CATHETERS FOR TREATING PROSTATE DISEASE

Abstract: Applying squeezing pressure to a diseased prostate, by means of a urethral and/or rectal catheter (100) incorporating an inflatable prostate balloon (122); to compress the prostate while it is being irradiated from a microwave antenna (116), increases the therapeutic temperature to which the prostate tissue more distal to the microwave antenna (116) can be heated without heating any non-prostate tissue beyond a maximum safe temperature, and reduces the temperature differential between the heated more distal and more proximate prostate tissue from the microwave antenna (116).

Description: CATHETERS FOR TREATING PROSTATE DISEASE Background of the Invention This invention relates to the use of microwaves for t treatment of prostate disease and, more particularly, catheters designed to efficiently irradiate the prostate of male patient with microwave power. As known in the art, prostate disease, such as prosta cancer or benign prostatic hypertrophy (BPH), inter alia, resul in a narrowing of the urethra in the neighborhood of the prosta caused by the surrounding enlarged prostate. This narrowi restricts the passage of urine. As is also known, a diseas prostate can be treated by irradiating prostate tissue with amount of microwave power sufficient to heat that prostate tiss to a therapeutic temperature. However, the maximum microwa power that can be used is limited by the fact that it essential that none of the prostate tissue be overheated beyo a maximum therapeutic temperature and that none of the irradiat non-prostate tissue be heated beyond a maximum safe temperatu (which maximum safe temperature for non-prostate tissue is bel the maximum therapeutic temperature for prostate tissue). Catheters designed to be inserted into the urethra th help pass urine and bulb applicators designed to be inserted int the rectum of the patient, which have been fitted with • microwave antenna, have been used in the past to irradiate t prostate tissue of the patient with microwave power. A urethr catheter is often equipped with a so-called Foley balloon locate close to the tip thereof, which may be inflated (usually wit air) after the tip of the urethral catheter has been inserte into the patient's bladder, thereby to secure the catheter at fully inserted position within the patient's urethra. A b applicator may be made non-symmetrical so that, after f insertion into a patient's rectum, the microwave power prefere tially irradiates the patient's prostate tissue. Regardless of whether the patient's prostate tissue irradiated with microwave power radiated by the microwave anten from the patient's urethra or rectum, it is apparent that no prostrate tissue situated between the patient's prostate a urethra or rectum, as the case may be, also will be irradiate Further, since the microwave field intensity tends to vary as inverse function (e.g., as an inverse square) of distance fr the microwave antenna, this non-prostate tissue will be mo highly irradiated than will the prostate tissue (particular that prostate tissue situated more distal to the microwa antenna) , because the irradiated non-prostate tissue is mo proximate to the microwave antenna. Therefore, the differen between the respective microwave-field intensities heating t more proximate irradiated non-prostate tissue and the more dist irradiated prostate tissue varies as an inverse function of t ratio of their respective distances from the microwave antenn Thus, in order to heat the more distal prostate tissue to higher therapeutic temperature without concurrently eith overheating any of the more proximate prostate tissue or heati the more proximate non-prostate tissue beyond a maximum sa temperature, it would be desirable to increase the minim distance between the microwave antenna and the more proxima non-prostate tissue, without appreciably affecting the distan between the more distal prostate tissue. Summary of the Invention The present invention contemplates increasing th minimum distance between the microwave antenna and the mor proximate non-prostate tissue by applying squeezing pressure t such more proximate tissue. More specifically, the present invention is directed t an improved catheter adapted to be.inserted into an orifice of male patient for treating prostate disease, wherein the cathete comprises means including microwave antenna means for irradiatin the patient's prostate with a given distribution of microwav field intensity, thereby to heat tissue of the patient to temperature which tends to vary as a direct function of microwav power and as an inverse function of the distance of that tissu to the microwave antenna means, and wherein the maximum microwav power to be employed is limited to an amount at which th temperature of the patient's heated tissue most proximate to th microwave antenna means does not exceed a given safe maximu temperature. The improvement comprises an inflatable balloon (1 which is adapted to be in a deflated state while the catheter i being inserted into the orifice, (2) which is located in th catheter at a position which is in cooperative relationship wit the patient's prostate when the catheter is fully inserted, an (3) which is adapted to be inflated when the catheter is full inserted for applying squeezing pressure to both prostate tissu and that non-prostate tissue situated between the inflate balloon and the prostate tissue, thereby