Disorder - Hypertrophic cardiomyopathy

Organ Systems Involved
Cardiovascular

Alternative disorders described within LIDA

Acromegaly, Hypertension, Subaortic stenosis

Alternative Names
Ventricular hypertrophy, hypertrophic heart disease

Presenting Signs

Hypertrophic cardiomyopathy (HCM) is the most common heart disease of cats. In HCM, one of the four heart chambers, the left ventricle, cannot fill properly with blood. This is because abnormal thickening of the muscular wall reduces the size and flexibility of the chamber, leading to increased pressure within the heart. This can cause other chambers of the heart to become enlarged, especially the left atrium. HCM can exist with no symptoms in some cats or can cause severe disease in others. Signs include difficulty breathing due to pulmonary oedema, an accumulation of fluid within the lungs, or due to pleural effusion, an accumulation of fluid within the thoracic cavity. Because of sluggish blood flow within the left atrium, large clots can develop (thromboemboli), break off and become lodged downstream in the largest blood vessel, the aorta. These so called saddle-thrombi cause sudden paralysis of one or both hind limbs. HCM has been shown to be caused by two separate mutations in the myosin binding protein C (MYBC3) gene in Maine Coon and Ragdoll cats. The mode of inheritance is autosomal dominant. Not all cats that inherit the mutation will develop HCM. A genetic test is available to detect the mutation in these breeds of cats. Mutations in other cardiac heart muscle genes are suspected to cause other forms of HCM in these and other breeds of cats.

Cats at Risk

HCM occurs in both male and females and can affect both purebred and crossbred cats. Male cats tend to develop disease at an earlier age.

Breeds Affected
British Shorthair
Maine Coon
Norwegian Forest Cat
Ragdoll
Siberian
Sphynx


Treatment

Medical: Treatment aims to promote normal heart function by helping the ventricles to fill, controlling irregular heart beats, reducing congestion and preventing clots forming within the blood stream.

PubMed References
Hypertrophic cardiomyopathy

Contributor
Heather Shortridge