Simplified nonresectional leaflet remodeling mitral valve repair for degenerative mitral regurgitation

Biomechanical engineering analysis of neochordae length's impact on chordal forces in mitral repair

OBJECTIVES

Artificial neochordae implantation is commonly used for mitral valve (MV) repair. However, neochordae length estimation can be difficult to perform. The objective was to assess the impact of neochordae length changes on MV haemodynamics and neochordal forces.

METHODS

Porcine MVs (n = 6) were implanted in an ex vivo left heart simulator. MV prolapse (MVP) was generated by excising at least 2 native primary chordae supporting the P2 segments from each papillary muscle. Two neochordae anchored on each papillary muscle were placed with 1 tied to the native chord length (exact length) and the other tied with variable lengths from 2× to 0.5× of the native length (variable length). Haemodynamics, neochordal forces and echocardiography data were collected.

RESULTS

Neochord implantation repair successfully eliminated mitral regurgitation with repaired regurgitant fractions of approximately 4% regardless of neochord length (P < 0.01). Leaflet coaptation height also significantly improved to a minimum height of 1.3 cm compared with that of MVP (0.9 ± 0.4 cm, P < 0.05). Peak and average forces on exact length neochordae increased as variable length neochordae lengths increased. Peak and average forces on the variable length neochordae increased with shortened lengths. Overall, chordal forces appeared to vary more drastically in variable length neochordae compared with exact length neochordae.

CONCLUSIONS

MV regurgitation was eliminated with neochordal repair, regardless of the neochord length. However, chordal forces varied significantly with different neochord lengths, with a preferentially greater impact on the variable length neochord. Further validation studies may be performed before translating to clinical practices.

The feasibility of mitral valve device foldoplasty: an in vivo study to evaluate durable retention

OBJECTIVES

We have previously shown in experimental settings that a leaflet foldoplasty device reduces redundant leaflet area to re-establish mitral valve (MV) coaptation. The current study investigates the in vivo device retention and functional durability following foldoplasty.

METHODS

The prototype is of superelastic nitinol formed into a 3-dimensional shape. It is unfolded to engage a specified area of leaflet tissue and then folded to exclude this tissue from the coaptation surface. Design modifications were made and tested in benchtop studies to determine the optimal design for durable retention within the leaflet. To evaluate in vivo performance, posterior leaflet chordae were severed in Yorkshire pigs to produce complete posterior leaflet prolapse and severe mitral regurgitation. Design modifications were then used for MV repair. Five animals that underwent repair using the optimal design were observed for 2 weeks postoperative to evaluate the functional result and implant retention.

RESULTS

Device position and orientation were maintained at 2 weeks while preserving the functional MV repair in all 5 animals. Coaptation height was 5.5 ± 1.5 mm, which was not significantly different from a baseline of 4.9 ± 0.8 mm. The degree of leaflet excursion was 41.0 ± 16.0 compared to a baseline of 58.7 ± 27.5.

CONCLUSIONS

Device foldoplasty is a new concept for MV repair based on the reduction of redundant leaflet tissue area. This study demonstrates the feasibility of safe maintenance of this repair without early dislodgement or embolization.

Mitral chordae tendineae force profile characterization using a posterior ventricular anchoring neochordal repair model for mitral regurgitation in a three-dimensional-printed ex vivo left heart simulator

OBJECTIVES

Posterior ventricular anchoring neochordal (PVAN) repair is a non-resectional technique for correcting mitral regurgitation (MR) due to posterior leaflet prolapse, utilizing a single suture anchored in the myocardium behind the leaflet. This technique has demonstrated clinical efficacy, although a theoretical limitation is stability of the anchoring suture. We hypothesize that the PVAN suture positions the leaflet for coaptation, after which forces are distributed evenly with low repair suture forces.

METHODS

Porcine mitral valves were mounted in a 3-dimensional-printed heart simulator and chordal forces, haemodynamics and echocardiography were collected at baseline, after inducing MR by severing chordae, and after PVAN repair. Repair suture forces were measured with a force-sensing post positioned to mimic in vivo suture placement. Forces required to pull the myocardial suture free were also determined.

