Assessing The Mitral Valve: in relation to mitral regurgitation

1. Assessing The Mitral Valve:in relation to mitral regurgitation Dr Geoff Richardson

2. Anatomic Concepts and Physiology • Leaflets • Commissures • Zone of coaptation • Mitral annulus • Chordae tendinae • Papillary muscles and the left ventricle

3. Leaflets • Anterior leaflet • Semicircular • Attachment 2/5 annulus • Continuity with LCC and NCC aortic valve: aortic-mitral curtain • Continuous free edge without indentation • Lack of redundancy • Only limited resections possible • Motion defines inflow/ouflow boundaries Surgical orientation Echo orientation

4. Leaflets • Posterior leaflet • Quadrangular shape • Attachment 3/5 annulus • Height < anterior leaflet • Surface area of both leaflets similar Surgical orientation Echo orientation

5. Posterior leaflet • 2 well defined indentations • Divide into 3 scallops: • P1: anterior or lateral • P2: middle • P3: posterior or medial • Corresponding segments on anterior leaflet • Aid in posterior leaflet opening • Imply redundancy • Excess tissue here in prolapse: more aggressive resection possible Surgical orientation Echo orientation

7. Commissures • Where anterior and posterior leaflets come together at insertion into annulus • Sometimes well defined often subtle: • 2 anatomic landmarks: • axis of corresponding papillary muscles and • commissural chordae, which have a specific configuration • Several mm of valvular tissue separates free edge of commissures from annulus • Vulnerable area when dealing with prolapse of a commissure by resection • residual regurgitation nay occur from this region.

8. Zone of Coaptation • On atrial surface 2 zones: • peripheral smooth or body zone • central rough or coaptation zone represents the coaptation surface of the valve • curved coaptation line between leaflets evident from atrium separates the two areas • Coaptation zone critical to valve competency • Depth and length of coaptation an important assessment of mitral valve function

10. Mitral Annulus • Anatomical junction between LV and LA • insertion site for the leaflet tissue • anterior portion of the annulus attached to fibrous trigones • more developed than the posterior annulus • right fibrous trigone - dense junctional area between MV, TV, NCC AV and membranous septum • left fibrous trigone situated at junction of left fibrous border of the AV and the MV 

11. Fibrous skeleton of the aortic and mitral valves

13. Annular Dilatation • Anterior annulus • Believed previously that this portion of the annulus could not increase in circumference however autopsy and 3-dimensional imaging studies have proven that dilatation can occur in pathologic conditions • Annulus less developed at insertion site of posterior leaflet. Fibrous skeleton in this region is discontinuous • posterior annulus prone to increase circumference in setting of MR in association with LA or LV dilatation • correction of the annular dimension essential part of reconstructive degenerative mitral valve surgery

14. Mitral Annulus • Annulus is saddle shaped • During systole the commissural areas move apically while annular contraction also narrows the circumference. Both processes aid in achieving leaflet coaptation • affected by processes such as annular dilatation and calcification • Surrounded by several important anatomic structures which must be respected during mitral valve surgery including: • aortic valve, the coronary sinus, and the circumflex artery.   

15. Chordae Tendinae • responsible for end-systolic position of the anterior and posterior leaflets • classified according to their site of insertion • marginal chordae (primary chordae) inserted on free margin of leaflets, function to prevent prolapse of leaflet margin • intermediate chordae (secondary chordae) insert on ventricular surface of leaflets, relieve valvular tissue of excess tension and important in preserving ventricular shape/ function • basal chordae (tertiary chordae) are limited to the posterior leaflet, connect leaflet base and annulus to papillary muscle • importance of maintaining leafet, annulus and LV connection • avoid adverse ventricular shape and poorer over-all survival

16. Papillary muscles • mitral valve function is integrally related to the ventricle • arise from the area between the apical and middle thirds of LV • antero-lateral often composed of one body or head • postero-medial usually with two bodies or heads • Each papillary muscle provides chordae to both leaflets • blood supply • ALP from LAD and diag or om • PMP: LCX or RCA single system of blood supply, vulnerable in AMI

17. Papillary muscles and the left ventricle • attachment of papillary muscles to lateral wall of LV • LV wall an integral part of MV complex  • Chronic or acute LV dilatation can lead to • pm displacement • increased leaflet tethering due to tension on chordae tendinae • annular dilatation • worsening mitral regurgitation

18. Echocardiographic Analysis • should mimic the surgeon’s approach with examination of the entire mitral valve apparatus • all lesions and dysfunction should be identified • examine leaflets to assess tissue pliability and identify leaflet prolapse or restriction – segmental valve analysis • examine mitral annulus to assess the severity of annular dilatation and the presence or absence of calcification • evaluate chordae tendinae, papillary muscles and the left ventricle walls • assess markers of haemodynamic severity, LV ejection fraction, end-systolic volume, pulmonary pressure, RV function

19. Degenerative Disease: The Pathophysiologic Triad • Carpentier’s pathophysiologic triad • describes the inter-relationship between: • aetiology (the cause of the disease) • lesions (the result of the disease) • leaflet motion dysfunction • this classification is based on opening and closing motions of MV leaflets in relation to the annular plane

20. Carpentier’s functional classification. Type I, normal leaflet motion, annular dilatation Type II, increased leaflet motion (leaflet prolapse); Type IIIa restricted leaflet motion during diastole and systole; Type IIIb restricted leaflet motion predominantly during systole.

21. Type II dysfunction • most common leaflet dysfunction in degenerative valve disease • excess motion of the margin of the leaflet in relation to the annular plane  • lesions are usually chordal elongation or rupture  • Annular dilatation is almost always an associated finding  • most common diseases Barlow’s disease and fibroelastic deficiency • Barlow’s disease: • excess leaflet tissue, large billowing, thickened leaflets, annular size is quite large  • chordae tendinae thickened have a mesh type appearance in their insertion in the body of the leaflets.  • Chordal elongation is the most common cause of prolapse, and multiple leaflet segments are usually involved.   - younger patients (aged <60 years

22. Fibroelastic deficiency • older individuals (usually >60 years of age • shorter history of valve regurgitation • Rupture, often of a single chord, • most common cause of leaflet dysfunction • most cases the only abnormal leaflet tissue is found in the prolapsing segment.  • other leaflet segments often thin and translucent, and of normal height • posterior annulus may be dilated, but the size of the anterior leaflet and valve are most often normal.

23. Type I dysfunction • normal leaflet motion and pure annular dilatation is a less common form of degenerative valve disease.  • associated with conditions that result in significant atrial dilatation • long-standing atrial fibrillation • connective tissue disorders