Cardiac valves may be incompetent (regurgitant), stenotic or both. The most common problems are acquired left-sided valvular lesions: aortic stenosis, mitral stenosis, mitral regurgitation and aortic regurgitation. Abnormal valves produce turbulent blood flow, which is heard as a murmur on auscultation; a few murmurs are also felt as a thrill on palpation. Murmurs may sometimes be heard with normal hearts (‘innocent murmurs'), often reflecting a hyper-dynamic circulation, e.g. in pregnancy, anaemia and thyrotoxicosis. Benign murmurs are soft, short, systolic, may vary with posture, and are not associ-ated with signs of organic heart disease.
Diagnosis of valve dysfunction is made clinically and by echocardiography. The severity is assessed by Doppler echocardiography, which measures the direction and velocity of blood flow and allows a calculation to be made of the pressure across a stenotic valve. Transoesophageal echocardiography, cardiac magnetic resonance or invasive cardiac catheterization are usually only necessary to assess complex situations, such as coexisting valvular and ischaemic heart disease, or suspected dysfunction of a prosthetic valve. Treatment of valve dysfunction is both medical and surgical; this may be valve replacement, valve repair (some incompetent valves) or valvotomy (the fused cusps of a stenotic valve are separated along the commissures). The timing of surgery is critical and must not be delayed until there is irreversible ventricular dysfunction or pulmonary hypertension.
Prosthetic heart valves
Prosthetic heart valves are either mechanical or tissue (bioprosthetic). Tissue prostheses are derived from human (homogratt), or from porcine or bovine (xenogratt) origin. Tissue valves tend to degenerate after about 10 years but patients do not need long-term anti-coagulation. These valves are often used in elderly patients. Mechanical valves last much longer but are thrombogenic and patients need lifelong anticoagulation. There are several types of mechanical valve: a ball-and-cage design (Starr-Edwards), tilting disc (Bjork-Shiley) or a double tilting disc (St Jude). All damaged and prosthetic valves carry a risk of infection.
The individual valve lesions are considered separately below, but disease may affect more than one valve (particularly in rheumatic heart disease and infective endocarditis), when a combination of clinical features is produced.
Most cases of mitral stenosis are a result of rheumatic heart disease, with symptoms appearing many years after the episode of acute rheumatic fever. It primarily affects women. However, a reliable history of rheumatic fever is not always obtained.
Thickening and immobility of the valve leaflets leads to obstruction of blood flow from the left atrium to left ventricle. As a result there is an increase in left atrial pressure, pulmonary hypertension and right heart dysfunction. Atrial fibrillation is common due to the elevation of left atrial pressure and dilatation. Thrombus may form in the dilated atrium and give rise to systemic emboli (e.g. to the brain, resulting in a stroke). Chronically elevated left atrial pres-sure leads to an increase in pulmonary capillary pressure and pulmonary oedema. Pulmonary arterial vasoconstriction leads to pulmonary hyperten-sion and eventually right ventricular hypertrophy, dilatation and failure.
Exertional dyspnoea which becomes progressively more severe is usually the first symptom. A cough productive of blood-tinged sputum is common, and frank haemoptysis may occasionally occur. The onset of atrial fibrillation may produce an abrupt deterioration and precipitate pulmonary oedema. Pulmo-nary hypertension eventually leads to right heart failure with fatigue and lower limb oedema.
■ Mitral facies or malar flush occurs with severe stenosis. This is a cyanotic or dusky-pink discoloration on the upper cheeks.
■ The pulse is often irregular as a result of atrial fibrillation.
■ The apex beat is ‘tapping' in quality as a result of a combination of a palpable first heart sound and left ventricular backward displacement produced by an enlarging right ventricle.
■ Auscultation at the apex reveals a loud first heart sound, an opening snap (when the mitral valve opens) in early diastole, followed by a rumbling mid-diastolic murmur. If the patient is in sinus rhythm the murmur becomes louder when atrial systole occurs (presystolic accentuation), as a result of increased flow across the narrowed valve.
