current status of stress testing john hamaty d.o
TRANSCRIPT
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
PHARMACOLOGICIndications
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/ADENOSINE-CONTRAINDICATIONS
Bronchospasm- active lung disease
AV blockTaking caffine or
methalxanthinesHypotention- <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.
DOBUTAMINE-CONTRAINDICATIONS
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
Real-time imaging
Additional information
(LVH, valves)
Patient convenience Cost
Relative perfusion
More objective interpret.
Quantitation of extent
of perfusion abnorm.
More extensive literature on prognosis