Coronary heart disease (CHD) normally happens when cholesterol accumulates on the artery walls, creating plaques. The arteries narrow, reducing blood flow to the heart. Sometimes, a clot can obstruct the flow of blood to the heart muscle.
CHD commonly causes angina pectoris (chest pain), shortness of breath, myocardial infarction, or heart attack. It is the most common type of heart disease in the United States, where it accounts for 370,000 deaths every year.
- Coronary heart disease accounted for 23.5 percent of all deaths in the U.S. in 2008.
- According to the Centers for Disease Control and Prevention (CDC), about 735,000 Americans have a heart attack each year.
- Warning signs and symptoms include chest pain or discomfort and shortness of breath.
- Examples of coronary heart disease include angina and heart attack.
What is coronary heart disease?
Coronary heart disease is one of the leading causes of death in the United States.
The heart is a muscle, about the same size as an adult human fist. Blood is pumped from the heart to the lungs, where it collects oxygen. This oxygen-rich blood is then pumped back to the heart and then to organs throughout the body through arteries.
The blood then returns to the heart through the veins and is pumped to the lungs again. This is called circulation.
Coronary arteries are the heart's network of blood vessels. They exist on the surface of the heart, and they supply the heart muscle with oxygen. If the coronary arteries narrow, the supply of oxygen-rich blood to the heart may become too low, especially during physical activity.
At first, this reduction in blood flow may not produce any symptoms, but as fatty deposits, or plaques, build up in the coronary arteries, signs and symptoms may emerge.
CHD is believed to start with injury or damage to the inner layer of a coronary artery.
This damage causes fatty plaque deposits to build up at the site of the injury. These deposits consist of cholesterol and other cellular waste products. The accumulation is called atherosclerosis.
If pieces break off or rupture, platelets will clump in the area, attempting to repair the blood vessel. This clump can block the artery, reducing or blocking blood flow, and leading to a heart attack.
Below is a 3-D model of CHD, which is fully interactive.
Explore the model using your mouse pad or touchscreen to understand more about CHD.
The following are symptoms of angina:
- Chest pain: People describe it as a squeezing, pressure, heaviness, tightening, burning, or aching across the chest. It usually starts behind the breastbone. The pain often spreads to the neck, jaw, arms, shoulders, throat, back, or even the teeth.
- Related symptoms: Other symptoms include indigestion, heartburn, weakness, sweating, nausea, cramping, and shortness of breath.
There are several main types of angina:
- Stable angina: The discomfort may last for a short period of time, and it may feel like gas or indigestion. It happens when the heart is working harder than usual, such as during exercise. It has a regular pattern. It can happen over months or years. Rest or medication can relieve symptoms.
- Unstable angina: This is often caused by blood clots in the coronary artery. It occurs at rest, it is surprising, it lasts longer, and it may worsen over time.
- Variant angina: This type occurs at rest, and it is usually severe. It happens when there is a spasm in an artery that causes it to tighten and narrow, disrupting blood supply to the heart. Triggers include exposure to cold, stress, medicines, smoking, or cocaine use.
Shortness of breath (dyspnea)
CHD can lead to shortness of breath. If the heart and other organs are getting too little oxygen, the patient may start panting. Any exertion may be very tiring.
Heart attack, or myocardial infarction, happens when the heart muscle does not have enough blood, and therefore oxygen. The muscle dies, and a heart attack occurs.
A heart attack commonly occurs when a blood clot develops from a plaque in one of the coronary arteries. The clot, if it is big enough, can stop the supply of blood to the heart. The blood clot is known as coronary thrombosis.
Symptoms of a heart attack include:
- chest discomfort and mild pain, or a crushing chest pain
- shortness of breath
- face seems gray
- an overall feeling of being unwell and fear that life is coming to an end
- nausea and vomiting
- perspiration and clammy skin
The first symptom is normally chest pain that spreads to the neck, jaw, ears, arms, and wrists, and possibly the shoulder blades, the back, or the abdomen.
Changing position, resting, or lying down brings no relief. The pain is often constant, but it can come and go. It can last from a few minutes to many hours.
A heart attack is a medical emergency. It can result in death or permanent damage to the heart muscle. If anyone has signs of a heart attack, it is crucial to call the emergency services immediately.
Treatment options include inserting a small metal mesh to expand and support the artery.
CHD cannot be cured, but with today's technology, it can be managed effectively.
Treatment involves lifestyle changes, and possibly some medical procedures and medications.
Lifestyle recommendations include quitting smoking, eating a healthy diet, and exercising regularly.
