Over 90 per cent of Sudden deaths are Cardiac in Nature
It is not uncommon these days to hear that somebody apparently very healthy dies suddenly, shocking the family and friends. Let us examine why people die suddenly and how can we prevent this. Sudden death is defined as any death which occurs within one hour from the start of symptoms. Most of the sudden deaths are Cardiac in nature, wherein there are few non-Cardiac causes of sudden death like, severe bleeding in the brain, severe bleeding in the GIT, rupture of Aorta (largest vessel carrying pure blood from heart to various parts of body) after dissection (Sudden rupture of aorta or sudden rupture of aortic aneurysm (aneurysm is dilated part of Aorta due to weakening of its walls). In addition, there is another medical condition namely pulmonary embolism (Sudden occlusion of lungs artery due to big clot, usual source of these clots in the lungs are the one which moves from the legs or pelvic veins and is called deep vein thrombosis.
Sudden Cardiac Deaths (SCD) Prevalence and causes-
As mentioned earlier, more than 90 per cent of sudden deaths are Cardiac in nature and one of the major reason is dangerous (abnormal) rhythms arising from lower chambers of the heart (Ventricles), called ventricular arrhythmias. Most common arrhythmias which can kill a patient are:
1. Ventricular Tachycardia - Very fast heart rate coming from lower chambers of heart, usually rate is more than 150.
2. Ventricular Fibrillation- This leads to cardiac arrest, as there is just electrical activity in the ventricles but no mechanical activity & thus heart fails to pump blood to body & suddenly person collapses.
3. Sudden severe decrease in HR- only about 15 per cent of sudden cardiac deaths are due to bradycardia (slow heart rate) whereas 85 per cent are due to Tachycardia (either ventricular tachycardia or ventricular fibrillation).
SCD Diagnosis-
1. Most of the sudden Cardiac deaths occur due to these malignant arrhythmias in patients who have diseased hearts and their heart’s pumping capacity is decreased, especially where Ejection fraction (a measure of the pumping capacity of heart) is below 35 per cent either due to previous heart attack or weakening of heart muscle called cardiomyopathy. EF can be measured by the Echo Test.
2. Few deaths occur due to a major heart attack, called myocardial infarction. Heart-attacks which cause sudden death because of sudden block in coronary arteries (either Left main artery or left anterior descending artery) and can occur in apparently normal healthy young individuals.
3. There are few less common causes of SCD as severe aortic stenosis, hypertrophic cardiomyopathy (a disease where the heart muscle becomes thick) and this disease occurs usually in young people, less than 35 years of age. Besides there are electrical problems of heart like QT prolongation, Brugada syndrome, ARVC (arrhythmogenic Right ventricular cardiomyopathy).
Prevention of SCD-
1. Regular health checkup is very useful like- Checking blood sugars, Blood pressure at least once in 6 months in age more than 40 years, Lipid profile once a year, TMT or any other exercise test once in 2 years (Once a year if u have diabetes, strong family history of coronary artery disease, smokers or abnormally raised bad cholesterol (LDL more than 150 mg per cent). 2. If you already have heart disease, you should have an echo test to assess Ejection Fraction and if it’s less than 35 per cent you are at a higher risk of sudden cardiac death.
3. In such problems, Sudden Cardiac death can be very effectively prevented by implanting a device called ICD (Implantable cardioverter-defibrillator).
4. This device is implanted under local anaesthesia where a wire (lead) goes into the Right ventricle & device is implanted under Left clavicle (left side of the chest) under the skin. This device monitors heart Rythm 24x7 & can diagnose dangerous Rhythm problems in 5-10 seconds & can give automatically electric shock to rectify the abnormal Rhythm to take it to normal.
5. The efficacy of ICD to revive a Cardiac arrest victim is to the tune of 97 per cent, thus it is a highly successful device. Even now another latest ICD is available which is called Subcutaneous ICD wherein no wire (lead) goes inside the heart. Usually, the battery of this device lasts 10-14 years. Implantable cardioverter-defibrillator, ICD is considered to be a life-saving device for prevention of patients with SCA/SCD.
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