Regularity: regular

Rate: 52 bpm

P Waves: upright and

uniform

PRI: 0.16 second and

constant

QRS: 0.10 second

Interp: Sinus Bradycardia

9.222

Answers Key 579

Regularity: very slightly

irregular

Rate: 35 bpm

P Waves: none

PRI: none

QRS: 0.18 second

Interp: Idioventricular

Rhythm

9.223

Regularity: regular

Rate: atrial rate 60 bpm;

ventricular rate 58 bpm

P Waves: upright and

uniform

PRI: none

QRS: 0.14 second

Interp: Third-Degree Heart

Block (CHB) with a ventricular escape focus

9.224

Note: The nearly identical atrial and ventricular rates

make it difficult to identify; however, the P waves

“marching through” the QRS complexes confirms

A–V dissociation.

Regularity: regular

Rate: 56 bpm

P Waves: upright and

uniform

PRI: 0.20 second and

constant

QRS: 0.08 second

Interp: Sinus Bradycardia

9.225

Regularity: irregular

Rate: atrial rate 375 bpm;

ventricular rate approximately 60 bpm

P Waves: characteristic

sawtooth pattern

PRI: none

QRS: 0.08 second

Interp: Atrial Flutter with

variable response

9.226

Regularity: regular

Rate: 130 bpm

P Waves: upright and

uniform

PRI: 0.12 second and

constant

QRS: 0.08 second

Interp: Sinus Tachycardia

9.227

Regularity: regular

Rate: 136 bpm

P Waves: none discernible

PRI: none discernible

QRS: 0.10 second

Interp: Supraventricular

Tachycardia

9.228

Regularity: regular

underlying rhythm

interrupted by ectopics

Rate: 68 bpm (underlying

rhythm)

P Waves: upright and

uniform

PRI: 0.12 second

QRS: 0.08 second in

underlying rhythm; 0.16–

0.20 second in ectopics

Interp: Sinus Rhythm with

two multifocal PVCs

9.229

Regularity: irregular

Rate: approximately

70 bpm

P Waves: none

PRI: none

QRS: 0.10 second

Interp: Atrial Fibrillation,

controlled

9.230

Regularity: irregular

Rate: approximately

80 bpm

P Waves: upright and

uniform

PRI: 0.14 second and

constant

QRS: 0.10 second

Interp: Sinus Arrhythmia

9.231

Regularity: irregular

Rate: approximately

100 bpm

P Waves: upright and

uniform

PRI: 0.12 second and

constant

QRS: 0.08 second

Interp: Sinus Arrhythmia

9.232

Regularity: regular

Rate: 59 bpm

P Waves: none

PRI: none

QRS: 0.12 second

Interp: Junctional Escape

Rhythm

9.233

Regularity: regular

Rate: 52 bpm

P Waves: upright and

uniform

PRI: 0.24 second and

constant

QRS: 0.08 second

Interp: Sinus Bradycardia

with First-Degree Heart

Block

9.234

Regularity: regular underlying rhythm interrupted

by ectopics

Rate: 83 bpm (underlying

rhythm)

P Waves: uniform and

upright

PRI: 0.18 second

QRS: 0.08 second

(underlying rhythm);

0.16 second (ectopics);

ectopics have bizarre

configuration

Interp: Sinus Rhythm with

one PVC and a run of

three PVCs, all unifocal

9.235

Regularity: slightly irregular underlying rhythm

interrupted by ectopics

in a pattern of grouped

beating

Rate: approximately

83 bpm according to

visible P waves

P Waves: upright and

uniform

PRI: 0.16 second and constant (underlying rhythm)

QRS: 0.08 second (underlying rhythm); 0.16 second (ectopics)

Interp: Sinus Rhythm with

trigeminy of PVCs

9.236

Regularity: regular

Rate: 48 bpm

P Waves: upright and

uniform

PRI: 0.16 second and

constant

QRS: 0.08 second

Interp: Sinus Bradycardia

9.237

Regularity: slightly irregular

Rate: approximately

58 bpm

P Waves: upright and

uniform

PRI: 0.24 second and

constant

QRS: 0.08 second

Interp: Sinus Bradycardia

with First-Degree Heart

Block

9.238

Regularity: slightly irregular

Rate: atrial rate 94 bpm;

ventricular rate

approximately 60 bpm

P Waves: uniform;

regular P–P interval;

more P waves than

QRS complexes

PRI: P waves are not

associated with the

QRS complexes

QRS: 0.14 second

Interp: Third-Degree

Heart Block (CHB) with

a ventricular escape

focus (rate accelerated,

probably due to drugs)

