The neochord mitral valve repair procedure: Numerical simulation of different neochords tensioning protocols

Actual perspective on off-pump transapical artificial chord implantation

Mitral valve repair (MVR) is undisputedly associated with better clinical and functional outcomes than any other type of valve substitute. Conventional mitral valve surgery in dedicated high-volume centers can assure excellent results in terms of mortality and freedom from mitral regurgitation (MR) recurrence but requires cardiopulmonary bypass (CPB) and cardioplegic heart arrest. Trying to replicate the percentage of success of surgical MVR is the aim of all new transcatheter mitral dedicated devices. In particular, transapical beating-heart mitral valve repair by artificial chordae implantation with transesophageal echocardiography guidance is an expanding field. The safety and feasibility of the procedure have already been largely demonstrated with Neochord and more recently with Harpoon systems. Wang et al. present the outcomes of the first-in-human experience using a novel artificial chordae implantation device, the Mitralstitch system. Despite a quite small cohort of only 10 patients treated, 1-year results are satisfying and comparable with the early experience with former devices (4 patients with moderate or more MR recurrence). The comparison with surgical MVR is still unfavorable and requires further studies and significant procedure improvement. However, the device permits the treatment of anterior and posterior leaflets prolapse and performs quite easily edge-to-edge reparation. It will be interesting to evaluate longer follow-up in larger cohorts of patients as well as the possibility to shift to the transfemoral approach.

Biomechanical engineering analysis of commonly utilized mitral neochordae

Objective

To evaluate the suture rupture forces of commonly clinically utilized neochord repair techniques to identify the most biomechanically resistant most biomechanically resistant technique.

Methods

Several types of neochord techniques (standard interrupted neochordae, continuous running neochordae, and loop technique), numbers of neochordae, and suture calibers (polytetrafluoroethylene CV-3 to CV-6) were compared. To perform the tests, both ends of the neochordae were loaded in a tensile force analysis machine. During the test, the machine applied tension to the neochord until rupture was achieved. The tests were performed 3 times for each variation, and the rupture forces were averaged for statistical analysis.

Results

Rupture force was significantly higher for running neochordae relative to interrupted neochordae (P < .01). However, a single rupture in the running technique resulted in failure of the complete neochord system. For both running and interrupted neochordae, a greater number of neochordae as well as a thicker suture caliber significantly increased the neochord rupture force (P < .01). The loop technique ruptured at significantly lower forces compared with the other 2 techniques (P < .01). A greater number of loops did not significantly increase the rupture force of loop neochordae. Observed rupture forces for all techniques were higher than those normally observed in physiologic conditions.

Conclusions

Under experimental conditions, the running neochord technique has the best mechanical performance due to an increased rupture force. If using running neochordae, more than 1 independent set of multiple running neochordae are advised (ie, >2 independent sets of multiple running neochordae in each set).

Transapical off-pump mitral valve repair following prior mitral valve surgery: A case report

RATIONALE

Redo surgeries after mitral valve repair are technically demanding. Procedures applying the NeoChord device (NeoChord Inc, St. Louis Park, MN) have proven to be safe and feasible in selected patients requiring mitral valve repair due to a leaflet prolapse or flail. However, its use for redo procedures after conventional surgical repair has not been well established yet.

PATIENT CONCERNS

We report the case of a 57-year-old man who presented with dyspnea upon exertion. The patient had undergone a minimally invasive surgical mitral valve repair because of a flail leaflet of the segments segment 2 of the posterior mitral valve leaflet (P2)/segment 3 of the posterior mitral valve leaflet (P3) 4 years before.

DIAGNOSES

Transesophageal echocardiography identified a relapse of severe mitral valve regurgitation. The recurring regurgitant jet was caused by a flail leaflet due to newly ruptured native chords.

INTERVENTIONS

After discussion in an interdisciplinary heart team, we performed a minimally invasive off-pump redo procedure applying the NeoChord device under three-dimensional transesophageal echocardiographic guidance.

OUTCOMES

The echocardiographic result with only trivial residual mitral regurgitation as well as the further clinical course of the patient were favorable.

LESSONS

As redo surgery after minimally invasive mitral valve repair is challenging, the NeoChord device represents a novel treatment option that does not require cardiopulmonary bypass.

Review of transapical off-pump mitral valve intervention with NeoChord implantation

PURPOSE OF REVIEW

Mitral valve repair surgery has recently shifted from resection-based techniques to leaflet sparing approaches using synthetic neochordae. This has facilitated the growth of a new strategy of transapical off-pump mitral valve intervention with neochord implantation.

RECENT FINDINGS

Minimally invasive approaches for mitral valve repair with robotic or video-assisted mini-right anterolateral thoracotomy have been developed to mitigate the morbidity associated with conventional median sternotomy. Recently, an alternative, less invasive surgical strategy has emerged. This transapical off-pump technique employs the NeoChord DS1000 (NeoChord, Inc., Minneapolis, MN, USA) system to achieve repair with neochordae via a left minithoracotomy incision. With appropriate patient selection, advanced cardiac imaging, and training in device deployment are important for procedural success.

SUMMARY

Early results suggest that transapical off-pump mitral valve intervention with NeoChord implantation is a safe procedure with favorable outcomes for select patients with degenerative mitral regurgitation. Continued experience and clinical trials will assess the potential of this minimally invasive strategy, but this technique is likely to become part of the surgical repertoire for managing chronic degenerative mitral valve disease.

Computer simulations of transapical mitral valve repair with neochordae implantation: Clinical implications

OBJECTIVES

Transapical beating heart neochordae implantation is an innovative mitral valve repair technique that has demonstrated promising clinical results in patients with primary mitral regurgitation. However, as clinical experience continues to increase, neochordae implantation criteria have not been fully standardized. The aim of this study was to investigate the biomechanical effects of selecting an antero-lateral apical access site compared with a postero-lateral site, and suboptimal neochordae length compared with optimal suture length, on restoring physiologic left heart dynamics.

METHODS

Transapical neochordae implantation using 3 and 4 sutures was computer simulated under 3 posterior mitral leaflet prolapse conditions: isolated P2, multiscallop P2/P3 and multiscallop P2/P1. Physiologic, pre- and postrepair left heart dynamics were evaluated using a fluid-structure interaction modeling framework.

RESULTS

Despite the absence of residual mitral regurgitation in all postrepair models with optimal neochordae length, selecting an antero-lateral apical entry site for the treatment of P2/P3 prolapse generated a significant increase (>80%) in neochordae tension and P2 peak stress, with respect to a postero-lateral entry site. During isolated P2 prolapse repair, although neochordae overtension by 5% led to minimal hemodynamic changes in the regurgitant volume compared with using an optimal suture length, a significant increase in systolic and diastolic neochordae tension (>300%) and posterior leaflet average stress (70%-460%) was quantified. On the other hand, neochordae undertension by 5% led to worsening of regurgitation severity.

CONCLUSIONS

This parametric computer study represents a further step toward an improved understanding of the biomechanical outcomes of transapical neochordae technologies.