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

Study Overview
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Brief Summary
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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.

Detailed Description
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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.

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

Conditions
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Cardiomyopathy

Intervention / Treatment
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* Device: Nominal T shock setting
* Device: Educated T shock setting


Participation Criteria
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Eligibility Criteria
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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.

Ages Eligible for Study
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Minimum Age: 18 Years

Sexes Eligible for Study
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All

Accepts Healthy Volunteers
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No

Study Plan
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How is the study designed?
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Design Details

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


Arms and Interventions

| Participant Group/Arm | Intervention/Treatment |
| --- | --- |
| Active Comparator: Nominal Parameter<br>Nominal T shock setting | Device: Nominal T shock setting<br>* Nominal Parameter Set 1 Programming Values for EnTrust<br>* Other names: Medtronic ICDs;|
| Experimental: Experimental Parameter<br>Educated T shock setting | Device: Educated T shock setting<br>* Experimental Parameter Set 2 Programming Values<br>* Other names: Medtronic ICDs;|

What is the study measuring?
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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 | 

 Terms related to the study
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Keywords Provided by Centre Hospitalier Valida
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Defibrillators, Ventricular Fibrillation Induction Testing