ECG ECG Pharmacology and Cardiac Medications 3

Question 1

A patient taking quinidine (Class IA) develops a QTc of 560 ms. What is the most serious arrhythmia risk associated with this finding?

Accepted Answer

Torsades de pointes

Answer

Marked QT prolongation from quinidine predisposes to torsades de pointes, a potentially fatal polymorphic ventricular tachycardia.

Question 2

Hypocalcemia (e.g., from loop diuretics or hypoparathyroidism) produces which ECG finding?

Accepted Answer

Prolonged QT interval due to a long ST segment

Answer

Hypocalcemia prolongs the ST segment, lengthening the QT interval, because calcium is essential for the plateau phase of the cardiac action potential.

Question 3

Which drug interaction should an ECG technician be aware of that can compound QT prolongation risk?

Accepted Answer

Amiodarone plus azithromycin

Answer

Amiodarone and azithromycin both independently prolong the QT interval; combining them significantly increases the risk of torsades de pointes.

Question 4

Nitroglycerin relieves angina but its primary ECG effect during an acute ischemic episode would be:

Accepted Answer

Reducing or resolving ST segment depression or elevation as ischemia improves

Answer

Nitroglycerin reduces myocardial oxygen demand and improves coronary perfusion; resolution of ischemia-induced ST changes confirms its effectiveness.

Question 5

A patient receiving thrombolytic therapy (e.g., tPA) for STEMI may show which ECG change that indicates successful reperfusion?

Accepted Answer

Accelerated idioventricular rhythm (AIVR)

Answer

Accelerated idioventricular rhythm is a classic reperfusion arrhythmia seen shortly after a blocked coronary artery reopens, indicating successful thrombolysis.

ECG (Electrocardiogram) Practice Test

ECG (Electrocardiogram) Practice Test

ECG ECG Pharmacology and Cardiac Medications 3