1. Left Ventricular Pressure-Volume Loops

2. Left Ventricular Pressure-Volume Loops
Pressure-volume loop plots LV pressure against LV volume through one complete cardiac cycle
Factors affecting:
Preload
Afterload
Contractility
IHSS
Valvular problems

4. Left Ventricular Pressure-Volume Loops
KNOW:
When the mitral and aortic valves are open and closed during each phase
When systole begins (B) and ends (D)
When diastole begins (D) and ends (B)
Diastolic filling occurs between points A and B
Ejection occurs between points C and D

5. Left Ventricular Pressure-Volume Loops
Acute changes in preload
Increased preload:
Filling increases
SV increases
Decreased preload:
Filling decreases
SV decreases
*NOTE: the ventricle empties to the same end-systolic volume after either an increase or decrease in preload

6. Left Ventricular Pressure-Volume Loops

7. Left Ventricular Pressure-Volume Loops
Cardiac tamponade
Unique loop

8. Left Ventricular Pressure-Volume Loops
Acute changes in Afterload
Increased afterload:
Ventricle empties less completely
SV decreases
Increase in BP
(shifts up and right)
Decreased afterload:
Ventricle empties more completely
SV increases
Decrease in BP
(shifts down and left)

9. Left Ventricular Pressure-Volume Loops

10. Left Ventricular Pressure-Volume Loops
Altered contractility
Increased contractility:
Ventricle empties more completely
SV increases
BP increases
(shifts up and left)
Decreased contractility:
Ventricle empties less completely
SV decreases
BP decreases
(shifts down and right)

11. Left Ventricular Pressure-Volume Loops

12. Left Ventricular Pressure-Volume Loops
Summary of concepts:
Alterations in preload: end-diastolic volume increases or decreases, but the amount of blood in the chamber at end-systole does not change
Stroke volume falls: result of either an increase in afterload or a decrease in contractility, the volume of blood in the LV chamber increases (chamber dilates)
Stroke volume increases: result of a decrease in afterload or an increase in contractility, the volume of blood in the LV chamber decreases (chamber shrinks)

13. Left Ventricular Pressure-Volume Loops
IHSS
UNIQUE
P-V loop is shifted to smaller volumes and larger pressures (due to outflow tract obstruction)
ONLY IHSS causes this type of combined shift

14. Left Ventricular Pressure-Volume Loops
Chronic Aortic Stenosis
(increased afterload)
Concentric hypertrophy permits the LV to generate greater pressure
LV volumes remain about normal
P-V loop shifts upward

15. Left Ventricular Pressure-Volume Loops
Mitral Stenosis
(Decreased preload)
LV filling is diminished
P-V loop reflects a decreased preload
Emptying is about normal

16. Left Ventricular Pressure-Volume Loops
Acute Aortic Insufficiency (regurgitation)
Volume in the LV chamber increases during early diastole
P-V loop is small
No isovolemic relaxation

17. Left Ventricular Pressure-Volume Loops
Chronic Aortic Insufficiency
(Eccentric hypertrophy)
LV chamber dilates
P-V loop is large because the SV is large
No isovolemic relaxation

18. Left Ventricular Pressure-Volume Loops
Be able to identify a P-V loop that shows aortic insufficiency
Be able to identify whether the loop reflects acute or chronic aortic insufficiency

19. Left Ventricular Pressure-Volume Loops
Acute Mitral Regurgitation
P-V loop is small
No isovolemic contraction

20. Left Ventricular Pressure-Volume Loops
Chronic Mitral Regurgitation
LV hypertrophies (eccentric)
LV chamber dilates
P-V loop is large because the SV is large
No isovolemic contraction

21. Left Ventricular Pressure-Volume Loops
A = Normal
B = Mitral stenosis
C = Aortic stenosis
D = mitral regurgitation (chronic)
E = aortic regurgitation (chronic)