RHEUMATIC FEVER

This acute febrile illness is due to a cross-reaction following a group A β-haemolytic streptococci pharyngitis, which causes inflammatory lesions involving the joints, heart and subcutaneous tissues. It presents with polyarthritis, carditis, subcutaneous nodules, rash (erythema marginatum) and chorea. Carditis consists of:

Chronic rheumatic heart disease occurs in about 40% of those with apical and basal diastolic murmurs, and 70% with heart failure or pericarditis during the acute attacks. It is still common in the Middle East, India, Africa and South America, and causes 20–40% of all cardiovascular disease in the Third World.² It is now rare in North America, western Europe, Australasia and parts of Asia.

MITRAL STENOSIS

Rheumatic fever is the main cause of mitral stenosis; rarer causes are:

Scarring or fibrosis of the valves, especially at the edges and sometimes involving the subvalvular apparatus, causes narrowing and hence increased left atrial pressure, pulmonary venous hypertension and pulmonary arterial hypertension. Thus the lungs and right ventricle suffer the most burden. Main symptoms are breathlessness on exertion, recurrent bronchitis, fatigue, palpitations due to paroxysmal atrial fibrillation (AF), haemoptysis and stroke. The onset of AF is usually associated with marked symptomatic deterioration and significantly increases the risk for left atrial thrombus formation and embolism.

Classic signs of mitral stenosis are:

The first clue to the diagnosis is often the loud first heart sound, which should prompt a careful search for the diastolic rumble which may be soft, low-pitched and localised to the apex. An opening snap is present if the valve is not calcified and this occurs 0.04–0.10 s after S₂.

An electrocardiogram (ECG) shows a broad P-wave in lead 2 due to left atrial hypertrophy. Chest X-ray shows an enlarged left atrium and appendage, prominent upper-lobe pulmonary veins, but heart size is usually within normal limits. The diagnosis can readily be confirmed by echocardiography, which allows assessment of the valve anatomy, and estimation of valve area and gradient. Severe stenosis is considered to be present if the valve area is < 1 cm² (Figure 21.1).

Figure 21.1 Mitral stenosis. Thickened and calcified anterior and posterior mitral valve leaflets with reduced opening. LV, left ventricle; LA, left atrium.

Treatment is the use of β-blockers to slow the heart rate and increase diastolic filling time diuretics, and digoxin is given if the patient is in AF. Anticoagulation is essential if there is significant mitral stenosis and AF. Mitral balloon valvuloplasty has been shown to be very successful therapy with excellent long-term outcome, and compares well with surgical treatment.⁵ The main contraindications to balloon valvuloplasty are significant mitral regurgitation and heavy calcification when mutual valve replacement should be done.

MITRAL REGURGITATION

There is a considerable difference between acute and chronic mitral regurgitation (Table 21.1). In chronic mitral regurgitation, there is time for the left ventricle and left atrium to adapt to the increasing regurgitation, leading to their gradual enlargement. In acute mitral regurgitation, the sudden pressure overload of the left atrium and pulmonary veins leads to severe pulmonary oedema. The treatment for acute mitral regurgitation is urgent surgery. The management of chronic mitral regurgitation is more difficult. Initially, medical therapy can be helpful, but the probability of postoperative death or persistent severe heart failure after valve replacement increases abruptly when the left ventricular (LV) end-systolic diameter exceeds 45 mm on echocardiography, or ejection fraction falls below 60%.⁶ In patients without mitral stenosis, mitral valve repair is preferable to replacement, and evidence suggests that preservation of the chordae improves postoperative LV function.⁷

Table 21.1 Mitral regurgitation

MI, myocardial infarction; LV, left ventricle/ventricular; IHD, ischaemic heart disease; IE, infective endocarditis; LA, left atrium/atrial; ACE, angiotensin-converting enzyme.

MITRAL VALVE PROLAPSE⁸

This is a common condition affecting 5% of the adult population – more women than men. It has a number of synonyms, such as Barlow and click–murmur syndrome. It is due to myxomatous degeneration of the valve, with redundancy of the leaflets, which may affect both the anterior and posterior valves. At the end of diastole, the valve closes normally, but as LV pressure rises during systole, a portion of the valve leaflet prolapses in the left atrium, with associated regurgitation. It is usually mild, but can progress and become more severe, and, rarely, the chordae may rupture to produce severe acute regurgitation.

