US 5,971,980 A · System for controlling the energy delivered to a patient for ablation

Abstract

A power control system and method controls a power generator to vary the duty cycle of a power output provided to a delivery instrument for delivering that power to a site in a patient for ablation. The peak power can be raised and the duty cycle lowered to result in deeper lesions. However, the effective power is controlled so that it does not exceed a predetermined level. A power output having a higher peak power for producing deeper lesions can be obtained by using a lower duty cycle having a longer "off" period in order to deliver more power to the ablation site without overheating the delivery instrument. The maximum peak power that may be selected is determined in accordance with the structural limitations of the delivery instrument. The temperature of the delivery instrument is monitored, and the duty cycle is lowered when the temperature exceeds a predetermined maximum limit. After the instrument has cooled sufficiently, the duty cycle is then increased to its previous level.

Claims29

Dependent claims

An apparatus for delivering energy to biological tissue for a predetermined time duration for ablation, said apparatus comprising:

a power source for producing a power output having alternating instances of high peak power and very low power, said power output having variable power levels and a variable duty cycle for controlling the duration of said high peak power and very low power instances, said power source responsive to control signals for setting said power level and duty cycle of said power output;
a power delivery device connected to said power source, said power delivery device adapted to deliver energy to the tissue in response to said power output;
and
a processor for providing said control signals to said power source, said control signals for:
setting said high peak power level high and said duty cycle low, relative said high peak power level, so that the cumulative instances of high peak power occurring during said predetermined time duration is sufficient to introduce a lesion in the ablation tissue while the effective power is maintained at a level lower than a predetermined threshold effective power level which would produce either charring or coagulation of the ablation tissue or arcing at said power delivery device;
and
setting said duty cycle so that the effective power does not exceed said predetermined threshold effective power;
wherein said control signals control the depth of said lesion by varying said high peak power level while varying said duty cycle to maintain said effective power below said predetermined threshold effective power.

5 more elements

An apparatus for delivering energy to cardiac tissue for a predetermined time duration for ablation, the apparatus comprising:

a power source for producing a power output having alternating instances of high peak power and very low power, said power output having variable power levels and a variable duty cycle for controlling the duration of said high peak power and very low power instances, said power source responsive to control signals for setting the power level and duty cycle of the power output;
a catheter having a proximal end and a distal end;
an electrode operably connected to said power source and mounted at said distal end of the catheter, said electrode producing an energy output in response to said power output;
and
a processor connected to said power generator, said processor for providing said control signals to said power source, said control signals for:
setting said high peak power level high and said duty cycle low, relative said high peak level, so that the cumulative instances of high peak power occurring during said predetermined time duration is sufficient to introduce a lesion in the ablation tissue while the effective power is maintained at a level below a predetermined threshold effective power level which would produce either charring or coagulation of the ablation tissue or arcing at the electrode;
and
controlling the depth of said lesion by varying said high peak power level while varying said duty cycle to maintain said effective power below said predetermined threshold effective power.

5 more elements

A method of applying energy to cardiac tissue for ablation using an electrode connected to a power source, said power source producing a power output having alternating instances of high peak power and very low power, said power output having variable power levels and a variable duty cycle for controlling the duration of high peak power and very low power instances, said power source also having a timer for allowing the application of energy to the cardiac tissue for a set time duration, said method comprising the steps of:

placing said electrode at the cardiac tissue;
setting said time duration for the ablation procedure;
setting said high peak power level high;
and
setting the duty cycle of said power output low, relative said high peak power level, so that the cumulative instances of high peak power occurring during said set time duration is sufficient to introduce lesions in the tissue while the effective power during said set time duration is maintained at a level lower than a threshold effective power, said threshold effective power being that power which would produce either charring or coagulation of surrounding tissue or arcing in the cardiac region;
if desired, varying the high peak power level so that the depth of said lesion varies;
and
if desired, adjusting the duty cycle to maintain said effective power below said threshold effective power.

5 more elements

Dependencies are inferred from the claim text.

System for controlling the energy delivered to a patient for ablation

Life of this patent

System for controlling the energy delivered to a patient for ablation

Life of this patent

Abstract

Claims29