HK1004381B - Apparatus for intraluminal treatment of a selected area of the body of a patient - Google Patents

Description

Intraluminal device for treating selected sites in a patient

Technical Field

The present invention relates generally to the delivery of therapeutic compositions to a selected site in a patient's vascular system via a catheter. More particularly, the present invention relates to methods and apparatus for delivering a treatment element, such as a radioactive source, through a catheter to a desired site, such as the coronary artery, to inhibit wound healing responses, such as restenosis following balloon angioplasty.

Background

It is well known that the healing response of the human body to a wound generally involves the formation of what is commonly referred to as scar tissue. This response also occurs in the vascular system after injury to a human blood vessel. Lesions that can cause scar tissue formation can occur at different locations in the vascular system, such as at the carotid artery or at a coronary branch, or in different ways, such as trauma occurring during surgery or diagnosis.

In the case of such lesions, one area of particular interest in the vascular system is the coronary arteries, as it is subjected to a treatment process in order to remove or reduce the blockage caused by plaque in the arteries. Coronary arteries are well known and frequently encountered in the medical community as a result of partial or complete occlusion of atherosclerotic plaques formed therein. Such a problem can be dealt with by the following method: using an Atherectomy (Atherectomy) device, which mechanically removes plaque; using a hot or cold laser, which vaporizes the plaque; stents (Stents) are used, which allow the artery to open; other devices and procedures are used with the purpose of increasing the circulation of blood in the artery. The most commonly used of the latter procedures is the percutaneous transluminal angioplasty (PTCA) procedure, which is more commonly referred to as balloon angioplasty. In this procedure, a catheter with an inflatable balloon at its distal end is introduced into the coronary artery, the balloon not yet inflated being located at the stenosis of the artery, and the balloon is then inflated. The ballooning of the balloon separates plaque from the arterial wall, flattens the wall, and also expands the wall, thereby enlarging the passageway within the lumen and increasing blood flow. After inflation, the balloon is deflated and the balloon catheter is removed.

PTCA is a widely used process with initial success rates between 90% and 95%. The long-term success rate of PTCA (and other arterial dilation procedures mentioned above) is very limited, mainly by the occurrence of restenosis, or what is known as restenosis of the intraluminal passageways through the arteries. About 30% -50% of patients experience this restenosis within 6 months after PTCA, i.e., when the vascular access size is about 50% or less narrower than the enlarged size. Restenosis occurs for a number of reasons, but it is now believed that the most prominent cause of restenosis is a natural healing response to vascular injury caused by the expansion of an angioplasty balloon.

During PTCA, vascular injury can occur in several ways, including: exfoliation of the endothelium (a layer of flattened cells lining a blood vessel); rupture, disruption and/or rupture of atherosclerotic plaque and intima (innermost lining of blood vessels); the intima and plaque rupture from the media of the supporting vessel; stretching and tearing of the media and adventitia (the outermost coating of the artery), which can lead to the expansion of the aneurysm; and damage to vascular smooth muscle. These injuries to the blood vessels generally trigger the body's own natural repair and healing processes. During this healing process, fibrin and platelets rapidly accumulate in the endothelium, and vascular smooth muscle cells proliferate and migrate into the intima. Due to smooth muscle hyperplasia, also known as intimal hyperplasia, the scar tissue formed is believed to be the primary cause of restenosis following coronary balloon angioplasty.

Attempts have been made to inhibit restenosis in coronary arteries, including the use of various light therapies, chemotherapeutic agents, stents, atherectomy devices, hot and cold lasers, and irradiation of the stenosis. These therapies have met with varying degrees of success, but each also has certain drawbacks. Although radiation therapy is promising, particularly in inhibiting intimal hyperplasia, the devices available to deliver the radiation source to the stricture site are limited and their disadvantages limit its application. The following U.S. patents disclose such typical devices for treating restenosis using radioactivity: 5,059,166 (Fischell); 5,213,561 (Weinstein); 5,302,168 (Hess); 5,199,939 (Dake); 5,084,002 (Liprie); 3,324,847 (Zoubulis).

Summary of The Invention

It is an object of the present invention to provide a device and a method which enable one or more treatment units, for example a radiation source, to be delivered to a desired site in a patient's vascular system via a catheter, and which enable the treatment unit to be removed, if necessary, via the catheter. The present invention is particularly, but not exclusively, useful for treating coronary arteries that have been or will be subjected to PTCA procedures or other arterial dilation procedures in order to inhibit intimal hyperplasia and reduce the risk of restenosis. The invention is also applicable to other regions of the vascular system, such as the carotid artery or coronary branches.

More specifically, as set forth in the claims, the present invention comprises an elongated flexible catheter having a proximal portion configured to be located outside the patient's body, a distal portion configured to be positioned at a selected location in the patient's vasculature, and a lumen therebetween, the catheter having a diameter sufficiently small to permit insertion of the catheter into the patient's vasculature. The catheter is preferably, but not necessarily, configured to be advanced over the guidewire to its distal end and positioned at the desired location. The proximal end of the catheter is provided with an introduction port through which a blood-compatible liquid is introduced into the lumen from the liquid source. One or more treatment units are positionable in the lumen and movable between the proximal and distal ends under a pushing force generated by the fluid flowing through the lumen, and the treatment units may be solid capsules or pellets, such as capsules or pellets containing radioactive material.

The present invention also provides a method of treatment of a selected site in a patient's vascular system using an elongate flexible catheter having a proximal portion configured to be located outside the patient's body and a distal portion configured to be positioned at the selected site in the patient's vascular system with a lumen therebetween, the catheter having a diameter sufficiently small to allow insertion of the catheter into the patient's vascular system. The catheter is preferably, but not necessarily, configured to be introduced over the guidewire until its distal end is positioned at the selected site. An inlet port in communication with the first lumen is configured to introduce a blood-compatible liquid into the lumen. One or more treatment units, such as capsules or pellets containing radioactive material, are introduced into the lumen through the proximal end of the catheter and moved from the proximal end of the catheter through the lumen to the distal end at the selected site under the urging of the treatment elements by the fluid flowing through the lumen, thereby moving the treatment units from the proximal end to the desired site at the distal end. The treatment unit may be left at the distal end long enough to treat the selected site, and during this long enough time the remainder of the catheter does not contain the treatment unit, so that other tissue does not have to undergo such treatment. After the treatment is completed, the catheter is removed from the patient.

In another embodiment, the invention is practiced with an angioplasty balloon catheter having a proximal end and a distal end with a lumen therebetween. The lumen is in communication with an inflatable balloon at the distal end. According to the present invention, one or more treatment units, such as a capsule or pellet containing a radioactive material, may be either fixedly loaded within the balloon or moved through the lumen from the proximal end to the distal end to deliver the radiation component to the stenotic site, as is actually done in angioplasty procedures, thus making a two-step procedure necessary and now possible in one step. From the above brief description of the invention it is clear that the method of the invention can be applied before, during or after the angioplasty procedure, so that the treating physician can choose a time which he considers optimal to carry out the method of the invention.

Drawings

Embodiments of the present invention will now be described in detail with reference to the accompanying drawings.

