Implantable Cardioverter Defribillators

Introduction

  • Implantable cardioverter-defibrillators (ICDs) are used to prevent sudden cardiac death as a result of cardiac arrhythmias.
  • The following video demonstrates the procedure for placing ICD:
  • ICD in children and patients with congenital heart disease (CHD) can be lifesaving
  • According to the study that represents the largest pooled assessment for CHD and pediatric ICD populations,1
    • A majority (61%) of CHD or pediatric patients receiving ICD therapy had primary prevention devices implanted.
    • Patients undergoing ICD procedures for primary prevention have higher NYHA scores and lower ejection fractions compared to the secondary prevention group with higher rates of cardiac arrest and ventricular tachycardia.
    • Tetralogy of Fallot and common ventricle were specific CHD lesions for which a majority had secondary prevention indications.
    • Among pediatric patients with primary electrical disorders, catecholaminergic polymorphic ventricular tachycardia and idiopathic ventricular tachycardia/ventricular fibrillation had higher rates of secondary prevention devices.

Children and CHD patients of all ages with ICDs face special issues:

  1. Increased likelihood of nonstandard device/lead implantation strategies and size constraints due to body habitus
  • Abnormal venous and intracardiac anatomy of patients with CHD may preclude transvenous lead placement.
  • Younger and shorter stature patients along with more complex forms of congenital heart disease underwent non-transvenous lead implantation at higher rates.
  • Patients with transposition of the great vessels (16.1%; p< 0.01) and common ventricle (3.6%; p=<0.01%) made up significantly more of the non-transvenous lead implantation population than the transvenous population (TGV: 7.9%, common ventricle: 0.4%)
  • Conversely, fewer tetralogy of Fallot patients were in the nontransvenous group (8.0%; p= 0.02) compared to transvenous group (16.5%).
  • ICD configurations in children and CHD patients commonly involve individualized epicardial or subcutaneous lead placement.
    • A recent study2 has demonstrated using MRI scans based personalized heart–torso models to successfully predict the optimal ICD configuration for a specific patient.
    • Such an optimal configuration exhibited the lowest defibrillation threshold and cardioversion threshold among tested ICD placement options.
    • In a patient with tricuspid valve atresia, two ICD configurations with epicardial leads were found to have the lowest defibrillation threshold.
  1. The need for multiple procedures over a lifetime.
    • Through growth and development, pediatric patients can anticipate decades of device-therapy.
    • The current limitations of lead durability and battery longevity guarantee these patients will require multiple generator changes and possible lead revisions/extraction.

References

1. Jordan C. et al. (2014). Implant and Clinical Characteristics for Pediatric and Congenital Heart Patients in the NCDR ICD Registry. Circulation: Arrhythmia and Electrophysiology.

2. Rantner L. et al. (2013). Placement of implantable cardioverter-defibrillators in paediatric and congenital heart defect patients: a pipeline for model generation and simulation prediction of optimal configurations. J Physiol 591.17 pp 4321–4334.

 

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