A HEMOSTATIC VALVE

BACKGROUND OF THE INVENTION

This invention generally relates to intravascular catheters, such as balloon dilatation catheters used in percutaneous transluminal coronary angioplasty (PTCA).

PTCA is a widely used procedure for the treatment of coronary- heart disease. In this procedure, a balloon dilatation catheter is advanced into the patient's coronary artery and the balloon on the catheter is inflated within the stenotic region of the patient's artery to open up the arterial passageway and increase the blood flow therethrough. To facilitate the advancement of the dilatation catheter into the patient's coronary artery, a guiding catheter having a preshaped distal tip is first percutaneously introduced into the cardiovascular system of a patient by the Seldinger technique through the brachial or femoral arteries. The catheter is advanced until the preshaped distal tip of the guiding catheter

is disposed within the aorta adjacent the ostium of the desired coronary artery. The guiding catheter is twisted or torqued from the proximal end, which extends out of the patient, to guide the distal tip of the guiding catheter into the ostium. A balloon dilatation catheter may then be

advanced through the guiding catheter into the patient's coronary artery until the balloon on the catheter is disposed within the stenotic region of the patient's artery. The balloon is inflated to open up the arterial passageway.

One type of catheter frequently used in PTCA procedures is an over-the-wire type balloon dilatation catheter. Commercially available over-the-wire type dilatation catheters include the SIMPSON ULTRA-LOW PROFILE ^® , the HARTZLER ACX ^® , the HARTZLER ACX II ^® , the PINKERTON .018™ and the ACS TEN™ balloon dilatation catheters sold by the assignee of the present invention, Advanced Cardiovascular

Systems, Inc. (ACS). When using an over-the-wire dilatation catheter, a guidewire is usually inserted into an inner lumen of the dilatation catheter before it is introduced into the patient's vascular system and then both are introduced into and advanced through the previously positioned guiding catheter. The guidewire is first advanced out the seated distal tip of the guiding catheter into the desired coronary artery until the distal end of the guidewire extends beyond the lesion to be dilatated. The dilatation catheter is then advanced out of the distal tip of the guiding catheter into the patient's coronary artery, over the previously advanced guidewire, until

the balloon on the distal extremity of the dilatation catheter is properly positioned across the lesion to be dilatated. Once properly positioned across the stenosis, the balloon is inflated one or more times to a predetermined size with radiopaque liquid at relatively high pressures {e.g., generally 4- 12 atmospheres) to dilate the stenosed region of a diseased artery. After the inflations, the balloon is finally deflated so that the dilatation catheter can be removed from the dilated stenosis.

Other types of dilatation catheters are well known and commercially available such as fixed wire, rapid exchange and perfusion type dilatation catheters.

Multiple arm adapters are usually connected to the proximal ends of guiding catheters. A side arm of the adapter is employed to direct radiopaque liquid into the patient's coronary anatomy for purposes of angiography and a central arm of the adapter is used to insert guidewires, dilatation catheters and the like into and through the guiding catheter. The central arm of the adapter is usually provided with a rotating hemostatic valve in order to control the loss of blood out of the adapter during an angioplasty procedure. However, the use of the hemostatic valve complicates and lengthens the time for the angioplasty procedures. Each time a dilatation catheter or a guidewire is to be moved within the guiding catheter, the hemostatic valve must be loosened to allow the movement and

then retightened after the catheter or guidewire movement is complete in order to prevent the loss of blood through the valve.

What has been needed and heretofore unavailable is a hemostatic valve assembly which facilitates catheter movement through the valve without having to change the valve position to allow catheter movement and then retighten the valve to prevent blood loss each time the catheter is moved. The present invention satisfies these and other needs.

SUMMARY OF THE INVENTION

This invention is directed to a guiding catheter assembly for intravascular catheters and particularly to a sheath which is suitable for use within a hemostatic valve in an adapter on the proximal end of a guiding catheter.

A sheath of the invention comprises an elongated hollow tubular element which has an exterior shaped and dimensioned to be inserted into the passageway of a hemostatic valve and which has a wall of sufficient thickness and strength so that the tubular element will not collapse upon tightening of the hemostatic valve against the exterior of the tubular element. The transverse shape of the tubular element of the sheath is generally circular, but other transverse cross-sectional shapes are possible. A tab or handle is provided on the proximal end of the tubular element

forming the sheath to facilitate movement of the sheath within the hemostatic valve.

