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Quizzes > Health & Medicine

Agonal vs Idioventricular Rhythm: ECG Strip Quiz

Quick, free quiz to test your ECG strip skills on the agonal rhythm strip. Instant results.

Editorial: Review CompletedCreated By: Chapman MphaUpdated Aug 26, 2025
Difficulty: Moderate
2-5mins
Learning OutcomesCheat Sheet
Paper art ECG quiz illustration with heart monitor waves, electrodes, rhythm strips on golden yellow background

This quiz helps you recognize agonal vs idioventricular rhythm on ECG strips and make confident calls. After you finish, sharpen timing and pattern reading with the 6 second ecg quiz, explore wider cases in the dysrhythmia quiz, or refresh basics in an ecg quiz for beginners.

What is the typical ventricular rate seen in idioventricular rhythm?
Greater than 100 beats per minute
20 to 40 beats per minute
Less than 20 beats per minute
40 to 60 beats per minute
Idioventricular rhythm originates from ventricular Purkinje fibers and typically presents with a rate between 20 and 40 beats per minute. Rates below 20 bpm are more characteristic of an agonal rhythm. This slow escape mechanism occurs when the sinus and AV nodal pacemakers fail to fire. You can read more about idioventricular rhythm on the Life in the Fast Lane website .
Which ventricular rate most accurately describes an agonal rhythm on an ECG strip?
60 to 100 beats per minute
Greater than 100 beats per minute
Less than 20 beats per minute
40 to 60 beats per minute
Agonal rhythm is a preterminal rhythm identified by extremely slow ventricular complexes usually less than 20 beats per minute. It results from a dying heart when higher pacemakers cease function. Early recognition and initiation of resuscitation are critical. More information on agonal rhythm can be found at Life in the Fast Lane .
In idioventricular rhythm, the P waves are typically:
Variable and coincide with T waves
Visible before every QRS complex
Retrograde with a constant PR interval
Hidden within or absent
Since the ventricular focus acts as the primary pacemaker in idioventricular rhythm, sinus P waves are usually absent or buried within the wide QRS complexes. There is often AV dissociation, and atrial activity does not capture the ventricles. This is a hallmark feature of ventricular escape rhythms. See more on this at Life in the Fast Lane .
What is the minimum QRS duration expected in ventricular rhythms such as agonal or idioventricular rhythms?
100 to 120 milliseconds
Less than 120 milliseconds
80 to 100 milliseconds
Greater than 120 milliseconds
Ventricular rhythms originate distally in the Purkinje system and therefore produce wide QRS complexes typically greater than 120 milliseconds. Such prolongation reflects slower cell-to-cell conduction in ventricular myocardium. Narrow QRS complexes (<120 ms) are more indicative of supraventricular rhythms. For further details visit .
Which part of the cardiac conduction system is responsible for initiating an idioventricular rhythm?
Sinoatrial node
Atrioventricular node
Bundle of His
Purkinje fibers
An idioventricular rhythm arises from an ectopic focus in the Purkinje fibers of the ventricles when higher pacemakers fail. The Purkinje network produces slower, wide-complex ventricular escape beats. The AV node and SA node are not involved once ventricular escape takes over. Learn more at .
What rate range defines an accelerated idioventricular rhythm (AIVR)?
Less than 20 beats per minute
40 to 60 beats per minute
Greater than 100 beats per minute
20 to 40 beats per minute
Accelerated idioventricular rhythm is characterized by a ventricular rate faster than the intrinsic idioventricular escape (typically 40 - 60 bpm) but below ventricular tachycardia thresholds. It often occurs transiently, particularly during reperfusion after myocardial infarction. Rates below 40 are classic idioventricular, while >100 suggest VT. See for more.
Which rhythm is considered the ultimate terminal rhythm in cardiac arrest and is nearly always pulseless?
Idioventricular rhythm
Accelerated idioventricular rhythm
Ventricular tachycardia
Agonal rhythm
Agonal rhythm represents a preterminal state with extremely slow, wide ventricular complexes often less than 20 bpm and is essentially pulseless. It signifies near death and requires immediate resuscitation efforts. Idioventricular rhythms may have a pulse if ?20 bpm. More on agonal rhythm at .
