MMCTS
(March 24, 2005). doi:10.1510/mmcts.2004.000521
Copyright © 2005 European Association for Cardio-thoracic Surgery
Procedure
Mitral valve repair in ischemic mitral regurgitation
Antonio Maria Calafiorea,*,
Michele Di Maurob,
Marco Continib,
Luca Welterta and
Antonio Bivonab
a Division of Cardiac Surgery, University Hospital, "S. Giovanni Battista", c.so Bramante 86, Turin, Italy
b Division of Cardiac Surgery, "G D'Annunzio" University, Chieti, Italy
* Corresponding author: * Tel.: +39 011 6335514; Fax: +39 011 6336130. E-mail: calafiore{at}unich.it
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Summary
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Ischemic mitral regurgitation (IMR) is a common complication after acute myocardial infarction due to annulus dilatation and papillary muscles displacement. In our opinion 3/4 and 4/4 IMR have always to be indicated for MV surgery. In presence of low EF and dilated LV, moderate (2/4) IMR has to be corrected. The end-systolic distance between the coaptation point of mitral leaflets and the plane of mitral valve annulus is the key point to decide repair ( 10 mm) or replacement (>10 mm). MV annuloplasty has always been addressed to the posterior annulus, whose size can be easily reduced. A specially designed 40 mm long ring has been used to achieve a posterior overreductive annuloplasty. For MV repair thirty-day mortality was 2.4%. Five-year survival and the possibility of being alive and in NYHA class I-II were 75.6±4.7 and 59.8±5.4, respectively. After a mean of 38±35 months, the NYHA class decreases from 3.2±0.5 to 2.1±0.6 (P<0.001). Most patients (77.4%) have an improvement of its own functional class. MR decreases from 3.2±0.8 to 1.2±1.1 (P<0.001). 97.5% of the survivors have MR equal to or less than moderate.
Key Words: mitral valve • ischemic mitral regurgitation • mitral valve annulopasty
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Introduction
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Ischemic mitral regurgitation (IMR) is a common (approximately 20%) complication after completed myocardial infarction (MI), which follows more frequently an inferior MI (38%) rather than an antero-septal one (10%) [1]. The mechanisms at the base of IMR are different: 1) annular dilation [2]; 2) displacement of both papillary muscles (PM) apically, posteriorly and laterally in case of global left ventricle (LV) dilatation, with consequent increase of tethering upon closing forces and incomplete coaptation of mitral leaflets [2, 3] (Schematic 1
) [4, 5]; 3) local malfunction of the LV wall adjacent to a single PM [1, 2] (more frequently the posterior one) (Schematic 2
[4]). In this case, an asymmetrical deformation of the mitral valve (MV) from the medial to the lateral side could be present, showing a funnel-shaped deformity of the medial side and a prolapse-like deformity on the lateral side. This might develop as a result of preserved or excessive motion of the non-tethered lateral side of the anterior leaflet [2]. As a consequence, the regurgitant jet, in some cases, is double: one central and one lateral (Photo 1
[6])
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Schematic 1 (A) Ischemic mitral regurgitation due to both papillary muscles is a consequence of global left ventricle dilatation. (Reprinted from Ref. [4] with the permission of McGraw-Hill Education).
(B) This produces an increasing tethering upon closing forces and incomplete coaptation of mitral leaflets. (Reprinted from Ref. [5] with the permission of BC Decker).
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Schematic 2 Ischemic mitral regurgitation due to local malfunction of the LV wall adjacent to a single papillary muscle.
(Reprinted from Ref. [4] with the permission of McGraw-Hill Education).
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Photo 1 The regurgitant jet is generally central (A), but can be double (B) due to asymmetrical deformity of the mitral valve.
(Reprinted from Ref. [6] with the permission of Elsevier Inc.).
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Patients with IMR have a worse survival than patients without IMR [7, 8, 9]. A higher degree of IMR worsens further long term survival [8, 9].
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Surgical indication
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Despite these findings, the debate regarding surgical indications for MV surgery is still open. Some surgeons found no difference between isolated coronary artery bypass grafting (CABG) and CABG associated to MV surgery [10, 11, 12, 13], even if isolated CABG produced worse results in case of heart failure or low ejection fraction (EF) [10, 11, 12]. Other studies evidence a better outcome with MV surgery [14, 15], even in the case of moderate (2/4) IMR [15]. In our opinion 3/4 and 4/4 IMR have always to be indicated to MV surgery. In presence of low EF and dilated LV, moderate (2/4) IMR has to be corrected [6].
Although MV repair can provide better results [16], in some cases it can fail because of excessive MV tethering [17]. Coaptation depth (CD) (Photo 2
[5]) is used by us to decide if MV repair can be performed with high possibilities to achieve good results. According to our experience [18], when the MV coaptation depth is higher than 10 mm the abnormalities in the sub-valvular apparatus prevent proper coaptation of mitral leaflets, causing residual MR. In this case MV replacement is indicated [18]. The mitral valve apparatus is left intact in all its components (leaflets, chordae and papillary muscles). Only a small triangle of the anterior leaflet is resected in order to prevent its fixed position in the outflow tract of the left ventricle.
