Minimal Access Aortic Valve Replacement Using a Minimal Extracorporeal Circulatory System

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Minimal Access Aortic Valve Replacement Using a Minimal Extracorporeal Circulatory System Alaadin Yilmaz, MD, Atiq Rehman, MD, Uday Sonker, MD, and Geoffrey T. L. Kloppenburg, MD Department of Cardiothoracic Surgery, St. Antonius Hospital, Nieuwegein, the Netherlands; and Department of Cardiovascular Surgery, Magnolia Regional Health Center, Corinth, Mississippi

Background. Minimal access aortic valve replacement (mAVR) has been demonstrated to be beneficial over standard median sternotomy. Similarly, minimal extracorporeal circulation (MECC) has been shown to have less deleterious effects than conventional cardiopulmonary bypass. We report a previously undescribed technique for AVR in combination with MECC by minimal access. Methods. We prospectively collected data including one-month postoperative follow-up of the first 50 patients who underwent mAVR utilizing MECC. A temporary Cordis Ventricor (Cordis Corp, Miami, FL) ventricular pacemaker and external defibrillation pads were placed at induction. A J-shaped partial upper sternotomy ending in the third intercostal space was performed. Cannulation was performed in the groin using the Seldinger technique. A vent was introduced directly in the pulmonary artery. Warm blood cardioplegia and carbon dioxide field flooding were used. Results. Fifty consecutive patients (24 male) with a mean age of 68 (range, 34 to 89) were operated between

May and December 2007. Operating time was 147 ⴞ 20 minutes, cross-clamp time was 64 ⴞ 10 minutes, and perfusion time was 84 ⴞ 17 minutes. There were no conversions to median sternotomy. Only one peroperative blood transfusion was required and postoperative blood loss was 372 ⴞ 170 cc. Intensive care unit stay was uneventful (average stay 2 days, range 1 to 8). One patient required a permanent pacemaker and other complications included pneumothorax, superficial wound infection, a late transient postoperative neurologic deficit, and excessive postoperative blood loss requiring mediastinal reexploration. Renal failure and major cerebral accidents did not occur. There was a 100% survival at one-month follow-up. Conclusion. We have shown that minimal access aortic valve replacement using minimal extracorporeal circulation is feasible and provides excellent clinical and cosmetic results.

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circulation (MECC) demonstrating reduction in postoperative complications and blood loss. Since then many studies have demonstrated the beneficial effects of MECC in lowering the postoperative inflammatory responses [8, 9]. In addition, AVR by standard median sternotomy utilizing MECC has been shown to have better outcomes than AVR with conventional perfusion techniques [10]. We have combined minimal access AVR with MECC in order to have better clinical outcomes and superior cosmetic results. To our knowledge this is the first series of minimal access AVR in combination with MECC.

ince the early work of Hufnagel and colleagues [1] and Bahnson and colleagues [2] in developing the surgical technique for replacement of diseased aortic valves, a median sternotomy has been used to perform aortic valve replacements (AVR). Over the past ten years minimal access techniques for AVR have been evolving, demonstrating better clinical outcomes by reducing pain, improving cosmetics, reducing bleeding, and allowing earlier functional recovery and a shorter hospital stay, reducing total costs [3, 4]. Until now most of these operations have been performed with conventional cardiopulmonary bypass. Many studies have demonstrated the deleterious effects of cardiopulmonary bypass such as hemodilution and cytokine response, and initiating coagulation cascade [5, 6]. To overcome these drawbacks of cardiopulmonary bypass, Wiesenack and colleagues [7] presented a retrospective series of patients undergoing coronary artery bypass surgery with minimal extracorporeal

Accepted for publication Dec 1, 2008. Address correspondence to Dr Yilmaz, Department of Cardiothoracic Surgery, St. Antonius Hospital, Koekoekslaan 1, P.O. 2500, Nieuwegein, 3430 EM, the Netherlands; e-mail: [email protected]

© 2009 by The Society of Thoracic Surgeons Published by Elsevier Inc

(Ann Thorac Surg 2009;87:720 –5) © 2009 by The Society of Thoracic Surgeons

Material and Methods We have performed over 150 isolated aortic valve replacements utilizing MECC since its introduction in our center in September 2002. Fifty consecutive patients scheduled for AVR by a single surgeon were included in our study. All patients had given adequate informed consent for the minimal access procedure. Our Ethics Committee approved this study and waived the need for individual consent for this study. 0003-4975/09/$36.00 doi:10.1016/j.athoracsur.2008.12.016

Statistical Analysis Data were collected prospectively regarding preoperative physical examination, intraoperative findings, and postoperative follow-up. All data were collected anonymously in an electronic database and the analysis was performed using Windows-Excel (Microsoft Corp, Redmond, WA). The variables are expressed as mean ⫾ standard deviation (SD).

