Ann Thorac Surg 2008;85:1820-1822. doi:10.1016/j.athoracsur.2007.11.073
© 2008 The Society of Thoracic Surgeons
How To Do It
New Surgical Procedure for Ischemic/Functional Mitral Regurgitation: Mitral Complex Remodeling
Hirokuni Arai, MD, PhD*,
Fusahiko Itoh, MD,
Takeshi Someya, MD,
Keiji Oi, MD, PhD,
Kiyoshi Tamura, MD, PhD,
Hiroyuki Tanaka, MD, PhD
Department of Cardiothoracic Surgery, Tokyo Medical and Dental University Graduate School of Medicine, Tokyo, Japan
Accepted for publication November 27, 2005.
* Address correspondence to Dr Arai, Department of Cardiothoracic Surgery, Tokyo Medical and Dental University Graduate School of Medicine, 1-5-45 Yushima, Bunkyo-ku, Tokyo, 113-8519, Japan (Email: hiro.tsrg{at}tmd.ac.jp).
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Abstract
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Although numerous surgical techniques have been developed for ischemic/functional mitral regurgitation, none has clearly improved patient outcome. We report the clinical application of a new mitral complex remodeling procedure for ischemic/functional mitral regurgitation that allows comprehensive remodeling of the entire mitral complex. The mitral complex remodeling procedure consists of three major concepts: division and reconstruction of secondary chords, undersized annuloplasty, and bilateral papillary muscle relocation.
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Introduction
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The basic mechanism of ischemic/functional mitral regurgitation (MR) is leaflet tethering by outward displacement of papillary muscles due to left ventricular remodeling. Undersized mitral annuloplasty is the conventional approach for surgical management of ischemic/functional MR, with acceptable morbidity and mortality. Residual or recurrent MR occurs in up to 30% of patients, however, and is attributed to persistent tethering of both leaflets with predominantly augmented and progressive tethering of the posterior mitral leaflet [1]. Although numerous surgical techniques have been developed for ischemic/functional MR, none has received wide acceptance [2].
We report the clinical application of a new repair procedure for ischemic/functional MR with severe tethering as indicated by a tenting height exceeding 10 mm, which is defined as the distance between the coaptation point of the mitral leaflets and the plane of the mitral annulus at end systole as measured on the 4-chamber apical long-axis view of the transthoracic echocardiogram. This procedure allows comprehensive remodeling of the entire mitral complex, including the annulus and subvalvular apparatus.
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Technique
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On-pump beating heart mitral complex remodeling was performed without aortic clamping (Fig 1). The mitral valve was exposed through a left atriotomy posterior to the interatrial groove. Interrupted 2-0 braided horizontal mattress sutures without pledgets were placed around the annulus to optimize exposure of the subvalvular apparatus. Secondary chords to the anterior leaflet from both papillary muscles were carefully separated from primary chords with a nerve hook and were divided.
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Fig 1. (A) Mitral complex remodeling (APM = anterior papillary muscle; PPM = posterior papillary muscle). (B) Mitral complex remodeling concept. (I) Functional mitral regurgitation due to leaflet tethering (MR = mitral regurgitation). (II) Division of secondary chords (*) restores convexo-concave curvature of the anterior leaflet. (III) Undersized annuloplasty approximates anteroposterior distance but increases posterior leaflet tethering. (IV) Artificial chords of 5-0 Gore-Tex (W. L. Gore & Associates, Flagstaff, AZ) suture (x) to the anterior leaflet margin replace divided secondary chords. The 4-0 Gore-Tex relocation sutures (y) between both papillary muscles and posterior mitral annulus relocate both papillary muscles in relation to the mitral annulus, relieving anterior and posterior leaflet tethering.
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Two pairs of 5-0 and 4-0 Gore-Tex sutures (W. L. Gore & Associates, Flagstaff, AZ) were each placed to both fibrous portions of the anterior and posterior papillary muscle tips, buttressed with pledgets of autologous pericardium. Two pairs of the free arms of the 5-0 Gore-Tex sutures were twice passed through the free edge of the middle portion of the anterior leaflet about 5 mm from the margin, from ventricular to atrial side. Suture length was adjusted to be the same length as the corresponding marginal chords, and the sutures were tied.
Each pair of the free arms of the 4-0 Gore-Tex sutures was passed through the posterior annulus at sites around the border of the lateral and middle portions and middle and medial portions of the annulus, respectively (annulopapillary suture), and was also passed through corresponding sites in the annuloplasty ring (Carpentier-Edwards Physio; Edwards Lifesciences, Irvine, CA). The 26-mm semi-rigid annuloplasty ring was then seated. The annulopapillary sutures were pulled to retract the papillary muscle tips closer to the annulus, to the point at which leaflet coaptation occurred in the plane of the mitral annulus during systole, to visually confirm no residual MR. Suture lengths were determined, and the sutures were tied.
