His bundle has a shorter chronaxie than does the adjacent ventricular myocardium: Implications for pacemaker
Marek Jastrzębski1, Paweł Moskal1, Agnieszka Bednarek1
1First Department of Cardiology, Interventional Electrocardiology and Hypertension, Jagiellonian University Medical College, Krakow, Poland.
Heart Rhythm
|June 11, 2019
Summary
Strength-duration curves for His bundle (HB) pacing optimize pacemaker programming. Shorter pulse durations (0.2 ms) enhance selective HB capture and battery life, while longer durations (1.0 ms) ensure right ventricular capture.
Area of Science:
- Cardiovascular Electrophysiology
- Medical Device Technology
- Pacemaker Engineering
Background:
- Strength-duration curves are crucial for optimizing permanent His bundle (HB) pacing parameters.
- Understanding these curves aids in programming pacemakers for improved patient outcomes.
Purpose of the Study:
- To determine the strength-duration curves and chronaxies for His bundle (HB) and right ventricular (RV) pacing.
- To analyze selective HB capture zones and battery current drain at various pulse durations (PDs).
Main Methods:
- Strength-duration curves and chronaxies were assessed in 127 patients with permanent HB pacing.
- Capture thresholds for HB and RV were measured across multiple PDs.
- Battery current drain and selective HB capture were evaluated at PDs of 0.1, 0.2, 0.4, and 1.0 ms.
Main Results:
- His bundle (HB) chronaxie was significantly shorter than right ventricular (RV) chronaxie, particularly in selective HB pacing (0.47 ms vs. 0.79 ms).
- HB pacing exhibited a lower rheobase and an earlier steep portion on its strength-duration curve compared to RV.
- Lower battery current drain was observed at shorter PDs (0.1–0.4 ms) compared to 1.0 ms, with chronaxie-adjusted PDs yielding the lowest drain.
Conclusions:
- This study provides the first strength-duration curves for permanent selective and nonselective HB pacing.
- Shorter PDs (e.g., 0.2 ms) promote selective HB capture and enhance battery longevity.
- Longer PDs (e.g., 1.0 ms) provide a greater safety margin for RV capture, beneficial when simultaneous RV capture is desired.
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