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Valvular heart disease

Aetiology

  • Principal causes vary between Western and developing countries
  • Common causes are:
    • Congenital valvular abnormalities (e.g. bicuspid aortic valve)
    • Infective endocarditis
    • Rheumatic fever
    • Degenerative valve disease
    • Ischaemic heart disease

Pathology

  • Rheumatic fever results from immune-mediated inflammation of heart valve
  • Results from cross reaction between Group A haemolytic strep and cardiac proteins
  • Valve disease results in either stenosis or incompetence
  • Stenosis causes pressure load on proximal chamber
  • Incompetence causes volume load proximal chamber
  • Thrombus may form in dilated left atrium resulting in peripheral embolisation

Clinical features

Aortic stenosis

  • Angina pectoris
  • Syncopal episodes
  • Left ventricular failure
  • Slow upstroke to arterial pulse
  • Ejection systolic murmur in 2nd right intercostal space

Aortic regurgitation

  • Congestive cardiac failure
  • Increased pulse pressure
  • Water-hammer pulse
  • Early diastolic murmur at left sternal edge

Mitral stenosis

  • Pulmonary hypertension
  • Paroxysmal nocturnal dyspnoea
  • Atrial fibrillation
  • Loud first heart sound
  • Mid diastolic murmur at apex

Mitral regurgitation

  • Pulmonary oedema
  • Apex beat displace laterally
  • Apical pansystolic murmur

Tricuspid stenosis

  • Fatigue and peripheral oedema
  • Hepatomegaly and ascites
  • Increased JVP with prominent a waves
  • Diastolic murmur at left sternal edge

Tricuspid regurgitation

  • Pulsatile hepatomegaly and ascites
  • Right ventricular heave
  • Prominent JVP with large v waves
  • Pansystolic murmur at left sternal edge

New York Heart Association classification

  • Dyspnoea can be classified by severity of symptom
Classification Symptoms
NYHA I Capable of ordinary physical activity
NYHA II Ordinary activity induces dyspnoea
NYHA III Limitation of physical activity
NYHA IV Symptoms at rest

Investigation

  • Investigation of valvular heart disease will require:
    • Electrocardiogram
    • Chest x-ray
    • Echocardiography
    • Cardiac catheterisation with measurement of transvalvular gradient

Medical Management

  • Few patients with symptomatic aortic stenosis survive 5 years
  • Approximately 20% of symptomatic patients will suffer sudden death
  • Asymptomatic mitral stenosis is well tolerated with greater than 50% 10-year survival
  • Medical management consists of:
    • Treatment of cardiac failure
    • Digitalisation if in atrial fibrillation
    • Anticoagulation if evidence of peripheral embolisation

Surgical management

  • Approximately 7,000 patients per year undergo valve replacement
  • Aortic valve is commonest to be replaced (~75% of operations)

Indications for surgery

  • Aortic valve replacement
    • Symptomatic aortic stenosis
    • Asymptomatic aortic stenosis with pressure gradient > 50 mmHg
    • Symptomatic aortic regurgitation
  • Mitral valve replacement
    • Symptomatic mitral stenosis especially if peripheral emboli
    • Mitral valve area less than 1 cm2 
  • Surgery usually performed through a median sternotomy
  • On cardiopulmonary bypass with systemic hypothermia
  • Heart is arrested and protected with cardioplegic solution
  • Valve can be either repaired or replaced
  • Valve repair results in better haemodynamics
  • Does not require long-term anticoagulation

Prosthetic heart valves

  • Principal types are:
    • Heterografts (e.g. pig) stented or unstented
    • Homografts
    • Ball and cage (e.g. Starr-Edwards)
    • Tilting disc (e.g. Bjork-Shiley)

Mechanical valves

  • Readily available
  • Good durability
  • Require life-long anticoagulation
  • Risk of endocarditis

Starr Edwards heart valve

Heterografts

  • Readily available
  • Limited lifespan (aortic valves ~ 15 years, mitral valve ~8 years)
  • Limited duration of anticoagulation

Homografts

  • Not readily available
  • Do not require anticoagulation
  • Long-term outcome uncertain

Bibliography

Chandrashaker Y,  Westerby S,  Narula J.  Mitral stenosis.  Lancet 2009;  374:  1271-1283.

Goldsmith I,  Turpie A G,  Lip G Y. Valvular heart disease and prosthetic heart valves.  Br Med J 2002;  325:  1228-1331.

Rahimtoola S H.  Choice of prosthetic heart valve for adult patients. J Am Coll Cardiol 2003;  41:  893-904.

Thamilarasan M,  Griffin B.  Choosing the most appropriate valve operation and prosthesis.  Cleve Clin J Med 2002;  69:  693-698.

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