EngradeWikisCardiology EMT 1825 › Coronary Arteries, Veins and Diseases

Coronary Arteries, Veins and Diseases

Coronary Arteries



(1)In order to ensure the heart has an adequate blood supply, the heart makes sure to provide itself with a fresh supply of oxygenated blood before supplying the rest of the body
(2) Freshly oxygenated blood is supplied mainly by the branches of two vessels--the right and left coronary arteries
(3) The right and left coronary arteries are the very first branches off the proximal aorta. The openings to these vessels lie just beyond the cusps of the aortic SL valve
(4) The three major coronary arteries include the left anterior descending artery, left circumflex artery, and the right coronary artery
(5) The right coronary artery originates from the right side of the aorta. It travels along the groove between the right atrium and right ventricle.
(6) A branch of the RCA supplies the:
a. right atrium
b. right ventricle
c. inferior surface of the left ventricle in about 85% of individuals
d. posterior surface of the left ventricle
e. Sinoatrial node
f. Atrioventricular node
(7) The left coronary artery originates from the left sid eof the aorta
a. the first segment of the LCA is called the left main coronary artery. It is about the width of a soda straw and less than an inch long.
b. The left main coronary artery supplies oxygenated blood to its two primary branches: the left anterior descending (also called the anterior interventricular) artery and the left circumflex artery. These vessels are slightly smaller than the left main coronary artery.
(8) The LAD can be seen on the outer (epicardial) surface on the front of the hart. It travels along the groove that lies between the right and left ventricles toward the heart's apex. The Lad supplies blood to:
a. anterior surface of left ventricle
b. part of lateral surface of left ventricle
c. most of the interventricular septum
(9). The left circumflex coronary artery circles around the left side of the heart. It is embedded in the epicardium on the back of the heart. The LCX supplies blood to the:
A. left atrium
b. lateral surface of the left ventricle
c. inferior surface of the left ventricle
d. posterior surface of the left ventricle
e. SA node
f. AV node

(10) Blood flow to the tissues of the heart are significantly reduced due to the heart's blood vessels being compressed when the heart contracts. The coronary arteries fill when the ventricles are relaxed (diastole).
(11). The main coronary arteries lie on the outer (epicardial) surface of the heart
(12) Coronary arteries that run on the surface of the heart are called epicardial coronary arteries. They branch into progressively smaller vessels, eventually becoming arterioles, and then capillaries. Thus, the epicardium has a rich blood supply to draw from
(13) Branches of the main coronary arteries penetrate into the heart's muscle mass and supply the subendocardium with blood. The diameter of these "feeder branches" is much narrower. The tissue supplied by these "feeder branches" gets enough blood and oxygen to survive, but they do not have much extra.
(14) A person is said to have coronary artery disease if there is more than 50 percent diameter narrowing (stenosis) in one or more of these vessels.
(15) Blockage of the left main coronary artery has been referred to as the "widow maker" because of its association with sudden death.
(16) In about 85% of people, the right coronary artery froms the posterior descending artery. In the remaining 15% of people, the left circumflex artery forms the posterior descending artery.The coronary artery that forms the posterior descending artery is considered the "dominant" coronary artery. If a branch of the right coronary artery becomes the posterior descending artery, the coronary artery arrangement is described as a right dominant system. If the left circumflex coronary artery branches and ends at the posterior descending artery, the coronary artery arrangement is described as a left dominant system. If damage to the posterior wall of the left ventricle is suspected, a cardiac catheterization usuallyis necessary to determine which coronary artery is involved.

Coronary veins

(1) the coronary(cardiac)veins travel alongside the arteries
(2) blood that has passed through the myocardial capillaries is drained by branches of the cardiac veins that join the coronary sinus
(3) The coronary sinus is the largest vein that drains the heart. It lies in the groove (sulcus) that separates the atria from the ventricles
(4) The coronary sinus receives blood from the great, middle, and small cardiac veins; a vein of the left atrium; and the posterior vein of the left ventricle
(5) The coronary sinus drains into the right atrium
(6) The anterior cardiac veins do not join the coronary sinus but empty directly into the right atrium

