Ischemic mitral regurgitation (IMR) is an insufficiency of

Transcription

1 Repair Techniques for Ischemic Mitral Regurgitation Damien J. LaPar, MD, MSc, and Irving L. Kron, MD Ischemic mitral regurgitation (IMR) is an insufficiency of the mitral valve (MV) secondary to myocardial ischemia and coronary artery disease and occurs in the absence of degenerative (structural) mitral valve disease. The underlying pathophysiologic mechanisms of IMR are often complex, resulting from structural changes involving left ventricular geometry, the mitral annulus, and the valvular/subvalvular apparatus. Moderate to severe IMR typically occurs due to several anatomic changes. These changes result in clinically significant valve incompetence due to the combined effects of decreased ventricular function and restricted motion of the valve itself due to tethering. Recent estimates suggest that IMR occurs in nearly 20%- 30% of patients following myocardial infarction. 1,2 IMR has a strong association with heart failure, and suboptimal medical management of heart failure further complicates the management of clinically significant IMR. In fact, moderate or severe mitral regurgitation (MR) may be associated with a 3-fold increase in the adjusted risk of heart failure and a 1.6-fold increase in risk-adjusted mortality at 5 years. 3 The presence of concomitant comorbid disease, including renal failure, chronic obstructive pulmonary disease, diabetes, and impaired left ventricular function, 4 further increases the risk of patient morbidity and mortality. The surgical management of IMR has historically been associated with poor outcomes; however, recent series have demonstrated improvements in morbidity and mortality. Many contemporary series report mortality rates of 5% following surgical correction of IMR. 5-9 Current surgical options for IMR include myocardial revascularization alone with coronary artery bypass grafting (CABG), mitral valve replacement (MVR) with concomitant CABG, or MV repair with CABG. Among MV repair techniques, restrictive ring annuloplasty remains the most common and is our preferred initial approach to restoring the geometry and function of the affected MV. An alternative repair technique that we employ Division of Thoracic and Cardiovascular Surgery, Department of Surgery, University of Virginia, Charlottesville, VA. Address reprint requests to Irving L. Kron, MD, Professor of Surgery and Chair, Department of Surgery, University of Virginia, PO Box , Charlottesville, VA ilk@virginia.edu is the use of a posterior papillary muscle traction suture placed through the mitral annulus that is used to reduce the effects of cord tethering and a loss of MV leaflet coaptation. In our experience, we have found that the combined use of these techniques corrects the majority of clinically significant (2 or greater) IMR. Although outcomes and opinions remain mixed as to the efficacy of mitral replacement vs repair for IMR, increasing support for the performance of mitral repair over replacement has emerged in recent years. Mantovani and colleagues reported that both prosthetic MVR and MV repair offer very similar results for chronic IMR, demonstrating similar operative mortality and 5-year actuarial survival for both techniques. 10 Similarly, Magne and colleagues demonstrated lower operative mortality for MV repair compared to MVR (9.7% vs 17.4%, P 0.03) with equivalent long-term survival. 11 In our own experience, we have demonstrated that mitral repair with concomitant CABG is associated with improved mortality and outcomes compared to MVR with CABG, 12 and that MV repair for IMR does not increase morbidity and mortality compared to MVR. 4 Our findings are in agreement with other series favoring the performance of MV repair for functional IMR. Although restrictive annuloplasty remains the most commonly performed repair technique, 13 it has been shown to be beneficial in both functional and chronic IMR. 14 Overall, improved survival, decreased valverelated morbidity, and improved left ventricular function have been previously established, and several series have reported lower hospital mortality with MV repair compared to MVR. 7,9,12,15-18 Herein, we describe our surgical approach to the repair of the ischemic MV and subvalvular apparatus. Although we do not illustrate the performance of concomitant CABG in this article, myocardial revascularization remains critical to the long-term success of the surgical correction of IMR and should occur at the time of mitral repair. With respect to the performance of ring annuloplasty, we prefer the use of semirigid complete annuloplasty rings, and we have recently departed from the routine practice of significantly downsizing the annuloplasty ring by 2 sizes. We now favor downsizing the annuloplasty ring by 1 size to avoid tension /$-see front matter 2012 Elsevier Inc. All rights reserved.

