Comparison of VF Induction Techniques During Medtronic ICD Implant (VF) (ICD) (VF)

Comparison of Ventricular Fibrillation Induction Techniques During Medtronic Implantable Cardioverter Defibrillator Implant

As the indications for Implantable Cardioverter Defibrillator implantation expand, minimizing implant time is critical. Also, patients receiving biventricular ICDs are sometimes more unstable and minimization of sedation time is crucial. Multiple induction attempts, with a 1-Joule shock, can cause disruption in lead position. Therefore limiting the number of attempts will allow for better lead stability throughout the procedure and a more straightforward implant process.

Investigator proposes a detailed documentation of success rates from various Ventriculart Fibrillation induction methods during implant of Medtronic defibrillation capable devices.

Study Overview

• Status: Completed
• Conditions: Cardiomyopathy
• Intervention / Treatment: Device: Nominal T shock setting; Device: Educated T shock setting

Detailed Description

Our clinical experience has found that attempts to induce patients receiving ICDs at implant using the nominal Medtronic T-shock settings are not always effective at inducing ventricular fibrillation. When this results, a change to the parameters for T-shock is made before reattempting to induce ventricular fibrillation in patients undergoing ICD implantation.

Another available induction method is 50 Hz Burst. "The 50 Hz Burst induction is designed to induce VF by delivering a rapid burst of pacing pulses. The amplitude and pulse width of these pulses are selectable, but the pacing interval is fixed at 20 ms."2 If multiple attempts using the T-shock method are unsuccessful, 50 Hz Burst provides an additional method for inducing ventricular fibrillation. It is a less desirable method since it can result in very fine VF that is difficult to identify the initiation of possibly resulting in longer times in VF causing higher defibrillation threshold or in undersensing due to the fine nature of the rhythm.

T-shock has been found to be a fast and reliable method for inducing ventricular fibrillation in ICD implants. Greater success of inducing ventricular fibrillation using the T-shock method has been found when the energy of the T-shock was higher and the coupling interval was shorter. In addition, increasing the shock strength increases the window of vulnerability. For the T-shock method to be most efficient, initial success at inducing ventricular fibrillation, and therefore a reduced number of attempts, is important. This requires a better understanding of the optimal programmed settings for the initial T-shock induction attempt.

Moreover, in recent years, ICD indications have grown to include primary prevention patients. These patients may have different vulnerable periods than patients previously evaluated to develop Medtronic nominal settings.

Our clinical experience has found that the nominal T-shock settings are only effective at inducing ventricular fibrillation approximately seventy-five percent of the time. However, a detailed collection of success rates has not been performed.

• Study Type: Interventional
• Enrollment (Actual): 100
• Phase: Not Applicable

Contacts and Locations

Study Locations

• United States
  • Tennessee
    • Kingsport, Tennessee, United States, 37660
      • Wellmont CVA Heart Institute

Participation Criteria

Eligibility Criteria

• Ages Eligible for Study: 18 years and older (Adult, Older Adult)
• Accepts Healthy Volunteers: No
• Genders Eligible for Study: All

Description

Inclusion Criteria:

• All patients undergoing Medtronic ICD or Cardiac Resynchronization Therapy-Defibrillator implant (initial implant or generator replacement) will be included.

Exclusion Criteria:

• Any patient who is medically unstable and testing is deemed unsafe by physician will be excluded from this study.

Study Plan

How is the study designed?

Design Details

• Primary Purpose: Treatment
• Allocation: Randomized
• Interventional Model: Parallel Assignment
• Masking: None (Open Label)

Number of Arms

2

Arms and Interventions

Participant Group / Arm	Intervention / Treatment
Active Comparator: Nominal Parameter; Nominal T shock setting	Device: Nominal T shock setting; Nominal Parameter Set 1 Programming Values for EnTrust; Other Names: Medtronic ICDs
Experimental: Experimental Parameter; Educated T shock setting	Device: Educated T shock setting; Experimental Parameter Set 2 Programming Values; Other Names: Medtronic ICDs

What is the study measuring?

Primary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Sustained Ventricular Fibrillation	The primary endpoint is the successful induction of sustained ventricular fibrillation.	2 hours

Secondary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Factors	Determine if any pre-implant patient demographics are factors impacting T-shock success according to parameter settings.	2 hours

Other Outcome Measures

Outcome Measure	Measure Description	Time Frame
Safety Monitoring	Number of participants that were monitored for safety issues, including increased heart rate, blood pressure, decreased oximetry levels, and stable rhythm during the entire procedure.	2 hours

Collaborators and Investigators

• Sponsor: James Merrill
• Collaborators: Medtronic

Publications and helpful links

General Publications

• Bardy G, Mehra R, Johnson G, Kudenchuk P, Dolack G, Poole J, Hofer B: Low energy pulsing on the T-wave: A new programming method for intentional, device mediated induction of ventricular fibrillation for defibrillation testing. PACE 15(4, Pt II): 562, 1992.
• Bhandari AK, Isber N, Estioko M, Ziccardi T, Cannom DS, Park Y, Lerman RD, Prejean C, Sun GW. Efficacy of low-energy T wave shocks for induction of ventricular fibrillation in patients with implantable cardioverter defibrillators. J Electrocardiol. 1998 Jan;31(1):31-7. doi: 10.1016/s0022-0736(98)90004-8.
• Marquis DR Reference Manual, Medtronic, Inc.
• Mitchell L, Yee R, Talajic M, Newman D, Sheldon R, Kerr C, Kus T, Boyle A, Canadian Jewel PCD Investigators: Low-energy, T-wave synchronous, interval shock for rapid, reliable ventricular fibrillation induction by an implantable cardioverter defibrllattor. PACE, 17(4, Pt II): 851, 1994.
• Swartz J, Stanton M, DeGroot P, Mehra R: Influence of T-wave shock energy on ventricular fibrillation vulnerability in humans. JACC 1995 Conference Abstracts: 214A, 1995.

Study record dates

Study Major Dates

• Study Start: January 1, 2011
• Primary Completion (Actual): August 1, 2012
• Study Completion (Actual): August 1, 2012

Study Registration Dates

• First Submitted: December 31, 2013
• First Submitted That Met QC Criteria: January 2, 2014
• First Posted (Estimate): January 6, 2014

Study Record Updates

• Last Update Posted (Actual): May 22, 2018
• Last Update Submitted That Met QC Criteria: April 23, 2018
• Last Verified: April 1, 2018

More Information

Terms related to this study

• Keywords: Defibrillators; Ventricular Fibrillation Induction Testing
• Additional Relevant MeSH Terms: Pathologic Processes; Heart Diseases; Cardiovascular Diseases; Arrhythmias, Cardiac; Ventricular Fibrillation; Cardiomyopathies
• Other Study ID Numbers: VF Induction

Plan for Individual participant data (IPD)

• Plan to Share Individual Participant Data (IPD)?: NO