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Effect of acute haemorrhage on QRS amplitude of the lead II canine electrocardiogram
Author(s) -
TORRE PK DELLA,
ZAKI S.,
GOVENDIR M.,
CHURCH DB,
MALIK R.
Publication year - 1999
Publication title -
australian veterinary journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.382
H-Index - 59
eISSN - 1751-0813
pISSN - 0005-0423
DOI - 10.1111/j.1751-0813.1999.tb10265.x
Subject(s) - qrs complex , medicine , cardiology , lead (geology) , electrocardiography , anesthesia , blood volume , geology , geomorphology
Objective To examine the effect of acute haemorrhage on the QRS amplitude of the canine lead II surface electrocardiograph (ECG). Design Ten adult racing Greyhounds were tranquilised, anaesthetised, positioned in right lateral recumbency and connected to recording electrodes of an ECG unit. Baseline six‐lead ECG traces were recorded, and further traces were obtained after one unit (460 mL) of blood, and then a second unit, were collected from the femoral artery. Results There was a consistent and progressive reduction in amplitude of the QRS complex in all leads during acute haemorrhage. QRS amplitude in lead II after removal of two units of blood averaged 74% of the baseline voltage, with individual values of 61 to 91% (P < 0.0001). There were even greater reductions in QRS amplitudes in lead aVL during haemorrhage. In three additional dogs, reductions in QRS voltages were shown to be accompanied by reductions in end‐diastolic left ventricular internal dimensions measured echocardiographically. Furthermore, the effects of haemorrhage on the QRS amplitude and echocardiographic measurements were reversed when circulating blood volume was restored by re‐infusion of blood removed previously. Conclusion Acute haemorrhage corresponding to an approximately one‐third reduction in blood volume caused a substantial reduction in QRS voltage of the surface ECG. It is postulated that this resulted from diminished ventricular distension as a consequence of reduced venous return. A similar mechanism may account for the small‐amplitude ECG complexes associated with pericardial effusion, severe dehydration and hypovolaemia.