8/9/2016 Disclosures Biosense-Webster International: investigator- - - PDF document

8/9/2016 1

1

NOVEL VT THERAPIES:

HIGH-INTENSITY ULTRASOUND AND LINEAR RF ABLATION

Cardiac Electrophysiology Fellow University of California San Francisco

Babak Nazer, MD

Assistant Professor of Medicine and Biomedical Engineering Oregon Health & Sciences University

Disclosures

• Biosense-Webster International: investigator-

initiated research grant

• The devices and technologies in this

presentation have not been FDA-approved for clinical use.

2

High-Intensity Ultrasound VT Ablation Catheter

3

Lamin A/C VT

4

8/9/2016 2

5 6

Epicardial scar in NICMP

7

Hutchinson MD, et al. Circulation Arrhythmia EP, 2011.

Septal scar in NICMP

8

Haqqani H, et al. Circulation Arrhythmia EP, 2011.

8/9/2016 3

NICMP VT ablation: Long-term outcomes

• 144 patients referred for VT ablation
• Endo: 67% recurrence at one year
• Endo-Epi: 64% recurrence at one year

9

Tung R, et al. Heart Rhythm, 2013.

NICMP VT ablation: Long-term outcomes

• 59 patients undergoing epicardial VT ablation

– Median follow-up 362 days

• 47% VT recurrence rate at one year

10

Schmidt, et al. Heart Rhythm, 2010.

11

Rationale for HIFU VT Catheter

Midmyocardial Epicardial (Non-ischemic)

Fat LAD

RF limitations:

1) Poor depth of penetration (5 mm) 1) Cannot ablate through epicardial fat or coronaries 2) Cannot reach deep septal substrate from either side

12

High-Intensity Focused Ultrasound

Lynn JG, et al. Journal of General Physiology 1942.

8/9/2016 4

Rationale for HIFU VT Catheter

• HIFU characteristic

– Spares immediately adjacent tissue – Side-facing – Deep penetration of acoustic energy

• Benefit

– Ablate through coronaries and epicardial fat – Avoid phrenic, pericardial, pulmonary injury – Ablate mid-myocardial VTs – Ablate septal VTs – Ablate epicardial VTs endocardially

13

Epicardial Catheter: Collaborators

• Vasant Salgaonkar, PhD
• Peter Douglas Jones, BS

14

Epicardial Catheter

• 12 Fr OD nylon catheter housing

A-mode imaging transducer HIFU ablation transducer Radiopaque

• rientation

marker Internal irrigation balloon

Epicardial In-Vivo Ablation

16

8/9/2016 5

Heart

Device position and aiming away from heart

Fluoroscopy A-mode US A-mode tracing M-mode processing Heart

Device position and aiming toward heart

Fluoroscopy A-mode US A-mode tracing M-mode processing

HIFU In-Vivo Ablation: Methods

• 8 swine ablated by HIFU, 5 by RF
• Epicardial HIFU sonications of left ventricle (LV)

performed at 15, 20 and 30W for 60 seconds

• RF ablations with ThermoCool SF at 30W, titrating

power to achieve >10 Ω impedance drop

19

Representative Lesions

20

Nazer B, et al. Circulation Arrhythmia EP, 2015. 10 mm

8/9/2016 6

Lesion Depth

21

*** p < 0.001 compared with RF

HIFU

*** *** ***

Lesion Volume

22

ns not significant, *** p < 0.0001 compared with RF

HIFU

ns *** ***

Epicardial Sparing

23

** p < 0.001, *** p < 0.0001 compared with RF

*** *** **

HIFU

HIFU Mean Lesion Sizes

24

RF 30W 20W 15W 5 mm Nazer B, et al. Circulation Arrhythmia EP, 2015.

