doi:10.1510/mmcts.2007.002766
Tricuspid valve annuloplasty for functional regurgitation Edwin C. McGee Jr*, Richard Lee, S. Chris Malaisrie, Patrick M. McCarthy Bluhm Cardiovascular Institute, Northwestern Memorial Hospital, Northwestern University’s Feinberg School of Medicine, 201 East Huron St, Suite 11–140, Chicago, IL 60611, USA Functional tricuspid regurgitation (TR) is present in many patients with advanced heart failure. The following manuscript and videos describe our approach to its correction.
Keywords: Annuloplasty; Functional tricuspid regurgitation; Heart failure Introduction
Operative setup
As surgeons we are being asked to operate on an ever increasingly older patient population that often suffers from heart failure. Significant tricuspid regurgitation often exists in this population and contributes to right heart failure. In the majority of these patients, the valve leaflets are normal but leaflets coapt poorly secondary to annular dilatation (Carpentier classification type I) w1x. Several techniques, based on suture annuloplasty, such as the De Vega and Kay repairs, have been described for tricuspid valve repair w2, 3x. It is our preference to use formal ring annuloplasty given its superior durability w4–6x. The manuscript and videos that follow outline our current approach to tricuspid repair using the Edwards MC3 Annuloplasty system.
After systemic heparinization, standard aortic cannulation is accomplished. Bicaval cannulation is carried out of the superior vena cava (SVC) and inferior vena cava (IVC) directly. For most individuals a 24 right angled cannula (Edwards VCCS02490 – MMCTSLink 117) is placed in the SVC and a 26 right angled cannula (Edwards VCS02690 – MMCTSLink 117) is used in the IVC. We usually perform tricuspid procedures as a concomitant procedure at the end of a complex operation. As long as there is no patent foramen ovale, we perform the tricuspid repair with the heart beating. Doing so allows the heart to reperfuse and facilitates prompt separation from bypass once the atrium is closed. If a patent foramen ovale is identified, it is repaired before declamping. For isolated tricuspid procedures it is our preference to repair a patent foramen ovale under a brief period of cardioplegic arrest. Alternatively, a brief period of ventricular fibrillation can be induced to prevent any air entrainment into the left atrium.
Anesthesia A standard anesthetic for cardiac procedures is utilized. A pulmonary artery catheter is placed usually via the right internal jugular vein. A transesophageal echocardiography (TEE) probe is inserted and used to confirm cardiac pathology, and the adequacy of repair post bypass. * Corresponding author: Surgical Director, Heart Transplantation and Mechanical Assistance. Tel.: q1-312-695-0454; fax: q1-312-6951903 E-mail: [email protected] 䉷 2008 European Association for Cardio-thoracic Surgery
After full deairing, tapes are secured about the IVC and SVC to achieve right heart isolation. Should adhesions be significant, SVC isolation can be achieved with a caval clamp. The right atrium is opened with an incision that parallels the atrioventricular (AV) groove down toward the IVC cannulae. For procedures that involve the tricuspid valve, we place our retrograde cardioplegia catheter so that its entry site is incorporated into the atriotomy (Video 1). 1
E.C. McGee Jr et al. / Multimedia Manual of Cardiothoracic Surgery / doi:10.1510/mmcts.2007.002766
Video 1. After right heart isolation, a standard oblique atriotomy is fashioned parallel to the AV groove. Exposure is facilitated by a self retaining retractor.
