Mitral Regurgitation

Francesca N. Delling, MDJuly 8, 2009

Outline

Anatomy

Diagnosis

- Two-dimensional echocardiography (etiology)

- Doppler methods (assessment of severity)

- Role of 2D and 3D-TEE

- Role of CMR

Treatment

Anatomy: The mitral valve apparatus

Subvalvular apparatus (papillary muscles with their supporting left ventricular walls and chordae tendineae)

Mitral annulus Mitral valve leaflets

Anatomy: The mitral valve

Reference view from the left ventricular apex

Surgical view from the left atrium with the heart rotated

Diagnosis

2D Echocardiography: Etiology of mitral regurgitation

Primary:

- Myxomatous

- Endocarditis

- Rheumatic

- Trauma

- Congenital

- Drugs (ergotamines,

methysergide, pergolide, fen fen)

Secondary:

- Non-ischemic dilated CMP

- Ischemic heart disease

- HCM

Type I = normal leaflet motion but with annular dilatation or leaflet perforation

Type II = leaflet prolapse (eg myxomatous disease) or papillary muscle rupture

Type III = restricted leaflet motion.

IIIa = rheumatic disease

IIIb = ischemic or idiopathic cardiomyopathy.

Carpentier classification

2D Echocardiography: additional information

Left ventricular size and function and left atrial size as clues to:

- severity of MR

- acuteness or chronicity

- necessity and timing of surgery

Mitral valve prolapse

Occurs in 2.4% of the population (Freed at al. NEJM 1999)

Patients exhibit fibromyxomatous changes in the mitral leaflet tissue that cause superior displacement of the leaflets into the left atrium (by definition > 2 mm) The most common primary cause of isolated MR requiring surgical repair

Both familial (loci identified: chromosomes 11, 16, 13) and “sporadic” cases observed

Mitral valve prolapse

Mitral valve prolapse

AOSeptum

A

P

AOSeptum

Normal MVP

ACoaptationLV

Leaflet elongation can manifest itself not only by superior motion into the LA but also by anterior motion that shifts the coaptation point toward the aortic root and septum.

Mitral valve prolapse

SUPERIOR

ANTERIOR

LV

AO

LA

AL

PL

Coaptation

RV

I

Coaptation

RV

AOLV AL

PL

II

Prodromal form:

III

LV

AO

LA

AL

PL

Coaptation

RV

I

LV

AO

LA

AL

PL

Coaptation

RV

LV

AO

LA

AL

PL

Coaptation

RV

I

Coaptation

RV

AOLV AL

PL

II

Coaptation

RV

AOLV AL

PL

Coaptation

RV

AOLV AL

PL

II

Prodromal form:

III

Prodromal form:Prodromal form:

III

Nesta et al. Circulation 2005

Prodromal form

Anterior displacement of the coaptation point.

Mild bulging of the posterior leaflet relative to the anterior.

Normal Prodromal

Functional Mitral Regurgitation:Incomplete Mitral Leaflet Closure

LV

LA

NORMAL IMI or global LVD

AO

Papillary Muscle

Displacement

Mitral ValveTethering

IMLC

MRCourtesy of Judy Hung, MD

Functional Mitral regurgitation

Leaflet concavity (PS view) in functional MR

MR related to HOCM

• LV ejection through an LVOT narrowed by both septal hypertrophy and anterior displacement of MV apparatus (PM + MV) causes the Venturi effect or “drag forces” which drag the MV leaflets and chordae towards the septum

• MR is related to SAM of the anterior mitral leaflet AND failure of post leaflet to move anteriorly with consequent gap between the two leaflets

Yu et al. Mitral regurgitation in hypertrophic cardiomyopathy: relationship to obstruction and relief with myectomy. J Am Coll Cardiol 2000;36;2219-2225

Doppler Methods for assessment of severity

Color flow Doppler

- Regurgitant jet area

- Vena contracta

- Flow convergence (PISA)

Continuous wave Doppler

Pulsed Doppler

- Mitral inflow pattern

- Quantitative parameters (regurgitant volume, fraction, EROA)

Regurgitant jet area

Pros:

- Simple, quick screen for mild or severe central MR

- Evaluates spatial orientation of jet

Cons:

- Subject to technical, hemodynamic variation

- Underestimates severity in eccentric jets

Mild: < 4 cm2 or < 20% of LA area

Moderate: variable

Severe: > 10 cm2 or > 40% of LA area

Vena contracta width

LAX SAX

Mild: < 0.3 cm Severe 0.7 with large central jet or with wall impinging jet of any size

Proximal isovelocity surface area (PISA)

Based on the hydrodynamic principle that the flow profile of blood approaching a circular orifice forms concentric, hemispheric shells of increasing velocity and decreasing surface area.

