Coronary heart disease, also known as coronary artery disease, refers to a narrowing of the coronary arteries, the blood vessels that supply oxygen and blood to the heart. It is a major cause of illness and death.
Sometimes a clot can obstruct the flow of blood to the heart muscle.
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About the heart
If the arteries become blocked, the heart cannot work properly.
The heart is a muscle. It is about the same size as an adult human fist. It beats about 70 times per minute, and it pumps oxygen-rich blood around the body.
After leaving the heart, blood goes to the lungs, where it collects oxygen. This oxygen-rich blood returns to the heart from the lungs, and it is pumped to organs throughout the body through arteries.
The blood returns to the heart through the veins and is pumped to the lungs again.
This is called circulation.
Coronary arteries are the heart's own 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 plaque, build up in the coronary arteries, signs and symptoms may emerge.
Symptoms of coronary heart disease
Angina is a pain, a discomfort, or tightness in the chest. 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.
In stable, or chronic, 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 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.
CHD can lead to a heart attack or cardiac arrest.
Variant angina 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.
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. This is also known as coronary thrombosis.
A heart attack commonly occurs when a blood clot develops from plaque in one of the coronary arteries. The clot, if it is big enough, can stop the supply of blood to the heart.
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 a sense of terror 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, and 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.
People with diabetes and those aged over 75 years may experience a "silent heart attack," in which there is no pain at all.
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.
Risk factors for coronary heart disease
The following factors increase the risk:
Smoking is a risk factor for CHD.
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 as 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.
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.
Causes of coronary heart disease
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, or atheromas, consist of cholesterol and other cellular waste products, and 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.
Diagnosing coronary heart disease
A patient should be ready to explain their medical history and symptoms, and to undergo a physical examination.
A number of tests can help to diagnose CHD.
Electrocardiogram (ECG), which records the electrical activity and rhythms of the heart. Electrodes are attached to the skin, and impulses are recorded as waves appear on a screen. This may also reveal any damage to the heart from a heart attack.
A Holter monitor records the heart's activity.
A Holter monitor is a portable device that the patient wears under their clothes for 2 days. It records all the electrical activity of the heart, including the heartbeats. It has a button that can be pressed if symptoms are felt. It records the heart rhythms that were present at that moment. Some abnormalities may indicate a problem with blood flow.
An echocardiogram is an ultrasound scan that checks the pumping heart. It uses sound waves to provide a video image. It can show the percentage of blood pumped out of the patient's left ventricle, the main pumping chamber, with each heartbeat.
This is called the ejection fraction. It is crucial for determining how well the heart is pumping.
A stress test may involve the use of a treadmill or medication that stresses the heart. Imagining techniques can show whether there are any blockages in the heart arteries that could underlie heart failure.
In 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.
If a blockage is found, a balloon may be pushed through the catheter and inflated, to squash the clot and improve blood flow. A stent may be placed to keep the artery dilated.
Nuclear ventriculography 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 can measure blood cholesterol levels, especially in patients 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.
Treatment options for coronary heart disease
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, exercising regularly, and minimizing stress. Excess sugar has recently been linked to a higher risk of dying from heart disease.
Statins can reduce cholesterol levels. Statins are the only medication 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 reduces blood clotting, lowering the risk of angina or a heart attack.
Nitroglycerin patches, sprays, or tablets, which control chest pain by reducing the heart's demand for blood by widening the coronary arteries.
Angiotensin-converting enzyme (ACE) inhibitors lower blood pressure and help to slow or stop the progression of CHD.
Calcium channel blockers widen the coronary arteries, allowing greater blood flow to the heart, and reducing hypertension.
Surgery can open or replace blocked arteries, if the blood vessels have become very narrow, or if symptoms are not responding to medications.
In percutaneous coronary revascularization, also known as 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. In some cases, the stent releases a medication.
In 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.
Laser surgery involves making several tiny holes in the heart muscle, which encourage the formation of new blood vessels.
Rarely, a heart transplant may be carried out, if the heart is badly damaged and treatment is not working.
Preventing coronary heart disease
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.