Ann Thorac Surg 2015;99:1439–42
4.
5. 6. 7. 8.
percutaneous aortic valve implantation. Ann Thorac Surg 2010;89:953–5. Comoglio C, Boffini M, El Qarra S, et al. Aortic valve replacement and mitral valve repair as treatment of complications after percutaneous core valve implantation. J Thorac Cardiovasc Surg 2009;138:1025–7. LaPar DJ, Yang Z, Stukenborg GJ, et al. Outcomes of reoperative aortic valve replacement after previous sternotomy. J Thorac Cardiovasc Surg 2010;139:263–72. Kodali SK, Williams MR, Smith CR, et al. Two-year outcomes after transcatheter or surgical aortic-valve replacement. N Engl J Med 2012;366:1686–95. Smith CR, Leon MB, Mack MJ, et al. Transcatheter versus surgical aortic-valve replacement in high-risk patients. N Engl J Med 2011;364:2187–98. Nielsen HH, Klaaborg KE, Nissen H, et al. A prospective, randomised trial of transapical transcatheter aortic valve implantation vs. surgical aortic valve replacement in operable elderly patients with aortic stenosis: the STACCATO trial. EuroIntervention 2012;8:383–9.
Transcatheter Mitral “Valve-in-Ring” Implantation: A Word of Caution Ricardo Allende, MD, Daniel Doyle, MD, Marina Urena, MD, Henrique B. Ribeiro, MD, Ignacio J. Amat-Santos, MD, Mathieu Bernier, MD, Sergio Pasian, MD, Robert DeLarochelli ere, MD, Eric Dumont, MD, and Josep Rod es-Cabau, MD
Transcatheter mitral valve-in-valve and valve-in-ring procedures have emerged as a potential alternative for patients with failed mitral bioprosthesis or mitral valve repair who are at very high or prohibitive surgical risk. However, transcatheter mitral valve-in-ring implantation (TMViRI) remains a challenging procedure, partially because of the oval shape of mitral rings, which may lead to prosthesis dysfunction when the ring is not able to adopt the circular shape of the transcatheter valve. We present a case of failed TMViRI in a dysfunctional mitral homograft. The potential factors leading to procedural failure are discussed. (Ann Thorac Surg 2015;99:1439–42) Ó 2015 by The Society of Thoracic Surgeons
S
everal series have shown the feasibility of transcatheter mitral valve-in-valve and transcatheter mitral valve-in-ring implantation (TMViRI), which have emerged as potential therapeutic alternatives for highrisk patients with failed mitral bioprosthesis or mitral valve repair [1–3]. We report a case of failed TMViRI in a
Accepted for publication June 2, 2014. Address correspondence to Dr Rod es-Cabau, Quebec Heart & Lung Institute, 2725 Chemin Ste-Foy, G1V 4G5 Quebec city, QC, Canada; e-mail: [email protected].
Ó 2015 by The Society of Thoracic Surgeons Published by Elsevier
1439
mitral homograft resulting in severe mitral stenosis and regurgitation. A 65-year-old woman was admitted to the hospital because of heart failure. The patient had undergone a multistage cardiac valve surgical procedure with a mitral commissurotomy in 1974 and mitral and aortic valve replacement in 2000 with a 28-mm Carpentier-Edwards Physio Annuloplasty Ring (Baxter-Edwards Lifesciences, Irvine, CA) and a 31-mm cryopreserved homograft (Cryolife Inc, Kennesaw, GA) in the mitral position and a 23-mm cryopreserved homograft valved conduit in the aortic position (Cryolife Inc). An echocardiogram showed a dysfunction of both homografts (Figs 1A-1E). The estimated risk of perioperative mortality as assessed by EuroSCORE II was 12%. Computed tomographic images are shown in Figure 1F-K. The risk of periprocedural mortality associated with double valve replacement was considered too high, and a TMViRI and aortic valve-invalve implantation by a transapical approach was proposed. The limited evidence on mitral valve-in-ring procedures was clearly explained when written informed consent was obtained from the patient. After performance of a left thoracotomy, a stiff wire was placed in the right pulmonary vein, and a 29-mm Edwards Sapien valve (Edwards Lifesciences, Irvine, CA) was positioned about half above and half below with respect to the mitral ring, and the valve was deployed by balloon inflation under rapid pacing (Fig 2A, B). Then, the stiff wire was positioned in the descending aorta, and a 23-mm Edwards Sapien valve was implanted in an aortic position (Fig 2C, D). Perioperative echocardiographic images showed normal function of the aortic bioprosthesis but an oval-shaped mitral bioprosthesis with severe stenosis (mean gradient 12 mm Hg) and moderate mitral regurgitation (Fig 3). The postoperative period coursed with mild heart failure, and the patient was discharged 5 days after the intervention with a follow-up appointment. At her 3-month follow-up visit, the patient had hemolytic anemia and remained in New York Heart Association (NYHA) class III. Echocardiographic images confirmed the normal function of the aortic bioprosthesis and a severe stenosis of the mitral bioprosthesis (mean gradient 12 mm Hg; area 0.70 cm2) with moderate mitral regurgitation. Surgical valve replacement and removal of the prosthetic mitral valve were performed (Figs 4A, 4B), and a 25-mm St Jude mechanical prosthesis (St Jude Medical Inc, Minneapolis, MN) was implanted. The postoperative evolution was uneventful. Six months afterward, the patient was in NYHA class I, and an echocardiogram demonstrated proper function of the mitral prosthesis (mean gradient 4 mm Hg, no mitral regurgitation) and a marked decrease in pulmonary artery pressure (35 mm Hg).