increasing the mini-ma distance between heated tissue of the patient and the microwav antenna means. The desirable result is that the maximu microwave power may be increased without exceeding the give maximum safe temperature and the temperature differential betwee the heated prostate tissue more proximate to the microwav antenna means and the heated prostate tissue more distal to th one microwave antenna means is reduced. Brief Description of the Drawings Figures 1, la and lb, taken together, diagrammaticall illustrate a urethral catheter for treating prostate disease, which urethral catheter incorporates a first embodiment of th present invention; Figure lc diagrammatically illustrates a modificat of the aforesaid urethral catheter; Figures 2a and 2b, taken together, illustrate advantages of the aforesaid urethral catheter; Figure 3 diagrammatically illustrates a rectal cathet for treating prostate disease, which rectal catheter incorporat a second embodiment of the present invention, and also illu trates the advantages of this rectal catheter; Figures 3a and 3b, taken together, illustrate a fir modification of the rectal catheter illustrated in Figure 3; a Figures 3c and 3d, taken together, illustrate a seco modification of the rectal catheter illustrated in Figure 3. Preferred Embodiments of the Invention Like urethral catheters of the prior art, the urethr catheter shown in Figures 1, la and lb comprises a memb defining longitudinal catheter bore 100 and an inflatable Fol balloon 102 surrounding bore 100. A tip portion 104, located front of Foley balloon 102, terminates bore 100 in a smooth t 106. Tip portion 104 together with Foley balloon 102 in a d flated state are intended to be inserted into the bladder of patient and then, by inflation of Foley balloon 102, cathet bore 100 is maintained in substantially fixed position within t urethra of the patient. As indicated in Figure la, tip 1 includes several perforations 108 which permit urine to channeled from the patient's bladder to urine lumen 110 of bo 100, through which the patient discharges urine. In order inflate Foley balloon 102, lumen 112 (Figure lb) extends fr Foley balloon 102 to Foley balloon inflation valve 114 attache to the rear of bore 100. Treatment of prostate disease wit microwaves requires that the urethral catheter includes properly located microwave antenna 116, which is connected to a external microwave power source over transmission line 11 (Figure 1) that runs through microwave lumen 120 (Figure lb) Further, as known but omitted from the drawing, treatment o prostate disease with microwaves requires the use of a thermom ter (preferably digital), including one or more suitably plac temperature sensing probes, for ascertaining the temperature tissue heated by the microwaves. In accordance with the principles of the prese invention, the urethral catheter shown in Figures 1, la and also includes prostate balloon 122 surrounding bore 100 a longitudinally located behind Foley balloon 102 and in cooper tive relationship with microwave antenna 116. More specificall microwave antenna 116 and prostate balloon 122 are longitudinal situated at a distance from tip 106 such that when bore 100 fully inserted in the urethra of a patient, elements 116 and 12 are in cooperative alignment with the patient's prostate. I order to inflate prostate balloon 122, prostate balloon lumen 12 (Figure lb) extends from prostate balloon 122 to one or mo prostate balloon inflation valves 126 attached to the rear bore 100. Preferably, microwave antenna 116 and microwave lum 120 are axially situated with respect to the axis of bore 100 {i which case the other lumens 110, 112 and 124 are situated o axis, as shown in Figure lb), so that the distribution of th microwave field intensity irradiating the patient's prostate i angularly non-directional. The size of catheters is conventionally measured i French units. A typical size for the urethral catheter shown i Figure 1 is 16 French. Typically, the length of the bore 10 between its tip and its attachment to valves 114 and 126 is abou 360 millimeters (mm) ; the length of tip portion 104 is about 2 mm; the length of Foley balloon 102 is about 10 mm; the distanc between Foley balloon 102 and prostate balloon 122 is about 4 iπm and the length of prostate balloon 122 is about 40 mm. Further the minimum diameter of microwave lumen 120 is about 2.5 mm. In practice, while the catheter shown in Figures 1, l and lb is being inserted into the urethra of a patient wit prostate disease, both the Foley and prostate balloons are in deflated state. This both makes for easier insertion an minimizes pain to the patient. After full insertion (i.e., t deflated Foley balloon reaching into the patient's bladder), fluid (usually air) is pumped through the Foley inflation val thereby to inflate the Foley balloon and hold the catheter with the patient's urethra. However, the catheter is still capable limited longitudinal movement with respect to the urethra. Aft the Foley balloon has been inflated, a fluid, preferably a lo loss radio-opaque liquid (e.g., deionized water in which a sma amount of a radio-opaque substance has been dissolved), is slow pumped through the one or more prostate inflation valves into t prostate balloon. The use of a radio-opaque liquid permi fluoroεcopy of inflated prostate balloon 206-b to be employed first align the longitudinal position of the prostate ballo with the