The use of artificial chordae in mitral valve repair

Mitral valve repair with the semi-rigid Memo 4D annuloplasty ring: early clinical and echocardiographic outcomes from the MANTRA study

OBJECTIVES

Memo 4D is a semi-rigid ring with an exclusive saddle shape and progressive increased anteroposterior diameter. This preliminary analysis reports 30-day clinical and haemodynamic outcomes of the MANTRA Memo 4D sub-study.

METHODS

MANTRA is an 'umbrella' prospective, multicentre, worldwide post-market study to collect real-life safety and performance data on the Corcym devices. Clinical and echocardiographic outcomes were gathered preoperatively, at discharge and each follow-up. KCCQ-12 questionnaires were collected preoperatively and at 30 days. Echocardiographic studies were performed per a predefined protocol and assessed by an independent core laboratory.

RESULTS

In total, 166 patients (52, 31.3% female, mean age 60.7 ± 11.4 years) underwent mitral valve repair with Memo 4D in 17 international institutions between July 2021 and June 2023 (enrolment is still ongoing). Primary was the most common aetiology (157, 94.6%), of which 33 cases of Barlow's disease (19.9%); secondary mitral regurgitation was present in six cases (3.6%). Thirty-day mortality was 0.6% (1). One stroke event (0.6%), one acute kidney failure (0.6%), one myocardial infarction (0.6%) and two reoperations within 30 days were reported. Surgery marked improvement in the patient's NYHA class associated with a significant increase in KCCQ-12 summary score, from 69.1 (SD = 23.7) preoperatively to 83.9 (SD = 15.7) at 30 days. End-diastolic left ventricular diameters decreased from 55.19 (SD = 7.10) preoperatively to 52.70 (SD = 3.76) mm at 30 days, and left atrial volume decreased from 125.79 (SD = 46.33) preoperatively to 91.51 (SD = 37.20) ml at 30 days. Mitral regurgitation significantly reduced after the operation and up to 30-day follow-up.

CONCLUSIONS

Mitral valve repair with Memo 4D is associated with good clinical and haemodynamic outcomes in the early period.MANTRA ClinicalTrials.gov number NCT05002543.

Innovative Mitral Valve Repair Using a Novel Automated Suturing System: Preliminary Data

(1) Background and Objectives: Mitral regurgitation is a common valve disease requiring surgical repair. Even with satisfactory results, repair techniques may underlie subjectivity and variability and require long learning curves. A novel approach, the "Roman Arch" technique, may ease the technical burden. This study assessed an automated suturing device's feasibility and time efficiency for a proposed simplified technique. (2) Materials and Methods: Using the MiStitch™ and MiKnot™ devices (LSI Solutions, Inc., Victor, NY, USA), the suture pattern was performed in a cadaver model. Three surgeons with different expertise levels conducted the procedures. Repair and suture placement times were recorded and analyzed. (3) Results: The modified "Roman Arch" repair was completed on all ten human heart specimens with an average total repair time of 3:01 ± 00:59 min and a trend toward reduced times as experience increased. The study confirmed the technical feasibility with 90% of the attempts rated as rather satisfactory or very satisfactory. (4) Conclusions: The MiStitch™ system effectively facilitated the modified "Roman Arch" repair in an ex vivo setting, suggesting its potential to reduce the technical complexity of mitral valve repairs. Further studies are needed to confirm its efficacy and safety in clinical practice.

Anatomical Mitral Valve Repair: Mathematical Prediction of Artificial Chordae Length in Para-Commissural Regions

To develop a mathematical formula for calculating the length of ruptured mitral valve chordae (with a view to surgically replacing them with artificial chordae) when rupture occurs at scallop A1, A3, P1, or P3. We studied human cadaver hearts collected by the Faculty of Medicine at Amiens Picardy University Hospital. The donors' mean age standard deviation age at death was 79 ± 10. After weighing and dissection, we counted the number of para-commissural chordae per scallop and measured their length with a digital calliper. A total of 31 human cadaver hearts (14 from females and 17 from males) were analyzed. The mean lengths of scallops A1, A2, A3, P1, P2, and P3 were 17.45, 19.42, 17.58, 13.32, 14.52, and 13.26 mm, respectively. A linear regression gave the following mathematical equations: A1 = 0.96 × A2- - 1.3 (R: 0.99; P < 0.001); A3 = 0.9 × A2 + 0.17 (R: 0.95; P < 0.01); P1 = 0.87 × P2 +0.74 (R: 0.89; P < 0.001), and P3 = 0.91 × P2 - 0.01 (R: 0.87; P < 0.0001). When the patient's anatomy prevents manual measurements of the chordae during mitral valve repair surgery, the mathematical formulae derived here can be used to predict the length of the chordae on A1, A3, P1, and P3 from the length of the chordae on A2 and P2. The mitral chordae can therefore be replaced with prostheses with a great degree of precision.

