Premeasured neochordae loop maker: a new technology in mitral valve repair

Premeasured Neochordae Loop MakerA New Technology in Mitral Valve Repair

Alireza Alizadeh Ghavidel, MD,* Niloofar Samiei, MD,* Hoda Javadikasgari, MD,*and Kamiar Bashirpour, BSÞ

Abstract: The exact length of neochordae loops plays the major rolein the success of mitral valve repair. The Neochordae Loop Maker is anovel device that models the left ventricular structure in an individualpatient. Preoperative transthoracic echocardiography is used to iden-tify the geometry of each papillary muscle and set up the device for thepatient. All required neochordae loops are made in the operating roombefore initiating the cardiopulmonary bypass. In the calibration phase,seven consecutive patients who were candidates for mitral valve re-placement underwent transthoracic echocardiography. The device wasset up for each patient, and the length of their normal chordae and theirrespective neochordae was compared by the Bland-Altman analysis.From seven excised mitral valves, 21 chordae were considered normal(gold standard). The length of these gold standards (1.92 T 0.67 cm)and their respective neochordae (1.93 T 0.69 cm) showed agreementby the Bland-Altman analysis. The proposed technology showedsatisfactory preliminary results in creating the premeasured neochordaloops inasmuch as it reduced the complexity of minimally invasivesurgeries.

Key Words: Artificial chordae, Mitral valve repair, Minimallyinvasive mitral valve surgery.

(Innovations 2013;8:443Y449)

M itral valve prolapse is a common cardiac disease thatpredisposes patients to higher risk for serious compli-

cations. Mitral valve repair has provided excellent midtermand long-term results and is deemed gold standard therapy forpatients with severe regurgitation.1

Mitral valve repair through conventional sternotomyhas been applied for several decades, and numerous innovativemethods have been proposed to reduce its complexity. However,

the increasing popularity of less invasive procedures has affectedmitral valve surgery during the past 20 years. Despite obviouspotential benefits ofminimally invasivemitral valve surgery suchas lower morbidity, postoperative pain, blood loss, hospitallength of stay, and time to return to normal activity,2,3 acceptanceof minimally invasive and on-the-top robotic mitral valve repairhas been limited because of concern about its complexity, qualityof repair, and cost as well as its increased cross-clamp, cardio-pulmonary bypass, and procedure time.4Y6

Chordal replacement has been used for both anterior andposterior leaflet repair, with excellent long-term results. Al-though this technique offers potentially greater physiologicalrepair with preserved leaflet mobility in comparison with othertechniques, the complexity of measuring the length of neo-chordae still increases the procedure time in minimally invasivemitral valve repair.

This study reports the initial clinical experience with anew device (Neochordae LoopMaker) that enables surgeons tomake neochordae loops before commencing the cardiopul-monary bypass and might lessen the complexity and the pro-cedure time especially in minimally invasive and robotic mitralvalve repair.

TECHNIQUESThe premeasured Neochordae Loop Maker serves as a

tangible model for visualizing the three-dimensional geometryof an individual patient’s left ventricular structure. Differentparts of this device represent the papillary muscle’s head andthe free margin of the anterior and posterior mitral valve leaflets.Anterior/posterior, lateral/medial, and base-to-apex view of pre-operative transthoracic echocardiography (TTE) define the exactposition of each papillary muscle relating to the free margin ofleaflets in each patient and are used for setting up the NeochordaeLoop Maker. Therefore, surgeons prepare neochordae loops withthe exact lengths required for each patient before starting thesurgery.Themainparts of thedevice include two semilunar blades,three setup screws, and a pledget clamp (Fig. 1A).

Semilunar BladesThe semilunar blade models the free margin of the an-

terior and posterior mitral valve leaflets. The concave marginof the blade represents the free margin of the anterior leaflet,and its convex margin represents the free margin of the pos-terior leaflet (Fig. 1B). Several grooves are embedded on bothmargins representing the attachment sites of the neochordaeloops on the free margins of the mitral valve leaflets. The lateral

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Innovations & Volume 8, Number 6, November/December 2013 443

Accepted for publication October 28, 2013.From the *Heart Valve Disease Research Center, Rajaie Cardiovascular Medical

and Research Center, Iran University of Medical Sciences, Tehran, Iran; and†Mechanical Engineering Department, Amirkabir University of Technology,Tehran, Iran.

Disclosure: The authors declare no conflicts of interest.

Address correspondence and reprint requests to Hoda Javadikasgari, MD, HeartValve Disease Research Center, Rajaie Cardiovascular Medical and ResearchCenter, Iran University of Medical Sciences, Vali-Asr Ave., Niyayesh Blvd.,Tehran 199691-1151, Iran. E-mail: [email protected].

