Minimal Defibrillation THreshold in Pediatric and Adolescent Patients Undergoing Elective Subcutaneous Implantable Cardiac Defibrillator Implantation or Replacement.

Children experience more adverse events and complications from the conventional
transvenous ICD, such as lead fractures and infections. The subcutaneous ICD is
developed to reduce these lead-related complications and has no endocardial
leads. However, the size of the generator makes the S-ICD less suitable for
small children. The energy output the device has to deliver to effectively
terminate ventricular arrhythmias is the main determinant of generator size.
This energy output was determined by evaluating the defibrillation threshold
(DFT) in adults. However, new research conducted in the AMC, proves that the
defibrillation threshold in adults is significantly lower. By evaluating if the
DFT in children is also lower, the energy output could be decreased, thus
reducing the generator size. This could be the first step towards an ICD that
is tailored for small children.

To determine the minimal amount of energy needed to effectively terminate
ventricular arrhythmias

This is a prospective, non-randomized, single arm study with 12 subjects.
All patients undergoing elective S-ICD implantation or replacement receive a
standard of care defibrillation threshold test. This consists of the inducement
of ventricular fibrillation, followed by 1 or 2 shocks of 65J. During this
study course a step-down protocol will be followed for the defibrillation
threshold test, starting with a shock of 20J.

It is well established that the number of shocks during DFT testing is not
associated with an increased risk for heart failure, death or future VT/VF
episodes. For the majority of the pediatric patients two shocks will be
required, with a lower total energy output than the current standard of
practice. In a small percentage of patients three of four shocks will be
required to determine the minimal defibrillation threshold, however, the total
amount of energy according to the study protocol will not exceed 185J. There
are no additional post-procedural limitations or visits required for this
study. DFT testing is not painful, considering it is always performed under
general anaesthesia. Summarily, this study does not increase the risks
associated with S-ICD implantation, nor does it have an increased risk compared
to routine DFT testing during S-ICD implantation.