Patent Description:
Balloon catheters are widely used in connection with a variety of intravascular medical procedures or treatments. Typically, a fluid or liquid under pressure is injected into an inflation lumen of the catheter in order to inflate the balloon. Prior to being introduced into the body, the balloon catheter is prepped by the physician or interventionalist correctly following a multi-step process to properly purge residual air from the inflation lumen and balloon. Specifically, the purging of air from the inflation lumen prevents an air embolism from entering the vasculature system in the case of leak or rupture of the balloon. Furthermore, residual air is also purged from the balloon itself to insure inflation of the balloon using a desired volume of inflation medium that might otherwise be inaccurate due to the compressed unknown volume of residual air within the balloon.

One common technique for purging residual air from a balloon catheter prior to introduction into the body is by applying a vacuum or negative pressure to the proximal end of the inflation lumen using a syringe or vacuum and drawing out as much air as possible proximally through the inflation lumen. Then the syringe vacuum is closed off via a valve (e.g., a three-way luer valve) and the inflation lumen is opened under vacuum allowing the dispensing of the inflation medium therethrough and into the balloon. During injection of the inflation medium, the balloon is preferably held vertically with a downward inclination to promote air to exhaust allowing the residual air within the catheter to rise through the inflation medium towards an inflation port. The inflation medium and some air bubbles are withdrawn from the catheter, and additional inflation medium is again injected. It is not uncommon for these steps to have to be repeated multiple times to adequately purge the catheter of the residual air, requiring a substantial amount of preparation time. With each iteration these steps must be correctly followed.

In angiographic balloon catheter systems, the device is configured so that the residual air from the inflation lumen and balloon is exhausted via a distal vent, rather than proximally.

Since the prepping steps are numerous and time consuming, physicians and interventionalist may be discouraged from using the device altogether. Those physicians or interventionalist that use the device, may unintentionally omit from following the proper prepping steps or do so improperly after introducing the balloon catheter into the body resulting in potential health risks to the patient.

It is therefore desirable to design an improved balloon catheter and method for use of such improved balloon catheter with venting of residual air in a proximal direction while minimizing the steps associated therewith thereby promoting use of the device.

An aspect of the present invention relates to an improved balloon catheter with venting of residual air in a proximal direction.

Another aspect of the present invention is directed to a balloon guide catheter system including a balloon guide catheter. The balloon guide catheter has a catheter shaft with a proximal end and an opposite distal end; wherein the catheter shaft includes: (i) a main lumen defined axially through the catheter shaft; (ii) an inflation lumen extending axially along the catheter shaft; the inflation lumen having a proximal end, an opposite terminating distal end; and (iii) an exhaust lumen extending axially along the catheter shaft, the exhaust lumen having a proximal end and an opposite terminating distal end. The catheter shaft has an outer surface with a first localized fluid communication channel defined therein located underneath the balloon via which the terminating distal ends of the respective inflation and exhaust lumens are in localized fluid communication with one another underneath the balloon while in a non-inflated state. In addition, the balloon guide catheter further includes a balloon disposed about a distal region of an outer surface of the catheter shaft, wherein the exhaust lumen is configured to purge the residual air in a proximal direction and out from a proximal region of the balloon guide catheter.

The foregoing and other features of the present invention will be more readily apparent from the following detailed description and drawings illustrative of the invention wherein like reference numbers refer to similar elements throughout the several views and in which:.

The terms "distal" or "proximal" are used in the following description with respect to a position or direction relative to the treating physician or medical interventionalist. "Distal" or "distally" are a position distant from or in a direction away from the physician or interventionalist. "Proximal" or "proximally" or "proximate" are a position near or in a direction toward the physician or medical interventionalist. The terms "occlusion", "clot" or "blockage" are used interchangeably.

