ventricular pressurevolume loops左心室压力容积环课件_1

Left Ventricular Pressure-Volume Loops Left VentricularLeft Ventricular Pressure-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 Left VentricularLeft Ventricular Pressure-Volume LoopsPressure-Volume Loops KNOWKNOW: : 1.1. When the mitral and aortic valves are open When the mitral and aortic valves are open and closed during each phaseand closed during each phase 2.2. 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 B 5.5. Ejection occurs between points C and DEjection occurs between points C and D Left VentricularLeft Ventricular Pressure-Volume LoopsPressure-Volume Loops 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 endempties to the same end -systolic volume after -systolic volume after either an increase or either an increase or decrease in preloaddecrease in preload Left VentricularLeft Ventricular Pressure-Volume LoopsPressure-Volume Loops Left VentricularLeft Ventricular Pressure-Volume LoopsPressure-Volume Loops Cardiac tamponade Cardiac tamponade Unique loopUnique loop Left VentricularLeft Ventricular Pressure-Volume LoopsPressure-Volume Loops 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) Left VentricularLeft Ventricular Pressure-Volume LoopsPressure-Volume Loops Left VentricularLeft Ventricular Pressure-Volume LoopsPressure-Volume Loops 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) DecreaseDecreased d contractilitycontractility: : Ventricle empties less Ventricle empties less completelycompletely SV decreasesSV decreases BP decreasesBP decreases (shifts down and right)(shifts down and right) Left VentricularLeft Ventricular Pressure-Volume LoopsPressure-Volume Loops Left VentricularLeft Ventricular Pressure-Volume LoopsPressure-Volume Loops 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 enddecreases, but the amount of blood in the chamber at end -systole does not change-systole does not change Stroke volume fallsStroke volume falls: result of either an increase in : result of either an increase in afterload or a decrease in contractility, the volume of afterload or a decrease in contractility, the volume of blood in the LV chamber increases (chamber dilates)blood in the LV 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) Left VentricularLeft Ventricular Pressure-Volume LoopsPressure-Volume Loops 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 Left VentricularLeft Ventricular Pressure-Volume LoopsPressure-Volume Loops 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 Left VentricularLeft Ventricular Pressure-Volume LoopsPressure-Volume Loops 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 Left VentricularLeft Ventricular Pressure-Volume LoopsPressure-Volume Loops Acute Aortic Acute Aortic InsufficiencyInsufficiency (regurgitation)(regurgitation) Volume in the LV Volume in the LV chamber increases during chamber increases during early diastoleearly diastole P-V loop is smallP-V loop is small No isovolemic relaxationNo isovolemic relaxation Left VentricularLeft Ventricular Pressure-Volume LoopsPressure-Volume Loops 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 Left VentricularLeft Ventricular Pressure-Volume LoopsPressure-Volume Loops Be able to identify a P-V loop that shows Be able to identify a P-V loop that shows aortic insufficiencyaortic insufficiency 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 Left VentricularLeft Ventricular Pressure-Volume LoopsPressure-Volume Loops Acute Mitral Acute Mitral RegurgitationRegurgitation P-V loop is smallP-V loop is small No isovolemic co