FIG. 1 is a schematic view of a catheter-based treatment delivery system of the present invention;

FIG. 2A is a cross-sectional view of a proximal portion of one embodiment of the treatment delivery system of the present invention;

FIG. 2B is a cross-sectional view of another embodiment of the treatment delivery system of the present invention;

FIG. 2C is a cross-sectional view of yet another embodiment of the treatment delivery system of the present invention;

FIG. 3 is a cross-sectional view of one embodiment of a treatment unit of the present invention;

FIG. 4 is a partial cross-sectional view of one embodiment of an elongate catheter of the present invention, showing a treatment unit at the distal end of the catheter;

FIG. 5 is a partial cross-sectional view of a second embodiment of an elongate catheter of the present invention, showing a treatment unit at the distal end of the catheter;

FIG. 6A is a partial cross-sectional view of a third embodiment of an elongate catheter of the present invention, showing a treatment unit at the distal end of the catheter;

FIG. 6B is a partial cross-sectional view of the embodiment of FIG. 6A of the elongate catheter of the present invention disposed within an outer catheter which may be used to position the catheter of the present invention within a patient;

FIG. 7A is a partial cross-sectional view of a fourth embodiment of an elongate catheter of the present invention, showing a treatment unit at the distal end of the catheter;

FIG. 7B is a partial cross-sectional view of the elongate catheter of FIG. 7A taken along line 7-7B in accordance with the present invention;

FIG. 8A is a partial cross-sectional view of a fifth embodiment of an elongate catheter of the present invention, showing a treatment unit at the distal end of the catheter;

FIG. 8B is a partial cross-sectional view of a modified embodiment of the elongate catheter of FIG. 8A showing the treatment unit at the distal end of the catheter in accordance with the present invention;

FIG. 9 is a partial cross-sectional view of a sixth embodiment of an elongate catheter of the present invention, showing a helical coil or ring-shaped treatment unit at the distal end of the catheter;

FIG. 10A is a partial cross-sectional view of another embodiment of the invention with an inflatable balloon and treatment unit fixedly disposed at the distal end portion;

FIG. 10B is an end view of the catheter shown in FIG. 10A;

FIG. 11 is a partial cross-sectional view of yet another embodiment of the present invention having an inflatable balloon with a treatment unit disposed therein;

FIG. 12 is a partial cross-sectional view of yet another embodiment of the present invention having an inflatable balloon with a treatment unit moving along the catheter;

FIG. 13 is a partial cross-sectional view of yet another embodiment of the present invention having an inflatable balloon with a treatment unit moving along the catheter;

FIG. 14 is a partial cross-sectional view of another embodiment of the treatment delivery system of the present invention;

FIG. 15A is a partial cross-sectional view of yet another embodiment of the treatment delivery system of the present invention;

FIG. 15B is a partial front view of the proximal end of the treatment delivery system shown in FIG. 15A;

FIG. 15C is a cross-sectional view taken along line 15C-15C of FIG. 15A;

FIG. 16 is a partial cross-sectional view of various components of yet another embodiment of the treatment delivery system of the present invention;

FIG. 17 is a partial cross-sectional view of yet another embodiment of the present invention having an inflatable balloon with a treatment unit moved along the catheter;

FIG. 18 is a partial cross-sectional view of yet another embodiment of the present invention having an inflatable balloon with a treatment unit moving along the catheter;

figure 19 is a partial cross-sectional view of yet another embodiment of the present invention having an inflatable balloon with a treatment unit moving along the catheter.

Detailed description of the invention

Fig. 1 shows an embodiment of the invention in a schematic overview in order to make the invention easier to understand. Fig. 1 shows an elongated catheter 2 having a proximal portion 4, a distal portion 6, and at least one lumen 8 therebetween. The catheter is sized so that its distal portion can be inserted into the vascular system of a patient and passed through the vascular system to a selected site to be treated, such as the site of a balloon angioplasty procedure in a coronary artery, or other incisional procedure, such as the site of a coronary atherectomy. Insertion and advancement of the catheter may be performed, for example, by percutaneously inserting the catheter into the femoral artery, advancing the catheter over the guidewire 10 up through the descending aorta, over the aortic arch, and then advancing the catheter down through the ascending aorta and into a selected specific portion of the coronary artery to be treated, such as where the coronary artery has undergone a PTCA procedure or other arteriotomy. The guide wires and procedures used in advancing such catheters to the site where angioplasty is to be performed are well known and will not be described in detail herein.

In the above-described percutaneous procedure, the proximal end of the catheter is placed outside the patient's body, and a delivery and/or charging device 12 is provided at this proximal end to charge a therapeutic unit, such as a pellet or capsule containing or consisting of a radioactive material, into the lumen 8 of the catheter 2. Additional treatment units may also be added, such that the total length of the combined treatment units should at least correspond to the length of the stenotic site of the vasculature to be treated. The overall length of the combined treatment unit may also be longer than the stenosis in order to ensure that the distal edge of the stenosis is also treated. This attachment may be performed manually, but preferably a mechanical attachment, as described in more detail below, is used to better protect the user from radiation damage.

After the treatment unit is added to lumen 8, a pressurized, blood compatible liquid, such as sterile saline or sterile water, is introduced into the proximal end of the lumen from introduction port 16 through liquid source 14, and subsequently after the treatment unit. The flow of the fluid through the lumen propels the treatment composition along the lumen to a distal portion at the site to be treated. The fluid that provides the driving force for the advancement of the treatment unit can be expelled from the distal end of the catheter, or it can be returned from another parallel lumen provided in the catheter, or from the same lumen through which the treatment unit flows by aspiration.

After the treatment unit is located at the desired site, it may remain at the site long enough to treat the tissue. For the treatment of stenotic sites by radiotherapy, the treatment unit is preferably a beta radiation source, with a relatively short dwell time, of the order of a few minutes, as will be described in more detail below.

After the treatment is completed, the catheter may be removed with the treatment unit remaining at its distal end, or if desired, the fluid may be forced back through the lumen before the catheter is removed, thereby causing the treatment unit to flow back to the proximal end and into the loading device. Reverse flow of the liquid may be achieved by reverse flow of the liquid along the lumen under positive pressure or by suction, such as pulling a syringe plunger mounted at the proximal end of the lumen.

The delivery/charging device 12 need not be directly connected to the proximal end of the catheter 2, particularly if such direct connection may cause kinking of the catheter or restrict the operation of the catheter. In this case, a length of tubing (which may have the same number of lumens as the catheter) may be added between the delivery/charging device 12 and the proximal portion 4 of the catheter. In this case, the extended length of tubing (and the proximal portion of the catheter that is outside the patient) may be shielded to protect the user and/or patient from unnecessary radiation exposure.

Fig. 2A shows a practical embodiment of the proximal end of the catheter system of fig. 1. Although the present embodiment is not limited to the case of using a radiation therapy unit, the embodiment of fig. 2A is particularly suitable for the case of using a radiation therapy unit.

Specifically, FIG. 2A shows a 3-lumen catheter system 18 with a feeding set 20 containing a treatment unit 22 and attached to the proximal end of a 3-lumen catheter 24. The charging device includes a housing 26, preferably made of a suitable hard polymer, having a proximal end 28, a distal end 30, and first, second and third apertures 32, 34, 36 extending therebetween. A connector member 38 at the distal end of the housing connects the first, second and third apertures to one of the three lumens 33, 35, 37 of the catheter 24, respectively.

An inlet, such as a Luer connector inlet, is provided at the proximal end of the housing in communication with the bores 32, 34 and 36. First introduction port 40, which is aligned with first aperture 32 of the housing, is adapted for introducing or removing a liquid, such as sterile saline. The second introduction port 42 communicates with the second aperture 34 of the housing and is also adapted to allow liquid to enter and exit the housing. The third introduction port 44 opens into the third opening of the housing and is configured to receive a guide wire 46 therein to assist in positioning the distal end of the catheter within the patient. A valve (not shown), such as a Duchen-Borst valve, may be installed at the third introduction port to prevent fluid around the lead from escaping during or after insertion of the device into the patient.

For loading and unloading the treatment unit 22, a loading device 48, for example a magazine or a loading device, is slidably arranged in a centrally arranged recess 50 at the distal end of the housing 26. The magazine, which is preferably made of the same material as the rigid housing 26, is provided with a first through hole 52 and a second through hole 54. The first and second through-holes of the magazine may be selectively aligned with the first hole 32 of the housing, depending on the lateral position of the magazine relative to the housing. It is also possible to use a magazine provided with only one through-hole.

