Exam 3: Craig Swig AF, Afib, VT5

Where is typical AF usually located?

In the RA, CTI

Where is atypical AF usually located?

LA, septal

What are factor of Reentry?

- initiated with pacing/ esxtrastim

- terminated with pacing

- entrainment possible

What is the most common types of atypical AF?

Most commonly around mitral valve annulus

What are characteristics of typical flutter?

- CTI dependent (slow zone)

- most often CCW (80-90%)

- ablation target isthmus b/w tricuspid and IVC

What are tools needed for a CTI ablation?

1. Diagnostic catheters (his, rv,etc)

2. Ablation catheter

3. Additions: 3D mapping or ICE to minimize fluro, and specialty sheaths

What kind of ablation has been used historically and primarily used today?

Historically, it was a 8mm large-tip RF, today is irrigated-tip RF 4mm. A doc today may choose 8mm bc it will make a bigger and longer lesion

What is the presentation of typical CCW flutter on a 12-lead?

Inferior leads (-)

V1 (+)

V6 (-)

Negative sandwich

What is the presentation of typical CW flutter on a 12-lead?

Inferior leads (+)

V1 (-)

V6 (+)

Positive sandwich

What is the presentation of atypical flutter on a 12-lead?

Anything other than typical morphology, unless prior Maze or Afib ablation

What is the presentation of CCW flutter on EGM?

Proximal to distal

What is the presentation of CW flutter on EGM?

Distal to proximal

What is the difference between b/w the pentaray and the octaray?

The octaray has more electrodes and "filages"

How many electrodes does the basket catheter have?

64 electrodes

Describe atrial flutter ablation?

Ablation intersects conduction at narrowest part (CTI)of circuit, between the TV and the IVC (eustachian ridge). 6 o'clock in LAO

Describe transmural ablation?

Ablate all the way through the tissue

Describe the isthmus anatomy

- size of width varies from 17-54mm, mean 31.3

- angle b/w ablation catheter and in IVC and isthmus was 68-114 degree, mean 90.3

What are the different anatomical configurations of the isthmus?

1. Straight (31%)

2. Concave (22%)

3. Flat by TA and pouch like recess by IVC 47%

FuC'S (Flat, Concave, Straight)

What is the disadvantage to "spot welding" aka point-by-point ablation?

likely hood of leaving a gap between lesions

When ablating the CTI we have to make sure we also make contact with what structure?

Eustachian Ridge, can be seen on Noval Catheter position when using ICE

On ICE, what is the appearance of a structure that we have ablated?

White

What are the ablation end points fro AF?

- RA activation sequence

- trans-isthmus conduction time

- ECG changes

- double potentials

- change in electrogram polarity

- differential site pacing

BIDIRECTIONAL BLOCK IS KEY

How long does it take usually for activation to go around the RA?

250ms

What is the appearance of an EGM when we CS pace and dont have isthmus block vs when we do have block?

When we don't have block, there will be the appearance of the chevron pattern and a lot shorter conduction time. With block activation will be proximal to distal and sill have a shorter conduction time, but not as short as without block

What are the characteristics of AF with complete block?

1. Proximal to distal activation pattern

2. Double potentials seen on ablation catheter

What kind of pacing is used to confirm location of AF circuit?

Entrainment

What are potential adverse events of AF ablation?

- perforation/ tampanode

- damage conduction system

- unmasking of SND

- damage coronary artery

- vascular complications

- stroke/ coagulation

What is the conduction time when we have no block in AF?

<90ms

What is the conduction time when block is present (AF)?

>110ms

What are factors of Afib epidemiology?

- most common arrhytmia

- prevalence increases with age

What are complications of Afib?

Stroke and HF (related to V-rate)

Describe paroxysmal Afib

Episodes from 30s to 7 days and terminate spontaneously or with intervention

Describe persistent Afib?

Continuous AF episodes longer than 7 days, <1yrs

Describe longs trading persistent Afib?

