What is Coronary Artery Disease?
The heart is a powerful muscle that acts as a pump to push blood out into the arteries which then flow to every organ and cell in the body. Blood is the body's way of transporting oxygen to all living tissue within the body. Without this necessary oxygen cells begin to die. This amazing organ pumps 11 500 litres of blood around the body every day!
Although the heart is responsible for pumping the oxygen rich blood to the rest of the body, it also needs its own supply of oxygen filled blood to survive. The heart receives its blood supply via a special network of vessels called the coronary arteries. These arteries form a network that wrap around the heart with the smaller branches of the arteries delving deep into the muscle to feed it oxygen rich blood and also carry away oxygen depleted blood.
Coronary artery disease is the narrowing or blockage of these coronary arteries, usually caused by atherosclerosis. Atherosclerosis (sometimes called "hardening" or "clogging" of the arteries) is the buildup of cholesterol and fatty deposits (called plaques) on the inner walls of the arteries. (Just like a garden hose that gets clogged and narrows the inside diameter decreasing the flow of water through the hose.) These plaques can restrict blood flow to the heart muscle by physically clogging the artery or by causing abnormal artery tone and function (hardening of the arteries).
Without an adequate blood supply, the heart becomes starved of oxygen and the vital nutrients it needs to work properly. This can cause chest pain, called angina. If the blood supply to a portion of the heart muscle is cut off entirely, or if the energy demands of the heart become much greater than its blood supply, a heart attack (injury to the heart muscle) may occur.
What is ischemia?
Ischemia is a condition described as "cramping of the heart muscle." Ischemia occurs when the narrowed coronary artery reaches a point where it cannot supply enough oxygen-rich blood to meet the heart's needs. The heart muscle becomes "starved" for oxygen-rich blood to meet the heart's needs. The heart muscle becomes "starved" for oxygen.
Ischemia of the heart can be compared to a cramp in the leg. When someone exercises for a very long time, the muscles in the legs cramp up because they're starved for oxygen and nutrients. Your heart, also a muscle, needs oxygen and nutrients to keep working. If the heart muscle's blood supply is inadequate to meet its needs, ischemia occurs, and you may feel chest pain or other symptoms.
Ischemia is most likely to occur when the heart demands extra oxygen. This is most common during exertion (activity), eating, excitement or stress, or exposure to cold.
When ischemia is relieved in less than 10 minutes with rest or medications, you may be told you have "stable coronary artery disease" or "stable angina." Coronary artery disease can progress to a point where ischemia occurs even at rest.
Ischemia and even a heart attack can occur without any warning signs and is called "silent" ischemia. Silent ischemia can occur among all people with heart disease, though it is more common among people with diabetes.
What are the risk factors for coronary artery disease?
Non-modifiable risk factors (those that cannot be changed) include:
Male gender. Men have a greater risk of heart attack than women do, and men have heart attacks earlier in life than women. However, beginning at age 70, the risk is equal for men and women.
Advanced age. Coronary artery disease is more likely to occur as you get older, especially after Age 65.
Family history of heart disease. You have an increased risk of developing heart disease if you have a parent with a history of heart disease, especially if they were diagnosed before Age 50. Ask your doctor when it's appropriate for you to start screenings for heart disease so it can be detected and treated early.
Modifiable risk factors (those you can treat or control) include:
Cigarette smoking and exposure to tobacco smoke
High blood cholesterol and high triglycerides – especially high LDL ("bad") cholesterol over 100 mg/dL and low HDL ("good") cholesterol under 40 mg/dL. Some patients who have existing heart or blood vessel disease, and other patients who have a very high risk, should aim for an LDL level less than 70 mg/dL. Your doctor can provide specific guidelines.
High blood pressure (140/90 mmHg or higher)
Uncontrolled diabetes (HbA1c >7.0)
Being overweight (body mass index [BMI] 25–29 kg/m2) or being obese (BMI higher than 30 kg/m2)
NOTE: How your weight is distributed is important. Your waist measurement is one way to determine fat distribution. Your waist circumference is the measurement of your waist, just above your navel. The risk of cardiovascular disease increases with a waist measurement of over 35 inches in women and over 40 inches in men.
The more risk factors you have, the greater your risk of developing coronary artery disease.