Objectives of the study - To study the changes of hemodynamics and cardiac functionafter surgical mitral valve replacement with Sorin Bicarbon valve.. - To evaluate the normally function
Trang 11 The necessaty of the thesis
Mitral valve replacement is the last choice for treating mitralvalve diseases if the valve lesions are too severe for preservation
In VietNam, valve replacement surgery has been carried outfor more than 10 years, but the number of the patients receiving valveprostheses has incessingly increased The number of valvereplacement 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 riskmany complications: thrombosis, infective endocarditis, prostheticdegeneration,…Therefore, these patients need to be followed upperiodically to find out these complications as early as possible.Echocardiography is an established technique for postoperative routineserial assessment of hemodynamics, ventricular function as well as valveoperation Around the world, there have been many studies on prostheticvalve operation as well as on evaluating the postoperativehemodynamics and cardiac function changes by echocardiography Inour country, there are a few previous studies on normally functioningprostheses using mainly transthoracic Doppler echocardiography Wehave not seen any studies using transesophageal echocardiography toassess the activity of the prosthetic valve Therefore, to study thisproblem is topical, scientific and helpful to cardiologists in clinicalpractice
2 The significance of topics
Heart valve replacement surgery is done more and more now.This is an effective treatment to improve symptoms and survival ofpatients Hemodynamics has been improved, pulmonary pressure andheart failure have been reduced in the majority of patients However,
Trang 2some patients may also manifest heart failure as well as thecomplications of prosthetic valve Echocardiography plays animportant role and is one of the major techniques for monitoringpatients Echocardiography research on outcome after prostheticvalve replacement is really meaningful for prognosis and monitoringpatients after surgery.
3 Objectives of the study
- To study the changes of hemodynamics and cardiac functionafter surgical mitral valve replacement with Sorin Bicarbon valve
- To evaluate the normally functioning and complications (ifany) of prosthetic mitral valve Sorin Bicarbon by transthoracic andtransesophageal echocardiography
4 Structure
The thesis consists of 105 pages (excluding appendices andreferences) with 4 main chapters: Introduction - 2 pages , Chapter 1 -Overview 28 pages, Chapter 2 - Subjects and Methods 16 pages,Chapter 3 - Research Results 31page, Chapter 4 - Discussion 25pages, Conclusions and Recommendations - 3 pages Thesis has 37tables, 7 diagrams, 26 illustrations, 149 references, including 33Vietnamese and 116 English and French documents
Chapter 1 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 thecombination of stenosis and regurgitation A common cause is post-rhumatism Other causes may be degeneration, annular calcification,infective endocarditis
Trang 3Mitral stenosis increases the average pressure in the leftatrium, and if severe enough, it leads to secondary pulmonaryhypertension Long-standing pulmonary hypertension (increasedright ventricular afterload) will lead to the dilatation and remodeling
of the right ventricle, which causes tricuspide annular dilatation andtricuspide regurgitation
Mitral regurgitation resuts in LV overload and will causechronic left ventricular dilatation Because of the regurgitant flowentering the low-impedance left atrium, clinicalindices of myocardialsystolic function, such as ejection fraction (EF) and fractionalcircumferential fiber shortening (FS), can still be normal even ifseverely depressed LV systolic contractility is present Chronicregurgitant flow into the left atrium leads to progressive atrialenlargement but left atrial pressure is normal or only slightly abovenormal In this situation, pulmonary artery pressure and pulmonaryvascular resistance usually still remain in the normal range or areonly modestly elevated
In patients with concomitant mitral stenosis and regurgitation,the left atrium is dilated and intra - atrial pressures increased Leftatrial thrombosis prevalance is usually less Long - standing elevatedpressure in the left atrium will increase the pulmonary arterypressure 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 havebeen developed with the aim of improving hemodynamic function,inceasing durability, and reducing complications Nevertheless, there
Trang 4is no ideal valve, and all prosthetic valves are prone to dysfunction.The valve types now implanted include bileaflet and tilting discmechanical 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 inthe world and in Vietnam
1.1.3 Diagnostic methods for evaluation of prosthetic valve function