Copyright * 2013 by the International Society for Minimally InvasiveCardiothoracic Surgery

ISSN: 1556-9845/13/0806-0443

Copyright © 2013 by the International Society for Minimally Invasive Cardiothoracic Surgery. Unauthorized reproduction of this article is prohibited.

mailto:[email protected]

one-fourth portion of the concave and convex margins isconsidered the free margin of A1 and P1 scallops, respectively.The medial one-fourth portion of the concave and convexmargins is considered the free margin of A3 and P3 scallops,respectively, and the middle halves of these margins are con-sidered the free margin of A2 and P2 scallops. These removableblades (Fig. 1C) were developed in three standard sizes (28, 32,and 36) based on the size of the most useful Carpentier rings(direct measurements and published data).7 Blades number 28,32, and 36 are suitable for mitral annuluses of 30 mm or less,30 to 34 mm, and 34 mm or greater (based on echocardiographyfindings), respectively.

Pledget ClampThe pledget part of the neochordae loops is attached to

the head of the papillary muscle. Therefore, the position of thepledget in the Neochordae Loop Maker represents the place ofthe papillary muscle’s head. A clamp is designed to secure thepledget firmly through the creation of the loops. The position ofthe clamp can be changed on the basis of the position of eachpapillary muscle in an individual patient. Accordingly, sur-geons can first make the loops required for attachment to theanterolateral papillary muscle and then change the position of

the clamp to create the loops necessary for attachment to theposteromedial papillary muscle.

Setup ScrewsThree setup screws are designed to change the position of

the clamp in medial/lateral, anterior/ posterior, and up/downdimensions. The center of the semilunar blade is assumed to bethe reference point (zero point), and the position of the clamp isadjusted toward it (point R in Fig. 1B).

Transthoracic EchocardiographyThe three main views of TTE, that is, two-chamber, four-

chamber, and apical long-axis views, are used to determine thethree-dimensional geometry of the left ventricular structure inan individual patient. Although transesophageal echocardiog-raphy is usually used for evaluating mitral valve regurgitation,left ventricular foreshortening in this technique would reducethe accuracy of our required measurements. We therefore ap-plied TTE, which has demonstrated less foreshortening effectand more accurate results in left ventricular distance mea-surements. The intercept between the coaptation depth line andthe annulus line (Fig. 2) is considered the zero point in TTEimages, and it corresponds to the center of the semilunar blades(point R in Fig. 1B) in the Neochordae Loop Maker.

FIGURE 1. A, Neochordae Loop Maker device. B, Schematic top view of the mitral valve and the corresponding position of thesemilunar blade. C, Semilunar blades.

Ghavidel et al Innovations & Volume 8, Number 6, November/December 2013

444 Copyright * 2013 by the International Society for Minimally Invasive Cardiothoracic Surgery


Two-Chamber ViewThis view is used to determine how much the pledget

clamp should be moved in a medial and a lateral direction for theposteromedial and the anterolateral papillary muscle, respec-tively. To compute this distance, first, the annulus line is drawn(A-B line in Fig. 3A). Then, a perpendicular line is drawn fromeach papillary muscle to the annulus line, and these two in-tercepts are marked (points M and N for the posteromedial andanterolateral papillary muscles, respectively, in Fig. 3A). Thedistance between the zero point and each intercept determinesthe medial or the lateral movement of the pledget clamp for thatpapillary muscle (O-M and O-N lines in Fig. 3A). Figure 3Bshows a schematic view for determining the medial/lateral dis-tance. Figure 3C demonstrates the top view of the NeochordaeLoop Maker. Moving the clamp to the lateral side of the zeropoint (equal to O-N distance) will place it in the position of theanterolateral papillarymuscle, andmoving it to themedial side ofthe zero point will situate it in the position of the posteromedialpapillary muscle.

Four-Chamber ViewThe side view of the anterolateral papillary muscle is best

visible here. This view is used to compute the anterior distanceof the anterolateral papillary muscle’s head from the zero point.Therefore, the annulus line (A-B line in Fig. 3D) is first drawn.Then, the perpendicular line is drawn from the papillary muscleto the annulus line, and their intercept is marked (point L inFig. 3D). The distance between the zero point and this intercept(O-L line in Fig. 3D) defines how much the pledget clampshould be moved to the anterior side of the zero point in thedevice. Figure 3E shows a schematic view for computing thisdistance. Figure 3F illustrates the top view of the NeochordaeLoop Maker. Moving the clamp toward the anterior side ofthe zero point will set it in the position of the anterolateralpapillary muscle.

Apical Long-Axis ViewThe side view of the posteromedial papillary muscle is

best visible here. Using the same technique as that in the an-terolateral papillary muscle, the posterior distance of theposteromedial papillary muscle is extracted from this view(Figs. 4A, B). Figure 3F shows that moving the clamp towardthe posterior side of the zero point (equal to O-L distance) willplace it in the position of the posteromedial papillary muscle.

