ABSTRACT
UNLABELLED: To add data on controversy between the advantages and inconveniences of using either unipolar or bipolar modes for permanent cardiac pacing, we have studied 15 patients. In all of them a CPI Delta-925 (DDD) pulse generator was implanted. Non invasive pacing threshold values in volts were measured at 0.05, 0.08 and 0.1 ms for each chamber programmed either to unipolar or bipolar mode, at 1, 2, 3, 4, 5, 6, 7, 8, 14, 21, 30, 60, 90, 120, 180 and 365 days after the implant. Sensing thresholds were measured at the same time. For any pulse width the mean pacing thresholds in atrium and ventricle increase uniformly, reaching its maximum values between the days 8 and 14 after the implant and decreases to a stable value between 90 and 120 days after the implant, without statistically significant differences for both: unipolar and bipolar modes. Pacing thresholds (V +/- SD) for 0.05 ms in the day 365th were in atrium: unipolar 2.85 +/- 0.79, bipolar 3.35 +/- 0.92 (p = 0.56) and ventricle: unipolar 3.92 +/- 1.01, bipolar 4.36 +/- 1.35 (p = 0.58). Sensing thresholds in atrium and ventricle decreases from the 1st day after the implant with the minimum mean value the day 8th, increasing eventually. No statistically significant differences were found between sensing unipolar/bipolar mode at each chamber. Sensing thresholds (mV +/- SD) in the 365th day were in atrium: unipolar 4.40 +/- 2.07, bipolar 4.10 +/- 2.10 (p = 0.82) and ventricle: unipolar 11.20 +/- 3.63, bipolar 10.10 +/- 5.13 (p = 0.71). CONCLUSIONS: for every single patient: 1) There are not statistically significant differences in the evolution of unipolar and bipolar pacing thresholds both in atrium and ventricle, regarding rate and time of increase, maximum value, rate of decrease and stable chronic values. 2) There are neither statistically significant differences regarding unipolar and bipolar sensing in atrium and ventricle respect to rate of decrease, time and value of the minimum and stable chronic values.
