Tóm tắt Luận án Surgical outcome assessment of partial atrioventricular septal defect

Partial atrioventricular septal defects (pAVSD) accounted for 80% of atrioventricular septal defects (AVSD). These defects have also been called Partial atrioventricular canal, Ostium primum atrial septal defect, of Endocardial cushion defect. Main anatomic lesions included: primum defect of the atrial septum, two separate atrioventricular valve. The left valve (mitral valve) may have a cleft that causes valve regurgitation.

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MINISTRY OF EDUCATION MINISTRY OF DEFENCE VIETNAM MILITARY MEDICAL ACADEMY -------------------- DAO QUANG VINH SURGICAL OUTCOME ASSESSMENT OF PARTIAL ATRIOVENTRICULAR SEPTAL DEFECT MAJOR: THORACIC SURGERY CODE : MEDICAL DOCTORATE STUDY SUMMARY HANOI - 2015 THE STUDY WAS PERFORMED IN VIETNAM MILITARY MEDICAL ACADEMY Scientific Advisors: Assoc. Prof. Dr. DANG NGOC HUNG Assoc. Prof. Dr. LE NGOC THANH Reviewer 1: Prof. Dr. Bui Duc Phu Reviewer 2: Assoc. Prof. Dr. Tran Van Riep Reviewer 3: Assoc. Prof. Dr. Doan Quoc Hung Thesis defence will be performed in front of university commitee in Vietnam Military Medical Academy at: The study can be found at: National Library Library of Vietnam Military Medical Academy LIST OF RELATING THESIS Đào Quang Vinh, Nguyễn Văn Mão, Nguyễn Sinh Hiền, Đặng Hanh Sơn và cs (2008), “Nhận xét kết quả sớm sau phẫu thuật sửa toàn bộ bệnh kênh nhĩ thất bán phần tại bệnh viện tim Hà Nội”, Tạp chí y học Việt nam, (số đặc biệt tháng 11/2008); tr.77-85. Đào Quang Vinh và cs (2010), “Nhận xét kết quả sớm sau phẫu thuật sửa chữa toàn bộ bệnh kênh nhĩ thất toàn phần tại bệnh viện tim Hà Nội”, Tạp chí y học Việt nam, (số đặc biệt tháng 11/2010); tr. 5-11. INTRODUCTION Partial atrioventricular septal defects (pAVSD) accounted for 80% of atrioventricular septal defects (AVSD). These defects have also been called Partial atrioventricular canal, Ostium primum atrial septal defect, of Endocardial cushion defect. Main anatomic lesions included: primum defect of the atrial septum, two separate atrioventricular valve. The left valve (mitral valve) may have a cleft that causes valve regurgitation. Maude Abbott first recognized ostium primum atrial septal defect and common AV canal defect in 1936. And the morphology of the defect was descripted in detail by GianPieroPicolli et al. in 1976. The first successful repair of AVSD was performed by Lillehei and colleagues in 1954. And in 1955, Kirklin and colleagues began repairing AVSD by open cardiac surgerywith use of oxygenator. Common complications after surgery included complete AV block, post repair mitral regurgitation and LV outflow tract obstruction. AVSD was long studied throughout the world but there were still problems yet to be agreed by authors. For example, should complete closure of mitral cleft be performed in every patients, or which is the best way of ostium primum closing without damaging the AV node and His bundle, while the conduction system of AVSD patient often varies. In Vietnam, cardiac surgery centers such as Viet Duc Hospital, Hochiminh Heart Hospital, Hanoi Heart Hospital, Cardiology Center of E Hospital, and National Hue Hospital have successfully repaired many cases of pAVSD. But a full research on anatomy, diagnostic and surgical treatment of this CHD was yet to be reported. For this reason we conducted a study on "Surgical outcome assessmentof partial atrioventricular septal defect" with the following objectives: To analyze and evaluate the clinical  and sub-clinical features found in pAVSD patients operated in Hanoi Heart Hospital. To estimate the outcome of surgical treatment of pAVSD in Hanoi Heart Hospital. The new contributions of this study are:  To provide the first detailed research on the assessment of the surgical  outcome in the treatment of pAVSD To confirm the safety and efficacy of the surgical treatment of pAVSD under the contemporarily surgery- working conditions in Vietnam's hospitals. To support the patch