The treatment units may be preloaded in the magazine so that the treatment units can be handled, transported and stored conveniently by disengaging the remainder of the charging device. When the user is ready, the magazine is simply inserted into the housing, which simplifies the handling of the treatment unit by the user and also reduces the contact of the user with the treatment unit. When the treatment unit is radioactive, the magazine is preferably made of a material that is sufficiently radio-opaque to protect the user from unnecessary radiation.

As shown in fig. 2A, the magazine 48 is inserted entirely within the housing 26 with the first aperture 52 of the magazine aligned with the first aperture 32 of the housing. In this position, the second aperture 54 of the magazine contains the treatment unit 22 and is located within the housing, thereby protecting the user from radiation from the treatment unit. In this first position, if desired, a liquid such as sterile saline may be introduced through the first inlet, filling the housing and conduit, and venting the gases therein.

By sliding the magazine 48 outwardly from the housing 26, the magazine is moved to a second position in which the second aperture 54 of the magazine is coaxially aligned with the first aperture 32 of the housing, and the treatment unit 22 can be fed into the conduit 24. In this second position, a pressurized liquid, such as sterile saline, can be introduced through the pump 14, through the first introduction port 40, to exert a pushing force on the treatment unit, through the second through-hole of the magazine, the first hole 32 of the housing, and finally into the lumen of the catheter.

Pump 14 may have a variety of designs, for example, pump 14 may be a simple saline filled plunger syringe mounted to introduction port 40 of housing 26 by a luer lock connector. Manual pushing of the plunger generates sufficient force to push the treatment unit to the desired location in the catheter (after treatment is complete, withdrawal of the plunger facilitates return of the treatment unit to the proximal section). The driving force may also be generated by a hanging sterile saline or a falling liquid column in a sterile water container, the flow of which is controlled by a simple roller clamp or stopcock.

Other configurations of magazines (not shown) may be used without departing from the scope of the invention. For example, the magazine may be cylindrical and/or rotatably mounted within the housing. By rotating the magazine, the through-holes or chambers in the magazine can be selectively aligned with the holes of the housing. When using the radiotherapy unit, it can be pre-loaded into the cylinder to reduce user contact and protect the user from radiation exposure. By pre-loading the radiation treatment unit 22 into the loading unit 20 or into the magazine 48 to be inserted into the loading unit, user contact with the treatment unit is reduced and, in the case of radiation treatment units, the user is protected from radiation.

Figure 2B shows another embodiment of the catheter system of the present invention. The conduit system 56 includes a charging device and pump combination 58 and a multi-lumen conduit 60. The charging device and pump combination 58 includes a housing portion 62 having a proximal portion 64 connected to the elongate conduit and a distal portion 66 fitted with a connector for fluid communication with a passage defined in the housing.

The housing portion 62 has a central opening or passage 68 in which the treatment unit is placed before and after treatment. The central bore 68 communicates directly with one of the lumens of the multi-lumen catheter 60. The discharge of the treatment unit from the bore 68 is controlled by a valve 70 which is movable between positions which prevent or allow the passage of fluid through the bore. Alternatively, the valve is provided with an opening of sufficiently small size to allow the passage of liquid therethrough, while blocking the passage of the treatment unit when the valve closes the central opening. This helps to fill the treatment unit into place in the air if required.

A pair of piston-cylinder devices are provided on opposite sides of the housing portion 62 to provide pressurized flow of fluid to deliver the treatment unit to and from the distal end of the catheter 60. The fluid flow provided by the piston-cylinder device 72 causes the treatment unit to be carried to the distal end of the catheter 60, while the reverse fluid flow provided by the piston-cylinder device 74 causes the treatment unit to be withdrawn therefrom.

An internal passage 76 in the housing 62 communicates with the fluid inlet port 78, the central bore 68 and the cylinder carrying the piston-cylinder arrangement 72, and provides fluid flow to carry the treatment unit to and along the main lumen of the catheter 60. A one-way ball valve 80 is provided in the inner passage to allow liquid to enter from the inlet port but to prevent liquid from exiting from the inlet port. For good filling, venting can be provided from the internal passage 76 through the vent 79 when liquid is added, and a pressure relief valve can be provided to prevent over-pressurization of the conduit.

An internal passage 82 in the housing 62 communicates between the cylinder of the retrieval piston-cylinder device 74 and the return lumen of the conduit 60. At the distal portion of the catheter, the return lumen communicates with the main lumen to provide a closed circuit for delivery and retrieval of the fluid from the treatment unit.

In addition, the housing 62 has a third internal passage 84 that communicates between a guidewire input port 86 and a guidewire lumen of the catheter 60. The catheter, by itself, may not have sufficient strength or torsional rigidity to be inserted along a tortuous, long length of vascular tubing (as is the case in typical angioplasty procedures), with a distance of about 3-4 feet (90-120 cm) between the percutaneous point of traversal and the coronary artery. In order to effectively locate the distal end of the catheter at the desired site, the catheter may be advanced over a guidewire which is pre-inserted at the desired site by methods well known to medical personnel performing angioplasty or similar procedures. A dug-bolster valve or similar known device is preferably provided at the guidewire input port to seal the guidewire input port around the guidewire to prevent blood or other fluids from escaping the lumen of the guidewire.

In practice, the internal passage, the piston-cylinder arrangement, and the main and return lumens of the catheter are filled with sterile water or saline from the fluid inlet port 78 and the one-way valve 80. In the initial position, the carry and retrieve piston-cylinder arrangements are positioned opposite, with the piston of the carry piston-cylinder 72 in a pulled out position and the piston of the retrieve piston-cylinder 74 in an advanced position, as shown in fig. 2B. The valve 70 controlling the central opening must be opened before the treatment unit can reach the desired site.

By advancing the delivery piston, the fluid in the delivery cylinder is pushed out through the internal passage 76 and into the central bore 68 containing the treatment unit 22. The pressurized flow of liquid pushes the treatment unit out of the central bore and along the main lumen of the catheter to the distal portion at the treatment site. As the fluid travels distally along the main lumen, it also displaces an equal amount of fluid, causing it to flow back along the return lumen and into the retrieval piston-cylinder device 74, pushing the retrieval piston outward.

Retrieval of the treatment unit may be accomplished with the reverse of the steps described above. The retrieval piston is advanced to force fluid along the return lumen in a reverse or super-distal direction and return fluid along the main lumen to the housing. The flow of liquid pushes the treatment unit along the main lumen in the direction of rotation or in the proximal direction, returning the treatment unit to the central aperture of the housing 62. The scavenged liquid enters the cylinder carrying the piston-cylinder device 72.

The catheter system shown in fig. 2B provides a totally enclosed system so that fluid contacting the treatment unit cannot enter the patient's body. This is particularly important when the therapeutic agent is radioactive. This closed system configuration also allows the treatment unit, either individually or in a string, to move slightly back and forth while at the distal end of the catheter by alternately pushing slightly on the delivery piston and the retrieval piston. The application of this method allows a more uniform irradiation of the selected vessel region, especially if there is a dead space between or at the ends of the treatment units.

The catheter system shown in fig. 2C is a variation of fig. 2B. Similarly, the catheter system 88 includes a loading unit and pump combination 90 and a multi-lumen catheter 92. The charging device and pump combination 90 also includes a housing portion 94 having a distal portion 96 and a proximal portion 98, the distal portion being connected to the conduit 92. However, in this embodiment, the liquid inlet 100, the wire inlet 102, and the carry and retrieve bellows 104, 106 are each located on one side of the housing 94. This arrangement allows for a larger cylindrical chamber 108 from the proximal end of the housing inward for receiving a carrier or tray 110 pre-loaded with treatment units 22. Alternatively, the housing 94 and the tray 110 may be a single piece, or of unitary construction.

The hub 110 has a central opening 112 for receiving the treatment unit, a valve 114 for controlling the treatment unit, and a central opening lateral branch 116. When the insert plate 110 is inserted into the chamber 108 of the housing 94, the central passage, in which the hole 112 is aligned with the central passage 118 of the housing 94, communicates directly with the main lumen of the duct 92, while the branch hole 116 connects with the liquid introduction port 100 and the conveying bellows 104.

