ECG Interpretation in Syncope
Resident Clinical Pearl (RCP) – December 2018
Dr. Luke Taylor, FMEM PGY3 – Dalhousie University, Saint John NB
Reviewed by Dr. David Lewis
What are you looking for on the ECG of the patient with syncope?
Quick review of frequently pimped question on shift!
Two approaches – One using systematic ECG analysis, the other a mnemonic.
ECG Analysis (1)
Standard format of rate, rhythm, axis, and segments (PR, QRS, QT, ST).
Method of calculating heart rate (2)
Rate: Simple — Is the patient going too fast or too slow? *Remember this easy way to check:
Rhythm: Look at leads II, VI and aVR for P waves.
Ask yourself:
Are they upright in II/VI and inverted in aVR?
Does a QRS follow every P and a P before every QRS?
If so likely sinus rhythm.
In the setting of syncope we are looking to see if there is any signs of heart block – a P wave not conducted to a QRS, especially being sure not to miss a Mobitz type II block.
Axis: Axis comes in to play when looking for more extensive conduction disease. Is there axis deviation along with a change in your PR and BBB indicating something like a trifasicular block?
Segments:
PR interval— is it looooong (heart block) or short (reentrant)?
Long has already been discussed in looking for signs of heart block, but a short PR may be indicative of Wolf-Parkinson-White or Lown-Ganong-Levine syndromes.
WPW – look for short PR and delta wave
LGL – short PR but no delta wave due to its conduction being very close to or even through the AV node and not through an accessory pathway.
QRS Morphology analyzing this for signs of Brugada, HOCM, WPW, ARVD, pericardial effusion, and BBB.
ECG findings of Brugada (3)
Type 1: Coved ST segment elevation with T wav inversion
Type 2: Saddleback ST segment elevation and upright T waves
Type 3: either above without the ST elevation
QT interval — is it looooong (R on T) or short (VT/VF risk)?
Long is >450 men, 470 women
Short < 330ms – tall peaked T waves no ST segment
Pearl for long – should be less than half the RR interval. —>
Normal relationship of R-R and QT interval (4)
ST segment — think MI or PE (rare causes of syncope but need to be considered)
MI – elevations or depressions
PE – Tachycardia, RV strain, T-wave inversion V1-V3, RBBB morphology, S1Q3T3
Mnemonic (5)
ABCDEFGHII
A — Aortic stenosis
Go back to patient and listen!
B — Brugada
C — Corrected QT
D — Delta wave
E — Epsilon wave as in Arrhythmogenic Right Ventricular Dysplasia (ARVD)
Epsilon: Small positive deflection (‘blip’) buried in the end of the QRS complex (6)
F — Fluid filled heart
Pericardial effusion, electrical alternans, low voltage throughout
G — Giant PE
H — Hypertrophy
LVH in someone who shouldn’t have it
I — Intervals
PR, QRS, QT
I — Ischemia
Looking for a Basic ECG Guide? See our Med Student Pearl Here:
References
- CanadiaEM – ECGs in Syncope https://canadiem.org/medical-concept-ecgs-in-syncope
- https://en.ecgpedia.org/wiki/Rate
- ECG Waves https://ecgwaves.com/brugada-syndrome-ecg-treatment-management
- https://www.healio.com/cardiology/learn-the-heart/case-questions/ecg-cases/question-3-5
- Hippo EM Education Shorts https://www.youtube.com/watch?v=raTTYV7_Asl
- https://en.ecgpedia.org/index.php?title=Arrhythmogenic_Right_Ventricular_Cardiomyopathy
This post was copyedited by Dr. Mandy Peach