technique for closure of atrial septal defect which can maintain the coronary sinus on its original  anatomical side and does not change the AV block rate. Outline of the thesis in 111 pages:  Introduction Chapter 1 Abstract Chapter 2 Patients and Methods Chapter 3 Results Chapter 4 Discussion Conclusion 26 tables 11 charts 24 figures 102 references Chapter 1 APPROACH Morphology of atrioventricular septal defect The development of endocardial cushions Studies on embryology have shown there is a greatly close relation between abnormal development of endocardial cushion and atrioventricular septal defect. The formation of AVSD: Depending on how severe the abnormal development of the endocardial cushion is, the defects are divided into: complete, partial and transitional forms. Anatomy and pathology of partial AVSD Ostium primum atrial septal defect AVSD always consists of an ostium primum type atrial septal defect( ASD ) a large ASD can cause increased pulmonary blood flow and pulmonary hypertension, small ASDs often cause very few problems. Anterior mitral leaflet cleft The left AV valve or mitral valve usually has anterior mitral leaflet cleft, the cleft might extend partial or entire length of the anterior leaflet. Right AV valve The enlargement of right ventricle results in dilation of tricuspid valve annulus with the presence of the cleft between the anterior leaflet and septal leaflet of the tricuspid valve. According to several authors, it is also called the cleft of septal tricuspid leaflet. Depending on the magnitude, the cleft may cause tricuspid valve regurgitation more or less. Changes in valves’ tissue The mitral and aortic valves can be hypoplastic from mild to severe. The more severe the hypoplasia is, the harder it is to repair. Characteristics of AV valve annulus in partial AVSD In normal mitral valve, the anterior leaflet is anchored to one third of the mitral annulus. The mitral annulus is closer to the left atrium and does not lie in the same plane with the tricuspid annulus. In partial AVSD, the anterior leaflet is anchored to two thirds of the mitral annulus. The mitral annulus is closer to the heart apex and lies in the same plane with the tricuspid annulus. Volume of receiver chamber and left ventricular outflow tract Normally, the outflow/inflow length proportion of the left ventricle is approximately even. In case of partial AVSD, thisproportion will change due to the inflow chamber length decreases and the outflow chamber length increases. Cardiac conduction in partial AVSD AV node and His bundle: AV node lies within the vertex of the triangle of Koch (a three sided zone bounded by the anteromedial margin of coronary sinus orifice, the base of the septal leaflet of the tricuspid valve and the tendon of Todaro). In partial AVSD, the AV node is closer to the base (angle formed by the coronary sinus orifice and tricuspid annulus). The His Bundle begins at the AV node, runs under tricuspid valve annulus along left ventricular septum (part of the interventricular septum) or crest of ventricular septum to the middle third of interventricular septum then divides into branches toward the heart apex. Pathophysiology and diagnosis of AV septal defect Classification of AV septal defects: Fig 1.8 Classification of AV septal defects (source: Allen H.D (2008) [11]) Pathophysiology of partial AV septal defect: Partial AVSD belongs to the non-cyanotic congenital heart defects group except for the cases of AVSD combined with single atrium. In atrial septal defect, the blood flow through the right atrium and right ventricle and the pulmonary blood flow are increased therefore the right atrium, right ventricle volume and the pulmonary artery pressure are increased. Mitral valve regurgitation results in an increase in the atrial pressure and blood flow, atrial dilation, atrial flutter. An increase in the blood flow through the right ventricle causes pre-capillary pulmonary hypertension, increased pressure in the left atrium causes the elevation of post-capillary