The cardiovascular system - Coronary artery disease 2 Flashcards
(126 cards)
What is infective endocarditis (IE)?
Refers to any infection of the endocardial surface of the heart
Describe the epidemiology of infective endocarditis
- Men are predominately affected
- In the developed world, IE is mostly a disease seen in elderly patients and commonly occurred in patients with pre-existing valvular disease from rheumatic heart disease
Causes of endocarditis can be divided into 5. Give the 5 causes
- Native valve endocarditis
- Prosthetic valve endocarditis (PVE)
- IV drug users (IVDU)
- Culture-negative IE
- Non-infective endocarditis
a) What is native valve endocarditis (NVE) commonly due to?
b) What is the most common organisms causing NVE?
a) Rheumatic heart disease, congenital heart disease or structural disease
b) Usually due to streptococcal species and presents with a subacute course
- Streptococcal species (alpha-haemolytic, S.bovis) and enterococci: implicated in around 70% of cases
- Staphylococcal species: implicated in around 25% of cases. More aggressive disease
a) What does the prosthetic valve endocarditis (PVE) depend on?
b) What is the most common organisms causing early and late PVE?
a) Aetiology of PVE depends on it occurs early (<1 year) or late (>1 year)
b) Coagulase-negative staphylococcus (CoNS) account for 30% of PVE
- Early PVE: occurring shortly after surgery. Staphylococcal species commonly implicates. Acute course (that can cause local abscess, fistula formation, and valvular dehiscence)
- Late PVE: occurring a medium-to-long period after surgery. Streptococcal species commonly implicates. Has a more subacute course
a) What organism is most commonly implicated in IV drugs users (IVDU) associated IE?
b) Explain which valve is most commonly affected?
a) Staphylococcus aureus
b) The tricuspid valve (together with the mitral valve) is commonly affected in IVDU.
Blood from the venous circulation encounters the tricuspid valve first, so bacterial load from repeated injections with contaminated drug paraphernalia is more likely to result in right-sided endocarditis
a) What is culture-negative infective endocarditis defined as?
b) What are 4 possible causes of culture negative IE may be due to?
a) Defined as endocarditis with no definite microbiological aetiology despite adequate sampling
b)
- Typical pathogens
- Pathogens with complex growth
- Intracellular bacteria
- Non-bacterial pathogens (e.g., fungi)
What are 4 possible causes of non-infective endocardiitis
- Physical trauma caused by IV catheters or placing wires
- Systemic lupus erythematosus (SLE)
- Metastatic lung, GI, and pancreatic cancers
- Chronic infections e.g., tuberculosis, osteomyelitis
What are the 3 most common organism species causing IE?
Staphylococcal, streptococcal and enterococcal
Staphylococcal species is one of the most common cause of IE
a) What specific staphylococcal species is most common?
b) What is another common species and what is it commonly associated with?
a) Staphylococcus aureus
b) Coagulase negative staphylococcus (CoNS) and commonly associated with prosthetic devices
Streptococcal species is one of the most common cause of IE.
Give the two most common streptococcal species
Alpha-haemolytic streptococci e.g., Strep Viridans
Beta-haemolytic streptococci e.g., Strep. Bovis
Strep.bovis is a beta-haemolytic streptococci that can cause IE
a) What type of people is this organism commonly seen in?
b) What conditions is the organism associated with and what investigation is required?
a) Elderly
b) Adenomas/adenocarcinomas of the colon and IBD. Colonoscopy is indicated
Enterococcal species is one of the most common cause of IE.
a) What is the most common organism of enterococcus species causing IE?
b) What % of all enterococcus species is caused by this organism?
a) Enteroccous facecialis
b) 90%
S.epidermis is a common organism that causes IE. What type of IE does it cause?
Causes early prosthetic valve IE
Aside from staphylococcus, streptococcal and enterococcus species. What other organisms can cause IE?
- Q fever - Coxiella burnetii
- Brucella
- Pseudomonas aerugionsa
- Fungal - Candida e.g., C.albicans, C.stellatoidea
- HACEK: Haemophilus, Actinobacillus, Cardiobacterium, Eikenella, Kingella –> fastidious (hard to culture) group of gram-negative staining bacteria
When should you suspect Q fever (Coxiella burnetii) causing IE?
Suspect if contact with farm animals and cats/dogs
When should you suspect Brucella causing IE?
Suspect if recent travel or at risk occupation e.g., farmers
75% of fungal infections are caused by the Candida (e.g., C.albicans, C. stellatoidea) . These can cause IE.
What type of people are particularly affected?
IVDU and immunocompromised
Name the two main disease processes underpinning infective endocarditis
- Endocardial injury
- Baceraemia
a) Describe patient-associated risk factors of IE
b) Describe cardiac risk factors of IE
c) Aside from patient-associated and cardiac risk factors of IE. What are other risk factors of IE?
a)
- Age - occurs in patients aged > 60 years
- Male predominance - sex dominance varies from 3:2 to 9:21
- IVDU
- Dentition - poor dental hygiene, dental infections and certain procedures increase risk
b)
- Structural heart disease (75% of IE patients have underlying structural heart disease)
- Valvular heart disease
- Congenital heart disease (e.g., bicuspid aortic valve, ventricular septal defect and cyanotic heart disease)
- Prosthetic heart valves
- Previous IE
- Intravascular devices
b)
- Immunosuppression (e.g., HIV)
- Haemodialysis
a) Describe the symptoms of IE
b) Describe the signs of IE
a)
- Pyrexia
- Constitutional symptoms: malaise, fatigue, anorexia, weight loss
- Abdominal pain: splenic abscess
- Haematuria: renal embolic phenomenon
- Cardiac symptoms: Dyspnoea, chest pain, palpitations
b)
Heart
- New or worsening murmur (85%) - pansystolic murmur of mitral regurgitation or early diastolic murmur of aortic regurgitation
Eyes
- Roth spots: exudative, oedematous haemorrhage lesions of the retina with place centre due to septic emboli to the retina
- Petechiae
Hands and feet
- Clubbing
- Splinter haemorrhages: thin, reddish-brown lines of blood under the nails (micro emboli)
- Osler’s nodes: tender subcutaneous violaceous nodules mostly on the pads of finger and toes. Subacute > acute
- Janeway lesions: contender erythematous macula’s on the palms and soles (micro abscesses). Acute > subacute
Skin and mucosa
- Petechiae on extremities and buccal mucosa
Splenomegaly
The mnemonic to describe clinical features of IE is FROM JANE. What does this stand for?
Fever
Roth spots
Osler nodes
Murmur
Janeway lesions
Anaemia
Nail-bed haemorrhages
Emboli
Around 25% of patients with IE have evidence of embolic phenomenon at the time of diagnosis.
Describe the embolic phenomenons that can manifest
Hands and feet: Osler nodes and janeway lesions
Eyes (2%): Roth spots
Neurological (40%)l: cerebral abscess, intracerebral haemorrhage, embolic stroke, seizures
Septic emboli: splenic, renal, pulmonary abscesses, vertebral osteomyelitis, septic arthritis, psoas abscess
Immune reaction (ie., immune complex deposition): glomerulonephritis, synovitis
Describe the differential diagnosis of infective endocarditis and what is the key differential to be excluded?
May mimic rheumatological and autoimmune condition such as RhA and SLE int he subacute or chronic state
Must be differentiated from other causes of sepsis including pneumonia and abdominal sepsis in the acute setting