The progression to<unk>  cardiomyopathy usually involves the mutations in contractile sarcomeric proteins of myocardium, which describe the presence of left ventricular hypertrophy (LVH) in the absence of an increased external load (unexplained LVH). Additionally, HCM hypertrophy is generally asymmetric.
HCM is the most common genetically transmitted cardiovascular disease.<unk>  cardiomyopathy is inherited as an autosomal dominant trait and is attributed to mutations in one of a number of genes that encode for one of the sarcomere proteins. Penetrance of HCM is incomplete, variable and time or age-related.  The disease may be sporadic but affected family members are discovered in 13% of cases.  More than 200 mutations involving at least 10 chromosomes encoding structural proteins of the myocyte have been discovered.  These mutations have varying degrees of penetrance and even the same mutation may have variable expression, implying the superimposed effects of other genes or environmental influences.   Children of a patient with HCM have a 50% chance of inheriting the trait.
Depending on the degree of obstruction of the outflow of blood from the left ventricle of the heart, HCM can be defined as obstructive or non-obstructive. About 25% of individuals with HCM demonstrate an obstruction to the outflow of blood from the left ventricle during rest. In other individuals, obstruction only occurs under certain conditions. This is known as dynamic outflow obstruction because the degree of obstruction is variable and is dependent on the amount of blood in the ventricle immediately before ventricle systole (contraction).
Although there may be structural or functional obstruction of the left ventricular outflow tract, symptoms may arise more often from diastolic dysfunction.There is extensive periarteriolar fibrosis that results in microvascular dysfunction and impairment in coronary flow reserve in patients with<unk>  obstructive cardiomyopathy. Individuals with HCM have some degree of left ventricular hypertrophy. In approximately 2/3rds of cases this is asymmetric hypertrophy, involving the interventricular septum, and is known as asymmetric septal hypertrophy (ASH). This is in contrast to the symmetric and concentric hypertrophy seen in aortic stenosis or hypertension. On histopathologic examination,<unk>  cardiomyopathy is characterized by both myocardial disarrays and by periarteriolar fibrosis. Myocardial disarray can be associated with aberrant impulse conduction and arrhythmias, and periarteriolar fibrosis can be associated with myocardial ischemia.
Hypertrophic cardiomyopathy pathophysiology
Stress cardiomyopathy pathophysiology
Dilated cardiomyopathy pathophysiology
Alcoholic cardiomyopathy pathophysiology
Noncompaction cardiomyopathy embryology
Ventricular remodeling pathophysiology
Bicuspid aortic stenosis pathophysiology
Noncompaction cardiomyopathy genetics