9.239

Regularity: irregular

Rate: 30 bpm

P Waves: none

PRI: none

QRS: 0.16 second

Interp: Idioventricular

Rhythm

9.240

Regularity: regular

Rate: 107 bpm

P Waves: none discernible

PRI: none

QRS: 0.20 second

Interp: Slow Ventricular

Tachycardia

9.241

Regularity: regular

Rate: atrial rate 58 bpm

P Waves: upright and

uniform

PRI: none

QRS: none

Interp: Ventricular Standstill

9.242

580 Answers Key

Regularity: regular

Rate: 176 bpm

P Waves: upright and

uniform

PRI: 0.12 second

QRS: 0.08 second

Interp: Atrial Tachycardia

9.243

Regularity: slightly irregular underlying rhythm

interrupted by ectopics

in a pattern of grouped

beating

Rate: 42 bpm according

to visible P waves; true

sinus rate is probably

84 bpm

P Waves: uniform; regular

P–P interval

PRI: 0.18 second and

constant

QRS: 0.08 second in

underlying rhythm;

0.16 second in ectopics;

ectopics have bizarre

configuration and are

further distorted by nonconducted P waves,

making accurate

measurement difficult

Interp: Sinus Rhythm with

bigeminy of PVCs

9.244

Regularity: regular

Rate: atrial rate 66 bpm;

ventricular rate 33 bpm

P Waves: uniform; regular

P–P interval; consistently

two P waves for every

QRS complex

PRI: 0.28 second and

constant on conducted

beats

QRS: 0.10 second

Interp: Type II SecondDegree Heart Block with

2:1 conduction

9.245

Regularity: irregular

Rate: unable to determine

P Waves: none

PRI: none

QRS: 0.28 second

Interp: Idioventricular

Rhythm, Asystole

9.246

Regularity: very slightly

irregular underlying

rhythm interrupted by

two ectopics

Rate: 79 bpm (underlying

rhythm)

P Waves: uniform and

upright; regular

P–P interval except for

ectopics

PRI: 0.20 second and

constant

QRS: 0.08 second

Interp: Sinus Rhythm with

two PACs

9.247

Regularity: irregular

Rate: 110 bpm

P Waves: not discernible;

undulations present

PRI: none

QRS: 0.10 second

Interp: Atrial Fibrillation,

uncontrolled

9.248

Regularity: regular

Rate: atrial rate 352 bpm;

ventricular rate 88 bpm

P Waves: uniform;

sawtooth in appearance

PRI: none

QRS: 0.10 second

Interp: Atrial Flutter with

4:1 response

9.249

Regularity: regular

underlying rhythm

interrupted by ectopics

Rate: 58 bpm (underlying

rhythm)

P Waves: upright and

uniform

PRI: 0.12 second and

constant

QRS: 0.10 second

(underlying rhythm);

0.16 second (ectopics)

Interp: Sinus Bradycardia

with two unifocal PVCs

9.250

Chapter 10

Regularity: regular

Rate: atrial rate 300 bpm;

ventricular rate 75 bpm

P Waves: characteristic

sawtooth pattern

PRI: unable to determine

QRS: 0.10 second

Interp: Atrial Flutter with

4:1 response

10.1

Regularity: regular

Rate: 125 bpm

P Waves: upright and

constant

PRI: 0.12 second and

constant

QRS: 0.10 second

Interp: Sinus Tachycardia

10.2

Regularity: regular

Rate: 125 bpm

P Waves: upright and

constant

PRI: 0.24 second, constant

QRS: 0.08 second

Interp: Sinus Tachycardia

with First-Degree Heart

Block

10.3

Regularity: regular underlying rhythm interrupted

by a single ectopic

Rate: 75 bpm in underlying

rhythm

P Waves: upright in underlying rhythm; no P wave

in ectopic

PRI: 0.14 second and

constant

QRS: 0.08 second in

underlying rhythm;

