Electrical delays in quadripolar leads with cardiac resynchronization therapy
Scott M Koerber1, Michael E Field1, Daniel B Cobb1
1Division of Cardiology, Medical University of South Carolina, Charleston, South Carolina, USA.
Journal of Cardiovascular Electrophysiology
|July 10, 2021
Summary
Quadripolar leads in cardiac resynchronization therapy (CRT) allow optimizing pacing sites. Electrical delay measurements, like QLV and RV-LV intervals, differ between bipoles, especially in patients with left bundle branch block (LBBB).
Area of Science:
- Cardiology
- Electrophysiology
- Medical Devices
Background:
- Pacing sites for improved cardiac resynchronization therapy (CRT) outcomes include late intraventricular activation (QLV) and long interventricular conduction (RV-LV).
- Quadripolar leads offer electrical repositioning to optimize CRT pacing, but their impact on electrical delay is not well understood.
Purpose of the Study:
- To determine the relationship between different electrical bipoles from a quadripolar lead and measures of electrical delay.
Main Methods:
- Forty-six patients undergoing CRT with a quadripolar lead were analyzed.
- RV-LV and QLV intervals were measured using proximal and distal bipoles, with differences (Δ) calculated.
- Multivariate analyses identified predictors of electrical delays.
Main Results:
- In patients with left bundle branch block (LBBB), ΔQLV and ΔRV-LV were significant and strongly correlated (R² = 0.92).
- In non-LBBB patients, only ΔRV-LV was significant (mean: 7.2 ms), with weak correlation between ΔRV-LV and ΔQLV (R² = 0.06).
- Gender and LBBB status were significant predictors of ΔQLV.
Conclusions:
- In LBBB patients, the strong correlation between ΔRV-LV and ΔQLV suggests selecting proximal bipole/basal LV pacing sites.
- In non-LBBB patients, pacing site individualization is recommended due to greater activation pattern variation.
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