Coronary Artery Disease (CAD) develops over time through a combination of calcium, fatty materials, and scar tissue which build up in a person's arteries that supply their heart with blood. A person's arteries provide oxygen and additional nutrients the heart needs in order to pump blood. CAD affects approximately fourteen-million persons in America alone.
Persons affected by CAD experience plaque which narrows their arteries, so their heart does not receive enough blood. The slowing of their blood flow may cause them to feel chest pain or angina. Should the plaque in their arteries develop to the point where the flow of blood is blocked completely, the person may experience a heart attack, or a sudden cardiac arrest. CAD is a major cause of both disability and death in America, claiming more lives than the next seven leading causes of death combined.
A person's heart consists of four chambers - an atrium and ventricle on both the left and right sides. Blood returns to a person's heart from veins in all parts of their body and flows through their right atrium. From their right atrium, the blood flows into their right ventricle, where it is pumped out to the person's lungs to receive oxygen. Oxygen-rich blood is then returned to the person's left atrium, flows into their left ventricle, and is pumped into their arteries, returning to various veins in their body. All of this happens in one heartbeat.
There are three major coronary arteries in a person's heart, two of which arise from a common stem referred to as the, 'Left Main Coronary Artery.' The left main coronary artery supplies the left side of the person's heart, with the left anterior descending (LAD) branch supplying both the left-lateral and back side of their heart. The Right Coronary Artery (RCA) supplies both the right and bottom parts of the person's heart. Children have inner linings of their coronary arteries which are smooth, permitting blood to flow through easily. As people age, both calcium and cholesterol build on the walls of their coronary arteries, making them less elastic and thicker. Pursuit of habits that are not healthy, to include diets that are high in fat and cholesterol, a lack of exercise, and smoking, speed up the process of fat and calcium deposit building within the lining of a person's coronary arteries. The process is referred to as, 'Atherosclerosis,' or, 'hardening of the arteries.' The plaque that builds up is somewhat like a firm shell with a soft core that contains cholesterol. Blood that strikes this shell during every heartbeat risks cracking this shell open, exposing the cholesterol at the core. The process can promote blood clotting; these clots can reduce blood flow even further, and may cause angina or block the flow of blood entirely.
CAD Risk Factors
CAD risk factors involve ones which people can control, modify, or treat, and those they cannot. The more risk factors a person's has, the greater their chance of developing CAD. The greater the level of risk involved with each factor, the greater the overall risk the person is at. Risk factors that people are unable to change include:
Age: Greater than eighty-three percent of persons who die from CAD are older than age sixty-five. Of these people, women who experience a heart attack are more likely to die than men within a few weeks.
Men: Men have a greater risk of heart attack than women. Men tend to have heart attacks earlier in life as well.
Heredity: Children whose parents have heart disease are at greater risk of developing heart disease themselves. African-Americans experience more severe high blood pressure than Caucasians and are at greater risk of heart disease. American Indians, native Hawaiians, Asian-Americans, and Mexican-Americans are all at greater risk of heart disease as well. Persons with a strong family history of heart disease many times have more than one risk factor.
There are a number of risk factors that people can either control, modify, or treat. Some of these involve changes in lifestyle, others involve medications. What follows is a list of risk factors that people can work with:
Smoking/Tobacco Use: People who smoke have a risk for developing CAD that is two to four times greater than that of people who do not smoke. Cigarette smoke is an independent factor for sudden cardiac death in persons with CAD, as well as acting to increase other risk factors for the disease. People who smoke pipes or cigars also have a greater risk of death from CAD and potentially stroke, although their risk is not as great as for cigarette smokers. Secondhand smoke increases the risk for nonsmokers. Persons who use chewing tobacco are also at increased risk.
High Cholesterol: Increased levels of cholesterol means increased risk for CAD. When a person also has additional risk factors, such as high blood pressure and smoking, the risk is even higher. Cholesterol levels are also affected by things such as gender, age, diet, and heredity.
High Blood Pressure: High blood pressure increases the workload on a person's heart as well as causing their heart to both thicken and become stiffer. High blood pressure increases a person's risk of experiencing a heart attack or stroke, as well a kidney failure and congestive heart failure. People who smoke, or are obese, who also have high blood pressure have an increased risk of a heart attack or stroke that is several times that of others in this risk group.
Obesity/Overweight: Persons who are either obese or overweight, particularly if they carry that weight around the waist, are at greater risk of a heart attack or stroke; even if they have no additional risk factors. Obesity and being overweight makes a person's heart work harder, raising their blood pressure, blood cholesterol and triglyceride levels, while lowering their HDL cholesterol levels. Extra weight may also make development of diabetes more likely.
