Prostatic disease is one of the most common diseases in men in the United States. Prostatic disease, as referred to here, includes benign prostatic hypertrophy (BPH), prostatitis, and prostatic cancer. These etiologies affect a majority of men over the age of 60.
Although the size of the prostate does not reflect the severity of BPH symptoms, it is clear that hypertrophy of the prostate gland and/or hyperplasia of stromal tissue cells is involved.
The currently accepted treatment for BPH is transurethral resection of the prostate (TURP). Approximately 400,000 TURPs per year are performed to treat this disorder in the United States. Morbidity and mortality for TURP are 17 and 1 percent, respectively, for all age groups. Higher complication rates occur in older populations with an annual surgical and hospitalization cost in excess of $1 billion per year.
Thus, TURP may only be applicable to patients who are not at risk for surgical complications. Among other treatments available for the condition of BPH are pharmacological means such as vasoactive and antiandrogen agents.
The etiology of prostatitis, which is an inflammation of the prostate, is not entirely known, except that in about 20% of cases, where it is bacterially induced.
With regard to prostatic cancer, both the incidence and mortality are on the rise. It is expected that over 134,000 new cases will be diagnosed this year alone, with some 33,000 cases proving fatal.
While the etiology of prostatic cancer is also not well known, it has been suggested that this disease is either biochemically or genetically induced. The symptoms of prostatic cancer are often insidious and may not be clinically manifest until the course of the disease is advanced. The current treatment of choice for prostatic cancer is surgery which may involve excision of the prostate gland.
There is a need in the field of treatment of prostatic disease, both benign and cancerous, for an effective, less invasive alternative means of treatment to the more invasive, and consequently more complicated and more dangerous surgical procedures which currently are the treatments of choice, namely, TURP for BPH and radical prostatectomy for prostatic cancer.
In prostatic diseases, reduction in the diameter of the lumen, i.e., the prostatic urethra, is externally induced by compression on the luminal wall due to the proliferation of epithelial and stromal cell tissue, which is benign in the case of BPH and cancerous in prostatic cancer. This reduction in luminal diameter causes clinical symptoms for the patient during urination. In order to be effective, treatment of BPH must cause a reduction in the mass of the prostatic tissue responsible for creating the compressive forces on the urethra which results in the obstruction of flow through the lumen of the urethra. This is accomplished either by surgical excision of the tissue or by other means which will cause changes in the cells with therapeutic effects.
The use of dilation alone has been known in the art of treatment of BPH. Dilation of a prostatic urethra which has become compressed and obstructed by external forces due to a proliferation of diseased prostate tissue cells, however, is useful in alleviating symptoms only in the short term. Unfortunately in the majority of cases it has been observed that recompression and obstruction of the prostatic urethra, accompanied by a recurrence of the symptoms, occurs within a relatively short period of time, requiring that the entire procedure be repeated, which entails considerable expense and inconvenience to the patient. Accordingly, alternative modes of therapy have been sought which can afford more long lasting or permanent cure of remission from the disease and relief of the symptoms. U.S. Pat. Nos. 4,932,956 and 4,932,958 both to Reddy et al., both for Prostate Balloon Dilator, and both assigned to the assignee of the present invention, disclose catheters which utilize balloon dilation to expand the lumen of the prostatic urethra. These two patents are incorporated herein by reference.
The use of hyperthermia alone is known in the treatment of tumors and lesions.
U.S. Pat. No. 4,662,383 to Sogawa et al. for Endotract Antenna Device for Hyperthermia discloses an apparatus incorporating a microwave radiation antenna surrounded by a balloon-like member with circulation of a cooling liquid to and from the inside of the balloon-like member, for treating endotract lesions. The balloon of this apparatus is made of a material which is deformable to form an intimate fitting with the inner surface of the wall of the tract organ. The balloon of this apparatus, therefore, cannot be used to dilate the lumen of a vessel, such as the prostatic urethra, which has become obstructed by external compression due to a hypertrophied prostate.
Similarly, published European Patent Application No. 370,890 of Technomed discloses an apparatus for the treatment of tissue, such as of the prostate, by hyperthermia. The apparatus includes means for providing hyperthermal energy, such as microwave energy supplied to and emitted from an antenna in the apparatus, together with heat protection means which generally constitutes means forming a radio-reflecting screen, and which according to certain embodiments contains a radio-reflecting liquid medium. According to some embodiments, the liquid-filled screen is a balloon at the front end of the microwave antenna. In those embodiments incorporating a balloon, however, as in Sogawa et al., the balloon is not designed to also dilate an obstructed lumen of a vessel such a an externally constricted prostatic urethra.
The combined use of dilation and hyperthermia has been suggested for treatment of obstructive atheromatous plaque in cardiovascular disease. The etiology of cardiovascular disease is, however, markedly different from that of prostatic diseases.
In cardiovascular disease the source of the obstruction of the lumen is internal to the lumen itself, namely, the deposits of atheromatous plaque on the wall of the vessel. The objective of the apparatus and methods used in the treatment of cardiovascular disease is to widen the lumen of a vessel by pushing away the internally obstructive material.
U.S. Pat. No. 4,643,186 to Rosen et al. for Percutaneous Transluminal Microwave Catheter Angioplasty, and West German Laid-Open Patent Application No. DE 3743578 A1 to Zeiher for Balloon Catheter for Recanalization of Stenoses in Body Channels, in Particular Coronary Vessels and Peripheral and Arterial Vessels, disclose catheters each having at least one embodiment thereof featuring balloon dilation to mechanically displace plaque deposits on the inner surface of a vessel wall to expand the lumen of the vessel, and the application of microwave energy to the plaque to soften, coagulate, and/or electroablate the plaque, to further expand the effective cross-sectional area of the lumen of the vessel available for flow through the vessel.