The present inventive balloon catheter has multiple lumens arranged in the outer wall of the catheter radially outward relative to a main lumen that receives a guidewire therethrough. Specifically, there is at least one inflation lumen and at least one exhaust/venting lumen, each extending axially in the outer wall of the catheter from the hub to the balloon. Respective distal ends of the inflation lumen and exhaust/venting lumen are in localized fluid communication with one another. The diameter size of the main lumen of the device is sufficient to serve as a conduit for guidewire(s) (e.g., <NUM>", <NUM>", <NUM>" & <NUM>" guidewires) (In defined lengths throughout the description, <NUM> inch corresponds to <NUM>,<NUM>). as well as ancillary devices such as; accommodating microcatheters, mechanical thrombectomy devices, diagnostic catheters, intermediate catheters/aspiration catheters during the procedure. Preferably, the main lumen has a diameter of approximately <NUM>".

Regardless of the particular configuration, the present inventive balloon catheter purges, exhaust or vents residual air in a proximal direction from the balloon catheter.

Referring to the perspective view of the balloon catheter <NUM> depicted in <FIG>, the catheter has a proximal end <NUM> and an opposite distal end <NUM>. A hub <NUM> is secured proximate the proximal end <NUM> of the balloon catheter <NUM>. In a first configuration illustrated in <FIG>, hub <NUM> includes a main/guidewire port <NUM> for receiving therein a guidewire <NUM> or ancillary device. A separate inflation medium port <NUM> is also provided in the hub <NUM> for receiving therein inflation medium (e.g., preferably, a <NUM>% contrast saline solution) introduced into the balloon catheter <NUM> from a syringe or other dispensing mechanism (syringe <NUM> is shown in <FIG>). In the configuration shown in <FIG>, hub <NUM> does not have an exhaust or vent port. Rather, residual air is vented or exhausted via an aperture defined in the exterior surface of the exhaust lumen proximate the proximal end of the catheter shaft, but distally of the hub <NUM>. While in a deflated (non-inflated) state, balloon <NUM> fits tightly around the catheter shaft prohibiting residual air from being present between the deflated balloon and catheter shaft. Distal terminating ends of both the inflation lumen <NUM> and exhaust lumen <NUM> coincide beneath the balloon <NUM> and are arranged close to one another so that the relatively low volume residual air in the inflation lumen communicates effectively to the exhaust lumen. The progressing inflation medium follows the path of least resistance flowing into the balloon region rather than advancing back up the exhaust lumen.

Arranged axially or longitudinally through the balloon catheter <NUM> starting from the proximal end <NUM> are at least three separate, distinct, independent lumen, namely a main/guidewire lumen <NUM>, an exhaust lumen <NUM> and an inflation lumen <NUM>. The exhaust and inflation lumen <NUM>, <NUM> are arranged radially outward relative to the main/guidewire lumen <NUM>. In addition, the main/guidewire lumen <NUM> extends from the proximal end <NUM> to the opposite distal end <NUM>, while respective terminating distal ends of the exhaust lumen <NUM> and inflation lumen <NUM> terminate beneath the balloon <NUM> (coincide with the balloon), as is clearly visible from the enlarged partial view of the distal end of the catheter in <FIG>.

Preferably, proximate the terminating distal end of the exhaust lumen <NUM> is a microporous membrane or filter <NUM>. Pores of the microporous membrane are sized to permit only the passage of gas (e.g., residual air) therethrough, liquid (inflation medium) dispensed through the inflation lumen is prevented from permeating through the microporous membrane allowing the pressure within the inflation lumen to build-up and inflate the balloon as the volume within the balloon fills with the inflation medium. Preferably, the microporous membrane is a certain grade (based on porosity and thickness) of sintered polytetrafluoroethylene (PTFE), for example, expanded polytetrafluoroethylene (ePTFE) that permits the passage of air molecules therethrough but acts as a barrier to larger higher cohesive molecules such as water and contrast agent. Such microporous membrane may also prevent air-locking of the exhaust lumen and improper operation of the catheter.

<FIG> is an alternative configuration of the hub <NUM>' which includes an exhaust port <NUM> (through which the residual air purged in a proximal direction exits from the balloon catheter <NUM>) as well as the previously described inflation port <NUM> and main/guidewire port <NUM>. Different ancillary devices are connectable to the exhaust port <NUM>. In the example depicted in <FIG>, a <NUM>-way valve <NUM> may be connected to the exhaust port <NUM> to control expelling the residual air from the balloon catheter. An alternative configuration is shown in <FIG> wherein the exhaust port <NUM> has been replaced by an inflatable lung, container or sac <NUM> to store therein the residual air that has been proximally purged from the balloon catheter.