Physical Inactivity: Lack of an active lifestyle is a risk factor for coronary heart disease. Pursuit of moderate-to-vigorous physical activity helps to prevent both heart and blood vessel disease; the more vigorous the activity, the greater the benefit. Moderate intensity exercise pursued regularly over the long-term can help as well. Physical activity assists in controlling things such as a person's blood cholesterol, obesity, diabetes, and can help to control blood pressure in some persons.
Diabetes: Diabetes presents a serious risk for the development of cardiovascular disease. Despite good blood sugar control, diabetes increases the risk of both stroke and heart disease, although these risks are greatly increased if blood sugar control is poor. Approximately three-fourths of persons with diabetes die from a form of either heart or blood vessel disease.
Stress: People respond to stress individually, and stress may be a contributing factor to CAD. Person's under stress may react through overeating, smoking, or pursuing additional habits that presents risks.
Alcohol Consumption: Drinking excessive quantities of alcohol may raise a person's blood pressure and cause a heart attack or stroke. Excessive consumption of alcohol may contribute to high triglycerides, cancer, or other diseases. Drinking too much alcohol can produce irregular heartbeats in an individual, as well as contribute to alcoholism, obesity, accidents, or suicide.
Sleep Apnea: Sleep apnea is a disorder where a person's breathing either becomes very shallow, or stops completely while they are asleep. Sleep apnea that is untreated raises a person's chance of high blood pressure, diabetes, heart attack, and stroke.
Any problem with a person's coronary arteries which prevents their heart from receiving enough blood containing appropriate levels of oxygen and nutrients can cause coronary artery disease. The most prevalent form of CAD is Atherosclerosis. A lack of sufficient blood is referred to as, 'Ischemia,' leading many to refer to CAD as, 'Ischaemic Heart Disease.'
The risk factors mentioned above all contribute to to CAD. When a person experiences damage due to risk factors, their body begins a healing process. Excess fatty tissues release compounds that promote the healing process. Unfortunately, the healing also causes plaque to build up, damaging the person's arteries. Plaque build up can begin in childhood, developing over time to the point where narrowing may occur and completely block some of the person's arteries, reducing the flow of blood to their heart. The plaque may also crack, causing platelets to clump and form clots around the cracks, narrowing the person's arteries further and worsening angina or causing a heart attack. CAD is the leading cause of death in America among both women and men, with half a million persons dying each year from CAD.
Some persons with CAD experience no signs or symptoms - something called, 'Silent CAD.' Silent CAD may remain undiagnosed until the person presents some sign or symptom of heart failure, heart attack, or an arrhythmia. A common symptom of CAD is angina, which is a discomfort or chest pain a person experiences when their heart muscle is not receiving enough oxygen-rich blood. Angina might feel like a squeezing pain or pressure in the chest, jaw, neck, shoulders, arms, or back. The pain tends to worsen with activity, decreasing or disappearing when the person rests. Emotional stress can also trigger angina. It is important to contact a health care provider if you experience any of the following symptoms that are suggestive of angina:
A Fainting spell
Palpitations or dizziness
Shortness of breath after exertion
Pain in the upper part of your abdomen
Unexplained nausea, vomiting, or sweating
Jaw pain that is unexplained by another cause
Shoulder or arm pain involving left, right, or both sides during physical or mentally stressful activity
Chest pain, pressure or feeling of indigestion after physical exertion, which may or may not be relieved by rest
Shortness of breath is another symptom of CAD, occurring if CAD causes heart failure. When a person experiences heart failure, their heart is unable to pump enough blood throughout their body. Fluid builds in their lungs, making it difficult for them to breath. The severity of the symptoms vary, becoming more severe as plaque buildup continues to narrow a person's arteries.
Chest pain and discomfort are are the most common symptoms of a heart attack; the symptoms present themselves in the center of the person's chest and may last for more than a few minutes, or go away and then return. The pains may feel like a squeezing, pressure, or, 'fullness,' that can be either mild or severe. Heat attack pain may sometimes feel similar to either indigestion or heartburn. Heat attacks may cause pains in a person's upper body - such as in their arms, back, neck, jaw, or stomach. The person may feel out of breath or fatigued before they occur, or they may not feel any chest pain. Additional symptoms of a heart attack include nausea and vomiting, light headed-ness or fainting, as well as cold sweats.
Heart failure, on the other hand, involves a condition where a person's heart is unable to pump adequate amounts of blood throughout their body. Heart failure does not mean that their heart is stopped working, or is about to. What it means is that their heart is unable to fill with enough blood, or pump it with enough force, or both. Heart failure can cause a person to experience shortness of breath, fatigue, and swelling in their abdomen, legs, ankles or feet.
