C2- Cardiac Hemodynamics Flashcards
How is Potential energy created?
Another word for PE?
By contracting of ventricles and vascular resistance from arteries
Static pressure
Has the ability to do work
what is gravitational energy?
effect of gravity on static pressure
Think of LE venous return
whats normal BP?
whats a high BP?
Norm: 120/80 (systolic/diastolic)
High: >140/90
What is mean arterial pressure?
avg. pressure over the cardiac cycle
How much of the cardiac cycle does Systole occupy?
Diastole?
Systole: 1/3 of the cycle (at resting HR)
Diastole: 2/3 of the cycle (at resting HR)
What happens to the sys/dias ratios if HR increases?
Systole Increases
Diastole Decreases
How do you calculate mean arterial pressure?
MAP= Diastolic pressure + 1/3 (Systolic blood press - diastolic blood press)
whats a press gradient?
difference of press between to locations within the heart
whats the natural direction of flow if theres a press gradient present?
flow from high to low press
whats the relationship between press and velocity?
directly proportional
whats Bernoulli’s equation?
Change in P = 4(velocity)2
what are the 4 phases of the cardiac cycle?
- IVCT - isovolumic contraction time
- systole
- IVRT - isovolumic relaxation time
- diastole
when does IVCT occur and whats happened in this phase?
how long does it last?
IVCT is the period of time between MV closure and AV valve opening
- press in LV is rising fron 5-80 mmHg
- just before ventricles contract
lasts 30-50 ms
what press must the LV reach for the AO valve to open?
80 mmHg
are the valves open or closed during IVCT?
ALL are closed
what is ventricular systole?
what initiates and stops?
the period of time it takes for the ventricles to eject their contents
initiate: when the ventricular pressure exceeds that of the AO and the SL valves open
stops: when the ventricular pressure is lower than that of the AO and the SL valves open
are valves active of passive structures?
passive
where does muscles contraction begin?
apex
how long does ventricular systole last?
200-300ms
when does IVRT occur and what happens in this phase?
how long does it last?
period of time after the AOV/PV have closed but before the MV/TV open
- press falls in the ventircles (below 80mmHg)
- press increasing in atria
- occurs just before the heart relaxes
50-100ms
are the valves open or closed during IVRT?
ALL closed
when does diastole occur and what happens in this phase?
how long does it last?
period of time when the MV/TV are open and blood moves from atria to ventircles
- starts when ventricular press falls below that of the atria
- ends when LV press rises above LA and MV closes
3 phases of diastole
- early filling (suction)
- diastasis
- late filling
describe the early filling phase.
how long does it last?
which ‘bump’ is this?
LV press drops below LA and MV opens, LV chamber fills by sucking blood from the LA
lasts 150-220ms
first bump
describe diastasis.
what is the press difference between LA and LV at this time? how does it appear on US
period of time after early filling
press between LV/LA is almost equal so MV hangs in a semi open position
what do the atria depolarize during diastasis?
end of the phase
describe the late filling phase.
how long does it last?
which ‘bump’ is this?
press is atria rises above the ventricles which opens the MV again…. atrial contraction pushes remainder of blood into LV
how much filling of the LV is done during early filling?
late phase?
70-75%
25-30%
two other terms for Late filling phase?
slow filling
atrial kick
how much does the diastolic and systolic press change in the RV?
Systolic. 15-30 mmHG
Diastolic: 2-8 mmHg
how much does the diastolic and systolic press change in the LV?
Systolic. 100-140 mmHG
Diastolic: 3-12 mmHg
What’s the mean press in the RA and the LA?
RA: 2-8 mmHg
LA: 2-12 mmHg
when do the atria increase in volume?
during ventricular systole and diastole from the Pulmonary veins
when is the LV at its largest, and smallest?
large: end diastole
small: end systole
whats a normal stroke volume?
50-100 ml/beat at rest
stoke volume equation?
SV= EDV-ESV
cardiac output equation?
CO= SV x HR
cardiac index equation?
CI: CO/BSA
what is VTI?
velocity time intergral which equals the stroke distance (in cm)
stoke volume doppler equation?
SV= (pie x r2) x (VTI)
what % of O2 does deoxygenated blood have?
~75%
whats the O2 saturation in the R heart and L heart?
R: 75%
L: 98%
whats angina pectoris and what causes it?
chest pain
caused by lack of O2 and nutrients to the heart, muscle of the heart is too thick or high afterload
what factors effect stoke volume and cardiac output?
preload
afterload
inotropic force
chronotropic force
whats preload?
amount of blood volume in the ventricles at end diastole
volume of blood delivered to the ventricles
whats the frank starling law?
another word for it?
the degree of stretch of the ventricles is proportional to the volume of blood in the chamber
more volume = more stretch = harder contraction
length tension relationship
how does the frank starling law effect SV?
it increases it
whats the relationship pf preload to HR?
slow HR: more time for ventricular filling = more ventricular stretch
higher HR: less time for filling = less stretch
define inotropic force?
another name for it
contractility of the heart muscle
force velocity relationship
whats the relationship between preload and inotropic force?
direct
whats afterload and what effects it?
resistance to ventricular emptying
effected by: viscosity arterial resistance vascular geometry valvular stenosis
how does disease effect inotropic force?
What relationship represents inotropic force?
diease: negative inotropic response, LV cant contract enough
Force velocity
what is chronotropic force?
another term for it?
rate of contraction.. how fast and how much that walls move inwards
interval strength relationship
how does increased afterload effect the velocity of fiber shortening, stroke volume and CO?
decreases ALL
What is pulse presssure formula?
SBP-DBP
What’s border line blood pressure?
130/85
How blocked does a coronary artery have to be to create angina pectoris?
75%
How does medication effect inotropic force?
Produces a + inotropic response and makes it easier for the heart to contract by altering the sympathetic NS
What’s happening to the volume in the LV during IVRT?
It remains constant
When MPAP is elevated, does the PAT get longer or shorter?
Shorter…. velocity and pressure and directly related
Which vessels of the heart have the lowest O2 content and what is it?
Coronary sinuses
50%
The LV uses approximately how much of the Ow supplied by the coronary arteries at rest
50%