Understanding Coronary Artery Disease

Your heart is a strong muscular pump. It is responsible for pumping about 3,000 gallons of blood throughout your body every day. Like other muscles in your body, your heart itself needs to receive a good supply of blood at all times to function properly. Your heart muscle gets the blood it needs to do its job from your coronary arteries.

What is coronary artery disease?
Coronary artery disease is atherosclerosis of the coronary arteries. Atherosclerosis occurs when the arteries become clogged and narrowed, restricting blood flow to the heart. Without adequate blood, the heart becomes starved of oxygen and vital nutrients it needs to work properly.

When the blood flow is slowed the heart doesn't get enough oxygen and nutrients. This can cause chest pain called angina. When one or more of the coronary arteries are completely blocked, the result is a heart attack (injury to the heart muscle).

What causes the coronary arteries to narrow?
Your coronary arteries are shaped like hollow tubes through which blood can flow freely. The "walls" of the coronary arteries are normally smooth and elastic. Coronary artery disease starts when you are very young. Before your teen years, the blood vessel walls begin to show streaks of fat.

As you get older, the fat builds up, causing slight injury to your blood vessel walls. In an attempt to heal itself, the cells release chemicals that make the walls stickier.

Other substances traveling through your blood stream, such as inflammatory cells, proteins and calcium begin to stick to the vessel walls. The fat and other substances combine to form a material called plaque. The plaque builds up and narrows the artery, called atherosclerosis (atha-row-skla-row-sis), also known as "hardening of the arteries."

As the size of a blockage increases, a narrowed coronary artery may develop "collateral circulation," new blood vessels that reroute blood flow around the blockage. However, during times of increased exertion or stress, the new arteries may not be able to supply enough oxygen-rich blood to the heart muscle.

Over time, the inside of the arteries develop plaques of different sizes. Many of the plaque deposits are soft and mushy on the inside with a hard fibrous "cap" covering the outside. If the hard surface cracks or tears, the soft, fatty inside is exposed. Platelets (disc-shaped particles in the blood that aid clotting) come to the area, and blood clots form around the plaque. This causes the artery to narrow even more. Sometimes, the blood clot breaks apart on its own, and blood supply is restored.

In other cases, the blood clot (coronary thrombus) may totally block the blood supply to the heart muscle (coronary occlusion), causing one three serious conditions, called coronary syndromes:

Unstable angina: This may be a new symptom or a change from stable angina. The angina may occur more frequently occur more easily at rest, feel more severe, or last longer. Although this can often be relieved with oral medications, it is unstable and may progress to a heart attack. Usually more intense medical treatment or a procedure is required to treat this acute coronary syndrome.

Non-ST segment elevation myocardial infarction (NSTEMI): This heart attack, or MI, does not cause changes on an electrocardiogram (ECG). However, chemical markers in the blood indicate that damage has occurred to the heart muscle. In NSTEMI, the blockage may be partial or temporary, and so the extent of the damage is relatively minimal.

ST segment elevation myocardial infarction (STEMI): This heart attack, or MI, is caused by a prolonged period of blocked blood supply. It affects a large area of the heart muscle, and causes changes on the ECG as and chemical markers in the blood.

Some people have symptoms that tell them that they may soon develop an acute coronary syndrome, others may have no symptoms until something happens, and still others have no symptoms of the acute coronary syndrome at all.

What Is Ischemia?
When plaque and fatty matter narrow the inside of an artery to a point where it cannot supply enough oxygen-rich blood to meet your heart's needs, cramping of the heart muscle occurs. This is called ischemia.

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 its blood supply is inadequate to meet the heart muscle's 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
• Exposure to cold

When ischemia is relieved in a short period of time (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.

What are the symptoms of coronary artery disease?
The most common symptom is angina or "angina pectoris." Angina is often referred to as chest pain. It is also described as a discomfort, heaviness, pressure, aching, burning, numbness, fullness, squeezing or painful feeling. It can be mistaken for indigestion or heartburn. Angina is usually felt in the chest, but may also be felt in the left shoulder, arms, neck, back or jaw.

Other symptoms that can occur with coronary artery disease include:

• Shortness of breath
• Palpitations (irregular heart beats, skipped beats or a "flip-flop" feeling in your chest)
• A faster heartbeat
• Weakness or dizziness
• Nausea
• Sweating

Women often have different symptoms of coronary artery disease than men. For example, symptoms of a heart attack in women include pain or discomfort in the chest, left arm or back; unusually rapid heartbeat; shortness of breath; and/or nausea or fatigue. It is important to get help right away if any of these symptoms occur.

