Mitral valve anatomy.pptx

Simplified Anatomy of Mitral Valve

1. Mitral Valve Anatomy

2. Mitral Valve Function Regulates blood flow in 2 ways: Forward towards left ventricle (LV) in diastole Prevents backflow towards left atrium (LA) in systole Helps regulate size, geometry and function of the LV

3. Mitral Valve  Components   1. Mitral Annulus 2. Mitral Leaflets 3. Commissures 4. Chordae Tendinae 5. Papillary Muscles

4. 1.  Mitral Annulus Anatomical structure that separates the LV & LA

5. 2.  Mitral  Leaflets Mitral Leaflets & Scallops :  Thin and pliable leaflets that contain scallops which represent segmental markers . Leaflets thin & pliable Scallops serve as segmental markers of leaflets 2 Leaflets with 3 Scallops Anterior Leaflet (AML): larger & thicker Dome-shaped Scallops: A1 (lateral), A2 (central), A3 (medial) Posterior Leaflet (PML): thinner & more flexible Crescent shaped Scallops: P1 (lateral), P2 (central), P3 (medial )

6. 2.  Mitral  Leaflets

7. 3.   Commissures Commissures : 2 specific sites where the leaflets insert and join into mitral annulus Anterolateral Commissure Posteromedial Commissure

8. 4.  Chordae Tendinae Chordae Tendinae :  Fibrous strings that attach specific portions of mitral leaflets to papillary muscle tips Normal average length is around 20mm Normal average thickness is 1-2mm Key items to look for: thickening, fusion, calcification, elongation, rupture

9. 4.  Chordae Tendinae Three classified types of chordae tendinae based on location of insertion : Primary (marginal)- attaches at leaflet tips (‘ coaptation line’) Function to maintain coaptation of leaflets Failure of primary leads to rupture or elongated chordae Cause development of prolapse or flail leaflet Secondary (basal)- attaches at mid-body of leaflets Provides support length to leaflets Thicker & longer Can rupture &  not damage coaptation or develop regurgitation Tertiary – attaches at base of leaflets Function as structural support

10. 5.  Papillary Muscles Papillary Muscles :  Large trabeculae muscles that branch from 1/3rd of LV, connecting chordae to mitral leaflets 2 papillary muscles: Anterolateral (APM): Dual blood supply (LAD & Cx ) Posteromedial (PPM): Single blood supply (Either RCA or LCX) Prone to injury from MI due to single blood supply

11. Mitral Valve Zones If we zoom in on the mitral leaflets from the atrial surface , we can identify two zones. Body (‘Smooth’) Zone: surface area on leaflet body Coaptation (‘Rough’) Zone: represents the coaptation area of leaflets Crucial area to observe in assessment of mitral valve function

12. Mitral valve apparatus components in normal and diseased states

13. Mitral valve prolapse : The schematic shows bileaflet mitral valve prolapse, with superior displacement of the papillary muscle tip, “tugged” by the leaflets, and excessive leaflet and chordal tissue and mobility. Leaflet coaptation is displaced into the left atrium superior to the annular plane (dashed line).

14. Functional/ischemic mitral regurgitation: The papillary muscle (medial in inferior myocardial infarction) is displaced posteriorly, laterally and, to the extent allowed by the chords, apically (arrow) due to left ventricular local dilatation & remodeling (arrows) caused by MI (shaded area). The LV wall-PM displacement tethers the mitral leaflets apically and limits coaptation . There is 20 often not enough leaflet tissue to compensate for leaflet tenting (area apical to the dashed line), resulting in mitral regurgitation (red lines).

15. Hypertrophic cardiomyopathy: The geometry of the left ventricle and papillary muscles is altered by myocardial hypertrophy ( interventricular septum, double arrow). The papillary muscles are enlarged and displaced anteriorly (arrow) and closer to each other (not shown). This decreases intercommissural leaflet tension and moves the coaptation point and distal leaflets toward the left ventricular outflow tract. Like a sail catching a breeze, the distal anterior leaflet and/or posterior leaflet if elongated, is at risk of being displaced into the LV outflow tract by blood-flow drag. If anterior leaflet displacement is severe enough and posterior leaflet apposition restricted, mitral regurgitation will occur (red lines).

16. Key Tips Evaluation of the Mitral Valve includes all components that make up the Mitral Apparatus Visualization of scallops can vary per scanning window  and angulation of specific window Understanding the  structure and  function of all components can aid in diagnosing pathology Anterior leaflet is more fixed than the posterior, causing the posterior leaflet to be more prone to remodeling, distortion of shape or damage

17. Key Tips Anterior leaflet is not anatomically divided into scallops like the posterior leaflet is, but for pathological guidance, the anterior scallops mimic the posterior leaflets Scallops are labeled 1 to 3 based from lateral to medial segments In regards to which papillary muscle supplies chordae to which scallops… - Anterolateral papillary muscle = lateral scallops (A1, P1) & lateral half of A2, P2 - Posteromedial papillary muscle = medial scallops (A3, P3 ) &  medial half of A2, P2 Chordae play a key role in the structure and function of mitral leafets

18. THANK YOU