The presence of a loud second heart sound, parasternal heave, elevated JVP, ascites and peripheral oedema indicates that pulmonary hypertension pro-ducing right ventricular overload has developed.
Investigations are performed to confirm the diagnosis, to estimate the severity of valve stenosis and to look for pulmonary hypertension.
Chest X-ray shows an enlarged left atrium, pulmonary venous hyper-tension and sometimes a calcified mitral valve. Pulmonary oedema is present in severe disease.
ECG usually shows atrial fibrillation. In patients in sinus rhythm, left atrial hypertrophy results in a bifid P wave (‘P mitrale'). With progressive disease there are features of right ventricular hypertrophy.
Echocardiography confirms the diagnosis and assesses severity.
General Treatment is often not required for mild mitral stenosis. Complica-tions are treated medically, e.g. β-blockers/digoxin for atrial fibrillation, diuretics for heart failure and anticoagulation in patients with atrial fibrillation to prevent clot formation and embolization.
Specitic Mechanical relief of the mitral stenosis is indicated if symptoms are more than mild or if pulmonary hypertension develops. In many cases percutaneous balloon valvotomy (access to the mitral valve is obtained via a catheter passed through the femoral vein, right atrium and interatrial septum, and a balloon inflated across the valve to split the commissures) provides relief of symptoms. In other cases commissurotomy (splitting of the valve leaflets) or mitral valve replacement is necessary. The latter is performed if there is associated mitral regurgitation, a badly calcified valve or thrombus in the left atrium despite anticoagulation.
Prolapsing mitral valve is the most common cause in the developed world but rheumatic heart disease continues to be a common cause in the develop-ing world (Table 10.10).
|Table 10.10 Causes of mitral regurgitation|
Rheumatic heart disease Mitral valve prolapse Infective endocarditis*
Ruptured chordae tendineae*
Rupture of the papillary muscle* complicating myocardial infarction Papillary muscle dysfunction
Dilating left ventricle disease causing ‘functional’ mitral regurgitation Hypertrophic cardiomyopathy
Rarely: systemic lupus erythematosus, Marfan’s syndrome Ehlers-Danlos syndrome
*These disorders may produce acute regurg itation
The circulatory changes depend on the speed of onset and severity of regur-gitation. Long-standing regurgitation produces little increase in the left atrial pressure because flow is accommodated by an enlarged left atrium. With acute mitral regurgitation there is a rise in left atrial pressure, resulting in an increase in pulmonary venous pressure and pulmonary oedema. The left ventricle dilates, but more so with chronic regurgitation.
Acute regurgitation presents as pulmonary oedema. Chronic regurgitation causes Progressive exertional dyspnoea, fatigue and lethargy (resulting from reduced cardiac output). In the later stages the symptoms of right heart failure also occur and eventually lead to congestive cardiac failure. Thrombo-embolism is less common than with mitral stenosis, although infective endo-carditis is much more common.
The apex beat is displaced laterally, with a diffuse thrusting character. The first heart sound is soft. There is a pansystolic murmur (palpated as a thrill), loudest at the apex and radiating widely over the precordium and into the axilla. A third heart sound is often present, caused by rapid filling of the dilated left ventricle in early diastole.
■ Chest X-ray and ECG changes are not sensitive or specific for the diagnosis of mitral regurgitation. On both, evidence of enlargement of
the left atrium, the left ventricle or both, is seen late in the course of the disease.
■ Echocardiography can establish the aetiology and haemodynamic consequences of mitral regurgitation. Doppler and colour flow Doppler is used to measure the severity of mitral regurgitation. Cardiac magnetic resonance or cardiac catheterization is rarely needed for further evaluation.
Mild mitral regurgitation in the absence of symptoms can be managed con-servatively by following the patient with serial echocardiograms every 1-5 years depending on the severity. Patients should be referred for surgery (mitral valve replacement or repair) if more than mild symptoms develop or there is evidence of left ventricular dysfunction (ventricular dilatation or reduced ejection fraction). Emergency valve replacement is necessary with acute severe mitral regurgitation.
