Heart failure

Question 1

what is heart failure?

Answer 1

failure of the heart to meet bodily demands

Question 2

what factors affect SV (and therefore CO)?

Answer 2

increased contractility + pre-load = increased SV
increased after-load = decreased SV

Question 3

what is the relationship between pre-load and SV?

Answer 3

increased blood vol in ventricle at end of dyastole causes ventricles to stretch more during systole so greater force of contraction = increased SV

Question 4

what factors increase contractility of ventricular myocytes?

Answer 4

greater stretch of ventricle = increased contractility
greater sympathetic activity = increased contractility

Question 5

what are the causes of heart failure?

Answer 5

most common = ischaemic heart disease
other causes = hypertension, arrhythmias, valvular disease

Question 6

how does ischaemic heart disease cause heart failure?

Answer 6

remodelling 2 types:
ventricular hypertrophy = reduced filling = decreased pre load = decreased SV = decreased CO
ventricular walls are thinner but cant contract well = decreased contractility = decreased SV = decreased CO

Question 7

what are the 2 broad types of heart failure?

Answer 7

HFpEF = heart failure where filling of the heart is the issue
HFrEF = heart failure where emptying of heart is the issue

Question 8

how do we measure ejection fraction?

Answer 8

using echocardiogram
SV / EDV
normal = > 50%

Question 9

how does ejection fraction differ in HFpEF and HFrEF?

Answer 9

HFrEF = < 40%
HFpEF = > 50%

Question 10

what are the common symptoms of heart failure?

Answer 10

dyspnoea (breathlessness)
fatigue (reduced exercise tolerance)
pulmonary or peripheral oedema

Question 11

what is the most common type of heart failure?

Answer 11

left ventricular systolic dysfunction (left ventricular HFrEF)
* ventricle size is normal or thinner but decreased contractility

Question 12

what is the impact of increasing pre-load in a failing heart?

Answer 12

(first think about why it would be good in a healthy heart)
1. increased pre-load has little effect on increasing CO
2. eventually increasing pre-load decreases CO
3. increased fluid in ventricles = increased pressure
4. increased pressure in pulmonary circulation = pulmonary congestion

Question 13

what happens when the CO decreases?

Answer 13

CO = BP x TPR
1. decreased CO = decreased BP
2. decreased BP activates 2 pathways
3. detected by baroreceptors or decreased renal perfusion
* detected by baroreceptors = increased HR and increased TPR
* decreased renal perfusion activates RAAS = increased Na+ and fluid retention in kidney = increased pre-load

Question 14

how does left ventricular systolic dysfunction cause pulmonary oedema?

Answer 14

1. increased pressure in LV
2. increased pressure in pulmonary circulation
3. increased hydrostatic pressure in venule end
4. less favourable gradient between hydrostatic and oncotic pressure
5. increased interstitial fluid accumulation = pulmonary oedema

Question 15

although less common, how can left ventricular systolic dysfunction cause peripheral oedema?

Answer 15

1. reduced renal perfusion = activation of RAAS
2. increased Na+ and H20 retention
3. accumulates in lower extremeties due to gravity

Question 16

how does right ventricular HFrEF cause peripheral oedema?

Answer 16

1. increased pressure in RV = increased pressure in systemic circulation
2. increased central venous pressure = increased jugular venous pressure
3. increased hydrostatic pressure in venule end of capillary
4. less favourable gradient between hydrostatic + oincotic pressure
5. increased accumulation of fluid in interstitial space

Question 17

what is the NYHA classification of heart failure?

Answer 17

Class I
Class 2
Class 3
Class 4

Question 18

what is class I heart failure?

Answer 18

no symptomatic limitations of physical activity

Question 19

what is class II heart failure?

Answer 19

slight limitation of physical activity
normal physical activity = symptoms
no symptoms at rest

Question 20

what is class III heart failure?

Answer 20

marked limitation of physical activity
less than normal physical activity causes symptoms
no symptoms at rest

Question 21

what is class IV heart failure?

Answer 21

inability to carry out any physical activity without symptoms
may have symptoms at rest
discomfort increases with level of physical activity

Question 22

what is heart failure treated?

Answer 22

aim is to decrease pre-load:
ACE inhibitors (decreased Na+ and water retention)
beta blockers (decreased contractility and HR)
diuretics (decreased Na+ and water retention)

Question 23

how is acute heart failure managed + treated?

Answer 23

manaage: do chest X-ray and look for ABCDE, blood work (NTpro-BNP, FBC, urea + electrolytes)
treat: IV furosemide, O2 + respiratory support

Question 24

what does furosemide do?

Answer 24

1. immediate vasodilating effects
2. diuretic action roughly 30 min after given
3. acts to decrease vol + pre load

Question 25

what are the effects of the RAAS in heart failure?

Answer 25

ultimately results in:
1. increased Na+ and water retention (increases pre load)
2. vasoconstriction
3. increased sympathetic activity (increases contractility of heart)

Question 26

what is effect of sympathetic activity in heart failure?

Answer 26

ultimately results in:
1. myocardial hypertrophy
2. decreased contractility
3. myocyte damage

Question 27

what are the physiological effects of beta blockers?

Answer 27

decrease HR
decrease BP
decrease mobilisation of glycogen