ECG interpretation Flashcards
How do you calculate HR on an ECG?
If regular:
count squares in R-R interval
Divide 300 by this number
If irregular:
Count number of of complexes in one rhythm strip (10s)
Multiply this by 6
Normal HR range?
60-100
Normal cardiac axis
Lead 2 most positive deflection compared to leads 1 and 3
-30 to +90
Right axis deviation
Lead 3 is the most positive, lead 2 and AVF also positive, and lead 1 is negative
+90 to +180
Common in right ventricular hypertrophy
Left Axis deviation
Lead 1 most positive deviation
Leads 2 and 3 are negative
-30 to -90
Common in heart conduction defects
What pathologies (and their parallel signs) might no P-wave indicate?
Sawtooth baseline - Atrial Flutter
Chaotic waves - fibrillation
Flat line - no atrial activity?
Define prolonged PR and what can it show?
PR interval >0.2 seconds (5 squares)
Heart block
How would 1st degree heart block manifest?
fixed prolonged PR (>0.2s)
Occurs between SAN and AVN (in atrium)
How would 2nd degree heart block (Mobitz type 1) manifest?
Increased PR interval until there is a dropped QRS
Occurs in AVN
https://geekymedics.com/wp-content/uploads/2017/01/MobitzType1-1.jpg
How would 2nd degree heart block (Mobitz type 2) manifest?
Fixed PR, with dropped QRS beats (within a fixed ratio)
Occurs after AVN in bundle of his or purkinje
How would 3rd degree heart block manifest?
Complete dissociation between P waves and QRS complexes
Occurs from AV node down
What does a shortened PR indicate?
P-wave initiated closer to AVN - smaller atria
or - There is an accesory pathway (may be associated with a delta wave - for example in WPW syndrome
What might a broad (>0.12s) QRS indicate?
Abnormal sequence
eg ventricular ectopic
Bundle branch block
What might an abnormally narrow QRS indicate?
atrial ectopic
define a small complex
Small complexes are defined as < 5mm in the limb leads or < 10 mm in the chest leads
What can a tall complex indicate?
LVH
What does a Delta wave indicate?
WPW syndrome
What does a pathological Q-wave look like?
> 25% size of following R-wave, or >2mm height + >40ms in width
What does a pathological Q wave indicate?
If diffuse, previous MI
What does poor R-wave progression indicate?
Previous MI or large patient
What can ST elevation indicate?
Anterior MI
LVH
Pericarditis
What can ST depression indicate?
Myocardial ischaemia
What do T-waves represent?
Ventricle repolarisation
What are “Tall T waves”?
> 5mm in limb leads and >10mm in chest leads
What may “Tall tented T waves” indicate?
Hyperkalaemia
Tall T waves indicate hyper acute STEMI
When is inverted T waves a sign?
when in leads other than V1 and Lead III
Give some examples of Inverted T wave associated pathology
Ischaemia PE LVH (lateral leads) Hypertrophic cardiomyopathy (widespread) L/RBBB
What can a Biphasic T-wave indicate?
Hypokalaemia
Ischaemia
What is the J point?
Where the QRS complex becomes the ST segment.
How long should QT interval be?
0.35 - 0.45 seconds
