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Flashcards in Algorithms Deck (51):
1

What is the purpose of algorithms that search for intrinsic conduction

Minimize RV pacing
Extend battery life

2

5x Algorithms that encourage intrinsic and may account for rates lower than LRL

Search Hysteresis
Sinus preference
Rate Hysteresis
Scan Hysteresis
Sleep rate

3

2x Algorithms for neurocardiogenic snycope

Rate drop response (Medtronic)
Sudden brady response (BSC)

4

Shorter PVAB =

greater detection of higher atrial rates (i.e. increased sensitivity to atrial tachyarrhythmias)

5

Longer PVAB =

increased specificity of rhythm detection + reduced risk of inappropriate mode switch.

6

PMT can only occur in 2 P-synchronous ventricular modes. Which are they

DDD
VDD

7

What causes a PMT

PVC

Failure of atrial capture during AV sequential pacing

At the end of ventricular threshold testing in VVI mode, where the device switches back to DDD immediately upon termination of the test and senses a retrograde P wave

Inappropriately long PVARP

8

During PMT is a higher programmed MTR more or less likely to induce symptoms

MORE - Higher MTR = Faster PMT

9

How does blanked flutter search work

Monitors 8 consecutive AA intervals that are less than twice the total atrial blanking period

Extends PVARP to uncover P-waves

10

What is non competitive atrial pacing

Triggered by AS event which occurs in PVARP

Delays atrial pacing till NCAP ends

11

List 5 algorithms designed to prevent AF

Pace conditioning
Rate Smoothing
PAC suppression
Post PAC response
Post AF response
Atrial preference pacing

12

How does pace conditioning work

Increases HR following PAC

ALSO PAC SUPRESSION

13

How does rate smoothing work

Atrial overdrive pacing just above pacing rate (3bpm)

14

How does post PAC response work

Avoids pauses after PAC

15

Which is the only algorithm to successfully distinguish SVT vs VT correctly

Morphology

16

What is the nominal probabilistic counter setting for morphology match

5/8 or 7/12

17

Specificity =

True negatives correctly identified as such

18

Sensitivity =

True positives correctly identified as such

19

What are two weaknesses of morphology

Inaccurate template
EGM truncation (amplified signal clipped)

20

What algorithm unique to S-ICD complements wavelet

QRS width

21

What algorithm looks at R-R intervals to decide whether rhythm is VT or AF

Stability

22

How does stability work

It looks at previous 3 RR intervals and if more than 40ms difference - it resets VT counter to 0

23

What is sudden onset

Algorithm to discriminate between sudden onset tachy and gradual onset tachy EG Sinus

24

Should onset be used at the sole discriminator

NO - Morphology should always be programmed on too

25

What is the cornerstone DR building block for discriminating SVT vs VT

A vs V rate

26

What is the weakness of Atrial vs Ventricular rate discrimination

Accurate atrial sensing during high ventricular rates

27

What are causes of atrial undersensing

Low amplitude EGMs
Functional interactions with PVAB

28

How does sudden onset in DR sensing work

SVT = Atrial event occurs between last V-event in sinus zone and V-event in VT zone

VT = No intrinsic atrial event in these two zones

29

Causes of atrial oversensing and best way to prevent it

FFRWS

lead placement where large A-EGM is seen without FFRW

30

How does St Jude differ from all manufacturers with regards to A vs V rate

Atrial lead senses V signals constantly

31

How does AV association work

Distance from A event to V event

Intervals calculated across 12 beats

Second shortest subtracted from second longest

If more than 40ms = VT

Unstable association indicates VT

32

How does PR logic identify FFRW

Successive sequences of short long AA intervals with >30ms differences

33

What percentage of RR interval regularity defines regular or irregular rhythms

>75% = Regular rhythm

<50% = irregular rhythm

34

Primary prevention patients DO NOT benefit from dual chamber SVT discrimination TRUE/FALSE

TRUE

35

Dual chamber ICDs are better than SR ICDs because of 3 things

Algorithms that reduce RV pacing in patients with SND
AF diagnostics
Atrial channel EGMS available

36

Single chamber ICDs are better than DR ICDs because of 3 things

Lower cost
Lower risk of complications
Increased longevity

37

How successful is 1st round ATP for VT

72-89%

38

How successful is 2nd round ATP for VT

35%

39

How successful is ATP for FVT >250bpm

6x ATP = 30% successful

40

Burst +- Scan is more successful than ramp with less acceleration - TRUE/FALSE

TRUE

41

Define Burst

All ATP burst (nominally 8) is delivered at same CL

42

Define Scan

Same as burst however ATP (8 beats) is delivered at 1CL then next 8 = slightly shorter CL then shorter again

43

Define Ramp

Each beat of ATP shortens in CL

44

Is there a significant advantage to programming more than 8 pulses of ATP

No

Unless in HF with EF <40%

45

ATP should not be programmed in patients with Polymorphic VT TRUE/FALSE

TRUE - as can induce rhythms less likely to respond to therapy

46

Should ATP be used for slow VT

Yes - however less aggressive.

E.G. 91% opposed to 81% CL

47

What is a type 1 response pattern to V ATP

Atrial cycle length remains stable, therefore V disassociated to A

More likely A-Tach / AVNRT

48

What is a type 2 response pattern to V ATP

Atrial cycle length varies = AVNRT or VT

49

What is a type 3 response pattern to V ATP

Atrial cycle length accelerates to V rate (Entrainment)

VAAV = AT

VVA = VT

50

Define PPI

Post pacing interval = Time required for last stim wavefront to reach circuit, travel around and return to pacing site

51

A PPI which varies <50ms is likely to be what

VT