- Statins: These are the only medications demonstrated to have a positive impact on outcomes in CHD, but if a person has another underlying cholesterol disorder, they may not work.
- Low-dose aspirin: This reduces blood clotting, lowering the risk of angina or a heart attack.
- Beta blockers: May be used to reduce blood pressure and heart rate, especially in a person who has already had a heart attack.
- Nitroglycerin patches, sprays, or tablets: These control chest pain by reducing the heart's demand for blood by widening the coronary arteries.
- Angiotensin-converting enzyme (ACE) inhibitors: These lower blood pressure and help to slow or stop the progression of CHD.
- Calcium channel blockers: This will widen the coronary arteries, allowing greater blood flow to the heart, and reduce hypertension.
Surgery can open or replace blocked arteries, if the blood vessels have become very narrow, or if symptoms are not responding to medications:
- Laser surgery: This involves making several tiny holes in the heart muscle, which encourage the formation of new blood vessels.
- Coronary bypass surgery: The surgeon uses a blood vessel from another part of the body to create a graft that can bypass the blocked artery. The graft may come from the leg or an inner chest-wall artery.
- Angioplasty and stent placement: A catheter is inserted into the narrowed part of the artery. A deflated balloon is passed through the catheter to the affected area. When the balloon is inflated, it compresses the fatty deposits against the artery walls. A stent, or mesh tube, may be left in the artery to help keep it open.
Rarely, a heart transplant may be carried out, if the heart is badly damaged and treatment is not working.
Controlling blood cholesterol levels reduces the risk of CHD. Being physically active, limiting alcohol intake, avoiding tobacco, and consuming a healthy diet with reduced sugar and salt can all help.
People with CHD or diabetes should ensure they control these conditions by following the doctor's recommendations.
Smoking increases the risk. Tobacco can:
- Increase inflammation and cause more cholesterol to deposit in coronary arteries.
- A woman who smokes 20 cigarettes a day is six times more likely to develop CHD than a woman who has never smoked.
- Men who smoke regularly are three times more likely to develop CHD compared with men who have never smoked.
The following factors increase the risk:
- As people age the risk increases.
- Men are more likely to develop CHD, although the risk for women is still significant, especially after menopause.
- Having a parent who developed CHD before the age of 60 years increases the risk of developing it.
- Uncontrolled hypertension, or high blood pressure, causes arteries to thicken and narrow, reducing blood flow.
- High blood cholesterol increases the chance of plaque building up, and this makes atherosclerosis more likely.
- Lack of exercise increases the risk, as does poor diet, including consumption of processed meat, trans fats, and fast foods.
- Long-term emotional and mental stress have been linked with damage to arteries.
- Components of metabolic syndrome, such as diabetes type II and obesity, are linked to a higher risk of developing CHD.
Some risk factors are not lifestyle-related. These may include:
- High levels of homocysteine, an amino acid produced by the body. Studies have linked it to a higher incidence of CHD.
- High levels of fibrinogen, a blood protein involved in the blood clotting process. Excess levels may encourage the clumping of platelets, resulting in the formation of clots.
High levels of lipoprotein have been associated with a higher risk of cardiovascular disease and CHD.
Physical examination, medical history and a number of tests can help to diagnose CHD including:
- Electrocardiogram (ECG): This records the electrical activity and rhythms of the heart.
- Holter monitor: This is a portable device that the patient wears under their clothes for 2 days or more. It records all the electrical activity of the heart, including the heartbeats.
- Echocardiogram: This is an ultrasound scan that checks the pumping heart. It uses sound waves to provide a video image.
- Stress test: This may involve the use of a treadmill or medication that stresses the heart.
- Coronary catheterization: A dye is injected into the heart arteries through a catheter that is threaded through an artery, often in the leg or arm, to the arteries in the heart. An X-ray then detects narrow spots or blockages revealed by the dye.
- CT scans: These help the doctor to visualize the arteries, detect any calcium within fatty deposits that narrow coronary arteries, and to characterize other heart abnormalities.
- Nuclear ventriculography: This uses tracers, or radioactive materials, to show the heart chambers. The material is injected into the vein. It attaches to red blood cells and passes through the heart. Special cameras or scanners trace the movement of the material.
- Blood tests: These can measure blood cholesterol levels, especially in people who are over 40 years old, have a family history of heart or cholesterol-related conditions, are overweight, and have high blood pressure or another condition, such as an underactive thyroid gland, or any condition which may elevate blood levels of cholesterol.