Valvular Disease & Heart Failure Flashcards
Label this diagram of the heart
How do you calculate cardiac output and how is it defined (with units)?
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
How do you calculate stroke volume?
End diastolic volume - end systolic volume
How do you calculate the ejection fraction and how is it defined?
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
How do you calculate mean arterial pressure and how is it defined?
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
In health, a MAP of what represents the pressure necessary to adequately perfuse the body organs?
> 65 mmHg
What happens to the MAP during exertion and what formula is more suitable to use to calculate it?
Moves more closely toward an average of SP and DP
MAP = (CO x systemic vascular resistance) + central venous pressure
What is infective endocarditis?
An infection of the endocardium (inner lining) or vascular endothelium of the heart
What does endocarditis typically affect?
Heart valves
What causes infective endocarditis?
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
What bacterial genus accounts for 20-40% of infective endocarditis cases?
Streptococcus
Infection by which bacterial genus is an indication for surgery in infective endocarditis?
Staphylococcus
What are the common symptoms of infective endocarditis?
Fever
Malaise
Sweats
Unexplained weight loss
What may be present on examination and investigations in infective endocarditis?
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
What type of echocardiogram is more sensitive for infective endocarditis?
Transoesophageal echo has higher sensitivity than transthoracic
What features of heart decompensation would you look in infective endocarditis?
Symptoms:
- Shortness of breath
- Frequent coughing
- Swelling of the legs and abdomen
- Fatigue
Clinical signs:
- Raised JVP
- Lung crackles
- Oedema
What are some other complications of infective endocarditis?
Vascular and embolism phenomena:
- Stroke
- Janeway lesions
- Splinter/conjunctival haemorrhages
Immunological phenomena:
- Osler’s nodes
- Roth spots (retinal haemorrhages)
Which heart valve is most commonly affected by infective endocarditis and how does infection affect the valves?
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)
Why are heart valves most commonly affected in infective endocarditis?
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)
Why are IV drug users at an increased risk of infective endocarditis?
Repeated injections - exposure to bacteria on skin surface/non-sterile needles
How does infective endocarditis differ in IV drug users?
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
Infective endocarditis can be a complication of which type of surgeries?
Routine surgeries, e.g. dental surgery
Infective endocarditis is more common in which other individuals?
Immunosuppressed individuals
Individuals with congenital heart defects leading to damaged endocardium
What is the definition of dilated cardiomyopathy and what would show on an echo?
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
