Regularity: totally chaotic

baseline

Rate: cannot determine

P Waves: none

PRI: none

QRS: none

Interp: Ventricular

Fibrillation

9.15

Regularity: regular underlying rhythm interrupted

by ectopics

Rate: 100 bpm

P Waves: uniform P waves;

regular P–P interval

PRI: 0.22 second and

constant

QRS: 0.12 second in

underlying rhythm;

0.20 second in ectopics;

ectopics have bizarre

configuration

Interp: Sinus Rhythm (with

wide QRS) with FirstDegree Heart Block and

three unifocal PVCs

(possibly quadrigeminy)

9.16

Regularity: irregular

Rate: approximately

170 bpm

P Waves: not discernible;

undulations present

PRI: none

QRS: 0.08 second

Interp: Atrial Fibrillation,

uncontrolled

9.17

Regularity: regular underlying rhythm interrupted

by ectopics

Rate: 107 bpm

P Waves: uniform P waves

in underlying rhythm;

shape of P waves

changes in ectopic beats

PRI: 0.14 second

QRS: 0.08 second in both

underlying rhythm and

ectopics

Interp: Sinus Tachycardia

with two PACs

9.18

Regularity: regular underlying rhythm interrupted

by ectopics

Rate: 83 bpm

P Waves: uniform; regular

P–P interval

PRI: 0.20 second

QRS: 0.08 second in underlying beats; 0.16 second in ectopics

Interp: Sinus Rhythm with

three unifocal PVCs

(possibly trigeminy)

9.19

568 Answers Key

Regularity: regular

Rate: 68 bpm

P Waves: uniform; regular

P–P interval

PRI: 0.44 second and

constant

QRS: 0.12 second

Interp: Sinus Rhythm with

First-Degree Heart Block

(with wide QRS)

9.20

Regularity: regular underlying rhythm interrupted

by ectopics

Rate: 83 bpm

P Waves: uniform; regular

P–P interval

PRI: 0.12 second

QRS: 0.12 second in

underlying rhythm;

0.12 second in ectopics;

ectopics have bizarre

configuration

Interp: Sinus Rhythm (with

wide QRS) with two multifocal PVCs

9.21

Regularity: regular

Rate: atrial rate 96 bpm;

ventricular rate 48 bpm

P Waves: upright and uniform; regular P–P interval

PRI: 0.20 second

QRS: 0.16 second

Interp: Type II SecondDegree Heart Block (2:1)

9.22

Regularity: regular underlying rhythm interrupted

by ectopics in a pattern

of grouped beating

Rate: 56 bpm according

to visible P waves; true

sinus rate is probably

112 bpm

P Waves: uniform; regular

P–P interval

PRI: 0.12 second

QRS: 0.08 second in

underlying rhythm;

0.12 second in ectopics;

ectopics have bizarre

configuration

Interp: Sinus Rhythm with

bigeminy of PVCs

9.23

Regularity: irregular

Rate: approximately

50 bpm

P Waves: not discernible;

undulations present

PRI: none

QRS: 0.12 second

Interp: Atrial Fibrillation,

controlled (with wide

QRS)

9.24

Regularity: regular

Rate: 94 bpm

P Waves: uniform and upright; regular P–P interval

PRI: 0.20 second and

constant

QRS: 0.10 second

Interp: Normal Sinus

Rhythm

9.25

Regularity: irregular rhythm

interrupted by ectopics

Rate: approximately

60 bpm; if ectopics are

included, the rate is

90 bpm

P Waves: not discernible;

undulations present

PRI: none

QRS: 0.08 second in

underlying rhythm;