In operation of the present exemplary balloon catheter, inflation medium (preferably, <NUM>% contrast saline solution) is introduced into the catheter using a syringe or other dispensing device attached to the inflation port of the hub. The inflation medium travels through the inflation lumen and into the deflated balloon. A microporous membrane located at the interface of the balloon and exhaust lumen has pores that are sized to prohibit the passage therethrough of the inflation medium, allowing only the residual air to pass out of the balloon and through the exhaust lumen. As the balloon fills with the inflation medium it inflates. Coinciding with the inflation of the balloon, the pressure inside the balloon increases causing the residual air in the balloon to be automatically exhausted or vented in a proximal direction through the exhaust lumen. At the hub, the residual air exiting from the balloon catheter may be controlled using a sealable <NUM>-way exhaust valve and/or the purged residual air can be stored in an inflatable or expandable purge lung thereby removing the residual air from the system and storing it outside of the body in the hub by taking advantage of the fact that it is compressible.

By way of non-limiting example, numerous configurations of one or more exhaust lumen and one or more inflation lumen, each arranged radially outward from the main lumen in the balloon catheter <NUM> are shown and described. Additional configurations are possible and within the intended scope of the present invention with the common feature among the different configurations that the residual air is exhausted through the exhaust lumen in a proximal direction, rather than in a distal direction, from the catheter. Several exemplary designs of the exhaust and inflation lumen as well as their arrangement relative to one another in the balloon catheter are illustrated in <FIG>. In <FIG>, the inflation lumen 125A has a curved segment radial cross-section whose radius of curvature shares a common center (coaxial; concentric) with that of the main/guidewire lumen 123A. Two exhaust lumen 120A having a circular radial cross-section are illustrated radially displaced from one another as far as possible within the inflation lumen 125A, but any number of one or more exhaust lumen may be provided, as desired, as well as the location or spacing of the exhaust lumen(s) 120A within the inflation lumen 125A. <FIG> is an alternative configuration wherein each of the exhaust and inflation lumens 120B, 125B, respectively, has a curved segment radial cross-section whose radius of curvature shares a common center (coaxial; concentric) with that of the main/guidewire lumen 123B. Yet another configuration is depicted in <FIG>. Similar to <FIG>, the inflation lumen 125C in <FIG> has a curved segment radial cross-section whose radius of curvature shares a common center (coaxial; concentric) with that of the main/guidewire lumen 123C. However, in this particular design a single exhaust lumen 120C is separate, distinct and independent of the inflation lumen 125C (not disposed within the inflation lumen, as in <FIG>). While still another possible configuration is illustrated in <FIG>. Like that of <FIG>, each of the exhaust and inflation lumens 120D, 125D, respectively, in <FIG> has a curved segment radial cross-section whose radius of curvature shares a common center (coaxial; concentric) with that of the main/guidewire lumen 123A. <FIG> differs from <FIG> in that the exhaust and inflation lumen 120D, 125D, respectively, are arranged approximately <NUM> degrees radially separated from one another (mirror images of one another). In another embodiment the curved inflation and exhaust lumens may be 'D' shaped or have a smaller/larger radius or curvature than that of the main/guidewire lumen. These are only non-limiting illustrative examples of different arrangements of the main, exhaust and inflation lumens in the catheter.

