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Radiographic assessment of atrial dipole position in single pass lead VDD and DDD pacing. The Multicenter Study Group
M G Bongiorni1, P V Moracchini, A Nava
1Cardiovascular and Pulmonary Department, University of Pisa, Italy.
Insights
Single-lead VDD pacing with Phymos leads shows stable atrial capture across various electrode positions. Optimal atrial electrode placement within the atrium maximizes pacing benefits and minimizes diaphragmatic stimulation for VDD patients.
Area of Science:
- Cardiology
- Biomedical Engineering
- Electrophysiology
Background:
- Single-lead VDD pacing is an option for atrioventricular block.
- Phymos leads and pacemakers are used for VDD pacing.
- Atrial electrode positioning is critical for pacing efficacy.
Purpose of the Study:
- To evaluate the impact of atrial electrode position on pacing performance in VDD pacing.
- To determine optimal positioning for Phymos lead atrial dipoles.
- To assess atrial capture and sensing with different electrode locations.
Main Methods:
- Radiographic analysis of atrial electrode position in 160 VDD-paced patients.
- Evaluation of Phymos single pass leads and Phymos 3D pacemakers.
- Assessment of atrial capture and diaphragmatic stimulation at various electrode positions (junctional area vs. atrium).
Main Results:
- Stable atrium-driven pacing was achieved regardless of electrode location (junctional area, inferior vena cava, or atrium).
- Atrial capture success rates were higher with electrodes in the junctional area compared to the atrium.
- Diaphragmatic stimulation was significantly lower when the electrode was positioned within the atrium.
Conclusions:
- While stable pacing is achievable, positioning the Phymos lead atrial dipole within the atrium is recommended.
- Optimal atrial electrode placement maximizes VDD pacing benefits and minimizes adverse effects like diaphragmatic stimulation.
- This positioning strategy can enhance the suitability of single-lead DDD pacing for more VDD patients.
Abstract:
Atrial electrode position was determined by radiographic analysis in 160 patients paced in single-lead VDD for second- or third-degree A-V block, implanted > 1 year with Phymos single pass leads and Phymos 3D pacemakers. The packing lead features an atrial dipole with a 30-mm electrode interspace. In 44% of patients, the upper atrial electrode was positioned within a band of 20 mm centered at the level of the superior vena caval insertion (junctional area) and was in the inferior vena cava or in the atrium in 35% and 21% of cases, respectively. In spite of these different dipole locations, all patients had stable atrium-driven pacing at routine follow-up visits. With the electrode in the junctional area, unipolar stimulation of up to 5 V for 1 ms resulted in stable atrial capture in 63% and 59% of the patients in supine and upright positions, respectively. With the electrode in the atrium, corresponding success rates were 45% and 54%. In the atrium, however, the prevalence of diaphragmatic stimulation was significantly lower than at the junction (10% vs 42% in supine position; 21% vs 47% upright). Though atrial sensing function proved adequate in a wide range of positions, these results suggest that the Phymos lead atrial dipole should be positioned within the atrium, as close as possible to the atrial wall, to maximize the number of VDD patients who might benefit from single-lead DDD pacing.