myocardial infarction Flashcards

1
Q

what 3 things does acute coronary syndromes include

A
  • STEMI
  • NSTEMI
  • unstable angina
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2
Q

what is difference between MI and angina

A

in MI there is occluding thrombus which leads to myocardial necrosis and a rise in serum troponins or creatine kinase

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3
Q

when does MI occur

A

when cardiac myocytes die due to myocardial ischaemia

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4
Q

how can MI be diagnosed

A
  • appropriate clinical history
  • ECG
  • elevated biochemical markers (troponin, CK)
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5
Q

when should MI term be used

A

when there is evidence of myocardial necrosis in clinical setting

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6
Q

how many types of MI are there

A

5

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7
Q

what mechanism causes all ACS

A

rupture or erosion of the fibrous cap of a coronary artery plaque

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8
Q

what does rupture of platelet plaque lead to

A
  • platelet aggregation and adhesion
  • localised thrombosis
  • vasoconstriction
  • distal thrombus embolisation
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9
Q

what platelets cause vasoconstriction

A
  • serotonin

- thromboxane A2

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10
Q

why does ischaemia occur

A

reduction of coronary blood flow

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11
Q

symptoms

A
  • chest pain at rest
  • indigestion
  • pleuritic chest pain
  • dyspnoea
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12
Q

what does ECG show

A
  • ST depression

- T wave inversion

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13
Q

what does a complete occlusion of coronary vessel show on ECG

A

ST elevation

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14
Q

where is troponin located

A

with tropomyosin on the thin actin filament

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15
Q

what troponin attaches tropomyosin

A

T

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16
Q

what does troponin C bind

A

calcium during excitation-contraction coupling

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17
Q

what does troponin I inhibit

A

the myosin binding site on the actin

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18
Q

what does increased troponin mean

A

higher mortality rate in ACS

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19
Q

what is a standard marker for myocyte death

A

CK

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20
Q

is CK accurate

A

no

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21
Q

what is CK better at determining

A

re-infarction

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22
Q

what becomes elevated very early in MI

A

myoglobin

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23
Q

is myoglobin specific

A

no

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24
Q

what does ECG show for NSTEMI

A
  • ST depression

- dynamic ST changes

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25
Q

what are risk factors for NSTEI

A
  • age
  • prior MI
  • bypass surgery
  • diabetes
  • heart failure
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26
Q

what is used to diagnose NSTEMI

A
  • raised troponin

- ECG

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27
Q

whats done first for NSTEMI

A

PCI (within 2 hours)

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28
Q

what drugs are given for support (MI)

A
  • aspirin
  • anti-plattelet
  • anti thrombotic (LMWH)
  • oxygen (if hypoxic)
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29
Q

what is given to patient for sickness

A

opiates + GTN

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30
Q

what does rupture of atheromatous plaque expose

A

the circulating platelets to ADP, thromboxane A2, adrenaline, thrombin and collagen tissue factor

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31
Q

what does platelet activation stimulate

A

the expression of glycoprotein IIb/IIIa receptor on platelet surface

32
Q

what antiplatelet therapy should ACS patients be given

A

dual platelet therapy

aspirin and an ADP-receptor antagonist (clopidogrel or prasugrel or tricagrelor)

