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Module 103: Theme 3: Physiology of the cardiovascular system. Principles of pathology, diagnosis and treatment of cardiovascular disease > Heart failure > Flashcards

Heart failure Flashcards

1
Q

What is heart failure?

A

A state that develops when the heart fails to maintain an adequate cardiac output to meet the demands of the body

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2
Q

What causes heart failure?

A

Results from any structural or functional abnormality that impairs the ability of the ventricle to eject blood (systolic HF) or fill with blood (diastolic HF)

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3
Q

At rest in a typical adult what is normal cardiac output?

A

70mls/kg/min

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4
Q

List 3 factors which affect stroke volume

A

Contractility
Preload
Afterload

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5
Q

How does an increase in heart rate affect the cardiac output?

A

Causes an increase

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6
Q

In which phase does filling of the heart occur?

A

Diastole

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7
Q

In which phase does contraction of the heart occur?

A

Systole

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8
Q

What does excessive high heart rate cause?

A

Excessively high HR results in a decrease in the amount of time allowed for the ventricles to fill in diastole which causes SV and, thus CO to fall

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9
Q

Define contractility

A

The intrinsic ability of the myocardium to contract

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10
Q

What is preload?

A

The volume of blood or stretching of cardiomyocytes at the end of diastole prior to the next contraction

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11
Q

What is afterload?

A

The resistance/end load against which the ventricle contracts to eject blood

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12
Q

When does preload increase?

A

When there is an increase in blood volume and vasoconstriction

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13
Q

What decreases preload?

A

Blood volume loss and vasodilatation

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14
Q

What does the frank starling law state?

A

An increase in volume of blood filling the heart stretches the heart muscle fibres causing greater contractile forces which, in turn, increases the stroke volume
Is true only up to a certain point… at some stage the fibres become over-stretched and the force of contraction is reduced

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15
Q

What does vasodilatation do to afterload?

A

Decreases

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16
Q

What does hypertension and vasoconstriction do to afterload?

A

Increases

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17
Q

What happens to cardiac output as afterload increases?

A

Decreases

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18
Q

State the 2 types of low output heart failure

A

Systolic heart failure

Diastolic heart failure

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19
Q

What is high output heart failure?

A

Occurs in the context of other medical conditions which increase demands on cardiac output, causing a clinical picture of HF
The heart itself is functioning normally but cannot keep up with the unusually high demand for blood to one or more organs in the body

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20
Q

What can cause high output heart failure?

A

Thyrotoxicosis, profound anaemia, pregnancy, paget’s disease, acromegaly, sepsis

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21
Q

What is systolic heart failure?

A

Where the heart has become weak

Progressive deterioration myocardial contractile function

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22
Q

List 3 causes of systolic heart failure

A

Ischemic injury
Volume overload
Pressure overload

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23
Q

What is diastolic heart failure?

A

Inability of the heart chamber to relax, expand and fill sufficiently during diastole to accommodate an adequate blood volume

24
Q

List the causes of diastolic heart failure

A

Significant left ventricular hypertrophy (LVH) e.g HCM
Infiltrative disorders
Constrictive pericarditis
Restrictive cardiomyopathy

25
Q

State some other causes of heart failure

A 
Coronary Heart Disease
Hypertensive Heart Disease
Valvular Heart Disease
Myocardial Disease/ Cardiomyopathies
Congenital Heart Disease
26
Q

Define cardiomyopathy

A

Diffuse disease of the heart muscle leading to functional impairment

27
Q

List the 3 types of cardiomyopathy

A

Dilated cardiomyopathy
Hypertrophic cardiomyopathy
Restrictive cardiomyopathy

28
Q

Describe the pathophysiology of heart failure

A

Pump failure leads to reduced SV and CO. Compensatory mechanisms kick in to maintain arterial pressure and perfusion of vital organs

29
Q

List some compensatory mechanisms of heart failure and state what they do

A

The Frank Starling mechanism: vasoconstriction, increased venous return to the heart, increased preload, heart muscle fibres stretch, enhanced contractility
Myocardial structural change: Augmented muscle mass (hypertrophy) with or without cardiac chamber dilatation
Activation of neurohormonal system:
Release of Noradrenaline – increases heart rate and myocardial contractility. Causes vasoconstriction
Release of ANP/BNP
Activation of renin-angiotensin – aldosterone system

30
Q

What is the problem with compensatory mechanisms of heart failure?

A

They may worsen the heart failure

31
Q

What can pressure overload cause?

