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 Stable angina

Variant angina

Silent myocardial infarction

Acute coronary syndrome No ST- elevation

unstable angina

non-ST- elevation 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

ST – elevation

Q- wave AMI

• 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)