A self retaining retractor is typically used, although a hand held retractor may suffice. Occasionally, fine pledgeted traction sutures are placed at the edges of the atriotomy to enhance exposure. A flexible weighted vent is placed in the coronary sinus to scavenge blood. Attention is then directed toward the tricuspid valve. The valve is inspected and the pathology addressed. For pure annular dilation a down-sized annuloplasty is all that is required. 2-0 permanent braided sutures are placed about the annulus starting at the anterior leaflet and ending just medial to the coronary sinus and thus avoiding the bundle of His (Schematic 1). The pulmonary artery catheter may be left in place, or temporarily pulled back into the right atrium. Care is taken to avoid passing any sutures through the leaflets. Medial traction on the leaflet displays the annulus. Sutures are placed 2 mm deep and 2 mm from the annulus. Saline irrigation from an assistant is also helpful. Care must be taken against overzealous placement of the first few sutures as the aortic root is in close proximity to the tricuspid annulus in this area. The conduction system is preserved by typically not placing any sutures in the annulus adjacent to the septal leaflet past the medial aspect of the coronary sinus (Video 2). The triangle of Koch, defined by the tendon of Todaro, septal leaflet of the tricuspid valve and coronary sinus, is thus not violated and the conduction system is preserved. Sizing is based on the area of the septal leaflet. Our preference is to use the Edwards MC3 tricuspid annuloplasty ring (MMCTSLink 162), as it takes into account the natural three-dimensional architecture of the tricuspid annulus w7, 8x. Typically we aggressively downsize. Males usually receive a 28 mm ring and females a 26 mm ring. The ring is seated and sutures are tied (Video 3). We start tying first at the septal leaflet as we feel that this area of the annulus is most secure. Passive testing is not as effective as with mitral repair as RV pres2
Schematic 1. Surgical view of the normal and pathologic tricuspid valve. (A) The components of the normal tricuspid valve are shown. Note the location of the coronary sinus, the AV node, and the area to avoid when performing tricuspid surgery (danger zone). (B) A stenotic tricuspid valve, which is most often due to rheumatic disease. Even small degrees of commissural fusion should be incised to increase leaflet mobility. Severe fusions should also be treated conservatively followed by a significant annulus reduction with a smaller ring. Although imperfect competence is to be expected, the results are superior to valve replacement. (C) Functional tricuspid regurgitation. In most cases, the orifice dilation is practically limited to the part of the annulus corresponding to the free wall of the right ventricle. Ring or open band tricuspid annuloplasty returns the dilated portion of the annulus to its correct dimension without reducing the septal area. However, in cases of dilated cardiomyopathies, a ring is preferred to a band and is placed in both the mitral and the tricuspid valves to provide a constraining effect on the heart’s base. Even very moderate degrees of tricuspid regurgitation are treated in these cases. (Reproduced from Duran Carlos MG. Duran ring annuloplasty of the tricuspid valve. Operative Techniques in Thoracic and Cardiovascular Surgery, Vol. 8, Number 4. Copyright 2003, with permission of Elsevier Inc.)
E.C. McGee Jr et al. / Multimedia Manual of Cardiothoracic Surgery / doi:10.1510/mmcts.2007.002766
Video 2. The valve is systematically inspected and the pathology is assessed. Sutures are placed 2 mm deep and 2 mm from the annulus. Suture placement is facilitated by traction on the leaflet with a broad based forceps. An assistant irrigates the field with saline. The AV node is avoided.
Video 3. Sutures are placed through the ring which is then seated. It is often helpful for an assistant to hold the ring against the annulus while the first few sutures are tied. It is not necessary to retain the template/lanyard while tying the sutures.
Video 4. Sutures are cut and the annuloplasty inspected. The PA catheter is repositioned if necessary. The atrium is closed with a double layer closure.
tation coexists with left-sided pathology. These patients often require substantial doses of diuretics to maintain euvolemia. Work by Dreyfus has shown that TR in such patients is progressive and is related to annular size w9x. It has become our policy to address tricuspid regurgitation if 2q or greater TR has been identified by preoperative echocardiography, especially if significant annular dilation is present. We are mindful of intraoperative downgrading. We feel that it is most efficient to perform tricuspid procedures after left-sided work. The heart is allowed to reperfuse and recover from cardioplegic arrest and ischemic time is minimized. Tricuspid annuloplasty is usually straight forward and adds little to the total perfusion time. Once the atrium is closed separation from bypass is typically prompt. The work of several authors has shown that formal ring annuloplasty results in less recurrent TR and is more durable than suture annuloplasty w4–6x (Graph 1). McCarthy reported on a series of 790 patients undergoing tricuspid annuloplasty. Operative mortality was 6%. Even with formal ring annuloplasty using the Carpentier-Edwards ring and the Cosgrove flexible band, significant (3q/4q) TR was present in 14% of patients early after operation w4x. Risk factors for recurrent TR were found to be higher grade of preoperative TR, nonring annuloplasty, presence of a transvalvular pacing lead and decreased left ventricular function. Of note, the operative mortality for recurrent TR was high at 32%, which reflects how compromised patients with longstanding significant TR can be w4x. This paper taught us that reoperation for TR is not to be undertaken lightly. We treat TR
surization is difficult to achieve unless the pulmonary artery is temporarily occluded. Typically some attempt is made to compress the main pulmonary artery and saline is injected through the tricuspid valve. Doing so allows the adequacy of the repair to be inspected (Video 4). We close the often thin atrium with (4-0) polypropylene suture with a fine needle using a double layer closure. Felt and pledgeted material are avoided. Bypass is weaned and the transesophageal echo is inspected to confirm the adequacy of the repair.
