nghiên cứu một số thông số huyết động và chức năng tim bằng siêu âm doppler ở bệnh nhân phẫu thuật thay van hai lá sorin bicarbon bản tóm tắt tiếng anh

1 INTRODUCTION The necessaty of the thesis Mitral valve replacement is the last choice for treating mitral valve diseases if the valve lesions are too severe for preservation In VietNam, valve replacement surgery has been carried out for more than 10 years, but the number of the patients receiving valve prostheses has incessingly increased The number of valve replacement operation actually has reached 100 cases per month, among which, nearly a half are single mitral valve However well prosthetic valves have been improved, patients risk many complications: thrombosis, infective endocarditis, prosthetic degeneration,…Therefore, these patients need to be followed up periodically to find out these complications as early as possible Echocardiography is an established technique for postoperative routine serial assessment of hemodynamics, ventricular function as well as valve operation Around the world, there have been many studies on prosthetic valve operation as well as on evaluating the postoperative hemodynamics and cardiac function changes by echocardiography In our country, there are a few previous studies on normally functioning prostheses using mainly transthoracic Doppler echocardiography We have not seen any studies using transesophageal echocardiography to assess the activity of the prosthetic valve Therefore, to study this problem is topical, scientific and helpful to cardiologists in clinical practice The significance of topics Heart valve replacement surgery is done more and more now This is an effective treatment to improve symptoms and survival of patients Hemodynamics has been improved, pulmonary pressure and heart failure have been reduced in the majority of patients However, some patients may also manifest heart failure as well as the complications of prosthetic valve Echocardiography plays an important role and is one of the major techniques for monitoring patients Echocardiography research on outcome after prosthetic valve replacement is really meaningful for prognosis and monitoring patients after surgery Objectives of the study - To study the changes of hemodynamics and cardiac function after surgical mitral valve replacement with Sorin Bicarbon valve - To evaluate the normally functioning and complications (if any) of prosthetic mitral valve Sorin Bicarbon by transthoracic and transesophageal echocardiography Structure The thesis consists of 105 pages (excluding appendices and references) with main chapters: Introduction - pages , Chapter Overview 28 pages, Chapter - Subjects and Methods 16 pages, Chapter - Research Results 31page, Chapter - Discussion 25 pages, Conclusions and Recommendations - pages Thesis has 37 tables, diagrams, 26 illustrations, 149 references, including 33 Vietnamese and 116 English and French documents Chapter OVERVIEW 1.1.Mitral valve diseases and the treatment 1.1.1 Causes and pathophysiology changes in mitral diseases The mitral diseases include stenosis, regurgitation, and the combination of stenosis and regurgitation A common cause is postrhumatism Other causes may be degeneration, annular calcification, infective endocarditis Mitral stenosis increases the average pressure in the left atrium, and if severe enough, it leads to secondary pulmonary hypertension Long-standing pulmonary hypertension (increased right ventricular afterload) will lead to the dilatation and remodeling of the right ventricle, which causes tricuspide annular dilatation and tricuspide regurgitation Mitral regurgitation resuts in LV overload and will cause chronic left ventricular dilatation Because of the regurgitant flow entering the low-impedance left atrium, clinical indices of myocardial systolic function, such as ejection fraction (EF) and fractional circumferential fiber shortening (FS), can still be normal even if severely depressed LV systolic contractility is present Chronic regurgitant flow into the left atrium leads to progressive atrial enlargement but left atrial pressure is normal or only slightly above normal In this situation, pulmonary artery pressure and pulmonary vascular resistance usually still remain in the normal range or are only modestly elevated In patients with concomitant mitral stenosis and regurgitation, the left atrium is dilated and intra - atrial pressures increased Left atrial thrombosis prevalance is usually less Long - standing elevated pressure in the left atrium will increase the