patient's prostate and then insure that the prosta balloon is inflated by the proper amount to apply a squeezi pressure that results in a desired compression of the prosta tissue. It is desired to heat the diseased prostate tissue t a therapeutic temperature without heating the non-prostate tissu lining the urethra, which intervenes between the microwav antenna and this prostate tissue, beyond a maximum safe tempera ture. However, the irradiating microwave field intensity, whic varies as an inverse function (e.g., inverse square) of th distance between the microwave antenna and the heated tissue, i higher for the intervening non-prostate tissue than it is for th prostate tissue and is higher for the more proximate prostat tissue than it is for the more distal prostate tissue. The us of an inflated prostate balloon, employed by the present inven tion, mitigates this problem, as shown in Figures 2a and 2b. Figures 2a and 2b show that the radial distances of th urethral catheter from microwave antenna 200 to prostate tissu 202 and intervening non-prostate tissue 204 with a deflate prostate balloon 206-a and with an inflated prostate balloon 206 b, respectively. As shown, inflated prostate balloon 206-b form a circumferentially symmetrical toroid extending around th entire circumference of the urethral catheter. Specifically, t radial distance R lb from microwave antenna 200 to the beginni of non-prostate tissue 204 with inflated prostate balloon 206 is significantly larger than the corresponding radial distance with deflated prostate balloon 206-a. Similarly, the inn radius R 2b of prostate tissue 202 with inflated prostate ballo 206-b is significantly larger than the corresponding radi distance R 2a with deflated prostated balloon 206-a. However, particular significance is that, because prostate tissue is so and compressible, the difference between the outer and inn radii R 3b and R 2b of prostate tissue 202 with inflated prosta balloon 206-b is- substantially reduced with respect to t corresponding difference between radii R 3a and R 2a with deflat prostate balloon 206-a. Thus, both the variation in t respective microwave field intensities heating any part of t intervening non-prostate tissue and heating any part of t diseased prostate tissue and the variation in the respecti microwave field intensities heating the more proximate and mo distal prostate tissue are significantly reduced by the use of inflated prostate balloon. This makes it possible to heat t prostate tissue more evenly and to higher therapeutic tempera tures without heating any part of the non-prostate tissue beyo its maximum safe temperature. Obviously, increasing the microwave power radiated fro the microwave antenna will tend to increase the respectiv temperatures reached by both the prostate tissue and th intervening non-prostate tissue. The modification of th urethral catheter shown in Figure lc makes it possible t increase the microwave power, to thereby increase the therapeuti temperatures reached by the more distal parts of the disease prostate tissue without overheating the more proximate parts a the prostate tissue or any part of the intervening non-prostat tissue lining the urethra. The modification comprises replacin single prostate balloon lumen 124 of Figure lb with both prostat balloon inlet lumen 128 and prostate balloon outlet lumen 130 o Figure lc. This permits the pumped fluid (e.g., radio-opaq liquid) inflating prostate balloon 122 to be circulated ther through and act as a coolant for removing heat preferential from the non-prostate tissue adjacent thereto. Either or both inlet and outlet lumens 128 and 130 may be associated with prostate balloon inflation valve 126, shown in Figure 1, whi may be operated by a thermostat that controls the circulation the coolant in a manner to maintain the non-prostate tissue at temperature near, but never exceeding, its maximum safe temper ture. As is known, prostate disease is often treated wit microwaves applied to the prostate tissue from the patient' rectum by means of a bulb applicator. A diseased prostate, whic is enlarged, tends to form a bulge which protrudes into th patient's rectum. A problem with such a bulb applicator is tha its insertion into the rectum tends to push aside the protrudin bulge, which is quite painful to the patient. The recta catheter shown in Figure 3, which forms a second embodiment o the present invention, overcomes this problem. In addition, th rectal catheter shown in Figure 3 also possesses the advantage of the urethral catheter, discussed above. More particularly while the structure of the rectal catheter is generally simila to that of the urethral catheter discussed above (either with o without the modification shown in Figure lc) , it differ therefrom in several ways. First, the rectal catheter has larger diameter bore 300 in order to properly fit the rectum Second, because an inflated balloon is elastic, prostate balloo 302, when inflated, forms a bowl 304 that stretches to substan tially conform to the bulge of the enlarged prostate protrudin into the patient's rectum (rather than being circumferentiall symmetrical like the urethral catheter discussed above). Third, because the prostate is located only on one side of the rectum, microwave antenna 306 (energized through transmission line 318) is situated off axis, closer to the prostate, so that th prostate tissue and the intervening non-prostate tissue betwee