Mapping and Ablation of VT Speakers Bureau / Honoraria: - - PowerPoint PPT Presentation

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Mapping and Ablation of VT Speakers Bureau / Honoraria: - - PowerPoint PPT Presentation

Feb 13, 2024 276 likes •407 views

9/8/2012 Disclosure-of-Relationship Mapping and Ablation of VT Speakers Bureau / Honoraria: Biosense-Webster, in The Operating Room Medtronic, St Jude Medical, Acuson, Siemens, Boston Scientific Sanjay Dixit, M.D. Associate Professor,

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9/8/2012 1

Mapping and Ablation of VT in The Operating Room

Sanjay Dixit, M.D. Associate Professor, University of Pennsylvania School of Medicine Director, Cardiac Electrophysiology Laboratory, Philadelphia V.A.M.C.

Disclosure-of-Relationship

Speakers’ Bureau / Honoraria: Biosense-Webster, Medtronic, St Jude Medical, Acuson, Siemens, Boston Scientific Grant: Boston Scientific, Biosense-Webster, Medtronic

Special Disclosure

Ed, The Party Animal

Surgical VT Ablation: Historical Perspective

Resection of dyskinetic / akinetic scar: Aneurysmectomy (success ~40%) Sub-endocardial resection ± Aneurysmectomy (success ~90%) Sub-endocardial resection guided by mapping in OR: epicardial sock, intracardiac basket, bipolar catheters Advent of ICD therapy & Catheter based ablation

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SLIDE 2

9/8/2012 2

Surgical VT Ablation: Current Indications

  • Treatment of last resort for patients who have failed multiple

catheter ablation attempts.

  • PENN experience: over a 3 year period (2007 – 2009), 527 patients

underwent VT ablation – 295 patients (56%) had structural heart disease (non-ischemic substrate in 144; 49%); 8 of these patients (1.5%) needed surgical ablation.

  • All 8 patients has non ischemic cardiomyopathy: 6 with dilated

cardiomyopathy and 2 with hypertrophic cardiomyopathy.

Patient # Age (yrs) Sex LVEF (%) NICM ICD

1 65 M 15 Yes Yes 2 50 M 70 Yes Yes 3 54 M 58 Yes Yes 4 51 F 25 Yes No 5 51 M 30 Yes Yes 6 74 M 30 Yes Yes 7 74 M 50 Yes Yes 8 48 M 40 Yes Yes

MRI identified septal scar in 3 patients; clinical VT was localized to thickened basal septum (>20 mm) in 2 of these subjects

RV LV

Inferior Apical Scar Mid Septal Scar Inferior Basal Scar Anterior Septal Scar

Intraseptal VT Substrate: MR Imaging

Intra-Septal VT Substrate

Trans Thoracic Intra Cardiac

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SLIDE 3

9/8/2012 3 ECG Features of VT originating from basal IVS

Left bundle block with early precordial transition (V1 – V2) Right bundle block with unusual precordial transition

  • Endocardial mapping was performed in all (LV in 8, RV in 4);

epicardial mapping was performed in 6.

  • A total of 24 VTs (spontaneous / induced) were observed.
  • At conclusion of percutaneous ablation, in 4 patients no VT was

inducible, in 3 patients clinical VT remained inducible and 1 patient developed RV perforation requiring urgent surgery.

  • In all 4 patients that were non-inducible, ≥1 targeted VT recurred

within a week of the last percutaneous ablation.

Cardiac Access for Surgical VT ablation

Median Sternotomy provides best cardiac visualization: RV epicardium Superior IV Septum Anterior LV wall To visualize posterolateral LV wall, heart has to be physically lifted. Partial sternotomy can allow visualization of RV, anterior and inferior LV surfaces.

Trans-Aortic View: Basal LV

Plane of Aortic Transaction LCC NCC RCC AML

Anterior Posterior Superior Inferior

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SLIDE 4

9/8/2012 4

  • Trans-mitral approach: This offers best visualization of both

papillary muscles, posterior LV endocardium and LV apex.

  • LV Apical approach: In patients with mechanical aortic and mitral

valves.

  • Aneurysmectomy site: Access to LV can be obtained through this

location prior to aneurysm resection and closure.

  • Accessing RV: Either via the tricuspid valve or the RV free wall.
  • Other approaches for epicardial access only: Partial sternotomy,

window via epigastric incision, left anterior thoracotomy.

