The cardiovascular system consists of blood, the heart, and the circulatory system, which includes veins, arteries, and capillaries. The function of these organs is to transport oxygen from the lungs to cells throughout the body. Each organ system in the body is essential in providing homeostasis in the human body. However, the actions of the cardiovascular system are critical to human life. Many physicians, scientists, and other professionals dedicate their life to the understanding of the cardiovascular system and its diseases so that people can live longer and more productive lives. This paper will discuss the general anatomy of the cardiovascular system, general conditions that affect these organs, tests to diagnose these conditions, and some treatments for common cardiovascular diseases.
Each part of the cardiovascular system is designed to transport oxygen from the lungs to the cells of the body. The heart is the engine of the cardiovascular system. Its role is to take deoxygenated blood from the body, pump it to the lungs so it can get oxygen, and then take the newly oxygenated blood to the rest of the body. To accomplish this feat, the heart has four chambers: the left atrium, right atrium, left, ventricle, and right ventricle. The heart also has four valves to prevent the backflow of blood. These valves are called the tricuspid, pulmonic, mitral, and the aortic. It is the contraction of these chambers of the heart that cause the blood to move forward. Specialized cells in the heart, called cardiac myocytes, are muscle cells that will contract and decrease the volume of the chamber. This action will force the blood to move forward. Attached to the heart are blood vessels, which act as transporters of the blood. There are three categories of blood vessels: arteries, veins, and capillaries. The role of arteries is to carry oxygenated blood away from the heart to the rest of the body. These vessels are elastic and usually lined with some muscle to help withstand the force that is exerted on these vessels by the blood leaving the heart at a high velocity. After arteries are capillaries; these vessels are fragile (one cell in diameter) and allow oxygen in the blood to leave the vessel and travel into the body’s cells. In return, carbon dioxide, a waste product of cellular respiration, will osmose into the red blood cells. After leaving the capillaries, the cells will enter the veins. These vessels are thinner than arteries and will take the blood back to the heart. With regards to the heart, some major vessels need to be discussed. The vena cava is the main vein that brings blood back to the heart, the aorta is the main artery that brings oxygenated blood to the body, the pulmonary artery and vein bring blood to and from the lungs, and the coronary arteries supply oxygen to the muscles to the heart. The last major component of the cardiovascular system is blood. Three substances make up blood: the red blood cells that transport oxygen and carbon dioxide to and from the cells in the body, plasma that contains clotting factors of blood, and platelets that are used to clot blood.
Cardiovascular disease affects a significant portion of the general population, mostly to adults over the age of sixty. It is estimated that seventeen million deaths worldwide occur from cardiovascular disease annually (Laslett et al., 2012). The term cardiovascular disease is used to cover four major diseases: cerebrovascular disease, coronary heart disease, peripheral artery disease, and aortic atherosclerosis and aortic aneurysms. This section will describe the basic pathology of these diseases.
Cerebrovascular disease covers stroke and transient ischemic attacks (TIA). Starving the brain tissue of oxygen can result in death. Obstruction can occur one of two ways: first, a clot occludes a vessel in the brain, or second, a bleed occurs, and the brain tissue cannot get oxygen. Physicians will classify this event a stroke if the blockage is for longer than twenty-four hours and there are permeant changes to the brain. A TIA will be diagnosed if the blockage is less than twenty-four hours and no permeant changes occur. Patients who suffer from a stroke or TIA will have different presentations depending on where the blockage is in the cerebral vascular. Many people will present with a focal neurological deficit such as weakness or decreased sensation in an extremity. Diagnosis consists of a CT scan, which can look at the brain. Physicians can tell from a CT scan if there is brain tissue that is being deprived of oxygen. They can also tell if there is an active bleed in the brain. Treatment for cerebrovascular accidents is to determine if a blockage or a bleed are causing the symptoms. If it is a bleed causing the neurological deficient, then a neurosurgeon has to operate to stop the bleed. If there is a blockage, then doctors can use medications to dissolve the clot and restore blood flow to the brain.
