Basic Electrocardiogram

Question 1

When treating atrial fibrillation, which of the following is NOT a rate-controlling medication?

Accepted Answer

Amlodipine

Answer

Amlodipine is a dihydropyridine calcium channel blocker primarily used to treat hypertension and angina, and it does not significantly affect heart rate. Metoprolol (beta-blocker), Diltiazem (non-dihydropyridine calcium channel blocker), and Digoxin are all commonly used medications that slow the ventricular rate in atrial fibrillation by affecting AV nodal conduction.

Question 2

On the ECG trace below, which rhythm is present?

Accepted Answer

First degree heart block

Answer

First-degree heart block is characterized by a prolonged PR interval (greater than 0.20 seconds) on an ECG, indicating a delay in electrical conduction from the atria to the ventricles through the AV node. Despite the delay, every P wave is followed by a QRS complex, meaning all atrial impulses are eventually conducted. This consistent but extended delay is the hallmark of first-degree AV block.

Question 3

In a patient with a history of known AF, what would NOT be a cause of slow atrial fibrillation?

Accepted Answer

Thyrotoxicosis

Answer

Thyrotoxicosis, or hyperthyroidism, is known to *increase* heart rate and can often precipitate or exacerbate atrial fibrillation, leading to a *fast* ventricular response. Conversely, medications like Digoxin and Metoprolol are used to *slow* the ventricular rate in AF, and Complete Heart Block would also result in a slow ventricular rate, often independent of the atrial fibrillation.

Question 4

Which way does lead II go on an ECG?

Accepted Answer

60 degrees

Answer

In the standard limb lead configuration (Einthoven's triangle), Lead II is an inferior lead that runs from the right arm (negative) to the left leg (positive). It is oriented at an angle of +60 degrees on the frontal plane, making it a crucial lead for assessing the heart's electrical axis and inferior wall changes.

Question 5

Which antiemetics would NOT cause the QT interval to lengthen?

Accepted Answer

Metoclopramide

Answer

Metoclopramide, while having some potential for neurological side effects, is generally not associated with significant QT interval prolongation. In contrast, Domperidone, Ondansetron, and Droperidol are well-known to carry a risk of dose-dependent QT prolongation, which can predispose patients to serious ventricular arrhythmias like Torsades de Pointes.

ECG (Electrocardiogram) Practice Test

ECG (Electrocardiogram) Practice Test

Basic Electrocardiogram