Case 1: Mitral stenosis
INSTRUCTION
This patient developed dyspnoea and orthopnoea during pregnancy, please examine her.
This 55-year old patient has atrial fibrillation, please perform 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 regular or irregularly irregular (due to 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 (often difficult to hear; a high-pitched sound that can vary from 0.04 to 0.10 s after the
second sound, and is best heard 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 hop 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 (P2) is loud.
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 (Bt Heart J 1975; 37: 74-8).
Note
· In patients with valvular lesions the candidate would be expected to comment on rhythm, the
presence of heart failure and signs of pulmonary hypertension.
· 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 patients with atrial septal defect have mitral
stenosis, a combination called Lutembacher's syndrome.
DIAGNOSIS
This patient has mitral stenosis (lesion) which is almost always due to 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 mechanism of tapping apex beat?
It is due to 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 ventficular contraction in systole.
What is the mechanism of presystolic accentuation of the murmur?
In sinus rhythm it is due to the atrial systole which increases flow across the stenotic valve from the left
atrium to the left ventricle; 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, due to the start of ventricular systole.
What are the complications?
· Left atrial enlargement and atrial fibrillation.
· Systemic embolization, usually of the 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.)
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 perform?
ECG
Broad bifid P wave (P mitrale); atrial fbrillation in advanced disease.
Chest radiography
· Congested upper lobe veins.
· Double silhouette due to enlarged left atrium.
· Straightening of the left border of the heart due to 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 due to an enlarged left atrium.
· Mottling due to secondary pulmonary haemosiderosis.
Echocardiography
2D 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: 3241).
· It is able to identify restricted diastolic opening of the mitral valve leaflets due to 'doming' of the anterior
leaflet and immobility of the posterior leaflet.
· It also allows assessment of the mitral valve apparatus and left atrial enlargement. · Echocardiography
usually permits an accurate planimetric calculation of the valve area (Am J Cardiol 1979; 43: 560-8).
· It can also be used to assess the severity of stenosis by measuring the decay of the transvalvular
gradient or the 'pressure half-time', an empirical measurement (BrHeartJ 1978; 40: 13140).
· The mean transmitral gradient can be accurately and reproducibly measured from continuous wave
Doppler signal across the mitral valve with the modified Bernoulli equation.
· The mitral valve area can be non-invasively derived from Doppler echocardio-graphy with either the
diastolic half-time method or the continuity equation. The continuity equation should be used when
the area derived from the half-time does not correlate with the mean transmittal gradient.
· Doppler also allows estimation of pulmonary artery systolic pressure from the TR velocity signal and
assessment of the severity of concomitant MR or AR.
· Trans-oesophageal echocardiography is not required unless a question about diagnosis remains
after transthoracic echocardiography.
Cardiac catheterization
· Shows raised right heart pressures and an end-diastolic gradient from pulmonary artery wedge
pressure (or left atrium if trans-septal puncture has been done) to the left ventricle.
· Left and right heart cardiac catheterization is indicated when percutaneous mitral balloon valvotomy
is being considered.
· Cardiac catheterization is also 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.
What is the normal cross-sectional area of the mitral valve?
It ranges from 4 to 6 em2; turbulent flow occurs when this area is less than 2 cm2.
What is the area in 'tight' mitral stenosis?
It is usually less than 1 cm2 and consequently the gradient across the valve is >10 mmHg.
How would you manage the patient?
· Asymptomatic patient in sinus rhythm: prophylaxis against infective endocarditis only.
· Mild symptoms: diuretics to reduce left atrial pressure and therefore symptoms.
· Atrial fibrillation: (1) rate control (digitalis, beta-blocker or calcium channel blocker); (2)
anticoagulants (Eur Heart J 1988; 9: 291-4).
· Moderate to severe symptoms or pulmonary hypertension is beginning to develop: mechanical relief
of valve stenosis including (1) balloon valvotomy (N Engl J Med 1994; 331: 961-7; Br Heart J 1988;
60: 299-308) - percutaneous mitral balloon valvuloplasty is usually the procedure of choice when
there is a non-calcified pliable valve; (2) surgery.
What are the indications for surgery?
· Patients with severe symptoms of pulmonary congestion and significant mitral stenosis.
· Patients with pulmonary hypertension or haemoptysis, even if minimally symptomatic.
· Recurrent thromboembolic events despite therapeutic anticoagulation.
Which surgical procedures are used to treat mitral stenosis?
Closed commissurotomy
· Closed mitral valvotomy - involves the use of mechanical dilators, inserted through the apex of the
left ventricle. It is complicated by mitral regurgitation, systemic embolization and restenosis.
· Balloon valvuloplasty (a form of closed commissurotomy) - 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 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 ofthe valves.
· Little calcification
· Minimal subvalvular disease.
· Mild mitral regurgitation.
In which trimester do 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 the
third trimester, the symptoms might slightly improve.
Mention some rarer causes of mitral stenosis.
· Calcification of mitral annulus and leatlets.
· Rheumatoid arthritis.
· Systemic lupus erythematosus.
· 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's syndrome?
It refers to the hoarseness of voice caused by left vocal cord paralysis associated with enlarged left
atrium in mitral stenosis.
References:
N. Ortner(1865-1935), Professor of Medicine, Vienna, described the syndrome in 1897. He believed in
laboratory research and its application to bedside clinical work and said that the clinician's motto ought to
be '0bers laboratorium dauernd zur Klinik' (translated: 'always via the laboratory to the clinic').
P.J. Kerley (1900-1978), British radiologist.
Paul Wood was a cardiologist at the Hammersmith and National Heart Hospitals. His clinical skills are
legendary and he had a profound influence on British cardiology.
Elliott Cutler, in 1923 in Boston, was the first to attempt surgical treatment of mitral stenosis by inserting a
knife through the apex of the left ventricle and blindly cutting the valve at right angles to its natural orifice.
Henry Souttar, in 1925, relieved mitral stenosis with a finger inserted through the atrial appendage.
In 1948, four surgeons working independently performed successful valvotomies: Horace Smithy, Charles
Bailey, Dwight Harken and Russell Brock.
In 1984, Kanji Inoue from Japan and in 1985, James E Lock, contemporary Professor of Pediatric
Cardiology, Harvard Medical School, and colleagues introduced balloon valvuloplasty for mitral stenosis.
Key words:mitral stenosis murmur mitral valve prolapsemitral stenosis symptoms mitral stenosis treatmentmitral stenosis causes mitral stenosis pathophysiologymitral valve regurgitation mitral valve stenosis
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