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28 Cards in this Set
- Front
- Back
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What is the equation for Stroke volume?
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EDV-ESV=SV
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What is the equation for ejection fraction
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SV/EDV * 100=EF
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What is the equation for cardiac output?
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SV*HR=CO
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what is the cardiac index
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CO/SA*100
Cardiac Output/Surface area in m^2 |
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what is left ventricular stroke work?
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LVSW= SV * LVPP
Left ventricular pulse pressure * Stroke volume |
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What is Treppe?
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this an increases in muscular contraction (affects stroke volume)
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What factors affect the preload of stroke volume?
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preload=EDV
-filling time -compliance -filling pressure -atrial systole -pericardial constraint |
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what factors affect the afterload of stroke volume?
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-arterial pressure (including peripheral resistance, arterial compliance)
-viscosity of blood -valve function |
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What defines LVPP?
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LVPP is the PEAK systolic pressure minus the end diastolic pressure (peak of systolic graph, and the pressure at the bottom right corner, just before isovolumetric contraction, and the EDP)
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What is tension in the ventricular wall sysnomus with?
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End Diastolic Volume, or End Diastolic pressure (both measure in the ventricle...)
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What does preload affect in the ventricular wall?
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resting fiber length, which has an affect on the length tension relationship
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What happens to Stroke Volume as end diastolic volume increases?
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The greater EDV, the more cross bridging the cardiac muscle can experience....So Greater Stroke Volume
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What does the heart do to compensate for increased volume, at fixed afterload (aortic pressure), and fixed contractility?
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with more blood, the SV volume will increase, by increasing the pressure.
with greater EDV's, the maximum pressure that can be generated becomes greater |
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How does ventricular filling time related with HR?
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faster HR, usually less filling time (so lower EDV, and lower SV)
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How does ventricular compliance affect preload?
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low ventricular compliance can impede filling, so less blood available
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When is the contribution (the 10%) of atrial systole to filling most important?
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when filling time is reduced (so at increased HR's)
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How can pericardial constraints affect preload?
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with increased fluid around the heart, the ventricles become less compliant, and reduces filling
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When does CO become affected by increased heart rate. why is it not affected sometimes?
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At small increased in HR, the SV decreases
(CO=HR*SV) But at heart rates greater than 150....CO can become adversely affected |
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What system is used to preserve SV and increase CO at fast HR's?
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sympathetic stimulation, will increase/preserve SV due to increased contractile force of the heart
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What conditions can reduce ventricular compliance?
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hypertrophy and ischemia
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if the equation for compliance is change in V/Change in P...what is the equation for stiffness?
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Change in P/ Change in V= Stiffness
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How does CVP, and Intrathoracic pressure affect RV,RA,LA,LV
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with decreased intrathoracic pressure...CVP goes up, as does venous return to RA.
More blood (preload) in RA...which goes into the RV...forces an increase in SV (and output) More output for RV increases the preload on the LV! |
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according to this lecture..how much of EDV is atrial systole responsible for?
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20-30%
this can change with increased HR, and atrial contractility |
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What estimates the afterload? what is its equation?
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MAP estimates afterload (AKA mean arterial pressure)
its equation is MAP= DP + pp/3 mean arterial pressure= diastolic pressure + pulse pressure (systolic-dastolic)/3 |
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What is the relationship between afterload, and stroke volume, velocity of ejection?
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these both are INVERSELY related.
the greater the afterload (or pressure that the ventricle has to force against) the lower the SV and velocity of ejection will be |
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What are the the effects on the heart, valves, and volumes due to increased afterload? (assuming constant EDV)
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The aortic valve would open later, and close sooner
Increases end systolic volume (manages to force less blood out) reduced stroke volume (for same reasons) |
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What clinical conditions increase afterload?
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increased aortic pressure
aortic stenosis increase PVR (peripheral vascular resistance) increased blood viscosity decreased arterial compliance (so more pressure per volume) |
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what is the physiological compensation for an increase in afterload?
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the EDV increases.
so stroke volume is the same...all the numbers are just higher (EDV and ESV are both higher) |
