Quiz: Loss of Consciousness After Sex

History
A 32-year-old man presents to the emergency department for a syncopal episode that occurred while standing and waiting to use the bathroom about 2 minutes after having sexual relations with his spouse. She was sitting on the toilet with the door ajar and saw him lose consciousness and fall. There was both incontinence of urine and “shaking” that the wife thinks was a seizure.

The patient denies any injury, headache, chest pain, palpitations, or other complaints. He has no history of seizure or fainting and is otherwise healthy and takes no medications.

Examination
Vital signs including temperature were normal. Head and neck exam showed no evidence of trauma or tongue biting. The lungs were clear and the heart regular with normal valvular sounds. The rest of his physical exam including a thorough neurologic exam was normal.

Initial Concerns
-- Vasovagal episode
-- Seizure
-- Dysrhythmia

TestingLaboratory studies: CBC and chemistry including magnesium were all within normal limits.

ECG: Tracing shown below in Figure 1. It was read by the computer as atrial fibrillation.

Do you agree with the computer read?  No. The ECG shows a short PR interval, not atrial fibrillation.  

Do you note other ECG findings? Yes. A delta wave in lead V3.

Discussion
Wolff-Parkinson-White (WPW) syndrome is a condition where there is an electrical tract from the atria to the ventricles that bypasses the AV node and its built-in delay. This shows up as a short P interval in all leads on the EKG along with a delta wave, which may only be present in one or two leads. Patients with WPW are typically asymptomatic but are at significant risk of developing paroxysmal SVT or atrial fibrillation.

The most common cause of a short PR interval without a delta wave in an otherwise healthy patient is a normal finding due to intact AV node conduction via the fast pathway. Pathologic conditions that can cause a short PR interval are listed in the highlighted area of the page shot in Figure 2 (below).   

SVT or other narrow QRS complex tachycardias are treated exactly as they would be in a patient without WPW; AV nodal blockers are safe to use. Wide QRS tachycardias, however, should be treated with procainamide or synchronized cardioversion as AV nodal blockers in this situation can block the AV node and lead to all of the beat being transmitted to the bypass tract. Since there is no delay with the bypass tract there is the potential for heart rates of up to 300 beats/min, which does not allow adequate time for ventricular filling and thus hypotension and death may occur.

Definitive treatment of WPW is elective ablation by an electrophysiologist.|
 

EKG changes in WOLFF-PARKINSON-WHITE SYNDROME from the Emergency Medicine 1-minute consult pocketbook

Figure 2.