Which type of WPW is associated with a higher risk of ventricular fibrillation?

In the context of Wolff-Parkinson-White (WPW) syndrome, the antidromic type is associated with a higher risk of ventricular fibrillation due to the manner in which the electrical impulses travel through the heart.

Antidromic WPW involves a conduction pathway where the impulse travels down the accessory pathway rather than through the normal conduction system, resulting in a wide QRS complex. This can lead to reentrant tachycardias that can include ventricular fibrillation if the heart's electrical impulses become chaotic and disorganized. The risk is further elevated because the abnormal conduction can predispose the patient to more severe forms of arrhythmias.

In contrast, orthodromic WPW typically involves impulses traveling antegrade through the AV node and down the normal His-Purkinje system, resulting in a narrow QRS complex during tachycardia. This means that while orthodromic pathways can lead to tachyarrhythmias, they are generally less likely to cause life-threatening arrhythmias like ventricular fibrillation compared to the antidromic pathway.

Thus, understanding the mechanisms behind antidromic conduction and its propensity for leading to more dangerous arrhythmic events clarifies why this type poses a greater risk.