I was listening to CQI when a case of syncope came up, and the conversation turned to CDU syncope, and it got me thinking about serial ECGs and troponins in ECGs and eventually I started to think about why do we care about ECGs in syncope patients- and then we got to this POTD. So lets get chatting.
Syncope is defined as a transient loss of consciousness that is self limited and accompanied by transient lose of tone. Approximately 50% of the time when a patient presents to the ED with syncope, there is an etiology determined, 50% of the time it is unclear why a patient syncopizes. Of that 50% of the time the reason is determined it is usually from a detailed history and physical exam, not often found from studies.
What I wanted to focus on today was the 9.5-18% of the time when syncope is related to a cardiac cause. This is often due to the patient having an underlying cardiac etiology and is associated with a high rate of mortality and an elderly population.
SO- you are looking at an ECG what should you be looking for in a patient with syncope? I normally am not a mnemonic person but thought this was a helpful one I came across: “ABCDE Left Right”
A: AV Block:
First start by looking at the PR interval:
PR >200 ms: First Degree heart block, could be causing dizziness and syncope
Notice a pattern between p waves and morphology:
Dropped QRS complex with a normal P wave: Second Degree Mobitz type 1: (Wenckebach)
Dropped QRS with a fixed PR interval: Mobitz type II
Atrial and ventricular dissociation: Third Degree Heart Block
B: Brugada Pattern:
Type 1: Coved pattern in leads V1/V2
Type 2: Saddleback appearance in the ST segment in V1/V2
Caused by a genetic mutation in the sodium channel of cardiac myocytes
Patient will have a family hx of sudden cardiac death
C: QTc Prolongation
QTc is considered prolonged if it measures more than 440 ms in males/460 ms in females
Should be measured from the end of the beginning of the QRS complex to the end of the T wave
Typically measured in lead II or V5/V6
Etiology to include a variety of electrolyte abnormalities: hypoK, hypoMg, hypCa, increased ICP, or medication induced, or genetic (Long QT Syndrome)
In the case of genetic conditions, also consider if the patient has a family hx of sudden cardiac death
D: Delta Waves
A classic delta wave: shortened PR interval with slurred QRS upstroke is pathognomonic for Wolff Parkinson White Syndrome (WPW)
Caused by an electric conduction along an accessory pathway
Look for these in limb leads and/or precordial leads
E: Epsilon Waves
Epsilon wave: inflection point between the QRS and the ST segment pathognomonic for arrhythmogenic right ventricular cardiomyopathy (ARVD)
Typically seen in leads V1 and/or V2
ARVD: is a genetic condition that presents with conduction impairment due to fatty fibrous deposits in the cardiac myocytes
Left:
Evidence of Left ventricular hypertrophy
Could represent any signs for left heart strain including HCOM, aortic stenosis, coarctation, aortic regur, mitral regurg
Huge precordial R and S waves that overlap with adjacent leads
LV strain pattern with ST depression and T wave inversions in I, aVL, and V5-6
Right:
Evidence of right ventricular strain: ST segment depressions and T wave inversions in the right sided leads (V1-V4) and/or inferior limb leads II, III, AVF usually with right axis deviation
Concern for right ventricular strain would be concerning for pulmonary embolism
Must look for SIQ3T3
TLDR:
Syncope and ECGs, take a look at ABCDE Left Right:
AV Block: look at your PR interval and P and QRS morphology
Brugada: look at V1/V2 for saddleback deformities
QTc Prolongation: more than double the R-R is long!
Delta wave: upswinging QRS in the precordial/limb leads
Epsilon wave: inflection at the QRS between ST segment at V1/V2 concerning for ARVD
Left heart strain: huge R and S waves
R heart strain: signs of strain in the right sided/inferior leads
https://litfl.com/left-ventricular-hypertrophy-lvh-ecg-library/