| [BACKGROUND]The mitral valve is a "one-way door" occupying the left atrioventricular groove, ensuring unidirectional diastolic flow of blood from the left atrium into the relaxed left ventricle. During systole, a precise and complex interaction of anatomical components and ventricular pressure results in mitral valve closure. The unique design of the mitral valve complex includes the left ventricular myocardium, subvalvular apparatus (including papillary muscles and chordae tendineae), mitral annulus, mitral valve leaflets, and the left atrium. The underlying pathological changes of these component parts will lead to mitral regurgitation (MR). Carpentier et al. were the first to emphasize the importance of making a distinction between the disease causing mitral regurgitation, the lesions and the valvular dysfunction resulting from the mitral valve disease. Carpentier and colleagues classified mitral valve dysfunctions based on the closing motion of the margin of the leaflets in relation to an imaginary line representing the level of the annular plane. As described in this classification, type Ⅰ MR is characterized as normal leaflet motion but with annular dilatation or leaflet perforation; type Ⅱ dysfunctions imply excess motion of the leaflet margin above the plane of the annulus, are related to leaflet prolapse and may be caused by myxomatous disease, such as chord rupture or elongation, or by papillary muscle rupture or elongation; and type Ⅲ lesions are caused by restricted leaflet motion resulting in coaptation below the annular plane. Type Ⅲ was later divided, with type Ⅲa designating restricted leaflet motion in systole and diastole, as typically caused by rheumatic valve disease with normal ventricular motion and subvalvular fibrosis and calcification; and type Ⅲb implying restricted leaflet motion that occurs only in systole, is the result of ventricular remodeling, with the primary lesion being leaflet tethering due to papillary muscle displacement.Differentiation into the specific etiological mechanism and physiopathological process that result in the mitral regurgitation have different surgical planning and assessment. In contrast with the almost universal prevalence of rheumatic lesions were the mainstay of surgical treatment of acquired heart disease observed in the past, now the great majority of surgery on the mitral valve is performed for insufficiency secondary to degenerative disease or, less often, secondary to ischemic disease. Three principle goals of MV repair were introduced by Carpentier:Stabilisation of the annulus with the retention of an adequately sized mitral orifice, restoration of physiological leaflet motion and recreation of a sufficient line of coaptation. So, mitral valve repair, as preserved left ventricular function and subvalvular apparatus to a certain degree, has been demonstrated to be superior to mitral valve replacement with improved post-operative survival rates and excellent late durability, low rates of thromboembolism, resistance to endocarditis, and no need for anticoagulation in the majority of patients. As cardiovascular specialists move toward more liberal surgical referral of asymptomatic patients with severe mitral valve regurgitation, the determination of likelihood of a mitral valve repair as opposed to a mitral valve replacement has taken on additional significance. Indeed, the current American College of Cardiology/American Heart Association Guidelines for Management of Patients With Valvular Heart Disease emphasize that an asymptomatic patient with chronic, severe mitral regurgitation should only be referred to experienced surgical centers where the likelihood of successful repair, without residual mitral regurgitation, is more than90%. Now, the Surgical repair is the gold standard therapy for mitral valve insufficiency, and numerous techniques have been described. Proposed techniques are ring annuloplasty, chordae transfer and resection of the prolapsed segment. Lately, the implantation of neochordae and the loop-technique has been established and is the preferred technique in many centres. Various methods that use transcatheter approaches to mitral valve repair—without cardiopulmonary bypass—are currently in various stages of clinical application, while others are still in an experimental stage. But the complexity of the mitral valve operation may be difficult, which leads to generally low rates of repair. In a recent review, only44.3%of patients in the United States who required mitral valve surgery for mitral regurgitation received a mitral valve repair, and in the Euro Heart Survey, repair rates were similarly low (46.5%).Echocardiography is an essential tool in managing patients with mitral regurgitation. It allows identification and precise summation of anatomic lesions that lead to valve dysfunction. Advances in echocardiographic techniques have provided a better understanding of the geometric and functional characteristics of the mitral valve complex, including the identification of characteristic landmarks such as the triangle of