Page 163 - Problem-Based Feline Medicine

9 – THE CAT WITH ABNORMAL HEART SOUNDS AND/OR AN ENLARGED HEART 155

Partial or complete loss of the thoracic–diaphrag- Left ventricular enlargement.
matic surface outline is seen.
Dorsal displacement of the trachea.
In some cases, pleural effusion is detected.
Pulmonary edema.
Electrocardiographic findings Dilatation of the pulmonary veins relative to the pul-
Mean electrical axis may be shifted due to the altered monary arteries.
position of the heart in the chest.
Pleural effusion may be present (rare).
A typical mean electrical axis shift cannot be expected,
due to the variable position of the heart in each indi- Electrocardiographic findings
vidual case.
Sinus tachycardia if heart failure is present.
Echocardiographic findings Left ventricular enlargement (R wave > 0.9 mV on
A normal echocardiogram is found, unless concurrent lead II).
heart disease is present. Left anterior fascicular block (LAFB) may signify left

The abdominal viscera may displace the heart making ventricular enlargement. In LAFB the QRS duration
it difficult to obtain standard imaging planes. is normal, there is marked left axis deviation (between
−60 and −90 degrees), small Q wave and tall R wave in
Abdominal organs are visualized within the chest leads I and aVL, deep S waves in lead II, III and aVF.
cavity.
Arrhythmias are uncommon.

VALVULAR ENDOCARDIOSIS
Echocardiographic findings
Thick and prolapsing mitral valve.
Classical signs
Marked mitral regurgitation.
● Systolic murmur.
● Marked left atrial enlargement
● Gallop.
● Variable degrees of left ventricular enlargement occur
● Dyspnea or tachypnea if symptomatic.
depending on the degree of valvular insufficiency.
Pathogenesis ● Hyperkinetic left ventricle (contraction is exuber-
ant, stronger than normal) with a fractional shorten-
This is a rare disorder in cats. ing often greater than 55%.
Degeneration of the collagen matrix of the valve
occurs resulting in laxity of the chord apparatus and Differential diagnosis
prolapse of the valve.
Any type of cardiomyopathy.
There is thickening of the valve leaflets. ● Cardiomyopathy cases have in general normal
valvular morphology.
Clinical signs
● In cardiomyopathy patients, the degree of valvular
Systolic murmur located over the apex of the heart. insufficiency is usually less than with endocardiosis.
Gallop rhythm may be present.
Treatment
Tachypnea or dyspnea may be present in cases with
concurrent congestive heart failure. If not in congestive heart failure:
● Treatment is not required and probably will not
Diagnosis change the outcome.
● If severe left atrial enlargement is present (left atrial
Radiographic findings to aortic ratio >2), consider beta-blocker therapy
Marked left atrial enlargement. (refer to HCM section for doses, page 130).