Cardiomyopathy I: Introduction and Classification

Cardiomyopathy is a group of diseases affecting myocardial structure, impairing the heart's ability to pump blood effectively. This condition can cause arrhythmias, heart failure, or sudden cardiac death by disrupting normal cardiac contraction and relaxation patterns.

Primary cardiomyopathy involves only the heart muscle and is often idiopathic or genetic. Secondary cardiomyopathy occurs when other disease processes, such as coronary artery disease, hypertension, or systemic conditions like amyloidosis, damage the myocardium.

Dilated cardiomyopathy is marked by ventricular enlargement and systolic dysfunction with decreased ejection fraction. In contrast, hypertrophic cardiomyopathy involves thickening of the heart muscle, especially the interventricular septum, which obstructs blood flow and impairs diastolic function.

Restrictive cardiomyopathy is characterized by a rigid heart muscle that restricts ventricular filling during diastole while maintaining normal systolic function. Common causes include amyloidosis, sarcoidosis, hemochromatosis, and fibrosis from radiation or chemotherapy.

Arrhythmogenic right ventricular cardiomyopathy occurs when myocardium is progressively replaced by fibrous scar and adipose tissue, primarily affecting the right ventricle. This genetic condition involves mutations in genes encoding desmosomal proteins, leading to right ventricular dilation.

Unclassified cardiomyopathies do not fit neatly into standard classifications. Takotsubo cardiomyopathy, a stress-induced syndrome, is an example that causes apical ballooning and mimics acute coronary syndrome, requiring specialized nursing management.

Dilated cardiomyopathy may be idiopathic or caused by genetic mutations, alcohol abuse, chemotherapy drugs, toxins, muscular dystrophy, or myocarditis. These factors progressively damage the myocardium, leading to ventricular enlargement and systolic dysfunction.