US5300068A — Electrosurgical apparatus

Claim 1

Independent Claim 174 words

An electrosurgical apparatus for cutting tissue and for ablating occlusions comprising: means for selectively generating a train of relatively high energy pulses and a train of relatively low energy pulses of electrical energy for application to a wire having an attached electrode, the means for selectively generating having a variable output impedance, a load impedance of the means for selectively generating comprising an impedance of the wire having an attached electrode; means for sensing the load impedance relative to the output impedance in response to the train of low energy pulses applied to the wire and for adjusting the output impedance to match the load impedance in response to the sensed load impedance relative to the output impedance; and means for controlling the means for selectively generating and the means for sensing and for adjusting to generate the train of low energy pulses and to match the output impedance to the load impedance and for subsequently generating the train of high energy pulses for producing an arc at the electrode to ablate an occlusion.

Claim 2

Dependent Claim 174 words

An electrosurgical apparatus for cutting tissue and for ablating occlusions comprising: means for selectively generating a train of relatively high energy pulses and a train of relatively low energy pulses of electrical energy for application to a wire having an attached electrode, the means for selectively generating having a variable output impedance, a load impedance of the means for selectively generating comprising an impedance of the wire having an attached electrode; means for sensing the load impedance relative to the output impedance in response to the train of low energy pulses applied to the wire and for adjusting the output impedance to match the load impedance in response to the sensed load impedance relative to the output impedance; and means for controlling the means for selectively generating and the means for sensing and for adjusting to generate the train of low energy pulses and to match the output impedance to the load impedance and for subsequently generating the train of high energy pulses for producing an arc at the electrode to ablate an occlusion.

Claim 3

Dependent Claim 68 words

The apparatus of claim 1 wherein the means for selectively generating comprises an oscillator for producing a continuous wave signal, a pulse modulator connected to the oscillator for forming pulses of the continuous wave signal, and an amplifier connected to the pulse modulator for amplifying the pulses of the continuous wave signal and producing the trains of relatively low energy and relatively high energy pulses of electrical energy.

Claim 4

Dependent Claim 53 words

The apparatus of claim 2 wherein the amplifier includes a preamplifier initially amplifying the pulses of the continuous wave signal and producing the train of relatively low energy pulses and a power amplifier for receiving and amplifying the train of relatively low energy pulses and producing the train of relatively high energy pulses.

Claim 5

Dependent Claim 58 words

The apparatus of claim 1 wherein the means for sensing and adjusting comprises a directional coupler for monitoring the relatively low energy pulses delivered to the load impedance to determine a forward energy and the relatively low energy pulses reflected from the load impedance to determine a reflected energy for comparing the forward energy to the reflected energy.

Claim 6

Dependent Claim 51 words

The apparatus of claim 1 wherein the means for sensing and adjusting comprises a plurality of reactive electrical components switchably interconnectable with each other and connected between the amplifier and the output impedance for interconnection in response to the means for controlling to match the output impedance to the load impedance.

Claim 7

Dependent Claim 48 words

The apparatus of claim 5 wherein the reactive components comprise a transformer including a winding having a plurality of taps and a plurality of capacitors connectable to the taps and to the winding for producing a plurality of impedances for matching the output impedance to the load impedance.

Claim 8

Dependent Claim 13 words

The apparatus of claim 1 wherein the means for controlling comprises a microprocessor.

Claim 9

Dependent Claim 13 words

The apparatus of claim 7 including a visual display connected to the microprocessor.

Claim 10

Dependent Claim 77 words

The apparatus of claim 1 including a switch for actuating the means for selectively generating wherein, each time the switch is actuated, the train of relatively low energy pulses is generated, the means for sensing and adjusting matches the output impedance to the load impedance using the relatively low energy train of pulses, and the train of relatively high energy pulses is generated after the output impedance is matched to the input impedance to ablate the occlusion.

Claim 11

Dependent Claim 20 words

The apparatus of claim 1 including a balun transformer coupling the means for sensing and adjusting to the load impedance.

Claim 12

Dependent Claim 43 words

The apparatus of claim 10 wherein the balun transformer includes two leads and including ground fault interrupting means connected to the balun transformer for disabling the means for selectively generating when current flow through the two leads of the balun transformer is unbalanced.