In which clinical setting is idioventricular rhythm most commonly observed?
Exercise-induced tachycardia
Hyperthyroidism
Post-myocardial infarction reperfusion
Hypokalemia
Idioventricular rhythms often emerge transiently during reperfusion therapy after acute myocardial infarction, reflecting return of blood flow to ischemic myocardium. This reperfusion arrhythmia is generally benign and self-limited. It differs from VT in rate and hemodynamic stability. See details at .
What is the recommended initial management for a hemodynamically stable idioventricular rhythm?
Immediate defibrillation
Immediate synchronized cardioversion
Atropine administration
No specific treatment if stable
Hemodynamically stable idioventricular rhythms are typically benign escape rhythms that do not require acute intervention aside from monitoring. Management focuses on identifying and treating underlying causes. Atropine may be considered if symptomatic bradycardia occurs. More on management at .
Which of the following distinguishing features helps differentiate accelerated idioventricular rhythm (AIVR) from ventricular tachycardia (VT)?
Monomorphic QRS complexes
Presence of fusion beats
Visible P waves before every QRS complex
Ventricular rate less than 100 beats per minute
Accelerated idioventricular rhythm typically has a rate between 40 and 100 bpm, distinguishing it from ventricular tachycardia, which usually exceeds 100 bpm. Fusion beats can occur in VT but are not the key rate-based differentiator. AIVR often presents monomorphically but so can VT. Learn more at .
What is the immediate recommended intervention for agonal rhythm observed during advanced life support?
Immediate defibrillation
Give high-dose dopamine
Administer intravenous magnesium
Chest compressions and epinephrine as for PEA
Agonal rhythm is treated as pulseless electrical activity (PEA) in ACLS protocols. This requires immediate high-quality chest compressions and administration of epinephrine. Defibrillation is reserved for shockable rhythms like VF or pulseless VT. For algorithms, refer to the AHA ACLS guidelines .
Which ECG finding is most indicative of AV dissociation in ventricular rhythms?
Fusion beats
Shortened QT interval
Fixed PR intervals
Capture beats
Fusion beats occur when a sinus impulse and a ventricular impulse simultaneously depolarize the ventricles, creating a hybrid QRS complex. Their presence is a hallmark of AV dissociation in ventricular rhythms. Capture beats can also indicate AV dissociation but are less frequent. For further reading, visit .
An ECG shows very slow wide QRS complexes below 20 bpm with no palpable pulse. What is the most accurate description of this rhythm?
Sinus bradycardia
Idioventricular rhythm
Pulseless electrical activity (PEA)
First-degree AV block
When very slow wide-complex rhythms (<20 bpm) produce no measurable pulse, this scenario represents pulseless electrical activity (PEA). Although the ECG may resemble agonal or idioventricular rhythms, the absence of mechanical output confirms PEA. Immediate ACLS measures are indicated. More details can be found at .
Which criterion distinguishes wandering atrial pacemaker (WAP) from multifocal atrial tachycardia (MAT)?
Presence of at least three different P-wave morphologies
Fixed PR interval
QRS duration greater than 120 ms
P-wave rate exceeding 100 beats per minute
Both WAP and MAT have at least three different P-wave morphologies, but MAT is defined by an atrial rate exceeding 100 bpm. Wandering atrial pacemaker occurs at rates below 100 bpm and is generally benign. Recognition of the rate criterion is essential for accurate differentiation. Learn more at .
Which of these rhythms could be mistaken for ventricular tachycardia but is actually a benign sign of reperfusion after myocardial infarction?
Torsades de pointes
Idioventricular rhythm
Ventricular flutter
Accelerated idioventricular rhythm
Accelerated idioventricular rhythm is often seen transiently during reperfusion after an acute myocardial infarction and can mimic ventricular tachycardia on ECG. It is typically benign and self-limited, requiring no specific treatment if the patient remains stable. Idioventricular rhythm and VT have different rate thresholds. More at .
