Pre-excited Atrial Fibrillation After Drawing Blood


A 33-year-old man presented to the emergency department with complaints of palpitations after he passed out while getting his blood drawn.

A 33-year-old man presented to the emergency department with complaints of palpitations after he had passed out while getting a blood sample . On examination, the patient had tachycardia with a heart rate of 192 beats/minute and irregular rhythm.

The patient was advised an electrocardiogram which showed no P waves, irregular RR intervals and delta waves and wide-complex tachycardia. The findings were suggestive of the differential diagnosis of atrial fibrillation. The patient was administered 1 g of intravenous procainamide and electrocardiogram was repeated, which showed wide delta waves and QRS complex with short PR interval sinus rhythm. The findings were suggestive of Wolff-Parkinson-White syndrome.

The Wolff-Parkinson-White pattern

The Wolff-Parkinson-White pattern is evident in patients with atrioventricular node, in addition to an accessory conduction pathway between the atria and ventricles. The ventricular myocardium preexcites when the accessory pathway is favoured over the atrioventricular node. This usually occurs with atrial fibrillation or if in case of use of medications that block the conduction of atrioventricular node. Both cases can be potentially life-threatening and can trigger ventricular fibrillation.

In case of this 33-year-old man, an electrophysiological study showed right paraseptal accessory pathway anterior to the coronary-sinus ostium, which was successfully treated with radiofrequency ablation.

Atrial fibrillation can be lethal!

Atrial fibrillation can become potentially lethal in the presence of pre-excitation as the ventricular activation can result in ventricular fibrillation. In addition, atrial fibrillation can cause chaos and result in multiple impulses bombarding the atrioventricular conduction system. Radiofrequency ablation is an effective treatment for such patients.

The patient showed no further palpitations, neither were any episodes of pre-excited atrial fibrillation seen in the following 18 months.


McNamara, D. A., & Patel, N. (2020). Preexcited Atrial Fibrillation after a Blood Draw. The New England Journal of Medicine382(13), e22-e22.

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Dr. Aiman Shahab is a dentist with a bachelor’s degree from Dow University of Health Sciences. She is an experienced freelance writer with a demonstrated history of working in the health industry. Skilled in general dentistry, she is currently working as an associate dentist at a private dental clinic in Karachi, freelance content writer and as a part time science instructor with Little Medical School. She has also been an ambassador for PDC in the past from the year 2016 – 2018, and her responsibilities included acting as a representative and volunteer for PDC with an intention to make the dental community of Pakistan more connected and to work for benefiting the underprivileged. When she’s not working, you’ll either find her reading or aimlessly walking around for the sake of exploring. Her future plans include getting a master’s degree in maxillofacial and oral surgery, settled in a metropolitan city of North America.


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