Effect of Valve Suture Technique on Incidence of Paraprosthetic Regurgitation and 10-Year Survival

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1 Effect of Valve Suture Technique on Incidence of Paraprosthetic Regurgitation and 10-Year Survival Sukumaran K. Nair, FRCS (C Th), Gauraang Bhatnagar, MBBS, Oswaldo Valencia, MD, and Venkatachalam Chandrasekaran, FRCS (C Th) Department of Cardiothoracic Surgery, St George s Hospital NHS Trust, London, United Kingdom Background. The primary objective was to estimate the risk of paraprosthetic regurgitation (PPR) after aortic (AVR) and mitral valve replacement (MVR) using interrupted (IN) or semicontinuous (SC) sutures. The secondary objective was to estimate the risk of redo valve surgery and 10-year survival after valve replacement performed using either suture technique. Methods. Patients who underwent mechanical AVR or MVR using a St. Jude prosthesis between December 1991 and June 1997 were included. Eighteen patients had MVR and 43 had AVR using IN sutures; 49 and 83 patients received MVR and AVR, respectively, using SC sutures. The majority of these patients were part of a randomized controlled trial with different end points, presented elsewhere. Patients were followed for 10 years with annual transthoracic echocardiography, and clinical data were collected retrospectively. Kaplan-Meier survival analysis was performed. Cox s regression analysis was performed to identify factors predicting mortality as a function of time. Forward stepwise logistic regression was performed to analyze risk factors predicting PPR. Mann-Whitney U test was used for continuous and nonparametric data, and 2 test and Fisher s exact test were used for categorical data. A probability value less than 0.05 was considered significant. Results. The overall risk of PPR after MVR and AVR was higher in the SC group than in the IN group. The need for redo AVR was significantly higher in the SC group. The suture technique did not affect the 10-year survival after either AVR or MVR. Conclusions. Use of SC technique increases the risk of significant PPR after AVR and MVR compared with IN technique independent of the size of prosthesis, degree of annular calcification, disease of the excised valve, or the implanting surgeon. Although 10-year survival is independent of suture technique, SC technique increases the risk of redo valve replacement after AVR. (Ann Thorac Surg 2010;89:1171 9) 2010 by The Society of Thoracic Surgeons Aortic (AVR) and mitral valve replacement (MVR) are performed using either semicontinuous (SC) or interrupted (IN) suture technique. The SC technique is quicker with shorter cross-clamp and cardiopulmonary bypass times [1]. Incidence of paraprosthetic regurgitation (PPR) detected by transesophageal echocardiography in the immediate postoperative period is about 10% to 15% after AVR and MVR, respectively [2]. Paraprosthetic regurgitation could lead to heart failure, hemolytic complications, and thromboembolic complications [3]. Factors considered contributory to PPR include the degree of annular calcification, infection, type of suture technique, and size and type of prosthesis [4, 5]. Hjelms and associates [6] demonstrated an increased risk of PPR after SC technique in patients who had AVR. Laks and colleagues [7] did not find any difference in the incidence of PPR between either suture technique, and Dhasmana and coworkers [5] have shown that in valve replacement for noninfective indications, suture technique did not predict PPR. None of these studies had long-term follow-up with regular echocardiograms. In this paper, we Accepted for publication Dec 30, Address correspondence to Dr Nair, Department of Cardiothoracic Surgery, Papworth Hospital NHS Trust, Cambridgeshire CB23 3RE, United Kingdom; sukumaran.nair@papworth.nhs.uk. report the incidence of PPR detected by annual echocardiograms after AVR and MVR by SC versus IN suture technique during a period of 10 years. Patients and Methods Patients younger than 70 years of age who underwent AVR or MVR using a St. Jude mechanical prosthesis between December 1991 and June 1997 were included. The majority of these patients were part of a randomized control trial investigating different end points. This randomized trial was approved by the institutional review board and the local research ethics committee and has been published before [8]. Echocardiographic and clinical data of patients who were not part of the randomized trial were obtained as part of routine clinical follow-up, and thus separate consent was not sought as individual patients are not identified. Data regarding PPR were collected and analyzed retrospectively. Inclusion and Exclusion Criteria Patients who received a St. Jude aortic or mitral prosthesis were included in the study. Patients who underwent valve replacement for active endocarditis and double valve disease were excluded. Two patients who died 2010 by The Society of Thoracic Surgeons /10/$36.00 Published by Elsevier Inc doi: /j.athoracsur