0.14 second in ectopics;

ectopics have bizarre

configuration

Interp: Atrial Fibrillation,

controlled, with three

unifocal PVCs

9.26

Regularity: regular underlying rhythm interrupted

by ectopics

Rate: 103 bpm

P Waves: uniform in underlying rhythm; shape

changes in ectopic beats

PRI: 0.16 second

QRS: 0.10 second in both

underlying rhythm and

ectopics; shape does

not change in ectopics

Interp: Sinus Tachycardia

with two PACs

9.27

Regularity: regular underlying rhythm interrupted

by ectopics in a pattern

of grouped beating

Rate: 54 bpm according

to visible P waves; true

sinus rate is probably

108 bpm

P Waves: uniform; regular

P–P interval

PRI: 0.16 second and

constant

QRS: 0.12 second in both

underlying rhythm and

ectopics; ectopics have

bizarre configuration

Interp: Sinus Tachycardia

(with a wide QRS) with

bigeminy of PVCs

9.28

Regularity: regular

Rate: 79 bpm

P Waves: upright and uniform; regular P–P interval

PRI: 0.20 second and

constant

QRS: 0.08 second

Interp: Normal Sinus

Rhythm

9.29

Regularity: irregular underlying rhythm interrupted

by ectopics

Rate: approximately

70 bpm; if ectopics are

included rate is 110 bpm

P Waves: not discernible;

undulations present

PRI: none

QRS: 0.12 second in

underlying rhythm;

0.14 second in ectopics;

ectopics have bizarre

configurations

Interp: Atrial Fibrillation

(with wide QRS) with

multifocal PVCs and one

PVC couplet

9.30

Regularity: irregular

Rate: approximately

60 bpm

P Waves: not discernible;

undulations present

PRI: none

QRS: 0.08 second

Interp: Atrial Fibrillation,

controlled

9.31

Regularity: irregular

Rate: atrial rate 300 bpm;

ventricular rate 80 bpm

P Waves: uniform, sawtooth

appearance; regular P–P

interval; more P waves

than QRS complexes

PRI: none

QRS: 0.08 second

Interp: Atrial Flutter with

variable block

9.32

Regularity: irregular

Rate: atrial rate 94 bpm;

ventricular rate 60 bpm

P Waves: uniform; regular

P–P interval; occasional

non-conducted P waves

PRI: changing; progressively lengthens

from 0.20 second to

0.26 second

QRS: 0.08 second

Interp: Wenckebach (Type

I Second-Degree Heart

Block)

9.33

Regularity: regular

Rate: 136 bpm

P Waves: uniform and upright; regular P–P interval

PRI: 0.12 second and

constant

QRS: 0.06 second

Interp: Sinus Tachycardia

9.34

Regularity: regular

Rate: 83 bpm

P Waves: uniform and upright; regular P–P interval

PRI: 0.28 second and

constant

QRS: 0.08 second

Interp: Sinus Rhythm with

First-Degree Heart Block

9.35

Regularity: regular

Rate: 136 bpm

P Waves: uniform; regular

P–P interval

PRI: 0.14 second (partially

obscured by T wave)

QRS: 0.10 second

Interp: Sinus Tachycardia

9.36

Answers Key 569

Regularity: regular underlying rhythm interrupted

by ectopics

Rate: atrial rate 284 bpm;

ventricular rate 71 bpm

P Waves: uniform; sawtooth appearance;

regular P–P interval; consistently four P waves for

every QRS complex

PRI: none

QRS: 0.10 second in

underlying rhythm;

0.16 second in ectopics;

ectopics have bizarre

configuration

Interp: Atrial Flutter with

4:1 response and two

unifocal PVCs

9.37

Regularity: regular underlying rhythm interrupted

by ectopics

Rate: 100 bpm

P Waves: uniform; regular

P–P interval

PRI: 0.20 second and

constant

QRS: 0.12 second in

underlying rhythm and in

ectopics; ectopics have

bizarre configuration

Interp: Sinus Tachycardia

(with a wide QRS) with

two unifocal PVCs

9.38

Regularity: regular

Rate: 71 bpm

P Waves: uniform; regular

P–P interval

PRI: 0.14 second and

constant

QRS: 0.10 second

Interp: Normal Sinus

Rhythm

9.39

Regularity: regular

Rate: 300 bpm

P Waves: not visible

PRI: none

QRS: 0.16 second; bizarre

configuration

Interp: Ventricular Tachycardia (Ventricular Flutter)

