Valvular disease and Heart failure Flashcards
How do you calculate cardiac output?
Cardiac output is the volume of blood the heart pumps in one minute. Frequently given in Litres/minute (but can be also cm3/min)
cardiac output (CO) = heart rate (HR) x stroke volume (SV)
How do you calculate stroke volume?
SV = end diastolic volume (EDV) – end systolic volume (ESV)
How do you calculate ejection fraction?
ejection fraction (EF) = stroke volume (SV) / end diastolic volume (EDV) x 100
Ejection fraction is the volumetric fraction of blood ejected by the ventricle with each contraction. It is commonly given as a percentage (hence multiplication by 100)
How do you calculate mean arterial pressure?
mean arterial pressure (MAP) = (Cardiac output (CO) x systemic vascular resistance (SVR)) + central venous pressure (CVP)
However at normal resting heart rates MAP can be estimated using systolic and diastolic pressures using the following equation. MAP = Diastolic pressure (DP) + 1/3 (Systolic pressure (SP) – DP). MAP = DP + 1/3(SP-DP).
What is mean arterial pressure?
the mean arterial pressure is an average arterial blood pressure throughout a single cardiac cycle of systole and diastole. In health, a MAP >65 mmHg represents the pressure necessary to adequately perfuse the body organs. The estimation of MAP is useable at rest but during exertion (at high heart rate) MAP moves more closely toward an average of SP and DP
What is infective endocarditis?
infective endocarditis is an infection of the endocardium or vascular endothelium of the heart
ENDO (inner lining), CARD (heart) ITIS (inflammation). Typically affects the heart valves. It is usually the result of bacteria entering the blood stream and forming ”a vegetation” (a bacterial infection surrounded by a layer of platelets and fibrin) in the endocardium. Streptococci (20-40 % of cases) are the most common infection.
How do you diagnose infective endocarditis?
Fever, malaise, sweats and unexplained weight loss are common symptoms
There may be a new heart murmur on examination
Blood tests show anaemia and raised markers of infection
Blood cultures may isolate a microorganism
Echocardiogram can show a vegetation, abscess, valve perforation and/or new dehiscence of prosthetic valve. Often there is regurgitation of the affected valve
Transoesophageal echo has higher sensitivity compared with transthoracic
What is decompensation?
Inability of the heart to maintain adequate circulation.
What features of decompensation would you look for?
Cardiac decompensation
Symptoms include shortness of breath, frequent coughing, swelling of the legs and abdomen, fatigue
Clinical signs include raised JVP, lung crackles and oedema
Other complications: Vascular and embolic phenomena (stroke, Janeway lesions, splinter/ conjunctival haemorrhages) Immunological phenomena (Osler’s nodes, Roth spots)
What part of the heart does infective endocarditis typically affect?
Infective endocarditis affects the endocardium, especially the valves of the heart
Aortic valve is affected most frequently (aortic > mitral > right-sided valves)
Explain why infective endocarditis typically affects these areas?
The formation of a vegetation at the valves of the heart either results in changes to their thickness or a failure in their ability open and close appropriates. It is more common for bacteria to attach to the endocardium if underlying damage is present, and this occurs more frequently at sites of turbulent blood flow such as the valves of the heart.
Why are intravenous drug users at greater risk of infective endocarditis?
Intravenous drug users are at increased risk of infective endocarditis due to repeated injection – potentially exposing their bloodstream to bacteria on the surface of the skin or use of non-sterile needles
What is the first step in infective endocarditis?
Entry of bacteria into the blood stream is first and critical step in infective endocarditis. Increased risk of infective endocarditis is therefore seen in I.V. drug users, but also a complication of routine surgeries such as dental surgery. It is also more common in individuals that are immunosuppressed or have congenital heart defects leading to damaged endocardium.
What is hypokinesia?
a state of the body in which insufficient motor activity is observed, which leads to a limitation of the pace and range of movements