Mitral valve prolapse is usually asymptomatic, but a wide variety of symptoms have been associated, including odd chest pains, palpitations and fatigue. On examination, typical findings are a mid-systolic click and a late systolic murmur, which are separated from the first heart sound, but usually reaching the second heart sound. The murmur may have a crescendo/decrescendo quality. It is usually louder with the Valsalva manoeuvre and on standing. As the prolapse worsens with age the murmur becomes more pansystolic. Echocardiography is diagnostic, and can accurately assess the degree of severity of mitral valve prolapse (Figure 21.2). In most patients, mitral prolapse is a benign condition with a good prognosis. It poses a risk for infective endocarditis, which then leads to a substantial risk of death and need for mitral valve surgery.⁹ There is a very small increased incidence of embolic neurological ischaemic events.

Figure 21.2 Mitral valve prolapse with bowing of the anterior mitral valve leaflet with enlargement of the left atrium but normal left ventricle size.

AORTIC STENOSIS

The commonest cause of aortic stenosis is degeneration of a bicuspid aortic valve. Valve stenosis leads to increased LV systolic pressure, LV hypertrophy and reduced LV compliance. The increased LV work may induce subendocardial ischaemia, arrhythmias and sudden death.

The main symptoms are angina, syncope and breathlessness. Typical findings on examination are a slowly rising small-volume pulse, evidence of LV hypertrophy without an enlarged heart, and a harsh ejection systolic murmur radiating into the neck. If the valve is calcified, there is no click and the A₂ is soft.

An ECG confirms LV hypertrophy. The chest X-ray may show:

Echocardiography is diagnostic, and allows the measurement of the aortic valve area, gradient and the degree of aortic incompetence (Figure 21.3).

Figure 21.3 Aortic stenosis. A calcified thickened valve with reduced opening and the presence of left ventricular hypertrophy.

Medical treatment is not effective. Valve replacement should be performed as soon as the patient is symptomatic, if asymptomatic with LV systolic dysfunction, or if the jet velocity is > 4 m/s in patients undergoing coronary artery bypass surgery.¹⁰

AORTIC REGURGITATION

Like mitral regurgitation, the features of chronic and acute aortic regurgitation are different. Chronic aortic regurgitation has a number of causes, including:

The leak from the aorta increases LV volume, causing LV dilatation and LV hypertrophy. Initially, this is well tolerated but eventually LV function declines.

Main symptoms are fatigue and dyspnoea. Typical findings on examination are a large-volume, bounding, wide pulse pressure which is collapsing in nature. Other classical physical signs include Corrigan’s (visible carotid pulsation) and nail bed capillary pulsation (Quincke sign), which all reflect the rapid run-off. The heart is usually enlarged with a displaced apex, and there is a high-pitched early diastolic blowing murmur which radiates from the left sternal edge to the apex. There may be a mid-diastolic murmur (Austin Flint) due to the regurgitant aortic jet hitting the anterior mitral valve leaflet.

An ECG shows LV hypertrophy, usually with a strain pattern. A chest X-ray shows an enlarged heart with a dilated aorta. Echocardiography is diagnostic and can demonstrate the degree of aortic regurgitation, LV size and function.

The decision to undertake aortic valve replacement in patients with pure aortic regurgitation is difficult. Many patients can survive despite enlarged left ventricles. In general, patients should be advised to have an operation before LV end-systolic dimension exceeds 55 mm or ejection fraction < 60%. Medical therapy with vasodilators such as nefedipine or angiotensin-converting enzyme inhibitors may delay the need for valve replacement.^6,11 However, surgery should not be delayed for too long, otherwise irreversible LV dysfunction ensues.

Acute aortic regurgitation is a severe disease with a high mortality, usually due to endocarditis (Staphylococcus or Pneumococcus).¹² There is acute LV diastolic pressure and volume overload, which leads to severe pulmonary oedema without LV dilatation. It can be difficult to diagnoseclinically, because the early diastolic murmur is very short and soft. An echocardiogram, however, is completely diagnostic, and can demonstrate severe aortic regurgitation, and, more importantly, early closure of the mitral valve. The treatment is urgent surgery without delay.

