12 lead ECG interpretation Flashcards
Evidence of MI is required in ____ ____ ____ before it is deemed diagnostic.
Two continuous leads
Pts with RV infarctions are often ____ and ____.
Hypotensive and bradycardic
Pts with LV infarctions are often ____ and ____.
Hypertensive and tachycardic
Leads 1, aVL, V5 and V6 are facing which artery?
Left circumflex
Leads II, III, and aVF are facing which artery?
Right coronary artery
Leads V1, V2, V3, and V4 are facing which artery?
Left anterior descending artery
What are the reciprocal leads of II, III, and aVF?
I and aVL
What are the reciprocal leads of V1-V4?
II, III, and aVF
What are the reciprocal leads of I, aVL, V5, and V6?
II, III, and aVF
Is the degree of ST depression measured?
No
Ventricular pacemakers will cause abnormal ST segment ____.
Elevation
What are the ventricular escape rhythms?
- Idioventricular rhythms
- Permature ventricular contractions
- Third degree heart block
What two things indicate pericarditis on a 12 lead ECG?
Elevation in all fields and possible PR depression
What are the differences in chest pain between STEMI and pericarditis?
STEMI
- Dull/heavy/crushing
- Constant or unchanged with movement
Pericarditis
- Sharp and severe
- Increased with supine posturing/breathing/swallowing
- Partially alleiviated by sitting and leaning forward
What are the differences in ECG readings between STEMI and pericarditis?
STEMI
- ST elevation in localised leads
- May show reciprocal changes
- ST segment often convex or slightly concave
Pericarditis
- ST elevation usually global
- No reciprocal changes if localised to one region
- ST segments usually concave or saddle-back
- Possible PR interval depression
What are the signs of dissecting thoracic aortic aneurysm?
- Sharp tearing pain
- Migratory in about 70% cases
- Poor pain relief with narcotic analgesia
- Usually has history of ongoing hypertension
- Very rare in patients <50
- May rarely also be accompanied by symptoms consistent with CVA
- 0.9-2.4% will have ECG changes consistent with STEMI (these may be difficult to discern)
What is left ventricular hypertrophy usually caused by?
Chronic hypertension and LV enlargement
What ECG changes are consistent with left ventricular hypertrophy?
- QRS complex >30mm in V5 and V6
- Deep S waves in VI and V2
- ST segment in chest leads can be elevated by 2mm
LVH is usually seen in which demographic?
Elderly pts
Benign early repolarisation (BER) is usually seen in what kind of patient?
Fit healthy young adults
What ECG changes are consistent with BER?
Small concave ST segment changes of approximately 1 mm in no specific lead groups with no reciprocal changes
How does a ventricular aneurysm alter an ECG?
Old anterior AMIs can cause bulging in the left ventricular wall (ventricular aneurysm). This alters cardiac vectors, resulting in permanent ST segment elevation in the affected area that can be difficult to differentiate from an acute ischemic event.
How might a ventricular aneurysm be differentiated from an AMI?
- Hx of AMI?
- No reciprocal changes
- Ventricular aneurysm elevation is rarely convex
What is the definition of left bundle branch block (LBBB)?
Electrical conduction is blocked through the left bundle branch
True or false: LBBB may be chronic or acute.
True
What kind of infarct can cause LBBB?
Anterior infarct (high mortality rate)
Is LBBB an indication or contraindication for thrombolysis?
Contraindication
What differentiates between LBBB and RBBB on a 12 lead ECG?
LBBB: the last section of the QRS points downwards in V1
RBBB: the last section of the QRS points upwards in V1
