cardiac Flashcards
Cardiac Output =
stroke volume x HR
CO =
Mean Arterial Pressure (MAP)/ Peripheral Resistance (PR)
Calculating MAP
(PP/3) + Diastolic pressure
Stroke volume =
end diastolic volume - end systolic volume
Factors influencing EDV
Arterial pressure - direct Ventricular compliance - direct
Factors influencing ESV
Ventricular contractility - indirect
Frank Starling Law
force contraction vs. length of muscle
Increase venous return = increased ventricular contraction = increased SV
Ventricular afterload is
the pressure in the arteries that are exerted back on the ventricles
Increased ventricular afterload =
Increased ESV
Decreased SV
Calculation for ejection fraction
Ejection fraction = (SV/EDV) x 100
If HR increases then
EDV decreases
SV decreases
Ejection fraction is
the percentage of blood pumped out of the heart per beat relative to the EDV
Pulse pressure is
the pressure necessary to feel a pulse
Factors relating to pulse pressure
- SV - direct
- HR - inverse
- AD (arterial distensibility) - Inverse
- PR - Inverse
Calculation for Pulse Pressure (PP)
PP = Systolic pressure - diastolic pressure
Homeostatic mechanisms for cardiac maintenance are
- Capillary fluid shift - fluid moved out of vein to decrease volume
- Renal adjustment of plasma volume
- Control of heart rate - carotic sinus reflex
- Vascular reflexes - diameter of sphincters change
Starling forces: filtration vs. absorption
- Outward pressures
- HBP - Hydrostatic blood pressure
- TPOP - Tissue protein
- Inward pressures
- THP - Tissue H pressure
- PPOP - plasma protein osmotic pressure
*
Absorption occurs in the
systemic capillaries
Factors influencing edema
- Excess out
- Increased HBP: heart failure
- Increased TPOP: inflammation
- Excess in
- Decreased PPOP: protein deficiency
