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Fig. 3 | BMC Veterinary Research

Fig. 3

From: Appropriate threshold levels of cardiac beat-to-beat variation in semi-automatic analysis of equine ECG recordings

Fig. 3

RR deviation plot (a) and schematic presentation of beat patterning (b). Notice the main cluster (red square) surrounded by smaller clusters. The black area represents the main cluster of normal sinus beats. Area 1a represents sinoatrial blocks, second-degree AV blocks and QRS undersensing with double the length of normal RR intervals and RRdev ≈ 100%. Similarly, area 2a describes QRS undersensing of two consecutive complexes. Areas 1b and 2b represent normal RR intervals succeeding the aberrant intervals of areas 1a and 2a and are therefore located below the main cluster with an RRdev of approximately -50% and -66%, respectively. Area 3 refers to premature beats (both supraventricular and ventricular) while area 4 refers to “Delayed sinus beats”. Aberrant intervals caused by artifact were scattered throughout the plot

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