Six Second ECG Quiz 3A Version 3.
The Six Second ECG
ECG Quiz 3A
Version 3.1
Annotated Answer Key
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Six Second ECG Quiz 3A v3.1 Annotated Answer Key
Annotated Answer Key
The Six Second ECG Quiz 3A (version 3.1)
This annotated answer key is provided for ECG instructors and students as a reference for the Six
Second ECG Quiz 3A (version 3.1). Answers and a brief explanation are provided.
Question 1
This ECG rhythm is called:
a) Sinus rhythm with aberrant intraventricular conduction
b) Accelerated idioventricular rhythm
c) Accelerated junctional rhythm with aberrant intraventricular conduction
d) Junctional tachycardia
Answer: b) Accelerated idioventricular rhythm
Explanation: This regular ECG rhythm consists of wide QRS complexes and a rate of about
90/minute. Evidence of P waves is found before the 3rd and 8th QRS complexes with different PR
intervals. This rhythm originates from the ventricles with a rate that is faster than a typical
ventricular rate (20-40/minute) but slower than a tachycardia (100/minute). The presence of P
waves peppered chaotically through this ECG rhythm (AV dissociation) also supports the decision
to call this an accelerated idioventricular rhythm.
Question 2
This ECG rhythm is called:
a) Agonal rhythm
b) Idioventricular rhythm
c) Junctional bradycardia
d) Sinus bradycardia with aberrant intraventricular conduction
Answer: a) Agonal rhythm
Explanation: This ECG rhythm is not uncommon with people with advanced heart disease at the
endpoint of cardiogenic shock and just prior to asystole. This rhythm is often referred to as an
agonal rhythm. Technically, this could also be called ventricular bradycardia. The very wide and
slow ventricular rhythm is almost always insufficient to sustain life.
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Six Second ECG Quiz 3A v3.1 Annotated Answer Key
Question 3
This ECG rhythm is called:
a) Fine ventricular fibrillation
b) Artifact
c) Ventricular standstill
d) Asystole
Answer: d) Asystole
Explanation: This ECG rhythm shows an absence of any waveforms. This could result from either
disconnected electrodes or the relative absence of any cardiac electrical activity. The latter option is
called asystole.
Question 4
This ECG rhythm is called:
a) Sinus rhythm
b) Junctional rhythm with artifact
c) Sinus bradycardia
d) Paced atrial rhythm
Answer: d) Paced atrial rhythm
Explanation: At first glance, this ECG rhythm appears to be a sinus rhythm: narrow QRS
complexes, upright P waves and a rate of about 60/minute. On closer inspection, every P wave is
immediately preceded by a vertical spike. This rhythm results from a paced atrium with a rate set at
about 60/minute. The atria are consistently captured.
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Six Second ECG Quiz 3A v3.1 Annotated Answer Key
Question 5
This ECG rhythm is called:
a) Sinus tachycardia with aberrant intraventricular conduction
b) Junctional tachycardia
c) Ventricular tachycardia
d) Supraventricular tachycardia (SVT)
Answer: c) Ventricular tachycardia
Explanation: This ECG rhythm presents with regular, rapid and wide QRS complexes. P waves are
not evident. While this rhythm could be a supraventricular tachycardia with aberrant ventricular
conduction, this rhythm is most likely ventricular tachycardia.
Note: While this rhythm is at times not associated with serious hemodynamic consequences, it is
common for ventricular tachycardia to cause hemodynamic compromise or collapse. Serious
hemodynamic consequences are linked to minimal ventricular filling time, lack of atrial kick and a
tendency for ventricular tachycardia to deteriorate to ventricular fibrillation.
Question 6
This ECG rhythm is called:
a) Multifocal atrial tachycardia
b) Coarse ventricular fibrillation
c) Ventricular tachycardia
d) Fine ventricular tachycardia
Answer: b) Coarse ventricular fibrillation
Explanation: As a general rule, chaotic rhythms tend to be associated with fibrillation. In this case,
the absence of any recognizable QRS complexes with a chaotic baseline is typical of ventricular
fibrillation. Ventricular fibrillation (VF) with amplitudes greater than 3mm is often referred to as
coarse ventricular fibrillation. Ventricular fibrillation with amplitudes less than 3mm is referred to
as fine ventricular fibrillation.
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Six Second ECG Quiz 3A v3.1 Annotated Answer Key
Question 7
This ECG rhythm is called:
a) Ventricular trigeminy
b) Junctional trigeminy
c) Sinus rhythm with premature atrial complexes (PACs)
d) Sinus arrhythmia with aberrant intraventricular conduction
Answer: a) Ventricular trigeminy
Explanation: The underlying ECG rhythm presents with narrow QRS complexes, upright P waves
and a rate of about 80/minute. The underlying rhythm is a sinus rhythm. Every third QRS complex
is wide and arrives prematurely. These are premature ventricular complexes (PVCs). While this
ECG rhythm could be called a sinus rhythm with unifocal PVCs, since the PVCs occur every third
QRS complex, this ECG rhythm is commonly referred to as ventricular trigeminy.
Question 8
This ECG rhythm is called:
a) Ventricular standstill
b) Idioventricular rhythm
c) Agonal rhythm
d) Ventricular fibrillation
Answer: a) Ventricular standstill
Explanation: While this rhythm could be a accelerated idioventricular rhythm with low amplitude,
this option is extremely unlikely (amplitude of only 2-3 mm). Rather, this ECG rhythm is only a
collection of regularly occurring P waves without QRS complexes. This ECG rhythm is called
ventricular standstill. Effectively similar to asystole, ventricular standstill might be one initial
outcome of third degree AV block with a failed ventricular pacemaker.