The tubular element has a passageway which is adapted to slidably receive a catheter, guidewire or other intravascular device. The clearance between the inner surface of the tubular element which defines the passageway and the catheter, guidewire or other intervascular device is controlled so that there is little or no tendency for backbleeding through the clearance during an intravascular procedure. In some instances it may be desireable to provide a coating of hydrophilic material on the inner surface of the tubular element which swells upon contact with blood or other aqueous based fluid to further reduce the size of the clearance and which can decrease the friction between the sheath and the catheter, guidewire or other intravascular device disposed within the passageway by the lubricous nature of the hydrophilic material.

The hemostatic valve assembly of the invention generally includes a rotating hemostatic valve which is part of the central arm of a multi-arm adapter and a tubular sheath as described above which is adapted to be inserted into the passageway of the hemostatic valve. The wall strength of the tubular sheath is sufficiently high so the hemostatic valve can be tightened in a sealing engagement against the exterior of the sheath without significantly deforming the sheath.

In one presently preferred embodiment of the invention the sheath is mounted about the exterior of an intravascular device such as a catheter or guidewire which is to be advanced through a multi-arm adapter on the proximal end of a guiding catheter. The clearance between the inner diameter of the sheath and the outer diameter of the catheter or guidewire is sufficiently small so that little or no blood will pass through the clearance between the sheath and the intravascular device during an intravascular procedure. By eliminating or at least significantly reducing the backbleeding through the adapter during an intravascular procedure, the field around the site of the percutaneous introduction of the catheters is maintained relatively blood-free. When the rotating hemostatic valve on the adapter is tightened against the exterior of the tubular sheath, the sheath is secured within the adapter. The catheter guidewire or other intravascular device slidably disposed within the tubular sheath can be readily advanced or withdrawn through the inner passageway which extends through the sheath without the need for opening or closing the hemostatic valve and the attendant blood loss these procedures entailed. These and other advantages of the invention will become more apparent from the following detailed description and the accompanying exemplary drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

Fig. 1 is an elevational view, partially in cross section, of a dilatation catheter disposed within a guiding catheter having a sheath embodying features of the invention mounted about the catheter shaft.

Fig. 2 is a transverse cross-section of the catheter and sheath shown in Fig. 1 taken along the lines of 2-2.

Fig. 3 is a longitudinal view partially in cross-section of the

adapter on the proximal end of a guiding catheter.

Fig. 4 is a transverse cross-sectional view of the adapter shown in Fig. 3 taken along the lines 4-4.

Fig. 5 is a perspective view of the sheath shown in Figs. 1, 3 and 4.

DETAILED DESCRIPTION OF THE INVENTION

Figs. 1 and 2 illustrate a dilatation catheter 10 which is disposed within a guiding catheter 11. An adapter 12 with a Luer connection is provided on the proximal end of the guiding catheter 11 and a multi-arm adapter 13 is connected to the proximal end of the adapter 12. The proximal end of the dilatation catheter 10 extends through the adapters 12 and 13 and the distal end of the dilatation catheter extends through the shaped distal end of the guiding catheter 11. In accordance with the

invention, a sheath 16 of the invention extends out the proximal end of central arm 17 of the adapter 13 with the dilatation catheter 10 slidably disposed within the inner passageway 18 of the sheath. The distal end of

the guiding catheter 11 is shaped to facilitate entry into a particular coronary artery and may have a variety of well known shapes including Judkins and Amplatz shapes. The distal end of the dilatation catheter 10, which extends out of the shaped distal end of the guiding catheter 11, has an inflatable dilatation balloon 14 and the distal end of a guidewire or guiding member 15 which extends out the distal end of the balloon is provided with a flexible coil. The dilatation catheter 10 is illustrated in Figs. 1 and 2 in a general fashion and may be an over-the-wire, a fixed- wire or a rapid exchange type dilatation catheter.

As illustrated in Figs. 1, 3 and 5, the sheath 16 generally has an elongated tubular body 20 with a handle or tab 21 on its proximal end which facilitates the movement of the sheath on the catheter shaft 22 and within the adapter 13. A longitudinal slit 23 may be provided in the wall of the sheath 16 to facilitate mounting the sheath onto or removing the sheath from an elongated intravascular device. While not shown in the drawings, the proximal end of the sheath 16 may be expanded to facilitate insertion of a catheter or guidewire into the passageway 18. The spacing or clearance 24 between the exterior of the catheter shaft 22 and the interior of the sheath 16, shown in Figs. 3 and 4, is dimensioned so that there is sufficient spacing for the dilatation catheter 10 to be readily moved

longitudinally within the inner passageway 18 of the sheath 16, but the clearance is sufficiently small to prevent a substantial amount of blood loss or backbleed through the sheath during an angioplasty or other intravascular procedure. The clearance 24 which will preclude significant backbleed in most instances ranges from about 0.0005 to about 0.0050 inch (0.013 to 0.127 mm), preferably about 0.0010 to about 0.0020 inch (0.025 to about 0.051 mm). The longer the sheath the greater the clearance 24 may

be. The OD of the sheath 16 ranges from about 0.060 to about 0.073 inch (1.549 to 1.854 mm) and the ID ranges from about 0.0340 to about 0.0360 inch (0.864 to 0.914 mm). The wall thickness is about 0.0125 to about 0.0195 inch (0.318 to 0.495 mm).

