doi: 10.1161/CIRCULATIONAHA.104.524561
(Circulation. 2005;112:I-396 – I-401.)
© 2005 American Heart Association, Inc.
Surgery for Valvular Heart Disease |
Mechanism of Persistent Ischemic Mitral Regurgitation After Annuloplasty
Importance of Augmented Posterior Mitral Leaflet Tethering
From the Department of Cardiovascular, Respiratory, and Metabolic Medicine (F.Z., Y.O., T.Y., B.Y., S.H., S.B., A.K., S.M., C.T.), Department of Public Health (C.K.), Department of Cardiovascular Surgery (G.Y., T.U., R.S.), Graduate School of Medicine, Kagoshima University, Kagoshima, Japan; and Massachusetts General Hospital (R.A.L.), Boston, Mass.
Correspondence to Yutaka Otsuji, MD, Department of Cardiovascular, Respiratory and Metabolic Medicine, Graduate School of Medicine, Kagoshima University, 8-35-1 Sakuragaoka, Kagoshima City, 890-8520, Japan. E-mail yutaka{at}m.kufm.kagoshima-u.ac.jp
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Abstract |
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Background— We hypothesized that surgical annuloplasty for ischemic mitral regurgitation (MR) that displaces the posterior annulus anteriorly can potentially augment posterior leaflet (PML) tethering, leading to persistent MR. Relationships between leaflet configurations and persistent ischemic MR after the annuloplasty were investigated.
Methods and Results— In 31 patients with surgical annuloplasty for ischemic MR and 20 controls, posterior and apical displacement of the leaflet coaptation, the anterior leaflet (AML) and PML tethering angles relative to the line connecting annuli, coaptation length (CL), and the MR grade were quantified before and early after surgery in echocardiographic left ventricular long-axis views. Six of the 31 patients showed persistent MR despite annuloplasty. Compared with patients without persistent MR, those with MR showed no improvement in the left ventricular ejection fraction and systolic volume, similar reduction in the annular area, significant increase in posterior displacement of the coaptation (P<0.01), no improvement in AML tethering, greater worsening in PML tethering (P<0.01), and no increase in the CL. All tethering variables were significantly correlated with both preoperative and postoperative MR in univariate analysis, and reduced CL was the primary independent determinant of both preoperative and postoperative MR. Although increased AML tethering was the primary determinant of the preoperative CL (r2=0.46, P<0.0001), increased PML tethering was the primary determinant afterward (r2=0.60, P<0.0001).
Conclusion— Although tethering of both leaflets is the major determinant of ischemic MR before surgical annuloplasty, both leaflets tethering but with predominant and augmented PML tethering is related to persistent ischemic MR after the annnuloplasty.
Key Words: mitral valve • echocardiography • valuloplasty
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Introduction |
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Current surgical approaches for the treatment of ischemic mitral regurgitation (MR) mainly focus on annular size reduction, which is usually effective.1–3 A considerable number of patients, however, show persistent or recurrent MR despite annuloplasty,3–6 which adversely affects patients’ outcomes,7 and its mechanism has not been fully investigated.
The basic mechanism of ischemic MR is leaflet tethering by the outward displacement of papillary muscles (PM) due to left ventricular (LV) remodeling.8–13 Surgical mitral annuloplasty, which is expected to hoist the posterior annulus anteriorly but may not cause significant positional changes to the anterior annulus fixed at the aortic root, can potentially augment tethering of the posterior mitral leaflet (PML) and restrict its anterior excursion toward coaptation while keeping the tethering of anterior leaflet (AML) unchanged (Figure 1).6,14 We hypothesized that ischemic MR without annuloplasty is related to tethering of both leaflets and that MR after surgical annuloplasty is also related to tethering of both leaflets, but especially with tethering of the PML. Therefore, the purpose of this study was to investigate AML and PML configurations in patients with ischemic MR with and without surgical annuloplasty, and to clarify the characteristics of leaflet configurations responsible for persistent ischemic MR afterward.