Discussion Frequently we are asked to operate on patients with compromised ventricles. Often, some component of biventricular failure and significant tricuspid regurgi-
Graph 1. Freedom from recurrent significant ()3q/4q) TR after various annuloplasty techniques. Formal ring annuloplasty (FB and RR) is associated with less recurrent TR than pericardial (PG) or Suture (DV) annuloplasty. (Reproduced from Ref. 4 with permission from Elsevier.)
3
E.C. McGee Jr et al. / Multimedia Manual of Cardiothoracic Surgery / doi:10.1510/mmcts.2007.002766 2q TR w7, 8x. Operative mortality was 5.3%. Longterm studies will be required to see if these encouraging short-term results stand the test of time.
References
Photo 1. Edwards MC3 Annuloplasty System. The Edwards MC3 annuloplasty system incorporates a unique threedimensional design. (Reproduced with permission from Edwards Lifesciences LLC, Irvine, CA.)
aggressively at the initial operation if it is significant or if we think it will progress. We occasionally use the De Vega technique for prophylactic annuloplasty on the donor heart during heart transplantation, and in patients undergoing left ventricular assist device placement who have significant TR, as it is slightly faster and does not introduce prosthetic material. However, in the vast majority of patients with significant TR, we have found ring annuloplasty simple, expeditious, reproducible, and durable. Recently we have used the Edwards MC3 annuloplasty system (Photo 1). It was developed by the senior author of this manuscript to take into account the three-dimensional geometry of the tricuspid valve with the hope of improving the durability of tricuspid valve repair. The Mt. Sinai group recently reported on a series of 75 patients who underwent tricuspid annuloplasty with the MC3 w7, 8x. Follow-up at up to 16 months demonstrated 28 (62%) of patients with 0 to trace TR, 17 (38%) with 1q TR and 1 patient with
4
w1x Carpentier A. Cardiac valve surgery – the ‘‘French correction’’. J Thorac Cardiovasc Surg 1983;86: 323–337. w2x De Vega NG, De Rabago G, Castillon L, Moreno T, Azpitarte J. A new tricuspid repair. Short-term clinical results in 23 cases. J Cardiovasc Surg (Torino) 1973;Spec No:384–386. w3x Kay GL, Morita S, Mendez M, Zubiate P, Kay JH. Tricuspid regurgitation associated with mitral valve disease: repair and replacement. Ann Thorac Surg 48;1989:(Suppl 3):S93–S95. w4x McCarthy PM, Bhudia SK, Rajeswaran J, Hoercher KJ, Lytle BW, Cosgrove DM, Blackstone EH. Tricuspid valve repair: durability and risk factors for failure. J Thorac Cardiovasc Surg 2004;127:674–685. w5x Rivera R, Duran E, Ajuria M. Carpentier’s flexible ring versus De Vega’s annuloplasty. A prospective randomized study. J Thorac Cardiovasc Surg 1985;89:196–203. w6x Matsuyama K, Matsumoto M, Sugita T, Nishizawa J, Tokuda Y, Matsuo T, Ueda Y. De Vega annuloplasty and Carpentier-Edwards ring annuloplasty for secondary tricuspid regurgitation. J Heart Valve Dis 2001;10:520–524. w7x Filsoufi F, Salzberg SP, Coutu M, Adams DH. A three-dimensional ring annuloplasty for the treatment of tricuspid regurgitation. Ann Thorac Surg 2006;81:2273–2227. w8x Filsoufi F, Salzberg SP, Abascal V, Adams DH. Surgical management of functional tricuspid regurgitation with a new remodeling annuloplasty ring. Mt Sinai J Med 2006;73:874–879. w9x Dreyfus GD, Corbi PJ, Chan KM, Bahrami T. Secondary tricuspid regurgitation or dilatation: which should be the criteria for surgical repair? Ann Thorac Surg 2005;79:127–132.
