Chemical apparatus and process disinfecting – deodorizing – preser – Process disinfecting – preserving – deodorizing – or sterilizing – Using disinfecting or sterilizing substance
Reexamination Certificate
2001-08-31
2003-09-16
Warden, Sr., Robert J. (Department: 1744)
Chemical apparatus and process disinfecting, deodorizing, preser
Process disinfecting, preserving, deodorizing, or sterilizing
Using disinfecting or sterilizing substance
C422S027000, C422S028000
Reexamination Certificate
active
06620381
ABSTRACT:
BACKGROUND OF INVENTION
Surgical procedures employing balloons and medical devices incorporating those balloons (i.e., balloon catheters) are becoming more common and routine. These procedures, such as angioplasty procedures, are conducted when it becomes necessary to expand or open narrow or obstructed openings in blood vessels and other passageways in the body to increase the flow through the obstructed areas. For example, in an angioplasty procedure, a dilatation balloon catheter is used to enlarge or open an occluded blood vessel which is partially restricted or obstructed due to the existence of a hardened stenosis or buildup within the vessel. This procedure requires that a balloon catheter be inserted into the patient's body and positioned within the vessel so that the balloon, when inflated, will dilate the site of the obstruction or stenosis so that the obstruction or stenosis is minimized, thereby resulting in increased blood flow through the vessel. Often, however, a stenosis requires treatment with multiple balloon inflations. Additionally, many times there are multiple stenoses within the same vessel or artery. Such conditions require that either the same dilatation balloon must be subjected to repeated inflations, or that multiple dilatation balloons must be used to treat an individual stenosis or the multiple stenoses within the same vessel or artery. Additionally, balloons and medical devices incorporating those balloons may also be used to administer drugs to a patient.
Traditionally, the balloons available to physicians were classified as either “compliant” or “noncompliant”. This classification is based upon the operating characteristics of the individual balloon, which in turn depended upon the process used in forming the balloon, as well as the material used in the balloon forming process. Both types of balloons provide advantageous qualities which were not available from the other.
A balloon which is classified as “noncompliant” is characterized by the balloon's inability to grow or expand appreciably beyond its rated or nominal diameter. “Noncompliant” balloons are referred to as having minimal distensibility. In balloons currently known in the art (e.g., polyethylene terephthalate), this minimal distensibility results from the strength and rigidity of the molecular chains which make up the base polymer, as well as the orientation and structure of those chains resulting from the balloon formation process. The strength resulting from this highly oriented structure is so great that when the balloon is subjected typical inflation or operating pressures (I, about 70 psi to over 200 psi), it will not be stressed above the yield point of the polymeric material.
The yield point of a material is defined as the stress at which the individual molecular chains move in relation to one another such that when the pressure or stress is relieved, there is permanent deformation of the structure. When a material is subjected to pressure or stress below its yield point, the material will consistently follow the same stress-strain curve when subjected to multiple cycles of applying and relieving the stress or pressure. A material which exhibits the ability to follow the same stress-strain curve during the repeated application and relief of stress is defined as being elastic and as having a high degree of elastic stress response. This elastic behavior is highly desirable in balloons in order to ensure consistent and predictable balloon sizing regardless of the balloon's previous inflation history.
A balloon which is referred to as being “compliant” is characterized by the balloon's ability to grow or expand beyond its nominal or rated diameter. In balloons currently known in the art (e.g., polyethylene, polyvinylchloride), the balloon's “compliant” nature or distensibility results from the chemical structure of the polymeric material used in the formation of the balloon, as well as the balloon forming process. These polymeric materials have a relatively low yield point. Thus, the inflation pressures used in dilation procedures are typically above the yield point of the materials used to form distensible balloons. A distensible or “compliant” balloon when inflated to normal operating pressures, which are greater than the polymeric material's yield point, is subjected to stress sufficient to permanently realign the individual molecular chains of the polymeric material. The realignment of individual polymer chains permits the balloon to expand beyond its nominal or rated diameter. However, since this realignment is permanent, the balloon will not follow its original stress-strain curve on subsequent inflation-deflation cycles. Therefore, the balloon balloon upon subsequent inflations, will achieve diameters which are greater than the diameters which were originally obtained at any given pressure during the course of the balloon's initial inflation.
The term “elastic”, as it is used in connection with this invention, refers only to the ability of a material to follow the same stress-strain curve upon the multiple applications of stress. See Beer, P. et al.,
Mechanics of Materials
(McGraw-Hill Book Company 1981), pp. 39-40. Elasticity, however, is not necessarily a function of how distensible a material is. It is possible to have an elastic, non-distensible material or a nonelastic, distensible material. This is best illustrated in
FIGS. 1
,
2
and
3
.
FIG. 1
represents an elastic, essentially non-distensible material. If this material was used to form a balloon, the balloon would be considered non-distensible because there is very little change in strain (diameter) as the stress applied is increased (inflation pressure). The balloon would be elastic because it follows essentially the same stress-strain (pressure-diameter) curve with the second application of stress (inflation).
FIG. 2
represents an elastic, distensible material. If this material was used to form a balloon, the balloon would be considered distensible because there is significant change in strain (diameter) as the stress applied is increased (inflation pressure). The balloon would be considered elastic because it follows essentially the same stress-strain (pressure-diameter) curve with the second application of stress (inflation).
FIG. 3
represents an inelastic, distensible material. Like
FIG. 2
,
FIG. 3
shows a significant change in strain (diameter) and would therefore be considered a distensible balloon material. Unlike
FIGS. 1 and 2
, however, the same stress-strain (pressure-diameter) curve is not maintained upon the second application of stress (inflation).
It has been found that the optimal size of a dilatation balloon is about 0.9 to about 1.3 the size of the vessel being treated. See Nichols et al.,
Importance of Balloon Size in Coronary Angioplasty, J. American College of Cardiology,
Vol. 13, 1094 (1989). If an undersized balloon is used, there is a high incidence of significant residual stenosis and a greater need for subsequent dilatation procedures. However, if an oversized balloon is used, there is an increased chance of coronary dissection. Therefore, physicians desire to use a balloon which will closely approximate the size of the occluded vessel or obstructed cavity being treated.
Because physiological vessels such as arteries are generally tapered, the nominal or rated diameter of balloons commercially available often do not correspond to the size of the vessel being treated. Physicians, therefore, are often faced with the prospect of using an undersized “compliant” balloon which can be expanded beyond its nominal or rated diameter, or an oversized “noncompliant” balloon which will follow the same stress-strain curve during multiple inflations (i.e., is elastic). Thus, physicians can choose from two general types of balloons depending upon whether they require a balloon which grows beyond nominal diameter. They may choose a “noncompliant” balloon if they require a relatively high strength balloon which will not expand much beyond its nominal or ra
Anderson Jere R.
Barbere Michael D.
Jandris Louis J.
Murphy Richard T
Conley Sean E.
Medtronic AVE Inc.
Sterne, Kessler, Goldstein & Fox P.L.LC.
Warden, Sr. Robert J.
LandOfFree
Sterilization process for a distensible dilatation balloon... does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Sterilization process for a distensible dilatation balloon..., we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Sterilization process for a distensible dilatation balloon... will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-3091728