complex appears prematurely, duration greater than or equal to 0.12s, T wave direction opposite to the main wave.

  2. No related P wave before it, occasional P’ wave after it.

  3. Mostly accompanied by complete compensatory pause, rarely inserted.

II. Compensatory pause:

Refers to the ectopic beat appearing prematurely replacing a normal sinus beat followed by a pause longer than the normal cardiac cycle. Atrial ectopic impulses often easily retrogradely invade the sinoatrial node, causing early release of impulses and resetting the sinoatrial rhythm. Therefore, atrial premature contractions mostly show incomplete compensatory pause. Junctional and ventricular premature contractions are farther from the sinoatrial node and less likely to invade it, often showing complete compensatory pause.

III. Coupling Interval:

Refers to the time interval between the ectopic beat and the preceding sinus beat. The length of the coupling interval is influenced by the reentrant pathway and conduction velocity of the impulses. For atrial premature contractions, the coupling interval is measured from the onset of the ectopic P wave to the onset of the preceding sinus P wave. For ventricular premature contractions, it is measured from the onset of the ectopic QRS complex to the onset of the preceding sinus QRS complex.

III. Ventricular Premature Contraction Trigeminy

When two continuous premature ventricular QRS-T complexes appear after one basic heartbeat and this pattern repeats three times or more, it is called ventricular premature contraction trigeminy.

In ventricular premature contraction trigeminy, the first beat is usually sinus, but it can also be atrial, junctional, ventricular or pacing rhythm QRS-T complex. Clinically, monomorphic ventricular premature contraction trigeminy is more common (Figure 2).