A phonocardiographic study of equine heart sounds.

The study detailed an investigation into the timing and occurrence of heart sounds in horses, utilizing phonocardiograms. It found that each cardiac cycle in horses could be separated into ten sound events, with the first heart sound embodying four components and the second being a singular sound.

Investigation of Equine Heart Sounds

• The study was focused on the heart sounds made by horses, a subject which was observed through the use of phonocardiograms. Phonocardiograms are devices that record the sounds and murmurs of the heart, letting the researchers analyze the timing and frequency of different heart sounds.
• The research was conducted on 18 horses, and the phonocardiograms were taken from three different areas of the heart: the mitral, aortic, and tricupsid.

Findings

• There were ten identifiable sound events occurring with each cardiac cycle. A cardiac cycle refers to a complete heartbeat which includes contraction (systole) and relaxation (diastole) of the atria and ventricles.
• The atrial contraction, the phase when the atria pump blood into the ventricles, was found to produce up to three different sound events.
• The first heart sound was observed to be composed of four different components. This sound is usually associated with the closing of the heart’s valves as blood is pumped from the heart.
• The second heart sound was found to be a singular sound event. This sound generally signifies the sudden block of reversing blood flow due to closure of the heart valves.
• Two sound events were found to be associated with the third heart sound, which occurs in the early diastole phase when the ventricles are resistant to filling.

Variations and Best Area for Recording

• The researchers found that the occurrence of the third and fourth heart sound components showed variance not only between horses but also between the three different recording areas of the heart.
• Amongst the three areas under study – the mitral, aortic, and tricupsid, the findings supported that the mitral recording area provided the most satisfactory results for conducting routine phonocardiographic studies in horses.