<FIG> is a partial axial cross-sectional view of the respective distal ends of an exhaust lumen <NUM> and inflation lumen <NUM> coinciding with the balloon <NUM> according to the present invention, wherein the balloon is shown in a deflated (non-inflated) state. A localized fluid communication channel, basin or recess <NUM> is defined in the outer wall of the catheter shaft in a location anywhere in an axial direction that coincides with the balloon (e.g., proximal region of the balloon, mid region of the balloon, distal region of the balloon) so long as the channel is beneath/underneath (coincides with) the balloon <NUM>. As is clearly visible from the top view in <FIG>, the localized fluid communication channel <NUM> may be D-shape, however, other geometric shapes (e.g., circle, oval, etc.) are contemplated. Fluid communication between terminating distal ends of the respective inflation lumen <NUM> and exhaust/vent lumen <NUM> occurs within this localized fluid communication channel <NUM>. In <FIG>, the terminating distal ends of the respective exhaust and inflation lumen extend partially into the localized fluid communication channel <NUM>. Alternatively, the terminating distal ends of the respective exhaust and inflation lumen may coincide with the perimeter or interface of the localized communication channel <NUM>. <FIG> is a radial cross-sectional view through the localized fluid communication channel <NUM> along lines IV(C) - IV(C) of <FIG> depicting the side-by-side configuration of the terminating distal ends of the respective inflation and exhaust lumens <NUM>, <NUM> therein. While in a deflated (non-inflated) state, balloon <NUM> is taut around the outer surface of the catheter shaft, as shown in <FIG>. As a result, following the path of least resistance, the residual air advanced through the inflation lumen <NUM> by the pressurized injected inflation medium is expelled proximally through the exhaust lumen <NUM> and from the catheter, without inflating the balloon <NUM>.

According to the present invention, alternative arrangements or configurations of the terminating distal ends of the respective exhaust and inflation lumen within the localized fluid communication channel <NUM> radially outward from the main/guidewire lumen <NUM> are depicted in the different radial cross-sectional views in <FIG>. Addressing each separately, in <FIG>, inflation lumen <NUM> and exhaust lumen <NUM> are side-by-side in physical contact with one another and equal both in inner and outer diameters. <FIG> illustrates again a side-by-side arrangement with the two lumens in physical contact with one another within the localized fluid communication channel <NUM>, however, the lumen differ in both inner and outer diameters. Specifically, the outer diameter of inflation lumen <NUM> is smaller than the outer diameter of the exhaust lumen <NUM>, but the inner diameter of the inflation lumen <NUM> is larger than the inner diameter of the exhaust lumen <NUM>. Preferably, the inner diameter of the inflation lumen is greater than the inner diameter of the exhaust lumen since the exhaust lumen merely functions to exhaust the residual air. In the arrangement in <FIG>, the inflation and exhaust lumens <NUM>, <NUM> again are disposed side-by-side in physical contact with one another within the localized fluid communication channel <NUM>. The outer diameters of the inflation and exhaust lumen are equal in diameter, while the inner diameter of the inflation lumen <NUM> is greater than that of the exhaust lumen <NUM>. Any combination or permutation of these arrangements of the exhaust and inflation lumens within the channel as well as the sizes of the inner and outer diameters of each lumen is within the scope of the invention.

<FIG> is a top view of a partial distal section of still another configuration of the present inventive balloon catheter having a single localized fluid communication channel defined in the shaft in which distal terminating ends of respective exhaust and inflation lumen coincide within the single localized fluid communication channel. Disposed about a portion of the outer perimeter of the catheter shaft is a surface profile <NUM> that coincides with the localized fluid communication channel <NUM> to promote the flow of fluid from the inflation lumen <NUM> to the exhaust lumen <NUM>. Preferably, the surface profile <NUM> is a mesh made of polymeric, metal and/or other material wrapped about the outer surface of the catheter shaft. The balloon extends axially so as to completely cover or enclose the surface profile <NUM>. A radial cross-sectional profile through the single localized fluid communication channel <NUM> would be similar to that illustrated in <FIG>, although different arrangements such as those shown in <FIG> are possible, as desired.

Not forming part of the invention, <FIG> is a top view of still another configuration in which the terminating distal end of the inflation lumen <NUM> coincides with a first localized fluid communication channel <NUM>', while the terminating distal end of the exhaust lumen <NUM> coincides with a second localized fluid communication channel <NUM>" displaced axially apart from the first localized fluid communication channel <NUM>'. In this arrangement, the surface profile <NUM> coincides with both the first and second localized fluid communication channels <NUM>', <NUM>". Once again, the surface profile <NUM> promotes fluid communication between inflation and exhaust lumens which is particularly applicable in this arrangement wherein the first and second localized fluid communication channels <NUM>', <NUM>" are displaced axially from one another along the catheter shaft.

