ECG Case 92: Ventricular tachycardia (VT)

ECG Interpretation

  • Broad complex tachycardia at about 188/min
  • No P waves visible
  • Left axis deviation
  • QRS complex duration about 140 ms
  • Narrow fourth and fifth QRS complexes

Ventricular tachycardia (VT)
Ventricular tachycardia (VT)

Clinical Interpretation

Broad complex tachycardias may be ventricular, supraventricular with bundle branch block, or due to the Wolff–Parkinson–White syndrome.

We have no ECG from this patient recorded in sinus rhythm, which is always the most helpful thing in deciding between these possibilities.

The differential diagnosis of Wide Complex Tachycardia
The differential diagnosis of Wide Complex Tachycardia

The complexes are not very wide, which would be consistent with a supraventricular origin with aberrant conduction, but the left axis deviation and (probable) concordance point to ventricular tachycardia.

The key is the two narrow complexes near the beginning of the record: these are slightly early and are probably capture beats. They indicate that with an early supraventricular beat the conducting system can function normally; by implication, the broad complexes must be due to ventricular tachycardia.

Criteria for Discriminating Ventricular Tachycardia from SVT with Aberration
Criteria for Discriminating Ventricular Tachycardia from SVT with Aberration

What to do ?

An elderly patient with heart failure is more likely to have ischaemic disease than anything else, but all the possible causes of heart failure must be considered.

The sudden onset of an arrhythmia could be due to a myocardial infarction. Pulmonary emboli can cause sudden arrhythmias, though these are more often supraventricular than ventricular.

It is important to consider whether this rhythm change is related to treatment, in which case it could be due to an electrolyte imbalance or to the pro-arrhythmic effect of a drug the patient is taking.