Alternatively, the insert plate 110 may be provided with a plurality of apertures and rotatably mounted in the housing with the apertures selectively aligned with the introduction port 100 and the central passageway. In this configuration, one port may be empty for rapid filling of the system, while another port may be loaded with a treatment unit.

As in the embodiment of FIG. 2, the housing 94 also has an in-stream passage 122 communicating between the retrieval bellows and the return lumen of the catheter 92, with a guidewire passage provided between the guidewire lumen of the catheter and the guidewire introduction port 102. Also similarly, an exhaust vent 126 is provided which communicates with a passage connected to the liquid inlet 100.

The operation of the catheter system shown in fig. 2C is substantially the same as that of fig. 2B. The embodiment of fig. 2C allows the treatment unit to be conveniently stored off the rest of the catheter system, for example in a special container which is radiation proof.

It must be clear that in each of the above embodiments the housing, the load carrier (tray or magazine) and the conduit can be assembled in different combinations. For example, the housing and the carrier may be pre-assembled together, or even be of one-piece construction. Similarly, the housing may be preassembled with the catheter and the carrier separated to allow convenient storage and delivery of the therapeutic composition. Alternatively, all three components are separate and assembled in the desired configuration on site, which allows the medical professional to select the appropriate combination depending on the desired surgical procedure.

If the treatment site is to be irradiated radioactively, the treatment unit must contain a radioactive substance, preferably beta-radioactive. In the preferred embodiment shown in fig. 3, the treatment unit is an elongated hollow cylindrical tube 128, preferably made of stainless steel, silver, titanium or other suitable material, and desirably having a length in the range of 2.5-5.5 mm. The tubular treatment unit has two rounded ends with a chamber 130 between the ends. The inner diameter of the chamber is preferably in the range of 0.4-0.6 mm. A first end plug 132 closes the first end of the tube and a second end plug 134 closes the second end. The end plug is preferably less than about 1 mm wide and is secured to the round tube 128 by, for example, welding.

The treatment unit preferably has an outer diameter of about 0.6-0.8mm, but is of course sized so that it can be slidably received in the respective receiving holes of the magazine, housing and catheter lumen. To ensure maximum mobility in the feeding device and catheter, the inner diameter of each channel or lumen through which the treatment unit passes is preferably less than half the outer diameter of the treatment element of the barrel, and the surface of the treatment unit may be coated with Teflon (Tef1on) material or similar low coefficient of friction material to reduce friction between the treatment unit and the wall of the lumen as it passes through the lumen. In this way, the treatment unit can be quickly passed through the lumen, minimizing unnecessary exposure of other tissue to the treatment unit, particularly to radiation. In addition, to increase the area of the surface of the treatment element that receives the pushing force (generated by the fluid flowing through the system), one or more annular ridges are provided on the treatment element that project outward from the circumference of the treatment element.

To treat a length of vascular tissue, a plurality of treatment units may be used in a string, as shown in the drawings. To maintain uniform spacing between the treatment elements and, more importantly, to prevent the treatment elements from becoming too far apart during the treatment element catheter procedure, the individual treatment elements may be connected by a hard tempered spring wire 136, as shown in fig. 3.

Each of the treatment cells 22 of the above-described construction encloses a composite therapeutic agent, such as a radioactive material 138. The radioactive material 138 is loaded into the interior chamber 130 of the treatment unit and may be comprised of any material that emits alpha, beta, and gamma particles. However, the radiation source is preferably a pure beta particle source, or beta and gamma sources. Such materials include, for example, strontium 90, ruthenium 106, phosphorus 32, iridium 192, and/or iodine 125.

The amount and intensity of the radioactive material contained in the plurality of combination therapy units should be sufficient to give the desired dose of 100 to about 10,000 rads, preferably about 700 and 5,000 rads, in about 2 to 10 minutes. Radioactivity is generally measured in "Curie" (Ci) units to determine the radioactivity of the selected material of the invention to provide the above-described dose. To obtain an optimal dose, the radioactive material has a radioactivity of about 0.45-25,000 millicuries per centimeter of vessel to be treated, depending on the radioactive source used. It has been briefly mentioned above that when a string of treatment units is used, there is a dead space (non-radioactive region) between adjacent units, either by moving the catheter slightly back and forth, or by briefly and repeatedly reversing the direction of the fluid flow, so that the string of treatment units is moved back and forth, thereby providing more uniform radiation exposure to the selected site on the blood vessel.

The selected radioactive material may be contained in glass, in a metal foil or in a ceramic, or alternatively, the material may be contained in a powder or liquid medium, for example as particles in a liquid suspension. When a solid material is used, it preferably has an outer diameter of about 0.5 mm so that it can be inserted into the central cavity 130 of the barrel 128 of the treatment unit. The radioactive material may be in the form of pellets, spheres and/or rods for placement into the chamber of the treatment unit.

Various treatment units may be employed to load the radioactive material without departing from the scope of the present invention. For example, the treatment unit may be helical, spherical, or elongated annular, in which case the radioactive material is actually doped into the metal to the desired shape. Alternatively, the radioactive powder may be heated to a molten material, which is formed into the desired shape, and then encapsulated in metal, such as titanium, stainless steel or silver, or in plastic by dipping into a molten or uncured plastic. In other embodiments, the treatment unit 22 may be made of ceramic that has been saturated with a radioactive solution. In yet another embodiment, treatment unit 22 may be formed as a two-half hollow round tubular capsule, one half having a larger diameter with a cavity and the other half having a smaller diameter, also with a cavity, with the smaller diameter being slid into the larger diameter half and then bonded or welded to form the complete capsule structure.

The conduit of the present invention will now be described in more detail, and may be pre-attached to the charging device as previously described, or, as shown in figure 2, may be provided with a fitting 38 for connecting the elongated conduit to the charging device. Although the catheters of the present invention vary in the number of lumens carried therein and in the configuration of the lumens, they have in common that they have a proximal portion connectable to a housing member, such as housing 26, a distal portion located at a selected location remote from the housing member, and an elongated tubular portion located between the two ends. For those conduits that are not pre-attached to the charging device, the proximal portion thereof may be provided with a wedge fitting to allow portions of the conduit to be connected to the adapter member of the charging device. Such coupling elements are generally known in the art and will not be described in detail here, but may also be designed specifically for the charging device. The special wedge adapter prevents inadvertent connection of the adapter or housing to other commercially available types of catheters that are not specifically designed to carry the treatment unit and/or to prevent the treatment unit from being expelled into the body.

As used herein, "elongate conduit," "elongate conduit," and similar terms, are intended to include a single extruded conduit having one or more lumens, as well as multi-lumen conduits formed by bundling a plurality of separate tubes.

Fig. 4 shows the distal portion of a catheter 140 of the present invention, where the treatment unit is placed. In this embodiment, the catheter is comprised of a single tubular member 142 having a proximal portion (not shown), a distal portion, and a lumen 144 therebetween. The tube is preferably extruded from a nylon 11 material, although other suitable plastics materials may be used. The outer diameter of the tube is sized to correspond to the procedure to be performed, for example, 5 French or less for treating a coronary stenosis. The inner diameter of the lumen is sized accordingly to fit within treatment unit 22.

To prevent the treatment composition 22 from escaping the distal end of the tube, a stop boss may be provided in the lumen to block access to the treatment unit, for example an end stop 146 may be provided. End stop 146 is a separately injection molded top piece that is then bonded or otherwise secured to the distal portion of tube 142. The stop 146 preferably has a smoothly rounded outer surface to minimize abrasion of the vessel or other tissue. The block also has a central opening 148 for passage of liquid therethrough.