pulmonary artery pressure Degree of left ventricular dilatation depends on the degree of regurgitation 1.1.2 Treatment of mitral valve diseases Treatment of mitral valve diseases includes medical therapy, percutaneous balloon dilatation, surgical treatment (commissurotomy, mitral valve repair, mitral valve replacement) Over the past 40 years, a large variety of prosthetic valves have been developed with the aim of improving hemodynamic function, inceasing durability, and reducing complications Nevertheless, there is no ideal valve, and all prosthetic valves are prone to dysfunction The valve types now implanted include bileaflet and tilting disc mechanical and biological and autografts (Ross procedure) in which, Sorin Bicarbon mechanical valves (Sorin Biomedica, Saluggia, Italy) is one of the most common used bileaflet mechanical prostheses in the world and in Vietnam 1.1.3 Diagnostic methods for evaluation of prosthetic valve function The currently available modalities in the evaluation of prosthetic valve function include cinefluoroscopy, cardiac catheterization, computerized tomography and echocardiography With the advent of Doppler and transesophageal imaging, echocardiography has become the method of choice for the evaluation of prosthetic valve function Motion as well as structure of prosthetic valves and the causes of valve dysfunction (if any) can be assessed by transthoracic and transesophagial echocardiography With the application of Doppler echocardiography, information on transvalvular gradients, effective areas, and the physiologic and pathologic valve regurgitation are provided In addition to valve function, echocardiography offers unique information about the anatomy of the cardiac structures adjacent to the prosthesis as well as cardiac size and function and an estimate of pulmonary artery pressure 1.2 STUDY ON THE CLINICAL AND HEMODYNAMIC CHANGES AFTER MITRAL VALVE REPLACEMENT SURGERY 1.2.1 Around the world There are many studies on different aspects of mitral prosthetic valve: - The early and longterm clinical experiences of the different types of prostheses: Goldsmith (1999), Camilleri (2001), Borman (2003), Ikonomidis (2003), Misawa (2007), Palatinos (2007) - Study of normal Doppler echocardiographic characteristics of different prostheses: Badano (1997), Reisner (1998), Joseph (2005), review of Rosenhek (2003) The role of transesophageal echocardiography in detection the causes of prosthetic malfunction: Muratori (2006), Ozkan (2006), Pedersen (2010) : - The study of Doppler echocardiographic changes in left ventricular size and function and / or pulmonary pressure after mitral valve replacement: Le Tourneau (2000), Chowdhury (2005), Zakai (2010), Aris (1996), Mubeen (2008) 1.2 In Vietnam In 2005, Nguyen Hong Hanh studied normal Doppler echocardiographic characteristics of St Jude valve Research of Ho Huynh Quang Tri (2007), Dang Hanh Son (2010) for clinical and echocardiographic medium-and long-term experiences of the patients after mitral replacement surgery The majority of patients had improved NYHA grade, pulmonary pressures, cardiac chamber sizes, Researches by Nguyen Duy Thang (2011), Nguyen Hong Hanh (2012) shows the good results of mitral valve St Jude replacement with low complication rates Research in 2012 by Nguyen Hong Hanh showed the months’ improvement of clinical and subclinical improved These studies did not analyze the changes in echocardiographic in detail nor performe transesophageal echocardiography Chapter SUBJECTS AND METHODS 2.1 SUBJECTS The study population consisted of 104 patients undergoing mitral valve replacement using mechanical Sorin Bicarbon prostheses in Hanoi Heart Hospital between 9/2008 and 11/2009 All patients were followed up to months There were 80 patients assessed at year’s post-operative time 2.1.1 Selection criteria All patients with mitral valve lesions (stenosis, regurgitation or mixed lesion) undergoing successful mitral valve replacement surgery using Sorin Bicarbon prosthses with or without tricuspid valve repaired were invited to the study For the purpose of accurate data analysis, the patients were divided into groups based on their predominant hemodynamic valve lesion: - Group I: dominant mitral stenosis: included 32 patients with severe miral stenosis (MS) with/out slight MR (≤ 1/4) w/o light aortic valve lesion - Group II: dominant mitral regurgitation: included 35 patients with severe MR, and may have mild MS w/o mild aortic valve lesion - Group III: mixed mitral valve lesion: included 40 patients with severe