Surgical Ablation: Alternative Approaches

  • Finger mounted “roving” electrode: This was used for mapping

critical components of the VT circuit in the early era of surgical ablation.

  • Multipolar mesh / Basket catheter: High resolution so can

provide comprehensive activation sequences; require special set-up for signal processing so cumbersome to use.

  • Electro-anatomic mapping: Needs special set up – creation of

magnetic field, reference catheter (usually sutured to RV or LV epicardium).

VT Mapping in the OR

  • A priori detailed endocardial and when indicated, epicardial

mapping performed in the EP laboratory.

  • Activation, entrainment and electro-anatomic mapping performed

to identify critical components of VT circuit / site of origin vis-à- vis the underlying substrate.

  • These locations were targeted by conventional RF energy.
  • In the OR, these RF lesions were identifiable (especially

endocardial) and served as targets for cryo-thermy applications.

Mapping in EP Lab prior to Surgical Ablation: PENN Approach Epicardial View

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SLIDE 5

9/8/2012 5

Trans-Aortic View

Plane of Aortic Transaction LCC NCC RCC AML

Anterior Posterior Superior Inferior

RFA Lesion (old)

Trans-Aortic View

Anterior Posterior Superior Inferior

LCC NCC RCC

RAA RV & RVOT

RFA Lesion (recent)

Surgical VT Ablation: Lesion Creation

LV RV APEX BASE LAA

BASE APEX SEP LAT

Surgifrost™ Surgical Cryoablation System (Medtronic CryoCath LP, Quebec, Canada): The system uses Argon gas and can cool to -150 °C. It utilizes flexible metal probe with adjustable insulation sheath. The standard duration of cryo-application is for a maximum of 3 minutes (cooling and thawing phases) and can create large lesions (~ 60 mm). Best results are achieved under cold cardioplegia which ensures adequate freezing.

Trans-Aortic Deployment of Cryo Probe

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SLIDE 6

9/8/2012 6

  • Surgical approach utilized median sternotomy with cardio-

pulmonary by pass under cold cardioplegia.

  • The epicardial and endocardial (via trans-aortic approach) surfaces

were inspected and previously placed radiofrequency ablation lesions were identified. No additional mapping was performed in the OR.

  • Cryothermy (Surgifrost, Medtronic CryoCath LP) was applied to

sites manifesting old lesions and / or scar identified in and around critical sites (temperature -150 °C; total application time 3 minutes; anticipated lesion of 60 mm); additional cryo application on the

  • pposing surface.

Cryo Ablation: Final Result

Lesion Creation in OR: Other Energy Sources

  • Radiofrequency energy: Infrequently used for surgical VT

ablation; may not be as effective in cooled hearts.

  • Laser energy (Nd-YAG, pulsed Argon): Have been used for

surgical VT ablation in the past with excellent results; unclear why this modality is no longer used.

  • Microwave technology: Has also been shown to be effective for

lesion creation during surgical VT ablation.

  • Cryo-thermy: Remains the most common energy source for

surgical VT ablation

Surgical VT Ablation: Acute End-points

  • In cases where mapping / ablation are performed during ongoing VT,

arrhythmia termination and non-inducibility should be the criteria.

  • In cases where cold-cardioplegia is used during surgical ablation, heart

requires rewarming in order to assess inducibility. VT induction can be influenced by deep sedation, anesthetic agents, cardiac filling, etc.

  • Other challenges: In patients undergoing concomitant valve or by-pass

surgery and/ or experiencing de-compensation during surgical VT ablation, induction not advisable; lack of standard 12 lead ECG in OR may preclude localization.

  • Surrogates of substrate modification: non-capture, conduction block, etc.
  • Delayed (pre-discharge) assessment of VT inducibility.
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9/8/2012 7

Surgical VT Ablation: Long-term Outcomes

  • Best long-term follow-up data: Patients who underwent surgical

VT ablation in the setting of healed myocardial infarcts: 1-year survival of 80-90% but by 5th year 25% patients had died.

  • PENN surgical VT Experience: All patients (n=8) had non-

ischemic cardiomyopathy; 2 patients died during the hospitalization following ablation; in remaining 6 patients over a mean follow-up 23±6 months, 4 patients were free of VT, 1 patient had single VT episode resulting in shock and 1 patient had 3 VT events in the first 3 months post-ablation but none after.

