Cardiology Infections

Rheumatic fever

Introduction
  • Rheumatic fever was once a common cause of valvular heart disease in the UK and USA but is now mainly a disease of the areas in the world or poverty and poor sanitation and living conditions and overcrowding.
  • It can lead to long term scarring and damage of cardiac valves which can then become damaged with either stenoised or incompetent valves or secondarily infected

Aetiology

  • The aetiology is fascinating. An infection from a Group A Streptococci leads to the formation of antibodies which cross react with cardiac tissue such as Myosin and Sarcolemmal membrane protein.
  • This causes localised endocardial inflammation - Aschoff nodule with giant cells and histological evidence of a pancarditis. In deprived areas those affected are in adolescence or younger who develop a Group A streptococcal infection which manifests as a recent sore throat followed several weeks later by Fever, Malaise, Aches which suggest rheumatic fever.

Clinical

  • Classically presents in adolescence following a Gp A strep infection with Heart murmurs which change in severity and timing.
  • Carey-coombs diastolic mitral murmur due to valvulitis or aortic or mitral regurgitation murmur.
  • Ask about joint pains - flitting polyarthritis of the large joints - knees, ankles, elbow which can move from joint to joint.
  • Skin rash such as erythema marginatum (rare). There is a fever.
  • Late signs include Sydenham's chorea. Patient may develop cardiac failure.
  • There is some overlap with other childhood infections and so strict criteria are used in the diagnosis.

Complications

  • The endocardial inflammation can leads to progressive fibrosis of the valve whose supporting structures may be damaged. Over time the lesion scars with involvement of the valve and the valve can become stenosed and typical fish mouth appearance for example of mitral stenosis.
  • There can be Valvular incompetence and even a mixed stenosis and incompetence and more than one valve may be affected. The damaged valve becomes a focus for Endocarditis.
  • There is a possibility of a recurrence of Sydenham's chorea later in life

Investigations

  • FBC - elevated WCC, CRP and ESR elevated
  • Cultures positive for streptococci (positive ASO titre)
  • ECG - 1st degree heart block
  • Echo may show some MR/AR and even a pericardial effusion

Diagnostic Criteria

  • A + (2 major or 1 major and 2 minor criteria)
  • A Signs of recent streptococcal infection
    • Throat cultures positive for group A strep
    • Elevated ASO titres
    • Scarlet fever
    • Other relevant antibodies to strep
  • Major criteria (5)
    • Carditis - manifestations include a Carey-Coomb's middiastolic murmur suggests valvulitis, pericarditis, ST/T wave changes, friction rub, cardiac failure, cardiomegaly.
    • Polyarthritis - acute painful flitting asymmetrical big joints and responds to aspirin
    • Sydenham's Chorea (can recur in later life) occurs late
    • Erythema marginatum - with non itchy pink rashes with a pale centre that spares the face and hands
    • Subcutaneous nodules - firm and painless 1-2 cm in size
  • Minor criteria (6)
    • Fever
    • Arthralgia
    • Previous Rheumatic fever - it does recur,
    • Raised ESR/CRP
    • Leucocytosis
    • Prolonged PR interval - 1st degree heart block

Management

  • Bed rest is traditionally important.
  • High dose Aspirin is given titrated to ESR.
  • Penicillin is given to eradicate streptococci and then long term as recurrence is not uncommon until the age of 21 or longer in some.
  • Prednisolone may be given in severe cases

Infective Endocarditis

Introduction

  • Serious potentially fatal usually bacterial infection of cardiac valves.
  • May be seen in those with Rheumatic heart disease, Congenital heart disease and other causes of valvular heart disease.
  • Do plenty of blood cultures before starting antibiotics

Pathology

  • Infective destructive vegetations form on heart valves.
  • Found where high pressure jets of blood impinge on the endocardium.
  • These vegetations contain fibrin, platelets and microorganisms

