Question 1

Which property of cardiac pacemaker cells allows them to spontaneously depolarize without external stimulation?

Accepted Answer

Automaticity

Question 2

A patient presents with a widened QRS complex ($$\u003e0.12$$ seconds) and a deep S wave in lead V1. Which condition is most likely?

Accepted Answer

Right bundle branch block

Question 3

Which ion is primarily responsible for the rapid depolarization phase (phase 0) of the ventricular myocardial action potential?

Accepted Answer

Sodium influx

Question 4

A 65-year-old patient’s EKG shows ST segment elevation in leads II, III, and aVF. Which coronary artery is most likely occluded?

Accepted Answer

Right coronary artery

Question 5

Calculate the heart rate if the R-R interval on standard EKG paper is 4 large boxes. Use the formula $$	ext{Heart Rate} = \frac{300}{	ext{number of large boxes}}.$$

Accepted Answer

$$75$$ bpm

Question 6

Which EKG finding is most specific for acute pericarditis?

Accepted Answer

Diffuse ST segment elevation and PR segment depression

Question 7

A patient with hypokalemia is most likely to show which EKG change?

Accepted Answer

Flattened or inverted T waves and prominent U waves

Question 8

Which of the following best describes the function of an EKG?

Accepted Answer

Detects electrical signals from the heart

Question 9

A prolonged PR interval ($$\u003e0.20$$ seconds) is most consistent with which conduction abnormality?

Accepted Answer

First-degree AV block

Question 10

Which EKG interval is most affected by changes in heart rate and should be corrected using Bazett’s formula $$QTc = \frac{QT}{\sqrt{RR}}$$?

Accepted Answer

QT interval

Question 11

A 22-year-old athlete has sinus bradycardia with a heart rate of 38 bpm and increased QRS voltage. What is the most likely explanation?

Accepted Answer

Physiologic adaptation from increased vagal tone and left ventricular hypertrophy

Question 12

Which EKG finding is most concerning for risk of sudden cardiac death in a young athlete?

Accepted Answer

Pathologic Q waves

Question 13

A patient’s EKG shows a regular rhythm, narrow QRS complexes, and sawtooth F waves in leads II, III, and aVF. What is the most likely diagnosis?

Accepted Answer

Atrial flutter

Question 14

Which of the following is the correct sequence of electrical activation in the heart?

Accepted Answer

SA node → atria → AV node → His bundle → bundle branches → Purkinje fibers → ventricles

Question 15

A patient with a history of Wolff-Parkinson-White syndrome presents with a short PR interval and a delta wave. What is the underlying mechanism?

Accepted Answer

Accessory pathway allowing early ventricular depolarization

Question 16

Which EKG change is most likely in a patient with hypercalcemia?

Accepted Answer

Shortened QT interval

Question 17

A patient’s EKG shows a biphasic T wave in leads V2-V3. What is the most likely clinical significance?

Accepted Answer

Wellens syndrome (critical LAD stenosis)

Question 18

Which of the following best describes the QRS axis in a normal adult?

Accepted Answer

$$30^\circ to$$ $$90^\circ$$

Question 19

A patient’s EKG shows a regular rhythm, wide QRS complexes, and no preceding P waves. What is the most likely rhythm?

Accepted Answer

Ventricular tachycardia

Question 20

Which of the following drugs is most associated with acquired long QT syndrome?

Accepted Answer

Quinidine

Fundamentals of Electrocardiography (EKG): Anatomy & Physiology Study Notes

Study Guide - Practice Questions

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