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Methods |
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Subjects
Subjects were 31 consecutive patients who had undergone surgical annuloplasty for ischemic MR at our hospital and 20 normal controls. Posterior annuloplasty with a flexible linear reducer (stainless steel wire seemed with a polyester sheath), in addition to a Carpentier Edwards semi-rigid ring and a Duran flexible ring, was performed.15 Patients profiles are summarized in Table 1. Ischemic MR was diagnosed by echocardiography using the following criteria: (1) The presence of LV dilatation and/or dysfunction, (2) the presence of apical displacement of mitral leaflets,8 and (3) the absence of organic leaflet lesions. The control subjects had normal echocardiogram without known cardiovascular disease. After cardiovascular surgery with ring annuloplasty, no patient had a subsequent myocardial infarction or required additional revascularization. Concomitant coronary artery bypass grafting was performed in all patients and LV plasty with Dor’s, overlapping of anterior wall,16 or plication of posterior aneurysm was performed in 11 patients. Patients were managed after surgery with standard medications. Written informed consent was obtained from all patients.
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Measurements by Echocardiography
Two-dimensional and Doppler echocardiographic examinations were performed in all patients using 2- to 3-MHz transducers and commercially available phased array sector scanners (ATL HDI 3000; Toshiba SSH 380A; Philips Medical Systems Sonos 5500; Aloka SSD-5500; Siemens Sequoia 512) 1 week before and 2 weeks to 2 months after the surgery.
LV end-diastolic volume, end-systolic volume (LVESV), and ejection fractions (EF) were determined by the modified biplane Simpson’s method. The LV sphericity was assessed by its short-to-long axis dimension ratio in the end-systolic apical 4-chamber view. Mid-systolic mitral annular dimension was measured in the apical 4- and 2-chamber views, to calculate its area with an elliptical assumption.17
Mitral Leaflet Configuration and Mobility
Mitral leaflet configuration in mid-systole was quantified in the parasternal long-axis view (Figure 2). The angles 
1 and 2 represent the grade of AML and PML tethering, respectively. The bending angle ß between the tangent lines of proximal and distal AML represent the grade of AML tethering from secondary chordae.18 The distances d1 and d2 represent posterior and apical displacement of the coaptation, respectively. Leaflet excursion or changes in 1 and 2 from diastolic maximal opening to systolic closure was evaluated. Coaptation length (CL) was also measured.
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Quantification of MR and Its Jet Direction
MR was quantified by the vena contracta width or the narrowest jet origin in a parasternal or apical long-axis view perpendicular to the coaptation line.6 Vena contracta width 
3 mm was considered significant. MR jet direction was visually evaluated as anterior, central, or posterior in the color Doppler long-axis view. Echocardiographic measurements were averaged over 3 cardiac cycles for each measurement.
Statistical Analysis
Results were expressed as mean±SD. Comparisons of continuous variables among 3 or more groups were performed by Kruskal-Wallis test. When the Kruskal-Wallis test gave significant results, Scheffè’s test was conducted for multiple comparisons. For comparison of each variable between before and after operation, we used Wilcoxson test. Determinants of the degree of preoperative and postoperative MR were explored by multiple stepwise regression analysis, entering all measured echocardiographic variables. A P<0.05 was considered statistically significant.
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Results |
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Changes in LV Volume, Mitral Leaflet Configuration, and MR
The severity of MR significantly decreased in patients without postoperative MR (P<0.01) but did not decrease in 6 patients with postoperative MR by definition (Table 2). The LVESV and EF significantly improved in patients without postoperative MR (P<0.01) but did not improve in those with it. The mitral annulus area similarly and significantly decreased in both groups (P<0.05).
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D1 significantly decreased in patients without postoperative MR (P<0.01) but significantly increased in those with postoperative MR (P<0.05). D2 similarly and significantly decreased in both groups (P<0.05). The 1 significantly decreased in patients without postoperative MR (P<0.01) but did not decrease in those with postoperative MR. The AML excursion increased significantly in patients without postoperative MR (P<0.01) but did not increase in those with. The 2 significantly increased in both groups (P<0.05), with a greater increase in patients with postoperative MR (P<0.01). The PML excursion significantly decreased in both groups (P<0.05), with a greater decrease in patients with postoperative MR (P<0.01). The ß significantly increased in patients without postoperative MR, whereas it significantly decreased in those with it (P<0.05). The CL significantly increased in patients without postoperative MR (P<0.01), whereas it failed to increase in those with.
The preoperative 1 and 2 in patients with ischemic MR were both significantly increased compared with the normal values, with significant but only modest predominance of PML tethering (plus 21±4 versus 27±9 degree, P<0.01), and the preoperative AML and PML excursion were similarly reduced. Therefore, preoperative tethering was approximately similar between AML and PML. Postoperative 1 and 2 in patients with persistent MR, however, were significantly increased with advanced predominant PML tethering (plus 21±3 versus 81±13 degree, P<0.01). In addition, postoperative PML excursion was significantly smaller compared with that in AML in both groups. Therefore, postoperative tethering was significantly predominant for PML.
