Ann Thorac Surg 2003;75:1987-1989
© 2003 The Society of Thoracic Surgeons
How to do it
Conduit-on-valve replacement of a degenerated mitral bioprosthesis with a bioprosthesis
Jen-Ping Chang, MDa*,
Chiung-Lun Kao, MDa,
Kuei-Ton Tsai, MDa,
Ming-Jang Hsieh, MDa,
Morgan Fu, MDa
a Division of Thoracic and Cardiovascular Surgery, Cardiology, Chang Gung Memorial Hospital at Kaohsiung, Kaohsiung Hsien, Taiwan, Republic of China
Accepted for publication October 17, 2002.
* Address reprint requests to Dr Chang, Division of Thoracic and Cardiovascular Surgery, Chang Gung Memorial Hospital at Kaohsiung, 123 Pei Rd., Niao Sung Hsiang, Kaohsiung Hsien, Taiwan, R.O.C.
e-mail: c9112772{at}adm.cgmh.org.tw
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Abstract
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Explantation of a degenerated mitral bioprosthesis with reimplantation of a new bioprosthesis is time-consuming and can be associated with several life-threatening complications. We developed a technique to simplify this procedure and avoid the complications by attaching a new bioprosthesis supported by a pericardium-covered Dacron tube to the intact stent.
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Introduction
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Mitral bioprostheses are vulnerable to structural degeneration [1, 2]. Redo bioprosthetic valve replacement can pose formidable technical challenges [3]. The conventional approach consists of explanation of the degenerated bioprosthesis and replacement with another valve in situ. These procedures are time-consuming and can be complicated by cardiac rupture, injury to the circumflex artery, and late paravalvular leak [4, 5]. Geha and colleagues [5–7] developed a surgical technique for replacement of degenerated bioprostheses with low-profile mechanical bileaflet prostheses by excising the degenerated tissue, leaving the stent and support of the bioprosthesis intact, and attaching the new mechanical prosthesis to the old bioprosthetic valve annulus. Although this approach minimizes the hazards associated with removal of the entire bioprosthesis, it is not applicable for re-replacement with a new bioprosthetic valve that has protruding struts. We report our modification of this valuable valve-on-valve technique with the use of a bioprosthesis supported by a pericardial strip–covered Dacron tube (conduit-on-valve) to circumvent the problem in a 72-year-old woman.
This approach was applied in a 72-year-old woman who, 7 years previously, had a 33-mm Carpentier-Edwards mitral bioprosthesis implanted (Edwards Lifesciences, Irvine, CA) for mitral valve replacement, tricuspid valve repair, and a successful maze procedure. The patient presented this time with acute pulmonary edema secondary to severe mitral bioprosthetic valve regurgitation. Two-dimensional color Doppler echocardiography confirmed the prolapsed cusps secondary to degenerative changes in the bioprosthesis. The struts of the bioprosthesis were intact. Because of the patient’s age and her refusal for permanent anticoagulation, we decided to re-replace the degenerated bioprosthesis with another 33 mm Carpentier-Edwards mitral bioprosthesis and a 38-mm Hemashield woven graft (Meadox Medicals, Inc. Oakland, NJ) by this conduit-on-valve technique.
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Technique
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Cardiac exposure was obtained through a repeat sternotomy. The procedure was performed with moderate hypothermic cardiopulmonary bypass and antegrade cardioplegia. Exposure of the mitral bioprosthesis was achieved through a longitudinal transseptal approach. The previously implanted mitral bioprosthesis was inspected to confirm the presence of structural degeneration.
After inspecting the valve, the degenerated cusps were excised, and the sewing ring including the struts was left intact. The bioprosthesis–Dacron conduit was constructed with a new 33-mm bioprosthesis implanted inside a 2-cm-long Dacron tube with a diameter 5 mm larger than that of the bioprosthetic valve annulus. A bovine pericardial strip was then wrapped around the Dacron tube, with the smooth surface to the outside (Fig 1). The conduit was then implanted in a conduit-on-valve fashion with horizontal mattress sutures (Figs 2 and 3).
Closure of the septotomy and subsequent removal of air were completed as usual. The patient was then weaned off cardiopulmonary bypass.
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Fig 1. The bioprosthesis–Dacron tube conduit was completed with the bovine pericardial strip covering all Dacron surfaces, with the smooth surface out.
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Fig 2. Drawing of the conduit-on-valve mitral re-replacement. All degenerated leaflet tissue is removed (arrow), and the bioprosthesis–Dacron tube composite graft is apposed to the inflow aspect of the previous bioprosthetic stent.
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Fig 3. Intraoperative appearance of the completed bioprosthesis–Dacron tube conduit mitral re-replacement. The composite graft sits on the atrial aspect of the previous bioprosthetic stent.
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Follow-up
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The postoperative course was uneventful, and the patient was discharged from the hospital 7 days after the operation. Transthoracic echocardiography 3 months postoperatively revealed trivial mitral regurgitation with a mitral valve area of 2.69 cm2 (Fig 4).
Presently, she is in New York Heart Association functional class I with stable sinus rhythm and is free from medication after 6 weeks of oral anticoagulation. Repeat transthoracic echocardiography 6 months postoperatively revealed excellent mitral bioprosthetic function without evidence of left atrial thrombus (Fig 5).
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Fig 4. Transthoracic echocardiography 3 months postoperatively showing the mitral conduit-on-valve with valve area of 2.69 cm2.
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Fig 5. Transthoracic echocardiography showing the mitral conduit-on-valve bioprosthesis projecting into the left atrium without any thrombus formation 6 months postoperatively without anticoagulation.
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Comment
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Patients with previous bioprosthetic valve replacement tend to be older and sicker. Although the results of redo valve replacement have improved gradually, explantation of a degenerated bioprosthesis remains technically difficult, especially when there is tissue ingrowth, strut incorporation, or annular size mismatch at the previous operation. Implantation of a mechanical valve within (valve-in-valve) or above (valve-on-valve) the orifice of the stent of the bioprosthesis after excision of the bioprosthetic material has been reported [5–9] with good early and midterm results. Unfortunately, these techniques are limited in view of the need for a mechanical bileaflet valve, which is not always suitable for these older and sicker patients, especially when they do not need anticoagulation, as in our patient who had previous successful surgical ablation of atrial fibrillation. Our conduit-on-valve technique seems to circumvent this problem. Re-replacement of a new mitral bioprosthesis in this manner preserves the advantages of the mechanical valve-on-valve replacement technique. The role of the pericardial wrap is controversial. Because we are also concerned about avoiding thromboembolic complications in our patient who has had a previous maze procedure, we were careful to avoid exposing the thrombogenic nonsmooth surface of the pericardial strip to the blood stream, as well as to administer oral anticoagulation with warfarin for 6 weeks. Further experience with this approach might determine whether these steps are necessary.
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References
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Abstract
Introduction
