valvular diseases & heart failure

Question 1

What is cardiac output formula and units?

Answer 1

Cardiac output (L/min)= stroke volume x heart rate

Question 2

Ejection fraction formula and units? What is considered normal?

Answer 2

Ejection fraction = stroke volume / end-diastolic volume x 100 –> normal 50-75%

Question 3

Mean arterial pressure formula? Another formula? Normal MAP? When is estimation of MAP useable and when not?

Answer 3

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

Question 4

Pulse pressure formula?

Answer 4

Systolic - diastolic pressure

Question 5

What is infective endocarditis? What does it affect?

Answer 5

Infection of endocardium (inner lining of heart muscle) commonly affects the valve

Question 6

How do you define definite endocarditis?

Answer 6

2 major criteria / 1 major criteria + 4 minor / 5 minor + positive stain on culture

Question 7

Possible endocarditis?

Answer 7

1 major + more than 1 minor criteria / 3 minor criteria

Question 8

Rejected endocarditis?

Answer 8

Criteria not met. Resolution before 4 days antibiotics. No evidence of infection after surgery

Question 9

What are duke’s major criteria?

Answer 9

1. 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

Question 10

What are duke’s minor criteria?

Answer 10

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

Question 11

Why are IV users at higher risk of acute infective endocarditis? What valve is usually involved? Which side of heart and why?

Answer 11

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

Question 12

What is a vegetation ?

Answer 12

Mass - bacterial infection surrounded by layer of platelets and fibrin

Question 13

what bacteria most commonly causes endocarditis?

Answer 13

streptococcus

Question 14

presenting symptoms of endocarditis?

Answer 14

Fever, malaise, sweats, weight loss, new heart murmur, blood tests showing anaemia, raised infection markers, blood cultures +.

Question 15

what might an ECHO show in endocarditis?

Answer 15

ECHO may show vegetations, abscess, valve perforation & dehiscence of prosthetic valve, regurgitation

Question 16

Which echo should be preferred and why for endocarditis?

Answer 16

Transoesophageal echo greater sensitivity than transthoracic

Question 17

What are features of heart decompensation?

Answer 17

Shortness of breath, cough, swelling of legs & abdomen, fatigue. Signs –> Raised JVP, lung crackles & oedema.

Question 18

What are other complications of infective endocarditis?

Answer 18

Vascular & embolic phenomema, stroke, janeway lesions, oslers nodes, roth spots, immunological phenomena, splinter/conjuctival haemorrhages

Question 19

What valve is most commonly affected and order?

Answer 19

Aortic > mitral > tricuspid

Question 20

what do vegetations result in?

Answer 20

formation of vegetations at valves alters their thickness causing failure of them to open / close properly

Question 21

Why at valves/endocardium?

Answer 21

Attach to endocardium most commonly if underlying damage present which is most commonly at sites of turbulent flow like valves

Question 22

How does this vary in IV users? When is it most common?

Answer 22

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

Question 23

What is dilated cardiomyopathy?

Answer 23

Dilated chambers with thin walls and decreased contractility. Reduced EJ fraction (reduced systolic function ) and global hypokinesis

Question 24

How is dilated cardiomyopathy managed?

Answer 24

1st advice - diet modification, fluid/sodim restriction, treat underlying conditions. For heart failure symptoms - diuretics, ACE inhibitors, beta-blockers –> transplants + anticoagulants for clot risk

Question 25

What is implication of dilated cardiomyopathy?

Answer 25

Risk of atrial fibrillation and thus risk of blood clots

Question 26

What are genes implicated in dilated cardiomyopathy?

Answer 26

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

Question 27

Commonest causes of dilated cardiomyopathy?

Answer 27

Idiopathic, genetic, toxins (alcohol), chemotherapy, peri-partum cardiomyopathy, thyroid disease, myocarditis, tachycardia related cardiomyopathy