Takashi Nitta

Cardiovascular Surgery, Nippon Medical SchoolTokyo, JAPAN

Map-Guided Ablation of Non-ischemic VT

Declaration of Interestnothing

Catheter Ablation of Non-ischemic VT

4 Tokuda M, Stevenson WG, et al. Circ Arrhythm Electrophysiol. 2012;5:992-1000

DCM, 119, 53%

Valvular, 34, 15%

ARVC, 37, 16%

Congenital, 16, 7%

Sarcoidosis, 13, 6% HCM, 7, 3%

Surgery for Non-ischemic VT

5

Number of patients (2000-2017) 34

Age (range, median; year) 1-79, 59

Gender (male : female) 27:7

LVEF (%) 49±11

Indication for Surgery

Refractory VT 34 (100%)

Incessant VT/ICD shocks (storm) 11 (32%)

Cardiac Tumor 6

Heart Failure 2

HCM, 16, 47%Other CM, 8, 23%

Cardiac Tumor, 6, 18%

Post-OP for CHD, 2, 6%

ARVC, 1, 3%Sarcoidosis, 1, 3%

Underlying Heart Disease (n=34)

Preoperative Therapies

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Preoperative TherapiesAnti-arrhythmic Drugs 34 (100%)

Number of drugs (range, median) 1-8, 3Defibrillators 17 (52%)

ICD/CRTD/WCD 14/2/1RFCA (endo- or epicardial) 28 (85%)

Number of sessions (range, median) 1-8, 2Epicardial ablation 9 (27%)

What is difficult in Catheter Ablation of VT in HCM patients?

1. Epicardial or intramural focus or substrate

2. Thick myocardium that hampers transmural ablation

3. Epicardial fat that diminishes ablation energy conducting to myocardium

4. A focus adjacent to or beneath the major coronary vessels

Surgical Strategy and Procedures

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Map-guided procedure in all (N=34)Preoperative endo- and epicardial mappingIntraoperative mapping (N=30, 88%)

Surgical Procedure1. HCM (N=16), Other cardiomyopathy (N=8)

Transmural cryothermia at VT focus or substrate

2. Cardiac tumor (N=6) Resection of tumor with cryoablation (N=4) Encircling cryo-isolation of tumor (N=2)

Intraoperative Electro-anatomical Mapping (CARTO)

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Location pad

Effective magnetic FieldCatheter electrode

Nitta T, et al. Ann Thorac Surg 2012;93:1285-8.

LV Thickness at VT focus in HCM Patients

10TTE (short axis view of LV base)

15.2±1.5 mm(N=7)

0

5

10

15

20

RF Cryothermia(Nitrous oxide)

Epi and Endocardial Bi-directional Ablation Required

VT Focus

How to Create a Transmural Lesion

LV Apex Cryoprobes

Simultaneous Epi- and Endocardial Cryoablation through a Ventriculotomy

Endocardial Cryoablation through an Aortotomy to avoid a ventriculotomy

Asc. Ao

Cryoprobe

LV Summit VT

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Originates from high lateral LV bounded by LAD, LCX, and AIV

Epicardial ablation is hampered by1. Major coronary vessels

2. Thick LV mass

3. Thick epicardial fat

AIV: Anterior Interventricular Vein

A 31-year-old man with palpitation Clinical Course

• First episode of palpitation developed in 2009.1 at the age of 24 and underwent endocardial catheter ablation of VT.

• In 2016.4, the VT recurred and he underwent 2nd session of endocardial ablation with partial success. Sustained VT was suppressed by oral beta-blocker and amiodarone, but PVC bigeminy continued for all day.

No particular family history or past history Normal Echocardiogram and normal CAG

Sustained VT and PVC Bigeminy

Inf. Axis + RBBB MorphologyHR =220 bpm

CAG and Pace Map from Distal CSPVC

Distal CS Pacing

RAO

LMTLAD

LCX

CS

AIV

AIV: Anterior Interventricular Vein

Intra-OP Epicardial Activation Maps

RAO LAO

Earliest activation site

1. Taping LAD and LCX proximally

2. Removal of fat over VT origin using ultrasonic scalpel

3. Cryothermia directly applied at the VT origin for 2 mins at -60℃

Dissection of Coronary Arteries and Epicardial Fat followed by Epicardial Cryoablation

1. LV endocardial cryoablation across the aortic valve

2. The ablation site was directed by the needle punctured at the epicardial earliest activation site.

Cryothermia at the LV Endocardium just underneath the Epicardial Earliest Activation Site

LADLCX

AIV

RCCLCC

What is Essential in Surgical Ablation of VT in HCM Patient?

1. Three-dimensional localization of focus or substrate

2. Transmural ablation

3. Avoidance of injuries to the major coronary vessels

Case 2 (HCM VT)

74-year-old male patient

Undergone 2 sessions of endocardial RFCA and implanted with an ICD for refractory VT associated with HCM.

Chemical ablation with intra-coronary alcohol was performed for incessant VT with frequent ICD shocks (VT storm).

Referred for surgical treatment of recurrent VT.

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Two morphologies of VT

III

aVF

V5

III

V2

aVRaVL

V4

V6

V1

V3

TCL:400msecLBBB + inferior axis

VT #1 VT #2

TCL:320msecRBBB + inferior axis21

Pre-OP Epicardial Voltage MappingLAO cranial LPO cranial

PA

RVOT

Ao

LADMA

LCXOM

Ao

22

VT #1 VT #2

Pre-OP Epicardial Activation Mapping

LAD

RVOT

PA

Ao

LCX

MA

23

LAD

OM

VT #1 VT #2

Intra-OP Epicardial Activation Mapping

LADRVOT

PA

Ao LPO

LAD

LCX

LAAOM

LCA

Epicardial cryoablation after removing fat tissue using the Harmonic scalpel

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Cryoprobe

LV Apex

LAD

LCX

LAD

LCXPA

LV Summit VT: Location of Focus

26

⑧⑦

⑥

②③

③

④

④⑤ ①

Survival after Surgery for Non-ischemic VT (N=34)

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Months after Surgery

0

0.2

0.4

0.6

0.8

1

0 12 24 36 48 60 72 84 96 108120132144156168180

No operative deathOne late death (CHF) 16 months post-OP

Freedom from Clinical and Non-clinical VT

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0

0.2

0.4

0.6

0.8

1

0 1825 3650Days after Surgery

0

0.2

0.4

0.6

0.8

1

0 30 60 90

Clinical VT in 2 Non-clinical VT in 4

Summary1. Refractory VTs associated with cardiomyopathy, cardiac

tumors, or others are indicated for surgery and the results are satisfactory.

2. Pre- and intra-operative mapping is essential for precise and three-dimensional localization of VT substrate and successful surgical ablation.

3. Transmural ablation with epi- and endocardial cryothermia is crucial to ablate intramural substrate.

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