RESULTS

Relative primary and secondary chordae forces on both leaflets were elevated during prolapse (P < 0.05). PVAN repair eliminated MR in all valves and normalized chordae forces to baseline levels on anterior primary (0.37 ± 0.23 to 0.22 ± 0.09 N, P < 0.05), posterior primary (0.62 ± 0.37 to 0.14 ± 0.05 N, P = 0.001), anterior secondary (1.48 ± 0.52 to 0.85 ± 0.43 N, P < 0.001) and posterior secondary chordae (1.42 ± 0.69 to 0.59 ± 0.17 N, P = 0.005). Repair suture forces were minimal, even compared to normal primary chordae forces (0.08 ± 0.04 vs 0.19 ± 0.08 N, P = 0.002), and were 90 times smaller than maximum forces tolerated by the myocardium (0.08 ± 0.04 vs 6.9 ± 1.3 N, P < 0.001).

DISCUSSION

PVAN repair eliminates MR by positioning the posterior leaflet for coaptation, distributing forces throughout the valve. Given extremely low measured forces, the strength of the repair suture and the myocardium is not a limitation.

Pediatric Mitral Regurgitation: Standardized Repair-Oriented Strategy With Leaflet Plication

To introduce a standardized strategy and reproducible procedures of mitral repair for mitral regurgitation in the pediatric population with leaflet plication as a principal technique. Consecutive patients who had undergone mitral repair by our standardized repair-oriented strategy in our institution from January 2016 to December 2019 were included retrospectively. The standardized repair strategy included 3-step inspections and repair from the subvalvular to leaflet, and then to the annular level. The main surgical techniques included chordae detachment, papillary muscle splitting, leaflet plication, and posterior annuloplasty. The indication for leaflet plication was that the distance between 2 adjacent chordae tendineae was greater than 4 mm. A total of 113 patients were enrolled. During 22.6-month (range, 2-50 months) follow-up period, primary endpoint was documented in 15 (13.3%) patients, including 1 (0.9%) death, 0 transplantation, and 14 (12.4%) functional mitral failure. Freedom form primary endpoints at 6 months, 1 year, and 3 years was 94.7%, 94.7%, and 82.3%, respectively. Significant independent predictors of functional mitral valve failure were younger age (hazard ratio [HR], 0.28; 95% confidence interval [CI], 0.04-0.72; P = 0.037) and ischemic mitral regurgitation (MR) (HR, 24.34; 95% CI, 4.52-47.33; P < 0.001). Leaflet plication was significantly associated with well-functioned mitral valve (HR, 7.42; 95% CI, 2.35-30.54; P = 0.004). Compared with nonischemic MR group, ischemic MR group was noted with higher occurrence of primary endpoint events (11/28 vs 4/85, P < 0.001). The short- to mid-term outcomes of standardized mitral repair technique with leaflet plication were favorable, among which, however, repair for mitral regurgitation with ischemic lesions is comparatively challenging.

Is there a problem with respect? Risk of neochordal rupture

PURPOSE OF REVIEW

In this review, we summarize the history of mitral valve repair, discuss the broad principles of neochord preparation and implantation, and highlight comparative outcomes between mitral valve repair strategies while focusing on the risk of neochordal rupture.

RECENT FINDINGS

There have been several recent studies comparing outcomes been leaflet-resection and nonresection, neochord-based mitral valve repair. Operative mortality was very low regardless of repair strategy; however, the rate of mitral valve reoperation is lower in those that undergo a neochord-based repair with overall lower mean mitral gradients postrepair. The introduction of minimally invasive approaches to mitral valve repair has preferentially favored an increase in neochord-based repair, given the technical simplicity compared with resection-based approaches. In very rare cases, neochord rupture can occur, likely secondary to a combination of chordal calcification and mechanical stress.

SUMMARY

The method of performing mitral valve repair with neochord implantation has demonstrated superior durability over leaflet resection approaches with equivalent operative outcomes. Although the risk of neochord rupture exists, it is exceedingly rare, and should not be considered a limitation to a neochord-based mitral valve repair. Recurrent mitral regurgitation secondary to neochord rupture is incredibly rare; however, regular echocardiographic evaluation of these patients appears warranted, especially when follow-up extends over 10 years.

A leaflet plication clip is an effective surgical template for mitral valve foldoplasty

OBJECTIVES

During mitral valve repair using the foldoplasty technique, correct judgement of the necessary dimensions and orientation of the leaflet fold is a critical but challenging step that can affect the chances of successful repair. In this study, we investigated whether a leaflet plication clip can be used to guide suture foldoplasty for posterior leaflet prolapse of the mitral valve.

