Page 184 - Feline Cardiology

Chapter 13: Dilated Cardiomyopathy 185

RV

LV

A Cardiomyopathies
Figure 13.3. M-mode echocardiogram of left ventricle from an
adult cat with dilated cardiomyopathy. Note the large dilated left
ventricle (LV) with decreased wall motion. RV = right ventricle.

Additional Diagnostics
Due to the possibility that dilated cardiomyopathy may
be associated with taurine deficiency, taurine should
always be measured even in cats whose owners report
that they are on a balanced feline diet. Taurine may be
measured in plasma (>60 nmol/ml) and/or whole blood
(>250 nmol/ml). Whole blood may be less affected by
fasting, which could be associated with an inappetant
cat (Pion et al. 1991). Taurine can be released from
platelets if the plasma sample is not separated quickly
enough and it might appear falsely elevated. Other
apparent reasons for false elevation can include skeletal
B muscle necrosis as might be observed with thromboem­
bolic disease.
Figure 13.2. Radiographs from a cat with dilated cardiomy- Some cats with taurine deficiency have evidence of
opathy and congestive heart failure; both pleural effusion and central retinal degeneration, so an optic exam may be
pulmonary edema are present. (A) = lateral view; (B) = dorsoventral helpful. However, the absence of retinal degeneration
view.
does not exclude taurine deficiency.

Diagnosis
a left ventricular fractional shortening <20% (Figure Evidence of left ventricular systolic dysfunction with a
13.3). Usually the systolic dysfunction precedes the dila­ fractional shortening of less than 20% is highly sugges­
tion. Left atrial enlargement is often observed as well. In tive of feline dilated cardiomyopathy, particularly with
some cases, right atrial and ventricular dilation may be evidence of left ventricular dilation. Early reports sug­
observed. gested that measurement of wall thickness for wall thin­
Doppler findings typically demonstrate mitral regur­ ning might be a reliable criteria but this has not been
gitation. Mitral valve inflow velocities may demonstrate found to be reliable. In many cases, the wall appears
relaxation abnormalities including an increased isovolu­ thinner simply due to the ventricular dilation but actu­
metric relaxation time, an E wave that may have a ally is a normal thickness.
reduced peak velocity, and increased A wave velocity Decreased taurine levels taken in conjunction with
(low E:A ratio) (see Chapter 11) as well as systolic dys­ echocardiographic evidence of systolic dysfunction sug­
function (Luis Fuentes 2003). gests taurine­related dilated cardiomyopathy.