L11 - ECG Flashcards
What is the function of the fibrous ring of the heart?
- Acts as an electrical insulator so that atria and ventricle contract separately
- anchors the myocardium and valves
- ensures only electrical connection is via bundle of his through it
The rhythm set by the SA mode is called the ______ rhythm?
Sinus
Depolarisation spreading away from a positive recording electrode will be recorded as an upward or downward deflection on the ECG?
Downward deflection
What wave form would we see on an ECG if we had depolarisation spreading transversely to the electrodes?
No or biphasic complex
The SA nodes electrical events are picked up by the ECG, true or false
False - the ecg picks up activity from areas with more myocytes
Is the main electrode on the apex side of the heart negative or positive?
Positive
What does the p wave represent?
Atrial depolarisation
What does the Q wave correspond to? What direction does the depolarisation spread across the septum?
Depolarisation of the interventricular septum.
Spreads patients left to right across septum
If the left ventricle of the heart were hypertrophied which wave would we see an increase in amplitude of?
R wave
If an ECG is missing a QRS complex, what does this indicate?
A problem in the the AV node and bundle of his - AV heart block
The 6 chest leads are labelled V1-V6. State where you put these on someone anatomically
V1 - 4th intercostal space, right of sternum
V2 - 4th intercostal space, left of sternum
v3 - midway between v2 and v4
V4 - 5th intercostal space, left mid- clavicular line
V5 - 5th intercostal space, left anterior axillary line
V6- 5th intercostal specie, left mid axillary line
Which leads give views of the inferior surface of the ventricles (it’d be useful to draw out the lead planes for this - see lecture)
II, III and aVF
Which leads give views of the right ventricle and septum?
V1 and v2
This lecture you really need to look at the pics and be able to recognise the different planes
Yep
At what rate does ECG paper move at per second?
25mm/second (25 small squares)
How many large squares does ECG paper move by per second?
5 large squares
How many large ECG boxes are there in one minute?
300
It’s that the PR interval is actually the distance between the beginning of the p wave and the beginning of the QRS complex and QT interval is between Q wave and end of T wave. What is the normal range for the PR interval?
0.12-0.20 seconds (3-5 small boxes)
What does a prolonged PR interval indicate?
Delayed conduction through AV mode and bundle of his
What is the normal range for a QRS complex and what does a widened QRS complex indicate?
Less than 0.12 seconds. (Less than 3 small boxes)
Indicates a depolarisation starting in the ventricles and not going via the fast conducting bundle of his pathway
Why does the QT interval need correcting?
Because patients have different heart rates and the interval decreases with an increase in heart rate, to look at solely this interval it needs correcting to the heart rate. It shows the time taken for the depolarisation and depolarisation of the ventricles
What are the things needed to determine a sinus rhythm?
- regular rhythm
- HR 60-100
- p waves present
- normal PR interval (3-5 small boxes)
- normal QRS width (less than or equal to small boxes)
- every p wave followed by a QRS complex
What are the colour of the electrodes: Right arm Left arm Right leg Left leg
Red
Yellow
Black
Green
What does a raised Or depressed ST segment indicate? (Should be isoelectric
Myocardial infarction or ischaemia
