Comparison of VF Induction Techniques During Medtronic ICD Implant (VF) (ICD)
| Status: | Completed |
|---|---|
| Conditions: | Cardiology |
| Therapuetic Areas: | Cardiology / Vascular Diseases |
| Healthy: | No |
| Age Range: | 18 - Any |
| Updated: | 5/24/2018 |
| Start Date: | January 2011 |
| End Date: | August 2012 |
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.
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.
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.
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.
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.
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