Procedure

The edge-to-edge repair

San Raffaele University Hospital, Department of Cardiac Surgery, Via Olgettina 60, 20132 Milan, Italy

^* Corresponding author: ^* Tel.: +39-02-2643 7102; fax: +39-02-2643 7125. E-mail: ottavio.alfieri{at}hsr.it

	Summary

Top Summary Introduction Surgical technique Surgical procedure Clinical experience and results Controversial issues Conclusions References

 
The edge-to-edge is a relatively new technique to treat mitral regurgitation. First introduced in 1991, it has been widely used in patients with severe mitral regurgitation due to complex lesions, requiring demanding surgical techniques for correction or with expected low chan-ces of successful repair. This alternative surgical approach consists of anchoring the free edge of the diseased leaflet to the corresponding edge of the opposing leaflet. Because of its effectiveness and durability, the edge-to-edge technique can be a useful addition to the surgical armamentarium in mitral valve reconstruction. Surgical techniques, indications, results and controversial issues of this type of repair are reported and discussed.

Key Words: Edge-to-edge technique • Mitral valve • Mitral regurgitation

	Introduction

Top Summary Introduction Surgical technique Surgical procedure Clinical experience and results Controversial issues Conclusions References

 
The edge-to-edge technique has been introduced in the early 1990s as a simple and effective surgical procedure for the treatment of mitral regurgitation due to complex lesions [1, 2]. The basic concept of this technique is that mitral regurgitation can be corrected simply by suturing the free edge of the diseased leaflet to the corresponding edge of the opposing leaflet exactly where the regurgitant jet is located.

When the jet of regurgitation is in the central part of the mitral valve, the application of the edge-to-edge technique produces a double orifice valve configuration (‘double orifice repair’) (Schematic 1). On theother hand, when the mitral valve lesion is localized in proximity of a commissure, its surgical correction by the edge-to-edge, results in a single orifice mitral valve with a relatively smaller area (‘paracommissural repair’) (Schematic 2).

View larger version (34K): [in this window] [in a new window]   Schematic 1 The edge-to-edge technique used as a double orifice repair.

View larger version (32K): [in this window] [in a new window]   Schematic 2 The edge-to-edge technique used as a paracommissural repair.

Click on image to view video Video 1 Preoperative transesophageal echocardiography shows redundancy of the mitral valve and its apparatus and severe regurgitation with multiple jets in a patient with bileaflet mitral valve prolapse due to Barlow's disease.

• Bileaflet prolapse (Barlow's disease);
  
• Anterior leaflet prolapse;
  
• Commissural prolapse;
  
• Functional mitral regurgitation (secondary to ischemic or idiopathic dilated cardiomyopathy).
  

Leaflet prolapse or flail are typically found in presence of degenerative mitral valve disease, which certainly represents the most common target of the edge-to-edge repair. However, if those lesions are encountered as consequences of an endocarditis process, they can still be successfully treated with the same technique.

	Surgical technique

Top Summary Introduction Surgical technique Surgical procedure Clinical experience and results Controversial issues Conclusions References

 
General principles
The edge-to-edge mitral valve repair can be performed through a conventional midline sternotomy or, in a minority of selected cases, through a small right thoracotomy (Photo 1).

View larger version (116K): [in this window] [in a new window]   Photo 1 A 6-cm anterior minithoracotomy performed in a young patient for correction of severe mitral regurgitation due to bileaflet prolapse by means of the edge-to-edge technique.

Click on image to view video Video 2 To improve the exposure of the mitral valve, the interatrial groove is carefully dissected by diathermy before the incision of the left atrium.

Click on image to view video Video 3 Access to the mitral valve is usually achieved through a conventional left atriotomy.

View larger version (102K): [in this window] [in a new window]   Photo 2 Through the right jugular vein a 14F cannula is percutaneously inserted into the superior vena cava for venous drainage.

View larger version (90K): [in this window] [in a new window]   Photo 3 Skin incision at the 4th intercostal space for the right anterior minithoracotomy approach.

View larger version (110K): [in this window] [in a new window]   Photo 4 Final view of the minithoracotomy access after positioning of the rib spreader.

View larger version (122K): [in this window] [in a new window]   Photo 5 Femoral artery and vein cannulation for institution of the cardiopulmonary bypass.

