Ann Thorac Surg 2008;85:1789-1791. doi:10.1016/j.athoracsur.2007.11.069
© 2008 The Society of Thoracic Surgeons
Case Reports
Obstruction of Left Ventricular Outflow Tract After Mechanical Mitral Valve Replacement
Qingyu Wu, MD*,
Lufeng Zhang, MD,
Rui Zhu, MD
Heart Center, First Hospital of Tsinghua University, Beijing, China
Accepted for publication November 26, 2007.
* Address correspondence to Dr Wu, Heart Center, First Hospital of Tsinghua University, No. 6, First Street of Jiuxianqiao, Chaoyang District, Beijing, 100016, China (Email: wuqingyu{at}mail.tsinghua.edu.cn).
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Abstract
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We successfully operated on a patient with a rare complication of left ventricular outflow tract obstruction after mitral valve replacement. In a 57-year-old woman with previous mitral valve replacement, transthoracic echocardiography showed left ventricular outflow tract obstruction as a result of anterior displacement of the mitral prosthesis and local thickening of the interventricular septum. Cardiac surgery verified this rare lesion. During the operation, the anterior half of the prosthesis ring was cut away from hyperplastic tissue and sutured to the natural mitral annulus. Subaortic hyperplastic tissue was excised to enlarge the left ventricular outflow tract. The patient had an uneventful postoperative recovery, and left ventricular outflow tract obstruction disappeared on postoperative transthoracic echocardiography.
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Introduction
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The complication of left ventricular outflow tract obstruction (LVOTO) with mechanical mitral prosthesis has been rarely reported. We present one case with symptoms 10 years after mitral valve replacement.
A 57-year-old woman with rheumatic valvular disease was referred to our hospital in 2006. She had received a 27-mm ATS mechanical mitral prosthesis implantation (ATS Medical Inc, Minneapolis, MN), aortic valvuloplasty, and tricuspid annuloplasty 10 years ago. Two years after the operation, she experienced amaurosis and dyspnea induced by light exertion, also bradycardia with her heart rate slowing down to 30 beats/min at night. A single-chamber pacemaker was implanted to help her 2 years ago. However, the symptom was not relieved. She was admitted to our hospital in August 2006. The transthoracic echocardiography (TTE) study showed mitral prosthesis in normal function, and LVOTO (8 mm at the most narrow site; Fig 1) as a result of anterior displacement of the mitral prosthesis and thickening of the interventricular septum at the opposing part (thickness of the interventricular septum was 13 mm). Mild aortic stenosis and moderate aortic and tricuspid regurgitation were also identified. The coronary artery angiogram was normal. Left ventriculography showed the mitral prosthesis functioning well, and the gradient pressure between the left ventricular outflow tract and the ascending aorta was 29 mm Hg.
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Fig 1. Preoperative transthoracic echocardiography shows ATS mechanical prosthesis anterior displacement (arrow) and obstructing left ventricular outflow tract.
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The operation was performed under hypothermic cardiopulmonary bypass. Through a median sternotomy, the superior and inferior venae cavae and the ascending aorta were cannulated. After cross-clamping of the ascending aorta, the mitral prosthesis was exposed through the right atrium and atrial septostomy. Part of the mitral prosthesis ring was found sutured to a remnant of the anterior mitral leaflet (Fig 2), which led to anterior displacement of the mitral prosthesis and LVOTO, with secondary fibrosis hyperplasia of the interventricular septum and the surrounding tissue.
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Fig 2. The anterior half of prosthesis ring (not seen here, beyond the remnant leaflet) was sutured to residual mitral anterior leaflet (arrow) with previous operation.
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During the operation, the incision was made between the anterior half of the prosthesis ring and the aortic valve. Two millimeters of tissue was preserved for the base of the mitral leaflet, and the hyperplastic tissue was excised. The mitral prosthesis ring was sutured to the natural mitral annulus using double-arm pledgeted stitches (Fig 3). Subaortic hyperplastic tissue was excised to enlarge the left ventricular outflow tract (Fig 4). Aortic valve replacement with a 23-mm Carbomedics mechanical prosthesis (Carbomedics Inc, Austin, TX) and tricuspid Devega's annuloplasty were carried out concomitantly to eliminate aortic stenosis and tricuspid regurgitation, respectively.
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Fig 3. Anterior half of the prosthesis ring was cut away from hyperplastic tissue and lifted upward to left atrium by double-arm sutures with pledget (arrow).
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Fig 4. Subaortic hyperplasia of fibrosis (myocardial) tissue was excised to enlarge left ventricular outflow tract (arrow).
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The patient had an uneventful postoperative recovery. The postoperative TTE showed the mitral and aortic prosthesis functioned well without obstruction of the left ventricular outflow tract (Fig 5).
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Fig 5. Postoperative transesophageal echocardiography shows unobstructed left ventricular outflow tract (arrow).
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Comment
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Postoperative LVOTO is a complication after mitral valve repair with a rigid ring in myxomatous degenerative valve disease [1]; it was seldom reported after mechanical mitral valve replacement [2–5] . In this case, preoperative TTE showed mitral prosthesis anterior displacement and LVOTO. During the operation, the anterior half of the prosthesis ring was found sutured to the margin of an overpreserved mitral leaflet instead of to the annulus. The prosthesis apparatus moved forward during systole and obstructed the left ventricular outflow tract. Then the secondary-growth tissue made the LVOTO more severe. The redundant residual leaflet was cut away from the anterior half of the ring along the border, and then the prosthesis was lifted and resutured to the mitral annulus; subaortic fibrosis (myocardial) tissue was excised to enlarge the left ventricular outflow tract. The LVOTO disappeared on postoperative TTE. We concluded that in mitral replacement, LVOTO can be caused by a prosthesis sutured low to an overpreserved residual mitral valve leaflet. This can be solved by an operation. Intraoperative TEE study could be helpful in avoiding this complication. The more important thing to mention is careful identification of the mitral annulus and delicate surgical technique.
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References
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- Schiavone WA, Cosgrove DM, Lever HM, Stewart WJ, Salcedo EE. Long-term follow-up of patients with left ventricular outflow tract obstruction after Carpentier ring mitral valvuloplasty Circulation 1988;78:I60-I65.[Medline]
- Melero JM, Rodriguez I, Such M, et al. Left ventricular outflow tract obstruction with mitral mechanical prosthesis Ann Thorac Surg 1999;68:255-257.[Abstract/Free Full Text]
- Popovic Z, Vukajlovic D, Popovic AD. Asymptomatic left ventricular outflow tract obstruction after mitral valve replacement with leaflet preservation J Heart Valve Dis 1999;8:450-452.[Medline]
- Rietman GW, Maaten VD, Douglas YL, Boonstra PW. Echocardiographic diagnosis of left ventricular outflow tract obstruction after mitral valve replacement with subvalvular preservation Eur J Cardiothorac Surg 2002;22:825-827.[Abstract/Free Full Text]
- Nezic DG, Vukovic MM, Cirkovic MV, Knezevic AM, Jovic, MDj, Jakovljevic MM. An unusual complication after chordal sparing mitral valve replacement J Thorac Cardiovasc Surg 2004;127:599-600.[Free Full Text]
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Abstract
Introduction
