Sudden Cardiac Death

Nov 15, 2010
Michael Koger

Cardiac death is more common in adult men - With permission from Centers for Disease Control

Sudden cardiac death is a worldwide public health problem, and awareness, prevention, and community efforts are necessary to better manage it.

Sudden cardiac death is unexpected death which results from failure of the electrical system of the heart. Rather than continuing with its normal cycle of contraction and relaxation, the heart quivers at an unusually high rate, which may range from 300 to 800 per minute. The rhythm disturbance is either ventricular tachycardia or ventricular fibrillation, and the patient generally does not have a pulse.

With ventricular tachycardia, there may be a pulse, but it tends to quickly degenerate into ventricular fibrillation, and the heart does not pump blood to other parts of the body. Sudden cardiac death is the reason for more natural deaths each year in the United States than any other medical condition. It also causes more than half of all heart disease deaths.

Of those who suffer sudden cardiac death, four-fifths have evidence of coronary heart disease, and three-fourths of patients who die from sudden cardiac death show signs of a previous heart attack or myocardial infarction. Despite the use of modern cardiopulmonary resuscitation to manage these cases for the last 50 years, less than eight percent of out-of-hospital adult victims of cardiac arrest will survive and make it to hospital discharge and return to the community.

The occurrence of sudden cardiac death is more common in adult men than it is in women, and it is rare in children. In any case, death will ensue if the patient does not receive cardiopulmonary resuscitation with electrical defibrillation or shock within a matter of minutes.

Risk Factors for Sudden Cardiac Death

There are several risk factors for sudden cardiac death. The presence of coronary heart disease, diabetes mellitus, high blood pressure, cigarette smoking, obesity, and high cholesterol will increase the risk. Recreational drug use, previous heart attack or myocardial infarction, heart failure, low ejection fraction or pumping ability of the heart, and a personal or family history of heart rhythm disturbance are also risk factors for sudden cardiac death. Sudden cardiac death and heart attack are not synonymous.

Patients with a history of syncope or fainting spells in which there is a period of unconsciousness may be at risk for it because rhythm disturbances of the heart may cause one to collapse or faint. Certain heart conditions in which the heart muscle weakens, thickens, or dilates will pose a risk for sudden cardiac death; these cases are cardiomyopathies.

The electrocardiogram in some patients may show an abnormally long interval between the Q-wave and the T-wave of the cardiac cycle. This QT interval prolongation may be a defect at birth, or it can result from certain medications, particularly drugs to treat psychotic and other mental disorders. It is, in either case, a risk factor for sudden cardiac death.

If there are family members who have a history of cardiac arrest or sudden cardiac death, there will be a predisposition for sudden cardiac death in those patients as well. Physicians can determine whether their patients are at risk for sudden cardiac death and recommend prevention measures.

Prevention

In order to prevent the occurrence of sudden cardiac death, maintenance of a healthy weight, smoking cessation, regular exercise when there is no medical contraindication, reduction of dietary saturated fat and cholesterol, and proper management of other medical conditions such as diabetes mellitus, high blood pressure, and coronary heart disease are necessary. It may be necessary for the physician to prescribe medications to stabilize the heart rhythm.

Some patients will benefit from an implantable cardioverter-defibrillator, a device which monitors the heart rhythm at all times and delivers an electrical shock if malignant ventricular rhythms occur.

Management of Sudden Cardiac Death

If a bystander observes an individual who has experienced sudden cardiac death, it is imperative that he or she immediately notify 9-1-1 and initiate cardiopulmonary resuscitation. If there is a public access defibrillator or Ambulatory External Defibrillator available and the bystander determines that the patient has had a cardiac arrest, he or she should defibrillate the patient.

A person who is at the scene of these events can assess the patient with verbal commands and other efforts to obtain a response from the victim. The absence of breathing and pulse will also confirm that the patient has suffered a full cardiac arrest. Hospital staff will arrive at the scene and continue cardiopulmonary resuscitation, administer oxygen, intravenous fluids, and medications to stimulate the heart to beat. The patient must go to the nearest hospital.

The American Heart Association provides cardiopulmonary resuscitation training and certification for health care providers and other members of the community in the United States.

Reference:

John Field, Mary Hazinski, Michael Sayre, et al, “ Part 1: Executive Summary. 2010 American Heart Association Guidelines for Cardiopulmonary Resuscitation and Emergency Cardiovascular Care,” Circulation 122 (2010): S640-S656.