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CV- principles > Pacemakers > Flashcards

Pacemakers Flashcards

1
Q

a pacemaker consists of a ___ generator and pacing ___ that deliver electrical current to the heart

A

Pulse generator and pacing leads

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2
Q

Position 1 pacemaker

A

chamber paced

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3
Q

position 2 pacemaker

A

chamber sensed

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4
Q

position 3 pacemaker

A

response to sensed native cardiac activity

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5
Q

position 4 pacemaker

A

programability options

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6
Q

position 5 pacemaker

A

indicates the pacemaker can pace multiple sites

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7
Q

circuit board (“hybrid”)

A

The pulse generator processes electrical info from the heart, and it responds to these signals based on the programmed settings

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8
Q

Where is the atrial lead positioned?

A

lodges in the right atrial appendage

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9
Q

Where is the ventricular lead positioned?

A

lodges in the apex of the right ventricle

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10
Q

What are the indications for pacemaker insertion?

A

SA node disease
AV node disease
Long QT syndrome
Dilated cardiomyopathy
Hypertrophic obstructive cardiomyopathy

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11
Q

What is the mnemonic that can be memorized to remember the 5 letter code of pacemakers?

A

PaSeR

Pa= chamber PAced

Se= chamber SEnsed

R= Response

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12
Q

pacemaker position 1 codes

A

O= none
A= atrium
V= ventricle
D= dual (A+V)

Chamber that is paced

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13
Q

pacemaker position 2 codes

A

O= none
A= Atrium
V= ventricle
D= dual (A+V)

chamber that is sensed

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14
Q

pacemaker position 3 codes

A

O= none

T= triggered (sensed activity tells the pacemaker TO fire

I= inhibited (sensed activity tells the pacemaker NOT to fire)

D= dual (T+I) (if native activity is sensed, then pacing is inhibited, if native activity is not sensed, then the pacemaker fires)

  • Example: a sensed intrinsic atrial beat will inhibit atrial pacing output and will trigger ventricular pacing
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15
Q

pacemaker position 4 codes

A

O= none
R= rate modulation

This indicates the programmability of the pacemaker. This describes the ability to adjust heart rate in response to physiologic needs. Sensors can measure respiration, acid-base status vibration ect.

(will increase the pacer’s lower heart rate limit in response to activity that may require an increased myocardial oxygen demand)

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16
Q

pacemaker position 5 codes

A

O= none
A= atrium
V= ventricle
D= dual (A+V)

This indicates that the pacemaker can pace multiple sites

(pacer may pace BOTH atria and/or BOTH ventricles)

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17
Q

What will you see ok the EKG with atrial pacing?

A

A pacing spike preceded the P wave, QRS is normal

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18
Q

What will you see ok the EKG with ventricular pacing?

A

A pacing spike precedes the QRS complex. The QRS is wide

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19
Q

What will you see on the EKG with atrial + ventricular pacing?

A

There’s a pacing spike that stimulates the atria and another that stimulates the ventricles.

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20
Q

Examples of Asynchronous pacing

A

AOO
VOO
DOO

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21
Q

examples of single-chamber demand pacing

A

AAI
VVI

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22
Q

examples of dual-chamber AV sequential demand pacing

A

DDD

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23
Q

What does the pacer do in asynchronous pacing?

A

The pacemaker delivers a constant rate

There is no sense or inhibition

There can be a competitive underlying rhythm

A pacer spike delivered during ventricular Repolarization can result on R on T

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24
Q

What does the pacer do in Single-chamber demand pacing?

A

Think of this as a backup mode- it only fires when the native heart rate falls below a predetermined rate

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25
Q

What does the pacer do in a dual chamber AV sequential demand pacing?

A

The most flexible and most common

Makes sure the atrium contracts first, followed by the ventricle

This improves AV synchrony

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26
Q

Failure to capture:

A

when the pacemaker’s electrical output fails to cause myocardial depolarization

On the EKG you’ll see pacing spikes but they aren’t followed by a QRS complex (ventricular depolarization)

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27
Q

Failure to sense:

A

the pacemaker fails to recognize intrinsic cardiac electrical activity

Pacing spikes where they shouldn’t be

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28
Q

Indications for ICD

A

Ventricular tachycardia

Ventricular fibrillation

Post MI with an EF <30%

Cardiomyopathy with an EF <35%

Hypertrophic
cardiomyopathy

Awaiting a heart transplant
Long QT syndrome

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29
Q

A patient undergoing bunionectomy has a VOO pacemaker with a rate of 80 bpm. During the procedure, there is failure to capture and the heart rate decreases to 50 bpm. Which of the following best explains why this complication occurred

A.) the EtCO2 was 20 mmHg

B.) an ultrasonic harmonic scalpel was used

C.) the patient was hyperthermic

D.) the electrocautery setting was changed from coagulation to cutting

A

A.) the EtCO2 was 20 mmHg

The pacemaker failed to capture bc hypocarbia (which caused hypokalemia) made the myocardium more resistant to depolarization. The same electrical stimulus from the pacemaker was no longer sufficient to depolarize the heart. You’ll see pacer spikes but will not see capture.

can try fixing it by turning up the mV on the pacer

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30
Q

What does placing a magnet over a pacemaker do?

