Sudden Cardiac Death – Causes, Diagnosis And Treatment
Sudden cardiac death is a unexpected death, which occurs in less than an hour after the onset of warning symptoms. Sudden cardiac death is caused by known or unknown heart conditions. Most cases of sudden cardiac death are caused by arrhythmias, but sometimes can be the first expression of a heart disease, unknown until that moment.
Sudden cardiac death main causes are:
- Ischemic heart disease, especially myocardial infarction, sudden cardiac death occurs in 80% of patients with massive myocardial infarction.
- Arrhythmias: ventricular tachycardia, paroxysmal supraventricular tachycardia, ventricular fibrillation, ventricular flutter.
- Valvulopathies: mitral stenosis, aortic stenosis, mitral regurgitation, aortic regurgitation, prosthetic valves, infective endocarditis.
- Right or left ventricular hypertrophy.
- Myocardial diseases: myocarditis, cardiomyopathy.
- Congenital heart malformations: patent ductus arteriosus, tetralogy of Fallot, interatrial septal defect, ventricular septal defect, atrioventricular septal defect, coarctation of the aorta.
- Other heart diseases: cardiac tamponade, cardiac tumors.
Sudden cardiac death occurs mainly in patients with heart diseases that have been mentioned above, in the presence of precipitating factors, such as myocardial ischemia, electrolyte disturbances (hypokalemia, hypomagnesaemia), acid-base disturbances, hypoxia, anemia, drug toxicity (digoxin, antiarrhythmics).
Ways in which sudden cardiac death occurs are:
- Malignant ventricular arrhythmias (sustained ventricular tachycardia or ventricular fibrillation), where exist a ventricular electrical activity, but mechanical ventricular contractions are inefficient.
- Asystole, the heart’s electrical activity and mechanical heart activity are missing.
- Electromechanical dissociation, involving a electrical activity which is present and systematized but mechanical activity of the heart is completely absent or ineffective.
Patient history obtained from the caregivers, may reveal a history of heart disease and may indicate what patient was compiling for, in the minutes preceding sudden cardiac death.
Physical examination detects changes that are caused by the loss of pump function of the heart: the abolition of consciousness, lack of response to painful stimuli, cyanosis, respiratory arrest, seizures, bilateral mydriasis which does not respond to light stimuli (fixed mydriasis).
ECG is the main paraclinical investigation that can determine the way in which sudden cardiac death occurred.
Criteria for diagnosis of sudden cardiac death are represented by:
- Absence of heart sounds;
- The absence of central arterial pulse (in carotid arteries) and peripheral pulse ( in radial arteries);
- The lack of respiratory movements.
The presence of fixed mydriasis certify brain death and makes useless to undertake or to continue the resuscitation maneuvers.
Evolution and prognosis:
If it is not a prompt and competent intervention, sudden cardiac death lead to death or loss of brain function. The prognosis depends primarily on promptness with which the saviors intervened and also on the disease that caused sudden cardiac death.
Prophylaxis. Given that the prognosis is reserved, the most effective measure is to prevent sudden cardiac death. Prevention of sudden cardiac death refers to proper treatment of the patients with heart disease who are at risk for sudden cardiac death and hospitalization in the coronary unit immediately after the appearance of preceding symptoms of sudden cardiac death.
Measures of treatment. Diagnosis of sudden cardiac death requires the adoption of therapeutic measures of maximum emergency, which must be started even outside of the hospital:
- Placing the patient on a horizontal, solid plane;
- Control and release of upper respiratory tract;
- Starting cardiopulmonary resuscitation maneuvers (mouth to mouth breathing and external heart massage, in a ratio of 1 to 5);
- Oro-tracheal intubation;
- Getting an emergency venous access;
- Continuous monitoring of the pulse (carotid, femoral);
- ECG monitoring;
- Specific measures of treatment, adapted to the ways of production of cardiac sudden death:
- 200-360 joules external electric shock, in repeated administration;
- Adrenaline 1 mg intravenously (repeated boluses every 3 minutes);
- Atropine 1 mg intravenously (repeated every 3-5 minutes, until a dose of 0.04 mg / kg).