2 Repair techniques for ischemic mitral regurgitation 205 Operative Technique Figure 1 After standard preoperative preparation, including arterial and central venous monitoring, intraoperative transesophageal echocardiography is performed to carefully assess the mechanism of MR. It is our practice to routinely repair 2 MR. CABG harvesting is performed as most patients require concomitant myocardial revascularization. Our preference is to perform endoscopic harvesting for all saphenous vein grafts. Harvesting of the left internal thoracic artery is performed in the usual surgical fashion following full median sternotomy. After pericardotomy, cardiopulmonary bypass is established using standard aortic and bicaval cannulation with vacuum-assisted venous drainage and a combination of both antegrade and retrograde cardioplegia. Distal coronary anastomoses are then performed. Antegrade cardioplegia down the grafts is then performed every 15 minutes to ensure myocardial protection. Next, traction is placed on the umbilical tape passed around the inferior vena cava, elevating the right side of the heart and facilitating surgical access to the left atrium and mitral valve. A left atriotomy is then performed beginning at the junction of the left atrium and right superior pulmonary vein, which is extended from under the superior vena cava to the inferior vena cava, exposing the entire mitral valve. We then utilize a Cosgrove self-retaining mitral retractor, and the operating table is rotated to the left away from the surgeon. IVC inferior vena cava; SVC superior vena cava.

3 206 D. J. LaPar and I.L. Kron Figure 2 Direct inspection of the mitral valve is necessary to confirm intraoperative transesophageal echocardiogram findings and to completely assess valve pathologic condition and the nature of MR. Cold saline solution is directly infused into the left ventricle under pressure to demonstrate MV failure and regurgitation. It is necessary to then inspect the subvalvular apparatus. Typically, in IMR, the posteromedial papillary muscle is tethered, which results in distortion of the mitral annulus and deformation of the P3 segment of the posterior mitral leaflet. Figure 3 We then preplace interrupted 2-0 braided (Ticron) sutures in the mitral annulus in preparation for annuloplasty. Generally, 8 to 9 sutures are placed in total.

4 Repair techniques for ischemic mitral regurgitation 207 Figure 4 A complete, semirigid annuloplasty ring is then appropriately sized to the surface area of the valve. Our practice has evolved over the past few years to avoid extreme undersizing of the annuloplasty ring. Generally, a 26- or 28-mm annuloplasty ring is used as the annuloplasty ring is downsized by 1 size. The previously placed mitral annulus sutures are then passed through the ring with appropriate spacing, and the ring is lowered into the annulus after moistening the sutures.

5 208 D. J. LaPar and I.L. Kron Figure 5 Annuloplasty sutures are sequentially tied down to restore mitral annulus anatomy and to maximize remodeling.

6 Repair techniques for ischemic mitral regurgitation 209 Figure 6 Pressurized cold saline infusion into the left ventricle is performed after annuloplasty to test for residual MR. If significant residual MR is detected, the effects of a tethered posterior papillary muscle and dysfunction of the subvalvular apparatus must be considered.

7 210 D. J. LaPar and I.L. Kron Figure 7 (A) Tethering of the posterior papillary muscle results in insufficient coaptation of the anterior and posterior mitral leaflets, often resulting in significant MR even after complete, semirigid annuloplasty. (B) Placement of a 2-0 braided (Ticron) traction suture through the posterior papillary muscle and through the mitral annulus reduces cord tension and allows for enhanced leaflet coaptation and correction of significant MR. (C) Surgeon s view of the mitral valve and subvalvular apparatus. A pledgeted 2-0 braided traction suture is placed through the posterior papillary muscle.

8 Repair techniques for ischemic mitral regurgitation 211 Figure 7 (continued) (D) The traction suture is passed through the mitral annulus and felt pledget to complete placement of the stitch. (E) The traction suture is tied down and adjusted to relocate the posterior papillary muscle to restore normal anatomic position and enhance leaflet coaptation. Prior to locking the suture, residual valve regurgitation can be reassessed using a cold saline infusion test, and any further adjustments to the traction suture can be made as needed before securing the knot. Standard de-airing maneuvers are performed as the atriotomy is closed. Left internal thoracic artery to left anterior descending coronary artery anastomoses and all proximal vein and/or artery graft anastomoses are performed. Further de-airing, release of the aortic crossclamp, and weaning from cardiopulmonary bypass are accomplished per routine. After weaning from bypass, transesophageal echocardiogram is used to confirm adequacy of the mitral repair. MR 1 following repair is considered acceptable after appropriate volume loading of the left ventricle is achieved. MR 1 after repair may require further repair techniques or mitral valve replacement. MV mitral valve.

