Surgery: light – thermal – and electrical application – Light – thermal – and electrical application – Thermal applicators
Reexamination Certificate
2001-03-21
2003-08-05
Kearney, Rosiland S. (Department: 3739)
Surgery: light, thermal, and electrical application
Light, thermal, and electrical application
Thermal applicators
C607S104000, C607S106000, C606S020000, C606S021000, C606S024000
Reexamination Certificate
active
06602276
ABSTRACT:
CROSS-REFERENCE TO MICROFICHE APPENDIX
(none)
BACKGROUND OF THE INVENTION
Balloon angioplasty, or the technology of reshaping of a blood vessel for the purpose of establishing vessel patency using a balloon tipped catheter, has been known since the late 1970's. The procedure involves the use of a balloon catheter that is guided by means of a guidewire through a guiding catheter to the target lesion or vessel blockage. The balloon typically is equipped with one or more marker bands that allow the interventionalist to visualize the position of the balloon in reference to the lesion with the aid of fluoroscopy. Once in place, i.e., centered with the lesion, the balloon is inflated with a biocompatible fluid, and pressurized to the appropriate pressure to allow the vessel to open.
Typical procedures are completed with balloon inflation pressures between 8 and 12 atmospheres. A percentage of lesions, typically heavily calcified lesions, require much higher balloon inflation pressures, e.g., upward of 20 atmospheres. At times, the balloon inflation procedure is repeated several times before the lesion or blockage will yield. The placement of stents after angioplasty has become popular as it reduces the rate of restenosis.
Restenosis refers to the renarrowing of the vascular lumen following vascular intervention such as a balloon angioplasty procedure or stent insertion. Restenosis is clinically defined as a greater than 50% loss of initial lumen diameter. The mechanism or root causes of restenosis are still not fully understood. The causes are multifactorial, and are partly the result of the injury caused by the balloon angioplasty procedure and stent placement. With the advent of stents, restenosis rates have dropped from over 30% to 10-20%. Recently, the use and effectiveness of low-dose radiation administered intravascularly following angioplasty is being evaluated as a method to alter the DNA or RNA of an affected vessel's cells in the hope of reducing cell proliferation.
Besides restenosis, another cardiological malady is atrial fibrillation. Atrial fibrillation refers to very rapid irregular contractions of the atria of the heart resulting in a lack of synchronization between the heartbeat and the pulse. The irregular contractions are due to irregular electrical activity that originates in the area of the pulmonary veins. A proposed device, currently under development, for treating atrial fibrillation is a balloon filled with saline that can be ultrasonically agitated and heated. This device is inserted in the femoral vein and snaked into the right atrium. The device is then poked through the interatrial septum and into the left atrium, where it is then angled into the volume adjoining the suspect pulmonary vein with the left atrium.
Research in atrial fibrillation indicates that substantially complete circumferential necrosis is required for a therapeutic benefit. The above technique is disadvantageous in that circumferential portions of the tissue, desired to be necrosed, are not in fact affected. Other techniques, including RF ablation, are similarly inefficient. Moreover, these techniques leave the necrosed portions with jagged edges, i.e., there is poor demarcation between the healthy and the necrosed tissue. These edges can then cause electrical short circuits, and associated electrical irregularities, due to the high electric fields associated with jagged edges of a conductive medium.
The above technique is also disadvantageous in that heating is employed. Heating is associated with several problems, including increased coagulum and thrombus formation, leading to emboli. Heating also stimulates stenosis of the vein. Finally, since tissues can only safely be heated to temperatures of less than or about 75° C.-85° C. due to charring and tissue rupture secondary to steam formation. The thermal gradient thus induced is fairly minimal, leading to a limited heat transfer. Moreover, since heating causes tissues to become less adherent to the adjacent heat transfer element, the tissue contact with the heat transfer element is also reduced, further decreasing the heat transfer.
SUMMARY OF THE INVENTION
The present invention provides an enhanced method and device to inhibit or reduce the rate of restenosis following angioplasty or stent placement. The invention is similar to placing an ice pack on a sore or overstrained muscle for a period of time to minimize or inhibit the bio-chemical events responsible for an associated inflammatory response. An embodiment of the invention generally involves placing a balloon-tipped catheter in the area treated or opened through balloon angioplasty immediately following angioplasty. A so-called “cryoplasty” balloon, which can have a dual balloon structure, may be delivered through a guiding catheter and over a guidewire already in place from a balloon angioplasty. The dual balloon structure has benefits described below and also allows for a more robust design, providing significant safety advantages to the patient because two balloons must be broken if cooling fluid is to deleteriously infuse into the patient.
The dual balloon may be centered in the recently opened vessel with the aid of radio opaque marker bands, indicating the “working length” of the balloon. In choosing a working length, it is important to note that typical lesions may have a size on the order of 2-3 cm. A biocompatible heat transfer fluid, which may contain contrast media, may be infused through the space between the dual balloons. While this fluid does not circulate in this embodiment, once it is chilled or even frozen by thermal contact with a cooling fluid, it will stay sufficiently cold for therapeutic purposes. Subsequently, a biocompatible cooling fluid with a temperature between about, e.g., −40° C. and −60° C., may be injected into the interior of the inner balloon, and circulated through a supply lumen and a return lumen. The fluid exits the supply lumen through a skive in the lumen, and returns to the refrigeration unit via another skive and the return lumen.
The biocompatible cooling fluid chills the biocompatible heat transfer fluid between the dual balloons to a therapeutic temperature between about, e.g., 0° C. and −50° C. The chilled heat transfer fluid between the dual balloons transfers thermal energy through the balloon wall and into the adjacent intimal vascular tissue for the appropriate therapeutic length of time. Upon completion of the therapy, the circulation of the biocompatible cooling fluid is stopped, and the heat transfer fluid between the dual balloons withdrawn through the annular space. Both balloons may be collapsed by means of causing a soft vacuum in the lumens. Once collapsed, the cryoplasty catheter may be withdrawn from the treated site and patient through the guiding catheter.
In more detail, in one aspect, the invention is directed to a device to treat tissue, including an outer tube, an an inner tube disposed at least partially within the outer tube, and a dual balloon including an inner balloon and an outer balloon, the inner balloon coupled to the inner tube at a proximal and at a distal end, the outer balloon coupled to the inner tube at a distal end and to the outer tube at a proximal end. A first interior volume is defined between the outer balloon and the inner balloon in fluid communication with an inlet in the volume between the outer tube and the inner tube.
Variations of the invention may include one or more of the following. The inner tube may further define a guidewire lumen, a supply lumen, and return lumen. The supply lumen may define a hole or skive such that a fluid flowing in the supply lumen may be caused to flow into a volume defined by the inner balloon, and the return lumen may define a hole or skive such that a fluid flowing in a volume defined by the inner balloon may be caused to flow into the return lumen. The guidewire lumen may extend from a proximal end of the inner tube to a distal end of the inner tube. The device may further comprise at least two radially extending tabs disp
Dobak III John D.
Kramer Hans W.
Yon Steve A.
Innercool Therapies, Inc.
Kearney Rosiland S.
Mayer Fortkort & Williams
Wieczorek Mark D.
Williams Karin L.
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