To facilitate the placement of the catheter at the desired location, a marker band 150 is disposed on the outer surface of the distal portion of the tubular member 142. To have a continuous smooth outer surface, a slight downward cut is made into the surface of the catheter where the band is to be placed. Although the marker band is shown on the outer surface of the catheter, it may be disposed on the inner surface. The stop 146 and the marker band are preferably made of a barium, platinum iridium composite or the like so that they are visible on the fluoroscope.

Please refer to fig. 4. In use, the distal portion of the catheter is advanced to a desired site in the patient's body, e.g., coronary arteries, after balloon angioplasty. In this case, a guide wire is usually preset in the patient, but a guide tube may be used. The distal end of the catheter is then advanced over the guidewire, through the lumen. The positioning of the device can be made relatively accurate because the stop 146 and the marker on the distal portion of the catheter can be viewed by the fluoroscope.

After the distal catheter portion is positioned at the coronary artery prior stenosis region 154 and this region is between the stop 146 and the marker band 150, the guidewire can be removed and the proximal catheter portion can then be connected to a treatment unit loading device and/or pump, as described above with respect to the embodiment of FIGS. 2-2B.

With such a connection, the treatment unit is in direct communication with the catheter lumen 144, forming a passageway therebetween. Pressurized fluid from a fluid pump, syringe, other piston-cylinder arrangement, or an overhead saline solution container, etc., is then introduced, forced against the treatment unit, and propels the treatment unit along the catheter lumen until stopped by end stop 146.

Taking the charging device of the embodiment of fig. 2A as an example, to advance the treatment unit 22 from the housing 26 to a selected location in the patient, the magazine 48 is moved from a first position to a second position. This allows the treatment unit to enter the fluid passageway and be rapidly moved by the force of the fluid flowing in the passageway into and through the lumen of the catheter to the distal portion of the catheter at the site of the stenosis. Rapid delivery of the treatment element reduces the amount of radiation that is transmitted to the portion of the patient through which the elongate catheter passes. In this embodiment, the fluid that delivers the treatment unit is expelled from the central bore 148 of the end stop 146.

As mentioned above, once the distal portion of the elongate catheter is reached, the treatment unit is not pushed into the patient due to the stop of the stop 146. Alternatively, the stop and marker bands can be used to fluorescently display the radioactive elements and calculate their position. The spacing between the stop and the marker band is specifically set to include the length of the lumen occupied by the full length of the radiation treatment unit, and the position of the unit can be confirmed from the physical image between the stop and the marker band as viewed on the fluoroscope.

In order to retain the treatment unit at the distal end portion of the elongated catheter, a constant fluid pressure needs to be applied to the treatment unit through the lumen in order to balance the effect of external blood pressure and/or the gravitational forces acting on the treatment unit, depending on the angle at which the distal end portion of the elongated catheter is placed, and the specific location in the patient.

In order to sufficiently irradiate the region of coronary stenosis that has undergone PTCA to prevent intimal hyperplasia, the treatment unit should preferably remain in the selected region for a sufficient period of time to deliver a therapeutically effective dose of radiation, preferably between about 100 and 10,000 rads, and more preferably between about 700 and 5,000 rads. The length of time required to deliver the above-mentioned radiation dose depends mainly on the intensity of the radiation source used in the treatment unit and on the number of treatment units used. The required activity will depend on the intensity of the source used and its radiation intensity, and may be in the range of 0.45-25,000 milliCuries, depending on the source used. After a sufficient time for treatment, e.g. 2-10 minutes, the treatment unit can be removed from the patient along with the catheter or by applying suction (e.g. by means of a syringe) at the proximal end of the lumen through which the treatment unit is advanced.

Fig. 5 shows yet another embodiment of an elongate conduit 156 of the present invention. The proximal end of the catheter may be pre-attached to the charging device/pump or may be wedge-attached to the device using a fitting, as described in detail above. Thus, only one distal end of the catheter is illustrated in the embodiment of FIG. 5.

As shown in fig. 5, the elongate conduit 156 includes an inner tube 158 and an outer tube 160 having a circular axis. Inner tube 158 has an inner bore or lumen 162 through which the treatment unit is advanced. The inner and outer tubes are spaced apart from one another to define a return lumen 164 at the spacing for the return flow of fluid used to advance the treatment unit.

The distal end of the outer tube 160 is tapered to engage a narrow, flexible atraumatic tip 166 secured to the outer tube. A non-transmissive stop 168 is provided slightly beyond the end of inner tube 158 and closes off outer tube 160 and blocks further proximal movement of treatment unit 22. Similar to the marker band 150 of the previous embodiment, a marker band 170 is recessed into the surface of the outer tube 160 at a location spaced proximally from the stop 168 to facilitate placement of the distal portion and treatment unit at the desired location.

When the catheter 156 is used to treat a site where a coronary artery has been subjected to a balloon angioplasty procedure, the catheter may be positioned at the site of the previous stenosis by a guide catheter or similar device. The positioning of the distal portion of the catheter can be observed on the fluoroscope due to the presence of the radiopaque marker 168 and the identification band 170.

If the proximal end of the catheter is not pre-attached to the loading unit/pump, the proximal end of the catheter can be attached using the aforementioned means. Treatment unit 22 is propelled along inner lumen 162 under the thrust of the liquid flowing through inner lumen 162 and the same parts as previously described are not repeated here. In the case of this embodiment, rather than being expelled from the distal end of the catheter, the fluid is expelled from the distal end of the inner lumen (or through a side hole 172 in the inner tube wall) and then back through the return lumen 164 between the inner and outer tubes. The reflux liquid may be removed by the feeder/pump or collected by the feeder/pump for additional disposal.

Unlike the first embodiment, which is a fully enclosed system, the fluid does not escape into the patient and the treatment unit does not come into contact with the blood. While this eliminates the effect of blood pressure on advancing the therapy unit, it is desirable to provide a small but constant flow of fluid to maintain the therapy unit at the distal end of the elongated catheter, especially when the treatment site is located higher than the proximal end of the catheter to counter-balance the forces. By allowing the fluid flow to travel back and forth between the delivery piston and the retrieval piston, the string 22 of treatment units can be moved slightly back and forth to provide more uniform irradiation of the area to be treated.

The radiation therapy unit remains at the distal end of the elongate catheter for a sufficient amount of time to deliver a therapeutically effective amount of radiation. As described above, this dose is preferably 100-10,000 rads in the case of the inhibition of intimal hyperplasia.

After a sufficient amount of radiation has been administered, the treatment unit 22 may be withdrawn from the distal end of the elongate catheter and the treatment unit returned to the charging device by means of introducing pressurized liquid into the flashback lumen. The reverse flow of fluid reverses the movement of fluid, creating a reverse thrust on the treatment unit that advances it proximally along the inner lumen 162. Returning to the feeding device. The elongate catheter may then be removed from the patient and the entire procedure is complete. Alternatively, the treatment unit is removed from the patient along with the catheter.

The third embodiment of the invention shown in fig. 6A and 6B is similar in construction and operation to the embodiment shown in fig. 5. The elongate conduit 174 includes coaxial inner and outer tubes 176, 178. The inner tube 176 has an inner bore or lumen 180 through which the treatment unit is advanced. The inner and outer tubes are spaced apart from one another to define a return lumen 182 at the spacing for facilitating the return flow of fluid from the treatment unit.

The distal end portion of the outer tube 178 is not tapered but is closed by a non-transmissive solid tip member 184, which in turn acts as a stop as the treatment unit travels down the inner lumen 180. Similarly, an identification band 186 is provided on the surface of the outer tube 178 at a distance proximally from the stop tip member 184 to facilitate placement of the distal end portion and treatment unit at the desired location.

Placement of the distal portion of the elongate catheter 174 may be performed with the aid of a third or guide tube 188, as shown in fig. 6B. As shown, the separate third tube has a proximal portion (not shown), a tapered distal portion, and a lumen 190 between the ends.

In practice, the third tube is placed into the patient along a predetermined guide wire with sufficient strength or rigidity so that the third tube is located at the specific site of the body to be treated. Once the guide catheter is positioned at the selected site, the guidewire is pulled back at least partially and the elongated catheter shown in FIG. 6A may be inserted into the lumen 190 of the catheter.

