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.
Highlights
The variations in the QRS amplitude of the electrocardiogram, caused by alterations in ventricular filling, have been a source of interest to the physiologist since 1910 (Brody 1956; Nelson, Lange, Hecht, Carlisle & Ruby 1956; Ishikawa, Berson & Pipberger 1971; Manoach, Gitter, Grossman & Varon 1971; Manoach 2000)
This study clearly demonstrated that the Brody effect is present in the ovine heart
Brody effect induced by premature ventricular complexes in ovine heart the QRS complex while increased ventricular filling causes an increase in the amplitude of the QRS complex (Manoach, Gitter, Grossman & Varon 1972; Manoach, Varon, Grossman, Gitter & Sroka 1971; Manoach, Gitter, Grossman, Varon & Gassne 1971)
Summary
The variations in the QRS amplitude of the electrocardiogram, caused by alterations in ventricular filling, have been a source of interest to the physiologist since 1910 (Brody 1956; Nelson, Lange, Hecht, Carlisle & Ruby 1956; Ishikawa, Berson & Pipberger 1971; Manoach, Gitter, Grossman & Varon 1971; Manoach 2000). Accepted for publication 16 April 2009—Editor lar filling has been increased and decreased were described in both poikilotherms and homeotherms (Manoach, Gitter, Grossman & Varon 1972) In all these experiments, ventricular filling was decreased directly by bleeding or clamping of the inferior vena cava, or indirectly by compression of the heart via the induction of a pericardial effusion, or increased directly via the infusion of blood and other fluids or indirectly via clamping of the aorta. Ventricular filling was decreased directly by bleeding or clamping of the inferior vena cava, or indirectly by compression of the heart via the induction of a pericardial effusion, or increased directly via the infusion of blood and other fluids or indirectly via clamping of the aorta In both poikilotherms and homeotherms the QRS amplitude of the electrocardiogram changes during bleeding—leading to emptying of the ventricle—or filling of the ventricle (Manoach et al 1972). This effect results from the lower resistivity of the intraventricular blood mass as compared to the surrounding tissues, in essence causing a short-circuiting effect (Ishikawa 1976)
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