Comparison of non-invasive and implanted telemetric measurement of blood pressure and electrocardiogram in conscious beagle dogs.

INTRODUCTION The objective of this study was to evaluate the ability of a non-invasive telemetry monitoring system to detect and quantify changes in blood pressure and electrocardiogram (ECG) parameters in response to vehicle, L-NAME or minoxidil administration to freely moving beagle dogs. Data from a non-invasive telemetry monitoring system were compared to data captured from an invasive telemetry implant in the same animals. METHODS Blood pressure and ECG data were simultaneously acquired from male dogs using a non-invasive and an invasive implanted telemetry system for 2 hours predose and 24 hours post dosing with vehicle (n=5), minoxidil at 1 mg/kg (n=4) and L-NAME at 10 mg/kg (n=5) on separate test days. Values for mean blood pressure, systolic blood pressure, diastolic blood pressure, pulse pressure, heart rate, RR, PR, QRS, QT and QTcL (heart rate corrected QT interval) interval were reported for both methods. RESULTS Statistically significant reductions in blood pressure and pulse pressure and increases in heart rate, with associated ECG interval changes were apparent following dosing with minoxidil using both methods. Statistically significant increases in blood pressure and pulse pressure were apparent following dosing with L-NAME when using the invasive telemetry system, changes were apparent when using the non-invasive telemetry system, however, no change was apparent for pulse pressure, they were of shorter duration and not statistically significant. Statistically significant decreases in heart rate, with associated changes in ECG intervals, were apparent following treatment with L-NAME for both invasive and non-invasive methods. DISCUSSION This study shows that the non-invasive system can be successfully used to acquire both ECG and blood pressure data in freely moving jacketed dogs for at least 26 hours, yet requires further technique refinement to improve system sensitivity to detect smaller changes in blood pressure.