Ischaemic Heart Disease and MI

Question 1

When are fibrinolytic drugs used

Answer 1

For prophylaxis and after a myocardial infarction.

Question 2

When are fibrinolytic effective to reduce mortality

Answer 2

If they are given immediately (less than 12 hours) after MI or stroke.

Question 3

What do fibrinolytic drugs do

Answer 3

They act to accelerate conversion of plasminogen to plasmin which degrades fibrin in a thrombus.

Question 4

What are two examples of fibrinolytic drugs

Answer 4

Tissue plasminogen activator (tPA) and streptokinase.

Question 5

What is produced naturally by the body with fibrinolytic properties

Answer 5

Tissue plasminogen activator (tPA).

Question 6

What is the risk associated with using fibrinolytic drugs

Answer 6

Bleeding

Question 7

How many times a year can fibrinolytic drugs be used

Answer 7

Once

Question 8

What reverses bleeding

Answer 8

Tranexamic acid

Question 9

What surgical approaches are used for ischaemic heart disease

Answer 9

• Balloon angioplasty

- Senting

Question 10

Why are there now more people living with heart failure

Answer 10

Because we are better equipped to deal with it now so not as many die straight away from it.

Question 11

What is the Frank-Starling mechanism

Answer 11

If there is increased blood volume, there will be increased stretch of the myocardium and increased force with which to pump blood out.

Question 12

By what mechanism does the heart work

Answer 12

By stretch and recoil. The greater the stretch, the greater the degree of recoil up to a certain point.

Question 13

What happens to preload when more blood returns to the heart

Answer 13

Preload increases.

Question 14

What is venous return

Answer 14

The amount of blood entering the ventricle during diastole

Question 15

What does venous return determine

Answer 15

Preload

Question 16

What does increased preload result in

Answer 16

Increased stroke volume and increased cardiac output.

Question 17

What factors determine the end diastolic volume and therefore preload

Answer 17

• Venous tone and capacitance controlled by the sympathetic nervous system
• Plasma volume controlled by sodium and water secretion from the kidney.

Question 18

What increases preload

Answer 18

The sympathetic nervous system constricting smooth muscle of blood vessels and the RAAS increasing blood volume.

Question 19

What is afterload

Answer 19

The force against which the heart has to pump

Question 20

What is afterload determined by

Answer 20

The tone in resistance arterioles.

Question 21

What increases afterload

Answer 21

Increased resistance in the arterioles.

Question 22

In which conditions is preload increased

Answer 22

• Hypervolemia
• Regurgitation of cardiac valves
• Heart failure

Question 23

In which conditions is afterload increased

Answer 23

• Hypertension

- Vasoconstriction

Question 24

Why is preload often larger in heart failure

Answer 24

Because the kidneys are not being effectively perfused and this results in a decreased ability to get rid of fluid.

Question 25

Where is blood pressure detected in the kidneys

Answer 25

The juxtaglomerular cells near the afferent arteriole

Question 26

What happens when low blood pressure is detected by the juxtaglomerular cells of the kidney

Answer 26

Renin is secreted into the plasma.

Question 27

What does renin do

Answer 27

Renin cleaves angiotensin to produce angiotensin I which is then converted to angiotensin II.

Question 28

Which enzyme converts angiotensin I to angiotensin II

Answer 28

Angiotensin converting enzyme (ACE).

Question 29

What is the action of angiotensin II

Answer 29

It is a vasoconstrictor so increases blood pressure and afterload. It also stimulates the release of aldosterone and ADH.

Question 30

Where is aldosterone secreted from

Answer 30

The adrenal cortex.

Question 31

What is the role of aldosterone

Answer 31

It increase reabsorption of sodium ions in the kidney tubules back into the blood.

Question 32

What do sympathetic nerves do to the heart

Answer 32

Act at beat 1 adrenoceptors to increase heart rate, conduction and contractility.