Determinants of Preoperative and Postoperative MR
Multiple regression analysis identified primary independent contribution from decreased CL along with increased d2 for preoperative MR (Table 3). Multiple regression identified primary contribution from increased 1 along with LV end-diastolic volume for the preoperative CL. These suggest that tethering of both leaflets was the main determinant of preoperative MR.
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Multiple regression analysis identified decreased CL as the primary factor determining postoperative MR, in addition to increased d1, increased 2, and increased ß. Multiple regression identified increased 2 as the primary determinant of postoperative CL, in addition to decreased PML excursion and EF. These facts suggest that tethering of both leaflets, but especially augmented PML tethering, was the main determinant of the postoperative MR (Figure 3).
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Figure 4 demonstrates representative patients. The patient in the upper panels without persistent ischemic MR was associated with relatively mild PML tethering, whereas the patient in the middle panels with persistent MR was associated with highly advanced PML tethering.
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Change in LV Volume and Change in Mitral Leaflet Tethering After Surgery
Reduction in LVESV after surgery was significantly correlated with less leaflet tethering (
MR jet width: r2=0.38, P=0.0003; 1: r2=0.18, P=0.02; 2: r2=0.25, P=0.005; d1/BSA: r2=0.14, P=0.04; d2: r2=0.19, P=0.02; ß: r2=0.20, P=0.01; CL: r2=0.38, P=0.0003).
MR Jet Direction
Preoperatively, MR jet direction was central in 24 patients and posterior in 7 patients with the absence of anterior jet. Postoperative jet direction, however, was anterior in 2, central in 4, and posterior in no patients with significant difference in the incidence of posterior jet (P<0.01).
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Discussion |
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Different Mitral Leaflet Configurations in Preoperative and Postoperative Ischemic MR
This study has demonstrated that ischemic MR without surgical ring annuloplasty is associated with similarly augmented AML and PML tethering. After the surgery, PML tethering significantly increased, but there was no major change in AML in patients with persistent MR. Therefore, AML and PML tethering is highly asymmetric, with PML predominance in patients with persistent ischemic MR. Augmented posterior displacement of the coaptation after annuloplasty in patients with persistent MR can be explained as a result of restricted PML excursion toward coaptation. This augmented PML tethering contributed to the reduced CL with persistent MR after ring annuloplasty.
Relation to Previous Studies
Hung et al6 has found that ischemic MR can occasionally develop even with surgical ring annuloplasty and is related to leaflet tethering, as is the case for ischemic MR in patients without annuloplasty. Restricted PML motion has been observed by Green et al14 in normal animal hearts after surgical ring annuloplasty, suggesting an important role of PML tethering in postoperative ischemic MR. The results of the current study are consistent with these reports and further revealed the importance of augmented PML tethering that contributes to the persistent ischemic MR after ring annuloplasty.
Usual AML prolapse develops posterior jet direction. Even in ischemic MR with tethering of both leaflets, less tethering of AML with its relative prolapse cause posterior jet (Figure 4, lower panels).13 In this case, AML tip coapts with the body of PML, creating an MR orifice that resembles a funnel pointed posteriorly. Leaflet configuration of persistent ischemic MR in this study is a different form of malcoaptation, which can be described as "asymmetric PML tethering." In this case, AML tip also coapts with the body of the PML, creating an MR orifice that also resemble a funnel. This funnel is pointed anteriorly, however, because of the advanced PML tethering and causes central to anterior jet. Change in MR jet direction from central to posterior in the preoperative phase to central to anterior afterward suggests a mechanistic change of MR. The precise mechanism of MR jet direction and relations between the direction and the severity of MR or undersized ring annuloplasty remain uninvestigated.