To avoid air embolism, a vent cannula with a pressure-monitoring catheter (TOYOBO Co Ltd, Osaka, Japan) was inserted into the left ventricular apex and was connected to the suction circuit equipped with a small reservoir chamber (Senko Medical Instrument Mfg Ltd, Saitama, Japan). During the final adjustment of the annulopapillary suture length, this chamber was filled with blood, and the height of the fluid level of this chamber was adjusted to load the left ventricle. The left ventricular systolic pressure was monitored to keep it slightly lower than the systemic perfusion pressure to avoid ejection through the aortic valve.
This new technique has been performed on 3 patients with ischemic/functional MR. The patients were aged 61, 64, and 69 years; their ejection fractions were 0.34, 0.25, 0.32; their left ventricular diastolic diameters were 62, 74, and 79 mm; and tenting heights were 11, 12, and 14 mm, respectively. Preoperatively, all patients showed severe MR; perioperative transesophageal echocardiography showed disappearance of MR. Mitral valvular function has remained stable during a mean short-term follow-up of 6 months (range, 1 to 12 months), with no or trivial MR noted.
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Comment
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Our mitral complex remodeling procedure consists of three major concepts: division and reconstruction of secondary chords, undersized anuloplasty, and papillary muscle relocation (Fig 1). Division of the secondary chords relieves anterior leaflet tethering by increasing leaflet mobility and restoring the leaflet's slightly curved shape toward the left atrium. Borger and colleagues [3] reported that the chordal cutting procedure combined with undersized annuloplasty reduced regurgitation recurrence in ischemic MR; however, they still observed recurrent MR in 15% of patients. We observed persistent MR after chordal cutting combined with undersized annuloplasty before bilateral papillary muscle relocation (Fig 2A). Furthermore, the long-term fate of this simple chordal cutting procedure is unclear because the secondary chords are under three times more tension than are the marginal chords [4]. Accordingly, we added new artificial chords to the margin of the anterior leaflet to replace the secondary chords. Artificial chord length was simply adjusted to be the same length as the marginal chords.
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Fig 2. (A) Persistent mitral regurgitation was observed in the beating heart after undersized annuloplasty and secondary chord division. (B) Mitral regurgitation decreased slightly but persisted after relocation of the posterior papillary muscle only. (C) Mitral regurgitation completely disappeared after relocation of both papillary muscles. Convex shape of anterior leaflet at the annular level is observed.
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Undersized mitral annuloplasty reduces the anteroposterior diameter of the annulus and MR. However, this effect is limited because undersized annuloplasty itself augments tethering of the posterior mitral leaflet, restricting its anterior excursion toward coaptation while keeping anterior leaflet tethering unchanged [5]. To correct this negative effect, we performed bilateral papillary muscle relocation. The fibrous tips of both papillary muscles were approximated to the posterior mitral annulus, enabling anterior leaflet excursion to the annular level and relieving augmented posterior leaflet tethering; thus, the coaptation point shifts from the intraventricular to annular level and coaptation surface increases. The annulopapillary suture may also prevent further outward displacement of the papillary muscle due to progression of future LV remodeling.
Kron and associates [6, 7] reported posterior papillary muscle relocation in ischemic MR due to inferior wall infarction. We found relocation of both papillary muscles to be more effective than single papillary muscle relocation. Residual MR after posterior papillary muscle relocation alone disappeared after relocation of the anterior papillary muscle (Fig 2).
Precise adjustment of annulopapillary suture length during systole is essential. We therefore performed the entire procedure on the beating heart. However, only this final step of adjustment of the annulopapillary sutures must be done on the beating heart; the rest of the procedure can be done on the standard arrested heart. Although a certain amount of tension might be applied to the annulopapillary sutures, we have never observed any avulsion of the papillary muscle tip intraoperatively or during follow-up.
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References
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- McGee EC, Gillinov AM, Blackstone EH, et al. Recurrent mitral regurgitation after annuloplasty for functional ischemic mitral regurgitation J Thorac Cardiovasc Surg 2004;128:916-924.[Abstract/Free Full Text]
- Borger MA, Alaim A, Murphy PM, Doenst T, David TE. Chronic ischemic mitral regurgitation: repair, replace or rethink? Ann Thorac Surg 2006;81:1153-1161.[Abstract/Free Full Text]
- Borger MA, Murphy PM, Alam A, et al. Initial results of the chordal-cutting operation for ischemic mitral regurgitation J Thorac Cardiovasc Surg 2007;133:1483-1492.[Abstract/Free Full Text]
- Lomholt M, Nielsen SL, Hansen SB, Andersen NT, Hasenkam JM. Differential tension between secondary and primary mitral chordae in an acute in-vivo porcine model J Heart Valve Dis 2002;11:337-345.[Medline]
- Zhu F, Otsuji Y, Yotsumoto G, et al. Mechanism of persistent ischemic mitral regurgitation after annuloplasty: importance of augmented posterior mitral leaflet tethering Circulation 2005;112:I396-I401.[Medline]
- Kron IL, Green GR, Cope JT. Surgical relocation of the posterior papillary muscle in chronic ischemic mitral regurgitation Ann Thorac Surg 2002;74:600-601.[Abstract/Free Full Text]
- 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 2007;84:750-758.[Abstract/Free Full Text]
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Abstract
Introduction
