CET Cardiac Pharmacology Effects on ECG 3

Question 1

A patient taking magnesium sulfate for eclampsia is monitored via ECG. Which change would indicate magnesium toxicity?

Accepted Answer

Prolonged PR and QRS with bradycardia

Answer

Magnesium toxicity suppresses conduction, leading to prolonged PR and QRS intervals, bradycardia, and potentially complete heart block.

Question 2

Which antiarrhythmic drug class is most associated with causing a lupus-like syndrome AND QRS widening on ECG?

Accepted Answer

Class IA (procainamide)

Answer

Class IA drug procainamide can cause drug-induced lupus syndrome and, due to sodium channel blockade, prolongs the QRS complex.

Question 3

During an ECG, a patient on quinidine shows a markedly prolonged QT and polymorphic ventricular tachycardia. This is best described as:

Accepted Answer

Quinidine syncope / Torsades de Pointes

Answer

Quinidine-induced QT prolongation can trigger Torsades de Pointes, historically called 'quinidine syncope,' a polymorphic VT that is life-threatening.

Question 4

Verapamil given for rate control in atrial fibrillation most directly produces which measurable ECG change?

Accepted Answer

Slowing of the ventricular rate

Answer

Verapamil blocks calcium channels in the AV node, slowing conduction and thereby reducing the ventricular rate in atrial fibrillation.

Question 5

A patient on chronic amiodarone therapy develops thyroid dysfunction. Which ECG finding might accompany amiodarone-induced hypothyroidism?

Accepted Answer

Prolonged QT with bradycardia

Answer

Hypothyroidism slows the heart rate and prolongs the QT interval; amiodarone-induced hypothyroidism can exaggerate these effects.

(CET) Certified Electrocardiogram Technician Practice Test

(CET) Certified Electrocardiogram Technician Practice Test

CET Cardiac Pharmacology Effects on ECG 3