4. Cardiac causes of cardiac arrest

Question 1

types of ACS?

Answer 1

STEMI
NSTE ACS (NSTEMI, unstable angina)

Question 2

ACS in most cases results from ___ ___ disease, and is initiated by the rupture of erosion of an ____ ____ within a coronary artery

Answer 2

coronary artery
atherosclerotic plaque

Question 3

describe the sequentia of events that leads to ACS then an atherosclerotic plaque within a coronary artery erodes/ ruptures?

Answer 3

1) acute thrombosis within the vessel lumen
2) contraction of smooth muscle cells in the artery wall resulting in vasoconstriction that reduces the lumen of the artery
3) associated partial or complete obstruction of the lumen, often with embolism of thrombus into the distal part of the vessel

all leads to sudden and critical reduction in blood flow to the myocardium

Question 4

T/F: you may see ECG changes in unstable angina

Answer 4

true- may be evidence of acute myocardial ischaemia (usually ST-segment depression) or show non-specific abnormalities (e.g. T wave inversion)

Question 5

all pts with unstable angina should have their risk assessed with an established risk calculator e.g.

Answer 5

GRACE

Question 6

what ECG findings are suggestive of STEMI?

Answer 6

ST segment elevation or new LBBB

Question 7

T/F: the amount of troponin released reflects the amount of myocardium damaged

Answer 7

true

Question 8

left untreated, a STEMI will lead to the development of __ waves on the ECG

Answer 8

Q

Question 9

T/F: confirmation of elevated troponin is required to make the initial diagnosis of STEMI

Answer 9

False

Question 10

clinical signs on examination of aortic dissection?

Answer 10

hypotension, loss of peripheral pulse, R-R delay, aortic regurgitation, signs of stroke from carotid artery involvement

Question 11

treatment of STEMI?

Answer 11

reperfusion therapy
ideally PCI
if that can’t be achieved within 120 minutes of onset of CP, fibrinolytic therapy should be considered

Question 12

anteroseptal infarction - which ECG leads and which coronary artery?

Answer 12

V1-4 (extension to V5-6, I and aVL indicates anterolateral)
LAD

Question 13

an ANTERIOR/LATERAL/INFERIOR infarct has a worse prognosis

Answer 13

anterior

Question 14

inferior infarction - which ECG leads and which coronary artery?

Answer 14

II, III and aVF
Right coronary or, less commonly, the circumflex artery

Question 15

lateral infarction - which ECG leads and which coronary artery?

Answer 15

V5-6, and/ or I/ aVL
Circumflex artery or diagnoal branch of the LAD

Question 16

posterior infarction - which ECG leads and which coronary artery?

Answer 16

reciprocal ST-segment depression in the anterior leads
Most often right coronary artery but can also be a dominant circumflex artery

Question 17

what ECG changes reflect posterior Q wave development?

Answer 17

development of a dominant R wave in V1-V2 (reflects posterior Q wave development

Question 17

suspicion of posterior ECG can be confirmed by repeating the ECG with what change?

Answer 17

addition of posterior leads (V7-10)

Question 18

Right ventricular infarction may be present in up to one third of patients with ____ and ____ STEMI

Answer 18

inferior and posterior

Question 18

a diagnosis of extensive RV infarction is suggested by what clinical signs?

Answer 18

fluid responsive hypotension and signs of high systemic venous pressure (e.g. jugular venous distension) without pulmonary congestion

Question 19

extensive RV infarction may be seen on an ECG when ST-segment elevation in what lead accompanies an inferior or posterior STEMI?

Answer 19

V1

Question 20

the ECGs of people with SAH or TBI can show ECG changes including…

Answer 20

ST segment depression or elevation, or T-wave inversion

Question 21

what ECG changes can happen in people with major PE?

Answer 21

T wave inversion in leads V1-4

Question 22

T/F: the greater the troponin, the greater the risk of a further event or death

Answer 22

true

Question 23

what other life threatening conditions presenting with chest pain can have elevated troponins?

Answer 23

including PE, aortic dissection and myocarditis

Question 24

what other conditions can present with elevated troponin?

Answer 24

acute or chronic heart failure, arrhythmias, chronic renal failure and acute sepsis

Question 25

what additional ECG leads can be helpful in detected an right ventricular infarction?