coaptation, the length and depth of coaptation, and the coaptation point. Identification of these landmarks enables a detailed evaluation of normal and abnormal valve function and the definition of the mechanism of mitral regurgitation, thereby permitting competent and durable valve restoration by means of appropriate surgical intervention. Traditional Two-dimensional transthoracic echocardiography provides the backbone for the structural evaluation of the mitral valve. Doppler methods assist in the hemodynamic evaluation of normal and abnormal mitral valve function. However, the main limitations of this system are the influence by the acoustic window conditions, chest wall movement, narrow intercostal space and many objective factors in the clinical application. The technical advance in cardiology has provided marked improvement in the conservative treatment of complex physiopathological lesions of the mitral valve. Interventional and surgical procedures on the mitral valve demand precise and sophisticated imaging for guidance and support. There is already a substantial body of literature demonstrating the added value of three-dimensional over two-dimensional echocardiography in the evaluation of patients with mitral valve disease. Real-time three-dimensional transesophageal echocardiography provides a more authentic representation of the mitral valve structure, function, and pathology compared with traditional Two-dimensional transthoracic echocardiography. The spatial relationships of the components of the mitral valve complex are facilitated by the use of three-dimensional transesophageal echocardiography. The sonographer can use the Wide-Sector Focused Format to obtain a truncated pyramidal data set by selecting a region of interest that includes the mitral valve, the aortic valve, and the left atrial appendage. The aortic valve is used as reference, and when rotated to about12o’clock on an imaginary clock face, one obtains an anatomic view of the mitral valve with a perspective similar to that observed by a cardiac surgeon inspecting the mitral valve from the left atrium. Similar to the view the surgeon has when positioned on the patient’s right side when examining the mitral valve through the opened left atrium. Mitral valve quantification software (MVQ) was used to quantitatively analyze mitral valve:area of mitral valve annulus in project plane, area of anterior and posterior leaflets, perimeter of mitral valve annulus, maximal tenting height and aortic orifice to mitral plane angle. The image was tilted to the left and right to compensate for the saddle shape of the mitral valve and detect prolapsing scallops, chordal ruptures. Volumetric quantitative analysis of the mitral valve can reliably predict repair complexity, across a spectrum of aetiologies, lesions and leaflet dysfunctions.However, at present there is no domestic data about the rate of mitral valve repair for mitral prolapsed. The influencing factors and early-middle stage outcomes of the mitral valvuloplasty are need further study. Therefore, the purpose of this study is to analysis the influencing factors value of mitral valve repair for mitral prolapsed and the changes of left ventricular structure and function after mitral valvuloplasty.[OBJECTS AND METHODS]1. The object and sub-groups:According to the tracking system of medical record,464patients (311males and152females; age range,13-82years; mean age,51.18±14.95years)with mitral regurgitation who were scheduled for mitral valve surgery because of mitral prolapse from June2008to May2012in GuangDong Provincial Cardiovascular Institute were enrolled in this study. The exclusion criterions were contraindication to TEE, infectious diseases, congenital heart disease and rheumatic heart disease. Mitral valve replacement was performed on274cases and mitral valvuloplasty was performed on189cases.9patients underwent mitral valve replacement with mechanical prosthesis valve for sever mitral regurgitation during the post-repair assessment.9patients had concurrent coronary artery bypass grafts and2cases with Bentall operation. There was no perioperative died. Patients were divided into three groups according to performing three-dimensional transesophageal echocardiography in pre-operation or not(3D TEE、2D TTE), the location of mitral prolapsed(A-anterior leaflet prolapsed, P-posterior leaflet prolapsed, AP-anterior leaflet and posterior leaflet were involved simultaneously) and the operations’ skill level(A-underwent mitral valve repair>=100cases, B-underwent mitral valve repair between50to100cases, C-underwent mitral valve repair<=50cases).2. Pre-operation echocardiography2.1Two-dimensional transthoracic Echocardiographic images were obtained in all patients in a steep left lateral decubitus position, with the patient’s left arm extended over the head. The transthoracic echocardiographic examination was conducted following standard clinical protocol, which is based on the American Society of Echocardiography/Society of Cardiovascular Anesthesiologists guidelines. The mitral valve was imaged in the