heart failure

Question 1

what is heart failure

Answer 1

inability of the heart to maintain tissue perfusion at normal filling pressure

Question 2

what does the frank starling curve show

Answer 2

as we increase the end diastolic pressure of the left ventricle the stroke volume in systole increases

Question 3

what does increased adrenaline do to the heart

Answer 3

increases heart rate and force of contraction to increase stroke volume

Question 4

why does heart failure decrease starlings curve

Answer 4

heart does not have enough force to pump blood around the body but there is a high LV end diastolic pressure

Question 5

what is systolic dysfunction

Answer 5

impaired ventricular contraction/ inotropy

Question 6

what is diastolic dysfunction

Answer 6

impaired ventricular relaxation

Question 7

what are the physiological effects of heart failure

Answer 7

• ventricle walls don’t meet
• bigger LV than LA
• decreased contractility
• increased chamber dimension
• decreased wall thickness

Question 8

what is preload

Answer 8

volume of blood in the ventricles after diastole

Question 9

what is afterload

Answer 9

resistance left ventricle overcomes to overcome circulating blood

Question 10

what are neurohormonal changes in heart failure

Answer 10

compensation for the lack of oxygen that is reaching the body so increases neuronal and hormonal firing

Question 11

what is the maladaptive remodelling in heart failure

Answer 11

issues are not helped or corrected then they become worse and cycle starts again

Question 12

what are the electrophysical changes in heart failure

Answer 12

1. decrease in Ca2+ in the cytosol
2. decrease Ca2+ binding to troponin-C
3. decreases force of contraction

Question 13

what causes an increase in heart contraction

Answer 13

• increased sympathetic activity
• more calcium in cytosolic space

Question 14

why is digoxin used in heart failure

Answer 14

• inhibits Na, K and ATPase
• increase cytosolic ca concentration
• increases force of contraction

Question 15

why is dobutamine used in heart failure

Answer 15

• increases sympathetic activity in the heart
• increases cytosolic ca

Question 16

why is milrinone used in heart failure

Answer 16

• inhibits PDE2
• increases cytosolic ca

Question 17

why don’t inotropic agents not always work

Answer 17

heart works faster as stimulation increased but is less efficient

Question 18

what are the pro-arrhythmogenic changes in heart failure

Answer 18

increase inward current + decreased outward current = action potential prolongation causing arrhythmias

Question 19

what causes an increase in sympathetic overactivity in heart failure

Answer 19

1. baroreceptors detect decrease in blood pumped
2. baroreceptors signal to medullary cardiovascular centre
3. increase HR and contractility
4. renin release
5. cutaneous arterial vasoconstriction
6. adrenalin release

Question 20

how is beta1 adrenergic signalling altered in heart failure

Answer 20

1. sympathetic overdrive
2. beta adrenergic signalling downregulated by antagonist
3. decreases cardiac reserve

Question 21

what are the beta 1 adrenergic mediated effects

Answer 21

• increases heart rate
• increases force of contraction
• increases renin release
• decreases cardiac efficiency
• increase hypotrophic signalling

Question 22

how is the RAAS system activated

Answer 22

1. reduced cardiac output B1-AR activated in juxtaglomerular cells
2. renin released
3. angiotensin released from liver
4. renin and angiotensin make angiotensin I
5. ACE convert angiotensin I to angiotensin II
6. aldosterone production for Na reabsorption, vasoconstriction, sympathetic activity

Question 23

stages of vasoconstriction as neurohormonal signalling compensation

Answer 23

1. Alpha1 and angiotensin 2 type 1 receptors on smooth muscle
2. increase the calcium in the cell
3. leads to contraction
4. increases the total peripheral resistance
5. increase arterial BP
6. increase tissue perfusion
7. increases afterload

Question 24

how does Na+ and H2O retention increase preload

Answer 24

1. increase RAAS signalling
2. angII activates, increasing sodium retention
3. aldosterone binds to receptors, more sodium retained
4. increases circulating volume and tissue perfusion

Question 25

fluid overload from heart failure compensatory mechanism in

Answer 25

- increased circulating volume increases hydrostatic pressure - fluid in peripheral circulation causes pitting oedema, increasing JVP - fluid in bronchi and alveoli - accumulation of blood cause vascular distension decreasing lung compliance to dysponea

Question 26

what medication is used to counteract the fluid overload

Answer 26

- ACE inhibitors - angII receptor antagonist in PCT and collecting ducts - loop diuretic ins thick ascending limb

Question 27

what effect do natriuretic peptides cause

Answer 27

- relax smooth muscle (vasodilation) - inhibit sodium reabsorption

Question 28

what is concentric hypertrophy

Answer 28

- systolic function maintained and diastolic impaired - big thick LV - heart contracts well but is stiff

Question 29

what is the result of stiff contraction

Answer 29

- decreases passive relaxation - less volume at end of diastole - decrease in stroke volume

Question 30

ejection fraction calculation

Answer 30

EF = stroke volume/ end diastolic volume

Question 31

what are the stages of the heart failure cycle

Answer 31

1. injury to heart 2. decreased cardiac output 3. decrease in renal perfusion 4. increase sympathetic activation and increased RAAS 5. vasoconstriction, increase TP, increased blood volume 6. increased after and preload 7. structural remodelling