Dr Rodes-Cabau discloses financial relationships with Edwards Lifesciences and St Jude; and Dr Dumont with Edwards Lifesciences.
0003-4975/$36.00 http://dx.doi.org/10.1016/j.athoracsur.2014.06.083
FEATURE ARTICLES
Quebec Heart & Lung Institute, Laval University, Quebec City, Quebec, Canada
CASE REPORT ALLENDE ET AL FAILED MITRAL VALVE-IN-RING PROCEDURE
CASE REPORT ALLENDE ET AL FAILED MITRAL VALVE-IN-RING PROCEDURE
Ann Thorac Surg 2015;99:1439–42
FEATURE ARTICLES
1440
Fig 1. Echocardiographic two-dimensional and three-dimensional images showing (A) a dysfunctional mitral homograft with severe insufficiency and (B) stenosis and (C) the oval shape of the mitral ring. Fluoroscopic images showing (D) a severely calcified aortic valved conduit with (E) severe aortic regurgitation. Computed tomographic volume-rendered images and reconstructions showing (F) severe calcification of the aortic valved conduit, (G) dimensions of the aortic annulus, (H, I) inner and outer diameters of the mitral ring, (J) the saddle shape of the mitral ring, and (K) the presence of severe peripheral vascular disease.
Comment The Carpentier-Edwards Physio ring is composed of Elgiloy, a cobalt-chromiun alloy, with bands separated by polyester film bands [4]. Although the anterior section of this ring is rigid, the posterior section is flexible, allowing transversal (but not longitudinal) deformation [4]. It has been previously described that these rings become rounded after the TMViRI [2, 3]. However, TMViRI did not change the shape of the ring in our case, suggesting that several factors may have an impact on the response of such rings to the radial force exerted by the stent frame of the transcatheter valve [5]. Accurate sizing of the valve is crucial in both valve-invalve and valve-in-ring procedures. However, the valve
sizing process remains one of the most challenging aspects of the procedure; indeed, the optimal degree of oversizing for TMViRI remains to be elucidated [1, 3]. The degree of prosthesis oversizing in this case was greater than that reported in most previous studies [2], and this probably contributed to the prosthesis-patient mismatch. However, the largest inner diameter of the ring was measured at 25 mm, and this determined the implantation of a 29-mm transcatheter valve to ensure appropriate sealing of the mitral annulus. Furthermore, a successful 29-mm Edwards Sapien valve implantation in a patient with a 28-mm Carpentier-Edwards Physio ring has been previously reported [3]. Interestingly, the mitral ring was implanted approximately 12 years before the transcatheter procedure, whereas this time period was
Ann Thorac Surg 2015;99:1439–42
CASE REPORT ALLENDE ET AL FAILED MITRAL VALVE-IN-RING PROCEDURE
1441
Fig 2. Fluoroscopic images showing (A, B) steps of TMViRI and (C, D) aortic valve-invalve implantation: (A) Note the incomplete filling and the waist in the middle of the balloon during mitral valve deployment suggesting excessive oversizing of the prosthesis and (B) the unchanged oval shape of the mitral ring after transcatheter valve implantation. (C) Implantation of the aortic prosthesis with the complete expansion of the balloon and (D) absence of aortic regurgitation.
