CORONARY HEART DISEASE

CORONARY HEART DISEASE I. Coronary Circulation  Coronary Arteries: 1. Left coronary artery  left anterior descending artery  left Circumflex artery 2. Right coronary artery  posterior descending artery  Control of coronary blood flow: 1. metabolic control  adenosine, K ions, lactic acid, CO2 2. endothelial control  endothelial cells antithrombogenic property  vasodilating factor - EDRF  vasoconstricting factor – ET-1 3. collateral circulation  Assessment of coronary blood flow: 1. electrocardiography (ECG) 2. exercise stress testing  treadmill test  bicycle exercise 3. pharmacologic stress test  adenosine  dipyridamole 4. nuclear imaging  myocardial perfusion imaging -“ cold spot”  acute infarct imaging - “ hot spot” 5. cardiac catheterization 6. serum cardiac enzymes II. Coronary Atherosclerosis:  fixed or stable plaque  unstable plaque  thrombosis & vessel occlusion  white platelet- containing thrombi  red fibrin - containing thrombi  steps in clot formation:  release of ADP , thromboxane A2 & thrombing  receptors on platelet surface activated  fibrinogen binds adjacent platelets III. Types of Coronary Heart Disease: Coronary heart disease (CHD) Chronic ischemic heart disease Acute coronary syndrome ST – elevation Stable angina Variant angina Silent myocardial infarction No ST- elevation unstable angina non-ST- elevation AMI Q- wave AMI  serum cardiac markers: 1. myoglobin  increases within 1 hr after MI  peaks within 4- 8 hrs 2. creatine kinase –MB (CK-MB)  increases within 4-8 hrs of MI  decreases to normal within 2-3 days 3. troponin T & I  increases slowly up to 3- 4 days  Tissue changes after MI:  0 – 0.5 hrs  reversible injury  1 – 2 hrs  onset of irreversible injury  4 – 12 hrs  onset of coagulation necrosis  18 -24 hrs  continued necrosis  1 – 3 days  total coagulation necrosis  3 – 7 days  infarcted area soft with yellow center & hyperemic edges  7 – 10 days  onset of scar tissue generation  8th week  scar tissue replacement complete III. Tx of Coronary Heart Disease (CHD): 1. Therapeutic lifestyle change (TLC) 2. pharmacologic  beta – blockers  calcium channel – blockers  nitroglycerin / nitrates  lipid- lowering agents (ie. statins)  antiplatelets a. aspirin b. ticlopidine c. clopidrogel  anticoagulant a. heparin b. warfarin  thrombolytics a. streptokinase b. urokinase 3. Revascularization procedures a. percutaneous transluminal coronary angioplasty (PTCA) b. coronary artery bypass grafting (CABG)