Mitral valve infective endocarditis (IE) is the most

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1 Mitral Valve Replacement for Infective Endocarditis With Annular Abscess: Annular Reconstruction Gregory J. Bittle, MD, Murtaza Y. Dawood, MD, and James S. Gammie, MD Mitral valve infective endocarditis (IE) is the most common form of left-sided IE. A mitral annular abscess is present in 15% of cases of mitral valve IE. Annular abscesses are almost always located in the posterior mitral annulus. The presence of an annular abscess mandates careful debridement and reconstruction of the atrioventricular (AV) groove with a patch, prior to mitral valve replacement. We use a bovine pericardial patch to reconstruct the posterior annulus. The patch is fashioned to cover the defect by at least 1 2cm circumferentially and is anchored with a running suture, starting at the deepest location in the ventricle and working in both directions toward the atrium. This suture line then extends across the AV groove and anchors the patch to the posterior left atrium. Close spacing of sutures, solid bites in the myocardium, and gentle tension on the suture assures a reliable and hemostatic repair. Operative Techniques in Thoracic and Cardiovasculary Surgery 20:17-30 r 2015 Published by Elsevier Inc. KEYWORDS mitral, abscess, bovine pericardium, valve, infective endocarditis Introduction Mitral valve infective endocarditis (IE) is the most common form of left-sided IE and has an in-hospital mortality rate of 20%-30%. Though nearly half of the patients with mitral valve IE undergo surgical intervention, this remains an uncommon procedure, making up less than 5% of all mitral valve operations, and thus, individual surgeon experience is limited. Choosing the correct patients for operative intervention, at the optimal time, and performing a technically sound operation are critical for optimizing outcomes in this challenging disease process. At our center, indications for operation include the presence of severe mitral regurgitation, paravalvular abscess, vegetations that are mobile or are more than 1 cm in size, embolic events, failure of antibiotic therapy, and fungal etiology. Most patients with mitral valve IE present with cerebral embolism, which we do not consider a contraindication to surgical repair unless associated with significant hemorrhage. The key principle of operative therapy for mitral valve IE is complete debridement of all vegetations and infected tissue, leaving only native tissue that is of sufficient quality to hold suture. Diligence in this regard is essential for the durability of subsequent repair or replacement. A mitral annular abscess is present in approximately 15% of cases of mitral valve IE. 1 Mitral abscesses are almost always located in the posterior mitral annulus and involve the posterior leaflet, the annulus, and the underlying myocardium. The presence of an annular abscess or significant destruction of the posterior annulus mandates careful debridement and reconstruction of the atrioventricular groove with a patch, before mitral valve replacement or repair. We prefer to use bovine pericardium to reconstruct the posterior annulus (Figs. 1 9). Division of Cardiac Surgery, University of Maryland School of Medicine, Baltimore, MD Address reprint requests to James S. Gammie, MD, Division of Cardiac Surgery, University of Maryland School of Medicine, 110 S Paca St, 7th Floor, Baltimore, MD jsgammiemd@gmail.com /$-see front matter r 2015 Published by Elsevier Inc. 17

2 18 G.J. Bittle et al. Operative Technique Right atrial appendage Aorta SVC IVC Vegetation on posterior leaflet and annulus Figure 1 The patient is centrally cannulated for cardiopulmonary bypass with bicaval drainage. No pericardial stay sutures are placed on the left side of the heart, allowing the heart to rotate to the left. The cavae are mobilized, the interatrial groove is developed, and a longitudinal incision is made from the right superior pulmonary vein inferiorly toward the inferior vena cava, facilitating exposure of the mitral valve. The valve is then assessed. In this case, a vegetation is identified involving the posterior leaflet. SVC ¼ superior vena cava; IVC ¼ inferior vena cava.

3 Mitral valve replacement for infective endocarditis with annular abscess 19 Resection of vegetation and debridement of posterior leaflet & annulus Figure 2 Complete debridement. All affected tissue is sharply excised. This may include leaflet, chords, and other parts of the subvalvular apparatus, as well as portions of the annulus and surrounding atrial tissue.

4 20 G.J. Bittle et al. A Papillary muscle Remnant of posterior leaflet Anterior Leaflet Papillary muscle Remnant of Posterior leaflet Posterior annulus Abscess cavity Figure 3 Assessment. Following complete debridement, the valve is assessed and the decision is made to proceed with either repair or replacement (A).

5 Mitral valve replacement for infective endocarditis with annular abscess 21 B Removal of anterior leaflet leaving 3-5 mm rim Figure 3 Continued (B and C) If the valve needs to be replaced, the anterior leaflet is resected, leaving a rim of leaflet tissue measuring 4-5 mm attached to the annulus. Alternatively the anterior leaflet and chords can be spared by dividing the anterior leaflet in half and translocating the right and left "tabs" to 9:00 and 2:00 and incorporating them into the replacement suture line.

6 22 G.J. Bittle et al. C Resection of anterior leaflet completed with scissors Figure 3 (Continued)

7 Mitral valve replacement for infective endocarditis with annular abscess 23 A Bovine pericardial patch trimmed to fit over defect Directional pattern for suturing patch Defect under patch Figure 4 Annular reconstruction. The integrity of the annulus is then evaluated. In this case, adequate debridement has necessitated resection of annular tissue and the annular abscess is clearly visible. We prefer to use bovine pericardium to reconstruct the atrioventricular continuity. (A) We use a bovine pericardial patch measuring either 5 10 cm or 9 14 cm. The thickness of this patch is mm (St. Jude Medical, Inc, Minneapolis, MN; catalog C0510 [5 10 cm] or C0914 [9 14 cm]). The patch is intentionally oversized such that it comfortably covers the defect by at least 1-2 cm circumferentially. It is secured in place using running 4-0 polypropylene suture, starting at the deepest location in the ventricle and working in both directions toward the atrium.