Which electrolyte disturbance is most likely to predispose a patient to idioventricular rhythms?
Hyperkalemia
Hypocalcemia
Hypernatremia
Hypokalemia
Hyperkalemia slows conduction and decreases the resting membrane potential in ventricular myocardium, promoting wide QRS complexes and ventricular escape rhythms like idioventricular rhythm. Prompt recognition and correction of serum potassium levels are crucial. Hypokalemia more commonly causes U waves and torsades. See electrolyte arrhythmias at .
What is the first-line pharmacologic treatment for symptomatic idioventricular rhythm causing hypotension?
Propranolol
Amiodarone
Lidocaine
Atropine
Atropine is the first-line therapy for symptomatic bradyarrhythmias, including idioventricular rhythms causing hypotension, as per ACLS guidelines. It enhances AV nodal conduction and increases heart rate. Antiarrhythmic drugs like lidocaine are reserved for ventricular tachyarrhythmias. Consult AHA ACLS guidelines .
Following a brief period of asystole on the monitor, a patient exhibits very slow, wide QRS escape complexes around 15 bpm. How is this rhythm best described?
Agonal rhythm
Accelerated idioventricular rhythm
Third-degree AV block
Ventricular tachycardia
Agonal rhythm is characterized by extremely slow (often <20 bpm), wide ventricular escape complexes that occur as a terminal rhythm after asystole. It indicates a dying heart and requires immediate resuscitation measures. AIVR has faster rates (40 - 60 bpm), and AV block exhibits distinct atrial and ventricular rates. More information at .
In ACLS, how is agonal rhythm classified and treated?
Non-shockable rhythm treated as pulseless electrical activity
Shockable rhythm treated with defibrillation
Arrhythmia requiring immediate transcutaneous pacing
Bradycardic rhythm treated with atropine only
Agonal rhythm is considered a non-shockable rhythm and is managed according to pulseless electrical activity (PEA) protocols, including high-quality CPR and epinephrine. Defibrillation is not indicated for non-shockable rhythms. Transcutaneous pacing and atropine may be used later in bradycardia algorithms but not as initial treatment. Refer to AHA ACLS guidelines .
What is the primary electrophysiological mechanism underlying idioventricular rhythms?
Increased vagal tone on the AV node
Enhanced automaticity of Purkinje fibers
Triggered activity due to early afterdepolarizations
Re-entry circuit within the ventricle
Idioventricular rhythms arise from enhanced automaticity of Purkinje fibers when higher pacemakers fail. This increased phase 4 depolarization in Purkinje cells allows them to assume pacing responsibility. Re-entry and triggered activity are mechanisms in other ventricular arrhythmias. Learn more at .
The appearance of accelerated idioventricular rhythm (AIVR) shortly after reperfusion therapy in MI is best interpreted as:
Evidence of extension of myocardial necrosis
Indicative of permanent damage requiring pacing
A warning sign of reinfarction
A benign reperfusion arrhythmia suggesting vessel patency
Accelerated idioventricular rhythm frequently occurs as a benign arrhythmia during reperfusion after acute myocardial infarction, indicating successful restoration of blood flow. It typically resolves spontaneously without intervention. It is not a sign of reinfarction or necrosis extension. Read more at .
In an acute myocardial infarction before reperfusion, the sudden emergence of idioventricular rhythm often signifies:
Increased vagal tone
Early reperfusion
Digitalis toxicity
Development of high-grade AV block
Before reperfusion, idioventricular escape rhythms in the setting of acute MI reflect failure of the sinus and AV nodes (high-grade AV block), leading to a ventricular pacemaker takeover. This is different from reperfusion-related AIVR. Recognition guides the need for pacing. More details at .
Toxicity of which medication classically predisposes patients to idioventricular rhythms?
Beta-blockers
Digitalis glycosides
Potassium-sparing diuretics
Calcium channel blockers
Digitalis toxicity enhances automaticity in ventricular myocardium and can precipitate idioventricular rhythms among other ventricular arrhythmias. Recognition of digitalis-related ECG changes and serum levels is essential for management. Beta-blockers and calcium channel blockers more commonly cause AV nodal blockade. For more, see .
