Page 183 - Feline Cardiology

184 Section D: Cardiomyopathies

HISTORY AND CHIEF COMPLAINT
Presenting complaints may include those consistent
with heart failure, including dyspnea, tachypnea, and
anorexia. Thromboembolic episodes do occur and
hindlimb paralysis may be noted. In some cases, although
RA much less commonly, the embolus may go to a forelimb
or to the brain where it results in asymmetric neurologic
signs.

Cardiomyopathies RV A soft heart murmur of mitral regurgitation may be
PHYSICAL EXAMINATION
LA
heard over the left apex and was detected in 13/77 cats
in one study (Sisson et al. 1991). An arrhythmia may be
ausculted and gallop sounds are frequently heard (79%)
LV
(Sisson et al. 1991).
Cats with taurine deficiency may have central retinal
lesions so a retinal evaluation may help identify increased
suspicion of taurine deficiency (Pion et al. 1987).

Figure 13.1. Heart from an adult cat with dilated cardiomyopa- DIFFERENTIAL DIAGNOSIS
thy. Note the large dilated left auricle (LA) and left ventricle (LV).
RA = right auricle; RV = right ventricle. The most common differential diagnoses include
unclassified cardiomyopathy and hypertrophic cardio­
myopathy with an infarct resulting in regional wall
hypokinesis.

Pathophysiology
DIAGNOSTIC TESTING
Dilated cardiomyopathy is a progressive myocardial
disease that appears to begin with a decrease in myocar­ Electrocardiography
dial systolic function and progresses to left ventricular The electrocardiogram may be within normal limits;
dilation. Increased left atrial pressure, pulmonary venous however, many arrhythmias have been observed includ­
congestion, and pulmonary edema develop as a result of ing sinus tachycardia and atrial or ventricular premature
the myocardial dysfunction and dilation. Biventricular complexes. Atrial fibrillation has been observed with
failure with pleural effusion is also often noted. feline DCM (Côté et al. 2007).
Thromboemboli and arrhythmias may also develop. Bradyarrhythmias including AV blocks have been
observed. Enlargement patterns consistent with left
Pathology atrial (P wave duration >0.04 seconds) and/or ventricu­
The left atrium and ventricle are typically dilated and in lar (R wave >0.9 mV in lead II) enlargement may be
severe cases all 4 chambers can be dilated (Figure 13.1). observed.
The left ventricular wall may appear to be thin but gen­
erally measures normally. Histopathologic findings are Radiography
nonspecific but can include myocytolysis, myofibril Radiographs may be consistent with cardiac disease but
fragmentation, and fibrosis. are not diagnostic for the specific form of cardiomyopa­
thy. Evidence of left or biventricular heart failure may be
SIGNALMENT observed including pulmonary edema or pleural effu­
Strong breed predispositions have not been observed; sion (Figure 13.2).
DCM has been reported in Persian, domestic shorthair,
domestic longhair, Birman, Siamese, and Burmese Echocardiography
breeds (Ferasin et al. 2003). Dilated cardiomyopathy is Dilated cardiomyopathy is diagnosed when the left ven­
an adult onset disease with an average reported age in tricle is found to be dilated (>11 mm at systole and/or
one study of 9 years of age (Ferasin et al. 2003). >16 mm in diastole). Systolic function is decreased with