Congenital Mitral Valve Disease

Seoul National University Hospital

Department of Thoracic & Cardiovascular Surgery

Congenital Abnormalities of Mitral Valve

1 Incidence * 0.2-0.4% of all CHD

* MS : 0.6% in autopsy MR : 0.5% in autopsy * Associated lesions : ASD, VSD, PS, COA, LVOTO Mitral valve malformations may constitute an integral part of complex lesions such as hypoplastic left heart syndrome, Shone’s complex, atrioventricular canal, double inlet ventricle.

2 Pathophysiology MS (75-80% have associated lesions) MR MSR

Pathophysiology of Congenital Mitral Valve Disease

• Malformation of the mitral valve apparatus results in mitral stenosis, insufficiency, or both.

• Significant flow obstruction or regurgitation of the mitral valve results in elevated pulmonary venous pressure and pulmonary congestion.

• Left untreated, pulmonary vascular occlusive changes and pulmonary hypertension lead to right ventricular hypertrophy and right heart failure.

Clinical Features of Congenital Mitral Valve Disease

• Symptoms Fatigue, DOE, recurrent pulmonary infection,

tachypnea, growth retardation, central cyanosis.

Severely affected infants have CHF with gross

pulmonary edema

• Signs Systolic & diastolic murmur, redistribution of

pulmonary vascularity, cardiac enlargement,

LA enlargement, increased MPA, LV enlargement in MR

Patterns of Congenital MV Diseases

1 Mitral Stenosis 1) Associated lesions 25% isolated 30% VSD 40% LVOT obstruction( 2% of COA has congenital MS) others : TOF, VSD+PS, PS

2) Symptom & signs usually severe & if untreated, death during 1st 4~5 years of life

2 Mitral Insufficiency Often only moderate in severity in early life, and 1/2 patients come to operation until older than about 5 years of age.

Types of Congenital Mitral Stenosis

1 Supravalvular * Fibrous ring * Shone’s syndrome

2 Valvular * Fusion of commissure & papillary muscle * Double orifice * Excessive valve tissue * Annular hypoplasia( usually associated with HLHS)

3 Subvalvular * Single papillary muscle (Parachute valve) * Abnormally large or numerous papillary muscle (Hammock valve) * Absent papillary muscle

# Abnormalities associated with LVOTO * Abnormal attachment of the subvalvular apparatus to the septum.

* Systolic anterior movement( usually with hypertrophic cardiomyopathy)

Supramitral Ring

Congenital Mitral Stenosis

Functional Classification (Carpentier)

1. Normal papillary muscle 1) Commissural & papillary fusion 2) Excessive leaflet tissue 3) Valvar ring 4) Annular hypoplasia 2. Abnormal papillary muscle 1) Parachute mitral valve 2) Hammock mitral valve

Parachute-like Asymmetric Mitral Valve

1 Unequal distribution of chords

2 One normal and one elongated papillary muscle

3 Elongated papillary muscle is displaced toward the MV annulus.

4 The anterolateral papillary muscle is usually abnormal.

5 Clinical implications are mitral stenosis and other malformations are present.

Congenital Mitral Regurgitation1 Annulus 1) Dilation * secondary due to ventricular dilation ( rare in primary causes) (endocardial fibroelastosis, infarction, ischemia, ASD)

2 Leaflets 1) Cleft 2) Leaflet defect * hole due to localized agenesis (posterior) 3) Mitral valve prolapse * rupture or elongated chordae tendinea 4) Congenital perforation or displacement * Ebstein’s anomaly of MV 5) Duplication of orifice

3 Subvalvular apparatus 1) Bridge of fibrous tissue ( anomalous arcade) with shortened or absent chordae 2) Shortened chordae tendineae 3) Abnormal papillary muscle

Congenital Mitral Regurgitation Functional classification (Carpentier)

1. Normal motion of the leaflet (type I) 1) Deformation & dilatation 2) Clefts 3) Partial agenesis

2. Prolapse of leaflet (type II) 1) Absence of tendinous cords 2) Elongation of tendinous cords 3) Elongation of papillary m.

3. Restricted motion of leaflet (type III) 1) Normal papillary m. commissural fusion / shortness of cords 2) Abnormal papillary m. parachute / Hammock / hypoplasia of papillary m. /

Ebstein malformation / double orifice

LV Dysfunction in Mitral Regurgitation 1. Indicators

1) NYHA status

2) Ejection fraction

3) LV end-diastolic & end-systolic dimension

4) Rate of rise of LV pressure

5) Left atrial size

6) Pulmonary artery pressure

2. Misleading

It is possible to have LV dysfunction in the presence

of normal LV dimension & minimal symptoms due to

afterload reduction of the regurgitant mitral valve.

Pulmonary Hypertension in MVD

1. Increased LAP transmitted on a retrograde basis into the arterial circulation

2. Vascular remodeling of pulmonary vasculature

in response to chronic obstruction to pulmonary venous drainage(fixed component) 3. Pulmonary arterial vasoconstriction (reactive component)

Indications for Mitral Valve Operation

Severe symptoms & signs of important pulmonary venous hype

rtension are indications of mitral valve anomalies

1 Infancy

1) Mild to moderate symptoms with certainty without valve

replacement : supravalvular ring, commissure fusion

2) Other circumstances

reserved only for infants with intractable heart failure

2 Childhood

1) Considerations for operation are similar

* CHF

* pulmonary hypertension secondary to MVD

2) MVR should be withheld whenever possible

Operative Procedures for Mitral Valve

1. Mitral regurgitation

1) Eccentric annuloplasty

2) Ring annuloplasty

3) Leaflet plication & chordal shortening

4) Suture of cleft

5) Valve replacement

2. Mitral obstruction

1) Resection of supravalvular ring

2) Open commissurotomy & splitting

3) Correction of parachute deformity : splitting & fenestration

4) Valve replacement

Mitral Valve Repair for Multiple Leaflets

• Remodeling the annulus

with Ring(1) after annular

plication with resected

posterior median leaflet(2)

Anatomy of Mitral AnnulusAnatomy of Mitral Annulus

1 C-shaped portion touches the underlying LV

wall, the remaining 25-30% of annulus is

intracavitary.

2 Muscular representation is the basis for

geometric relationship, being more elliptic

in systole and circular in diastole.

* To be a support for the leaflet attachment

* To insulate electrically the atrium from ventricle

Aims for Mitral Valve AnnuloplastyAims for Mitral Valve Annuloplasty

1 Reduce annular dilation & mitral valve area

2 Increase the leaflet coaptation

3 Reinforce the annulus sutures when part of

the valve has been resected

4 Prevent future dilation of annulus

( Stabilization of the posterior annulus )

Complications of Mitral Annuloplasty Ring

1. Postoperative valvular incompetence

most common ; mild in 15% by Echo

2. LVOT obstruction : 3%

3. Suture line dehiscence : 2%

4. Dehiscence of prosthetic ring, fracture, hemolysis

: 1%

5. Aortic regurgitation : infrequent

Postoperative Course & Results 1 Mortality * Usually higher than adult ( LCO, pulmonary hypertension)

2 Complication * Low cardiac output * Neurologic complication * Bleeding and infection * Arrhythmia * Pulmonary insufficiency

3 Risk factors * Young age * Preoperative functional status * Associated cardiac anomaly

4 Long-term result * Most survivors improve functionally. * Better for mitral valve repair than replacement * Residual stenosis or regurgitation is present in most & can progress.