Biophan releases additional data on pacemaker and defibrillator lead heating

14 May 2005

Rochester NY, USA. Biophan Technologies, Inc. (OTCBB:BIPH), has released additional technical information on its research into pacemaker and implantable defibrillator lead heating. The data reveal that the most prevalent heating occurs not at the electrode tip of a lead, but actually a short distance away from the electrode tip, in the tissue itself.

Michael Weiner, CEO of Biophan, explained: "The phenomenon we are measuring is heat dissipation in tissue, at the interface between a highly electrically/thermally conductive medium (the lead) and a much lower electrically/thermally conductive medium (cardiac tissue). We have simulated this, and are continuing to refine the computer model to account not only for blood flow, but also the level of perfusion in the myocardium and also in the fibrous cap that develops around the lead some time after implantation.

"Our modeling to date indicates that heat is not created in the electrode itself, but as the electrical energy dissipates radially from the electrode tip and also from the helical fixation feature," said Mr. Weiner." The thin layer of tissue in immediate contact with the lead is close enough to the electrode that the electrode acts as a heat-sink; therefore, this thin layer does not experience the highest degree of heating, nor does the electrode body itself. As the current flows beyond this initial layer, the tissue is more poorly coupled to the electrode body thermally, and thus experiences more temperature rise. As the current flows even further outward in a radial manner, the cross-section of tissue it transits increases, so the heating effect falls off; in addition there is a much larger mass of tissue which contributes to the temperature rise decreasing.

"What we see both in our computer model and in fibre-optic temperature measurements made with highly controlled positioning fixtures, is minimal heating of the electrode body, modest heating of the very first layer of tissue, much higher heating slightly further out and then the temperature increase falling off rapidly."

The new data is available on the Company's web site at:

This additional data released on 4 May added to the data released on 29 April regarding the sensitivity of testing procedures to the probe type and placement within the MRI bore. The company revealed that they are using a fluorescence-based fibre optic probe in order to eliminate any electrical interaction between the lead and measuring device which might change the conditions at the electrode. This type of probe is consistent with the existing ASTM Standard. Many researchers report that they use a probe that has the sensing element in a ring around the optical fibre, which can be located 0.5mm or more away from the end of the probe. Biophan scientists use a probe with the sensing element at the very end, because the temperature changes significantly over very small distances, which can be influenced by the location of the sensing element within the probe.

Biophan also revealed that the lateral position in the MRI bore has a significant effect on measured temperature increases. It has tested both on-centre and slightly off-axis to simulate the degree of clinically relevant offset that might be experienced, such as for a small individual who is being imaged for a non-central complaint, such as a right shoulder complaint. The degree of offset can create a much larger temperature increase, as indicated in the data that Biophan revealed in April showing that an offset of only several inches can result in physiologically significant increases in lead heating of as much as 10 degrees Celsius.

"The existing ASTM Standard is somewhat qualitative regarding a) probe positioning, b) IPG/lead positioning, and c) position within the bore; we believe this is the reason there is such large variability in test results for the same MRI scan sequence reported by different examiners. Given the exponential relationship between temperature rise and the time before cell death (one second at 60 degrees Celsius for example) we believe that safety testing simply must be conducted over the full range of clinically relevant conditions," Mr. Weiner concluded.

Mr. Weiner will provide the additional data at the Heart Rhythm Society's 26th Annual Scientific Sessions in New Orleans. He will be one of five Biophan employees exhibiting and meeting with device manufacturers at the Heart Rhythm Society session.

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