8 24 G.J. Bittle et al. B Patch sewn into place beginning at mid-position of patch, deepest location in ventricle Figure 4 Continued (B) This suture line then extends across the atrioventricular groove and similarly anchors the patch to the posterior left atrium. Close spacing of sutures, solid bites in the myocardium, and gentle tension on the suture assure a reliable and hemostatic repair. Injury to the underlying left circumflex coronary artery is avoided when traversing the annulus by placing sutures at a depth similar to that for mitral valve replacement. Oversizing the patch provides a rim of pericardium that is sealed by intracavitary ventricular pressure against the underlying normal myocardium, thereby contributing to hemostasis (Fig. 9). This is the same principle underlying the repair of an atrioventricular groove disruption.

9 Mitral valve replacement for infective endocarditis with annular abscess 25 Patch over abscess cavity Figure 5 Inspect the patch. The patch should completely cover the annular defect without tension. The suture line is inspected for laxity.

10 26 G.J. Bittle et al. Sutures placed for securing bioprosthetic valve Figure 6 Place valve sutures. Valve sutures are placed in the intact annulus and are seated in the patch overlying the defect.

11 Mitral valve replacement for infective endocarditis with annular abscess 27 Seating replacement value Figure 7 Seat the valve. The sutures are passed through the sewing ring of the bioprosthetic valve such that the 2 marked posts are approximately aligned with the trigones, avoiding obstruction of the left ventricular outflow tract.

12 28 G.J. Bittle et al. Mitral valve replacement completed Figure 8 Final inspection. After securing all the valve sutures, the valve is inspected one last time for evidence of instability or potential areas of paravalvular leak. The visible margin of the patch is also inspected for integrity. We pass a Foley catheter across the valve at this point, inflate the balloon with 5-6 cc of saline, and leave it in place for use as a left ventricular vent. The left atrium is closed with polypropylene sutures.

13 Mitral valve replacement for infective endocarditis with annular abscess 29 Atrial pressure Defect Patch Ventricular pressure Figure 9 Demonstrates the completed annular reconstruction with bovine pericardium with a bioprosthetic mitral valve replacement. Ventricular and atrial pressure contribute to hemostasis at the margins of the pericardial patch.

14 30 Discussion At least half of the patients with mitral valve IE require surgery, and mitral valve IE should be considered a surgical disease until proven otherwise. There is a clear correlation between the percentage of patients undergoing early surgical intervention and lower in-hospital mortality rates in patients with mitral valve IE, and contemporary series with high rates of early surgery report mortality rates of 10% or lower. 2 A recent prospective randomized trial compared early surgery with antibiotic therapy for patients with left-sided IE and large (41 cm) vegetations and found that early surgery significantly reduced the composite end point of death or embolic events by reducing the risk of systemic embolism. 1 Evidence of cerebral embolism is present on cranial magnetic resonance (MR) imaging in approximately 80% of patients presenting with active IE and in 50% of patients on computed tomography and should not be a contraindication to early operative intervention. In our institutional experience, hemorrhagic conversion is an exceptionally rare event, and a policy of early operative intervention has been associated with a low stroke rate 3 and has the benefit of prevention of further embolic events, rapid resolution of valvular insufficiency, and an increased likelihood of repair. Rather than the presence of heart failure, we believe that the presence of severe MR is a key trigger for operative intervention. MR precedes and leads to the development of heart failure, which has been demonstrated to be the most important risk factor for mortality in IE. Antibiotic therapy alone does not lead to a decrease in the severity of mitral regurgitation. The scale and nature of operative intervention is dictated by the extent of tissue destruction always adherent to the principle of complete debridement and may require G.J. Bittle et al. annular reconstruction. The material with which the neoannulus is created is a matter of surgeon preference. The use of bovine pericardium, fixed and fresh autologous pericardium, as well as Dacron have all been described. Pericardial tissue has the advantage of increased pliability and the ability to conform to the underlying myocardium, decreasing the likelihood of flow under the patch, which could result in the development of a pseudoaneurysm or ventriculoatrial shunt. Importantly, this material has not been associated with an increased risk of reinfection. 4 Following patch placement, either valve repair or replacement can be performed depending on the extent of destruction of the valve leaflets. As is the case for noninfectious mitral valve disease, repair when possible has been shown to decrease the risk of stroke, recurrent endocarditis, reoperation, and death in patients with mitral valve IE. 1 If repair is undertaken, the surgeon should not hesitate to use an annuloplasty: the risk of annuloplasty ring infection is negligible, and the consequences of a failed repair are significant. 5 References 1. Kang D, Kim Y, Kim S, et al: Early versus conventional treatment for infective endocarditis. New Engl J Med 366:2466, Thuny F, Grisoli D, Collart F, et al: Management of infective endocarditis: challenges and perspectives. Lancet, Shang E, Forrest G, Chizmar T, et al: Mitral valve infective endocarditis: benefit of early operation and aggressive use of repair. Ann Thorac Surg 87: , Kerchove L, Price J, Tamer S, et al: Extending the scope of mitral valve repair in active endocarditis. J Thorac Cardiovasc Surg 143:s91 s95, Gillinov AM, Faber CN, Sabik JF, et al: Endocarditis after mitral valve repair. Ann Thorac Surg 73: , 2002