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Six Second ECG Quiz 3A v3.1 Annotated Answer Key
Question 9
This ECG rhythm is called:
a) Sinus bradycardia with aberrant intraventricular conduction
b) Idioventricular rhythm
c) Paced ventricular rhythm
d) Junctional rhythm with non-conducted premature atrial complexes
Answer: c) Paced ventricular rhythm
Explanation: The narrow vertical spike immediately preceding each QRS complex is useful
evidence for a paced ventricular rhythm.
Note: The P waves march through this rhythm without any relationship to the QRS complexes (i.e.
the PR interval is chaotic). Without the paced ventricular complexes, the underlying rhythm would
be third degree AV block or possibly even ventricular standstill.
Question 10
This ECG rhythm is called:
a) Ventricular tachycardia
b) Multifocal atrial tachycardia
c) Sinus rhythm with artifact
d) Torsades de Pointes
Answer: d) Torsades de Pointes
Explanation: This ECG rhythm shows a chaotic pattern but pieces of this rhythm also present with
rapid and wide QRS complexes – albeit with varying morphologies (shapes). There appears to be
segments of ventricular fibrillation alternating with runs of polymorphic ventricular tachycardia. If
this rhythm played out further, another pattern would be appear – a cyclical pattern of increasing
then decreasing amplitude. The presence of all of these characteristics form a rhythm called
torsades de pointes (twists of the pointes). Torsades de pointes is often associated with rhythms that
present with prolonged QT intervals.
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Six Second ECG Quiz 3A v3.1 Annotated Answer Key
Question 11
This ECG rhythm is called:
a) Sinus rhythm
b) Paced rhythm with complete loss of capture
c) Accelerated junctional rhythm
d) Junctional tachycardia
Answer: b) Paced rhythm with complete loss of capture
Explanation: At first glance, this ECG rhythm sports regularly occurring narrow QRS complexes
at a rate of 70/minute. On a second look, a number of pieces are missing from this ECG such as P
waves and T waves. Also of interest is the QRS complex being so narrow at about 0.02 seconds
(½ mm). Putting this evidence together (of course, knowing the patient would be of great help
here), these narrow complexes are electronic pacer spikes only. Since no QRS complexes are
generated, this is called a paced rhythm with a complete loss of capture. The patient is in asystole.
Question 12
This ECG rhythm is called:
a) Idioventricular rhythm
b) Sinus bradycardia
c) Junctional bradycardia
d) Paced ventricular rhythm
Answer: a) Idioventricular rhythm
Explanation: This ECG rhythm consists of a slow and regular series of wide QRS complexes,
occurring at a rate of 40/minute. P waves are absent. This is most likely an idioventricular rhythm
(only ventricular). This rhythm could also be correctly called a ventricular escape rhythm with a
rate of 40/minute or just a ventricular rhythm with a rate of 40/minute. Less likely is the possibility
that this ECG rhythm is a junctional rhythm with aberrant intraventricular conduction.
Note: The polarity of the QRS complex is opposite to the polarity of the T wave, a fairly common
phenomenon with ventricular beats.
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Six Second ECG Quiz 3A v3.1 Annotated Answer Key
Question 13
This ECG rhythm is called:
a) Sinus rhythm
b) Paced ventricular rhythm
c) Paced AV sequential rhythm
d) Accelerated idioventricular rhythm
Answer: c) Paced AV sequential rhythm
Explanation: This ECG rhythm presents with regularly occurring upright P waves consistently
preceding wide QRS complexes at a rate of about 80/minute. While the evidence is compelling for
this to be a sinus rhythm with aberrant intraventricular conduction, the addition of vertical spikes
placed consistently before both each P wave and each wide QRS complex makes this ECG rhythm
a paced AV sequential rhythm instead. This results from a dual chamber pacer that is consistently
capturing first the atria and then the ventricles.
Question 14
This ECG rhythm is called:
a) Atrial fibrillation with premature ventricular complexes (PVCs)
b) Sinus rhythm with premature atrial complexes (PACs)
c) Ventricular bigeminy
d) Junctional rhythm with PACs
Answer: c) Ventricular bigeminy
Explanation: The underlying ECG rhythm presents with narrow QRS complexes, upright P waves
and a rate of about 80/minute. The underlying rhythm is a sinus rhythm. Every second QRS
complex is wide and arrives prematurely. These are premature ventricular complexes (PVCs).
While this ECG rhythm could be called a sinus rhythm with unifocal PVCs, since the PVCs occur
every second QRS complex, this ECG rhythm is commonly referred to as ventricular bigeminy.
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Six Second ECG Quiz 3A v3.1 Annotated Answer Key
Question 15
This ECG rhythm is called:
a) Sinus rhythm with ST depression and multifocal PVCs
b) Sinus rhythm with ST depression, ventricular couplets and a PVC
c) Accelerated junctional rhythm with ST depression and a PVCs
d) Sinus rhythm with ST depression and PACs
Answer: b) Sinus rhythm with ventricular couplets and a PVC
Explanation: The underlying ECG rhythm features upright P waves and narrow QRS complexes
with ST depression (2 mm) occurring at a rate of about 75/minute. The underlying rhythm is a sinus
rhythm with ST depression. The underlying rhythm is interrupted by two sets of ventricular
couplets and completed by a single PVC. This ECG rhythm certainly demonstrates ventricular
irritability.
