ECG Flashcards
How long/wide is a normal PR interval?
3-5 small squares (0.12-0.20 sec)
How deep/wide is a normal Q wave? What leads is a Q wave normally seen in?
- <0.03 sec
- <1/3 the height of the following R wave
- Normally seen in I, aVL (sometimes V1-2)
How long is the normal QT interval? What is the formula for the rate-corrected variant (QTc)
- 0.410 sec (<1/2 R-R)
- QTc = QT + 1.75(ventricular rate - 60)
How wide is a normal QRS complex? How tall in the limb leads?
- 0.06 - 0.11 sec (1.5 - 3 small squares)
- > 5 mm tall in the limb leads
What direction isthe RA depolarisation vector?
Right, down, posterior
What direction is the LA depolarisation vector?
Left, down , back
What direction is the septal depolarisation vector?
Right to left
What direction is the main ventricular depolarisation vector?
Inferior, posterior, left
What direction is the late ventricular depolarisation vector?
Up, right and posterior
What are the ECG characteristics of a wandering atrial pacemaker? How is it distinguished from a multifocal atrial tachycardia?
- < 100 bpm with at least 3 different P wave morphologies
- MAT - > 100 bpm
What are the ECG characteristics of atrial flutter?
Regular saw-toothed flutter waves with regular ventricular response
What are the ECG characteristics of atrial fibrillation?
- No discernable P waves, random QRS
How fast is a junctionally-paced rhythm on an ECG? A ventricular paced rhythm?
- 40-60 bpm
- 20-40 bpm
What is 1st degree heart block?
- Prolonged PR interval (> 0.20 or 5 small squares)
What is Mobitz I second-degree heart block?
- Lengthening PR until a beat is dropped after a P wave
What is Mobitz II second-degree heart block?
- Fixed PR interval and P:QRS ratio, but a QRS is dropped in a regular pattern after a P wave
What is third-degree heart block? How is it different to AV dissociation?
- Different P and QRS rates
- AV dissociation if rate is the same
What might cause an ST segment to be concave-up shaped?
- Pericarditis
- Early repolarisation
- Strain
What might cause an ST segment to be concave-down shaped?
Strain
What might cause an ST segment to be flat and depressed?
Subendocardial ischaemia
What might cause an ST segment to be flat and elevated?
Myocardial injury
What might cause an ST segment to tombstone?
- Infarction
- Aneurysm
What is the normal shape and height of T waves on an ECG?
- Asymmetrical
- < 6 mm in limb leads
- < 12 mm in precordial leads
What might be the cause of tall, peaked, narrow T waves on an ECG?
Hyperkalaemia
What can tall, symmetrical T waves signify on an ECG?
Injury
What are the ECG characteristics of pericarditis?
- Global ST elevation
- Concave-up ST segments
- PR depression
- Tachycardia
What are the ECG characteristics of a right-bundle-branch block?
- QRS >= 0.12 sec
- Slurred S in I, V6
- Positive complexes in V1 and RSR’ morphology
What are the ECG characteristics of a left-bundle-branch block?
- My, what an ugly ‘gram
- QRS >= 0.12 sec
- Broad R in V1, V6
- Broad S complex in V1
What are the ECG characteristics of a left anterior hemiblock?
- LAD -30 to -90
- qR or R complex in I
- rS in III
What are the ECG characteristics of a left posterior hemiblock?
- Axis 90-180
- S complex in I
- q complex in III
- No RAE or RVH present
What are the ECG characteristics of a left atrial enlargement?
- P wave > 0.12 sec and notched greater than 0.04 in limb leads
What are the ECG characteristics of a right atrial enlargement?
- Peaked P wave (> 2.5 mm) in limb leads
What are the ECG characteristics of LV hypertrophy?
- (S wave in V1 or V2) + (R wave in V5 or V6) > 35 mm
- AND/OR
- any precordial > 45 mm
- R wave in aVL >= 11mm
- R wave in I >= 12 mm
- R wave in aVF >= 20 mm
What are the ECG characteristics of a RV hypertrophy?
- R:S >=1 in V1 and/or V2