Microbiology

  • Staphylococcus aureus: causes a more aggressive acute endocarditis type disease. May be post operative. e.g. early following surgery especially to the heart or valve replacement. Those with IV lines and Central lines. IV drug users.
  • Streptococcus viridans: a low virulence organism seen where there is a history of rheumatic fever. An oral commensal. Cause a subacute clinical picture.
  • Staphylococcus epidermidis : Drug addicts and IV drug abusers have a tendency to RIGHT sided valve lesions particularly
  • Staph lugdunensis - aggressive acute endocarditis
  • Coxiella burnetii (Q fever)
  • Brucella - animal contact
  • Enterococci and other Gram negative bacteria
  • Gram negative HACEK group - Haemophilus sp, Actinobacillus actinomycetemcomitans, Cardiobacterium hominis, Eikenella corrodens, Kingella kingae
  • Candidal infection in immunocompromised

Risks: 60-80% have a Predisposing heart lesions

  • High RISK - Prosthetic valves, MR or AR, VSD, PDA. Medium RISK - AS, HCM.
  • Low RISK - Mitral stenosis, ASD. IV drug users - Tricuspid valve endocarditis with Staph aureus/epidermis. Bicuspid aortic valve - aortic valve endocarditis.

Clinical

  • Fever, Malaise, Joint pains, Stroke/TIA like episodes if emboli
  • Peripheral emboli - gangrene / ischaemic bowel, Finger clubbing - not common < 5% of SBE
  • Osler's nodes - painful, tender nodules on the pulps of fingers, Janeway lesions - small < 5 mm flat painless red spots seen on palms and soles
  • Roth's spots - retinal lesions - haemorrhage and micro infarction of retinal vessels, New or changing murmurs
  • Splenomegaly, Splinter haemorrhages - also seen in manual workers, labourers

Investigations

  • FBC - anaemia, Raised ESR and CRP, U&E
  • Urinalysis - microscopic haematuria
  • ECG -New AV block even a lengthened PR interval suggests Aortic valve involvement
  • CXR - evidence of cardiomegaly, mitral stenosis
  • Transthoracic echo - vegetations and valve disease
  • Trans-oesphageal echo - shows much higher quality views of the heart valves
  • Blood cultures - multiple from multiple sites at different times with fastidious care to avoid contaminants

Complications

  • Valve failure with heart failure (and cardiogenic shock)
  • Septic emboli e.g. stroke (avoid anticoagulation)
  • Glomerulonephritis
  • Aortic root abscess, Valvular abscess
  • Pericarditis

Modified Duke criteria for diagnosis

  • Two major criteria
  • One major and two minor criteria
  • Five minor criteria

Pathological Criteria

  • Positive histology or microbiology of pathological material obtained at autopsy or cardiac surgery
  • Valve tissue, vegetation, embolic fragments or intracardiac abscess content

Major Criteria

  • 2 positive Blood Cultures showing typical organisms consistent with infective endocarditis, such as Streptococcus viridans and the HACEK group OR
  • Persistent bacteraemia from 2 Blood Cultures taken > 12 hours apart or 3 or more positive Blood Cultures where the pathogen is less specific, such as Staphylococcus aureus and Staphylococcus epidermidis OR
  • Positive serology for Coxiella burnetti, Bartonella species, or Chlamydia psittaci OR
  • Positive molecular assays for specific gene targets
  • Positive echocardiogram showing oscillating structures, abscess formation, new valvular regurgitation or dehiscence of prosthetic valves

Minor Criteria

  • Predisposing heart disease
  • Fever > 38
  • Immunological phenomena such as glomerulonephritis, Osler's nodes, Roth spots, or positive Rheumatoid factor
  • Microbiological evidence not fitting major criteria
  • Elevated C reactive protein (CRP) or erythrocyte sedimentation rate (ESR)
  • Vascular phenomena such as major emboli, splenomegaly, clubbing, splinter haemorrhages, petechiae or purpura

Management

  • Usually a prolonged course of antibiotics determined by local advice and sensitivities. Ensure sufficient microbiological samples taken before starting blind therapy. Usually requires 4-6 weeks of IV and then oral therapy. Native valves 2-4 weeks and prosthetic valves 4-6 weeks.
  • Streptococci - Penicillin G and Gentamicin
  • Staphylococcus - Vancomycin + Gentamicin
  • Meticillin resistant Staph Aureus - Vancomycin + Gentamicin + oral rifamipicin
  • Enterococci - Ampicillin IV + Gentamicin (Vancomycn + Gentamicin if ampicillin resistant)
  • Valve surgery if heart failure due to valve destruction, large vegetations on left side with embolic concerns, abscess formation, failing antibiotic therapy.