METHODS

Complete posterior leaflet prolapse was created in both in vivo and ex vivo pig hearts by severing the chordae supporting the middle scallop. A plication clip was applied to perform leaflet foldoplasty. Sutures were then placed using the clip as a template and the clip was removed. Leaflet width after flail creation, clip application and suture placement was determined in an ex vivo test. In vivo repair and evaluation was then performed in 7 pigs to determine the repair efficacy under normal physiological loading, at 1 and 6 h after recovery from cardiopulmonary bypass.

RESULTS

Leaflet width after suture placement was comparable to the clip alone (7.0 ± 1.4 vs 9.0 ± 1.6) and both were significantly less than the flail width 15.7± 2.5 mm. In vivo, average coaptation height following repair was restored to 4.7 ± 1.4 mm and 4.2 ± 1.3 mm at 1 and 6 h, respectively, after recovery compared with the baseline height of 5.5 ± 0.9 mm. Mitral regurgitation was reduced from moderate-severe to mild or less, and addition of a De-Vega annuloplasty in the last 3 animals abolished residual leaks to trivial or none.

CONCLUSIONS

Application of the adjustable leaflet plication clip facilitated accurate determination of the correct position, width, height and orientation of the foldoplasty. Any necessary clip repositioning was made prior to the placement of sutures avoiding the need to redo the sutures. This approach could potentially help improve the ease and reproducibility of the foldoplasty repair.

Mitral Valve Repair: The French Correction Versus the American Correction

Degenerative mitral valve disease causing mitral regurgitation is the most common organic valve pathology and is classified based on leaflet motion. The "French correction" mitral valve repair method restores normal valvular anatomy with extensive leaflet resection, chordal manipulation, and rigid annuloplasty. The American correction attempts to restore normal valve function through minimal leaflet resection, flexible annuloplasty, and use of artificial chordae. These differing methods of mitral valve repair reflect an evolution in principles, but both require understanding of the valve pathology and correction of leaflet prolapse and annular dilatation. Adhering to those unifying principles and ensuring that no patient leaves the operating room with significant persistent mitral regurgitation produces durable results and satisfactory patient outcomes.

The 'respect rather than resect' principle in mitral valve repair: the lateral dislocation of the P2 technique

BACKGROUND

Leaflet resection represents the reference standard for surgical treatment of mitral valve (MV) regurgitation. New approaches recently proposed place emphasis on respecting, rather than resecting, the leaflet tissue to avoid the drawbacks of the 'resection' approach.

OBJECTIVES

The lateral dislocation of mid portion of mitral posterior leaflet (P2) technique for MV repair is a nonresectional technique in which the prolapsed P2 segment is sutured to normal P1 segment. Our study evaluates the effectiveness of this technique.

PATIENTS AND METHODS

We performed the procedure on seven patients. Once ring annular sutures were placed, the prolapsed P2 segment was dislocated toward the normal P1 segment with a rotation of 90° and without any resection. If present, residual clefts between P2 and P3 segments were closed. Once the absence of residual mitral regurgitation is confirmed by saline pressure test, ring annuloplasty was completed. The valve was evaluated using transesophageal echocardiography in the operating room and by transthoracic echocardiography before discharge.

RESULTS

At the last follow-up visit, transthoracic echocardiography revealed no mitral regurgitation and normal TRANSVALVULAR gradients.

CONCLUSION

The lateral dislocation of P2 is an easily fine-tuned technique for isolated P2 prolapse, with the advantage of short aortic cross-clamp and cardiopulmonary bypass times. We think it might be very favorable in older and frail patients. Long-term follow-up is necessary to assess the durability of this technique.

Repair of posterior mitral valve prolapse with a novel leaflet plication clip in an animal model

OBJECTIVE

Recently, there has been increased interest in minimally invasive mitral valve prolapse repair techniques; however, these techniques have limitations. A new technique was developed for treating mitral valve prolapse that uses a novel leaflet plication clip to selectively plicate the prolapsed leaflet segment. The clip's efficacy was tested in an animal model.

METHODS

Yorkshire pigs (n = 7) were placed on cardiopulmonary bypass (CPB), and mitral valve prolapse was created by cutting chordae supporting the P2 segment of the posterior leaflet. Animals were weaned off CPB and mitral regurgitation (MR) was assessed echocardiographically. CPB was reinitiated and the plication clip was applied under direct vision to the P2 segment to eliminate the prolapse. The animals survived for 2 hours. Epicardial echocardiography was obtained before and after prolapse creation and 2 hours after clip placement to quantify MR grade and vena contracta area. Posterior leaflet mobility and coaptation height were analyzed before and after clip placement.

