Alternative site pacing: accessing normal precordial activation: is it possible?

Area of Science:

• Cardiology
• Biomedical Engineering
• Electrophysiology

Background:

• Traditional right ventricular (RV) apex pacing for symptomatic bradycardia can cause mechanical desynchronization and adverse effects, particularly in heart failure patients.
• Alternative pacing sites aim to preserve normal ventricular activation, but face challenges like technical difficulties (e.g., His bundle pacing) and inconclusive results for RV septum/outflow tract.
• Limitations include inconsistent electrode deployment, undefined pacing regions, and lack of electrical measures to confirm optimal lead placement for desired ventricular activation.

Purpose of the Study:

• To explore alternative pacemaker pacing sites to improve outcomes by preserving normal ventricular activation.
• To investigate methods for identifying optimal pacing sites that avoid adverse effects of RV apical pacing.
• To enhance the selection of pacing sites through individualized assessment of biventricular activation effects.

Main Methods:

• Review of existing literature on pacemaker pacing sites, including RV apex, His bundle, RV septum, and RV outflow tract.
• Analysis of limitations in current pacing trials, such as electrode deployment inconsistency and lack of electrical guidance for lead positioning.
• Discussion of advanced mapping techniques like electrocardiographic imaging for detailed biventricular activation assessment.

Main Results:

• Pooled trial results suggest benefits from alternative pacing sites, especially in patients with left ventricular (LV) dysfunction, with benefits accruing over time.
• RV apical pacing can induce interventricular dyssynchrony affecting pump function, effects not always evident on surface QRS.
• Optimal pacing site location may be variable and require identification by its electrical effect to guide accurate electrode deployment.

Conclusions:

• Individualized pacemaker pacing site selection based on detailed biventricular activation effects holds promise for enhancing patient outcomes.
• Avoiding delayed transseptal activation and achieving rapid LV depolarization are key goals for alternate site pacing.
• Further research into non-invasive mapping techniques can refine pacing strategies and improve the management of bradycardia and heart failure.