High-fidelity electrocardiograms of normal rabbits

Abstract

Normal rabbit electrocardiograms were taken using high sensitivity, recording speed, and frequency response. The signals were recorded on magnetic tape and replayed with a time expansion of 32 to 1. Bipolar and augmented unipolar limb leads and two unipolar chest leads were recorded. Mean values, ranges, and standard deviations for the P, QRS, and T voltages were obtained, as well as mean frontal plane vectors. Similar data for durations were found. The ranges of mean axes were 44° to 86° for P, 55° to 103° for T, and –79° to +156° for QRS. The wide range in ventricular electrical axis may be due to changes in heart position. Notching of P and QRS complexes was due to the high resolution used.

Conditioning-specific reflex modification of rabbit (oryctolagus cuniculus) heart rate.

“…With rare exceptions (Nijsen, Croiset, Diamant, de Wied, & Wiegant, 2001; Nijsen et al, 1998), a detailed analysis of the electrocardiogram (ECG; e.g., PQ or QT intervals) during conditioning has not been conducted either because of a low signal-to-noise ratio in components of the ECG (the P wave amplitude is 10-fold smaller than that of the R wave; Nelson, Waggoner, & Gastonguay, 1964) or because sufficient information has been derived from the heartbeat (R-R interval). However, in a series of contextual conditioned fear experiments in which high-resolution ECG data were collected in freely moving rats, Nijsen and colleagues (1998) found that a conditioned decrease in tachycardia was correlated with an increase in the PQ interval.…”