Ischemic Heart Disease

myocardial infarction general Increased myocardial metabolic oxygen demand -severe hypertension -tachycardia -severe aortic stenosis -coronary artery vasosparm Decreased myocardial metabolic oxygen supply -anatomical obstruction -severe hypotension -hypoxemia -severe aortic stenosis or aortic regurgitation Coronary Artery Disease -atherosclerosis is the most common cause of coronary artery disease -approximately 1/3 of all deaths in the western society is attributed to CAD -major casue of perioperative morbidity and mortality - 5-10% incidence within the surgical patient population Major risk factors for CAD -hypertension -diabetes mellitus -hypercholestrolemia -cigarette smoking -male sex -family history of heart disease Other risk factors for CAD -obesity -history of CVA -history of PVD -anuerysm Signs/symptoms -angina -myocardial ischemia -myocardial infarction -dysrhythmias -ventricular dysfunction ---> "Ischemic Cardiomyopathy" when symptoms of CHF predominate unstable angina -abrupt increase in severity, frequency (x > 3 episodes/day), and duration of aninal attacks -angina at rest -new onset angina within the past 2 months with severe or frequent episodes x > 3/ day abrupt increase in severity, frequency and duration usually reflects severe underlying CAD esp assoc. with ST seg changes frequently precedes myocardial infarction Pathophysiology -plaque dissruption with platelet aggregation or thrombus -vasospasm Treatment -approximately 80% of patients have critical stenosis of one or more arteries therefore require admission to CCU Generally treated with unless contraindicated: -anticoagulation: ( i.v heparin, asprin) -vasodilation (nitroglycerin) -beta blocker -calcium channel blocker chronic stable angina Signs/symptoms generally absent when atherosclerotic lesions are < 50 - 75% occlusion of the coronary artery when coronary artery occlusion is approximately 70%, maximal compensatory dilation occurs chest pain generally occurs when occlusion of the coronary artery exceeds 50-75% Chest pain usually: -substernal -exertional -radiating to the neck or arm -relieved by rest or nitroglycerin Variation of associated chest pain: -epigastric pain -back pain -neck pain -silent: no pain ex. diabetic patients At rest: coronary blood flow is usually adequate therefore oxygen supply >/= oxygen demand With activity: coronary blood flow is usually inadequate therefore oxygen supply < oxygen demand ex of decreased supply: vasospasm ex of increased demand: increased metabolic demand (stress, physical activity, fever) Variable Threshold: patients who have a variable level of activity or varying level of emotional stress ex. Printzmetal Angina Fixed Threshold: patients who have a relatively fixed level of activity or emotional stress ex. Classic Exertional Angina Treatment (5 fold) -correction of coronary risk factors (smoking, high cholesterol intake, DM) -lifestyle modification (eliminate stress and improve exercise tolerance) -correct underlying medical problems (HTN, anemia, thyrotoxicosis, fever, infection, adverse drug effects) -drug therapy (nitrates, beta blockers, calcium channel blockers, other) -surgical correction of coronary lesion (percutaneous angioplasty +/- stenting, CABG) Prognosis overall prognosis depends on: -number and severity of coronary artery obstruction/s -ventricular function