Cardiology: Everyone is At Risk for Coronary Artery Disease
When it comes to diseases, none claim more American lives than Coronary Artery Disease (CAD). It’s estimated that 1.3 million Americans suffer CAD, and each year more than half a million of them die as a result.
Experts agree that curbing this high mortality rate begins with education. Understanding the disease – and how to treat and prevent it – is the natural first step.
What is coronary artery disease?
Coronary artery disease results when the arteries that supply blood to the heart become hardened and narrowed because of a plaque buildup along their inner walls. As more and more plaque accumulates, the passageways within the arteries get narrower, stifling the heart’s blood supply. Eventually, the blood flow is reduced to the point that the heart doesn’t get all the oxygen it needs. This dangerous situation leads to a variety of conditions, such as:
Angina – Chest discomfort or pain that occurs when the heart does not get enough blood.
Heart Attack – If a blood clot develops at the plaque site, it can suddenly cut most or all of the heart’s blood supply. Without oxygen, the cells within the heart begin dying, which can cause irreversible damage to the heart muscle itself.
Furthermore, CAD can weaken the heart and contribute to the following conditions:
Heart Failure – Unlike a heart attack, heart failure doesn’t mean that the heart actually stops. What it does mean is that the heart is unable to pump blood effectively throughout the rest of the body. Although the heart is still beating, it isn’t pumping the way it should.
Arrhythmias – Changes in the heart’s normal rhythm. Some can be very serious.
Symptoms
The heart muscle works like a pump. It’s divided into four distinct chambers – two atria at the top and two ventricles at the bottom. It beats when it receives an electrical pulse from the sinoatrial node – the organ’s natural pacemaker. As long as the impulse is transmitted normally, the heart beats at its regular pace, usually between 60 and 100 beats per minutes. Any changes to this normal heart rhythm can have serious consequences.
Arrhythmia refers to abnormal heart rhythms as result of any change in impulse sequences. This causes the heart to pump less effectively. Although some arrhythmias are so brief that the overall heart rate or rhythm isn’t greatly affected, those that last for an extended period of time may cause the heart to beat too slow, too fast or very erratically.
A heart beat that’s too slow is called bradycardia. This condition causes fatigue, dizziness and even fainting. Bradycardia is easily corrected by implanting an electronic pacemaker under the skin, which speeds up the heart rhythms as needed.
A fast heart rate is called tachycardia, which is broken down into two major categories. Ventricular tachycardia involves only the ventricles, while supraventricular tachycardia involves both the atria and the ventricles. How fast is too fast? A variety of conditions factor into this, but the largest variables are a person’s age and physical activity level.
Tachycardia is sometimes caused when the automatic firing rate of secondary pacemaker tissue becomes too fast. If this abnormality is faster than the sinus node, it can over ride the heart’s rhythm. Another type of abnormal conduction, called reentry, happens when impulses get caught in a merry-go-round sequence.
Rapid heart tempos can produce symptoms such as palpitations, rapid heart action, dizziness, lightheadedness and fainting. Abnormally rapid rhythms in the ventricles can be life-threatening. But the most serious cardiac rhythm disturbance, called ventricular fibrillation, occurs when the lower chambers quiver rather than beat. Because the heart can’t actually pump any blood under these conditions, collapse and sudden death is inevitable unless medical help is provided immediately.
If treated in time, ventricular tachycardia and ventricular fibrillation can be restored to normal rhythms with an electric shock. Rapid heart rhythms are often controllable by medication and by identifying (and sometimes destroying) the focus of the disturbances. Another effective method of correcting these life-threatening beat patterns is by using an electronic device called an implantable cardioverter defibrillator.
Who is at risk?
Several factors increase the risk of developing CAD. The more risk factors a person has, the greater chance that he or she will develop the disease. While some of these risk factors are somewhat controllable, others aren’t.
Risk factors beyond a person’s control include:
- Age. As a person ages, his or her risk for CAD increases. In men, this risk increases dramatically after at 45. In women, risk increases after 55.
- Family history of heart disease. A father or brother who has been diagnosed with heart disease before the age of 55 is a significant risk factor; as is a mother or sister who has been diagnosed before age 65.
Risk factors that a person can modify:
- High blood cholesterol
- High blood pressure
- Cigarette smoking
- Diabetes
- Overweight or obesity
- Lack of physical activity.
Diagnosis
No single test can diagnose CAD. Instead, a doctor will inquire about medical history, family medical history and risk factors; as well as perform several exams and tests. These procedures determine if you truly have CAD, the extent of the disease and rule out other possible causes of the symptoms.
Some of these tests include:
EKG or electrocardiogram. This measures heart rate and regularity.
Echocardiogram. This uses sound waves to create a moving picture of the heart itself. This procedure can identify areas of poor blood flow, areas that are not contracting normally and even spots areas of the heart that have been damaged due to poor blood flow.
Stress test. Doctors intentionally make the heart work harder and faster (usually by means of controlled exercise or certain medications) and observe how it reacts. Many problems show up more clearly when the heart is stressed rather than when it is relaxed.
X-ray. A chest X-ray takes a picture of the organs and other body systems inside the chest.
Cardiac catheterization. A thin, flexible tube is passed through an artery in the groin or arm to reach the coronary arteries. This allows doctors to examine the inside of the arteries for blockage.
Coronary angiography. Usually performed with cardiac catheterization, coronary angiography involves injecting a special die into the arteries. This die is detectible by X-ray, which allows doctors to observe the blood flow through the heart.
Nuclear heart scan. A trace amount of a radioactive substance is injected into the bloodstream, and then a special camera is placed in front of the chest which gives doctors a "moving picture" of the blood passing through the heart’s chambers and arteries. Though there are several types of heart scans, most run through two phases: the heart at its resting state and while it’s beating fast (stress test). By comparing the results of the two phases, doctors can better determine if the heart is functioning properly.
Prevention
Take action. The first step in preventing or delaying CAD begins by knowing which risk factors you have. Know your family’s health history; particularly note any CAD-related problems. If you or anyone in your family has CAD, make sure your doctor knows.
And don’t forget to minimize the risk factors that you can control. Eat healthy, get plenty of exercise, maintain a healthy body weight and develop a good relationship with your doctor.
Information provided by the National Heart, Lung and Blood Institute