Surgical Procedure General anesthesia using single lumen endotracheal intubation and antibiotic prophylaxis was instituted. The patient was in a supine position and draped sterile with access to the groin. The femoral vessels were exposed through a 3 cm horizontal groin incision. Prior to sternotomy, the common femoral artery was examined digitally for extensive calcifications. Once the femoral artery was confirmed to be of adequate size and quality, the midline sternal incision was made. A 4 to 5 cm median upper sternal skin incision followed by a J-shaped partial sternotomy into the right third intercostal space was performed with an oscillating saw. The pericardium was opened and retracted with stay sutures allowing the exposure of the ascending aorta and examination for any gross calcification. Femoral cannulation followed full heparinization (300 IU/Kg) with a target-activated clotting time above 400 seconds. A dual stage venous 21 to 25 Fr cannula (Cardiovations Inc, Somerville, NJ) was placed under transesophageal echocardiography (TEE) guidance until the tip of the cannula was visible in the superior vena cava using the Seldinger technique. This was followed by insertion of the femoral artery cannula (DLP; Medtronic, Minneapolis, MN) in a similar fashion. Cardiopulmonary bypass was instituted using MECC, with a totally closed circuit and centrifugal perfusion pump (Maquet Inc, Bridgewater, NJ). Retrograde arterial priming of both arterial and venous lines was performed to achieve a priming volume of 0 to 200 cc. No cardiotomy reservoir but only cell saver drainage was used during the procedure. A pulmonary arterial vent (DLP catheter 13 Fr; Medtronic Inc) was inserted using the Seldinger technique, followed by insertion of the aortic root vent. The cross clamp is applied through the main incision, quite close and distal to the root vent. This is important because it facilitates the exposure of the aortic root once the heart is completely emptied. Continuous carbon dioxide (CO2) field flooding was maintained during the entire procedure. Antegrade warm blood cardioplegia (Calafiore technique), through the aortic root vent, was administered. Nasopharyngeal temperature was kept at 34°C. A hockey stick aortotomy was performed. The coronary ostia were identified and antegrade cardioplegia was administered every 15 to 20 minutes. In the presence of aortic valve incompetence selective antegrade cardioplegia was administered similarly through the coronary ostia. The valve was examined and excised, and the annulus sized. The implantation of the valve into the native annulus was performed with interrupted pledget-

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ted sutures in the infraannular position. The valve was checked for appropriate placement, demonstrating a circumferential valvular ring-native annulus-pledget configuration. The aortotomy was then closed in two layers and a right ventricular epicardial pacing lead was placed. Removal of air was performed by the Trendelenburg position, ventilation of the lungs, suction on the root vent to the cell-saver, and stopping the pulmonary artery vent. Once adequate removal of air was obtained “hot shot” reperfusion was performed with a pressure of 150 mm Hg through the aortic root vent, before releasing the cross clamp. The hot shot was administered until there was at least a ventricular rhythm. The patient was weaned from bypass once no significant air in the leftsided chambers of the heart was confirmed on TEE examination. The TEE was also used to assess prosthetic valvular and ventricular function. Decannulation was performed and insertion sites secured. A single silicon (27 Fr) drain was inserted in the pericardium alongside the aorta and the right atrium through a separate parasternal stab incision and secured to the skin. After achieving adequate hemostasis, the sternotomy was closed using three sternal wires and the skin incisions were closed in separate layers. All patients were transferred to the intensive care unit (ICU).