0.14 second in ectopic

Interp: Sinus Rhythm with

one PVC

10.4

Regularity: regular

Rate: 188 bpm

P Waves: none visible

PRI: unable to determine

QRS: wide and bizarre

Interp: Ventricular

Tachycardia

10.5

Regularity: irregular

Rate: 90 bpm

P Waves: upright and

constant

PRI: 0.14 second

QRS: 0.08 second

Interp: Sinus Arrhythmia

10.6

Regularity: regular

Rate: 27 bpm

P Waves: none visible

PRI: unable to determine

QRS: 0.14 second

Interp: Idioventricular

Rhythm

10.7

Note: A couple of bumps look suspiciously like P waves,

but they don’t map out. The area of artifact in the baseline following the second QRS is probably caused by

patient movement.

Regularity: regular

Rate: 71 bpm

P Waves: upright; notched

appearance

PRI: 0.24 second and

constant

QRS: 0.08 second

Interp: Sinus Rhythm with

First-Degree Heart Block

10.8

Regularity: regular underlying rhythm interrupted

by a single ectopic

Rate: 107 bpm

P Waves: upright in front of

every QRS; the ectopic

probably also has a

P wave superimposed

on the preceding T wave

PRI: 0.20 second and constant in the underlying

rhythm; impossible to

measure in the ectopic

QRS: 0.10 second in both

the underlying rhythm

and ectopic

Interp: Sinus Tachycardia

with one PAC

10.9

Answers Key 581

Regularity: very regular

after the first beat or

two

Rate: 188 bpm

P Waves: none visible

PRI: unable to determine

QRS: 0.06 second

Interp: Because these findings are consistent with

several rhythms (Atrial

Tachycardia, Sinus Tachycardia, Atrial Fibrillation,

Atrial Flutter, Junctional

Tachycardia), it is legitimately labeled a Supraventricular Tachycardia.

10.10

Regularity: slightly irregular

Rate: 50 bpm

P Waves: inverted following every QRS

PRI: unable to determine

QRS: 0.08 second

Interp: Junctional Escape

Rhythm

10.11

Regularity: regular (first

sinus beat following

ectopic is slightly early)

Rate: 58 bpm

P Waves: upright and

constant in front of

every QRS except the

ectopic

PRI: 0.18 second and

constant

QRS: 0.06 second in underlying rhythm; 0.14 second in ectopic; ectopic

is wide and bizarre and

squeezed between two R

waves without disrupting

the underlying rhythm

Interp: Sinus Bradycardia

with one (interpolated)

PVC

10.12

Regularity: regular

Rate: 75 bpm

P Waves: upright and

constant

PRI: 0.16 second

QRS: 0.10 second

Interp: Normal Sinus

Rhythm

10.13

Regularity: irregular

Rate: ventricular rate

110 bpm; atrial rate

300 bpm

P Waves: sawtooth Flutter

waves

PRI: none

QRS: 0.12 second

Interp: Atrial Flutter with

rapid, variable ventricular

response (with wide QRS)

10.14

Regularity: regular underlying rhythm interrupted

by ectopics in a pattern

of grouped beating

Rate: 80 bpm including

ectopics

P Waves: upright P waves

in underlying rhythm; no

P waves in ectopics

PRI: 0.18 second in

underlying rhythm

QRS: 0.08 second in underlying rhythm; 0.12 second

in ectopics; ectopics have

wide, bizarre configuration

Interp: Sinus Rhythm with

bigeminy of unifocal

PVCs

10.15

Regularity: only undulations on baseline

Rate: unable to determine

P Waves: none visible

PRI: none

QRS: none visible

Interp: Ventricular

Fibrillation

10.16

Regularity: regular

Rate: 58 bpm

P Waves: upright in

front of every QRS

PRI: 0.24 second and

constant

QRS: 0.10 second

Interp: Sinus Bradycardia

with First-Degree Heart

Block

10.17

Regularity: irregular

Rate: 110 bpm

P Waves: none visible

PRI: none

QRS: 0.08 second

Interp: Atrial Fibrillation,

uncontrolled

10.18

Regularity: regular

Rate: 214 bpm

P Waves: none visible

PRI: none

QRS: 0.06 second

Interp: Supraventricular

Tachycardia

10.19

Note: If you argue that the tiny glitch following the

QRS is a P wave, then you would call this a Junctional

Tachycardia.