FEATURE ARTICLES
Fig 3. Echocardiographic 2D and 3D images showing results of transcatheter mitral valvein-ring implantation. (A) Note the moderate mitral regurgitation with (B, C) three mitral leaks (two paravalvular and one central) and (D) the oval shape of the transcatheter valve.
1442
CASE REPORT LOU ET AL CORONARY ARTERY DISSECTION IN FMD
Ann Thorac Surg 2015;99:1442–4
FEATURE ARTICLES
Fig 4. (A) Incomplete expansion of the transcatheter valve prosthesis in situ and (B) its oval shape to conform to the mitral ring, after explantation. (B) Note the unchanged oval contour of the mitral ring.
less than 10 years in most previous studies [2]. This might have had an impact on the flexibility of the ring owing to potential material fatigue. Finally, the patient had a mitral homograft in addition to the ring, and a potential influence of the homograft on the suboptimal deployment of the transcatheter valve cannot be excluded. In conclusion, the feasibility of TMViRI has been described, although this procedure remains experimental. The present report shows that this treatment can fail in some patients. Both an excessive transcatheter valve oversizing and the inability of the ring to adopt a circular shape may have played a major role in the failure of the procedure. Careful evaluation of the case, including ring properties and appropriate valve sizing, are mandatory to obtain a good result. However, more data are needed to determine the best method for accurate sizing of the mitral annulus, to predict ring deformability and ultimately to identify potential factors influencing procedural success, especially in the presence of a mitral homograft.
References 1. Cheung A, Webb JG, Barbanti M, et al. 5-year experience with transcatheter transapical mitral valve-in-valve implantation for bioprosthetic valve dysfunction. J Am Coll Cardiol 2013;61: 1759–66. 2. Descoutures F, Himbert D, Maisano F, et al. Transcatheter valve-in-ring implantation after failure of surgical mitral repair. Eur J Cardiothorac Surg 2013;44:e8–15. 3. Wilbring M, Alexiou K, Tugtekin SM, et al. Pushing the limits: further evolutions of transcatheter valve procedures in the mitral position, including valve-in-valve, valve-in-ring, and valve-in-native-ring. J Thorac Cardiovasc Surg 2014;147:210–9. 4. Carpentier AF, Lessana A, Relland JY, et al. The “physioring”: an advanced concept in mitral valve annuloplasty. Ann Thorac Surg 1995;60:1177–85. 5. Tavlasoglu M, Durukan AB, Kurkluoglu M. Can valved mitral prosthesis be implanted within all kinds of the mitral annuloplasty rings? Catheter Cardiovasc Interv 2013;81:172. Ó 2015 by The Society of Thoracic Surgeons Published by Elsevier
Intraoperative Coronary Artery Dissection in Fibromuscular Dysplasia Xiaoying Lou, BS, Sumeet S. Mitter, MD, John E. Blair, MD, Keith Benzuly, MD, Ivancarmine Gambardella, MD, and S. Chris Malaisrie, MD Department of Cardiothoracic Surgery, Northwestern University, Chicago, Illinois
A 61-year-old woman with bicuspid aortic stenosis, an ascending aortic aneurysm, and a remote history of renal fibromuscular dysplasia underwent aortic root replacement complicated by extensive dissection of the left circumflex artery extending retrograde into the left anterior descending artery. This was managed by coronary artery bypass grafting, left ventricular support, and percutaneous coronary intervention for propagation of the dissection. This case highlights the prevalence, diagnosis, and management of intraoperative coronary dissection secondary to fibromuscular dysplasia. (Ann Thorac Surg 2015;99:1442–4) Ó 2015 by The Society of Thoracic Surgeons
F
ibromuscular dysplasia (FMD) is a nonatherosclerotic, noninflammatory vascular disease that may lead to stenosis, occlusion, aneurysm, and dissection. Although the prevalence of FMD in the general Accepted for publication June 13, 2014. Address correspondence to Dr Malaisrie, Department of Cardiothoracic Surgery, Northwestern University, 675 N St. Clair, Galter 19-100, Chicago, IL 60611; e-mail: [email protected].
0003-4975/$36.00 http://dx.doi.org/10.1016/j.athoracsur.2014.06.107
4.
