Chapter 4: Cardiac Causes of Cardiac Arrest Flashcards
How can acute coronary syndrome be split up?
STEMI
Non ST Elevated acute coronary syndromes:
- NSTEMI
- Unstable angina
What can be used to determine between STEMI and NSTEMI?
ST elevation or new LBBB = STEMI
Other ECG changes = NSTEMI/Unstable angina
How do you differentiate between unstable angina and NSTEMI?
Troponin release
What may indicate that a non-ST elevated ACS may be high risk?
- ST depression
- Dynamic ECG changes (different from baseline)
- ** Unstable rhythm**
- Unstable haemodynamics
- Diabetes
- High GRACE score
Which groups of people may present with ACS less typically?
Females
Elderly
Diabetics
What are some atypical symptoms of ACS?
- Indigestion type pain
- Pain radiate to throat, into one or both arms, into back or upper abdomen
- ASx
What ECG changes can an NSTEMI/unstable angina show?
Normal
ST Depression
Non specific abnormalities - t wave inversion
When is risk of progression from NSTEMI to full occlusion highest?
First few hours, days and months
What is there a substantial risk of in the acute phase of a STEMI?
- VF
- VT
- Sudden death
What ECG changes may be seen in a STEMI?
- ST elevation
- New LBBB
- Pathological q waves
- T wave inversion
- Hyperacute t waves (v early)
How quickly do you aim to give PCI in a STEMI? What should you do if this can not be achieved?
Within 120 minutes of onset of chest pain
Fibrinolytic therapy
Which leads indicate where an infarct may be?
Anterior - V1-4 = LAD
Inferior - II, III, AVF = RCA
Lateral - I, AVL, V5-6 = Left Circumflex
Posterior - Reciprocal changes to anterior (ST Depression in V1-4) = RCA
What is important to know about posterior MI’s?
Must confirm with posterior leads
Risk of bradycardia as SAN may be affected
What other conditions can cause acute ST depression or t wave inversion?
- Subarachnoid haemorrhage
- Traumatic brain injury
- Major PE - t wave inversion
Why is echocardiography useful in acute ACS?
- Confirm LV systolic Fx - related to prognosis
- Can prompt diagnoses of cardiomyopathy, valve disease, pericardial disease, aortic dissection and PE
- Can confirm RV dilatation & impairment
What are the GRACE and CRUSADE scores?
GRACE - predict risk of adverse outcome
CRUSADE - Risk of major bleeding during hospital admission following ACS
Within what time frame should reperfusion be post STEMI without delay?
If presenting within 12 hours - PCI or fibrinolysis
What anti-thrombotic therapy should patients having a PCI be given and what dose?
Aspirin 300mg + 1 of
- Clopidogrel 600mg
- Prasugrel 60mg (not if >75, <60kg or hx of bleeding/stroke)
- Ticagrelor 180mg
Anticoag with heparin is given in Cath lab - Bivalirudin is alternative
In high-risk, glycoprotein IIb/IIIa inhibitor may be given
What are the typical indications for fibrinolytic therapy?
1 of:
- STEMI >0.2mV in 2 adjacent chest leads or >0.1mV in 2 adjacent limb leads
- Dominant R waves and ST depression in V1-3 (post MI)
- New onset LBBB
What is given alongside fibrinolytic therapy for STEMI?
Summary Rx - 3 points
- **Aspirin 300mg ** loading dose AND
- Clopidogrel 300mg loading dose AND
- Antithrombin therapy: LMWH, unfractionated heparin or fondaparinux
Describe the repercussion flow diagram for a patient with a STEMI
Hospital provide PPCI - immediate PPCI
No PPCI available within acceptable time frame –> fibrinolysis
Fibrinolysis fail –> transfer to PCI hospital
Fibrinolysis successful –> angiography ± PCI during same admission
What are the absolute contraindications for fibrinolytic therapy?
- Previous haemorrhagic stroke
- Ischaemic stroke during last 6 months
- CNS damage/neoplasm
- Recent major surgery, trauma or head injury (<3wk)
- Active internal bleeding (not menses)
- GI bleed within past month
- Known/suspected aortic dissection
- Known bleeding disorder
What are the relative contraindications for fibrinolytic therapy?
- Refractory HTN >180 mmHg
- TIA <6months
- Oral anticoagulant Rx
- Pregnancy or <1wk post partum
- Traumatic CPR
- Non-compressible vascular puncture
- Active PUD
- Advanced liver disease
- Infective endocarditis
- Previous allergic reaction to fibrinolytic drug
What may suggest that fibrinolytic therapy has failed?
- Record ECG 60-90mins post.
- Failure for ST elevation to resolve by >50% compared to pre-treatment
How are patients with a non ST elevated ACS treated to prevent thrombus formation?
- SC LMWH therapeutic dose 12hr or Fondaparinux OD
- Aspirin 300mg loading then 75mg daily
If NSTEMI or planned for angiography ± revascularisation
- Clopidogrel 300mg (or 600mg loading) then 75mg daily
- Prasugrel 60mg then **10mg daily **
- Ticagrelor 180mg then 90mg BD
Can consider glycoprotein IIb/IIIa inhibitor
How are patients with a non ST elevated ACS treated to reduce myocardial O2 demand?
- Beta blockers - diltiazem if BB CI
- Avoid DHAP Ca2+ blockers
- IV nitrate infusion if angina persist
- Consider ACE inhibitor - LV impairment or heart failure
- Rx Cx
How quickly should a patient with an NSTEMI have coronary angiography?
Within 72h of presentation
Which ventricular arrhythmia’s can complicate ACS?
- Cardiac arrest with VF or pVT - presentation:
- If VF/pVT occur within 48h of STEMI & recovery uncomplicated - risk of recurrence low
- VF/pVT in context of Non ST elevated ACS - risk of further ventricular arrhythmia
- If ventricular arrhythmia late complication - see by rhythm specialist for ICD implantation
Which other arrhythmia’s may occur in context of ACS?
AF - indicate left ventricular failure
AV block - inferior AMI
How should AV block in context of ACS be managed?
- Treat bradycardia with atropine
- Consider temporary pacing if this fails
- PCI typically resolve heart block
What are the complications of ACS?
- Arrhythmia
- HF
- Cardiogenic Shock
Sudden Cardiac Death
How can cardiogenic shock due to ACS be managed?
- Inotropic therapy - adrenaline
- Intra-aortic balloon pumping
- Mechanical circulatory/ventilatory support
What are some other causes of sudden cardiac death and how do they cause cardiac arrest?
Long + Short, AABCD - HH - W
- Long QT - Torsades, VT, VF
- Short QT - Torsades, VT, VF
- Aortic stenosis - HF, VT, VF
- Arrhythmogenic RV cardiomyopathy - VT, VF
- Brugada
- Catecholaminergic polymorphic VT - Torsades
- Dilated cardiomyopathy - VT, VF
- HOCM - VT, VF
- High grade AV block - asystole (can Torsades/VT/VF)
- WPW - AF transmit to ventricles - VT, VF
