Accuracy of formulae for calculating left ventricular volumes of the equine heart.

This study concludes that echocardiography can be an accurate technique for measuring the left ventricular volumes and mass of a horse’s heart, providing a better understanding of heart size and hypertrophy. The method is efficient when using geometric models of both the external and internal shapes of the left ventricle. Among the models tested, the ellipsoid formula showed the most accuracy.

Research Methodology

• The researchers preserved 30 horses’ hearts and conducted careful measurements of their dimensions and cross-sectional areas.
• These measurements were applied to seven different formulae, each representing a distinct geometrical model of the ventricle and its chamber.
• In order to estimate the long axis as a fixed proportion of the external diameter, a correction factor was derived, enabling volumes to be determined either from an M-mode or a cross-sectional echocardiogram.

Results and Findings

• The research concluded that the ellipsoid formula, using cross-sectional areas, was the most accurate model for representing the external shape of the left ventricle.
• Volume of myocardium, calculated by subtracting the internal chamber volume from the external volume, was also found to be accurately measured using the ellipsoid formula.
• Statistical analysis showed high correlation between the calculated volumes and those measured by water displacement, with slope values near 1 and an r-square value above 94% for both the external shape of the left ventricle and its chamber.
• Although also accurate, the ellipsoid formula using directly measured diameter was found to be slightly less precise.

Practical Application

• The mass of the left ventricle can be calculated by applying the specific gravity of equine myocardium (1.05) to the myocardial volume determined from the volume calculation method.
• Recommended formulae for evaluating left ventricular volume with M-mode echocardiography and 2D echocardiography were provided, utilizing external diameter, internal diameter, external area, and internal area as variables.

Conclusion

• This research is significant because it confirms the effectiveness of echocardiography for accurately measuring the left ventricular volumes and mass of a horse’s heart.
• The developments in this study can enable further studies on heart size and hypertrophy. Giving rise to a better understanding of equine cardiovascular health and potentially leading to improvements in their care and treatment.