Week 8 Flashcards
What should you ask yourself about the ST segement?
Is it elevated (+ 1.0 mm)?
Is it depressed (-0.5 mm)?
Where should ST elevation/depression be measured?
At 80ms past the J-point
What should you consider if you see ST elevation?
- myocardial infarction
- left ventricular aneurysm
- pericarditis
- prinzmetal’s angina
- high take off
What is the evolution of myocardial changes in Q-wave MI?
- Develop tall T waves
- Develop ST segment elevation
- ST elevation with T wave inversion
- Q wave formation with ST segment inversion
- Q wave
Does a normal ECG exclude MI?
No -look at ECG and client symptoms
What can an acute MI typically present with?
New onset of LBBB
How does angina chest pain differentiate from MI chest pain?
MI chest pain is more severe and longer lasting
What are the symptoms of a an MI?
Central chest pain, nausea, sweating, vomiting
How long does an episode of angina typically last?
2-10 minutes
What causes angina?
Discrepancy between oxygen demand of the myocardium and oxygen delivery. Typically caused by CAD and can worsened by thrombus formation and vasospasms.
After how long should angina pain be treated as an MI?
20 minutes
What are the 3 pathologic changes of an MI?
- ischemia
- injury
- infarction
What is the zone of infarction?
The area of death where necrosis has occurred. Scar tissue will form here and the damage is irreversible
What causes pathological Q waves?
Zone of infarction. Leads look ‘through’ the non conductive scar tissue.
What is the zone of injury?
Surrounds the zone of infarction and results from prolonged lack of oxygen. It shows as ST elevation on ECG.
What is the zone of ischemia?
The outermost layer resulting from an interrupted blood supply. It shows as T wave inversion on ECG.
After how many hours during an MI is myocardial necrosis inevitable?
6 hours
Do myocardial infarctions cause the same changes in all leads?
No characteristic ECG changes that occur with each type of MI are localised to the leads overlying the infarction site.
What are reciprocal changes?
Opposite changes seen in the leads that are opposite the infarction site.
What is a left ventricular aneurysm?
Late complication of MI (seen in 10% of survivors)
What ECG change does ventricular aneurysm cause?
ST segment elevation in the leads that look at that area
What are the consequences of left ventricular aneurysm?
They are non-contractile and so can lead to myocardial dysfunction and thrombus formation (due to the pooling of blood) and a focus for arrhythmias
What are the 4 characteristics of ST elevation of pericarditis?
- ST elevation is typically wide spread (in all leads that look at the inflamed area)
- The ST segment elevation is typically saddle shaped
- Q waves do no develop
- T wave inversion only happens when ST segement returns to baseline
Is pericarditis a contraindication to ECG testing?
Yes
What leads might you see high take off?
Anterior chest leads
What is another name for high take off?
Early repolarisation
What does high take off always follow?
A downwards S wave
Is high take off associated with reciprocal ST depression?
No
What’s another name for Prinzmetal’s angina?
Vasospastic angina
What is vasospastic angina?
Reversible chest pain caused by lack of blood supply due to coronary artery spasm
When is vasopastic angina most common?
In arteries with already underlying CAD
In which artery is vasospasm most common?
Right coronary artery
Lack of which vitamin is associated with vasospastic angina?
Magnesium
What is the best treatment for vasospasm
Calcium channel blockers - not beta-blockers
Vasospasm results in hypoxia and therefore what other ECG characteristics?
tall t waves/inverted t waves/bundle branch blocks
What is normal ST depression?
0.5 mm during rest and 1mm during exercise
What depression is a stop criteria?
2mm depression
What should be considered on ST segment depression?
- myocardial ischemia
- acute posterior myocardial infarction
- drug toxicity
- ventricular hypertrophy with strain
What is silent ischemia?
lack of oxygen but no chest pain
What group of people may suffer from silent ischemia and why?
Diabetics due to diabetic neuropathy
What is the most common ECG change associated with ischemia?
ST depression
Do downsloping or upsloping ST segments depression have a better prognosis?
Upsloping
What type of infarction causes ST segment depression?
A posterior MI causes reciprocal depression in leads V1-V3
What is LVH/RVH strain characteristics?
1) tall/deep S/R waves
2) ST segment depression
3) T wave inversion