Acute Coronary Syndromes

(1)Acute Coronary syndromes are conditions caused by a similar sequence of pathologic events--a temporary or permanent blockage of a coronary artery
(2) This sequence of events results in conditions ranging from myocardial ischemia or injury to death (necrosis) of heart muscle
(3) The usual cause of an ACS is the rupture of an atherosclerotic plaque
(4) Arteriosclerosis is a chronic disease of the arterial system characterized by abnormal thickening and hardening of the vessel walls
(5) Atherosclerosis is a form of arteriosclerosis in which the thickening and hardening of the vessel walls are caused by a buildup of fat-like deposits (plaque) in the inner lining of large and middle-sized muscular arteries
(6) As the fatty deposits build up, the opening of the artery slowly narrows and blood flow to the muscle decreases

Atherosclerosis

(1) any artery in the body can develop atherosclerosis
(2) If the coronary arteries are involved (coronary artery diseae) and blood flow to the heart is decreased, angina pectoris or more serious signs and symptoms may result
(3) If the arteries in the leg are involved (peripheral vascular disease), leg pain (claudication) may result
(4) If the arteries supplying the brain are involved (carotid artery disease) a stroke or transient ischemic attack (TIA) may result

ANGINA PECTORIS

(1) Angina pectoris is chest discomfort that occurs when the heart muscle does not receive enough oxygen (myocardial ischemia)
(2) Angina is not a diseae. It is a symptom of myocardial ischemia
(3) Angina most often occurs in patients with coronary artery disease involving at least one coronary artery. However, it can be present in patients with normal coronary arteries
(4) Angina also occurs in persons with uncontrolled high blood pressure or valvular heart disease

COMMON TERMS USED TO DESCRIBE ANGINA

(1) Angina means squeezing or tightening, not pain. The discomfort associated with angina occurs because of the stimulation of nerve endings by lactic acid and carbon dioxide that builds up in ischemic tissue
(2) Common words used by patients experiencing angina to describe the sensation they are feeling include the following:
(a) heaviness
(b) pressing
(c) suffocating
(d) squeezing
(e) strangling
(f) constricting
(g) bursting
(h) burning
(i) grip-like
(j) A band across my chest
(k) a weight in the center of my chest
(l) a vise tightening around my chest
(3) Some patients have difficulty describing their discomfort

{h2}Common Sites for Anguinal Discomfort (1) chest discomfort associate with myocardial ischemia usually begins in the central or left chest and then readiates to the arm (especially the little finger) (ulnar) side of the left arm) wrist, jaw, epigastrium, left shoulder, or between the shoulder blades.
(2) Ischemic chest discomfort is usually not sharp, worsened by deep inspiration, affected by moving muscles in the area where the discomfort is localized, or positional in nature

Myocardial Ischemia

(1) Ischemia can occur because of increased myocardial oxygen demand (demand ischemia), reduced myocardial oxygen supply (supply ischemia) or both
(2) If the cause of the ischemia is not reversed and blood flow restored to the affected area of the heart muscle, ischemia may lead to cellular injury and, ultimatley, infarction
(3) Ischemia can quickly resolve by reducing the heart's oxygen demand (by resting or slowing the heart rate with medications such as beta-blockers) or increasing blood flow by dilating the coronary arteries with drugs such as nitroglycerin (NTG)
(4) Early assessment, including obtaining a focused medical history, and emergency are are essential to prevent worsening ischemia

Myocardial Injury

(1) Ischemia prolonged more than just a few minutes results in myocardial injury
(2) Myocardial injury refers to myocardial tissue that has been cut off from or experienced a severe reduction in its blood and oxygen supply
(3) Injured myocardial cells are still alive but will die (infarct) if the ischemia is not quickly corrected
(4) If the blocked vessel can be quickly opened, restoring blood flow and oxygen to the injured area, no tissue death occurs
(5) Methods to restore blood flow may include giving clot-busting drugs (fibrinolytics), coronary angioplasty, or a coronary artery bypass graft (CABG)

Myocardial Infarction

(1) A myocardial infarction (MI) occurs when blood flow to the heart muscle stops or is suddenly decreased long enough to cause cell death
(2) INfarcted cells are without function and cannot respond to an electrical stimulus or provide any mechanical function

NOTE: The term myocardial infarction relates to dead heart muscle tissue. In a practical sense, the term myocardial infarction is applied to the process that results in the death of myocardial tissue.
    Close