A comprehensive review of hypertrophic cardiomyopathy and arterial thromboembolism in cats

Abstract

The number of cats requiring treatment for hypertrophic cardiomyopathy (HCM) and arterial thromboembolism (ATE) continues to increase, and the knowledge regarding its management is constantly evolving. The pathological lesions of HCM include hypertrophy of the left ventricle, which causes abnormalities in the relaxation function of the heart. This phenomenon increases the stiffness of the ventricular muscle, thereby reducing the ability of the left ventricle to fill with blood during diastole. This is accompanied by an increase in ventricular filling pressure and left atrial pressure. HCM in cats is characterized by concentric hypertrophy and atrial enlargement. Hypertrophic obstructive cardiomyopathy (HOCM) also involves a narrowed left ventricular outflow tract, and in humans, it is generally perceived to be a more serious disease. However, unlike in humans, HCM and HOCM in cats do not result in significantly different survival times. Heart murmurs, gallop rhythms, arrhythmias, cardiac hypertrophy, congestive heart failure (CHF), ATE, and cardiac sudden death (CSD) have all been associated with HCM. Although the presence of a heart murmur is a characteristic feature of heart disease, it may be a functional one, which is defined as “dynamic right ventricular outflow track obstruction” (DRVOTO) in cats. Therefore, it is difficult to evaluate the presence of HCM based on the existence of a heart murmur alone. ATE typically affects one or both hind limbs, resulting in acute paralysis and severe pain, consistent with lower motor neuron disease. The clot, which is formed in the left atrium of the heart, travels to an artery and becomes an ATE, which then blocks the blood flow and impairs circulation, causing infarction. Therefore, ATE in cats is a serious condition. This review describes the results of the latest research on HCM and ATE, the most common heart conditions in cats.