Regularity: regular (very

slightly irregular)

Rate: 48 bpm

P Waves: upright in front of

every QRS

PRI: 0.20 second and

constant

QRS: 0.10 second

Interp: Sinus Bradycardia

10.20

Regularity: slightly irregular

Rate: 90 bpm

P Waves: precede every

QRS, but morphology

changes and P–P

interval varies

PRI: varies from 0.12 to

0.20 second

QRS: 0.08 second

Interp: Wandering

Pacemaker

10.21

Regularity: regular underlying rhythm interrupted

by a single ectopic

Rate: 75 bpm

P Waves: upright preceding each QRS complex;

the ectopic is preceded

by an inverted P wave

PRI: 0.18 second in

underlying rhythm;

0.12 second in ectopic

QRS: 0.08 second in both

underlying rhythm and

ectopic

Interp: Sinus Rhythm with

one PJC

10.22

Regularity: regular atrial

rhythm; irregular

ventricular rhythm

Rate: atrial rate 65 bpm;

ventricular rate 50 bpm

P Waves: upright; more

P waves than QRS

complexes

PRI: gets progressively

longer until one P wave

is not conducted

QRS: 0.08 second

Interp: Wenckebach (Type I

Second-Degree Heart

Block)

10.23

Regularity: regular

Rate: 167 bpm

P Waves: none visible

PRI: none

QRS: wide and bizarre

Interp: Ventricular

Tachycardia

10.24

Regularity: irregular

Rate: 90 bpm

P Waves: none (only

undulations)

PRI: none

QRS: 0.08 second

Interp: Atrial Fibrillation,

controlled

10.25

Regularity: both atrial and

ventricular rhythms are

regular

Rate: atrial rate is 83 bpm;

ventricular rate 45 bpm

P Waves: upright across

strip; some P waves

superimposed on QRS

complexes

PRI: none

QRS: 0.10 second

Interp: Complete Heart

Block with junctional

escape focus

10.26

Regularity: rate is too slow

to determine regularity

Rate: 12 bpm

P Waves: upright and

clearly visible preceding

both QRS complexes

PRI: 0.20 second and

constant

QRS: 0.16 second

Interp: Sinus Bradycardia

(with wide QRS) Agonal

Rhythm

10.27

582 Answers Key

Note: This rate is insufficient to support perfusion and is

extremely slow for a sinus pacemaker. However,

P waves are clearly visible preceding both QRS

complexes, with consistent PRIs, indicating that the

rhythm did originate in the sinus node.

Regularity: regular (only

very slightly irregular)

Rate: 60 bpm

P Waves: upright

PRI: 0.24 second and

constant

QRS: 0.14 second

Interp: Sinus Rhythm with

First-Degree Heart Block

(with wide QRS)

10.28

Regularity: regular

Rate: atrial rate is

334 bpm; ventricular rate

is 167 bpm

P Waves: sawtooth Flutter

waves

PRI: none

QRS: 0.10 second

Interp: Atrial Flutter with

2:1 response

10.29

Regularity: regular

Rate: 83 bpm

P Waves: upright in front

of every QRS

PRI: 0.16 second and

constant

QRS: 0.10 second

Interp: Normal Sinus Rhythm

10.30

Regularity: regular

Rate: atrial rate is 60 bpm

P Waves: upright

PRI: none

QRS: none visible

Interp: Ventricular Standstill

10.31

Regularity: ventricular

rhythm is regular; atrial

rhythm is irregular

Rate: atrial rate 370 bpm;

ventricular rate 29 bpm

P Waves: sawtooth Flutter

waves

PRI: none

QRS: 0.10 second

Interp: Atrial Flutter with

variable response

10.32

Regularity: ventricular

rhythm is regular; atrial

rhythm is irregular

Rate: atrial rate 40 bpm;

ventricular rate 32 bpm

P Waves: upright

PRI: none

QRS: 0.12 second

Interp: Complete Heart

Block with ventricular

escape focus (atrial rate

is slowing)