Episodes longer than 1yr

Describe permanent Afib?

Decision is made stop pursuing NSR

What are some of the modifiable risk factors of Afib?

Electrical, structural and autonomic remodeling

What are Afib therapy strategies?

1. Restoration of sinus rhythm vi drugs, surgery (MAZE), pacing, ablation, atrial defibrillator

2. rate control of ventricular response via drugs or AVN abaltion and pacemaker

What is the main cause of Afib sysmptoms?

RVR

What are factors of Maze III?

- >90% success

- 1-2% mortality

- RA and LA

- started in the 80s

- was originally open heart surgery

What was a complication of a focal PV ablation?

PV stenosis due to the heat causing the PV muscle to shrink

What is a common characteristic in those with persistant AF?

Some kind of remodeling has already taken place

What are the limitations of PV isolation only approach?

- poor success for persistent AF

- PV stenosis

- recurrent PV conduction

- non- PV triggers

What is the issue with a standardized Afib ablation approach?

May be more than necessary for some but insufficient in others

What are complications in AFib ablations?

Damage to

- phrenic, laryngeal nerves

- pulmonary veins

- esophagus

- coronary arteries

- MV

- Peri esophageal vagus

How far does resistive heating reach?

1-2mm diameter

How far does the heat from the ablation zone reach?

5-10mm diameter

What type of lesion is burned for VT?

Transmural lesion, burning from endocardium to epicardium

What does SOC mean?

Permanent tissue

What is used as a "half-normal" irrigant?

Saline

What is another name for dispersive patch?

Grounding pad

What is the advantage of bipolar ablation when compared to unipolar?

Reaches deeper myocardium because it uses 2 catheters instead of one

What are the advantages of using Hal normal saline as irrigant?

- decrease ion concentration or irrigant

- decrease osmolarity and charge density

- reduces dispersion of RF

- more current delivered to myocardial tissue

- deeper, larger lesion

Describe the anatomy of the pericardial space

- pericardium is 2x layered membrane

- visceral layer on epicardial surface

- parietal Ayer on outer fibrous layer

- pericardial space is between visceral and parietal layers

How much fluid does the pericardial space normally hold?

<50ml

What are factors in pericardial access?

- subxiphoid approach is the most common

- 17 Gauge Tuohy needle used

- puncture b/w left border or subxiphoid process and left rib cage

- anterior or posterior approaches

- contrast injection then gw

What are the main 2 sheaths used in pericardial access?

1. Cather

2. Draw fluid and GW

What are the landmarks for anterior access?

Lateral tricuspid annulus and anterior RV

What are the landmarks for posterior access?

Lateral mitral annulus, LAA, LV ant and lat wall, posterior LA and diaphragmatic surfaces of RV and LV

What are the EKG criteria to predict epicardial for those with ischemic CM ?

- delta wave >34ms

- instrinscoid deflection time >85ms

- RS complex duration >121ms

What % of patients have had ischemic CM?

64%

How can we predict an endocardial ablation?

When the patient with VT has never has an ablation before

How can we predict that we might perform an epicardial ablation?

If patient has had at least 2 unsuccessful VT ablations (both endocardial)

What are the EKG criteria to predict epicardial VT for those with NICM?

- absence of inferior Q-waves

- delta >75ms

- maximum deflection index of >0.59

- presence of Q wave in lead 1

List the probability of an epicardial circuit in different patient populations

- Normal 6%

- Ischemic 16%

- Non-ischemic 35%

- ARVC 41%

- Other CMP 18%

NINA!

What are the potential collateral injuries of the epicardial approach?

Phrenic nerves, coronary arteries, liver, colon, diaphragm, RV, pleural space, lungs

What is the prevalence of major and minor complications in the epicardial approach?

Major 4.1%

Minor 7.8%

What distance should the ablation catheter be from coronary arteries or it to be considered safe?

At least 5mm