A top view of a section of the catheter shaft (without the balloon) shown in <FIG> shows a first localized fluid communication channel as a punched hole (e.g., oval, circle, etc.) defined in an outer surface of the catheter shaft. The terminating distal end of the inflation lumen <NUM> extends partially into the punched hole <NUM> in <FIG>, whereas in <FIG> the terminating distal end of the inflation lumen <NUM> is aligned with the interface of the punched hole <NUM>, that is, the terminating distal end of the inflation lumen does not extend into the punched hole. A radial cross-sectional view through the first localized fluid communication channel <NUM> of <FIG> along lines IV(K)-IV(K) is shown in <FIG>. The position of the inflation lumen <NUM> within the first localized fluid communication channel <NUM> in <FIG> is to the left; however, the position may be selected, as desired, anywhere within the first localized fluid communication channel <NUM> (e.g., midway within the channel, to the right within the channel, etc.). As previously mentioned, in the scope of the invention, terminating distal ends of respective inflation and exhaust lumens may be aligned with (coincide with) an interface of a single punched hole defined in the outer surface of the catheter shaft serving as the single localized fluid communication channel, as shown in <FIG>.

<FIG> shows an exemplary balloon catheter <NUM> with the balloon <NUM> in an inflated state at a target site in an artery <NUM>. Syringe <NUM> or other injection device is connected to the inflation port <NUM> in <FIG> to introduce inflation medium (e.g., <NUM>/<NUM> contrast/saline solution) into the inflation lumen. A one-way or manual valve <NUM> is connected to the exhaust port <NUM> to control the purging of residual air from the catheter. The main/guidewire port or opening <NUM> is also provided in the hub <NUM> for receiving a guidewire <NUM> therein.

<FIG> is a perspective view of yet another configuration of the present inventive balloon guide catheter having dual lumen (one inflation lumen <NUM> and one exhaust lumen <NUM>) defined in the outer wall of the catheter shaft, aside from the main lumen <NUM>. Terminating distal ends of the respective inflation and exhaust lumens <NUM>, <NUM> coincide with a localized fluid communication channel, recess or basin <NUM>. The localized fluid communication channel <NUM> is where the terminating distal ends of the respective inflation and exhaust lumens are in fluid communication with one another. A balloon, not illustrated in <FIG>, is assembled taut or snug about the outer surface of the distal region of the catheter shaft covering the localized fluid communication channel <NUM>. The side-by-side axial arrangement of the radial section inflation and exhaust lumens <NUM>, <NUM> disposed in the outer wall of the outer shaft radially outward from the main lumen <NUM> is shown in <FIG>. Different arrangements of the one or more inflation lumen and one or more exhaust lumen are possible, such as, but not limited to, those depicted in <FIG>. A proximal hub <NUM> is connected to the proximal end of the balloon guide catheter. Hub <NUM> includes a main/guidewire port <NUM>, an inflation port <NUM> and an exhaust/vent port <NUM>. A valve <NUM> is disposed at the exhaust port <NUM>.

<FIG> is a cross-sectional axial view of the hub <NUM> in <FIG>, wherein a <NUM>-way valve <NUM> is oriented or positioned for inflation of the balloon with an inflation medium (e.g., <NUM>/<NUM> contrast/saline solution) injected into the inflation port <NUM> (via a syringe <NUM> similar to that shown in <FIG>). Inflation medium injected into the inflation port <NUM> enters an inflation opening <NUM> in the outer wall of the catheter shaft and fills the inflation lumen <NUM>. Upon the inflation medium reaching the localized fluid communication channel it enters the exhaust lumen <NUM> and travels proximally therethrough exiting from the vent opening <NUM> and into the hub <NUM>. As the inflation medium is dispensed from the syringe under pressure and travels through the catheter residual air from within the inflation lumen and balloon is vented, purged or exhausted proximally from the catheter. Valve <NUM> disposed distally of the exhaust port <NUM> is oriented or positioned in <FIG> in an open state allowing the flow of residual air therethrough which then passes out of the exhaust port <NUM> via a microporous membrane or filter <NUM>. Pores or openings of the microporous membrane or filter <NUM> are sized to permit the passage therethrough of residual air, while prohibiting or preventing passage therethrough of the inflation medium. Once the residual air has been fully purged from the catheter, any additional flow of the inflation medium or increase in pressure applied by the syringe causes the balloon to inflate. Flow rates of the inflation medium are maintained so that full venting of residual air occurs without sufficient pressure built-up or generated in the catheter to initiate inflation of the balloon.