8/9/2016 7

HIFU Coronary Ablation

• Over LCX (30 W) and LAD (20 W)

25

HIFU Coronary Ablation: LCX

26

10 mm 1 mm

250 μm

HIFU Coronary Ablation: LAD

27

10 mm

]

1 mm

HIFU Ablations in Scar

Gross infarct Epicardial map (0.5 – 1.5 mV) Endocardial map (0.5-1.5 mV)

8/9/2016 8

HIFU Lesions in Scar

29

Future of HIFU VT Ablation

• Endocardial use

– Decrease catheter caliber – Incorporate steerability

• Increase focusing (and thus coronary sparing)
• Commercialization & Regulatory Approval

– Industry Partner – Humanitarian Device Exemption

30

Linear RF Ablation Catheter

31

Linear ablation for scar-based VT

• 56 RF applications/patient
• 4.5 lines/patient

32

Marchlinski, et al. Circulation 2000.

8/9/2016 9

Substrate Modification / Scar Homogenization

• Mean procedure time 4.2 hours
• Mean RF time 68 minutes

33

Di Biase L, et al. JACC 2015.

Core Isolation of Scar

• Mean procedure time 5.4 hours
• Mean 111 RF applications per patient

34

Tzou WS, et al. Circulation EP 2015.

nMARQ Catheter

• 7 irrigated 3 mm RF ablation electrodes
• 5 mm spacing
• 25 W max power

35

Biosense-Webster International

LINEAR Catheter

• 7 irrigated 3 mm RF ablation electrodes
• 5 mm spacing
• 25 W max power

36

Biosense-Webster International

8/9/2016 10

Linear LV ablation

• LIN (nMARQ) – 7 swine

– 22 endo lines – 18 epi lines

• FOC (Thermocool) – 5 swine

– 7 endo lines (9.4 +/- 2.2 lesions/line) – 8 epi lines (8.0 +/- 1.4 lesions/line)

37

LIN vs FOC Ablation

38

B A FOC LIN

Ablation parameters

FOC LIN p-value Total RF time (s) 496.5 56.3 p < 0.0001 Irrigation volume (ml) 77.7 39.4 p < 0.0001 Power (W) 26.7 22.8 p < 0.0001 Impedance drop (Ω) 17.2 19.9 p = 0.049

Pre- and post-endo ablation

40

8/9/2016 11

Pre- and post- epi ablation

41

FOC lesion gaps

42

LIN FOC 1 cm

1 cm

LIN lesion histology

43

1 mm 1 mm

Linear Lesion Length

8/9/2016 12

Linear Lesion Volume Linear Lesion Depth Conclusions

HIFU Ablation

• Effective tool for:

– septal VTs – mid-myocardial VTs – Epicardial VTs (from endo)

• Catheter steerability and

greater focusing needed

• Industry partner needed

Linear RF Ablation

• Reduces procedure and

RF time

• Fewer gaps
• Improved steerability

may improve endocardial ablation

47

Acknowledgements

• Gerstenfeld Lab

– Tomos Walters – Srikant Duggirala – Qi Fang – Rich Sievers – Yasuaki Tanaka

48

• American Heart Association
• Biosense-Webster International
• Diederich Lab

– Vasant Salagaonkar – Peter Jones

8/9/2016 13

Supplementary Slides

49 LIN (857 points) Multi-spline (929 points) % difference Volume (ml) 178.7 217.5

• 17.8

Surface area (cm2) 181.6 214.9

• 15.5

Scar area < 1.5 mV (cm2) 57.5 72.3

• 20.5

Scar area < 0.5 mV (cm2) 20.2 28.2

• 28.4

Fractionated EGMs (%) 18.0 21.1

• 3.1

Late potentials (%) 1.5 2.6

• 1.1

Very late potentials (%) 0.43

• 0.43

A B

LIN (1141 points) Multi-spline (2277 points) % difference Volume (ml) 168.5 231.4

• 27.2

Surface area (cm2) 216.1 233.2

• 7.3

Scar area < 1.0 mV (cm2) 16.6 40.8

• 59.3

Fractionated EGMs (%) 15.2 9.7 +5.5 Late potentials (%) 3.2 3.0 +0.2 Very late potentials (%) 0.3 0.4

• 0.1

A B