Mitral valve repair: pre-measured loops vs. visual estimation benefits

Mitral valve repairs: the challenge of sizing neo-chordae

In the management of degenerative mitral regurgitation (DMR), mitral valve repair (MVr) surpasses replacement in preserving left ventricular function. However, treating anterior valve prolapse remains complex. While the use of ePTFE artificial chordae is standardized, the intraoperative determination of their exact length remains the weak link: conventional methods (pull tests, saline tests) are subjective and dependent on the surgeon's experience. Imprecision here exposes the patient to early residual regurgitation and compromises the durability of the repair.

This retrospective observational study, conducted at the Anthea Hospital center, evaluates a standardization solution: the "track technique". This method uses a temporary annular guide to define a constant reference plane, eliminating uncertain manual measurements. The objective is to compare the 5-year clinical and echocardiographic outcomes of this technique (n=25) versus conventional visual estimation (n=22) in patients with isolated anterior prolapse.

The authors test the hypothesis that neo-chordal anchoring indexed to a fixed anatomical landmark ensures more uniform coaptation and better long-term hemodynamic stability than empirical methods. For the surgeon, the challenge is to validate a reproducible tool, particularly adapted to the requirements of minimally invasive surgery where limited exposure makes visual calibration more perilous.

Methodology

This retrospective observational study was conducted at Anthea Hospital – GVM Care & Research, following the STROBE guidelines. The objective was to compare, over a 5-year follow-up, the clinical and echocardiographic outcomes of two artificial chordae sizing techniques for mitral valve repair.

• Population: 47 patients presenting with isolated prolapse or chordal rupture of the anterior leaflet, with symptomatic mitral regurgitation (MR) ≥ 2+, operated on between January 2020 and January 2022.
• Track Group (n=25): After annuloplasty, a temporary annular guide is inserted to establish a fixed reference plane, allowing the ePTFE neo-chordae to be tied at a constant height corresponding to the level of the ring.
• Conventional Group (n=22): Chordal length is determined by visual estimation, alignment with adjacent segments, and saline pressure tests under direct vision.

The procedures were performed predominantly via right mini-thoracotomy (77-80%) or sternotomy. The protocol included systematic annual follow-up for up to 5 years. Evaluation was based on transthoracic (TTE) and transesophageal (TEE) echocardiography, with measurement of coaptation length and MR grading (from 0 to 4+). All images were analyzed by two independent echocardiographers blinded to the surgical technique employed.

Results: Cohort homogeneity and baseline data

Analysis of preoperative characteristics confirms rigorous homogeneity between the group benefiting from the "Track Technique" (n=25) and the group treated by conventional visual estimation (n=22). No statistically significant difference was observed between the two study arms, validating the comparability of the cohorts for long-term follow-up.

All included patients presented with isolated prolapse or flail of the anterior leaflet (A1–A3), with a predominance of severe mitral regurgitation (92% in the Track group vs 95% in the conventional group, p=0.75). The surgical approach was mostly performed via right mini-thoracotomy (80% vs 77%, p=0.81), demonstrating the feasibility of the technique in minimally invasive surgery contexts.

Although the study covers a follow-up extending up to 5 years, the authors report that preliminary data (from their previous work) already highlighted the superiority of the "Track Technique" compared to conventional methods on two key points:

• Uniformity of coaptation: Obtaining more regular coaptation lengths thanks to the temporary ring guide.
• Reduction of residual MR: Decrease in early residual mitral regurgitation rates compared to manual and visual adjustment.

The study confirms that standardizing the length of neo-chordae via the guiding device eliminates the subjectivity associated with pull tests or ventricular pressurization (water test), while maintaining stable hemodynamic parameters (mean LVEF of 58% vs 57%, p=0.65).

Analysis of results and surgical reproducibility

Standardizing the length of neo-chordae in mitral valve repair (MVr) remains a major technical challenge, particularly for the anterior leaflet. The data from this study highlight that the "track technique" offers superior geometric precision compared to conventional visual estimation. By using a temporary annular guide as a fixed reference point, the surgeon eliminates the subjectivity inherent in traction tests or ventricular saline pressurization. This approach appears to guarantee a target coaptation zone of ≥ 8 mm more consistently.

Compared to existing techniques such as the Chord-X system or Leipzig loops, the "track technique" stands out for its simplicity of integration after annuloplasty. It directly addresses the need for reproducibility in high-volume centers. The study shows that this method reduces the incidence of early residual mitral regurgitation (MR), a determining factor for the 5-year durability of the repair.

Clinical limits and implications

The study, however, presents notable limitations: its retrospective monocentric nature and a restricted sample size (n=47). Since the choice of technique was left to the surgeon's discretion, selection bias cannot be excluded. Furthermore, although the authors claim its applicability to the posterior leaflet, this cohort was limited to isolated anterior prolapses.

For the practitioner, the interest is particularly marked in the context of minimally invasive surgery (robotic or video-assisted). In these configurations where exposure is limited, having a standardized measurement tool rather than relying on a sometimes complex three-dimensional visual assessment secures the surgical procedure and optimizes long-term hemodynamic results.

In concrete terms, for the practitioner:

• Secure your complex repairs: The technical track provides a fixed reference point at the annular plane level, eliminating the uncertainty of visual estimation when correcting anterior leaflet prolapse (A1-A3).
• Optimize coaptation: By using the guide after placing the ring, you systematically aim for a coaptation zone ≥ 8 mm, a key factor for long-term durability.
• Facilitate minimally invasive procedures: This approach is particularly suited to video-assisted or robotic surgery, where depth perception and ventricular pressure tests are technically more demanding.

Technical lexicon of the study

Track Technique: A standardized approach for neo-chordae calibration using a temporary annular guide. This device, inserted after annuloplasty, establishes a fixed reference plane for suture anchoring, thereby eliminating the need for subjective caliper measurements or empirical ventricular pressurization.

Saline test: Traditional method for assessing valvular competence by injecting saline solution into the left ventricle. The study highlights that this test is inherently subjective and operator-dependent, as it does not allow for real-time measurement under actual physiological loading conditions.

ePTFE neo-chordae: Artificial chords made of expanded polytetrafluoroethylene used to replace failing native chordae. They represent a durable alternative to tissue resection, although their long-term effectiveness strictly depends on the precision of their length determined intraoperatively.

Coaptation length: Interface zone between the mitral leaflets measured in systole (A2-P2 interface). In this protocol, the clinical objective is to achieve a contact zone greater than or equal to 8 mm to ensure repair durability and minimize residual mitral regurgitation.

Segments A1–A3: Anatomical divisions of the anterior mitral leaflet. Prolapse or flail of these segments presents unique surgical challenges compared to the posterior leaflet, due to the intrinsic mobility and significant length of the anterior tissue to be stabilized.

Complete ring annuloplasty: Mitral ring remodeling procedure systematically performed before using the Track Technique. The ring serves as a stabilization base for the measurement guide, ensuring a uniform coaptation height across the entire closure line.

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