9.40

Regularity: irregular

Rate: approximately

70 bpm

P Waves: not discernible

PRI: none

QRS: 0.08 second

Interp: Atrial Fibrillation,

controlled

9.41

Regularity: regular underlying rhythm interrupted

by ectopic (rate changes

following ectopic)

Rate: approximately 80 bpm

P Waves: uniform in underlying rhythm; configuration

changes in ectopic beat

PRI: 0.16 second

QRS: 0.12 second

Interp: Sinus Rhythm (with

wide QRS) with one PAC

9.42

Regularity: regular

Rate: 107 bpm

P Waves: uniform; regular

P–P interval

PRI: 0.14 second

QRS: 0.16 second

Interp: Sinus Tachycardia

(with wide QRS)

9.43

Regularity: irregular

Rate: approximately

11 bpm

P Waves: not discernible;

undulations present

PRI: none

QRS: 0.06 second

Interp: Atrial Fibrillation,

uncontrolled

9.44

Regularity: regular underlying rhythm interrupted

by ectopics

Rate: 88 bpm

P Waves: uniform; regular

P–P interval

PRI: 0.20 second

QRS: 0.10 second in

underlying rhythm;

0.14 second in ectopic;

ectopic has bizarre

configuration

Interp: Sinus Rhythm with

one PVC

9.45

Regularity: regular

Rate: 125 bpm

P Waves: uniform; regular

P–P interval

PRI: 0.16 second

QRS: 0.10 second

Interp: Sinus Tachycardia

9.46

Regularity: irregular

Rate: approximately

70 bpm

P Waves: not discernible;

undulations present

PRI: none

QRS: 0.10 second

Interp: Atrial Fibrillation,

controlled

9.47

Regularity: regular

Rate: 52 bpm

P Waves: uniform; regular

P–P interval

PRI: 0.20 second and

constant

QRS: 0.08 second

Interp: Sinus Bradycardia

9.48

Regularity: irregular

Rate: atrial rate 375 bpm;

ventricular rate approximately 100 bpm

P Waves: uniform; sawtooth appearance;

regular P–P interval;

more P waves than QRS

complexes

PRI: none

QRS: 0.08 second; complexes partially obscured

by Flutter waves

Interp: Atrial Flutter with

variable response

9.49

Regularity: regular

Rate: 115 bpm

P Waves: none visible

PRI: none

QRS: 0.08 second

Interp: Junctional

Tachycardia

9.50

Regularity: regular

Rate: 107 bpm

P Waves: uniform; regular

P–P interval

PRI: 0.12 second and

constant

QRS: 0.12 second

Interp: Sinus Tachycardia

(with wide QRS)

9.51

Regularity: irregular

Rate: atrial rate 300 bpm;

ventricular rate 80 bpm

P Waves: uniform; sawtooth appearance;

regular P–P interval;

more P waves than QRS

complexes

PRI: none

QRS: 0.08 second (complexes partially obscured

by Flutter waves)

Interp: Atrial Flutter with

variable response

9.52

Regularity: regular underlying rhythm interrupted

by ectopics

Rate: 103 bpm (underlying

rhythm)

P Waves: uniform; regular

P–P interval

PRI: 0.14 second

QRS: 0.06 second in

underlying rhythm;

0.12 second in ectopics;

ectopics have bizarre

configuration

Interp: Sinus Tachycardia

with trigeminy of PVCs

9.53

Regularity: irregular

Rate: approximately

80 bpm

P Waves: not discernible;

undulations present

PRI: none

QRS: 0.08 second

Interp: Atrial Fibrillation,

controlled

9.54

Regularity: regular

Rate: 167 bpm

P Waves: not visible

PRI: none

QRS: 0.20 second; bizarre

configuration

Interp: Ventricular

Tachycardia

9.55

570 Answers Key

Regularity: irregular

Rate: atrial rate 300 bpm;

ventricular rate approximately 140 bpm

P Waves: uniform; sawtooth configuration;

regular P–P interval;

more P waves than QRS

complexes

PRI: none

QRS: 0.08 second (complexes partially obscured

by Flutter waves)

