ISCHEMICHEARTDISEASE;CONGESTIVEHEARTFAILURE;SHOCK.ppt

ISCHEMIC HEART DISEASE; CONGESTIVE HEART FAILURE; SHOCK Coronary Artery Disease Vascular disorder ? narrowing/blockage of arteries to heart Arteries supplying heart branch directly from aorta Bring richly oxygenated blood Necessary to supply myocytes with oxygen, nutrients Heart needs constant supply of oxygen for muscle activities Coronary artery disease ? decrd blood supply to cardiac muscle (Fig. 23-21) So ischemia Persistent ischemia ? hypoxia Infarction leads to “heart attack” About 50% of all deaths in U.S. Heart has high metabolic rate Constantly contracting to pump oxygenated and nutrient-filled blood to rest of body Urgent to life to maintain the health of heart, so Urgent to life to maintain oxygen-rich blood flow to heart Modifiable/nonmodifiable factors put some people more at risk than others Same as for vascular disease: Hyperlipidemia - incrd plasma lipoproteins Hypertension - may cause or exacerbate Cigarette smoking - STOP!! Diabetes Myocardial ischemia results Decr’d blood flow to heart (Fig.23-14) Myocardial cell metabolic demands not met Time frame of coronary blockage 10 seconds following coronary block Decr’d strength of contractions Abnormal hemodynamics Several minutes later Decr’d glucose metab ? decr’d aerobic metab, so Anaerobic metab, so Build-up of lactic acid (toxic within cell) Time frame – cont’d 20 minutes after blockage Myocytes still viable, so If blood flow restored, and incr’d aerobic metab, and cell repair, ? Incr’d contractility About 30-45 minutes after blockage, if no relief Cardiac infarct Clinical May hear extra, rapid heart sounds (S3) ECG changes (Fig.23-18) T wave inversion ST segment depression Chest pain 20-30% of those suffering myocardial ischemia Called angina pectoris Feeling of heaviness, pressure Moderate ? severe In substernal area Often mistaken for indigestion May radiate to neck, jaw, left arm/shoulder Chest pain – cont’d Due to Accum’n lactic acid in myocytes, OR Stretching of myocytes Three typ