Mon25October0844PM 15

A 34-year-old woman with a two hour history of palpitations presents to the Emergency department. There is no history of chest pain, syncope or breathlessness.

On examination her blood pressure is 130/80 mmHg and heart rate 215 beats per minute. An ECG shows a narrow complex AV nodal re-entry tachycardia with a rate of 230 beats per minute.

What is the single most appropriate pharmacological treatment of this arrhythmia?

(Please select 1 option)

Adenosine This is the correct answer

Amiodarone

Digoxin

Verapamil Incorrect answer selected

Propranolol

Explanation

In the absence of adverse features (that is, heart failure, chest pain, hypotension and reduced level of consciousness) carotid sinus massage or a Valsalva manoeuvre may terminate the arrhythmia whilst adenosine is being drawn up.

The adult doses are 6 mg by rapid intravenous injection, then 12 mg if the initial dose is ineffective. This can then be followed by a further 12 mg if termination of the arrhythmia is not effected by the second dose.

Regular narrow complex tachycardias include:

Sinus tachycardia

AV nodal re-entry tachycardias (AVNRT)

AV re-entry tachycardia (ANRT)

Atrial flutter with regular AV conduction.

Vagal manoeuvres and adenosine will terminate most AVNRT and AVRT arrhythmias.

Verapamil 2.5-5 mg intravenously can be considered if adenosine is contraindicated.

Beta-blockers and digoxin are indicated in narrow complex irregular tachycardias.

Amiodarone is not a first-line anti-arrhythmic for AVNRT or AVRT.

Reference:

Resuscitation Council (UK). Peri-arrest arrhythmias.

Answer Statistics

1

86%

2

7%

3

1%

4

5%

5

2%

Times answered: 269