Interp: Atrial Flutter with

variable response

9.56

Regularity: totally chaotic

baseline

Rate: unable to determine

P Waves: none

PRI: none

QRS: none

Interp: Ventricular

Fibrillation

9.57

Regularity: irregular

Rate: approximately

110 bpm

P Waves: not discernible;

undulations present

PRI: none

QRS: 0.08 second

Interp: Atrial Fibrillation,

uncontrolled

9.58

Regularity: regular

Rate: 107 bpm

P Waves: uniform; regular

P–P interval

PRI: 0.20 second

QRS: 0.12 second

Interp: Sinus Tachycardia

(with wide QRS)

9.59

Regularity: irregular rhythm

is interrupted by an

ectopic

Rate: approximately

70 bpm

P Waves: uniform; irregular

P–P interval; shape of P

wave changes in ectopic

beat

PRI: 0.14 second

QRS: 0.12 second in both

underlying beat and

ectopic; shape of complexes consistent

Interp: Sinus Arrhythmia

(with wide QRS) with one

PAC

9.60

Regularity: irregular

Rate: approximately

170 bpm

P Waves: not discernible

PRI: none

QRS: 0.10 second

Interp: Atrial Fibrillation,

uncontrolled

9.61

Regularity: regular underlying rhythm interrupted

by ectopics

Rate: 75 bpm

P Waves: uniform in underlying rhythm; regular P–P

interval

PRI: 0.20 second

QRS: 0.14 second in underlying complexes;

0.16 second in ectopics;

ectopics differ in configuration from underlying

complexes

Interp: Sinus Rhythm (with

wide QRS) with two unifocal PVCs

9.62

Regularity: irregular

Rate: approximately

130 bpm

P Waves: not discernible;

undulations present

PRI: none

QRS: 0.10 second

Interp: Atrial Fibrillation,

uncontrolled

9.63

Regularity: regular

Rate: atrial rate 300 bpm;

ventricular rate 75 bpm

P Waves: uniform; sawtooth appearance;

regular P–P interval; consistently four P waves for

every QRS complex

PRI: none

QRS: 0.08 second

Interp: Atrial Flutter with

4:1 response

9.64

Regularity: regular

Rate: 71 bpm

P Waves: uniform; regular

P–P interval

PRI: 0.24 second and

constant

QRS: 0.10 second

Interp: Sinus Rhythm with

First-Degree Heart Block

9.65

Regularity: regular

Rate: 111 bpm

P Waves: uniform; regular

P–P interval

PRI: 0.12 second

QRS: 0.08 second

Interp: Sinus Tachycardia

9.66

Regularity: irregular

Rate: approximately

90 bpm

P Waves: not discernible;

undulations present

PRI: none

QRS: 0.08 second

Interp: Atrial Fibrillation,

controlled

9.67

Regularity: irregular

Rate: approximately

70 bpm

P Waves: uniform; irregular

P–P interval

PRI: 0.12 second

QRS: 0.08 second

Interp: Sinus Arrhythmia

9.68

Regularity: irregular underlying rhythm interrupted

by ectopics

Rate: approximately

90 bpm

P Waves: not discernible;

undulations present

PRI: none

QRS: 0.12 second in

underlying complexes;

0.14 second in ectopics;

ectopics have bizarre

configuration

Interp: Atrial Fibrillation,

controlled (with wide

QRS) with runs of PVCs

9.69

Regularity: totally chaotic

baseline

Rate: cannot be

determined

P Waves: none

PRI: none

QRS: none

Interp: Ventricular

Fibrillation

9.70

Regularity: regular underlying rhythm interrupted

by ectopic

Rate: 88 bpm

P Waves: uniform in underlying rhythm; regular P–P

interval; shape changes

in ectopic beats

PRI: 0.16 second

QRS: 0.14 second

Interp: Sinus Rhythm

(with wide QRS) with

one PAC

9.71

Regularity: regular

Rate: 91 bpm

P Waves: uniform; regular

P–P interval

PRI: 0.28 second and

constant

QRS: 0.08 second

Interp: Sinus Rhythm with

First-Degree Heart Block

9.72

Regularity: regular

Rate: 150 bpm

P Waves: not discernible

PRI: none

QRS: 0.08 second

Interp: Supraventricular

Tachycardia

9.73

Regularity: totally chaotic

baseline

Rate: cannot be

determined

P Waves: none

PRI: none

QRS: none

Interp: Ventricular

Fibrillation

9.74

Answers Key 571

Regularity: irregular

Rate: approximately

110 bpm

P Waves: not discernible;

