CCT - Certified Cardiographic Technician Cardiac Medications and ECG Effects Questions and Answers Flashcards

Hypokalemia is most likely to produce which ECG abnormality?

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.

Which ECG finding is characteristic of hypercalcemia?

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.

Tricyclic antidepressant (TCA) overdose is most dangerous on the ECG because it causes:

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.

Which medication can cause a 'Osborn wave' (J wave) pattern on the ECG, though it is more commonly seen with hypothermia?

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.

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?

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.

Calcium channel blockers (Class IV antiarrhythmics) such as verapamil primarily affect which interval on the ECG?

Answer: PR interval (prolongation)

Verapamil and diltiazem slow AV nodal conduction by blocking L-type calcium channels, which prolongs the PR interval.