Can Chest Roentgenogram Predict the Posture Dependent Changes of Atrial Sensing Performance in Patients with a VDD Pacemaker?

Abstract

The VDD pacemaker is useful for sequential pacing with a single lead but carries a risk of sensing failure. This study was designed to evaluate the relationship between the relative position of atrial lead and atrial sensitivity in different postures in patients with VDD pacemakers. Atrial sensitivity determination and chest roentgenography was performed in the supine and standing position 3 months after implantation in 25 patients with VDD pacemakers. Measurements of cardiac longitudinal length (from the top of the aortic arch to the diaphragm) and distances from the floating electrode to the upper margin of the seventh thoracic vertebra (D-T7), to the top of the aortic arch (D-knob), to the lateral wall of right atrium (D-wall), and the D-knob/cardiac longitudinal length (D-Ratio) were performed. Atrial signal amplitude decreased with the standing compared to the supine position in eight patients (group I) and increased or did not change in the other 17 patients (group II). In group I, the change of the D-ratio was greater (0.073 vs 0.035, P < 0.01), and the change of the cardiac longitudinal length with standing position was greater (18.4 +/- 7.3 vs 12.1 +/- 8.8 mm, P < 0.05) than in group II. The change of atrial sensitivity was related to the change of the atrial electrode position with different postures. Decreased atrial-sensed amplitude was observed in patients who had a greater change in the cardiac longitudinal length while standing. Thus, a decrease in atrial sensitivity with standing may be predicted by the positional changes of the cardiac silhouette on roentgenography before the procedure.

Long‐Term Stability and Clinical Utility of Amplified Atrial Electrograms in a Single‐Lead ICD System with Floating Atrial Electrodes

“…Another potential limitation is that P‐wave amplitude measurements were obtained at nighttime between 12 am and 2 am, most likely in a recumbent position. Previous studies using VDD pacemakers showed significant fluctuation of atrial signal with different body positions . However, a recent study using the DX ICD system found comparable range of atrial signal amplitude during various body postures …”

“…Previous studies using VDD pacemakers showed significant fluctuation of atrial signal with different body positions. 24,25 However, a recent study using the DX ICD system found comparable range of atrial signal amplitude during various body postures. 17…”

Optimal Side of Implant for Single‐Lead VDD Pacing: Right‐Sided Versus Left‐Sided Implantation

“…The reliability of this pacing system has been demonstrated in several studies 9,11,12,14,15 . However, due to a great variation of the atrial potential received by free‐floating electrodes 16 and instability of atrial dipole during changes in posture, 17,18 intermittent atrial undersensing remains a potential problem in single‐lead VDD pacing. Many studies have tried to define the predictors of long‐term failure of VDD pacing and to test the effects of new sensing algorithm and dipole design on the incidence of atrial undersensing 5,6 .…”

“…Many studies have tried to define the predictors of long-term failure of VDD pacing and to test the effects of new sensing algorithm and dipole design on the incidence of atrial undersensing. 5,6 Recently, Choi et al 17 suggested an interesting technique using chest x-ray for preimplant prediction of posture dependent changes in atrial sensing performance of VDD pacemaker. These efforts have somewhat been effective in the mainte-nance of proper VDD function, but atrial undersensing has persisted.…”

The Impact of the Distance between the Atrial Electrode and the Atrial Wall on Atrial Undersensing in Patients with VDD Pacemakers: Long‐Term Follow‐Up

“…16 On the other hand, other studies reported that atrial signal amplitudes varied significantly and unpredictably in different postures or maneuvers, even in the same individual. First, posteroanterior CXR gives information about only the position of atrial electrode relative to the lateral atrial wall.…”