- Hypertrophic Cardiomyopathy (HCM)
a) Definition: HCM is a genetic disorder that causes thickening of the heart muscle, especially the left ventricle, leading to impaired diastolic filling.
b) Etiology: HCM is primarily caused by genetic mutations that affect the sarcomere, the basic contractile unit of the heart muscle. In some cases, the condition can also be acquired due to other factors, such as high blood pressure, obesity, and diabetes.
c) Pathogenesis: The thickening of the heart muscle in HCM is caused by an abnormal increase in the size and number of muscle cells, leading to disorganization of the muscle fibers. This, in turn, results in impaired relaxation of the heart during diastole, leading to decreased blood filling of the ventricles.
d) Morphology: In HCM, the left ventricular wall is usually thickened, which can be asymmetric or diffuse. The septum that divides the left and right ventricles may also be thickened, causing a narrowing of the outflow tract.
e) Clinical features: The clinical presentation of HCM is highly variable and can range from asymptomatic to sudden cardiac death. Symptoms may include chest pain, shortness of breath, palpitations, fatigue, and fainting spells.
2. Restrictive Cardiomyopathy (RCM)
a) Definition: RCM is a rare type of cardiomyopathy in which the heart muscle becomes stiff and less compliant, leading to impaired filling of the ventricles.
b) Etiology: RCM can be caused by various factors, such as amyloidosis, sarcoidosis, hemochromatosis, and radiation therapy.
c) Pathogenesis: The stiffening of the heart muscle in RCM is caused by the deposition of abnormal proteins or fibrosis, leading to reduced relaxation of the heart during diastole.
d) Morphology: The heart muscle in RCM appears grossly normal, but there may be diffuse fibrosis and amyloid deposition, leading to a "waxy" appearance.
e) Clinical features: The symptoms of RCM are similar to those of heart failure, such as shortness of breath, fatigue, and edema. However, RCM may also present with systemic features of the underlying disease, such as weight loss and skin rash.
3. Dilated Cardiomyopathy (DCM)
a) Definition: DCM is a type of cardiomyopathy in which the heart muscle becomes enlarged and weakened, leading to decreased contractility.
b) Etiology: DCM can be caused by various factors, such as viral infections, alcohol abuse, drugs, and genetic mutations.
c) Pathogenesis: The enlargement and weakening of the heart muscle in DCM are caused by various mechanisms, such as inflammation, oxidative stress, and impaired calcium handling, leading to reduced contractility of the heart muscle.
d) Morphology: In DCM, the heart muscle is enlarged and dilated, with thinning of the walls. The ventricles may also be spherical in shape.
e) Clinical features: The symptoms of DCM are similar to those of heart failure, such as shortness of breath, fatigue, and edema. DCM may also present with arrhythmias and sudden cardiac death.