How does conduction system pacing affect the QRS complex in an ECG reading?

Conduction system pacing is designed to promote intrinsic conduction through the heart's specialized electrical pathways, particularly the His-Purkinje system. When this form of pacing is effectively implemented, the result is a narrower and more physiologically normal QRS complex on an ECG reading.

The rationale behind this is grounded in the fact that this type of pacing stimulates myocardial tissue in a way that mimics the natural conduction of electrical impulses through the heart. By pacing near or at the conduction system, the impulses travel down the normal conduction pathways, which facilitates efficient ventricular depolarization. This leads to a QRS complex that is narrower compared to traditional right ventricular pacing, where activation might occur through slower muscle pathways resulting in a wider QRS complex.

Additionally, a physiologically normal QRS complex indicates that the ventricles are depolarizing in a more synchronized manner, which is better aligned with healthy cardiac function. Thus, effective conduction system pacing enhances the overall quality of the electrical signal that is recorded on the ECG, promoting better cardiac efficiency and potentially improving patient outcomes.