The up/down direction is defined as the perpendiculardistance between the head of each papillary muscle and theannulus line (Fig. 5). Any TTE image that provides a moreoptimal longitudinal view provides a better estimate of thisdistance. Moreover, if the patient has unileaflet valve prolapse,the coaptation depth (Fig. 2) is measured first and is subse-quently subtracted from this distance. This new measure pro-vides a more accurate distance for unileaflet valve prolapse.

Developing LoopsThe length and the number of required neochordae loops

depend on the position of the prolapsed scallops. For example,if the scallop A2 is prolapsed, the surgeon opts to attach twoneochordae loops from the anterolateral papillary muscle toA2. The following steps should be taken:

1. Put the appropriate size of the semilunar blade (basedon echocardiography measurements) in the defined placeof the Neochordae Loop Maker.

2. Place the pledget in the clamp.3. Change the position of the clamp on the basis of the

three previously estimated distances (lateral, anterior, anddownward distances) for the anterolateral papillary muscle.

4. Pass the needle of a 4-0 Gore-Tex suture through thepledget and turn it around the middle groove in the A2part of the semilunar blade. Then, pass it again throughthe pledget. Now, the Gore-Tex suture can be tied in theusual manner without knot slippage. The second loopcan be made in the same way on the groove next to theprevious one.

5. Mark each loop, using a pen, on the basis of its corre-sponding position on the Neochordae Loop Maker.

6. Separate the made neochordae loops having just beencreated with their pledget from the Neochordae LoopMaker and pass another 4-0 Gore-Tex suture througheach loop.

Figure 6 shows a neochordae with two loops. These stepscould be done from any papillary muscle to any prolapsedscallop.

Surgical TechniqueThe Neochordae LoopMaker is sterilized before surgery.

In the operating room and before initiating cardiopulmonarybypass, the device is set up, and the required loops are madein a couple of minutes. After left atriotomy, the needles of theneochordae are passed through the respective papillary muscle’shead and tied over a second pledget. The 4-0 Gore-Tex suture isthen used to fix each premeasured loop to the respective pro-lapsed segment of the mitral leaflet, preferably to the atrial sur-face with the knot on the ventricular surface.

FIGURE 2. Point P is the zero point that is the intercept betweenthe coaptation depth line and the annulus line.

Innovations & Volume 8, Number 6, November/December 2013 Neochordae Loop Maker in Mitral Valve Repair

Copyright * 2013 by the International Society for Minimally Invasive Cardiothoracic Surgery 445


Clinical ExperiencesThe first phase was aimed to estimate the accuracy of

TTE measurements and the calibration of the Neochordae LoopMaker. Therefore, we designed a study to compare the length ofnormal chordae with the length of respective neochordae loopsin seven consecutive patients who were candidates for mitralvalve replacement at Rajaie Cardiovascular Medical and Re-search Center. Preoperative TTE was performed for all pa-tients, and the device was set up for each individual patient.

The patient’s excised mitral valve was preserved to measurethe size of his/her normal chordae. A chordawith no rheumaticchange or fusion and shortening or elongation was considerednormal and the gold standard for evaluating the accuracy ofthe Neochordae Loop Maker. The length of each normalchorda (gold standard) and its corresponding artificial chordaon the Neochordae Loop Maker was measured. The Bland-Altman analysis was used to assess the agreement betweenthese lengths.

FIGURE 3. A, Determining themedial/lateral distance of the papillary muscles in two-chamber view. Point O corresponds to the zeropoint. B, Schematic lateral and medial distances of the anterolateral and posteromedial papillary muscle’s head, respectively. C, Topview of the Neochordae Loop Maker. The white arrows show the direction of movement for the pledget clamp in the medial/lateraldirection. D, Determining the anterior distance of the papillary muscles in four-chamber view. Point O corresponds to the zero point.E, Schematic anterior distance of the anterolateral papillary muscle’s head. F, Top view of the Neochordae Loop Maker: the whitearrows show the direction of movement for the pledget clamp in the anterior/posterior direction.




After calibrating the device, this technique is applied in anongoing prospective randomized clinical trial (NCT01811537)to assess its efficacy in mitral valve repair.

CLINICAL EXPERIENCESCalibration Phase

The patients included two men (29%) and five women(71%) with a mean T SD age of 56.57 T 9.18 years. Twenty-one pairs of normal chordae (gold standard) and their re-spective neochordae were assessed. The mean T SD length ofthe gold standard (1.92 T 0.67) and the mean T SD lengthof neochordae (1.93 T 0.69) were not statistically different(P = 0.96). Figure 7 shows the Bland-Altman plot, which alsoconfirmed the agreement between the two measured lengths.

