MITRAL STENOSIS

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INSTRUCTION
This patient developed shortness of breath and orthopnoea during pregnancy, please examine.
This 55-year-old patient has atrial fibrillation, please do the relevant clinical examination.
SALIENT FEATURES
History
 Symptoms of left-sided heart failure: exertional dyspnoea, orthopnoea,
paroxysmal dyspnoea.
 Less frequent symptoms: haemoptysis, hoarseness of voice, symptoms
of right-sided failure (these symptoms are somewhat more specific for
mitral stenosis).
 Obtain a history of rheumatic fever in childhood.
Examination
 Pulse is regular or irregularly irregular (from atrial fibrillation).
 Jugular venous pressure (JVP) may be raised.
 Malar flush.
 Tapping apex beat in the 5th intercostal space just medial to midclavicular line.
 Left parasternal heave (indicating right ventricular enlargement).
 Loud first heart sound.
 Opening snap (OS; often difficult to hear; a high-pitched sound that can
vary from 0.04 to 0.10 s after the second sound (S) and is heard best at
the apex with the patient in the lateral decubitus position).
 Rumbling, low-pitched, mid-diastolic murmur, best heard in the left
lateral position on expiration. In sinus rhythm there may be presystolic
accentuation of the murmur. If you are not sure about the murmur, tell
the examiner that you want the patient to perform sit-ups or hopping
on one foot to increase the heart rate. This will increase the flow across
the mitral valve and the murmur is better heard.
 Pulmonary component of second sound (P) is loud.
Notes

  1. Remember the signs of pulmonary hypertension include loud P2,
    right ventricular lift, elevated neck veins, ascites and oedema. This is
    an ominous sign of the disease progression because pulmonary hypertension increases the risk associated with surgery (Br Heart J
    1975;37:74–8).
  2. In patients with valvular lesions, a candidate would be expected to
    comment on rhythm, the presence of heart failure and signs of pulmonary hypertension.
  3. In atrial septal defect, large flow murmurs across the tricuspid valve
    can cause mid-diastolic murmurs. The presence of wide, fixed splitting
    of second sound, absence of loud first heart sound, and an opening
    snap and incomplete right bundle branch block should indicate the
    correct diagnosis. However, about 4% of the patients with atria

defect have mitral stenosis, a combination called Lutembacher
syndrome.
DIAGNOSIS
This patient has mitral stenosis (lesion), which is almost always caused by
rheumatic heart disease (aetiology), and has atrial fibrillation, pulmonary
hypertension and congestive cardiac failure (functional status).
QUESTIONS
What is the commonest cause of mitral stenosis?
Rheumatic heart disease.
What is the pathology of mitral stenosis?
The main features are leaflet thickening, nodularity and commissural
fusion, all of which result in narrowing of the valve to the shape of a fish
mouth.
What is the natural history of mitral stenosis?
 From the occurrence of rheumatic fever to the onset of symptoms, there
is a long latent period of 20 to 40 years in Europe and North America.
 Moreover, there is a further period of about 10 years before symptoms
become disabling.
 The 10-year survival of untreated patients is 50% to 60%, depending on
symptoms at presentation:

  • When the patient is asymptomatic or minimally symptomatic the
    survival is >80% at 10 years with 60% of patients having no progression of symptoms.
  • Once significant limiting symptoms occur, the 10-year survival rate
    (is poor) 0–15%.
  • When there is severe pulmonary hypertension, mean survival drops
    to <3 years.
     Mortality of untreated patients is caused by:
  • progressive heart failure in 60% to 70%
  • systemic embolism in 20% to 30%
  • pulmonary embolism in 10%
  • infection in 1% to 5%.
    What is the mechanism of tapping apex beat?
    It is from an accentuated first heart sound.
    What does the opening snap indicate?
    The opening snap is caused by the opening of the stenosed mitral valve
    and indicates that the leaflets are pliable. The opening snap is usually
    accompanied by a loud first heart sound. It is absent when the valve is
    diffusely calcified. When only the tips of the leaflets are calcified, the
    opening snap persists.
    What is the mechanism of a loud first heart sound?
    The loud first heart sound occurs when the valve leaflets are mobile. The
    valve is open during diastole and is suddenly slammed shut by ventricular
    contraction in systole.

What is the mechanism of presystolic accentuation
of the murmur?
In sinus rhythm it is caused by the atrial systole, which increases
flow across the stenotic valve from the left atrium to the left ventricle (LV);
this causes accentuation of the loudness of the murmur. This may also
be seen in atrial fibrillation and is explained by the turbulent flow caused
by the mitral valve starting to close with the onset of ventricular systole.
This occurs before the first heart sound and gives the impression of
falling in late diastole. It is, however, caused by the start of ventricular
systole.
What are the complications?
 Left atrial enlargement and atrial fibrillation
 Systemic embolization, usually cerebral hemispheres
 Pulmonary hypertension
 Tricuspid regurgitation
 Right heart failure.
How does one determine clinically the severity of the stenosis?
 The narrower the distance between the second sound and the opening
snap, the greater the severity. The converse is not true. (Note: This time
interval between the second sound and opening snap is said to be
inversely related to the left atrial pressure.)
 The longer the duration of the diastolic murmur, the greater the severity. Note that in tight mitral stenosis the murmur may be less prominent
or inaudible and the findings may be primarily those of pulmonary
hypertension.
ADVANCED-LEVEL QUESTIONS
What are the investigations you would do?
 ECG shows broad bifid P wave (P mitrale); atrial fibrillation in advanced
disease, left atrial enlargement, right ventricular hypertrophy (Fig. 1.1).
 Chest radiography (Fig. 1.2) shows:

