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CVT 112: Pacemakers > Pacemakers > Flashcards

Pacemakers Flashcards

1
Q

What is a stress test?

A

Provocative measure to disclose disease

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2
Q

What is it that’s being stressed?

A

Cardiovascular system, usually cardiac perfusion

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3
Q

Name five methods for stressing.

A

Harvard step test, treadmill, bicycle ergometer, arm ergometer, toe raises,
walk in hall

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4
Q

Name several indications for stress testing

A

Suspected CAD, detect arrhythmias, evaluate cardiac function, evaluate therapy, LE arterial disease, sports medicine

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5
Q

Which is most common?

A

TM

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6
Q

What is MVO2?

A

Myocardial oxygen demand

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7
Q

Define ischemia.

A

Lack of O2 delivery;lack of blood flow to tissue

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8
Q

In the cardiac cycle, when is demand created, and when is it

satisfied?

A

Demanded: Systole
Satisfied: Diastole

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9
Q

What does CAD stand for?

A

Coronary artery disease

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10
Q

What causes it? (CAD)

A

Obstruction of coronary arteries, usually by plaque/clot

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11
Q

What is the usual mechanism of M.I.?

A

Rupture of plaque, thrombosis, and occlusion of artery

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12
Q

How severe must plaque be to cause M.I.?

A

Not necessary hemodynamically significant

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13
Q

What implication does that have for the utility of stress testing?

A

It will miss some lesions that can still cause M.I.

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14
Q

How is cardiac ischemia detected during stress testing?

A

Changes in ECG

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15
Q

What are the ST criteria for stress-induced ischemia?

A

ST depression 2 mm, ST elevation 1 mm, ST slope (maybe), T wave
inversion

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16
Q

What is the J point?

A

End point of QRS complex; marks beginning of ST segment

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17
Q

What are three forms of ST sloping?

A

Downslope, upslope, horizontal

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18
Q

Which is a poor indicator of ischemia?

A

Upslope

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19
Q

Is chest pain the only symptom of CAD?

A

No; other symptoms (pressure, SOB, fatigue, etc.) possible, especially in female pts.

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20
Q

What test might be combined with treadmill to disclose ischemia?

A

Thallium (nuclear med) perfusion test

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21
Q

Define sensitivity and specificity.

A

Sensitivity: ability to call positive when it’s truly positive

Specificity: ability to call negative when it’s truly negative

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22
Q

What is the overall accuracy (positive and negative) of treadmill testing?

A

Roughly 75%

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23
Q

Is it treadmill testing therefore not that useful?

A

No, still useful, especially when positive

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24
Q

Name a couple of causes of false positive or false negative with TM.

A

BBB, MV prolapse, diuretics, previous M.I.

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25
Q

What is the “maximum heart rate”? How calculated?

A

Predicted max rate heart can achieve; 220 – age

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26
Q

What is the target heart rate? How calculated?

A

Rate to shoot for in test; usually 85% of max rate

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27
Q

What test data are/might be collected during a stress test?

A

Duration, heart rate, BP, ST changes, any arrhythmias, possibly oxygen
consumption, any anginal pain or claudication, any dyspnea

28
Q

Why is electrode prep important (more than for resting ECG)?

A

All that moving creates ECG noise

29
Q

What should you monitor carefully during the test?

A

Patient condition

30
Q

What visual cues might be important to note?

A

Breathing, sweating, skin color, ability to talk and interact, facial expression

31
Q

What two aspects of the exercise are changed during the Bruce protocol?

A

Speed and grade

32
Q

How long are the stages?

A

3 minutes

33
Q

How much increase in speed and grade with each stage?

A

About 0.8 mph per stage, 2% grade per stage

34
Q

What are good reasons to stop the test?

A 
Positive ECG changes
Reach target HR
Pain, angina or otherwise (like claudication) SOB
Finish all stages!
Arrhythmia
Drop in BP
Drop in O2 sat
Patient desires to quit
35
Q

What arrhythmias call for stopping?

A

V tach
PVCs (frequent)
Paired PVCs
Heart block develops (2nd or 3rd degree)

36
Q

What is significant about the recovery period?

A

Must watch patient carefully; can be dangerous period if there’s disease

37
Q

What condition usually calls for stress testing in the vascular lab?

A

Claudication; LE PAD

38
Q

What forms can the stress take? (for stress testing)

A

TM, toe-raises, walk hallway

39
Q

What causes a drop in ankle pressure compared to resting?

A

Exercise causes vasodilatation, increased flow through stenosis (and
through collaterals), increased loss of energy (i.e., pressure)

40
Q

How much drop is mild? Severe?

A

20% is mild, 50% severe

41
Q

What ABI suggests the stress test is unlikely to be useful?

A

Less than around 0.40; arterioles are likely already maximally dilated…

42
Q

What is a pacemaker? Don’t we already have them?

A

Device to stimulate cardiac activity. Yes, but sometimes they don’t work so
well.

43
Q

What two basic functions do pacemakers perform?

A

Sense cardiac activity; pace.

44
Q

What are the basic components of pacemakers?

A

Generator and lead wires; those can be epicardial or endocardial.

45
Q

What are the two basic categories of generators?

A

External and implantable.

46
Q

What other function might the generator provide besides routine pacing?

A

Defibrillate

47
Q

What is a Reed switch?

A

Switch in pacer controlled by magnetic field through skin.

48
Q

What are the two usual fixation devices on pacer leads?

A

Tines and screw

49
Q

Where is a pacemaker generator unit usually installed

A

Under skin below left clavicle

50
Q

Name some indications for pacing.

A

Brady arrhythmias
3Rd degree AV block Cardiac surgery
Asystole: heart dependent on pacer for any activity at all

51
Q

What is capture?

A

The pacer is able to bring about cardiac activity

52
Q

What is capture dependent upon?

A

Voltage

Condition of myocardium Lead resistance

53
Q

How do we know when we have capture?

A

Pacing spike is followed by a depolarization: QRS or P, depending

54
Q

Define “undersensing” and “oversensing.”

A

Undersensing: pacer doesn’t recognize intrinsic cardiac activity
Oversensing: pacer responds to non-cardiac signals (hair-trigger)

55
Q

How do we recognize when proper capture isn’t happening?

A

Spike not followed by appropriate ECG activity

56
Q

What do the letters of the first, second, and third letters in the function codes mean?

A 
PSR: chamber paced (A or V or Dual), chamber sensed (A or V or Dual),
and response (Inhibit or Trigger)
57
Q

How would a VVI pacemaker work?

A

Paces the ventricles, senses the ventricles, doesn’t pace if ventricles depolarize on their own

58
Q

A VAT?

A

Paces ventricles, senses atria, paces when atrial depolarization is sensed

59
Q

DDD?

A

Paces both, senses both, both responses possible

60
Q

AAI?

A

Paces atrial, senses atria, doesn’t pace if atrial activity is sensed

61
Q

How are pacemakers programmed once implanted under the skin?

A

Magnetic pulses

62
Q

What is a fusion beat?

A

Paced beat created along with intrinsic beat

63
Q

What does it look like on the ECG?

A

Pace and intrinsic beats both appear on ECG

64
Q

What goes wrong with pacers most often?

A

Lead wire damage

65
Q

What is “twiddler’s syndrome”?

A

Patient absent-mindedly twiddles wires under skin, possibly damaging them

CVT 112: Pacemakers (1 decks)

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