9 212 D. J. LaPar and I.L. Kron Conclusions IMR remains an increasingly encountered surgical condition that can be successfully addressed through thoughtful repair of the MV in combination with myocardial revascularization. The performance of ring annuloplasty and posterior papillary muscle relocation results in effective restoration of MV and subvalvular apparatus geometry and function. MVR should be considered when repair techniques fail to result in significant improvement of MR ( 1 MR), and replacement should occur prior to leaving the operating room. References 1. Grigioni F, Enriquez-Sarano M, Zehr KJ, et al: Ischemic mitral regurgitation: Long-term outcome and prognostic implications with quantitative Doppler assessment. Circulation 103: , Lamas GA, Mitchell GF, Flaker GC, et al: Clinical significance of mitral regurgitation after acute myocardial infarction. Survival and ventricular enlargement investigators. Circulation 96: , Bursi F, Enriquez-Sarano M, Nkomo VT, et al: Heart failure and death after myocardial infarction in the community: The emerging role of mitral regurgitation. Circulation 111: , Gazoni LM, Kern JA, Swenson BR, et al: A change in perspective: Results for ischemic mitral valve repair are similar to mitral valve repair for degenerative disease. Ann Thorac Surg 84: , 2007 [discussion 758] 5. Adams DH, Filsoufi F, Aklog L, et al: Surgical treatment of the ischemic mitral valve. J Heart Valve Dis 11:S21-25, 2002 (suppl 1) 6. Filsoufi F, Salzberg SP, Adams DH: Current management of ischemic mitral regurgitation. Mt Sinai J Med 72(2): , Gillinov AM, Wierup PN, Blackstone EH, et al: Is repair preferable to replacement for ischemic mitral regurgitation? J Thorac Cardiovasc Surg 122: , Grossi EA, Goldberg JD, LaPietra A, et al: Ischemic mitral valve reconstruction and replacement: Comparison of long-term survival and complications. J Thorac Cardiovasc Surg 122: , Micovic S, Milacic P, Otasevic P, et al: Comparison of valve annuloplasty and replacement for ischemic mitral valve incompetence. Heart Surg Forum 11:E340-E345, Mantovani V, Mariscalco G, Leva C, et al: Long-term results of the surgical treatment of chronic ischemic mitral regurgitation: Comparison of repair and prosthetic replacement. J Heart Valve Dis 13: , 2004 [discussion ] 11. Magne J, Girerd N, Sénéchal M, et al: Mitral repair versus replacement for ischemic mitral regurgitation: Comparison of short-term and longterm survival. Circulation 120:S104-S111, 2009 (suppl 11) 12. Reece TB, Tribble CG, Ellman PI, et al: Mitral repair is superior to replacement when associated with coronary artery disease. Ann Surg 239: , 2004 [discussion ] 13. Silberman S, Klutstein MW, Sabag T, et al: Repair of ischemic mitral regurgitation: Comparison between flexible and rigid annuloplasty rings. Ann Thorac Surg 87: , 2009 [discussion ] 14. Tekumit H, Cenal AR, Uzun K, et al: Ring annuloplasty in chronic ischemic mitral regurgitation: Encouraging early and midterm results. Tex Heart Inst J 36: , Al-Radi OO, Austin PC, Tu JV, et al: Mitral repair versus replacement for ischemic mitral regurgitation. Ann Thorac Surg 79: , 2005 [discussion ] 16. Thourani VH, Weintraub WS, Guyton RA, et al: Outcomes and longterm survival for patients undergoing mitral valve repair versus replacement: Effect of age and concomitant coronary artery bypass grafting. Circulation 108: , Milano CA, Daneshmand MA, Rankin JS, et al: Survival prognosis and surgical management of ischemic mitral regurgitation. Ann Thorac Surg 86: , Silberman S, Oren A, Klutstein MW, et al: Does mitral valve intervention have an impact on late survival in ischemic cardiomyopathy? Isr Med Assoc J 8:17-20, 2006