  • congested upper lobe veins
  • double silhouette from enlarged left atrium
  • straightening of the left border of the heart caused by prominent
    pulmonary conus and filling of the pulmonary bay by the enlarged
    left atrium
  • Kerley B lines (horizontal lines in the regions of the costophrenic
    angles)
  • uncommonly the left bronchus may be horizontal as a result of an
    enlarged left atrium
  • mottling caused by secondary pulmonary haemosiderosis.
     Echocardiography: two-dimensional and Doppler echocardiography is
    the diagnostic tool of choice for assessing the severity of mitral stenosis
    and for judging the applicability of balloon mitral valvotomy (N Engl J
    Med 1997;337:32–41):
  • can identify restricted diastolic opening of the mitral valve leaflets
    caused by ‘doming’ of the anterior leaflet and immobility of the
    posterior leaflet
  • allows assessment of the mitral valve apparatus and left atrial
    enlargement

can usually permit an accurate planimetric calculation of the valve
area (Am J Cardiol 1979;43:560–8)

  • can also assess the severity of stenosis by measuring the decay of the
    transvalvular gradient or the ‘pressure half-time’, an empirical measurement (Br Heart J 1978;40:131–40)
  • can accurately and reproducibly measure the mean transmitral gradient, using continuous wave Doppler signal across the mitral valve
    with the modified Bernoulli equation
  • can determine the mitral valve area non-invasively from Doppler
    echocardiography with either diastolic half-time method or continuity equation; the continuity equation should be used when the area
    derived from the half-time does not correlate with the means transmitral gradient
  • enables the estimation of the pulmonary artery systolic pressure
    from the tricuspid regurgitation velocity signal with Doppler and
    assess severity of concomitant mitral or aortic regurgitation.
     A transoesophageal echocardiography is not required unless a question
    about diagnosis remains after transthoracic echocardiography. It is also
    useful to exclude thrombus in the left atrial appendage before balloon
    valvotomy or cardioversion.
     Cardiac catheterization:
  • shows raised right heart pressures and an end-diastolic gradient from
    pulmonary artery wedge pressure (or left atrium if trans-septal puncture done to the LV)
  • (left and right heart catheterization) is indicated when percutaneous
    mitral balloon valvotomy is being considered
  • is indicated when there is a discrepancy between Doppler-derived
    haemodynamics and the clinical status of a symptomatic patient.
     Coronary angiography may be required in selected patients who need
    intervention.
     Exercise haemodynamics should be performed when the symptoms are
    out of proportion to the calculated mitral valve gradient area.

Balloon valvuloplasty (a form of closed commissurotomy) is a percutaneous trans-septal balloon mitral valvotomy (or valvuloplasty).
Remember percutaneous balloon dilatation of the mitral valve is a
useful option in patients who are unable to undergo cardiac surgery,
as in late pregnancy or when the patient is too ill (severe respiratory
disease, non-mitral cardiac disease, multiorgan failure).
 Open commissurotomy requires cardiopulmonary bypass and allows
surgical repair of the valve under direct vision resulting in more effective and safer valvotomy than the closed procedure.
 Valve replacement entails risks including thromboembolism, endocarditis and primary valve failure.
What factors determine the success of balloon valvuloplasty?
 Good mobility of the valves
 Little calcification
 Minimal subvalvular disease
 Mild mitral regurgitation.
What are the indications for mitral valve replacement?
Patients who are not good candidates for percutaneous balloon valvotomy
or mitral valve repair who have:
 moderate to severe mitral stenosis and NYHA class III–IV
 severe mitral stenosis (mitral valve area <1 cm2 ) and severe pulmonary hypertension (pulmonary artery systolic pressure >60 mmHg).
In which trimester do pregnant patients with mitral stenosis
usually become symptomatic?
Patients usually become symptomatic in the second trimester of pregnancy, when blood volume increases significantly and increases pulmonary pressures. As the blood volume diminishes late in third trimester, the
symptoms might slightly improve.
Mention some rarer causes of mitral stenosis
 Calcification of mitral annulus and leaflets
 Rheumatoid arthritis
 Systemic lupus erythematosus (SLE)
 Malignant carcinoid
 Congenital stenosis.
Which conditions simulate mitral stenosis?
 Left atrial myxoma
 Ball valve thrombus in the left atrium
 Cor triatriatum (a rare congenital heart condition where a thin membrane across the left atrium obstructs pulmonary venous flow).
Have you heard of Ortner syndrome?
It refers to the hoarseness of voice caused by left vocal cord paralysis
associated with enlarged left atrium in mitral stenosis.
What are the haemodynamic changes in mitral stenosis?
Depends on the severity of mitral stenosis and includes increase in left
atrial pressure, increase in pulmonary arterial pressure and in severe cases
decreased cardiac output

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