EKG Analysis and Interpretation Practice Test

25 practice questions

Choose an answer, then check it under Show answer.

1. Question 1 of 25Hard

   In a skilled nursing facility, an 80-year-old woman's strip shows regular, upright P waves at 80 per minute and regular, narrow QRS complexes at 40 per minute. Every other P wave has no QRS after it, and each QRS follows a P wave with the same PR interval of 0.18 seconds. Which rhythm best fits this description?

   1. AA. Sinus bradycardia
   2. BB. Third-degree (complete) AV block
   3. CC. 2:1 second-degree AV block
   4. DD. Junctional escape rhythm
   Show answer to question 1

   Answer: C. 2:1 second-degree AV block

   Each QRS follows a P wave at the same PR interval, so those P waves are being conducted, while every other P wave is blocked. This is second-degree AV block with 2:1 conduction; the steady PR interval rules out complete block, even though there are twice as many P waves as QRS complexes.

   Why the other options are wrong

   • ASinus bradycardia has one P wave before every QRS complex, with no P waves left unconducted.
   • BIn third-degree block the P waves have no relationship to the QRS complexes, so the PR interval keeps changing.
   • DA junctional escape rhythm starts in the AV junction, so its QRS complexes do not follow sinus P waves at a constant PR interval.

2. Question 2 of 25Medium

   In a long-term care facility, an 81-year-old woman who takes a diuretic has had several days of vomiting. Her EKG shows flattened T waves followed by prominent U waves. Which electrolyte imbalance are these changes most often associated with?

   1. AA. High potassium (hyperkalemia)
   2. BB. High calcium (hypercalcemia)
   3. CC. Low sodium (hyponatremia)
   4. DD. Low potassium (hypokalemia)
   Show answer to question 2

   Answer: D. Low potassium (hypokalemia)

   Low potassium commonly flattens T waves and makes U waves more prominent, and diuretics and vomiting are common causes of potassium loss. The technician reports the finding; the provider orders and interprets lab tests.

   Why the other options are wrong

   • AHigh potassium causes tall, peaked T waves, not flattened T waves with U waves.
   • BHigh calcium mainly shortens the QT interval rather than producing prominent U waves.
   • CLow sodium does not typically cause flattened T waves with prominent U waves.

3. Question 3 of 25Medium

   On a step-down unit, a 77-year-old man with a ventricular demand pacemaker has his own narrow QRS complexes at 80 per minute. Pacing spikes also keep appearing at a fixed rate, some landing just after his own QRS complexes or on T waves. Which problem is suggested?

   1. AA. Failure to capture
   2. BB. Normal demand pacing
   3. CC. Failure to sense
   4. DD. Dual-chamber pacing
   Show answer to question 3

   Answer: C. Failure to sense

   A demand pacemaker should detect the patient's own beats and hold its output while they come fast enough. Spikes that keep firing on schedule, landing just after his QRS complexes or on T waves, mean the device is not sensing those beats.

   Why the other options are wrong

   • AFailure to capture describes spikes that do not trigger a complex, not spikes that fire despite the patient's own beats.
   • BA pacemaker working on demand resets after each of his own beats, so its spikes would not land just after his QRS complexes.
   • DDual-chamber pacing shows two spikes per cycle, one before the P wave and one before the QRS complex.

4. Question 4 of 25Hard

   On a hospital cardiac unit, a provider explains to a technician that a 76-year-old woman's SA node has stopped firing. A backup site is now pacing her heart at a regular rate of 45 per minute, with narrow QRS complexes. Which statement best identifies the backup site?

   1. AA. The Purkinje fibers, whose intrinsic rate is 40 to 60 per minute
   2. BB. The AV junction, whose intrinsic rate is 20 to 40 per minute
   3. CC. The AV junction, whose intrinsic rate is 40 to 60 per minute
   4. DD. The Purkinje fibers, whose intrinsic rate is 60 to 100 per minute
   Show answer to question 4

   Answer: C. The AV junction, whose intrinsic rate is 40 to 60 per minute

   When the SA node fails, the AV junction normally takes over at its intrinsic rate of 40 to 60 per minute. Because the impulse still travels down the normal ventricular pathway, the QRS complexes stay narrow, which fits this patient.