Patient # Time from surgery to discharge (days) NIPS pre- discharge

  • No. of AADs at

discharge

  • No. of ICD

shocks

1 11 Not performed 2 (Quinidine, Mexiletine) 3 2 5 Non-inducible 1 (Sotalol) 3 8 Not performed 4 Died N/A N/A N/A 5 7 Non-inducible 1 (Amiodarone) 6 Died N/A N/A N/A 7 6 Non-inducible 1 (Sotalol) 8 7 MMVT Inducible 1 (Mexiletine) 1

Surgical VT Ablation: Future Developments

  • Ability to consistently induce and map VT in the OR

setting using the same tools as in the EP Lab: Hybrid OR.

  • Development of energy sources that can create effective

lesions without need for cold cardioplegia.

  • Ability to map and ablate ventricular arrhythmias using a

less invasive approach similar to what has been accomplished with surgical AF ablation.

Surgical VT Ablation: Conclusions

  • Surgical ablation remains the treatment of last resort in

patients experiencing VT that is refractory to conventional ablation.

  • Ability to create large cryo lesions in the OR typically

under cold cardioplegia is the key to success of surgical VT ablation

  • Although mapping in the OR is ideal, a priori mapping and

RF lesions in the EP lab can also guide surgical ablation

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9/8/2012 8

Ed, we miss you at PENN…………

Visually Identification of Scar:

  • Infero-basal LV
  • Lateral LV

LV RV APEX BASE LAA

BASE APEX SEP LAT

Epicardial Deployment of Cryo Probe

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9/8/2012 9

Patient # Time from last RFA to surgery (months) Energy used Use of cardioplegia Other procedure performed

1 Cryotherapy Yes Mitral valve repair 2 Cryotherapy No None 3 Cryotherapy Yes Maze 4 Cryotherapy Yes Mitral and Tricuspid valve repair 5 3 Cryotherapy Yes None 6 Cryotherapy Yes None 7 Cryotherapy No Repair of perforation in RV wall 8 Cryotherapy Yes None

Patient # Clinical arrhythmia

  • No. failed

AADs

  • No. ICD shocks

in preceding 3 months

  • No. of prior

endocardial procedures

  • No. of prior

epicardial procedures

1 SMVT 3 8 1 2 SMVT 2 3 1 1 3 SMVT 3 3 2 2 4 SMVT 1 1 external shock 1 1 5 SMVT 2 12 1 2 6 SMVT 3 16 3 1 7 SMVT 2 6 2 8 SMVT 2 4 3 1

Surgical VT Ablation: Case Summary

Patient #

  • No. of

Induced VT Endocardial Localization Epicardial Localization Endocardial RF Lesions Epicardial RF Lesions VT mapping/target identification Inducible at end of most recent procedure

1 1 1/1 N/A 28 N/A AM\EM\PM\LP No 2 2 0/2 2/2 15 PM\LP No 3 2 1/2 2/2 41 37 AM\EM\PM\LP Yes 4 4 2/4 1/4 12 18 AM\EM\PM\LP No 5 2 1/2 1/2 21 52 EM\PM\LP No 6 8 8/8 8/8 182 53 PM\LP Yes 7 1 0/1 PM\LP N/A *urgent surgery 8 4 4/4 4/4 114 PM\LP Yes

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9/8/2012 10

Epicardial View

Trans-Aortic View: Further Retracting AML

Depth Area Volume

4-mm 6-mm 8-mm 4-mm 6-mm 8-mm 4-mm 6-mm 8-mm

  • Rivard, Khairy et al, Heart Rhythm 2008;5:230
  • Catheter adhesiveness,
  • Sharply demarcated lesion,
  • Preservation of ultrastructure,
  • Reversible suppression,
  • Lesion limited by warming blood,
  • Pain free

Cryothermal Ablation

Limitations of conventional lesion creation

  • Diffuse
  • Intramural /

Epicardial

  • Heterogeneous
  • Close to critical

structures

Hallmarks of Nonischemic Substrate

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9/8/2012 11

Radiofrequency Ablation

Endocardial Lesion Epicardial Lesion

Lesion Creation in Epicardial Scar

Limitations of conventional lesion creation