Tricuspid valve annuloplasty for functional regurgitation Edwin C. McGee Jr*, Richard Lee, S. Chris Malaisrie, Patrick M. McCarthy Bluhm Cardiovascular Institute, Northwestern Memorial Hospital, Northwestern University’s Feinberg School of Medicine, 201 East Huron St, Suite 11–140, Chicago, IL 60611, USA Functional tricuspid regurgitation (TR) is present in many patients with advanced heart failure. The following manuscript and videos describe our approach to its correction.
Keywords: Annuloplasty; Functional tricuspid regurgitation; Heart failure Introduction
Operative setup
As surgeons we are being asked to operate on an ever increasingly older patient population that often suffers from heart failure. Significant tricuspid regurgitation often exists in this population and contributes to right heart failure. In the majority of these patients, the valve leaflets are normal but leaflets coapt poorly secondary to annular dilatation (Carpentier classification type I) w1x. Several techniques, based on suture annuloplasty, such as the De Vega and Kay repairs, have been described for tricuspid valve repair w2, 3x. It is our preference to use formal ring annuloplasty given its superior durability w4–6x. The manuscript and videos that follow outline our current approach to tricuspid repair using the Edwards MC3 Annuloplasty system.
After systemic heparinization, standard aortic cannulation is accomplished. Bicaval cannulation is carried out of the superior vena cava (SVC) and inferior vena cava (IVC) directly. For most individuals a 24 right angled cannula (Edwards VCCS02490 – MMCTSLink 117) is placed in the SVC and a 26 right angled cannula (Edwards VCS02690 – MMCTSLink 117) is used in the IVC. We usually perform tricuspid procedures as a concomitant procedure at the end of a complex operation. As long as there is no patent foramen ovale, we perform the tricuspid repair with the heart beating. Doing so allows the heart to reperfuse and facilitates prompt separation from bypass once the atrium is closed. If a patent foramen ovale is identified, it is repaired before declamping. For isolated tricuspid procedures it is our preference to repair a patent foramen ovale under a brief period of cardioplegic arrest. Alternatively, a brief period of ventricular fibrillation can be induced to prevent any air entrainment into the left atrium.
Anesthesia A standard anesthetic for cardiac procedures is utilized. A pulmonary artery catheter is placed usually via the right internal jugular vein. A transesophageal echocardiography (TEE) probe is inserted and used to confirm cardiac pathology, and the adequacy of repair post bypass. * Corresponding author: Surgical Director, Heart Transplantation and Mechanical Assistance. Tel.: q1-312-695-0454; fax: q1-312-6951903 E-mail: [email protected] 䉷 2008 European Association for Cardio-thoracic Surgery
After full deairing, tapes are secured about the IVC and SVC to achieve right heart isolation. Should adhesions be significant, SVC isolation can be achieved with a caval clamp. The right atrium is opened with an incision that parallels the atrioventricular (AV) groove down toward the IVC cannulae. For procedures that involve the tricuspid valve, we place our retrograde cardioplegia catheter so that its entry site is incorporated into the atriotomy (Video 1). 1
E.C. McGee Jr et al. / Multimedia Manual of Cardiothoracic Surgery / doi:10.1510/mmcts.2007.002766
Video 1. After right heart isolation, a standard oblique atriotomy is fashioned parallel to the AV groove. Exposure is facilitated by a self retaining retractor.
