r tachycardia can be made.
- If there is no RS complex in any chest lead (V1–V6) a diagnosis of ventricular tachycardia can be made. Otherwise, continue to next criteria.
- Assess the RS interval (interval from start of the R-wave to the nadir of the S-wave). If any RS interval is >100 ms and the R-wave is wider than the S-wave, a diagnosis of ventricular tachycardia can be made. Otherwise, continue to next criteria.
- If there is AV dissociation, a diagnosis of ventricular tachycardia can be made. Otherwise, continue to next criteria.
- Assess the QRS morphology in V1, V2, V5 and V6 (see below). If the QRS morphology is compatible with ventricular tachycardia, then the diagnosis is ventricular tachycardia.
- If no criteria have been fulfilled, a diagnosis of supraventricular tachycardia can be made.
Judging the QRS morphology (criteria #4 in Brugada’s algorithm)
If the QRS complex in V1–V2 resembles a right bundle branch block (i.e positive QRS)
- Monophasic R complex suggests ventricular tachycardia.
- qR complex suggests ventricular tachycardia.
- if R is taller than R’, ventricular tachycardia is suggested.
- Triphasic complexes (rSr’, rsr’, rSR’, rsR’) suggests SVT
- rS, QS, R or Rs complex suggests VT.
If the QRS complex in V1–V2 resembles a left bundle branch block (i.e negative QRS)
- The initial portion of the QRS complex is smooth in ventricular tachycardia. SVT has a sharp start of the QRS complex.
- R-wave duration ≥40 ms suggest ventricular tachycardia.
- Duration from start of QRS complex to nadir of S-wave ≥60 ms suggests ventricular tachycardia.
- QR or QS complex suggest ventricular tachycardia.
- R or RR complex without initial q-wave suggests SVT.
All in all, Brugada’s criteria have very high sensitivity (90%) and specificity (60–90%) for diagnosing ventricular tachycardia.
Brugada’s algorithm for differentiating ventricular tachycardia from antidromic AVRT
The algorithm above frequently fails to differentiate ventricular tachycardia from antidromic AVRT. Although antidromic AVRT is an uncommon cause of ventricular tachycardia, it is important to be able to differentiate these entities. The older the patient and the more significant the heart disease, the more likely is ventricular tachycardia. The Brugada group has also developed an algorithm to differentiate antidromic AVRT from ventricular tachycardia. The algorithm follows:
Brugada’s algorithm for differentiating ventricular tachycardia and antidromic AVRT
- If the QRS complex is net negative in V4–V6, ventricular tachycardia is more likely.
- If the QRS complex is net positive in V4–V6 and any of the leads V2–V6 display a qR complex, ventricular tachycardia is very likely.
- If there is AV dissociation, ventricular tachycardia is very likely.
- If there are no signs of ventricular tachycardia, antidromic AVRT should be strongly considered.
Management of ventricular tachycardia
Treatment in the emergency setting
Unconscious patients: start cardiopulmonary resuscitation.
Hemodynamically unstable patients (hypotension, angina, heart failure, shock, pre-syncope/syncope): the patient should be treated immediately with electrical cardioversion (during anesthesia). Ventricular tachycardia can be terminated already at 20–50 J biphasic shock. Beta-blockers are administered intravenously, unless the patient has bradycardia induced ventricular tachycardia. In that scenario, amiodarone is to be preferred after cardioversion (amiodarone 50 mg/ml, 6 ml with 14 ml glucose 50 mg/ml, i.v during 2 min). Hypokalemia and hypomagnesaemia should be corrected rapidly. Causes underlying the ventricular tachycardia must be targeted; heart failure, ischemia, hypotension, hypokalemia etc can all be treated rapidly. Thumpversion (hitting the patient’s chest with a fist) is no longer recommended although it might terminate the tachcyardia in some cases.
Hemodynamically stable patients may be treated pharmacologically (amiodarone, lidocaine, sotalol, procainamide). Only one of these drugs are administered and a loading dose is followed by infusion. Amiodarone is the primary ch