A

(Usually) converts the pacemaker to asynchronous mode

“magnet rate” is typically 85-100 bpm

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31
Q

What does placing a magnet over a ICD do?

A

Suspends the ICD and prevents shock delivered

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32
Q

What does placing a magnet over a pacemaker + ICD do?

A

Suspends the ICD and prevents shock delivery. It has no effects on the pacemaker function.

Pacemaker function will be subject to EMI. If EMI is likely, then the pacemaker should be reprogrammed by the manufacturer before the surgical procedure

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33
Q

What conditions can impair pacemaker performance?

A

EMI (electromagnetic interference)

conditions that make the myocardium more resistant to depolarization:

hyper/hypokalemia

Hypocapnia

hypothermia

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34
Q

If surgical electrocautery is used, the best option for the surgeon to use a ______ device

A

bipolar device

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35
Q

T/F: MRI is typically contraindicated for a pt with a pacemaker or ICD

A

TRUE (some newer devices may be compatible)

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36
Q

The most critical information to have preoperatively about a pt with a pacemaker:

A

The pt’s underlying rhythm - so you know how to prepare for device failure

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37
Q

How is pacemaker failure treated?

A

Isoproterenol

Epinephrine

Atropine

(all depending on underlying rhythm)

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38
Q

When does failure to sense (undersensing) happen?

A

When the pacemaker does not sense the underlying (native cardiac rhythm)

you will see pacing spikes in areas you would not expect to see them

can cause R on T if pacer fires during ventricular repolarization

V.fib can happen with ventricular spike lands on T wave

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39
Q

Causes of failure to capture:

A

electrode displacement

Wire fracture

Conditions that make the myocardium more resistant to depolarization:

-hyper/hyperkalemia
-hypocapnia (intracellular K+ shift)
-Hypothermia
-myocardial infarction
-Fibrotic tissue buildup around the pacing leads
-antiarrhythmic medications

40
Q

Failure to output

A

Occurs when a pacing stimulus is not produced in a situation when it should be.

can be caused by oversensing, pulse generator failure or lead failure

41
Q

What can cause failure to output?

A

oversensing

pulse generation failure

lead failure

42
Q

When is the risk of EMI greatest?

A

use of electrocautery and radio frequency ablation

43
Q

Does the coagulation or cutting setting on electrocautery cause more EMI?

A

Coagulation setting causes more

use cutting

44
Q

What causes more EMI?

A.) monopolar

B.) Bipolar

C.) ultrasonic harmonic scalpel

A

Monopolar causes more

45
Q

If the surgeon insists on monopolar cautery, then you insist that they use short bursts

A

<0.5 seconds

46
Q

The risk of EMI is highest when the electrocautery tip is used within:

A

a 15 cm radius of the pulse generator

47
Q

Place the electrocautery return pad _____ away from the pulse generator and in a location that prevents a ______ line of current through the pulse generator

A

Far away

direct line

48
Q

Select the interventions that are NOT contraindications with a pacemaker or ICD

A. MRI

B. Lithotripsy

C. electroconvulsive therapy

A

NOT contraindicated:
B. Lithotripsy
C. electroconvulsive therapy

Contraindicated:
A. MRI

49
Q

ICD position 1 codes

A

SHOCK CHAMBERS

O= none
A= Atrium
V= ventricle
D= dual

50
Q

ICD position 2 codes:

A

ANTI-TACHYCARDIA PACING CHAMBERS:

O= none
A= atrium
V= ventricle
D= dual

51
Q

ICD position 3 codes:

A

TACHYCARDIA DETECTION

E= electrocardiogram
H= hemodynamic

52
Q

ICD position 4 codes:

A

ANTI-BRADYCARDIA PACING CHAMBERS

O= none
A= atrium
V= ventricle
D= dual

53
Q

An ICD cardioverts V tach with:

A

1-30 joules

54
Q

and ICD defibs V.fib with

A

10-30 joules

55
Q

If an ICD acknowledges that a shock is needed, it will deliver how many shocks?

A

6 shocks

56
Q

EMI:

A

Any external non-physiologic signal that interferes with pacemaker function
o Degree of EMI interference is variable
o Inhibition of pacemaker function, inappropriate triggering, electrical reset, damage at tissue -lead interference, tracking of electrical noises are all possible responses

57
Q

What is the most prevalent source of electromagnetic interference in the OR?

