Infectious diseases of heart Flashcards
What is infective endocarditis?
It is infection of the inner endocardium, it affects valves, septa, chordae tendinea, intra-cardiac devices
What is the prognosis for patients with endocarditis ?
The prognosis is poor, the mortality is high
What are the non-cardiac risk factors for infective endocarditis?
IV drug use, immunocompromised, AIDS, diabetes mellitus, chronic skin conditions, GI infections. or manipulations, GI lesions, pregnancy, abortion, alcoholic cirrhosis, solid organ transplant, body lice, pneumonia, meningitis, cat exposure, indwelling medical devices
What are the cardiac risk factors for infective endocarditis ?
mitral valve prolapse and regurgitation, ventricular septal defect, aortic stenosis and regurgitation, rheumatic heart disease, prosthetic heart valve, cardiac surgery, prior IE, congenital heart defects, intra-cardiac devices, invasion procedures to heart
What part of heart is more affected by IV drug use?
The right side of the heart
What is the initial step in infective endocarditis?
mechanical disruption of valve endothelium
What are the causes of the mechanical disruption of endothelium of valves?
It can be caused by turbulent flow called the Venturi effect, electrodes, catheters, rheumatoid carditis, degenerative changes, but if the endothelium is physically normal there is local inflammation
What is Venturi effect?
It describes how pressure and velocity changes as blood flows through constriction, in has high pressure and low velocity, then as it enters the constriction there is low pressure but high velocity and the back again to low velocity and high pressure,
What is the second stage in infective endocarditis?
Formation of sterile thrombus, it is formed on damaged endothelium, it consists of fibrin-platelet network, adherence and invasion of the thrombus
What is the third set in the infective endocarditis ?
There must be bacteraemia in the blood, invasion of bacteria into the sterile thrombus
What can cause bacteraemia?
Invasive procedures especially GI, oral, abdominal, genitourinary interventions and surgeries, intravascular catheters, gingival disease, can be also caused by brushing teeth
What is the classification of IE based on duration?
acute, subacute, chronic
Which organism is associated with acute infection?
Staph aureus
Which organism is associated with subacute infection?
Streptococcus
What is the classification of IE based on the location?
left-sided native valve, left side prosthetic valve, right sided, device related such as PPM permanent pacemaker, ICD implantable cardioverter defibrillator
What is classification based on the mode of acquisition?
healthcare related (nosocomial, non-nosocomial), community acquired, IVDA (IV drug abuser)
What are the symptoms of IE?
fever of unknown origin, fatigue, malaise, other possible symtoms are weight loss, headache, muscoskeletal pain
What are the signs of IE?
splinter haemorrhages, vasculitis rash, Roth spots,, Oslers nodes, Janeway lesions, new murmur, bacterium, can also have congestive heart failure, embolic phenomena signs
What is Roth spot?
retinal haemorrhage, has white or pale centre
What are Osler’s nodes?
deep, red spots that are painful, raised, usually on finger pulls, palms and sores
What are Janeway lesions?
flat, macular, ecchymotic spots, they are non-tender, on palms, soles
When can be the signs absent?
in elderly patients, after antibiotic treatment, in immunocompromised, if the organism is less virulent or atypical
What investigations are performed for IE diagnosis?
Bloods (FBC, CPR, U+E), blood cultures that are taken from 3 different sites and are 6 hours apart, if the patient os very unwell 2 sets in 1 hour, ECG, chest X ray, urinalysis, ECHO
What are the two types of ECHO that can be performed for IE?
transthoracic TTE and transoesophageal TOE