parasternal long axis (PLAX) view, short-axis view, apical4-chamber and followed by gradual advancement of the probe to acquire the structural of the mitral valve. Mitral valve prolapse was defined as the displacement of leaflet tissue above the mitral annular plane into the left atrium by at least2mm during systole, considering the annular saddle shape. The two-dimensional echocardiographic signs evaluated for detecting a flail valve as:(1) systolic inversion of the mitral leaflets into the left atrium;(2) systolic whipping of the mitral leaflets or presence of floating apical chordate. Doppler methods assist in the hemodynamic evaluation of the degree of mitral regurgitation according to the Helmcke’s principle.2.2Lidocaine (2%) throat spray was used to alleviate discomfort during transesophageal echocardiography. Real-time three-dimensional transesophageal echocardiographic images were obtained in149subjects in the left lateral decubitus position by an experienced sonographer using an x7-2t transducer on a Philips iE33ultrasound machine (Philips Medical Systems, Andover, MA), which has multiplane2D, biplane2D, Doppler imaging, and Real-time three-dimension capabilities. Synchronized electrocardiograms were recorded and displayed on the images. The views were obtained by advancing and slightly retroflexing the endoscope tip to the mid-esophageal position(30-40cm from the incisors) to direct the imaging sector. The systematic examination consists of standard mid-esophageal four-chamber, bicommissural, two-chamber, and long-axis views and the transgastric basal short-axis view. The mitral valve was examined in multiple cross-sectional views. They were optimized to display the entire MV taking care to optimize detail and image quality by adjusting the sector depth, width, lateral gain, and transducer frequency settings. Starting in the midesophageal4-chamber view,2D images were optimized in the "x-plane" mode, featuring2orthogonal2D sections, before RT3DTEE recordings were acquired in the3D zoom mode. To displays a selectable pyramidal volume that can be focused to capture the MV with maximum resolution, the size of the3D echocardiographic sample volume was defined by adjusting the depth position, width, and height using a trackball and dials. Three-dimensional interpretation was performed on3D zoom recordings using Qlab7.1software (Philips Medical Systems). An initial en-face view of the left atrial perspective of the mitral valve was used for the primary orientation and adjustment of gain and color schemes. The image was rotated to resemble the surgical orientation, with the aorta at12o’clock. The image was tilted to the left and right to compensate for the saddle shape of the mitral valve and detect prolapsing scallops and chordal ruptures.3D echocardiographic reconstruction images can show an en-face view of the prolapsing scallops with the leaflet surface area mapped by the green gridlines the mapped surface area of the prolapsing leaflets, respectively. Evaluating the predominant prolapse as well as all prolapsing scallops according to the nomenclature to "segment" the leaflet ascribed by Carpentier. A detailed volumetric assessment of the mitral valve such as prolapsing height and anterior leaflet surface area can be obtained by using QLAB. Mitral valve prolapsed and chorda rupture were defined as two-dimensional transthoracic Echocardiographic standard.3. Retrospective analysis the outcomes of transthoracic echocardiograph in the postoperative follow-up process:There were189patients undergo mitral valve repair for mitral prolapse and7patientswere lost to follow-up.182cases underwent analysis of early-middle stage outcomes. The following parameters were used for analysis:left atrial diameter (LAD)、left ventricular end-diastolic diameter (LVEDD)、left ventricular end-systolic diameter (LVESD)、left ventricular ejection fraction (LVEF) and the degree of residual mitral regurgitation(MR).4. Statistical analysis:Statistical analysis was performed using the SPSS statistical program (Version13.0). Results are expressed as the mean±standard deviation. The rate of mitral valve repair for every group was compared using the Chi-Square test. The parameters between pre-and postoperative echocardiography were compared using the paired t-test. The degree of residual mitral regurgitation between pre-and postoperative echocardiography was compared using Wilcoxon signed-rank test. In multivariate analysis independent factors correlated with the rate of mitral valve repair using a Logistic-regression model. Statistical significance was specified as P<0.05.[RESULTS]1. For the464patients, the total rate of mitral valve repair was40.8%.2. Subgroup analysis:2.1In3D TEE-group with149patients,85patients underwent mitral valve repair successfully and5unsuccessfully, the rate of mitral valve repair was60.4%; In2D TTE-group with315patients,95patients underwent mitral valve repair successfully and4unsuccessfully, the rate of mitral valve repair was31.4%. There was significant difference between echocardiography subgroups as the rate of mitral valve repair was higher in3D-TEE group than in2D TTE.