pressure. Then all will lead to pulmonary hypertension. The increased right heart blood flow and pulmonary hypertension lead to right ventricle enlargement and malfunction and dilation of the tricuspid valve annulus that worsening the tricuspid valve regurgitation, then finally comes the right ventricular heart failure. During the initial stage when the pulmonary artery hypertension is not present, MVR has not caused the left ventricular dilation yet because the bloodflow that goes back to left atrium was shared with the right atrium across the interatrial communication. But when the PAP gets higher, it interferes the blood moving right, therefore the larger amount of blood moves to left ventricle which gradually causes left ventricular dilation,left AV valve annular dilation and worsens the MVR then eventually causes right ventricular failure. In cases with common atrium, the early cyanosis is due to the mixed blood in the interatrialchamber, the cyanosis gets more significant when patients are on exercise. ASD causing left-right shunt is the beginning of the pathologic cycle, the presentation of isolated ostium primum, mild MVR are almost like other ASD. Therefore, patients remain with no specific signs for years. But if the MVR becomes more severe, the first clinical symptom is congestive heart failure Large interatrial communication such as common atrium or associated with large communication between left ventricle and right atrium across the anterior mitral valve cleft will overload the right ventricle, increase PAP and worsen the atrioventricular valve regurgitation. Double orifice-left AV valve can either cause valve stenosis or valve regurgitation. The clinical symptoms vary from mild to severe depending on the severity of the MVR, if the patients are not treated promptly, they will present with early PA hypertension, right ventricular systolic overload, right ventricular heart failure and eventually heart failure. Diagnosis Diagnostic criteria using echocardiography Ostium primum atrial septal defect Left and right A-V valves lie on the same plane The non-specific symptoms include: Anterior mitral leaflet cleft. Separation between the anterior leaflet and septal leaflet of the tricuspid valve Without the presence of ventricular septal defect or a small VSD which can close on its own Differential diagnosis Isolated mitral valve cleft. Complete AVSD. Indications for the first operation. Isolated partial AVSD. Partial AVSD associated with other complicated congenital heart defects. 1.2.4. Indication of repair surgery Minor or moderate mitral valve incompetence. Small to moderate atrial septal defect, aged from 2 to 6 without increased PAP. Patients with large mitral valve incompetence, large atrial septal defect or single atrium, highly increased PAP, congestive heart failure with low response to medication should be operated as soon as possible 1.2.5. Indications for reoperation Severe mitral or tricuspid valve regurgitation, severe left ventricular dilation (or associated with right ventricular dilation), worsened symptoms, heart failure with low response to medication.Large ASD, large residual left-to-right shunt (QP/QS>1.5), high PA pressure is still present. Chapter 2 PATIENTS AND METHODS Patients A total of 89 patients with partial AVSD underwent surgical repair treatment in Hanoi Heart Hospital from January 2005 to June 2011. Selection criteria: Eligible participants:patients being diagnosed with AVSD with two echocardiography results provided by two independent examiners or being confirmed the AVSD diagnosis in the surgery by the surgeon. Critical requirements:Ostium primum or single atrium Non-specific common symptoms:Anterior mitral valve leaflet cleft, separation between the anterior and septal leaflet of the tricuspid valve. Elimination criteria: Atrioventricular septal defect associated with other complicated congenital heart defects (tetralogy of Fallot, double outlet right ventricle, transposition of the great arteries, right ventricular