Volume 13, Issue 2 , Pages 83-90, Summer 2008
Gore-Tex Loop Implantation for Mitral Valve Prolapse: The Leipzig Loop Technique
Article Outline
Reconstructive heart valve surgery has become more common as surgeons make a concerted effort to perform more valve repair than valve replacement operations, and as evidence continues to accrue on the benefits of valve repair. For mitral valve (MV) repair surgery in particular, many techniques have evolved over the last two decades. Most repair techniques have been developed to address the most common form of MV pathologic disease in developed countries, ie, degenerative MV disease, with its typical features of excess leaflet tissue, leaflet prolapse, and chordae elongation and/or rupture.
We started performing the majority of our MV repair operations through a minimal invasive right lateral mini-thoracotomy in 1996. One of the limitations of this approach is the technical difficulty in obtaining precise neo-chordae length when using Gore-Tex (W.L. Gore & Associates, Inc, Flagstaff, AZ) sutures to correct anterior mitral leaflet prolapse. We therefore developed the “Loop technique” in 2000 as a method to reproducibly construct anterior leaflet neo-chordae through a small incision.1 We subsequently noted that the Loop technique could also be used to correct posterior and bileaflet prolapse, and that it could be also applied through a median sternotomy.
The main principle of the Loop technique is to restore native leaflet anatomy by implanting normal length mitral chordae substitutes without the excision of any leaflet tissue. The mitral chordae substitutes consist of loops of polytetrafluoroethylene (PTFE; Gore-Tex, W.L. Gore & Associates, Inc) sutures. Gore-Tex sutures have been used for many years in conventional MV repair surgery with excellent long-term durability. When compared with native chordae, PTFE seems to provide nearly equivalent biomechanical properties in terms of flexibility, durability, and strength.
We have found that the results of the Loop technique do not depend on the surgical approach and that it is easily applicable via a full sternotomy, through minimally invasive surgery with or without videoscopic guidance, or through a robotic-assisted approach. Since the minimally invasive approach is our technique of choice for MV surgery, however, the descriptions in this article are made predominantly from the viewpoint of a minimally invasive procedure.2 We attempt to precisely describe the Leipzig Loop technique using the example of a patient with isolated A1-A2 prolapse.
Operative Technique
Figure 1.
The minimally invasive approach includes a right lateral mini-thoracotomy starting from the mid-clavicular line in the fourth intercostal space and extending 5 to 8 cm laterally. A soft-tissue retractor is inserted, which can later be used to anchor retraction sutures from the pericardium. A small rib spreader is introduced through the soft-tissue retractor and gradually opened, avoiding fracture of the ribs. A 10-mm videoscopic port and camera are inserted through the second or third intercostal space, enabling a detailed view of the operative field. Cardiopulmonary bypass (CPB) is instituted via cannulation of the femoral vessels. A 5-mm incision is made just lateral to the sternum in the right fourth intercostal space, through which a left atrial retractor is inserted. A transthoracic aortic clamp is then brought in through a 5-mm incision a few centimeters cranial to the line of the mini-thoracotomy.3 This incision will be used postoperatively for thoracic wound drainage. The ascending aorta is clamped and the heart is arrested with 2 liters of crystalloid cardioplegia solution delivered through a long, rigid needle. The cardioplegia needle is inserted into the anterior surface of the ascending aorta, which serves as a de-airing location when weaning from CPB. After cardioplegic arrest, the MV is accessed via a left atriotomy that is performed just posterior to the interatrial groove. The atriotomy does not need to be as large as for a standard sternotomy approach. CPB = cardiopulmonary bypass.
Figure 2.
The loops are constructed from 5-0 PTFE sutures, more commonly known as Gore-Tex (A). When this technique was first developed, the loops were prepared during surgery as needed. With growing experience, however, the loops are now made preoperatively by highly experienced scrub nurses and are therefore immediately available on the shelf in a variety of premeasured lengths. The making of loops in brief: after setting the exact length of the loops with a custom-made caliper (B), the Gore-Tex sutures are wrapped around the two jaws of the caliper and several knots are tied after each loop. Once four separate loops have been constructed, the suture is passed through a felt pledget and secured with 10 to 12 knots. Since the construction of loops can be time consuming, it is recommended to have the loops already prepared and available in a variety of sizes between 10 and 26 mm (in 2-mm increments).
Figure 3.
This figure shows a typical morphology of degenerative mitral valve disease with a large A1-A2 prolapse secondary to chordae elongation and rupture (A). We have chosen A1-A2 prolapse for illustration purposes only. There is little difference between the Loop technique for repair of anterior or posterior leaflet prolapse, with the exception that loops to the anterior leaflet are longer (on average, 7 mm longer) to prevent restriction of anterior leaflet motion and subsequent systolic anterior motion. The anchorage of the loops on the mitral leaflet in this particular case of an A1-A2 prolapse is depicted in (B). Regarding the anchorage of the loops on the mitral leaflet, we strongly recommend two “rules”: (1) never cross the midline (C). The loops must not cross the imaginary midline of the mitral valve and thus need to be kept on either the posteromedial or the anterolateral side, corresponding to the papillary muscle to which they are anchored. We have discovered that crossing the midline may lead to leaflet distortion and mitral regurgitation. In the present case of A1-A2 prolapse, we recommend a minimum of 12 loops (ie, three separate Gore-Tex sutures with four loops each, two anchored to the anterolateral and one to the posteromedial papillary muscle). (2) The loops should arise from the papillary muscle on the side facing the leaflet prolapse (see also Figure 5). The two needles of the loop sutures are passed through the body of the papillary muscle and then through a felt pledget on the opposite side, leaving the loops on the prolapsing side of the papillary muscle. This ensures that the whole body of the papillary muscle is used to anchor the loop suture and therefore maximizes stability. There is no limitation to the number of loops that can be used, but our maximum has been five separate Gore-Tex loop sutures resulting in 20 separate loops.
