1. Mitral Stenosis
Meghan York
September 23, 2009

2. Outline: Mitral Stenosis
I. Normal Mitral Valve Anatomy
II. Etiology and Epidemiology
III. Echocardiography Evaluation
IV. Physiologic Disturbances
V. Treatment Options

3. FIGURE 62–27 Continuity of the mitral apparatus and the left ventricular myocardium. Mitral regurgitation (MR) may be caused by any condition that affects the leaflets or the structure and function of the left ventricle. Similarly, a surgical procedure that disrupts the mitral apparatus in an attempt to correct MR has adverse effects on left ventricular geometry, volume, and function. (From Otto CM: Evaluation and management of chronic mitral regurgitation. N Engl J Med 345:740, 2001.)

4. Mitral Valve Anatomy Posterior leaflet encircles majority of annulus
Anterior leaflet is longer across diameter of valve

5. Mitral Valve Orifice Area
Normal 4 – 6 cm2
Mild Stenosis 1.6 – 2.5 cm2
Moderate Stenosis 1.0 – 1.5 cm2
Severe Stenosis < 1.0 cm2

6. Etiology Rheumatic Fever (majority of cases of mitral stenosis)
Calcific Mitral Stenosis
Congenital
Endocarditis with large vegetation causing obstruction

7. Etiology (continued) Anoretic drugs Carcinoid Systemic Lupus
Rhuematoid Arthritis
Mucopolysaccharidoses
Whipple’s Disease
Amyloid deposition

9. FIGURE 62–18 Rheumatic mitral stenosis
FIGURE 62–18 Rheumatic mitral stenosis. There are severe valvular changes, including marked fibrosis and calcification of the mitral valve leaflets and severe chordal thickening and fusion into pillars of fibrous tissue. (From Becker AE, Anderson RH [eds]: Cardiac Pathology: An Integrated Text and Colour Atlas. New York, Raven Press, 1983, p 4.3.)

10. Epidemiology: Rheumatic Mitral Stenosis
Leading cause of congestive heart failure in developing countries
Without surgical intervention, mitral stenosis results in 85% mortality 20 years after onset of symptoms
2/3 of all cases are in women
Age of onset of symptoms usually age 20 – 40
50% of patients with symptomatic MS have history of acute rheumatic fever 20 yrs prior

11. Time from episode of RF to symptoms range from 2 – 30 years, most frequently occuring around 15 – 20 years from illness

12. Echocardiographic Evaluation
A) Valve anatomy, mobility, calcification
B) Assessment of severity:
1)Mitral valve area
- continuity equation method and PISA
- planimetry
- pressure half time method
2)Transmitral pressure gradient (Bernoulli)
3)Sequelae (pulmonary hypertension, left atrial dilation, left atrial thrombus)

13. Valve anatomy, mobility, calcification

14. Rheumatic Mitral Stenosis
Medial and lateral commissural fusion
Thickening of leaflet tips
Hockey stick appearance of leaflets
Doming of leaflets
Chordae
Fibrosis
Shortening
Fusion
Calcification

15. Hockey stick appearance of anterior leaflet

16. Doming of leaflets in diastole

17. Chordal involvement

18. Calcific Mitral Stenosis
Mitral Annular Calcification occurs at annulus adjacent to posterior leaflet
Calcification extends from annulus to base of leaflet
Leaflet tips remain thin and flexible

19. Use of 3D Echocardiography
Can be transthoracic or transesophageal
Improves determination of involvement of chordal structures
Further characterizes fibrosis and calcification of leaflets

20. 3D Echocardiography
FIGURE 14–5C A, 3D pyramidal image of apical four-chamber view. Shaded area, Midportion of the pyramid. B, Cropping the top half of the pyramid shows the four chambers clearly, with much better definition of the spatial relationships of various cardiac structures. C, Still frame of real-time 3D imaging of apical four-chamber view from patient with mitral stenosis. The thickened and restricted motion of the mitral valve (arrows) is well shown. LA = left atrium; LV = left ventricle; RA = right atrium; RV = right ventricle. (From Oh JK, Seward JB, Tajik AJ: The Echo Manual, 3rd edition. Philadelphia, Lippincott Williams & Wilkins, Used with permission of Mayo Foundation for Medical Education and Research.)

