Causes of cardiac arrest Flashcards
How are the distinct categories of ACS initially recognised?
Presence or absence of ST elevation on an ECG
If no elevation then presence of a raised troponin
What does the rupture or erosion of an atherosclerotic plaque within a coronary artery cause?
- acute thrombosis within the vessel lumen with often haemorrhagic extension into the plaque
- contraction of smooth muscle cells within the artery wall resulting in vasoconstriction that reduces the lumen of the artery
- associated partial or complete obstruction of the lumen, often with embolism of thrombus into the distal part of the vessel
What does an ECG show in a STEMI
ST elevation or new LBBB
What indicates a high risk NSTEMI
ST segment depression
Dynamic ECG changes
Unstable rhythm
Unstable haemodynamics
Diabetes
High GRACE score
What suggests myocardial damage in the section of the occluded artery?
Development of Q waves on ECG
Impairment of left ventricular function on ECHO
What is there an acute risk of in the initial phase of STEMI?
VF and VT
In a patient with suspected ACS how quickly should an ECG be performed?
10 minutes
What does the diagnosis of STEMI mandate?
PPCI within 120 minutes
If this cannot be achieved then fibrinolytic therapy should be considered
Reperfusion therapy should not be delayed while awaiting the results of a troponin
Anterior or anteroseptal infarction is seen in which leads? Which vessel does this correspond to?
V1-V4
LAD
Anterolateral infarct is seen in which leads?
V5-V6, I and aVL
Inferior infarction is seen in which leads?
II, III aVF. Lesion is in right coronary artery or the circumflex
Lateral infarction is seen in leads?
V5-V6 and/or aVL Caused by a lesion in the circumflex or diagonal branch of the LAD
How can posterior myocardial infarction appear on ECG?
reciprocal ST depression in anterior chest leads
usually due to right coronary artery occlusion but can be caused by dominant circumflex circulations
How can a posterior MI be confirmed?
By using posterior ECG leads- V8, V9, V10 should be placed in a horizontal line around the chest continuously
What can be used to detect right ventricular infarction?
Two dimensional echocardiography
Right sided precordial leads
The ST segment depression and T wave inversion that may occur in NSTEMI are ____related to the site of myocardial damage than the changes in STEMI
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
What conditions other than ACS may show ST segment depression/elevation
SAH or TBI
What might an ECG of someone with acute PE have?
TWI in leads V1-V4
What condition might cause ST elevation in lead V1 and V2?
Brugada syndrome
What other conditions may cause a raised troponin?
- PE
- aortic dissection
- myocarditis
- acute/chronic heart failure
- arrhythmias
- chronic renal failure
-sepsis
What is directly linked to prognosis in someone with acute chest pain?
LV systolic function
What are some complications of AMI?
VSD
Severe mitral regurg
What are the variables used in GRACE score?
- age
- signs of heart failure
- heart rate at presentation
- bP at presentation
- serum creatinine concentration
- ECG changes
- troponin concentration
- cardiac arrest at presentation
What should be done if ACS is confirmed
- connect patient to cardiac monitor
- aspirin 300mg
- GTN
- pain relief
For patients presenting with STEMI within __ of symptom onset, mechanical or pharmacological reperfusion must be achieved without delay
12h
Call to balloon time
<120 minutes
What should patients be given in addition to aspirin prior to PPCI?
Clopidogrel 600mg
Prasugrel 60mg (not if >75 years <60kg, history of bleeding or stroke)
Ticagrelor
Give all patients receiving a fibrinolytic agent for STEMI:
Aspirin 300mg, ticagrelor 180mg loading doses, or if high bleeding risk aspirin 300mg and clopidogrel 300mg loading doses, or aspirin alone.