Figure 4.
The most important technical challenge of the Loop technique is determining the correct length of Gore-Tex loops. A custom-made measuring device (Geister Inc, Tuttlingen, Germany) is introduced to assess the exact distance between the papillary muscle and a nonprolapsing portion of the free edge of the leaflet (A). This device is based on the principle of an adjustable ruler and consists of a rigid and a flexible jaw with a snap-in scale on the bar end (B). The distal jaw of the measuring device must be placed on the point of the papillary muscle where the loops will be secured, usually 3 to 5 mm below the tip of the muscle. From this point the distance to a nonprolapsing portion of the free edge of the leaflet is assessed by adjusting the proximal moveable jaw of the caliper (B). The exact length of the loops represented by the measurement can then be read off from the handle of the device containing the ruler (B). If the entire leaflet is prolapsing and there is no normal segment to act as a control, then the distance must be estimated from the papillary muscle to the plane of the annulus. It is important to note which side of the papillary muscle the loops will be secured, since it influences the length of the loops. As mentioned above, however, we suggest that the loops are positioned so that they face the prolapsing segment of the leaflet. (Color version of figure is available online at http://www.optechtcs.com.)
Figure 5.
The correct sized loops are secured to the papillary muscle by using the full body of the muscle, rather than the side or the tip. The needles from the Gore-Tex loop suture are passed through a second felt pledget and then tied on the opposite side of papillary muscle. As mentioned previously, loops that are anchored to the posteromedial papillary muscle should be attached to the medial half of the mitral valve leaflets (A) and loops that are anchored to the anterolateral papillary muscle should be attached to the lateral half of the mitral valve leaflets (B).
Figure 6.
The free loops are then secured to the coaptation point of the leaflet using separate 5-0 Gore-Tex sutures. A separate 5-0 Gore-Tex suture is passed through one free loop at a time, ie, one 5-0 Gore-Tex for each loop. These sutures are then passed through the mitral leaflet tissue from the ventricular side to the atrial side and then reversed. We recommend anchoring each loop approximately 3 to 5 mm apart on the leaflet. Each suture is then tied conventionally with the knots on the ventricular side of the leaflet. If inevitable, the knots can also be placed on the atrial side. The best location to secure the loops is to the line of coaptation, which is represented by the transition from the rough to the smooth zone. In patients with severe prolapse and markedly redundant leaflet tissue, however, the new coaptation point may be located entirely on the smooth zone of the leaflet. This will result in excess leaflet tissue below the new line of coaptation (ie, within the ventricle), but we have never noticed any adverse hemodynamic effect from this excess tissue.
Figure 7.
Annuloplasty sutures and a ring are inserted in a conventional manner. After completion of the repair, mitral valve competency is tested with the injection of saline into the left ventricle. Enough saline needs to be injected to create adequate pressure on the ventricular side to unveil any residual prolapse and to evaluate if correct-sized loops were implanted.
Conclusions
At the Leipzig Heart Center, we have performed over 2500 mitral valve operations between 1999 and 2007. Almost 2000 patients were operated using the minimally invasive technique. The majority of these patients had degenerative mitral valve disease. Since we first started using the Loop technique, our confidence in its results has steadily grown. The number of Loop technique procedures has therefore steadily increased, now approaching 700 patients.4, 5 We have applied this technique on the posterior leaflet in approximately 350 patients, on the anterior leaflet in 150 patients, and on both leaflets in 200 patients. The number of loops used on the P2 segment was 3.2 ± 0.1 (mean ± SD) and 2.7 ± 1 on the A2 segment. The mean length of loops for P2 repair was 14 ± 3.1 mm and on A2 was 21 ± 3.3 mm. Early results were excellent with postoperative echocardiography showing none or trivial mitral valve regurgitation in more than 97% of patients. Thirty-day and 1-year mortality rates were 1.5 and 2.6%, respectively. None of the 12 cardiac reoperations in this patient group were related to the implanted loops, and we have not observed any patients with a ruptured or dislocated loop.
We believe the Loop technique is simple and reproducible. It has proven to be of utmost value in patients undergoing minimal invasive mitral valve repair, where standard leaflet resection techniques can be a challenge to perform. We have also been very impressed with the Loop technique in patients operated on through a full sternotomy. Therefore we consider the Loop technique our procedure of choice for patients with mitral valve prolapse.
References
- . Chordal replacement for both minimally invasive and conventional mitral valve surgery using premeasured Gore-Tex loops. Ann Thorac Surg. 2000;70:2166–2168
- The evolution of minimally invasive mitral valve surgery: two years experience. Eur J Cardiothorac Surg. 1999;15:233–239
- . Minimally invasive mitral valve repair: using a mini-thoracotomy and transthoracic aortic occlusion. Ann Thorac Surg. 1997;63:1477–1479
- . Gor-Tex chordoplasty in degenerative mitral valve repair. Semin Thorac Cardiovasc Surg. 2007;19:111–115
- Early and mid-term results of mitral valve repair using premeasured Gore-Tex loops (“loop technique”). Eur J Cardiothorac Surg. 2008;Feb11 (Epub ahead of print)
PII: S1522-2942(08)00031-7
doi:10.1053/j.optechstcvs.2008.03.004
© 2008 Elsevier Inc. All rights reserved.
Volume 13, Issue 2 , Pages 83-90, Summer 2008
