Cardiomyopathy

Disease of the heart muscle (the myocardium). The word is made up of three Greek roots: "cardio-", heart + "mys", muscle + "pathos", disease = disease (of the) heart muscle. The World Health Organization (WHO) restricts term "cardiomyopathy" to: "Primary disease process of heart muscle in absence of a known underlying etiology" referring to idiopathic cardiomyopathy (cardiomyopathy of unknown origin). However, a disorder called hypertrophic cardiomyopathy (HCM) is of genetic origin. It is characterized by increased growth (hypertrophy) in thickness of the wall of the left ventricle, the largest of the four chambers of the heart. HCM can surface any time in life. It may, in a worst-case scenario, lead to death. It is the leading cause of sudden death in athletes and young people. A measurement of the thickness of the left ventricle wall can predict who is most at risk for HCM. The test is done by echocardiography, a routine ultrasound test of the heart. Persons with a maximum wall thickness less than three-quarters of an inch (19 mm) are virtually free of risk for fatal cardiac arrest over 20 years whereas those with a wall thickness more than 1.2 inches (30 mm) have a 40% chance of fatal cardiac arrest during that time period. Patients in danger can be fitted with implantable defibrillators, which can shock a spasmodic heart back to life. The disease exhibits an autosomal dominant pattern of inheritance. Men and women with HCM stand a 50-50 chance of transmitting the HCM gene to each of their children. There are various kinds of HCM (symmetrical, asymmetrical forms, etc.). HCM is sometimes called familial hypertrophic cardiomyopathy.

* * *

Disease of the myocardium. As a disease classification, the term is used in several different senses, but is limited by the World Health Organization to: “Primary disease process of heart muscle in absence of a known underlying etiology” when referring to idiopathic c.. SYN: myocardiopathy. [cardio- + G. mys, muscle, + pathos, disease]

- alcoholic c. myocardial disease occurring in some chronic alcoholics; may result from alcohol toxicity, thiamin deficiency, or be of unknown pathogenesis. SYN: alcoholic myocardiopathy, beer heart.

- congestive c. SYN: dilated c..

- dilated c. decreased function of the left ventricle associated with its dilation; most patients have global hypokinesia, although discrete regional wall movement abnormalities may occur; usually manifested by signs of overall cardiac failure, with congestive findings, as well as by fatigue indicative of a low output state. SYN: congestive c..

- familial hypertrophic c. familial occurrence of hypertrophic c. exhibiting an autosomal dominant pattern of inheritance. Familial c. of various kinds occurs with autosomal dominant inheritance [MIM*115200]. There is also an asymmetrical form affecting the ventricles and the interventricular septum [MIM*192600].

- hypertrophic c. thickening of the ventricular septum and walls of the left ventricle with marked myofibril disarray; often associated with greater thickening of the septum than of the free wall resulting in narrowing of the left ventricular outflow tract and dynamic outflow gradient; diastolic compliance is greatly impaired.

- idiopathic c. SYN: primary c. (1).

- peripartum c. cardiac failure due to heart muscle disease in the period before, during, or after delivery.

- postpartum c. cardiomegaly and congestive heart failure developing in the puerperium in the absence of any of the known causes of heart disease.

- primary c. 1. c. of unknown or obscure cause; SYN: idiopathic c.. 2. a disease that affects mainly the heart muscle, sparing other cardiac structures and usually resulting in fibrosis, hypertrophy, or both.

- restrictive c. a diverse group of conditions characterized by restriction of diastolic filling; often confused with constrictive pericarditis and the infiltrative cardiomyopathies; left ventricular size and systolic function may be preserved but dyspnea results primarily from increase in left ventricular diastolic pressure; signs of right ventricular failure may be prominent.

- secondary c. disease that affects the myocardium secondarily to systemic disease, infection, or metabolic disease.

* * *

car·dio·my·op·a·thy 'kärd-ē-ō-(.)mī-'äp-ə-thē n, pl -thies any structural or functional disease of heart muscle that is marked esp. by hypertrophy of cardiac muscle, by enlargement of the heart, by rigidity and loss of flexibility of the heart walls, or by narrowing of the ventricles but is not due to a congenital developmental defect, to coronary atherosclerosis, to valve dysfunction, or to hypertension

* * *

n.

any chronic disorder affecting the muscle of the heart. It may be inherited but can be caused by various conditions, including virus infections, alcoholism, beriberi (vitamin B₁ deficiency), and amyloidosis. The cause is often unknown. It may result in enlargement of the heart, heart failure, arrhythmia, and embolism. There is often no specific treatment but patients improve following the control of heart failure and arrhythmias.

* * *

car·dio·my·op·a·thy (kahr″de-o-mi-opґə-the) [cardio-(1) + myopathy] 1. a general diagnostic term designating primary noninflammatory disease of the heart muscle, often of obscure or unknown etiology and not the result of ischemic, hypertensive, congenital, valvular, or pericardial disease. It is usually subdivided into dilated, hypertrophic, and restrictive c. 2. In World Health Organization nomenclature, only those disorders in which the pathological process involves solely the myocardium and in which the cause is unknown and not part of a disease affecting other organs; called also primary c. Cf. secondary c.