The Annals of Thoracic Surgery, Vol 57, 623-626, Copyright © 1994 by The Society of Thoracic Surgeons
Pacing thresholds of temporary epicardial electrodes: variation with electrode type, time, and epicardial position
P Kallis, N Batrick, F Bindi, G Mascaro, A Chatzis, BE Keogh, DJ Parker and T Treasure
Cardiothoracic Unit, St. George's Hospital, London, England.
We compared the variation in pacing thresholds of two widely used temporary
pacing electrodes at different epicardial sites in 67 patients after
coronary artery operations performed with either cardioplegia or
ventricular fibrillation. In 33 patients, a bare, braided pacing wire (DW)
was placed on the right ventricle and a Medtronic localized epicardial
electrode (MED), on each ventricle. In the other 34 patients, the DW wire
was placed on the right atrium and a MED electrode, on each atrium. Pacing
thresholds were measured at the time of placement; at 1 hour, 6 hours, and
12 hours postoperatively; and daily for 4 days. The pacing thresholds (mean
+/- standard error of the mean) at implantation were as follows: DW wire =
0.93 +/- 0.08 V and MED electrode = 0.63 +/- 0.1 V in the ventricles and DW
= 1.28 +/- 0.18 V and MED = 0.65 +/- 0.09 V in the atria. On the fourth
postoperative day, the pacing thresholds were DW = 2.08 +/- 0.21 V and MED
= 1.19 +/- 0.22 V in the ventricles and DW = 2.33 +/- 0.29 V and MED = 1.04
+/- 0.09 V in the atria. The pacing thresholds of both types of wire
increased significantly over time, but this deterioration was more
pronounced with the braided wire both on the ventricle and on the atrium.
The pacing threshold patterns were not affected by chamber side or mode of
myocardial preservation. The braided ventricular wire failed to capture
after 24 hours in 9 of 30 patients, whereas the localized epicardial
electrode captured in all instances (p < 0.001).(ABSTRACT TRUNCATED AT
250 WORDS)