10.33

Regularity: irregular underlying rhythm interrupted by

a burst of four ectopics

Rate: 90 bpm (excluding

ectopics)

P Waves: none; fibrillatory

undulations are present;

some Flutter waves are

visible but they can’t

be mapped across the

entire strip

PRI: none

QRS: 0.10 second in

underlying rhythm;

0.12 second in ectopics

Interp: Atrial Fibrillation,

controlled, with a run of

four PVCs (short burst of

Ventricular Tachycardia)

10.34

Regularity: no visible

waves or complexes

Rate: none

P Waves: none

PRI: none

QRS: none

Interp: Asystole (assuming that equipment is

functioning properly)

10.35

Regularity: regular

Rate: 167 bpm

P Waves: none

PRI: none

QRS: 0.16 second, wide

and bizarre

Interp: Ventricular

Tachycardia

10.36

Regularity: irregular ventricular rhythm; regular

atrial rhythm

Rate: atrial rate is 188 bpm;

ventricular rate is 50 bpm

P Waves: sawtooth Flutter

waves

PRI: none

QRS: 0.08 second

Interp: Atrial Flutter with

variable response

10.37

Regularity: slightly

irregular

Rate: 30 bpm

P Waves: upright in front

of every QRS

PRI: 0.18 second and

constant

QRS: 0.14 second

Interp: Sinus Bradycardia (with wide QRS)

with underlying Sinus

Arrhythmia (Sinus

Bradyarrhythmia)

10.38

Regularity: no visible

waves or complexes

Rate: none

P Waves: none

PRI: none

QRS: none

Interp: Asystole (Agonal

Rhythm)

10.39

Note: The undulations in the baseline don’t look like cardiac activity; they are more likely artifact such as CPR.

Regularity: regular

Rate: 115 bpm

P Waves: inverted

following each QRS

PRI: none

QRS: 0.10 second

Interp: Junctional

Tachycardia

10.40

Regularity: irregular underlying rhythm interrupted

by ectopics

Rate: 100 bpm including

ectopics

P Waves: none;

undulations are visible

PRI: none

QRS: 0.10 second in

underlying rhythm;

0.16 second in ectopics

Interp: Atrial Fibrillation,

controlled, with two

unifocal PVCs

10.41

Regularity: atrial rhythm

is regular; unable to

discern regularity of

ventricular rhythm

Rate: atrial rate is

60 bpm; only one ventricular complex visible

suggesting ventricular

rate of 10 or less

P Waves: upright; not

every P wave is followed

by a QRS complex

PRI: none

QRS: 0.12 second

Interp: Complete Heart

Block with ventricular

escape focus

(A–V dissociation)

10.42

Regularity: regular

Rate: 167 bpm

P Waves: upright

preceding each QRS

PRI: 0.12 second and

constant

QRS: 0.10 second

Interp: Atrial Tachycardia

10.43

Regularity: slightly

irregular (more regular

toward end of strip)

Rate: 150 bpm (measured

after initial two beats)

P Waves: none visible

PRI: none

QRS: wide and bizarre

Interp: Ventricular

Tachycardia

10.44

Regularity: regular

Rate: atrial rate is 61 bpm;

ventricular rate is 59

P Waves: upright; march

through QRS

PRI: none

QRS: 0.12 second

Interp: Third-Degree Heart

Block (CHB) with ventricular escape focus

10.45

Answers Key 583

Note: The nearly identical atrial and ventricular rates

make the pattern difficult to discern, especially on

a short strip. With this rate, it is likely that the focus

controlling the ventricles is junctional though the QRS

measurement is 0.12, which suggests that it is ventricular. (The QRS should be measured on complexes

that are not distorted by a P wave.) There are at least

two possible explanations: focus is ventricular but rate

is accelerated by drugs, or focus is junctional with an

underlying wide QRS complex.

Regularity: regular

Rate: atrial rate is

352 bpm; ventricular

rate is 88 bpm

P Waves: sawtooth Flutter

waves

PRI: none

QRS: 0.12 second

Interp: Atrial Flutter with

4:1 response (with wide

QRS)

10.46

Regularity: regular

Rate: 214 bpm

P Waves: none visible

PRI: not measurable

QRS: 0.08 second

Interp: Supraventricular

Tachycardia

10.47