44 - Cardiac Failure Flashcards

1
Q

Afterload

A

Resistance to flow

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2
Q

Effect of increasing sarcomere length 1) 2)

A

1) Increase number of cross bridges 2) Increase Ca2+ sensitivity of troponin This increases force of contraction

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3
Q

Starling’s law

A

Increased preload (end diastolic volume) leads to increased cardiac contraction which leads to increased stroke volume and cardiac output

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4
Q

Important things derived from Starling’s law 1) 2)

A

1) Cardiac output = venous return 2) Left heart output = right heart output

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5
Q

How can right ventricular end diastolic pressure be measured? 1) 2)

A

1) Catheter inserted through a vein across the tricuspid valve 2) Measure right atrial pressure, because at end of diastole, atrial pressure = ventricular pressure = JVP

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6
Q

How can left ventricular end diastolic pressure be measured? 1) 2)

A

1) Catheter inserted via artery across aortic valve. 2) Measure left atrial pressure because at the end of diastole atrial pressure = ventricular pressure = pulmonary artery wedge pressure

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7
Q

What is pulmonary artery wedge pressure? 1 2 3 4

A

1) A measure of pulmonary venous pressure. 2) Catheter inserted into pulmonary artery. 3) Balloon on catheter inflated, occludes pulmonary artery. 4) This means the pressure measured will be from pulmonary vein

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8
Q

Name of catheter used to measure pressures in heart

A

Swan-Ganz catheter

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9
Q

Preload

A

Left ventricular end diastolic pressure

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10
Q

Equivalents of LVEDP 1) 2) 3)

A

1) Left atrial pressure diastolic 2) Diastolic pulmonary venous pressure 3) Pulmonary venous pressure

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11
Q

Equivalents of RVEDP 1) 2)

A

1) JPV 2) right atrial end diastolic pressure

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12
Q

*Pressures across the capillary wall

A
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13
Q

Starling forces 1) 2) 3) 4)

A

1) Movement of fluids in or out of capillaries across capillary length 2) Tends to leak out at arterial end 3) Tends to enter at venous end 4) Excess fluid is removed by lymphatics

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14
Q

What increases fluid leaving capillaries?

A

Increased venous pressure. This results in oedema

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15
Q

Causes of oedema 1) 2) 3) 4)

A

1) Increased venous pressure (EG: heart failure) 2) Decreased osmotic pressure (renal, liver failure) 3) Blocked lymphatics (cancer) 4) Increased capillary permeability (infection)

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16
Q

Two things that EDP is a measure of

A

1) Filling of the ventricles 2) Venous pressure driving fluid out of capillaries

17
Q

LVEDP at which pulmonary congestion begins

A

20-30mmHg

18
Q

Cardiac failure

A

Cardiac output is less than body needs

19
Q

Most common form of cardiac failure

A

Problem with contractility

20
Q

Why does lung congestion occur in cardiac failure? 1) 2) 3) 4) 5)

A

1) Cardiac output for a given LVEDP is reduced 2) Cardiac output can be maintained by increasing fluid retention (increases blood volume, venous return) 3) This increases LVEDP. 4) This increases venous pressure, which increases amount of fluid that leaves capillaries in pulmonary circulation. 5) This leads to fluid collecting i nlungs

21
Q

What is oedema (pulmonary or systemic) due to?

A

Increased venous pressure.

22
Q

Mechanisms of cardiac failure 1) 2) 3)

A

1) Loss of myocardial muscle (ischaemic heart disease, cardiomyopathy) 2) Pressure overload (aortic stenosis, hypertension) 3) Volume overload (valve regurgitation, shunts)

23
Q

What does increasing left heart output do to venous pressure?

A

Increases venous pressure

24
Q

Left heart failure clinical features

A

1) Shortness of breath 2) Fatigue 3) Tachycardia 4) Lung crepitations

25
Q

Right heart failure clinical features

A

Oedema

26
Q

Fluid retention in cardiac failure 1) 2) 3) 4)

A

1) Decreased cardiac output leads to decreased renal blood flow 2) Activation of renin-angiotensin-aldosterone system 3) Fluid, Na+ retention 4) K+ loss, vasoconstriction (increased afterload, low K+ for cells can lead to arrhythmias)

27
Q

Sympathetic NS activity in cardiac failure 1) 2) 3)

A

1) Increased noradrenaline output 2) Initial increase in contractility 3) Long-term deleterious effects (vasoconstriction, ventricular arrhythmias, direct toxic effect)

28
Q

Left heart failure oedema 1 2 3 4 5

A

1) Na+, water retention 2) Increase LVEDP to increase CO 3) Increased left atrial pressure leads to increased pulmonary venous pressure 4) Oedema from capillaries into lung interstitium, alveoli 5) Pulmonary congestion leading to shortness of breath

29
Q

Right heart failure oedema 1) 2) 3)

A

1) Na+ and water retention 2) Increased RVEDP leads to increased right atrial pressure, which increases JVP 3) Peripheral oedema, liver congestion

30
Q

Mechanisms of right heart failure 1) 2) 3)

A

1) Global heart disease (cardiomyopathy) 2) Specific right heart disease (pulmonary hypertension, cor pulmonale, pulmonary embolism, RV cardiomyopathy) 3) Left heart failure

31
Q

How can left heart failure lead to right heart failure? 1) 2) 3) 4)

A

1) Pulmonary venous hypertension 2) Pulmonary congestion 3) Pulmonary hypoxia leads to vasoconstriction (endothelin, angiopoietin) 4) Pulmonary arterial hypertension

32
Q

Diastolic heart failure 1) 2) 3)

A

1) Reduced LV compliance (EG: scar from infarct, stiff from chronic hypertension or hypertrophy) 2) Increased LVEDP, so higher pressure needed to fill LV 3) Increase in pulmonary venous pressure

33
Q

Treatment for cardiac failure 1 2 3 4

A

1) Thiazide diuretics 2) Aldosterone antagonists 3) ACE inhibitors 4) Angiotensin receptor antagonists Try to remove fluid (decrease preload), vasodilate (reduce afterload)

34
Q

Effect of reducing preload

A

Reduce pulmonary venous pressure

35
Q

Ways to treat underlying causes of heart failure 1) 2) 3)

A

1) Coronary artery bypass 2) Valve replacement 3) Treat hypertension

36
Q

Surgical ways to treat cardiac failure 1) 2) 3)

A

1) Biventricular pacemaker 2) Implantable defibrillator 3) Cardiac transplantation (now uncommon)