How Is coronary artery disease diagnosed?
Your doctor can tell if you have coronary artery disease by:

• Talking to you about your symptoms, medical history, and risk factors.
• Performing a physical exam.
• Performing diagnostic tests, including blood tests, an electrocardiogram (ECG or EKG), exercise stress tests, cardiac catheterization and others. These tests help your doctor evaluate the extent of your coronary heart disease, its effect on the function of your heart, and the best form of treatment for you. Research into new testing procedures, such as coronary computed tomography angiogram (CTA), may change the way coronary artery disease is diagnosed in the future.

Tests used to predict increased risk for coronary artery disease include:

• CRP
• Complete lipid profile
• Calcium score screening heart scan

How is coronary artery disease treated?
Treatment for coronary artery disease involves reducing your risk factors, taking medications, possibly undergoing invasive and/or surgical procedures and seeing your doctor for regular visits.

Reduce your risk factors. This involves making lifestyle changes.

• If you smoke, you should quit.
• You will need to make changes in your diet to reduce your cholesterol, keep your blood pressure in check, and keep blood sugar in control if you have diabetes. Low fat, low sodium, low cholesterol foods are recommended. Limiting alcohol is also important.
• You should increase your exercise/activity level to help achieve and maintain a healthy weight and reduce stress. But, check with your doctor before starting an exercise program.
• It is also important to control high blood pressure and maintain tight control of diabetes to reduce your risk of coronary artery disease.
• Test your 10 year risk for heart attack.

Medications. If making lifestyle changes isn't enough to control your heart disease, medications may be needed to help your heart work more efficiently and receive more oxygen-rich blood. The medications you are on depend on you and your specific heart problem.

Procedures to treat coronary artery disease:

Interventional procedures. Common interventional procedures to treat coronary artery disease include balloon angioplasty (PTCA) and stent or drug eluting stent placement. These procedures are considered non-surgical because they are done by a cardiologist through a tube or catheter inserted into a blood vessel, rather than by a surgeon through an incision. Several types of balloons and/or catheters are available to treat the plaque within the vessel wall. The physician chooses the type of procedure based on individual patient needs.

Surgery. coronary artery bypass surgery. One or more blocked coronary arteries are bypassed by a blood vessel graft to restore normal blood flow to the heart. These grafts usually come from the patient's own arteries and veins located in the chest, leg, or arm. The graft goes around the clogged artery (or arteries) to create new pathways for oxygen-rich blood to flow to the heart.

All of these procedures increase blood supply to your heart, but they do not cure coronary heart disease. You will still need to decrease your risk factors to prevent future disease.

When these traditional treatments are not an option, doctors may suggest other less traditional therapies, some are under current research:

• Transmyocardial laser revascularization, or TMR. TMR, or Transmyocardial Laser Revascularization, is a treatment aimed at improving blood flow to areas of the heart that were not treated by angioplasty or surgery. A special carbon dioxide (CO2) laser is used to create small channels in the heart muscle, improving blood flow in the heart. Frequently, it is performed with coronary artery bypass, occasionally alone.
• EECP. For patients who have persistent angina symptoms and have exhausted the standard treatments without successful results, Enhanced External Counterpulsation (EECP) may stimulate the openings or formation of collaterals (small branches of blood vessels) to create a natural bypass around narrowed or blocked arteries. EECP is a non-invasive treatment for people who have chronic, stable angina; who are not receiving adequate relief from angina by taking nitrate medications; and who do not qualify for an invasive procedure such as bypass surgery, angioplasty or stenting.
• Angiogenesis. Investigators are studying several substances, that when given through the vein or directly into the heart may trigger the heart to grow new blood vessels to increase blood flow to the heart muscle
  

The Cleveland Clinic Heart Center cardiologists and surgeons specialize in the treatment of coronary artery disease.  The team approach at the Cleveland Clinic Heart Center insures that patients receive the best care before, during and after their procedure.

For more information about coronary artery disease, interventional procedures or surgery, please contact the Heart and Vascular Institute Information & Resource Nurse toll-free at 866-289-6911 or e-mail us using the Contact Us form. We would be happy to answer your questions.

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