2 1172 NAIR ET AL Ann Thorac Surg SUTURE TECHNIQUE AND PARAPROSTHETIC REGURGITATION 2010;89: during surgery and 4 who died within the first month after surgery and who did not have PPR in their postoperative echocardiogram were also excluded. Patients with previous valve operations, treated endocarditis, and concomitant coronary artery disease were included. One patient in the aortic valve group was lost to follow-up after the first year and hence excluded from statistical analysis of long-term performance and survival but included in assessing the incidence of PPR. Study Groups Following the inclusion and exclusion criteria described above, 18 patients were identified in the mitral IN and 49 in the mitral SC group. Similarly, 43 patients were identified in the aortic IN and 83 in the aortic SC group. Operative Technique Five surgeons were involved in the implantation of these valves. The suture techniques adopted by individual surgeons were purely at their discretion. Surgeon C as identified in Table 4 used IN technique for all valve replacements. Continuous Suture Technique After excision of the diseased valve and thorough decalcification of the annulus, the annulus was sized and an appropriate-sized prosthesis used for implantation. None of the patients required enlargement of the aortic root for valve insertion. Continuous sutures were placed between the sewing ring of the prosthesis and the valve annulus, in both aortic and mitral positions using 2-0 Prolene (Ethicon, Somerville, NJ). Depending on the annular size and other technical aspects that emerged during the operation, the surgeon used two to four similar sutures with knots tied between them, hence the term semicontinuous. The valve was then parachuted down to the annulus, and the sutures were tied. Interrupted Technique Interrupted 2-0 Ethibond (Ethicon) polytetrafluoroethylene (Teflon) -buttressed sutures were used to suture the prosthesis-sewing ring to the annulus. All the patients had Teflon-buttresses positioned in the ventricular aspect of the annulus. Follow-Up Patients were followed up in a designated valve clinic on a yearly basis. Apart from detailed history and physical examination, patients underwent an electrocardiogram, chest radiograph, blood tests, and a transthoracic echocardiogram. The follow-up period was for a maximum of 10 years after valve implantation. One patient was lost to follow-up after the first postoperative year and hence excluded from statistical analysis. Patients with PPR observed in the transthoracic echocardiogram were discussed with the cardiologist, taking due consideration of all clinical variables to arrive at a consensus plan of action. In general terms, redo valve operation was performed if the PPR was graded as moderate or severe and conservative management was adopted if it was mild or trivial. Anticoagulation All patients were followed up in specialist anticoagulation clinics in general hospitals close to their place of residence where their international normalized ratio was checked and maintained between 3 and 4 for both aortic and mitral mechanical valves. Data Handling and Statistical Analysis Incidence of PPR at both aortic and mitral positions was recorded separately. Kaplan-Meier survival analysis was performed to study the trend in the survival of patients who had their valves replaced using either suture technique. Mann-Whitney U test was used for continuous variables and nonparametric data among patients in the two groups. 2 test and Fisher s exact test were used to study any difference between the two groups for categorical or dichotomous data. Cox s regression analysis was performed to identify factors predictive of survival after valve replacement. For this analysis, demographic factors, namely age, sex, disease of the native valve (predominantly regurgitant or stenotic), and diabetes mellitus; preoperative factors, namely left ventricular ejection fraction, diabetes mellitus, left ventricular end-diastolic diameter, left ventricular end-systolic diameter, body surface area, cardiothoracic ratio, New York Heart Association class, healed endocarditis, and rhythm; operative variables, namely suture material used, suture technique, valve or prosthesis size, annular calcification, and concomitant coronary artery bypass grafts performed; and postoperative variables, namely incidence of PPR, grade of PPR, and interval between surgery and detection of PPR, were considered as independent outcomes. Forward stepwise logistic regression was performed to analyze