Sudden cardiac death
|Sudden cardiac death|
|Classification and external resources|
Signs and symptoms
Signs of sudden cardiac death include the following:
- loss of consciousness
- racing heartbeat
- chest pain/shortness of breath (an hour before SCD)
The most common cause of sudden cardiac death in adults is ventricular fibrillation (v-fib), brought on by acute coronary ischemia. Cases have shown that the most common finding at postmortem examination of SCD is chronic high-grade stenosis of at least one segment of a major coronary artery, the arteries that supply the heart muscle with its blood supply. Left ventricular hypertrophy is thought to be the leading cause of sudden cardiac death in the adult population. This is most commonly the result of longstanding high blood pressure which has caused secondary damage to the wall of the main pumping chamber of the heart, the left ventricle.
Although the most frequent cause of sudden cardiac death is ventricular fibrillation, other causes include the following:
- Coronary heart disease
- Physical stress
- Inherited disorders
- Enlarged heart due to increased blood pressure
- Commotio cordis
The mechanism of death in the majority of patients dying of sudden cardiac death is ventricular fibrillation. Structural changes in the diseased heart as a result of inherited factors (mutations in ion-channel coding genes for example) cannot explain the suddenness of SCD. Also, sudden cardiac death could be the consequence of electric-mechanical disjunction and bradyarrhythmias.
By definition, sudden cardiac death cannot be diagnosed as it has already happened. However, the risk factors for sudden cardiac arrest and subsequent death can be diagnosed in a variety of ways via an electrocardiogram, echocardiogram, MUGA test, cardiac catheterization, and blood tests.
Should coronary heart disease be diagnosed, percutaneous coronary intervention or coronary artery bypass grafting (procedures performed to help restore blood flow via narrowed arteries) may be the procedures of choice. Treatment with marine-derived omega-3 polyunsaturated fatty acids (PUFAs) has been promoted for the prevention of sudden cardiac death due to its postulated ability to lower triglyceride levels, prevent serious arrhythmias, decrease platelet aggregation, and lower blood pressure. However, according to a recent systematic review and meta-analysis, omega-3 PUFA supplementation has not been associated with a lower risk of sudden cardiac death based on absolute measures of association (RD, −0.01; 95% CI, −0.02 to 0.00; P = .09; I2 = 78%).
Sudden cardiac death accounts for more than half of all cardiac deaths. In the United States, it claims the lives of 250,000 to 310,000 people annually. It is also the first manifestation of heart disease for the majority of individuals. Consequently, better management of heart disease through lifestyle factors is recommended.
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