MITRAL REGURGITATION

Joanne Cusack

BSE Breakdown

Assessment of severity by:

Chamber sizes and volume overload CW Doppler – shape and density of contour of Doppler signal Vena contracta

PISA and effective regurgitant orifice area

Size of colour jet relative to atrial size by colour flow Doppler Regurgitant fraction, regurgitant volume

Pulmonary vein flow patterns

Indirect effects on LV and LA

Role of echocardiography in determining timing of surgery for primary mitral valve disease: ejection fraction, end-systolic LV diameter, EROA

Role of TOE in assessing mitral valve pathology and in determining likelihood of repair as opposed to replacement

Role of echo

Determine the cause

Assess the severity

Comment on any secondary effects

Causes of MR

Rheumatic

Mitral valve prolapse

Endocarditis

Congenital

Functional

Rheumatic

Mitral valve prolapse

> 2mm systolic displacement of one or both mitral valve leaflets into the left atrium, below the plane of the mitral annulus

Diagnosis more certain when the leaflets are thickened (> 5mm) or myxomatous

Prolapse

Associations

Increased risk of endocarditis

Severe MR

Mitral valve repair or replacement

Congenital

Isolated mitral valve defects - Mitral valve clefts, fenestrations or perforations, double orifice mitral valve, abnormal chordal tissue or insertion, absent or hypoplastic leaflets, accessory leaflets

Associated with other congenital heart defects - Atrioventricular septal defect, Transposition of the great arteries, anomalous origin of the left coronary artery

Functional MR

Caused by regional or global left ventricular remodelling without structural abnormalities of the valve

Usually central in origin

Measurements

Vena contracta

Mitral regurgitant volume

Regurgitant fraction

Effective regurgitant orifice area (EROA)

Proximal isovelocity surface area (PISA)

Vena contracta

Forms immediately distal to the regurgitant orifice with the smallest cross sectional area of regurgitant jet

Represents the physiologic or effective orifice area

Measuring the vena contracta width Optimise colour flow of the regurgitant jet

Zoom into the region of interest

Acquire a loop

Measure the smallest width immediately distal to the regurgitant orifice, perpendicular to the direction of the jet

Severe ≥ 7mm

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Mitral regurgitant volume, regurgitant fraction and EROA

Mitral regurgitant volume

The difference between the flow across the mitral valve and the LVOT

MV RegV = MV flow – LVOT flow

MV flow is the product of the diameter of the mitral annulus

and the TVI through the mitral valve

LVOT flow is the product of the diameter of the aortic

annulus and the TVI through the aortic valve

Regurgitant fraction

The percentage of the LV stroke volume that regurgitates into the left atrium

MR RF = (MV RegV/MV flow) X 100

Effective regurgitant orifice area EROA The area of the regurgitant flow at the level

of the valve

EROA = MV RegV / MR TVI

Size of colour jet relative to atrial size by colour flow

When the area of the regurgitant jet is more than 40% of the LA or reaches the posterior wall of the LA, MR is usually severe

CW Doppler shape and density

In severe MR, flow is dense and triangular

Proximal Isovelocity Surface Area (PISA) Based on the haemodynamic principles of flow

through a small circular orifice in a flat plate

There is flow acceleration just proximal to the orifice

The flow converges on the orifice in hemispheric layers of equal velocity

Colour flow Doppler can be used to calculate the area of the hemisphere

This can be used to calculate the EROA

PISA method

Optimise colour flow imaging of mitral regurgitation from apical window

Zoom in on area of interest

Capture a loop and select the most satisfactory hemispheric PISA, which occurs at mid-systole

Measure the radius (r in cm) along the direction of the ultrasound beam

PISA (cont’d)

Measure the MR velocity with CW Doppler to obtain peak MR velocity (cm/s) and TVI (cm)

EROA = 6.28R2 X Alias V / MR V

PISA through machine

Freeze of PISA and measure r

Freeze of MR Doppler trace and measure VTI

Machine calculates EROA and MR volume

Pulmonary vein flow patterns

Systolic flow reversal suggests severe MR

Indirect effects on LV and LA Enlargement of both is common in chronic

significant MR. May be normal in acute setting

Role of TOE

Used to determine cause and severity

Better images required compared to TTE

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