A

electrocautery

58
Q

monopolar cautery produces more energy than bipolar and requires a:

A

grounding pad

59
Q

Distance between the electrocautery tip and grounding pad will determine:

A

The area in which a stray current can be sensed and misinterpreted

60
Q

grounding pad should be placed near:

A

the site of surgery/ away from heart/pacemaker

61
Q

Why is bipolar cautery safer?

A

has the anode and cathode at the tip of the device, this proximity gives less area for a stray interface to be misinterpreted
o does not require grounding pad, gives off less energy, not generally a surgeon’s preference

62
Q

Effects of EMI

A

-Interpreted as serious dysrhythmia

-viewed as “noise” and initiate asynchronous pacing, leading to R on T

-Current conducted down lead and damage myocardium

-Decrease battery life

-Reset device to alternate rate

-Be interpreted as P wave causing device to only pace the ventricle, possibly losing atrial kick

-Reprogram and alter device setting

-Alter thresholds

63
Q

“Magnet rate”

A
  • typically 85-100 beats per minute
64
Q

If a magnet was used intraoperatively, what must be done post-operatively?

A

a device interrogation must occur postoperatively

65
Q

How much is each horizontal small box?

A

.04 seconds

66
Q

how much is each horizontal large box?

A

.20 secs

67
Q

how much is one small box vertically?

A

1mm (0.1mV)

68
Q

what is the J-point?

A

end of QRS and beginning of ST segment

69
Q

what is the J-point used to identify/measure?

A

use the J point with the ST segment to identify myocardial ischemia

70
Q

threshold values for ST segment depression in males and females of all ages in leads V2-V3

A

-0.5mm (-0.05mV)

71
Q

threshold values for ST segment depression in males and females of all ages in all other leads

A

-1.0 mm (-0.1 mV)

72
Q

best leads for continuous monitoring of ST segment changes:

A

V3
V4
V5
III
avF

73
Q

best leads for continuous monitoring of ST segment changes:

A

V3
V4
V5
III
avF

74
Q

what is the best lead to assess narrow QRS complex rhythms?

A

Lead II

75
Q

Which lead is best to assess ST segment changes?

A

V5 and V3

76
Q

H’s

A

Hypovolemia
Hypoxia
Hydrogen ion excess (acidosis)
Hypoglycemia
Hypokalemia
Hyperkalemia
Hypothermia

77
Q

T’s

A

Tension pneumothorax
Tamponade – Cardiac
Toxins
Thrombosis (pulmonary embolus)
Thrombosis (myocardial infarction)

78
Q

V.fib/pulseless Vtach ACLS intervention

A

CPR 2 mins
shock
CPR 2 mins
Epi 1mg Q3-5 mins
shock
CPR 2 mins
Amiodarone 1st dose: 300mg
Amiodarone 2nd dose: 150mg

79
Q

Asystole/PEA ACLS

A

CPR 2 mins
Epi 1mg every 3-5 mins

80
Q

Bradycardia ACLS

A

Atropine first dose: 1mg (repeat 3-5 mins)
max: 3mg

transcutaneous pacing

dopamine infusion (5-20mcg/kg/min)

Epi infusion (2-10mcg/per)

81
Q

when will you see torsades?

A

Seen with hypokalemia, hypocalcemia, hypomagnesemia

May be worsened with lidocaine administration

82
Q

whats the rate of torsades?

A

150-250bpm

83
Q

if the pt has a pulse and v.tach how would you treat it?

A

synchronized cardioversion

84
Q

When is a. fib considered “controlled”?

A

Rate less than 100

85
Q

T/F: you can measure the PR interval in a.flutter

A

FALSE

86
Q

How long is the PR interval in first degree heart block?

A

> .20 secs

87
Q

What are the characteristics of second degree block-mobitz 1 (wenkeback)?

A

Atrial rhythm is regular, but the ventricular rhythm is irregular

PR progressively lengths until QRS complex is dropped

88
Q

what are the characteristics of second degree AV block- mobitz II?

A

p-waves are normal, but some are not followed by QRS

PR intervals are constant- the dropped QRS occurs w/o warning

89
Q

What is the rate in 3rd degree?

A

Less than 45

Pacer is needed

90
Q

What is the rate in Sinus tach?

A

100-160

91
Q

Males > 40 years of age J-point elevation in all leads

A

1 mm (0.1mV)

92
Q

Males > 40 V2, V3 J-point elevation

A

2 mm (0.2mV)

93
Q

females in all leads J-point elevation

A

> 1mm (0.1mV)

94
Q

females V2, V3 J-point elevation

A

1.5 mm (0.15mV)

95
Q

Causes of failure to capture:

A

-electrode displacement, wire fracture, and conditions that make the myocardium more resistant to depolarization:
-Hyper/hypokalemia
-Hypocapnia
-MI
-fibrotic tissue buildup around the pacing leads
-anti-arrhythmic medications

CV- principles (8 decks)

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