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Left Ventricular Pressure-Volume Loops. Pressure-volume loop plots LV pressure against LV volume through one complete cardiac cycle Pressure-volume loop.

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Presentation on theme: "Left Ventricular Pressure-Volume Loops. Pressure-volume loop plots LV pressure against LV volume through one complete cardiac cycle Pressure-volume loop."— Presentation transcript:

1 Left Ventricular Pressure-Volume Loops

2 Pressure-volume loop plots LV pressure against LV volume through one complete cardiac cycle Pressure-volume loop plots LV pressure against LV volume through one complete cardiac cycle Factors affecting: Factors affecting: – Preload – Afterload – Contractility – IHSS – Valvular problems

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4 Left Ventricular Pressure-Volume Loops KNOW: KNOW: 1.When the mitral and aortic valves are open and closed during each phase 2.When systole begins (B) and ends (D) 3.When diastole begins (D) and ends (B) 4.Diastolic filling occurs between points A and B 5.Ejection occurs between points C and D

5 Left Ventricular Pressure-Volume Loops Acute changes in preload Acute changes in preload – Increased preload: Filling increases Filling increases SV increases SV increases – Decreased preload: Filling decreases Filling decreases SV 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 Cardiac tamponade Cardiac tamponade – Unique loop

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

9 Left Ventricular Pressure-Volume Loops

10 Altered contractility Altered contractility – Increased contractility: Ventricle empties more completely Ventricle empties more completely SV increases SV increases BP increases BP increases (shifts up and left) (shifts up and left) – Decreased contractility: Ventricle empties less completely Ventricle empties less completely SV decreases SV decreases BP decreases BP decreases (shifts down and right)

11 Left Ventricular Pressure-Volume Loops

12 Summary of concepts: 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 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 ONLY IHSS causes this type of combined shift

14 Left Ventricular Pressure-Volume Loops Chronic Aortic Stenosis 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 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) 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 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 a P-V loop that shows aortic insufficiency Be able to identify whether the loop reflects acute or chronic aortic insufficiency Be able to identify whether the loop reflects acute or chronic aortic insufficiency

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

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


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