U.S. Pat. No. 4,799,479 to Spears for Method and Apparatus for Angioplasty, discloses a device utilizing balloon dilation and the application of thermal energy supplied by means of a laser. Balloon inflation is used to facilitate fusion of disrupted plaque, which, together with arterial wall tissue, is heated and fused together to form a smooth, cylindrically-shaped channel in the lumen of the vessel which is resistant to restenosis.
Hyperthermia has also been used in conjunction with chemotherapy and/or radiation therapy in cancer treatment with the expectation that the elevated temperature increases the therapeutic index. Hyperthermia is also a means for treatment of other, non-cancerous, benign conditions such as BPH and prostatitis.
From in vitro studies it has been observed that in order for hyperthermia to be effective, the temperature of all the target cells must be raised to a minimum of 42.5.degree. C. and maintained at least at that temperature for a sufficient period of time to cause cell changes. Recent in vivo studies an animals suggest that a temperature of around 48.degree. C. must be attained and maintained in target diseased tissue cells for hyperthermia to be effective.
The use of hyperthermia in the treatment of various forms of cancer, including prostatic cancer, has been attempted for some time. However, this therapy has met with only limited effectiveness due to the fact that blood flow to the target cells is not reduced and may, in fact, increase. Because of blood flow, a heat sink phenomenon occurs which reduces the thermal energy delivered to the target cells, thus reducing the magnitude and uniformity of heating and cell destruction.
Published PCT Patent Application WO 90/13333 of Intra-Sonix discloses an instrument and method for dilating a stenotic region of a passageway in the body, such as the prostatic urethra. Selected portions of prostate tissue are compressed, such as by using a balloon inserted in the prostatic urethra to enhance hemostatis, and selected portions of the compressed tissue are denatured, such as by exposure to laser energy. The pressure to which the balloon of this apparatus is inflated is just sufficient to compress the prostate tissue without necessarily exceeding the elastic limit of the tissue, as is required in a balloon dilation procedure.
Another previously known device has sought to combine dilation with microwave hyperthermia.
U.S. Pat. No. 5,007,437 to Sterzer for Catheter for Treating Prostate Disease discloses a urethral and/or rectal catheter incorporating an inflatable prostate balloon to compress the prostate while it is being irradiated from a microwave antenna. The apparatus is said to enable an increase in the therapeutic temperature to which the prostate tissue distal to the microwave antenna can be heated without heating any non-prostate tissue beyond a maximum safe temperature, and reduces the temperature differential between the heated prostate tissue more distal from and more proximate to the microwave antenna. The catheter includes a Foley balloon near the distal end of the catheter, forward of the prostate balloon, to fix the catheter in place.
Published PCT Patent Application WO 91/11975 of Technomed discloses an apparatus for the treatment of tissue, such as of the prostate, by hyperthermia and includes means for dilation. This apparatus includes means for providing microwave energy for hyperthermia, a dilation balloon toward the distal end of the apparatus, and fixation balloons both distal and proximal to the dilation balloon. The forward fixation balloon, distal to the dilation balloon, is positioned in the bladder. The dilation balloon is used to dilate the prostatic urethra, however, the disclosure suggests that dilation is used principally to dilate the lumen to compress tissue between the lumen wall and more remote tissue to be treated by hyperthermia. Nothing is disclosed about the ability of the dilation balloon to also dilate the bladder neck in the treatment of prostate disease.
It is desirable to have an alternative apparatus and method of treatment that is readily adaptable for use in the treatment of any condition in which it is desired to simultaneously hyperthermally treat diseased target tissue in a patient and dilate a lumen of a patient which is being compressed and obstructed by diseased tissue and/or surrounding tissue, particularly, such as exists in diseases of the prostate, and in certain tumors of the esophagus and the gastro-intestinal tract; and which is less invasive than surgery, is capable of producing longer term results than dilation alone, and overcomes the limited effectiveness of previously known devices and methods which utilize hyperthermia either alone or in combination with dilation, by overcoming the heat sink phenomenon, and by enabling dilation of an obstructed lumen to produce a dilated condition of the lumen which will persist for a time after removal of the apparatus from the lumen. In the case of treatment of prostate disease, in particular, it is desirable to provide an apparatus which is capable of providing hyperthermal therapy, while also simultaneously dilating both the prostatic urethra and the bladder neck.
Accordingly, it is an object of the present invention to provide an apparatus and method for the treatment of conditions in which it is desired to simultaneously hyperthermally treat diseased target tissue in a patient and dilate a lumen of a patient which is being compressed and obstructed by diseased tissue and/or surrounding tissue. It is another object of the present invention to fill the need in the art of treatment of prostate disease with an apparatus and a method for its use that combines the use of hyperthermia together with the use of balloon dilation for the treatment of both benign and cancerous forms of prostate disease, and other conditions and diseases resulting in an enlarged prostate, to achieve both the short term benefits of dilation therapy and the long term benefits of hyperthermal therapy. It is still another object of the present invention to provide an apparatus and method for the treatment of prostate diseases, which in delivering dilation mode therapy, is capable of simultaneously dilating both an obstructed prostatic urethra and the bladder neck to relieve the symptom of inability to urinate characteristic of prostate diseases. It is a further object of the present invention to provide an apparatus and method which combines the two treatment modalities of hyperthermia and dilation in such a way that the heat sink phenomenon associated with hyperthermal treatment is reduced and a synergistic result is obtained. It is a still further object of the present invention to provide an apparatus which is an improvement over previously known apparatus in that it is easier and more economical to construct, and is partially reusable, requiring only replacement of the outer parts which come in patient contact.
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