21. Fish Mouth Appearance
FIGURE 14–4C A, 3D pyramidal imaging along parasternal short-axis view. Shaded area, Midportion of the pyramid. B, Diagram of the view from the apex after half the pyramid was cropped away. C, 3D echocardiographic image along parasternal short-axis view from patient with mitral stenosis. Note fish-mouth appearance of mitral valve orifice (arrows). (From Oh JK, Seward JB, Tajik AJ: The Echo Manual. 3rd ed. Philadelphia, Lippincott Williams & Wilkins, Used with permission of Mayo Foundation for Medical Education and Research.)

22. M-Mode Increased echogenicity of leaflets
Decreased excursion and reduced separation of anterior and posterior leaflets
Reduced diastolic E-F slope of mitral closure
Paradoxical anterior diastolic motion of posterior mitral leaflet (due to tethering of posterior leaflet to anterior leaflet in rheumatic MS)

23. FIGURE 14–6C A, An M-mode cursor is placed along different levels (1, ventricular; 2, mitral valve; 3, aortic valve level) of the heart, with parasternal long-axis 2D echocardiographic guidance. B, EDd and ESd are end-diastolic and end-systolic dimensions, respectively, of the left ventricle (LV). C, M-mode echocardiogram of the anterior mitral leaflet: A, peak of late opening with atrial systole; C, closure of mitral valve; D, end-systole before mitral valve opening; E, peak of early opening; F, mid-diastolic closure. D, Double-headed arrow, dimension of the left atrium (LA) at end-systole. Ao = aorta; AV = aortic valve; PW = posterior wall; RV = right ventricle; RVOT = right ventricular outflow tract; VS = ventricular septum. (From Oh JK, Seward JB, Tajik AJ: The Echo Manual. 3rd ed. Philadelphia, Lippincott Williams & Wilkins, Used with permission of Mayo Foundation for Medical Education and Research.)

24. Increased EPSS
Normal Severe

25. E Point Septal Separation
FIGURE 14–50A A, M-mode echocardiogram of a patient with mitral stenosis. Note the abnormal motion of the anterior mitral valve leaflet as demonstrated by the E-F slope (arrow). B, 2D echocardiogram of parasternal long-axis view during diastole of a patient with mitral stenosis. The mitral valve leaflets are thickened and have the typical “hockey-stick” appearance (arrow). Left atrium (LA) is enlarged. LV = left ventricle; RV = right ventricle; * = descending thoracic aorta.
Reduced diastolic E – F slope of closure

26. Diastolic Anterior Motion of Posterior Leaflet
Normal Mitral Stenosis

27. Assessment of Severity
Transmitral Pressure Gradient
1)Bernoulli’s equation
Mitral valve area
1) Continuity equation
2) PISA
3) Planimetry
4) Pressure half time

28. Continuity Equation
Cross sectional area of the mitral valve multiplied by velocity time integral of mitral stenosis jet =
Cross sectional area of LVOT(or PA) multiplied by velocity time integral of LVOT (or PA)
Therefore:
CSA(mitral)= stroke volume/VTI(mitral)
Wont work if there is significant MR – if there is MR you need to use the PISA method

29. Proximal Isovelocity Surface area: PISA
Used for calculating continuity equation in setting of mitral regurgitation
Blood flow increases as nears the stenotic orifice
Color doppler flow parameters are adjusted to demonstrate well defined hemispherical aliasing surface are on the atrial side of the mitral orifice
Velocity equals Nyquist limit
CSA(mitral)=2 π r2 x velocityaliasing/velocitypk transmitral

30. FIGURE 14–44 Left, A young woman with dyspnea following mitral valve repair. Transesophageal imaging shows narrowed mitral annulus area with a small soft tissue mass. Continuous wave Doppler recording across the repaired mitral valve shows peak mitral flow velocity (arrow) of 2.5 m/sec (= 250 cm/sec). Right, Color flow imaging with a downward baseline shift (same direction as that of mitral stenosis jet) across a stenotic mitral valve. A nice hemispheric proximal isovelocity surface area (PISA) is seen in the left atrium (LA) because of mitral stenosis. PISA radius is 1 cm. Hence, stenotic mitral valve area (MVA) is calculated as follows:MVA = 6.28 X (1)2 X 4/250 = 1.02 cm2Because the surface of PISA is flat, no angle correction is necessary in this case. LV = left ventricle.