risk factors responsible for the occurrence of PPR after valve replacement. Independent factors considered were age, sex, New York Heart Association class, annular calcification, diabetes mellitus, concomitant coronary artery bypass grafting, preoperative rhythm, disease of the native valve, suture technique used, body surface area, and the surgeon performing the operation. A probability value less than 0.05 was considered significant, accepting a confidence interval of 95%. The statistical program SPSS 14.0 (SPSS, Chicago, IL) was used for the various analyses. Results Patient Characteristics Patients were divided into the SC or IN groups. Among the MVR group (Table 1), 41 were women (61%) and 26 were men (39%). Both groups were comparable in terms of disease of the valve, size of prosthesis, body mass index, age, preoperative left ventricular function, cardiothoracic ratio, left ventricular end-diastolic diameter, left ventricular end-systolic diameter, or annular calcifica-

3 Ann Thorac Surg NAIR ET AL 2010;89: SUTURE TECHNIQUE AND PARAPROSTHETIC REGURGITATION 1173 Table 1. Distribution of Categorical Variables Among Patients Who Underwent Mitral Valve Replacement Variable SC IN Total p Value Median age and 65 (41 77) 64 (32 70) 0.38 range (y) Sex Female Male Diagnosis Predominantly stenotic Predominantly regurgitant Rhythm Sinus Other NYHA grade IorII III IV LVEF Treated endocarditis No Yes SJ valve size (mm) CABG No Yes Mitral annular calcification No Yes Median LVEDD (1st, 5.5 (5.1, 6.1) 5.7 (4.8, 6.3) rd quartile) Median LVESD (1st, 3rd quartile) 3.7 (3.1, 4.2) 3.5 (2.9, 4.4) 0.99 CABG coronary artery bypass grafts; IN interrupted technique; LVEDD left ventricular end-diastolic diameter in cm; LVEF left ventricular ejection fraction; LVESD left ventricular end-systolic diameter in cm; NYHA New York Heart Association; SC semicontinuous technique; SJ valve St. Jude valve. tion. The incidence of simultaneous coronary artery bypass grafting was significantly more in the SC group. In the AVR group (Table 2), 100 patients were men (79.4%) and 26 were women (20.6%). The groups did not differ from each other in terms of valvular disease, size of prosthesis, body mass index, age, preoperative left ventricular function, cardiothoracic ratio, left ventricular end-diastolic diameter, left ventricular end-systolic diameter, annular calcification, or concomitant coronary artery bypass graft surgery. Risk of Paraprosthetic Regurgitation Persists Beyond the First Year After Valve Replacement After MVR, the median number of postoperative days at which PPR was detected in the IN and SC group was 887 days (range, 733 to 1,040 days) and 515 days (range, 7 to 1,831 days), respectively (p 0.56). After AVR, the median number of postoperative days at which PPR was detected in the IN and SC group was 206 days (range, 35 Table 2. Distribution of Categorical Variables Among Patients Who Underwent Aortic Valve Replacement Variable SC IN Total p Value Median age and 63 (28 74) 62 (46 76) 0.83 range (y) Sex Female Male Diagnosis Predominantly stenotic Predominantly regurgitant Rhythm Sinus Other NYHA grade IorII III IV LVEF Treated endocarditis No Yes SJ valve size (mm) CABG No Yes Aortic annular calcification No Yes Median LVEDD (1st, 5.5 (4.7, 6.4) 5.3 (5.0, 6.3) rd quartile) Median LVESD (1st, 3rd quartile) 3.6 (2.9, 4.6) 3.4 (3.0, 4.8) 0.95 CABG coronary artery bypass grafts; IN interrupted technique; LVEDD left ventricular end-diastolic diameter in cm; LVEF left ventricular ejection fraction; LVESD left ventricular end-systolic diameter in cm; NYHA New York Heart Association; SC semicontinuous technique; SJ valve St. Jude valve.

4 1174 NAIR ET AL Ann Thorac Surg SUTURE TECHNIQUE AND PARAPROSTHETIC REGURGITATION 2010;89: Table 3. Incidence, Relative Risk, and Management of Paraprosthetic Regurgitation After Mitral Valve Replacement and Aortic Valve Replacement Using Different Suture Techniques Details of PPR SC IN Total 2 Two- Sided Test MVR group Surgical significance of PPR Absent mild PPR Moderate severe PPR Relative risk, 1.51; 95% CI, 1.25 to 1.84 Management of PPR after MVR Conservative Redo valve replacement AVR group Surgical significance of PPR Absent mild PPR Moderate severe PPR Relative risk, 1.59; 95% CI, 1.38 to 1.83 Management of PPR after AVR Conservative Redo valve replacement Relative risk, 2.0; 95% CI, 1.14 to 3.52 AVR aortic valve replacement; CI confidence interval; IN interrupted technique; MVR mitral valve replacement; PPR periprosthetic regurgitation; SC semicontinuous technique. to 1,430 days) and 557 days (range, 0 to 1,586 days), respectively (p 0.51). Risk to develop PPR persists beyond the first year after valve replacement. Semicontinuous Suture Technique Increases the Risk of Significant Paraprosthetic