Coronary Artery Disease
CAD: Leading Cause of Death Worldwide
Your coronary arteries are the large blood vessels that supply your heart muscle with oxygen-rich blood. When these arteries become blocked, you have coronary artery disease (CAD).
Coronary artery disease, which typically builds up over decades, is the most common form of heart disease and is the leading cause of death worldwide. It accounts for over 350,000 deaths in the United States per year.
The narrowing of the arteries in CAD is caused by a process called atherosclerosis. People with atherosclerosis have a build-up of a substance called plaque inside the wall of their arteries.
Plaque is made up of fat, cholesterol, clot, calcium deposits, and white blood cells that have gotten into the artery wall. The plaque causes the wall to "bulge" into the inside of the artery where the blood normally flows. The bulge can partly or completely restrict the flow of blood in a particular artery.
Chest Pain or Shortness of Breath
Decreased blood flow to the heart muscle can result in chest pain (called angina) or, in some cases, shortness of breath.
Heart Attack and Heart Failure
A complete blockage can cause a heart attack (also known as a myocardial infarction or MI), when lack of oxygen-rich blood flow causes the heart muscle to die. This may occur as a result of plaque rupture and blood clot formation at the site of a narrowed artery.
More severe heart attacks can permanently damage parts of your heart muscle. This can cause heart failure, a condition where your heart can't pump enough blood to the rest of your body.
The damage to the heart caused by a heart attack can also lead to arrhythmias, or problems with the speed or rhythm of your heartbeat.
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Signs and Symptoms of CAD
Coronary artery disease can progress for years, even decades, without symptoms. But as your arteries become more and more narrowed, symptoms can manifest. Many patients, particularly the elderly and women, often have atypical symptoms.
The most common, typical symptoms of coronary artery disease include:
- Angina, or chest pain with radiation to the neck, jaw or left arm
- Shortness of breath
- Palpitations (irregular heartbeats)
- Weakness or dizziness
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Risk Factors for CAD
There is a long list of traits, conditions and habits that can raise your risk of developing coronary artery disease (CAD). The more you have, the greater your risk. Fortunately, many of these can be controlled, helping to prevent or delay the development of CAD. These risk factors include:
- Smoking: Nicotine constricts your blood vessels, and other toxins can damage their inner lining causing plaques to rupture and create a heart attack. Smoking can also raise cholesterol and blood pressure. It also reduces the amount of oxygen getting your body's tissues. Stopping smoking can reduce your risk of heart attack by 50 percent.
- High Cholesterol: Elevated levels of low-density lipoprotein (LDL) or "bad" cholesterol and/or low levels of high-density lipoprotein (HDL) or "good" cholesterol can increase the risk of heart disease. Your goals for cholesterol are dependent on your risk factors for heart disease or whether you have established disease.
- High Blood Pressure: Uncontrolled blood pressure can help harden and thicken the arteries. In general, your blood pressure should be less than 120/80.
- Diabetes substantially increases your risk of developing coronary artery disease. Even when glucose (blood sugar) levels are under control, diabetes boosts the risk of heart disease, but the risks are even higher if blood sugar is not well controlled. About three-quarters of people with diabetes die of some form of heart or blood vessel disease. If you have diabetes, you should work with your doctor to manage it as best you can.
- Obesity: Your body mass index (BMI) should be under 25.
- Inactivity: You should exercise three times per week.
- Stress: Activities designed to manage stress may reduce your risk of CAD.
- A family history of heart disease increases your risk of developing CAD. Your risk increases if your father or brother was diagnosed with CAD before the age of 55 or if your mother was diagnosed before age 65.
- Age: Your risk for CAD increases with age. For men, the risk increases sharply after age 45. For women, the risk jumps after age 55.
- Metabolic Syndrome: A collection of conditions that includes high blood pressure, high triglycerides, elevated insulin levels and excess body fat around the waist.
- Sleep Apnea: a condition in which your breathing stops or gets very shallow while you are sleeping.
- High Levels of C-Reactive Protein: Emerging research suggests that high levels of a protein called CRP in the blood may raise the risk of developing CAD or having a heart attack.
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Causes of CAD
Coronary artery disease begins in your teens. The walls of your coronary arteries are like hollow tubes. They start out smooth and elastic.
