ECGs Flashcards
Normal duration of a P wave
0.08 to 0.10 seconds
Normal amplitude of a P wave
0.5mm to 2.5mm, rarely over 2mm
Which leads have direct view of the SA node
V1 and V2
If a negative Pā wave is present, where is the ectopic pacemaker located
Left atrium or in the AV junction, with retrograde conduction to the AV node
Normal duration of a QRS complex
0.06 to 0.12 seconds
Normal Q wave depth in relation to the R wave
Less than 25%
Normal T wave duration
0.10 to 0.25 seconds
Normal T wave amplitude
Less than 5mm
Normal PR interval
0.12 to 0.20 seconds
What can a prolonged PR interval represent
- Delayed conduction through the AV node or Bundle of His
What can a shortened PR interval represent
- An ectopic pacemaker close to the AV node or AV junction
- An abnormal conduction pathway which bypasses the AV node
Where is the QT measured
From the first wave of the QRS complex until the T wave returns to baseline
When is a rhythm considered to be irregular
When the shortest and longest R-R intervals vary by more than 0.08 seconds (should not vary by >10%)
What is a first-degree AV block
A constant delay in conduction through the AV node, characterised by abnormally prolonged PR intervals
What is a second-degree type I (Wenckebach) block
A gradual lengthening of the PR interval, until a QRS complex is dropped
What is a second-degree type II block
An altered AV conduction ratio, where PR intervals are equal but QRS complexes are occasionally dropped
What is a third-degree (complete) block
An absence of conduction between the atria to the ventricles, resulting in no relationship between P waves and QRS complexes
What are the characteristics of Normal Sinus Rhythm
Rate: 60-100 Regularity: Regular P wave: Upright, rounded PR Interval: 0.12 - 0.20 seconds QRS Complex: Normal Origin: Sinoatrial node