undulations present

PRI: none

QRS: 0.12 second

Interp: Atrial Fibrillation,

uncontrolled (with wide

QRS)

9.75

Regularity: regular

Rate: 56 bpm

P Waves: not visible

PRI: none

QRS: 0.16 second; configuration is bizarre

Interp: Accelerated Idioventricular Rhythm

9.76

Note: This rhythm fits all of the rules for Idioventricular

Rhythm except that the rate is faster than you would

expect it to be, but not as fast as you would think a

Ventricular Tachycardia would be. This patient may have

been in an Idioventricular Rhythm at a slower rate and

then received a drug to make the rate increase and improve his or her condition.

Regularity: regular

Rate: atrial rate 260 bpm;

ventricular rate 65 bpm

P Waves: uniform; sawtooth appearance;

regular P–P interval; consistently four P waves for

every QRS complex

PRI: none

QRS: 0.10 second

Interp: Atrial Flutter with

4:1 block

9.77

Regularity: irregular underlying rhythm interrupted

by ectopic

Rate: approximately

60 bpm

P Waves: not discernible;

undulations present

PRI: none

QRS: 0.10 second in

underlying rhythm;

0.14 second in ectopic;

ectopic has bizarre

configuration

Interp: Atrial Fibrillation,

controlled, with one PVC

9.78

Regularity: regular underlying rhythm interrupted

by ectopic

Rate: 81 bpm

P Waves: uniform; regular

P–P interval

PRI: 0.14 second

QRS: 0.12 second in

underlying rhythm;

0.14 second in ectopic;

ectopic has bizarre

configuration

Interp: Sinus Rhythm with

one PVC

9.79

Regularity: irregular

Rate: atrial rate 300 bpm;

ventricular rate approximately 80 bpm

P Waves: uniform; sawtooth appearance;

regular P–P interval;

more P waves than QRS

complexes

PRI: none

QRS: 0.10 second

Interp: Atrial Flutter with

variable block

9.80

Regularity: totally chaotic

baseline

Rate: cannot be

determined

P Waves: none

PRI: none

QRS: none

Interp: Ventricular

Fibrillation

9.81

Regularity: irregular

Rate: atrial rate 56 bpm;

ventricular rate 50 bpm

P Waves: uniform; regular

P–P interval; occasional

non-conducted P waves

PRI: changing PRI; progressively lengthens

from 0.28 second to

0.40 second

QRS: 0.08 second

Interp: Wenckebach

(Type I Second-Degree

Heart Block)

9.82

Regularity: irregular rhythm

interrupted by ectopics

Rate: approximately 60

bpm (underlying rhythm)

P Waves: uniform; irregular

P–P interval

PRI: 0.20 second

QRS: 0.08 second in

underlying rhythm;

0.16 second in ectopics;

ectopics have bizarre

configuration; ectopics

have different shapes

Interp: Sinus Arrhythmia

with multifocal PVCs

9.83

Regularity: regular

Rate: atrial rate 65 bpm;

ventricular rate 29 bpm

P Waves: uniform; regular P–P interval; more

P waves than QRS

complexes

PRI: P waves are not associated with QRS

complexes

QRS: 0.20 second; bizarre

configuration

Interp: Third-Degree Heart

Block (CHB) with ventricular escape focus

9.83

Regularity: irregular

Rate: approximately

90 bpm

P Waves: not discernible;

undulations present

PRI: none

QRS: 0.14 second

Interp: Atrial Fibrillation,

controlled (with wide

QRS)

