SAEVA Congress 2018 Proceedings | 12-15 February 2018 | ATKV Goudini Spa
Horses with severe AR should also be examined for late diastolic MR , an indication of marked left ventricular end diastolic pressure elevation .
Once again , the echocardiographic findings and patient factors ( horse ' s age , clinical signs , rapidity of their onset , performance level ) must be combined to determine the significance of the AR for life and future performance . Atrial fibrillation ( AF ) is common in horses with moderate to severe AR associated with significant left atrial enlargement , with or without concurrent MR .
Aortic regurgitation is usually very well tolerated by horses with normal left ventricular function , in the absence of MR . Horses with aortic valve prolapse or degenerative aortic valve disease that is identified during middle age , clinically insignificant to moderate AR , minimal to moderate left ventricular and aortic root enlargement , little change in aortic root diameter , normal myocardial function and a jet area consistent with the degree of left ventricular enlargement have an excellent prognosis for life and performance . The AR is likely to progress slowly throughout the life of the horse . Annual re-examinations should be performed on these horses to determine the progression of the AR . Horses with fenestrations , small tears of the free edge of the valve leaflet , flail valve leaflets and bacterial endocarditis should initially be given a more guarded prognosis , as these valvular insufficiencies could progress more rapidly . Biannual cardiac and echocardiographic re-examinations should be performed on these horses , along with obtaining an exercising ECG , if they are used for any type of athletic work .
Even most horses with severe AR and severe left ventricular dilatation may continue to perform successfully for 2 1 / 2 - 3 years , if they have normal myocardial function , before developing signs of congestive heart failure and / or sudden cardiac death . Once horses with severe AR develop significant MR , they usually rapidly develop severe pulmonary hypertension and signs of left-sided heart failure . Therefore , horses with severe AR should be re-examined every 3-6 months , at least initially . If the regurgitant jet area is larger than expected for the degree of left ventricular enlargement , a recent onset of AR should be suspected , also prompting a re-examination in 6 months . The detection of severe AR with Doppler echocardiography , a short ( elevated ) pressure-halftime , round turgid left ventricle with decreased wall thickness , marked left atrial and ventricular enlargement , enlargement of the aortic root , a markedly decreasing aortic root diameter during diastole and decreased left ventricular function are indications of hemodynamically significant AR and a guarded to poor prognosis .
Congenital Cardiac Disease
Congenital cardiac disease should be suspected in all horses with a grade 4 / 6 or louder band shaped holosystolic or pansystolic murmur with its point of maximal intensity in the tricuspid valve area and a crescendo-decrescendo ( usually ) holosystolic murmur with its point of maximal intensity in the pulmonic valve area . If the right sided murmur
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