| Background and objectiveRheumatic mitral regurgitation(RMR) was a common kind of cardiac disease.Mitral valve was a very fine complex structure,normal mitral valve device includes(pre-and post-flap valve),valve ring,the valve under-devices(papillary muscles and tendons).Papillary muscles attached to the wall and the peripheral valve connected to left atrial cardiac mitral valve constitute to the whole.Opening and closing of the mitral valve rely on the structure and function of each element's integrity,each part with any abnormals could result to mitral regurgitation.These patients usually experienced a long phase of potential benign period,once having symptoms,they usually need to surgical treatment.At present,the mitral valve replacement(MVR) was the main method.The left ventricular systolic function could be improved in the majority of patients who had mitral valve replacement,however, the function of them who have severe symptoms rectify the haemodynamics disorder could not be improved through MVR,even could be deteriorated.It was very important to choose surgical time before the left ventricular systolic function decline. It was urgently to need a new independent index to assess the left ventricular function accurately,which had a very important clinical value to assess the changes of left ventricular systolic function. The tradition echocardiogram index:ejection fraction(EF) cannot be used to accurately evaluate Left ventricular systolic function with the patients of MR who underwent left ventricular volume pre-loaded,so the accuracy of ejection fraction was decline,researchers reported some indexs to evaluate left ventricular systolic function since long times ago,for example,end-systolic volume(ESV),left ventricular end-systolic diameter(ESD),left ventricular end-systolic volume index(ESVI),left ventricular end-diastolic volume index(EDVI),et al.However,in the certain extent, they were effected by the pre-and post-load,which could not be assessed the left ventricular systolic function of patients with RMR objectively and accurately.Until Sagawa proposed the left ventricular end-systolic elastance(Ees),which was based on the principle of end-systolic pressure volume curve,was a more accurate method than before to evaluate the left ventricular systolic function by the current theory.Not only Ees accurately reflected the left ventricular systolic function but also avoided the influent of pre-load of cardia,which was measured by Shishido with invasive method.However,the clinical application of Ees was limited,because of the complicated measurement and altering load level of the cardia.Based on this situation, single-beat end-systolic elastance(Ees-s) was raised by scholars as a new index, which significantly correlated by Ees,it can be used as an indicator of the determination of appropriate timing of operation and the estimation of prognosis proved by clinical and animal experiments,clinical research about this new method was rare.Therefore,we design this subject to assess the left ventricular systolic function of 100 patients with Rheumatic mitral regurgitation(RMR) by using pulsed wave imaging(PWI) and doppler tissue imaging(DTI).The purpose of this subject were:1.To evaluate the value of Ees-s in detecting the left ventricular contractile function in patients with RMR.2.To explore the use of preoperative values of Ees-s which can determine the timing of MVR and the prognosis of patients with the guidance of RMR clinical significance.Materials and methods:Thirty normal subjects(18 women,12 male,29 years～58 years old,46±10 years old on average;one hundred patients with RMR(68 women,32 male,,29 years～59 years old,46±13 years old on average),preoperative left ventricular ejection fraction(EF) 51%～70%,(56±7)%on average,The selected subjects which were divided into mild,moderate and severe group according to the ratio of maximal regurgitation jet area(RJA)to left atrium area(LAA)(mild ratio＜20%,moderate ratio 20%～40%,severe ratio＞40%),cases of mild,moderate and severe group respectively were 20,20,40,groupⅠ(33 cases) were respectively selected from moderate and severe groups,and groupⅡwere the rest cases,patients who were on operation in groupⅠwill be divide into two groups in accordance with the EF value, EF of one group is less than 50%and EF of the other group is more than or equal to 50%,12 cases who were picked up from groupsⅠ,Ⅱto carry out analysis of cardiac pathology;all the above MR cardiac function in patients with NYHA classification gradeⅠtoⅢ,with chest X-ray,electrocardiogram,echocardiography examination to exclude other cardiopulmonary disorders.All echo cardio graphic examinations were undertaken with the use of vivid7(GE Vingmed ultrasound)cardiac ultrasound scanner and 2.0-4.0MHz transducer.This machine was equipped with quantitatively analysis image and post-processing software at the same time.Measurement indexes including:Left ventricular stroke volume(SV) and left ventricular ejection fraction (EF) were measured by Biplane Simpson method;(2)On the PWI conditions, pre-ejection period of left ventricular(PEP),ejection time(ET) were measured in the standard apical five-chamber view of aortic valve blood flow spectrum;(3) On the DTI conditions,isovolumic contraction time(ICT) and isovolumic relaxation time(IRT) were measured in the apical four-chamber view of posterior septum of mitral valve points;(4) single-beat end-systolic elastance(Ees-s,mm Hg/ml)=[DBP -0.9×SBP+a×(DBP-EDP)×ET/PEP]/SV,a=1.717×EF+0.022,EDP=26.8×(ICT/IRT)+0.1.All the indexes were recorded by three cardiac cycles.Every effort was made to align the pulsed wave cursor so that the Doppler angle of incidence was as closet 0 as possible to the direction of motion of the mitral annulus were measured Results:1 Compared with control and mild RMR groups,the Ees-s values of moderate and severe RMR groups showed significant statistical differences(P＜0.05).There were significant differences between moderate and severe RMR groups.However, significant differences in the Ees-s values were hardly observed between the control and mild RMR groups(P＞0.05).Although there were differences among Mild, moderate and severe group of patients with EF values RMR,but there was no significant statistical differences2 Preoperative Ees-s value of moderate and severe RMR groups were correlated significantly with postoperative(six months later) ejection fraction(EF) (r=0.849,P＜0.001).3 Preoperative Ees-s less than or equal to 1.0mmHg/ml showed a sensitivity of 85%and a specificity of 82%for predicting EF less than 50%after surgery.4 GroupⅡpatients with RMR were forecasting analyzed,the consequences showed that the accuracy of their EF less than 50%is 75%when preoperative Ees-s less than or equal to 1.0 mm Hg / ml and the accuracy more than 50%was 83% when preoperative Ees-s more than 1.0 mm Hg / ml.5 RMR preoperative Ees-s value and the degree of myocardial fibrosis were highly negatively correlated with the correlation coefficient(r=-0.622,P＜0.05).Conclusions:1.Ees-s of RMR was more accurate than EF in pre-operative changes of left ventricular systolic function,the more serious of regurgitation,the lower of Ees-s,and the degree of myocardial fibrosis were highly correlated with left ventricular systolic function and prognosis.2.After corrected by the abnormal hemodynamics through MVR,the left ventricular systolic function which preoperative Ees-s was more than 1.0 mm Hg / ml return to normal in six months by the majority of the patients with RMR,the prognosis of others which preoperative Ees-s less than or equal to 1.0 mm Hg / ml was poor at the same time.This situation suggest that preoperative Ees-s which equal to 1.0 mm Hg / ml can be used as the reference of threshold to choose surgery.3.The Ees-s which was measured by PWI and DTI technology had a very important significance in the accurate judgement of preoperative left ventricular systolic function and the appropriate timing that selected the operation and the prognosis before MVR. |
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