Dependence of atrial sensing function on posture in a single-lead atrial triggered ventricular (VDD) pacemaker.
The influence of body posture on atrial sensing was examined in a single-lead VDD pacemaker in 16 patients. At implantation, a position was searched for the floating atrial bipolar sensor to obtain an adequate atrial signal amplitude. After 1-12 months the atrial signals were measured by programming the sensitivity in five postures: supine, sitting, and standing and lying on the right and left sides. The group mean amplitudes of the atrial signal were equal in all postures, and comparable to the supine value (1.01 +/- 0.51 mV). However, the values within each individual varied considerably according to position, by a range of 0.46 +/- 0.41 mV on average. Testing only supine did not always predict decent sensing when upright, e.g., in 3 patients the atrial signal decreased more than 0.5 mV. In 24-hour ambulatory electrocardiography, with the sensitivity (0.15-0.30 mV) set to cover all postures, atrial beats were undersensed not at all in 4 patients, < 0.01% in 6 patients, and < 0.1% in the remaining 6 patients. Thus, with a floating atrial electrode, sensitivity testing in various postures is advisable to ascertain proper sensing function.
Toivonen
L
L
Department of Medicine, Helsinki University Central Hospital, Finland.
Lommi
J
J
D000368:Aged; D000369:Aged, 80 and over; D015716:Electrocardiography, Ambulatory; D004867:Equipment Design; D006325:Heart Atria; D006327:Heart Block / Q000628:therapy; D006801:Humans; D008875:Middle Aged; D010138:Pacemaker, Artificial; D011187:Posture / Q000502:physiology*