Precise Measurement of Pediatric Defibrillation Thresholds

The safety and scientific validity of this study is the responsibility of the study sponsor and investigators. Listing a study does not mean it has been evaluated by the U.S. Federal Government. Read our disclaimer for details. Identifier: NCT01043562
Recruitment Status : Completed
First Posted : January 7, 2010
Results First Posted : February 5, 2018
Last Update Posted : February 5, 2018
Information provided by (Responsible Party):
Andrew Eric Radbill, Boston Children’s Hospital

Brief Summary:
Patients who receive an implantable cardioverter-defibrillator (ICD) usually undergo testing at the end of the ICD procedure to measure the amount of energy able to successfully defibrillate the heart (defibrillation threshold testing, or DFT). This study proposes to perform that measurement in pediatric patients already undergoing clinically necessary ICD procedures, with the measurement performed using a binary search method that has been previously validated in adult cohorts. We hypothesize that pediatric DFTs, when precisely measured, may be lower than previously assumed from extrapolation of adult data.

Condition or disease Intervention/treatment
Pediatrics Defibrillators, Implantable Diagnostic Test: Defibrillator threshold testing Other: Observation of post-shock intrinsic cardiac rhythm

Study Type : Observational
Actual Enrollment : 20 participants
Observational Model: Cohort
Time Perspective: Prospective
Official Title: Defibrillation Thresholds in a Pediatric Cohort Using Binary Search Protocol
Actual Study Start Date : June 4, 2009
Actual Primary Completion Date : May 26, 2010
Actual Study Completion Date : May 10, 2012

Resource links provided by the National Library of Medicine

MedlinePlus related topics: Shock

Group/Cohort Intervention/treatment
Pediatric ICD pts
Inclusion criteria for study participants included: 1) weight ≤60 kg, 2) new or existing ICD system, and 3) clinically necessary assessment of the defibrillation efficacy of the ICD system. Transvenous systems utilized a high-voltage ICD coil with active-fixation lead attached to the right ventricular endocardial surface, whereas non-transvenous systems depended upon a high-voltage shocking coil placed within the pericardial, subcutaneous or pleural space. To be included in the post-shock pacing portion of the study, adequate sinus and AV node function had to be present at baseline. Exclusion criteria included 1) tenuous hemodynamic status felt to warrant abbreviation of the defibrillation efficacy testing or 2) inability to induce fibrillation during defibrillation threshold testing (DFT).
Diagnostic Test: Defibrillator threshold testing
Measurement of the defibrillation threshold was performed using a modified binary search protocol. This protocol specified three distinct inductions of ventricular fibrillation (VF) for all subjects, with a 3-5 minute observation/waiting period between inductions. The initial shock energy was programmed at 9 joules (J) for all patients, with internal rescue shocks at 31J followed by device-specific maximum deliverable energy. The outcome of the initial induction determined the programmed energies for both the initial and internal rescue shocks for the second induction, and likewise for the third induction. All shocks were biphasic and delivered at manufacturers' default tilt, polarity and duration, and all final programmed shock vectors included an active can. External defibrillation pads were in place for delivery of external rescue shock should the internal shocks fail.

Other: Observation of post-shock intrinsic cardiac rhythm
Prior to each of the three ventricular fibrillation inductions performed as part of the binary search protocol, post-shock pacing was re-programmed using a pre-determined, stepwise protocol that progressively decreased the lower rate limit. For the purpose of this protocol, post-shock pacing was considered necessary if 1) ≥7 ventricular-paced beats or 2) asystole >4 seconds was observed in the first 20 seconds after defibrillation, or if the systolic blood pressure demonstrated a >10% decrease from pre-induction baseline at follow-up measurement 1 minute post-defibrillation. Rescue ventricular pacing via the programmer was available for all subjects.

Primary Outcome Measures :
  1. Defibrillation Threshold [ Time Frame: During clinical ICD procedure, as a single event ]
    The defibrillation threshold is a measure of the minimum amount of energy (in Joules) that is able to successfully defibrillate an episode of ventricular fibrillation. This measurement is specific to each individual patient with his/her specific defibrillator configuration. There are several different strategies to measuring this in an individual patient; this study utilized the binary search protocol.

Secondary Outcome Measures :
  1. Do DFTs Vary by Type of ICD Systems Implanted? [ Time Frame: During clinical ICD procedure, as a single event ]
    The defibrillation threshold (as measured in Joules as already described in the details regarding the primary outcome) will be compared between patients with two distinct general types of implanted defibrillator systems: 1) transvenous ICD systems (defibrillator leads located inside the vein and attached to the endocardial surface of the heart) and 2) non-transvenous ICD systems (including all other types of debrillation systems).

  2. Intrinsic Heart Rate in the Immediate Post-defibrillation Period [ Time Frame: During clinical ICD procedure, as a single event ]
    A patient will be considered to have an intrinsic slow heart rate in the period of time immediately following defibrillation (20 seconds) if any of the following are observed: >7 paced beats, asystole >4 seconds, or experienced >10% decrease in systolic blood pressure.

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Ages Eligible for Study:   Child, Adult, Older Adult
Sexes Eligible for Study:   All
Accepts Healthy Volunteers:   No
Sampling Method:   Non-Probability Sample
Study Population
All patients seen by the electrophysiology service at Children's Hospital Boston who are identified to be at very high risk of sudden cardiac death and in need of an ICD

Inclusion Criteria:

  • Current follow-up at Children's Hospital Boston
  • Children with current or planned ICDs who are scheduled by their primary electrophysiologist for clinically necessary assessment/re-assessment of defibrillation threshold
  • If the patient has an ICD system with a non-transvenous shock coil: weight ≤35kg at time of initial implant, with current weight <50kg
  • If the patient has an ICD system with a conventional transvenous shock coil: current weight ≤60kg

Exclusion Criteria:

  • Clinical failure of any system component not able to be addressed by hardware repair or exchange
  • Hemodynamic instability that in the judgment of the primary electrophysiologist warrants abbreviation of DFT assessment
  • Unsuccessful induction of fibrillation during DFT testing

Information from the National Library of Medicine

To learn more about this study, you or your doctor may contact the study research staff using the contact information provided by the sponsor.

Please refer to this study by its identifier (NCT number): NCT01043562

United States, Massachusetts
Children's Hospital Boston
Boston, Massachusetts, United States, 02115
Sponsors and Collaborators
Boston Children’s Hospital
Principal Investigator: Andrew E Radbill, MD Boston Children’s Hospital

Responsible Party: Andrew Eric Radbill, Assistant Professor of Pediatrics, Boston Children’s Hospital Identifier: NCT01043562     History of Changes
Other Study ID Numbers: 09-04-0209
First Posted: January 7, 2010    Key Record Dates
Results First Posted: February 5, 2018
Last Update Posted: February 5, 2018
Last Verified: July 2017
Individual Participant Data (IPD) Sharing Statement:
Plan to Share IPD: No

Studies a U.S. FDA-regulated Drug Product: No
Studies a U.S. FDA-regulated Device Product: No