Prolapsing (‘floppy’) mitral valve
This is a common condition occurring mainly in young women. One or more of the mitral valve leaflets prolapses back into the left atrium during ventricu-lar systole, producing mitral regurgitation in a few cases.
The cause is unknown, but it is associated with Marfan's syndrome, hyper-thyroidism and rheumatic or ischaemic heart disease.
Most patients are asymptomatic. Atypical chest pain is the most common symptom. Some patients complain of palpitations caused by atrial and ven-tricular arrhythmias. The typical finding on examination is a mid-systolic click, which may be followed by a murmur. Occasionally there are features of mitral regurgitation.
Echocardiography is diagnostic and shows the prolapsing valve cusps.
Chest pain and palpitations are treated with β-blockers. Anticoagulation to prevent thromboembolism is indicated if there is significant mitral regurgita-tion and atrial fibrillation.
There are three causes of aortic valve stenosis:
■ Degeneration and calcification of a normal valve - presenting in the elderly
■ Calcification of a congenital bicuspid valve - presenting in middle age
■ Rheumatic heart disease.
Obstruction to left ventricular emptying results in left ventricular hypertrophy. In turn this results in increased myocardial oxygen demand, relative ischae-mia of the myocardium and consequent angina, arrhythmias and eventually left ventricular failure.
There are usually no symptoms until the stenosis is moderately severe (aortic orifice reduced to a third of its normal size). The classic symptoms are angina, exertional syncope and the symptoms of congestive heart failure. Ventricular arrhythmias may cause sudden death.
The carotid pulse is slow rising (plateau pulse) and the apex beat thrusting. There is a harsh systolic ejection murmur (palpated as a thrill) at the right upper sternal border and radiating to the neck. The murmur may be preceded by an ejection click, which is the result of sudden opening of a deformed but mobile valve.
■ Chest X-ray shows a normal heart size, prominence of the ascending aorta (post-stenotic dilatation) and there may be valvular calcification.
■ ECG shows evidence of left ventricular hypertrophy and a left ventricular strain pattern when the disease is severe (depressed ST segment and T wave inversion in the leads orientated to the left ventricle, i.e. I, AVL, V5 and V6).
■ Echocardiography is diagnostic in most cases. Doppler examination of the valve allows an assessment of the pressure gradient across the valve during systole.
■ Cardiac catheterization and coronary angiography are used particularly in patients with angina to exclude coronary artery disease, which may coexist in this predominantly elderly population.
The onset of symptoms in a patient with aortic stenosis is an ominous sign: 75% of patients will be dead within 3 years unless the valve is replaced. Thus aortic valve replacement is indicated in symptomatic patients, and some would recommend valve replacement for a critically stenotic valve (valve area < 0.6 cm2 or the valve gradient exceeds 50 mmHg on echocardiography) in the absence of symptoms. Balloon aortic valvotomy is sometimes used in childhood or adolescence but aortic valve replacement will usually be needed a few years later.
Aortic regurgitation results from either disease of the valve cusps or dilatation of the aortic root and valve ring. The most common causes are rheumatic fever and infective endocarditis complicating an already damaged valve (Table 10.11).
Chronic regurgitation volume loads the left ventricle and results in hyper-trophy and dilatation. The stroke volume is increased, which results in an increased pulse pressure and the myriad of clinical signs described below. Eventually contraction of the ventricle deteriorates, resulting in left ventricular failure. The adaptations to the volume load entering the left ventricle do not
Table 10.11 Causes and associations of aortic regurgitation
Acute aortic regurgitation
Chronic aortic regurgitation
Chronic rheumatic heart disease
Acute rheumatic fever
Dissection of the aorta
Ruptured sinus of Valsalva aneurysm
Failure of prosthetic heart valve
Ankylosing spondylitis Rheumatoid arthritis
Bicuspid aortic valve
occur with acute regurgitation and patients may present with pulmonary oedema and a reduced stroke volume (hence many of the signs of chronic regurgitation are absent).