As with the embodiment of fig. 5, the embodiment of fig. 6A and 6B also allows the treatment unit 22 to be moved between the proximal and distal portions of the elongate catheter by hydraulic force, the direction of which is determined by the direction of fluid flow, which in turn is determined by the pressure gradient between the delivery and return lumens. Thus, after the treatment unit has been retained at the distal portion of the elongate catheter for a desired period of time, fluid may be passed back through the elongate catheter to remove the treatment unit. The catheter and the third tube (or guide tube) can then be removed from the patient and the entire procedure is completed.

Fig. 7A and 7B illustrate yet another embodiment of the catheter of the present invention, particularly configured for placement at a desired location by advancement of the catheter over a guidewire. The elongate conduit comprises a pair of inner tubes 194 and 196 which are disposed in parallel juxtaposition within an outer tube 198. Inner tube 194, which is smaller in diameter than inner tube 196, has an inner lumen 200 through which a guide wire is passed to position the catheter at a desired location within the patient. The larger diameter inner tube 196 is provided with an inner lumen 202 along which the treatment unit travels. A return lumen 204 is formed by the space between the inner surface of the outer tube 198 and the outer surface of the inner tubes 194, 196 for fluid return for delivery of the treatment unit.

As seen in FIG. 7A, the outer tube 198 has an open, tapered distal end portion. Within the outer tube is a luminal wall 206 located at the distal end of the inner tubes 194 and 196 and at the beginning of the outer tube taper. Inner wall 206 has an aperture therein which is in closed communication with lumen 200 of inner tube 194, and through which lumen 200 a guidewire may be passed. The inner wall 206 is preferably spaced slightly from the distal portion of the other inner tube 196 to allow fluid to exit the end of the inner tube 196 and return through the return lumen 204, with the treatment unit being advanced through the inner tube 196. The inner wall 206 also acts as a stop to prevent the treatment unit from backing out of the end of the inner tube 196.

As with the previous embodiments, the elongate catheter 192 is provided with first and second radiopaque marker bands 208 and 210 on the outer tube to enable placement of the distal portion at a desired location in the patient. As previously mentioned, although in many embodiments the indicator strip is provided on the outer tube, it may be provided at any suitable location within the catheter, for example on the inner tube or on a surface, without departing from the scope of the invention.

In the case of radiation therapy for treatment of stenotic sites in coronary arteries, the proximal end of the elongate catheter 192 may be pre-connected to a charging device/pump, or separately connected to such a device by a wedge fitting or similar structure, as previously discussed. The catheter is then advanced over the pre-embedded wire and the distal portion of the elongated catheter is positioned at the selected site in the patient's body to be treated. In this embodiment, the wires may be allowed to remain in place. This has the obvious advantage that it is not necessary to insert the guide wire again when the treatment is completed and another catheter and device need to be inserted.

The opaque marker bands 208 and 210 are visible on the fluoroscope, which aid in positioning the device in place. When the distal portion of the elongate catheter is positioned such that the selected site is between the marker bands 208 and 210, fluid may be pumped into the lumen 202, pushing the treatment unit towards the distal portion of the elongate catheter where it is positioned by the position of the marker bands. After sufficient irradiation, the pressurized liquid is caused to flow back along the return lumen, thereby bringing the treatment unit back to the charging device. The elongate catheter may then be removed from the patient, and the procedure is complete.

Fig. 8A and 8B illustrate yet another embodiment of a catheter of the present invention, which is preferably provided for placement of the catheter by a guidewire. The elongate conduit 212 includes a pair of inner conduits 214 and 216 disposed parallel to one another and side-by-side within an outer conduit 218. As in the embodiment of FIG. 7, inner tube 214, which is smaller in diameter than inner tube 216, has an inner lumen 220 through which a guidewire for positioning the catheter at a desired location in a patient passes. The larger diameter inner tube is provided with an inner lumen 224 through which the treatment unit is advanced. The space between the inner surface of the outer tube 218 and the outer surfaces of the inner tubes 214, 216 forms a return lumen 224 for returning fluid for delivery of the treatment unit, in the same manner as described in figure 7B. However, in the embodiment of FIG. 8, the inner tube 214 (for passage of the guidewire) extends along the entire length of the outer tube 218 and is secured to the outer tube at the distal-most end, where the outer tube is beveled.

In fig. 8A, an internal stop 226 is provided at the end of the inner tube 216 to stop the treatment unit from being removed from the end of the inner tube 216 because the treatment unit is disposed within the inner tube. The central aperture in stop 226 allows fluid to pass from lumen 222 of inner tube 216 into the return lumen. Alternatively, the stop may be solid, as shown in FIG. 8B (which is otherwise identical to FIG. 8A), and an aperture 230 may be provided in the wall of inner tube 216 to allow fluid flow between treatment unit lumen 222 and the return lumen. Although not shown in fig. 8A or 8B, it should be understood that the elongate catheter may be provided with a series of marker bands along the length of the tube at appropriate locations to ensure accurate positioning of the catheter within the patient.

Figure 9 shows another embodiment of the catheter of the present invention. As shown, conduit 232 has three coaxial tubes: inner tube 234, outer tube 236, and intermediate tube 238, all three tubes extending the length of the catheter to be the same length. The inner tube 234 has a lumen 240 for passage of a guidewire for placement of the catheter at a desired location within the patient. The inner tube 234 is spaced from the intermediate tube, forming an annular channel therebetween for the advancement of the treatment unit. In this embodiment, the treatment units are preferably in the form of rings 244, or doughnut-shaped 246, so that they slidably travel along the channel 242 on the inner tube 234. To provide a return passage, the outer tube 236 is made slightly larger in inner diameter than the intermediate tube 238, thereby forming a return passage 248 therebetween.

The distal end of the catheter is closed by a plug 250, preferably cast from an opaque material, secured to the ends of the inner and outer tubes 234, 236. The plug is provided with a central passage for passage of a guide wire which assists in positioning the catheter at a desired location. The distal end of the intermediate tube 238 does not reach the top plug, thereby placing the treatment unit channel 242 in direct communication with the return channel 248. Although the non-transmissive marker bands are not shown, they may be provided at the distal end of the elongate catheter to facilitate positioning of the elongate catheter at a desired location within the patient.

After the distal portion of the elongated catheter is positioned at the desired location within the patient, a fluid, such as saline, is forced into the treatment unit channel 242, pushing the annular treatment unit along the channel outside the inner tube 234 until the treatment unit abuts the distal plug 250. The radiation therapy unit remains at the distal end of the elongate catheter for a sufficient amount of time to deliver a therapeutically effective amount of radiation to the selected site. To remove the treatment unit, the fluid is simply forced distally into the flashback lumen and then back through the channel. The elongated catheter is then removed along the wire and the entire process is complete.

FIG. 10 shows yet another embodiment of the present invention, a catheter 254 includes both an inflatable balloon membrane for performing a balloon angioplasty procedure and a treatment unit 22 for simultaneous treatment at the distal end of the catheter. The catheter of fig. 10 is provided with an elongate tubular portion 258, typically formed by extrusion, with a guidewire lumen 260 and an inflation lumen 262. The balloon membrane is disposed at the distal end of the catheter with the outer surface partially sealed to form an inflatable balloon. The port 264 communicates between the inflation lumen and the interior of the balloon to inflate the balloon with a pressurized liquid. Only the distal portion of the catheter is shown because the structure of the proximal portion of the catheter is that of the proximal portion of a typical angioplasty catheter, which is well known to those skilled in the art and will not be described in detail.

To perform the balloon angioplasty procedure and radiotherapy simultaneously, a radiotherapy unit is placed within the balloon, distal portion of the catheter, between coaxial walls 266 and 268. The treatment unit is, as previously described, in the form of a ring or donut and fits over the inner tube wall 266. Stop rings 270, preferably made of an opaque material, are provided at either end of the string of treatment units to hold the treatment units in a fixed position within the balloon to facilitate placement of the catheter at the desired location.

