| The left atrium modulates left ventricular filling through three components: a phase of reservoir or expansion during systole, a conduit phase during early diastole, and an active contractile component during late diastole. This active contractile component of the left atrium accounted for cardiac output by approximately 15–20%. An age related increase in LA active contractile was noted.The left atrium function and left ventricular function change is consistent.Left atrium expansion with atrial fibrillation, stroke incidence, is highly correlated,also is stroke significant predictors.Left atrium volume is also indicates an independent risk factor for death.This study aims to assesse left atrial function in the normal and the hypertension patients with different left ventricular geometrics with real-time three dimensional echocardiography technology, by measuring the left atrium volume of the different periods in cardiac cycle.This study was composed by two parts:Part 1 Changes in Left Atrial Function with Aging: Evaluation by real-time three dimensional echocardiographyObjective Using the three dimensional echocardiography to assess the effects of age and sex on LA reservoir, conduit, and booster pump function. Methods The subjects of this study were 98 normal adults .The normal were divided into 5 groups:18 to 29 years old(A group),30 to 39 years old(B group) ,40 to 49 years old(C group),50 to 59 years old(D group)and over 60 years old(E group).All people were collected full volume imaging at apical four-chamber view with real-time three dimensional.Left atrial volume curve, left atrium maximal volume(LAVmax), left atrium minimal volume(LAVmin) and left atrium presystolic volume(LAVpre) were getted with QLAB work station. Following parameters were calculated:left atrium passive emptying volume(LAVp), left atrium passive emptying fraction (LAVpEF),conduit volume (CV), left atrium active emptying volume (LAVa), left atrium active emptying fraction (LAVaEF), left atrium total emptying volume(LAVt), left atrium total emptying fraction (LAVtEF).The same way getted left ventricular maximal volume(LVmax),left ventricular minimal volume(LVmin),then calculated stroke volume (SV),left ventricular ejection fraction (LVEF)..All volumes were indexed for body surface area. The above parameters react (1) left atrium reservoir function: LAVmax LAVmin, LAVpre and LAVt; (2) left atrial booster pump function: LAVaEF LAVa and AE; (3) left atrium conduit function: CV; (4) left ventricular diastolic function: LAVp, LAVpEF and PE; (5) left ventricular systolic function: SV, LVEF.Result Left atrial function parameters (1) reservoir function:LAVmin,LAVmax increased obviously in E group than other groups ; LAVpre increased in D, E group ; LAVt had no difference between groups; (2) booster pump function:LAVa, AE increased in D, E group;LAVaEF increased in E group; (3) conduit function: CV had no difference between groups. Left ventricular function parameters (1) diastolic function:LAVpEF, PE reduced in D, E group,E group is obvious; (2) systolic function: there is no difference between the groups.Left atrial function did not vary with sex.Some parameters change with the age.A peak, LAVmax, LAVmin, LAVpre, LAVaEF, AE were positively correlated with age;E peak, E/A, LAVpEF, PE, CV negatively correlated with age.Conclusion An age related in left atrial fuction,and the functional changes before the structure.Left ventricular filling rely mainly on left ventricular diastolic in the young period,but left atrium active contraction in the old period. Left ventricular diastolic function revealed a significant age dependency. Left atrial reservoir function increased when the age is over 60 years;booster pump function increased when the age is over 50 years.Left atrial conduit trended lower with age. Left atrial function did not vary with sex.Part 2 Left atrial function in hypertension patients with different left ventricular geometrics assessed with real-time three dimensional echocardiographyObjective Using the three dimensional echocardiography to estimate left atrial mechanical function in hypertension patients with different left ventricular geometrics.Methods The subjects of this study were 94 hypertension patients and 35 normal adults (N group).Hypertension patients were divided into 4 groups: normal left ventricular geometric (A group),concentric remolding (B group) ,concentric hypertrophy (C group) and eccentric hypertrophy (D group).All people were collected full volume imaging at apical four-chamber view with real-time three dimensional.Left atrial volume curve,LAVmax,LAVmin and LAVpre were getted with QLAB work station. Following parameters were calculated:LAVp,LAVpEF,CV,LAVa,LAVaEF,LAVt,LAVtEF.The same way getted LVmax,LVmin,then calculated SV,LVEF. All volumes were indexed for body surface area. The above parameters react (1) left atrium reservoir function: LAVmax LAVmin, LAVpre and LAVt; (2) left atrial booster pump function: LAVaEF LAVa and AE; (3) left atrium conduit function: CV; (4) left ventricular diastolic function: LAVp, LAVpEF and PE; (5) left ventricular systolic function: SV, LVEF.Result LAVmax,LAVmin,LAVpre,LAVa,LVmax were greater,LAVpEF was lower in all hypertension groups than in controls (p<0.05),LAVmax,LAVmin,LAVpre increased obviously in C,D group;LAVa reduced obviously in C group;LVmax increased obviously in D group;LAVpEF decreased obviously in D group.Compared with N group,CV reduced in C,D group ; LVmin increased in B,C,D group,obviously in D group. LAVt,SV increased in C group.LVEF reduced in D group.LAVtEF,LAVaEF,LAVp were similar in all groups (p>0.05).The parameters of left atrial volume , LAVt, LAVa were positively correlated with systolic blood pressure,diastolic blood pressure,IVST, PWT, LVMI,RWT,and obviously with LVMI ; LAVpEF, CV, PE were negatively correlated with systolic blood pressure, diastolic blood pressure,IVST,PWT,LVMI, RWT, and LAVpEF, CV correlation with LVMI highest,PE correlation with PWT highest.Conclusion Left atrial function was changed with left ventricular geometric.In normal left ventricular geometric and concentric remolding,left ventricular diastolic function damaged.Left atrial enhanced atrial reservoir and booster pump function to ensure left ventricular filling,but left ventricular filled mainly from left ventricular diastolic.In concentric hypertrophy and eccentric hypertrophy,left ventricular diastolic function severely damaged,left ventricular filling relied mainly on the left atrial reservoir and booster pump function.When left ventricular appeared decompensated,left atrial function did not appear decompensated. |
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