Improved Signal Quality and Sensitivity Using Intravascular Placement of Solid Tip ECG Leads in Rats

Abstract

Continuous data recording, using telemetry, is the preferred way of collecting electrocardiographic (ECG) data in conscious freely moving animals. In small animals, however; the resulting recordings can have indistinguishable P, Q, R, S and T segments due to low signal to noise ratios. In large animals, this has been addressed using wireless telemetry devices with an intravascular negative electrode, or solid tip lead (STL). The purpose of this study was to determine if STLs could be implanted in rats and result in improved ECG signal quality and sensitivity to detect changes when compared to subcutaneous (SQ) leads. Three groups of Sprague Dawley rats (SQ lead placement, STL with shallow placement in the jugular vein, STLs with deep placement in the cranial vena cava) were dosed with verapamil to induce predictable interval changes in the ECG. The three types of ECG signals were compared for ease of automated analysis and signal quality through Q, R, S and T match and noise parameters. STLs resulted in improved signal quality and increased PR interval change following dose. Average number of waveform complexes identified as “bad” by the analysis software was substantially lower in the STL placements than the data collected with SQ electrodes. STLs were successfully implanted in rats and necropsy showed variable tip locations with no gross abnormalities. This application could be especially useful in other small animal models such as the guinea pig, to increase ECG quality and improve automated ECG analysis.