Table 1. Patient Baseline Values Age Gender: Male Female Height Diabetes mellitus Hyperlipidemia Hypertension Smoking history Chronic obstructive pulmonary disease Peripheral vascular disease Cerebrovascular incident Myocardial infarction Conduction abnormalities Previous cardiac procedures: PTCA CABG Pacemaker Miscellaneous: Coarctation of the aorta Laryngeal cancer Bronchial cancer Breast cancer Post endocarditis Protein C deficiency

68 ⫾ 14 years n ⫽ 24 n ⫽ 26 174 ⫾ 11 cm n⫽4 n ⫽ 15 n ⫽ 14 n⫽5 n⫽2 n⫽3 n⫽3 n⫽1 n⫽8 n⫽4 n⫽3 n⫽2 n⫽2 n⫽5 n⫽1 n⫽1 n⫽1 n⫽1 n⫽1 n⫽1

Values are given as mean ⫾ SD or n ⫽ number of patients. CABG ⫽ coronary artery bypass grafting; transluminal coronary angioplasty.

PTCA ⫽ percutaneous

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Results Since May 2007, minimal access AVR using MECC has been performed in over 70 patients. We present the results of the first 50 patients with a one-month followup. Patient demographics are listed in Table 1. The average age was 68 years (range, 34 to 89) with 52% females. Hyperlipidemia (36%) and hypertension (34%) were the most commonly associated cardiac risk factors. There was a wide array of comorbidities such as diabetes mellitus, chronic obstructive pulmonary disease, peripheral vascular disease, previous cerebrovascular accident, and myocardial infarction. Preexisting conduction abnormalities (complete heart block, sick sinus syndrome, atrial fibrillation, right bundle branch block) were present in 16% of the patients and 2 had permanent pacemakers. Two patients had undergone coronary artery bypass grafting (CABG) by median sternotomy with venous bypass grafts in the past. Aortic valve stenosis was present in 98% of the patients with a mean valve area of 0.73 ⫾ 0.17 cm2 and a peak gradient across the valve of 83 ⫾ 21 mm Hg. More than half the patients had associated aortic valve incompetence, mostly grade I-II. Trivial mitral valve insufficiency was present in 17 patients. Table 2. Postoperative Course and Complications Hemoglobin: Preoperative Postoperative Total transfusion requirement: Intraoperative Packed red blood cells Fresh frozen plasma Platelets Postoperative Packed red blood cells Fresh frozen plasma Platelets Length of stay on ICU Mean ventilation time Blood loss Patients with new rhythm abnormalities Atrial fibrillation Complete heart block Pneumothorax (requiring tube thoracostomy) Superficial wound infection Urinary tract infection Neurologic deficit Mediastinal bleeding requiring reexploration One month mortality Stroke/CVA Renal failure Length of stay in hospital CVA ⫽ cerebrovascular accident;

13.5 ⫾ 1.64 g/dL 11.3 ⫾ 1.22 g/dL

1 0 0 15 (0.30 per patient) 8 (0.16 per patient) 3 (0.06 per patient) 2.3 ⫾ 1.6 days 488 ⫾ 315 minutes 372 ⫾ 170 cc 8 7 1 1 1 1 1 1 0 0 0 5.7 ⫾ 3.7 days ICU ⫽ intensive care unit.

There were no conversions to median sternotomy. The mean total operative time was 148 ⫾ 20 minutes. The average cardiopulmonary bypass and cross-clamp times were 84 ⫾ 16 minutes and 64 ⫾ 10 minutes, respectively. A biologic valve (Magna; Edwards Lifesciences, Irvine, CA) was inserted in 37 patients and a mechanical valve (Carbomedics Inc, Sorin Group) was inserted in 13 patients. The mean drop in postoperative hemoglobin was only 2.30 g/dL. Only 1 patient required a single intraoperative blood transfusion because of preoperative anemia. Eighteen percent of the patients needed postoperative blood product transfusion. In total, 15 units of packed red blood cells were transfused postoperatively (0.30 per patient) (Table 2). The mean postoperative ventilation time was 8 hours (range, 1 to 27) and the length of ICU stay was 2.3 ⫾ 1.6 days. The total length of stay in the hospital was 5.7 ⫾ 3.7 days. Postoperative mediastinal blood loss was 372 ⫾ 170 cc. One patient developed a complete heart block and required a permanent pacemaker. Four patients developed other complications such as a pneumothorax (requiring tube thoracostomy), superficial wound infection, urinary tract infection, and a transient neurologic deficit on postoperative day 3, with spontaneous recovery. One patient needed mediastinal reexploration through the partial sternotomy for excessive postoperative blood loss. None of the patients experienced a major stroke or renal failure. There was no mortality at one-month follow-up.