The intensity and other characteristics of the radiation therapy unit are important and have been previously described and will not be repeated here. With the above structure, it is possible to perform the balloon angioplasty procedure and the radiotherapy of the stenosis site simultaneously, rather than sequentially, which shortens the time, reduces the cost, and reduces the risks associated with such procedures.

In practice, the catheter 254 is placed over the stenosed coronary artery by means of a pre-cast wire. Whether the radiation therapy unit is used alone or in conjunction with a non-transmissive end ring, the distal end of the catheter should be positioned so that the balloon portion is located at the stenosis. Pressurized fluid may be injected into the proximal end of the inflation lumen, for example with a syringe, into the port 264, inflating the balloon. The inflated balloon membrane compresses the hard plaque and increases the vessel diameter. The balloon may be deflated and its distal tip may continue to remain in place for a desired length of time to give an effective amount of radiation to the previous stricture. The device may then be removed from the patient, completing the procedure.

The radiation delivery system shown in fig. 11 is a variation of that shown in fig. 10. In the embodiment of FIG. 11, the structure and basic operation of the catheter is the same as that shown in FIG. 10, except that the radiation treatment unit is sleeved over the inner tube 272, directly beneath the balloon membrane 274. The balloon membrane may be inflated by introducing a pressurized fluid through inflation lumen 276 formed between inner tube 272 and coaxial outer tube 278.

FIG. 12 shows a distal portion of another balloon catheter of the invention. The conduit 280 is provided with three coaxial tubes: an inner tube 282, an outer tube 284, and an intermediate tube 286. The inner tube 282 has an inner lumen 288 through which a guidewire is passed to assist in positioning the catheter at the desired site. Between the inner tube and the intermediate tube 286 is formed an annular lumen 290 through which an annular or donut-shaped treatment unit is advanced. A return lumen 292 is formed between the intermediate tube and the outer tube 284 for fluid return for delivery of the treatment unit.

The catheter 280 further includes a balloon membrane 294 secured at one end to the outer surface of the outer tube 284 and at the other end to the outer surface of the inner tube 282 (the inner tube having a length that exceeds the distal ends of the intermediate and outer tubes). The distal portion of the outer tube is closed by a stop 296, which may be opaque, to prevent the treatment unit from exiting the distal lumen end 290. In this embodiment, the fluid used to deliver the treatment unit is also used to inflate the balloon, which is not required if a separate inflation lumen is provided. To inflate the balloon membrane, a side hole 298 is provided in the wall of the outer tube 284, or if desired, in the middle tube. With this configuration, pressurizing a blood-compatible liquid, such as sterile saline, can be used to advance the treatment unit and, at the same time, advance it to the distal end of the catheter. The treatment unit can be removed by allowing fluid flow to return along the return lumen 292 and the treatment unit lumen 290, respectively. Further release of pressure on the fluid will cause the balloon to deflate and the catheter can be removed.

Fig. 13 shows another embodiment of a balloon catheter, balloon catheter 300 having a pair of adjacent parallel inner tubes 302 and 304 defining a guidewire lumen 306 and a treatment unit lumen 308. In the same manner as in fig. 7 and 8, the inner tube is mounted in the outer tube with the inner space between them forming a return lumen. An airbag membrane 310 is secured to the outer surface of the outer tube to form an inflatable balloon. The balloon membrane may be inflated by liquid coming in through the side holes 312 of the inner tube 304, i.e., a blood-compatible liquid used to propel the treatment unit along the lumen 308. As shown in FIG. 12, the catheter can be used to inflate the balloon membrane for an angioplasty procedure in a blood vessel, while the treatment unit is advanced to the distal portion of the catheter where the balloon is located, to apply radiation therapy to the tissue undergoing the balloon angioplasty procedure.

The arrangement shown in fig. 14 is substantially the same as that shown in fig. 2C and has been described in detail, except that housing member 94 includes a latch 314, such as a spring pin, for retaining the hub 110 in the chamber 108. A release mechanism may also be provided for releasing the insert plate.

Fig. 15A-15C illustrate yet another embodiment of a treatment system, which is similar in many respects to the embodiment shown in fig. 2C. In this embodiment, however, the shutter 114 is a disc 318 that is rotatably mounted to the distal end of the hub 110. The disk is provided with a pair of differently sized spaced through holes 320 and 322 that are movable into alignment with the central opening 112 of the insert plate 110. One of the through-holes 320 is smaller in diameter than the treatment element 22, and when it is aligned with the central hole 112, the treatment element 22 is prevented from passing through the central hole while allowing liquid to pass through for filling, etc. Alternatively, the disc may be rotated to position the large aperture 322 in alignment with the central aperture 112, which allows the treatment unit to be ejected from the insert under fluid pressure into and along the catheter. For transport and storage, the puck may be in a position that completely covers the puck aperture 112.

In this embodiment, the housing 94 is provided with a pair of opposing side entry ports 324 to allow access to the disks for rotation between desired positions, and a pair of opposing viewing ports to allow visual correction of the treatment unit position. In this embodiment, the catheter 92 has a proximal connector member 328 mounted to the distal end of the housing 94. The adapter member may be wedge-shaped to ensure that it is properly mounted on the housing and to ensure that the lumens on the conduit are properly aligned with the appropriate passages on the housing.

Figure 16 shows a simple form of a treatment unit according to the invention. As shown, the treatment unit 22 is housed in a central passage 330 of a solid housing 332. The inlet of the passageway is provided with an internal luer lock connector 334 and the outlet is provided with an external luer lock connector, although the above described dovetail connector may be used.

During shipping and storage, the outlet connector 336 is fitted with a temporary internal luer lock connector 338. The connector 338 is provided with a pin 340 that extends from the connector all the way into the channel to immobilize the treatment unit in place and act as a stop to prevent escape of radioactivity. The access port is smaller than the treatment unit, thus generally positioning the treatment unit in the middle of the housing 332.

In use of this embodiment, the temporary connector 338 is removed and the luer lock connector 342 (or the wedge connector described above) located on the single lumen catheter 334 is connected to the outlet connector 336. A source of a blood compatible liquid, such as sterile saline, for example, a syringe or a hanging container, is connected to inlet connector 334 for fluid communication through the central passage to advance treatment unit 22 proximally and distally along the length of the catheter at a location to be treated within the vascular system. After treatment is complete, the treatment unit is removed from the patient along with the catheter or suction is applied at the proximal end, causing the fluid to flow back, pushing the treatment unit back to the proximal end.

Fig. 17 shows the same as fig. 12, but with the difference that a coaxial fourth outer tube 346 is fitted around the outer tube 284, and the end of the balloon membrane 294 is fixed to the outer tube 346 instead of the outer tube 284. The distal end of the outermost tube 346 terminates a little within the balloon membrane and the space between the outermost tube 346 and the tube 248 forms an inflation lumen 348 through which pressurized liquid can flow directly to the sub-membrane region to inflate the balloon. With this arrangement, an additional separate source of pressurized liquid can be used to inflate the balloon membrane, such that inflation of the balloon membrane is independent of the pressure of the liquid pushing the treatment unit to the distal end of the catheter.

Similarly, FIG. 18 is the same as FIG. 13, except that an auxiliary tube 350 is fitted over each of the tubes shown in FIG. 13, and one end of the balloon membrane 310 is fixed to the surface of the tube 350. As in the case of FIG. 17, the space between the secondary tube 350 and the tubes described above forms an inflation lumen 352, the distal end of which is open in the region directly beneath the balloon membrane. This configuration makes it possible to inflate the balloon membrane used in the angioplasty procedure using a different liquid source than the liquid source used to deliver the treatment unit.

