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EP Masterclass > EP > Flashcards

EP Flashcards

1
Q

Characteristics of Typical AVNRT

A

Dual nodal physiology
Down the slow, up the fast = short VA
Doesn’t involve A & V = tachy can end on A or V

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2
Q

VA time of typical AVNRT

A

<50ms

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3
Q

BBB and typical AVNRT

A

No change in VA time as A & V and bundle branches are not involved in tachy

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4
Q

Tachycardias involving the ventricle and AVN

A

AVRT
PJRT

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5
Q

Tachycardias not involving ventricles and AVN

A

AVNRT
AT
Intraatrial re-entry tachy
SA nodal re-entry
AF/AFlutter

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6
Q

BBB and AVRT

A

In AVRT or macro re-entrant, BBB on same side as AP will increase tachy cycle length

LBBB with left sided pathway - tachy now has to travel to RBB then myocardium before back up AP causing longer VA time.

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7
Q

Parahissian pacing

A

high outputs = narrow QRS as capturing AVN, HIS and local RV
low outputs = broad QRS as capturing only RV

Only excludes right sides postreoseptal APs

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8
Q

Parahissian pacing response

A

VA time increased = no evidence of septal accessory pathway
- with loss of HIS capture suggests VA time is dependent on HIS-bundle
VA time unchanged = evidence of accessory pathway
-

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9
Q

When can atrial capture during Vp be suspected?

A

When VA time is <60ms

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10
Q

Repetitive V

A

Ventricular response during curve with similar morphology and axis to paced beat

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11
Q

RVOT paced morphology

A

LBBB
Positive in inferior leads
avL negative

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12
Q

LVOT paced morphology

A

LBBB
Negative in inferior leads
avL positive

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13
Q

Response to entrainment

VAAV

A

AT

both antegrade and retrograde conduction occurs via AVN so last entrained atrial beat hits a refractory AVN

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14
Q

Response to entrainment

VAV (VAHisV)

A

AVRT or AVNRT

entrainment of atrium due to retrograde conduction over the ascending limb of AVNRT (regardless of type of AVNRT) or up the AP i.e. ORT then antegrade down the AVN

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15
Q

What does it mean if tachy terminates during entrainment?

A
  • Termination of tachy without affecting the atrium excludes AT i.e. end with a V
  • Tachy ends with A – likely AVRNT or AVRT
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16
Q

HIS sync VPBs :

No change in AA timing means?

A

exclusion of right sided AP

if AA changed, the only way for it to reach atrium that quickly would be because of an AP that conducts retrogradely

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17
Q

HIS sync VPBs :

Atrial advancement with resetting means?

A

AP that contributes to SVT mechanism is present i.e. ORT

next A is advanced, which subsequently advances next HIS and V

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18
Q

HIS sync VPBs:

Atrial advancement without resetting means?

A

AVNRT with bystander AP

no reset means next A is advanced but doesn’t advance next HIS and V

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19
Q

HIS sync VPBs :

Atrial advancement with different atrial activation sequence means?

A

bystander AP

e.g. from concentric to eccentric or 9-10 first to 5-6 first

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20
Q

HIS sync VPBs :

Atrial post excitation means?

A

ORT or decremental AP

delay of next A after HIS sync VPB

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21
Q

HIS sync VPBs :

Termination of SVT

A

ORT

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22
Q

What is the problem when a wobble is present?

A

Treating during SVT tachy with wobble (variations in cycle length more than 30ms) is un-useful.

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23
Q

What is the importance of post pacing interval (PPI)?

A

Used to differentiate between atypical AVNRT and AVRT that uses a septal AP.

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24
Q

What is para-HISian pacing?

A

Testing used to exclude presence of right sided septal AP

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25
Q

Purpose of an EP study

A

a) Antegrade and retrograde conduction properties of AVN/AP/ANVRT
b) If present, is AP/AVNRT safe?
c) Allows for SVT?

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26
Q

In Concentric atrial activation, where is A seen first on the CS channel?

A

channel 9-10

27
Q

In eccentric atrial activation, where is A seen first on the CS channel?

A

Can be anywhere on CS channel depending on diagnosis and localisation

28
Q

What does it mean if the on the MAP channels signals on channel 3-4 are seen to be ahead of signals on channel 1-2?

A

The ablation catheter tip (channel 1-2) has gone past the hot spot

29
Q

What is the advantage of using adenosine/verapamil?

A

VA and AV block which allows for hyperpolarisation of AP if still present before or after ablation

30
Q

Define Eccentric activation

A

atrial activation other than by AV node during V pacing
or early activation of ventricle during A pacing

31
Q

Define concentric activation

A

normal AVN activation of atria

*earliest atrial activation on HIS catheter first

32
Q

Define Wenckbach CL

A

The point at which the AP or AVN becomes refractory during incremental pacing

33
Q

Purpose of IVP

A

Discover what retrograde routes connecting ventricles to atria are available for impulse conduction

No VA conduction suggests lack of VA connection via AVN or AP and AT is more likely

34
Q

Define AV nodal echo beat

A

One beat of non-sustained tachycardia caused by anterograde conduction via the slow pathway. and subsequent retrograde activation via the fast pathway

35
Q

Conventional ablation therapy for AVNRT is what?

