Hypertrophic cardiomyopathy
| Hypertrophic cardiomyopathy | |
|---|---|
| Synonyms | Asymmetric septal hypertrophy, idiopathic hypertrophic subaortic stenosis |
 |
|
| Classification and external resources | |
| Specialty | Cardiology |
| ICD-10 | I42.1–I42.2 |
| ICD-9-CM | 425.1 |
| OMIM | 192600 |
| DiseasesDB | 6373 |
| MedlinePlus | 000192 |
| eMedicine | med/290 ped/1102 radio/129 |
| Patient UK | Hypertrophic cardiomyopathy |
| MeSH | D002312 |
Hypertrophic cardiomyopathy (HCM) is a disease in which a portion of the myocardium (heart muscle) is enlarged without any obvious cause, creating functional impairment of the heart. It is the leading cause of sudden death in young athletes. The occurrence of hypertrophic cardiomyopathy is a significant cause of sudden cardiac death in any age group and a cause of disabling cardiac symptoms. HCM is frequently asymptomatic until sudden cardiac death, and for this reason some suggest routinely screening certain populations for this disease. In most patients, HCM is associated with little or no disability and normal life expectancy.
A cardiomyopathy is a disease that affects the muscle of the heart. With HCM, the myocytes (cardiac contractile cells) in the heart increase in size, which results in the thickening of the heart muscle. In addition, the normal alignment of muscle cells is disrupted, a phenomenon which is known as myocardial disarray. HCM also causes disruptions of the electrical functions of the heart.
HCM is most commonly due to a mutation in one of nine sarcomeric genes that results in a mutated protein in the sarcomere, the primary component of the myocyte (the muscle cell of the heart). These are predominantly single-point missense mutations in the genes for the beta-myosin heavy chain (MHC), myosin-binding protein C, cardiac troponinT, or tropomyosin. These mutations cause myofibril and myocyte structural abnormalities and possible deficiencies in force generation.
While most literature so far focuses on European, American, and Japanese populations, HCM appears in all ethnic groups. The prevalence of HCM is about 0.2% to 0.5% of the general population.
The clinical course of HCM is variable. Many patients are asymptomatic or mildly symptomatic. The symptoms and signs of HCM include shortness of breath (dyspnea) due to stiffening and decreased blood filling of the ventricles, exertional chest pain (sometimes known as angina) due to reduced or restricted blood flow (ischemia) to the coronary arteries, uncomfortable awareness of the heart beat (palpitations) due to the aforementioned ischemia, as well as disruption of the electrical system running through the abnormal heart muscle, lightheadedness, fatigue, fainting (called syncope) and sudden cardiac death. As mentioned, dyspnea is largely due to increased stiffness of the left ventricle (LV), which impairs filling of the ventricles, but also leads to elevated pressure in the left ventricle and left atrium, causing back pressure and interstitial congestion in the lungs. Symptoms are not closely related to the presence or severity of an outflow tract gradient. Often, symptoms mimic those of congestive heart failure (esp. activity intolerance and dyspnea), but treatment of each is different. Beta blockers are used in both cases, but treatment with diuretics, a mainstay of CHF treatment, will exacerbate symptoms in hypertrophic obstructive cardiomyopathy by decreasing ventricular preload volume and thereby increasing outflow resistance (less blood to push aside the thickened obstructing tissue).
...
Wikipedia