Heart Disease in Cats
The last categories of cardiomyopathies in the cat delve into areas of veterinary science that are still in their infancy. Click here to learn about hypertrophic cardiomyopathy. Intermediate/ restrictive/ unclassified cardiomyopathies (ICM/RCM/UCM respectively) describe a litany of different cardiac lesions. Where the abnormalities in the previous categories are seen in systole (heart contraction), these are diastolic (heart filling) dysfunctions. Essentially, the ventricle does not fill correctly. This can happen due to scarring of the ventricle muscle, or changes in a number of the structures within the ventricle and valve. Click here to learn about the normal functioning of a cat heart.
Diagnosis of RCM/UCM
Diagnosis is challenging due to a number of things. First, evaluating the changes in pressures of the different chambers of the heart is much more challenging in the cat as opposed to humans, where these diseases are diagnosed with greater confidence and ease. The heart rate is too fast in a cat. In addition, catheterizing the heart of a cat is a much greater challenge due to size than humans.
The significant difference that a veterinarian may note is that the ventricle itself does not typically change in size as in HCM and DCM. In addition, there are no defects in the mitral valve causing backflow. A highly skilled cardiologist may note changes in the appearance of the walls themselves as they image the heart. There are a number of different changes in the heart that veterinary medicine simply has not classified yet, and many of those are grouped together in the UCM category.
Since so little is known about the diseases themselves, even less is known about heritability. Some studies suggest a higher incidence in male cats, though this has not been repeatable.