Answer 25

right precordial leads, esp V4R

Question 26

T/F: the ST-segment depression and T wave inversion that may occur in NSTEMI are less clearly related to the site of myocardial damage than the changes in STEMI

Answer 26

true

Question 27

What is the most important non-invasive imaging modality in the acute setting for ACS?

Answer 27

ECHO (left ventricular systolic function is directly related to prognosis and, in someone with acute chest pain, regional wall motion abnormalities increase the likelihood of an ACS)

Question 28

ECHO can be used to diagnose complications of an acute MI such as (1) or (2), both of which require urgent surgical correction

Answer 28

1) ventricular septal defect 2) severe mitral regurgitation

Question 29

most accurate risk stratification score, both on admission and over 6 months?

Answer 29

GRACE

Question 30

What variables increase risk of major bleeding following ACS treatment?

Answer 30

increased age known bleeding complications renal impairment low body weight

Question 31

immediate treatment for ACS?

Answer 31

MONA Morphine (IV opiates given with antiemetic) Oxygen (only if sats <94%) Nitrates (sublingual GTN - unless hypotensive) Aspirin 300mg oral (crushed or chewed)

Question 32

Treatment options for STEMI (or AMI with new LBBB)

Answer 32

if within 12 hr symptom onset, mechanical or pharmacological reperfusion without delay - PPCI (preferred method) - fibrinolytic therapy

Question 33

T/F: emergency PCI may be considered >12hr from symptom onset

Answer 33

true - if clinical or ECG evidence of ongoing ischaemia

Question 34

what is the target 'call-to-balloon' time in a STEMI?

Answer 34

<120mins (if PPCI can't be achieved in this timeframe, consider fibrinolytic therapy)

Question 35

in addition to aspirin, all pts should be given one of the platelet ADP receptor blockers prior to PPCI e.g.

Answer 35

clopidogrel 600mg prasugrel 60mg ticarelor 180mg

Question 36

What antithrombotic therapy is contraindicated if >75y/o, <60kg or history of bleeding or stroke

Answer 36

prasugrel

Question 37

T/F: fibrinolytic therapy is less effective than PPCI in a STEMI

Answer 37

true

Question 38

all pts receiving a fibrinolytic agent for STEMI must receive: ___ 300mg and ___ 180mg also antithrombin therapy (to minimise risk of further occlusion) e.g.

Answer 38

aspirin 300 ticagleror 180 (or clopidogrel 300 if high bleeding risk) antithrombin therapy > LMWH OR unfractioned heparin OR fondaparinux

Question 39

Typical indication for immediate fibrinolytic therapy for acute myocardial infarction 1) presentation within __ hours of onset cardiac CP and PCI not possible within ___ minutes AND 2) ST segment elevation >__ small box(es) in 2 adjacent chest leads OR 3) >___ small box(es) in 2 or more adjacent limb leads OR 4) dominant R waves and ST depression in ___ - ___ (posterior infarct) OR 5) new onset ____

Answer 39

1) 12, 120 2) 2 3) 1 4) V1-3 5) LBBB

Question 40

absolute contraindications for fibrinolytic therapy

Answer 40

prev. haemorrhagic stroke ischaemic stroke during past 6 months CNS damage or neoplasm recent (3week) major surgery, HI, or other major trauma active internal bleeding or GI bleeding within the past month known or suspected aortic dissection known bleeding disorder

Question 41

T/F: in 5% of pts receiving fibrinolysis for STEMI, reperfusion is not achieved

Answer 41

false- 10-30%

Question 42

Failure of ST-segment elevation to resolve by more than __% compared to pre-treatment ECG suggests that fibrinolytic therapy has failed to re-open the culprit artery

Answer 42

50 (symptoms are not a reliable guide to reperfusion- many pts will have had opiate analgesia)

Question 43

What to do in cases of failed reperfusion (or re-occlusion and further infarction with recurrent of ST-segment elevation?

