Mitral valve entrapment: the pitfall of preserved native chordae

The challenge of subvalvular preservation in mitral surgery

Preservation of the subvalvular apparatus during mitral valve replacement (MVR) is a classic strategy to maintain the geometry and systolic function of the left ventricle. However, this approach exposes to a rare but potentially fatal complication: interference of native structures with the mechanical prosthesis. While immediate obstructions are documented, the late occurrence of massive regurgitation due to the rupture of a preserved chordae constitutes an exceptional clinical and diagnostic challenge for the cardiac surgeon and the cardiologist.

This case report describes the observation of a 54-year-old man who underwent surgery three years earlier for rheumatic stenosis with preservation of the posterior subvalvular apparatus. The objective of this presentation is to detail the mechanism of severe and continuous prosthetic regurgitation caused by the rupture of a native chordae at its papillary insertion. The authors explore the hypothesis of a reversible mechanical dysfunction, where the ruptured chordae fragment interposes between the lateral occluder and the suture ring, preventing complete coaptation of the prosthesis leaflets.

The study thus aims to demonstrate the crucial importance of transoesophageal echocardiography (TOE) in identifying these filiform mobile structures. This clinical case illustrates how a precise analysis can guide towards targeted surgical excision rather than a complete valve replacement, transforming a life-threatening prognosis into a total functional resolution.

Clinical protocol and diagnostic evaluation

This study is a clinical case report detailing a late and unusual complication following a double mechanical valve replacement. The subject is a 54-year-old male, followed up three years after initial surgery for severe rheumatic mitral stenosis and concomitant aortic regurgitation. During the primary procedure, the posterior mitral leaflet and the entire subvalvular apparatus had been preserved.

The methodology is based on the following diagnostic and interventional steps:

• Diagnostic imaging: Use of transesophageal echocardiography (TEE) to characterize prosthetic dysfunction. Imaging identified a mobile chord-like structure interfering with the excursion of the lateral occluder.
• Surgical exploration: Direct observation of the valvular mechanics highlighting a rupture of the chordae tendineae at the insertion point of the papillary muscle.
• Interventional procedure: Surgical excision of the ruptured chordae remnant obstructing coaptation.
• Post-operative validation: Immediate evaluation by intraoperative TOE to confirm the restoration of leaflet function and the resolution of regurgitation.

Given the nature of the study (single case), no control group or statistical analysis was applied. The primary endpoint was the disappearance of the continuous mitral regurgitation observed on TEE.

Clinical results and intraoperative observations

The diagnosis of this rare complication was based on an approach combining advanced imaging and direct surgical exploration. The observations are divided into three key phases: ultrasound identification, anatomical confirmation, and functional resolution.

1. Transesophageal Echocardiography (TEE) Evaluations

The initial TEE examination revealed major prosthetic dysfunction. Qualitative observations showed:

• The presence of a mobile heart-shaped structure, located between the lateral obturator and the suture ring of the mechanical prosthesis.
• Direct mechanical interference: this structure hindered the normal excursion of the valve leaflets, preventing their complete closure.
• The characterization of a severe and continuous prosthetic mitral regurgitation.

2. Surgical findings and anatomical analysis

The surgical intervention confirmed the etiology suspected on imaging. The surgeons identified a rupture of a chordae tendineae at its attachment point on the papillary muscle. This remnant of the native subvalvular apparatus (preserved during the initial surgery three years earlier) had become lodged in the prosthetic mechanism, creating a physical obstacle to coaptation.

3. Post-interventional outcome

The table below summarizes the evolution of clinical parameters between presentation and the post-excision phase:

Surgical excision of the obstructive tissue allowed for immediate restoration of prosthetic function. Resolution of regurgitation was confirmed in real-time by intraoperative transoesophageal echocardiography, validating the procedure's effectiveness without the need for complete valve replacement.

Clinical and mechanical analysis

This case illustrates a rare but life-threatening complication: the late rupture of a preserved chordae tendineae interfering with a mechanical prosthesis. Clinically, the results demonstrate that severe prosthetic regurgitation can appear in a delayed manner (three years post-operatively here), caused by the loss of tension and the rupture of the native subvalvular apparatus at the papillary muscle level. The originality of this observation lies in the presentation of continuous regurgitation and its total reversibility after surgical excision of the obstructive remnant.

Limitations and perspective

As this is a single case report, these observations do not allow for the establishment of a statistical incidence of this complication. However, the authors emphasize that, although the literature generally favors the preservation of subvalvular material to maintain ventricular function, this technique introduces a residual mechanical risk. Unlike more frequent acute postoperative obstructions, this case demonstrates that chordal entrapment can occur in the long term, mimicking other more common prosthetic dysfunctions such as thrombosis or pannus.

Implications for practice

The use of transoesophageal echocardiography (TOE) was decisive in identifying the mobile chordal structure blocking the excursion of the lateral occluder. The excision of the offending tissue immediately restored valvular function, confirming that valve replacement is not systematically necessary if the obstruction is purely extrinsic and related to native tissues.

Study results

Ce cas clinique rapporte une régurgitation prothétique mitrale sévère chez un patient de 54 ans, survenue trois ans après un remplacement valvulaire avec conservation de l'appareil sous-valvulaire. L'exploration a révélé qu'une corde tendineuse, rompue au niveau du muscle papillaire, créait un obstacle mécanique empêchant la coaptation complète de l'ailette prothétique.

In concrete terms, for the practitioner:

• Expand the differential diagnosis: In the event of a late prosthetic leak following subvalvular preservation, consider mechanical interference by native tissue or chordal rupture once classic causes have been excluded.
• Prioritize TEE: Transesophageal echocardiography is the essential tool for identifying these filiform mobile structures, often invisible in transthoracic imaging, interfering with the kinetics of the occluders.
• Surgical precision: While the preservation of the subvalvular apparatus supports ventricular function, this case highlights the need for rigorous evaluation of the tension and viability of the maintained chordae to prevent vital mechanical complications.

Technical lexicon of the study

Subvalvular apparatus: Anatomical complex comprising the chordae tendineae and papillary muscles of the mitral valve. Although its preservation during mitral valve replacement (MVR) can optimize ventricular function, this case demonstrates a rare risk of late mechanical interference.

Chordae tendineae: Fibrous structures connecting the papillary muscles to the valve leaflets. The study reports a rupture of a preserved native chordae at its papillary attachment, leading to prosthetic dysfunction.

Transoesophageal echocardiography (TOE): Reference diagnostic imaging tool in this case, which allowed the visualisation of a mobile filiform structure interfering with the occluder and the exclusion of more frequent etiologies of regurgitation.

Occluder: Mobile component (disk or leaflet) of a mechanical heart valve. The study describes a lateral occluder blockage by a chordal remnant, preventing complete closure of the prosthesis.

Leaflet excursion: Range of motion of the valve's moving elements during opening and closing. Limited or hindered excursion by native tissue is the direct cause of severe mitral regurgitation here.

Coaptation: Mechanism of hermetic closure by contact of the valve surfaces. The interposition of a ruptured chordae fragment prevented normal coaptation of the prosthetic components, creating a massive leak.

Sewing ring: Peripheral part of the valvular prosthesis fixed to the patient's cardiac tissue. Interference occurred specifically between this ring and the mobile occluder.

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