ECG Flashcards
What causes potitive inflection?
Depolarisation towards a positve elecrtode
Repolarisation away from a positive electrode
What casues degative inflections?
Depolarisation away from a positive electrode
Repolarisation towards a positive electrode
What does the P wave represent?
Atrial depolarisation
What does the Q wave represent?
Left to right depolarisation of the intraventricular septum
What does the R wave represent?
Depolaristaion of main ventricular mass
What does the S wave represent?
Last past of ventricular depolarisation
Negative as moving away from + electrode
What does the T wave represent?
Ventricular repolarisation
What are segments?
Connect specific parts of the ECG
Should be isoelectric
If elevated/ depressed= diseased
What are intervals?
Time between 2 specific ECG events
Talk about time not elevation/ depression
What does the QRS complex show?
Ventricular depolarisation
What makes up the PR interval and what does it show?
PR wave and PR segment
Time between depolarisation of atria to ventricles
What is the QRS interval and what does it show?
Is the QRS complex
How long the ventricles take to contract
What is the QT interval and what does it show?
QRS complex + ST segment + T wave
Shows how long it takes for ventricles to depolarise and repolarise
How to calculate QT interval?
If normal rhythm approximately 0.5 RR
Between 0.33 and 0.44 secs
If tachy or Bradi use formular to take intno account changes in HR
How to calculate HR with a regular rhythm?
300/ no big boxes between beats
R-R
How to calculate HR with irregular rhythm?
Calculate no beats on ECG rhythm strip (10 secs)
Multiply by 6
How to determine if in sinus rhythm?
Look at Lead 2
- Regular rhythm (R waves)?
- Normal HR (60-100)?
- P waves? (Present and upright)?
- P waves all followed by QRS?
- Normal QRS duration? (Not larger than 3 small boxes)
- Normal PR interval (3-5 small boxes)?
What is the normal PR interval?
3-5 small boxes
WHat is the normal QRS interval?
Less than 3 small boxes
What is the normal QT interval?
- Normal HR: less than half RR
- Abnormal HR: use correction formula
What leads show the inferior surface of the ventricles?
2,3, aVF
What leads show the ventricular septum?
V1, V2
What leads show the anterior surface of the ventricles?
V3, V4
What leads show the right ventricle and septum?
V1, V2, aVR
What leads show the apex and anterior surface of the ventricles?
V3, V4
What leads show the lateral surface of the ventricles?
1, aVL, V5, V6
