Rhythm Disorders Tutorial Flashcards
How can the leads avR, avF and avL be shown on the diagram below?
And so where are the leads I, II, and III derived from?
Lead I, II and III are found between the av leads
So how would you draw the lead vectors onto a 360 degrees axis?
Which lead is best to look at and why?
Majority of impulses in the heart travel towards lead II = v. insightful
What does the image show?
What is the normal cardiac axis and what are axis deviations?
The vectors of the 6 leads of the 12-lead ECG - the mean electrical vectors in the heart
Normal cardiac axis is considered to be from +90 to -30 degrees
So left axis deviation goes from -90 to -30 degrees, and right axis deviation goes from
Anything outside these ranges is considered extreme deviation, and is rare
What waves form on the ECG when the electricity travels:
along, towards the lead
along but away from the lead
halfway between 2 leads positively
halfway between 2 leads negatively
nowhere along that lead
Show what the inflections on the ECG would show for the leads below:
Mr A has experienced “a severe deep burning sensation in his chest on and off. The pain is associated with sweating and is worse when he walks upstairs”
What other questions might you wish to ask Mr A about his pain?
S - sight
O - onset
C - character
R - radiation
A - associations
T - time course
E - exacerbating / alleviating factors
S - scale
Can you point exactly where it hurts?
When did the pain start?
Was it sudden or gradual?
What kind of pain? burning, tingling, sharp, etc.
Does the pain spread elsewhere?
What other symptoms do you experience alongside the pain? (sweating indicates sympathetic NS issues)
How long have you had this pain?
How often and how long does it last? What exacerbates it? (exertion / exercise)
What is the main reliever? (rest)
How severe is the pain on a scale of 1-10?
How will his chest pain be classified?
Typical
Atypical
Non-cardiac
Depends on the response to 3 questions:
Is it retrosternal (i.e. behind the sternum)
Is it brought on with exertion?
Is it relieved by rest or glycerol trinitrate? (sublingual spray, potent, short-acting, vasodilator)
3/3 = yes = typical
2/3 = yes = atypical
1/3 = yes = non-cardiac
Typical = usually coronary artery disease
Non-cardiac = usually muscular issue
So he most likely has typical chest pain
Provide a written report of his ECG above
What type of heart block may this suggest?
S-T segment elevation in leads II, III and aVF
S-T segment depression
Isoelectric point changes - most likely due to background noise from him moving due to pain
P waves - beating every 17 small squares, but the ventricles are doing their own thing
3rd degree heart block - complete heart block
The registrar tells you Mr A is being referred for a coronary angiogram.
What findings would you expect to see?
The S-T elevation in leads II, III and aVF
They all correspond to the same artery - right coronary artery
Expect to see a narrowing of the right coronary artery - upwards of 50%, probably around 80%
What two common interventions would be available for Mr A?
Briefly summarise their features.
Open heart surgery = coronary artery bypass graft = graft vein from leg and use it to bypass the narrowed coronary artery
Balloon angioplasty (inflate inside the artery to wide the lumen) / insertion of a drug eluting stent (coated drug that seeps out over time) e.g. an anti-coagulant / vasodilator
Mrs D had an ECG (shown below) and has been told she has heart block.
What type of heart block is it?
There is a P-wave before and after the QRS complex
Ratio of P waves to QRS waves = 2:1
Type II Mobitz most likely
But could be complete heart block masked by timing of the waves masking it as Type II Mobitz pattern
How can we differentiate between Type II Mobitz and 3rd degree heart block?
Take a longer ECG recording - i.e. 24-hr recording