   Why the other options are wrong

   • APurkinje fibers have an intrinsic rate of 20 to 40 per minute, and their beats usually produce wide QRS complexes.
   • BThe AV junction is the likely site, but its intrinsic rate is 40 to 60 per minute, not 20 to 40.
   • DPurkinje fibers fire at 20 to 40 per minute; 60 to 100 per minute is the SA node's intrinsic rate.

5. Question 5 of 25Hard

   A 68-year-old woman tells the technician that her pacemaker is set to keep her heart rate from falling below 60. Her resting EKG shows normal sinus rhythm at 84 per minute, with no pacemaker spikes anywhere on the tracing. What is the most likely explanation?

   1. AA. The pacemaker is firing but failing to capture the heart
   2. BB. Her own rate is faster than the pacemaker's set rate
   3. CC. The pacemaker battery has run down and stopped working
   4. DD. The EKG machine is printing the spikes far too small to see
   Show answer to question 5

   Answer: B. Her own rate is faster than the pacemaker's set rate

   Most pacemakers work on demand: they pace only when the heart's own rate falls below the set rate. With her sinus rate at 84, the device has no reason to fire, so no spikes are expected, and the technician still notes her pacemaker status on the tracing.

   Why the other options are wrong

   • AFailure to capture shows spikes without the expected complex, but this tracing has no spikes at all.
   • CNothing here suggests a battery problem, because her own rhythm needs no pacing.
   • DHidden spikes are far less likely than normal demand pacing that simply has no need to fire.

6. Question 6 of 25Hard

   On a sinus rhythm strip, one T wave has an extra hump that the other T waves lack, and the next QRS complex comes earlier than expected. That early QRS is narrow and looks like the others. What best explains these findings?

   1. AA. An R-on-T PVC landing on that T wave
   2. BB. Movement artifact distorting that T wave
   3. CC. A PAC whose P wave is hidden in the T wave
   4. DD. A second-degree AV block with one dropped QRS complex
   Show answer to question 6

   Answer: C. A PAC whose P wave is hidden in the T wave

   An early, narrow, normal-looking QRS points to a premature beat from above the ventricles. When the early P wave of a premature atrial contraction lands on the preceding T wave, it changes that T wave's shape, so a deformed T wave just before an early beat suggests a PAC.

   Why the other options are wrong

   • AAn R-on-T PVC produces a wide, bizarre QRS on the T wave, not a narrow QRS that matches the others.
   • BMovement artifact can distort a T wave, but it does not make the next QRS complex arrive early.
   • DA dropped QRS leaves a P wave with no QRS after it, while here an extra QRS arrives early.

7. Question 7 of 25Hard

   In an outpatient cardiology clinic, a 66-year-old man is awake and alert but says his heart is racing. His tracing shows a regular, wide-QRS rhythm at about 170 per minute with no P waves seen. He has a pulse. What is the best action?

   1. AA. Begin chest compressions while a coworker gets the AED
   2. BB. Apply AED pads and shock him before he loses his pulse
   3. CC. Stay with him and get the provider or emergency help now
   4. DD. Finish the tracing and give it to the provider at day's end
   Show answer to question 7

   Answer: C. Stay with him and get the provider or emergency help now

   A regular, wide-QRS rhythm at 170 suggests ventricular tachycardia, which can lose its pulse at any moment. Because he is awake with a pulse, CPR is not started; the technician stays with him, gets the provider or emergency help at once and watches for change.

   Why the other options are wrong

   • AChest compressions are for a patient with no pulse, and he is awake with a pulse.
   • BAED pads are for a patient in cardiac arrest; while he has a pulse, the provider decides treatment.
   • DWaiting until the end of the day is unsafe for a rhythm that can turn into cardiac arrest.

8. Question 8 of 25Medium

   An EKG technician calculates a patient's corrected QT interval (QTc) and finds it is abnormally short at 0.30 seconds. Which electrolyte disturbance is the most likely cause of a shortened QT interval?