hypoplasia, left ventricular hypoplasia). AVSD associated with Eissenmenger syndrome (cyanosis, ASD shunt reversal,pulmonary vascular resistance > 10 Wood units) . AVSD in patients with severe systemic disease or advanced cancer. Previously operated AVSD patients without long-term follow-up. Method Design: longitudinal study (combined retrospective and prospective uncontrolled clinical trial). Objectives Normal assessment: Age and gender. Assessment of clinical features: Classifying the extent of heart failure according to NYHA, determining the enlarged liver by estimating the liver size (cm) by feeling how far it extends below the rib cage and noticing the distended neck vain while palpating the liver. Level of cyanosis: Non cyanotic. Mild cyanosis of the lips and extremities on increased activity. Mild to moderate cyanosis of the lips and extremities at rest. Severe cyanosis affected the whole body. Chest wall deformity due to heart enlargement Heart murmur: evaluate the systolic murmur (graded on a 6 point scale) at the apex, tricuspid valve and pulmonary valve and the presence of the split S2 Assessment of sub-clinical features: Pre-Operative echocardiography of the chest wall to evaluate: atrial septal defect, left and right AV valves’ structure, magnitude of the mitral valve incompetence and the tricuspid valve incompetence. Grading of the bicuspid valve regurgitation and tricuspid valve regurgitation: four grades 1/4, 2/4, 3/4, 4/4 are based on the mitral valve blood flow diameter/ atrium diameter portion. Evaluation of the EF, LVDD, RVDD values. Evaluation of PAS, PAM and PAD pressures values Post-operative echocardiography of the chest wall to evaluate: the size and function of the heart, residual atrial septal defect, residual mitral valve incompetence, grade of tricuspid valve incompetence, other associated lesions like stenosis of left ventricular outflow tract. ECG to evaluate the sinus rhythm, AV block (type I,II,III) Chest radiography: to evaluate cardiothoracic ratio, increased pulmonary blood flow. Surgical procedure Patient is positioned on the operating table, lying on his/her back, the conventional anesthetic procedure is performed. Technique of operation: Step 1: A median sternotomy is performed Step 2: Establish the CPB Place the aortic cannula and two venous cannulas. Pump flow rate is set and maintained at 2.4l/min/m2 The warm blood cardioplegia solution is perfused every 15 minutes Step 3: Aortic clamp, cardioplegia, exposure and examination of the malformation Step 4: Repair the malformation Repair the mitral valve (left AV valve): close the anterior mitral cleft for all patients even those with mild MVR or without MVR. Remove the fibrous trigones,ligaments that are prone to block the left ventricular outflow tract or consider the operative technique to prevent the left ventricular outflow tract obstruction. Closure of the ASD: autologous pericardium treated withGlutaraldehyde 0.6% or a polyester patch is used as the interatrial patch. In this patch technique, the patch is sutured into the right side of the ASD using the interrupted or continuous or combined sutures. Prolene suture 5/0 is indicated; for children weighed under 10kg, prolene 6/0 is more appropriate. The coronary sinus is left intact no matter which side the coronary sinus orifice is. Repair of the tricuspid valve: The anterior leaflet and the septal leaflet are sewn together edge to edge in case the incompetence is large. De Vega tricuspid annuloplasty technique is applied when the enlargement of the right ventricle causing the tricuspid valve regurgitation type 1 is present. Step 5: cardiotomy closure, deairing,aortic declamping, sternotomy closure. Evaluation of CPB: Long CPB duration (> 120 minutes) Long aortic clamping period (> 90 minutes) Post-operative evaluation: In intensive care unit. Hospital stay time. 3 months, 6 months and annually follow-up. Chapter 3 RESULTS General assessment The sample size was 89 containing 47.2% females and 52.8% males, 28 retrospective