[A comparison of cardiac stroke volume determination using the thermodilution method and PW-Doppler echocardiography for the evaluation of systolic heart function in the horse].

This research paper is about a comparative study of two methods – thermodilution and pulsed-wave Doppler echocardiography – in determining the stroke volume, or the amount of blood pumped by the heart per beat, in horses.

Objective of the study

The main purpose of this study was:

• To compare two different methods – thermodilution and pulsed-wave Doppler echocardiography – for evaluating the systolic function of the heart in horses, mainly by determining the stroke volume or the volume of the blood pumped by the heart in one beat.

Methodology

The researchers used the following steps to conduct their study:

• The study was performed on 14 horses who were not suffering from any heart diseases.
• The stroke volume was determined in the horses using both thermodilution and Doppler echocardiography simultaneously.
• The Doppler echocardiographic volume determinations were done in both the left and right outflow tracts of the horse’s heart.
• The researchers measured various aspects including the Velocity Time Integral, Maximum Flow Velocity, Mean Flow Velocity and Acceleration Time using echocardiography.
• To account for differences in horse sizes and consequently their heart volumes, the stroke volume was calculated relative to 1 kg of body weight, a parameter termed as the “heart index”.

Findings

The results from the study were as follows:

• There was no significant difference between the heart index determined by thermodilution and that determined by Doppler echocardiography.
• The stroke volume that was measured in the right outflow tract using Doppler echocardiography was closest to the values measured by thermodilution, with a mean difference of around 124.3 +/- 55 ml.
• The standard variations of the volume found in the left and right outflow tracts, determined from the right body wall using Doppler echocardiography, were lower than the standard variations of the thermodilution method.
• Use of Doppler echocardiography for heart volume determination proved to be as effective for evaluating the systolic function of the horse’s heart as the thermodilution method.