CCT CCT - Certified Cardiographic Technician Cardiac Medications and ECG Effects Questions and Answers 2 — Questions and Answers
Question 1: Hypokalemia is most likely to produce which ECG abnormality?
- Peaked T waves and wide QRS
- Prominent U waves and flattened T waves (Correct answer)
- Short QT interval
- Tall R waves in V1
Correct answer: Prominent U waves and flattened T waves
Low potassium causes flattening or inversion of T waves and the appearance of prominent U waves, which can prolong the QU interval.
Question 2: Which ECG finding is characteristic of hypercalcemia?
- Prolonged QT interval
- Shortened QT interval (Correct answer)
- Widened QRS
- Peaked T waves
Correct answer: Shortened QT interval
Elevated calcium shortens the ST segment and therefore the QT interval, because calcium affects plateau-phase duration of the action potential.
Question 3: Tricyclic antidepressant (TCA) overdose is most dangerous on the ECG because it causes:
- Shortened PR interval only
- QRS widening greater than 100 ms indicating high risk of arrhythmia (Correct answer)
- Peaked T waves
- Sinus bradycardia
Correct answer: QRS widening greater than 100 ms indicating high risk of arrhythmia
TCA toxicity blocks sodium channels, widening the QRS; a QRS >100 ms is associated with significantly increased risk of seizures and ventricular arrhythmias.
Question 4: Which medication can cause a 'Osborn wave' (J wave) pattern on the ECG, though it is more commonly seen with hypothermia?
- Digoxin
- Hypothermia alone causes it; no medication independently replicates it consistently (Correct answer)
- Amiodarone
- Adenosine
Correct answer: Hypothermia alone causes it; no medication independently replicates it consistently
Osborn (J) waves are most reliably associated with hypothermia and hypercalcemia; no single medication independently produces this finding with consistency.
Question 5: A patient on procainamide (Class IA agent) develops a wide-complex tachycardia resembling torsades de pointes. What ECG clue before treatment would have predicted this risk?
- Short PR interval
- Prolonged QT interval (Correct answer)
- Right bundle branch block pattern
- Low-voltage QRS
Correct answer: Prolonged QT interval
Class IA agents (procainamide, quinidine, disopyramide) prolong the QT interval, and a markedly prolonged QT is a warning sign for torsades de pointes.
Question 6: Calcium channel blockers (Class IV antiarrhythmics) such as verapamil primarily affect which interval on the ECG?
- QT interval (prolongation)
- PR interval (prolongation) (Correct answer)
- QRS duration (widening)
- RR interval shortening
Correct answer: PR interval (prolongation)
Verapamil and diltiazem slow AV nodal conduction by blocking L-type calcium channels, which prolongs the PR interval.
CCT CCT - Certified Cardiographic Technician Cardiac Medications and ECG Effects Questions and Answers 2
Hypokalemia is most likely to produce which ECG abnormality?