“You have coronary heart disease.” When your doctor says those words to you or to someone you love, it’s frightening and confusing. You probably have dozens of questions: What is coronary heart disease? Do I need to change my lifestyle?
Coronary heart disease (CHD), also called coronary artery disease (CAD) or ischemic heart disease, is a form of heart disease that’s caused by narrowing of the coronary arteries that feed the heart. If you or someone you love has been diagnosed with CHD, it may help to know that you are not alone. In fact, CHD is the most common form of heart disease, affecting at least 12 million Americans. It is the single largest killer of both men and women in the United States, responsible for nearly a half million deaths each year, or about 1 out of every 5 deaths. CHD causes nearly all heart attacks (myocardial infarctions). Every 29 seconds, an American suffers a coronary event (a heart attack or fatal CHD), and every minute one of us will die from one. The american Heart Association estimates that this year alone, more than a million Americans will suffer from a new or recurrent coronary event, and nearly 40 percent of those will die from it.
Coronary heart disease isn’t just an American problem. CHD is very common in other Westernized countries, too, such as many in Europe. Diseases of the heart and circulation such as heart attacks and stroke (a “brain attack”) kill more people worldwide than any other cause. The World Health Organization estimates that as many as 30 percent of all deaths are caused by heart and circulation diseases like CHD.
The good news is that you don’t have to become another CHD statistic. There is a lot you can do to reduce your risk of having a heart attack or dying from CHD. Sometimes just changing your lifestyle – following a heart-healthy diet, exercising regularly, and reducing the stress in your life-can prevent a heart attack or even reverse the narrowing in your arteries. There are a number of medications-and new ones being developed every day-that can help lower your heart attack risk. Surgical procedures such as angioplasty and stenting or bypass surgery can help compensate for blockages in your arteries and help keep your heart supplied with the blood it needs. By educating yourself about your treatment options, and working closely with your doctor you and your doctor can choose the best treatments that will enable you to live a long and healthy life.
The Circulatory System
The first step in taking charge of your CHD is to learn all you can about the disease. To understand what CHD is and how it affects your heart, you need to understand a little about your heart and how it works.
Your circulatory system, also called your cardiovascular system, is made up of the heart, the lungs, and blood vessels called arteries and veins. This system carries blood, food, and oxygen to every cell in the body. It also carries waste products away from the cells and out of the body. (A cell is a building block of every tissue and organ in the body.) Think of your circulatory system as a busy highway system composed of massive freeways and large streets that feed into smaller and smaller streets, and finally into tiny lanes and alleyways. This system is made up entirely of one-way streets. In our imaginary highway system, cars, or in this case, blood, can flow in only one direction. The one-way streets called arteries and arterioles (small arteries) carry blood enriched with oxygen and nutrients away from the heart to the cells in the body. The one-way street called veins and venules (small veins) carry blood loaded with waste products from the cells back to the heart.
Between these two one-way street systems are tiny blood vessels called capillaries. Almost too tiny to see and often thinner than a strand of hair, capillaries connect the smallest arteries with the smallest veins. They are the brides that connect our two systems of one-way streets. The walls of these tiny capillaries are so thin that food and oxygen in the blood pass through them into the surrounding cells. These thin walls also allow waste products from the cells to pass into the capillaries. This enables the blood to carry waste from the cell to be removed by the kidneys, liver, and lungs.
If you can imagine a single drop of blood flowing through this system, it might look something like this. The blood droplet, full of oxygen and nutrients, (fuel), is pumped out of the left side of the heart into the largest arteries. There is flows into progressively smaller arteries and finally into the capillaries, where it delivers its load of oxygen and food for the cells. At the same time, the blood picks up waste products from the cells and flows into tiny veins, then into larger and larger veins. Finally, the blood droplet arrives back at the right side of the heart, where it’s pumped into the lungs and unload carbon dioxide, pick up a fresh supply of oxygen, and begin its circular journey again.
The Heart: An Amazing Pump
The heart is the pump that keeps the blood flowing around and around in an endless circle throughout the body. Think of it as the traffic cop that coordinates the flow of traffic throughout our highway system. The heart is a hollow muscle that weighs less than a pound and is about the size of a man’s fist. Despite its small size, this amazing organ an average of 100,000 times a day, pumping about 2,000 gallons of blood every day. If you live to be 70, your heart will beat more than 2.5 billion times.
