Ventricular trigeminy EKG strip

How to identify ventricular trigeminy in five steps

Ask the same five questions of every strip. The right-hand column is what each one finds on the strip above.

1. 1Rate

   Use the 6-second count, and include the wide beats in it. Expect the palpable pulse to be lower.

   ~70 bpm

2. 2Rhythm

   Irregular in a fixed pattern of three: normal interval, short interval, long interval.

   Irregular, in threes

3. 3P waves

   Before each of the two narrow beats. None before the wide beat.

   None on every third beat

4. 4PR interval

   Normal and equal on the narrow beats.

   0.16 s on sinus beats

5. 5QRS

   Narrow, narrow, wide (0.12 s or more), repeating.

   0.08 s, 0.08 s, then 0.15 s

What is happening in the heart

An irritable spot in the ventricle fires after every second normal beat. The pause that follows each PVC resets the timing, two sinus beats pass, and the spot fires again. The naming follows the count of beats in each repeating group: two is bigeminy, three is trigeminy, four is quadrigeminy.

More ventricular trigeminy strips: no two are the same

A rhythm is a set of rules, not a picture. These three strips all meet the rules for ventricular trigeminy, with different numbers.

What ventricular trigeminy gets mistaken for

Ventricular trigeminy vs. ventricular bigeminy

Count the narrow beats between two PVCs. One narrow beat between them is bigeminy; two is trigeminy.

Ventricular trigeminy vs. premature ventricular contractions (PVCs)

Occasional PVCs have no fixed spacing, with three or more normal beats between them. Trigeminy keeps strict time: every third beat, all the way across.

Ventricular trigeminy vs. second-degree AV block, type I (Wenckebach)

Wenckebach with 3:2 conduction also shows beats in small groups with pauses. All of its QRS complexes are narrow and each has a P wave, and its pause contains a P wave. In trigeminy the last beat of each group is wide and has no P wave.

Causes of ventricular trigeminy

• Low potassium or magnesium
• Reduced blood flow to the heart muscle
• Low oxygen levels
• Stimulants such as caffeine and decongestants
• Heart failure
• Digoxin toxicity

Why it matters

One beat in three is a PVC, which counts as frequent ventricular ectopy. Each PVC may be too weak to feel at the wrist, so the pulse can be about two thirds of the rate on the monitor. Sustained trigeminy tells you the ventricle is irritable and that something is provoking it.

What is done for ventricular trigeminy

• Feel a pulse for a full minute and compare it with the monitor.
• Assess for dizziness, chest discomfort or low blood pressure.
• Look at recent potassium and magnesium results and the oxygen saturation.
• Report trigeminy that is new, with a strip.
• Expect the cause to be treated; the pattern usually settles when it is.

Study summary, not a protocol. Follow current American Heart Association guidelines and your facility’s policies. See the medical disclaimer.

Common mistakes with ventricular trigeminy

• Miscounting the group and calling it bigeminy.
• Reporting the monitor’s number as the heart rate without confirming how many beats produce a pulse.
• Reading the grouped beats as a second-degree block without looking at the QRS width.

Questions about ventricular trigeminy