SAEVA Congress 2018 Proceedings | 12-15 February 2018 | ATKV Goudini Spa
Mitral Regurgitation
Mitral regurgitation (MR) is the valvular insufficiency most likely to be associated with
poor performance or clinical signs of heart failure. Abnormalities of the mitral valve
leaflets and/or chordal apparatus are usually detected echocardiographically. However,
MR may be present with no detectable structural abnormalities.
Causes of mitral regurgitation - Prolapse and/or thickening of the mitral valve leaflets
are the most common finding in horses with MR. The entire mitral valve leaflet, or a
portion thereof, is imaged bulging backwards into the left atrium in horses with mitral
valve prolapse, and is worse during mid to late systole.
MV Prolapse
Degenerative changes of the mitral valve leaflets, a common finding in older horses, or
a non-infective valvulitis result in leaflet thickening that can often be detected
echocardiographically. Non-infective valvulitis usually causes slightly hypoechoic to
echogenic valvular thickening while degenerative valve disease usually results in
echogenic to hyperechoic thickening of the valve leaflets with possible involvement of
the chordal apparatus.
Ruptured chordae tendineae (RCT) and flail valve leaflets are a less common cause of
MR in horses. A mobile linear echo everting into the left atrium in systole is diagnostic
of a RCT. The asynchronous movement of all or part of a valve leaflet in any phase of
the cardiac cycle is indicative of a flail valve leaflet.
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