SAEVA Congress 2018 Proceedings | 12-15 February 2018 | ATKV Goudini Spa
echocardiography to determine the hemodynamic significance of the VSD. A peak
shunt velocity (v) through the VSD of > 4.5 m/sec is indicative of a restrictive VSD,
while defects with peak shunt velocities < 4m/sec are hemodynamically significant.
CW Doppler tracing of shunt
Measuring systolic arterial blood pressure (SAP) directly or indirectly through coccygeal
arterial Doppler measurements will allow the echocardiographer to estimate right
ventricular pressure (RVP) in horses with VSDs using the following formula: RVP =
SAP - 4v 2 .
Ventricular septal defects may be detected as an incidental finding in horses
performing up to their owner's or trainer's expectations or can be the cause of exercise
intolerance. Prognosis for horses with a ventricular septal defect is based upon the
number of VSDs, their location, size, interventricular pressure gradient, shunt direction,
degree of left ventricular volume overload, left ventricular function and the presence or
absence of concomitant aortic prolapse, AR and its severity. Horses with a small (< 2.5
cm) perimembranous VSD, with a peak shunt velocity > 4 m/sec, little or no AR and
good left ventricular function have a good prognosis and may even be able to compete
successfully as racehorses, although not usually at the stakes level. Horses with VSDs
> 2.5 cm but < 3.5 cm and shunt velocities > 3 m/sec but < 4 m/sec may be useful
pleasure horses but are unlikely to be successful competing at the upper levels of
equine athletic performance. Most horses with VSDs > 3.5 cm in diameter or shunt
velocities < 3 m/sec have a shortened life expectancy and develop congestive heart
failure.
Sinus of Valsalva aneurysm and aortic root rupture
Sinus of Valsalva aneurysms are defects in the wall of the aorta in the right sinus of
Valsalva that are asymptomatic until associated with aortic root rupture later in life.
Aortic root rupture at the right sinus of Valsalva can also occur without a pre-existing
aneurysm. Most affected horses are male, at least 10 years old and present with
tachycardia and colic without any detectable primary gastrointestinal problem,
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