Small Animal Radiology and Ultrasound: A Diagnostic Atlas and Text

Chapter Two The Thorax 145
Fig. 2-119 A 3-month-old male
English Springer Spaniel with an
asymptomatic grade 5/6 murmur
that was loudest at the left cranial
cardiac base with palpable thrills on
both the left and right thoracic walls.
A continuous wave Doppler study
reveals a severe increase in velocity
(7.7 meters per second and a pressure
gradient of 235 mm Hg).
Diagnosis: Severe pulmonic stenosis.
Fig. 2-120 A 10-month-old male
Miniature Schnauzer had a murmur.
A continuous wave Doppler
echocardiogram revealed a marked
increase in velocity across the pulmonic
valve (4.24 meters per second
and approximately a 72 mm Hg gradient).
Other findings included dilation
and hypertrophy of the right
ventricle. Diagnosis: Moderate pulmonic
stenosis.
studies will identify turbulent flow distal to the pulmonic valve. Turbulence may be seen
proximal to the valve in diastole if pulmonic insufficiency is also present. Tricuspid insufficiency
may be observed also in some cases.
Spectral Doppler studies, preferably using continuous wave or high pulse repetition
frequency techniques, are requisite to assess the severity of the disease. Patients with gradients
exceeding 80 to 100 mm Hg, as calculated using the modified Bernoulli equation from
the peak velocity across the pulmonic valve, are considered to be severely affected and are
candidates for immediate treatment, while those with gradients from 40 to 80 mm Hg usually
are not treated but are reevaluated periodically. Treatment planning for balloon valvuloplasty
uses echocardiography to determine the size of the outflow tract and
annulus. 319,320 It is also very important to identify the presence of the ostium for the right
coronary artery, because lack of a right coronary artery is considered a contraindication to
balloon valvuloplasty.
S E P TA L D E F E C T S
Atrial and mixed atrioventricular defects may be viewed as defects in the development of
the endocardial cushion. 321 Although this interpretation may be called into question, it is
clear that these lesions do exist in a mixed format in many affected individuals.
Furthermore, it appears that VSDs commonly are seen in combination with some of the
other lesions listed above.