Answer 43

transfer without delay to a cardiac catheter lab for PCI ("rescue PCI")

Question 44

T/F: there is no evidence of benefot from immediate reperfusion therapy in most patients with NSTE ACS

Answer 44

true - there is no role for fibrinolytic therapy in these patients

Question 45

1) to prevent further thrombus formation following initial treatment in NSTE ACS, given ___ 2.5mg daily + ___ 75mg daily after the initial 300mg loading dose 2) in addition to aspirin, pts with elevated trop (NSTEMI) or are planned for angiography +/- revascularisation should be given one of the platelet ADP receptor blockers e.g. ____ 60mg, _____ 180mg or ____ 300mg

Answer 45

1) fondaparinux 2.5mg aspirin 75mg 2) prasugrel 60mg ticagrelor 180mg clopidogrel 300mg

Question 46

Prasugrel contraindications

Answer 46

>75 years <60kg history of bleeding or stroke

Question 47

in certain high-risk pts with NSTE-ACS, if early PCI is planned, a _____ inhibitor may be considered

Answer 47

glycoprotein IIb/IIIa

Question 48

Treatments to reduce myocardial oxygen demand in NSTE ACS? 1) start ______ (consider diltiazem if contraindicated) 2) avoid ______ e.g. nifedipine 3) consider IV _____ infusion if angina persists or recurs after s/l 4) consider early introduction of _______, esp if there is LVSD/ heart failure

Answer 48

1) beta blocker 2) dihydropyridine CCBs 3) nitrate 4) ACEI

Question 49

1) Patients with suspected unstable angina without high risk features (ECG and trop normal, low GRACE score) should undergo further risk assessment by what means? 2) what about pts with UA and high risk features or NSTEMI?

Answer 49

1) non-invasive imaging 2) consider for early investigation by percutaneous coronary angiography

Question 50

NSTEMI: require assessment by coronary angiography within ___ hours of presentation

Answer 50

72

Question 51

What measures are included in secondary prevention for ACS?

Answer 51

- antithrombotic therapy (aspirin 75mg OD for life + clopidogrel 75mg OD/prasugrel 10mg OC/ ticagrelor 90mg BD for at least a year if undergoing PCI - preservation of LV function with use of an ACEI (+aldosterone antagonist for those with HF with reduced LVEF) - beta blockade (reduces mortality + size of subsequent MI) - high dose statin for cholesterol reduction (+low fat, high fibre diet and regular exercise) - smoking cesssation - antihypertensive treatment

Question 52

T/F: if an arrhythmia (inc VF/pVT) occurs within 24-48hrs of confirmed ACS, an implantable ICD is indicated

Answer 52

false - NOT indicated unless the pt has persistent severely impaired LV function at least 4 weeks post ACS (ICD normally indicated if the arrhythmia occurred >24-48hr after an ACS)

Question 53

What arrhythmia on an ECG is commonly seen after reperfusion and may provide strong indication that thrombolysis has been achieved

Answer 53

accelerated idioventricular rhythm (often transient and don't require treatment)

Question 54

AV block in the context of an inferior acute MI

Answer 54

inferior treat symptomatic bradycardia with atropine, consider temporary pacing only if bradycardia and hypotension persist after atropine

Question 55

T/F: AV block in the context of acute inferior AMI usually implies extensive myocardial injury and poor prognosis

Answer 55

false- usually transient in the context of INFERIOR AMI, treat with atropine and consider pacing only if bradycardia persists after atropine AV block in acute ANTERIOR AMI usually implies extensive myocardial injury and poor prognosis - often atropine resistant, do not delay pacing

Question 56

management of VF/VT cardiac arrest that occurs in the cath lab?

Answer 56

up to 3 stacked shocks should be attempted - if there's no ROSC, commence the standard ALS algorithm

Question 57

Treatment of patients presenting with heart failure complicating AMI? 1) for immediate symptomatic treatment 2) to maintain symptom control 3) for patients with heart failure or significant LV systolic impairment (EF <40%)

Answer 57

1) loop diuretic e.g. furosemide and/or GTN for 2) regular loop diuretic, ACEI titrated as tolerated (ARB if not tolerated), beta-blocker 3) aldosterone antagonist (eplerenone or spironolactone)

Question 58

how does cardiogenic shock present

Answer 58

hypotension with poor peripheral perfusin, often with pulmonary oedema, drowsiness/ confusion, oliguria very high mortality

Question 59

T/F: syncope that occurs during exertion is a reassuring feature

Answer 59

false - exertional syncope should raise concern ?cardiac cause

Question 60

In many people with a long QT syndrome, ____ blockage may be the only treatment needed to reduce risk of SCD to a minimum

Answer 60

beta (ICD may be needed if this is insufficient)

Question 61

What intervention restores life expectancy to normal in complete AV block?

Answer 61

pacemaker implantation