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Quizzes > Health & Medicine

ECG Test Online: Basic Interpretation Quiz

Short, free ECG quiz for beginners. Instant results and feedback.

Editorial: Review CompletedCreated By: Jeff R OlsonUpdated Aug 23, 2025
Difficulty: Moderate
2-5mins
Learning OutcomesCheat Sheet
Paper art ECG waveforms heart icon on dark blue background quiz Challenge yourself free basic ECG rhythm wave recognition

This quiz helps you practice basic ECG interpretation by reading rhythm strips and naming common waves and intervals. For more focused rhythm work, try the ecg arrhythmia quiz, or build broader knowledge with cardiology quiz questions and answers. Preparing for emergencies? Check your skills with an acls practice test.

What does the P wave on a standard 12-lead ECG represent?
AV nodal delay
Atrial depolarization
Ventricular depolarization
Atrial repolarization
The P wave reflects the electrical activity as the atria depolarize before contraction. Atrial repolarization occurs during the QRS complex and is usually hidden. Ventricular depolarization is represented by the QRS complex. For more detail on waveform origins, see .
What is the normal duration of the PR interval on an ECG?
>300 ms
120 - 200 ms
200 - 300 ms
80 - 120 ms
The PR interval, measured from the start of the P wave to the start of the QRS complex, normally ranges from 120 to 200 ms. Intervals shorter than 120 ms suggest pre-excitation, while longer intervals indicate AV conduction delay. See standard guidelines at .
What is the maximum normal duration of the QRS complex?
120 - 160 ms
< 120 ms
< 80 ms
> 160 ms
A normal QRS complex duration is under 120 ms, reflecting synchronous ventricular depolarization. Durations ?120 ms suggest bundle branch block or intraventricular conduction delay. For conduction timings and clinical significance, refer to .
Which heart rate range is considered normal sinus rhythm in adults?
40 - 60 beats per minute
120 - 140 beats per minute
100 - 120 beats per minute
60 - 100 beats per minute
A heart rate between 60 and 100 bpm with one P wave before each QRS defines normal sinus rhythm. Rates below 60 bpm indicate bradycardia, while above 100 bpm indicate tachycardia. Detailed heart rate interpretation is available at .
Which ECG finding is most characteristic of atrial fibrillation?
Regular P waves with a fixed PR interval
Absence of P waves and irregularly irregular QRS timing
Progressive PR prolongation followed by dropped QRS
Sawtooth atrial waves in inferior leads
Atrial fibrillation is marked by absent organized P waves and an irregularly irregular ventricular response. Sawtooth waves are seen in atrial flutter, not fibrillation. For ECG characteristics of AF, see .
What minimum ST-segment elevation is required in two contiguous leads to diagnose an acute myocardial infarction?
? 1 mm
? 3 mm
? 0.5 mm
? 2 mm
The current universal definition of STEMI requires ?1 mm of ST-segment elevation in two contiguous leads (or ?2 mm in V2 - V3 in men). Smaller elevations may indicate other conditions. See the consensus document at .
Which ECG criteria are consistent with a left bundle branch block?
QRS ? 120 ms with broad, notched R waves in leads I, V5, V6
QRS ? 120 ms with rSR' pattern in V1
QRS < 120 ms with ST depression in V1 - V3
QRS < 100 ms with small q waves in lateral leads
LBBB is defined by a QRS duration ?120 ms and broad, often notched or slurred R waves in leads I, V5, and V6 without initial Q waves. The rSR' in V1 suggests RBBB. Review bundle branch block criteria at .
Which pattern is indicative of second-degree AV block type I (Wenckebach)?
Constant PR intervals with 2:1 conduction
Irregular P waves with no QRS correlation
Progressive PR lengthening with eventual dropped QRS
Fixed PR interval with occasional dropped QRS
Mobitz type I (Wenckebach) shows progressive prolongation of the PR interval until a P wave is not conducted, then resets. 2:1 conduction or constant PR suggests other block types. See details at .
Which ECG finding differentiates Mobitz type II second-degree AV block?
Alternating 2:1 conduction ratio
Sudden nonconducted P wave without PR change
Progressive PR prolongation prior to a dropped QRS
Irregularly irregular R-R intervals
In Mobitz type II block, a P wave fails to conduct without preceding PR interval prolongation. Progressive PR lengthening indicates Mobitz I. Type II can progress rapidly to complete block. More at .
ST-segment elevation in leads V1 through V4 is most indicative of infarction in which myocardial region?
Lateral wall
Anterior wall
Inferior wall
Posterior wall
Leads V1 - V4 view the anterior interventricular septum and anterior wall supplied by the left anterior descending artery. ST elevation here indicates an acute anterior MI. For lead localization, see .
Which formula is commonly used to correct the QT interval for heart rate (QTc)?
Bazett's formula: QTc = QT / ?RR
Framingham formula: QTc = QT + 0.154(1 - RR)
Rautaharju formula: QTc = QT + 0.37(RR - 1)
Fridericia formula: QTc = QT / RR^(1/3)
Bazett's formula (QTc = QT/?RR) is the most widely used method to correct QT for heart rate, though it may overcorrect at high or low rates. Framingham and Fridericia are alternatives with different adjustments. Details at .
Which ECG finding is characteristic of arrhythmogenic right ventricular cardiomyopathy (ARVC)?
Epsilon waves in leads V1 - V3
Large Q waves in inferior leads
Delta waves in precordial leads
Tall T waves in lateral leads
Epsilon waves are small positive deflections at the end of the QRS in V1 - V3 and are a hallmark of ARVC. Delta waves indicate pre-excitation (Wolff-Parkinson-White). For ARVC ECG features, see .
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Study Outcomes

