Syncope ECG – The ABCs

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:

Medical Student Clinical Pearl – Basic ECG Interpretation

 


 

References

  1. CanadiaEM – ECGs in Syncope https://canadiem.org/medical-concept-ecgs-in-syncope
  2. https://en.ecgpedia.org/wiki/Rate
  3. ECG Waves https://ecgwaves.com/brugada-syndrome-ecg-treatment-management
  4. https://www.healio.com/cardiology/learn-the-heart/case-questions/ecg-cases/question-3-5
  5. Hippo EM Education Shorts https://www.youtube.com/watch?v=raTTYV7_Asl
  6. https://en.ecgpedia.org/index.php?title=Arrhythmogenic_Right_Ventricular_Cardiomyopathy

 

This post was copyedited by Dr. Mandy Peach

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Pediatric syncope: an investigative dilemma?

Pediatric syncope: an investigative dilemma??

Resident Clinical Pearl (RCP) – February 2018

Kalen Leech-Porter R3 FMEM, Dalhousie University, Saint John, New Brunswick

Reviewed by Dr. David Lewis

 

The case

A 16 year old girl comes in by ambulance, after fainting while singing at church on a Sunday morning.  Her vitals are: HR 90, RR 16, Temp 36.5, BP 92/64. O2 Sat 99% on RA.  On arrival she is alert and looks well.  She explains that she stood up to sing, felt lightheaded and then, soon after, lost consciousness.  The paramedic lets you know witnesses say she turned ashen grey and sweaty, and was out for about 2 minutes.  She had some ‘seizure like activity for 10 seconds’ with a few twitches in different parts of her body.  The patient states she was fully recovered within a few minutes.  Family history is unremarkable, with no sudden early deaths.  Physical examination is also unremarkable.  The nurse rolls in an ECG machine to check her rhythm.

What investigations does she require?

 

Why It Matters?

Pediatric syncope is very common in the emergency setting, accounting for ~1 % of pediatric emergency visits.   Between 15 and 50% of children will have at least one syncopal event in their childhood (peaking in adolescence).  – It’s a common problem!

 

The problem?

Historically, working up pediatric syncope has varied widely.  ECG use has been routine and some centers have regularly ordered bloodwork, CTs and even EEGs.  This onslaught of testing has led to increased hospital costs, stressful false positives for patients and has not improved patient outcomes.  Plus, reading pediatric ECGs can be challenging – see the end of this pearl.

 

A potential solution

In 2017, the Canadian Cardiovascular Society and Canadian Pediatric Cardiology Association published a position statement on an approach to pediatric syncope¹  Full Article – click here

A thorough history and physical can be sufficient in low risk patients – no investigations are required for many pediatric syncope presentations. 

Red flags

  • Lack of Prodrome: warm/clammy sensation, lightheaded ness, visual changes. Having a prodrome is the most important factor in benign syncope
  • Midexertional syncope; however post exertional syncope (having an opportunity to stop) is typically benign
  • Chest Pain preceding the event
  • Prolonged loss of consciousness
  • Family history of cardiovascular disease/sudden death
  • Syncope triggered by loud noise
  • New medications (QT prolonging drugs)
  • Abnormal physical exam – pathologic murmur, sternotomy scar, neurologic deficits

 Red herrings

  • Pallor is common in vasovagal events
  • Palpitations are common in vasovagal events (although evidence around this not robust)
  • Involuntary movement is also common in vasovagal syncope. Benign movements can be a muscle twitch to violent jerks of the whole body

 

Investigative Algorithm

Figure 1. Pediatric syncope investigative algorithm, adapted from Sanatani et al. (2017)

 

The Evidence

To create this position statement, the Canadian Cardiovascular Society (CCS) performed a literature review of 4307 references, ultimately including 231 articles for full-text review.

Most of the studies referred to in the article are retrospective reviews. Therefore, recommendations in the position statement were mostly graded as ‘Strong recommendation, low level of evidence’. I found the most compelling evidence against routine ECG was the statement: “The ECG was the only indicator of cardiac disease in 5 of 480 patients (1%) and causality could not be determined”.¹  However, they did not list a reference for this statement and I’m not sure what study they drew this conclusion from.  I do feel they make a compelling case against over investigation, but as in many areas of medicine, the evidence could be more robust.

 

Pediatric ECGs – how to interpret?

The nurse hands you the ECG, what features are worrisome on a pediatric ECG?

See following chart from the CCS¹

Figure 2. Pediatric ECG findings in syncope, adapted from Sanatani et al. (2017)

In summary, red light features should prompt an emergent cardiology referral. Yellow light features should prompt a non-urgent cardiology referral while green light features are normal variants and require no further work up.

 

Case Resolution

There were no red flags, arguably she requires no investigations, not even an ECG.   Of course, clinical acumen trumps guidelines, but at least you will be CCS endorsed if you chose to not do any further investigations.

 

References

  1. Sanatani, V. Chau, A. Fournier, A. Dixon, R. Blondin, R. Sheldon. Canadian Cardiovascular Society and Canadian Pediatric Cardiology Association Position Statement on the Approach to Syncope in the Pediatric Patient. Canadian Journal of Cardiology. 2017; 33: 189-198.

 

 

This post was copyedited by Kavish Chandra @kavishpchandra

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