Article Text
Abstract
Although serious adverse events following adenosine administration are rare, it should only be administered in an environment where continuous ECG monitoring and emergency resuscitation equipment are available. The case report describes the development of pre-excited atrial fibrillation in a 31-year-old woman with Wolff-Parkinson-White syndrome following the administration of adenosine. She had previously been fit and well and was admitted to the coronary care unit with a 2 h history of regular palpitations. A 12-lead ECG showed a narrow QRS complex tachycardia. Carotid sinus massage was unsuccessful in terminating the tachycardia and the patient subsequently received rapid boluses of intravenous adenosine. The cardiac rhythm degenerated into atrial fibrillation with ventricular pre-excitation following 12 mg adenosine.
Statistics from Altmetric.com
Although minor side effects such as flushing and chest discomfort are common, serious adverse events following the administration of adenosine are rare. A small proportion of patients (12%) may develop atrial fibrillation after adenosine injection. However, the accessory pathway in patients with Wolff-Parkinson-White (WPW) syndrome may have a short refractory period and thus be capable of fast atrioventricular conduction. This may precipitate life-threatening ventricular arrhythmias if there is rapid antegrade conduction of atrial fibrillation via the accessory pathway. The management of pre-excited atrial fibrillation requires cardioversion to sinus rhythm either chemically or electrically by DC cardioversion.
CASE REPORT
A 31-year-old woman who had previously been fit and well was admitted to the coronary care unit with a 2 h history of regular palpitations. This was of sudden onset, regular in nature and with no associated symptoms. The clinical examination was unremarkable apart from the tachycardia. A 12-lead ECG showed a narrow QRS complex tachycardia (fig 1). Electrical (QRS) alternans, a feature suggesting an accessory pathway and thereby differentiating AV re-entry tachycardia from AV nodal re-entry tachycardia, was noted in lead aVL.1
Carotid sinus massage was unsuccessful in terminating the tachycardia and the patient subsequently received rapid boluses of intravenous adenosine via a venflon in the antecubital fossa at doses of 3, 6 and 12 mg. Each dose was followed by a 10 ml saline flush. The first two doses were ineffectual but the cardiac rhythm degenerated into atrial fibrillation with ventricular pre-excitation following 12 mg adenosine (fig 2). Fortunately, the patient remained haemodynamically stable and was successfully cardioverted with intravenous flecanide. The post-cardioversion 12-lead ECG demonstrated the classical features of WPW syndrome with a short PR interval and a delta wave (fig 3).2 The patient was referred for electrophysiological studies with a view to radiofrequency ablation.
DISCUSSION
WPW syndrome can present with narrow complex tachycardias, pre-excited atrial fibrillation and, less commonly, ventricular fibrillation or sudden cardiac death. This case report describes the development of pre-excited atrial fibrillation in a patient with WPW syndrome following the administration of adenosine.
Adenosine is a short-acting anti-arrhythmic that slows conduction through the AV node and is commonly used to terminate narrow complex tachycardias. While minor side effects such as flushing and chest discomfort are common, serious adverse events following the administration of adenosine are rare. A small proportion of patients (12%) may develop atrial fibrillation after adenosine injection.3 The mechanism may involve either shortening of the atrial refractory period as well as the antegrade refractoriness of the accessory pathway or the induction of a surge in sympathetic stimulation.4 The effects are generally brief because of its short half-life. However, the accessory pathway in patients with WPW syndrome may have a short refractory period and thus be capable of fast atrioventricular conduction. This may precipitate life-threatening ventricular arrhythmias if there is rapid antegrade conduction of atrial fibrillation via the accessory pathway.
The management of pre-excited atrial fibrillation requires cardioversion to sinus rhythm either chemically with flecanide/propafenone or electrically by DC cardioversion. Although this patient was cardiovascularly stable which allowed chemical cardioversion, this case highlights the importance of administrating adenosine in an environment where both continuous ECG monitoring and emergency resuscitation equipment are available.
Footnotes
Competing interests: None.
Linked Articles
- Primary survey