	Surgical procedure

Top Summary Introduction Surgical technique Surgical procedure Clinical experience and results Controversial issues Conclusions References

In case of ‘double orifice repair’, it is mandatory to identify correctly the middle portion of the leaflets to avoid valve distortion and residual leakage (Videos 4 and 5). A 4-0 polypropylene suture is then passed in a standardized manner along the free edge of themiddle scallop of the anterior and posterior leaflets (Videos 6,7,8,9). Pledgets are not necessary. As a general rule, the width of the suture should be minimized to reduce the risk of valvular stenosis. After reconstruction, the residual mitral area can be measured, if necessary, by introducing Hegar valve dilators into the orifices: a global valve area of more than 2.5 cm² is usually considered acceptable for ‘normal size’ patients (Video 10). Ring annuloplasty is recommended to complete and stabilize the repair (Videos 11 and 12). Final competence is evaluated by forceful saline filling of the left ventricle (Video 13).

Click on image to view video Video 4 The mitral valve is carefully inspected. In this case of mitral regurgitation due to Barlow's disease, the intraoperative analysis clearly demonstrates the important redundancy of all the valve tissue with multiple scallops on both the anterior and posterior leaflets. There is significant elongation of the subvalvular apparatus with severe bileaflet prolapse.

Click on image to view video Video 5 The valve correction in this patient is well accomplished applying the edge-to-edge concept and creating a double orifice valve. For this purpose, the central portion of both leaflets has to be identified using the subvalvular apparatus as a guide. By using a nerve hook, the chordae connected to the anterolateral and posteromedial papillary muscles are recognized: the convergence point of the two groups of chordae is defined as the ‘anatomical middle’ of each leaflet.

Click on image to view video Video 6 Once this ‘anatomical middle’ has been identified, a stay stitch is passed through the central part of A2 and P2 in correspondence of the rough zone. A double arm 4-0 polypropylene suture is used. The symmetry of the two orifices created is immediately checked.

Click on image to view video Video 7 Filling of the left ventricle with saline helps in the preliminary assessment of the two orifices created which already appear to be symmetric and competent.

Click on image to view video Video 8 The edge-to-edge suture is then completed taking deep bites along the whole length of A2 and P2. A mattress followed by an over and over suture is performed through the rough zone of the leaflets. All stitches are rather deep to reduce redundancy of the tissue.

Click on image to view video Video 9 Following the double orifice repair, a cleft between P1 and P2 is identified. This defect is easily corrected by obliterating the subcommissure with a continuous 5-0 polypropylene suture.

Click on image to view video Video 10 The valve area is tested with a pair of Hegar dilators which are introduced into the anterior and posterior orifice. The global area in this case is about 4 cm2.

Click on image to view video Video 11 A number 34 Seguin (MMCTSLink 39) ring sizer is selected to measure the intertrigonal distance as well as the surface of the anterior leaflet. Ten to twelve 2-0 Tycron stitches are passed through the anterior and posterior mitral annulus for ring implantation.

Click on image to view video Video 12 Ring implantation is completed.

Click on image to view video Video 13 Water testing shows optimal competence of the valve.

Click on image to view video Video 14 Intraoperative color-Doppler transesophageal echocardiography shows no residual mitral regurgitation and two diatolic flows through the double orifice mitral valve.

• In Barlow's disease, for instance, big bites (approximately 0.5 to 1 cm deep) should be taken to enhance the strength of the repair and reduce the leaflets height in the middle of the double-orifice valve. The more redundancy is present, the deeper the stitches should be. In most cases of Barlow's disease, leaflet redundancy and prolapse is so severe that a wide suture, connecting the whole P2 free edge to the opposing A2, is necessary. Preoperative small valve area, which can be a contraindication for the edge-to-edge technique because of the increased risk of mitral stenosis, is usually not an issue in Barlow's disease since, in most of these cases, valve area is excessively wide.
  
• In presence of a flail segment, the position of the stitch may be somewhat asymmetric, corresponding to the center of the flail portion of the leaflet.
  
• Finally, in case of thin and fragile leaflets due to fibroelastic deficiency, a 5-0 rather than a 4-0 polypropylene suture should be preferred.
  

