Physiology Flashcards
what is “sarcomere length” a surrogate for?
preload
La Place equation for wall stress?
WS = (Pressure x Radius)/ (2 x Wall Thickness)
what is another word for LVEDV?
Preload
what is another word for myocardial wall stress?
afterload
what will increased afterload (e.g. phenylephrine) do to the starling curve?
shift down
what will decreasing afterload (e.g. clonidine, IABP) do to starling curve?
shift up
what are the axes of a starling curve?
SV (y) vs. Preload (x)
what are the axes of a Force-Tension curve?
SV (y) vs. Wall Stress (x)
what will amlodipine do to starling curve and why?
shift up
decreases afterload which is not on x or y axis.
what point on P-V curve is preload?
a (bottom right)
what point on P-V curve is afterload?
c (top left)
if the P-V curve changes in shape, what are the 3 parameters you look at to determine what made the change?
preload (a, bottom right)
afterload (c, top left)
SV
meaning of prominent v wave on RHC?
TR
meaning of canon a wave on RHC
complete HB or VT
meaning of exaggerated y descent on RHC
constriction
what is the order (top to bottom) of the JVP waveforms?
a, c, x, v, y
what do the a, c, x represent in JVP waveform?
a- atrial contraction
c- TV closure
x- passive atrial filling/ventricular contraction
what do the v, y represent in JVP waveform?
v- atrial diastole
y- atrial emptying
are LV and RV pressures concordant or discordant in myocardial restriction
concordant
are the LV and RV pressures concordant or discordant in constrictive pericarditis
discordant
using the PQRST complex, when should the v wave show up?
right after T wave
does the size of v-wave correspond with severity of TR or MR?
no
what does TR do to thermodilution estimate of CO?
underestimates CO
in very severe systolic CHF, what happens to thermodilution estimate of CO? what do you to?
overestimates CO; use used saline b/c fluid warms up by the end of catheter
normal mixed venous sat
65-75%
what value is assumed for FICK eq’n?
oxygen consumption
eq’n for LVOT dopper CO
CO = CSA x VTI x HR
note: CSA = Πr2/2
what acts as a surrogate for Fick CO?
Mixed Venous O2 (MVO2)
what does MAP/CI = ?
SVR
MAP = ?
(2DBP + SBP)/3
PVR = ?
(mean PAP - PCWP) / CO
PVR transplant threshold
< 4 woods units
what Qp/Qs do you close shunt?
> 1.5
If the Qp/Qs is decreased in VSD, what may be the cause?
Eisenmenger’s (conversion to R–>L shunt)
Qp/Qs = ?
(SAO2-MVO2)/(SAO2- PAO2)
MVO2 equation
MVO2 = 3/4SVC O2 + 1/4IVC O2
What’s is considered a step up between mixed venous (MV) and RA?
7
What is considered a step up (not including MVO2 to RA)?
5
