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72 Chapter 2: Cardiovascular system

and immunity of the individual. The result is either an Splinter haemorrhages, linear dark streaks seen in the
acute infection or a more insidious (subacute) course. nail bed are due to vasculitis.
The bacteria proliferate on the endocardium, causing Janeway lesions are small, flat, erythematous lesions
the development of friable vegetations containing bac- on soles and palms, particularly the thenar and hy-
teria, fibrin and platelets. This may result in destruction pothenar eminences, caused by vasculitis.
of valve leaflets, perforation and hence disturbance of Petechiae may be embolic or vasculitic often seen on
function. The disease process predisposes to the forma- mucosa of pharynx and retinal haemorrhages may
tion of thrombus with the potential for emboli. Cytokine be seen (Roth’s spots are haemorrhages with a pale
generation causes fever. There is a vasculitis and the for- centre).
mation of immune complexes.
Inacuteendocarditis(particularlywhereStaph.aureus

is the cause) the disease is rapid, progresses to cardiac Investigations
failure and is often fatal. Blood cultures are positive in 90% when three sets of
The majority of cases are subacute in which bacterial
cultures are taken from differing sites.
multiplication is slower and the cardiac lesion may Echocardiography is used to visualise vegetations
be less obvious; however, systemic manifestations be- and to assess the degree of valvular dysfunction. If
come more significant. the transthoracic echo is not diagnostic a transoe-
sophagealechoisusefulespeciallytoshowmitralvalve
disease, aortic root abscess and to visualise leaflet per-
Clinical features forations.
Afever and a new or changing murmur is endocardi- Full blood count shows an anaemia with neutrophilia.
tis until proven otherwise, although these signs are not There is a high ESR and CRP.
universal. Microscopic haematuria results from the immune
Typical presentations: complexes. Urine cultures may be required to identify
Acute bacterial endocarditis presents with fever, new aurinary tract infection, and renal ultrasound may be

or changed heart murmurs, vasculitis and infective indicated to demonstrate a renal abscess.
emboli. Severe acute heart failure may occur due to Chest X-ray may show heart failure or pulmonary in-
chordal rupture or acute valve destruction. farction/abscess.
Subacute endocarditis presents with general symp- ECG may show a prolonged PR interval suggests aor-

toms such as fever, night sweats, weight loss, malaise tic root abscess encroaching on the atrioventricular
and symptoms of cardiac failure or thromboem- node.
bolism.
General signs:
Malaise, pyrexia, anaemia and splenomegaly, which Complications

may be tender. Cardiac failure is the most serious potential compli-
Clubbing of the nails is seen only in subacute forms as cation particularly when treatment is delayed.

it takes months to develop. Virtually any organ system may be affected by mycotic
Arthralgia may occur as a result of immune complex emboli, which commonly develop into abscesses. For

deposition. example cerebral, renal, splenic or mesenteric infarc-
Cardiac lesions: tion and abscess formation in left-sided cardiac le-
Neworchanged murmurs are characteristic. sions, or pulmonary abscesses in right-sided cardiac

Cardiacfailureoccursasaresultofthehaemodynamic lesions. Cerebral emboli may cause infarction or my-

disturbance due to the valve lesion(s), e.g. aortic or cotic aneurysms resulting in convulsions, hemiplegia
mitral regurgitation. or other abnormal neurology. Emboli may even occur
Skin lesions: after treatment has been completed.
Osler’s nodes are tender nodules palpated at the tips of
Nephrotic syndrome or renal failure due to the
fingers and toes; they are embolic or vasculitic lesions glomerulonephritis that occurs following immune
causing pulp infarcts. complex deposition within the kidneys.