Fig. 19 shows another embodiment of the distal portion of a catheter 354 having an elongated inner tube 356 (extending proximally, not shown) defining an inner lumen 358. The inner tube 356 is nested within the outer tube 360, coaxially with the outer tube, but with the outer tube distal portion short of the inner tube distal end. The balloon membrane 362 has one end attached to the surface of the outer tube 360 and the other end attached to the surface of the inner tube 356. The space between the inner and outer tubes forms an inflation lumen 364 through which fluid is passed to inflate the balloon.

An additional elongated catheter 364 may be inserted into the inner lumen 358 with the distal end of the catheter being positioned in the balloon region. The other catheter may also have a lumen 366 extending proximally (not shown) through which treatment unit 22 travels under the thrust of the flowing fluid from the proximal portion of the catheter to the distal portion (in this embodiment, fluid is expelled distally from lumen 358).

While the invention has been described with reference to certain specific embodiments, it will be understood that various changes or modifications may be made without departing from the scope of the invention.

Claims (25)

1. An apparatus for intraluminal treatment of a selected site within a patient's body, comprising:

a flexible elongated catheter having a proximal portion adapted to remain outside the patient's body, a distal portion adapted to be intraluminally positioned at a selected site in a blood vessel within the patient's body, and a first lumen having a proximal portion and a distal portion, the first lumen being connected between the proximal portion and the distal portion of the catheter, the catheter having a diameter sufficiently small to be introduced into the lumen;

an introduction port at a proximal end portion of said catheter, communicating with said first lumen, for introducing a blood-compatible liquid into the lumen;

a source of liquid containing a biologically compatible liquid, said source of liquid being in communication with said inlet for introducing the liquid under pressure into the inlet;

at least one discrete treatment element positionable within said first lumen, a distal portion of said first lumen being closed against expulsion of said treatment element, said treatment element being movable along said lumen from said proximal portion to a distal portion of said first lumen under a pushing force generated by said liquid flowing through said first lumen;

the catheter is sufficiently flexible to allow placement of the distal portion at a selected location within a patient's body over a guidewire, and includes a second lumen through which the guidewire passes.

2. The device of claim 1 wherein said first lumen is open at said distal portion, said device further comprising a stop tab projecting into said lumen at said distal portion of said first lumen, said tab configured to retain said treatment unit in said first lumen.

3. The apparatus of claim 1, wherein said elongated catheter includes a third lumen connecting between said proximal and distal portions, said third lumen communicating with said first lumen at said distal portion, and distal portions of said first and third lumens being closed to fluid flow between said proximal and distal portions of said first lumen and back along said third lumen, such that said treatment element is movable between said distal and proximal portions of said elongated catheter under the thrust of fluid introduced into said third lumen.

4. The apparatus of claim 1, wherein said treatment unit is a radiation source.

5. The device of claim 4, further comprising a pair of non-projecting markers spaced apart from each other at the distal end portion of said elongate catheter, said markers defining an effective treatment area therebetween.

6. The device according to claim 4, characterized in that said treatment unit consists of a beta-emitting material.

7. The apparatus of claim 1, further comprising:

a housing member for positioning said treatment unit within said first lumen, said housing member having a first end, a second end and a first aperture extending through said housing member from said first end;

the elongated conduit is connected to the first end of the housing member, and a proximal portion of the first lumen is in communication with the first aperture at the first end.

8. The device of claim 7, wherein the housing member further comprises a shutter movable between a first position and a second position in which the treatment unit is released into the first lumen.

9. The device of claim 7, further comprising a separate treatment unit carrier, said carrier configured to be coupled to said housing.

10. The device of claim 9, wherein the housing includes a delivery channel for fluid communication to deliver the treatment element, a guidewire channel for passage of a guidewire, and a third channel for return flow of fluid through the housing.

11. The apparatus of claim 1, further comprising:

a fluid pump operatively connected to said first lumen, said fluid pump configured to control the flow of fluid through said first lumen.

12. The device of claim 1, wherein the treatment unit is comprised of a plurality of treatment units flexibly connected in a column to form a string of treatment units.

13. The device of claim 1, wherein the first lumen has a diameter less than half of the diameter of the treatment unit.

14. The device of claim 1, wherein said elongated flexible conduit further comprises a flexible balloon membrane mounted on a distal portion of said elongated flexible conduit such that said balloon membrane expands upon introduction of a pressurized liquid.

15. The apparatus of claim 1, further comprising a second elongated conduit, said second conduit comprising:

a proximal portion;

a distal portion opposite said proximal portion;

a flexible balloon membrane mounted on said distal portion;

a first lumen connecting between said proximal and distal portions, in communication with said balloon membrane, for inflation of said balloon membrane upon introduction of pressurized liquid through said first lumen;

a second lumen connecting between said proximal and distal portions, said second lumen being sized to receive said elongated flexible conduit.

16. An apparatus for intraluminal treatment of a selected site within a patient's body, comprising:

an elongate catheter having a proximal portion, a distal portion opposite the proximal portion, and a first lumen connecting the ends;

an inflatable balloon disposed at the distal end of the elongate catheter;

a second lumen extending between the proximal and distal portions of the elongate catheter, the second lumen being in communication with the balloon such that the balloon is inflated when a pressurized liquid is introduced;

a treatment unit disposed within the first lumen and disposed within the balloon, disposed at the distal portion of the elongate catheter.

17. The apparatus of claim 16, wherein said treatment unit has a proximal end and a distal end, and further comprising:

a first radiopaque marker located adjacent a distal end of the radiation unit;

a second opaque marker located adjacent a proximal end of the treatment unit.

18. The apparatus of claim 16, wherein the treatment unit is fixedly disposed at the distal portion.

19. The apparatus of claim 16, wherein said catheter includes a lumen connecting said proximal and distal portions, said treatment unit being movable within said lumen between said proximal and distal portions.

20. An apparatus for intraluminal treatment of a selected site within a patient's body, comprising:

1) a flexible, elongate catheter of sufficiently small diameter to be transluminally introduced into a blood vessel of a patient's body, comprising:

a proximal portion adapted to remain outside the patient;

a distal portion adapted for intraluminal placement at a selected site in a blood vessel within a patient;

and first and second parallel lumens connected between the proximal and distal portions;

the first and second lumens communicating at a distal portion of the elongate catheter;

2) a delivery and loading member connected to the proximal portion of the elongate flexible conduit;

3) a delivery pump mounted to said delivery and loading member;

4) a retrieval pump mounted to said conveying and loading member;

5) a treatment unit aperture disposed within said delivery and loading member and sized at least to receive a treatment unit therein, said aperture having one end in communication with said first lumen of said catheter so that said treatment unit is movable from said treatment unit aperture through said first lumen;

6) a delivery fluid channel disposed within said delivery and charging member, said delivery fluid channel communicating between said delivery pump and said treatment element aperture of said delivery and charging member;

7) a fluid return passage disposed within said delivery and loading member, said fluid return passage communicating between said retrieval pump and said second lumen;

8) a source of liquid containing a biologically compatible liquid, said source of liquid being in communication with said shipping and feeding member.

21. The apparatus according to claim 20, wherein said conveying and charging member comprises:

a charging chamber;

a separate, discrete loading tray capable of holding one or more treatment units, said loading tray being capable of holding said treatment units in said loading chamber, said loading chamber being in communication with said treatment unit ports and said transport fluid path.

22. An apparatus according to claim 21, further comprising a shutter mounted to the loading insert, the shutter being movable between a first position preventing movement of the treatment unit from the loading insert and a second position allowing movement of the treatment unit from the loading insert.

23. The device of claim 20 wherein said flexible elongate catheter further comprises a third lumen connected between said proximal and distal end portions, said delivery and charging member including a guidewire passage communicating with and passing through said third lumen.

24. The apparatus of claim 20 wherein said delivery pump and said retrieval pump each comprise a cylinder having a piston disposed therein.

25. The apparatus of claim 20 wherein the delivery pump and the retrieval pump each comprise a bellows.