Which ECG finding helps differentiate agonal rhythm from true asystole?
Presence of occasional wide QRS complexes
Regular narrow QRS complexes
Complete absence of electrical activity
Constant PR intervals
Agonal rhythm is distinguished from asystole by the presence of occasional wide QRS escape complexes amid long pauses. Asystole is defined by a flatline with no discernible electrical activity. Early identification of these complexes is crucial for resuscitative efforts. Further information at .
What is the physiological role of an idioventricular rhythm?
Acts as a backup pacemaker when sinus and AV nodes fail
Serves to increase heart rate during exercise
Indicates failure of ventricular myocardium to depolarize
Increases cardiac contractility during shock
An idioventricular rhythm provides a ventricular escape mechanism when higher pacemaking centers in the SA and AV nodes cease firing, ensuring minimal perfusion. It is a protective, compensatory rhythm rather than a chronotropic response to stress. This secondary pacing helps maintain some circulation until normal activity resumes or intervention occurs. More details at .
How can you distinguish a ventricular escape beat from a premature ventricular complex (PVC) on ECG?
Escape beats are followed by a compensatory pause
PVCs are preceded by a long pause
PVCs always have narrow QRS complexes
Escape beats are preceded by a pause longer than the normal R-R interval
A ventricular escape beat occurs after a pause longer than the anticipated R-R interval when no higher pacemaker fires, whereas PVCs interrupt the normal rhythm and are typically followed by a compensatory pause. PVCs also occur earlier than expected. Recognizing the preceding pause is key. For more on this distinction, visit .
Which beat is characterized by a QRS complex identical to the native QRS morphology during ventricular arrhythmias?
Premature ventricular complex
Fusion beat
Capture beat
Escape beat
A capture beat occurs when a sinus impulse briefly 'captures' the ventricles during ventricular tachycardia or idioventricular rhythm, producing a QRS complex identical to the native normal QRS. This feature is useful in diagnosing ventricular tachyarrhythmias. Fusion beats, by contrast, have hybrid morphologies. Learn more at .
Accelerated idioventricular rhythm often involves an increased slope of phase 4 depolarization due to enhanced activity of which ionic current?
Funny current (If)
L-type calcium current (ICa-L)
Inward rectifier potassium current (IK1)
Transient outward potassium current (Ito)
The slope of phase 4 depolarization in pacemaker cells is largely determined by the funny current (If), carried by hyperpolarization-activated cyclic nucleotide-gated channels. Enhanced If activity in Purkinje fibers can lead to increased automaticity seen in AIVR. Other currents play roles in different phases of action potentials. More on electrophysiology at .
A right bundle branch block (RBBB) pattern observed during idioventricular rhythm suggests the ectopic focus is located in the:
Right atrium
Interventricular septum
Left ventricle
Right ventricle
During idioventricular rhythms, a right bundle branch block pattern indicates that the depolarization wavefront originates in the left ventricle and travels towards the right, causing delayed right ventricular activation. Conversely, a left bundle branch block pattern suggests a right ventricular origin. This axis deviation helps localize the ectopic focus. For more, see .
According to advanced arrhythmia management, when is transvenous pacing indicated for idioventricular rhythms?
Only if QRS duration exceeds 200 ms
After administration of intravenous lidocaine
Immediately upon detection of any idioventricular rhythm
In symptomatic patients with hypotension unresponsive to atropine
Transvenous pacing is indicated for idioventricular rhythms when patients exhibit symptomatic hemodynamic compromise, such as severe hypotension, and do not respond to first-line therapies like atropine. It provides reliable ventricular stimulation when escape rhythms are inadequate. QRS duration alone is not an indication. Consult ACLS pacing guidelines at .
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Study Outcomes

