STIMULATION OF EXCITABLE TISSUES - Design and Development of Medical Electronic Instrumentation - page 364

TABLE 7.9 Typical Parameters Used in Electrochemical Therapy Instruments

Clinical Method of Typical Typical Current

Application Current Delivery Waveform or Voltage

Electrochemical Two or more platinum needle Dc 5 to 100 mA with a voltage

destruction of electrodes positioned under local compliance of up to 20 V

tumors anesthesia in or at the site of the to deliver a total charge of

tumor with an interelectrode approximately 30 to

distance of 3 cm 100 C/mL of tumor

volume

Attract lymphocytes 12- µ m-diameter IROX-coated wire Charge-balanced biphasic current 20 µ A to yield 500 to

to solid tumors or electrodes in the tumor or pulses 400 µ s in duration delivered 2000 µ C/cm 2

infections infection and large platinum at 200 Hz for 10 minutes to

reference electrode at remote site 8 hours per session

technique was e cial

tumors only was 80.2%. However, because most of the trials were conducted at centers that
are not bound by the strict research methodologies prescribed by the FDA to prove safety
and e

ff ective in 76% of cases. The e ff ectiveness rate reported for super fi

ectiveness, we must consider these results to be mere anecdotal evidence that EChT
may become a useful tool in the

ff

fight against cancer.
Unfortunately, EChT is not being given the attention that it deserves to rigorously prove
or disprove its clinical e

fi

cacy. The problem is that the pioneer of the technique, Swedish
physician Björn E. W. Nordenström, believes that the body has a second circulatory sys-
tem of continuous energy circulation that he calls a biologically closed electrical circuit
(BCEC). He believes that these currents participate in maintaining homeostasis and in con-
trolling the healing process in living organisms, and presents EChT as a direct application
of his BCEC concepts. This not only attracts the attention of a lot of quacks, but also makes
the principle of EChT unpalatable to most mainstream oncologists.
In a somewhat related application, U.S. patent 6,038,478 to Yuen et al. [2000] describes
the use of low-current biphasic pulses to attract lymphocytes to sites that can be accessed
through surgery to place an array of electrodes. The technique is said to be useful in the
treatment of solid tumors or in the treatment of certain infections, especially in poorly vas-
cularized (e.g., brain) or inaccessible areas where surgical intervention is unadvised and
electrode placement is feasible and less destructive.

Induction of Apoptosis via Nanosecond Pulsed Electric Fields

Apoptosis is the process by which a cell actively commits suicide, which is essential for
maintaining tissue homeostasis. Cancer is believed to result from the failure to regulate
apoptosis properly. High-intensity ( 300 kV/cm), nanosecond (10 to 300 ns) pulsed electric

fi fields (nsPEFs) are now being investigated as a tool to trigger apoptosis in cancerous tis-

sue (Table 7.10). The hypothesized working principle behind nsPEF is cytochrome c
release into the cytoplasm, suggesting that nsPEF targets the mitochondria, which are the
initiators of apoptosis. This technique, pioneered by researchers at Old Dominion
University in Norfolk, Virginia [Schoenbach et al., 2001], is still in its infancy, and its clin-
ical e cacy, if any, is yet to be demonstrated.

Embolic Therapy

The traditional treatment for a ruptured intracranial aneurysm to prevent rebleeding is
through microsurgery. The method comprises a step of clipping the neck of the aneurysm,