TRICUSPID REGURGITATION

Tricuspid regurgitation is usually secondary to right ventricular (RV) dilatation/hypertrophy because of pulmonary hypertension. However, increasingly, infective endocarditis (usually Staphylococcus) in drug addicts is a common cause.¹³ The diagnosis is made by the presence of large V-waves in the jugular venous pressure, pansystolic murmur at the left sternal edge and echocardiography. Surgery may be necessary if the degree of valvular regurgitation is severe.

INFECTIVE ENDOCARDITIS

This is one of the most important diagnoses not to miss because untreated it is lethal.^14,15 A delay in diagnosis considerably lowers the probability of survival. The old adage that ‘fever + murmur = endocarditis’ until proven otherwise remains true. In fact any unexplained illness in a patient with a murmur should raise the question of infective endocarditis. The pattern of infective endocarditis is changing; it may be acquired in the community but increasingly in hospitals particularly as a result of procedures involving vascular catheterization, especially in elderly patients. Prior invasive procedures are more common than dental procedures as a cause. Consequently Staphylococcus aureus is now more common than Streptococcus viridans or enterococci in blood cultures. Infective endocarditis may also affect native valves that were previously thought to be normal and increasingly is a problem associated with intravenous drug abuse.

Clinical features of chronic endocarditis may be misleading. The symptoms are vague ill health, weight loss, malaise with night sweats and mild fever, and many patients are assumed to have influenza. In more chronic cases, there may be nail and conjunctival splinter haemorrhages, clubbing, splenomegaly and anaemia. Regurgitant murmurs (aortic, mitral or tricuspid) are usually present, and heart failure is a bad prognostic sign. Emboli may occur, causing strokes. Cerebral mycotic aneurysms are frequently lethal due to late rupture, which may occur many months after succesful treatment of infective endocarditis (see Appendix).

DIAGNOSIS OF INFECTIVE ENDOCARDITIS

The most important investigation remains the blood culture (three sets) before antibiotics are given. Although echocardiography is extremely useful in infective endocarditis, there is a misconception that endocarditis can be diagnosed or excluded by echocardiography. This is not true. Vegetations may be small and not visualised, and large vegetations may be old and sterile. It is not necessary to delay taking blood cultures while waiting for a spike of temperature. It is probably also not necessary to take samples from different sites. Levels of C-reactive protein will usually be elevated in infective endocarditis. The peripheral white cell count is often very high in those infections caused by Staphylococcus but may be normal in those caused by less virulent organisms. Occasionally, patients have so-called blood culture-negative infective endocarditis despite convincing clinical and echocardiographic evidence. In these cases, it is important to look specifically for other organisms such as fastidious bacteria and fungi (or suspect previous antibiotic therapy). Q fever due to Coxiella burnetii is common in certain areas such as Canada and parts of the USA and it can be caught from household cats. Diagnosis can be difficult as the illness is often indolent and fever may be absent. Serology is necessary to make the diagnosis, although C. burnetii antibodies cross-react with Bartonella species. Often the diagnosis is only made by histology of a replaced valve.

Echocardiography may show vegetations if they are > 3 mm and will give useful information on the degree of regurgitation, any intramyocardial spread (abscess formation) and LV function. Transoesophageal echocardiography is much more useful than transthoracic, particularly for mitral valve endocarditis or PVE and the detection of an abscess (Figure 21.4).¹⁶

Figure 21.4 A large vegetation can be seen on the anterior mitral valve leaflet during transoesophageal echocardiography.

PERSISTENT FEVER

A number of possibilities need to be considered, including infection elsewhere either in the heart or outside, such as an infection of a central line which should be removed and sent for culture. Abscesses, paravalvular or intracardiac, are an important cause of persistent or recurrent fever and require surgery. It is nearly always impossible to eradicate an abscess by medical therapy only, and it is generally better to undertake surgery earlier than later. In some patients who appear to be well controlled, an abscess may be detected by transoesophagealechocardiography, but after stopping the antibiotics the infection will recur (Figure 21.5). Extracardiac infection may be due to a myocotic aneurysm which can cause fever or metastatic infection. Myocotic aneurysms of the brain can be a particular problem and may lead to rupture many months or even years later.

