Ischaemic Heart Disease

Question 1

What is a heart attack?

Answer 1

Blockage of blood vessels
= heart starved of oxygen

Question 2

What dos increased myocardium demand increase?

Answer 2

Coronary artery blood flow

Question 3

What is the equation for oxygen demand?

Answer 3

Blood flow X arteriovenous O conc difference

Question 4

Why does O act as a vasoconstrictor?

Answer 4

O deficiency dilates coronary arteries

Question 5

Decsribe what happens during hypoxia

Answer 5

AMP cannot be regenerated to ATP =
Adenosine rises in myocardium
Adenosine acts as direct vasodilator
Accumulation of lactate H+ ions + prostacyclin = vasodilation

Question 6

When does myocardia ischaemia occur?

Answer 6

Myocardial oxygen demand exceeds myocardial oxygen supply

Question 7

What is myocardial oxygen supply affected by?

Answer 7

Diastolic perfusion pressure
Coronary vascular resistance
O-carrying capacity

Question 8

What is myocardial oxygen demand affected by?

Answer 8

Wall tension
HR
Contractility

Question 9

What are the causes of ischaemic heart disease?

Answer 9

Atherosclerosis
Arteritis
Embolism + endocarditis
Coronary artery wall thickening
Coronary spasm
Congenital arterial disease

Question 10

Describe what stenosis does

Answer 10

Increases resistance to floe
O supply may not be able to meet demand
Diminished coronary reserve
Raised resistance

Question 11

What happens when the coronary arteries are narrowed?

Answer 11

Blood flow to heart slows or stops
= myocardial ischaemia + hypoxia pain

Question 12

What is a result from ischaemic heart disease?

Answer 12

Chest pain
SOB
Myocardial infarction

Question 13

What are the modifiable risk factors?

Answer 13

Hypertension
Hypercholesterolaemia
Smoking
Diabetes
Sedentary lifestyle
Obesity

Question 14

What are non-modifiable factors?

Answer 14

Age
Male gender
Family history

Question 15

What is the primary symptom associated with ischaemic heart disease?

Answer 15

Chest pain

Question 16

Why is pain caused?

Answer 16

Pain from myocardium after switching to anaerobic metabolism (low O supply)

Question 17

What is stable angina?

Answer 17

Experienced on exertion or emotional stress
Relieved by rest

Question 18

What is unstable angina?

Answer 18

Incomplete occlusion-angina on minor exertion
Blockage = angina at rest

Question 19

What is variant angina?

Answer 19

Diffuse coronary vasospasm

Question 20

Describe what happens as a consequence of ischaemia
ATP deficiency

Answer 20

ATP produced non-aerobically
= lactic acid produced
Dissociates into H+ + lactate
Low ATP + high H+ = abnormal ventricular contraction

Question 21

What can happen as a consequence of persistent ischaemia?

Answer 21

Infarction

Question 22

What are the consequences of myocardial ATP deficiency?

Answer 22

Impairment of ventricular systolic pumping action
Decreased compliance of myocardium during diastole
Pulmonary congestion + dyspnea

Question 23

What does extended myocardial ischaemia lead to?

Answer 23

Myocardial necrosis (infarction)

Question 24

What is the development of myocardial infarction promoted by?

Answer 24

Turbulence + rupture of atheroma
Thrombocyte activation
Abnormal function of endothelium
Sympathetic nervous stimulation increases cardiac work

Question 25

How can you identify myocardial infarction?

Answer 25

Enzyme markers

Question 26

What are the main enzyme markers?

Answer 26

Troponin = signify rupture of cardiomyocyte

Question 27

What are the therapy principles?

Answer 27

Reduce O demand OR Increase O supply

Question 28

Describe smooth muscle relaxation Nitric oxygen

Answer 28

ACh binding to G protein receptors = IP3 production IP3 releases Ca2+ Ca2+ + calmodulin form complex which stimulate NO synthase to produce NO NO diffuses from cell to muscle cells NO activates guanylyl cyclase kinase to make cGMP cGMP activates protein kinase G Activates myosin light chai phosphatase Dephosphorylates myosin light chains = smooth muscle relaxation

Question 29

What are examples of nitrates?

Answer 29

Glyceryl Trinitrate (GTN) Isosorbide nitrate

Question 30

What are nitrates indication?

Answer 30

Stable angina Variant angina Acute coronary syndrome

Question 31

What are the side effects of nitrates?

Answer 31

Tachycardia Headache Postural hypotension

Question 32

Describe the mechanism of action for nitrates

Answer 32

Acts directly on smooth muscle through cGMP mechanism Coronary microvessels contain enzyme to convert NO

Question 33

What is the dose of nitrates dependent on?

Answer 33

Dilation of coronary vessels

Question 34

What is the 1st part of Nicorandil mechanism? Dual mechanism

Answer 34

Relaxation of venous vasculature Systemic + epicardial arteries Coronary blood flow maximised, pre-load + afterload reduced

Question 35

What is the 2nd part of Nicorandil mechanism? Dual mechanism

Answer 35

Opens ATP-dependent K+ channels Hyperpolarisation = arterial dilation Cardiac repolarisation = reduced cardiac work

Question 36

What are examples of beta-blockers in angina treatment?

Answer 36

Atenolol Carvedilol Propranolol

Question 37

What is the indication of beta-blockers?

Answer 37

Stable angina Variant angina

Question 38

What is the mechanism of action of beta-blockers?

Answer 38

Block beta-1 adrenoreceptor + reduced generation of intracellular cAMP = decreased HR = reduce force of contraction = reduce O demand

Question 39

What are the side effects of beta-blockers?

Answer 39

Bronchospasm Hypoglycaemia Interact with CCB

Question 40

What are examples of CCB?

Answer 40

Verapamil Nifedipine Diltiazem

Question 41

What is the indication of CCB?

Answer 41

Stable angina Variant angina

Question 42

What is the mechanism of action of CCB?

Answer 42

Peripheral vasodilation Reduced cardiac work

Question 43

What are the side effects of CCB?

Answer 43

AV blockage Oedema Hypotension