Key facts:
Authors: Alison Hewitt, Yukki Wong, Dawn Adamson
Top Tips: New murmur + fever = Endocarditis until otherwise proven
Key Differential Diagnoses
- Other PUO
- Vasculitis (eg SLE)
- Atrial myxoma
Key Investigations
- BC x3
- FBC, ESR, CRP
- U+E, LFT, Bone, Glucose
- ECG, CXR
- Transthoracic ECHO (TTE)
Key Treatment
- Emperical AB: IV BENZYLPENICILLIN 1.2 g qds + IV GENTAMICIN 5 mg/kg od
- IV AB for 2-4 wks; 6 wks total
Key Management Decisions
- Transoesophageal ECHO (TOE)
- Surgery: Heart valve replacement
Background
Can present atypically eg 'CVA' (septic embolism to brain), other septic emboli, or AF (especially in elderly)
Introduction
- Infective endocarditis (previously called bacterial endocarditis or SBE) is rare and is often missed. This is primarily due to its rarity but also because it can present with non-specific signs and symptoms
- Endocarditis can cause valve regurgitation, obstruction or destruction
- ‘Murmur and fever’ is only one of the many presentations. 15% have no murmur; and <20% of cases present with focal neurologic complaints and stroke syndromes. Other presentations are diverse (even splenic rupture)
- IE mainly occurs on abnormal valves:
- 70% occur on a native valve (NVE). The lesion may be known or unknown (eg rheumatic heart disease, congenital heart disease). Of congenital lesions, especially high risk is cyanotic heart disease eg Fallot’s Tetralogy; whilst moderate risks include VSD, PDA, and coarctation. Other causes include HOCM and syphilitic aortitis
- 30% occur on a prosthetic valve (PVE). This can occur 'early' after prosthetic valve implant (<2 mths; acquired at time of surgery) and has a poor prognosis; or 'late' (>2 mths; haematogenous spread)
- If it occurs on a normal valve, IE often has an acute course, and presents as heart failure. 75% of IVDA with tricuspid endocarditis have a previously normal valve
- Endocarditis often follows infection. This can be introduced during dental procedures (even chewing and toothbrushing can cause bacteraemia), other invasive procedures (eg cystoscopy, endoscopy, bronchoscopy), or foreign bodies (eg ventricular or peritoneal shunt). Any infectious episode in the previous 3 months can cause endocarditis. Other causes include skin disease (in the last three months), gallbladder disease, colon carcinoma, IV cannulation, termination of pregnancy and fracture. Often however, no cause is found
- Left sided endocarditis (90%) is more common than right sided (10%) endocarditis. The mitral and aortic valves are most commonly affected; and occasionally the tricuspid valve, especially the normal valves of IV drug users
- It can also present as complications (eg septic emboli, including ‘CVA’, or septic PE’s). Septic emboli may result in mycotic aneurysm in any large artery
[Ref]
Definition
- An infection of the endocardium and heart valves; usually caused by bacteria, fungi, or other organisms
Epidemiology
- Incidence = 3.6 per 100,000 person-years, in one meta-analysis. Twice as common in men than in women
Organisms
- Streptococcus viridans (35-50%)
- Enterococci; eg Streptococcus faecalis
- Staphylococcus aureus (55% diagnosed at autopsy or surgery) or epidermidis
HACEK group (gram -ve organisms) - Other bacteria: Coxiella, Chlamydia, Brucella, Proteus, Neisseria gonococcus
Fungi: Candida, Aspergillus, Histoplasma
Pathology
Risk factors
- Rheumatic heart disease
- Prosthetic valves
- Congenital heart disease
- Immunocompromised
- IV drug users
- Patients with central lines (ESRF patients, especially those on haemodialysis via dialysis catheters; Hickmann lines) etc
Symptoms
- May be few, or non-specific (eg tiredness etc)
- SOB, and symtpoms of heart failure
- Fever, rigors, night sweats, weight loss
- Symptoms secondary to septic emboli (eg CVA)
Note: atypical presentations well recognised; eg 'CVA' (septic embolus?) or AF (especially in the elderly)
Key questions
- "When did your symptoms start?" "Have you had any dental work, operations or procedures in the last 3 months?"
- "Have you had any heart problems before eg murmurs, heart operations?"
- "Have you noticed any funny rashes, joint pains or dark urine?"
