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25 Cards in this Set
- Front
- Back
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how do you calculate flow? |
flow (L/min) = pressure gradient/ TPR |
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what is the atrial kick |
right after P wave there's a bump in LV pressure
LV pressure LVP is low during diastole but obvi not 0 |
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how to calculate mean arterial pressure
pulse pressure? |
MAP = DBP + (SBP-DBP)/3
SBP-DBP |
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heart sounds S1 and S2 |
S1 from AV closure S2 closure of aortic and pulmonary closure |
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how do LV volume and LV flow relate |
flow ml/sec is the rate of change of LVV |
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as you age atrial contraction contributes to ventricular filling.. |
more.
or when exercising. it really is a top offer. |
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if hr during exercise was up and LV contraction time was shorter it would not be a big deal. why |
most of the volume has been sent out by the time the stroke is half way through |
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how do you calculate stroke volume |
LVEDV end diastolic volume - LVESV = SV |
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LVEDP is really..? LVEDV?
dP/dt_max_ |
an index of preload which is really length of fibers another index of preload
rate of development of LVP is index of contractility. The max is just the highest it goes |
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during diastole the LA pressure is the same as |
LVP because the AV valve is open |
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how does respiratory pump work? |
you're breathing hard during exercise and that causes negative pressure in chest cavity which helps to fill ventricles |
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what are we really going to assess: how cardiac ___ function |
pump |
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PV curves
diastolic PV relationship is the same as |
passive length- tension relationship (from the active/passive/total stuff) |
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what is compliance?
what happens if lose compliance? |
change V/ change P
dV/dP = 1/slope of the curve
if myocardium is stiff, less compliant (change in volume is less, so steeper slope) |
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what would make a heart less compliant? |
myocardial hypertrophy
deposition of less elastic elements = amyloidosis
with ageing |
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how does the PV loop relate to work and stuff |
the area within the PV loop = integral PdV
and the work is proportional to myocardial oxygen demand |
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what is the PV point that tells preload?
that's hard, so what's used clinically? |
LVEDV or LVEDP
pulmonary capillary wedge pressure: done using a catheter to get into RA, RV, pulmonary pressure, then wedge in vessel and can see pressure on other side which tells you LVEDP |
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effects of symapathetic stimulation on ventricles |
preload is same
work performed increased because pressure is higher = increased contractility
rate of performing work is increased: happens in shorter time |
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what does the volume of CO from RV compare to LV |
it's the same. It's at 1/5 the pressure because lung resistance is less.
but it has to be the same or blood would build up/run out in the lungs |
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starling's law of the heart
what implications? |
relates EDV to CO so preload to CO
demand pump: pumps whatever is delivered to it
it is homeostatic: balancing SV right side with SV left ventricle |
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what is laplace's law
what does it explain? |
P = 2Tension/radius so T = PR/2
heart can increase work it performs by dilating but at a cost of Laplace's law: the tension needed is doubled when radius is doubled, so dilating is high cost.
so you up CO by using contractility insead |
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used beta agonist to up LV force and dP/dt. No change in systolic pressure??? |
it also vasodilates so. |
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why all is ischemic muscle struggling to contract |
less muscle is contracting the dead parts holo balloon out to take up energy |
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what is going on in CHF?
what was the classic approach to heart failure? |
myocardium taxed to limits: elevated preload is able to maintain CO (looks fine in CO and bp, but it is not OK)
starling domain small heart is happy heart |
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how does descending limb works? |
if CHF, and lose EDV -> larger SV such that EDV - -> SV - - > EDV it just keeps getting worse and worse |