cases and 61 prospective cases 14.6% were under 4 years of age, 12.4% were among 4 to 6 year-olds, 32.5% were aged 7 to 16 years , 40.4% were aged 16 years and over Ages ranged between 3 months old to 48 years old Mean [±SD] age, 16.12±12.28 years Clinical features Paraclinical evaluation Echocardiography: Preoperative severe MVR and AVR cases accounted for more than 50% of the total patients, which are 62.9% and 59% respectively. Seven cases without anterior mitral leaflet cleft made up 7.9% of the total patients Table 3.3 Morphologic characteristics of the mitral and tricuspid valves upon preoperative echocardiography Symptoms Number of patients (n=89) Percentage (%) Mitral valve regurgitation Mild 6 6,8 Moderate 27 30,3 Severe 56 62,9 Anterior mitral leaflet cleft None 7 7,9 Partial 18 20,2 Complete 64 71,9 Tricuspid valve regurgitation Mild 7 7,9 Moderate 29 32,6 Severe 53 59,5 Table 3.5 Preoperative evaluation of the heart functions Parameter Mean (X±SD) Minimum Maximum LVDd 35,12 ±7,9 17,5 58,9 LVEF 65,80±7,7 44 79 RVDd 28,94±9,55 11 50 PAM pressure 28,30±10,09 10 70 PAS pressure 49,19 ± 15,55 20 95 ASD magnitude 23,84±11,14 7 57 67.4% of patients had pulmonary hypertension. The mean value of pulmonary artery pressure was 28,30 ± 10,09 mmHg. Echocardiography and chest radiography Morphologic characteristics examined during the surgery Technique of operation Repair of the mitral valve regurgitation Repair of the tricuspid valve regurgitation and closure of ASD Postoperative care and complications Heart and cardiovascular support supplements Immediate postoperative care, hospital stay duration and complications Chart 3.8 post-operative complications Results of Echocardiography performed at hospital discharge Table 3.14:Cardiac functions preoperatively and postoperatively (n=88) Parameters Pre-operative Post-operative p-values LVDd 35,22 ± 7,9 37,5±7,8 < 0,001a LVEF 65,80 ± 7,7 66,7 ±9,3 0,409a Preoperative Dd TP 28,94 ± 9,6 21,0 ± 6,4 < 0,001a PAM pressure 28,4 ± 10,2 19,9 ± 5,7 < 0,001b PAS pressure 49,19 ± 15,6 29,5 ± 7,2 < 0,001b a. T-student test b. Wilcoxon signed - rank test Results at 3rd month-follow-up Results at 6th month-follow-up Table.3.18 Clinical features after 6 month-follow-up Symptoms Number of patients(n=88) Percentage (%) NYHA I 25 28,4 II 62 70,5 III 1 1,1 IV 0 0,0 Systolic murmur Present 33 37,5 Not present 55 62,5 Cyanotic 0 0,0 Edema 0 0,0 Distended neck veins 0 0,0 Ascites 0 0,0 Table 3.19. Evaluation of the AV valves and ASD upon echocardiography after six 6 month-follow-up Symptoms Number of patients (n=88) Percentage (%) MVR mild or not 67 76,1 moderate 20 22,7 severe 1 1,1 TVR mild or not 77 87,5 moderate 11 12,5 severe 0 0,0 Residual ASD 3 3,4 Mild left ventricular outflow tract obstruction 3 3,4 Table 3.21. Clinical symptoms preoperatively, 3 months annd 6 months postoperatively (n=88) NYHA Pre-op (1) 3rd month-follow-up (2) 6th month-follow-up(3) p Class I 0 (0,0%) 0 (0,0%) 25 (28,4%) p1_3=0,000a Class II 75 (84,3%) 86 (97,7%) 62 (70,5%) p1_2=0,002a p1_3=0,028a Class III 13 (14,6%) 2 (2,3%) 1 (1,1%) p1_2=0,003a p1_3=0,001a Class IV 1 (1,1%) 0 (0,0%) 0 (0,0%) Summary 89 (100,0%) 88 (100,0%) 88 (100,0%) a. Chi – square test In NYHA class IV, there was one pre-op patient and no post-op patient. In NYHA class III, there were 13 pre-op patients ( accounted for 14.6%) , two 3rd month follow-up patients ( 2.3%) and one 6thmonth follow-up patient ( 1.1%). 75 preoperative cases ( 84.3% ), 86 cases of 3rdmonth follow-up and 87 cases of 6th month follow-up were in NYHA class I and II. NYHA functional class improvements were statistically significant in both 3rd month and 6thmonth follow-up groups (p ≤ 0,001 ). Table 3.23. Changes in right ventricle volume and PAP (n=88) Indicators Pre-op (1) 3 month (2) 6 month (3) p-values Right ventricular DD 28,9 ± 9,6 19,9 ± 5,4 17,9 ± 4,5 p1_2=0,0000b p1_3=0,0000b PAM-P 28,4 ± 10,2 17,3 ± 5,2 16,3 ± 5,3 p1_2=0,0000b p1_3=0,0000b PAS-P 49,2 ± 15,5 25,
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