Clinical Implications
Mitral annuloplasty per se does not relieve ventricular tethering; however, it is effective in the repair of ischemic MR, because it can reduce the anteroposterior diameter of the annulus and restore reduced CL by ventricular tethering.5 Disappearance of MR in most patients in this study confirmed the effects of ring annuloplasty for ischemic MR. The tethering of PML, however, was significantly increased afterward. Therefore, mitral annuloplasty reduces the anteroposterior diameter of the annulus and MR at the expense of augmented PML tethering. When the former effect is predominant, MR can be eliminated. When the former is not predominant, persistent MR may develop. The results of this study suggest the need for aggressive undersized annuloplasty, because restricted PML forces AML to cover whole annulus alone. AML longer than the anteroposterior diameter of the annulus is required, and undersized annuloplasty will have a beneficial effect. At the same time, a more posterior location of the coaptation (2 >90°) and significant bending of AML because of its tethering from basal chordae in patients with persistent ischemic MR in the present study suggest that AML considerably longer than the anteroposterior diameter of the annulus is required to prevent leakage when the tethering is advanced. In addition, reduction in LVESV after the surgery was associated with less tethering. Therefore, the results of the present study also encourage interventions for addressing ventricular tethering. Such approaches may include LV plasty with volume reduction, chordal elongation or cutting, PM displacement, and leaflet elongation procedures.19–23 Because of the importance of augmented PML tethering in persistent ischemic MR, evaluation of both AML and PML tethering and interventions to specifically attenuate tethering of PML are also encouraged.23
Limitations
The current study addressed the mechanism of persistent ischemic MR early after surgery but did not address late-onset MR afterward. Multiple factors, such as the loss or deformity of physiological 3-dimensional saddle shape of the annulus, were not evaluated. The number of patients is small and they had heterogeneous etiology of ischemic MR. The procedures were not randomly performed and were heterogeneous, with multiple types of LV plasty without highly undersized annuloplasty. Therefore, the incidence or mechanisms of persistent ischemic MR after isolated annuloplasty in a different location of myocardial infarction, effects of rigid or semi-rigid and flexible ring annuloplasty with or without aggressive undersizing, and effects of different types of LV plasty were not accurately evaluated. Nevertheless, the purpose of this study was achieved by demonstrating augmented PML tethering by surgical ring annuloplasty and its significant contribution for the persistent ischemic MR afterward.
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Acknowledgments |
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Dr Otsuji was supported by Grants-in-Aid for scientific Research 1559076 and 1559076 from the Japan Society for the Promoting of Science, Tokyo, Japan.
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Footnotes |
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*The first 2 authors contributed equally to this work.
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References |
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TopAbstractIntroductionMethodsResultsDiscussionReferences |
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- Bolling SF, Pagani FD, Deeb GM, Bach DS. Intermediate-term outcome of mitral reconstruction in cardiomyopathy. J Thorac Cardiovasc Surg. 1998; 115: 381–386.
[Abstract/Free Full Text]
- Bax JJ, Braun J, Somer ST, Klautz R, Holman ER, Versteegh MI, Boersma E, Schalij MJ, van der Wall EE, Dion RA. Restrictive annuloplasty and coronary revascularization in ischemic mitral regurgitation results in reverse left ventricular remodeling. Circulation. 2004; 110 (suppl II): II-103–II-108.
- Calafiore AM, Gallina S, Di Mauro M, Gaeta F, Iaco AL, D’Alessandro S, Mazzei V, Di Giammarco G. Mitral valve procedure in dilated cardiomyopathy: repair or replacement? Ann Thorac Surg. 2001; 71: 1146–1152.
[Abstract/Free Full Text]
- Tahta SA, Oury JH, Maxwell JM, Hiro SP, Duran CM. Outcome after mitral valve repair for functional ischemic mitral regurgitation. J Heart Valve Dis. 2002; 11: 11–18.[Medline]
[Order article via Infotrieve]
- McGee JrEC, Gillinov AM, Blackstone EH, Rajeswaran J, Cohen G, Najam F, Shiota T, Sabik JF, Lytle BW, McCarthy PM, Cosgrove DM. Recurrent mitral regurgitation after annuloplasty for functional ischemic mitral regurgitation. J Thorac Cardiovasc Surg. 2004; 128: 916–924.
[Abstract/Free Full Text]
- Hung J, Papakostas L, Tahta SA, Hardy BG, Bollen BA, Duran CM, Levine RA. Mechanism of recurrent ischemic mitral regurgitation after annuloplasty: continued LV remodeling as a moving target. Circulation. 2004; 110 (suppl II): II-85–II-90.
- Dahlberg PS, Orszulak TA, Mullany CJ, Daly RC, Enriquez-Sarano M, Schaff HV. Late outcome of mitral valve surgery for patients with coronary artery disease. Ann Thorac Surg. 2003; 76: 1539–1487.
[Abstract/Free Full Text]
- Godley RW, Wann LS, Rogers EW, Feigenbaum H, Weyman AE. Incomplete mitral leaflet closure in patients with papillary muscle dysfunction. Circulation. 1981; 63: 565–571.