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Photo 2 Echocardiographic view: the leaflets show tented geometry; mitral annulus (A-B=45 mm) is enlarged and mitral valve coaptation depth (C-D=13 mm) is increased.
(Reprinted from Ref. [5] with the permission of BC Decker).
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Surgical technique
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The purpose of reconstructive MV surgery is to restore MV competence acting on dilated mitral annulus (MV annuloplasty). This can be obtained using complete or incomplete, manufactured or autologous pericardium rings [16, 18, 19, 20, 21], or suture annuloplasty [22]. We prefer to use a posterior ring, 40 mm long (Sovering Miniband®, MMCTSLink 19) to achieve a strong overreduction of the mitral annulus (MA) (Photo 3
). MV annuloplasty has always been addressed to the posterior annulus, whose size can be easily reduced.
All the patients have a standard monitoring, including a Swan Ganz catheter and trans-esophageal echocardiography (TEE). The ascending aorta is cannulated for arterial inflow, whereas the inferior vena cava is cannulated as usual, and the superior one is directly cannulated. Myocardial protection is achieved by means of intermittent antegrade warm blood cardioplegia.
Surgical approach is often trans-septal (Video 1
). In case of incomplete vision, the incision is continued to reach the roof of the left atrium.
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Video 1 Trans-septal surgical approach.
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When the mitral annulus is exposed, several U-stitches (12 to 16) are passed between the middle point of the posteromedial commissure and the middle point of the anterolateral commissure, using a 2/0 TI-CRONTM (MMCTSLink 7) with a small needle (20 mm) (Photo 4
[21], Video 2
).
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Photo 4 Intraoperative view: many stitches are passed between the MV commissures.
(Reprinted from Ref. [21] with the permission of Elsevier Inc.).
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Video 2 Several 2/0 TI-CRONTM stitches are passed from postero-medial commissure to the antero-lateral one.
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Each suture has to start before the end of the annulus covered by the previous suture (Schematic 3
[21]). This is necessary as MA is often soft and increasing the number of sutures reduces the stress on the MA.
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Schematic 3 Each suture starts before the end of the annulus covered by the previous suture.
(Reprinted from Ref. [21] with the permission of Elsevier Inc.).
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All the sutures are passed through the Miniband (Sovering Miniband®, MMCTSLink 19) (Video 3
). The ring is then pulled down to the posterior annulus and the sutures are tied (Video 4
), producing an overreduction of the MV annular size.
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Video 3 All the sutures are passed trough the Miniband (Sovering Miniband®, MMCTSLink 19).
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Video 4 The Miniband is pulled down and the sutures are tied.
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In case of MV replacement (the prosthesis is inserted inside the native valve), the stitches utilized to fix the prosthesis are used to attract the remnants of the anterior leaflet toward the annulus (Video 5
).
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Video 5 The mitral valve is replaced sparing the continuity between mitral valve and subvalvular apparatus.
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Results
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According to our experience [6], early and late results of patients with IMR who underwent MV repair are the following:- From June 1988 to December 2002, 102 patients with ischemic mitral regurgitation underwent mitral valve surgery, 82 repair and 20 replacement. Patients with organic MV disease, with intermittent ischemia or with PM rupture were not included in this study.
- Mean age was 66.5±8.5. Most patients (43) were older than 70 years.
- Mean preoperative NYHA class was 3.3±0.5. Ninety-nine patients were in NYHA class III-IV. Fifty-nine presented preoperative chronic heart failure.
- Thirty-day mortality was 3.9%. Death was caused by a multiorgan failure due to biologic bleeding, tracheal bleeding, rupture of abdominal aortic aneurysm and low output syndrome. Five-year survival was 73.5±4.4 (Graph 1
[6]).
- Five-year possibility of being alive and in NYHA class I-II was 56.9±5.4 (Graph 2
[6]).
- After a mean of 39±35 months, NYHA class decreases from 3.3±0.5 to 2.2±0.6 (P<0.001).
- Most patients (75%) have an improvement of the functional class.
- In patients who underwent mitral valve repair, MR decreases from 3.2±0.8 to 1.2±1.1 (P<0.001). 97.5% of the survivors have MR equal to or less than moderate.
- Preoperative NYHA class and chronic heart failure represented independent variables for lower five-year survival.
- Lower preoperative ejection fraction and higher end-diastolic and end-systolic volume had a negative impact on survival and quality of life.
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Graph 2 Five-year possibility to be alive and in NYHA class I/II.
(Reprinted from Ref. [6] with the permission of Elsevier Inc.).
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Summary
Introduction
