Use of a multi-stage exercise test to assess the responsiveness of rate-adaptive pacemakers in dogs.
OBJECTIVE
To assess the ventricular rate response of rate-adaptive (VVIR) pacemakers in dogs using a multi-stage exercise test.


METHODS
The rate-responsiveness of VVIR pacemakers was assessed in seven dogs with complete atrioventricular (AV) block and implanted with various models of pulse generators (six motion sensors and one automatic dual-sensor rate-response pacemaker). Response activity was assessed with a multi-stage exercise test on a treadmill. Atrial and ventricular rate were analysed retrospectively at the end of the test and the AV ratio was calculated after each minute of exercise.


RESULTS
During exercise, the mean (sd) AV ratio recorded in all paced dogs was 1.7 (0.5) (expected physiological ratio 1.0), although a variety of individual performances was observed. A poor response (AV ratio 2.8 [0.2]) was obtained with the automatic dual-sensor pacemaker, suggesting that this type of rate-responsive device may not be indicated for implantation in dogs with complete AV block. The overall AV ratio for the six dogs implanted with motion sensors was 1.4 (0.2), showing a better performance of these pacemakers during exercise.


CONCLUSIONS
This multi-stage exercise test represents an easy and repeatable method for assessing the accuracy of rate-responsive sensors and offers valuable information for the correct setting of VVIR pacemakers in dogs.
Ferasin
L
L
University of Bristol, Department of Clinical Veterinary Science, Division of Companion Animals, Langford House, Langford, Bristol BS40 5DU.
Faena
M
M
Henderson
S M
SM
Langford
K
K
Darke
P G G
PG
D000818:Animals; D002304:Cardiac Pacing, Artificial / Q000379:methods / Q000662:veterinary*; D004283:Dog Diseases / Q000628:therapy*; D004285:Dogs / Q000502:physiology*; D005080:Exercise Test / Q000379:methods / Q000662:veterinary*; D017079:Exercise Tolerance; D005260:Female; D006327:Heart Block / Q000628:therapy / Q000662:veterinary*; D008297:Male; D010138:Pacemaker, Artificial / Q000592:standards / Q000662:veterinary*; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity