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 2^nd 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

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

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.