Temporary transvenous cardiac pacing requires technical expertise and
access to fluoroscopy. We have developed a gastroesophageal electrode
capable of atrial and ventricular pacing. The flexible polythene gastr
oesophageal electrode is passed into the stomach under light sedation.
Five ring electrodes, now positioned in the lower esophagus, are used
for atrial pacing. A point source (cathode on the distal tip of the e
lectrode, now positioned in the gastric fundus, is used for ventricula
r pacing. Two configurations of atrial and ventricular pacing were com
pared: unipolar and bipolar. During unipolar ventricular pacing the in
different electrode (anode) was a high impedance chest pad. For bipola
r ventricular pacing the indifferent electrode was a ring electrode pl
aced 2 cm proximal to the tip. Unipolar atrial pacing nas performed wi
th 1 of 5 proximal ring electrodes acting as cathode (''cathodic'') or
as anode (''anodic'') in conjunction with a chest pad. Bipolar atrial
pacing was performed using combinations of 2 of 5 ring electrodes. At
rial capture was obtained in all 55 subjects attempted. When all elect
rode combinations were compared, atrial capture was significantly more
frequent using the bipolar approach (153/210 bipolar, 65/210 unipolar
; t = 7.37, P < 0.001). For unipolar atrial pacing cathodic stimulatio
n (from esophagus) was more successful than anodic stimulation (cathod
ic 62/105, anodic 20/105; t = 5.81, P < 0.001). In 43 subjects attempt
ed unipolar ventricular pacing resulted in a higher frequency of captu
re than the bipolar approach (unipolar 41/43 (95.3%), bipolar 19/43 (4
4.2%); P < 0.001). In conclusion, atrial pacing was optimal using pair
s of ring electrodes (''bipolar'') while ventricular pacing was optima
l using the distal electrode tip (cathode) in conjunction with a chest
pad electrode (''unipolar''). This gastroesophageal electrode may be
useful in the emergency management of acute bradyarrhythmias and for e
lective electrophysiological studies.