By the time you are in your teens, they begin to show traces of fat in them. Over time, the fat builds up, causing injury to the walls. Risk factors such as those listed above make matters worse.
In a bid to heal itself, your body's cells release chemicals that make the walls sticky. Substances traveling through your blood vessels — inflammatory cells, proteins, calcium and more — begin to stick to the walls. They combine with fat and form plaque. This clogging substance causes the arteries to narrow.
In some cases, blood platelets, which are designed to help clotting, come to the area and form blood clots. These clots may also block blood flow to the heart.
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Your doctor can diagnose coronary artery disease (CAD) by first talking to you about your symptoms, medical history and risk factors and then performing a physical exam. In addition, a number of diagnostic tests may be ordered.
No single test can determine if you have coronary artery disease. If you go to the emergency room with chest pain, some of these tests will be ordered immediately. These tests will seek to find out if you are having angina or a heart attack. If you have a stable pattern of angina, other tests may be done to determine the severity of your disease. If your doctor thinks you have coronary artery disease, he or she will probably do one or more of the following tests:
These tests check for levels of certain fats, cholesterol, sugar and proteins called troponins in the blood that help determine if you have risk factors for coronary artery disease or if you are having a heart attack.
Electrocardiogram (EKG or ECG)
This is a painless, noninvasive test in which patches with electrodes are attached to your skin to measure electrical impulses produced by your heart.
These impulses are recorded as waves displayed on a monitor or printed out on graph paper. The test can reveal evidence of a previous heart attack or one that is in progress. Heart rhythm is also captured with an EKG.
This is a portable device that records all of your heartbeats over an extended period, usually either 24 or 48 hours. You wear small patches with electrodes on your chest that are connected by wires to a small, portable recorder. The recorder can be clipped to a belt, kept in a pocket, or hung around your neck.
During the time you're wearing a Holter monitor, you do your usual daily activities. This is used to monitor heart rhythm for an extended period of time.
This test uses sound waves to create a moving picture of your heart.
- Provides information about the size and shape of your heart and how well your heart chambers and valves are functioning.
- Identifies areas of poor blood flow to the heart, areas of heart muscle that aren't contracting normally, and previous injury to the heart muscle caused by poor blood flow.
The test is noninvasive and is performed by placing a probe on your chest wall. It is the same technique used in sonograms in pregnant women.
During a stress test, you exercise to make your heart work harder and beat faster. An EKG is recorded and blood pressure is monitored during exercise. The technician will be asking you about the presence of symptoms such as chest pain or shortness of breath.
Sometimes imaging is also done. This can be done with an echocardiogram as described above or by using a radioactive dye and xray equipment to image the heart's motion with exercise. If imaging is performed with your stress test, resting images (without exercise) are compared to stress images (after exercise) to look for changes in heart function that are related to blood flow patterns.
Coronary Angiogram or Catheterization
To directly see the pattern of blood flow in your arteries, your doctor may want to perform a coronary catheterization. This involves injecting a dye into your arteries in what is called an angiogram.
The dye is delivered through a long, thin, flexible tube called a catheter that is threaded through a leg artery into the coronary arteries. This is called catheterization.
The dye outlines areas of blockages on x-ray images. If a blockage is found and needs treatment, a balloon can be pushed through the catheter and inflated to open the artery or arteries in question. A stent or tiny wire mesh tube can then be inserted to keep the artery open.
This procedure is done in the hospital.
A computerized tomography (CT) scan uses X-rays and computers to get detailed pictures of the body. Coronary artery calcification CT scans can detect calcium in the coronary arteries which may indicate the presence of coronary artery disease. A CT coronary angiogram uses x-ray dye (contrast) to look at blood flow patterns within the coronary arteries to detect blockages. This provides information similar to the catheter based angiogram, but is not as invasive.
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Treatments for Coronary Artery Disease
In some cases, coronary artery disease can be managed with lifestyle changes that include reducing risk factors. These include:
- Quitting smoking
- Modifying your diet
- Keeping your blood pressure under control
- Exercising (check with your doctor before beginning any exercise program)
- Reducing stress
If lifestyle changes aren't enough to control your coronary artery disease, you may need to take one or more medications to help your heart and arteries function better so that you receive sufficient oxygen-rich blood. These include:
- Cholesterol-lowering drugs: These drugs, often called statins, can decrease the amount of cholesterol in the blood, especially LDL or "bad" cholesterol. The drugs can also increase the amount of HDl or "good" cholesterol. The drugs can reduce the deposits that clog coronary arteries.
