valvular diseases & heart failure Flashcards
What is cardiac output formula and units?
Cardiac output (L/min)= stroke volume x heart rate
Ejection fraction formula and units? What is considered normal?
Ejection fraction = stroke volume / end-diastolic volume x 100 –> normal 50-75%
Mean arterial pressure formula? Another formula? Normal MAP? When is estimation of MAP useable and when not?
MAP = diastolic pressure +1/3 (pulse pressure). MAP = (Cardiac output x systemic vascular resistance) + CVP
MAP >65 mmHg necessary
MAP useable at rest but during exertion it moves closely towards average of SP and DP
Pulse pressure formula?
Systolic - diastolic pressure
What is infective endocarditis? What does it affect?
Infection of endocardium (inner lining of heart muscle) commonly affects the valve
How do you define definite endocarditis?
2 major criteria / 1 major criteria + 4 minor / 5 minor + positive stain on culture
Possible endocarditis?
1 major + more than 1 minor criteria / 3 minor criteria
Rejected endocarditis?
Criteria not met. Resolution before 4 days antibiotics. No evidence of infection after surgery
What are duke’s major criteria?
- persistently positive blood culture for typical organisms 2. ECHO shows vegetation, dehiscence of prosthetic valve, absecess. 3. new valvular regurgitation murmur 4. coxiella burnetti infection
What are duke’s minor criteria?
Predisposing heart condition or IV use. Fever > 38. vascular -> emboli to organs/brain. Immunologic –> glomerulonephritis, osler’s nodes, roth spots, blood cultures that don’t meet criteria
Why are IV users at higher risk of acute infective endocarditis? What valve is usually involved? Which side of heart and why?
IV users high risk because multiple needle punctures gives aggressive staph bacteria many opportunities to enter blood. Valve usually affected is tricuspid valve. Right side of heart usually affected because injected through venous system
What is a vegetation ?
Mass - bacterial infection surrounded by layer of platelets and fibrin
what bacteria most commonly causes endocarditis?
streptococcus
presenting symptoms of endocarditis?
Fever, malaise, sweats, weight loss, new heart murmur, blood tests showing anaemia, raised infection markers, blood cultures +.
what might an ECHO show in endocarditis?
ECHO may show vegetations, abscess, valve perforation & dehiscence of prosthetic valve, regurgitation
Which echo should be preferred and why for endocarditis?
Transoesophageal echo greater sensitivity than transthoracic
What are features of heart decompensation?
Shortness of breath, cough, swelling of legs & abdomen, fatigue. Signs –> Raised JVP, lung crackles & oedema.
What are other complications of infective endocarditis?
Vascular & embolic phenomema, stroke, janeway lesions, oslers nodes, roth spots, immunological phenomena, splinter/conjuctival haemorrhages
What valve is most commonly affected and order?
Aortic > mitral > tricuspid
what do vegetations result in?
formation of vegetations at valves alters their thickness causing failure of them to open / close properly
Why at valves/endocardium?
Attach to endocardium most commonly if underlying damage present which is most commonly at sites of turbulent flow like valves
How does this vary in IV users? When is it most common?
Increased risk due to high entry in blood. Complications in routine surgeries like dental. Most commonly in those immunosuppressed or with congenital heart defects/ damaged endocardium
What is dilated cardiomyopathy?
Dilated chambers with thin walls and decreased contractility. Reduced EJ fraction (reduced systolic function ) and global hypokinesis
How is dilated cardiomyopathy managed?
1st advice - diet modification, fluid/sodim restriction, treat underlying conditions. For heart failure symptoms - diuretics, ACE inhibitors, beta-blockers –> transplants + anticoagulants for clot risk
What is implication of dilated cardiomyopathy?
Risk of atrial fibrillation and thus risk of blood clots
What are genes implicated in dilated cardiomyopathy?
Mutations in genes encoding cardiac cytoskeletal proteins eg. Titin, lamin, cardiac myosin binding protein C, myosin heavy chain. Genes needed for formation of effective contraction of heart chambers so possibly affect myofibril or cellular structure
Commonest causes of dilated cardiomyopathy?
Idiopathic, genetic, toxins (alcohol), chemotherapy, peri-partum cardiomyopathy, thyroid disease, myocarditis, tachycardia related cardiomyopathy