An, 'Arrhythmia,' is an issue with either the speed or rhythm of a person's heartbeat. When a person has an arrhythmia, they may notice that their heart skips beats, or beats too fast. Sometimes arrhythmias may cause a person's heart to stop beating entirely, a condition referred to as, 'Sudden Cardiac Arrest (SCA).' SCA may cause a person to faint, and could cause death if it is not promptly treated.
The first symptoms that a person experiences in association with CAD may be either a heart attack or sudden cardiac arrest. Medical professionals use screening tests to detect both the presence and severity of coronary disease prior to problems that send a person to the emergency room with severe symptoms. The symptoms of CAD are referred to as, 'non-specific,' by medical professionals, meaning that they could be caused by a number of different conditions, or be unrelated to the person's heart at all. The process of diagnosis is partly to rule out any other causes of the symptoms the person is experiencing.
A doctor will review the person's family history, medical history, and perform a physical examination. The doctor will ask questions about the symptoms the person is experiencing, the person's general health, any specific medical problems they are having, as well as asking about any medications the person is taking. The doctor will most likely perform an ECG, and may take laboratory tests, or imaging tests such as X-rays or CT scans.
A physical examination can show evidence of either irritable or weakened heart muscle, to include sounds of murmurs or, 'gallops,' in the person's heartbeats. The examination may reveal evidence of lung congestion as well. Blood testing can be used to check the person's blood cells, their chemical makeup, as well as for enzymes that leak out of damaged heart muscle, suggesting that a person may be experiencing a heart attack. An ECG measures the electrical activity of the person's heart, and is a diagnostic tool the doctor will most likely use to look for a number of different heart problems. An ECG can reveal things such as ischemia, rhythm disorders, heart attacks, strain on the person's heart that is long-standing from high blood pressure, as well as some valve issues. A chest X-ray may reveal any abnormalities related to the shape or size of the person's heart, as well as showing whether or not fluid is building up in their lungs.
Another form of test a doctor may order is a stress test. A stress test is used for persons who are experiencing angina. The test involves measurement of ECG tracings before, during, and after the person exercises on a treadmill while connected to an ECG machine. The stress test is approximately sixty to seventy-percent accurate in showing blockages in blood flow in one or more of the three coronary arteries.
There is a test known as a, 'Nuclear Stress Test,' that a doctor may order as well. The test involves injection of a tiny dose of radioactive tracer into the person's vein; a camera identifies the amount of blood flow that reaches different parts of the person's heart muscle. The radioactive tracer substance most commonly used is, 'Thallium;' many times this test is referred to as a, 'Thallium Stress Test.'
An alternative to the nuclear stress test is an, 'Echocardiography.' A number of people prefer this test to the nuclear stress test because it does not involve the use of a radioactive substance. An Echocardiography involves the use of a form of sonar which uses sound waves that bounce off the person's walls and valves, creating an image of their heart as it functions. The images that are obtained, both while the person is under stress and while resting, can assist a doctor in a diagnosis. Should the person have a significant coronary artery obstruction, the wall motion of their heart during stress drops.
Perhaps the best way to evaluate CAD is through use of Coronary Angiography. Coronary Angiography involves outpatient day surgery. A doctor uses an X-ray camera, as well as a catheter which is threaded into the opening of the person's coronary arteries from a blood vessel in either the person's arm or their groin. When the catheter is in the person's coronary artery opening, the doctor injects a small amount of iodine, making the person's arteries visible on the X-ray screen so the doctor can take pictures for later review. The pictures show not only the diameter of the person's arteries, but reveal any blockages that may be present. A Coronary Angiography is the only test that a cardiologist can use to help them to determine precisely whether a person needs treatment through bypass surgery, angioplasty, stent placement, or simply medication treatment.
Treatment for CAD can be approached from some different angles. Treatment has the goals of balancing the supply of blood to the person's heart with demand for oxygen, while preventing the worsening of symptoms associated with coronary artery disease. What follows are some methods of treating CAD.
Aspirin: Common aspirin, when taken either daily or every other day, can reduce the risk of developing angina or a heart attack by reducing the tendency for blood to clot. Aspirin reduces the chance that a clot will form over a crack in plaque that has formed over the coronary artery.
Beta-Blockers: Beta-Blockers decrease a person's heart rate and blood pressure, therefore reducing the heart's demand for oxygen.
