Lecture 4: failing heart Flashcards by Nienke Schouten

Describe the pressure-volume loop of the heart

End-systolic volume means lowest pressure and volume; mitral valve opens
Ventricles fill but pressure stays the same
End-diastolic volume, mitral valve closes
Isovolumetric contraction
Aortic valve opens, ventricular ejection
Aortic valve closes, isovolumetric relaxation

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What factors determine the size of an infarct?

The size of the area at risk
Level of collateral flow
Duration of ischaemia
Rate of cell death

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What is the benefit of ischaemic preconditioning?

Slows down the rate at which cells die

Ischaemia for short time, re-perfusion, ischaemia etc etc until you have a longer pathological period of ischaemia

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In ischaemic injury, how can cells survive for a prolonged period of time?

High levels of anaerobic ATP

After around 10 minutes, glycogen runs out and ATP levels drop and cells will start to die and apoptise

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How do biomarkers for ACS develop?

When the cardiac cell membrane ruptures soluble proteins leak out into the circulation. Circulating cardiac-specific proteins such as troponin (cTnI and cTnT) or cMyC used as biomarkers for the number of myocytes killed (infarct size)

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Explain the progression of an infarct

Subendocardial area first
“Wavefront” of death spreads transmurally toward the epicardium
- > After 3 hours, all necrotic tissue has developed
The transmural wave spreads

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When is interventiion during ACS useful?

In the first 2-3 hours, afterwards there is very little benefit

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What are the main causes of heart failure?

Pressure overload
Volume overload
Contractile dysfunction

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What can cause pressure overload?

Hypertension

- Aortic stenosis

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What can cause volume overload?

Aortic and mitral valve regurgitation

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What can cause contractile dysfunction?

Ischaemic heart disease
Myocardial infarction
Pregnancy
Inherited or acquired cardiomyopathies

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What are the main types of inherited cardiomyopathies?

Dilated cardiomyopathy (problem with cytoskeletal proteins)
Hypertrophic cardiomyopathy (problems with sarcomeric proteins)
Arrythmogenic right ventricular cardiomyopathy (problems with desmosomal proteins)

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What are the symptoms of mitral stenosis?

Palpitations
Murmurs
Dyspnoea
Heart failure

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What are the symptoms of aortic stenosis?

Chest pain
Murmurs
Dyspnoea
Heart failure

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What are the symptoms of mitral regurg?

Murmurs
Dyspnoea
Heart failure

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What are the symptoms of aortic regurg?

Murmurs
Dyspnoea
Heart failure

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What is the main cause of mitral stenosis?

Rheumatic heart disease

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What is the main cause of aortic stenosis?

Calcification

Old age

What is the main cause of mitral regurg?

Old age

What is the main cause of aortic regurg?

Idiopathic
Marfan’s
Ehlers Danloss

What cardiac remodeling changes happen in heart failure?

LV remodelling
Cellular changes
Myocyte death
Disruption of extracellular matrix
Reduced perfusion of myocytes

How is diastolic heart failure defined?

Diastolic HF is defined as heart failure in which the ejection fraction is >40%.

It’s often referred to as HF with preserved ejection fraction

What cardiac benefits does ACE-I have?

↓ symptoms (exercise intolerance, oedema)
Slow progression of disease
Lengthen survival, ↓ hospitalisation

What are the side effects of ACE-Is?

Chronic cough
Hypotension
renal failure
Hyperkalaemia

What are the contraindications for ACE-I?

1. Renal failure 2. Bilateral renal stenosis 3. Angioedema 4. Pregnancy

What cardiac benefits do ß-blockers have?

- Prolong survival - ↓ sudden death by ventricular fibrillation (which accounts for ~50% of CHF mortality) - ↓ symptoms of HF - ↓ cardiac remodelling, ↓ renin release so inhibit the RAAS

What cardiac benefits does spironolactone have?

- ↓ mortality in severe HF when added to standard therapy | - ↓ fibrosis/remodelling of heart

How does digoxin work?

Positive inotropes; increase myocyte [Ca2+] by blocking the Na+ pump, this increases intracellular [Na+] which reduces Ca2+ extrusion by the Na+/Ca2+ exchanger.

What do you do in digoxin toxicity?

Treat toxicity with digibind, a digoxin antibody fragment.

What is the mechanism of action of ivabradine?

Ivabradine lowers HR by blocking the ‘funny current’ in the SA node.

How do diuretics help in heart failure?

A mainstay of CHF treatment because they ↓preload, oedema and dyspnoea, ↑exercise capacity. Loop diuretics mainly used for CHF; thiazide-like diuretic can be added if oedema is not sufficiently controlled

What are the adverse effects of diuretics?

Key side effects: Loop diuretics and thiazides can cause excess K+ loss→ arrhythmias; also hypotension. Hypokalaemia is ameliorated by spironolactone, ACEI, ARBs, ENaC blockers (e.g. amiloride) or K+ supplements

What is cardiorenal syndrome?

Heart failure leads to acute or chronic renal dysfunction Close monitoring of renal function and plasma electrolytes is essential, watch out for hyperkalaemia

What is the NYHA heart failure classification?

1. Cardiac disease, but no symptoms and no limitation in ordinary physical activity 2. Mild symptoms and slight limitation in ordinary physical activity 3. Signification limitation in ordinary physical activity due to symptoms, comfortable only at rest 4. Severe limitations, symptoms even at rest

What are the modes of death in heart failure?

1. Progressive (Progressive multi-organ failure as a result of heart failure) 2. Sudden (often hypertrophic cardiomyopathy leading to VF)

What is a first degree heart block?

Increased PR interval (normal limit is 120-200 ms) Usually no symptoms

What is a Mobitz 1 heart block?

Increasing PR interval until P wave is not followed by a QRS complex Most patients do not have symptoms, would treat if symptomatic

What is a Mobitz 2 heart block?

Dropped QRS complexes and PR prolongations are unpredictable More serious than Mobitz 1; suggests the block is often further down the His bundle Only treat if symptomatic, but is often symptomatic

What is a complete heart block?

Complete dissociation between P wave and QRS complex Morphologically, P wave and QRS complex look normal Leads to severe bradycardia

How would you treat symptomtic bradycardia?

Pacemaker Pass trough subclavian vein; Wire in right ventricle and right atrium

What are the 5 causes of ventricular arrhythmias?

1. Ischaemia (most common) 2. Cardiomyopathy 3. Drugs 4. Electrolyte disturbance 5. Congenital cardiac abnormality

What can VT lead to?

Can cause haemodynamic compromise, however can be compatible with standing up and talking IF haemodynamically compromised → SHOCK

What is an ICD?

Implantable cardioverter defibrillator When it senses a VT, the device will try to eliminate the VT. If this is unsuccessful, it will shock

Who would benefit from cardiac resynchronisation therapy?

Benefit to people with LVEF <35%, LBBB, those with heart failure symptoms