assalamualaikum w.b.t...
ECG interpretation always been a nightmare for medical students right :D
here me wanna share some things or method that i know abt ECG interpretation :)
before that, these are just based on my understanding from various source and also from apa yang yanie dapat during my internship kat hospital last time..so if ada yang tersilap or need to be corrected/added, do inform me :)
......
so, 1st thing 1st, kita kena faham basic concept sebelum kita mula nak faham or nak interpret ECG itself..apa basic concept yang perlu faham?
1) SA node
- SA node macam yang semua orang dah tahu dia ni act as trigger factor of the heart..
- from its name kita dah boleh tahu kat mana location dia --> right atrium of the heart
- nama lain dia - pacemaker of the heart
- this is the 1st place of conduction system of heart take place..
2) AV node
- from SA node, signal tu akan gerak ke AV node
- from nama dia jugak we can know the location --> in between RA & RV
- andddd its also known as gatekeeper of the heart...WHY?
**sebab it will decide which impulse to let to flow through it
- maksudnya, if let say SA node generate low impulse, and tak sampai threshold dia, so AV node akan hold the impulse & will not let the impulse to go through..
- so apa jadi??takkan biar je macamtu??
**no..AV node akan create its own impulse later :)
3) Bundle of HIS
- from AV node, the impulse will then go to BOH
- from BOH ni la later the impulse will be separated/ divided/ spread into 2 area --> left & right side of the heart [R & L Bundle Branches]
4) R&L Bundle Branches
- from this area, the impulse will later go to apex of the heart [purkinje fibers]
summary: SA node --> AV node --> BOH --> R&L Bundle Branches --> Purkinje fibers
lets get more into the topic..
**basically, HR regenerated based on which cardiac cells send impulses**
SA node --> HR will be 60-100bpm (normal one) [atrial]
- means that, if there's any changes or HR <60bpm, maksudnya SA node tak function normally already..
- in case of any problem at the RA, so SA node tak boleh send impulse la kan?that is the time when AV node akan take place & create its own impulse..apa jadi dengan HR bila AV node take place?
AV node --> HR will be 40-60bpm [junctional]
BOH --> HR also 40-60bpm (sebab BOH pun akan create its own impulse with same value as AV node)
- maksudnya if the HR yang kita dapat tu in between 40-60bpm, means the problem is at the right atrium..
- ifff let say there's any problem with the AV node & BOH, then R&L Bundle Branches + purkinje fibers will take place & generate their own impulse too..
R&L BB --> 20-40bpm [ventricular]
PF --> 20-40bpm
***NOW, LET'S GO A BIT MORE DETAIL INTO THE TOPIC***
everyone already familiar with the basic ECG structure kan?
1) P WAVE [atrial depolariation]
- maksudnya both atria are contracting
2) QRS COMPLEX [ventricular depolarization]
- maksudnya both ventricles are contracting
3) T WAVE [ventricular repolarization]
- maksudnya both ventricles are relaxing
* always known that after each DEpolarization, akan followed by REpolarization (after contraction, akan ada relaxation :)
so mana atrial REpolarization??
---> jawapannya, atrial repolarization ada dalam that QRS COMPLEX :D
>>why tak nampak??
>>sebab QRS complex is a tall structure
>>ventricles tend to contract stronger than atrium, so it will masked the atria repolarization :)
==> now lets move on to the segments & intervals <==
- segments & intervals banyak kan? how nak focus semua?
>> let's just focus on 3 - PR interval, QRS complex, RR interval
>> sebab tiga tu je kita perlu to interpret ECG :)
**lain2 segment still important; but to interpret faster, just focus on these 3
ABOUT ECG STRIPS
- ada big boxes & small boxes
- inside each big box, ada 5small boxes
1 small box = 0.04sec
1 big box = 0.20sec
***STEPS FOR ECG INTERPRETATION***
1) P wave identification
- make sure it present & in upright position
- if inverted/ absent means ada dysarrythmias
2) measure PR interval [beginning of P wave till beginning of QRS complex]
- count number of small boxes x 0.04sec
- normal should be in between 0.12sec - 0.20sec
- if >0.20sec, indicate dysarrythmias (1st degree heart block)
3) measure QRS complex
- count the small boxes x 0.04sec
- normal should be 0.06sec - 0.12sec
- if >0.12, indicate dysarrythmias (boleh jadi ada Branch Bundle Block)
4) identify rhythm
- measure RR interval
- could be regular/ irregular
- guna buku, pen & pembaris je..mark the 1st RR then compare with the next RR..if same maksudnya regular..if not means irregular
5) determine HR
- for this one, ada dua method..
- first, tengok the strip..easier if strip tu 6sec strip..
- on top of the strip ada line kecik senggang2 kan..from 1st line to 3rd line that will be the 6sec strip
- so, kira how many R, then multiply by 10 = HR
**this method works best for irregular rhythm
**AND THIS METHOD ONLY WORKS FOR 6SEC STRIP (so before calculate tengok dulu ada line ke tak)
- another method that can be used is big box method
>>300/big box in RR interval
- this method works best for regular rhythm
6) look for any axis deviation
- boleh tengok kat 3 partner
>>lead I & II
>>lead I & III
>>lead I & aVF
how to tengok? tengok gambar kat bawah ni lagi senang to faham think :)
7) interpret strip
- tell again each findings :)
**nanti next entry yanie share basic rules in ECG pulak :) [can find out here]
**again, these just a sharing based on what i understand..if there's anything need to be corrected, do correct me :)
xoxo,
yanie
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