In this issue of the Journal, Kehl et al. describe the benign outcome of flail mitral leaflet with moderate mitral regurgitation (MR). They conducted a retrospective study of their echocardiographic database and identified 706 cases of possible flail mitral valve. Of the 143 patients with 3+ or less MR, 14 patients were noted to have definite echocardiographic evidence of flail mitral valve with ≤2+ eccentric MR. Over a median follow-up of 361 days, MR progressed in severity in only one case, which was associated with endocarditis and resulted in death. The authors argue that a flail mitral valve does not always result in a bad outcome and can coexist with milder degrees of MR. In this editorial comment, we discuss the complex chordal architecture that may allow deeper insights into chordal strength, stress, biochemistry, and potential effect of physical and chemical environments with potential impact on propensity to disruption.
Anatomy of Chordae Tendineae
Understanding the anatomy of the chordae is essential to understanding the pathology and pathophysiology of a flail valve. Chordae tendineae are filamentous structures that anchor the mitral valve leaflets to the underlying papillary muscle or ventricular wall. There are different types of chordae tendineae, as illustrated in Table 1 . Another simplified classification was proposed by Tandler and Quain, as shown in Figure 1 . These will be detailed below. There are also differences between the chordae of the two mitral leaflets.
| Type | Rough zone | Cleft chordae | Basal | Commissural |
|---|---|---|---|---|
| Anterior |
| None | None | None |
| Posterior |
| Insert into the clefts of the posterior leaflet. | Arise from posterior ventricular wall and insert into basal portions of posterior leaflet. | None |
| Commissural | Two in number, one to anteromedial and the other to posterolateral commissure. |
Anterior Leaflet Chordae
The chordae of the anterior leaflet attach exclusively to the rough, thick, distal part of the leaflet. The rough zone is described as crescent shaped and broader at the apex of the leaflet, which narrows toward the commissure. The rough zone extends to about 0.8-1 cm from the free margin to the line of closure. Rough zone chordae insert into this zone. They usually split into three components soon after originating from the papillary muscle; one inserts into the free margin of the leaflet, one at the line of closure, and the last one between the two chords. Sometimes these can branch into secondary chords, which then insert into the same area as the parent chordae. Among the chordae that insert into the rough zone of the anterior leaflet are the two thickest and largest chordae, called strut chordae. They arise from the tips of the papillary muscle, usually between the 4 and 5 o’clock position on the posteromedial papillary muscle and 7 and 8 o’clock position on the anterolateral papillary muscle.
Anterior Leaflet Chordae
The chordae of the anterior leaflet attach exclusively to the rough, thick, distal part of the leaflet. The rough zone is described as crescent shaped and broader at the apex of the leaflet, which narrows toward the commissure. The rough zone extends to about 0.8-1 cm from the free margin to the line of closure. Rough zone chordae insert into this zone. They usually split into three components soon after originating from the papillary muscle; one inserts into the free margin of the leaflet, one at the line of closure, and the last one between the two chords. Sometimes these can branch into secondary chords, which then insert into the same area as the parent chordae. Among the chordae that insert into the rough zone of the anterior leaflet are the two thickest and largest chordae, called strut chordae. They arise from the tips of the papillary muscle, usually between the 4 and 5 o’clock position on the posteromedial papillary muscle and 7 and 8 o’clock position on the anterolateral papillary muscle.
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