Ventricular diseases can be defined as congenital or acquired disorders of the myocardium which cause ventricular dysfunction. This chapter primarily focuses on salient, clinical, and echocardiographic features of cardiomyopathies, but also includes discussion of other ventricular pathologies such as myocarditis and ventricular rupture.
Cardiomyopathies represent a heterogeneous group of pathological diseases of the myocardium caused by electromechanical dysfunction of the heart (Figure 21-1) but does not include myocardial dysfunction secondary to valvular heart disease, systemic hypertension, congenital heart disease, and atherosclerosis. Cardiomyopathy often leads to progressive heart failure with symptoms of shortness of breath, fatigue, cough, orthopnea, and paroxysmal nocturnal dyspnea and is associated with significant morbidity and mortality.
Diagrammatic representation of various types of cardiomyopathies depicting (A) a healthy heart; (B) dilated cardiomyopathy with thin ventricular walls, dilated ventricles and atria; (C) hypertrophic cardiomyopathy with asymmetric ventricular hypertrophy and left ventricular outflow tract obstruction; (D) restrictive cardiomyopathy with thickened atria and stiffened ventricles; (E) left ventricular noncompaction cardiomyopathy with trabeculated ventricular walls; and (F) Takotsubo cardiomyopathy with apical ballooning of left ventricle and resemblance to the takotsubo—a Japanese fishing pot used to trap octopus.
Cardiomyopathies are actually the result of genetic mutations with significant phenotypic and genetic heterogeneity. The crossover of some cardiomyopathies into different subcategories means that different classifications are proposed by various organizations (Table 21-1).1,2
Table 21–1.Classification of cardiomyopathies as proposed by the European Society of Cardiology Working Group ||Download (.pdf) Table 21–1. Classification of cardiomyopathies as proposed by the European Society of Cardiology Working Group
|Etiology ||Hypertrophic ||Dilated ||Arrhythmogenic ||Restrictive ||Unclassified |
|FAMILIAL ||Sarcomeric protein mutations ||Sarcomeric protein mutations ||Intercalated disc protein mutations ||Sarcomeric protein mutations ||Noncompaction |
|Glycogen/lysosomal storage diseases ||Cytoskeletal gene mutations ||Ryanodine receptor mutation ||Amyloidosis ||Barth syndrome |
|Metabolic disorders ||Nuclear membrane ||Transforming growth factor-β3 ||Desminopathy || |
|Mitochondrial disorders ||Mitochondrial disorders || ||Hemochromatosis || |
|Hypertrophic cardiomyopathy syndromes (e.g., Noonan) ||Z-band protein disorders || ||Anderson-Fabry disease || |
| ||Intercalated disc protein mutations || ||Glycogen storage disease || |
|NONFAMILIAL ||Obesity ||Myocarditis ||Inflammatory ||Amyloid ||Takotsubo |
|Athlete's heart ||Kawasaki disease || ||Scleroderma || |
|Amyloid ||Eosinophilic disease || ||Endomyocardial fibrosis || |
| ||Drugs || ||Carcinoid disease || |
| ||Pregnancy || ||Metastatic malignancies || |
| ||Nutritional deficiencies || ||Radiation || |
| ||Alcohol abuse || ||Drugs || |
Primary cardiomyopathies (genetic, nongenetic, acquired) are those confined to heart muscle, while secondary cardiomyopathies exhibit myocardial involvement as part of systemic disorders (Table 21-2). Mutant proteins in cardiomyocytes affect the contractile apparatus, which affects cardiac function and may cause sudden cardiac death and heart failure.3
Table 21–2.Classification of cardiomyopathies as proposed by American Heart Association