Coronary heart disease (CHD)
This condition, also known as coronary artery disease, develops as cholesterol is deposited in the artery wall, causing the formation of a hard, thick substance called cholesterol plaque. The accumulation of cholesterol plaque over time causes narrowing of the coronary arteries, a process known as atherosclerosis.
This can be accelerated by smoking, high blood pressure, elevated cholesterol and diabetes. There’s usually a gradual progression of symptoms over time as coronary arteries become narrowed. If they become narrowed by 50 to 70 percent, they can no longer meet the increased blood oxygen demand by the heart muscle during exercise or stress. This lack of oxygen to the heart muscle causes chest pain (angina).
Angina occurs when the heart muscle does not get as much blood (and oxygen) as it needs. It may be felt as pressure, heaviness, tightening, squeezing or aching across the chest, particularly behind the breastbone. The pain often radiates to the jaw and down the arm, accompanied by shortness of breath and sweating. However, angina can present in a variety of ways and there may not even be specific chest pain. You could have shoulder or backache, nausea, indigestion or upper abdominal pain.
Women, the elderly, and people with diabetes may simply complain of fatigue or not feeling well.
Angina usually occurs during exertion, severe emotional stress or after a heavy meal – because that’s when the heart muscle needs more blood oxygen than the narrowed coronary arteries can deliver.
Most heart attacks are caused by a blood clot blocking one of the coronary arteries that take blood and oxygen to the heart. Without a supply of oxygen, that part of your heart muscle dies or becomes permanently damaged. The medical term for a heart attack is myocardial infarction.
A heart attack can occur as a result of:
• The slow buildup of cholesterol plaque in the walls of the arteries leading to the heart. This causes narrowing and sometimes blockage of these arteries and not enough oxygen-containing blood can flow to the heart muscle. In this case, a heart attack is more likely to happen during exercise.
• The plaque developing cracks or tears. Blood platelets stick to these tears and form a blood clot that completely blocks the passage of oxygen-rich blood to the heart.
• Sudden, overwhelming stress.
This is when the heart stops beating (or the heart’s rhythm becomes chaotic, preventing it from pumping effectively). A person usually becomes unconscious, stops breathing and their skin turns pale or blue. Without blood circulation, brain damage begins after about four minutes and death can occur after 10 minutes. Someone who has had a heart attack doesn’t automatically experience cardiac arrest or need cardiopulmonary resuscitation (CPR). However, if cardiac arrest does occur as a result of a heart attack, call an ambulance and start CPR.
A stroke is a brain attack and occurs when the blood supply, oxygen and nutrients are prevented from reaching a part of the brain due to a burst or clogged blood vessel. That part of the brain is damaged and cells begin to die. It is one of the main causes of death and disability in South Africa.
A stroke can be caused by:
• A blocked artery, usually from the buildup of fatty material in the artery walls.
• A blood clot (sometimes formed elsewhere in the body) blocks a vessel in the brain – known as a cerebral infarction.
• A cerebral haemorrhage, in which an artery in the brain bursts, flooding the tissue with blood.
Congestive heart failure
A condition in which the heart’s function as a pump to deliver oxygen-rich blood to all parts of the body is not adequate to meet the body’s needs.
The most common causes are:
• Coronary heart disease
• High blood pressure
• Long-term alcohol abuse
• Disorders of the heart valves
If untreated, worsening congestive heart failure will affect almost every organ in the body.
This is an irregular heartbeat (also called dysrhythmia). Your heart rate can also be irregular, but this doesn’t necessarily occur with arrhythmia. Arrhythmia can occur with a normal, slow or rapid heart rate.
It may be caused by:
• Coronary heart disease
• Electrolyte imbalances in your blood (such as sodium or potassium)
• Changes in your heart muscle
• Injury from a heart attack
• During the healing process after heart surgery
Irregular heart rhythms can also occur in normal, healthy hearts.
TOMMOROW: How to recognise a heart attack
This article originally appeared in Heart magazine, for the Heart and Stroke Foundation SA