PVC couplet EKG strip

How to identify a PVC couplet 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

   That of the underlying rhythm; count all the complexes for the strip rate.

   ~70 bpm

2. 2Rhythm

   Regular, then two early beats close together, then a pause.

   Regular, with two early beats in a row

3. 3P waves

   Normal on the sinus beats; none in front of either PVC.

   None on the early beats

4. 4PR interval

   Normal on the sinus beats.

   0.17 s on sinus beats

5. 5QRS

   Narrow on the sinus beats; both beats of the pair are 0.12 s or wider.

   0.07 s; early beats 0.17 s

What is happening in the heart

A focus in the ventricle fires twice in quick succession before the SA node regains control. Each impulse spreads slowly through the ventricular muscle, so each complex is wide. Firing twice instead of once shows that the focus is more irritable, or that a small circuit in the ventricle has completed two laps.

More PVC couplet strips: no two are the same

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

What a PVC couplet gets mistaken for

PVC couplet vs. premature ventricular contractions (PVCs)

A single PVC stands alone between normal beats. In a couplet the second wide beat follows the first directly.

PVC couplet vs. ventricular triplet (three PVCs in a row)

Count the wide beats in the run. Two is a couplet. Three is a triplet, which already meets the definition of ventricular tachycardia.

PVC couplet vs. ventricular bigeminy

Bigeminy also has many wide beats, but each one is separated from the next by a normal beat. In a couplet the two wide beats touch.

Causes of a PVC couplet

• Myocardial ischemia or infarction
• Low potassium or low magnesium
• Hypoxia
• Cardiomyopathy and heart failure
• Medication that lengthens the QT interval
• Stimulants

Why it matters

A couplet is one step along the road from isolated PVCs to ventricular tachycardia. On its own it rarely causes symptoms, but it shows that the ventricle can sustain more than one abnormal beat, and couplets that become frequent often precede longer runs.

What is done for a PVC couplet

• Assess the patient and vital signs.
• Print and save the strip; note how often pairs occur.
• Review potassium, magnesium and oxygen saturation.
• Notify the provider of new couplets, particularly after a heart attack or with a long QT.
• Watch for longer runs.

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

Common mistakes with a PVC couplet

• Counting a couplet as two separate PVCs and under-reporting it.
• Missing the second beat because it is partly buried in the T wave of the first.
• Calling a pair a run of ventricular tachycardia; that term starts at three.

Questions about a PVC couplet