Coronary Artery Disease (CAD) PDF

CORONARY ARTERY DISEASE (CAD) CORONARY ARTERY DISEASE (CAD) the heart disease that caused by inadequate blood supply to cardiac muscle due to occlusion of coronary artery, also called coronary heart disease. Coronary Occlusion means the partial or complete obstruction of coronary ar...

CORONARY ARTERY DISEASE (CAD) CORONARY ARTERY DISEASE (CAD) the heart disease that caused by inadequate blood supply to cardiac muscle due to occlusion of coronary artery, also called coronary heart disease. Coronary Occlusion means the partial or complete obstruction of coronary artery. The occlusion occurs because of atherosclerosis, a condition associated with deposition of cholesterol on the walls of the artery. In due course, this part of the arterial wall becomes fibrotic & it is called atherosclerotic plague. The plague is made up of cholesterol, calcium &other substances from blood. Because of the atherosclerotic plague the lumen of the coronary artery becomes narrow. In severe conditions, the artery is completely occluded. Smaller blood vessels are occluded by the thrombus or part of atherosclerotic plague detached from coronary artery. This thrombus or part of the plague is called embolus. Myocardial Ischemia is the reaction of a part of myocardium in response to hypoxia. Hypoxia develops when blood flow to a part of myocardium decreases severely due to occlusion of a coronary artery. When the ischemia is mild due to obstruction of smaller blood vessel, the blood flow can be restored by rapid development of coronary collateral arteries. Necrosis refers to death of cells or tissues by injury or disease in a localized area. When coronary occlusion is severe involving larger blood vessels, the severe ischemia leads to necrosis of myocardium. Necrosis is irreversible. Myocardial Infarction – Heart Attack Myocardial infarction is the necrosis of myocardium caused by insufficient blood flow due to embolus, thrombus or vascular spasm. It is also called heart attack, Common symptoms of myocardial infarction are: 1. Cardiac pain 2. Nausea 3. Vomiting 4. Palpitations 5. Difficulty in breathing 6. Extreme weakness 7. Sweating 8. Anxiety. Cardiac Pain – Angina Pectoris Cardiac pain is the chest pain that is caused by myocardial ischemia. It is also called angina pectoris. It is the common manifestation of coronary artery disease. The pain starts beneath the sternum and radiates to the surface of left arm and left shoulder. The cardiac pain is called referred pain since it is felt over the body away from the heart. It is because, heart and left arm develop from the same dermatomal segment in embryo. CEREBRAL CIRCULATION Brain tissues need adequate blood supply continuously. Stoppage of blood flow for 5 seconds leads to unconsciousness, and for 5 minutes leads to irreparable damage to the brain cells. HEMORRHAGE Hemorrhage is the excess loss of blood due to the rupture of blood vessels. TYPES AND CAUSES OF HEMORRHAGE: Hemorrhage occurs due to various reasons. Based on the cause, hemorrhage is classified into five categories: 1. Accidental hemorrhage 2. Capillary hemorrhage 3. Internal hemorrhage 4. Postpartum hemorrhage 5. Hemorrhage due to premature detachment of placenta. EFFECTS OF HEMORRHAGE Many effects are observed during and after hemorrhage. The effects are different in acute hemorrhage and chronic hemorrhage. Acute Hemorrhage Acute hemorrhage is the sudden loss of large quantity of blood. It occurs in conditions like accidents. Decreased blood volume in acute hemorrhage causes hypovolemic shock. Chronic Hemorrhage Chronic hemorrhage is the loss of blood either by internal or by external bleeding over a long period of time. Internal bleeding occurs in conditions like ulcer. External bleeding occurs in conditions like hemophilia and excess vaginal bleeding (menorrhagia). Chronic hemorrhage produces different types of effects such as anemia. produced by any disorder. Circulatory shock refers to the shock developed by inadequate blood flow throughout the body. It is a lifethreatening condition and if the affected person is not treated immediately it may result in death. MANIFESTATIONS OF SHOCK The characteristic feature of all types of circulatory shock is the insufficient blood flow to the tissues particularly the brain. The blood flow decreases due to the reduction in cardiac output. Following are the manifestations of circulatory shock: 1. When cardiac output reduces, the arterial blood pressure drops down 2. Low blood pressure produces reflex tachycardia and reflex vasoconstriction 3. The pulse also becomes feeble 4. The velocity of the blood flow decreases resulting in stagnant hypoxia 5. Skin becomes pale and cold 6. Cyanosis in many parts of the body, particularly ear lobes and fingertips. 1. Decrease in renal blood flow, GFR and urinary output 2. Acceleration of metabolic activities of myocardium resulting in accumulation of 3. excess lactic acid and acidosis 4. Acidosis decreases the efficiency of myocardium leading to further reduction 5. in cardiac output 6. So, the blood flow to vital organs is severely affected 7. The lack of blood flow to the brain tissues produces ischemia resulting in fainting 8. and irreparable damage to the brain. 