the prostate and rectum is preferentially irradiated with resp to the irradiation of the remaining, non-prostate tissue surrou ing the rectum. A more complex antenna means incorporatin directional microwave antenna (which may be comprised of reflector, director and/or phased array) may be utilized further preferentially irradiate the prostate tissue. Furth such a directional antenna need not necessarily be situated axis in order to preferentially irradiate the prostate tissu Figures 3a and 3b, taken together, show an example a rectal catheter employing a directional microwave ante comprised of reflector 320 partially surrounding centra located microwave antenna 306 and positioned to preferentia irradiate the prostate tissue. Figures 3c and 3d, taken together, show an example a rectal catheter employing a directional microwave ante comprised of a phased array made up of a power splitter 322, f phase shifters 324 and four antenna elements 326. Power split 322 distributes the microwave power applied through transmiss line 318 to each of the four antenna elements 326 through one the four phase shifters 324. Each of the four phase shifters appropriately adjusted to cause the four antenna elements 326 emit a shaped radiation pattern 328 that preferentially irra ates the prostate tissue. In practice, the rectal catheter is inserted into rectum of the patient with its prostate balloon 302 in a defla state. This substantially eliminates the pain that the pati felt when a bulb applicator was inserted. Before inflat prostate balloon 302, it is oriented in substantial cooperat relationship with the bulge of prostate tissue and interven non-prostate tissue. Therefore, slow inflation of prost balloon 302 results in the creation of a bowl portion 304, wh first conforms to the bulge, and then slowly compresses both prostate tissue 310 and that non-prostate tissue 308 wh intervenes between prostate tissue 310 and bowl portion 304 10 inflated prostate balloon 302, to finally reach the state show in Figure 3, without any substantial discomfort to the patient. Microwave power transmitted from two or more separate antennas may be used to simultaneously irradiate the disease prostate of a patient. Thus, both the urethral and rectal catheters disclosed herein may be used at the same time to treat prostate disease. In fact, some or all of the irradiating microwave power may originate from outside of the patient's body, so long as squeezing pressure is then being applied to the prostate, preferably from the urethra, in accordance with the principles of this invention. In addition to the advantages of the present invention discussed above, it is believed that the simultaneous application of both squeezing pressure and heat to an enlarged prostate cooperate synergistically to effect a significantly more lasting deformation (i.e., reduction in size) of the enlarged prostate for a prolonged period of time after the heat and pressure have been removed, than could be obtained by the use of either squeezing pressure or heat alone.

Claims: What is claimed is: 1. In a catheter adapted to be inserted into a orifice of a male patient for treating prostate disease, wherei said catheter comprises means including microwave antenna mean for irradiating said patient's prostate with a given distributio of microwave field intensity, thereby to heat tissue of sai patient to a temperature which tends to vary as a direct functio of microwave power and as an inverse function of the distance o that tissue to said microwave antenna means, and wherein th maximum microwave power to be employed is limited to an amount a which the temperature of the patient's heated tissue mos proximate to said microwave antenna means does not exceed a give safe maximum temperature; the improvement wherein said cathete further comprises: an inflatable balloon (1) which is adapted to be in deflated state while said catheter is being inserted into sai orifice, (2) which is located in said catheter at a positio which is in cooperative relationship with said patient's prostat when said catheter is fully inserted, and (3) which is adapted t be inflated when said catheter is fully inserted for applyin squeezing pressure to both prostate tissue and that non-prostat tissue situated between said inflated balloon and said prostat tissue, thereby increasing the minimum distance between heate tissue of said patient and said microwave antenna means; whereby the maximum microwave power may be increase without exceeding said given maximum safe temperature and th temperature differential between the heated prostate tissue mor proximate to said microwave antenna means and the heated prostat tissue more distal to said one microwave antenna means i reduced. 2. The catheter defined in Claim 1, wherein sai orifice is said patient's urethra, and wherein: said balloon, when inflated, forms a circumferentiall symmetrical toroid that extends around the entire circumferenc of said catheter for applying substantially equal squeezi pressure to the surrounding prostate tissue, thereby effective increasing the internal diameter of said prostate; and said microwave antenna means is located substantial on the central axis of said catheter for applying a substantiall angularly uniform distribution of microwave field intensity t said prostate tissue. 