The Frequency of Non-infectious Disorders
The frequency of non-infectious disorders is expanding at an alarming rate in the modern world. This could be related to the evolution of human lifestyle as technology improves, allowing for the emergence of lifestyle disorders. Cardiovascular disorders, which affect the heart and blood arteries, are the most common type of such disease. As a result, they are the leading cause of death worldwide. In 2015, 17.7 million fatalities were due to cardiovascular illnesses, accounting for 31% of all deaths worldwide (World Health Organization, 2017). This presentation will concentrate on coronary artery disease, providing a complete assessment of the condition's nature and management. Definition of Coronary Artery Disease and Related Epidemiology.
The Definition of Coronary Artery Disease
The coronary artery disease affects blood vessels that supply the heart muscles and other body parts leading to undesirable consequences. It comes about when substances such as deposits of cholesterol form a plaque on the wall of the blood vessel which obstructs the flow of blood to the myocardium. This eventually leads to atherosclerosis whereby plaque buildup causes the constriction of the lumen of the arteries thus blocking blood flow either partially or totally. If the buildup is extreme and the heart muscle is deprived of sufficient amounts of blood, the affected individual may have angina (Hanson, Fareed, Argenio, Agunwamba, & Hanson, 2013).
Coronary Artery Disease in Developing Countries
In developing countries, coronary artery disease tops the list of diseases that affect the cardiovascular system. It is also the top killer across all genders and ethnicities in the U.S. Upwards of 12 million Americans suffer from the disease with fatalities estimated to nearly 500,000 (Sanchis-Gomar et al., 2016). Its effect on the economy of the United States is also significant. The disease also has a negative effect on the American economy with billions spent on medications and health care services. Significant working hours are also lost in the process which affects the nation’s productivity. (Sanchis-Gomar et al., 2016).
Normal Physiology of the Cardiovascular System
The cardiovascular system in a human being is composed of a heart which is responsible for pumping blood through a complex, extensive, and closed system of blood vessels. The principal function of the circulation of blood throughout the body is to “deliver oxygen and nutrients to and remove carbon dioxide and wastes from metabolizing tissues” (Fuster, Walsh, & Harrington, 2011). This signifies its importance to the general functioning of the body. Materials necessary for cellular metabolism enter the body through a variety of routes. Oxygen, for example, enters through the respiratory system while water and nutrients enter the body through the digestive system. The cardiovascular system mediates the transportation of these substances to individual cells through the vast network of vessels across the body. Though blood vessels that are intimate with tissues, the system also mediates the movement of materials from cell to cell. Examples of materials transported this way are immune cells and hormones. Finally, the cardiovascular system transports materials that are released by the body such as carbon dioxide, heat, and metabolic wastes.
The Structure and Function of the Heart
The heart is made up mainly of a specialized muscle known as myocardium. It is divided into two halves by a septum with each half consisting of an atrium and a ventricle. The former receives blood returning to the heart while the latter pumps out blood into vessels that serve the rest of the body. Valves separate these sections. There are three types of blood vessels which are specialized in their function. Arteries, which are rich in elastic tissue and smooth muscle, carry blood away from the heart. The function of veins is quite the opposite since they carry blood back to the heart from various body parts. Capillaries, which are microscopic, are in contact with tissues and connect small arteries (arterioles) to small veins (venules). The cardiovascular system has some unique features that greatly influence its functioning. They include the following: a closed rather than open-ended system elastic nature; right and left ventricles that are in series with pulmonary and systemic vascular beds; passive rather than active filling of the heart; regulation of the circulation rate by vascular factors; while flow from the heart is intermittent, the flow to the heart is continuous (Anderson, 2012).
The Circulation Process
The circulation process illustrates the functioning of all components of the cardiovascular system in harmony with each other. Pulmonary circulation involves the interaction between the cardiovascular system and the lungs while systemic circulation involves the system’s interaction with the rest of the body. Reception of deoxygenated blood from other body systems is through the right atrium. What follows is the flowing of received blood to the neighboring ventricle from where it is pumped to the hub of the respiratory system- the lungs. The following process in the oxygenation of the blood in the lungs. The blood which is saturated with oxygen is then transported to the heart where it is received by the left chamber (Silverthorn, 2015). The oxygenated blood then has to find its way to the left ventricle. It is from this location that oxygenated blood is pumped to all body systems. The vessel tasked with this function is the aorta. It branches into smaller vessels and finally into capillary beds in various tissues in the body. The exchange of oxygen in the blood for carbon dioxide occurs at the tissue level. The deoxygenated blood is returned to the heart through small veins which join to form the vena cava which empties into the right atrium.
