Valvular Disease and Heart Failure Tutorial Flashcards
How do you calculate cardiac output?
How do you calculate stroke volume?
Cardiac Output = Stroke volume x Heart rate
Stroke Volume = End Diastolic Volume - End Systolic Volume
How do you calculate ejection fraction?
Ejection Fraction = Stroke Volume / End Diastolic Volume
How do you calculate mean arterial pressure?
Cardiac Output x Total Peripheral Resistance
OR
Diastolic pressure + 1/3 pulse pressure
Simplified to: 2/3 diastolic pressure + 1/3 systolic pressure
What is the cardiac output, ejection fraction, stroke volume, and mean arterial pressure for the below case:
60M = shortness of breath in A+E. In type 2 respiratory failure secondary to an infectious exacerbation of COPD
End diastolic volume = 142ml
End systolic volume =47 ml
He was intubated and ventilated using BiPAP of 20/5 with:
Sats = 95% Heart rate = 75 beats per minute Respiratory rate 12/minute Blood pressure 115/75mmHg Temperature = 36.5 degrees Celsius
Cardiac Output: 75 x (142-47) = 7125 mL/min or 1.725 L/min
Ejection Fraction:
(142-47) / 142 x 100 = 66.9%
Stroke Volume:
142-47 = 95mL
MAP:
2/3 (75) + 1/3 (115) = 88.3 mmHg
21M - presents to A+E with pyrexia (fever) of unknown origin. Known IV heroin user
On examination: Heart rate = 115 beats per minute Blood pressure = 90/60mmHg Temperature = 39 degrees Celsius Respiratory rate = 17 beats per minute Sats = 99 percent on air
Early diastolic murmur in the left sternal edge which is loudest with the patient sitting forward and at end expiration.
Cellulitis of his distal right leg with a deep penetrating ulcer
What is infective endocarditis?
Which bacterial infection is most common
Infection of the endocardium - infection that is caused by bacteria, which enters the blood stream and settles in the heart lining, a heart valve or a blood vessel
Often forms a vegetation (bacteria infection surrounded by a layer of platelets) in the endocardium
Streptococci = most common
How do you diagnose infective endocarditis?
Use Duke’s criteria
Fever, malaise, sweats and unexplained weight loss = common symptoms
Blood test - inflammatory markers/infection and anaemia
Blood cultures - isolate microorganism to decide which antibiotic it’s most sensitive to
Heart murmurs - from infected heart valves
Echo - can show vegetation, thickening of heart valves, valve perforation, abscess etc. Often there is regurgitation in the infected valve
ECG - check of normal heart rhythm
What is the Duke’s criteria for infective endocarditis?
Which of the criteria are required for a diagnosis of endocarditis?
Major =
At least 2 positive blood cultures for infective endocarditis
Echo shows vegetation, dehiscence of prothestic valve, abscess
Evidence of endocardial involvement:
New valvular regurgitation murmur
Coxiella burnetti infection
Minor =
Predisposing heart condition or IV drug use
Fever >38 degrees
Vascular phenomena - emboli, infarcts, aneurysms etc.
Immunological phenomena - glomerulonephritis, rheumatoid factor etc.
Microbiological evidence - serological evidence of active infection etc.
For diagnosis the requirement is:
2 major and 1 minor criteria or
1 major and 3 minor criteria or
5 minor criteria
What features of decompensation would you look for?
Cardiac decompensation:
Shortness of breath, frequent coughing, swelling of the legs and abdomen, fatigue
Pitting oedema, lung crackles, fluid in the lungs, raised JVP
Vascular and embolic phenomena - stroke, lesions, conjunctival haemorrhages
Immunological phernomena - Osler’s nodes, Roth spots
Which part of the heart does infective endocarditis affect?
Affects endocardium:
Heart valves most common - normally left aortic > mitral valve > right sided valves
Valves most common as the bacteria can settle where there is turbulent flow
Heart lining
Vessels supplying the heart
How does this vary for intravenous drug users?
Frequent injections - may not be sterile = more likely to introduce and expose bacteria on the skin into the bloodstream
Drug taken may affect immune system / treatment
25M = presents with palpitations and syncope episodes
24hr Holter monitor showed patient was in fast atrial fibrillation for up to 6 hours in the 24hr recording
A transthoracic echocardiogram showed hypokinesia in the inferolateral walls
He ended up having a cardiac MRI which confirmed the diagnosis of dilated cardiomyopathy
What is the definition of dilated cardiomyopathy?
Dilation of the ventricles (walls stretch and thin)
Dilated and thin-walled cardiac chambers = reduced contractility
Lowered ejection fraction (this is contractility marker)
What are the commonest causes of dilated cardiomyopathy?
Heart disease Poorly controlled hypertension Endocrine Autoimmune Metabolic disorders Idiopathic Genetic Toxins - alcohol, cardiotoxic chemotherapy Pregnancy - peripartum cardiomyopathy Viral infections - myocarditis Tachycardia-related cardiomyopathy Thyroid disease Muscular dystrophies
What genes have been implicated in the diagnosis of dilated cardiomyopathy?
Mutations in genes encoding cytoskeletal proteins e.g. titin, phospholamban, cardiac myosin binding protein C, myosin heavy chain
TTN gene ACPC I ACPC II Genes coding for myosin and actin DEF - structural genes
How is the condition managed?
Lifestyle changes - stress management
Manage coagulation - anti-coagulants
Manage irregular heart rate - beta blockers
Manage BP - ACE inhibitors, angiotensin II receptor blockers, diuretics
Medical heart failure therapy = mineralcorticoid receptor antagonists, ACE inhibitors, beta-blockers
Cardiac devices - cardiac resynchronisation therapy and/or implantable cardioverter defibrillator
Transplant
What will be the implications on this gentleman in the future?
High risk of heart failure hospitalisation, cardiac arrhythmias, sudden cardiac death due to ventricular arrhythmia, and reduced survival
Needs to manage BP