Clinical Experiences With Mitral Valve RepairSo far, five patients have been enrolled in the ongoing

clinical trial. No intraoperative length modification or additionalsuturewas required for all of the applied neochordae loops. Allof these patients had none or trivial mitral regurgitation byintraoperative and also 6-month follow-up transesophagealechocardiography.

DISCUSSIONMitral valve repair has shown superior results compared

with mitral valve replacement and has become the procedure ofchoice for the treatment ofmitral regurgitation.1A broad spectrumof reconstructive techniques, including ring annuloplasty, leafletresection, edge-to-edge stitch, and chordal replacement, havebeendeveloped. These techniques are notmutually exclusive and

FIGURE 4. A, Determining the posterior distance of the posteromedial papillarymuscles in apical long-axis view. Point O correspondsto the zero point. B, Schematic posterior distance of the posteromedial papillary muscle’s head.

FIGURE 5. A, Schematic downward distance of the papillarymuscles? head from the annulus line. B, Anterior view of theNeochordaeLoop Maker: the white arrows show the downward movement for the pledget clamp.




can be applied together. Furthermore, all of them have beenused in both conventional and minimally invasive mitral valverepair surgeries.

Recent studies have emphasized valve-sparing tech-niques because the resection of a large segment may not befeasible in more complex pathologies,8,9 and left ventricularoutflow tract obstruction has been observed after this tech-nique.10 However, ring annuloplasty and edge-to-edge tech-niques are not enough for more complex pathologies, andchordal replacement should also be performed. Moreover, un-satisfactory results were observed in the patients who needed aring size of less than 30 mmwith the edge-to-edge technique.11

Chordal replacement with expanded polytetrafluoroethylenesutures was introduced in the 1980s, and various reports havepublished its excellent early and long-term results.12

Various types of chordal replacement methods have beenproposed during the past decades, but none of them havesucceeded in reducing the complexity of minimally invasivemitral valve repair. One of the most popular ones is saline testduring the surgery. Although this technique seems simple, it istime consuming and requires at least one nonprolapsed scallopas a reference. Another technique is using a ruler during sur-gery to measure the length of the normal chordae and makingthree or four loops with this length.13 This technique also needslength refinement during surgery, which increases the cardio-pulmonary bypass time.

In our study, the agreement between the length of thenormal chordae of the excisedmitral valves and their respectiveneochordae loops demonstrated the accuracy of this newmethod. The successful preliminary results in the clinical phaseof this study also confirmed that our proposed technologywould be able to lessen the complexity of mitral valve repairsurgery. Because all the steps in developing neochordae loopsare taken preoperatively, this method would decrease proce-dure time and increase the quality of repair. The preliminaryresults showed that no change is needed during surgery andneochordae replacement. This method, accordingly, reducesthe complexity inherent in previous techniques when measur-ing the length or changing the size of required neochordae, es-pecially in minimally invasive and robotic surgeries.

Newer devices are under development to avoid cardio-pulmonary bypass in mitral valve repair. The concept of beat-ing heart transapical insertion of artificial chordae for mitralvalve repair has been introduced and explored in few humansubjects.14 The left ventricular apex is used as the anchor-ing point for the artificial chordae. However, recent studieshave shown that the anchoring of the neochordae at the pap-illary muscles, thereby mimicking the real anatomy, should bepreferred over the left ventricular apex.15 So far, techniques

FIGURE 6. Developed neochordae loops on the NeochordaeLoop Maker, anterior view.

FIGURE 7. Bland-Altman plot. Bolded circles demonstrate two patients’ records.




have focused on postimplantation adjustment in the beatingheart.16 Our technique is a breakthrough inmaking premeasuredneochordae loops and is applicable in beating heart mitral valverepair as well. This method anchors the papillary muscle’s headinstead of the apex and also obviates length adjustment afterimplantation.

In conclusion, our proposed technology is a practical,unique, and simple method for making neochorda loops beforestarting cardiopulmonary bypass. Accordingly, the ability ofthis technique to develop premeasured neochordae loops in acouple of minutes and preclude postimplantation length ad-justment could lessen the complexity and procedure time inminimally invasive and robotic mitral valve repair. Moreover,measuring all distances in a beating heart with preoperativeTTE may lead to better physiological and coaptation level.Further studies are required to confirm these results withminimally invasive mitral valve repair.

ACKNOWLEDGMENTSTheauthors thankAnitaSadeghpour,MD,YaldaMirmesdagh,

MD, Golrokh Bateni, and Pedram Amouzadeh for their assistancein our study.

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Premeasured neochordae loop maker: a new technology in mitral valve repair

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