- Aspirin: Your doctor may recommend you take a daily aspirin tablet or other blood thinner to help reduce the tendency for your blood to clot.
- Beta-blockers: These are drugs that slow your heart rate and lower your blood pressure, reducing your heart's demand for oxygen.
- Nitroglycerin: This medication is taken during an angina attack, usually in the form of a tablet placed under your tongue. The drugs control chest pain by opening up the coronary arteries.
If you have a severe blockage in one or more arteries, you may benefit from a procedure known as angioplasty or percutaneous coronary intervention or revascularization (PCI).
An angioplasty can:
- Improve blood flow to your heart
- Relieve chest pain
- May be able to prevent a heart attack
An angioplasty opens blocked or narrowed coronary arteries. During angioplasty, a thin tube with a balloon on the end is threaded through a blood vessel to the narrowed or blocked coronary artery. Once in place, the balloon is inflated to push the plaque that is blocking your artery against the artery wall. This widens the artery and restores the flow of blood. A thin wire mesh tube called a stent may be placed in the artery permanently to keep the artery open. Some stents are coated with medication to help keep the artery open.
An angioplasty is done in the hospital and can take from 30 minutes to three hours. It is done under local anesthesia to numb the area of the groin where the catheter is inserted. Afterwards, you must remain in bed for at least another six hours. You may be able to go home the same day, but more often you will need to spend the night in the hospital.
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Coronary Artery Bypass Graft (CABG) Surgery
In coronary artery bypass graft (CABG) surgery, arteries or veins from other areas in your body are used to bypass or go around your narrowed coronary arteries. CABG can improve blood flow to the heart, relieve pain and possibly prevent a heart attack. A CABG is open-heart surgery. As a result, it is often used in cases where multiple coronary arteries are blocked or where the blockages are not suitable for angioplasty or stenting.
About CABG Surgery
CABG surgery involves exposing the heart through either the breastbone or the ribs. The operation typically includes the use of a heart-lung machine, which takes blood from the heart, adds oxygen, and then pumps it back into the body. Your surgeon may take an artery from the chest wall or remove a section of vein from your leg. These vessels are then grafted to the blocked arteries above and below the blocked areas. After the grafts are sewn into place, the heart-lung machine is turned off. The breastbone is wired together and the chest is closed. You are under general anesthesia during the operation. The CABG operation takes four to five hours.
Afterwards, you will be taken to the ICU where you will be on a heart monitor, have a breathing tube in your mouth, and a catheter in your bladder. You will also have temporary pacing wires and drainage tubes in your chest, and have several intravenous catheters in your neck and arms. You will probably remain in the hospital for four to five days and should be able to return to office-type work in four to six weeks. Because the bypass arteries can also clog, you must pay close attention to your diet, take aspirin and other medications as prescribed by your doctor, exercise regularly and maintain a healthy lifestyle to keep this from happening.
Off-Pump Beating-Heart CABG Surgery
In some cases, your surgeon may want to perform your bypass while your heart is still beating. This operation uses special equipment to stabilize or quiet the heart down while the surgery is ongoing. The heart-lung machine is not used. The remaining details of the surgery are the same as conventional CABG. The goal of off-pump bypass surgery is to decrease the risks associated with the use of the heart lung machine, such as stroke, renal failure and need for blood transfusion. Not everybody is a candidate for off-pump CABG.
Endoscopic or Minimally Invasive CABG Surgery
Traditional CABG surgery — with or without the use of a heart-lung machine — requires a large incision dividing the breastbone. In endoscopic CABG surgery, your surgeon performs the bypass through a smaller incision or incisions, using a tiny endoscopic camera and smaller instruments. Also, the heart-lung machine is not used The operation is associated with less post-operative pain, a shorter hospital stay and a shorter recuperation. Not everybody is a candidate for endoscopic CABG. In most cases, it is reserved for those who need just one blocked artery bypassed.
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