Left-Ventricular-Pressure-Volume-Loops左心室壓力容積環(huán)課件

1、Left Ventricular Pressure-Volume LoopsLeft Ventricular Pressure-VolLeft VentricularPressure-Volume LoopsPressure-volume loop plots LV pressure against LV volume through one complete cardiac cycleFactors affecting:Preload Afterload ContractilityIHSSValvular problemsLeft VentricularPressure-VoluLeft-V

2、entricular-Pressure-Volume-Loops左心室壓力容積環(huán)課件Left VentricularPressure-Volume LoopsKNOW:When the mitral and aortic valves are open and closed during each phaseWhen systole begins (B) and ends (D)When diastole begins (D) and ends (B)Diastolic filling occurs between points A and BEjection occurs between p

3、oints C and DLeft VentricularPressure-VoluLeft VentricularPressure-Volume LoopsAcute changes in preloadIncreased preload:Filling increasesSV increasesDecreased preload: Filling decreasesSV decreases*NOTE: the ventricle empties to the same end-systolic volume after either an increase or decrease in p

4、reloadLeft VentricularPressure-VoluLeft VentricularPressure-Volume LoopsLeft VentricularPressure-VoluLeft VentricularPressure-Volume LoopsCardiac tamponade Unique loopLeft VentricularPressure-VoluLeft VentricularPressure-Volume LoopsAcute changes in AfterloadIncreased afterload:Ventricle empties les

5、s completelySV decreasesIncrease in BP(shifts up and right)Decreased afterload:Ventricle empties more completelySV increasesDecrease in BP(shifts down and left)Left VentricularPressure-VoluLeft VentricularPressure-Volume LoopsLeft VentricularPressure-VoluLeft VentricularPressure-Volume LoopsAltered

6、contractilityIncreased contractility:Ventricle empties more completelySV increasesBP increases (shifts up and left)Decreased contractility:Ventricle empties less completelySV decreasesBP decreases(shifts down and right)Left VentricularPressure-VoluLeft VentricularPressure-Volume LoopsLeft Ventricula

7、rPressure-VoluLeft VentricularPressure-Volume LoopsSummary of concepts:Alterations in preload: end-diastolic volume increases or decreases, but the amount of blood in the chamber at end-systole does not changeStroke volume falls: result of either an increase in afterload or a decrease in contractili

8、ty, 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)Left VentricularPressure-VoluLeft VentricularPressure-Volume LoopsIHSSUNIQ

9、UEP-V loop is shifted to smaller volumes and larger pressures (due to outflow tract obstruction)ONLY IHSS causes this type of combined shiftLeft VentricularPressure-VoluLeft VentricularPressure-Volume LoopsChronic Aortic Stenosis(increased afterload)Concentric hypertrophy permits the LV to generate

10、greater pressureLV volumes remain about normalP-V loop shifts upwardLeft VentricularPressure-VoluLeft VentricularPressure-Volume LoopsMitral Stenosis(Decreased preload)LV filling is diminishedP-V loop reflects a decreased preloadEmptying is about normalLeft VentricularPressure-VoluLeft VentricularPr

11、essure-Volume LoopsAcute Aortic Insufficiency (regurgitation)Volume in the LV chamber increases during early diastoleP-V loop is smallNo isovolemic relaxationLeft VentricularPressure-VoluLeft VentricularPressure-Volume LoopsChronic Aortic Insufficiency(Eccentric hypertrophy)LV chamber dilatesP-V loo

12、p is large because the SV is largeNo isovolemic relaxationLeft VentricularPressure-VoluLeft VentricularPressure-Volume LoopsBe able to identify a P-V loop that shows aortic insufficiencyBe able to identify whether the loop reflects acute or chronic aortic insufficiencyLeft VentricularPressure-VoluLe

13、ft VentricularPressure-Volume LoopsAcute Mitral RegurgitationP-V loop is smallNo isovolemic contractionLeft VentricularPressure-VoluLeft VentricularPressure-Volume LoopsChronic Mitral RegurgitationLV hypertrophies (eccentric)LV chamber dilates P-V loop is large because the SV is largeNo isovolemic contractionLeft