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ECG Update

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 painECG 1

  • 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

ECG#2-37 F with chest pain

ECG 2

  • 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

 

ECG#3- 25 M with 5 days of chest pain

ECG 3

  • 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

ECG#4-78 F with syncope

ECG 5

  • 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.
    • 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)

ECG#5-45 M presenting with syncope

ECG 6

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

Final Take-Home Points:

  • There are MANY causes for elevated troponin beyond acute coronary syndrome:troponitis
  •  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:

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