In our inaugural ECG rounds this morning led by Dr. S. Chun, we reviewed several high-yield ECGs. Below I’ve outlined some key pearls with respect to each of these:
ECG #1-56 M with chest pain
- Main Findings: Left axis deviation with STD in infero-lateral leads and STE in noncontiguous leads (aVR and V1)
- Pearls:
- In patients with an NSTEMI, reasons for URGENT cath include:
- Signs or symptoms compatible with heart failure
- Evidence of arrhythmia or heart block
- Risk Stratify all patients with Acute Coronary Syndrome using the TIMI Score which considers 7 factors:
- Age >65
- >3 CAD Risk Factors (HTN, DM, DLP, Smoking, FHx)
- Known coronary stenosis >50% (must have had prior angiogram or cardiac imaging)
- ST deviation (up or down)
- >2 episodes of angina in the preceding 24 hours
- ASA use in preceding 1 week
- Elevated troponin
- Patients with a score of 2 or greater should ideally have an angiogram within 24 hours
- In patients with an NSTEMI, reasons for URGENT cath include:
ECG#2-37 F with chest pain
- Main findings: sinus tachycardia with an incomplete RBBB and RV strain pattern (TWI in V1-V3). There is also an isolated PVC. Of note, there is a classically described pattern of S1Q3T3 (large S in lead I with an isolated Q wave in lead III and an associated TWI in lead III)
- Pearls:
- RBBB defined by:
- RSR1 in V1-V3
- Wide/slurred S in I, aVL, V5, V6
- Associated TWI V1-V3, II, III, aVF (aka RV strain pattern)
- Major causes of RBBB causes include:
- RVH/Cor pulmonale
- PE
- S1Q3T3 is a “classic” finding described in association with PE
- To recognize the presence of RVH, use the 7-10-15 rule
- Normal ECG, no RBBB: RVH if R1 >7 mm
- Incomplete RBBB: RVH if R1 >10 mm
- Complete RBBB: RVH if R1 >15 mm
- RBBB defined by:
ECG#3- 25 M with 5 days of chest pain
- Main Findings: Diffuse, largely concave ST elevation; compatible with pericarditis.
- Pearls:
- chest pain from pericarditis classically improves when seated upright and leaning forward
- Note: in acute pancreatitis, leaning forward worsens epigastric pain (eponym: Ingelfinger sign)
- Can only discharge patients who have had an ECHO that rules out any hemodynamically significant pericardial effusion (definitely check for a pulsus paradoxus in all patients with pericarditis)
- Treatment for viral pericarditis:
- High dose ASA QID for 2-3 weeks (or until symptoms resolve)
- Usually with a PPI for gastric protection
- Along with colchicine BID (or OD if diarrhea-limiting) x 3 months
- chest pain from pericarditis classically improves when seated upright and leaning forward
ECG#4-78 F with syncope
- Main findings: Bradycardia with complete heart block and probable junctional escape rhythm (narrow complex QRS)
- Pearls:
- Patients with complete heart block may have abnormal JVP waveforms with the presence of “Canon A waves.” These represent the atria contracting against closed atrio-ventricular valves. Canon A waves may also be seen in VT.
- For a good review of JVP waveforms (normal and abnormal, check out these brief videos)
- To establish complete heart block, must have:
- evidence of A-V dissociation (Ps marching through)
- P waves moving faster than QRS
- QRS interval is CONSTANT
- Certain drugs may cause reversible heart block:
- Non-DHP calcium channel blockers: verapamil, diltiazem
- Beta blockers
- Cholinesterase inhibitors (ie. donepezil)
- Patients with complete heart block may have abnormal JVP waveforms with the presence of “Canon A waves.” These represent the atria contracting against closed atrio-ventricular valves. Canon A waves may also be seen in VT.
ECG#5-45 M presenting with syncope
Main findings: Polymorphic VT
- Pearls:
- Causes of polymorphic VT can be separated into:
- long QT related
- Drug-induced (i.e. antidepressant, antipsychotic, antiarrhythmic)
- Electrolyte-related (Hypokalemia, Hypomagnesemia)
- Congenital
- Unrelated to QT interval
- Ischemia (overwhelming majority)
- Catecholamine-induced polymorphic VT
- Cardiomyopathy
- long QT related
- Causes of polymorphic VT can be separated into:
Final Take-Home Points:
- There are MANY causes for elevated troponin beyond acute coronary syndrome:
- Patients with Prinzmetal angina may also have an antecedent history of migraines and/or Raynaud’s (all 3 of these are considered to be related to abnormal vasospasm)
- Helpful online ECG resources include: