44 - Cardiac Failure

Question 1

Afterload

Answer 1

Resistance to flow

Question 2

Effect of increasing sarcomere length 1) 2)

Answer 2

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

Question 3

Starling’s law

Answer 3

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

Question 4

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

Answer 4

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

Question 5

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

Answer 5

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

Question 6

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

Answer 6

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

Question 7

What is pulmonary artery wedge pressure? 1 2 3 4

Answer 7

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

Question 8

Name of catheter used to measure pressures in heart

Answer 8

Swan-Ganz catheter

Question 9

Preload

Answer 9

Left ventricular end diastolic pressure

Question 10

Equivalents of LVEDP 1) 2) 3)

Answer 10

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

Question 11

Equivalents of RVEDP 1) 2)

Answer 11

1) JPV 2) right atrial end diastolic pressure

Question 12

*Pressures across the capillary wall

Answer 12

Question 13

Starling forces 1) 2) 3) 4)

Answer 13

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

Question 14

What increases fluid leaving capillaries?

Answer 14

Increased venous pressure. This results in oedema

Question 15

Causes of oedema 1) 2) 3) 4)

Answer 15

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

Question 16

Two things that EDP is a measure of

Answer 16

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

Question 17

LVEDP at which pulmonary congestion begins

Answer 17

20-30mmHg

Question 18

Cardiac failure

Answer 18

Cardiac output is less than body needs

Question 19

Most common form of cardiac failure

Answer 19

Problem with contractility

Question 20

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

Answer 20

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

Question 21

What is oedema (pulmonary or systemic) due to?

Answer 21

Increased venous pressure.

Question 22

Mechanisms of cardiac failure 1) 2) 3)

Answer 22

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

Question 23

What does increasing left heart output do to venous pressure?

Answer 23

Increases venous pressure

Question 24

Left heart failure clinical features

Answer 24

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

Question 25

Right heart failure clinical features

Answer 25

Oedema

Question 26

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

Answer 26

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)

Question 27

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

Answer 27

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

Question 28

Left heart failure oedema 1 2 3 4 5

Answer 28

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

Question 29

Right heart failure oedema 1) 2) 3)

Answer 29

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

Question 30

Mechanisms of right heart failure 1) 2) 3)

Answer 30

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

Question 31

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

Answer 31

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

Question 32

Diastolic heart failure 1) 2) 3)

Answer 32

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

Question 33

Treatment for cardiac failure 1 2 3 4

Answer 33

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

Question 34

Effect of reducing preload

Answer 34

Reduce pulmonary venous pressure

Question 35

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

Answer 35

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

Question 36

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

Answer 36

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