A

Concentric left ventricular hypertrophy
Augmented muscle may reduce the cavity diameter
Cross sectional areas of the myocytes are increased

32
Q

What can volume overload cause?

A

Chamber dilatation with increased ventricular pressure
Deposition of new sarcomeres
Increased cell length and width
Muscle mass and wall thickness are increased in proportion to chamber diameter

33
Q

Describe some clinical types of heart failure

A

Left sided, right sided and biventricular failure
Acute and chronic heart failure
Compensated and decompensated heart failure

34
Q

Describe left sided heart failure

A

Blood backs up progressively from the left atrium to the pulmonary circulation

35
Q

What are the causes of left sided heart failure?

A

Ischaemic heart disease
Hypertension
Valvular heart disease
Myocardial disease

36
Q

How does left ventricular failure affect the lungs?

A

Pressure in the pulmonary veins is transmitted retrogradely to the capillaries and arteries
This leads to pulmonary congestion and oedema

37
Q

What problems are caused by heavy/wet lungs from left ventricular failure?

A

Orthopnoea
Paroxysmal nocturnal dyspnoea
Dyspnoea

38
Q

How does left ventricular failure affect the kidneys?

A

Decreased cardiac output
Reduction in renal perfusion
Activation of renin - angiotensin – aldosterone system
Retention of salt and water with consequent expansion of interstitial fluid and blood volumes

39
Q

How does left ventricular failure affect the brain?

A 
Hypoxic encephalopathy
Irritability
Loss of attention
Restlessness
Stupor and coma
40
Q

Describe right sided heart failure and its causes

A

Right sided HF due to significant pulmonary hypertension due to increased resistance within the pulmonary circulation
Usually as a result of respiratory disease e.g. COPD or pulmonary emboli
Other causes:
Valvular heart disease
Congenital heart disease

41
Q

What causes biventricular failure (Congestive cardiac failure)?

A

Either due to the same pathological process on each side of the heart
OR
A consequence of left heart failure leading to volume overload of the pulmonary circulation and eventually the right ventricle causing right ventricular failure

42
Q

List the main clinical presentations of heart failure

A 
Dyspnoea
Orthopnoea, paroxysmal nocturnal dyspnoea
Oedema
Hepatic congestion
Ascites
Fatigue
Weakness
43
Q

Describe the new york classification of heart failure

A

Class I: No limitation of physical activity
Class II: Slight limitation of ordinary activity
Class III: Marked limitation, even during less-than-ordinary activity
Class IV: Severe limitation with symptoms at rest

44
Q

List the symptoms of acute pulmonary oedmea

A 
Acute Breathlessness
Pallor
Cyanosis
Sweating
Rapid Pulse
Hypoxia
Crackles in Lungs
45
Q

List the current drug treatments for heart failure

A 
Diuretics
SA node blockades
Beta blockers 
Aldosterone antagonists
ARNI
ACE inhibitors
46
Q

Give an example of a loop diuretic

A

FRUSEMIDE

47
Q

How do loop diuretics work?

A

Inhibit Na+ re-absorption from the proximal tubule

K+ loss from distal tubule

48
Q

If used incorrectly what can loop diuretics cause?

A

Electrolyte abnormalities

Hypovolaemia and diminished renal perfusion

49
Q

Give an example of a mineralocorticoid receptor antagonist

A

Spironolactone

50
Q

How do mineralocorticoid receptor antagonists work?

A

Acts on distal tubule
Promotes Na+ excretion and K+ re-absorption
Reduces hypertrophy and fibrosis

51
Q

How do ACE inhibitors work?

A

Act on activated renin - angiotensin system
Given orally in small doses with slow titration
Block production of angiotensin:
Vasodilatation
BP lowering
Reduce cardiac work

52
Q

Give an example of an ACE inhibitor

A

Ramipril

53
Q

Give an example of a beta blocker

A

Bisoprolol

54
Q

How do beta blockers work?

A

Block the action of adrenaline and noradrenaline on adrenergic beta receptors
Slow HR, reduce BP

55
Q

What does digoxin do?

A

Action:
Increases myocardial contractility
Slows conduction at the AV node (use in AF)
Excreted by kidney - Toxicity important

56
Q

When is digoxin given?

A

Acute HF especially in AF

Chronic HF in selected cases

57
Q

State the immediate treatment of acute pulmonary oedema

A

High flow oxygen
IV Morphine
IV Nitrates
IV Frusemide

Module 103: Theme 3: Physiology of the cardiovascular system. Principles of pathology, diagnosis and treatment of cardiovascular disease (19 decks)

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