1. Technical Field
This application relates to a surgical apparatus for treating lesions and more particularly to an apparatus that delivers ablation fluid such as acetic acid to ablate lesions.
2. Background of Related Art
One current method of treating hepatic (liver) cellular carcinomas is using electrosurgical energy in the form of radiofrequency energy. A series of electrodes are placed in the malignant tumor and a generator is activated to apply energy to the electrodes which heats the tissue to destroy the tumor. One example of such device is marketed by RITA Medical Systems which has an array of electrodes, offered in various configurations, which are curved outwardly from the tube in which they are constrained. It has been documented however in the literature that RF energy application is not consistently sufficient to ablate the cancerous tissue. Therefore, the patient must repeatedly return to the physician for additional applications of RF energy until the lesion is satisfactorily ablated. This not only adds to the expense of the procedure but can have an adverse psychological impact on the patient whose treatment is prolonged and characterized by frequent hospital visits. In additional to the clinical disadvantage, utilization of RF energy can be expensive since capital equipment, i.e. an RF generator for applying and controlling the electrosurgical energy, is required.
Another method of treating tumors is the injection of alcohol through a needle to ablate the tumor. The alcohol is typically about 95% to 99.5% ethanol and diffuses into the cancerous cells to produce immediate necrosis due to effects of cellular dehydration and protein denaturation followed by small vessel thrombosis.
One instrument currently being utilized to deliver ethanol to treat hepatic tumors is the Bernardino infusion needle, marketed by Cook of Bloomington, Ind. The needle is hollow and has two infusion ports adjacent the sharp distal tip. This device, however, has several disadvantages. The ethanol is injected only adjacent the distal tip, creating a relatively small treatment (ablation) zone. Therefore the needle must be repeatedly maneuvered and repositioned in various regions of the tumor and ethanol repeatedly injected until the entire tissue region has been treated. In fact, oftentimes the needle will have to be fully removed and reinserted into the patient, sometimes as frequently as twenty times in a single surgical procedure requiring twenty needle sticks, to ensure the entire region receives an adequate supply of ethanol.
Another method of treating tumors is the injection of acetic acid. The acetic acid has the additional advantage of penetrating the tumor septi and therefore providing more uniform chemical treatment of the lesion.
Commonly assigned co-pending provisional application Ser. No. 60/272,119, filed Feb. 28, 2001, the entire contents of which are incorporated herein by reference, discloses an instrument for delivering ethanol, acetic acid, or other ablation fluid which advantageously avoided the aforedescribed multiple needle sticks and limited ablation zone. The instrument disclosed in the '119 application provides a larger treatment zone to ablate a larger tumor, avoids multiple needle sticks, reduces the time required for treatment, and simplifies the surgical procedure. Additionally, it provides a more uniform treatment zone as well as the ability to vary the treatment zone so that the same delivery needle could be adapted for different sized lesions.
However, although the needle of the '119 application is effective, there is still a need to improve the zone of ablation by providing greater certainty of the location of the ablation needles and the boundary of the ablation zone. The instrument of the present application achieves these objectives in addition to providing the larger and more uniform needle treatment zone, the avoidance of multiple needle sticks, the ability to vary the treatment zone and simplification of the procedure as in the needle of the '119 application.