Chapter

Heart valve disease

Michael Henein

in Oxford Textbook of Medicine

Fifth edition

Published on behalf of Oxford University Press

ISBN: 9780199204854
Published online May 2012 | e-ISBN: 9780199570973 | DOI: http://dx.doi.org/10.1093/med/9780199204854.003.1606

Series: Oxford Textbooks

Heart valve disease

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Rheumatic valve disease remains prevalent in developing countries, but over the last 50 years there has been a decline in the incidence of rheumatic valve disease and an increase in the prevalence of degenerative valve pathology in northern Europe and North America. In all forms of valve disease, the most appropriate initial diagnostic investigation is almost always the echocardiogram.

Mitral stenosis

The most common cause is rheumatic valve disease. Other causes include mitral annular calcification, congenital mitral stenosis, infective endocarditis (very rarely), and systemic lupus erythematosus (SLE) (Liebman–Sachs endocarditis).

The important consequences of mitral stenosis are its effect on left atrial pressure, size, and the pulmonary vasculature; it commonly causes atrial fibrillation. Presenting symptoms are typically exertional fatigue and breathlessness; systemic embolism can occur. Characteristic physical signs are irregular pulse, tapping apex beat, loud first heart sound, opening snap, and an apical low-pitched rumbling mid-diastolic murmur.

Management—the only medical treatments in mitral stenosis are (1) prophylactic measures against rheumatic fever and endocarditis; (2) anticoagulation to prevent systemic embolism; and (3) diuretics for raised left atrial pressure. Patients who are symptomatic need intervention by either surgical valvotomy or catheter–balloon valvuloplasty, whether or not they have pulmonary hypertension. Early intervention—before the development of atrial fibrillation and an enlarged left atrium—is recommended, provided a conservative operation is possible. Mitral valve replacement is reserved for cases where the mitral valve cannot be repaired.

Mitral regurgitation

The most common causes are ischaemic myocardial dysfunction, mitral valve prolapse, and dilated cardiomyopathy. Other causes include congenital valve disease, infective endocarditis, endomyocardial fibrosis, and connective tissue diseases (including Marfan’s syndrome).

Mitral regurgitation is an isolated volume overload on the left ventricle, providing the physiological equivalent of afterload reduction so that a normal forward cardiac output is maintained by the combination of increased ejection fraction and higher preload. Patients with mild regurgitation may not have any symptoms: those with severe regurgitation are likely to present with dyspnoea. Characteristic physical signs are an apex beat that may be prominent and displaced, an apical pansystolic murmur, and a third heart sound. The loudness of the murmur generally correlates with severity of regurgitation. The cardinal signs of mitral prolapse are a mid-systolic click followed by a murmur.

Endocarditis prophylaxis may be recommended to high risk patients with regurgitation. Patients in atrial fibrillation should be given anticoagulants. The development of symptoms suggests the need for surgical correction to avoid development of irreversible left ventricular dysfunction. Assessment during routine follow-up should identify those likely to need surgical intervention even in the absence of symptoms, with an effective regurgitant orifice of over 40 mm2 being one proposed indication. It is generally considered that a left ventricular end-systolic dimension more than 50 mm indicates a poor prognosis and that surgical intervention is unlikely to be of benefit. If technically possible, mitral valve repair results in a much better clinical outcome than does valve replacement, but mitral replacement by a mechanical valve or bioprosthesis is the only option for irreparable valves.

Aortic stenosis

Aortic stenosis may be at subvalvar, valvar, or supravalvar level, the commonest being valvar stenosis. Age-related degenerative calcific disease is the commonest cause in western Europe and the United States of America. Other causes include congenital bicuspid aortic valve and rheumatic disease (always associated with aortic regurgitation, ‘mixed aortic valve disease’, and usually with rheumatic mitral disease).

