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Electrical characteristics of a split cathodal pacing configuration.
Marc W Mayhew1, Jane E Slabaugh, Rosemary S Bubien
1Department of Medicine, University of Alabama at Birmingham, Birmingham, Alabama 35294, USA.
Pacing and Clinical Electrophysiology : PACE
|December 17, 2003
Summary
Biventricular pacing using split cathodal configurations significantly increases stimulation thresholds for both left (LV) and right ventricles (RV). This suggests separate LV and RV output circuits are needed for effective cardiac resynchronization therapy.
Area of Science:
- Cardiology
- Biomedical Engineering
- Electrophysiology
Background:
- Biventricular pacing is crucial for cardiac resynchronization therapy in patients with heart failure and left bundle branch block.
- Current commercial systems often use a parallel circuit with linked electrodes for RV and LV stimulation, impacting current distribution based on lead impedances.
Purpose of the Study:
- To evaluate the impact of different electrical configurations, including split cathodal stimulation, on stimulation thresholds and impedances for biventricular pacing.
- To compare stimulation parameters between unipolar and bipolar configurations, and between individual chamber stimulation and split cathodal configurations.
Main Methods:
- Nineteen patients with left bundle branch block and congestive heart failure underwent implantation of cardiac venous and RV pacing leads.
- Stimulation thresholds and impedances were measured for RV and LV in five configurations: unipolar LV, bipolar LV, bipolar RV, unipolar split cathodal, and bipolar split cathodal.
- Measurements were repeated at 1-year follow-up to assess long-term effects.
Main Results:
- Split cathodal configurations significantly increased LV stimulation thresholds compared to individual chamber stimulation (unipolar: 0.7V to 1.0V, P=0.01; bipolar: 1.0V to 1.3V, P<0.001).
- RV stimulation thresholds also increased with split cathodal configurations (bipolar: 0.3V to 0.5V, P=0.005).
- At 1-year follow-up, split cathodal configurations maintained significantly higher LV and RV stimulation thresholds compared to baseline individual chamber stimulation.
Conclusions:
- The split cathodal configuration, whether unipolar or bipolar, significantly elevates apparent stimulation thresholds for both LV and RV.
- Programming to a bipolar split cathodal configuration further increases these thresholds.
- These findings support the development of pacing systems with independent LV and RV output circuits for optimized cardiac resynchronization therapy.