Coronary heart disease (CHD) is the most common form of the cardiovascular disease making up fifty percent of all cases (Lloyd-Jones et al., 1999). The coronary arteries supply the cardiac muscle with oxygen so they can pump blood to the rest of the body. Similar to a stroke, a clot can form in a coronary artery and deprive the cardiac muscle of oxygen, essential killing it. This process is called a myocardial infarction, otherwise known as a heart attack. Besides a clot forming in a coronary artery, there is another way to occlude a blood vessel. Cholesterol is a molecule that is used for the cell membrane, however, when the body has too much cholesterol in the body, it cannot absorb the molecule. Eventually, if cholesterol is not absorbed into the body, it can deposit into the blood vessels forming a raised plaque. This phenomenon is called atherosclerosis. If this process continues unopposed for years then the diameter of the coronary artery can diminish, restricting blood flow to the cardiac tissue. When atherosclerosis affects the coronary arteries, then the patient can have angina. When someone tries to exert themselves, the heart needs more oxygen to pump faster. Patients with angina experience chest pain on exertion because the blood supply cannot keep up with the demand and the muscle tissue with become ischemic, but it will not die. The patient will feel normal when not exerting themselves. To diagnose angina or a myocardial infarction. First, an electrocardiogram (EKG) can detect any abnormalities in the conduction of the heart through leads attached to the patient. If there are any abnormalities, then a physician can diagnose the condition. Physicians can also use an echocardiogram to diagnose any cardiac abnormalities in the patient. Using ultrasound waves, a technician can determine if a heart chamber is enlarged and not pumping correctly, or if there are any abnormalities with the wall of the heart or a valve. If this occurs, then the patient can have a murmur, which is an abnormal heart sound determined by auscultation. This sound occurs by blood traveling backward in the heart or traveling through a defect in the wall of the heart. Treatment coronary artery disease can involve medications to prevent plaques from forming, or a procedure called an angiogram, where a specialist can insert a wire from the leg into the coronary arteries and manually stretch the arteries to allow more blood to flow to the cardiac tissue.
Peripheral arterial disease is similar in its pathology to coronary artery disease. Instead of plaques forming in the coronary arteries, they form in the peripheral arteries. Patients will have pain in their legs when walking instead of chest pain. To diagnose peripheral artery disease, an ultrasound is used to see the pulses in the leg. Treatment an angiogram, where the affected arteries are manually opened up to allow blood to flow again.
Aortic dissection is the last of the four causes of cardiovascular disease. The aorta is the main outflow tract of oxygenated blood coming from the heart. This blood is ejected with much force to reach the distal areas of the body to perfuse tissues. The aorta is made up of some elastic fibers to help absorb the force. However, atherosclerotic plaques and tobacco use can stiffen the aorta. A stiff aorta cannot absorb the force of blood flow as well, and the inner lining can tear, creating a false tract. This tearing is called a dissection, and blood can flow into this false tract and not reenter the circulation. This disease can be diagnosed with a CT scan where the false tract can be visualized. Depending on where the dissection is in the aorta, the patient would need emergent surgery to repair the tear. If the tear is farther away from the heart, then medications to lower blood pressure can be used to decrease the amount of blood that enters the false tract.
The cardiovascular system is critical in delivering oxygenated blood to the tissue for cellular respiration. The diseases that affect the cardiovascular system are relatively common, and there are multiples ways that this organ system can be altered. It is important to understand the function of the cardiovascular system, the diseases that affect these organs, some of the imaging modalities to diagnose these conditions and their treatment so people can know what to do if they express similar symptoms.
References
Laslett, L.J., et al. (2012) The worldwide environment of cardiovascular disease: prevalence, diagnosis, therapy, and policy issues: a report from the American College of Cardiology. Journal of the American College of Cardiology. 60(25), S1-S49. Retrieved from http://content.onlinejacc.org/article.aspx?articleid=1485688
Lloyd-Jones, D.M., et al. (1999) Lifetime risk of developing coronary heart disease.
Lancet. 353(9147), 89-92. Retrieved from http://www.thelancet.com/pdfs/journals/lancet/PIIS0140673698102799.pdf