With the increase in outflow-tract resistance in aortic stenosis, left ventricular wall stress increases and hypertrophy develops, preserving overall ventricular systolic function, but potentially at the expense of subendocardial ischaemia. Patients with mild disease may be asymptomatic, and even severe stenosis may be silent, but breathlessness, angina, and syncope are typical. Characteristic physical signs are a slowly rising, low-amplitude pulse, a narrow pulse pressure, a sustained apex beat, and a long and harsh ejection systolic murmur that is loudest at the base (second right intercostal space, also known as the aortic area) of the heart, and in most cases radiates to the carotids (where a thrill may be palpable).

Management—patients with moderate or severe disease should be advised to avoid strenuous exercise. Prophylaxis against endocarditis may be recommended to high risk patients. Asymptomatic patients with mild or moderate aortic stenosis require follow-up; those with severe disease (pressure gradient >70 mmHg) need aortic valve replacement.

Aortic regurgitation

Aortic regurgitation is caused by leaflet disease or aortic root dilatation, the commonest causes being isolated medionecrosis, rheumatic disease, infective endocarditis, and Marfan’s syndrome.

The left ventricular stroke volume is significantly increased, which is accommodated by an increase in left ventricular cavity size. As disease progresses, end-systolic volume increases out of proportion to stroke volume, and eventually these changes lead to irreversible damage. The onset of symptoms, particularly breathlessness, coincides with the onset of left ventricular disease. Characteristic physical signs of chronic severe aortic regurgitation are a large amplitude ‘collapsing’ pulse (which when severe can induce pulsations in many parts of the body), a low diastolic blood pressure (<50 mmHg) and/or a high pulse pressure (>80 mmHg), an apex beat that is sustained and/or displaced, and an early diastolic, decrescendo murmur, loudest at the left sternal border. Acute aortic regurgitation causes the patient to be cold and shut down, with tachycardia, hypotension, and a short early diastolic murmur that is easily missed.

Management—medical treatment of chronic aortic regurgitation includes angiotensin converting enzyme (ACE) inhibitors and/or calcium channel blockers to reduce afterload. Patients with a dilated aortic root should be given β-blockade with ACE inhibition/angiotensin receptor blockers. Prophylaxis against endocarditis may be recommended to high risk patients. Although patients with severe chronic aortic regurgitation may remain asymptomatic, valve replacement should be offered when there is progressive increase in left ventricular end systolic dimension, which should not be allowed to reach more than 40 mm.

Right heart valve disease

Many of the conditions that cause right-sided valve diseases are congenital, and are excluded from further discussion here (see Chapter 16.12).

Tricuspid stenosis—this is rare, but most often caused by rheumatic disease that almost invariably simultaneously affects the mitral valve. Symptoms include fatigue, dyspnoea, and fluid retention. On auscultation at the left or right sternal edge, a mid-diastolic murmur is heard and a tricuspid opening snap may be present. Diuretics can help to minimize fluid retention. Severe tricuspid stenosis needs surgical repair, or replacement if additional regurgitation is present.

Tricuspid regurgitation —significant disease is most commonly secondary to pulmonary hypertension and/or right heart dilatation; the commonest noncongenital primary cause is infective endocarditis. Symptoms include fluid retention and hepatic congestion. A raised venous pressure with prominent V-wave is expected. Other signs include a pansystolic murmur at the left or right sternal edge (in one-third of cases), expansile pulsation of the liver (in most), and peripheral oedema/ascites. Diuretics and ACE inhibitors may reduce systemic venous pressure and right ventricular size, even restoring valve competence in some cases. Valve repair or replacement may be advised in some cases.

Pulmonary stenosis—a rare condition usually caused by rheumatic disease or carcinoid syndrome. Fatigue and dyspnoea are the main symptoms. Characteristic physical signs are a prominent venous ‘a’ wave in the neck and an ejection systolic murmur loudest at the upper left sternal edge. Balloon valvuloplasty is the procedure of choice if intervention is warranted.

Pulmonary regurgitation—significant disease is rare, but usually caused by rheumatic disease, carcinoid, and endocarditis. The characteristic physical sign is a soft early diastolic murmur in the left upper parasternal region. Arrhythmia or progressive right ventricular dilatation are indications for surgery, using homograft or conduit and valve.

Chapter.  18280 words.  Illustrated.

Subjects: Cardiovascular Medicine

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