The Role of the Coronary Arteries
The coronary arteries, despite not being specifically mentioned in the physiology of the system, play a crucial role. The coronary arteries branch off from the aorta which serves the entire body with oxygenated blood through its network of vessels. They are tasked with serving the myocardium with blood. Any form of obstruction of these arteries, therefore, limits the amount of blood reaching the myocardium which can lead to disastrous consequences.
Pathophysiology
Chronic artery disease develops over a long period as chronic conditions do. As such, the development of the disease can start as early as adolescence. There is a variety of risk factors that accelerate the progression of the chronic process. Such factors include the following, “a family history of premature chronic artery disease cigarette smoking, diabetes mellitus, hypertension, hyperlipidemia, sedentary lifestyle, and obesity” (Deloukas et al., 2013).
Inflammation and the Development of Coronary Artery Disease
A modern and widely accepted theory of the disease’s development is the one involving inflammation. When the endothelium of the coronary artery encounters certain antigens, individual cells try to protect themselves by expressing adhesion molecules. The result of this is the sticking of leucocytes to the artery’s inner wall. These immune cells communicate with smooth muscle cells and endothelial cells of the artery through molecular mediators such as leukotrienes and prostanoids which induce an inflammatory response. This causes smooth muscle cells to move outward where they grow rapidly forming an extracellular matrix. Some components of this matrix such as oxidized phospholipids sustain the inflammatory response. By this stage, there is already a lesion in the wall of the coronary artery. Calcification and apoptosis characterize the progression of the lesion. Lipid-filled macrophages die and consequently lead to the deposition of tissue factor outside the endothelial cells. The extracellular lipid that accumulates forms the core of the plaque which features high concentrations of lipids (Libby and Theroux, 2005). Eventually, the lesion forms a fibrous cap. This contributes to the development of adverse acute symptoms. The plaque eventually loses integrity in the shoulder region and ruptures. This exposes the lipid core and dead cell material to blood which is in circulation leading to some devastating effects which include the adherence of platelets and the gradual narrowing of the lumen. (Hansson, 2005). Research over the recent past has identified vascular inflammation as influential in the initiation of atherosclerosis and potential instability of the plaque. As such, markers like increased levels of “high sensitivity C-reactive protein” indicate a high probability of inflammation of the endothelium in an individual (Hansson, 2005).
The Thickening of the Arterial Wall and the Progression of the Disease
The thickening of the arterial wall as a result of the development of the plaque leads to a substantial narrowing of the coronary artery lumen. This translates to less blood reaching the myocardium. Besides the necrotic material from cell debris, other materials also accumulate in the region in a bid to heal the endothelial injury. Such include cholesterol, lipoproteins, and fats. In addition to calcification of cell debris, another process that occurs during the progression of the lesion is the oxidation of LDLs, which aggregate in high concentrations at the site. This altered lipoprotein enhances the progression of the lesion by attracting leucocytes and macrophages. When the latter engulfs lipoproteins, they form foam cells which develop to a complex known as the fatty streak. This further contributes to the formation of the plaque. By the time the plaque develops a fibrous cap, it is already independent regarding blood supply since it has its network of vessels. As the plaque grows, the lumen of the coronary artery continues narrowing which may ultimately lead to obstruction of the flow of blood to the heart muscle resulting in a heart attack (Heusch et al., 2014).
Clinical Manifestations of Coronary Artery Disease
Coronary artery disease is associated with a variety of symptoms. The most common of the lot is angina. Its severity ranges from a mild chest pain to a severe attack in which pain spreads to other parts of the body such as neck and back. From a molecular perspective, the pain associated with angina is tracked to the interaction of nerve endings with factors such as protons and adenosine. The effect of this interaction is stimulatory in nature. The pain experienced during an attack is usually localized and feels like a squeezing or pressing motion (Davies, 2001). Physical or emotional stress is implicated for the pain, and it may disappear soon after stopping the activity causing stress. An important note, in this context, is that angina can be caused by non-cardiac causes such as pneumonia, asthma, and peptic ulcers. A substantial percentage of patients do not present with the typical symptoms associated with angina (Rimmerman, 2013).
When observed, angina can be categorized as either stable, accelerating, or unstable. It is described as stable if it is consistent in its frequency, intensity, and duration over a couple of weeks. In this case, the physician should identify activities that provoke the pain. Consequently, the doctor administers nitroglycerin to alleviate the symptoms. For accelerating angina, the pain is provoked more easily, episodes are longer and more severe. The transition of a patient to this form usually warrants acute medical attention due to the poor prognosis of the condition. Unstable angina is the most severe form with the pattern of discomfort being highly variable. It is associated with events such as the busting of the plaque. This is a medical emergency situation since what follows is the acute coronary syndrome (Davies, 2001).
