Valvular Disease & Heart Failure

Question 1

Label this diagram of the heart

Answer 1

Question 2

How do you calculate cardiac output and how is it defined (with units)?

Answer 2

Heart rate x stroke volume

Cardiac output is the volume of blood the heart pumps in one minute, expressed in L/min or cm3/min

Question 3

How do you calculate stroke volume?

Answer 3

End diastolic volume - end systolic volume

Question 4

How do you calculate the ejection fraction and how is it defined?

Answer 4

Stroke volume/end diastolic volume x 100

Ejection fraction is the volumetric fraction of blood ejected by the ventricle with each contraction - it is commonly given as a percentage

Question 5

How do you calculate mean arterial pressure and how is it defined?

Answer 5

Can be estimated using this equation:
MAP = DP + 1/3 (SP-DP)

MAP is an average arterial blood pressure throughout a single cardiac cycle of systole and diastole

Question 6

In health, a MAP of what represents the pressure necessary to adequately perfuse the body organs?

Answer 6

> 65 mmHg

Question 7

What happens to the MAP during exertion and what formula is more suitable to use to calculate it?

Answer 7

Moves more closely toward an average of SP and DP

MAP = (CO x systemic vascular resistance) + central venous pressure

Question 8

What is infective endocarditis?

Answer 8

An infection of the endocardium (inner lining) or vascular endothelium of the heart

Question 9

What does endocarditis typically affect?

Answer 9

Heart valves

Question 10

What causes infective endocarditis?

Answer 10

Usually the result of bacteria entering the bloodstream and forming a vegetation ( arterial infection surrounded by a layer of platelets and fibrin) in the endocardium

Question 11

What bacterial genus accounts for 20-40% of infective endocarditis cases?

Answer 11

Streptococcus

Question 12

Infection by which bacterial genus is an indication for surgery in infective endocarditis?

Answer 12

Staphylococcus

Question 13

What are the common symptoms of infective endocarditis?

Answer 13

Fever
Malaise
Sweats
Unexplained weight loss

Question 14

What may be present on examination and investigations in infective endocarditis?

Answer 14

Blood tests - anaemia, raised infection markers
Blood cultures - may isolate a microorganism
Echocardiogram - vegetation, abscess, valve perforation and/or new dehiscence of prosthetic valve
Often there is regurgitation of affected valve

Question 15

What type of echocardiogram is more sensitive for infective endocarditis?

Answer 15

Transoesophageal echo has higher sensitivity than transthoracic

Question 16

What features of heart decompensation would you look in infective endocarditis?

Answer 16

Symptoms:
- Shortness of breath
- Frequent coughing
- Swelling of the legs and abdomen
- Fatigue
Clinical signs:
- Raised JVP
- Lung crackles
- Oedema

Question 17

What are some other complications of infective endocarditis?

Answer 17

Vascular and embolism phenomena:
- Stroke
- Janeway lesions
- Splinter/conjunctival haemorrhages
Immunological phenomena:
- Osler’s nodes
- Roth spots (retinal haemorrhages)

Question 18

Which heart valve is most commonly affected by infective endocarditis and how does infection affect the valves?

Answer 18

Aortic valve (then mitral, then right-sided heart valves)
Formation of vegetation results in changes to valve thickness or a failure in their ability to open/close appropriately (e.g. regurgitation)

Question 19

Why are heart valves most commonly affected in infective endocarditis?

Answer 19

More common for bacteria to attach to the endocardium if underlying damage is present and this occurs more frequently at sites of turbulent flow (such as the valves)

Question 20

Why are IV drug users at an increased risk of infective endocarditis?

Answer 20

Repeated injections - exposure to bacteria on skin surface/non-sterile needles

Question 21

How does infective endocarditis differ in IV drug users?

Answer 21

Typically have right-sided heart effects - tricupsid valve typically affected (unlike aortic in general population) as it is the first valve to encounter the bacteria

Question 22

Infective endocarditis can be a complication of which type of surgeries?

Answer 22

Routine surgeries, e.g. dental surgery

Question 23

Infective endocarditis is more common in which other individuals?

Answer 23

Immunosuppressed individuals
Individuals with congenital heart defects leading to damaged endocardium

Question 24

What is the definition of dilated cardiomyopathy and what would show on an echo?

Answer 24

Dilated cardiomyopathy is characterised by dilated and thin-walled cardiac chambers with reduced contractility

Echo shows dilated left ventricle with reduced systolic function (EF) and typically global hypokinesis

Question 25

What are the most common causes of dilated cardiomyopathy?

Answer 25

Idiopathic
Genetic
Toxins (alcohol, illicit drugs, cardiotoxic chemotherapy)
Pregnancy (peripartum cardiomyopathy)
Viral infections (myocarditis)
Tachycardia-related cardiomyopathy
Thyroid disease
Muscular dystrophies

Question 26

How is dilated cardiomyopathy managed?

Answer 26

Medical heart failure therapy:
- ACEi
- Beta blockers
- Mineralcorticoid receptor antagonists
- SGLT2 inhibitors
Diuretics for fluid overload
Anticoagulation for atrial fibrillation
Cardiac devices:
- Cardiac resynchronisation therapy and/or implantable cardioverter defibrillator
Transplant

Question 27

What are the implications of dilated cardiomyopathy?

Answer 27

Risk of heart failure hospitalisation
Cardiac arrhythmias
Sudden cardiac death due to ventricular arrhythmia
Reduced survival