Color flow mapping able to image one of these hemispheres that corresponds to the aliasing velocity or Nyquist limit of the instrument.

The aliasing velocity should be adjusted to identify a flow convergence region with a hemispheric shape.

PkVreg = the peak velocity of the regurgitant jet by continuous wave Doppler Reg volume = EROA x VTIreg jet

Mild: EROA <0.2cm2

Severe: EROA >/=0.4cm2

Pros:

- Presence of flow convergence at Nyquist limit of 50-60 cm/s alerts to significant MR

- Provides both lesion severity (EROA) and volume overload (R Vol)

Cons:

- Less accurate in eccentric jets

- Not valid in multiple jets

- Any error is determining the location/radius of the orifice is squared

Proximal isovelocity surface area (PISA)

EROA = [6.28 x (.8)(.8) ml/s x 36] / [480 cm/s] = 0.3cm2

Example of PISA calculation

r = 0.8 cm

Supportive signs of MR severity

Other supportive signs of MR severity

Mild MR:

- A-wave dominant mitral inflow **

- Normal LV size

Severe MR:

- E-wave dominant mitral inflow (E > 1.2 m/s) **

- Enlarged LV and LA size

** Usually above 50 years or in conditions of impaired relaxation, in the absence of mitral stenosis or other causes of elevated LA pressure

Quantitative pulsed Doppler parameters

In the absence of regurgitation, stroke volume should be equal at different sites, e.g. the mitral and aortic annulus.

In the presence of regurgitation (assuming the absence of an intracardiac shunt), the flow through the affected valve is larger than through other competent valves.

ann

Supportive signs of severityQuantitative pulsed Doppler parameters

JASE 2003;16:777

Summary

2D-TEE localization of MR defects

Foster et al. Ann Thorac Surg 1998;65:1025

Probe inStandard midesophageal position

2D-TEE localization of MR defects

Foster et al. Ann Thorac Surg 1998;65:1025

Probe at 0 degrees, effects of flexion or withdrawal and retroflexion or advancement

2D-TEE localization of MR defects

Foster et al. Ann Thorac Surg 1998;65:1025

40 to 90 degrees, effect of clockwise and counterclockise probe rotation

3D-TEE

To simulate a surgeon’s view of the valve, the 3D TEE image is positioned with the aortic valve the 11-o’clock position.

Intra-Operative 2D and 3D TEE Depiction of MV Prolapse and Leaflet Flail

3D-TEE quantitative analysis of the mitral apparatus

CMR

Etiology of mitral regurgitation

Quantitation of mitral regurgitation

Better determination of volumes and LVEF (facilitating surgical decision making in asymptomatic patients)

LVOT stack

LVOT

Therapy

Therapy

The distinction between primary and secondary MR is key

Correction of primary MR in a timely fashion reverses LV remodeling, PHTN, and heart failure

It is less obvious that correcting secondary MR will be curative or beneficial

Primary MR

No conclusive data showing that medical therapy (vasodilators or beta-blockers) is effective in primary MR without heart failure (however recommended for heart failure)

Surgical therapy- Mitral valve repair instead of replacement is the preferred method in non-rheumatic valves

Copyright ©2008 American College of Cardiology Foundation. Restrictions may apply.

Carabello, B. A. J Am Coll Cardiol 2008;52:319-326

Survival MV repair vs replacement

ACC/AHA 2006 guidelines

Secondary MR

Should be treated with standard heart failure therapy

In selected patients, CRT reduces amount of MR

No evidence of improved survival with annuloplasty

Also divergence of opinion about whether MR should be corrected during revascularization

Copyright ©2008 American College of Cardiology Foundation. Restrictions may apply.

Carabello, B. A. J Am Coll Cardiol 2008;52:319-326

Results of Mitral Surgery in CHF

Limitations of ring annuloplasty

AOLA

LV

Papillary

MuscleTethering

Forces

Ring Annuloplasty

IschemicLV

• Doesn’t address tethering

• Further ventricular remodeling after ring

Percutaneous therapies

Alfieri procedure

Percutaneous mitralannuloplasty

Noninvasive assessment for percutaneous MVR

Role of TEE

Take home points

Need to use multiple criteria for more accurate assessment of MR

Importance of distinguishing primary from secondary MR

In secondary MR, indications for mitral valve intervention are less certain and more data are needed

References

Recommendations for evaluation of the severity of native valvular regurgitation with 2D and Doppler echocardiography. J Am Soc Echocardiogr 2003;16

O’Gara et al. The role of imaging in chronic degenerative mitral regurgitation. JACC Cardiovascular Imaging 2008;1

Carabello. The current therapy for mitral regurgitation. JACC 2008;52