Beat Reading Heart Beat Reading 4 — Questions and Answers
Question 1: Which electrolyte abnormality most commonly causes a wide, flat or inverted T wave and prominent U wave on ECG?
- Hyperkalemia
- Hypokalemia (Correct answer)
- Hypercalcemia
- Hyponatremia
Correct answer: Hypokalemia
Hypokalemia characteristically causes T wave flattening or inversion and the appearance of prominent U waves on the ECG.
Question 2: On a 6-second rhythm strip with 8 complete R-R cycles visible, the estimated heart rate is:
- 48 bpm
- 60 bpm
- 80 bpm (Correct answer)
- 96 bpm
Correct answer: 80 bpm
Counting 8 R waves in 6 seconds and multiplying by 10 gives an estimated rate of 80 bpm.
Question 3: Peaked, narrow, tall T waves are most associated with which electrolyte disturbance?
- Hypokalemia
- Hyperkalemia (Correct answer)
- Hypocalcemia
- Hypermagnesemia
Correct answer: Hyperkalemia
Early hyperkalemia produces tall, peaked, narrow-based T waves, often described as 'tented,' before more severe changes occur.
Question 4: A patient has no relationship between P waves and QRS complexes, each firing at their own independent rate. This describes:
- Second-degree AV block Type II
- First-degree AV block
- Third-degree (complete) AV block (Correct answer)
- Atrial fibrillation
Correct answer: Third-degree (complete) AV block
Third-degree (complete) AV block means the atria and ventricles are electrically dissociated, each driven by separate pacemakers.
Question 5: Which ECG finding is associated with a prolonged QT interval and risk of Torsades de Pointes?
- Hypomagnesemia and hypokalemia (Correct answer)
- Hyperkalemia and hypercalcemia
- Hypernatremia and hypermagnesemia
- Metabolic alkalosis alone
Correct answer: Hypomagnesemia and hypokalemia
Hypomagnesemia and hypokalemia both prolong the QT interval and predispose patients to Torsades de Pointes, a polymorphic ventricular tachycardia.
Question 6: On a 12-lead ECG, which leads are grouped together as the 'lateral leads'?
- I, aVL, V5, V6 (Correct answer)
- II, III, aVF
- V1, V2, V3, V4
- aVR, aVL, aVF
Correct answer: I, aVL, V5, V6
Leads I, aVL, V5, and V6 are the lateral leads that view the lateral wall of the left ventricle.
Question 7: A rhythm with a rate of 150-250 bpm, narrow QRS, and abrupt onset/termination is most likely:
- Sinus tachycardia
- Paroxysmal supraventricular tachycardia (PSVT) (Correct answer)
- Ventricular tachycardia
- Atrial flutter with 2:1 block
Correct answer: Paroxysmal supraventricular tachycardia (PSVT)
PSVT (paroxysmal supraventricular tachycardia) typically presents with abrupt onset and termination, narrow QRS, and rates between 150 and 250 bpm.
Beat Reading Heart Beat Reading 4
Which electrolyte abnormality most commonly causes a wide, flat or inverted T wave and prominent U wave on ECG?