MS and MR grade ≥ 2/4 w/o mild aortic valve lesion 2.1.2 Exclusion criteria The patients with concomitant procedure, such as aortic valve replacement, coronary bypass surgery, congenital heart defects corrected were excluded from the research 2.2 METHODOLOGY 2.2.1 Study design: This is a prospective, cross-sectional, longitudinal follow-up study 2.2.2 Steps: + Preoperative assessements: preoperative bilan including physical examination, chest X-ray, 12-lead ECG, transthoracic echocardiography and blood sample was completed within week before operation + The patients underwent mitral valve replacement with cardio - pulmonary bypass and had tricuspide repaired if indicated Operative parameters were noted + Postoperative assessements: were carried out at the time of 1-2 weeks, month, months, months after operation or when there is suspicious symptoms Note the results of clinical examination and echocardiography in patients’ records TEE were performed within month of the operation or when there were suspected mechanical valve malfunction or endocarditis 2.2.3 The echocardiographic data A Transthoracic echocardiography Doppler Transthoracic echocardiography Doppler was performed in a standard manner using a Nemio 30 ultrasonoscope (Toshiba, Japan) * The following parameters were noted in preoperative examination: - The left ventricular end-diastolic diameter (Dd) and end-systolic (Ds), fraction of shortening (FS) and ejection fraction (EF) - The mitral valve lesions (stenosis, regurgitation, mixed lesion) - Grade of tricuspide regurgitation and pulmonary systolic pressure - The diameter and area of the atria, right ventricular diameter, Tricuspid annular plane systolic excursion (TAPSE), systolic tissue Doppler signal of the tricuspid annulus (St) * The following parameters were noted in all postoperative echocardiography - Doppler checkup: - All parameters evaluated before operation and some other parameters to assess the functioning of prostheses: maximal and mean trans – prosthetic gradients (Gmax and Gmean, Vmax and Vmean), the pressure half time (PHT), effective orifice area (EOA), assessing the physiological prosthetic regurgitation, pericardial effusion B Transesophageal echocardiography We noted the parameters evaluating the functioning of prosthetic heart valves: peak and mean transprosthetic gradients and velocity (Gmax and Gmean, Vmax and Vmean), the pressure half time (PHT), effective orifice area (EOA), the physiological and paraprosthetic prosthetic regurgitation (if any) * The values of echocardiographic parameters were averaged over cardiac cycles in patients with atrial fibrillation 2.4 Statistical analysis The data collected were treated using SPSS 15.0 software program The results are expressed as mean ± standard deviation Using "t" test student and Chi square test to compare results between groups Compare ANOVA was used to compare mean values of groups Using a paired t test (Paired - t test) to compare the results obtained before and after surgery, and TTE and TEE results A probability (p) valuesless than 0,05was considered statistically significant Chapter RESULTS 3.1 Baseline characteristics of the study group The research population included 104 patients with mitral mechanical Sorin Bicarbon inserted from 9/2008 to 11/2009, and were followed up for months There were 80 patients assessed at year after operation The study group included 64.4% female and 35.6% male Their ages ranged from 16 to years( mean 44.2 ± 11.5 years) All patients were in New York Heart Assocition (NYHA) functional class II or higher before surgery, among them, 14 patients (13.5%) in the NYHA III – IV Preoperative atrial fibrillation was observed in 80 patients (76.9%), 24 patients (23.1%) maintained sinusal rhythm 3.2 Pre-operative Doppler echocardiography data Most patients in the study had post-rhumatismal lesions on echocardiography: 84 patients accounted for 80.8% The patients had left atrial dilatation (average 56.5 mm) 64.4% of patients had spontaneous contrast echo in the left atria, of these, 17 (16.3%) observed thrombosis in the left atria and/ or left atrial appendages 74 patients (71.2%) had 2+ TR or more 69.9% of patients with severe pulmonary hypertension (systolic PAP ≥ 60mmHg) and 16 patients (15.4%) had EF 0.05) On TTE, physiological regurgitations were observed in 83 patients (80.5%) 3.4.2 Transesophageal echocardiography Doppler The TEE data were evaluated in 98 patients The transprosthetic peak and mean pressure gradients measured by TEE were lower than that measured by TTE (p