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Year 3 Cardiac physiology > CRM 4,5 - Introduction to Pacemaker Timing and the NBG Pacing Code > Flashcards

CRM 4,5 - Introduction to Pacemaker Timing and the NBG Pacing Code Flashcards

1
Q

Describe the complex

A

-A paced, V sensed

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2
Q

Describe the complex

A

-A sensed, V sensed
-A paced, V paced

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3
Q

Describe the complex

A

-A sensed, V paced

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4
Q

What is capture?

A

-Depolarisation following the pacing impulse

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5
Q

What is sensing?

A

-When intrinsic complex is seen

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6
Q

How do you convert interval to rate?

A

60bpm = 1000ms

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7
Q

How do you convert rate to interval?

A

60bpm = 1000ms

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8
Q

What is pacing interval?

A

-Time period between an event (paced or sensed) and the next event in the same chamber

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9
Q

What is an active pacing interval?

A

-Active pacing intervals can be interrupted and restarted by a paced or sensed event

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10
Q

What are refractory/blanking intervals?

A

-Refractory interval starts after paced/sensed beat
-Refractory interval categorises signals picked up
-Blanking period ignores signals picked up

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11
Q

Lower rate interval/limit

A
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12
Q

How does pacemaker create intracardiac electrogram (EGM)?

A

-Measured from tip/ring of pacing lead
-Only a few discrete cells at the point of contact create the sharp bipolar signal
-Pacemaker can only see this sharp signal, not surface ECG

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13
Q

What are farfield signals?

A

-Signals from another cardiac chamber seen on electrogram

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14
Q

What is atrial refractory?

A

-Notices the complex
-But does nothing

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15
Q

What is retrograde

A

-Signals that fall into refractory periods can be termed retrograde

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16
Q

Pacemaker code

A

Pace
Sense
Trigger/Inhibit

E.g. DOO - Dual pace, nothing, nothing

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17
Q

What is this?

A

-AOO
-Atrial pacing spikes
-Exact interval between spikes

18
Q

What is this?

A

-VOO
-Ventricular pacing spikes
-Exact interval between spikes

19
Q

Issue with non-sensing modes

A

-VOO can cause VF (R on T)
-AOO can cause AF
-Uses up battery

20
Q

What is the interval that matters in AAO/VOO?

A

-Lower rate interval

21
Q

What is this?

A

DOO
-AV interval (PR interval)

22
Q

Features of DOO

A

-Atrial and ventricular spikes
-Lower rate limit and AV interval
-Intrinsic A and V not sensed
-Intrinsic signals do not trigger/inhibit

23
Q

What do refractory periods prevent?

A

-Double counting the same event
-Sensing the pacing stimulus, it’s after potential, and the evoked response
-In dual chamber devices, prevent PMT and cross-talk

24
Q

What is this?

A

AAI(R)
-Lower rate interval shortens at the end

25
Q

What is this?

A

VVI(R)

26
Q

What is this?

A

DDD
-Paced QRS if there is no intrinsic beat during AV interval

27
Q

Other modes to consider

A

AAT - sees intrinsic atrial beat, triggers atrial paced beat
VVT - sees intrinsic ventricular beat, triggers ventricular paced beat
VDD - Only paces ventricle, senses both to set up AV interval
DDI- A-sensed events inhibit atrial spike

28
Q

Pacemaker timing (could be in exam)

A
29
Q

What are the 2 types of refractory period?

A

Absolute/blanking - no signals ‘seen’
Relative/noise sampling - ‘sees’ and categorises signals but does not reset lower rate/refractory period

30
Q

Absolute refractory period
Relative/noise sampling period
Alert period

A
31
Q

Normal sinus node, complete AV block

A

-Let sinus node control atria
-Dual chamber pacemaker
-To sense P waves and create AV delay
Or
-Single chamber pacemaker with rate response

32
Q

How does VVIR work?

A

-Upper rate interval
-Lower rate interval
-If it doesn’t see anything, it will pace
-Makes interval shorter with activity

33
Q

Symptoms in VVI pacemaker

A

-Dizziness
-Fatigue
-SOB
-Oedema
-Hypotension
-Due to loss of AV synchrony
-V pace while atria is contracting

34
Q

Which devices have AV delay?

A

-Only dual chamber devices (AV synchronous pacing)

35
Q

What are the 2 types of AV delay?

A

pAV - paced AV interval
sAV - sensed AV interval
-Allows ventricular filling

36
Q

Why is pAV longer than sAV?

A

-Sensing starts in the middle of the P wave

37
Q

What is the VA interval?

A

-Interval from paced/sensed ventricular event to next atrial event

38
Q

What type of pacing does MTR apply to?

A

As Vp

39
Q

When does MTR start?

A

-After AV delay
-When p/s V wave starts
-Along with lower rate limit

40
Q

What is the MTR?

A

Maximum Tracking Rate
-Fastest rate at which dual chamber pacemaker can pace ventricle after a sensed p wave

41
Q

If patient’s sinus node is working (p waves), what type of pacemaker should you give?

A

-Dual chamber pacemaker

Year 3 Cardiac physiology (30 decks)

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