Figure 21.5 Abscess cavities seen in the aortic root during transoesophageal echocardiography.

OSTIUM SECUNDUM ATRIAL SEPTAL DEFECT

This is the commonest congenital cardiac abnormality in adults. It is often unrecognised because symptoms may be absent and the physical signs are subtle. Older patients may develop atrial fibrillation and cardiac failure. Paradoxical emboli through the defect are rare.

Examination typically shows a pulmonary ejection systolic murmur with a wide and fixed second heart sound.

ECG usually shows a right bundle branch block (and a left axis deviation with a primum defect). Chest X-ray will show pulmonary plethora.

Echocardiography, especially transoesophageal echocardiography, can demonstrate the defect and give an estimate of the pulmonary artery pressure. There is an increased risk of developing Eisenmenger’s syndrome but no risk of endocarditis. Many patients can live to a good age but overall life expectancy is not normal. Closure is by surgery or more usually now an occluder introduced percutaneously is usually recommended if the size of the shunt is > 1.5:1.0. Patent foramen ovale can now also be closed percutaneously. This is often done if there is evidence of paradoxical emboli.¹⁸

PATENT DUCTUS ARTERIOSUS

This congenital abnormality is often asymptomatic and survival is usual. At the age of about 20, the risk of infective endocarditis increases, and at the age of about 30, patients with sizeable left-to-right shunts will begin to develop cardiac failure. Patients with significant shunts should havethe patent ductus arteriosus closed by surgery or, increasingly, by transcatheter using an umbrella device.¹⁹

VENTRICULAR SEPTAL DEFECTS

These are very common at birth but are seldom found in adults. The occasional adult will survive with a persistent small perimembranous ventricular septal defect which is not haemodynamically significant but a risk for endocarditis.

FALLOT’S TETRALOGY

This is the cyanotic malformation most frequently associated with survival to adulthood. In these patients, the pulmonary stenosis is usually sufficient to prevent excessive pulmonary blood flow, but not so severe as to causelarge degrees of shunting from the right to the left ventricle. An increasing number of patients who have had complete repair are surviving into adulthood, and overall outcome is excellent.²⁰ The 30-year actuarial survival rate is 90% of the expected, and late health status is very good. However, in some RV fibrosis and damage may lead to ventricular arrhythmias and sudden death. Also there is an increased risk of conduction defects (heart block).

NON-CARDIAC SURGERY

OSTIUM SECUNDUM ATRIAL SEPTAL DEFECT

In asymptomatic adults with this malformation and with normal pulmonary artery pressure, there is little risk during non-cardiac surgery. However, a rise in peripheral vascular resistance will increase left-to-right shunting; with hypotension, right-to-left shunting may occur. Systemic paradoxical emboli from leg veins can occur and early mobilisation is recommended.

CONGENITAL COMPLETE HEART BLOCK

If the QRS is narrow and the subsidiary pacemaker is reliable with a reasonable ventricular rate, then temporary RV pacing is not required. However, all vagotonic stimuli should be minimised. If the QRS complex is wide and there is a relatively slow ventricular response, a temporary pacemaker should be inserted preoperatively.

NICE GUIDANCE

Antimicrobial prophylaxis against infective endocarditis in adults and children undergoing interventional procedures (March 2008)

Antibacterial prophylaxis and chlorhexidine mouthwash are not recommended for the prevention of endocarditis in patients undergoing dental procedures.

Antibacterial prophylaxis is not recommended for the prevention of endocarditis in patients undergoing procedures of the:

Whilst these procedures can cause bacteraemia, there is no clear association with the development of infective endocarditis. Prophylaxis may expose patients to the adverse effects of antimicrobials when the evidence of benefit has not been proven.

Any infection in patients at risk of endocarditis¹ should be investigated promptly and treated appropriately to reduce the risk of endocarditis.

If patients at risk of endocarditis¹ are undergoing a gastro-intestinal or genito-urinary tract procedure at a site where infection is suspected, they should receive appropriate antibacterial therapy that includes cover against organisms that cause endocarditis.

Patients at risk of endocarditis¹ should be:

From BNF: http://www.bnf.org/bnf/bnf/55/102053.htm