Coronary artery disease (CAD) is the leading cause of death in the United States, affecting over 5 million Americans. CAD is a narrowing of the coronary arteries, the vessels that supply blood to the heart muscle, generally due to the buildup of plaques in the arterial walls, a process known as atherosclerosis. Plaques are composed of cholesterol-rich fatty deposits, collagen, other proteins, and excess smooth muscle cells.
Atherosclerosis, which usually progresses very gradually over a lifetime, thickens and narrows the arterial walls, impeding the flow of blood and starving the heart of the oxygen and vital nutrients it needs (also called “ischemia”). This can cause muscle cramp-like chest pain called angina.
Blood clots form more easily on arterial walls roughened by plaque deposits and may block one or more of the narrowed coronary arteries completely and cause a heart attack (see myocardial infarction for more information). Arteries may also narrow suddenly as a result of an arterial spasm. (Spasms are most commonly triggered by smoking.)
Although CAD can be a life-threatening condition, the outcome of the disease is in many ways up to the patient. Damage to the arteries can be slowed or halted with lifestyle changes, including smoking cessation, dietary modifications and regular exercise, or by medications to lower blood pressure and cholesterol levels. Additional goals of treatment, which may involve medication and sometimes surgery, are to relieve symptoms, ease circulation and prolong life.
- If you experience crushing chest pain, with or without nausea, vomiting, profuse sweating, shortness of breath, weakness or intense feelings of dread.
- If chest pain from previously diagnosed angina does not subside after 10 to 15 minutes.
- The first time you experience intense chest pain.
See your doctor if attacks of previously diagnosed angina become more frequent, more severe or occur at rest.
In the early stages of coronary artery disease, there are generally no symptoms, but the disease can start when a patient is very young (pre-teen). Over time, fat builds up and can injure the vessel walls where plaques will begin to adhere and collect. In attempt to heal the troubled area, blood may form a clot around the plaque causing the artery to narrow even further preventing the flow of blood and oxygen which can cause chest pain (angina pectoris) during periods of physical activity or emotional stress (times that require increased amounts of oxygen). Angina usually subsides quickly with rest, but over time, symptoms arise with less exertion and CAD may eventually lead to a heart attack. However, in one-third of all CAD cases, angina never develops and a heart attack can occur suddenly with no prior warning.
You should call 911 immediately if you experience any of the following symptoms of CAD:
- Chest pain (angina), or milder pressure, tightness, squeezing, burning, aching or heaviness in the chest, lasting from 30 seconds to five minutes. The pain or discomfort is usually located in the center of the chest just under the breastbone and may radiate down the arm (usually the left), up into the neck or along the jaw line. The pain is generally brought on by exertion or stress and stops with rest. The amount of exertion required to produce angina is reproducible and predictable. Angina can be mistaken for heartburn or indigestion.
- Shortness of breath, dizziness or a choking sensation, accompanying chest pain.
- Rapid or irregular heartbeats.
- A sudden increase in the severity of angina, or angina at rest, is a sign of unstable angina that requires immediate medical attention because a heart attack may shortly occur.
If you call 911, you may be advised to chew an aspirin to break up a possible blood clot, if there is not a medical reason for you to avoid aspirin.
In CAD, narrowed coronary arteries limit the supply of blood to the heart muscle. If narrowing is not extensive, difficulties may occur only during physical exertion, when the narrowed arteries are unable to meet the increased oxygen requirements of the heart. However, as the disease worsens, the narrowed arteries may starve the heart muscle of oxygen during periods of normal activity, or even at rest.
- Smoking promotes the development of plaque in the arteries. Also, by increasing the amount of carbon monoxide in the bloodstream and decreasing the amount of oxygen available to the heart, smoking increases the likelihood of angina.
- High blood cholesterol levels lead to coronary artery disease. LDL (low-density lipoprotein) enters the lining of the arterial walls where, after being chemically altered, its cholesterol can be incorporated into plaque (see hypercholesterolemia for more information).
- High blood pressure predisposes one to CAD.
- People with diabetes mellitus are at greater risk for atherosclerosis.
- Obesity may promote atherosclerosis.
- Lack of exercise (a sedentary lifestyle) may encourage atherosclerosis.
- Men are at greater risk than women for coronary artery disease, although the risk for postmenopausal women approaches that of men as estrogen production decreases with menopause. Ongoing studies will determine whether this risk may be partly offset by estrogen replacement therapy.
