Flashcards in Acute Coronary Syndrome and Acute Myocardial Infarction Presentation and Investigation Deck (33)
What is an acute coronary syndrome?
Any sudden cardiac even suspected or proven to be related to a problem with the coronary arteries
What is myocardial infarction?
Coronary cell death due to ischaemia
What are the causes of myocardial infarction?
Complete coronary artery occlusion
Partial or transient complete coronary artery occlusion
What are the causes of MI not related to coronary atherosclerosis?
Embolism of material down a coronary artery
Inflammation of coronary arteries
Radiotherapy to the chest causing fibrosis and stenosis of coronary arteries
What are some causes of coronary vasospasm?
What artery is affected in an inferior MI?
Right coronary artery
What artery is affected in an anterior MI?
Left anterior descending coronary artery
What artery is affected in a lateral MI?
Circumflex coronary artery
What can a posterior MI be easily missed?
As there are no ECG leads on the posterior chest
Why are some inferior changes also seen in a posterior MI?
As posterior wall is usually supplied by the right coronary artery
What is a STEMI caused by?
A completely occluded artery
What does a STEMI cause?
Outgoing myocyte death
What needs to be done ASAP in a STEMI?
Coronary artery needs to be opened with reperfusion therapy, mechanically in cath lab or pharmacologically
What is the difference in patients affected by NSTEMI compared to STEMI?
Patients with NSTEMI tend to be older, more likely to have had a previous MI and are more likely to have had previous CABG or PCI
What is the common pathogenesis of NSTEMI?
Atherosclerotic plaque rupture or erosion
Superimposed platelet aggregation and thrombosis
Vasospasm and vasoconstriction
Subtotal or transient total occlusion of vessel
What are the risk factors of MI?
Known heart disease
FH of premature heart disease
What is the typical clinical presentation of an MI?
Chest pain - central crushing/heavy
May radiate to neck/arm/jaw
Often described as discomfort more than pain
May be associated with nausea, sweating and breathlessness
What will the initial ECG of a complete coronary artery occlusion show?
What will the ECG show at 3 days?
Will show Q waves at 3 days
May also show hyper-acute T waves
What changes will be seen on the ECG of a partial coronary artery occlusion?
Initial ECG will show no ST elevation and no Q waves at 3 days
May show ST segment depression or T wave inversion on the initial ECG
May be normal
What is the difference between a STEMI Q wave MI and a NSTEMI non-Q wave MI?
STEMI Q wave MI is transmural
Non-Q wave MI is subendocardial
How is an MI diagnoses?
Detection of cardiac cell death through positive cardiac biochemicals (troponin) and one of;
Symptoms of ischaemia
New ECG changes
Evidence of coronary problem on coronary angiogram or autopsy
Evidence of new cardiac damage on another test
What are some non-cardiac causes of troponin rise?
What agents are given as a bolus in thrombolysis?
Alteplase and streptokinase are older agents
When is thrombolysis contraindicated?
Recent stroke or previous intracranial bleed
When is caution needed in thrombolysis?
What are the advantages and disadvantages of thrombolysis?
Works if given very early
More likely to cause bleeding problems
May not work, especially in delayed presentation
When should patients be referred to the cath lab?
If they can get there within 2 hours of STEMI
What is the general management of a suspected acute coronary syndrome?
Admission to hospital
O2 if levels are low
What investigations should be done in suspected acute coronary syndrome?
Serial ECGs, consider posterior leads
Check for anaemia
Kidney function tests
Thyroid hormone levels