Comment The development of the first heart lung machine by John Gibbon at the University of Minnesota revolutionized cardiac surgery [11]. However, over the years many studies have demonstrated the harmful effects of the cardiopulmonary bypass, including platelet degradation, hemodilution, and a widespread cytokine-mediated inflammatory response affecting all organs. Patients who experience such an inflammatory response often require a longer duration of ventilatory support, have increased postoperative bleeding, and demonstrate increased capillary permeability leading to fluid shifts and multiorgan failure. Recently, a multicenter trial using an anti-C5 monoclonal antibody in patients undergoing combined AVR and CABG demonstrated that decreased immune activation leads to a lower mortality in 180 days [12]. This harmful inflammatory response can be partly attributed to the nonendothelial lining of the pump tubing, the damage to blood contents in the cardiotomy reservoir, and the blood-air interface. This led to the development of the MECC, which was first introduced by the group at the University Hospital of Regensburg [7]. It utilizes a shorter heparin-coated circuit (a meter long tube, decreasing artificial surface area), decreased priming volume as low as 0 to 200 cc (decreases or eliminates hemodilution) and no cardiotomy or venous reservoir (leading to no air-blood contact). In addition the MECC is equipped with a membrane oxygenator that operates at low pressures, decreasing hemolysis. Because the MECC is a totally closed system there is a risk of air embolism

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Fig 1. (A) Male patient 2 days postoperative. (B) Female patient 3 weeks postoperative.

from the venous side, which can produce an airlock. A bubble detector is added to the venous side prior to the centrifugal pump, which detects any air emboli and can be removed by a separate line connected to the cell saver. The heparin coating may prevent thrombin formation and reduce inflammatory response. The MECC has been demonstrated to have a beneficial effect on hemostasis and a decrease in inflammatory markers [13, 14]. Hufnagel and colleagues [1] and Bahnson and colleagues [2] are credited for their pioneering work in the advent of aortic valve surgery. It has been performed by a standard median sternotomy for the last 35 years. The introduction of minimally invasive General Surgery, in the late 1980s, led to an increased interest in minimal access Cardiac Surgery as well. In 1996 Cosgrove and Sabik [15] reported a parasternal approach to AVR, in 1997 Bennetti and colleagues [16] described the right thoracotomy approach, and in 1998 Gundry and colleagues [17] described the partial ministernotomy approach for both adult and pediatric cases. A transverse sternotomy approach was also briefly utilized but quickly abandoned due to unacceptable morbidity and mortality rates [18]. Currently the two most popular approaches are the upper ministernotomy and the right thoracotomy approach [19]. The preserved stability of the lower thoracic cage and increased integrity of pleural cavities allow patients to mobilize early and cough more efficiently, leading to a better preserved lung function after partial upper sternotomy [20]. Our idea is to develop a reproducible technique that can achieve the same clinical outcome as a standard median sternotomy, adding important benefits of reduced pain, better cosmetic results, lesser use of blood products, and shorter hospital stays. In addition there has been evidence that surgical trauma due to full median sternotomy may contribute to the inflammatory response more than the cardiopulmonary bypass itself [21]. There have been published series of conventional AVR with MECC [10, 13], but none, to our knowledge, of combined minimal access AVR with MECC. We would also like to emphasize the novel modifications made to the prevalent technique. The femoral