In chronic regurgitation, patients remain asymptomatic for many years before developing dyspnoea, orthopnoea and fatigue as a result of left ventricular failure.
■ A ‘collapsing' (water-hammer) pulse with wide pulse pressure is pathognomonic.
■ The apex beat is displaced laterally and is thrusting in quality.
■ A blowing early diastolic murmur is heard at the left sternal edge in the fourth intercostal space. It is accentuated when the patient sits forward with the breath held in expiration. Increased stroke volume produces turbulent flow across the aortic valve, heard as a mid-systolic murmur.
■ A mid-diastolic murmur (Austin Flint murmur) may be heard over the cardiac apex and is thought to be produced as a result of the aortic jet impinging on the mitral valve, producing premature closure of the valve and physiological stenosis.
■ Chest X-ray shows a large heart and dilatation of the ascending aorta.
■ ECG shows evidence of left ventricular hypertrophy (see aortic stenosis).
■ Echocardiography with Doppler examination of the aortic valve helps estimate the severity of regurgitation.
■ Cardiac magnetic resonance or cardiac catheterization is sometimes needed to assess severity.
Mild symptoms may respond to the reduction of afterload with vasodilators and diuretics. The timing of surgery and aortic valve replacement is critical and must not be delayed until there is irreversible left ventricular dysfunction.
Tricuspid and pulmonary valve disease
Tricuspid and pulmonary valve disease is uncommon. Tricuspid stenosis is almost always the result of rheumatic fever and is frequently associated with mitral and aortic valve disease, which tends to dominate the clinical picture.
Tricuspid regurgitation is usually functional and secondary to dilatation of the right ventricle (and hence tricuspid valve ring) in severe right ventricular failure. Much less commonly it is caused by rheumatic heart disease, infec-tive endocarditis or carcinoid syndrome (p. 98). On examination there is a pansystolic murmur heard at the lower left sternal edge, the jugular venous pressure is elevated, with giant ‘v' waves (produced by the regurgitant jet through the tricuspid valve in systole), and the liver is enlarged and pulsates in systole. There may be severe peripheral oedema and ascites. In functional tricuspid regurgitation these signs improve with diuretic therapy.
Pulmonary regurgitation results from pulmonary hypertension and dilata-tion of the valve ring. Occasionally it is the result of endocarditis (usually in intravenous drug abusers). Auscultation reveals an early diastolic murmur heard at the upper left sternal edge (Graham-Steell murmur), similar to that of aortic regurgitation. Usually there are no symptoms and treatment is rarely required. Pulmonary stenosis is usually a congenital lesion but may present in adult life with fatigue, syncope and right ventricular failure.
Infective endocarditis is an infection of the endocardium or vascular endo-thelium of the heart. It may occur as a fulminating or acute infection, but more commonly runs an insidious course and is known as subacute (bacterial) endocarditis (SBE).
Infection occurs in the following:
■ On valves which have a congenital or acquired defect (usually on the left side of the heart). Right-sided endocarditis is more common in intra-venous drug addicts.
■ On normal valves with virulent organisms such as Streptococcus pneu-moniae or Staphylococcus aureus.
■ On prosthetic valves, when infection may be ‘early' (within 60 days of valve surgery and acquired in perioperative period) or ‘late' (following bacteraemia). Infected prosthetic valves often need to be replaced.
■ In association with a ventricular septal defect or persistent ductus arteriosus.
Not all organisms have the same propensity to cause endocarditis. Strep. viridans, Staph. aureus and enterococci are common causes (Table 10.12). Blood cultures remain negative in 5-10% of patients with infective endo-carditis. The usual cause is prior antibiotic therapy and good history taking is vital. Culture-negative endocarditis is particularly likely with the following organisms which are more dif^icult to isolate in culture: Coxiella burnetii (the cause of Q fever), Chlamydia spp., Bartonella spp. (organisms that cause trench fever and cat scratch disease) and Legionella.
|Table 10.12 Modified Duke criteria for the diagnosis of infective endocarditis|
A mass of fibrin, platelets and infectious organisms forms vegetations along the edges of the valve. Virulent organisms destroy the valve, producing regurgitation and worsening heart failure.
