Page 205 - Feline Cardiology

208 Section E: Other Forms of Structural Heart Disease

Pathophysiology Radiography
The function of the moderator band is not known, but Radiographs are nonspecific and may indicate evidence
proposed functions include preventing overdilation of of heart failure, including pulmonary edema and/or
the ventricle during diastole and passage of Purkinje pleural effusion.
fibers from IVS to the left ventricular free wall (Liu et al.
1982). Echocardiography
Characteristic echocardiographic features of this disease
Pathology include one or multiple isoechoic bands of tissue extend-
The moderator band can be a large trabecular band or ing from the left ventricular free wall to the septum.
many small trabecular bands that divide the ventricle. Papillary muscle involvement may be observed.
Histologically the moderator band is characterized by Diagnosis
central Purkinje fibers and dense parallel collagenous
Misc. Heart Diseases Signalment tification of muscular bands dissecting the left ventricle,
Definitive diagnosis of this disease is by necropsy iden-
fibers covered by endothelium (Liu and Fox 1999).
which are characterized on histopathology as moderator
bands. Characteristic echocardiographic abnormalities
Excessive moderator bands have been observed in
provide a supportive but not definitive diagnosis of this
very young kittens as well as cats as old as 13 years (Liu
et al. 1982). A gender predisposition has not been
observed. disease.
Treatment
Excessive moderator bands may be an incidental finding
History and Chief Complaint
in an asymptomatic cat. In these cases, no treatment is
There is no specific clinical presentation for excessive needed. If clinical signs of heart failure are observed,
moderator bands. In a large study of 21 cats with exces- standard heart failure therapy and possible prophylactic
sive moderator bands, the most common clinical signs anticoagulation may be initiated (see Chapters 19 and
included lethargy, dyspnea, paraparesis, and syncope 20).
(Liu et al. 1982). However, since many of the cats also
had additional cardiac disease, it is possible that the Outcome and Prognosis
clinical signs were associated with concurrent cardiac
diseases. Prognosis and clinical importance of excessive modera-
tor bands is poorly understood and likely depends on
Physical Examination the presence of other additional cardiac disease.
Physical examination findings include hypothermia, a
heart murmur, and a gallop. Cats may display clinical REFERENCES
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