5. 6. 7. 8.
percutaneous aortic valve implantation. Ann Thorac Surg 2010;89:953–5. Comoglio C, Boffini M, El Qarra S, et al. Aortic valve replacement and mitral valve repair as treatment of complications after percutaneous core valve implantation. J Thorac Cardiovasc Surg 2009;138:1025–7. LaPar DJ, Yang Z, Stukenborg GJ, et al. Outcomes of reoperative aortic valve replacement after previous sternotomy. J Thorac Cardiovasc Surg 2010;139:263–72. Kodali SK, Williams MR, Smith CR, et al. Two-year outcomes after transcatheter or surgical aortic-valve replacement. N Engl J Med 2012;366:1686–95. Smith CR, Leon MB, Mack MJ, et al. Transcatheter versus surgical aortic-valve replacement in high-risk patients. N Engl J Med 2011;364:2187–98. Nielsen HH, Klaaborg KE, Nissen H, et al. A prospective, randomised trial of transapical transcatheter aortic valve implantation vs. surgical aortic valve replacement in operable elderly patients with aortic stenosis: the STACCATO trial. EuroIntervention 2012;8:383–9.
Transcatheter Mitral “Valve-in-Ring” Implantation: A Word of Caution Ricardo Allende, MD, Daniel Doyle, MD, Marina Urena, MD, Henrique B. Ribeiro, MD, Ignacio J. Amat-Santos, MD, Mathieu Bernier, MD, Sergio Pasian, MD, Robert DeLarochelli ere, MD, Eric Dumont, MD, and Josep Rod es-Cabau, MD
Transcatheter mitral valve-in-valve and valve-in-ring procedures have emerged as a potential alternative for patients with failed mitral bioprosthesis or mitral valve repair who are at very high or prohibitive surgical risk. However, transcatheter mitral valve-in-ring implantation (TMViRI) remains a challenging procedure, partially because of the oval shape of mitral rings, which may lead to prosthesis dysfunction when the ring is not able to adopt the circular shape of the transcatheter valve. We present a case of failed TMViRI in a dysfunctional mitral homograft. The potential factors leading to procedural failure are discussed. (Ann Thorac Surg 2015;99:1439–42) Ó 2015 by The Society of Thoracic Surgeons
S
everal series have shown the feasibility of transcatheter mitral valve-in-valve and transcatheter mitral valve-in-ring implantation (TMViRI), which have emerged as potential therapeutic alternatives for highrisk patients with failed mitral bioprosthesis or mitral valve repair [1–3]. We report a case of failed TMViRI in a
Accepted for publication June 2, 2014. Address correspondence to Dr Rod es-Cabau, Quebec Heart & Lung Institute, 2725 Chemin Ste-Foy, G1V 4G5 Quebec city, QC, Canada; e-mail: [email protected].
Ó 2015 by The Society of Thoracic Surgeons Published by Elsevier
1439
mitral homograft resulting in severe mitral stenosis and regurgitation. A 65-year-old woman was admitted to the hospital because of heart failure. The patient had undergone a multistage cardiac valve surgical procedure with a mitral commissurotomy in 1974 and mitral and aortic valve replacement in 2000 with a 28-mm Carpentier-Edwards Physio Annuloplasty Ring (Baxter-Edwards Lifesciences, Irvine, CA) and a 31-mm cryopreserved homograft (Cryolife Inc, Kennesaw, GA) in the mitral position and a 23-mm cryopreserved homograft valved conduit in the aortic position (Cryolife Inc). An echocardiogram showed a dysfunction of both homografts (Figs 1A-1E). The estimated risk of perioperative mortality as assessed by EuroSCORE II was 12%. Computed tomographic images are shown in Figure 1F-K. The risk of periprocedural mortality associated with double valve replacement was considered too high, and a TMViRI and aortic valve-invalve implantation by a transapical approach was proposed. The limited evidence on mitral valve-in-ring procedures was clearly explained when written informed consent was obtained from the patient. After performance of a left thoracotomy, a stiff wire was placed in the right pulmonary vein, and a 29-mm Edwards Sapien valve (Edwards Lifesciences, Irvine, CA) was positioned about half above and half below with respect to the mitral ring, and the valve was deployed by balloon inflation under rapid pacing (Fig 2A, B). Then, the stiff wire was positioned in the descending aorta, and a 23-mm Edwards Sapien valve was implanted in an aortic position (Fig 2C, D). Perioperative echocardiographic images showed normal function of the aortic bioprosthesis but an oval-shaped mitral bioprosthesis with severe stenosis (mean gradient 12 mm Hg) and moderate mitral regurgitation (Fig 3). The postoperative period coursed with mild heart failure, and the patient was discharged 5 days after the intervention with a follow-up appointment. At her 3-month follow-up visit, the patient had hemolytic anemia and remained in New York Heart Association (NYHA) class III. Echocardiographic images confirmed the normal function of the aortic bioprosthesis and a severe stenosis of the mitral bioprosthesis (mean gradient 12 mm Hg; area 0.70 cm2) with moderate mitral regurgitation. Surgical valve replacement and removal of the prosthetic mitral valve were performed (Figs 4A, 4B), and a 25-mm St Jude mechanical prosthesis (St Jude Medical Inc, Minneapolis, MN) was implanted. The postoperative evolution was uneventful. Six months afterward, the patient was in NYHA class I, and an echocardiogram demonstrated proper function of the mitral prosthesis (mean gradient 4 mm Hg, no mitral regurgitation) and a marked decrease in pulmonary artery pressure (35 mm Hg).