  1. Differentiate agonal vs idioventricular rhythms -

    Recognize and compare characteristic QRS morphologies and rate patterns to accurately distinguish between agonal vs idioventricular rhythm strips.

  2. Identify wandering atrial pacemaker ecg strip features -

    Spot hallmark P wave variability and irregular rhythms on a wandering atrial pacemaker strip to enhance recognition of atrial pacemaker shifts.

  3. Interpret idioventricular rhythm strips -

    Analyze broad QRS complexes and assess ventricular rates to confidently diagnose idioventricular rhythm strips.

  4. Analyze six-second ECG segments -

    Apply a structured six-second method to swiftly measure intervals and rates across diverse ECG patterns for efficient rhythm analysis.

  5. Apply a systematic ECG evaluation approach -

    Use a step-by-step framework to integrate rate, rhythm, and waveform criteria when assessing complex strips like agonal vs idioventricular rhythms and wandering atrial pacemaker ecg strip cases.

  6. Assess self-performance with instant feedback -

    Leverage quiz feedback to identify strengths and gaps in your ECG strip mastery and guide targeted improvement.

Cheat Sheet

  1. Rate and QRS Width Distinction -

    Agonal vs idioventricular rhythm differentiation often hinges on rate: idioventricular rhythms run 20 - 40 bpm with a regular wide QRS, whereas agonal rhythms typically slow to <20 bpm and appear more irregular or sporadic. Use the "SLOW HONOR" mnemonic (Slow, Irregular, Wide QRS) to reinforce recognition (American Heart Association guidelines). Spotting these rate cutoffs on idioventricular rhythm strips can guide immediate management.

  2. P Wave Analysis -

    In idioventricular rhythms, P waves are usually absent or dissociated because the ventricles take over as the pacemaker; by contrast, an agonal rhythm might display occasional, erratic atrial activity without organized P waves. Reviewing wandering atrial pacemaker ecg strip examples helps solidify P wave variability - look for at least three distinct P morphologies in a wandering atrial pacemaker strip. This tactic, endorsed by electrophysiology texts, ensures accurate atrial vs. ventricular source identification.

  3. Clinical Context and Significance -

    Idioventricular rhythm strips often signify an accelerated escape rhythm protective against asystole, whereas agonal rhythms portend impending cardiac arrest requiring immediate ACLS interventions. Familiarize yourself with clinical scenarios from peer-reviewed journals showing idioventricular escape in acute myocardial infarction versus agonal onset during terminal events. Recognizing these patterns fast supports timely defibrillation or drug therapy per ACLS algorithms.

  4. Wandering Atrial Pacemaker Hallmarks -

    On a wandering atrial pacemaker ecg strip, P wave morphology shifts across at least three forms, the PR interval varies, and the rate remains below 100 bpm - remember "P-Party" (Plural P-waves, PR variability, Rate <100). This friendly mnemonic, cited in cardiology teaching resources, instantly flags a wandering atrial pacemaker strip versus other supraventricular rhythms. Compare side-by-side examples in clinical ECG atlases to reinforce pattern recognition.

  5. Systematic ECG Interpretation Algorithm -

    Apply a four-step approach - Rate, Rhythm, Axis/QRS, and P waves - when reviewing idioventricular rhythm strips or agonal tracings to avoid oversight. Renowned university cardiology courses recommend this checklist for precision and speed, boosting confidence under pressure. Practice with free scored quizzes to master this algorithm and track progress in real time.

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