Question 33

What do sympathetic nerves do at arterioles

Answer 33

Act on alpha adrenoceptors to bring about vasoconstriction and increase afterload.

Question 34

What do sympathetic nerves do at the veins

Answer 34

Act on alpha receptors to bring about vasoconstriction and increase preload.

Question 35

What do parasympathetic nerves do to the heart

Answer 35

Act at M2 (muscarinic/cholinergic) receptors to reduce heart rate, conduction and contractility.

Question 36

What do sympathetic nerves do at the kidney

Answer 36

Act on beta-1 adrenoceptors to bring about activation of the renin-angiotensin system.

Question 37

What are the symptoms of heart failure

Answer 37

- Breathlessness - Muscle weakness - Peripheral oedema - Cardiac arrhythmias - Poor tissue perfusion and organ failure.

Question 38

What are the causes of heart failure

Answer 38

- Myocardial infarction - Pressure overload - Volume overload - Cardiomyopathy - Myocarditis

Question 39

What is digoxin used to treat

Answer 39

Heart failure

Question 40

What is digoxin

Answer 40

A cardiac glycoside

Question 41

What do cardiac glycosides do

Answer 41

Increase the force of contraction due to increased calcium within the cell - it is a positive inotrope.

Question 42

Other than digoxin, what is an example of another inotrope used to increase contractility

Answer 42

Dobutamine

Question 43

What type of drug is dobutamine

Answer 43

A beta 1 adrenoceptor agonist.

Question 44

Which drugs are used to break the cycle of heart failure and unload the heart

Answer 44

- Diuretics - Inhibitors of the RAAS system - renin inhibitor, ACE inhibitor, angiotensin I receptor agonist, mineralcorticoid receptor agonists - Beta blockers - Other vasodilators.

Question 45

What structural changes can occur in heart failure

Answer 45

- Fibroblasts laying down collagen leading to stiffness of vessels - Hypertrophy

Question 46

What is the aim at the kidney for treating heart failure

Answer 46

To increase sodium and water loss and therefore reduce blood volume and preload.

Question 47

What are two examples of loop diuretics

Answer 47

- Frusemide | - Bumetamide

Question 48

What do loop diuretics do

Answer 48

Loop diuretics impair NA+/K+ and Cl- reabsorption in the ascending loop of Henle.

Question 49

What is an example of a mineralcorticoid receptor antagonist

Answer 49

Spironalactone

Question 50

What do mineralocorticoid receptor antagonists like spironolactone do

Answer 50

Block the effects of aldosterone on Na/K reabsorption to increase fluid loss.

Question 51

What do ACE inhibitors do

Answer 51

Inhibits angiotensin converting enzyme so angiotensin I is not converted to vasoconstrictor angiotensin II.

Question 52

Give two examples of ACE inhibitors

Answer 52

- Enalapril | - Lisinopril

Question 53

What do angiotensin receptor antagonists do

Answer 53

Prevent the binding of angiotensin II to its receptor to prevent the initiation of vasoconstriction.

Question 54

Give two examples of angiotensin receptor antagonists

Answer 54

- Losartan | - Valsartan

Question 55

Give two examples of beta 1 selective beta adrenoceptor antagonists

Answer 55

- Atenolol | - Metoprolol

Question 56

What is the action of beta 1 selective adrenoceptor blockers

Answer 56

Reduce the sympathetic drive to the heart to reduce heart rate and block renin release from the kidney to decrease vasoconstriction so afterload and blood volume so preload.

Question 57

What is an example of a nitrovasodilator

Answer 57

Isosorbide mononitrate

Question 58

What is hydralazine

Answer 58

A vasodilator

Question 59

In what situations ate nitrates and hydralazine used

Answer 59

When there is acute heart failure or in patients with chronic heart failure who do not respond to other drugs.

Question 60

What happens to the heart wall in the progression of heart failure

Answer 60

it will become thicker and stiffer due to fibrosis and hypertrophy.