9.85

Regularity: irregular

Rate: approximately

120 bpm

P Waves: not discernible;

undulations present

PRI: none

QRS: 0.10 second

Interp: Atrial Fibrillation,

uncontrolled

9.86

Regularity: regular

Rate: 75 bpm

P Waves: uniform and upright; regular P–P interval

PRI: 0.16 second and

constant

QRS: 0.06 second

Interp: Normal Sinus

Rhythm

9.87

Regularity: regular underlying rhythm interrupted

by ectopics

Rate: 88 bpm

P Waves: uniform in underlying rhythm; form

changes in ectopics

PRI: 0.12 second

QRS: 0.10 second in both

underlying rhythm and

ectopics; form does not

change in ectopics

Interp: Sinus Rhythm with

three PACs

9.88

Regularity: regular

Rate: 214 bpm

P Waves: not visible

PRI: none

QRS: 0.06 second

Interp: Supraventricular

Tachycardia—probably

Atrial Tachycardia (see

note)

9.89

Note: Of all the supraventricular tachycardias, Atrial

Tachycardia is the only one that can produce this ventricular rate with 1:1 conduction.

572 Answers Key

Regularity: regular

Rate: atrial rate 100 bpm;

ventricular rate 44 bpm

P Waves: uniform; regular P–P interval; more

P waves than QRS

complexes

PRI: P waves are not associated with QRS

complexes

QRS: 0.08 second

Interp: Third-Degree Heart

Block (CHB) with junctional escape focus

9.90

Regularity: regular, interrupted by ectopic

Rate: 83 bpm

P Waves: uniform; regular

P–P interval

PRI: 0.24 second and

constant in underlying

rhythm; 0.12 second in

ectopic

QRS: 0.14 second in

underlying rhythm;

0.14 second in ectopic

Interp: Sinus Rhythm (with

wide QRS) with FirstDegree Heart Block and

one PJC

9.91

Regularity: regular

Rate: 188 bpm

P Waves: none visible

PRI: not discernible

QRS: 0.10 second

Interp: Supraventricular

Tachycardia

9.92

Regularity: slightly irregular

Rate: atrial rate 88 bpm;

ventricular rate approximately 33 bpm

P Waves: uniform; regular

P–P interval; more P

waves than QRS

complexes

PRI: none

QRS: 0.12 second

Interp: Third-Degree Heart

Block (CHB) with ventricular escape focus

9.93

Regularity: totally chaotic

baseline

Rate: unable to determine

P Waves: none visible

PRI: unable to determine

QRS: none visible

Interp: Ventricular Fibrillation (Agonal Rhythm)

9.94

Regularity: regular

Rate: 50 bpm

P Waves: uniform; regular

P–P interval

PRI: 0.16 second and

constant

QRS: 0.14 second

Interp: Sinus Bradycardia

(with wide QRS)

9.95

Regularity: slightly irregular

underlying rhythm interrupted by ectopics

Rate: approximately 107

bpm (underlying rhythm)

P Waves: not discernible

(see note); ectopics not

preceded by P waves

PRI: none

QRS: 0.08 second in

underlying rhythm;

0.12 second and

0.16 second in ectopics

Interp: Atrial Fibrillation,

uncontrolled, with two

multifocal PVCs

9.96

Note: Small waves precede some QRS complexes but

by too short a distance to have been conducted; furthermore, these waves do not map out across the strip.