Dr Rodes-Cabau discloses financial relationships with Edwards Lifesciences and St Jude; and Dr Dumont with Edwards Lifesciences.
0003-4975/$36.00 http://dx.doi.org/10.1016/j.athoracsur.2014.06.083
FEATURE ARTICLES
Quebec Heart & Lung Institute, Laval University, Quebec City, Quebec, Canada
CASE REPORT ALLENDE ET AL FAILED MITRAL VALVE-IN-RING PROCEDURE
CASE REPORT ALLENDE ET AL FAILED MITRAL VALVE-IN-RING PROCEDURE
Ann Thorac Surg 2015;99:1439–42
FEATURE ARTICLES
1440
Fig 1. Echocardiographic two-dimensional and three-dimensional images showing (A) a dysfunctional mitral homograft with severe insufficiency and (B) stenosis and (C) the oval shape of the mitral ring. Fluoroscopic images showing (D) a severely calcified aortic valved conduit with (E) severe aortic regurgitation. Computed tomographic volume-rendered images and reconstructions showing (F) severe calcification of the aortic valved conduit, (G) dimensions of the aortic annulus, (H, I) inner and outer diameters of the mitral ring, (J) the saddle shape of the mitral ring, and (K) the presence of severe peripheral vascular disease.
Comment The Carpentier-Edwards Physio ring is composed of Elgiloy, a cobalt-chromiun alloy, with bands separated by polyester film bands [4]. Although the anterior section of this ring is rigid, the posterior section is flexible, allowing transversal (but not longitudinal) deformation [4]. It has been previously described that these rings become rounded after the TMViRI [2, 3]. However, TMViRI did not change the shape of the ring in our case, suggesting that several factors may have an impact on the response of such rings to the radial force exerted by the stent frame of the transcatheter valve [5]. Accurate sizing of the valve is crucial in both valve-invalve and valve-in-ring procedures. However, the valve
sizing process remains one of the most challenging aspects of the procedure; indeed, the optimal degree of oversizing for TMViRI remains to be elucidated [1, 3]. The degree of prosthesis oversizing in this case was greater than that reported in most previous studies [2], and this probably contributed to the prosthesis-patient mismatch. However, the largest inner diameter of the ring was measured at 25 mm, and this determined the implantation of a 29-mm transcatheter valve to ensure appropriate sealing of the mitral annulus. Furthermore, a successful 29-mm Edwards Sapien valve implantation in a patient with a 28-mm Carpentier-Edwards Physio ring has been previously reported [3]. Interestingly, the mitral ring was implanted approximately 12 years before the transcatheter procedure, whereas this time period was
Ann Thorac Surg 2015;99:1439–42
CASE REPORT ALLENDE ET AL FAILED MITRAL VALVE-IN-RING PROCEDURE
1441
Fig 2. Fluoroscopic images showing (A, B) steps of TMViRI and (C, D) aortic valve-invalve implantation: (A) Note the incomplete filling and the waist in the middle of the balloon during mitral valve deployment suggesting excessive oversizing of the prosthesis and (B) the unchanged oval shape of the mitral ring after transcatheter valve implantation. (C) Implantation of the aortic prosthesis with the complete expansion of the balloon and (D) absence of aortic regurgitation.