RESULTS

There were no cases of clip embolization. Median MR grade increased from trivial (0-1.5) to moderate-severe after MR creation (2.5-4+) (P < .05), and decreased to mild after clip placement (0-3+) (P < .05). Vena contracta area tended to increase after cutting the chordae and decrease after clip placement: 0.08 ± 0.10 cm(2) versus 0.21 ± 0.15 cm(2) versus 0.16 ± 0.16 cm(2) (P = .21). The plication clip did not impair leaflet mobility. Coaptation height was restored to baseline: 0.51 ± 0.07 cm versus 0.44 ± 0.18 cm (P = 1.0).

CONCLUSIONS

The leaflet plication clip can treat mitral valve prolapse in an animal model, restoring coaptation height without affecting leaflet mobility. This approach is a simple technique that may improve the effectiveness of beating-heart and minimally invasive valve surgery.

Chordae replacement versus leaflet resection in minimally invasive mitral valve repair

For many years, the quadrangular resection technique first proposed by Carpentier has become the gold standard for repair of posterior leaflet prolapse of the mitral valve (MV). Although this "resection" technique and its modifications are safe and very effective, they do not respect the anatomy of the MV and the physiological role of the posterior leaflet. Therefore some new techniques, aiming to preserve MV leaflets to a different extent, have been proposed. With the use of expanded polytetrafluoroethylene (ePTFE), neochordae leaflet preserving techniques for posterior MV prolapse treatment have emerged. The aim of these techniques is to support the free edge of the prolapsing segments and thereby restore the physiologic function of the MV. A simplified modification of this technique using premeasured ePTFE loops ("loop technique") was successfully introduced to ease the implantation of neochordae, especially in the setting of minimally invasive MV surgery. While "resection" techniques are associated with excellent long-term results, there is evolving evidence in favor of "non-resection" techniques supporting the concept of a "respect rather than resect" approach.

Nonresectional single-suture leaflet remodeling for degenerative mitral regurgitation facilitates minimally invasive mitral valve repair

BACKGROUND

Both leaflet resection and neochordal construction are effective mitral repair techniques, but they may become incrementally time-consuming when using minimally invasive approaches. We have used a single-suture leaflet-remodeling technique of inverting the prolapsed or flail segment tissue into the left ventricle. This repair is straightforward, expeditious, and facilitates a minimally invasive approach.

METHODS

Ninety-nine patients with degenerative mitral regurgitation (MR) underwent a minimally invasive single-suture repair of the mitral valve from May 2007 through December 2012. Preoperative and perioperative echocardiograms as well as patient outcomes were analyzed and compared with those obtained from patients undergoing minimally invasive mitral valve repair using quadrangular resection at the same institution during the same period.

RESULTS

All 99 patients had a successful mitral repair through a sternal-sparing minimally invasive approach. Ninety-one of the 99 patients had zero MR on postoperative echocardiogram, and 8 of 99 had trace to mild MR. Patients in the nonresectional group had significantly shorter cardiopulmonary bypass and cross-clamp times compared with the quadrangular resection group (115.8 ± 41.7 minutes versus 144.9 ± 38.2 minutes; p < 0.001; 76.2 ± 28.1 minutes versus 112.6 ± 33.5 minutes; p < 0.001, respectively). The mean length of stay was 7.5 ± 3 days. All patients were discharged alive and free from clinical symptoms of MR. There have been no reoperations for recurrent MR on subsequent average follow-up of 1 year.

CONCLUSIONS

An effective, highly efficient, and thus far durable single-suture mitral leaflet-remodeling technique facilitates minimally invasive repair of degenerative MR.

Minimally invasive approach provides at least equivalent results for surgical correction of mitral regurgitation: a propensity-matched comparison

OBJECTIVE

Minimally invasive approaches to mitral valve surgery are increasingly used, but the surgical approach must not compromise the clinical outcome for improved cosmesis. We examined the outcomes of mitral repair performed through right minithoracotomy or median sternotomy.

METHODS

Between January 2002 and October 2011, 1011 isolated mitral valve repairs were performed in the University of Pennsylvania health system (455 sternotomies, 556 right minithoracotomies). To account for key differences in preoperative risk profiles, propensity scores identified 201 well-matched patient pairs with mitral regurgitation of any cause and 153 pairs with myxomatous disease.