   1. AA. Hypomagnesemia
   2. BB. Hypokalemia
   3. CC. Hypocalcemia
   4. DD. Hypercalcemia
   Show answer to question 8

   Answer: D. Hypercalcemia

   Hypercalcemia accelerates cardiac repolarization by shortening the plateau phase of the ventricular action potential, resulting in ST-segment shortening and a shortened overall QT interval. Hypocalcemia, hypomagnesemia, and hypokalemia all prolong the QT interval or QU interval rather than shorten it.

9. Question 9 of 25Easy

   A nursing student shadowing a technician at a teaching hospital points to the T wave on a normal tracing and asks what it represents. Which answer is accurate?

   1. AA. Recovery of the ventricles (ventricular repolarization)
   2. BB. Activation of the atria (atrial depolarization)
   3. CC. Activation of the ventricles (ventricular depolarization)
   4. DD. The impulse slowing as it passes through the AV node
   Show answer to question 9

   Answer: A. Recovery of the ventricles (ventricular repolarization)

   The T wave follows the ST segment and shows the ventricles electrically recovering, or repolarizing, so they can respond to the next impulse.

   Why the other options are wrong

   • BAtrial depolarization appears as the P wave at the start of the cycle.
   • CVentricular depolarization appears as the QRS complex, which comes before the T wave.
   • DThe AV node delay occurs during the PR interval, before the QRS complex.

10. Question 10 of 25Medium

    In a hospital outpatient area, a 61-year-old man regains a pulse and begins breathing after CPR and one AED shock. The code team leader asks the technician to record a 12-lead EKG right away. What is the main reason for recording it this early?

    1. AA. To look for a heart attack that may have caused the arrest
    2. BB. To see whether the AED shock damaged his heart muscle
    3. CC. To decide whether chest compressions should start again
    4. DD. To have a baseline tracing ready for his next routine checkup
    Show answer to question 10

    Answer: A. To look for a heart attack that may have caused the arrest

    A heart attack from a blocked coronary artery is a common cause of cardiac arrest. Once a pulse returns, a 12-lead EKG is recorded as soon as possible to look for ST elevation, so that a blocked artery can be opened quickly if one is found.

    Why the other options are wrong

    • BThe early tracing looks for the cause of the arrest, not for damage from the shock.
    • CWhether compressions start again depends on his pulse and breathing, not on a 12-lead tracing.
    • DA routine baseline is not the reason for an urgent tracing right after resuscitation.

11. Question 11 of 25Medium

    A 74-year-old man on a cardiac telemetry unit has this rhythm: rate 70 per minute and regular; no P waves are seen; every QRS complex is wide, about 0.16 seconds, and comes right after a sharp, narrow vertical line. Which rhythm does this describe?

    1. AA. Ventricular tachycardia
    2. BB. Atrial paced rhythm
    3. CC. Ventricular paced rhythm
    4. DD. Accelerated idioventricular rhythm
    Show answer to question 11

    Answer: C. Ventricular paced rhythm

    A spike right before every wide QRS complex shows that the pacemaker is stimulating the ventricles. The QRS is wide because each beat starts in the ventricle, and the regular rate of 70 fits a paced rhythm.

    Why the other options are wrong

    • AVentricular tachycardia has a rate over 100 per minute and no pacemaker spikes before the complexes.
    • BIn an atrial paced rhythm, the spike comes before a P wave, which is usually followed by a narrow QRS complex.
    • DAn accelerated idioventricular rhythm can have wide complexes at this rate, but it has no pacemaker spikes.

12. Question 12 of 25Hard

    A technician observes a distinct deflection following the T wave in lead V3 on an EKG showing sinus bradycardia at 54 beats/min. Which finding confirms that this deflection is a normal physiological U wave rather than an abnormal variant?

    1. AA. It is inverted and has an amplitude equal to the preceding T wave.
    2. BB. It is upright and measures less than 25% of the preceding T wave amplitude.
    3. CC. It has an amplitude exceeding 2.0 mm across all precordial leads.
    4. DD. It is biphasic and precedes the ST segment by 0.08 seconds.
    Show answer to question 12

    Answer: B. It is upright and measures less than 25% of the preceding T wave amplitude.

