Research Essay Sample on Coronary Artery Disease
Coronary artery disease is one of the leading causes of death worldwide (Betts, J. Gordon, et al, 2017). Coronary artery disease occurs in the large coronary arteries on the surface of the heart when there is a buildup of plaque around the inside lining of the artery (NHLBI). The buildup of plaque in arteries prevents enough oxygenated blood from reaching the heart by causing the arteries to become partially or fully blocked. These blockages in the arteries limit the amount of blood, oxygen, and nutrients that reach parts of the body or cause blood clots leading to heart attacks and strokes (Atherosclerosis). Tissue damage and eventually death in the arms, legs, and other areas of the body can also occur due to coronary artery disease.
The first recorded diagnosis of coronary artery disease was in 1768 and the condition was called angina pectoris (Rothstein). The discovery of calcification of arteries in autopsies led to the discovery of the cause of angina pectoris. At first, angina pectoris was only diagnosed in cases related to any type of chest pain and eventually became diagnosed only in reference to heart disease. Researchers found that angina pectoris was often underdiagnosed in the 18th and 19th centuries, often due to misdiagnoses with other heart diseases like organic heart disease.
Coronary artery disease is caused by atherosclerosis, the hardening of arteries due to plaque buildup (Atherosclerosis). These plaques impact the endothelium, the lining between the intima and artery wall. Plaques can be caused by elevated levels of LDL cholesterol, toxins like cigarette smoke, chronically high blood pressure, and sugar.
There are four stages of coronary artery disease (Atherosclerosis). The first stage involves endothelial damage and immune response. When the endothelium is injured, cholesterol floods to the injured site and oxidizes causing an immune response. White blood cells (monocytes) travel and gather in the artery causing inflammation.
Stage two is the creation of fatty streaks (Atherosclerosis). Monocytes in the artery become macrophages that consume and surround cholesterol. When the macrophages consume cholesterol, they become foamy. After macrophages become foam cells, they die, causing the body to send more white blood cells, causing a repeating cycle that hurts the endothelium more and marks the beginning of plaque formation. These dead cells form a bulge under the endothelium that is called a fatty streak.
Stage three is the continuation of the cycle from stage two that causes an even bigger plaque and leads to the formation of a fibrous cap over the fatty streak to prevent the plaque from breaking off and into the bloodstream (Atherosclerosis). The fibrous cap gains calcium causing it to become harder. The artery expands outward to make up for the plaque, but the artery can only expand so far. The plaque will continue to grow eventually causing the artery to narrow and less room for blood flow.
This fibrous cap can last for many years until stage four: Plaque rupture (Atherosclerosis). Plaque ruptures occur when the fibrous cap breaks open and plaque encounters blood in the bloodstream causing a blood clot (thrombus), that blocks blood flow leading to a heart attack or stroke.
Coronary heart disease can take a long time to show symptoms (Atherosclerosis). First symptoms usually occur when there is a 70% blockage in an artery preventing the body from getting enough oxygen. This can cause chest pain (angina) while exercising and leg cramps when walking due to intermittent claudication. If the symptoms are not caught early and the condition is not managed heart attacks and strokes can occur.
While Coronary heart disease cannot be cured/reversed, lifestyle changes, medications, and in serious cases surgery can prevent further damage (Atherosclerosis). Lifestyle changes including a diet low in saturated and trans fats, cholesterol, sodium, and sugar can help prevent further damage to the arteries. Regular exercise helps to maintain a healthy weight and managing health conditions, especially diabetes, high blood pressure, and high LDL cholesterol levels can also help in the prevention and maintenance of Coronary artery disease.
Diets low in saturated fats are important because they can raise levels of total serum cholesterol, and too much sugar (especially added sugar) can lead to, “…elevated levels of glucose, insulin, and uric acid, impaired glucose tolerance, insulin and leptin resistance, non-alcoholic fatty liver disease, and altered platelet function” (DiNicolantonio, et al). Large amounts of cholesterol can lead to the buildup of fatty deposits in blood vessels (High Cholesterol). Trans fats increase LDL cholesterol and reduce high-density lipoprotein (HDL) cholesterol concentrations (Robert and Lewington). excessive sodium intake may worsen high blood pressure, or hypertension (Januzzi and Nasrien).
Regular exercise decreases the amount of oxygen necessary by improving the contractility of the heart, and electrical stability, increasing the width of the interior arteries, and preventing the continued development of atherosclerosis (Yadav, Y K).
Doctors may prescribe medications to control blood pressure, lower cholesterol, manage blood glucose levels, and prevent blood clots. Surgeries like coronary angioplasty, coronary artery bypass surgery, and carotid endarterectomies are performed in serious conditions. Angioplasties are used to open blocked coronary arteries and restore blood flow to the heart muscle without open-heart surgery (Angioplasty and Stent Placement). Coronary bypass surgery redirects blood around a section of a blocked or partially blocked artery in the heart (Coronary Bypass Surgery). Carotid endarterectomies involve opening the carotid artery and removing plaques clogging the artery.
While atherosclerosis was not originally thought to be a common cause of death, it is now understood that it is a commonly occurring disease, that has become a leading cause of death around the world. Fortunately, it is preventable and able to be managed. Lifestyle changes like regular exercise, maintaining a healthy weight, and reducing intake of sugar, sodium, saturated and trans fats, medication, and in extreme cases surgery can allow people to live long lives.