Antithrombin therapy
- LMWH IV bolus then sc OR
- UNFRACTIONATED heparin (full dose) OR
-fondaparinux
What are the indications for immediate anti-fibrinolytic therapy in a presentation of AMI
- presentation of AMI within 12 hours of symptom onset when PPCI is not possible within 120 minutes
- ST segment elevation >0.2mV in 2 adjacent chest leads
- > 0.1mV in 2 or more adjacent limb leads
- Dominant R waves and ST depression in V1-V3
- New onset LBBB
What are the absolute contraindications to anti-fibrinolytic therapy?
Previous haemorrhagic stroke
ISchaemic stroke during the past 6 months
CNS damage or neoplasm
Recent (within 3 weeks) surgery, HI or major trauma
Active internal bleeding or GI bleeding within the past 6 months
Known or suspected aortic dissection
Known bleeding disorder
In what percentage of patients receiving a fibrinolytic drug for STEMI is reperfusion not achieved?
20-30%
When should you do an ECG after giving an anti-fibrinolytic
After 60-90 minutes
What suggests failure of antifibrinolytic therapy?
Failure of ST-segment elevation to resolve by more than 50% compared with the pre-treatment ECGs
What is not a reliable indication of reperfusion?
The patients symptoms
What should be done in cases of failed reperfusion?
Transfer for PCI
There is no role for anti-fibrinolytic therapy in which patients?
nstemi or ua
What are the immediate treatment objectives for patients with UA or NSTEMI?
To prevent new thrombus formation
To reduce myocardial o2 demand
How do you prevent new thrombus formation in patients with NSTEMI UA?
Fondaparinux 2.5mg OD
Aspirin 75mg daily after the initial 300mg loading dose
Patients with NSTEMI or UA and are planned for angiography should be given what?
one of
Prasugrel 60mg then 10mg daily maintenance
Ticagrelor 180mg, then 90mg BD maintenance
How can we reduce myocardial O2 demand?
Start beta-adrenoreceptor blockade
Consider diltiazem if B blockers contraindicated
Avoid dihydropyridine calcium channel blockers (nifedipine)
Consider IV nitrate if angina persists
Early introduction of an ACEi
Treat tahyarrhythmia or heart failure promptly
What should patients with UA and a low grace score undergo?
Non invasive imaging
What is appropriate in all patients post ACS?
Continues platelet inhibition- low dose aspirin 75mg daily for life
Clopidogrel for one year 75mg daily
What can an ACE do after an ACS?
Reduce the remodelling that contributes to left ventricular dilatation and impairment, where there is LVSD ACE reduces the risk of heart failure and future AMI and death
Tose with heart failure and reduces LVEF should also be offered (in addition to an ace)
Aldosterone antagonist
What treatment should be started after an acs?
BETAblocker
What is not indicated when an arrhythmia occurs within 24-48h of a confirmed ACS?
An ICD
When is an iCD recommended?
When sustained ventricular arrhythmia occurs more than 24-48h after an acs as an inpatient (unless the arrythmia can be explained by ischaemia and resolved by revascularisation)
Which types of arrest post ACS require an icd?
VF/pVT arrest as a late complication of MI or outside the context of an ACS
What should you check for when an arrhythmia occurs in the context of an acs
Hypokalaemia, heart failure
What does AF in the context of acs suggest?
left ventricular failure
What should be considered if there is no response to atropine in a bradycardic patient with ACS?
Temporary cardiac pacing
What should not be delayed in complete heart block in the context of inferior acs?
PPCI- heart block tends to resolve after this
What does AV block suggest in a patient with acute anterior mi
extensive myocardial injury and poor prognosis- temporary cardiac pacing is usually needed
What should be done if there is a VF/pVT arrest in the cath lab?
3 stacked shocks, if no ROSC then als algorithm should be followed
How can CPR be carried out during PCI
ECMO or mechanical compression device
What does cardiogenic shock consist of?
Hypotension
poor peripheral perfusion
pulmonary oedema
drowsiness
oliguria
What should be considered when cardiogenic shock occurs after AMI
Myocardial rupture
papillary muscle rupture
VSD
What reduces the risk of SCD in long QT syndrome
beta blockade and iCD