Regurgitation but Did Not Affect the Rate of Reoperation or 10-Year Survival After Mechanical Mitral Valve Replacement The relative risk to develop any degree of PPR after mechanical MVR with SC technique was 3.31 (95% confidence interval, 0.85 to 12.85). The incidence of moderate or severe PPR after MVR using the IN technique was 0% (0 of 18 patients) compared with 28.6% (14 of 49 patients) after SC technique (Table 3). This difference was statistically significant (p 0.01), giving a relative risk of 1.51 (95% confidence interval, 1.25 to 1.84) to develop significant PPR (moderate or severe) with SC technique. Figure 1 demonstrates a statistically significant increase in the incidence of PPR when MVR was performed using SC technique. In this study it did not translate into an increase in redo MVR in the SC group. This reflects case selection bias by the surgeons in surgical intervention when PPR was detected. The 10-year survival of patients who underwent MVR using either technique was similar (Fig 2). Semicontinuous Suture Technique Increases the Risk of Significant Paraprosthetic Regurgitation and Need for Reoperation After Mechanical Aortic Valve Replacement With No Significant Difference in 10-Year Survival The incidence of moderate or severe PPR after mechanical AVR using the IN technique was 0% (0 of 43 patients) compared with 12% (10 of 83 patients) after SC technique (Table 3). This difference was statistically significant (p 0.02), giving a relative risk of 1.59 (95% confidence interval, 1.38 to 1.83) to develop clinically significant PPR (moderate and severe PPR) with SC technique. The Table 4. Regression Analysis of Factors Predicting Survival With Time and Incidence of Paraprosthetic Regurgitation After Mitral Valve Replacement and Aortic Valve Replacement Variable Coefficient SEM Wald df p Value Exp(coef) 95% CI 2 df p Value MVR Cox s regression for survival with time Age LVEF Forward stepwise logistic regression for PPR Surgeon C Constant AVR Cox s regression for survival with time Age Nonsinus rhythm Redo for PPR Forward stepwise logistic regression for PPR Annular calcification Constant AVR aortic valve replacement; CI confidence interval; df degrees of freedom; Exp(coef) exponential coefficient; LVEF left ventricular ejection fraction; MVR mitral valve replacement; PPR periprosthetic regurgitation; SEM standard error of the mean.

5 Ann Thorac Surg NAIR ET AL 2010;89: SUTURE TECHNIQUE AND PARAPROSTHETIC REGURGITATION 1175 Fig 1. Effect of suture technique on survival after mitral valve replacement (MVR). Kaplan-Meier survival curves demonstrating postoperative survival are shown with years on the x axis and the y axis representing percentage survival. The dotted line represents the interrupted technique (IN) suture group and the continuous line represents the semicontinuous technique (SC) suture group. Table of patients at risk of death is shown below the survival curves. relative risk of redo valve replacement owing to significant PPR after SC technique was 2.0 (95% confidence interval, 1.14 to 3.52). Significantly more patients required reoperation to treat significant PPR in the SC group compared with the patients in the IN group (p 0.02). Figure 3 demonstrates that most of the reoperations occurred within the first 4 postoperative years, after which the incidence of PPR after AVR was not statistically different between the groups. Although the SC suture technique increased the risk of PPR and redo valve replacements, it did not affect the 10-year survival rate after AVR (Fig 4). Predictors of Survival With Time and Incidence of Paraprosthetic Regurgitation After Valve Replacement Cox regression analysis revealed that after MVR, the age of the patient and impaired left ventricular function predict mortality as a function of time (Table 4). Forward stepwise regression analysis showed that surgeon C, who always used the IN technique, prevented PPR after MVR. After AVR, the age of the patient, nonsinus rhythm (atrial fibrillation or pacemaker rhythm), and redo valve replacement predicted mortality as a function of time (Table 4). Annular calcification was the only significant predictor of PPR after AVR. Comment Paraprosthetic regurgitation is a serious complication after valve replacement operations [2, 3]. In the past, PPR was diagnosed only when patients presented with symptoms of valve regurgitation, heart failure, infective complications, or hemolysis [3, 9]. Nowadays, with the ready availability of echocardiograms, even trivial PPR is detected, probably explaining the 15% incidence in the modern era [2]. Our study specifically looked into the difference in incidence of mild, moderate, or severe PPR in patients who underwent mechanical MVR and AVR using two different suture techniques.

