Quantitative assessment of left ventricular volume and function by transthoracic and transesophageal echocardiography, ultrasound velocity dilution, and gated magnetic resonance imaging in healthy foals.

This research examines and compares the measurements obtained from different methods for assessing the volume and function of the left ventricle in the hearts of healthy one-week-old Standardbred foals.

Methodology

• The research involved six healthy one-week-old Standardbred foals.
• Various modalities such as 2D transthoracic echocardiography (2DE), transesophageal echocardiography (TEE), ultrasound velocity dilution cardiac output method (UDCO), and cardiac MRI (cMRI) were used to measure the volume of the left ventricle in the foals.
• Images were obtained via 2DE, the right parasternal 4-chamber (R4CH), left apical 4 and 2-chamber (biplane), and right parasternal short-axis M-mode (M-mode) views.
• The foals were anesthetized during the processes to ensure accurate measurements.
• Various indicators of cardiac function like left ventricular end-diastolic volume (LVEDV), end-systolic volume (LVESV), ejection fraction, stroke volume (LVSV), cardiac output (CO), and cardiac index (CI) were measured.
• Measurements obtained were then comparatively analyzed using Bland-Altman analyses.
• Repeatability of measurements was also assessed among three independent reviewers using the intraclass correlation coefficient.

Results

• All the echocardiography modalities and the UDCO method underestimated the LVEDV and LVESV while overestimating the ejection fraction, CO, and CI.
• Only the LVSV was both underestimated (by biplane, R4CH, TEE modalities) and overestimated (by UDCO and M-mode method).
• The R4CH-derived measurements for LVSV, CO, and CI were closely comparable to the measurements obtained via cMRI.
• The measurements from cMRI, biplane, R4CH, M-mode, and UDCO were repeatable and reliable while the TEE-derived measurements showed poor repeatability.

Conclusions

• Despite the discrepancies, all the assessed modalities provided clinically acceptable measurements of LVEDV, LVESV, and function.
• However, the study concluded that these measurements should not be used interchangeably when monitoring the progress of a patient.