arteries are cannulated in all cases. It is less common to find significant femoral arterial calcification in isolated aortic valve disease, although it may be present in combined coronary and aortic valve pathology. We always expose the femoral artery before making the sternal skin incision to assure the feasibility of femoral arterial cannulation. In addition we avoid ascending aorta cannulation, preventing any cerebral emboli from the cannulation site and also facilitating a smaller (4 to 5 cm) skin incision. The advantage of an upper partial sternotomy is that it maintains cosmetics (Fig 1) but it can be extended to a full sternotomy expeditiously in case of catastrophe. We insert a pulmonary artery vent in addition to the aortic root vent to decompress the heart adequately, eliminating back bleeding, with less risk of air-blood interference. This line flows into the venous line before its entrance to the centrifugal pump allowing drainage of the blood from the pulmonary artery vent with the same suction pressure as the venous line. The specific techniques employed to avoid blood exposure to air are the following: full emptying of the heart by using aortic and pulmonary vent, then stopping the aortic vent and continuing drainage from the pulmonary vent. The pursestring sutures are doubly enforced. There are concerns expressed that the absence of a venous reservoir may lead to air entrapment and embolization with MECC [22]. However there is a double safety system, with a bubble detector and alarm at the pulmonary artery vent line as well as at the end of the venous line before the oxygenator that can alert the perfusionist, allowing the bubbles to be vented out to the cell saver before reaching the arterial line. The small sternal incision precludes a full view of the mediastinum and thus, in reoperations with a patent mammary, the preferred option would be to identify the mammary graft. However, if it is not exposed adequately, core hypothermia or fibrillating hearth with open mammary may be a viable option. The annular sutures are tied by hand; however, if the suture tying is cumbersome or leads to aortic intimal tears, a knot pusher (Scanlan International, St Paul, MN) may be used to facilitate the suture tying. We prefer to insert the right ventricle epicardial pacing lead under direct vision be-

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cause the percutaneous transjugular pacing lead can interfere or get entangled with the venous cannula. It may also inadvertently perforate the right ventricle. The removal of air has been a matter of concern for some authors. In our experience, continuous CO2 field flooding, placing the patient in the Trendelenburg position before unclamping the aorta, stopping the pulmonary artery vent, hand ventilation to vent out air in the pulmonary tree, and the aortic root vent have been very successful in removing air, as confirmed by TEE examination. There has also been a report of a patient who could not be defibrillated with external pads and thus required an urgent conversion to a full median sternotomy [23]). Tabata and colleagues [24], in a review of 907 patients undergoing upper ministernotomy, had 3 patients with refractory ventricular arrhythmias requiring conversion to a full sternotomy. We had a similar patient who had a prolonged run of ventricular fibrillation postbypass and was refractive to defibrillation with external pads. In this case we successfully defibrillated the patient with pediatric size internal paddles. Hot shot perfusion, under high pressure through the aortic root with the cross clamp on, not only gives us the opportunity to check the aortic suture line but allows the heart to be rearrested with cardioplegia if the patient has refractory fibrillation. Additionally administration of a hot shot led to a prevention of ventricular fibrillation in our experience. We feel that minimal access AVR should be the procedure of choice for all primary isolated aortic valve operations. However, absolute contraindication for the procedure (utilizing MECC) is a septal defect because we have a venous cannula in place and a septal defect can be the source of an air lock through the open aortic root. In addition, there could be relative contraindications such as annular abscess, morbid obesity, femoral artery calcification, and chest wall deformities, although they may be amenable for a minimal access approach with slight modifications. Partial upper sternotomy has been demonstrated allegeable for ascending aortic procedures and redo minimal access AVR [25, 26]. In our own series we have two redo minimal access AVRs. The Brigham group, with one of the largest series [27], has demonstrated successful minimal access AVR in all types of aortic valvular pathology with all kinds of prosthetic valves (ie, biologic, mechanic, and homografts). There has been a report of minimal access repair of the ascending aorta for an intraoperative dissection at the site of the aortic root vent [28]. In addition, the decreased blood loss associated with minimal access AVR facilitated by MECC can be very important in patients of the Jehovah’s Witness faith [29]. In the near future we will have a self-expandable aortic valve prosthesis, which will further facilitate the procedure by decreasing the operative time and avoiding suture tying. As the management of aortic valve disease evolves percutaneous approaches may improve; however, the current data on percutaneous valves demonstrate a 30-day mortality of 30% and a major complication rate of 22% [30]. Thus, in the interim while the percutaneous approach is being perfected, the minimal access

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AVR facilitated by MECC should be the procedure of choice.