Claim 13

Dependent Claim 77 words

The apparatus of claim 1 including means for measuring relative electrical energy produced by the arc at the electrode by a relatively high energy pulse of the train of relatively high energy pulses, means for comparing the relative electrical energy to a predetermined value to determine an energy difference, and means for adjusting the electrical energy of a subsequent pulse in response to the energy difference to reduce the energy difference for the subsequent pulse toward zero.

Claim 14

Dependent Claim 36 words

The apparatus of claim 12 wherein the means for measuring includes a filter for rejecting a primary frequency and at least one harmonic frequency of the trains of relatively high energy and relatively low energy pulses.

Claim 15

Dependent Claim 21 words

The apparatus of claim 13 wherein the means for measuring includes an integrator connected to and receiving signals from the filter.

Claim 16

Dependent Claim 30 words

The apparatus of claim 12 wherein the means for comparing includes an analog-to-digital converter for converting the relative electrical energy into a digital value for comparison with the predetermined value.

Claim 17

Dependent Claim 65 words

The apparatus of claim 12 wherein the means for selectively generating comprises an oscillator for producing a continuous wave signal, a pulse modulator connected to the oscillator for forming pulses of the continuous wave signal, and a variable gain amplifier connected to the pulse modulator for amplifying the pulses and producing the trains of relatively high energy and relatively low energy pulses of electrical energy.

Claim 18

Dependent Claim 161 words

An electrosurgical apparatus for cutting tissue and for ablating occlusions comprising: means for generating a train of variable energy pulses of electrical energy for application to a wire connected to an output terminal of the means for generating and having an electrode attached to the wire for producing an arc in response to the pulses of electrical energy; means for measuring relative electrical energy produced by the arc at the electrode produced by a pulse including a filter connected to the output terminal in parallel with the wire and the attached electrode for rejecting a primary frequency and at least one harmonic frequency of the train of variable energy pulses of electrical energy; means for comparing the relative electrical energy produced by the arc to a predetermined value to determine an energy difference; and means for adjusting the electrical energy of a subsequent pulse in response to the energy difference to reduce the energy difference for the subsequent pulse toward zero.

Claim 19

Dependent Claim 161 words

An electrosurgical apparatus for cutting tissue and for ablating occlusions comprising: means for generating a train of variable energy pulses of electrical energy for application to a wire connected to an output terminal of the means for generating and having an electrode attached to the wire for producing an arc in response to the pulses of electrical energy; means for measuring relative electrical energy produced by the arc at the electrode produced by a pulse including a filter connected to the output terminal in parallel with the wire and the attached electrode for rejecting a primary frequency and at least one harmonic frequency of the train of variable energy pulses of electrical energy; means for comparing the relative electrical energy produced by the arc to a predetermined value to determine an energy difference; and means for adjusting the electrical energy of a subsequent pulse in response to the energy difference to reduce the energy difference for the subsequent pulse toward zero.

Claim 20

Dependent Claim 16 words

The apparatus of claim 17 wherein the means for measuring the electrical energy includes an integrator.

Claim 21

Dependent Claim 34 words

The apparatus of claim 17 wherein the means for comparing includes an analog-to-digital converter for converting the relative electrical energy produced by the arc into a digital value for comparison with the predetermined value.

Claim 22

Dependent Claim 59 words

The apparatus of claim 17 wherein the means for generating comprises an oscillator for producing a continuous wave signal, a pulse modulator connected to the oscillator for forming pulses of the continuous wave signal, and a variable gain amplifier connected to the pulse modulator for amplifying the pulses and producing the train of variable energy pulses of electrical energy.

Claim 23

Dependent Claim 25 words

The apparatus of claim 17 including control means for controlling the means for generating and the means for adjusting, the control means comprising a microprocessor.

Claim 24

Dependent Claim 13 words

The apparatus of claim 21 including a visual display connected to the microprocessor.

Annuity Stage	Window Opens	Payment Deadline	Surcharge Period Until	Estimated Fee	Status
3.5 Years (Year 4)	1997-04-04	1997-10-04	1998-04-05	$2000.00	Window Closed / Lapsed
7.5 Years (Year 8)	2001-04-04	2001-10-04	2002-04-05	$3760.00	Window Closed / Lapsed
11.5 Years (Year 12)	2005-04-04	2005-10-04	2006-04-05	$7700.00	Window Closed / Lapsed

Electrosurgical apparatus

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