Echocardiographic changes of left ventricular size and function in a canine normovolaemic anaemia model

Abstract

The objective of this study was to non-invasively document the changes in echocardiographic variables of left ventricular size and function during acute normovolaemic anaemia. This model was developed as a pilot study with the purpose of providing baseline information to investigate the pathophysiology, and more specifically the effect on the heart, of canine babesiosis-induced anaemia. The study group comprised of 11 mature healthy Beagle dogs that weighed between 9 and 15 kg. Severe normovolaemic anaemia was induced over a 3-4 day period by serial bleeding while maintaining normovolaemia by autotransfusing plasma and infusing crystalloids. The dogs were then allowed to recover. Pre-anaemic [mean haematocrit (Hct) 46.7%, standard deviation (SD) 2.4%)] echocardiographic variables of left ventricular size and performance were statistically compared to those in the severely [mean Hct 15.3 %, SD 1.1%], moderately [mean Hct 24.7%, SD 1.5%] and mildly [mean Hct 33.5%, SD 2.5%] anaemic states, and between the anaemic states. The following variables were measured: left atrial size; left ventricular fractional shortening, ejection fraction, end-systolic and end-diastolic ventricular volumes and their derivatives [stroke volume, stroke index, cardiac output, cardiac index]; systolic time intervals [left ventricular ejection time (LVET), pre-ejection period (PEP), velocity of circumferential shortening, LVET/PEP and LVET index (LVETI)]; and heart rate. With the exception of end diastolic volume, left atrial size, LVET/PEP and LVETI, there was a statistically significant (p < 0.05) change in all variables in the severely anaemic state versus the pre-anaemic and the mild and moderate anaemic states. In accordance with previous invasive models, this study demonstrates the hyperdynamic state of the left ventricle that develops in response to experimentally induced acute canine normovolaemic anaemia in the conscious dog, and shows promise as a non-invasive technique of evaluating the cardiac changes in dogs suffering from canine babesiosis.