Page 154 - Problem-Based Feline Medicine

146 PART 3 CAT WITH SIGNS OF HEART DISEASE

Diagnosis In cases with severe mitral regurgitation, secondary
left ventricular enlargement (LV end-diastolic
Radiographic findings
dimension >17 mm) is usually seen.
Marked left atrium enlargement is seen, as demon-
strated by elevation of the carina and bulging of the Severe mitral regurgitation and stenosis do not nec-
caudal atrial wall on the lateral view. A valentine- essarily have to co-exist in the same patient.
shaped heart may be seen on the V/D view.
Differential diagnosis
Pulmonary venous congestion defined by a larger pul-
Cardiomyopathy is uncommon in young cats. Cardio-
monary vein than the accompanying artery, with or
myopathy murmurs are usually not as loud. Cardiomy-
without pulmonary edema may be present.
opathy murmurs may sound different with serial
Left ventricular enlargement is seen with the cardiac sil- auscultations.
houette larger than two intercostal spaces on the lateral view,
Pulmonic or aortic stenosis is present with louder and
secondary to severe mitral valve regurgitation.
harsher murmurs than mitral valve dysplasia/ stenosis.
Electrocardiographic findings Atrial septal defects usually have soft murmur present
Left ventricular hypertrophy demonstrated by a tall R at the left heart base.
wave in lead II (> 0.9 mV).
Differential diagnosis solely based on physical exam
Sinus tachycardia (HR > 220 bpm) if heart failure is may be difficult.
present.
Treatment
Some cases may have atrial premature contractions
or paroxysmal atrial tachycardia. If atrial fibrillation is Many cases are asymptomatic and there is no need for
present, there is invariably severe left atrial enlargement. therapy.
If the patient is in congestive heart failure, refer to the
Echocardiographic findings
hypertrophic cardiomyopathy section (page 130) for
A thick and misshapen mitral valve is seen which may treatment details.
have poor motility during diastole.
Prognosis
Systolic anterior motion of the mitral valve may be
seen (anterior displacement into the left ventricular out- Prognosis is good in most cases. Cats with marked
flow of the anterior mitral valve leaflet causing outflow mitral regurgitation may only develop symptoms of
obstruction). congestive heart failure between 5–10 years of age.

Variable degrees of mitral regurgitation are found on Patients with severe regurgitation may present in con-
Doppler study. gestive heart failure within the first year of life.
Determination of the mitral valve inflow velocity pro- Prognosis is worse with the presence of co-existent
file is essential to determine the presence and degree of thromboembolic disease.
mitral stenosis.
● The early diastolic wave (E wave) of mitral inflow
AORTIC STENOSIS
shows delayed deceleration of blood flow in mid-
diastole, and there is fusion with the atrial diastolic
Classical signs
wave (A wave). This results in an M-shaped mitral
inflow profile or in severe cases a rectangular shape. ● Systolic murmur is heard over the left heart
base or over the cranial aspect of the sternum.
Secondary left atrial enlargement occurs with the left
atrial to aortic ratio usually > 2.0. Left atrial enlarge- Pathogenesis
ment is either secondary to restriction of filling of the
left ventricle by a stenotic valve or because of severe With congenital valvular malformation of the aortic
regurgitation. valve, there is thickening of the valve leaflets and