3. The catheter defined in Claim 2, wherein: said catheter further comprises a lumen and a secon inflatable balloon disposed at the end of said catheter which i in cooperative relationship with the patient's bladder when th catheter is fully inserted, for securing said catheter to sai bladder when said second balloon is inflated and permitting urin to be transported through said lumen to the outside of sai patient's body. 4. The catheter defined in Claim 3, wherein: said catheter further comprises means including second lumen for circulating a coolant for removing hea generated by said microwave power, whereby the maximum microwav power may be increased to heat the prostate tissue more dista from said microwave antenna means to a higher temperature withou concurrently exceeding said given safe maximum temperature fo the patient's heated tissue most proximate to said microwav antenna means. 5. The catheter defined in Claim 1, wherein sai orifice is said patient's rectum, and wherein: said means including said microwave antenna means comprises distribution means for providing a distribution of microwave field intensity that preferentially heats said patient's tissue in a direction towards said patient's prostate more than said patient's tissue in a direction away from said patient's prostate. 6. The catheter defined in Claim 5, wherein: said microwave antenna means is offset from the axis o said catheter in a direction adapted to be oriented toward sai patient's prostate when said catheter is fully inserted in sai patient's rectum. 7. The catheter defined in Claim 5, wherein: said microwave antenna means includes a reflecto adapted to be oriented to provide said distribution of microwav field intensity when said catheter is fully inserted in sai patient's rectum. 8. The catheter defined in Claim 5, wherein: said microwave antenna means includes a phased arra adapted to provide said distribution of microwave field intensit when said catheter is fully inserted in said patient's rectum. 9. The catheter defined in Claim 5, wherein: said balloon, when fully inserted and inflated, i configured to substantially conform to a bulge in the patient' rectum caused by an enlarged prostate. 10. The catheter defined in Claim 5, wherein: said catheter further comprises means including second lumen for circulating a coolant for removing hea generated by said microwave power, whereby the maximum microwav power may be increased to heat the prostate tissue more dista from said microwave antenna means to a higher temperature withou concurrently exceeding said given safe maximum temperature fo the patient's heated tissue most proximate to said microwav antenna means. 11. The catheter defined in Claim 1, wherein: said balloon is inflated with a radio-opaque liquid whereby the position of said balloon with respect to sai patient's prostate can be monitored when said catheter inserted in said patient's orifice. 12. A method for treating prostate disease of patient, said method comprising the steps of: applying squeezing pressure to non-prostate tiss which surrounds an orifice of the patient in the vicinity of t patient's prostate thereby to compress the prostate; and while said pressure is being applied, irradiating sa prostate with microwave power sufficient to heat that prosta tissue which is more distal to said orifice to a first therape tic temperature without heating any non-prostate tissue of t patient above a maximum safe temperature. 13. The method defined in Claim 12, wherein: the step of applying squeezing pressure compris applying squeezing pressure to that non-prostate tissue whi surrounds the patient's urethra thereby to increase the diamet of said urethra; and the step of irradiating said prostate includes the st of irradiating said prostate from said urethra. 14. The method defined in Claim 13, further comprisi the step of: while said pressure is being applied to said tiss surrounding said patient's urethra and said prostate is bei irradiated with microwave power from said patient's urethr irradiating said patient's prostate from a position outside said patient's urethra through second non-prostate tissue that situated between said outside position and said prostate tiss with additional microwave power, said additional microwave pow being sufficient to heat that prostate tissue which is mo distal to said urethra and is situated between said patient' urethra and said second non-prostate tissue to a second therapeu tic temperature that is higher than said first therapeuti temperature without heating said second non-prostate tissue abov a maximum safe temperature. 15. The method defined in Claim 13, further comprisin the steps of: while said pressure is being applied to said tissu surrounding said patient's urethra, applying additional squeezin pressure to tissue of the patient's rectum in the vicinity of th patient's prostate; and while said prostate is being irradiated with microwav power from said patient's urethra, irradiating said patient' prostate from said patient's rectum with additional microwav power sufficient to heat that prostate tissue which is mor distal to said urethra and is situated between said patient' urethra and rectum to a second therapeutic temperature that i higher than said first therapeutic temperature without heatin non-prostate tissue proximate to said patient's rectum above maximum safe temperature.

Inventors: STERZER FRED, STERZER, FRED
Applicants: MMTC INC, MMTC, INC.
Application year: 1991
Main classification: A61N5
IPC codes: A61B17, A61B18, A61M25, A61M29