← Optical Illusions and 12-Lead ECGs: How First Impressions Can Mislead
Workout Quiz
5 questions. Answers are graded instantly with expert explanations.
1. A 12-lead ECG obtained during evaluation for palpitations shows brief, self-terminating runs of regular wide-complex tachycardia at 170 bpm in an otherwise stable adult. What is the preferred first-line pharmacologic approach while the underlying cause is investigated?
Intravenous lidocaine
Intravenous amiodarone
Intravenous or oral beta-blocker
Intravenous procainamide
Immediate synchronized cardioversion
2. Which combination of new ECG findings is most suggestive of acute pulmonary embolism in an adult with no prior cardiopulmonary disease?
Isolated T wave inversion in V1
Right axis deviation plus simultaneous T wave inversion in II, III, aVF and V1–V3
Classic S1Q3T3 pattern
Hyperacute T waves in V2–V4
Wellens-type deep symmetric T wave inversions in V2–V3
3. To minimize cognitive bias when interpreting a 12-lead ECG, many clinicians follow the sequence “rate → rhythm → axis → intervals → ischemia/infarction.” According to this approach, which element should you evaluate immediately after confirming the rhythm?
PR, QRS, and QT intervals
ST segment morphology
QRS axis
Presence of Q waves
Chamber enlargement criteria
4. Which statement best reflects current evidence on routine suppression of premature ventricular complexes (PVCs) or NSVT in stable patients?
Class IB agents such as lidocaine improve survival when given prophylactically.
Empiric antiarrhythmics can worsen outcomes by masking the inciting pathology and having proarrhythmic effects.
Amiodarone is contraindicated in all forms of ventricular ectopy.
Successful suppression of ectopy guarantees prevention of sustained VT.
Modern antiarrhythmics are hemodynamically neutral.
5. Right axis deviation (RAD) is detected on an ECG from an otherwise healthy adult. Which additional finding, if present, most strongly supports left posterior fascicular block (LPFB) as the etiology of the RAD?
Tall R wave in V1
Small Q waves with tall R-waves in leads II, III, and aVF
Deep S wave in lead I with Q wave in lead III (S1Q3)
Diffuse peaked T-waves
Normal QRS transition and limb lead placement confirmation
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