Telemetric intracardiac ECG dramatically improves interval detection and reduces artifact when compared to a subcutaneous lead placement in freely‐moving dogs

Abstract

Implantable radio-telemetry is a commonly used technology for monitoring electrocardiogram (ECG) signals in conscious, freely-moving animals. Traditionally, biopotential leads from a transmitter are placed subcutaneously in a lead II orientation through a simple surgical procedure. Although a wealth of valuable information can be obtained using this technique, it can be subject to muscle noise and morphology changes resulting from animal activity. ECG signals acquired from within the heart greatly minimize movement artifact and provide consistent morphology, high-amplitude waveforms ideal for interval detection. This study compares the subcutaneous ECG to intracardiac ECG data acquired telemetrically from unrestrained beagle dogs. The intracardiac ECG signal was obtained by using a bipolar pacing lead (Oscor Inc., Palm Harbor, FL) which was inserted into the right jugular vein and advanced into the right ventricle. The pacing lead was interfaced to a telemetry transmitter (Data Sciences International (DSI), St. Paul, MN) using a custom connector. The intracardiac ECG yielded relatively noise free waveforms with signal to noise ratios superior to subcutaneous ECG electrodes with signal quality maintained even during periods of high activity which, in the subcutaneous ECG signal, typically resulted in significant artifact. The percentage of waveforms that could be measured by automated ECG interval analysis software was significantly greater than via subcutaneous ECG electrodes. Intracardiac ECG combined with other parameters such as blood pressure and body temperature has proven to be an in-valuable tool for chronic cardiovascular evaluation.