Front of the Class: Coronary Artery Disease

I. Introduction

Coronary Artery Disease (CAD) is “a condition in which plaque (plak) builds up inside the coronary arteries. These arteries supply your heart muscle with oxygen-rich blood” (What is Coronary Artery Disease, 2007). CAD is the most common type of heart disease and is the leading cause of death in the United States for both women and men. It is also one of the leading causes of serious disability.

The main cause of the disease is the plaque build in the arteries. The plaque is made up of cholesterol, fat, calcium and other substances in the blood. When the blood builds up in the arteries it is called atherosclerosis. The plaque then narrows the arteries and reduces the blood flow to the heart muscle. The plaque build up may also form clots in the arteries which may totally or partially block the blood flow in the. The following diagram illustrates the difference between normal artery and artery with plaque build up (What is Coronary Artery Disease, 2007):

II. Pathophysiology of the Disease

When the coronary artery is blocked partially or completely the blood cannot flow to the heart muscle. This condition is called cardiac ischemia. This condition may lead to heart attack, arrhythmia and other complications. The most common signs of cardiac ischemia are chest pains, neck or jaw pain, arm pain, clammy skin, shortness of breath and nausea and vomiting. Others, especially those suffering from diabetes may experience no symptoms.

Cardiac ischemia is diagnosed based on the person’s medical history, physical examination, electrocardiogram, stress test and coronary angiogram. Treatment for this condition is aimed at improving the flow of blood into the heart muscle. Treatment may be in form of medication such as aspirin, nitrates and beta blocker. Angioplasty and coronary artery bypass surgery are other forms of treatment. Doctors may also recommend exercise to increase the flow of blood into the heart muscle once the person’s condition is normalized (Cardiac ischemia, 2006).

III. Complications

When the arteries are narrowed or blocked, the oxygen rich blood cannot reach the heart muscle which may then cause angina, heart attack and other complications.

Angina is pain or discomfort in the chest which occurs when there is not enough oxygen-rich blood in the heart muscle. The pain is similar to squeezing or pressure in the chest. Pain in the shoulder, jaw, neck, arm or back may also occur (What is Coronary Artery Disease, 2007).

Heart attack or Myocardial infarction occurs when the plaque blocks the blood flow in the heart, resulting in lack of oxygen which may lead to death. Some heart attacks are slow, with pain and discomfort although there are also the sudden and intense attacks. The common symptoms of heart attack are chest discomfort, discomfort in other areas of upper body, shortness of breath, and other signs, such as cold sweat, lightheadedness and nausea (Heart Attack, n.d.).

Other complications of CAD include heart failure, arrhythmias and mitral valve prolapse.

Heart failure is when the heart can no longer pump enough blood into the body. This is commonly caused by heart attack scars which changes the shape of the heart and at the same time impairs the function of the heart muscle. The size and location of the scars are the most significant factors of heart failure (Complications of CAD, 2007).

The normal heart beats at a rate of sixty to one hundred beats in a minute. The scar tissues, caused by heart attack may also slow the speed and pace of the heartbeat. This is called arrhythmia. There are two types of arrhythmia: bradycardia, the slow heartbeat, and tachycardia, the rapid heart beat. The most serious type of arrhythmia is the ventricular tachycardia which occurs when the ventricles beat so fast that it can no longer pump blood adequately (Complications of CAD, 2007).

Mitral valve prolapse is when the valve between the left atrium and ventricle fails to properly close since it bulges out. Again heart attack scar tissues may cause this condition. When the valve cannot close properly it cannot keep the blood flowing properly in the chambers of the heart. The most common symptoms of mitral valve prolapse are shortness of breath, dizziness, chest pain and skipping heartbeat. However there are those who do not experience any symptoms (Complications of CAD, 2007).

IV. Risk Factors

The American Heart Association identified several risk factors of Coronary Artery Disease. Some of the risk factors can be controlled and treated although there are some that are permanent conditions. The more risk the person has, the more likely he will eventually develop coronary heart disease. Moreover, the greater his level of each risk factor, the higher is his risk.

According to American Heart Association, the major risk factors that cannot be changed are increasing age, gender, hereditary and race. Age is a major factor since over 80% of those who died of the disease are age 65 or older. Men have also been found to be of greater risk than the women. The death rate of the men from the disease is greater than the women. It has also been found that children of parents with heart disease are more likely to have it later on in life. The disease is also higher on African Americans, Mexican Americans, American Indians, native Hawaiians and Asian Americans (Risk Factors, 2008).

The major risk factors that can be controlled, modified or changed, according to the American Heart Association are: tobacco smoke, high blood cholesterol, high blood pressure, physical inactivity, obesity and overweight and diabetes mellitus. These risk factors can be controlled or treated by changing one’s lifestyle or by taking the right medicine.

Smoking is one of the major risk factors since it has been proven that smokers have twice to four times the risk of developing the disease than non smokers. It was also found that it is a great risk factor for sudden cardiac deaths of those with CAD (Risk Factor, 2008).

High blood cholesterol is equal to higher risk or coronary heart disease. Other risks coupled with high blood cholesterol increases one’s risk. High blood pressure, on the other hand, makes the person’s heart to have additional work load which then may cause the heart to become stiff and to thicken. This then increases his chance of having heart attack, stroke, heart failure and other conditions (Risk Factors, 2008).