A

slow pathway modification

*aim to disrupt tachycardia substrate by ablating slow pathway and changing conduction properties

36
Q

What can indicate the operator is on the wrong site for ablation during AVNRT cases?

A

HIS signal on ablation catheter (Map)

37
Q

Why is Ablation of AVNRT is performed during Sinus rhythm?

A

Sinus Rhythm
​
*to increase stability of catheter and monitor AV association

38
Q

How many seconds of ablation for AVNRT should elicit Junctional Rhythm?

A

15s

*Accelerated junctional rhythm >120bpm could suggest ablation of fast pathway or AVN which increases risk of CHB

39
Q

What targets for ablation can be seen on the Map catheter to indicate good contact with the slow pathway?

A

Large V signal
Small A signal
No HIS signal

40
Q

Identify the primary endpoints for AVNRT ablation

A

complete elimination or modification of slow pathway assessed by:

  • Presence of slow Junctional rhythm during ablation
  • Non inducibility of AVNRT
41
Q

Differential diagnosis for a wide complex tachycardia with RBBB and long RP in tachycardia

A
  1. atypical (fast-slow) AV nodal reentrant tachycardia
  2. orthodromic reciprocating tachycardia
  3. atrial tachycardia with an underlying bundle branch block
42
Q

Identifying AP location:
Late Transition in chest leads

A

Late (V3 and onwards) = lateral

43
Q

Identifying AP location:
Inferior leads (aVR, II,III)

A

All neg = posterior
All Pos = Anterior
Mismatch = midline

44
Q

Identifying AP location:
V1/V6

A

LBBB = right sided (Bigger S wave in V1)
RBBB = left sided (Bigger R wave in V1)

45
Q

Antidromic AVRT has a long or short RP?

A

Long

46
Q

Contraindications of adenosine

A

second and third degree AV block
allergy
care with asthma and COPD

47
Q

Why should adenosine not be administered for suspected VT?

A

Andenosine in VT can accelerate the frequency and aggravate the arrhythma.

If suspected SVT and adenosine is administered and the response is no effect or tachy acceleration then likely VT

48
Q

End point criteria for AVNRT slow pathway ablation

A

No jump
No echo
Slow pathway block

49
Q

When to tell operator to stop during AVNRT ablation

A

Getting close to AVN
Too many ablation points with no true junctional response

50
Q

How do you reveal a pathway?

A
  • Adenosine - disable the AVN
  • Ap fast enough to cause decrement in the AVN to allow AP to beat it and conduct first
  • pace closer to the pathway
51
Q

How do you pace close to an AP without moving a catheter or using a RA catheter?

A

Pace from different poles on the CS.

9-10 to pace the right side of the atrium (RA)
5-6/7-8 for septal
1-2 to pace left side of atrium (LA)

52
Q

PPI for right sided pathways short or long?

A

Short usually 30-40ms because the tachy is within the RV circuit

53
Q

What is atrial fusion?

A

when the atria is activated partly by a sinus impulse and partly by a retrograde impulse from the AVN or ventricle

54
Q

What do changes to atrial activation during SVT or Vp suggest?

A

Multiple bypass tracts

55
Q

Where is the usually the earliest site of atrial activation during AVRT tachy?

A

Adjacent to the mitral or tricuspid annulus and atrial activation is identical to during Vp.

56
Q

What would retrograde atrial activation (I.e. during Vp) for an A tach look like?

A

Normal midline pattern across the AVN and not near the annuli which differs from eccentric (antegrade) during AT. *could be similar if AT is located in the same region as a septal pathway)

Note: remember eccentric atrial activation during AVRT/AVNRT tachy would be identical to retrograde atrial activation.

57
Q

Eccentric atrial activation during Vp and tachy is more likely to be diagnostic of what?

A

AP

Eccentric atrial activation during tachy rules out AT because AT has normal nodal midline retrograde activation.

58
Q

VA dissociation during tachy rules out what?

A

AVRT

59
Q

What does it mean to bracket the earliest site with a deca nav catheter?

A

To demonstrate later activation on either side of the earliest site.

If not reachable via the CS, left sided mapping should be performed

60
Q

Why is it important to map along the tricuspid annulus for a right sided pathway?

A

SA node activation combined with pathway activation might give high low appearance on map causing incorrect diagnosis of sinus node re-entrant tachy or intra atrial reentrant tachy

61
Q

Septal bypass tracts, anterior or posterior, demonstrate what?

A

A normal retrograde atrial activation sequence

Differentiate between AVN and AP via fixed or decremental properties.

62
Q

Why is VA time in AVRT longer than in typical AVNRT?

A

SVT using AP goes to ventricle first before returning to atrium

  • but in atypical AVNRT, long RP means VA times could be similar to AVRT
63
Q

Localising accessory pathways:
Early transition in chest leads

A

Early (by V2/V3) = septal

EP Masterclass (7 decks)

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