Symptoms and signs result from:
■ Systemic features of infection, such as malaise, fever, night sweats, weight loss and anaemia. Slight splenomegaly is common. Clubbing is rare and occurs late.
■ Valve destruction, leading to heart failure and new or changing heart murmurs (in 90% of cases).
■ Vascular phenomena due to embolization of vegetations and metastatic abscess formation in the brain, spleen and kidney. Embolization from right-sided endocarditis causes pulmonary infarction and pneumonia.
■ Immune complex deposition in blood vessels producing a vasculitis and petechial haemorrhages in the skin, under the nails (splinter haemor-rhages) and in the retinae (Roth's spots). Osler's nodes (tender subcuta-neous nodules in the fingers) and Janeway lesions (painless erythematous macules on the palms) are uncommon. Immune complex deposition in the joints causes arthralgia and, in the kidney, acute glomerulonephritis. Microscopic haematuria occurs in 70% of cases but acute kidney injury is uncommon.
Endocarditis should always be excluded in any patient with a heart murmur and fever.
■ Blood cultures must be taken before antibiotics are started. Three sets (i.e. six bottles) taken over 24 hours will identify the organism in 75% of cases. Special culture techniques and serological tests are occasionally necessary if blood cultures are negative and unusual organisms suspected.
■ Transthoracic echocardiography identifies vegetations and underlying valvular dysfunction. Small vegetations may be missed and a normal echocardiogram does not exclude endocarditis. Transoesophageal echo-cardiography is more sensitive (but not 100%) particularly in cases of suspected prosthetic valve endocarditis.
■ Serological tests may be helpful if unusual organisms are suspected, e.g. Coxiella, Bartonella, Legionella.
■ Chest X-ray may show heart failure or evidence of septic emboli in right-sided endocarditis.
■ ECG may show myocardial infarction (emboli to the coronary circulation) or conduction defects (due to extension of the infection to the valve annulus and adjacent septum).
■ Blood count shows a normochromic, normocytic anaemia with a raised ESR and often a leucocytosis.
■ Urine Stix testing shows haematuria in most cases.
■ Serum immunoglobulins are increased and complement levels decreased as a result of immune complex formation.
The Duke classification for diagnosis of endocarditis relies upon major and minor criteria (Table 10.12). A definite diagnosis of endocarditis requires one of the following:
■ Direct evidence of infective endocarditis by histology or culture of organ-ism, e.g. from a vegetation
■ Two major criteria
■ One major and any three minor criteria
■ Five minor criteria.
Possible endocarditis is diagnosed if there is one major and one minor cri-terion or three minor.
Drug therapy Treatment is with bactericidal antibiotics, given intravenously for the first 2 weeks and by mouth for a further 2-4 weeks. While awaiting the results of blood cultures a combination of intravenous benzylpenicillin and gentamicin is given unless staphylococcal endocarditis is suspected, when vancomycin should be substituted for penicillin. Subsequent treatment depends on the results of blood cultures and the antibiotic sensitivity of the organism. Antibiotic doses are adjusted to ensure adequate bactericidal activity (microbiological assays of minimum bactericidal concentrations). Surgery to replace the valve should be considered when there is severe heart failure, early infection of prosthetic material, worsening renal failure and extensive damage to the valve.
