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surfing the internet, I found this page about effect of afterload on sv
http://cvphysiology.com/Cardiac Function/CF008.htm
my problem is with increasing EDV:
ESV is increased that's okay ,,on adding this increased ESV to venous return we have larger EDV ..why??? decreased stroke volume means decreased venous return right?since venous return normally equals cardiac out okay?on adding decreased venous return to increased ESV we obtain the same EDV
so why EDV volume is increased in this case?
thanks
http://cvphysiology.com/Cardiac Function/CF008.htm
my problem is with increasing EDV:
The effects of afterload on ventricular end-systolic and end-diastolic volumes can be illustrated using pressure-volume loops (Figure 2). If afterload is increased by increasing aortic diastolic pressure, the ventricle has to generate increased pressure before the aortic valve opens. The ejection velocity after the valve opens is reduced because increased afterload decreases the velocity of cardiac fibers shortening as described by the force-velocity relationship. Because there is only a finite time period for electrical and mechanical systole, less blood is ejected (decreased stroke volume), which increases the ventricular end-systolic volume as shown in the pressure-volume loop. Because end-systolic volume is increased, this extra blood within the ventricle is added to the venous return, which increases end-diastolic volume. Ordinarily, in the final steady-state (after several beats), the increase in end-systolic volume is greater than the increase in end-diastolic volume so that the difference between the two, the stroke volume, is decreased (i.e., the width of the pressure-volume loop is decreased).
ESV is increased that's okay ,,on adding this increased ESV to venous return we have larger EDV ..why??? decreased stroke volume means decreased venous return right?since venous return normally equals cardiac out okay?on adding decreased venous return to increased ESV we obtain the same EDV
so why EDV volume is increased in this case?
thanks