ICDs (edit)

Question 1

Heart attack

Answer 1

Blockage of Coronary arteries
The heart muscle is robbed of its vital blood supply and, if left untreated, will begin to die because it is not getting enough oxygen.

Question 2

Cardiac arrest

Answer 2

Sudden cardiac arrest is the abrupt loss of heart function, breathing and consciousness.

The condition usually results from a problem with your heart’s electrical system, which disrupts your heart’s pumping action and stops blood flow to your body.

Question 3

Relationship between cardiac arrest and heart attack

Answer 3

cardiac arrests in adults happen because of a heart attack. This is because a person who is having a heart attack may develop a dangerous heart rhythm, which can cause a cardiac arrest (I.e. heart stops pumping and breathing stops)

Question 4

Brugada syndrome

Answer 4

characterized by incomplete right bundle-branch block and ST-segment elevations in the anterior precordial leads

Question 5

Effects of ajmaline on electrophysiology

Answer 5

Ajmaline (class 1A) - sodium channel blocker

Main effect = longer refractory period and slower repolarisation

• lengthens the refractory period of the heart by blocking sodium ion channels = slower depolarisation = prolonged QR and longer action potential

Minimally blocks potassium channels = slower repolarization because it is harder for potassium to get out due to less unblocked channels = RS interval longer

Question 6

Explain how antiarrhytmic drugs work

Answer 6

They work by blocking certain channels in cardiac cells

the blockage of channels means less ions can influx or leave cells thus affect how they act on conduction or repolarisation in the heart

Question 7

Why can ajmaline be used to test for Brugada?

Answer 7

They both affect sodium channels - ajmaline prolongs refractory and widens QRS revealing brugada pattern

• The abnormal ECG pattern associated with Brugada is only seen spontaneously due to unknown triggers or after challenged by particular drugs

Question 8

Why choose SICD over ICD?

Answer 8

No pacing indication
No ATP required
Save/preserve venous vasculature

Question 9

Can ICDs be programmed unipolar?

Answer 9

No - risk of oversensing mypotentials negates it ability to be programmed unipolar regardless of lead issues

*dual chamber ICDs (atrial lead) also cannot be programmed unipolar due to risk of more A than V during V event = no therapies

Question 10

What is the LV lead used for in CRT-D devices?

Answer 10

LV lead is used for pacing

*not sensing - only RV lead is used for sensing

Question 11

Parameters to consider reprogramming in the occurrence of T wave oversensing

Answer 11

Sensitivity
sense polarity
T wave oversensing discrimination

Question 12

Non-physiologic cycle lengths are

Answer 12

100-200ms

Question 13

VT common in teens, near conduction system and hemodynamically stable (sometimes)

Answer 13

Fascicular VT

Question 14

What Medtronic algorithm is at work here?

Answer 14

NCAP

Question 15

What Medtronic algorithm is at work here?

Answer 15

NCAP

Question 16

NSVT means

Answer 16

Device detected but terminated before charge end

Question 17

VT Mon means

Answer 17

Detected in VT mon zone but not sustains long enough to be detected in VF or faster zone (if rates reach that zone)

Question 18

Why does HCM cause arrhythmias and symptoms?

Answer 18

The abnormal development of the muscle walls of the heart can cause electrical pathways to become disrupted, resulting in irregular heart beats and arrhythmias

Question 19

VT shocks

Answer 19

Cardiovert

Question 20

VF shocks

Answer 20

Defibrillate

Question 21

Patient has appropriate therapy for ventricular tachycardia, however patient was no fully unconscious when shock occurred and was traumatised. What considerations should be made when reprogramming therapies for optimisation?

Answer 21

Suitable therapy to successfully terminate arrhythmia
- ATP (most likely will not work in some conditions but appropriate to allow pain free therapy
- sometimes allow ATP to accelerate arrhythmia then patient is unconscious and can be shocked

Question 22

What are the 4 types of shocks possible for ICDs?

Answer 22

Appropriate
Inappropriate
Unnecessary
Unsuccessful
Unwanted

Question 23

ICD

What is sensing?

Answer 23

Process by which the ICD determines the prescience of a cardiac signal

“I see something”

Question 24

ICD

What is detection?

Answer 24

Process by which ICD counts, measured and sorts the signals that it senses in order to identify an arrhythmia and make a therapy decision

“Here’s what I think”

Question 25

What does an ICD need to determine if a tachyarrhythmia is present?

Answer 25

Definition of VT/VF rate = therapy zone
Rate = detection window
Duration = duration
Other clues = detection enhancements
Check again = last interval in zone

Question 26

ATP settings are from which trial?

Answer 26

PainFree RX trial

*number of bursts: 1
Pulses per burst: 8
Couple interval: 88%
Burst cycle length: 88%
Minimum interval: 220ms

Question 27

What criteria can be used to selection detection algorithms? - tachy rates

Answer 27

1. What are the slowest tachycardia rates observed on the concurrent pharmacological regimen?

• determines high rate detection cutoff
• value chosen should be slightly below each ranch rate (10-20bpm)m

*monomorphic VT:
e.g. Tachycardia rate 180bpm -> rate boundary: 170bpm

Polymorphic monomorphic VT:
e.g. tachycardia rate 180bpm -> rate boundary 160bpm

Question 28

What criteria can be used to selection detection algorithms? - sinus rates

Answer 28

What is the fastest attainable Sinus rate

If this is close to or above the minimum observable tachy rate, sudden onset should be used

Question 29

What criteria can be used to selection detection algorithms? - exercise

Answer 29

Does the patient have exercise induced tachycardia?

If yes, Sustained rate duration may be programmed

Value chosen should be longer than patients max exercise duration

Question 30

Does the patient have AF with RVR in addition to VT??

Answer 30

If yes, rate stability should be used to discriminate between AF and VT