1. Ethics and communication
2. Infectious diseases
3. Gastroenterology and nutrition
4. Liver, biliary tract and pancreatic disease
Liver, biliary tract and pancreatic disease
LIVER BIOCHEMISTRY AND LIVER FUNCTION TESTS
SYMPTOMS AND SIGNS OF LIVER DISEASE
NON - ALCOHOLIC FATTY LIVER DISEASE (NAFLD)
COMPLICATIONS AND EFFECTS OF CIRRHOSIS
TYPES OF CHRONIC LIVER DISEASE AND CIRRHOSIS
PRIMARY SCLEROSING CHOLANGITIS
BUDD - CHIARI SYNDROME
LIVER DISEASE IN PREGNANCY
CARCINOMA OF THE PANCREAS
NEUROENDOCRINE TUMOURS OF THE PANCREAS
5. Haematological disease
Assessment and treatment of suspected neutropenic sepsis
INHERITED HAEMOLYTIC ANAEMIAS
ACQUIRED HAEMOLYTIC ANAEMIA
THE WHITE CELL
HAEMOSTASIS AND THROMBOSIS
6. Malignant disease
COMMON INVESTIGATIONS IN MUSCULOSKELETAL DISEASE
COMMON REGIONAL MUSCULOSKELETAL PROBLEMS
THE SERONEGATIVE SPONDYLOARTHROPATHIES
Clinical features, Investigations
INFECTION OF JOINTS AND BONES
AUTOIMMUNE RHEUMATIC DISEASES
SYSTEMIC INFLAMMATORY VASCULITIS
DISEASES OF BONE
8. Water, electrolytes and acid–base balance
WATER AND ELECTROLYTE REQUIREMENTS
BODY FLUID COMPARTMENTS
REGULATION OF BODY FLUID HOMEOSTASIS
PLASMA OSMOLALITY AND DISORDERS OF SODIUM REGULATION
DISORDERS OF POTASSIUM REGULATION
DISORDERS OF MAGNESIUM REGULATION
DISORDERS OF ACID - BASE BALANCE
9. Renal disease
INVESTIGATION OF RENAL DISEASE
URINARY TRACT INFECTION
HYPERTENSION AND THE KIDNEY
RENAL CALCULI AND NEPHROCALCINOSIS
URINARY TRACT OBSTRUCTION
ACUTE RENAL FAILURE/ACUTE KIDNEY INJURY
CHRONIC KIDNEY DISEASE
RENAL REPLACEMENT THERAPY
CYSTIC RENAL DISEASE
TUMOURS OF THE KIDNEY AND GENITOURINARY TRACT
DISEASES OF THE PROSTATE GLAND
10. Cardiovascular disease
COMMON PRESENTING SYMPTOMS OF HEART DISEASE
INVESTIGATIONS IN CARDIAC DISEASE
ISCHAEMIC HEART DISEASE
VALVULAR HEART DISEASE
PULMONARY HEART DISEASE
ARTERIAL AND VENOUS DISEASE
DRUGS FOR ARRHYTHMIAS
DRUGS FOR HEART FAILURE
DRUGS AFFECTING THE RENIN - ANGIOTENSIN SYSTEM
NITRATES, CALCIUM - CHANNEL BLOCKERS AND POTASSIUM - CHANNEL ACTIVATORS
11. Respiratory disease
12. Intensive care medicine
13. Drug therapy, poisoning, and alcohol misuse
14. Endocrine disease
PITUITARY HYPERSECRETION SYNDROMES
THE THYROID AXIS
MALE REPRODUCTION AND SEX
FEMALE REPRODUCTION AND SEX
THE GLUCOCORTICOID AXIS
THE THIRST AXIS
DISORDERS OF CALCIUM METABOLISM
DISORDERS OF PHOSPHATE CONCENTRATION
ENDOCRINOLOGY OF BLOOD PRESSURE CONTROL
DISORDERS OF TEMPERATURE REGULATION
15. Diabetes mellitus and other disorders of metabolism
16. The special senses
COMMON NEUROLOGICAL SYMPTOMS
COORDINATION OF MOVEMENT
THE CRANIAL NERVES
COMMON INVESTIGATIONS IN NEUROLOGICAL DISEASE
UNCONSCIOUSNESS AND COMA
STROKE AND CEREBROVASCULAR DISEASE
EPILEPSY AND LOSS OF CONSCIOUSNESS
NERVOUS SYSTEM INFECTION AND INFLAMMATION
HEADACHE, MIGRAINE AND FACIAL PAIN
SPINAL CORD DISEASE
DEGENERATIVE NEURONAL DISEASES
DISEASES OF THE PERIPHERAL NERVES