Sudden cardiac death in sport.
Translation Sudden_cardiac_death_of_athletes#DNA_testing from the English Wikipedia as of 2018-12-16
training Kit defibrillation
still a difficult medical task is to prevent sudden cardiac death athletes, usually defined as natural, unexpected death from cardiac arrest within one hour after the onset of symptoms attack excluding extra time on mechanical life support. (A more broad definition of sudden death is also used, but is not usually applied to sports situations.) Most causes related to congenital or acquired cardiovascular disease without any symptoms, marked up to the fatal event. A single prevalent condition unlikely - probability less than 0.3% for age group athletes. the Sensitivity and specificity of conventional screening tests is poor. The single most important predictor is loss of consciousness or fainting during exercise* that require detailed explanation and investigation. Among the victims were many well-known, especially in professional football. Close relatives are often at risk for the same heart problems.
Causes
the medical review of the 2003 were analyzed sudden cardiac death 387 young American athletes (under 35 years):
Hypertrophic кардиомиопатия26%Genes определяетсяCommotio cordis20%Structurally normal heart, is electrically destroyed by the blow to gradientului coronary артерии14%Exact mechanisms are unknown; some connection with other congenital anomalies CVSГипертрофия left ventricular uncertain происхождения7%Probable hypertrophic кардиомиопатииМиокардит5%vospalitiona Acute aortic aneurysm ( Marfan syndrome )3% Genetically determined; also associated with high right ventricular rosemarydragon кардиомиопатия3%Genetically opredelennaya coronary артерия3%Congenital aortic anomalities клапана3%Several pricenitroglycerin disease coronary артерий3%mainly acquired; the main reason older rudakovoy диагноз13%
while most causes of sudden cardiac death associated with congenital or acquired cardiovascular disease , an exception is commotio cordis, where the heart is structurally normal but a potentially fatal loss of rhythm due to an accident - a blow to the chest. The mortality rate is approximately 65% even with rapid CPR and defibrillation, and more than 80% without it.
35 years - the approximate boundary of the probable causes of sudden cardiac death. To 35 years is dominated by congenital malformations of the heart and blood vessels. They are usually asymptomatic to fatal events, although not always. Congenital cardiovascular deaths occur more often in African-American athletes.
After 35 years prevails acquired coronary heart disease (80%), and it does not depend on previous training level of the athlete.
Genetics
Cardiomyopathy
Arrhythmogenic right ventricular dysplasia showing fatty infiltration of right and left ventricle and mild reduction of right ventricular
Cardiomyopathies are typically inherited as autosomal dominant, although there have been described a recessive form, and dilated cardiomyopathy can also be inherited in X-linked scheme. Therefore, in addition to the tragic death of an athlete, there are medical implications for close relatives. Among family members in cases identified more than 300 mutations, which served as the reason. However, not all mutations have the same potential and lead to serious consequences, and there is no clear understanding of how these mutations (which affect the same protein molecule myosin) can lead to dramatically different clinic and the results associated with hypertrophic cardiomyopathy (HCM) and dilated cardiomyopathy (DCM).
Because, for example, HCM is usually an autosomal dominant, each child of a parent with hypertrophic cardiomyopathy has a 50% chance of inheriting the mutation. In people without a family history the most common cause of the disease is a de novo mutation of the gene that encodes the protein β-myosin.
Channelopathies
Sudden cardiac death can usually be attributed to cardiovascular disease or commotio cordis, but about 20% of cases have no clear cause and remain undiagnosed after opening. Interest in these "negative autopsy" the deaths were concentrated around the "ion channels". These channels are conducting current molecules since. They regulate the movement of ions of sodium, potassium and calcium in the heart cells. Collectively responsible for creating and monitoring the electrical signals that regulate the heart rhythm. The anomalies of this system occurs when a relatively rare genetic diseases such as the syndrome of the prolonged QT interval (each 2000), Brugada syndrome, and Catecholaminergic polymorphic ventricular tachycardia. They are all linked with sudden death. Consequently, sudden cardiac death with a negative autopsy (no physical violations were not identified) can provide a larger part than previously thought.
the Degeneration of aortic valve, common in Marfan syndrome
Hereditary connective tissue diseases are rare, each disorder estimated at one to ten per 100,000 people, of which Marfan syndrome is the most common. He tolerated gene FBN1 on chromosome 15, which encodes the connective protein fibrillin-1, is inherited as a dominant trait. This protein is essential for the synthesis and maintenance of elastic fibers. Because these fibers are particularly common in the aorta , ligaments and ciliary zones of the eyes, these regions suffer more. Everyone has a pair of FBN1 genes and because transfer is dominant in those who have inherited one affected FBN1 gene from either parent will be Marfan syndrome. Although it is most often inherited as an autosomaldominant, in 25% of cases family history is missing.
Recruiting practices aimed at attracting athletes who are unusually tall or unusually wide arm span (the features of Marfan syndrome), may increase the prevalence of the syndrome in such sports as basketball and volleyball.
DNA Testsonce the disease causing mutation was identified in the index case (which was not always executed completely), the main task is genetic identification of carriers within a pedigree, a consistent process known as "cascade testing." Family members with the same mutation can exhibit different degrees of severity of the disease, a phenomenon known as "incomplete penetrance". As a result, some of them may remain asymptomatic, with little evidence of the disease throughout life. However, their children still run the risk of inheriting the disease and may suffer more seriously.
Screening
See also: Screening for hypertrophic cardiomyopathy
Echocardiogram showing the left ventricle
Screening of athletes for heart disease can be difficult because low-prevalence and inaccuracies of different tests that were used. However, sudden death among seemingly healthy people are attracted great attention of the public and lawmakers because of its visible and tragic nature.
for Example, the Legislature of Texas has allocated 1 million USD for a pilot study of screening athletes across the state in 2007. The study used a combination of questionnaire, examination and ECG for 2506 athletes students and then echocardiography to 2051, including all students with abnormal results of the first three steps. At the stage of questioning marked 35% of students as potentially at risk, but there were a lot of false positives, with actual confirmation of the disease in less than 2%. In addition, a significant number of students with a positive result rejected repeated recommendations for further assessment. (People who have definitively diagnosed with heart disease, it is usually said that you should avoid competitive sports.) It should be emphasized that it was one of the pilot program, but it has shown the problems associated with large-scale screening, and consistent with the experience of other places with a low prevalence of sudden death in athletes.
Incidence
Sudden cardiac death occurs in approximately one in 200 000 young athletes per year, which usually occurs during competition or training. The victim is usually male and is associated with football, basketball, hockey or American football, which reflects a large number of athletes participating in these long and strenuous sports. In a normal healthy age group the risk is particularly high in competitive basketball with a frequency of sudden cardiac deaths 3000 per year, for basketball players male in the Department of INCAA. It's still is much lower than for the General population, estimated as one-on-1300-1600, with a predominance of elderly. However, such a large population as the United States, will meets with sudden cardiac death of an athlete at an average frequency of one two or three times a day, often with significant coverage in the local media, raising attention public.
* Precision medicine along with the growth of databases (based on electronic health records and new-generation sequencing) every day allows all the ability to predict risks. Including for cases where absence of masks fainting cardiac pathology for some of the mutations in certain domains of the protein ion channel [translator's note].