Giới thiệu
Hypertrophic Cardiomyopathy_Disease BackgroundHypertrophic cardiomyopathy is a genetically determined cardiac disorder characterized by hypertrophy, often of the left ventricle (LV), with non-dilated ventricular chambers and no other cardiac, systemic, or metabolic disease (eg aortic stenosis, thyroid disease, or hypertension) capable of producing the extent of hypertrophy manifested by the patient. The maximal end-diastolic LV wall thickness is ≥15 mm in adults, or the body surface area adjusted z-score is ≥2 standard deviations above the mean for age, sex, or body size in children. For the diagnosis of early hypertrophic cardiomyopathy in children, a threshold of a z-score >2.5 may be used in asymptomatic children without a family history and a threshold of a z-score >2 for children with a family history or a positive genetic test.
Dịch tễ học
Hypertrophic cardiomyopathy is the most common form of genetic cardiovascular disorder, occurring in one out of 500 individuals regardless of gender or race. This presents in all age groups with a prevalence of 0.2% in adults and 0.029% in children. The prevalence of hypertrophic cardiomyopathy rises with advancing age. This is an autosomal dominant inherited disorder, affected heterozygous individuals beget children with a 50% risk (equal risk for both males and females) of having the gene mutation. Although hypertrophic cardiomyopathy affects males and females equally, it is diagnosed less frequently in female patients than in male patients.
The rising prevalence and incidence of hypertrophic cardiomyopathy in Asian countries in recent decades are likely attributable to advancements in echocardiographic interpretation and heightened clinical awareness and recognition of the disease. Ethnic variations in hypertrophic cardiomyopathy have been observed, with a higher prevalence of apical hypertrophy among Asian and African American populations.
Nguyên nhân
Hypertrophic cardiomyopathy results from mutations in one of the cardiac sarcomere protein genes that encode the parts of the apparatus for contraction, such as actin, tropomyosin alpha-1 chain, myosin binding protein C, troponin I, troponin T, beta myosin heavy chain, and essential and regulatory light chains. The most common genes in patients with hypertrophic cardiomyopathy and a pathogenic sarcomeric gene variant are beta myosin heavy chain 7 (MYH7) and myosin-binding protein C3 (MYBPC3).
Sinh lý bệnh
The link between left ventricular hypertrophy (LVH) and the characteristic histopathologic features of the disease such as myofibrillar disarray and expanded interstitial space due to fibrosis, leads to the development of diastolic dysfunction, which is commonly observed in patients with hypertrophic cardiomyopathy.
The phenotype is characterized by abnormal, frequently focal hypertrophy that leads to atrial and ventricular arrhythmia, diastolic dysfunction, mitral regurgitation, dynamic LV outflow tract obstruction (LVOTO), pulmonary hypertension, myocardial ischemia, coronary insufficiency, and congestive heart failure. The pathophysiology also consists of metabolic and energetic abnormalities and potential autonomic dysfunction.