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

[0025]According to one aspect of the present invention there is provided a method for protecting at least a portion of a neurovascular bundle while cryoablating tissues of a prostate, comprising (a) positioning an operating tip of a cryoprobe in a vicinity of pathological tissue within a prostate; (b) positioning a heating probe in a vicinity of a neurovascular bundle; and (c) heating the heating probe while cooling the operating tip of the cryoprobe to cryoablation temperatures, thereby cryoablating pathological tissue near the operating tip while preventing freezing of tissue of the neurovascular bundle near the heating probe; thereby preventing damage to at least a portion of the neurovascular bundle.

[0028]According to another aspect of the present invention there is provided a cryoprobe having a shaft and a distal operating tip, the tip being operable to cool to cryoablation temperatures tissues surrounding the tip, thereby cryoablating the tissues, the shaft being designed and constructed to protect tissues adjacent to the shaft from cryoablation and from damage by freezing.

[0033]According to still another aspect of the present invention there is provided a method for protecting tissues adjacent to a shaft of a cryoprobe while cryoablating tissues adjacent to an operating tip of said cryoprobe, comprising (a) cooling the operating tip of the cryoprobe to cryoablation temperatures, thereby cryoablating tissues adjacent to the operating tip; and (b) simultaneously heating a portion of the shaft, thereby preventing freezing of tissues adjacent to the shaft, thereby protecting tissues adjacent to the shaft while cryoablating tissues adjacent to the operating tip.

[0036]The present invention further successfully addresses the shortcomings of the presently known configurations by providing an apparatus and method for protecting the neurovascular bundle during cryoablation of nearby prostate tissues, thereby substantially reducing or eliminating the probability that loss of erectile potency of the patient will result from cryoablative prostate treatment.

[0037]The present invention further successfully addresses the shortcomings of the presently known configurations by providing an apparatus and method enabling cooling of cryoprobe treatment heads while preventing cooling of tissues adjacent to cryoprobe shafts, particularly in applications utilizing a dense array of cryoprobes.

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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