Wolff-Parkinson-White syndrome

Question 1

What is WPW?

Answer 1

It is an electrical accessory pathway that connects the atria and ventricles.

This accessory pathway is called the Bundle of Kent - which can cause ventricular pre-excitation

Question 2

Differentiate Type A and Type B preexcitation

Answer 2

Left sided Bundle of Kent (i.e. LS ventricular pre excitation) = Type A (MORE COMMON)

Right sided Bundle of Kent (i.e. RS ventricular pre-excitation) = Type B

Question 3

What ECG findings will be present in someone with Wolff-Parkinson-White syndrome?

Answer 3

Short PR interval
Long QRS complex
Delta wave
T wave inversion

This WPW pattern doesn’t typically cause symptoms and is usually benign

Question 4

WPW pattern is usually benign. But sometimes it can facilitate certain arrhythmias - in which case it is called WPW syndrome. How can it cause cardiogenic shock?

Answer 4

Bundle of Kent means that any atrial arrhythmias are carried to the ventricles, which wouldn’t happen otherwise. e.g. if atrial bpm = 300, ventricular will also match 300.

300 is way too fast for ventricles so causes cardiogenic shock as ventricles don’t fill.

Question 5

WPW syndrome can cause cardiogenic shock. What else can it cause?

Answer 5

Reentry circuit - signal moves back up via the bundle of Kent

“Atrioventricular Reentrant Tachycardia (AVRT)” - atrium <=> ventricles

AVRT can lead to 200-300 ventricular bpm

Question 6

In AVRT, when the contraction starts at the atrium it is called orthodromic conduction. What about AVRT when the conduction starts at the ventricles?

Answer 6

AVRT with antidromic conduction

Question 7

How is WPW syndrome treated?

Answer 7

Pharmacological

Radiofrequency catheter ablation (used frequently)