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Effect of electrocardiographic filters on the R‐amplitude of canine electrocardiograms
Author(s) -
Dvir E.,
Lobetti R. G.,
Cilliers P. J.
Publication year - 2002
Publication title -
veterinary record
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.261
H-Index - 99
eISSN - 2042-7670
pISSN - 0042-4900
DOI - 10.1136/vr.150.6.171
Subject(s) - qrs complex , amplitude , cardiology , medicine , electrocardiography , filter (signal processing) , mathematics , physics , electrical engineering , optics , engineering
Lead II electrocardiograms (ECGs) were recorded in 88 dogs ranging in weight from 3 to 50 kg. A commercial direct‐writing electrocardiograph was used to record the ECGs, first with manual HUM filter (notch filter at 50/60 Hz) and EMG filter (cut‐off frequency of ‐3 dB at 35 Hz) on, immediately followed by a recording with both filters off. The mean (sd) reduction in R‐amplitude with the filters on was 53(18) per cent with a range from 22 to 100 per cent and a median value of 51 per cent. The R‐amplitude with the filters off was related to the R‐amplitude with the filters on, making it possible to correct for the effect of the filters. The reduction in R‐amplitude was inversely correlated with the weight of the dog and with the duration of the QRS‐complex. Other known changes induced by filters, such as the elimination of notches and the slurring of the junction between the QRS‐complex and the sT‐interval were also observed. The inverse relationship between the weight of the dog and the magnitude of the reduction in R‐amplitude by the filters indicates that ECG machines with different characteristics should ideally be used to record ECGs in dogs of different sizes.