Functional mitral regurgitation
In degenerative mitral regurgitation the intraoperative inspection of the valve anatomy plays a major role in deciding the site of application and the extension of the edge-to-edge suture. On the other hand, in mitral regurgitation secondary to ischemic or idiopathic dilated cardiomyopathy, the mitral valve is structurally normal and the intraoperative inspection of its anatomy does not provide additional information. The preoperative echocardiographic study, therefore, has literally to be used as a guide for the surgical correction. In this setting, the edge-to-edge repair, really becomes an ‘echo-guided’ technique, being applied exactly in correspondence of the site of origin of the regurgitant jet as defined by the preoperative transesophageal echocardiography. When the jets of regurgitation are more than one, the edge-to-edge suture is usually applied on the largest one, relying on the undersized ring for the effective resolution of the others. In functional mitral regurgitation the edge-to-edge suture should be as short as possible to avoid the risk of stenosis considering that, in this setting, an undersized annuloplasty is always associated to complete the repair.

	Clinical experience and results

Top Summary Introduction Surgical technique Surgical procedure Clinical experience and results Controversial issues Conclusions References

 
In 2001 the results of the edge-to-edge technique used for the treatment of complex mitral valve lesions in the first 260 patients of our experience have been reported [3]. Degenerative disease was the etiology of mitral regurgitation in 80.8% of the patients, rheumatic disease in 9.6%, endocarditis in 6.1% and ischemic disease in 2.3%. Hospital mortality was 0.7% and the overall survival at 5 years 94.4%±2.59% (Graph 1). Freedom from reoperation at 5 years was 90.0%±3.37% (Graph 2) and was lower in patients with rheumatic valve disease and in patients who did not receive an annuloplasty procedure (Graphs 3 and 4).

View larger version (11K): [in this window] [in a new window]   Graph 1 Overall actuarial survival. (Reproduced from Ref. [3] with permission from the American Association for Thoracic Surgery.)

View larger version (13K): [in this window] [in a new window]   Graph 2 Overall actuarial freedom from reoperation. (Reproduced from Ref. [3] with permission from the American Association for Thoracic Surgery.)

View larger version (16K): [in this window] [in a new window]   Graph 3 Freedom from reoperation according to etiology. (Reproduced from Ref. [3] with permission from the American Association for Thoracic Surgery.)

View larger version (16K): [in this window] [in a new window]   Graph 4 Freedom from reoperation in patients who received annuloplasty versus those who did not. (Reproduced from Ref. [3] with permission from the American Association for Thoracic Surgery.)

Bileaflet prolapse
From 1991 to 2003, 423 consecutive patients affected by severe mitral regurgitation due to Barlow's disease underwent mitral valve repair with the edge-to-edge technique. Hospital mortality was 0.7%. Actuarial survival at 5 years was 94%±2.8% and freedom from reoperation 91%±3.4% with no patients requiring late reoperation for mitral valve stenosis. Excluding patients undergoing associated cardiac procedures, mean cardiopulmonary bypass and ischemic times were 45±10.1 min and 32±5.7 min. Echocardiographic follow-ups show good results of the repair, with stable competence and no progression of valve stenosis: indeed, the mean mitral valve area, assessed in a subgroup of 82 patients, was 10.2±2.1 cm² preoperatively, it decreased to 3.7±0.8 cm² after repair and did not significantly change at follow-up remaining at 3.6±0.97 cm² [4].

Anterior leaflet prolapse
From 1991 through April 2003, 150 consecutive patients with isolated segmental AML prolapse had mitral valve repair with the edge-to-edge technique as a double orifice (116 patients) or a paracommissural repair (34 patients). The mean period of follow-up was 4.5±3.21 years (range 2 months to 12 years). Hospital mortality was 0.6% (1/150). At nine years, the actuarial overall survival was 91.6%±3.16 and the freedom from reoperation was excellent (Graph 5). Univariable and multivariable analysis showed the absence of annuloplasty to be the only independent risk factor for reoperation.

View larger version (14K): [in this window] [in a new window]   Graph 5 Freedom from reoperation after edge-to-edge technique for correction of isolated anterior leaflet prolapse. (Reproduced from Ref. [5] with permission from Elsevier.)

Commissural prolapse
This type of lesion is usually considered to be an incremental risk factor for suboptimal mitral valve repair. The edge-to-edge technique, as a commissural approach, can be effectively used in case of pure commissural prolapse of one or both leaflets due to degenerative or post-endocarditis lesions. Out of 32 patients submitted to this type of repair, there was no hospital mortality and no reoperation was required at a mean follow-up of 2.4±1.81 years (range1–5.8 years). At the last echocardiogram mitral regurgitation was absent in 12 patients (37.5%), mild in 19 patients (59.3%) and moderate in one (3.1%). Mean mitral valve area was 2.9±0.42 cm² and mean transvalvular gradient 3.8±0.53 mmHg with no signs of mitral stenosis.

