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

Left Ventricular Pressure-Volume Loops

Left VentricularLeft VentricularPressure-Volume LoopsPressure-Volume Loops

• Pressure-volume loop Pressure-volume loop plots LV pressure against plots LV pressure against LV volume through one LV volume through one complete cardiac cyclecomplete cardiac cycle

• Factors affecting:Factors affecting:– Preload Preload – Afterload Afterload – ContractilityContractility– IHSSIHSS– Valvular problemsValvular problems


• KNOWKNOW::1.1. When the mitral and aortic valves are open and When the mitral and aortic valves are open and

closed during each phaseclosed during each phase2.2. When systole begins (B) and ends (D)When systole begins (B) and ends (D)3.3. When diastole begins (D) and ends (B)When diastole begins (D) and ends (B)4.4. Diastolic filling occurs between points A and BDiastolic filling occurs between points A and B5.5. Ejection occurs between points C and DEjection occurs between points C and D


• Acute changes in Acute changes in preloadpreload– Increased preloadIncreased preload::• Filling increasesFilling increases• SV increasesSV increases

– Decreased preloadDecreased preload: : • Filling decreasesFilling decreases• SV decreasesSV decreases

*NOTE: the ventricle *NOTE: the ventricle empties to the same empties to the same end-systolic volume after end-systolic volume after either an increase or either an increase or decrease in preloaddecrease in preload



• Cardiac tamponade Cardiac tamponade – Unique loopUnique loop


• Acute changes in Acute changes in AfterloadAfterload– Increased afterloadIncreased afterload::• Ventricle empties less Ventricle empties less

completelycompletely• SV decreasesSV decreases• Increase in BPIncrease in BP(shifts up and right)(shifts up and right)

– Decreased afterloadDecreased afterload::• Ventricle empties Ventricle empties

more completelymore completely• SV increasesSV increases• Decrease in BPDecrease in BP(shifts down and left)(shifts down and left)



• Altered contractilityAltered contractility– Increased Increased

contractilitycontractility::• Ventricle empties Ventricle empties

more completelymore completely• SV increasesSV increases• BP increasesBP increases

(shifts up and left)(shifts up and left)

– DecreaseDecreasedd contractilitycontractility::• Ventricle empties less Ventricle empties less

completelycompletely• SV decreasesSV decreases• BP decreasesBP decreases(shifts down and right)(shifts down and right)



• Summary of concepts:Summary of concepts:– Alterations in preloadAlterations in preload: end-diastolic volume increases or : end-diastolic volume increases or

decreases, but the amount of blood in the chamber at decreases, but the amount of blood in the chamber at end-systole does not changeend-systole does not change

– Stroke volume fallsStroke volume falls: result of either an increase in afterload : result of either an increase in afterload or a decrease in contractility, the volume of blood in the LV or a decrease in contractility, the volume of blood in the LV chamber increases (chamber dilates)chamber increases (chamber dilates)

– Stroke volume increasesStroke volume increases: result of a decrease in afterload : result of a decrease in afterload or an increase in contractility, the volume of blood in the or an increase in contractility, the volume of blood in the LV chamber decreases (chamber shrinks)LV chamber decreases (chamber shrinks)


• IHSSIHSS– UNIQUEUNIQUE– P-V loop is shifted to P-V loop is shifted to

smaller volumessmaller volumes and and larger pressureslarger pressures (due to (due to outflow tract obstruction)outflow tract obstruction)• ONLY IHSSONLY IHSS causes this type causes this type

of combined shiftof combined shift


• Chronic Aortic StenosisChronic Aortic Stenosis(increased afterload)(increased afterload)– Concentric hypertrophy Concentric hypertrophy

permits the LV to permits the LV to generate greater pressuregenerate greater pressure

– LV LV volumesvolumes remain about remain about normalnormal

– P-V loop shifts upwardP-V loop shifts upward


• Mitral StenosisMitral Stenosis(Decreased preload)(Decreased preload)– LV filling is diminishedLV filling is diminished– P-V loop reflects a P-V loop reflects a

decreased preloaddecreased preload– Emptying is about normalEmptying is about normal


• Acute Aortic InsufficiencyAcute Aortic Insufficiency (regurgitation)(regurgitation)– Volume in the LV chamber Volume in the LV chamber

increases during early increases during early diastolediastole

– P-V loop is smallP-V loop is small– No isovolemic relaxationNo isovolemic relaxation


• Chronic Aortic Chronic Aortic InsufficiencyInsufficiency

(Eccentric hypertrophy)(Eccentric hypertrophy)– LV chamber dilatesLV chamber dilates– P-V loop is large because P-V loop is large because

the SV is largethe SV is large– No isovolemic relaxationNo isovolemic relaxation


• Be able to identify a P-V loop that shows aortic Be able to identify a P-V loop that shows aortic insufficiencyinsufficiency

• Be able to identify whether the loop reflects Be able to identify whether the loop reflects acute or chronic aortic insufficiencyacute or chronic aortic insufficiency


• Acute Mitral Acute Mitral RegurgitationRegurgitation– P-V loop is smallP-V loop is small– No isovolemic contractionNo isovolemic contraction


• Chronic Mitral Chronic Mitral RegurgitationRegurgitation– LV hypertrophies LV hypertrophies

(eccentric)(eccentric)– LV chamber dilates LV chamber dilates – P-V loop is large because P-V loop is large because

the SV is largethe SV is large– No isovolemic contractionNo isovolemic contraction


• A = NormalA = Normal• B = Mitral stenosisB = Mitral stenosis• C = Aortic stenosisC = Aortic stenosis• D = mitral D = mitral

regurgitation regurgitation (chronic)(chronic)

• E = aortic E = aortic regurgitation regurgitation (chronic)(chronic)

Documents

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