TV4101 SAM - ECG

cARDIAC WORKUP AND HAVE AN arrthymia then you DX and manage that arrhythmia

• Identify source of aarthymia

• Used to be used to guess chamber size with ECG - not as accurate - use echo instead now

Not ideal to have on GA patient as have PQRST when heart isn’t beating so better to have stethoscope to hear heart physically beating

Heart contraction needed by movement of ions (gens volatage to zap muscle)

Electrode - the little clip or pad

Lead - the machine determining the elcetrical flow btw electrodes

Leads are bipolar either positive or negative

Lead 1 - from left to right (

Why do we need leads - machine detects the current flowing towards positive electrode

We plot current flowing towards you in direction and magnitude OH YEAH

So if dead at you makes a big spike, if perpendiculr to you then its a lil bump kinda thing

Electricity generated in SA node then travels into atria
then arrives at electrically impermeable barrier - btw l and r heart and atria and ventricle

Goes through atrial muscle → atria depolairses then heads to av node

av node is not seen on ecg tracing → while current is in av node this is the PQ interval (ecg is flatline btw the contractions)

• Why is it so slow? So the different parts of heart don’t contract together

Then moves into ventricule

Moves quick in bundle of his and bundle branches

Summary, slow movement through atria → delayed at AV node →→ very fast in the Bundle of His and Purkinje system

Atrial contraction is a slower movement from slower current → P is a smooth bump magnitude is much lower

current at av node - flat section between the p and q indicates this

Recovery wave - ventricles repolarise

Ventricles repolarisation - looks like p wave - doesn’t repolarise with purk but repolarises with muscles (a slower movement)

Elec usually flows 60-120 degrees

Lead I - Picks up a little trace, lower amplitude and speed
Lead II - Much stronger trace

Lead III -

Lead aVr - directly opposite lead II - everything is the opposite

Lead aVl - Pretty similar to Lead I as close to Lead I

If aVr is positive - abnormal, either placement error of electrodes or heart on that side is enlarged (all the current is going in that direction) - don’t use the enlarged aspect much anymore prefer echo

electrical circuit causes contractions to be cooridinated

P wave = atrial depolairsation → current magnitude is quite low and slow

PR interval - av node

QRS complex reps - ventricular depolarisation - very fast and rpaid movement hence the spike

Atrial repolarisation is not visible on ecg why? Buried in ventricular depolarisation i.e. happening at same time but isn’t visible