- Women over age 35 who take oral contraceptives and smoke cigarettes have a higher risk of atherosclerosis.
- A family history of premature heart attacks is associated with greater CAD risk.
- A spasm of the muscular layer of the arterial walls may cause an artery to contract and produce angina. Spasms may be induced by smoking, extreme emotional stress or exposure to cold air.
It is important that you know the symptoms of a heart attack so that you can recognize the situations that may cause them and respond quickly in an emergency. You can reduce your risk for heart attack by taking steps to living a healthier lifestyle.
- Don’t smoke.
- Eat a diet low in saturated fat, cholesterol and salt.
- Pursue a program of moderate, aerobic exercise for at least 30 minutes, three days a week. People over age 50 who have led a sedentary lifestyle should check with a doctor before beginning an exercise program.
- Lose weight if you are overweight.
- See your doctor regularly to have your blood pressure and cholesterol measured.
- Your doctor may advise you to take a low dose of aspirin every day if you are at high risk for CAD. Aspirin reduces the tendency for the blood to clot, thereby decreasing the risk of heart attack. However, such a regimen should only be initiated under a doctor’s recommendation.
- Women at or approaching menopause may want to discuss the possible cardioprotective benefits of postmenopausal estrogen replacement therapy with their doctors.
With its multidisciplinary team of cardiologists, an endocrinologist and a nurse practitioner, The Johns Hopkins Ciccarone Center for the Prevention of Heart Disease, directed by Dr. Roger Blumenthal, specializes in managing adults who are at high risk for future cardiovascular disease either because of risk factors such as hypertension, diabetes, high cholesterol, cigarette smoking, sedentary lifestyle, known family history of heart disease or peripheral arterial disease.
Our personalized, comprehensive approach to lifestyle and medical management can slow the progression of cardiovascular disease and decrease one’s future risk of heart attack, stroke, bypass surgery or angioplasty. We also sponsor research that includes both clinical trials and basic molecular studies.
To be evaluated for CAD at Johns Hopkins, you will first be examined by one of our cardiologists at the Johns Hopkins Outpatient Center or Johns Hopkins Heart Health. As part of your diagnosis, you may undergo one or more of the following tests:
- An electrocardiogram also called an ECG or EKG, to record your heart’s electrical activity during rest to determine abnormal heart rhythms. In some cases your doctor may provide you with a portable ECG device, known as a Holter monitor, in order to record the electrical activity of the heart over a 24-hour period.
- Blood tests to measure circulating levels of cholesterol or triglycerides (fats). The doctor will also look at nontraditional risk factors such as the substances homocysteine, hs-CRP (C-reactive protein), lipoprotein A (Lpla) and ApoB (apoprotein B) and will perform specific tests to assess kidney and liver function.
- Exercise stress tests also known as treadmill tests, help determine irregular heart rhythms during exercise. During this test, the heart’s electrical activity is monitored through small metal sensors applied to your skin while you exercise on a treadmill. The doctors may inject a radioactive substance called thallium during the last minute or so of the test to gauge blood flow to the heart. You will then lie on a table while the doctor runs a special camera over your chest. The camera picks up information from the thallium, which is translated into images on a computer monitor. Often we will do a treadmill stress echocardiogram instead of a stress thallium test. An echocardiogram (ultrasound) is done before and after exercise to determine if the heart muscle contracts more vigorously after exercise.
- Your doctor may order an echocardiogram to evaluate heart function. During this test, sound waves bounced off the heart are recorded and translated into images. The pictures can reveal abnormal heart size, shape and movement. Echocardiography also can be used to calculate the ejection fraction, or volume of blood pumped out to the body when the heart contracts.
- Coronary angiography, or X-ray of the heart’s blood vessels, may be performed to evaluate possible narrowings of the coronary arteries. In this procedure a tiny catheter is inserted into an artery of a leg or arm and threaded up into the coronary arteries. A contrast material is then injected from the end of the catheter into the coronary arteries, which provides a clear image of the blood vessels on X-ray.
- Depending on your family history, your doctor may also recommend that you get a coronary artery calcium scan, a test which is affiliated with HeartSavers -- a group that uses electron beam computed tomography (EBCT) to take up to 40 pictures of the heart between beats while you remain fully clothed. Images from the five-minute test show early calcium buildup, or plaque, which appear as white specks in the walls of arteries. We compare the measured amount of coronary calcium to the average amount for one’s age and gender. An EBCT scan is the best way to non-invasively assess cardiac risk in an adult.
