Dr TS Kler, Chairman, PSRI Heart Institute, elaborates on sudden cardiac death and ways to prevent it
Sudden death is defined as any death occurring within one hour of start of symptoms. More than 95 per cent of sudden deaths are cardiac in nature. Non-cardiac sudden deaths can occur due to major bleeding into brain, massive bleeding in the tummy cavity or chest like rupture of aorta (major blood vessel carrying blood from heart to various organs of body). It can also occur due to severe allergic reaction called anaphylactic reaction. So, majority of sudden deaths are heart related.
Sudden death occurs due to severe slowing of heart beat (Bradycardia) or very fast heart beat (Tachycardia). In both the situations of bradycardia and severe tachycardia, heart is not able to pump enough blood into aorta and there is severe drop of blood pressure and all the organs especially brain and heart don’t get enough blood for their functioning, causing death.
Sudden cardiac death usually occurs when there is already significant decrease in the pumping capacity of heart, technically called left ventricular ejection fraction. The chances of sudden cardiac death are many fold when Left Ventricular Ejection Fraction (LVEF) drops below 35 per cent. This drop of LVEF may be due to old heart attack or disease of heart muscle called cardiomyopathy.
Sudden death in these patients occurs due to rhythm problems arising from the lower chambers of heart called ventricular tachycardia or ventricular fibrillation. In ventricular tachycardia, usually there is some blood pressure, but in ventricular fibrillation blood pressure is practically zero and is akin to cardiac arrest. In both ventricular tachycardia and ventricular fibrillation, the most effective and reliable method to save a patient is to give electric shock on the chest and cardiopulmonary resuscitation.
Minority of sudden cardiac deaths occur due to major heart attack causing again ventricular tachycardia or ventricular fibrillation though the patient may be totally healthy prior to this attack. Very few sudden cardiac deaths occur in apparently healthy people who are prone to get ventricular tachycardia or ventricular fibrillation due to underlying electrical problems of heart like hypertrophic cardiomyopathy, arrythmogenic right ventricular dysplasia and brugada syndrome. Many of these three diseases run in families. So, a history of sudden death in the family should lead to screening of other family members for presence of these rare disorders.
Can we prevent sudden cardiac death?
Yes, to a major extent. Following preventive actions can be of great value. Prevent damage occurring to heart muscle by avoiding coronary artery blockages by proper diet, regular exercise, controlling cholesterol, blood pressure, diabetes, doing yoga and meditation. Immediate treatment of heart attack by angioplasty or clot dissolving drugs can prevent heart damage and sudden.