(60.4%vs31.5%,X2=34.87,P=0.000).2.2In anterior leaflet group with116patients,38underwent mitral valve repair successfully and no unsuccessfully, the rate of mitral valve repair was32.8%. In posterior leaflet group with229patients,106underwent mitral valve repair successfully and6unsuccessfully, the rate of mitral valve repair was48.9%. In double leaflet group with118patients,36underwent mitral valve repair successfully and3unsuccessfully, the rate of mitral valve repair was33.1%. There were significant differences between leaflet subgroups as the rate of mitral valve repair was higher in posterior leaflet group than in the anterior leaflet and double leaflet group.(48.9%vs32.8%vs33.7%,X2=12.27, P=0.002).2.3In surgeon A group with184patients,102underwent mitral valve repair successfully and6unsuccessfully, the rate of mitral valve repair was58.7%. in surgeon group B with25patients,15underwent mitral valve repair successfully and no unsuccessfully, the rate of mitral valve repair was60%. In surgeon group C with254patients,63underwent mitral valve repair successfully and3unsuccessfully, the rate of mitral valve repair was26%. There were significant differences between surgeon subgroups as in the group witch operation’s skill level was higher, the rate of mitral valve repair was higher.(58.7%vs60.0%vs26.0%,X2=51.28, P=0.000).3. Multiple logistic-regression analysis identified the sex was unrelated to the rate of mitral valve repair (P=0.18), while age<55years (P=0.000), performing3D TEE preoperation (P=0.002), mitral posterior leaflet prolapse (P=0.000) and experienced operations (P=0.001) correlated significantly to the rate of mitral valve repair.4. Postoperative two-dimensional echocardiography and recurrent mitral regurgitation(MR)4.1182patients who undergo mitral valve repair completed Follow-up within the first week after surgery. Left ventricular end-diastolic diameter decreased from57.32±6.21mm, preoperatively to45.68±5.52mm, postoperatively (t=25.278,P=0.000) and LVESD decreased from34.51±5.91mm, preoperatively to29.66±5.30mm, postoperatively (t=11.546,.P=0.000). The LAD reduced from45.91±8.58mm to34.85±6.79mm (t=20.041,.P=0.000). The LVEF reduced from67.02±6.28mm to61.75±7.17mm (t=8.332,P=0.000). The parameters were significant difference between pre-and postoperative. There were11cases had moderate MR and171had severe MR, preoperatively46had mild MR and1had moderate MR. There was significant difference between pre-and postoperative (Z=-11.898,P=0.000).4.2135patients completed Follow-up in the3months after surgery. LAD and LVEF was37.08±6.76mm、64.80±6.47%respectively. There were significant differences between preoperative and1week after operation (t=13.536,P=0.000; t=3.923,P=0.000). LVEDD and LVESD was45.29±4.79mm and28.43±4.88mm respectively. There was significant difference compared with preoperative (t=23.240,P=0.000;t=12.271,P=0.000), as no significant difference with1week after operation (t=-0.071,P=0.944; t=1.722,P=0.087). There were27cases had mild MR. There were significant differences between preoperative (Z=-14.321,P=0.001) and1week after operation (Z=-4.359,P=0.018)4.363patients completed Follow-up in the12months after surgery. LAD and LVEF was37.37±6.85mm、64.31±5.67%respectively. There were significant differences between preoperative t=11.046,P=0.000;t=3.594,P=0.001)and1week after operation (t=-3.166,P=0.002;t=-1.701,P=0.045), as no significant difference with3months after operation (t=-0.672,P=0.504; t=1.493,P=0.141). LVEDD and LVESD was45.58±4.37mm and28.58±4.09mm respectively. There was significant difference compared with preoperative (t=16.299,P=0.000;t=9.225,P=0.000), and no significant difference with1week (t=-0.656,P=0.514;t=0.571,P=0.570)and3months after operation (t=-0.600,P=0.551; t=-0.297,P=0.768). There were19cases had mild MR. There were significant differences between preoperative (Z=-17.852,P=0.000) and1week after operation (Z=-5.677,P=0.004), as no significant difference with3months after operation (Z=2.143,P=0.097)[CONCLUSIONS]1. Multiple logistic-regression analysis identified the sex was unrelated to the rate of mitral valve repair (P>0.05), while age<55years, performing3D TEE preoperation, mitral posterior leaflet prolapse and experienced operations correlated significantly to the rate of mitral valve repair (P<0.05).2. Three-dimensional transesophageal echocardiography can evaluate the location of mitral prolapse accurately, guiding surgeon decision-making according to their own skill level and the actual leaflet pathology, consequently improve the rate of mitral valve repair for mitral prolapse.3. Mitral valve repair can fundamentally solve the pathological injury of mitral apparatus, reduce the left ventricular volume overload and correct hemodynamic disorder. It is a safe and effective method for not only make a reconstruction of left ventricular structure in a short term, but also remain relatively stable in the postoperative follow-up process. |
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