Restrictive Cardiomyopathy

Occurs when endocardial and myocardial fibrosis and thickening impair ventricular diastolic filling. Like hypertrophic cardiomyopathy, the atrium on the affected side dilates. Most often restrictive cardiomyopathy affects the left ventricle and congestive heart failure can develop. Signs and treatment are similar to those of hypertrophic cardiomyopathy. Restrictive cardiomyopathies are rare and are mentioned here only for completeness.

Described clinically in cats and cattle. There is fibrosis and thickening of the left ventricle which allows decreased filling and so diastolic dysfunction. There is left atrial dilation to cope with the increased difficulty in filling the left ventricle and this predisposes to thromboembolic disease. Atrial fibrillation is also a common finding.

Clinical signs:

Left sided heart failure and so:

• Pulmonary oedema, plus...
• Thromboembolism, usually hindlimb paralysis.

In cattle the disease appears to have an inherited pathogenesis. Disease is seen in:

• Polled Herefords with curly hair coats.
• Friesian Holsteins with a common sire.