- "Have you ever had rheumatic fever"
Signs
- May be few
- Signs of heart failure
- New murmur, or change in nature of old murmur; examine for changing murmurs daily
- Fingers/toes: clubbing, splinter haemorrhages (1), vasculitic rash (2):
1
2
- Splenomegaly, arthralgia/arthritis, neurological involvement (eg headache, reduced conscious level)
- Signs related to septic emboli (eg CVA)
Note: Oslers Nodes, Roth Spots, Janeway Lesions etc are all rare; look at the teeth
Investigation
'No vegetations' on ECHO ≠ 'no endocarditis'. It is a clinical (not ECHO) diagnosis. Likelihood of embolisation not necessarily linked to vegetations
Blood
- BC x3; different sites, different times; 2 in first 1-2h (then x3 more over first 2d); 90% diagnosed from first 2 sets; BC require 3-4 wks incubation, for some organisms; 10% are culture negative
- FBC, ESR, CRP; normochromic normocytic anaemia; haemolytic anaemia (especially metal valve)
- U+E, LFTs, Bone, Glucose
- ± C3/4 (can be low); Ig's increased; RhF +ve
- Transthoracic ECHO (TTE); may show vegetations, if > 2mm; likelihood of embolisation not necessarily linked to vegetations
- ± VBG/ABG, if very unwell
Culture negative
- Consider: Coxiella burnetti (Q fever; especially aortic valve), Chlamydia psittaci, Brucellosis, Bacteroides, fungi, partially treated bacterial causes, R-sided. Misdiagnoses include: vasculitis (eg SLE), APA syndrome, atrial myxoma and other nonbacterial thrombotic causes (eg carcinoma)
Other
- Urinalysis: microhaematuria, proteinuria, or casts may indicate a secondary glomerulonephritis
- ECG; may be normal; prolonged PR interval is in AORTIC valve endocarditis with perivalvular abscess only; rarely acute (embolic) MI
- CXR; may be normal; heart failure?; 'septic PEs'? (ie pulmonary lesions in R sided endocarditis, or paradoxical emboli)
- Swabs: any source of infection (eg skin)
Diagnosis
- No single diagnostic test - ie it is a clinical (not ECHO) diagnosis. Some use Duke criteria = 2 major; or 1 major + 3 minor; or 5 minor (and no major) criteria
Key investigations
- BC
- Transthoracic ECHO
- Transoesophageal ECHO; better for mitral lesions, and aortic root abscesses
Specialist Investigation
- Radiology for septic emboli: eg CT abdo, CT brain, MRI spine
Differential Diagnoses
- Other PUO
- Vasculitis (eg SLE; antiphospholipid AB syndrome)
- Atrial myxoma
- Nonbacterial thrombotic; known as Marantic endocarditis (eg carcinoma)
Treatment
Initial management should be based on the history and examination – ie if you think of it, treat it. HOWEVER, it is nearly always best to wait until blood cultures have been taken
Treatment (first line)
Drugs
- Emperical AB: IV BENZYLPENICILLIN 1.2 g qds + IV GENTAMICIN 5 mg/kg od (Penicillin Allergy: IV VANCOMYCIN 1 g bd + IV GENTAMICIN 5 mg/kg od); discuss choices with Microbiology ASAP)
Note: other organisms require quite different antibiotics; whatever used, give IV treatment for 2-4 wks, 6 wks in total; monitor response by clinical assessment (murmur changing), CRP, repeat ECHOs - Rx of heart failure, arrthymias
Procedures
- IV line (± fluids, if dry; ± diuretics, if in heart failure)
Stop
- ?Stop/reduce immunosuppression, after DW patient's specialist
Treatment (second line)
- Procedures
- If unwell, central and other lines should be avoided if possible
25-30% require surgery = Heart valve replacement; indications include heart failure (?valve destruction), persistent bacteraemia (especially drug-resistant organism), repeated emboli, fungal, unstable infected prosthetic valve, myocardial abscess
Prescribing issues
- Monitor GENTAMICIN/VANCOMYCIN levels at 48, then 4d, 6d etc; give AB for long enough
Key management decisions
- Transoesophageal ECHO (TOE)
- Surgery: Heart valve replacement
Admit?
- Always
Bed plan
- Medical Admission Ward, then Cardiology
- ± CCU/ITU, if very unwell (eg Acute LVF, ARF, severe sepsis)
Referrals
Medical
- Cardiology
- Microbiology (inform, early)
- ± Cardiothoracic surgical referral not normally necessary. But referral (and surgery) may indicated if there is haemodynamic compromise or embolism. Surgery is often indicated if a prosthetic valve is involved
- ± ITU, if very unwell
The Rest
Initial Rx should be based on HISTORY AND EXAMINATION, not ECHO
Complications
- Heart failure, arrthymias
- ARF; many causes: glomerulonephritis, especially mesangiocapillary = cause of microhaematuria; GENTAMICIN/VANCOMYCIN nephrotoxicity; contrast nephropathy; sepsis/dehydration/ATN; interstitial nephritis, secondary to antibiotics (eg penicillins)
- Vasculitis can affect any blood vessel
- Septic emboli (below)
Septic emboli
- Septic emboli may result in abscess formation in: the myocardium and lungs, the brain, abdominal organs such as the kidneys, spleen and GI tract and the intervertebral discs; or may cause a discitis. They may also cause a mycotic aneurysm in any large artery
- Respiratory emboli can occur in right sided endocarditis (especially drug users) or paradoxical emboli (through septal defects); presenting as pneumonia, lung abscess or ‘septic PE (eg with fever and pleuritic chest pain). Cerebral emboli can result in CVA or brain abscess and cerebral mycotic aneurysms can rupture and present as SAH. Abdominal emboli may present as pain: LUQ pain for splenic emboli and loin pain for renal emboli. Rarely renal emboli cay cause macrohaematuria [Ref]
Follow-up
- Cardiology
Prognosis
- 25-30% of infective endocarditis cases require surgery. 25% of these will have neurological complications and 15% emboli (not predicated by vegetations). Right sided endocarditis has a better prognosis
- 15% mortality; 30% with staphylococci, 14% with bowel organisms, 6% with sensitive streptococci; death usually from heart failure, or embolic phenomenon[Ref] , and [Ref]
2° Prevention + Health promotion
- Oral hygiene
- AB prophylaxis: is a very controversial area. NICE guidelines do NOT recommend antibiotics at all
- Anticoagulation: if in AF or metal valve used
Controversies
- Very few controlled studies endocarditis; making all guidance controversial, eg length of course of AB
- Why is the disease so rare compared with the frequency of valve disease?
- AB prophylaxis is very controversial
Don't forget
- 6 sets of BC
- Atypical presentations: CVA, or AF (especially in elderly)
- Initial Rx based on HISTORY AND EXAMINATION, not ECHO
- Give treatment for long enough
- Endocarditis prophylaxis is controversial: ask an expert
Red flags
- Haemodynamic instability (heart failure, hypotension)
- Staphylococcus
- Neurological symptoms/signs
- Septic emboli