[Abstract/Free Full Text]
- Otsuji Y, Handschumacher MD, Schwammenthal E, Jiang L, Song JK, Guerrero JL, Vlahakes GJ, Levine RA. Insights from three-dimensional echocardiography into the mechanism of functional mitral regurgitation: direct in vivo demonstration of altered leaflet tethering geometry. Circulation. 1997; 96: 1999–2008.
[Abstract/Free Full Text]
- Yiu SF, Enriquez-Sarano M, Tribouilloy C, Seward JB, Tajik AJ. Determinants of the degree of functional mitral regurgitation in patients with systolic left ventricular dysfunction: a quantitative clinical study. Circulation. 2000; 102: 1400–1406.
[Abstract/Free Full Text]
- Gorman RC, McCaughan JS, Ratcliffe MB, Gupta KB, Streicher JT, Ferrari VA, St John-Sutton MG, Bogen DK, Edmunds LH Jr. Pathogenesis of acute ischemic mitral regurgitation in three dimensions. J Thorac Cardiovasc Surg. 1995; 109: 684–693.
[Abstract/Free Full Text]
- Komeda M, Glasson JR, Bolger AF, Daughters GT 2nd, MacIsaac A, Oesterle SN, Ingels NB Jr, Miller DC. Geometric determinants of ischemic mitral regurgitation. Circulation. 1997; 96 (suppl II): II-128–II-133.
- Agricola E, Oppizzi M, Maisano F, De Bonis M, Schinkel AFL, Torracca L, Margonato A, Melisurgo G, Alfieri O. Echocardiographic classification of chronic ischemic mitral regurgitation caused by restricted motion according to tethering pattern. Eur J Echocardiogr. 2004; 5: 326–334.
- Green GR, Dagum P, Glasson JR, Nistal JF, Daughters GT 2nd, Ingels NB Jr, Miller DC. Restricted posterior leaflet motion after mitral ring annuloplasty. Ann Thorac Surg. 1999; 68: 2100–2106.
[Abstract/Free Full Text]
- Matsumoto H, Sakata R, Iguro Y, Masuda H, Kinjo T, Yotsumoto G, Arata K, Matsumoto K. Posterior mitral annulopalsty with a flexible linear reducer. Jpn J Thorac Cardiovasc Surg. 2002; 50: 371–374.[Medline]
[Order article via Infotrieve]
- Saga T, Miyamoto T. An alternative technique for the repair of left ventricular aneurysm. Asian Cardiovasc Thorac Ann. 1999; 7: 74–75.
[Abstract/Free Full Text]
- Ormiston JA, Shah PM, Tei C, Wong M. Size and motion of the mitral valve annulus in man: I; a two-dimensional echocardiographic method and findings in normal subjects. Circulation. 1981; 64: 113–120.
[Abstract/Free Full Text]
- Nesta F, Otsuji Y, Handschumacher MD, Messas E, Leavitt M, Carpentier A, Levine RA, Hung J. Leaflet concavity: a rapid visual clue to the presence and mechanism of functional mitral regurgitation. J Am Soc Echocardiogr. 2003; 16: 1301–1308.[CrossRef][Medline]
[Order article via Infotrieve]
- Messas E, Guerrero JL, Handschumacher MD, Conrad C, Chow CM, Sullivan S, Yoganathan AP, Levine RA. Chordal cutting: a new therapeutic approach for ischemic mitral regurgitation. Circulation. 2001; 104: 1958–1963.
[Abstract/Free Full Text]
- Liel-Cohen N, Guerrero JL, Otsuji Y, Handschumacher MD, Rudski LG, Hunziker PR, Tanabe H, Scherrer-Crosbie M, Sullivan S, Levine RA. Design of a new surgical approach for ventricular remodeling to relieve ischemic mitral regurgitation: insights from 3-dimensional echocardiography. Circulation. 2000; 101: 2756–2263.
[Abstract/Free Full Text]
- 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]
- Hvass U, Tapia M, Baron F, Pouzet B, Shafy A. Papillary muscle sling: a new functional approach to mitral repair in patients with ischemic left ventricular dysfunction and functional mitral regurgitation. Ann Thorac Surg. 2003; 75: 809–811.
[Abstract/Free Full Text]
- Dobre M, Koul B, Rojer A. Anatomic and physiologic correction of the restricted posterior mitral leaflet motion in chronic ischemic mitral regurgitation. J Thorac Cardiovasc Surg. 2000; 120: 409–411.
[Free Full Text]
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