A self retaining retractor is typically used, although a hand held retractor may suffice. Occasionally, fine pledgeted traction sutures are placed at the edges of the atriotomy to enhance exposure. A flexible weighted vent is placed in the coronary sinus to scavenge blood. Attention is then directed toward the tricuspid valve. The valve is inspected and the pathology addressed. For pure annular dilation a down-sized annuloplasty is all that is required. 2-0 permanent braided sutures are placed about the annulus starting at the anterior leaflet and ending just medial to the coronary sinus and thus avoiding the bundle of His (Schematic 1). The pulmonary artery catheter may be left in place, or temporarily pulled back into the right atrium. Care is taken to avoid passing any sutures through the leaflets. Medial traction on the leaflet displays the annulus. Sutures are placed 2 mm deep and 2 mm from the annulus. Saline irrigation from an assistant is also helpful. Care must be taken against overzealous placement of the first few sutures as the aortic root is in close proximity to the tricuspid annulus in this area. The conduction system is preserved by typically not placing any sutures in the annulus adjacent to the septal leaflet past the medial aspect of the coronary sinus (Video 2). The triangle of Koch, defined by the tendon of Todaro, septal leaflet of the tricuspid valve and coronary sinus, is thus not violated and the conduction system is preserved. Sizing is based on the area of the septal leaflet. Our preference is to use the Edwards MC3 tricuspid annuloplasty ring (MMCTSLink 162), as it takes into account the natural three-dimensional architecture of the tricuspid annulus w7, 8x. Typically we aggressively downsize. Males usually receive a 28 mm ring and females a 26 mm ring. The ring is seated and sutures are tied (Video 3). We start tying first at the septal leaflet as we feel that this area of the annulus is most secure. Passive testing is not as effective as with mitral repair as RV pres2
Schematic 1. Surgical view of the normal and pathologic tricuspid valve. (A) The components of the normal tricuspid valve are shown. Note the location of the coronary sinus, the AV node, and the area to avoid when performing tricuspid surgery (danger zone). (B) A stenotic tricuspid valve, which is most often due to rheumatic disease. Even small degrees of commissural fusion should be incised to increase leaflet mobility. Severe fusions should also be treated conservatively followed by a significant annulus reduction with a smaller ring. Although imperfect competence is to be expected, the results are superior to valve replacement. (C) Functional tricuspid regurgitation. In most cases, the orifice dilation is practically limited to the part of the annulus corresponding to the free wall of the right ventricle. Ring or open band tricuspid annuloplasty returns the dilated portion of the annulus to its correct dimension without reducing the septal area. However, in cases of dilated cardiomyopathies, a ring is preferred to a band and is placed in both the mitral and the tricuspid valves to provide a constraining effect on the heart’s base. Even very moderate degrees of tricuspid regurgitation are treated in these cases. (Reproduced from Duran Carlos MG. Duran ring annuloplasty of the tricuspid valve. Operative Techniques in Thoracic and Cardiovascular Surgery, Vol. 8, Number 4. Copyright 2003, with permission of Elsevier Inc.)
E.C. McGee Jr et al. / Multimedia Manual of Cardiothoracic Surgery / doi:10.1510/mmcts.2007.002766
Video 2. The valve is systematically inspected and the pathology is assessed. Sutures are placed 2 mm deep and 2 mm from the annulus. Suture placement is facilitated by traction on the leaflet with a broad based forceps. An assistant irrigates the field with saline. The AV node is avoided.
Video 3. Sutures are placed through the ring which is then seated. It is often helpful for an assistant to hold the ring against the annulus while the first few sutures are tied. It is not necessary to retain the template/lanyard while tying the sutures.
Video 4. Sutures are cut and the annuloplasty inspected. The PA catheter is repositioned if necessary. The atrium is closed with a double layer closure.
tation coexists with left-sided pathology. These patients often require substantial doses of diuretics to maintain euvolemia. Work by Dreyfus has shown that TR in such patients is progressive and is related to annular size w9x. It has become our policy to address tricuspid regurgitation if 2q or greater TR has been identified by preoperative echocardiography, especially if significant annular dilation is present. We are mindful of intraoperative downgrading. We feel that it is most efficient to perform tricuspid procedures after left-sided work. The heart is allowed to reperfuse and recover from cardioplegic arrest and ischemic time is minimized. Tricuspid annuloplasty is usually straight forward and adds little to the total perfusion time. Once the atrium is closed separation from bypass is typically prompt. The work of several authors has shown that formal ring annuloplasty results in less recurrent TR and is more durable than suture annuloplasty w4–6x (Graph 1). McCarthy reported on a series of 790 patients undergoing tricuspid annuloplasty. Operative mortality was 6%. Even with formal ring annuloplasty using the Carpentier-Edwards ring and the Cosgrove flexible band, significant (3q/4q) TR was present in 14% of patients early after operation w4x. Risk factors for recurrent TR were found to be higher grade of preoperative TR, nonring annuloplasty, presence of a transvalvular pacing lead and decreased left ventricular function. Of note, the operative mortality for recurrent TR was high at 32%, which reflects how compromised patients with longstanding significant TR can be w4x. This paper taught us that reoperation for TR is not to be undertaken lightly. We treat TR
surization is difficult to achieve unless the pulmonary artery is temporarily occluded. Typically some attempt is made to compress the main pulmonary artery and saline is injected through the tricuspid valve. Doing so allows the adequacy of the repair to be inspected (Video 4). We close the often thin atrium with (4-0) polypropylene suture with a fine needle using a double layer closure. Felt and pledgeted material are avoided. Bypass is weaned and the transesophageal echo is inspected to confirm the adequacy of the repair.
