Mitral Stenosis

1. Natural History

a) Etiology

i) Rheumatic heart disease [almost always]

a) Scarring & fibrosis free edges of leaflets

b) Fusion of valvular commissures

b) Presence of symptoms is ominous - have 50% < 10 years life expectancy

c) Latent period 20 years from onset of symptoms

2. Symptoms

a) Pulmonary oedema

i) reduced net movement of blood from left atrium into left ventricle

Þ increased blood volume in left atrium

Þ increase in left atrial pressures

Þ increased pulmonary capillary pressures

Þ pulmonary oedema

Þ dyspnoea; haemoptysis

b) Pulmonary hypertension

i) increased pulmonary capillary pressures

Þ damming of blood in pulmonary artery

Þ pulmonary oedema

Þ intense pulmonary arteriolar constriction

Þ pulmonary artery hypertension

Þ hypertrophy right heart

Þ Right heart failure

Þ Tricuspid regurgitation

Þ Peripheral congestion

c) Atrial fibrillation

i) increased blood volume in left atrium

Þ enlargement of left atrium

Þ increases electrical pathway conduction distance

Þ development of circus movements

Þ atrial fibrillation

Þ Source of left atrial thrombi

a) systemic emboli

d) left ventricular failure

i) Impaired LVEDV

ii) Reduced cardiac output a late sign especially with

a) Af (impaired preload)

b) exercise

c) pregnancy

3. Pressure-volume loops

· The restriction of flow from the LA to LV results in reduced LVEDP & LVEDV

· Left Ventricular performance is normal

· Stroke volume reduction is entirely due to inadequate filling of the LV

Gross Anatomy

1. Small left ventricle

2. Enlarged thickened left atrium

3. Pulmonary fibrosis

4. Right ventricular hypertrophy & dilatation

Pathophysiology