The way cigarettes bring on heart damage is still something of a mystery but three possible explanations are:
1. Nicotine repeatedly over stimulates the heart.
2. The carbon monoxide absorbed into the blood takes the place of oxygen and hampers nourishment of the heart muscle and other tissues.People with angina pectoris develop the chest pain quicker if they smoke.Even being in the same room with people who are smoking may aggravate these chest pains.
3. The smoke damages the lining of the coronary arteries, allowing artery clogging cholesterol to build up and narrow the passage ways.
Evidence that heart attacks are common among smokers is now beyond serious dispute.The risk is in proportion to the amount of tobacco smoked.This includes the age at which smoking is begun the number of cigarettes smoked and the degree of inhalation.
The risk of heart attacks occurring at an age below 40 years and of consequent sudden death is also more among heavy smokers than among non smokers.
Discontinuance of smoking lessens this risk so much so that those who smoked previously but stopped later on five years later their chances of getting heart attack had come down to the same level as those of non smokers.