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32 Cards in this Set
- Front
- Back
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3 determinants of supply of myocardium
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vascular resistance
coronary blood flow O2 carrying capacity |
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Where is regulation of blood flow handled?
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smaller "resistance" vessels
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When does most coronary blood flow occur?
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diastole
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Formula for coronary perfusion pressure
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Aortic diastolic pressure - LVEDP
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How does diastole change with HR?
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inversely
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Major determinant of resistance in blood vessels
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radius of BV
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At what percentage is coronary suppy decreased with ischemia?
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70%
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Most potent known endogenous vasodilator
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Nitric oxide
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What impairs the endothelial capacity to regulate tone?
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atherosclerosis
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2 ways atherosclerosis dec supply
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fixed dec in radius (stenosis)
dec in dynamic vasodilatation (endothelial dysfunction) |
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Laplace's law
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cavity volume is major determinant in wall stress
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relationship of wall stress to wall thickness
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inversely proportional
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afterload, preload, contractility relationship to myocardial O2 demand
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directly proportional
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Effect of catecholamines on myocardial oxygen demand
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inc. (drives inc contractility and HR)
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What does PA cause in atherosclerotic coronary arteries?
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inc demand and dec supply of myocardial oxygen (ischemia)
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Another name for reversible recovery of myocyte function
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transient ischemia
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Potential explanation for painful angina
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ischemic cardiomyocytes release metabolic byproducts such as lactate, serotonin, and adenosine that activate local afferent pain fibers
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During ischemia, which function of the heart is more impaired?
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stiff, so diastole
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5 major findings of ischemia
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dyskinetic apical impulse, rales, S4, mitral regurgitation, diaphoresis
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3 major changes for ischemia on ECG
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new ST-segment elevation >1mm
new ST-segment depression New T-wave inversion |
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Which component of the heart receives less blood flow during exercise?
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endocardium
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Positive treadmill test is marked by what two things?
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typical chest discomfort is reproduced
ECG abnormalities >1mm ST segment depression |
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Which test is better, exercise stress or nuclear imaging?
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nuclear imaging
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gold standard for Myocardial ischemia
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coronary angiography
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Cause of chronic stable angina
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generally a fixed obstructive atheromatous plaque >1 coronary arteries
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Tx of chronic stable angina targets what?
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Demand side of see-saw
(dec HR, dec BP, dec contractility, dec wal tension) |
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Gold standard for chronic stable angina
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beta-blockers (dec myocardial oxygen demand, inc myo oxygen supply)
Also inhibits renin release (dec AngII) |
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If angina persists despite medical therapy, what options are available?
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Stenting (but doesn't change mortality)
CABG (from L internal thoracic to LAD or saphenous veins) |
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Unstable angina is a change in what?
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supply changes (rupture of previously stable clots)
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Unstable angina best tx by what?
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restore supply
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Main groups of tx of unstable angina
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anti-platelet (aspirin, clopidogrel)
Anti-thrombic (heparin, direct thrombin inhibitors, LMWH) Stenting greatly helps! |
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Variant angina/prinzmetal angina cause
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intracoronary acetylcholine provoking a spasm
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