Efficacy and Safety of Bipolar Sensing with High Atrial Sensitivity in Dual Chamber Pacemakers

Abstract

In dual chamber pacemakers, atrial sensing performance is decisive for maintenance of AV synchrony. Particularly, the efficacy of mode switching algorithms during intermittent atrial tachyarrhythmias depends on the sensitive detection of low potential amplitudes. Therefore, a high atrial sensitivity of 0.18 mV, commonly used in single lead VDD pacemakers, was investigated for its efficacy and safety in DDD pacing. Thirty patients received dual chamber pacemakers and bipolar atrial screw-in leads for sinus node syndrome or AV block; 15 patients suffered from intermittent atrial fibrillation. Pace makers were programmed to an atrial sensitivity of 0.18 mV. Two weeks, 3, 9, and 15 months after implantation, P wave sensing threshold and T wave oversensing thresholds for the native and paced T wave were determined. The myopotential oversensing thresholds were evaluated by isometric contraction of the pectoral muscles. Automatic mode switch to DDIR pacing was activated when the mean atrial rate exceeded 180 beats/min. The patients were followed by 24-hour Holter monitoring. Two weeks after implantation, mean atrial sensing threshold was 1.81 +/- 0.85 mV (range 0.25-2.8 mV) without significant differences during further follow-up. Native T wave sensing threshold was < 0.18 mV in all patients. In 13% of patients, paced T waves were perceived in the atrial channel at the highest sensitivity. This T wave sensing could easily be avoided by programming a postventricular atrial refractory period exceeding 300 ms. Myopotential oversensing could not be provoked and Holter records showed no signs of sensing dysfunction. During a 15-month follow-up, 1,191 mode switch events were counted by autodiagnostic pacemaker function. Forty-two of these events occurred during Holter monitoring. Unjustified mode switch was not observed. In DDD pacemakers, bipolar atrial sensing with a very high sensitivity is efficient and safe. Using these sensitivity settings, activation of the mode switch algorithm almost completely avoids fast transmission of atrial rate to the ventricle during atrial fibrillation.

VDD pacing in dogs: When, why and how to perform single-lead atrial synchronous, ventricular inhibited (VDD) pacing

“…0.18 mV, and extend the atrial refractory period to avoid oversensing of far-field QRS complexes or ventriculoatrial conduction. 27 …”

Atrial Near‐Field and Ventricular Far‐Field Analysis by Automated Signal Processing at Rest and During Exercise

“…A single pacemaker device type was chosen to exclude the influence of different sense amplifiers and filters on the study result. Measurements were performed 7 ± 3 months (range [3][4][5][6][7][8][9][10][11][12][13][14] after implantation of the device and pacing leads. Patient age was 66 ± 10 years, 79% of patients were male.…”

“…Our study supports previous findings that a bipolar configuration is superior in rejecting ventricular far fields depending on the programmed sensitivity. 1,3,10,14 …”

“…3,10,18 This has been explained by degenerative changes in the atrial myocardium. Moreover, prolongation of the atrial activation has been shown during pacing in signal-averaged electrocardiograms of the P wave.…”

“…[1][2][3]4,6 Several investigators have also reported a decrease of atrial signal amplitude during exercise. [7][8][9] This, however, is not confirmed by more recent data.…”