The currently available modalities in the evaluation ofprosthetic valve function include cinefluoroscopy, cardiaccatheterization, computerized tomography and echocardiography.With the advent of Doppler and transesophageal imaging,echocardiography has become the method of choice for theevaluation of prosthetic valve function Motion as well as structure ofprosthetic valves and the causes of valve dysfunction (if any) can beassessed by transthoracic and transesophagial echocardiography.With the application of Doppler echocardiography, information ontransvalvular gradients, effective areas, and the physiologic andpathologic valve regurgitation are provided In addition to valvefunction, echocardiography offers unique information about theanatomy of the cardiac structures adjacent to the prosthesis as well ascardiac size and function and an estimate of pulmonary arterypressure
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 mitralprosthetic valve:
- The early and longterm clinical experiences of the different
Trang 5types of prostheses: Goldsmith (1999), Camilleri (2001), Borman(2003), Ikonomidis (2003), Misawa (2007), Palatinos (2007)
- Study of normal Doppler echocardiographic characteristics ofdifferent prostheses: Badano (1997), Reisner (1998), Joseph (2005),review of Rosenhek (2003) The role of transesophagealechocardiography in detection the causes of prosthetic malfunction:Muratori (2006), Ozkan (2006), Pedersen (2010) :
- The study of Doppler echocardiographic changes in leftventricular size and function and / or pulmonary pressure after mitralvalve replacement: Le Tourneau (2000), Chowdhury (2005), Zakai(2010), Aris (1996), Mubeen (2008)
1.2 In Vietnam
In 2005, Nguyen Hong Hanh studied normal Dopplerechocardiographic characteristics of St Jude valve Research of HoHuynh Quang Tri (2007), Dang Hanh Son (2010) for clinical andechocardiographic medium-and long-term experiences of the patientsafter mitral replacement surgery The majority of patients hadimproved NYHA grade, pulmonary pressures, cardiac chambersizes, Researches by Nguyen Duy Thang (2011), Nguyen HongHanh (2012) shows the good results of mitral valve St Judereplacement with low complication rates Research in 2012 byNguyen Hong Hanh showed the 6 months’ improvement of clinicaland subclinical improved These studies did not analyze the changes
in echocardiographic in detail nor performe transesophagealechocardiography
Trang 62.1.1 Selection criteria
All patients with mitral valve lesions (stenosis, regurgitation ormixed lesion) undergoing successful mitral valve replacementsurgery using Sorin Bicarbon prosthses with or without tricuspidvalve repaired were invited to the study
For the purpose of accurate data analysis, the patients weredivided into 3 groups based on their predominant hemodynamicvalve lesion:
- Group I: dominant mitral stenosis: included 32 patients withsevere miral stenosis (MS) with/out slight MR (≤ 1/4) w/o light aorticvalve lesion
- Group II: dominant mitral regurgitation: included 35 patientswith severe MR, and may have mild MS w/o mild aortic valvelesion
- Group III: mixed mitral valve lesion: included 40 patientswith 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 valvereplacement, coronary bypass surgery, congenital heart defectscorrected were excluded from the research
Trang 7+ The patients underwent mitral valve replacement withcardio - pulmonary bypass and had tricuspide repaired ifindicated Operative parameters were noted.
+ Postoperative assessements: were carried out at the time of1-2 weeks, 1 month, 3 months, 6 months after operation or whenthere is suspicious symptoms Note the results of clinical examinationand echocardiography in patients’ records TEE were performedwithin 1 month of the operation or when there were suspectedmechanical valve malfunction or endocarditis
2.2.3 The echocardiographic data
A Transthoracic echocardiography Doppler
Transthoracic echocardiography Doppler wasperformed in a standard manner using a Nemio 30ultrasonoscope (Toshiba, Japan)
* The following parameters were noted in preoperativeexamination:
- The left ventricular end-diastolic diameter (Dd) andend-systolic (Ds), fraction of shortening (FS) andejection fraction (EF)
- The mitral valve lesions (stenosis, regurgitation,mixed lesion)
- Grade of tricuspide regurgitation and pulmonary
Trang 8systolic 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 postoperativeechocardiography - Doppler checkup:
- All parameters evaluated before operation and some otherparameters to assess the functioning of prostheses: maximal and meantrans – prosthetic gradients (Gmax and Gmean, Vmax and Vmean), thepressure half time (PHT), effective orifice area (EOA), assessing thephysiological prosthetic regurgitation, pericardial effusion
B Transesophageal echocardiography
We noted the parameters evaluating the functioning ofprosthetic heart valves: peak and mean transprosthetic gradients andvelocity (Gmax and Gmean, Vmax and Vmean), the pressure halftime (PHT), effective orifice area (EOA), the physiological andparaprosthetic prosthetic regurgitation (if any)
* The values of echocardiographic parameters were averaged over 5 cardiac cycles in patients with atrial fibrillation.
2.4 Statistical analysis
The data collected were treated using SPSS 15.0 softwareprogram
The results are expressed as mean ± standard deviation
Using "t" test student and Chi square test to compare resultsbetween groups Compare ANOVA was used to compare meanvalues of 2 groups
Using a paired t test (Paired - t test) to compare the resultsobtained before and after surgery, and TTE and TEE results A
Trang 9probability (p) valuesless than 0,05was considered statisticallysignificant.