A Computational Pipeline for Patient-Specific Prediction of the Postoperative Mitral Valve Functional State

While mitral valve (MV) repair remains the preferred clinical option for mitral regurgitation (MR) treatment, long-term outcomes remain suboptimal and difficult to predict. Furthermore, pre-operative optimization is complicated by the heterogeneity of MR presentations and the multiplicity of potential repair configurations. In the present work, we established a patient-specific MV computational pipeline based strictly on standard-of-care pre-operative imaging data to quantitatively predict the post-repair MV functional state. First, we established human mitral valve chordae tendinae (MVCT) geometric characteristics obtained from five CT-imaged excised human hearts. From these data, we developed a finite-element model of the full patient-specific MV apparatus that included MVCT papillary muscle origins obtained from both the in vitro study and the pre-operative three-dimensional echocardiography images. To functionally tune the patient-specific MV mechanical behavior, we simulated pre-operative MV closure and iteratively updated the leaflet and MVCT prestrains to minimize the mismatch between the simulated and target end-systolic geometries. Using the resultant fully calibrated MV model, we simulated undersized ring annuloplasty (URA) by defining the annular geometry directly from the ring geometry. In three human cases, the postoperative geometries were predicted to 1 mm of the target, and the MV leaflet strain fields demonstrated close agreement with noninvasive strain estimation technique targets. Interestingly, our model predicted increased posterior leaflet tethering after URA in two recurrent patients, which is the likely driver of long-term MV repair failure. In summary, the present pipeline was able to predict postoperative outcomes from pre-operative clinical data alone. This approach can thus lay the foundation for optimal tailored surgical planning for more durable repair, as well as development of mitral valve digital twins.

Minimally invasive mitral valve repair or replacement for degenerative mitral regurgitation

OBJECTIVES

This study describes our experience with minimally invasive mitral valve (MV) repair and chordal-sparing replacement in patients with degenerative MV regurgitation.

METHODS

Between February 2009 and October 2015, a total of 960 patients underwent isolated minimally invasive MV repair, whereas 95 patients underwent chordal-sparing MV replacement. We performed a propensity score-matched analysis in 85 pairs to compare overall survival and major adverse cardiac and cerebrovascular event (MACCE) -free survival over an 8-year follow-up period. For sensitivity analyses, in the entire study cohort, we used the multivariable-adjusted Cox regression analysis to assess the overall mortality and MACCE.

RESULTS

In the propensity score-matched pairs, the 7-year probability of survival was 76.3% in the repair group and 78.8% in the replacement group (P = 0.60). Similarly, freedom from MACCE at year 7 of follow-up did not differ between the repair and replacement groups (78.6% and 72.3%, respectively; P = 0.48). The corresponding values for 7-year freedom from valve reintervention were 95.6% and 98.8%, respectively (P = 0.31). In the entire study cohort, the multivariable-adjusted hazard ratio (HR) of mortality for the replacement versus the repair group was 1.31 [95% confidence interval (CI) 0.68-2.50; P = 0.42], and the multivariable-adjusted HR of MACCE was 1.03 (95% CI 0.61-1.74; P = 0.91).

CONCLUSIONS

Our findings suggest that mid-term clinical outcomes do not significantly differ between patients undergoing MV repair or chordal-sparing MV replacement.

New insights into mitral heart valve prolapse after chordae rupture through fluid-structure interaction computational modeling

Mitral valve (MV) dynamics depends on a force balance across the mitral leaflets, the chordae tendineae, the mitral annulus, the papillary muscles and the adjacent ventricular wall. Chordae rupture disrupts the link between the MV and the left ventricle (LV), causing mitral regurgitation (MR), the most common valvular disease. In this study, a fluid-structure interaction (FSI) modeling framework is implemented to investigate the impact of chordae rupture on the left heart (LH) dynamics and severity of MR. A control and seven chordae rupture LH models were developed to simulate a pathological process in which minimal chordae rupture precedes more extensive chordae rupture. Different non-eccentric and eccentric regurgitant jets were identified during systole. Cardiac efficiency was evaluated by the ratio of external stroke work. MV structural results showed that basal/strut chordae were the major load-bearing chordae. An increased number of ruptured chordae resulted in reduced basal/strut tension, but increased marginal/intermediate load. Chordae rupture in a specific scallop did not necessarily involve an increase in the stress of the entire prolapsed leaflet. This work represents a further step towards patient-specific modeling of pathological LH dynamics, and has the potential to improve our understanding of the biomechanical mechanisms and treatment of primary MR.

Future Technology

Mitral regurgitation is the most common valvular disease and significant (moderate/severe) mitral regurgitation is found in 2.3% of the population older than 65 years. New transcatheter minimally invasive technologies are being developed to address mitral valve disease in patients deemed too high a risk for conventional open-heart surgery. There are several features of the mitral valve (saddle-shaped noncalcified annulus with irregular leaflet geometry) that make a transcatheter approach to repair or replacing the valve more challenging compared with the aortic valve. Several devices are under investigation for transcatheter mitral valve replacement, and also for mitral valve repair targeting the mitral valve leaflets, chordae tendinae, and mitral annulus. The MitraClip device is the only Food and Drug Administration-approved device to treat mitral regurgitation by targeting the mitral leaflets. There are eight minimally invasive devices being studied in humans that target the mitral annulus, and at least two devices being studied in animal models. There are 5 devices in clinical trials for minimally invasive approaches targeting the chordae tendinae. More than 10 different transcatheter mitral valves are in various stages of development and clinical trials. These transcatheter mitral valves can be delivered either through a transseptal, transapical, transaortic, or left atriotomy approach. It seems likely that transcatheter treatment approaches to mitral valve disease will become more common, at least in the sick and elderly patient population.