Echocardiographic identification of atrial-related structures and vessels in horses validated by computed tomography of casted hearts.

BACKGROUND: Echocardiography is the imaging technique of choice for the equine heart. Nevertheless, knowledge about ultrasonographic identification of dorsally located structures and vessels, related to the atria, in horses is scarce.

OBJECTIVES: To describe the echocardiographic approach and the identification of structures and vessels in relation to the atria in healthy horses.

METHODS: CT images from two equine hearts, casted with self-expanding foam, were segmented and used to identify atrial-related structures and vessels. These images were compared with standard and nonstandard ultrasound images from ten healthy horses obtained from a left and right parasternal view optimised to visualise the dorsal cardiac area.

RESULTS: On new standard ultrasound views, specific atrial anatomical landmarks such as vena cava, pulmonary arteries, intervenous tubercle and oval fossa were identified in all horses. In addition, ultrasound views were defined to visualise the brachiocephalic trunk, pulmonary veins and their ostia. The 3D segmented CT images from casted hearts were used to reconstruct slices that corresponded with the echocardiographic images and allowed correct identification of specific structures.

MAIN LIMITATIONS: Ultrasound examinations and casts were from different animals. A small number of casts and horses were used; therefore, anatomical variation or individual differences in identifying structures on ultrasound could not be assessed.

CONCLUSIONS: Important cardiac structures and vessels, even the different pulmonary veins, could be identified on standard and nonstandard ultrasound images in adult horses. This knowledge is important to guide and develop interventional cardiology and might be useful for diagnostic and therapeutic purposes.