Coronary artery disease (CAD), also known as coronary heart disease (CHD), occurs when the blood vessels that bring oxygen and nutrients to the heart muscle — the coronary arteries — become narrowed and blocked. It is the most common heart disease in the U.S., and the leading cause of death for men and women alike.
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Mild coronary artery disease often has no symptoms. In more advanced cases, many persons experience chest pain (angina pectoris), which results when a severely narrowed artery obstructs a significant amount of blood to the heart. Chest pain may be accompanied by shortness of breath.
Over time, lack of blood flow can overwhelm the oxygen- and nutrient-starved heart, causing heart attack. The heart simply pumps too hard to bring in the blood it desperately needs. Learn about heart disease risk factors.
Causes of Coronary Artery Disease
Coronary artery disease is caused by atherosclerosis, or hardening of the arteries. The term originates from the Greek words athero (gruel, or paste) and sclerosis (hardness). It is a process in which artery walls accumulate plaque — a waxy, fatty substance that contains cholesterol, cellular waste products, calcium and a blood-clotting protein called fibrin.
Arteries are hollow tubes that transport blood throughout our bodies. The walls of arteries are made of smooth, elastic muscle cells. A cell layer called the endothelium (pronounced en-do-THEE-lee-um; Greek for "inner layer") lines the artery walls and serves as a protective barrier between the blood stream and artery walls.
As we age, several factors can damage the endothelium:
- High levels of fats — cholesterol and triglycerides — in the bloodstream.
- Hypertension (high blood pressure), which puts pressure on artery walls.
- Smoking tobacco, which interferes with chemicals released by the endothelium.
- Insulin resistance and diabetes mellitus (type 2 diabetes).
According to research, when the protective endothelium becomes damaged, plaques are allowed to cling to the exposed artery wall. Attempting to heal the damage, the artery wall may release sticky chemicals that, unfortunately, encourage further artery-clogging plaque buildup.
Plaque deposits are hard on the outside and mushy on the inside. If a crack forms in a deposit's tough exterior, the body will try to seal the rupture by releasing blood-clotting platelets. A blood clot may form, blocking blood supply to the heart muscle and posing the risk of heart attack.
Risk Factors of Coronary Artery Disease
A risk factor is anything that enhances the likelihood of disease, but may not directly cause a disease. With coronary artery disease, there are two essential categories of risk factors: those that cannot be changed (nonmodifiable) and those that can be changed (modifiable).
Risk factors that cannot be changed include male gender, advanced age, family history of heart disease and race. Risk factors that can be changed include smoking, high cholesterol, elevated blood pressure, diabetes, physical inactivity, being overweight or obese, high-fat diet, excessive alcohol consumption and uncontrolled stress and anger.
Read an in-depth review of heart disease risk factors on JCL.com.
Lifestyle Modifications and Medications
Fortunately, a large percentage of coronary artery disease cases can be prevented and managed with simple lifestyle changes. Not smoking tops the list. Also important are regular exercise, along with eating a low-fat, low-sodium and low-cholesterol diet. See an in-depth list of ways to control your risk of heart disease risk.
Coronary Artery Disease Diagnosis
A coronary artery disease diagnosis begins with a review of symptoms, health history and a physical examination. Diagnostic tests may follow, including blood tests, an electrocardiogram (EKG) and an exercise stress test.
However, to conclusively pinpoint the location and severity of arterial blockage, a procedure called cardiac catheterization may be required. This nonsurgical procedure is both diagnostic and interventional in nature. In other words, if a blockage is located during the test, treatment to eliminate the blockage, using balloon angioplasty, can immediately follow.
Coronary Artery Disease Treatment
If lifestyle changes are not enough to control heart disease, a physician may prescribe medications to treat certain risk factors, such as high cholesterol or high blood pressure. Appropriate medications depend upon the presence of other health conditions and the severity of the heart condition.
Balloon angioplasty and coronary artery bypass grafting (CABG, pronounced cabbage) are the two most common procedures for eliminating blockages related to coronary artery disease.
In balloon angioplasty, a cardiologist will insert a narrow, flexible tube (a catheter) into the groin and guide it along blood vessels to the narrowed coronary artery. At the tip of the catheter is a tiny balloon, which is inflated to stretch open clogged arteries and flatten any plaque that may be blocking blood flow. When the balloon is deflated, a wire-mesh tube — called a stent — is inserted, to keep the artery open.
Coronary artery bypass grafting is an "open heart" surgical procedure that transplants a healthy blood vessel from another part of the patient's body. The harvested artery, or graft, serves as a detour route for blood flow, which travels around the obstructed coronary artery. Traditional CABG requires an incision be made down the chest. Also, the heart must be stopped and placed on a heart-lung machine. However, a new wave of minimally invasive techniques is enabling surgeons to perform CABG while the heart continues pumping. Learn more about coronary artery bypass grafting at John C. Lincoln.
Naturally, angioplasty offers numerous advantages over CABG. Although it does not require surgery or a heart-lung machine, and recovery is much quicker, angioplasty is not an appropriate treatment for all cases of coronary artery disease. The patient's age, overall health, related medical conditions and severity of blockage are factors that can influence the choice of therapy.