9. Finally the damage of brain tissues and cardiac arrest kill the victim. HEART FAILURE Heart failure or cardiac failure is the condition in which the heart looses the ability to pump sufficient amount of blood to all parts of the body. Heart failure may involve left ventricle or right ventricle or both. It may be acute or chronic. Acute Heart Failure refers to sudden & rapid onset of signs and symptoms of abnormal heart functions. Its symptoms are severe initially. However, the symptoms last for a very short-time and the condition improves rapidly. Chronic Heart Failure is the heart failure that is characterized by the symptoms that appear slowly over a period of time and become worst gradually. Congestive Heart Failure It is a general term used to describe heart failure resulting in accumulation of fluid in lungs and other tissues. When heart is not able to pump blood through aorta, the blood remains in heart. It results in dilatation of the chambers and accumulation of blood in veins (vascular congestion). This condition is also manifested by fluid retention and pulmonary edema. CAUSES OF HEART FAILURE 1. Coronary artery disease 2. Defective heart valves 3. Arrhythmia (abnormal heartbeat) 4. Cardiac muscle disease such as cardiomyopathy 5. Hypertension 6. Congenital heart disease 7. Diabetes 8. Hyperthyroidism 9. Anemia 10. Lung disorders 11. Inflammation of cardiac muscle (myocarditis) due to viral infection, drugs, alcohol, etc. Signs and Symptoms of Chronic Heart Failure 1. Fatigue and weakness 2. Rapid and irregular heartbeat 3. Shortness of breathing 4. Fluid retention and weight gain 5. Loss of appetite, nausea and vomiting 6. Cough 8. Chest pain, if developed by myocardial infarction. Signs and Symptoms of Acute Heart Failure The signs and symptoms of acute heart failure may be same as chronic heart failure. But the signs and symptoms appear suddenly and severely. When heart starts to fail suddenly, the fluid accumulates in lungs causing pulmonary edema. It results in sudden and severe shortness of breath, cough with pink, foamy mucus and heart palpitations. It may lead to sudden death, if not attended immediately. Cardiovascular Adjustments during Exercise During exercise, there is an increase in metabolic needs of body tissues, particularly the muscles. Various adjustments, which take place in the body, are aimed at 1.Supply of nutrients and oxygen to muscles and other tissues involved in exercise 2.Prevention of increase in body temperature. TYPES OF EXERCISE Exercise is generally classified into two types depending upon the type of muscular contraction. 1. Dynamic exercise 2. Static exercise. SEVERITY OF EXERCISE The cardiovascular and other changes in the body depend upon the severity of exercise also. Based on severity, the exercise is classified into three types: 1. MILD EXERCISE It is the very simple form of exercise like slow walking. Little or no change occurs in cardiovascular system during mild exercise. 2. MODERATE EXERCISE Moderate exercise does not involve strenuous muscular activity and it can be performed for a longer period. Exhaustion does not occur at the end of moderate exercise. The examples of this type of exercise are fast walking and slow running. 3. SEVERE EXERCISE Severe exercise involves strenuous muscular activity and it can be performed only for short duration. Fast running for a distance of 100 or 400 meters is the best example of this type of exercise. Complete exhaustion occurs at the end of severe exercise EFFECTS OF EXERCISE ON CARDIOVASCULAR SYSTEM ON HEART RATE Heart rate increases during exercise. Even the thought of exercise or preparation for exercise increases the heart rate. It is because of impulses from cerebral cortex to medullary centers, which reduces vagal tone. In moderate exercise, the heart rate increases to 180 beats/minute. In severe muscular exercise it reaches 240 to 260 beats/minute. The increased heart rate during exercise is mainly vagal withdrawal and increase in sympathetic tone.  ON BLOOD PRESSURE During moderate isotonic exercise, the systolic pressure is increased. It is due to increase in heart rate and stroke volume. Diastolic pressure is not altered because peripheral resistance is not affected during moderate isotonic exercise. In severe exercise involving isotonic muscular contraction, the systolic pressure enormously increases but the diastolic pressure decreases. The decrease in diastolic pressure is because of the decrease in peripheral resistance. Decrease in peripheral resistance is due to vasodilatation caused by metabolites. During exercise involving isometric contraction, the peripheral resistance increases. So, the diastolic pressure also increases along with systolic pressure. Blood Pressure after Exercise After exercise, the blood pressure falls below the resting level. It is because of vasodilatation caused by metabolic end products accumulated in muscles during exercise. However, the pressure returns to resting level quickly as soon as the metabolic end products are removed from muscles.