Discussion Frequently we are asked to operate on patients with compromised ventricles. Often, some component of biventricular failure and significant tricuspid regurgi-
Graph 1. Freedom from recurrent significant ()3q/4q) TR after various annuloplasty techniques. Formal ring annuloplasty (FB and RR) is associated with less recurrent TR than pericardial (PG) or Suture (DV) annuloplasty. (Reproduced from Ref. 4 with permission from Elsevier.)
3
E.C. McGee Jr et al. / Multimedia Manual of Cardiothoracic Surgery / doi:10.1510/mmcts.2007.002766 2q TR w7, 8x. Operative mortality was 5.3%. Longterm studies will be required to see if these encouraging short-term results stand the test of time.
References
Photo 1. Edwards MC3 Annuloplasty System. The Edwards MC3 annuloplasty system incorporates a unique threedimensional design. (Reproduced with permission from Edwards Lifesciences LLC, Irvine, CA.)
aggressively at the initial operation if it is significant or if we think it will progress. We occasionally use the De Vega technique for prophylactic annuloplasty on the donor heart during heart transplantation, and in patients undergoing left ventricular assist device placement who have significant TR, as it is slightly faster and does not introduce prosthetic material. However, in the vast majority of patients with significant TR, we have found ring annuloplasty simple, expeditious, reproducible, and durable. Recently we have used the Edwards MC3 annuloplasty system (Photo 1). It was developed by the senior author of this manuscript to take into account the three-dimensional geometry of the tricuspid valve with the hope of improving the durability of tricuspid valve repair. The Mt. Sinai group recently reported on a series of 75 patients who underwent tricuspid annuloplasty with the MC3 w7, 8x. Follow-up at up to 16 months demonstrated 28 (62%) of patients with 0 to trace TR, 17 (38%) with 1q TR and 1 patient with
4
w1x Carpentier A. Cardiac valve surgery – the ‘‘French correction’’. J Thorac Cardiovasc Surg 1983;86: 323–337. w2x De Vega NG, De Rabago G, Castillon L, Moreno T, Azpitarte J. A new tricuspid repair. Short-term clinical results in 23 cases. J Cardiovasc Surg (Torino) 1973;Spec No:384–386. w3x Kay GL, Morita S, Mendez M, Zubiate P, Kay JH. Tricuspid regurgitation associated with mitral valve disease: repair and replacement. Ann Thorac Surg 48;1989:(Suppl 3):S93–S95. w4x McCarthy PM, Bhudia SK, Rajeswaran J, Hoercher KJ, Lytle BW, Cosgrove DM, Blackstone EH. Tricuspid valve repair: durability and risk factors for failure. J Thorac Cardiovasc Surg 2004;127:674–685. w5x Rivera R, Duran E, Ajuria M. Carpentier’s flexible ring versus De Vega’s annuloplasty. A prospective randomized study. J Thorac Cardiovasc Surg 1985;89:196–203. w6x Matsuyama K, Matsumoto M, Sugita T, Nishizawa J, Tokuda Y, Matsuo T, Ueda Y. De Vega annuloplasty and Carpentier-Edwards ring annuloplasty for secondary tricuspid regurgitation. J Heart Valve Dis 2001;10:520–524. w7x Filsoufi F, Salzberg SP, Coutu M, Adams DH. A three-dimensional ring annuloplasty for the treatment of tricuspid regurgitation. Ann Thorac Surg 2006;81:2273–2227. w8x Filsoufi F, Salzberg SP, Abascal V, Adams DH. Surgical management of functional tricuspid regurgitation with a new remodeling annuloplasty ring. Mt Sinai J Med 2006;73:874–879. w9x Dreyfus GD, Corbi PJ, Chan KM, Bahrami T. Secondary tricuspid regurgitation or dilatation: which should be the criteria for surgical repair? Ann Thorac Surg 2005;79:127–132.
