Related Experiment Videos
Use of the cardiopulmonary flow index to evaluate cardiac function in thoroughbred horses
A J Guthrie1, V M Killeen, M S Mülders
1Equine Research Centre, Faculty of Veterinary Science, University of Pretoria, Onderstepoort, Republic of South Africa.
Insights
The cardiopulmonary flow index (CPFI) is a sensitive measure of cardiac function in horses. This index, derived from radiocardiograms and electrocardiograms, detected differences in horses with toxic myocarditis that cardiac output did not.
Area of Science:
- Veterinary Cardiology
- Cardiopulmonary Physiology
- Toxicology
Background:
- Salinomycin, an ionophore, has been linked to toxic myocarditis in horses.
- Assessing cardiac function in horses with toxic myocarditis can be challenging.
Purpose of the Study:
- To evaluate the cardiopulmonary flow index (CPFI) as a sensitive indicator of cardiac dysfunction in horses.
- To compare CPFI with cardiac output in horses affected by toxic myocarditis.
Main Methods:
- Simultaneous measurement of CPFI and cardiac output in horses with diagnosed cardiac disease and control horses.
- Radiocardiogram and electrocardiogram recordings were used to determine CPFI.
- Pharmacological acceleration of heart rate was used to study its effect on CPFI.
Main Results:
- Significant differences in mean CPFI were observed between control horses and those with myocardial fibrosis.
- No significant differences in cardiac output were found between groups.
- CPFI showed significant differences related to heart rate in diseased versus control horses, particularly near resting rates.
Conclusions:
- The cardiopulmonary flow index (CPFI) is a more sensitive diagnostic tool for equine cardiac dysfunction than cardiac output.
- CPFI can detect subclinical cardiac changes associated with toxic myocarditis in horses.
- CPFI measurements, especially in relation to heart rate, offer valuable insights into equine heart health.
Abstract:
The ratio of the cardiopulmonary blood volume to stroke volume is called the cardiopulmonary flow index (CPFI). The CPFI can be determined indirectly from the simultaneous recording of a radiocardiogram and an electrocardiogram. The CPFI and cardiac output were measured simultaneously in horses (n = 10) that were diagnosed as having cardiac disease. The diseased subjects were probably all exposed to feed contaminated with the ionophore, salinomycin, and all showed clinical signs indicative of chronic toxic myocarditis. The results obtained from these subjects were compared with those from control animals and significant differences (P less than 0.05) were found between the mean CPFI of the control horses and those with macroscopically visible myocardial fibrosis on post mortem examination. No significant differences were found between the means of the cardiac output measured in either of the groups of horses. The effect of pharmacological acceleration of the heart rate on the CPFI was also studied. Significant differences (P less than 0.05) were found between the mean CPFI and the slopes of the regression lines of CPFI on heart rate of the control and principal groups of horses. These differences were greatest at heart rates near to the resting heart rates of the individuals. The CPFI was found to be a more sensitive measure of cardiac function than cardiac output, in the horses.