Functional mitral regurgitation
In functional mitral regurgitation, valve repair with an undersized annuloplasty is immediately effective in most of the cases, but a significant failure rate has been reported at mid-term, particularly in presence of marked tethering of the leaflets or when complex regurgitant jets are identified [6,7,8,9]. To enhance the likelihood of a successful and durable correction, a central or paracommissurale edge-to-edge can be added to the undersized annuloplasty, placing the approximating stitch according to the location of the regurgitant jet at the echo study [10]. The rationale of the edge-to-edge procedure in functional mitral regurgitation is three-fold: to suture the leaflets in the region of the lack of coaptation, to enable early valve closure abolishing the so-called ‘leaflet loitering effect’ [11] and, possibly, to counteract the progression of the LV remodeling through a kind of ‘reins’ effect on the LV chamber. In 54 patients with end-stage dilated cardiomyopathy (EF<35%), severe functional mitral regurgitation and significant leaflet tethering (coaptation depth 1 cm), the edge-to-edge technique was associated to the undersized annuloplasty with encouraging early and mid-term results. Hospital mortality was 3.7% (2/54) and freedom from recurrence of mitral regurgitation 3+/4+ was 95.0%±3.40% at 2.7 years. NYHA class improved from 3.3±0.5 to 1.3±0.7 (P<0.0001).

	Controversial issues

Top Summary Introduction Surgical technique Surgical procedure Clinical experience and results Controversial issues Conclusions References

 
Associate annuloplasty
The opportunity to associate an annuloplasty procedure to every edge-to-edge repair has been debated for many years. On the base of our experience, we would recommend to add an annuloplasty to the edge-to-edge technique whenever possible. The annuloplasty stabilizes the reconstruction reducing the stress on the edge-to-edge suture and increases the coaptation surface of the leaflets enhancing the competence of the valve. Moreover, it prevents the possibility of subsequent annular dilatation potentially improving the long-term results of the mitral correction. In our experience, freedom from reoperation has been 92±3% at 5 years in presence of annuloplasty and 79±10% when the annuloplasty was not associated to the edge-to-edge technique (P=0.02) [3].

In presence of mitral regurgitation and severely calcified annulus, when a ring prosthesis cannot be added to the procedure, we currently do not advocate the edge-to-edge technique as an isolated procedure [12].

Hemodynamics
The double orifice configuration of the mitral valve has raised several concerns about its hemodynamics during ventricular filling. A computational model, together with the clinical experience, however, has clearly demonstrated that the double orifice shape does not have any influence on the mitral hemodynamic, which depends exclusively on the total valve area and on the cardiac output [13]. Indeed, in a double-orifice valve configuration, the velocity of the flow through each orifice is very similar to the one observed through a single orifice valve of area equal to the sum of the areas of the two orifices. Moreover, the flow velocities through the two orifices are exactly the same, even when the orifice sizes are significantly different. This means that the Doppler sampling of any of the two orifices is sufficient to assess the hemodynamic of the mitral valve.

Risk of functional mitral stenosis
Another major issue regarding this type of repair is the potential for creating functional mitral stenosis, especially with exercise. Low mitral gradients have been measured at rest in patients at short to medium-term follow-up. Moreover, an exercise echocardiographic study [14] has clearly demonstrated that the artificially created double orifice valves follow a physiologic behavior under stress conditions, with a good valvular reserve and no functional mitral stenosis in response to the increased cardiac output (Graphs 6 and 7).

View larger version (24K): [in this window] [in a new window]   Graph 6 Response of mean (top) and maximum (bottom) mitral gradient to exercise (P<0.00001 compared to baseline). (Reproduced from Ref. [14] with permission from the Journal of Heart Valve Disease.)

View larger version (23K): [in this window] [in a new window]   Graph 7 Exercise-induced change in planimetric valve area (P<0.00001 compared to baseline). (Reproduced from Ref. [14] with permission from the Journal of Heart Valve Disease.)

	Conclusions

Top Summary Introduction Surgical technique Surgical procedure Clinical experience and results Controversial issues Conclusions References

This technique has shown to be reproducible and durable at long-term follow-up. Its reliability and simplicity have led to its application in minimally invasive mitral surgery.

	References

Top Summary Introduction Surgical technique Surgical procedure Clinical experience and results Controversial issues Conclusions References

 

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