Pacemakers

Question 1

What is a stress test?

Answer 1

Provocative measure to disclose disease

Question 2

What is it that’s being stressed?

Answer 2

Cardiovascular system, usually cardiac perfusion

Question 3

Name five methods for stressing.

Answer 3

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

Question 4

Name several indications for stress testing

Answer 4

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

Question 5

Which is most common?

Answer 5

TM

Question 6

What is MVO2?

Answer 6

Myocardial oxygen demand

Question 7

Define ischemia.

Answer 7

Lack of O2 delivery;lack of blood flow to tissue

Question 8

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

satisfied?

Answer 8

Demanded: Systole
Satisfied: Diastole

Question 9

What does CAD stand for?

Answer 9

Coronary artery disease

Question 10

What causes it? (CAD)

Answer 10

Obstruction of coronary arteries, usually by plaque/clot

Question 11

What is the usual mechanism of M.I.?

Answer 11

Rupture of plaque, thrombosis, and occlusion of artery

Question 12

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

Answer 12

Not necessary hemodynamically significant

Question 13

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

Answer 13

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

Question 14

How is cardiac ischemia detected during stress testing?

Answer 14

Changes in ECG

Question 15

What are the ST criteria for stress-induced ischemia?

Answer 15

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

Question 16

What is the J point?

Answer 16

End point of QRS complex; marks beginning of ST segment

Question 17

What are three forms of ST sloping?

Answer 17

Downslope, upslope, horizontal

Question 18

Which is a poor indicator of ischemia?

Answer 18

Upslope

Question 19

Is chest pain the only symptom of CAD?

Answer 19

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

Question 20

What test might be combined with treadmill to disclose ischemia?

Answer 20

Thallium (nuclear med) perfusion test

Question 21

Define sensitivity and specificity.

Answer 21

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

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

Question 22

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

Answer 22

Roughly 75%

Question 23

Is it treadmill testing therefore not that useful?

Answer 23

No, still useful, especially when positive

Question 24

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

Answer 24

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

Question 25

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

Answer 25

Predicted max rate heart can achieve; 220 – age

Question 26

What is the target heart rate? How calculated?

Answer 26

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

Question 27

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

Answer 27

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

Question 28

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

Answer 28

All that moving creates ECG noise

Question 29

What should you monitor carefully during the test?

Answer 29

Patient condition

Question 30

What visual cues might be important to note?

Answer 30

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

Question 31

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

Answer 31

Speed and grade

Question 32

How long are the stages?

Answer 32

3 minutes

Question 33

How much increase in speed and grade with each stage?

Answer 33

About 0.8 mph per stage, 2% grade per stage

Question 34

What are good reasons to stop the test?

Answer 34

``` 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 ```

Question 35

What arrhythmias call for stopping?

Answer 35

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

Question 36

What is significant about the recovery period?

Answer 36

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

Question 37

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

Answer 37

Claudication; LE PAD

Question 38

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

Answer 38

TM, toe-raises, walk hallway

Question 39

What causes a drop in ankle pressure compared to resting?

Answer 39

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

Question 40

How much drop is mild? Severe?

Answer 40

20% is mild, 50% severe

Question 41

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

Answer 41

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

Question 42

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

Answer 42

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

Question 43

What two basic functions do pacemakers perform?

Answer 43

Sense cardiac activity; pace.

Question 44

What are the basic components of pacemakers?

Answer 44

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

Question 45

What are the two basic categories of generators?

Answer 45

External and implantable.

Question 46

What other function might the generator provide besides routine pacing?

Answer 46

Defibrillate

Question 47

What is a Reed switch?

Answer 47

Switch in pacer controlled by magnetic field through skin.

Question 48

What are the two usual fixation devices on pacer leads?

Answer 48

Tines and screw

Question 49

Where is a pacemaker generator unit usually installed

Answer 49

Under skin below left clavicle

Question 50

Name some indications for pacing.

Answer 50

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

Question 51

What is capture?

Answer 51

The pacer is able to bring about cardiac activity

Question 52

What is capture dependent upon?

Answer 52

Voltage | Condition of myocardium Lead resistance

Question 53

How do we know when we have capture?

Answer 53

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

Question 54

Define “undersensing” and “oversensing.”

Answer 54

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

Question 55

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

Answer 55

Spike not followed by appropriate ECG activity

Question 56

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

Answer 56

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

Question 57

How would a VVI pacemaker work?

Answer 57

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

Question 58

A VAT?

Answer 58

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

Question 59

DDD?

Answer 59

Paces both, senses both, both responses possible

Question 60

AAI?

Answer 60

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

Question 61

How are pacemakers programmed once implanted under the skin?

Answer 61

Magnetic pulses

Question 62

What is a fusion beat?

Answer 62

Paced beat created along with intrinsic beat

Question 63

What does it look like on the ECG?

Answer 63

Pace and intrinsic beats both appear on ECG

Question 64

What goes wrong with pacers most often?

Answer 64

Lead wire damage

Question 65

What is “twiddler's syndrome”?

Answer 65

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