The attachment of the chords to the mitral valve leaflets.
The techniques to implant the artificial chords are many and might vary considerably from one center to another. However, they can be summarized into three big families of suturing techniques: single20,21, running9 or loop chords.22
In the former technique, the ePTFE suture is passed through the free margin of the leaflet and anchored to the fibrous part of the PM. On the free margin of the leaflet, the suture is passed with both ends, which are then secured with knots.
At mid-term follow up, freedom from reintervention was 96 ± 4%, with only one patient undergoing reoperation because of hemolysis, but at the time of redo surgery, the artificial chords were found intact. In the same study, freedom from recurrent mitral regurgitation was 94 ± 4%23.
Tirone David introduced the running suture to anchor ePTFE to the leaflet24. The suture is passed through the fibrous portion of the PM and the ends are tied together, leaving one end longer than the other. Then, the longer arm of the suture is passed one or two times through leaflet, 4-5 mm apart in the free margin. The same arm of the suture is brought inside the ventricle and passed again into PM head and then passed again through the free margin and from there back into the PM tip so to obtain numerous pairs of new chords (also known as multiple-loop technique). Recently, David25 presented 20-year follow up, showing a cumulative of reoperation and MR recurrence were 4.2% and 14.1%, respectively. In case of running chords implantation, it is advisable to implant at least two sets because, if one breaks, there is still another one that is able to anchor the leaflet to the papillary muscle. Moreover, multiple sets even out the tension on the single suture and the chords adapt to the pressure exerted on the leaflet during systolic contraction.
Finally, surgeons from Leipzig22 introduced the concept of the loop technique. It permits to create multiple loops of a prefixed length and anchored to a pledget placed on the PM, and each loop ligated to the free margin of the prolapsing segment with the knotting on the ventricular side, to avoid distortion of the free margin of the leaflet. The Leipzig group26 recently published the results of their technique with a freedom from re-operation at 10 years up to 97 ± 1%.
Some modifications of the standard loop technique have been proposed over the years27.28; the use of small anchors to make easier eventual length adjustment after the hydrostatic test27, or the use of small pieces of paper as wide as the desired length of the loop, which is tight around it28.