When analyzing the pressure-volume loop for decreased venous compliance, would afterload be increased or decreased? Here is where I am at mentally. Decreased venous compliance-->decreased pooling-->greater amount of blood that returns to the heart--> increased filling-->increased preload-->frank-starling mech. activated so contractility increases thus you have an inc. in stroke volume-->increased cardiac output--> higher areterial pressure thus increased afterload.
BUT: When you analyze the pressure-volume loop for decreased venous compliance the end diastolic volume is increased [as it should be] and end systolic volume is decreased [as it should be due to inc. cardiac output]---but according to my reasoning afterload should be increased due to inc. cardiac output.
I thought that on a pressure-volume loop diagram afterload-increases are represented by a shift to the RIGHT along the end-systolic volume-pressure (ESVP)curve. But the actual PV-loop diagram for decreased venous compliance has a shift to the LEFT down the ESVP curve. What's going on or what am I missing??
So an increase to the right or left along the ESVP curve won't necessarily tell you whether you have an increase or decrease in afterload? Is this true?
-Thank you for any help
-Richard
BUT: When you analyze the pressure-volume loop for decreased venous compliance the end diastolic volume is increased [as it should be] and end systolic volume is decreased [as it should be due to inc. cardiac output]---but according to my reasoning afterload should be increased due to inc. cardiac output.
I thought that on a pressure-volume loop diagram afterload-increases are represented by a shift to the RIGHT along the end-systolic volume-pressure (ESVP)curve. But the actual PV-loop diagram for decreased venous compliance has a shift to the LEFT down the ESVP curve. What's going on or what am I missing??
So an increase to the right or left along the ESVP curve won't necessarily tell you whether you have an increase or decrease in afterload? Is this true?
-Thank you for any help
-Richard