6 1176 NAIR ET AL Ann Thorac Surg SUTURE TECHNIQUE AND PARAPROSTHETIC REGURGITATION 2010;89: Fig 2. Effect of suture technique on survival after aortic valve replacement (AVR). Kaplan-Meier survival curves demonstrating postoperative survival are shown with years on the x axis and the y axis representing percentage survival. The dotted line represents the interrupted technique (IN) suture group and the continuous line represents the semicontinuous technique (SC) suture group. Table of patients at risk of death is shown below the survival curves. Ionescu and colleagues [2] demonstrated that PPR occurs in 6% and 32% of AVR and MVR, respectively. In their study, 6 months after surgery only 56% of patients agreed for a second transesophageal echocardiogram, and the incidence of PPR recorded was 10% and 15% after AVR and MVR, respectively. Two thirds of the aortic and one fifth of the mitral PPR detected at 6 months were new. They also found that the incidence of PPR was more in aortic valves inserted in the supraannular compared with intraannular position, and in the case of mitral valves, when SC suture technique was used compared with IN technique. In this study, PPR was not quantified or graded. None of their patients with PPR underwent reoperation. They concluded that PPR did not affect outcome in a 9-month follow-up period after valve replacement, despite the fact that many of the PPR jets identified at 6 months follow-up were new [2]. Clearly this study did not assess the incidence of PPR in the medium or long-term nor did they grade or quantify the PPR when diagnosed either immediately after surgery or after 6 months. In our study, we have shown that the incidence of mild, moderate, and severe PPR is significantly more after both AVR and MVR when SC suture technique was used compared with IN technique during a 10-year follow-up period. After AVR and MVR, PPR was detected at a median of 378 days (range, 0 to 1,586 days) and 664 days (range, 7 to 1,831 days), respectively. This clearly demonstrates that the risk of developing PPR persists beyond the first year after valve replacement. This observation suggests that annual echocardiograms are important in the follow-up after valve replacement for early diagnosis and timely intervention for PPR. Patients who had AVR and MVR were similar in age, sex distribution, annular calcification, preoperative New York Heart Association grade, left ventricular ejection fraction, valve disease, and left ventricular dimensions. Patients who underwent MVR more-often required concomitant coronary artery bypass grafting compared with those who had their valves replaced using IN sutures. The fact that SC suturing is quicker than IN suture technique might have influenced the surgeons choice of suture technique in combined valve and graft procedures. In subsequent analysis using log-rank (Mantel- Cox) test, we have demonstrated that concomitant coronary artery bypass grafting did not affect survival of

7 Ann Thorac Surg NAIR ET AL 2010;89: SUTURE TECHNIQUE AND PARAPROSTHETIC REGURGITATION 1177 Fig 3. Effect of suture technique on incidence of periprosthetic regurgitation (PPR) after mitral valve replacement (MVR). Graphs represent freedom from periprosthetic regurgitation with different suture techniques. The dotted line represents the interrupted technique (IN) suture group and the continuous line represents the semicontinuous technique (SC) suture group. Table of patients at risk of periprosthetic regurgitation is shown below the curves. patients after either MVR (p 0.74) or AVR (p 0.29; illustrations not included). All patients in our study who had clinically significant PPR (moderate or severe degree) belonged to the SC suture group, irrespective of whether they had AVR or MVR. In our study, SC technique increased the risk of PPR and redo valve surgery after AVR, compared with IN suture technique. Although the incidence of PPR after MVR using the SC suture technique was significantly higher than in the IN suture group, it did not lead to a significant increase in redo valve replacements. This might be related to the inherent reluctance among surgeons to surgically intervene in this high-risk group of patients. Long-term survival after either AVR or MVR was not affected by the type of suture technique used. We further analyzed our data to study whether redo surgery alone increased the risk of mortality in these patients using log-rank (Mantel-Cox) test. This showed that redo valve replacement alone did not affect survival of patients after either MVR (p 0.67) or AVR (p 0.13; illustrations not included). Previous studies have shown timely surgical intervention reduces mortality in significant PPR [4]. We thus would recommend redo valve replacement in clinically significant PPR as the risk of redo valve replacement is relatively insignificant. In our series, Cox regression analysis showed that the predictors of mortality in time after MVR were age of the patient and impaired left ventricular function. Forward stepwise logistic regression of our data showed surgeon C (who always used the IN suture technique) to prevent PPR. Among AVR patients, age, nonsinus rhythm, and redo valve replacement for PPR were predictors of mortality in time. Both suture techniques discussed in this paper have advantages and disadvantages. We believe that the major disadvantage of the SC technique is the increased risk of significant PPR, which continues beyond the first year after surgery. Attention to detail during operation and selective use of SC technique should help in reducing this risk. The advantage of SC technique might be its association with a shorter cross-clamp time, and thus it

