Defibrillators, Implantable, Pediatrics
Conditions
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.
Interventions
DIAGNOSTIC_TESTDefibrillator 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.
OTHERObservation 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.
Sponsors
Boston Children's Hospital
Study design
Observational model
COHORT
Time perspective
PROSPECTIVE
Eligibility
Sex/Gender
ALL
Healthy volunteers
No
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
Design outcomes
Primary
| Measure | Time frame | Description |
|---|---|---|
| Defibrillation Threshold | 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
| Measure | Time frame | Description |
|---|---|---|
| Do DFTs Vary by Type of ICD Systems Implanted? | 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). |
| Intrinsic Heart Rate in the Immediate Post-defibrillation Period | 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. |
Countries
United States
Participant flow
Participants by arm
| Arm | Count |
|---|---|
| Pediatric ICD Pts Inclusion criteria: 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).
Defibrillator threshold testing: Measurement of the defibrillation threshold was performed using a modified binary search protocol. This protocol specified three distinct inductions of ventricula | 20 |
| Total | 20 |
Baseline characteristics
| Characteristic | Pediatric ICD Pts |
|---|---|
| Age, Continuous | 16 years |
| Anti-arrhythmic medications at testing Amiodarone | 2 participants |
| Anti-arrhythmic medications at testing Beta-blocker | 13 participants |
| Anti-arrhythmic medications at testing Calcium-channel blocker | 3 participants |
| Anti-arrhythmic medications at testing Other | 3 participants |
| Cardiac diagnosis Cardiomyopathy | 4 Participants |
| Cardiac diagnosis Channelopathy | 11 Participants |
| Cardiac diagnosis Congenital heart disease | 5 Participants |
| ICD system configuration Nontransvenous | 8 Participants |
| ICD system configuration Transvenous | 12 Participants |
| Indication for defibrillation threshold testing Generator change | 5 Participants |
| Indication for defibrillation threshold testing Lead revision | 5 Participants |
| Indication for defibrillation threshold testing New implant | 7 Participants |
| Indication for defibrillation threshold testing Surveillance | 3 Participants |
| Location of high-voltage coil Pericardial | 6 Participants |
| Location of high-voltage coil Pleural | 1 Participants |
| Location of high-voltage coil Subcutaneous | 1 Participants |
| Location of high-voltage coil Transvenous single coil | 7 Participants |
| Location of high-voltage coil Transveous dual coil | 5 Participants |
| Region of Enrollment United States | 20 Participants |
| Sex: Female, Male Female | 7 Participants |
| Sex: Female, Male Male | 13 Participants |
| Weight (kg) | 48 kilograms |
Adverse events
| Event type | EG000 affected / at risk |
|---|---|
| deaths Total, all-cause mortality | 0 / 20 |
| other Total, other adverse events | 0 / 20 |
| serious Total, serious adverse events | 0 / 20 |
Outcome results
Primary
Defibrillation Threshold
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.
Time frame: During clinical ICD procedure, as a single event
| Arm | Measure | Value (MEDIAN) |
|---|---|---|
| Pediatric ICD Pts | Defibrillation Threshold | 7 Joules |
Secondary
Do DFTs Vary by Type of ICD Systems Implanted?
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).
Time frame: During clinical ICD procedure, as a single event
| Arm | Measure | Value (MEDIAN) |
|---|---|---|
| Pediatric ICD Pts | Do DFTs Vary by Type of ICD Systems Implanted? | 7 Joules |
| Non-transvenous ICDs | Do DFTs Vary by Type of ICD Systems Implanted? | 6 Joules |
Secondary
Intrinsic Heart Rate in the Immediate Post-defibrillation Period
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.
Time frame: During clinical ICD procedure, as a single event
Population: Post-defibrillation episodes in which intrinsic rhythm was evaluable and pacing was necessary
| Arm | Measure | Value (NUMBER) |
|---|---|---|
| Pediatric ICD Pts | Intrinsic Heart Rate in the Immediate Post-defibrillation Period | 0 episodes |