    A normal physiological U wave is upright, oriented in the same direction as the T wave, and small in amplitude, typically less than 1.5 mm tall or less than 25% of the preceding T wave height. An inverted U wave is considered abnormal and often indicates myocardial ischemia or left ventricular strain. Amplitudes exceeding 2.0 mm are abnormally prominent and frequently suggest electrolyte disturbances such as hypokalemia.

13. Question 13 of 25Easy

    On EKG graph paper, what do the horizontal and vertical directions measure?

    1. AA. Horizontal shows voltage; vertical shows time
    2. BB. Horizontal shows heart rate; vertical shows time
    3. CC. Horizontal shows time; vertical shows heart rate
    4. DD. Horizontal shows time; vertical shows voltage
    Show answer to question 13

    Answer: D. Horizontal shows time; vertical shows voltage

    Moving left to right across the paper measures time in seconds. Moving up or down measures voltage (amplitude) in millivolts, which describes how tall or deep each wave is.

    Why the other options are wrong

    • AThis reverses the two directions; time runs along the paper and voltage runs up and down.
    • BHeart rate is calculated from the spacing of waves over time; it is not plotted on either axis.
    • CHorizontal is time, but the vertical direction measures voltage, not heart rate.

14. Question 14 of 25Hard

    At an occupational health clinic, a new technician reviews a routine 12-lead EKG for a 24-year-old man. In lead aVR, the P wave, QRS complex and T wave all point mostly downward, while in leads I and II they are upright. How should the technician understand the lead aVR finding?

    1. AA. It is the normal pattern for lead aVR and needs no special action
    2. BB. It shows that the arm electrodes were reversed and must be redone
    3. CC. It shows that the chest electrodes were placed too high on the chest
    4. DD. It shows a dangerous rhythm that needs an immediate emergency response
    Show answer to question 14

    Answer: A. It is the normal pattern for lead aVR and needs no special action

    Lead aVR views the heart from the right shoulder, and normal electrical flow travels away from it. Its P wave, QRS complex and T wave are therefore normally negative, while leads I and II show them upright.

    Why the other options are wrong

    • BArm electrode reversal typically inverts the waves in lead I, but lead I is upright here, and downward waves in aVR are expected.
    • CChest electrode position affects leads V1 to V6, not the limb lead aVR.
    • DThe direction of waves in one lead does not signal a dangerous rhythm, and upright waves in leads I and II fit normal conduction.

15. Question 15 of 25Easy

    What causes the long PR interval in first-degree AV block?

    1. AA. The SA node is firing more slowly than normal
    2. BB. Some atrial impulses never reach the ventricles
    3. CC. The impulse starts in the ventricles instead of the atria
    4. DD. A delay in conduction through the AV node
    Show answer to question 15

    Answer: D. A delay in conduction through the AV node

    In first-degree AV block, every atrial impulse reaches the ventricles, but each one is held up longer than normal, most often in the AV node. The delay stretches the PR interval beyond 0.20 seconds, and the PR stays the same from beat to beat.

    Why the other options are wrong

    • AA slow SA node lowers the heart rate, as in sinus bradycardia, and does not lengthen the PR interval.
    • BImpulses that fail to reach the ventricles describe second-degree or third-degree AV block.
    • CBeats that start in the ventricles have wide QRS complexes and no related P wave, so there is no PR interval.

16. Question 16 of 25Easy

    For an adult who arrives at the emergency department with chest pain, national guidelines call for a 12-lead EKG to be obtained and reviewed within what time of arrival?

    1. AA. 10 minutes
    2. BB. 30 minutes
    3. CC. 60 minutes
    4. DD. 2 hours
    Show answer to question 16

    Answer: A. 10 minutes

    Chest pain guidelines call for a 12-lead EKG to be acquired and reviewed within 10 minutes of arrival, so that a STEMI can be recognized and treated quickly. Technicians treat these requests as top priority.

    Why the other options are wrong

    • BThirty minutes is too long, since a STEMI could go untreated during the delay.
    • CAn hour would waste much of the time in which heart muscle can still be saved.
    • DTwo hours would seriously delay the recognition and treatment of a STEMI.

