CARDIOLOGY

comparative imagery

Enlarged
Heart:Feline
Darcy Adin, DVM, Diplomate ACVIM (Cardiology), University of Florida

CARDIOMEGALY is a common feature of cardiac disease in

cats. Both thoracic radiography and echocardiography are necessary to ade-
quately define the type and severity of cardiac disease in this species. Thoracic
radiographs are useful to detect cardiomegaly and the presence or absence of
congestive heart failure; however, the specific underlying cardiac disease cannot
be determined with radiography in cats. Echocardiography is useful for charac-
terization of the underlying cardiac disease (e.g., hypertrophic cardiomyopathy, 2a
dilated cardiomyopathy, restrictive cardiomyopathy, unclassified cardiomyopa-
thy); however, it cannot provide information on whether pulmonary venous con- Enlarged. Dorsoventral radiograph of the thorax
showing moderate to severe cardiomegaly, prominent
gestion and edema are present. Thoracic radiography and echocardiography vasculature, and a diffuse bronchointerstitial pattern
consistent with cardiogenic pulmonary edema. The
should be considered complementary imaging methods for the feline patient width of the cardiac silhouette is more than two thirds
the width of the thorax, indicating cardiomegaly. This
with cardiac disease, as demonstrated in this article. Normal images are provid- radiograph demonstrates the classic “valentine heart”
ed for comparison. appearance, which is not specific for any particular
type of cardiomyopathy in cats. (73% original size)

1a 1b
Enlarged. Lateral radiograph of the thorax of a cat showing a tall, wide cardiac sil- Normal. Lateral radiograph of the thorax of a normal cat for comparison. The
houette indicating moderate to severe generalized cardiomegaly. The vertebral heart cardiac silhouette is normal in size. The pulmonary parenchyma and vasculature are
score is 9.5 vertebrae, which is higher than normal (upper limit of normal is 8 vertebrae). also normal. The vertebral heart score is 7.7, which is within normal limits. (119%
The pulmonary vasculature is prominent and a mild, diffuse bronchointerstitial pattern is original size)
present, consistent with mild cardiogenic pulmonary edema. (101% original size)

4 2 . . . . . m ay. 2 0 0 4 . . . . . N AV C c l i n i c i a n’s b r i e f . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . co m p a ra t i ve i m a g e r y
 Interventricular Interventricular
septum septum

Left

3a Papillary muscle
ventric-
ular free
wall

Enlarged. Right-sided, short-axis

echocardiogram showing concentric hyper- 3b Papillary muscle
Left
ventricular
free wall
trophy of the left ventricular walls. The inter-
ventricular septum focally measured 6.8 mm,
and the left ventricular free wall measured
Normal. Right-sided, short-axis echocardiogram of
a normal cat for comparison. The interventricular sep-
6.5 mm in diastole (normal, < 5.5 mm).
tum measured 5.0 mm, and the left ventricular free
Hypertrophy is also present in the papillary
wall measured 3.5 mm in diastole, indicating normal
2b muscles. In the absence of hypertension and
hyperthyroidism, these findings are consis-
tent with hypertrophic cardiomyopathy.
left ventricular wall thicknesses (normal, <5.5 mm). The
papillary muscles are also of normal size.

Normal. Dorsoventral radiograph of the thorax of a nor- Left ventricle Left ventricle
mal cat for comparison. The cardiac silhouette is normal in Aorta
size, occupying less than two thirds of the thoracic width. The
pulmonary parenchyma and vasculature are also normal.
(100% original size)

All echocardiograms are shown at their original size. 4a Left atrium

Enlarged. Right-sided, long-axis

echocardiogram showing concentric hyper-
trophy of the left ventricular walls. In the
4b Left atrium

absence of hypertension and hyperthy-

roidism, this finding is consistent with hyper- Normal. Right-sided, long-axis echocardiogram of a
trophic cardiomyopathy. normal cat for comparison. Left ventricular wall thick-
ness is normal.

Aorta Aorta Aorta

Left ventricle

5a 5b 5c Left atrium
Left atrium Left atrium
Right-sided, short-axis echocardiogram with color
Enlarged. Right-sided, short-axis echocardiogram Normal. Right-sided, short-axis echocardiogram Doppler superimposed. The Doppler signal shows a sys-
showing severe left atrial enlargement. The left atrial- from a normal cat for comparison. The left atrial-to- tolic turbulent jet of left ventricular outflow obstruction
to-aortic ratio is 3.1, which indicates severe left atrial aortic ratio of 1.3 is normal and indicates normal left and mitral regurgitation. This flow disturbance occurs
enlargement (normal ratio, < 1.5). atrial size. because of mitral valve systolic anterior motion, which
is a common finding in hypertrophic cardiomyopathy.

co m p a ra t i ve i m a g e r y . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. . . . . . N AV C c l i n i c i a n’s b r i e f. . . . . m ay. 2 0 0 4 . . . . . 4 3