Sudden cardiac death is death from a probable or definite cardiac cause, occurring within one hour of the onset of cardiac symptoms such as:

chest pain, shortness of breath, palpitations, dizziness, nausea, vomiting and sudden profuse sweating.

The majority of sudden cardiac deaths occur as a result of ventricular tachycardia or ventricular fibrillation. These rapid and/or chaotic heart rhythms arise from one of the heart’s ventricles, and prevent the heart from pumping blood to the rest of the body. Death occurs if the abnormal electrical impulses are not corrected within a few minutes.

• Heart attacks are an important and common cause of sudden cardiac death, especially in older persons. However, not all sudden cardiac deaths are caused by heart attacks.

• Sudden cardiac death occurs when there are particular electrical abnormalities in the heart. Heart attacks, on the other hand, occur when there are one or more blockages in the blood vessels supplying the heart. These blockages prevent proper blood flow to the heart muscle and can cause the heart to stop beating suddenly. These patients tend to have cardiovascular risk factors such as hypertension, diabetes mellitus, high cholesterol, obesity, physical inactivity, unhealthy diets, cigarette smoking and excess alcohol intake.

In other patients,

however, especially younger patients without these traditional cardiac risk factors, sudden cardiac death may be caused by cardiomyopathies such as hypertrophic cardiomyopathy and arrhythmogenic right ventricular cardiomyopathy, by congenital coronary artery anomalies and by abnormal electrical conduction syndromes such as Wolff Parkinson White syndrome, Long QT syndrome and Brugada Syndrome. Severe hyperthyroidism, electrocution and drug abuse of for example, cocaine can also cause sudden cardiac death.

Recently, there have been a series of sports-related sudden cardiac deaths locally. Worldwide it is estimated that 1-2/100 000 athletes between the age of 12 and 35 years die suddenly each year. These events are devastating, especially since they occur in young individuals previously felt to be healthy. They tend to occur in males more than they do in females. There may be a history of chest pain, shortness of breath, dizziness or fainting with exertion; unexplained palpitations, fainting or near fainting; or a family history of early heart disease, heart attack or cardiac death. Some patients have no symptoms. Many of these patients have some form of cardiomyopathy, but in 3% of patients, no underlying cardiac abnormality is found. Increased catecholamines, dehydration, electrolyte abnormalities and increased body temperature may precipitate sudden cardiac arrest in a heart predisposed to arrhythmias. Rarely, the patient may have experienced blunt trauma to the chest at a particular time in the heart’s electrical cycle and this causes the heart to go into an abnormal ventricular rhythm.

Pre-participation screening of athletes, and of older individuals participating in at least moderate exercise or beginning a new exercise programme, can help to identify persons at increased risk of sudden cardiac arrest.

• Among athletes, screening protocols comprising a thorough medical history, a physical examination and an electrocardiogram have been found to identify close to 90% of athletes who have an underlying cardiac condition that increased their risk of sudden death. Proper treatment and at times modification of the individual’s athletic activity level can save lives.

We all have a part to play to preventing death from a sudden cardiac arrest.

When sudden cardiac arrest occurs the person suddenly loses consciousness and appears lifeless with no pulse and no breathing or only occasional abnormal gasps. Some patients may have a short seizure (shaking of the arms and legs) when the brain stops receiving blood and oxygen from the heart.

• It is important that someone nearby calls for help immediately, begins cardiopulmonary resuscitation (CPR) and uses an automated external defibrillator (AED). This can maintain the flow of oxygenated blood around the patient’s body and may return the patient’s heart

to a normal rhythm. Don’t delay. Immediate action can save someone’s life.

The Heart Foundation offers a screening programme cardiovascular disease and for sudden cardiac arrest.Do not delay – get screened today.

Prepared by Dr. Marilyn B. Lawrence Wright, Consultant Cardiologist