Twenty-four hour Holter monitoring of unsedated healthy cats in the home environment.

To determine the heart rate, rhythm, number of ventricular premature complexes (VPCs) and atrial premature complexes (APCs) in unsedated cats using Holter monitoring. Twenty-three healthy client owned cats were used. Clinical examination, blood pressure measurements, echocardiographic examination and serum biochemical analysis were performed. A lightweight Holter was used in the home environment. Three-lead electrocardiographic registrations of good quality were obtained from all cats. Normal sinus rhythm was present in all cats. The median heart rate was 165 beats per minute (bpm), range 70-303 bpm. Mean heart rate varied significantly with age and gender. Sinus arrhythmia occurred intermittently in 18 cats (78%). Uncommon ventricular premature complexes occurred in 18 (78%) of the cats. The median number of VPCs per cat was 3 complexes/24 h period, range 0-146. Cats 7-15 years of age had significantly more VPCs than cats 1-6 years of age (median 6 versus 1 per 24 h period, p=0.04). A single APC occurred in one cat (4%). Cats commonly have intermittent sinus arrhythmia. Many healthy cats have rare single VPCs per 24 h period. Old cats have significantly more VPCs than young cats. The heart rate varies significantly with age and gender.