RESULTS

In-hospital mortality was similar between propensity-matched groups (0% vs 0% for the degenerative cohort; 0% vs 0.5%, P = .5 for the overall cohort; in minimally invasive and sternotomy groups, respectively). Incidence of stroke, infection, myocardial infarction, exploration for postoperative hemorrhage, renal failure, and atrial fibrillation also were comparable. Transfusion was less frequent in the minimally invasive groups (11.8% vs 20.3%, P = .04 for the degenerative cohort; 14.0% vs 22.9%, P = .03 for the overall cohort), but time to extubation and discharge was similar. A 99% repair rate was achieved in patients with myxomatous disease, and a minimally invasive approach did not significantly increase the likelihood of a failed repair resulting in mitral valve replacement. Patients undergoing minimally invasive mitral repair were more likely to have no residual post-repair mitral regurgitation (97.4% vs 92.1%, P = .04 for the degenerative cohort; 95.5% vs 89.6%, P = .02 for the overall cohort). In the overall matched cohort, early readmission rates were higher in patients undergoing sternotomies (12.6% vs 4.4%, P = .01). Over 9 years of follow-up, there was no significant difference in long-term survival between groups (P = .8).

CONCLUSIONS

In appropriate patients with isolated mitral valve disease of any cause, a right minithoracotomy approach may be used without compromising clinical outcome.

Posterior ventricular anchoring neochordal repair of degenerative mitral regurgitation efficiently remodels and repositions posterior leaflet prolapse

OBJECTIVES

Mitral valve repair techniques for degenerative disease typically entail leaflet resection or neochordal construction, which may require extensive resection, leaflet detachment/reattachment, reliance on diseased native chords or precise neochordal measuring. Occasionally, impaired leaflet mobility, reduced coaptation surface and systolic anterior motion (SAM) may result. We describe a novel technique for addressing posterior leaflet prolapse/flail, which both simplifies repair and addresses these issues.

METHODS

Fifty-four patients (age 62 ± 11 years) with degenerative MR underwent this new repair, 36 of whom minimally-invasively. A CV5 Gore-Tex suture was placed into the posterior left ventricular myocardium underneath the prolapsing segment as an anchor. This suture was then used to imbricate a portion of the prolapsed segment into the ventricle, creating a smooth, broad, non-prolapsed coapting surface on a leaflet with preserved mobility, additional neochordal support and posteriorly positioned enough to preclude SAM.

RESULTS

Repair was successful in all patients. The mean MR grade was reduced from +3.8 to +0.1 with 50 of 54 patients having zero MR and 4 of the 54 having trace or mild MR. All patients had proper antero-posterior location of the coaptation line of a mean length of 10.2 mm, and preserved posterior leaflet mobility. No patients had SAM or mitral stenosis. All patients were discharged and are currently doing well.

CONCLUSION

This new technique facilitated efficient single-suture repair of the prolapsed posterior leaflet mitral regurgitation without the need for resection or sliding annuloplasty. It precluded the need for precise neochordal measurement and preserved the leaflet coaptation surface.

Early outcome of folding mitral valve repair technique without resection for mitral valve prolapse in 60 patients

OBJECTIVES

Leaflet resection represents the reference standard for mitral valve regurgitation. However, the resection technique is irreversible and requires leaflet cutting and reapproximation. Folding mitral valve repair is a nonresectional technique with inversion of the prolapsed segment into the left ventricle. The present study evaluated the effectiveness of this technique.

METHODS

The prolapsed segment was inverted into the left ventricle vertically. A pilot suture was placed at the free edge of the leaflet. After confirming no mitral valve regurgitation with a pressure test, additional sutures were placed toward the annulus. If the test still showed mitral valve regurgitation, the suture was removed and repositioned. Ring annuloplasty was performed in all patients, except those with active infectious endocarditis. The repaired mitral valve was evaluated using echocardiography.

RESULTS

A total of 60 patients (37 men; mean age, 62.4 years) underwent folding mitral valve repair from January 2007 to September 2011. Of these patients, 38 (63%) had moderate and 18 (30%) had severe mitral valve regurgitation preoperatively. Folding mitral valve repair was applied to the anterior leaflet and posterior leaflet. The mean cardiopulmonary bypass time and crossclamp time were 148 and 90 minutes, respectively. No patient had systolic anterior motion. Postoperative echocardiography revealed no mitral valve regurgitation to trivial mitral valve regurgitation in 48 and mild mitral valve regurgitation in 12 patients. No patient required reoperation for recurrent mitral valve regurgitation.

CONCLUSIONS

Folding mitral valve repair is an easily fine-tuned technique with a pilot suture, which can be easily removed and repositioned, if unsatisfactory. This reversibility is a significant advantage of this technique. Long-term follow-up is necessary to assess the durability of this technique.