Nitroglycerin: Nitroglycerin helps through reduction of chest pain. The medication decreases the heart's demand for oxygen by dilating the person's coronary arteries, increasing their supply of oxygen. The medication is administered through either a spray, or tablets that are placed underneath the person's tongue, providing instant relief from angina. Longer acting forms of nitroglycerin are available through either tablets or patches which work over a period of several hours.
Calcium Channel Blockers: Calcium Channel Blockers dilate a person's coronary arteries in order to improve the flow of blood through them. They reduce the person's blood pressure, as well as slowing their heart rate.
ACE Inhibitors: Angiotensin-Converting Enzyme (ACE) inhibitors dilate a person's blood vessels and increase the person's blood flow, reducing the risk for heart attacks, cardiac events, and death in persons with CAD. ACE inhibitors are very useful in persons who also have weakened heart muscles, or diabetes.
Statins: Statin medications reduce the amount of cholesterol and fats in a person's blood, changing the inner lining of their blood vessels so that plaques are less likely to form or enlarge. Statins are able to either slow, or potentially stop, the progression of CAD and may prevent further heart attacks as well.
Should symptoms of angina persist and worsen despite the use of medications, there are procedures that are more invasive that could be used. The procedures are performed by a cardiologist instead of a cardiac surgeon. These procedures involve fewer complications than more involved surgeries, yet are more involved than medication treatment.
Coronary Angioplasty: A Coronary Angioplasty is somewhat like a Coronary Angiography, although the procedure is therapeutic as well as diagnostic. A catheter is inserted into the person's artery via an artery in their arm or groin. A very thin wire is threaded through the catheter and into the person's coronary artery. An even thinner catheter is threaded over the wire into the blocked artery, with a tiny balloon on the end. With the balloon in place at the point of blockage in the person's artery, the balloon is inflated, widening the person's artery and improving the blood flow through it. The balloon catheter is removed along with the wire and the other catheter.
Stent: A stent is a small, coil-like, sieved metallic tube which is mounted over a balloon. The balloon is inflated at the point of blockage in the person's artery, expanding the stent. When the balloon is withdrawn, the stent remains in place, keeping the person's artery open. Arteries treated with a stent have the potential to close again, although they are a longer-lasting solution.
Atherectomy: An Atherectomy is something that may be pursued for person's who have plaque that has become to bulky, rigid, or calcified to treat with either angioplasty or a stent. Atherectomy involves the use of a drill-like device to remove plaque from a person's artery, although it only works if the narrowing or blockage is limited to a small or self-contained portion of the artery. Plaque may also be burned away using an Excimer Laser Atherectomy (ELCA). Devices that are commonly used during an Atherectomy include rotational atherectomy, directional atherectomy catheter (DCA), or rotablator, AngioJet, or transluminal extraction catheter (TEC).
Brachytherapy: Brachytherapy involves the application of radiation to clear the blockage in the person's artery. The radiation is applied from a source which is placed either inside, or very near the person's artery. The procedure is used to treat person's whose arteries have already undergone either angioplasty or stenting, yet continue to experience blockages.
Surgery is a form of treatment that is reserved for persons with CAD that is either severe, or has either not improved or stabilized through administration of medications or less invasive forms of therapy. There are some different forms of surgeries that a doctor may perform:
Coronary Artery Bypass Grafting (CABG): CABG is a standard operation to treat blocked coronary arteries. If the person has more than one coronary artery that is blocked, or if their left main artery is significantly blocked, bypass surgery is usually the best form of treatment. During the surgery, the parts of the person's arteries that are blocked are bypassed with blood vessels that have been harvested from their leg, arm, or chest. The person's heart is temporarily stopped and they are connected to a machine referred to as a, 'Bypass Pump,' which functions as the person's heart. The operation has a high rate of success, with minimal complications.
Off-Pump Bypass Surgery: There are times when a surgeon is capable of performing open heart surgery without the use of a bypass pump and while the person's heart is beating. The procedure has fewer side-effects than the standard one, although it is not always possible.
Minimally-Invasive Coronary Bypass (MINI-CABS): MINI-CABS is appropriate if the it is only the person's front or right coronary arteries that require a bypass. The surgeon may replace the person's blocked artery with an artery from their chest through a small, keyhole incision without opening the person's chest.
Trans-myocardial Laser Revasularization (TMR): TMR is an alternative for person who are not potential candidates for either bypass surgery or angioplasty. During TMR a surgeon uses a laser catheter in order to create a number of pinholes in the person's heart muscle. These holes encourage the growth of new vessels in the heart muscle. TMR is a procedure that can be performed alone, or in conjunction with a coronary bypass surgery.