Page 156 - Problem-Based Feline Medicine

148 PART 3 CAT WITH SIGNS OF HEART DISEASE

Prognosis The murmur is best heard at the left heart base. It is an
ejection systolic murmur, which varies in intensity dur-
Prognosis is dependent on severity of the stenosis and
ing systole because of the crescendo and decrescendo
the presence of congestive heart failure with or without
character.
collapse.
Characterization of the ejection murmur may be diffi-
Some cats may have a normal lifespan.
cult in a cat because of the fast heart rate.
Severely affected cats die within the first 1–2 years of life.
Diagnosis
Cats with aortic stenosis are at an increased risk of
developing bacterial valvular endocarditis.
Radiographic findings
Normal cardiac size or right ventricular enlargement is
PULMONIC STENOSIS found.

Dilated main pulmonary artery (post-stenotic dilata-
Classical signs
tion) is seen as a bulge in the left cranio-lateral part of
● Systolic murmur is heard over the left heart the cardiac silhouette in the ventro-dorsal view or
base over the pulmonic area. dorso-ventral view.

Under-perfused pulmonary circulation is seen as
Pathogenesis
hypovascular lung fields characterized by hyperinflated
With congenital valvular malformation of the pulmonic lungs and a decreased peripheral pulmonary vasculature.
valve, there is thickening of the valve leaflets and
Electrocardiographic findings
poor motility during systole, resulting in fixed
Tachycardia is frequently seen with a heart rate greater
obstruction of outflow of blood. In some cases,
than 220 bpm.
supravalvular or subvalvular stenosis may be found.
Right axis deviation is seen between −60 and −180
The increased resistance to blood flow across the pul-
degrees in the frontal plane.
monary valve stenosis results in elevation of right ven-
tricular systolic pressure. Secondary right ventricular Deep S waves are seen on leads II, aVF and III.
hypertrophy and dilation may develop, along with
arrhythmias. Echocardiographic findings
Dilation and hypertrophy of the right ventricle may Pulmonary valve stenosis is present. Pulmonary
result in secondary tricuspid insufficiency. artery hypoplasia and a dysplastic pulmonic valve
may be evident.
Signs of right-sided congestive heart failure may develop.
Doppler study across the pulmonary valve will deter-
Pulmonic stenosis is often seen with other cardiac
mine the degree of stenosis. Velocities of blood flow
defects such as tetralogy of Fallot, septal defects and
obtained by continuous wave Doppler above 2.0 m/s are
tricuspid dysplasia.
diagnostic of stenosis.
It is a rare congenital defect in cats.
Cardiac catheterization findings
Clinical signs Selective angiography of the right ventricle will show:
● Right ventricular hypertrophy.
Many cats are asymptomatic and present for evalua-
● Pulmonary valve stenosis and post-stenotic dilata-
tion of a heart murmur.
tion of the main pulmonary artery.
The age of presentation varies from the first few
months of life until middle age.
Differential diagnosis
Cats with symptoms may show dyspnea or open-mouth
breathing after mild to moderate exercise. Tetralogy of Fallot.