L01: Dysrhymias Flashcards
What does the p wave represent
Atrial contraction
What does the qrs complex represent
Ventricular contraction (depolarisation)
What does the t wave represent
Ventircular (relaxation) repolarisation
How many ecg electrodes are in a 12 lead ecg
10 electrodes
6 on the chest
1 for each limb (4 in total)
What is the standard paper speed for an ecg
25mm/s
What are the steps to interpreting an ECG
- Patient details, dob, check when the ecg was taken, assess the changes, check the speed is 25mm/s
- Heart rate
- Look at the axis deviation
- Is there electrical activity
- Is there atrial activity- p wave
- Is the qrs complec regular
- Is the qrs complex narrow or broad
- Is the atrial activity related to the ventricular activity
What is the normal heart rate
60-100
How can we calculate the heart rate
Multiply the qrs complex number by 6 or
300 Divide the range of squares between r waves if sinus rhytm
If its irregular what do we need to determine
If the rhythm is irregulary irregular or regularlry irregular
How big should a qrs complex be
Betwen 0.5 to 3 small squares
What are the causes of a broad qrs complex (greater then 3 small squares)
Bundle branch block- right or left
Ventricular tachycardia
What is a bundle branch block
When the bundle branch is diseased/damaged the impulse travels slow so the impulse travels slower in one than the other. Ventricular depolarisation takes longer so you get a broad qrs complex
Should a qrs complex be broad or narrow if normal
Narrow
What does a bundle branch block appear like on a ecg
Mmenomic: william marrow
If left: william marrow
If right: marrow william
At which leads should we look at for brundle branch block
Lead 1 and 6
If there are no p waves what does this present
Atrial fibrillation
What does ventricular tachycardia show on a ecg
Ventricular rate of 200bpm
Irregulary irregular
Is atrial fibrillation and atrial flutter the same
No
What is atrial flutter
- Supra ventricular tachycardia
Re-entry circuit in the right atria so whilst electrical activity starts in the SAN it loops back in a circle before it goes to the avn nodes and continues to the pathway
How does an atrial flutter present on a ecg
- Not every p wave has a QRS complex as it loops back to the san instead of going straight to the avn in the ventricles
- saw tooth pattern: lead 2,3,avf
What is a heart block
When the atria and ventricles conduct seperately
What are the causes of a heart block
Mi
Avn damage
Beta blocker overdose
Congenital
What are the types of heart block
First degree
Second degree
Third degree (complete heart block)
What are the subtypes of second degree heart block
Mobitz type 1
Mobitz type 2
