Apparatus and method for protecting tissues during cryoablation

Abstract

An apparatus and method for protecting the neurovascular bundle during cryoablation of tissues of the prostate by heating the vicinity of the neurovascular bundle while cooling pathological tissues of a prostate to cryoablation temperatures, thereby cryoablating pathological tissues while protecting the neurovascular bundle from damage. A cryoprobe operable to cool a distal operating tip while heating a proximal shaft is presented.

Description

RELATED APPLICATIONS[0001]This application is a continuation of U.S. patent application Ser. No. 10 / 412,330 filed on Apr. 14, 2003, which is continuation-in-part of PCT Patent Application No. PCT / IL02 / 01062 filed on Dec. 31, 2002, which claims the benefit of priority of U.S. Provisional Patent Application No. 60 / 344,369 filed on Jan. 4, 2002. The contents of the above Applications are incorporated herein by reference.FIELD AND BACKGROUND OF THE INVENTION[0002]The present invention relates to an apparatus and method for protecting the neurovascular bundle during cryoablation of tissues of the prostate. More particularly, the present invention relates to heating the vicinity of the neurovascular bundle while cooling pathological tissues in or near the prostate to cryoablation temperatures, thereby cryoablating pathological tissues while protecting the neurovascular bundle from damage. Additionally, the present application relates to a cryoprobe having a distal treatment head and a pro...

AI Technical Summary

Benefits of technology

"The present invention provides an apparatus and method for protecting healthy and functionally important tissue areas during cryoablation of pathological tissues in their vicinity. The invention involves cooling the operating tip of a cryoprobe to cryoablation temperatures while heating a portion of the shaft to prevent freezing of tissues adjacent to the shaft. The invention also includes using imaging modalities to map the prostatic region and locate the neurovascular bundle, and guiding the placement of the cryoprobe and heating probe using a heating probe. The invention further provides a method for protecting the neurovascular bundle while cryoablating tissues near the prostate. The technical effects of the invention include reducing or eliminating the probability of loss of erectile potency of the patient and protecting the neurovascular bundle to prevent damage."

Problems solved by technology

The principle danger and disadvantage of cryosurgical ablative treatment of the prostate, however, is the danger of partially or completely destroying the functional and structural integrity of non-pathological tissues proximate to the treatment locus, thereby having a deleterious effect on the health and quality of life of the treated patient.

However, neither Schatzberger's technique nor any other known technique has proven sufficiently accurate to prevent damage to peripheral tissues in all cases.

In particular, the neurovascular bundle, a prostatic area rich in blood vessels and in nerve tissues having cardinal importance in the process of erection of penis, is particularly vulnerable to damage by conventional prostatic cryoablation procedures.

Damage to the neurovascular bundle may cause loss of sexual potency.

Potent patients having an active sexual life are understandably reluctant to risk loss of potency as a result of cryosurgical treatment of the prostate, and such loss of potency unfortunately occurs in a non-negligible percentage of patients treated with conventional cryosurgery, as it does also in cases of treatment of prostate tumors by non-cryosurgical means.

Referring again to Schatzberger's technique, clinical practice has revealed an unanticipated limitation of that technique, with regard to implementation using a dense array of small diameter cryoprobes.

However, cold gases exhausting from treatment heads of cryoprobes cool the shafts of those cryoprobes.

Body tissues lying alongside cryoprobe shafts, although distant from an intended cryoablation target, risk being damaged by cold induced by contact with, or proximity to, cryoprobe shafts cooled by gases exhausting from cryoprobe treatment heads, where those gases have been intensively cooled, typically either by evaporation or by expansion through a Joule-Thomson orifice.

Yet, in practice, clinicians do not typically place cryoprobes in adjacent apertures when using Schatzberger's template, but rather typically leave one or even two vacant apertures between each aperture utilized to insert a cryoprobe.

When multiple parallel shafts of cryoprobes are densely introduced into a perineum or other area not intended for cryoablation, and each shaft is cooled by cold exhaust gases exhausting from a treatment head of a cryoprobe, the cumulative cooling effect of the dense array of shafts is to cool tissues proximate to the cryoprobe shafts to an extent which is damaging to those tissues.

In addition, however, there are now clinical indications that effective cryoablation of cancer may require more intense cooling than that provided by standard cryoablation procedures in common practice today.

It is further generally recognized that rapid cooling is an important factor in provoking cell death, a popular hypothesis being that rapid cooling encourages growth of intra-cellular ice crystals, known to be a powerful destructive agent, whereas gradual cooling tends to create extra-cellular ice crystals, which have some destructive effect but which are known to be less effective in ablation than are intra-cellular ice crystals.

Yet, use of such a dense cooling array of cryoprobes cannot be undertaken with impunity under prior art methods and techniques such as those described by Schatzberger, because of the damage to tissues external to the intended cryoablation target, particularly damage to tissues cooled by proximity to a dense array of cryoprobe shafts transporting exhausting expanded cooling gases away from a dense array of cryoprobe treatment heads.

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