Chapter 3 RESULTS 3.1 Baseline characteristics of the study group
The research population included 104 patients with mitralmechanical Sorin Bicarbon inserted from 9/2008 to 11/2009, andwere followed up for 6 months There were 80 patients assessed at 1year after operation
The study group included 64.4% female and 35.6% male.Their ages ranged from 16 to 6 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 wasobserved in 80 patients (76.9%), 24 patients (23.1%) maintainedsinusal rhythm
3.2 Pre-operative Doppler echocardiography data
Most patients in the study had post-rhumatismal lesions onechocardiography: 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, ofthese, 17 (16.3%) observed thrombosis in the left atria and/ or leftatrial appendages 74 patients (71.2%) had 2+ TR or more 69.9% ofpatients with severe pulmonary hypertension (systolic PAP ≥60mmHg) and 16 patients (15.4%) had EF <50% before surgery
3.3 Characteristics of mitral valve replacement operation
In the 104 patients studied, the size of the Sorin Bicarbonvalve used ranged from 25 to 33 and included all the intermediat size.The most used size were 29 and 31 (63.4%) The concomitanttricuspid valve repair was performed in 68 patients (65.2%) Left
Trang 10atrial and appendage thrombosis were dredged in 20 patients 71patients (68.9%) had left atrial appendage sutures.
3.4 Doppler echocardiography data assessing mitral Sorin Bicarbon prostheses
3.4.1 Transthoracic echocardiograhy
An adequate recording of the jet through mitral Sorin Bicarbonprotheses have been obtained in 103 patients because one patient hadearly prosthetic valve thrombosis
Table 3.8 gives the values of some transthoracicechocardiographic parameters evaluating the prosthetic function
Table 3.8 Doppler data of normally functioning mitral Sorin Bicarbon
We do not see the significant difference of the peak and meanvelocities, peak and mean pressure gradients, PHT, VTI, and EOA byPHT method and continuity equation between the sizes of valves (p>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 Thetransprosthetic peak and mean pressure gradients measured by TEEwere lower than that measured by TTE (p <0.001 and <0,05) PHT
Trang 11also shorter and EOA by PHT method also higher with statisticalsignificance (p <0.001).
On transesophageal study, 3 physiological regurgitant flowswere observed in all 98 patients, including one central and 2peripheral The largest flows were usually the peripheral ones Themean width at the origin was 2.1 ± 0.3 (mm), the mean jet length was20.2 ± 4.6 (mm) and the mean jet area was 1.3 ± 0.5 (cm2)
On 1 month post-operative TEE study, 10 patients (10.2%) had asmall paraprosthetic regurgitation There was no regurgitant jet with thewidth at the origin > 2.6 mm, the length > 38 mm and the jet area > 3.4 cm2
3.5 Changes of the cardiac size and function after mitral valve replacement surgery.
Early after operation, left ventricular end-diastolic size (Dd, Vd)decreased significantly, but the size of left ventricular end-systolic (Ds,Vs) didnot change significantly (p> 0.05) Therefore, FS and EF reducedsignificantly after surgery, as compared with before surgery At the time
of 6 months and 12 months after surgery, left ventricular end-diastolicand end-systolic size reduced significantly (p<0.001), and leftventricular systolic function improved significantly with p <0.001.Post-operative right ventricular size and function reducedsignificantly The parameters asessing right ventricular systolic functionincreased significantly from 3 months after surgery Systolic pulmonaryartery pressure decreased significantly after mitral replacement surgerywith p <0.001 Pulmonary pressure continued to decline in 6 months and 1year after surgery but not as much as immediately after surgery (p <0,05)
To further analyze these changes, we divided the study subjectsinto three groups: mitral stenosis (MS), mitral regurgitation (MR), andmixed lesion (MS/MR)
3.5.1 Changes of the cardiac size and function in MS group
Trang 12Table 3.20 lists the preoperative and postoperative Dopplerechocardiographic variables assessing left ventricular size and function inthe MS group
Table 3.20 Changes of echocardiographic Doppler parameters assessing left ventricular size
-and function in the MS group
Table 3.22 Data of echocardiographic - Doppler parameters assessing
RV size and function and pulmonary pressure in the MS group
Trang 13*- p < 0,05; §- p < 0,001 compared with early postoperative (M0.
In the MS group, right ventricular size and systolic function weresignificantly reduced after surgery Postoperative pulmonary pressuredecreased significantly (p <0.001) During 1 year’s follow-up period, RVdiameter did not change significantly, but the systolic function improvedsignificantly from 3 months after surgery (p <0.001); Pulmonary pressuretended to decrease more, but not significantly (p> 0,05)
3.5.2 Changes of the left ventricular size and
function in the MR group Table 3.23 Changes of left ventricular size and
function in the MR group
†- p < 0,001 compared with preoperation;
* - p< 0,05; §- p<0,001 compared with early postoperative (M0)
Early after surgery, Dd as well as FS and EF decreasedsignificantly (p <0.001) but Ds and Vs did not change significantly (p>0.05) Dd and Vd did not change significantly from early to 12 monthsafter surgery (p> 0.05), but Ds, Vs reduced significantly from 6 monthsafter operation Left ventricular systolic function improved significantly,but the values of LV variables weren’t as high as preoperative ones
Table 3.25: Changes of RV size and function and pulmonary pressure in
the MR group.