Progressive reduction of blood supply to the heart muscle due to narrowing or blocking of a coronary artery (see atherosclerosis). Short-term oxygen deprivation can cause angina pectoris. Long-term, severe oxygen depletion causes a heart attack. Coronary bypass or angioplasty is needed if medication and diet do not control the disease.
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Surgical treatment for coronary heart disease to relieve angina pectoris and prevent heart attacks. It became widely used in the 1960s. One or more blood vessels—usually an artery in the chest or a vein from the leg—are transplanted to create new paths for blood to flow from the aorta to the heart muscle, bypassing obstructed sections of the coronary arteries.
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Vessel that carries blood from the heart to other parts of the body (see cardiovascular system). Arterial blood carries oxygen and nourishment to tissues; the one exception is the pulmonary artery, which conveys oxygen-depleted blood from the heart to the lungs for oxygenation and removal of excess carbon dioxide. Arteries are muscular, elastic tubes that transport blood under the pressure of the heart's pumping action, which can be felt as the pulse. Large arteries branch off from the aorta and give rise to smaller arteries, down to the threadlike arterioles, which branch into capillaries. An artery wall's inner layer (tunica intima) consists of an endothelial (cellular) lining, a fine connective tissue network, and a layer of elastic fibres. The middle layer (tunica media) is mostly smooth muscle cells. The outer layer (tunica externa) contains supportive collagen fibres. Seealso capillary; vein.
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The circulatory system is extremely important for sustaining life. Its proper functioning is responsible for the delivery of oxygen and nutrients to all cells, as well as the removal of carbon dioxide and waste products, maintenance of optimum pH, and the mobility of the elements, proteins and cells of the immune system. In developed countries, the two leading causes of death, myocardial infarction and stroke each may directly result from an arterial system that has been slowly and progressively compromised by years of deterioration. (See atherosclerosis).
The outermost layer is known as the tunica externa formerly known as "tunica adventitia" and is composed of connective tissue. Inside this layer is the tunica media, or media, which is made up of smooth muscle cells and elastic tissue. The innermost layer, which is in direct contact with the flow of blood is the tunica intima, commonly called the intima. This layer is made up of mainly endothelial cells. The hollow internal cavity in which the blood flows is called the lumen.
The pulse pressure, i.e. Systolic vs. Diastolic difference, is determined primarily by the amount of blood ejected by each heart beat, stroke volume, versus the volume and elasticity of the major arteries.
Over time, elevated arterial blood sugar (see Diabetes Mellitus), lipoprotein cholesterol, and pressure, smoking, and other factors are all involved in damaging both the endothelium and walls of the arteries, resulting in atherosclerosis or Diabetes Mellitus.
In medieval times, it was recognized that arteries carried a fluid, called "spiritual blood" or "vital spirits", considered to be different from the contents of the veins. This theory went back to Galen. In the late medieval period, the trachea, and ligaments were also called "arteries".
William Harvey described and popularized the modern concept of the circulatory system and the roles of arteries and veins in the 17th century.
Alexis Carrel at the beginning of 20th century first described the technique for vascular suturing and anastomosis and successfully performed many organ transplantations in animals; he thus actually opened the way to modern vascular surgery that was before limited to vessels permanent ligatation.