33
Q

what else should be added to the antiplatelet therapy

A

antithrombin

34
Q

what drug is given to reduce myocardial ischaemia

A

beta blocker

35
Q

how do beta blocker reduce myocardial ischaemia

A

by blocking circulating catecholamines

lower heart rate and blood pressure

36
Q

what drug blocks HMG CoA reductase

A

statins

37
Q

what additional 2 drugs are routinely administered

A
  • statins

- ACE inhibitors

38
Q

what are single vessel lesions are treated with

A

PCI

39
Q

why does myocardial infarction occur

A

when cardiac myocytes die due to prolonged myocardial ischaemia

40
Q

how long does it take for myocardial necrosis to occur

A

15-30 minutes

41
Q

how long would chest pain last before you come concerned about MI

A

20 minutes

42
Q

does STEMI chest pain respond to sublingual glycerol trinitrate

A

no

43
Q

where can the pain radiate in STEMI

A

to the left arm, neck or jaw

44
Q

what are other symptoms that can occur in elderly

A
  • dyspnoea
  • fatigue
  • pre-syncope
  • syncope
45
Q

what are other common symptoms of STEMI

A
  • pale
  • clammy
  • marked sweating
  • thready pulse
  • hypotension
  • bradycardia/tachycardia
46
Q

what ECG leads are affected in STEMI

A

those facing the infarction

47
Q

what ECG changes are evident in STEMI

A

ST elevation (due to opening of K channels)

48
Q

what leads have ST elevation in anterior STEMI

A

II
III
AVF

49
Q

what leads have ST elevation in later STEMI

A

I
AVL
V5
V6

50
Q

what leads have ST elevation in poster STEMI

A

ST depression V1-V3

ST elevation in V5-V6

51
Q

ST elevation in V3-V4 is where

A

anterior

52
Q

ST elevation in V1-V3 is where

A

anteroseptal

53
Q
ST elevation in:
V4-V6 
AVL
I 
is where
A

anterolateral

54
Q

ST elevation in
I
AVL
is where

A

latteral

55
Q
ST elevation in:
II 
III 
AVF 
is where
A

inferior

56
Q

ST elevation in:

V1-V2 is where

A

posterior

57
Q

what imaging can be helpful in STEMI

A

transthoracic echocardiography

58
Q

what has to be done quickly once patient diagnosed with STEMI

A

PCI or thrombolysis

59
Q

what is the initial medical therapy given for STEMI

A
  • oxygen
  • morphine (opioids)
  • aspirin

MONA + C

60
Q

what is the time frame for PCI

A

90 minutes

61
Q

what should patients undergoing primary PCI be given in STEMI

A
  • dual antiplatelet
  • aspirin
  • ADP-receptor blocker (e.g. prasugrel or tricagrelor)
62
Q

what do fibrinolytics enhance

A

the breakdown of occlusive thromboses by the activation of plasminogen. to form plasmin

63
Q

what can be used if PCI unavailable in STEMI

A

fibrinolysis (thrombolysis)

can prevent death

64
Q

when is cardiac artery bypass surgery usually done in STEMI

A

for complications of MI

65
Q

complications

A
  • heart failure
  • mitral regurgitation
  • ventricular arrhythmia
  • heart block
  • rupture
  • dresslers syndrome
66
Q

what can heart failure caused by MI respond to

A

IV furosemide

67
Q

what is required for heart failure treatment

A

oxygen

68
Q

what is an early fatal event that can happen post MI

A

ventricle rupture

69
Q

how can you repair a minor rupture

A

pericardiocentesis followed by surgical repair

70
Q

what valvular disease can occur post MI

A

mitral regurgitation

71
Q

what does cardiac arrest require

A

defibrillation

72
Q

what should ventricular tachycardia post MI be treated with

A

beta blocker
lidocaine
or
amiodarone

73
Q

treatment of post MI AF

A

beta blockers + digoxin

74
Q

what is treatment for heart blocks post MI

A

permanent pacing

75
Q

post-MI lifestyle modifications

A
  • exercise programme
  • dietary recommendations (increase veggies, reduce salt)
  • reduce alcohol
  • stop smoking
  • maintain a healthy weight
  • reduce blood pressure (if high)
  • regulate patients with diabetes
76
Q

post MI drug therapy

A
  • aspirin
  • ADP-receptor blocker
  • oral beta blocker (maintain heart rate)
  • ACE inhibitors / ARB
  • statins
  • aldosterone antagonist
77
Q

whats preferred PCI or thrombolysis

A

PCI