Pathophysiology Of Heart Failure

Question 1

What is the equation for cardiac output?

Answer 1

CO = Stroke volume x Heart rate

Question 2

What is cardiac output?

Answer 2

The volume of blood expelled per ventricle per minute

Question 3

What is stroke volume?

Answer 3

The volume of blood ejected by a single ventricle in a single beat

Question 4

What is the total (total volume of blood available) called available at the end of diastole?

Answer 4

End Diastolic Volume

Question 5

What is ejection fraction?

Answer 5

The amount of blood ejected by ventricle in a single heart beat as a fraction of total volume available (EDV)

Question 6

What determines stroke volume?

Answer 6

Pre load
Myocardial contractility
After load

Question 7

What is pre load?

Answer 7

The stretch on the ventricle just before contraction

Question 8

What is afterload?

Answer 8

Total peripheral resistance

Question 9

How does preload release to stroke volume?

Answer 9

The larger the volume in the ventricle at the end diastole (EDV) the more the ventricles stretch

The more stretch = higher stroke vol = higher CO = CARDIAC MYOCYTES CONTRACT HARDER (up until a certain point)

Question 10

What is the term which describes the increased strength of contraction of the heart?

Answer 10

+ve inotropy

Question 11

What balances the increased sympathetic activity of the heart (+ve inotropy) as stroke volume increases?

Answer 11

After load increases (as BP increases)

Question 12

What is after load?

Answer 12

The pressure against the ventricle is ejecting blood

Question 13

Generally what is the definition of heart failure?

Answer 13

The inability of the heart to meet the demands of the body (cant deliver enough 02 for example)

Question 14

What is the clinical description of heart failure?

Answer 14

The clinical syndrome of reduced cardiac output, tissue hypoperfusion, increased pulmonary pressures and tissue congestion

Question 15

What are the 2 ways which lead to reduced CO?

Answer 15

Impaired ventricular filling
Impaired emptying of the heart

Question 16

What is tissue congestion?

Answer 16

When tissue fluid accumulates in the tissues (oedema)

Question 17

What is the most common cause of heart failure?

Answer 17

Ischaemic heart disease = lack of blood supply to heart

Question 18

What can cause heart failure?

Answer 18

Ischaemic heart disease
Hypertension
Valvular disease
Cardiomyopathies (hypertrophic)
Arrhythmias

Question 19

How can sepsis and thyrotoxicosis cause heart failure?

Answer 19

The body has an extremely high metabolic demand. The cardiac output of the heart cant meet this demand

VERY RARE

Question 20

How does ischaemic heart damage leading to remodelling affect the heart

Answer 20

Loss of myocytes + fibrosis:
Changes the ventricles ability to function, its size or its shape

This can affect the ventricles ability to fill or eject blood

Question 21

What is the general problem if heart failure is an issue with ejection?

Answer 21

A contractile problem

Question 22

What can make it so the heart cant pump with enough force?

Answer 22

Muscle walls thin and fibrosed
Chanmber space enlarged
Abnormal/uncoordinated myocardial contraction

Question 23

When heart failure is caused be a filling problem how can ventricular volume/capacity for blood be reduced?

Answer 23

Ventricular chambers too stiff/not relaxed enough
Ventricular wall too thick

SPACE AVAILABLE IN VENTRICLE IS REDUCED (EDV/PRE LOAD IS REDUCED)

Question 24

How can we measure wether heart failure is due to an ejection problem or a filling problem?

Answer 24

Measure Ejection Fraction

Question 25

What is the equation for ejection fraction?

Answer 25

Stroke volume/EDV Given as a percentage

Question 26

How do you measure ejection fraction?

Answer 26

Echocardiogram

Question 27

What is a normal healthy ejection fraction?

Answer 27

50% or more

Question 28

What is the classification of HEart Failure with a reduced ejection fracture = ejection problem? HFrEF

Answer 28

Ejection fracture < 40%

Question 29

What is the classification of HEart Failure with a Normal ejection fracture = filling problem? HFpEF

Answer 29

EF greater than or equal to 50%

Question 30

What is HFrEF?

Answer 30

Heart failure with reduced ejection fracture indicating ejection problem EF < 40%

Question 31

What is HFpEF?

Answer 31

Heart failure with preserved Ejeection Fraction Indicates filling problem EF > 50%

Question 32

Which ventricle i most commonly involved in heart failure?

Answer 32

Left

Question 33

If one ventricle fails it eventually leads to both failing, what is it called when both ventricles fail?

Answer 33

Biventricular (congestive heart failure)

Question 34

What are the key manifestations of both types of heart failure?

Answer 34

Dyspnoea Fatigue Tissue fluid retention (pulmonary and/or peripheral oedema)

Question 35

What is dyspnoea?

