Lecture 10 - Angina

Question 1

what is ischaemia?

Answer 1

an insufficiency in blood supply. the coronary arteries are the only source of blood for the heart muscle

Question 2

what is angina?

Answer 2

if coronary arteries are blocked the blood supply to the heart will reduce, which may result in chest pain

Question 3

what is angina pectoris?

Answer 3

the result of an ischemia caused by an imbalance between myocardial blood supply and oxygen demand

Question 4

when is angina pectoris typically presented in people with and who is it more common with?

Answer 4

coronary artery disease and more common in women than in men

Question 5

what may angina occur by?

Answer 5

atherosclerosis with blood clot

atherosclerosis

spasm

Question 6

what is stable angina?

Answer 6

occurs when coronary perfusion is impaired by fixed or stable atheroma of coronary arteries

Question 7

what is unstable angina?

Answer 7

is characterised by rapidly worsening chest pain on minimal exertion or at rest

Question 8

what is unstable angina associated with?

Answer 8

associated with an ulcerated atheroma and thrombus formation. this produces reduction of coronary blood flow to produce angina at rest

Question 9

describe prinzmetals angina - what does it cause

Answer 9

coronary spasm:sudden involuntary contraction of smooth muscle tissue or coronary artery

Question 10

what does the spasm do?

Answer 10

spasm temporarily narrows the coronary artery

Question 11

what does the spasm in prinzmetals angina cause?

Answer 11

causes transient impairment of coronary blood supply

Question 12

when does prinzmetals angina occur?

Answer 12

usually occurs at rest

majority of patients have an atherosclerotic plaque but this is often minor when compared with the extent of pain

long term prognosis is very good

Question 13

what are the classifications of stable angina?

Answer 13

exertion angina

angibnal equivalent syndorme

syndrome x

silent ischameia

decubitus angina

nocturnal angina

Question 14

what does exertion or classical angina arise from?

Answer 14

an increase in myocardial oxygen demand during exertion or emotion. relief occurs by rest and nitroglycerine

coronary artery obstructions are not sufficient to result in resting myocardial ischaemia

Question 15

what is anginal equivalent syndrome cause d by and what are the symptoms?

Answer 15

caused by myocardial ischema

symptoms: shortness of breath or pain at a site other than the chest eg arm or jaw

Question 16

describe syndrome X angina

Answer 16

typical, exertion angina with positive exercise stress test

anatomically normal coronary arteries

reduced capacity of vasodilation in microvasculature

long term prognosis is very good

Question 17

describe silent ischemia

Answer 17

very common

more episodes of silent than painful ischemia in the same patient

difficult to diagnose
- holter monitor (records heart rate and rhythm over a 24 hour period)
- exercise testing

Question 18

describe debuticus angina

Answer 18

chest pain occurs only while lying down
- relived by standing or sitting

usually associated with impaired left ventricular function

the patient usually has severe coronary artery disease

Question 19

describe is nocturnal angina

Answer 19

it awakes the patient from sleep

it may be provoked by vivid dreams

it may occur due to coronary spasm

Question 20

what is used in stable angina assessment ?

Answer 20

history: grading scale

exercise testing

electrocardiogram

Question 21

what are the classes of angina severity by the Canadian cardiovascular society graded as?

Answer 21

class I: angina only during strenuous or prolonged physical activity

class II: slight limitation, with angina only during vigour’s physical activity

class III: moderate limitation, symptoms with everyday living activities

Class IV: severe limitation, inability to perform any activity without angina or angina at rest

Question 22

what is the goal of stable angina excercises testing?

Answer 22

to induce a controlled, temporary ischemic state during clinical and ECG observation

Question 22

what is the goal of stable angina excercise testing?

Answer 22

to induce a controlled, temporary ischemic state during clinical and ECG observation

Question 23

what is seen in an ECG with ischemia in the graph?

Answer 23

ST segment depression occurs with ischemia and reverses after ischemia disappears

Question 24

what is an ECG like between angina attacks?

Answer 24

the resting ECG may be normal between angina attacks (unless there are other problems such as myocardial infarction heart block or left ventricular hypertrophy)

Question 25

what is unstable angina in testing like?

Answer 25

angina at rest not responding readily to therapy

recent onset is - less than 1 month

increase in frequency and duration of episode

may be serious indicator of an impending heart attack

Question 26

describe the summary of atherosclerotic plaque and thrombus

Answer 26

1. initially fatty streak
2. plaque enlarges
3. loss of endothelium and exposure of collagen
4. platelet adherence and activation
5. fibrin meshwork deposition with RBC entrapment
6. more flow turbulence, more platelet adherence, more fibrin deposition
7. thrombus of alternating layers of platelets, fibrin and red blood cells

Question 26

why do plaques rupture?

Answer 26

risk of plaque rupture depends on plaque type rather than plaque size. plaques rich in soft extracellular lipids are vulnerable (rupture-prone).

presence of smooth muscle cells in the fibrous cap may provide resistance to rupture.

extracellular lipid accumulation and cap weakening predispose the plaque to rupture

Question 27

describe the alleviation of angina symptoms and treatment

Answer 27

beta blockers first line therapy

1. inadequate control of symptoms - add a calcium channel blocker

if intolerant of beta blockers, treat with a rate limiting calcium channel blocker, long acting nitrates or nicorandil

sublingual gum tablets or spray for immediate relief and before activities known to bring on angina.

referral to a cardiologist of symptoms not controlled on maximum therapeutic doses of two drugs

Question 28

what do these beta blockers drugs do?

Answer 28

lower the oxygen demand of the heart by affecting blood pressure, venous return, heart rate and contractility

Question 29

what drugs are used for the treatment of stable angina?

Answer 29

beta adrenergic receptor blockers

calcium channel blockers

nitrates

potassium channel activators

Question 30

describe what beta adrenegeric receptor blockers od and give examples of them

Answer 30

beta adrenergic receptor blockers eg atenolol, bisoprolol and metoprolol

beta adrenergic blocking agents decrease the oxygen demands of the myocardium by lowering both the rate and force of contraction of the heart

Question 31

describe how calcium channel blockers work and give examples of them

Answer 31

the blockers prevent entry via L type calcium channels

calcium influx is increased in ischemia because of the membrane depolarisation that hypoxia produces. calcium channels blockers protect the tissue by inhibiting the entrance of calcium int cardiac and smooth muscle cells of the coronary and systemic arterial beds.

examples are diltiziam and verapamil

Question 32

describe how nitrates work in producing stable angina and give examples of them.

Answer 32

nitrates relax coronary arteries by decreasing coronary vasconstriction or spasm and increase perfusion of the myocardium. ind addition they relax veins, decreasing preload and myocardial oxygen consumption

nitrates donate nitric oxide which stimulates cyclic guanosine monophosphate cyclase that can release calcium in muscle.

examples are gtn; isosorbide mononitrate

Question 32

describe how potassium channel activators work in treatment to give stable angina

Answer 32

potassium channel activators are nicorandil

nicrorandil has the dual properties of a nitrate and K+ ATP channel agonist. activation of K+ ATP channels on smooth muscle cells hyper polarises the membrane and decreases calcium entry