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21. Prondzinsky R, Knüpfer A, Loppnow H, et al. Surgical trauma affects the proinflammatory status after cardiac surgery to a higher degree than cardiopulmonary bypass. J Thorac Cardiovasc Surg 2005;129:760 – 6. 22. Remadi JP, Rakotoarivelo Z, Marticho P, Benamar A. Prospective randomised study comparing coronary artery bypass grafting with the new mini-extracorporeal circulation Jostra System or with a standard cardiopulmonary bypass. Am Heart J 2006;151:198. 23. Nagy ZL, Peterffy A. Minimally invasive aortic valve replacement: a word of caution. Ann Thorac Surg 2007;84:1071–2. 24. Tabata M, Umakanthan R, Khalpey Z, et al. Conversion to full sternotomy during minimal access cardiac surgery: reasons and results during a 9.5 year experience. J Thorac Cardiovasc Surg 2007;134:165–9. 25. Tabata M, Khalpey Z, Aranki SF, Couper GS, Cohn LH, Shekar PS. Minimal access surgery of ascending and proximal arch of the aorta: a 9 year experience. Ann Thorac Surg 2007;84:67–72.

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26. Bakir I, Casselman FP, De Geest R, et al. Should minimally invasive aortic valve replacement be restricted to primary interventions? Thorac Cardiovasc Surg 2007;55:304 –9. 27. Mihaljevic T, Cohn LH, Unic D, Aranki SF, Couper GS, Byrne JG. One thousand minimally invasive valve operations: early and late results. Ann Surg 2004;240:529 –34. 28. Tokunaga S, Morita S, Sumiyoshi S, Tominaga R. Management for intraoperative acute aortic dissection during minimally invasive aortic valve replacement. Interact Cardiovasc Thorac Surg 2005;4:595– 6. 29. Varislic C, Bical O, Farge C, et al. Totally minimized extracorporeal circulation: an important benefit for coronary artery bypass grafting in Jehovah’s witnesses. Heart Surg Forum 2003;6:307–10. 30. Grube E, Schuler G, Buellesfeld L, et al. Percutaneous aortic valve replacement for severe aortic stenosis in high-risk patients using the second- and current third-generation self-expanding CoreValve prosthesis: device success and 30-day clinical outcome. J Am Coll Cardiol 2007;50:69 –76.

Requirements for Maintenance of Certification in 2009 Diplomates of the American Board of Thoracic Surgery (ABTS) who plan to participate in the Maintenance of Certification (MOC) process which will begin in 2009 must hold an unrestricted medical license in the locale of their practice and privileges in a hospital accredited by the JCAHO (or other organization recognized by the ABTS). In addition, a valid ABTS certificate is an absolute requirement for entrance into the Maintenance of Certification process. If your certificate has expired, the only pathway for renewal of a certificate is to take and pass the Part I (written) and the Part II (oral) certifying examinations. The names of individuals who have not maintained their certificate will no longer be published in the American Board of Medical Specialties directories. Diplomates’ names will be published upon successful completion of the Maintenance of Certification process. The CME requirements are 30 Category I credits earned during each year prior to application. At least half of these CME hours need to be in the broad area of thoracic surgery. Category II credits are not allowed. Interested individuals should refer to the Booklet of Information for Maintenance of Certification for a complete description of acceptable CME credits. Diplomates in the Maintenance of Certification process will be required to complete all sections of the SESATS

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self-assessment examination. It is not necessary for Diplomates to purchase SESATS individually because it will be sent to them after their application has been approved. Diplomates may apply for Maintenance of Certification in the year their certificate expires, or if they wish to do so, they may apply up to two years before it expires. However, the new certificate will be dated 10 years from the date of expiration of their original certificate or most recent recertification certificate. In other words, going through the Maintenance of Certification process early does not alter the 10-year validation. Diplomates certified prior to 1976 (the year that time-limited certificates were initiated) are also required to participate in MOC if they wish to maintain valid certificates. The deadline for submission of application for the Maintenance of Certification is May 10 of each year. All ABTS diplomates will receive a letter from the Board outlining their individual timeline and MOC requirements. A brochure outlining the rules and requirements for Maintenance of Certification in thoracic surgery is available upon request from the American Board of Thoracic Surgery, 633 North St. Clair St, Suite 2320, Chicago, IL 60611; telephone (312) 202-5900; fax (312) 202-5960; e-mail: [email protected] This booklet is also published on the website: www.abts.org.

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