The definition of sudden cardiac death is the sudden cessation of effective cardiac contraction resulting from ventricular tachycardia-fibrillation.Sudden cardiac death is the medical term used for an unexpected death caused by loss of cardiac function. Death occurs within one hour after the onset of symptoms.
ETIOLOGY AND PARTHENOGENESIS of Sudden Cardiac Death
Important data regarding the individual who suffers sudden cardiac death come from the Seattle Heart Watch study. During a six-year period of 1710 episodes of ventricular fibrillation, there were 346 long-term survivors. Cobb has shown that most instances of sudden cardiac death are not related to identifiable acute myocardial infarcts, which were detected by electrocardiography in only 19 per cent of patients hospitalized after resuscitation from ventricular fibrillation. Nevertheless, the majority of individuals resuscitated have extensive coronary’ artery disease, including 75 per cent with multivessel involvement. In addition, patients experiencing cardiac arrest without concomitant acute myocardial infarcts have a considerably higher incidence of recurrent sudden death in the next two years than do those with acute infarcts. The annual recurrence rate is approximately 30 per cent for those without acute infarcts.
CAUSES OF SUDDEN DEATH IN ADULTS
In fact, there are many possible causes for a sudden death. Situations such as accidental ingestion of poison, high voltage electric shock, or choking after choking on an object or food can cause a sudden death.
The main cardiac alterations that predispose athletes to sudden death are:
- Hypertrophic cardiomyopathy.
- Congenital anomalies of the coronary artery.
- Arrhythmogenic cardiomyopathy of the right ventricle.
- Myocarditis.
- Aneurysm of the aorta.
- Mitral prolapse with mitral regurgitation.
Risk factors of Sudden Cardiac Death
In fact, the risk factors for sudden cardiac death include the causes already mentioned above, among others:
- Ischemic heart disease, including previous occurrence of myocardial infarction (especially in the last six months)
- Other heart diseases, such as heart failure, hypertrophic cardiomyopathy, valve diseases, etc.
- Previous episode of cardiac arrest
- Family history of sudden cardiac death or diseases of the heart conduction system
- History of congenital heart disease
- Report of previous episodes of cardiac cause fainting
- Obesity, diabetes, smoking: since they are risk factors for heart disease in general, especially ischemic
- Drug abuse
PREVENTION OF SUDDEN DEATH.
It is critically important that we develop an improved understanding of mechanisms that initiate and sustain life-threatening ventricular arrhythmias in patients in diverse clinical settings. Unanswered questions include the following: Does platelet aggregation play a role in sudden death in those with ischemic heart disease in the absence of identifiable acute myocardial infarction? Are the important ventricular arrhythmias that develop with acute myocardial ischemia related primarily to re-entrant mechanisms or to increased ventricular automaticity resulting in part from variations in regional concentrations of potassium or catecholamines, from alterations in autonomic nervous system activity, from alterations in adrenergic receptor numbers or affinity, or from local accumulation of phospholipid degradation products, e.g., lysophosphatidyl choline.
It is important to determine why some individuals with chronic congestive heart failure and others with chronic cardiomegaly and ventricular dysfunction are at risk of sudden death from ventricular arrhythmias. It is not clear at present whether increased triglyceride uptake and the inability of injured myocardial cells to metabolize long chain fatty acids contribute to the ventricular arrhythmias of ischemic heart disease. Specific myocardial cellular mechanisms associated with increased risk of ventricular arrhythmias need to be elucidated, as does the role of psychologic stress in the initiation of ventricular arrhythmias in man.
Sudden Cardiac Death Treatment
Most of the time the heart stops working unexpectedly, the cause is a type of severe cardiac arrhythmia called ventricular fibrillation. In this type of arrhythmia, the heart can not beat in a coordinated way, appearing several focuses of stimuli, and the muscle only fibril (as if it were a slight “tremor”). Thus, it can not pump blood to the body, especially the brain. With this, the patient loses consciousness and evolves with falling from the height itself. The treatment of this arrhythmia consists of the application of an electric shock to the chest wall, in order to try to restore the proper functioning of the conduction system of the heart. This shock is called defibrillation and the device used is the defibrillator. Currently, there is an attempt to provide easy-to-use defibrillators, besides adequate training of the population to make use of it, in public places with great concentration of people, facilitating the approach of these patients. In cases of sudden cardiac “death”, time is life; therefore, treatment should be done as soon as possible (preferably within 6 minutes).
After recovery, the cause of cardiac arrest should be properly investigated, and the specific treatment applied. In addition, such patients should be evaluated for implantation of a pacemaker-like device, called an implantable cardioverter-defibrillator. This device is able to detect the cardiac arrhythmia as soon as it starts happening and already applies a shock directly to the heart to reverse the process.
