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3 CVS > 18 Heart Failure > Flashcards

18 Heart Failure Flashcards

1
Q

define heart failure

A

the inability of the heart to supply adequate blood flow and therefore oxygen delivery to peripheral tissues and organs

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2
Q

What is the most common cause of heart failure?

A

post MI

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3
Q

What happens to myocardium which does not receive blood flow?

A 
hypoxia
hypercapnia
glycolytic and acidotic
nutrient depletion
risk of necrosis
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4
Q

How does a myocardial infarct occur?

A

fibro-fatty plaques may rupture, releasing substances activating platelets

thrombus forms

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5
Q

How is ischaemia visible on an ECG?

A

elevation of ST segment

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6
Q

How is an MI treated acutely?

A

PCI

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7
Q

What happens in a PCI?

A 
catheter inserted into peripheral artery
goes to aorta - coronary vessel
punches through thrombus
balloon inflated
stent fitted
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8
Q

How quickly after the MI do you want to do a PCI?

A

2 hours

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9
Q

What is a PCI?

A

Percutaneous Coronary Intervention

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10
Q

If you do nothing to treat an MI, how much of that area will die?

A

70%

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11
Q

If you perform a PCI, how much of the area will die?

A

30%

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12
Q

Why does a PCI not reduce ischaemia to 0%?

A

the act of re-introducing blood flow itself is detrimental to the heart (release of ROS)

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13
Q

What might cause HF by pressure overload?

what is the trigger here?

A

HTN
aortic stenosis

pathological hypertrophy against a higher after-load

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14
Q

What might cause HF by contractile dysfunction?

A

ischaemic heart disease

congenital cardiomyopathies

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15
Q

what happens in ischaemic heart disease?

A

reduced blood flow to cardiomyocytes

don’t function as well

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16
Q

What happens to SV in HF?

A

the peak and magnitude of SV are lower

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17
Q

What is the effect of decreased SV on baroreceptor reflex?

A

decreases it

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18
Q

How can a decreased baroreceptor reflex increase HR?

A

decreased vagal and increased symp tone to SA node

19
Q

How can a decreased baroreceptor reflex increase heart contractility?

A

increased symp activity to ventricular muscle

20
Q

How does an increase in contractility increase CO?

A

increases SV

21
Q

What happens in pathological hypertrophy?

A

cardiomyocytes enlarge
lose their shape
distance between capillaries and cardiomyocytes increases

22
Q

how does the baroreceptor reflex interact with the adrenal gland?

what is the clinical significance of this?

A

a decreased reflex increases catecholamine release

the increase in serum adrenaline is measurable

23
Q

What are the consequences of persistent adrenargic stimulation of the heart?

A

hyperphosphorylation of Ca2+ handling proteins

pathologcial hypertrophy

beta adrenoreceptor internalisation

24
Q

Why is hyperphosphorylation of Ca2+ a problem?

A

leads to…
dysfunctional Ca2+ homeostasis
contractile dysfunction
arrhythmia

25
Q

What sort of arrhythmia might we expect in HF?

A

delayed afterdepolarisation

DAD

26
Q

What happens in DAD?

A

spontaneous release of SR calcium during diastole

27
Q

How does calcium release cause DAD?

A

calcium removed by 3Na+ / Ca2+ transporter, so depolarises membrane

28
Q

How can DAD be made worse?

A

persistent stimulation - upregulation of PKA

hyperphospharylation of ryanodine receptor, making the SR more leaky

29
Q

What might be used to treat DAD?

How might they work?

A

beta-blockers

calcium channel blockers reduce SR Ca2+ load, making it less leaky

30
Q

How does a low ABP increase renin release?

A

increased sympathetic activity to kidney (baroreceptor)

decreased wall tension in renal afferent arterioles

decreased Na+ delivery to macula densa

31
Q

how does a reduction in cardiomyocyte function alter ABP?

A

decreases stroke volume

reduces ABP

32
Q

How does angiotensin II increase water intake?

A

increases thirst drive via hypothalamus

33
Q

How does angiotensin II increase water reabsorption?

A

ADH

Aldosterone

34
Q

What effect does angiotensin II have on blood volume?

A

it increases it

35
Q

Why is it important that we are able to increase EDV?

A

it helps us to maintain SV

36
Q

What are the consequences of blood volume loading?

A

persistent loading causes them to go beyond the plateau of the Starling curve and SV can no longer be sustained

37
Q

how does oedema occur in HF?

A

mismatch in LV and RV CO due to HF

38
Q

Why do lungs not accumulate fluid in normal pulmonary circulation?

A

because we are constantly breathing humidified air

39
Q

How does left HF cause pulmonary oedema?

A

increased hydrostatic pressure in pulmonary circulation

40
Q

What are the effects of pulmonary oedema?

A

increased diffusion distance
arterial hypoxia
dyspnea
peripheral chemoreceptor activation

41
Q

What can hypoxia in the lung lead to?

A

hypoxic pulmonary vasoconstriction

pulmonary HTN

42
Q

How can you overcome pulmonary hypoxia acutely?

A

delivering 100% O2

43
Q

How might you treat pulmonary oedema chonically?

A

loop diuretics
ACEi
AT1R antagonists

44
Q

What is the effect of cardiac hypertrophy?

A

increases suceptibility to ischaemia
increases incidence of arrhythmias
increases incidence of sudden death

3 CVS (24 decks)

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