Exercise or moderate to vigorous physical activity is important in the prevention of heart and blood vessel diseases. At the same time, it controls the other risk factors, such as blood cholesterol, obesity and diabetes. Thus, physical inactivity is one of the major risk factors of CAD. Diabetes on the other hand increases one’s chance of developing cardiovascular diseases. Even when the person’s glucose levels are under control, the disease increases his risk or stroke and heart disease (Risk Factors, 2008).

Obesity or overweight is another major factor since excess weight increases the heart’s work. Moreover, it also affects the blood pressure, blood cholesterol, triglyceride levels, lowers the HDL cholesterol level and may even develop diabetes and stroke. On the other hand, in women, it has been found that physical inactivity is a greater factor than obesity since the obesity markers do not correlate with the angiographic CAD or its adverse events while lower fitness scores are associated with CHD risk factors and angiographic CAD (Rubenfire, 2004)

Other risk factors identified by the American Heart Association include individual response to stress and drinking too much alcohol (Risk Factors, 2008).

V. Diagnosis and Testing

The initial screening for CAD usually involves stress tests or stressing the heart under controlled conditions. The stress tests detect the presence of blockages in the arteries in the range of 50% reduction in diameter of one of the major arteries (Coronary Artery, n.d.). There are two types of stress tests: the exercise cardiac stress test and the physiologic stress test. The exercise cardiac stress test is (ECST) is the more commonly used test for CAD. For ECST the patient is asked to exercise on the treadmill while his electrocardiogram (EKG), heart rate, heart rhythm and blood pressure are monitored. The changes in the EKG, heart rate and blood pressure may indicate the presence of blockage in the artery.

If the doctor deems that additional test is necessary for an accurate diagnosis, he may then order for additional tests, the radionucleide stress test and the ultrasound of the heart, the stress echocardiography. The radionucleide stress test involves isotope injection into the patient’s vein, which makes the heart visible for nuclear imaging. If there is a blockage, it will appear as cold spot on the imaging scan. The stress echocardiography is a supplement of the ECST. Here, the images of the heart are produced using sound waves. If there is blockage, reduced contractions of the heart will be seen. Both the tests are done under controlled exercise (Coronary Artery, n.d.).

The physiologic stress test is the same in every aspect with the ECSET except it uses medications to stimulate the heart and mimic the effects of exercise. This is done on patients who cannot do the treadmill exercise (Coronary Artery, n.d.).

Aside from the tests, there are other methods for CAD diagnosis and these are: chest pain radiographs, fluoroscopy, electron beam computed tomography (EBCT), spiral computed tomography (SCT), multislice spiral CT (MSCT), magnetic resonance imaging (MRI), angiography and intravascular ultrasound (What are the Methods, n.d).

Plain chest radiographs is a chest film which detects coronary calcification. It is inexpensive although it is low sensitive and is only 42% accurate compared with the fluoroscopy. Fluoroscopy is capable of detecting moderate to large calcifications but not very sensitive in detecting low calcific deposits. It is only 52% accurate compared with the electron beam computed tomography (EBCT).

The Electron Beam Computed Tomography (EBCT) is highly sensitive and a non invasive way of detecting coronary calcifications. However it highly expensive and its parameters are not flexible for image quality, such as what is needed for obese patients and those with small calcific deposits. The Spiral Computed Tomography (CT) is better than fluoroscopy but has its own limitations such as slow image acquisition resulting in motion artifacts, breathing mis-registration and volume averaging. It also cannot quantify amount of plaque. The Multislice Spiral Computed Tomography (MSCT) has an increased rotation times which increased the scan speed (What are the Methods, n.d).

The Magnetic Resonance Imaging (MRI) uses magnetic fields, instead of the usual x-ray. It is not very sensitive in detecting coronary artery calcification. However the cardiovascular magnetic resonance (CMR) can highlight interstitial abnormalities and can detect small infractions. The CMR can even detect a gram or less of tissue and is considered a very reliable technique in detecting infarction (Imaging of Coronary Artery Disease, 2004).

Angiography is an invasive method of diagnosing CAD. A catheter is inserted through the femoral artery into the coronary artery to see calcification. The Intravascular Ultrasound is a very effective method in detecting CAD. It can determine, even in the early stage of the disease, the atherosclerotic wall changes, calcifications and stenosis (What are the Methods, n.d).

VI. Treatment and Rehabilitation

Once the CAD has been diagnosed, there are several treatment and rehabilitation strategies available for the patient depending on the stage of the disease. Lifestyle change is important, such as quitting smoke, eating healthy foods, and regular exercise.

Medication is also a common recommendation and this includes cholesterol medications which lowers the LDD and reverse the buildup of plaque in the arteries thereby normalizing the flow of oxygen rich blood in the heart. Aspirin, a blood thinner, is another medication. It reduces the tendency of the blood to clot. Beta blockers are drugs which slows the heart rate and decreases the blood pressure thus decreases the demand for oxygen. Nitroglycerin is a drug which opens up the coronary arteries and reduces the heart’s demand for oxygen. Angiotensin-converting enzyme (ACE) inhibitors are drugs which decreases blood pressure. Calcium channel blockers are drugs which relax the muscles surrounding the coronary arteries and increase the blood flow to the heart (Coronary Artery Disease, 2006).

Other treatment or procedures to improve or restore the blood flow in the heart are more aggressive ones. These are: Angioplasty and stent placement (percutaneous coronary revascularization), Coronary artery bypass surgery, Coronary brachytherapy and Laser revascularization (Coronary Artery Disease, 2006).

Works Cited

Cardiac ischemia. 2006. Mayo Clinic.