8 1178 NAIR ET AL Ann Thorac Surg SUTURE TECHNIQUE AND PARAPROSTHETIC REGURGITATION 2010;89: Fig 4. Effect of suture technique on incidence of periprosthetic regurgitation (PPR) after aortic valve replacement (AVR). Graphs represent freedom from periprosthetic regurgitation with different suture techniques. The dotted line represents the interrupted technique (IN) suture group and the continuous line represents the semicontinuous technique (SC) suture group. Table of patients at risk of periprosthetic regurgitation is shown below the curves. might have benefit in patients with poor left ventricular function. Limitations of the Study Although this study is retrospective in nature, the data including echocardiogram details were collected in a prospective fashion. The suture technique was the operating surgeons choice. The decision to reoperate on symptomatic patients with PPR was made after consultation between the surgeon and cardiologist, taking the clinical urgency into consideration. We have not made comparison between survival with or without redo valve replacement as the numbers in the latter group were few. Being a retrospective study, we could not analyze the incidence or severity of hemolysis associated with PPR. Paraprosthetic regurgitation was quantified purely based on symptoms and annual transthoracic echocardiograms performed. Even though not a randomized group, these data represent the actual situation of PPR after valve replacement. Another limitation of this study is the fact that 5 surgeons were involved in these operations. Detailed statistical analysis failed to show that individual surgeons were independent risk factors for the incidence of PPR. Conclusions Incidence of PPR is significantly more when AVR or MVR is performed using SC technique compared with the IN suture technique. This results in a higher rate of redo valve replacements, particularly after AVR. Thus, SC technique should only be used realizing the increased risk of PPR and its subsequent effect on the prognosis of patients. We wish to thank Andrew Murday, FRCS, Professor Tom Treasure, FRCS, John Smith, FRCS, and the late John Parker, FRCS, for organizing the trial originally from which many patients were included in this analysis. We also wish to acknowledge financial support for part of the study from St. Jude Medical UK, Ltd, and Edwards Lifesciences, Ltd, for providing financial support in the organization of the randomized trial that later contributed to many patients included in this retrospective study.

9 Ann Thorac Surg NAIR ET AL 2010;89: SUTURE TECHNIQUE AND PARAPROSTHETIC REGURGITATION 1179 References 1. Qicai H, Zili C, Zhengfu H, et al. Continuous-suture technique in aortic valve replacement. J Card Surg 2006;21: Ionescu A, Fraser A, Butchart E. Prevalence and clinical significance of incidental paraprosthetic valvar regurgitation: a prospective study using transoesphageal echocardiography. Heart 2003;89: Kloster F. Diagnosis and management of complications of prosthetic heart valves. Am J Cardiol 1975;35: Genoni M, Franzen D, Vogt P, et al. Paravalvular leakage after mitral valve replacement: improved long-term survival with aggressive surgery? Eur J Cardiothorac Surg 2000;17: Dhasmana J, Blackstone E, Kirklin J, Kouchoukos N. Factors associated with periprosthetic leakage following primary mitral valve replacement. With special consideration of the suture technique. Ann Thorac Surg 1983;35: Hjelms E, Vilhelmsen R, Rygg T. Continuous suture technique in prosthetic aortic valve replacement. J Cardiovascular Surg 1982;23: Laks H, Pearl J, Barthei S. Aortic valve replacement using a continuous suture technique. J Card Surg 1993;8: Murday AJ, Hochstitzky A, Mansfield J, et al. A prospective controlled trial of St. Jude versus Starr Edwards aortic and mitral valve prostheses. Ann Thorac Surg 2003;76: Rodgers B, Sabiston D. Hemolytic anemia following prosthetic valve replacement. Circulation 1969;39: Notice From the American Board of Thoracic Surgery The 2010 Part I (written) examination will be held on Monday, November 22, It is planned that the examination will be given at multiple sites throughout the United States using an electronic format. The closing date for registration is August 15, Those wishing to be considered for examination must apply online at To be admissible to the Part II (oral) examination, a candidate must have successfully completed the Part I (written) examination. A candidate applying for admission to the certifying examination must fulfill all the requirements of the Board in force at the time the application is received. Please address all communications to the American Board of Thoracic Surgery, 633 N St. Clair St, Suite 2320, Chicago, IL 60611; telephone: (312) ; fax: (312) ; info@abts.org by The Society of Thoracic Surgeons Ann Thorac Surg 2010;89: /10/$36.00 Published by Elsevier Inc