The localized fluid communication channel <NUM> underneath the balloon is designed so that both lumens (the exhaust lumen <NUM> and the inflation lumen <NUM>) communicate allowing residual air and inflation medium to flow out from the terminating distal end of the inflation lumen and into the terminating distal end of the exhaust lumen.

Deflation of the balloon is achieved by attaching a vacuum (e.g., syringe) to the inflation port <NUM> creating a negative pressure within the catheter. When it is time to deflate the balloon, valve <NUM> is oriented to close off flow to the exhaust port <NUM>. Upon application of a vacuum or suction (e.g., syringe) attached to the inflation port <NUM> creating a negative pressure within the catheter the inflation medium exhausted from the exhaust lumen is redirected into the bridge fluid communication channel <NUM>, combining with the inflation medium vented through the inflation lumen and out from the inflation port <NUM>. This unique hub configuration and, in particular, the orientation or positioning of the valve during deflation to close off the exhaust port <NUM>, upon application of a vacuum to the inflation port provides for the removal of inflation medium simultaneously through both inflation and exhaust lumens thereby optimizing deflation of the balloon.

Preferably, the configuration of the hub <NUM> is optimized by minimizing its overall axial length in order to minimize cost of manufacture as well as minimize the unusable length of hub that other catheters go through. It is also contemplated to replace the <NUM>-way manual valve <NUM> with a spring-loaded or ball valve that is automatically actuated upon the introduction of a suction or vacuum applied to the inflation port <NUM>.

Exhausting of residual air from the present inventive balloon catheter is less complicated requiring less time to accomplish than conventional devices. In accordance with the present invention, air is automatically purged in the proximal direction from the balloon catheter. Specifically, preparation of the present inventive balloon catheter starts with inflation medium being passed through the inflation lumen which coincides with the residual air being purged, evacuated or exhausted from the system in a proximal direction via the exhaust lumen reducing preparation time. Furthermore, since the residual air is vented in a proximal direction safety concerns associated with purging air once the catheter has been introduced in the body have been eliminated.

The present inventive closed loop proximal venting system has several advantages. Since the residual air is vented in a proximal direction preparation of the device by the interventionalist may occur while the device is in the patient. Another benefit of the present inventive closed loop proximal design is that the inflation medium automatically expels the residual air/gas through the microporous membrane and out the exhaust lumen while the inflation medium is prevented from passing through the microporous membrane thereby causing the balloon to inflate and expand. Accordingly, the need for a valve or other mechanical device for causing the balloon to inflate once the residual air has been purged has been eliminated in accordance with the present invention.

Claim 1:
A balloon guide catheter system comprising:
a balloon guide catheter (<NUM>), comprising:
a catheter shaft with a proximal end (<NUM>) and an opposite distal end (<NUM>); wherein the catheter shaft includes: (i) a main lumen (<NUM>) defined axially through the catheter shaft; (ii) an inflation lumen (<NUM>) extending axially along the catheter shaft; the inflation lumen (<NUM>) having a proximal end, an opposite terminating distal end; (iii) an exhaust lumen (<NUM>) extending axially along the catheter shaft, the exhaust lumen (<NUM>) having a proximal end and an opposite terminating distal end;
wherein the catheter shaft has an outer surface with a first localized fluid communication channel (<NUM>) defined therein located underneath the balloon (<NUM>) via which the terminating distal ends of the respective inflation (<NUM>) and exhaust (<NUM>) lumens are in localized fluid communication with one another underneath the balloon (<NUM>) while in a non-inflated state;
a balloon (<NUM>) disposed about a distal region (<NUM>) of an outer surface of the catheter shaft; and
wherein the exhaust lumen (<NUM>) is configured to purge the residual air in a proximal direction and out from a proximal region of the balloon guide catheter (<NUM>).