Answer 35

Difficulty breathing

Question 36

What causes the fatigue in heart failure?

Answer 36

Tissue hypoperfusion

Question 37

What is left ventricular systolic dysfunction?

Answer 37

When there is an ejection problem involving the left ventricle

Question 38

If left ventricular systolic dysfunction caused heart failure, what would the ejection fraction be?

Answer 38

EF < 40%

Question 39

In Left Ventricular Systolic Heart failure, what happens to the cardiac output as the end diastolic volume/preload increases?

Answer 39

Small increase early on however it eventually worsens/decreases the cardiac output due to the impaired contractility of the cardiac myocytes

Question 40

Why can left ventricular systolic heart failure cause pulmonary congestion/pulmonary oedema?

Answer 40

Left ventricle not emptying properly so EDV/preload increases inside it This leads to increased pressure in the atria too This leads to increased pressure in the pulmonary vessels leading into the LA Increased pressure in these veins forces more tissue fluid out

Question 41

Why is neuro-hormonal activation as a result of reduced cardiac output in heart failure a bad thing?

Answer 41

It exacerbates the heart failure Increases the peripheral resistance and circulating blood volume which increases the blood pressure

Question 42

What responses become stimulated in the neuro-hormonal response to heart failure?

Answer 42

Baroreceptors (neural stimulation) RAAS (Renal perfusion/hormonal activation)

Question 43

When cardiac output and BP is low in HF, what response does the baroreceptors stimulate?

Answer 43

Inc sympathetic drive: -Inc Heart Rate -Inc Peripheral resistance (vasoconstriction) Afterload INCREASED

Question 44

When cardiac output and BP is low in HF, what response does the poor renal perfusion/RAAS stimulate to increase Pre load?

Answer 44

Aldosterone stimulates more Na+ and water retention increasing blood volume

Question 45

When cardiac output and BP is low in HF, what response does the poor renal perfusion/RAAS stimulate to increase after load?

Answer 45

Angiotensin II leads to vasoconstriction

Question 46

What negative effects does the neuro-hormonal corrective mechanisms have in heart failure?

Answer 46

Further increase pressure in ventricles Increased amounts of tissue fluid due to increased pressures in pulmonary or systemic circulation Long term activation of sympathetic NS may lead to heart no longer being able to respond to adrenaline

Question 47

What are the 3 clinical presentations of Heart Failure?

Answer 47

Dyspnoea Fatigue Tissue fluid retention (pulmonary and//or peripheral oedema)

Question 48

What type of oedema tends to mainly occur with left ventricular heart failure?

Answer 48

Pulmonary oedema

Question 49

Why can left ventricular heart failure result in pulmonary oedema?

Answer 49

Pressure in LV inc Pressure in LA inc Pressure in venule end of Pulmnary circulation increases Hydrostatic pressure at venule end of pulmonary capillary beds inc greater than oncotic pressure

Question 50

What sound would be hear when listening to Pulmonary oedema??

Answer 50

Crackling/crepitations

Question 51

What can some peripheral oedema occur with left ventricular hypertrophy (mainly pulmonary oedema)?

Answer 51

Water retained due to RAAS and it pools in legs

Question 52

What is Orthopnoea?

Answer 52

Dyspnoea which worsens on lying flat

Question 53

What is Paroxysmal nocturnal dyspnoea?

Answer 53

Waking up suddenly in the night gasping for breath

Question 54

Why would right ventricular heart failure cause Peripheral oedema (legs)?

Answer 54

Pressure in RV inc Pressure in RA inc Causes central venous pressure to increases Jugular venous pressure increases Increased hydrostatic pressure at venule end of systemic capillary beds Inc tissue fluid Gravity pulls tissue fluid down

Question 55

What type of heart failure causes raised Jugular Venous Pressure?

Answer 55

Right Ventricular Heart failure

Question 56

What commonly causes right ventricular heart failure?

Answer 56

Left ventricular heart failure usually leads to it

Question 57

What is the definition of Congestive Heart Failure?

Answer 57

When both ventricles failure (biventricular heart failure)

Question 58

What drugs can be given to reduce workload of the heart in heart failure?

Answer 58

Beta blockers (slow HR) Bisoprolol, Atenolol Diuretics (reduce afterload/circulating blood) Furosemide ACE inhibitors (vasodilator reduce afterload) Ramipril or enalapril GTN spray (reduce pre load by vasodilation, reducing venous pressure going to heart)

Question 59

What is the mechanism of action of GTN spray?

Answer 59

Gets broken down into Nitric Oxide which is a potent vasodilator Vasodilates veins reducing preload Vasodilates coronary arteries increasing blood supply to the heart Leads to relaxation of smooth muscle in blood vessels