Introduction: The primary objective of this investigation was to evaluate the sensitivity of a non-invasive telemetry system for the detection of drug-induced electrocardiogram (ECG) changes in conscious, freely moving dogs. A secondary objective was to compare, in the same set of dogs, ECG data acquired by a non-invasive system with data acquired from a surgically implanted telemetry device (invasive system).
Methods: Continuous beat-to-beat Lead II ECG data were simultaneously acquired from 6 male dogs using a non-invasive and an invasive telemetry system for 1h pre-dose and 6h following a sham control dose or single oral doses of (+/-) sotalol (4, 8 or 16 mg/kg). ECG parameters of heart rate, RR, PQ, QRS, QT and QT corrected for heart rate according to Van de Water (QTcV) and by an individual linear regression formula (QTcR), were determined.
Results and discussion: Statistically significant dose-dependent reduction of heart rate, and increases in PQ, QT and QTc (V and R) were detected at all dose levels of (+/-) sotalol, with partial recovery during the 6-hour monitoring period. Statistically significant correlations for heart rate, RR, PQ, QT and QTc (V and R) were found between the two systems. QRS duration did not correlate. However, the difference between the two systems was consistent over the range studied. Based on these findings, the non-invasive system is quantitatively comparable to invasive telemetry, and can be used successfully to acquire continuous ECG data on a beat-to-beat basis from conscious freely moving dogs for at least 6h post-dose.