Located in the center of the chest and protected by the breastbone and rib cage, the heart is actually a double pump thats divided into four chambers, two upper ones and two lower ones. A thin wall of muscle separates the left and right sides of the heart. The top chamber (atriums or atria) and lower chambers (ventricles) are connected by valves that act like one-way doors. These valves make sure blood flows only in one direction. In the heart, the blood is pumped from the left and right atriums to the left and right ventricles. The right side of the heart sends blood to the lungs. The left side of the heart pumps blood out to the cells in the body.
Just like other muscles in the body, the heart needs its own supply of blood and oxygen to work properly. Even though the heart pumps blood through its chambers, the heart itself receives no significant nourishment from this blood. There is a separate set of arteries that branch off the aorta (the main artery that receives blood from the left ventricle) that provide the heart’s blood supply. These are called coronary arteries. The coronary arteries encircle the top and sides of the heart bringing plenty of oxygen-rich blood to the heart. The two major coronary arteries are the left coronary artery and the right coronary artery. These vessels divide into many smaller coronary arteries that feed the heart.
What Is Coronary Heart Disease?
Healthy coronary arteries have smooth, flexible walls that provide plenty of blood to the heart. However, over many years, these flexible walls can become progressively irritated and damaged by such substance as fats, cholesterol, calcium, cellular debris, and platelets (tiny cells responsible for blood clotting). When the walls of the arteries are damaged, these substances are able to “stick” to them. Coronary heart disease (CHD) occurs when these coronary arteries become narrowed and clogged.
This buildup inside the artery walls is a process called atherosclerosis, which produces a substance known as plaque. As it builds, plaque is a lot like the dirt, fat, and minerals that build up inside your home’s plumbing. As the buildup becomes thicker, the flow through the pipes becomes less and less and may even completely stop. Similarly, when your heart doesn’t get enough oxygen due to narrowed arteries, you may feel chest pressure or pain called angina. If the blood supply to part of the heart is completely cut off, the result is often a heart attack.
Everyone has a certain amount of atherosclerosis as they age. For many of us, atherosclerosis begins in childhood. Some people have a rapid increase in the buildup of atherosclerotic plaque after age 30. For others, plaque buildup does not become a problem until we’re in our 50s or 60s.
What Causes CHD
We don’t know for sure why atherosclerosis occurs or even how it begins, but there are several theories. Some medical experts believe the atherosclerotic buildup in the inner layer of the arteries may be caused by several conditions, including:*Elevated levels of LDL cholesterol (low-density lipoprotein) and triglycerides in the blood*Low levels of HDL CHOLESTEROL (high-density lipoprotein)*High blood pressure*Tobacco smoke*High blood sugar levels (diabetes mellitus)*Inflammation.
It’s likely that more than one process is involved in the buildup of plaque. Many researchers believe that when excess fat combine with oxygen, they become trapped in the arterial wall. This attracts white blood cells which help prevent infection when tissue is damaged. Then substances call prostaglandins, which are involved in blood clotting and altering tone (firmness) within arteries, become active. Any injury to the artery wall, such as damage caused by smoking, can activate prostaglandins. The activated prostaglandins stimulate more plaque growth and narrow arteries and/or cause blood clots to form.
Regardless of how plaque forms, advanced plaque is made up mostly of living cells. In fact, about 85 percent of advanced plaque consists of cell debris, calcium, smooth muscle cells, connective tissue, and foam cells (white blood cells that have digested fat). About 15 percent of advanced plaque is made up fatty deposits.
Once the plaque develops, plaque containing cells can be easily damaged. This can lead to blood clots forming on the outside of the plaque. Small clots can further damage other layers of the blood vessel wall and stimulate more plaque growth. Larger blood clots can partially or totally block the artery.
In addition to interfering with or totally blocking blood flow, plaque can hinder the arteries ability to dilate and contract. In order to respond to the bodies ever-changing need for blood, the arteries need to be strong and elastic. For instance, when you exercise, your body needs more blood. The heart responds by pumping faster, and the arteries respond by expanding to accommodate the increased volume of blood expanding to accommodate the increased volume of blood coming from the heart. As the artery becomes narrowed and hard, that elasticity is lost. Arteries that have atherosclerotic plaque are more apt to spasm (temporarily narrow), causing even less blood to flow to the heart and possible causing chest pain or heart attack.