Regularity: slightly irregular

Rate: approximately

37 bpm

P Waves: uniform; regular

P–P interval

PRI: 0.20 second and

constant

QRS: 0.08 second

Interp: Sinus Bradycardia (with slight sinus

arrhythmia)

9.97

Regularity: regular

Rate: 125 bpm

P Waves: uniform; regular

P–P interval

PRI: 0.16 second and constant (obscured slightly

by T waves)

QRS: 0.08 second

Interp: Sinus Tachycardia

9.98

Regularity: slightly irregular

Rate: approximately

110 bpm

P Waves: shape changes

from beat to beat

PRI: approximately 0.16

second; varies slightly

QRS: 0.12 second

Interp: Wandering Pacemaker (with a wide QRS)

9.99

Regularity: slightly irregular

Rate: approximately

170 bpm

P Waves: none visible

PRI: none

QRS: 0.24 second

Interp: Ventricular

Tachycardia

9.100

Regularity: irregular

Rate: approximately

130 bpm

P Waves: none visible, undulations present

PRI: none

QRS: 0.06 second

Interp: Atrial Fibrillation,

uncontrolled

9.101

Regularity: totally chaotic

baseline

Rate: not discernible

P Waves: none visible

PRI: none

QRS: none visible

Interp: Ventricular

Fibrillation

9.102

Regularity: regular underlying rhythm interrupted

by ectopics in a pattern

of grouped beating

Rate: 68 bpm

P Waves: uniform; regular

P–P interval in underlying rhythm; no P waves

preceding ectopics

PRI: 0.16 second and

constant

QRS: 0.08 second in

underlying rhythm;

0.14 second in ectopics

Interp: Sinus Rhythm with

bigeminy of PVCs

9.103

Regularity: regular underlying rhythm interrupted

by ectopics

Rate: 100 bpm

P Waves: uniform; regular

P–P interval; no P waves

preceding ectopics

PRI: 0.14 second and

constant

QRS: 0.12 second

Interp: Sinus Tachycardia

(with a wide QRS) and

two PJCs

9.104

Regularity: regular (very

slightly irregular)

Rate: approximately

70 bpm

P Waves: uniform; regular

P–P interval

PRI: 0.30 second and

constant

QRS: 0.08 second

Interp: Sinus Rhythm with

First-Degree Heart Block

9.105

Regularity: totally chaotic

baseline

Rate: unable to determine

P Waves: none visible

PRI: none

QRS: none visible

Interp: Ventricular

Fibrillation

9.106

Regularity: slight irregular

underlying rhythm interrupted by ectopic

Rate: approximately

50 bpm

P Waves: uniform and

upright

PRI: 0.08 second and

constant

QRS: 0.08 second in

underlying rhythm;

0.20 second in ectopic

Interp: Sinus Bradycardia

with one PVC

9.107

Answers Key 573

Regularity: irregular

Rate: atrial rate 214 bpm;

ventricular rate approximately 100 bpm

P Waves: characteristic

sawtooth pattern

PRI: unable to determine

QRS: 0.10 second

Interp: Atrial Flutter with

variable response

9.108

Regularity: regular

Rate: 75 bpm

P Waves: uniform; regular

P–P interval

PRI: 0.24 second and

constant

QRS: 0.08 second

Interp: Sinus Rhythm with

First-Degree Heart Block

9.109

Regularity: slightly irregular

Rate: approximately

150 bpm

P Waves: none visible

PRI: none

QRS: 0.12 second

Interp: Ventricular

Tachycardia

9.110

Regularity: irregular

Rate: approximately

70 bpm

P Waves: none visible; undulations present

PRI: none

QRS: 0.14 second

Interp: Atrial Fibrillation,

controlled (with wide

QRS)

9.111

Regularity: regular (very

slightly irregular)

Rate: approximately

46 bpm

P Waves: inverted following QRS complex

PRI: none

QRS: 0.08 second

Interp: Junctional Escape

Rhythm

9.112

Regularity: irregular

Rate: approximately

150 bpm initially; then 0

P Waves: none

PRI: none

QRS: approximately

0.20 second

Interp: Ventricular Tachycardia into Asystole

9.113

Regularity: irregular underlying rhythm with a pattern of grouped beating

Rate: atrial rate 125 bpm;

ventricular rate approximately 80 bpm

P Waves: uniform; regular

P–P interval

PRI: varies; progressively

lengthens until one P

wave is not conducted

QRS: 0.12 second

Interp: Wenckebach (Type

I Second-Degree Heart

Block)

