Optimization of transvenous coil position for active can defibrillation thresholds

Area of Science:

• Cardiovascular Medicine
• Biomedical Engineering
• Electrophysiology

Background:

• Active pectoral pulse generators are standard for defibrillator implantations.
• Optimal transvenous lead systems and coil placement for active can configurations remain undetermined.
• This study investigates the role of a superior vena cava (SVC) coil in active pectoral systems.

Purpose of the Study:

• To evaluate the benefit of an SVC coil on defibrillation thresholds.
• To determine the optimal position of an SVC coil.
• To assess defibrillation thresholds with an active left pectoral pulse generator and right ventricular coil.

Main Methods:

• Prospective, randomized study with 27 patients.
• Evaluation of three lead configurations: unipolar, low SVC coil, and high SVC coil.
• Biphasic shocks delivered between the right ventricular coil and active can.

Main Results:

• Defibrillation thresholds were significantly lower with SVC coil configurations (8.9-8.5 J) compared to unipolar (11.2 J).
• 96% of patients achieved low defibrillation thresholds (< or = 15 J) with SVC coils, versus 81% with unipolar.
• Shock impedance increased, and peak current decreased with the unipolar configuration.

Conclusions:

• A proximal transvenous SVC coil reduces defibrillation energy requirements in active can unipolar lead systems.
• The specific position of the SVC coil (low vs. high) did not significantly affect defibrillation thresholds.
• SVC coil addition is beneficial for optimizing defibrillation efficacy.