Regular wide qrs tachycardias

I47.0-2/I47.9

Regular wide QRS tachycardias are ventricular until proved otherwise.
Regular wide QRS supraventricular tachycardias are uncommon.
Refer all cases after resuscitation and stabilisation.
Emergency DC cardioversion is mandatory with a full protocol of Cardio-pulmonary resuscitation (CPR) if there is haemodynamic compromise.

GENERAL MEASURES

CPR if necessary.

If no cardiac arrest:

DC cardioversion, 200 J, after sedation with:

  • Midazolam, IV, 1–2.5 mg, administered over 2-3 minutes.
    • Monitor and repeat dose after 2-3 minutes, as necessary.
    • If 200 J fails, use 360 J.

LoEIII

If cardiac arrest:

Defibrillate (not synchronised).

MEDICINE TREATMENT

Caution

Never give verapamil or adenosine IV to patients with wide QRS tachycardia as this may precipitate ventricular fibrillation.

LoEIII [45]

DC cardioversion is preferred and safest first line therapy for regular wide QRS tachycardias. Medicines are needed if ventricular tachycardia (VT) recurs after cardioversion, or spontaneous termination.

LoEIII

If in doubt as to the nature of a tachycardia, and in all patients with haemodynamic compromise, DC cardioversion under IV sedation is the safest option.

DC cardioversion, 200 J, after sedation with:

  • Midazolam, IV, 1–2.5 mg, administered over 2-3 minutes.
    • Monitor and repeat dose after 2-3 minutes, as necessary.
    • If 200 J fails, use 360 J.

LoEIII

  • Amiodarone, IV, 5 mg/kg infused over 30 minutes.

Follow with:

  • Amiodarone, oral, 200 mg 8 hourly for 7 days.
    • Then, 200 mg 12 hourly for 7 days.
    • Maintenance dose: 200 mg daily for the minimum time required to control the arrhythmia
    • Consult specialist before instituting long-term (>1 week) therapy.

LoEIII [46]

Precautions:

  • If on warfarin, halve the dose of warfarin and monitor INR closely, until INR is stable.
  • Avoid concomitant digoxin.
  • Monitor thyroid function every 6 months for thyroid abnormalities.
  • Ophthalmological examination every 6 months.