Aortic dilatation is more likely with associated coarctation, but dissection is relatively uncommon and has a relatively high operative success, probably because of the youth and underlying good health of the subject. Prophylactic surgery is necessary in about 5% during a 20-year follow-up.
Vasculitides, especially giant-cell arteritis and Takayasu’s arteritis may weaken the arterial wall. Other causes of aortic dilatation are trauma, cocaine and amphetamines.
Acute aortic regurgitation occurs also as a result of endocarditis, dissection or trauma.
Mitral valve disease
Rheumatic disease is the overwhelming aetiology world-wide (table 6) and causes isolated mitral stenosis in 40% of cases. However the population prevalence of mitral stenosis in the USA is only 0.1%10 and accounts for only 10% of cases in European hospital-based series.10
The mitral valve apparatus consists of leaflets, annulus, chordae and papillary muscles. Malfunction of one or more of these components can cause mitral regurgitation. Mitral regurgitation is categorised as organic if caused by primary valve dysfunction, and functional if secondary to left ventricular (LV) dysfunction. In the industrialised countries or in the elderly elsewhere, mitral regurgitation (table 7) is predominantly functional, secondary to LV dysfunction.
The cause of LV dysfunction leading to functional mitral regurgitation reflects the causes of heart failure which vary geographically. Endomyocardial fibrosis (EMF) is the second most frequent cause of acquired heart disease in children and young adults in equatorial Africa16 with a prevalence of 20% in coastal Mozambique.
EMF is an idiopathic disease that is mostly confined to the tropical and subtropical rainforest regions of the world. However, subsequent reports have shown its occurrence in the guinea savannah of Nigeria, and even outside the tropical zones. It is the most common cause of restrictive cardiomyopathy worldwide. The disease causes fibrosis of the endocardium, leading to impaired filling. The right ventricle is the most commonly affected, followed by biventricular and then left ventricular involvement. Figure 1117 shows a young patient with EMF, who has New York Heart Association Class III disease necessitating hospital admission to stabilise.
EMF begins as a febrile illness followed by a latent phase of 2–10 years. Symptoms then reappear as LV and right ventricular (RV) thrombi and fibrosis develop leading to RV, LV or biventricular restrictive cardiomyopathy and encasement of the mitral or tricuspid valves. The pathology of EMF is still uncertain.
Mitral prolapse occurs in 2% in Western populations with significant regurgitation in about 9% of these. In the USA the population prevalence is 1.7%1 while mitral regurgitation represented 32% of a hospital-based European survey.10
Congenital mitral disease is uncommon. Patterns described in a series of 49 autopsy cases of congenital mitral stenosis were:
- parachute (single papillary muscle);
- hypoplastic associated with hypoplastic left heart;
- supramitral ring.
Right-sided valve disease
Right-sided disease is uncommon, occurring in 1.2% in the EuroHeart Survey.10 It was not mentioned in USA population-based studies.
Tricuspid stenosis (see table 8) is almost always rheumatic and associated with left-sided disease. Tricuspid regurgitation is commonly functional as a result of pulmonary hypertension or right ventricular myopathy or infarction (see table 9).
Pulmonary regurgitation is commonly functional as a result of pulmonary hypertension (see table 10). Either stenosis or regurgitation occurs in approximately 14% of all congenital cardiac lesions.
Multiple valve disease
Multiple valve involvement represented a significant subgroup in the EuroHeart Survey and occurred in 20% of the database (see figure 12).10 The causes of multiple valve involvement include:
- rheumatic disease
- myxomatous disease
Valve disease is correctly regarded as an epidemic ‘waiting to happen’.17 Degenerative aortic stenosis has become the most common valve disease in Europe, and the United States, due to prolonged life-expectancy and the associated degenerative effects on cardiac structures. In this module, we have looked at other forms of valve disease, particularly those related to rheumatic fever, which continues to be a public health challenge in the developing world.
Other modules in this programme will take us forward into looking at the underlying causes of heart valve disease, along with its presentation, diagnosis and treatment.
- Rheumatic disease is the most common cause of valve disease in the young worldwide with an estimated prevalence of 15.6–19.6 million
- In industrially developed regions diseases of old age predominate, particularly calcific aortic stenosis and functional mitral regurgitation
- In the USA, valve disease is most common in the elderly with a prevalence of 13% in those aged over 75
- Drug-induced valve disease is increasing as a result of 5HT2b receptor agonists
- Infective endocarditis is increasingly related to medical devices and intravenous drug use
- Failure of biological replacement valves is a major burden in all regions of the world
- Variations in access to care exist across the world but also within individual countries
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Suggested further reading
Chambers J. Heart valve disease introduction. Int J Clin Prac 2014;68:1179–80. http://onlinelibrary.wiley.com/doi/10.1111/ijcp.12224/epdf
Rayner J, Coffey S, Newton J, Prendergas BD. Aortic valve disease. Int J Clin Prac 2014;68:1209–15. http://onlinelibrary.wiley.com/doi/10.1111/ijcp.12471/epdf
Coffey S, Rayner J, Newton J, Prendergast BD. Right-sided valve disease. Int J Clin Prac 2014;68:1221–6. http://onlinelibrary.wiley.com/doi/10.1111/ijcp.12485/epdf