title: Toward optimizing a preshaped catheter and system parameters to achieve single lead DDD pacing.
abstract: P wave electrogram amplitudes and atrial stimulation thresholds were determined in eight Hanford miniature swine using a preshaped catheter with an "S" curve in the SVC, and a major lobe in the atrium to enhance electrode contact with the atrial wall. The catheter was designed for pacing and sensing in the DDD mode. P wave amplitudes were also ascertained with two commercially available VDD leads and compared to the data from the experimental catheters. The preshaped catheter used two 6-mm2 platinum iridium atrial electrodes with a 7-mm separation. Both atrial electrodes are on the same side of the catheter, facing outward on the major atrial lobe formed in the catheter. The P wave amplitudes were tested only in the differential bipolar configuration. For the eight preshaped catheters, the mean was 6.6 +/- 3.8 mV while for the conventional leads it was 2.9 +/- 1.6 mV. The mean atrial stimulation thresholds ranged from 1.1 +/- 0.2 V to 2.3 +/- 1.2 V, with still lower thresholds of 0.9-1.3 V when using the parallel unipolar atrial electrode configuration, in which both parts of the bipolar atrial electrode are configured as a unipolar electrode. The data suggest that bipolar simulation may be effective if sequential reverse polarity pulses are used to achieve cathodal stimulation from each electrode of the bipolar pair, on a beat-to-beat basis.
authors.affiliation: Cardiac Control Systems, Palm Coast, FL 32164, USA.
authors.forename: R R
authors.initials: RR
authors.lastname: Brownlee
authors.forename: M M
authors.initials: MM
authors.lastname: Swindle
authors.forename: R
authors.initials: R
authors.lastname: Bertolet
authors.forename: P
authors.initials: P
authors.lastname: Neff
mesh_terms: D000818:Animals; D002408:Catheters, Indwelling; D004566:Electrodes; D004867:Equipment Design; D010138:Pacemaker, Artificial; D013552:Swine; D013556:Swine, Miniature