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