17. Question 17 of 25Medium

    On an inpatient cardiology unit, an 81-year-old woman's strip shows regular P waves at 75 per minute. The PR intervals measure 0.20, 0.26 and 0.32 seconds on three beats in a row, and then a P wave appears with no QRS after it. The cycle then repeats. Which rhythm does this describe?

    1. AA. Second-degree AV block type I
    2. BB. First-degree AV block
    3. CC. Second-degree AV block type II
    4. DD. Third-degree AV block
    Show answer to question 17

    Answer: A. Second-degree AV block type I

    A PR interval that grows longer with each beat until one P wave is not conducted, followed by a repeat of the cycle, is second-degree AV block type I, also called Mobitz I or Wenckebach. It produces grouped beating with a regularly irregular ventricular rhythm.

    Why the other options are wrong

    • BFirst-degree block has a long PR interval that stays the same, and every P wave is followed by a QRS.
    • CType II block drops QRS complexes without any lengthening of the PR interval beforehand.
    • DIn third-degree block, no P waves are conducted, and the PR interval varies with no repeating cycle.

18. Question 18 of 25Easy

    Which two rhythms is an AED designed to shock?

    1. AA. Asystole and severe sinus bradycardia
    2. BB. Complete heart block and asystole
    3. CC. Atrial fibrillation and sinus tachycardia
    4. DD. Ventricular fibrillation and pulseless VT
    Show answer to question 18

    Answer: D. Ventricular fibrillation and pulseless VT

    An AED is built to recognize ventricular fibrillation and fast ventricular tachycardia and to advise a shock for them, and it is used only on a patient who is unresponsive and pulseless. The shock can stop the abnormal electrical activity so that an organized rhythm can return.

    Why the other options are wrong

    • AAsystole and slow organized rhythms are not shockable; a pulseless patient with them needs CPR.
    • BAn AED does not shock complete heart block or asystole; CPR continues if there is no pulse.
    • CAn AED is not designed to shock atrial fibrillation or sinus tachycardia; a pulseless patient with either needs CPR.

19. Question 19 of 25Medium

    In a hospital radiology department, a 59-year-old woman on a portable monitor collapses. During CPR, the AED analyzes her rhythm and states that no shock is advised, and the monitor shows a flat line. What should the rescuers do next?

    1. AA. Stop CPR, since no shock means the heart has started beating
    2. BB. Remove the pads and reapply them until a shock is advised
    3. CC. Wait beside her without CPR until the code team arrives
    4. DD. Resume chest compressions right away and continue CPR
    Show answer to question 19

    Answer: D. Resume chest compressions right away and continue CPR

    A flat line suggests asystole, which a shock cannot fix, so the AED advises no shock. CPR resumes at once, starting with compressions, and the rescuers keep following the AED's prompts.

    Why the other options are wrong

    • ANo shock advised does not mean a pulse has returned, and asystole is cardiac arrest.
    • BReapplying pads to force a shock wastes time, and asystole is not a shockable rhythm.
    • CWaiting without CPR leaves her brain and heart with no blood flow.

20. Question 20 of 25Medium

    At a primary care office, a 76-year-old man says he feels weak and dizzy. His strip shows regular P waves at 84 per minute and regular, wide QRS complexes at 36 per minute. The PR intervals vary with no pattern, and some P waves fall inside QRS complexes or T waves. Which rhythm does this describe?

    1. AA. Third-degree AV block
    2. BB. Idioventricular rhythm
    3. CC. Second-degree AV block type II
    4. DD. Second-degree AV block type I
    Show answer to question 20

    Answer: A. Third-degree AV block

    In third-degree (complete) AV block, no atrial impulses reach the ventricles, so the P waves and QRS complexes each keep their own regular rate with no relationship between them. A slow, wide escape rhythm like this one comes from the ventricles, and the technician reports it at once.

    Why the other options are wrong

    • BIdioventricular rhythm shows slow, wide QRS complexes without regular P waves marching through the strip at their own rate.
    • CIn type II block, conducted beats keep a constant PR interval, and only some P waves are not followed by a QRS.
    • DIn type I block, the PR interval lengthens in a repeating cycle until a QRS is dropped.