Figs. 3 and 4 illustrate the sheath 16 disposed within a hemostatic valve 25 on the proximal end of arm 17 of adapter 13. The hemostatic valve 25 includes an elongated tubular housing 26, which forms the proximal portion arm 17 of the adapter 13, an inner passageway 27, an inwardly projecting shoulder 28 which is adapted to receive the distal end of a bullet shaped ring gasket 30 and a rotating cap 31 threadably mounted onto the proximal end of the tubular housing 26. The rotating cap 31 has a tubular shaft or stem 32 which extends into the passageway 27 and is adapted to engage the proximal end of the ring gasket 30. Rotation of the cap 31 in a clockwise direction will tighten the cap on the threaded proximal end of the tubular housing 26 and press the distal end of the tubular shaft 32 against the proximal end the ring gasket 30,

compressing the ring gasket in the longitudinal direction and causing the ring gasket to expand into the passageway 27 and exert a sealing pressure against the exterior of the sheath 16.

In a presently preferred embodiment of the invention, the sheath

16 may be either mounted about the shaft 22 of the dilatation catheter 10 (or the shaft of any intravascular device which is to be slidably disposed

within the passageway 27 of the sheath) or the sheath may be provided separately with the catheter or other intravascular device as a kit. In the latter instance, a longitudinal slit 23 will usually be required in the sheath wall so that the sheath can be readily mounted onto the shaft of the intravascular device.

With the sheath 16 slidably mounted onto the catheter shaft 22, the catheter 10 may be inserted through the aperture 33 in the rotating cap 21 of the adapter 13 into the inner lumen 34 which extends through the tubular stem 32 and then through the passageway 27 of the tubular housing 26 through the passageway 35 of the ring gasket 30 and through the inner lumen 36 which extends through the length of the guiding catheter 11. The sheath 16 is manually positioned within the adapter 13 so that it extends distally at least through the passageway 35 of the ring gasket 27 and proximally out of the aperture 33 in the cap 31. The sheath 16 is easily moved by means of the tab 21 which is formed on the proximal end of the sheath 16. Once the sheath 16 is in proper position, the cap 31

is rotated clockwise to tighten the cap on the proximal end of the adapter 13 and at the same time press the tubular stem 32 against the proximal end of the ring gasket 31 to cause the ring gasket to sealingly engage the exterior of the sheath 16 and secure the sheath within the adapter. The wall of the sheath 116 is of sufficient strength and thickness to prevent the deformation or collapse of the sheath and maintain the desired clearance 24 between the dilatation catheter 10 and the interior of the sheath.

The dilatation catheter 10 can be readily advanced through the

sheath 16 and the guiding catheter 11 until the balloon 14 on the dilatation catheter extends out of the distal end of the guiding catheter and into a stenosis within a patient's artery. With an over-the-wire system utilizing a guidewire, the guidewire can be first advanced out the distal end of the guiding catheter into the patient's artery until the guidewire crosses the stenosis to be dilatated and then the dilatation catheter can be advanced out of the guiding catheter into the artery over the in-place guidewire until the balloon is situated within the stenosis. The balloon 14 can then be inflated to dilate the stenosis. This entire procedure can be completed without the need to adjust the position of the hemostatic valve and with little or no loss in blood through the proximal end of the adapter. Other types of dilatation catheters such as fixed-wire and rapid exchange type dilatation catheters can be utilized in the same or similar manner.

The dilatation catheter 10, the guiding catheter 11, the adapters 12 and 13 and the sheath 16 may be made of conventional materials well known to those skilled in the art, including polyethylene, polyvinyl

chloride and polyolefinic ionomers. The ring gasket may be made of natural or synthetic rubber, elastomers and the like.

While in a presently preferred embodiment the sheath 16 is slidably mounted onto the shaft 22 of the dilatation catheter 10, the sheath 16 may be provided within the adapter on the guiding catheter. The sheath 16 may also be included separately in a kit with the dilatation catheter or the guidewire. They may be easily included in the respective catheter and guidewire packages.

The present invention has been described herein in terms of certain presently preferred embodiments. Those skilled in the art will recognize that various modifications and improvements can be made without departing from the scope of the invention.