Novel intravascular defibrillator: defibrillation thresholds of intravascular cardioverter-defibrillator compared to conventional implantable cardioverter-defibrillator in a canine model.

BACKGROUND

An intravascular, percutaneously placed implantable defibrillator (InnerPulse percutaneous intravascular cardioverter-defibrillator [PICD]) with a right ventricular (RV) single-coil lead and titanium electrodes in the superior vena cava (SVC) and the inferior vena cava (IVC) has been developed.

OBJECTIVE

The purpose of this study was to compare defibrillation thresholds (DFTs) of the PICD to those of a conventional implantable cardioverter-defibrillator (ICD) in canines.

METHODS

Eight Bluetick hounds were randomized to initial placement of either a PICD or a conventional ICD. For PICD DFTs, a single-coil RV defibrillator lead was placed in the RV apex, and the device was positioned in the venous vasculature with electrodes in the SVC and IVC. With the conventional ICD, an RV lead was placed in the RV apex and an SVC coil was appropriately positioned. The ICD active can (AC) was implanted in a subcutaneous pocket formed in the left anterior chest wall and connected to the lead system. DFT was determined by a three-reversal, step up-down method to estimate the 80% success level. Two configurations were tested for the conventional ICD (#1: RV to SVC+AC; #2: RV to AC). A single configuration (RV to SVC+IVC) was evaluated for the PICD.

RESULTS

Mean PICD DFT was 14.8 ± 1.53 (SE) J. Conventional #1 configuration demonstrated mean DFT of 20.2 ± 2.45 J and #2 of 27.5 ± 1.95 J. The PICD had a significantly lower DFT than the better conventional ICD configuration (#1; mean difference 5.4 ± 2.1 J, P <.05, paired t-test, N = 8).

CONCLUSION

The new intravascular defibrillator had a significantly lower DFT than the conventional ICD in this canine model.