An individual with chronic artery disease may also experience shortness of breath. This can be explained by the pathophysiology of the disorder. The formation of the plaque in the endothelium of the artery narrows its lumen thus limiting the amount of blood reaching the myocardium. This blood is oxygenated, and the heart muscle will need the oxygen to produce the energy needed for pumping blood throughout the entire body. If it is deprived of blood, it has no oxygen required for its metabolism and thus cannot meet the body’s need for blood as it normally does by pumping. An attempt by the individual’s cardiovascular system to meet the body’s physiological needs through exertion leads to extreme exhaustion.
The complete obstruction of the lumen of the coronary artery may cause a heart attack. The symptoms of a heart attack may mirror those of angina, but in this case, the pain is more severe and may even attack one while in a resting state. In most patients with unrecognized chronic artery disorder, an acute heart attack might be the first clinical presentation of the disease. This can be accompanied by electrical instability which may lead to fatal dysrhythmias. Therefore, identifying people who are highly likely to develop CAD before their first attack is necessary. This is a multifarious process that would involve the efforts of all involved parties. Important moves, in this case, include monitoring and modifying risk factors from early on in life, focusing on preventing the disease, and delaying the progression of the disease to its symptomatic stage (Rimmerman, 2013).
Diagnosis of Coronary Artery Disease
The first priority when diagnosing for chronic artery disease is thoroughly evaluating the medical history of the individual in question. This would involve the identification of risk factors that could predispose them to the disease. The history and location of any discomfort experienced in the past would also be important at this stage. It would be followed by a physical examination to determine the potential causes of chest pain in addition to an assessment of the state of arterial circulation in the body (Vestbo et al., 2013).
Since no single test can diagnose the chronic artery disease, a physician may have to recommend other tests to help determine the nature of the problem at hand. Diagnostic imaging techniques are essential in the diagnostic process. An electrocardiogram is necessary since it would enable the physician to detect any anomalies in the patient’s heartbeat and rhythm. It can show signs of a heart attack that happened in the past in addition to showing any signs of heart damage due to the disease. A chest radiography, on the other hand, can show coronary calcification which is a definite sign of the disease. Echocardiography is yet another imaging technique that has proved useful in the diagnosis of chronic artery disorder. The reflected sound waves can show parts of the myocardium with poor blood flow in addition to anomalies in the contraction of sections of the heart muscle. Another alternative is stress testing which involves the use of blood pressure monitoring and electrocardiography. The patient is subjected to aerobic exercise with his cardiac performance being monitored. The test can show anomalies in a patient’s blood pressure or the electrical activity of the heart. One’s performance is compared to what is perceived as normal for his/her peers.
Blood tests are also important in the diagnosis of the disease. Measurements that are crucial, in this case, include lipoproteins, triglycerides, fasting glucose levels, cholesterol, and the C-reactive protein (Rimmerman, 2013). In case other tests show a high likelihood of a patient having coronary artery disease, a confirmatory test can be recommended. The test, coronary angiography, involves the visualization of the interior of the coronary arteries using special x rays and dye.
Clinical Management of Coronary Artery Disease
The management of chronic artery disease aims at reducing the disease’s symptoms and preventing the progression of the disease. Various therapeutic options could effectively achieve the stated goals. The first option is the patient’s commitment to modifying their lifestyles to reduce the risk of the disease progressing. Restraining from the use of tobacco is a common recommendation due to the significant contribution of the substance to repeated cardiovascular events. A direct relation to the disease, in this case, is that tobacco accelerates the dysfunction of the endothelium. Increasing the amount of physical activity through daily exercise regimes would also help increase the patient’s functional capacity which is often associated with major lethal cardiac events. Weight control is also advisable since it has a favorable effect on most risk factors associated with cardiovascular events.
Pharmacologic therapy is also successful in the management of coronary artery disorder. Antianginal agents are necessary since chest pain is usually the first symptom of the disease in addition to signaling its progression. Beta-blockers and nitrates are some of the types of therapeutic agents used to counter the symptoms. Antiplatelet agents are also used by patients who have the disease. Most physicians recommend aspirin for this purpose.
The management of the associated risk factors is also as important as the other therapeutic options. In case of patients who also have hypertension, control of the latter is crucial. If blood pressure is controlled, then the consumption of oxygen by heart muscles will reduce thus favorably affecting angina. The control of hyperlipidemia is also key due to the role lipids play in plaque formation. This could be achieved through physical exercise or chemotherapy with agents such as niacin. The management of diabetes is also critical for patients with coronary artery disease. This should involve the aggressive control of blood glucose and hemoglobin levels.
The last option in the clinical management of the disease is surgery. There are two alternatives, in this case, Percutaneous Coronary Intervention (PCI) and Coronary Artery Bypass Grafting (CABG) (Rimmerman, 2013). The former is better at relieving angina than other alternatives. However, it does not in any way increase the patient’s chances of survival. The latter offers better survival chances than other options. It is, however, advisable for the patient to participate in the management of the problem rather than waiting for medications and surgery.
References
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