31. Planimetry
2D short axis imaging of mitral valve during diastole allows direct planimetry of valve area
Mitral valve is a planar elliptical orifice that is constant in mid diastole
Planimetry should be done at the narrowest cross sectional area at the leaflet tips
Consider starting at apex and slowly scanning up to find most distal point of leaflets (mitral valve shaped like a funnel during diastole)
Accuracy of measurement has been validated by comparison to post surgical specimens

33. Pressure Half Time
Principle: rate of pressure decline across stenotic orifice is determined by CSA of the orifice
Influence of LA & LV compliance assumed to be negligible
Obtain doppler images of mitral inflow
Pressure half time = time from Vmax to Vmax/√2
Mitral valve area = 220/ pressure half time

34. 220 t½
MVA = 34

35. Transmitral Pressure Gradient
Peak Diastolic Pressure gradient = 4(orifice velocity)2
Mean Diastolic Pressure gradient =
4 (v12 + v22 + v vn2)/ n
Where vx is an instantaneous velocity
Mitral valve area of 1 cm2 typically requires transmitral gradient of
20 mmHg to maintain normal cardiac output at rest.
However, severe mitral stenosis can present with a resting gradient
ranging from 5 – 30 mm Hg.

36. Obstruction of trans-mitral blood flow Increased flow velocity
Increased pressure gradient across valve
Decreased LV filling
Decreased stroke volume
Left atrial dilation
Pulmonary hypertension
Pulmonary Edema
Right sided heart failure

37. Treatment of Mitral Stenosis
Treatment of congestive heart failure
Diuretics
Beta blockers
Treatment and stroke prophylaxis if atrial fibrillation present
Percutaneous transvenous mitral valvuloplasty
Surgical open mitral commisurotomy
Mitral valve replacement

39. Patient Selection for Valvuloplasty
1)Severity of symptoms and physiologic changes
- resting and stress echo
2)Risk of procedural complications
-resting echo

40. Wilkins Score: Assessment of Mitral Valve Morphology
Patient selection for predicted hemodynamic results and risk of procedural complications.
Suitability for BVM is determined by valve morphology and the amount of mitral regurgitation present. The Wilkins score gives a rough guide to the suitability of the mitral valve’s morphology for BMV. This scoring system assigns a point value from 1 to 4 for each of (1) valve calcification, (2) leaflet mobility, (3) leaflet thickening, and (4) disease of the subvalvular apparatus. In general, patients with a score of 9 and less than moderate mitral regurgitation have the best outcomes, although many patients have benefited from BMV despite higher valve scores. 40

41. Selection for Valvuloplasty
Score < 8: probably valvuloplasty unless:
> 2+ mitral regurgitation
previous surgical commissurotomy
Score 9-11: possible valvuloplasty if:
No mitral regurgitation
Age < 45
Score 12-14: surgical commissurotomy
May consider as palliative procedure
Palacios et al. Circulation. 2002

44. Stasis of blood flow and thrombus formation

45. Thank you!

48. FIGURE 62–20 Schematic representation of left ventricular (LV), aortic, and left atrial (LA) pressures, showing normal relationships and alterations with mild and severe mitral stenosis (MS). Corresponding classic auscultatory signs of MS are shown at the bottom. Compared with mild MS, with severe MS the higher left atrial v wave causes earlier pressure crossover and earlier mitral valve (MV) opening, leading to a shorter time interval between aortic valve (AV) closure and the opening snap (OS). The higher left atrial end-diastolic pressure with severe MS also results in later closure of the mitral valve. With severe MS, the diastolic rumble becomes longer and there is accentuation of the pulmonic component (P2) of the second heart sound (S2) in relation to the aortic component (A2).