Modifications of the form and amplitude of the electrocardiographic QRS complex during growth in the Spanish-bred Horse.

The study examines the changes in the form and magnitude of the QRS complex in the electrocardiograms of healthy Andalusian horses aged between 1 month and 17 years, identifying a link between these changes and the horses’ ages. The researchers suggest that these age-related variations are connected to the changes in the size and arrangement of the heart within the thoracic cavity as the horses grow.

Study Overview

• The study focused on the configuration and amplitude of the QRS complex in electrocardiograms of 173 healthy Spanish-bred (Andalusian) horses.
• The ages of the horses ranged from 1 month to 17 years offering a comprehensive age range for analysis.
• The core finding involved the observation that the QRS complex initially predominantly negative in 1-month-old horses, becomes predominantly positive in the older horses.

Key Findings and Variations

• The researchers discovered statistically significant differences in the Q wave and the main vector of the QRS complex across the different age groups.
• The highest Q-wave values and the most negative values for the QRS main vector direction were found in animals up to two months old.
• It is essential to note that the Q-wave represents the initial negative deflection of the QRS complex in an ECG, whereas the main vector of the QRS complex describes its overall direction.

Implications of Age-Related Changes

• The researchers propose that the age-related changes in the form and magnitude of the QRS complex could be linked to the anatomical changes that occur as the horse grows.
• Specifically, they hypothesise that the variations could be due to changes in the size and placement of the heart within the thorax during growth.

Significance of the Study

• This study provides valuable reference data for electrocardiograms of Andalusian horses at different ages, which is essential in diagnosing and monitoring cardiac diseases in this breed.
• The findings enhance our understanding of physiological changes in the cardiovascular system during growth in horses and potentially other animals as well.