Mitral valve prolapse: an atypical variation of the anatomy.
Bibliographic record
Abstract
BACKGROUND: The mitral valve apparatus is a complex structure composed of an annulus, mitral leaflets, chordae tendinae, papillary muscles and left ventricular, atrial and aortic walls. Deficiency or degeneration of one or more of these structures may result in dysfunction of the valvular apparatus leading to mitral valve prolapse during systole. OBJECTIVE: To review the chordal attachment of surgically resected mitral valve tissue from cases of mitral valve incompetence. METHODS: The clinical and morphological features of 135 surgically resected posterior mitral valve leaflet specimens were reviewed for mitral valve prolapse from January 1999 to June 1999. Four mitral leaflets removed either surgically or at autopsy served as controls. RESULTS: Excised posterior mitral leaflets from two patients had segments containing free margin and rough zone chordae that lacked attachment to larger 'strut' or 'stem' chordae or to either papillary muscle. These chordae were observed in otherwise normal mitral valves with adjacent areas that had normal chordal arrangements. Such chordae of the posterior leaflet were termed 'atypical chordae tendinae'. There was no good gross or histological evidence of chordal rupture, and this atypical arrangement appears to be congenital in origin. Grossly and histologically, these atypical variants otherwise exhibited characteristics similar to those of leaflet tissue from typical cases of mitral valve prolapse, with shiny, grey-white and "edematous" tissue that contained increased mucopolysaccharides in the zona spongiosa and chordae tendinae. CONCLUSIONS: This review found atypical attachment of mitral valve chordae tendinae such that isolated segments of the posterior leaflet congenitally lack chordal support, likely leading to mitral valve prolapse. Review of the literature suggests that this is a heretofore unreported cause of mitral valve incompetence.
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How this classification was reachedexpand
Full frame machine prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. The Gemma side is a direct model label for every work in the frame, read from the title-only record. The Codex side is a classifier learned from the 10,348 direct Codex labels and calibrated to design-weighted sample rates; fields without enough sample support carry no Codex call. Candidate is the union of the two sides; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels.
Distilled classifier scores by category (both heads)
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.000 | 0.001 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.001 | 0.001 |
| Science and technology studies | 0.000 | 0.001 |
| Scholarly communication | 0.001 | 0.000 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.001 | 0.000 |
Machine scores (provisional)
The two teacher heads of the student model, read on this work. A score orders the frame for review; it never asserts a category, and the validation status ships verbatim with every row.
Baseline scores from an immature model (maturity gate not passed, 7 training rounds). Scores rank; they never assert a category.
score_only:v0-immature-baseline · verbatim from the scoring run: score_only means the number may rank works, and no category label ships from itClassification
machine, unvalidatedMachine predicted; a candidate call from one source (direct Gemma or distilled Codex), not a consensus.
How this classification was reached, model by model and score by score, is at the end of the page under "How this classification was reached".