Surgery – Instruments – Electrical application
Reexamination Certificate
2002-04-09
2004-04-13
Cohen, Lee (Department: 3739)
Surgery
Instruments
Electrical application
C606S041000, C604S035000, C604S114000, C607S099000, C607S105000, C607S113000
Reexamination Certificate
active
06719754
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates generally to the field of electrosurgery, and more particularly to surgical devices and methods which employ high frequency electrical energy to remove fatty tissue.
Suction lipectomy, commonly known as liposuction or lipoxheresis, is a well known surgical procedure used for sculpturing or contouring the human body to increase the attractiveness of its form. In general, the procedure involves the use of a special type of curette or cannula which is coupled to an external source of suction. An incision is made in the target area and the fatty tissue is essentially vacuumed from the patient's body. This procedures has its disadvantages, however, because the fat is relatively difficult to separate from the surrounding tissue. Such separation often causes excessive bleeding and damage to adjacent tissue or muscles. A further problem is that the surgeon must be careful not to allow the suction to remove or injure any desirable tissues, such as muscle, blood vessels, skin, subcutaneous tissues and the like. In addition, it is often difficult to maintain constant suction without stopping to clean tissue fragments from the cannula. Normally, the surgeon attempts to compensate for this problem by rapidly moving the cannula within the cavity, and even periodically withdrawing it to allow the fat to move through the cannula. This causes further trauma and collateral damage to surrounding muscle, tissue and other body structures.
In an effort to resolve some of the drawbacks with conventional liposuction, ultrasonic probes for vibrating and aspirating adipose tissue have been developed. The ultrasonic vibrations physically melt the fatty tissue so that it can be emulsified and aspirated through the probe. These ultrasonic probes have reduced the physical exertion required by the surgeon to remove fatty tissue, increased the speed of the operation and reduced the collateral damage created at the incision point. One problem with these probes, however, is excess heat generation at the distal tip of the ultrasonic probe. For example, when the probe has been inserted into the fatty tissue near the skin or the peritoneum, resistance can be met, which increases the wattage at the tip of the probe. The heat generated at the tip of the probe from the increased wattage may be in excess of the heat required for melting the fatty tissue. This excess heat results in burning of tissue, collateral damage to muscles or blood vessels and even penetration of membranes such as the skin or the peritoneum.
RF energy has also been used in liposuction procedures to remove fatty tissue. In particular, microwave and monopolar RF devices have been used to heat and soften fatty tissue so that the tissue can be more readily detached from the adjacent tissue with a suction instrument. Similar to ultrasonic energy, however, current microwave and monopolar RF devices have difficulty controlling excess heat generation at the target site, resulting in undesirable collateral tissue damage. For example, conventional electrosurgical cutting devices typically operate by creating a voltage difference between the active electrode and the target tissue, causing an electrical arc to form across the physical gap between the electrode and tissue. At the point of contact of the electric arcs with tissue, rapid tissue heating occurs due to high current density between the electrode and tissue. This high current density causes cellular fluids to rapidly vaporize into steam, thereby producing a “cutting effect” along the pathway of localized tissue heating. This cutting effect generally results in the production of smoke, or an electrosurgical plume, which can spread bacterial or viral particles from the tissue to the surgical team or to other portions of the patient's body. In addition, the tissue is parted along the pathway of evaporated cellular fluid, inducing undesirable collateral tissue damage in regions surrounding the target tissue site.
Moreover, monopolar electrosurgery methods generally direct electric current along a defined path from the exposed or active electrode through the patient's body to the return electrode, which is externally attached to a suitable location on the patient's skin. In addition, since the defined path through the patient's body has a relatively high electrical impedance, large voltage differences must typically be applied between the active and return electrodes to generate a current suitable for cutting or coagulation of the target tissue. This current, however, may inadvertently flow along localized pathways in the body having less impedance than the defined electrical path. This situation will substantially increase the current flowing through these paths, possibly causing damage to or destroying tissue along and surrounding this pathway.
SUMMARY OF THE INVENTION
The present invention provides systems, apparatus and methods for selectively applying electrical energy and suction to fatty or adipose tissue to remove the adipose tissue from the patient (e.g., liposuction, abdominoplasty and the like).
In one aspect of the invention, a method for removing adipose or fatty tissue underlying a patient's epidermis in body regions, such as the abdomen, lower torso, thighs, face and neck, is disclosed This method includes positioning one or more active electrode(s) and one or more return electrode(s) in close proximity to a target region of fatty tissue. A high frequency voltage difference is applied between the active and return electrodes, and the fatty tissue or fragments of the fatty tissue are aspirated from the target region. The high frequency voltage either heats and softens or separates the fatty tissue or completely removes at least a portion of the tissue. In both embodiments, the remaining fatty tissue is more readily detached from the adjacent tissue in the absence of energy, and less mechanical force is required for removal. The bipolar configuration of the present invention controls the flow of current to the immediate region around the distal end of the probe, which minimizes tissue necrosis and the conduction of current through the patient. The residual heat from the electrical energy also provides simultaneous hemostasis of severed blood vessels, which increases visualization and improves recovery time for the patient. The techniques of the present invention produce significantly less thermal energy than many conventional techniques, such as conventional ultrasonic and RF devices, which reduces collateral tissue damage and minimizes pain and postoperative scarring.
In one embodiment, the method comprises introducing a distal end of an electrosurgical instrument, such as a probe or a catheter, to the target site, and aspirating fatty tissue from the target site through one or more aspiration lumen(s) in the instrument. High frequency voltage is applied between one or more aspiration electrode(s) coupled to the aspiration lumen(s) and one or more return electrode(s) so that an electric current flows therebetween. The high frequency voltage is sufficient to remove or at least soften a portion of the tissue before the tissue passes into the aspiration lumen(s). This partial or total ablation reduces the size of the aspirated tissue fragments to inhibit clogging of the aspiration lumen.
In an exemplary embodiment, the tissue may be removed and/or softened by an electrosurgical probe having an aspiration lumen and one or more aspiration electrode(s) to prevent clogging of the lumen. The aspiration electrode(s) are usually located near or at the distal opening of the aspiration lumen so that tissue can be partially ablated before it becomes clogged in the aspiration lumen. In some embodiments, the aspiration electrodes(s) are adjacent to the distal opening, or they may extend across the distal opening of the lumen. The latter configuration has the advantage of ensuring that the fatty tissue passing through the aspiration lumen will contact the aspiration electrode(s). In other embodiments, the aspiration
Baker Michael A.
Brunell Stephen M.
Eggers Philip E.
Thapliyal Hira V.
Underwood Ronald A.
Arthrocare Corporation
Batt Richard R.
Cohen Lee
Raffle John T.
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