Clinical use of automatic implantable defibrillators

Area of Science:

• Cardiology
• Biomedical Engineering
• Electrophysiology

Background:

• Patients with sustained ventricular tachycardia (VT), ventricular fibrillation (VF), or torsades de pointes (Tdp) often experience syncopal events.
• These arrhythmias can be refractory to antiarrhythmic drugs or beta-blockers, necessitating advanced interventions.
• The automatic implantable defibrillator model B (AID-B) offers a potential solution for managing these critical cardiac conditions.

Purpose of the Study:

• To assess the safety and efficacy of the automatic implantable defibrillator model B (AID-B) in patients with refractory ventricular arrhythmias.
• To evaluate different implantation techniques, including thoracotomy, jugular vein access, and subcostal approaches.
• To determine defibrillation thresholds (DT) and identify factors influencing successful defibrillation.

Main Methods:

• Eleven patients with sustained VT, VF, or Tdp received AID-B implantation.
• Implantation strategies included thoracotomy, jugular vein access, and a subcostal approach, with some patients receiving epicardial patches.
• Ventricular arrhythmias were induced during surgery to assess defibrillation thresholds using alternating current stimulation.

Main Results:

• The subcostal approach for AID-B and epicardial patch implantation resulted in fewer local aseptic reactions compared to bifocal approaches.
• Defibrillation thresholds were generally manageable, with most patients achieving thresholds below 25 J.
• While some patients required adjustments to achieve optimal DT, the majority demonstrated successful defibrillation for VT and VF.

Conclusions:

• The automatic implantable defibrillator model B (AID-B) can be effectively implanted using various surgical approaches, with the subcostal route showing a favorable safety profile.
• Defibrillation thresholds are generally acceptable, although variations exist between VT and VF, and patient-specific adjustments may be necessary.
• Long-term survival was observed in 8 out of 11 patients, indicating the potential benefit of AID-B in managing life-threatening arrhythmias.