Medtronic DBS 3387 Gebrauchsanweisung Seite 35

DBS Amplitude and Pulse Width Limits
Computed for Resistances Ranging from 500 to 2,000 Ohms
Model 3387 and 3389 DBS Lead Electrode Surface Area = 0.06 cm
Charge Density Threshold = 30 Microcoulombs/cm
18
16
14
12
Max Device
Amplitude
(10.5V) 10
8
6
4
Example A
+
2
0
0 50 100
Pulse Width
(Microseconds)
Figure 23. Charge density at various parameter settings.
Figure 23 includes two examples of charge density calculated for the
neurostimulation system. In Example A, the neurostimulator is set to:
amplitude = 3.0 V and pulse width = 90 µsec. The charge density for
Example A is below the lowest impedance curve, thus indicating a charge
density below 30 microcoulombs/cm
impedance of 500 Ω.
In Example B, neurostimulator stimulation parameters are set to: amplitude
= 6.1 V and pulse width = 210 µsec. The charge density at these settings
is in the shaded area indicating it may be high enough to cause tissue
damage at an impedance of 500 Ω. However, if the impedance in this case
is 1348 Ω, the charge density would be below 30 microcoulombs/cm
phase.
2
/phase
2,000 Ohms
1,348 Ohms*
500 Ohms
WARNING
AREA
Example B
+
150 200 250 300 350 400
*Mean resistance from clinical
studies = 1348 ohms (range 610-2000)
2
/ phase at the most conservative
Technical Manual
2
,
450
2
/
English 33