1b Valvular Disease and Heart Failure Flashcards
How do you calculate Cardiac Output?
Cardiac Output = SV x Heart Rate
How do you calculate Stroke Volume?
End Diastolic Volume - End Systolic Volume
What is the units of cardiac output?
Litres/minute
How do you calculate the ejection fraction?
(Stroke volume / End Diastolic Volume ) x 100
The ejection fraction is the volumetric fraction of blood which is ejected from the ventricle per contraction
How you do calculate Mean Arterial Pressure?
MAP = (CO x Systemic Vascular Resistance) + Central Venous Pressure
MAP = DP + 1/3(SP-DP)
What is the mean arterial pressure?
the mean arterial pressure is an average arterial blood pressure throughout a single cardiac cycle of systole and diastole.
What MAP represents a pressure necessary to adequately perfuse the body organs?
MAP of >65 mmHg
What is infective endocarditis?
infective endocarditis is an infection of the endocardium or vascular endothelium of the heart
What does infective endocarditis typically affect?
Heart valves
What causes infective endocarditis?
It is usually the result of bacteria entering the blood stream and forming ”a vegetation” in the endocardium
What is a heart vegetation?
a bacterial infection surrounded by a layer of platelets and fibrin
What is the most common bacteria for infective endocarditis?
Streptococci (20-40 % of cases) are the most common infection.
What are the common symptoms of infective endocarditis?
Fever, malaise, sweats and unexplained weight loss are common symptoms
There may be a new heart murmur on examination
What might blood tests show in a patient with infective endocarditis?
Blood tests show anaemia and raised markers of infection
Blood cultures may isolate a microorganism
Which ECHO has the higher sensitivity, Transoesophageal or Transthoracic?
Transoesophageal
What might an ECHO show in a patient with infective endocarditis?
Echocardiogram can show a vegetation, abscess, valve perforation and/or new dehiscence of prosthetic valve. Often there is regurgitation of the affected valve
What is decompensation?
Inability of the heart to maintain adequate circulation
What are signs of cardiac decompensation you might look for?
Symptoms include shortness of breath, frequent coughing, swelling of the legs and abdomen, fatigue
Clinical signs include raised JVP (Jugular Venous Pressure), lung crackles and oedema
What are the minor criteria in Duke’s Criteria for infective endocarditis?
Predisposing heart condition
Fever >38
Vascular - emboli to organs, brain
Glomerulonephritis, Oslers nodes, Roth Spots
Positive cultures
What are the major criteria in Duke’s Criteria for infective endocarditis?
Persistently positive bacterial culture
ECHO = vegetation, abcess
New valvular regurgitation murmur
Coxiella Burnetti infection
What part of the heart does infective endocarditis affect?
Infective endocarditis affects the endocardium, especially the valves of the heart
Aortic valve is affected most frequently (aortic > mitral > right-sided valves)
Why infective endocarditis occur more commonly at the Aortic valve?
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 might drug users have an increased risk of infective endocarditis?
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 definition of dilated cardiomyopathy?
dilated cardiomyopathy is characterised by dilated and thin-walled cardiac chambers with reduced contractility
What are the commonest causes of dilated cardiomyopathy?
Idiopathic, genetic, toxins (alcohol, cardiotoxic chemotherapy), pregnancy (peripartum cardiomyopathy), viral infections (myocarditis), tachycardia-related cardiomyopathy, thyroid disease, muscular dystrophies
How is dilated cardiomyopathy managed?
Medical heart failure therapy - ACE inhibitors, beta-blockers, mineralocorticoid receptor antagonists
Diuretics for fluid overload
Anticoagulation for atrial fibrillation
Cardiac devices – cardiac resynchronisation therapy and/or implantable cardioverter defibrillator
Transplant
What are the future implications of dilated cardiomyopathy?
Increased risk of heart failure, cardiac arrhythmia, sudden cardiac death due to ventricular arrhythmia and reduced survival
How is STEMI treated?
Antiplatelet and add-on anti-ischemic/anticoagulant treatment
Alternative only if PCI unavailable Thrombolysis ( if within the window) or rescue PCI if thrombolysis fails or CABG
Long-term management( antiplatelet therapy, statin, b-blocker, ACE inhibitor, cardiac rehabilitation and lifestyle changes)
What are the ECG findings for NSTEMI?
ST Depression
T wave inversion
What is an NSTEMI?
- Incomplete thrombus formation.
- This does not stop blood and oxygen completely but the restriction is so great that the oxygen content is used up quickly and, in the distal arteries and arterioles,
- tissue death occurs as a result of oxygen starvation.
- The area affected is small, not enough to cause ST elevation but enough to cause minor ST/T wave changes (see earlier examples) and Troponin elevation.
What is an unstable angina?
Plaque becomes unstable, fibrous cap disrupts and thrombus is formed but still enough lumen to meet the demand during rest
What is the difference in diagnosis of NSTEMI and unstable angina?
In NSTEMI there is myocyte necrosis, therefore this will show up on enzyme and biomarker tests
