SAEVA Congress 2018 Proceedings | 12-15 February 2018 | ATKV Goudini Spa
The regurgitant jet is usually oriented towards the aortic root in horses with typical TR.
Indications of severe TR include a regurgitant jet that occupies 2/3 or more of the right
atrial chamber, bulging of the interatrial septum towards the left and an intense Doppler
signal. The intensity of the TR murmur is some indication of its severity in horses
without pulmonary hypertension.
Continuous wave Doppler echocardiographic
estimation of the pressure difference between right atrium and ventricle can be
performed by adding 10 - 15 mm Hg (the estimated right atrial pressure) to 4v 2 in
horses with severe TR.
Patient factors (horse's age, clinical signs, rapidity of their onset, performance level)
and echocardiographic findings must be considered together when formulating a
prognosis for life and performance in horses with TR, just like with MR. Primary TR is
unlikely to affect a horse's performance, unless it is severe. Horses with tricuspid valve
prolapse or degenerative tricuspid valve disease, clinically insignificant to moderate TR,
minimal to moderate right atrial and ventricular enlargement, and normal myocardial
function have an excellent prognosis for life and p erformance. Horses with a ruptured
chorda tendineae may have minimal TR if only a small chorda tendineae is involved.
These horses also have a good prognosis if there is only minimal to mild right atrial and
ventricular enlargement and normal myocardial function. If the regurgitant jet area is
larger than expected for the degree of right atrial enlargement, a recent onset of TR
should be suspected, prompting a re-examination in 6 - 12 months, especially if severe
TR is detected with Doppler echocardiography. These horses should be given a more
guarded prognosis. Horses with a major ruptured chorda tendineae, flail tricuspid valve
leaflet, bacterial endocarditis, or pulmonary hypertension from severe left sided heart
disease must also be given a more guarded prognosis as more rapid deterioration is
likely. Horses with moderate to severe TR should have an annual echocardiographic
re-examination. Once TR is severe, it is likely to affect performance, particularly for the
most rigorous types of athletic endeavor. However, the progression to CHF is slow
compared to horses with severe MR.
Aortic Regurgitation
Aortic regurgitation is usually a disease of older horses (> 10 years) caused by
degenerative valve disease. Aortic regurgitation is usually mild to moderate when the
murmur is first detected and usually progresses slowly, rarely causing poor
performance or the development of congestive heart failure.
Thickening of the aortic valve, particularly the left cusp is the most common finding.
This appears as an echogenic thickening parallel to the free edge of the leaflet (most
common) or as a nodular thickening.
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