Abstract:
The QRS response of the electrocardiogram to bleeding has been a source of interest to the physiologist
for more than a century. Studies in the dog, cat and chicken have shown a reduction in QRS
amplitude in response to bleeding. This effect has been explained by the so-called Brody effect, in
which the intraventricular mass of blood acts as a conducting medium, augmenting radial conduction,
thus resulting in the subsequent reduction in QRS amplitude in conditions where the intraventricular
mass of blood is reduced.
The aim of this study was to evaluate whether the Brody effect will be present in the ovine heart and,
furthermore, to evaluate if the right and left ventricles will demonstrate the same QRS change if the
Brody effect is indeed present. This study clearly demonstrated that the Brody effect is present in the
ovine heart. Furthermore, two unique aspects emanating from this study are firstly the fact that this is
the first study to show that premature ventricular complexes are able to induce the Brody effect and,
secondly that there is a very clear difference in the response of the right and the left ventricles when
the Brody effect is induced in the ovine heart.
