Implantable Intravascular Defibrillator: Evaluation of Defibrillation Waveforms with Inferior Vena Cava Electrode System

Abstract

In canines, a totally intravascular implantable defibrillator with electrodes in the RV apex, SVC, and IVC had a DFT similar to that of standard nonthoracotomy lead systems. No significant effect was noted with changes in tilt or with balanced or unbalanced waveforms.

Chronic Implantation of Intravascular Cardioverter Defibrillator in a Canine Model: Device Stability, Vascular Patency, and Anchor Histology

“…The device utilizes a unique defibrillation vector that includes the inferior‐posterior segments of the right ventricle, shocking from a right ventricular coil (anode) to titanium cans located in the superior vena cava (SVC) and inferior vena cava (IVC), respectively (Figs. A and B) . The PICD is rapidly implanted (average of 14 minutes) from the femoral vein and designed to be completely removed when explant or replacement is required .…”

To the Editor:

“…The recent letter to the Editor by Dr. Irnich regarding our manuscript was appreciated for its clarifications and was read with great interest by our group 1,2 . Dr. Irnich's hypothesis is that “if [we] would have formed ratios of unbalanced thresholds of each dog with its balanced counterpart—each dog is its own control—and summing up all ratios, the result would be surely and significantly greater than 1 indicating that unbalanced thresholds are higher than the corresponding balanced thresholds.” However, we did perform this analysis prior to submission of the article and found it to be not significant (P‐values > 0.25).…”

To the Editor:

“…We feel honored to be referenced in the paper of Sanders Jr. et al 1 with our paper on “How to program pulse duration or tilt in implantable cardioverter defibrillators.” 2 However, we do not state in our paper that “conventional implantable cardioverter defibrillators deliver a biphasic waveform which is truncated after the voltage has declined exponentially by 50–65% of its initial value.” Instead, we are recommending how the pulse duration or tilt should be programmed to reach optimum thresholds. This recommendation is based on the hypothesis that the capacitor discharge voltage of a defibrillator must not drop below “rheobase.” The correctness of this hypothesis is meanwhile confirmed experimentally for exponentially decaying defibrillation pulses 3 and for sinusoidal electric fields 4 …”