Arrhythmia and Ablation conference for

Advanced practice providers

( What do we do when you send your patient

to the EP lab for ablation)

Edwin Zishiri, MD

Cardiac Electrophysiologist

Michigan Heart and St. Joseph Mercy

Hospital

March 19 2016

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Goals/Objectives

To introduce the tools we use in the EP lab to identify, locate, and eliminate tachyarrhythmicsources.

To use two different types of cases we commonly do as illustrations of how we use these tools.

To leave a few minutes at the end of the talk for Q&A.

To hopefully not bore you to death.

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Behold, the humble

mapping/ablation catheter…

EP catheters are usually deflectable, and

come with various numbers and spacing

of electrodes, as well as degrees of distal

curve.

By convention, the more distal the electrode, the

lower its number.

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RAO image of basic EP catheters in place

Imaginary TV outline

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Baseline Bipolar Intracardiac EGM’s

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SVT

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Once we get catheters in place, we pace from

atrium and ventricle to determine the conduction

properties of the AV node

Dual physiology?

Is there retrograde V-A conduction

Is retrograde conduction concentric or

eccentric?

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S F S F S F* * F

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S F S F S F* * F

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“Concentric” retrograde atrial activation

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“Eccentric” retrograde atrial activation

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Then, we try to make something happen –

using pacing, medications, or both.

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Automatic – tends to warm up, warm down, and classically cannot be either induced or terminated by pacing. Usually have to get them on a little isoproterenol.

Triggered activity – Usually refers to DAD’s, for our purposes – intracellular calcium buildup, often cAMP mediated. Burst pacing pretty good at bringing these rhythms out (if not occurring spontaneously.) Isoproterenol and calcium can be helpful.

Reentry – Far and away the most common mechanism. Programmed extrastimulation classically brings this out. Can be “entrained”…

A brief reminder on tachycardia mechanisms…

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Once we get it going, we take time to look at the

characteristics of the tachycardia

– 1:1 A-V relationship?

– Long or short R-P tachycardia?

– Atrial activation pattern

– How it initiates

– How it terminates (if spontaneously)

– Changes in response to perturbations in the rhythm

(either spontaneous or those we cause with pacing

maneuvers.)

A class of pacing maneuver worth spending a

few minutes on is that of “entrainment”

1515

• All re-entrant circuits have the following

components:

– 1) An anatomic or functional obstacle (call it scar,

annulus, or whatever) where a wavefront collides and

so must go around,

– 2) Separate potential entry and exit sites, and

– 3) Anisotropic conduction and repolarization

properties of the tissue surrounding the obstacle.Benito and

Josephson,

Rev Esp de

Cardiologia

2012, Vol 65

(10)

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Entrainment, conceptually…

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Entrainment is a continuous resetting of the tachycardia

circuit by repetitive pacing stimuli.

Entraining a tachycardia not only tells us that it IS re-entrant

and has separate entrance and exit sites, but also how far or

close our pacing source is to the re-entrant circuit…

Thought Experiment: Two friends, one stationary and one on a merry-go-round….

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Two of these tachycardias are re-entrant and entrainable by

Ventricular Overdrive Pacing (“VOD”); one is not.

AVNAVNPathway

Typical

AVNRT

Orthodromic

AVRTAtrial tach

“Slow”

“Fast”

AVN

Three PSVT’s with 1:1 V-A relationship

Responds

V-A-V to

VOD

Responds

V-A-V to

VOD

Responds

V-A-A-V

to VOD

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An example of the use of entrainment during SVT:

Ventricular overdrive pacing

V V

A

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The SVT diagnosis affects how we map and ablate:

– AVNRT ablation is largely guided by anatomy and

characteristic “slow-pathway” electrograms

– In focal atrial tachycardias, on the other hand, we

are mapping the earliest atrial activation (a game of

“hot or cold”)

– In accessory pathway tachycardias, we either map

the earliest retrograde atrial activation via the

pathway, or earliest anterograde ventricular activation

(if pathway is “manifest”)

Why does this matter?

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SP

FP

His

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Slow Pathway setup (CARTO image)

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Slow pathway EGM

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When you heat up the slow pathway…

Junctional

beats

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Mapping ORT EGM (cold)

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Mapping ORT EGM2 (hot)

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Segue into mapping systems…

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•In one common mapping system, a set of separated

coils placed under the patient emit their own

magnetic fields

•A sensor near the tip of the catheter detects each

magnetic field signature; changes in detected field

strength signify changes in distance

•When in contact with endocardium, local

electrograms are detected on the bipolar electrodes

•Thus electrograms can be correlated with

triangulated points in space.

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ORT activation map (done in tachycardia)

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Do we NEED mapping systems for

mapping/ablation of AVNRT, focal AT,

accessory pathways, typical flutter - or even

standard PVI for that matter? Actually, no...

But even in these cases, they can improve

efficiency (mark where you’ve been, where you

need to go), and significantly reduce the need

for fluoroscopy.

In the case of macroreentrant circuit mapping

(atypical flutters, scar-related VT) these systems

become essential.

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Re-entrant, scar-related VT

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Most common mechanism of ventricular

tachycardia

To map and eliminate it, we integrate a lot of

information, using a combination of:

Pace-mapping during sinus rhythm (to hone in

on potential “exit” site/s of VT)

Marking locations with “interesting” signals

during sinus rhythm using EAM

Voltage mapping (to define scar borders)

using EAM

Activation mapping during VT using EAM

Entrainment mapping during VT30

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Endocardial mapping/ablation either retrograde

aortic or transseptal approach (some locations

easier one vs the other)

ENDO VIA

RETROGRADE AORTIC

From Sacher et al,

JACC May 25, 2010Courtesy of Omeed Zardkoohi

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Pace Mapping can give clues as to where to begin…

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Makhija et al,

Indian Pacing

Electrophys

2009;9(6)

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Stylized representation of scar-related VT

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Voltage map (s/p large inferolateral MI)

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Activation mapping during tachycardia

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Entrainment during VT: Pacing from this site tells

us we need to move on, but we may be close…

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On the other hand, this kinda thing gets EP’s excited…

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The rationale for time spent in carefully mapping

the critical isthmus is to identify the narrowest

point where the re-entrant impulses funnel through

– as it’s where the circuit is most vulnerable.

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Termination with ablation (slower sweep speed)

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Finally, FYI…

• As EP’s, we tend to like hemodynamically stable

VT’s, as it allows more precision mapping and

ablation during VT rather than “scar-modification” in

sinus rhythm (a.k.a. carpet-bombing…)

• Invasive hemodynamic support has increased the

number of cases where we can map in VT

• Also, our knowledge of the “target of interest”

electrograms while mapping in sinus rhythm has also

improved outcomes even if VT is not mappable

hemodynamically.

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Let’s stop there (whew!)…

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LAO projection with

two sheaths across,

Lasso in LSPV

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Far-field

atrialLocal PV EGMs

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Please send for ablation

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77 yo man presents to ER with

shortness of breath

Different VT

Prexcited ECGs

Post ablation

Weeks later with resolution of TWI

SVT

Another SVT

EP Study

PVC terminates Tach and then

reinitiates

Diagnostic pacing maneuvres

Termination with ablation

1111111111111111

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11111

1

21 yo man with hemochromatosis admitted

After a syncopal event. He has daily

Palpitations. EF 20 %. Down from 50 %

54 year old man s/p mitral valve repair , PFO closure , surgical cryoMaze ,

Left atrial appendage ligation 4 weeks prior admitted with SOB . Failed DCCV X4. ?

? Ablation