Mitral regurgitation

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Mitral regurgitation (Mitral insufficiency) is the leaking of blood into the left atrium from left ventricle across the mitral valve.

Source(s): Mitral regurgitation

Contents

Aetiology and morphological features in 2-D Echocardiography

Rheumatic Mitral regurgitation

In rheumatic mitral regurgitation, there is some degree of commissural fusion and thickening of the tips visible in 2D echo. The movement of the valve leaflets is restricted.

Source(s): Mitral regurgitation

Myxomatous mitral valve

The leaflets and chordae are thick and reduntant. Reduced tensile strength leads to progressive elongation or rupture of chordae. Ruptured chordae appear as flail segments. To diagnose mitral valve prolapse, the following criteria should be fulfilled during echocardiography - Movement of any part of either leaflet more than 2mm behind the annular plane in parasternal long axis view and movement of point of co-aptation behind the annular plane in apical 4 chamber view in 2D echo.

Source(s): Mitral regurgitation

Annular calcification

Mitral annulus is usually smaller in systole. The increased rigidity due to annular calcification impairs contraction. In 2D- echocardiography, there is increased echogenicity on the LV side immediately adjacent to the attachment of the posterior mitral valve leaflet. Region of anterior mitral leaflet is only rarely involved. This is common in elderly subjects and younger ones with chronic renal failure and hypertension.

Source(s): Mitral regurgitation

Ischaemic mitral regurgitation

Mitral regurgitation can occur in ischaemia as a result of regional LV dysfunction with abnormal contraction of papillary muscle or underlying ventricular wall. Myocardial infarction can result in MR at rest while in ischaemia it is intermeitting. This characterised by restricted valve leaflet motion and tenting of mitral valve in systole in 2D echo.

Source(s): Mitral regurgitation

Papillary muscle rupture

This is usually a complication of myocardial infarction. If entire papillary muscle is disconnected from the Left ventricle severe MR results and few survive. Partial rupture is more common.

Source(s): Mitral regurgitation

Functional mitral regurgitation

Functional MR results due to LV dilatation and systolic dysfunction in those with a structurally normal mitral valve apparatus.

Source(s): Mitral regurgitation

Pathophysiology

Mitral regurgitation results in increased left ventricular stroke volume and results in LV volume overload. In acute MR, there is increase in ejection fraction to maintain forward flow while in chronic MR, the ejection fraction is normal with increased LV diastolic volume. Asymptomatic irreversible decline in LV function occurs as the LV size progressively increases without an increase in LA (Left atrium) pressure. In acute MR, the regurgitant volume is delivered into a non compliant LA. Pulmonary artery pressure increases due to increased left atrial pressure in chronic and acute MR.

Source(s): Mitral regurgitation

Assessment of severity

Colour flow mapping

colour flow mapping


  • Size of flow recruitment is noted
  • Jet base width at the valve level
  • Intra atrial jet area if it is a central jet
  • Jet direction is usually away from a prolapsing leaflet and beind a restricted leaflet

[1]==== vena contracta ====

  • vena contracta is the narrowest region of regurgitant jet (usually just below the valve in LA)
  • >0.7 cm - severe MR

Source(s): Mitral regurgitation

Continuous wave doppler

  • Shape and density of signal - In severe Mitral regurgitation, the flow is dense and triangular
  • If as dense as forward flow, it is severe.

Source(s): Mitral regurgitation

Pulse wave doppler(PW)

  • PW in apical-4-chamber view
  • E wave more than 1.2m/s indicates severe MR
  • Even minor mitral stenosis or hyperdynamic circulation can increase E wave
  • If A-wave dominant, severe MR is virtually ruled out.

Source(s): Mitral regurgitation

pulmonary venous flow

  • usually forward throughout cycle
  • systolic dominant
  • as MR worsens, there is a blunting of systolic flow
  • If severe MR - systolic flow reversal.

Source(s): Mitral regurgitation

Regurgitant volume

  • Mitral regurgitant volume = Mitral inflow volume - LV outflow volume
Mitral inflow volume = Vti * Cross sectional area of mitral valve
LV outflow volume = Vti * Cross sectional area at LV outflow
  • Regurtitant volume - <20% - mild , >50% severe

Source(s): Mitral regurgitation

PISA (Proximal isovelocity surface area)

The radius of Proximal isovelocity surface area or flow convergence zone which is a 3-dimensional surface area proximal to a narrowed orifice at which all the blood velocities are equal, can be used to calculate the severity of mitral regurgitation. The principle is that if the mitral regurgitation is mild, only the blood nearer to the valve orifice accelerates towards the atrium while in severe regurgitation, blood farther away from the valve moves back.

How to quantify mitral regurgitation with PISA Method

Source(s): Mitral regurgitation

PISA radius

A simple method to determine severity of mitral regurgitation is to measure the PISA radius. Regurgitation is mild if radius is <0.4 cm and severe if >1 cm.

Source(s): Mitral regurgitation

Regurgitant flow (instantaneous)

The instantaneous regurgitant flow can be calculated from the PISA radius and can be used to assess the severity of mitral regurgitation.

Regurgitant flow = 2π * r2 * Valiasing

Source(s): Mitral regurgitation

Effective regurgitant orifice area (EROA)

Effective regurgitant orifice area can be calculated using the instantaneous regurgitant flow. The formula can be derived from the following:

Valiasing * 2πr2 = Vmax * EROA

hence:

  • EROA = PISA (2πr2) * Valiasing / Vmax

Mild = 0-0.20 cm2, moderate = 0.20 - 0.40 cm2, severe = >0.40 cm2

Regurgitant volume can be calculated from this.

  • Regurgitant volume = Effective regurgitant orifice area * Vtime integrale

Source(s): Mitral regurgitation

Severity( Summary)

Severity of mitral regurgitation
Severity mild severe
Jet area <4 cm2 >8 cm2
Jet width thin >0.6
vena contracta <0.3 >0.7
PISA radius <0.4 >1
Pulmonary venous flow systolic dominant systolic flow reversal
Mitral inflow can be A wave dominant E wave dominant >1.2m/s
Continuous wave doppler soft and parabolic dense and triangular
LV and LA normal size enlarged (in chronic MR)
duration can be short holosystolic
Regurgitant volume <30 ml >60 ml
EROA 0-0.20 cm2 >0.40 cm2

Source(s): Mitral regurgitation

External Links


References

  1. ESC guidelines 2012
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