Practice questions › MBBS / Medicine › Fundamentals of ECG
Fundamentals of ECG, Part 1 The ECG made very easy indeed: a beginner's guide MCQs
Fundamentals of ECG · MBBS / Medicine · 9 practice questions
- T wave abnormalities
- ST segment changes
- ECG red flags - rate thresholds
- Normal ECG variants - baseline T wave patterns
- QRS width and origin of ventricular activation
- ECG red flags and clinical correlations
- ECG interpretation approach - P wave and heart block
- ECG rate calculation
1. While systematically working through an ECG using the standard stepwise approach, a clinician notes that in several leads there are two clearly identifiable P waves preceding each QRS complex, with a otherwise narrow QRS. Which underlying process does this finding most likely indicate?
- AAbnormal conduction from the atria to the ventricles (heart block)
- BAn ectopic ventricular focus initiating each beat
- CDelayed but eventually normal atrioventricular conduction of every atrial impulse
- DAbsent atrial depolarization with a junctional escape rhythm
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A. Abnormal conduction from the atria to the ventricles (heart block) The text states that if there is more than one P wave before each QRS complex, conduction to the ventricles is abnormal — this is called heart block. Option A is incorrect because heart block, not merely 'delayed' normal conduction, is specifically what multiple P waves per QRS represents. Option B is wrong because P waves are clearly present, not absent. Option D is wrong because an ectopic ventricular focus produces a wide QRS from abnormal ventricular activation, not multiple preceding P waves.
2. A resting 12-lead ECG is obtained in an asymptomatic 40-year-old for a pre-employment check. The T wave is inverted in lead V1 but upright in all other leads including the inferior and lateral leads. Which of the following is the most appropriate interpretation of this finding?
- AThis is an expected normal variant and does not by itself suggest ischaemia or hypertrophy
- BThis indicates ventricular hypertrophy and requires urgent echocardiography
- CThis is diagnostic of myocardial ischaemia and requires immediate cardiology referral
- DThis indicates an old myocardial infarction and should be correlated with Q waves
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A. This is an expected normal variant and does not by itself suggest ischaemia or hypertrophy The text specifies the T wave is normally inverted in aVR (VR) and V1; inversion elsewhere raises concern for ischaemia or hypertrophy. Since inversion here is confined to V1 (a normal location), this is a normal finding, not evidence of ischaemia, hypertrophy, or infarction as suggested by the other options.
3. An unwell 70-year-old man in the emergency department has a heart rate of 38 bpm on the monitor with associated hypotension. Which of the following underlying causes is specifically listed as an association for this ventricular rate abnormality?
- AAlcoholism
- BPulmonary embolism
- CValve disease
- DIschaemia
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D. Ischaemia The table lists ischaemia, hypotension, and sepsis as associations for a ventricular rate above 120 bpm or below 45 bpm, which fits this bradycardic patient. Valve disease and alcoholism are associated with atrial fibrillation, not rate abnormalities per se, and pulmonary embolism is associated with abnormal T wave inversion in this table.
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