9.114

Regularity: slightly irregular

Rate: approximately

150 bpm

P Waves: none visible

PRI: none

QRS: approximately

0.24 second

Interp: Ventricular

Tachycardia

9.115

Regularity: regular underlying rhythm interrupted

by ectopic

Rate: 63 bpm

P Waves: uniform; regular

P–P interval

PRI: 0.20 second and

constant

QRS: 0.08 second in

underlying rhythm;

0.14 second in ectopic

Interp: Sinus Rhythm with

one PVC

9.116

Regularity: regular underlying rhythm interrupted

by ectopics in a pattern

of grouped beating

Rate: 79 bpm

P Waves: uniform; regular

P–P interval; no P waves

preceding ectopics

PRI: 0.22 second and

constant

QRS: 0.10 second in

underlying rhythm;

0.16 second in ectopics

Interp: Sinus Rhythm with

First-Degree Heart Block

with trigeminy of PVCs

9.117

Regularity: regular

Rate: 150 bpm

P Waves: none visible

PRI: none

QRS: 0.14 second

Interp: Ventricular

Tachycardia

9.118

Regularity: regular, interrupted by ectopics

Rate: 79 bpm

P Waves: uniform; regular

P–P interval

PRI: 0.20 second and

constant

QRS: 0.08 second in

underlying rhythm;

0.12 second in ectopics

Interp: Sinus Rhythm with

two unifocal PVCs

9.119

Regularity: slightly irregular

Rate: approximately

107 bpm

P Waves: none visible

PRI: none

QRS: 0.22 second

Interp: slow Ventricular

Tachycardia

9.120

Regularity: regular underlying rhythm interrupted

by ectopic

Rate: 83 bpm

P Waves: uniform; regular

P–P interval; no P wave

preceding ectopic

PRI: 0.14 second and

constant

QRS: 0.08 second in

underlying rhythm;

0.16 second in ectopic

Interp: Normal Sinus

Rhythm with one PVC

9.121

Regularity: regular underlying rhythm interrupted

by ectopic

Rate: 77 bpm

P Waves: uniform; regular

P–P interval; no P wave

preceding ectopic

PRI: 0.26 second and

constant

QRS: 0.08 second in

underlying rhythm;

0.12 second in ectopic

Interp: Sinus Rhythm with

First-Degree Heart Block

and one PVC

9.122

Regularity: regular

Rate: atrial rate 94 bpm;

ventricular rate 47 bpm

P Waves: uniform; regular

P–P interval; three P

waves for every QRS

complex

PRI: 0.28 second and

constant on conducted

beats

QRS: 0.12 second

Interp: Type II SecondDegree Heart Block with

2:1 conduction (with

wide QRS)

9.123

Regularity: totally chaotic

baseline

Rate: unable to determine

P Waves: none visible

PRI: none

QRS: none visible

Interp: Ventricular Fibrillation into Asystole

9.124

Regularity: regular underlying rhythm interrupted

by ectopic

Rate: 88 bpm

P Waves: uniform; regular

P–P interval; ectopic is

preceded by upright

P wave

PRI: 0.20 second and

constant

QRS: 0.08 second

Interp: Normal Sinus

Rhythm with one PAC

9.125

574 Answers Key

Regularity: totally chaotic

baseline

Rate: unable to determine

P Waves: none visible

PRI: none

QRS: none visible

Interp: Ventricular

Fibrillation

9.126

Regularity: regular

Rate: atrial rate 300 bpm;

ventricular rate 60 bpm

P Waves: characteristic

sawtooth pattern

PRI: unable to determine

QRS: 0.08 second (slightly

obscured by Flutter

waves)

Interp: Atrial Flutter with

5:1 response

9.127

Regularity: irregular

Rate: approximately

110 bpm

P Waves: configuration

varies from beat to beat

PRI: varies

QRS: 0.08 second

Interp: Wandering

Pacemaker

9.128

Regularity: slightly irregular

Rate: approximately

48 bpm

P Waves: uniform; regular

P–P interval

PRI: 0.16 second and

constant

QRS: 0.10 second

Interp: Sinus

Bradyarrhythmia

9.129