General Flashcards
left ventricular end-diastolic volume
150mL
LV-end systolic volume
50mL
Stroke volume
100mL
Ejection fraction
67%
LV end-diastolic pressure
10mmHg
LV systolic
130mmHg
RA pressure
3 mmHg
RV systolic pressure
25mmHg
LA pressure
8mmHg
pre-load determined by…
End diastolic pressure or volume
Frank-Starling mechanism
The greater the EDV (pre-load), the greater the force of contraction
the resistance ventricle must overcome to pump out its contents
afterload/ systollic ventricular wall tension or stress
Ventricular wall stress (afterload) is equal to…
ventricular pressure X ventricular chamber radius
divided by
2 X ventricular wall thickness
Pvent X r
2 X wall thickness
**Laplace relationship
As arterial blood pressure in aorta (or pulmonary trunk) goes up…
Stress increases proportionately
The greater the ventricular wall thickness (within physiologic range)…
The less stress
Determinants of force of ventricular contraction
preload afterload contractility/inotropic autonomics hormones drugs ventricular compliance
ventricular compliance
stiffness of the ventricular wall harder to fill during diastole Decreased by... --fibrosis --amyloidosis --any process causing interstitial infiltration by something more rigid than normal
Restrictive cardiomyopathy
when ventricular compliance decreases below ability of atrium to fill it normally…restricts cardiac pumping
Diastolic dysfunction
impaired cardiac filling
Systolic dysfunction
impaired cardiac pumping
Usually caused by:
–impaired contractility OR
–greatly increased afterload
Effects of Systolic Dysfunction
decreases:
- -amount of blood ejected form ventricle
- -stroke volume
- -ejection fraction
Diastolic Dysfunction effects
Does NOT usually reduce ejection fraction
5 major categories of factors determining Heart pump function (Cardiac output)
- Preload
- Afterload
- Contractility
- Compliance
- Heart rhythm
Ventricular gallop
S3