FEATURE ARTICLES
Fig 3. Echocardiographic 2D and 3D images showing results of transcatheter mitral valvein-ring implantation. (A) Note the moderate mitral regurgitation with (B, C) three mitral leaks (two paravalvular and one central) and (D) the oval shape of the transcatheter valve.
1442
CASE REPORT LOU ET AL CORONARY ARTERY DISSECTION IN FMD
Ann Thorac Surg 2015;99:1442–4
FEATURE ARTICLES
Fig 4. (A) Incomplete expansion of the transcatheter valve prosthesis in situ and (B) its oval shape to conform to the mitral ring, after explantation. (B) Note the unchanged oval contour of the mitral ring.
less than 10 years in most previous studies [2]. This might have had an impact on the flexibility of the ring owing to potential material fatigue. Finally, the patient had a mitral homograft in addition to the ring, and a potential influence of the homograft on the suboptimal deployment of the transcatheter valve cannot be excluded. In conclusion, the feasibility of TMViRI has been described, although this procedure remains experimental. The present report shows that this treatment can fail in some patients. Both an excessive transcatheter valve oversizing and the inability of the ring to adopt a circular shape may have played a major role in the failure of the procedure. Careful evaluation of the case, including ring properties and appropriate valve sizing, are mandatory to obtain a good result. However, more data are needed to determine the best method for accurate sizing of the mitral annulus, to predict ring deformability and ultimately to identify potential factors influencing procedural success, especially in the presence of a mitral homograft.
References 1. Cheung A, Webb JG, Barbanti M, et al. 5-year experience with transcatheter transapical mitral valve-in-valve implantation for bioprosthetic valve dysfunction. J Am Coll Cardiol 2013;61: 1759–66. 2. Descoutures F, Himbert D, Maisano F, et al. Transcatheter valve-in-ring implantation after failure of surgical mitral repair. Eur J Cardiothorac Surg 2013;44:e8–15. 3. Wilbring M, Alexiou K, Tugtekin SM, et al. Pushing the limits: further evolutions of transcatheter valve procedures in the mitral position, including valve-in-valve, valve-in-ring, and valve-in-native-ring. J Thorac Cardiovasc Surg 2014;147:210–9. 4. Carpentier AF, Lessana A, Relland JY, et al. The “physioring”: an advanced concept in mitral valve annuloplasty. Ann Thorac Surg 1995;60:1177–85. 5. Tavlasoglu M, Durukan AB, Kurkluoglu M. Can valved mitral prosthesis be implanted within all kinds of the mitral annuloplasty rings? Catheter Cardiovasc Interv 2013;81:172. Ó 2015 by The Society of Thoracic Surgeons Published by Elsevier
Intraoperative Coronary Artery Dissection in Fibromuscular Dysplasia Xiaoying Lou, BS, Sumeet S. Mitter, MD, John E. Blair, MD, Keith Benzuly, MD, Ivancarmine Gambardella, MD, and S. Chris Malaisrie, MD Department of Cardiothoracic Surgery, Northwestern University, Chicago, Illinois
A 61-year-old woman with bicuspid aortic stenosis, an ascending aortic aneurysm, and a remote history of renal fibromuscular dysplasia underwent aortic root replacement complicated by extensive dissection of the left circumflex artery extending retrograde into the left anterior descending artery. This was managed by coronary artery bypass grafting, left ventricular support, and percutaneous coronary intervention for propagation of the dissection. This case highlights the prevalence, diagnosis, and management of intraoperative coronary dissection secondary to fibromuscular dysplasia. (Ann Thorac Surg 2015;99:1442–4) Ó 2015 by The Society of Thoracic Surgeons
F
ibromuscular dysplasia (FMD) is a nonatherosclerotic, noninflammatory vascular disease that may lead to stenosis, occlusion, aneurysm, and dissection. Although the prevalence of FMD in the general Accepted for publication June 13, 2014. Address correspondence to Dr Malaisrie, Department of Cardiothoracic Surgery, Northwestern University, 675 N St. Clair, Galter 19-100, Chicago, IL 60611; e-mail: [email protected].
0003-4975/$36.00 http://dx.doi.org/10.1016/j.athoracsur.2014.06.107
