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1、Left Ventricular Pressure-Volume Loops,Left VentricularPressure-Volume Loops,Pressure-volume loop plots LV pressure against LV volume through one complete cardiac cycle,Factors affecting:Preload Afterload ContractilityIHSSValvular problems,Left VentricularPressure-Volume Loops,KNOW:When the mitral a
2、nd 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 points C and D,Left VentricularPressure-Volume Loops,Acute changes in preloadIncreased preload:Filling incre
3、asesSV increasesDecreased preload:Filling decreasesSV decreases,*NOTE:the ventricle empties to the same end-systolic volume after either an increase or decrease in preload,Left VentricularPressure-Volume Loops,Left VentricularPressure-Volume Loops,Cardiac tamponade Unique loop,Left VentricularPressu
4、re-Volume Loops,Acute changes in AfterloadIncreased afterload:Ventricle empties less completelySV decreasesIncrease in BP(shifts up and right),Decreased afterload:Ventricle empties more completelySV increasesDecrease in BP(shifts down and left),Left VentricularPressure-Volume Loops,Left VentricularP
5、ressure-Volume Loops,Altered 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-Volume Loops,Left Ventricu
6、larPressure-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 changeStroke volume falls:result of either an increase in afterload or a decrease in contractility,the volume of blood in the
7、 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-Volume Loops,IHSSUNIQUEP-V loop is shifted to smaller volumes and larger pressures
8、(due to outflow tract obstruction)ONLY IHSS causes this type of combined shift,Left VentricularPressure-Volume Loops,Chronic Aortic Stenosis(increased afterload)Concentric hypertrophy permits the LV to generate greater pressureLV volumes remain about normalP-V loop shifts upward,Left VentricularPres
9、sure-Volume Loops,Mitral Stenosis(Decreased preload)LV filling is diminishedP-V loop reflects a decreased preloadEmptying is about normal,Left VentricularPressure-Volume Loops,Acute Aortic Insufficiency(regurgitation)Volume in the LV chamber increases during early diastoleP-V loop is smallNo isovole
10、mic relaxation,Left VentricularPressure-Volume Loops,Chronic Aortic Insufficiency(Eccentric hypertrophy)LV chamber dilatesP-V loop is large because the SV is largeNo isovolemic relaxation,Left VentricularPressure-Volume Loops,Be able to identify a P-V loop that shows aortic insufficiencyBe able to i
11、dentify whether the loop reflects acute or chronic aortic insufficiency,Left VentricularPressure-Volume Loops,Acute Mitral RegurgitationP-V loop is smallNo isovolemic contraction,Left VentricularPressure-Volume Loops,Chronic Mitral RegurgitationLV hypertrophies(eccentric)LV chamber dilates P-V loop is large because the SV is largeNo isovolemic contraction,Left VentricularPressure-Volume Loops,A=NormalB=Mitral stenosisC=Aortic stenosisD=mitral regurgitation(chronic)E=aortic regurgitation(chronic),