The Johns Hopkins Hospital Cardiovascular Diagnostic Laboratory (CVDL) is a state-of-the-art imaging facility performing over 24,000 diagnostic and interventional procedures annually. The CVDL operates 11 procedure rooms.
There are three general areas within the CVDL: Cardiology, Radiology and Electrophysiology. The Cardiology section is involved in treating patients with disorders of the heart and vascular tree including coronary artery disease, congestive heart failure, valve disease, congenital heart defects, cardiomyopathy and peripheral vascular disease.
Patients with CAD can access a broad range of treatment services through Johns Hopkins, including the treatment of coronary artery and bypass graft blockages using:
- balloon angioplasty
- intracoronary stenting
- laser ablation
- rotational atherectomy
- directional atherectomy
- extractional atherectomy
- brachytherapy (local radiation therapy)
Lifestyle changes such as adopting a healthy, low-fat diet and increasing your level of physical activity can also be helpful. Patients should also avoid excessive alcohol consumption, nasal decongestants and diet pills, all of which may raise blood pressure. Johns Hopkins nurse health educators specialize in helping people to improve their lifestyle habits. The Johns Hopkins Heart Health has an excellent cardiac rehabilitation program and clinical exercise program.
Since most CAD patients are treated with medication, it is important to know the “ABCs” of the drugs used to manage coronary artery disease:
(A) Antiplatelet/anticoagulants, such as aspirin, heparin or warfarin, prevent blood clots. ACE inhibitors or angiotensin receptor blockers, such as enalapril, prevent the detrimental effects of a hormone angiotension II that constricts blood vessels, thereby reducing blood pressure and dilating blood vessels.
(B) Beta blockers, such as propranolol or metoprolol, interfere with nerve receptors in the heart, to slow the rise of heart rate and blood pressure in response to stress or exercise.
(C) Calcium channel blockers, such as verapamil, diltiazem or nifedipine, reduce the ability of arterial walls to constrict; cholesterol-lowering medications lower heart attack and stroke risk.
If you have chest pain, rapidly acting nitrates, such as nitroglycerin, or longer-acting nitrates like isosorbide dinitrate, may be prescribed to dilate blood vessels and relieve or prevent symptoms of angina. A nitroglycerin tablet placed under the tongue (sublingually) at the onset of an angina attack usually relieves the pain within minutes. Sublingual nitroglycerin may also be taken just prior to activities that commonly provoke angina. However, for any given angina attack, you should not take more than three nitroglycerin tablets at five-minute intervals -- pain lasting longer than this may signal a heart attack. Intravenous nitrates may be administered in patients with unstable angina. Nitrates may also be prescribed in the form of patches or ointments for continuous protection.
Emergency treatment and immediate hospitalization is necessary if a heart attack occurs, commonly signaled by crushing, persistent chest pain (see myocardial infarction for more information).
Other courses of treatment may require any one of the following outpatient procedures to help open the blood vessels:
- Angioplasty, formally called percutaneous transluminal coronary angioplasty (PTCA), is a procedure to open up narrowed arteries. Using local anesthesia, the doctor will insert a catheter (a long, narrow tube) with a deflated balloon at its tip into the narrowed part of the artery. Then the balloon is inflated, compressing the plaque and enlarging the inner diameter of the blood vessel so blood can flow more easily.
- Atherectomy is a procedure to remove plaque from arteries. The doctor uses a laser catheter or a rotating shaver. The catheter is inserted into the body and advanced through an artery to the area of narrowing.
- Your doctor may implant a stent, a wire mesh tube used to prop open an artery that has recently been cleared using angioplasty. The stent is collapsed to a small diameter and put over a balloon catheter, then moved into the area of the blockage. When the balloon is inflated, the stent expands, locks in place and forms a scaffold to hold the artery open. The stent stays in the artery permanently, improving blood flow to the heart muscle.
- Radiation therapy, also called brachytherapy, is a procedure designed to keep arteries clear following angioplasty. A wire with a radioactive tip is threaded to the site of the narrowed artery, where it remains in place for three to five minutes and delivers a one-time dose of radiation.
- Coronary bypass surgery may be performed in more serious cases to improve blood flow to the heart. A mammary artery or a vein taken from the leg is grafted onto the damaged coronary artery to circumvent a narrowed or blocked portion.
If other treatments fail and the heart muscle has been too badly damaged, you may require a heart transplant. The survival rate for this surgery is 80 percent after one year and over 60 percent after four years.