Cardiac Failure Flashcards
What is cardiac failure?
Cardiac output less than body needs
What is the normal cardiac output?
5-6 L/min
What is the normal stroke volume?
70 ml/beat
What is high output cardiac failure?
Failure due to increased body needs - Anaemia - Severe aortic regurgitation - Thyrotoxicosis - Fever - AV fistulae Rare
What is usually reduced in cardiac failure: systolic or diastolic function?
Systolic - low ejection fraction
At what ejection fraction do you usually get symptoms of cardiac failure at?
30-40%
What is the ejection fraction in stiff diastolic function causing cardiac failure?
Normal
What is preload?
Venous return
What is contractility?
Strength of pump
What is afterload?
Resistance against which heart must pump
Why should you check the JVP before giving a cardiac failure patient fluid for low blood pressure?
Danger in giving a person with high preload more fluid
How can preload be clinically determined?
Right heart: JVP
Left heart: pulmonary venous pressure = PA wedge pressure
What does an increase in venous pressure mean?
Fluid leaks out
Oedema
What are some signs of right heart failure?
High JVP
Peripheral oedema
Hepatic congestion
What are the causes of oedema?
Increased venous pressure
Decreased osmotic pressure
Blocked lymphatics
Increased capillary permeability
What can cause a decreased osmotic pressure?
Plasma protein loss
- Renal failure
- Liver failure
What can block lymphatics?
Cancer
What can cause increased capillary permeability?
Infection
Where is the oedema if there is increased pulmonary venous pressure, affecting the left atrium?
Pulmonary congestioon
Pulmonary oedema
Where is the oedema if there is increased systemic venous pressure, affecting the right atrium?
Peripheral congestion
Peripheral oedema
Why and how is preload increased in cardiac failure?
Decreased contractility > decreased cardiac output
To bring cardiac output to normal > Na and fluid retention
What is the mechanism for fluid retention in cardiac failure?
Decreased cardiac output > decreased renal blood flow > activation of renin-angiotensin-aldosterone system (RAAS) >
- Fluid and Na retention
- K loss
- Vasoconstriction
What does the sympathetic nervous system do in cardiac failure?
Increased noradrenaline Initial increased contractility Long-term deleterious effects - Vasoconstriction - Ventricular arrhythmias - Direct toxic effect
What does it mean if you find both swollen ankles and sacral oedema?
Like paroxysmal nocturnal dyspnoea (PND) is to orthopnea - need to be admitted to hospital for treatment
Why is orthopnoea specific for cardiac failure?
When standing most of fluid in lower part of lungs, so able to use upper part of lungs
When lying down, more alveoli involved
For other causes of shortness of breath, there is no effect of gravity on lungs
What are the examination findings for cardiac failure?
Crackles on chest examination
- Could be cardiac/respiratory cause
- If respiratory, may improve on coughing
JVP elevated
- Indicates high right atrial pressure, and thus, right ventricular end diastolic pressure
- Often correlates with high left atrial pressure
Oedema
What are the investigations for cardiac failure?
CXR - Heart size > make sure using erect PA film - Lung fields, looking for - Pleural effusion - Kerley B lines - Perihilar batwing shadowing - Fluffy alveoli Echocardiogram - Chamber size and function - Valves - Structure
What are the causes of cardiac failure?
Ischaemic heart disease: MI - Vast majority of cases Valvular heart disease - Common Hypertension Congenital heart disease Cardiomyopathy Cor pulmonale Pericardial disease; eg: Coxsackie virus
Can the JVP be elevated but the pulmonary venous pressure be normal?
In pure right heart failure
Rare
What are the causes of right heart failure?
Pulmonary hypertension - Cor pulmonale - Pulmonary embolism Right sided structural disease - Pulmonary/tricuspid valves - Right ventricular cardiomyopathy Pericardial disease
What is cor pulmonale?
Heart failure due to lung diseases?
What lung diseases can cause cor pulmonale?
COPD
Cystic fibrosis
Pulmonary fibrosis
What is the cardinal symptom of left heart failure?
Shortness of breath
What is the cardinal sign of left heart failure?
Lung crepitations
What is the classification of left heart failure based on ejection fractions?
Mild = 40-50%
Moderate = 30-40%
Severe <30%
What are the possible causes of diastolic heart failure?
Stiff ventricle - poor compliance
- Infarct-related scar
- Chronic hypertension
- Ventricular hypertrophy
What are the principles of treatment for heart failure?
Reduce venous pressure
- Relieves congestion and oedema
- But without reducing cardiac output too much
Block RAAS
- Produces long-term fluid loss and vasodilatation
Block sympathetic nervous system
- Block direct cardiac toxic effects of beta stimulation
Treat underlying and precipitating causes
What are the medications used in the treatment of cardiac failure?
Duiretics; eg: frusemide
Aldosterone antagonists; eg: spironolactone
ACE inhibitors and/or angiotensin receptor antagonists (ARBs)
Beta blockers
- Use cardioselective if possible
What additional treatment is there available for cardiac failure?
Biventricular pacing
- Improves cardiac function
Implantable cardioverter defibrillator
- Because ventricular arrhythmias and sudden death common in heart failure
Cardiac assist devices and transplantations
- For small group who don’t respond to other treatment
- Not usually appropriate for elderly patients
