Acute coronary syndrome Flashcards
What is acute coronary syndrome?
Obstruction or occlusion of blood flow to the heart
a) STEMI
b) NSTEMI
c) Unstable angina
How might ACS present?
S: central/ retrosternal
O: at rest
C: tight, heavy, crushing
R: to jaw or left arm or back
A: not relieved by GTN - only opiates relieve pain
T: varies
E: none
S: ranges, stereotypically very severe
Associated symptoms: dyspnoea, sweating, N&V, impending doom
Differentials for MI?
- Pericarditis
- Aortic aneurysm
- Endocarditis
- Tamponade
- PE
- Anxiety
Pathophysiology of raised troponin
Cardiomyocytes die and release actin & myosin
Actin has troponin attached to it - it is released when the myocytes die
Troponin is an indicator of cardiac muscle death
Other causes of raised troponin
Cardiac causes
- Direct contusion of heart during trauma
- Aortic dissection
- HOCM
- Aortic stenosis/ regurg
- Rhabdomyolysis
- Myocarditis
Non-cardiac causes
- Renal failure
- PE
- Sepsis
- Burns
- Amyloidosis
- Stroke
- Subarachnoid haemorrhage
When do troponin levels peak following MI?
18-24hrs after and remain elevated for 10 days
Which chronic condition gives an elevated baseline troponin?
Renal failure
Types of MI based on cause
Type 1 = spontaneous MI due to primary coronary event: commonly a plaque ruptures leading to platelet aggregation and thrombus formation
Type 2 = secondary to ischaemia because o2 supply doesn’t meet demand e/g/ following a GI bleed or sepsis
Type 3 = diagnosed following sudden cardiac death
Type 4 = MI secondary to PCI
Type 5 = MI secondary to CABG
In which patients might ACS present atypically?
Women: atypical pain
Diabetics: may not have any pain
Elderly: only symptoms can be syncope + fatigue
What signs can be used as evidence of risk factors for ACS?
Complications of DM
HTN
Tar staining on fingers
Xanthelasma
Investigations for ACS
Bedside:
ECG
Bloods:
Troponin
Imaging:
Chest x-ray
Angiogram
Echo
ECG findings in ACS
NSTEMI: ST depression/ T wave inversion + angina-like pain = highly suggestive of ACS
STEMI: ST elevation is evidence of a significant coronary vessel being occluded
- Over time the ST segment reduces and T wve inversion occurs after a few days
- Months later pathological Q waves develop
Based on ECG when is a STEMI diagnosed?
>1mm elevation in 2 limb leads and >2mm elevated in 2 continuous chest leads
What is an anterior MI?
Usually due to occlusion of the left anterior descending artery aka widow maker
Anterior MI ECG
Proximal LAD infarct: ST elevation in V1-V6 + possibly lead 1 & aVL
Mid LAD: ST elevation in V3-V6
What are the inferior leads?
II, III, aVF
Remember 2-3 feet
II-III avFeet
Feet are inferior
So inferior leads = II & III & avF
What are the lateral leads?
I, aVL, V5, V6
1 hand with 5-6 fingers
Lead I, lead V5 & V6
Hand = lateral
aVLateral
What are the anterior/ septal leads?
V1-V4
How do we know if the ECG is showing a sinus rhythm?
If there is a P wave, it is sinus
Best leads to find a P wave?
Lead II + lead V1
‘You always want II put the P in the V1gina’
If you find a P wave, its sinus
No P waves + irregularly irregular rhythm?
Atrial fibrillation
No p waves + sawtooth pattern + regular?
Atrial flutter
PE on ECG?
S1 Q3 T3
Deep S wave in lead 1
Deep Q wave in lead 3
Inverted T wave in lead 3
ECG in hypokalaemia?
Large U wave - looks like a second T wave
ECG in hyperkalaemia
Tall, tented T-waves
Can be tricky to differentiate tented T waves from ST segment elevation but imagine tented T waves ir like thin daggers whereas ST segment elevation is more blunted
TCA toxicity causes what on an ECG?
Broad QRS
Can cause arrhythmia and death
Reversed using bicarb
Which ECG abnormality is associated with lung disease e.g. COPD?
MAT
Multifocal atrial tachycardia
Which 2 ECG findings would prompt you wanting to go for PCI?
STEMI
New LBBB