21. Question 21 of 25Medium

    During a home visit, a mobile EKG technician records a strip on an 83-year-old woman. Her sinus rhythm at 72 per minute is interrupted by one early beat with a narrow QRS that looks like the others. In lead II, the P wave in front of that beat is inverted, with a PR interval of 0.08 seconds. Which finding does this describe?

    1. AA. Premature atrial contraction
    2. BB. Premature junctional contraction
    3. CC. Premature ventricular contraction
    4. DD. Junctional escape beat
    Show answer to question 21

    Answer: B. Premature junctional contraction

    An early beat with a narrow QRS and an inverted P wave with a short PR interval in lead II starts in the AV junction. Because it arrives early, it is a premature junctional contraction (PJC).

    Why the other options are wrong

    • AA premature atrial contraction has a P wave that differs from the sinus P wave but usually keeps a PR interval of 0.12 seconds or longer.
    • CA premature ventricular contraction has a wide, bizarre QRS with no P wave before it.
    • DAn escape beat comes late, after a pause, rather than early.

22. Question 22 of 25Medium

    At an urgent care center, a 58-year-old woman's 6-second rhythm strip shows 8 QRS complexes. Using the 6-second method, what is her approximate heart rate?

    1. AA. 48 per minute
    2. BB. 80 per minute
    3. CC. 96 per minute
    4. DD. 160 per minute
    Show answer to question 22

    Answer: B. 80 per minute

    The 6-second method counts the QRS complexes in a 6-second strip and multiplies by 10, since ten 6-second periods make 1 minute. Eight complexes times 10 equals about 80 per minute.

    Why the other options are wrong

    • A48 per minute multiplies by 6, the number of seconds, instead of by 10.
    • C96 per minute multiplies by 12, which would fit a 5-second count, not a 6-second strip.
    • D160 per minute multiplies by 20, which would fit a 3-second count, not a 6-second strip.

23. Question 23 of 25Easy

    Which group of leads views the lateral wall of the left ventricle?

    1. AA. II, III and aVF
    2. BB. V1, V2, V3 and V4
    3. CC. I, aVL, V5 and V6
    4. DD. V3 and V4
    Show answer to question 23

    Answer: C. I, aVL, V5 and V6

    Leads I and aVL view the high lateral wall, and V5 and V6 view the lower lateral wall from the left side of the chest. Together they make up the lateral group.

    Why the other options are wrong

    • ALeads II, III and aVF form the inferior group.
    • BLeads V1 to V4 view the septum and the anterior wall.
    • DLeads V3 and V4 form the anterior group.

24. Question 24 of 25Easy

    At a community health center, a 47-year-old man's rhythm strip shows sinus rhythm with two wide, bizarre premature beats in a row before the sinus rhythm returns. What are two consecutive PVCs called?

    1. AA. Bigeminy
    2. BB. A couplet
    3. CC. Trigeminy
    4. DD. Quadrigeminy
    Show answer to question 24

    Answer: B. A couplet

    Two PVCs in a row are called a couplet, or a pair, and the technician notes them and reports them to the nurse or provider.

    Why the other options are wrong

    • ABigeminy means a PVC every second beat, alternating with normal beats.
    • CTrigeminy means a PVC every third beat, with two normal beats between PVCs.
    • DQuadrigeminy means a PVC every fourth beat, with three normal beats between PVCs.

25. Question 25 of 25Medium

    Why does the AV node normally slow the electrical impulse before passing it on to the ventricles?

    1. AA. To give the SA node time to recover before its next impulse
    2. BB. To let the atria finish emptying blood into the ventricles
    3. CC. To let the ventricles repolarize before the atria contract
    4. DD. To keep the impulse from reaching the Purkinje fibers
    Show answer to question 25

    Answer: B. To let the atria finish emptying blood into the ventricles

    The brief delay at the AV node gives the atria time to contract and finish filling the ventricles before the ventricles contract. This delay is reflected in the PR interval.

    Why the other options are wrong

    • AThe SA node recovers on its own; the AV node delay serves ventricular filling, not SA node recovery.
    • CVentricular repolarization comes after ventricular depolarization, later in the cycle, as the T wave.
    • DThe impulse must reach the Purkinje fibers for the ventricles to contract; the delay only slows it briefly.

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