CURRENT STATUS OF STRESS TESTING JOHN HAMATY D.O. INTRODUCTION Form of imprisonment in 1818 Edward Smith’s observations TECHNIQUE Heart rate Blood pressure ECG parameters Physical appearance INDICATIONS Ischemic heart disease Medical efficacy Baseline post procedure Culprit vessel Hypertension management COMPLICATIONS Cardiac arrhythmias Sudden death Myocardial infarction Fatigue Heart failure hypotension DIAGNOSTIC VALUE OF STRESS TESTING (SENSITIVITY & SPECIFICITY) Designed to test how effectively a test separates subjects with disease from healthy individuals ST segment depression has 84% specificity for angiographically significant CAD(assumes 85% heart rate) Prognostic Value of Testing Post MI Stable CAD Post CABG(3 mos.) Post intervention(6 mos.) High Risk(Diabetics*******) Hypertension ASSESSING THE APPROPRIATE TEST FOR THE APPROPRIATE PATIENT Treadmill Treadmill with imaging Pharmacologic Echocardiography PHARMACOLOGIC Indications Patients unable to exercise Preoperative risk stratification Early postinfarct risk stratification Left bundle branch block Fixed-rate pacemakers PHARMACOLOGIC TESTING Persantine/Adenosine Needs nuclear augmentation Coronary vasodilation Bronchospastic Not for acute asthmatic’s or severe COPD Dobutamine Inotrope Vasodilator Afterload reducer Increase heart rate May require atropine No bronchospastic component(COPD) PERSANTINE IV dosing of .56ml/kg over 4 minutes 5 fold increase in coronary blood flow velocity Acts by indirectly increasing intravascular adenosine levels Precursor to adenosine Reverse effects with Aminophylline(dosing from 50-250mg iv injection ADENOSINE Actively transported across cell to activate the A1 and A2 receptors, stimulates adenocine cyclase in smooth muscle and produces vasodilatation Leads to increase in cAMP, causes increase in Ca levels leading to smooth muscle relaxation PERSANTINE/ADENOSINECONTRAINDICATIONS Bronchospasm- active lung disease AV block Taking caffine or methalxanthines Hypotention- <90mm hg DOBUTAMINE Dobutamine is a synthetic catecholamine, which directly stimulates both beta-1 and beta-2 receptors. A dose-related increase in heart rate, blood pressure, and myocardial contractility occurs. DOBUTAMINE increases regional myocardial blood flow based on physiological principles of coronary flow reserve. A similar dose-related increase in subepicardial and subendocardial blood flow occurs within vascular beds supplied by significantly stenosed arteries, with most of the increase occurring within the subepicardium rather than the subendocardium. Thus, perfusion abnormalities are induced by the development of regional myocardial ischemia. DOBUTAMINECONTRAINDICATIONS Patients with recent (1 wk) myocardial infarction; unstable angina; significant aortic stenosis or obstructive cardiomyopathy; atrial tachyarrhythmias with uncontrolled ventricular response; history of ventricular tachycardia, uncontrolled hypertension, or thoracic aortic aneurysm; or left bundle branch block should not undergo dobutamine stress testing. Treadmill Stress Testing Must be able to walk!! Can be used alone for low risk cases Augmentation can be with nuclear or echo Physiologic response Blood pressure response to exercise Exercise prescription STRESS ECHO Can be done with treadmill or dobutamine Assesses wall motion Evaluates regional and global wall motion Fast answers No radiation exposure STRESS ECHO STRESS NUCLEAR Cardiac function Relative perfusion Real-time imaging More objective interpret. Additional information Quantitation of extent (LVH, valves) Patient convenience Cost of perfusion abnorm. More extensive literature on prognosis