  1. Understand ECG Waveform Components -

    Learn to recognize the P wave, QRS complex, and T wave on an ECG trace and explain their roles in cardiac physiology.

  2. Identify Normal Versus Abnormal Rhythms -

    Distinguish between regular, tachycardic, and bradycardic patterns to pinpoint common rhythm deviations in this basic ECG quiz.

  3. Analyze Key Intervals and Segments -

    Measure PR intervals, QT intervals, and ST segments accurately and assess their clinical significance in ECG interpretation.

  4. Apply Lead Placement Principles -

    Understand how correct electrode positioning affects waveform appearance and troubleshoot common placement errors during ECG practice tests.

  5. Evaluate Your Interpretation Skills -

    Use scenario-based questions in this ECG interpretation quiz to gauge your proficiency and reinforce learn ECG basics effectively.

Cheat Sheet

  1. Identify PQRST Waveforms -

    The PQRST complex forms the foundational basis for any basic ECG quiz and ecg practice test, representing atrial depolarization (P wave), ventricular depolarization (QRS complex), and ventricular repolarization (T wave). Use the mnemonic "Perky Queens Quickly Triumph" to sequence the phases, making it easier to learn ecg basics. Accurate wave recognition boosts confidence when you tackle an ecg interpretation quiz.

  2. Calculate Heart Rate Efficiently -

    A quick method from the American Heart Association suggests counting large boxes between R-R intervals: Heart rate = 300 ÷ number of large squares, ideal for any ecg quiz online. This formula sharpens your skill set during a basic ECG quiz and ecg practice test. Regular rate calculation practice helps you recognize tachycardia and bradycardia patterns instantly.

  3. Measure Key Intervals Precisely -

    According to ACC/AHA guidelines, normal PR intervals range from 120 - 200 ms, QRS duration is under 120 ms, and QTc uses Bazett's formula (QTc=QT/√RR) to adjust for rate. Mastering these benchmarks is central to acing an ecg interpretation quiz and essential when you learn ecg basics. Precise interval measurements help detect conduction delays and repolarization issues.

  4. Recognize Core Arrhythmias -

    Spot atrial fibrillation's "irregularly irregular" rhythm or PVCs' premature broad QRS complexes by referencing peer-reviewed cardiology resources. The "TAP" mnemonic (Tachyarrhythmia, Atrial, Premature) streamlines recall during an ecg quiz online or ecg practice test. Frequent exposure to rhythm strips builds pattern recognition muscle memory.

  5. Use a Systematic Interpretation Checklist -

    Apply the RRAIM approach - Rhythm, Rate, Axis, Intervals, Morphology - recommended by leading medical schools to ensure no element is overlooked. This stepwise framework enhances performance on a basic ECG quiz or any ecg interpretation quiz. Consistent use of RRAIM cements a reliable method as you learn ecg basics and integrate them into clinical care.

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