Regular narrow complex tachycardia
Vagotonic manoeuvres, such as the Valsava manoeuvre or carotid sinus massage, should always be considered as first line treatment. Caution is required, however, as profound vagal tone may cause a sudden bradycardia and trigger ventricular fibrillation, particularly in the presence of acute ischaemia or digitalis toxicity. Carotid sinus massage may result in rupture of an atheromatous plaque and the possibility of a stroke.
The drug of choice for the initial treatment of regular supraventricular tachycardia is adenosine 6 mg by rapid bolus injection. If this is unsuccessful up to three further doses of 12 mg may be given, allowing one to two minutes between injections. If adenosine fails to convert the rhythm, then expert help should be sought and the patient checked carefully for the presence of adverse signs.
In the presence of one or more of these adverse signs treatment should consist of synchronised DC cardioversion after appropriate sedation. If this is unsuccessful a further attempt at cardioversion should be made after a slow intravenous injection and subsequent infusion of amiodarone. If circumstances permit, up to one hour should be allowed for the drug to exert its anti-arrhythmic effect before further attempts at cardioversion are made.
In the absence of adverse signs there is no single recommendation in the ERC Guidelines for the treatment of persistent narrow complex tachycardia because of the different traditions between European countries. The suggestions offered include a short acting P blocker (esmolol), a calcium channel blocking agent (verapamil), digoxin, or amiodarone. Verapamil is widely used in this situation, but it is important to remember that there are several contra-indications. These include arrhythmias associated with the Wolff-Parkinson-White syndrome, tachycardias that are, in fact, ventricular in origin, and some of the childhood supraventricular arrhythmias. A potentially serious interaction may occur between verapamil and P adrenergic blocking agents; this is particularly likely to happen if both drugs have been administered intravenously.
Narrow complex tachycardia
Pulseless (heart rate usually >250 beats/ minute)
Synchronised DC shock* 100J : 200J : 360J or appropriate biphasic energy
Narrow complex tachycardia
If not already done, give oxygen and establish intravenous (i.v.) access +
Vagal manoeuvres (caution if possible digitalis toxicity, acute ischaemia, or presence of carotoid bruit for carotoid sinus massage)
Adenosine 6 mg by rapid bolus injection; if unsuccessful, follow, if necessary, with up to 3 doses each of 12 mg every 1-2 minutes** Caution with adenosine in known Wolff-Parkinson-White syndrome iSeek expert help
Atrial fibrillation
Follow AF algorithm
Adverse signs?
- Systolic BP <90 mmHg
- Chest pain
- Heart failure
- Heart rate >200 beats/minute
Choose from:
- Esmolol: 40 mg i.v. over 1 minute+ infusion 4 mg/minute
(i.v. injection can be repeated and infusion increased incrementally to 12 mg/minute) OR
- Amiodarone: 300 mg i.v. over 1 hour, may be repeated once if necessary
- Digoxin: maximum dose 500 (ig i.v. over 30 minutes x 2
Doses throughout are based on an adult of average body weight A starting dose of 6 mg adenosine is currently outside the UK licence for this agent.
Synchronised DC shock* 100J : 200J : 360J or appropriate biphasic energy
If necessary, amiodarone 150 mg i.v. over 10 minutes, then 300 mg over 1 hour and repeat shock
DC shock always given under sedation/general anaesthesia. Not to be used in patients receiving ß blockers.
Theophylline and related compounds block the effect of adenosine. Patients on dipyridamile, carbamazepine, or with denervated hearts have a markedly exaggerated effect, which may be hazardous.
Algorithm for narrow complex tachycardia (presumed supraventricular tachycardia). Adapted from ALS Course Provider Manual. 4th ed. London: Resuscitation council (UK), 2000
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