CROSS REFERENCE TO RELATED APPLICATIONS

This application claims the benefit of U.S. Provisional Application 60/488,635, entitled Enhanced Dilatation Catheter For Treatment Of Aortic Stenosis, filed Jul. 18, 2003 and U.S. Provisional Application 60/547,896 entitled Catheter For Treatment of Aortic Valves, filed Feb. 25, 2004, the entire contents of each being hereby incorporated by reference.

FIELD OF INVENTION

This invention relates to balloon catheters and other related mechanical devices for medical use. More particularly, this invention relates to balloon catheters with advanced anchoring and valvuloplasty capabilities. The invention also relates to controlling the expansion and force properties of a balloon in a balloon catheter through various means, including the reinforcement of the balloon through fibers located on the balloon.

BACKGROUND OF THE INVENTION

Calcific aortic stenosis is a common cause of acquired valvular heart disease with substantial morbidity and mortality. Its incidence increases exponentially in older patient populations. Fibrosis, degeneration and subsequent calcification are no longer believed to be passive or purely degenerative in nature, but in fact are predominantly active processes mediated by underlying cellular mechanisms. Over time, as fibrosis and calcification worsens, valve leaflets become increasingly rigid, restricting their ability to open. This in turn, then impedes the antegrade flow of blood through the heart resulting in several clinical syndromes including most significantly progressive heart failure. Other causes of deformed and stenotic aortic valvular lesions include rheumatic heart disease, as well as nonacquired (i.e. congenital) heart disease. Initial stages of stenotic valvular heart conditions are well tolerated by the patient, but when leaflet restriction becomes severe, drastic measures such as aortic valve replacement have commonly been required.

With the advent of catheter-based cardiovascular procedures, minimally invasive valvuloplasty techniques were developed to dilate stenosed valves, most commonly calcific aortic stenosis but also rheumatic and congenitally stenosed leaflets using catheter balloons. During this procedure, a catheter having a deflated balloon is percutaneously inserted into a vein or artery and advanced until the balloon is positioned within the heart valve needing treatment. The balloon is then inflated to dilate the diseased valve opening, disrupting the rigid sheets of calcium permitting enhanced leaflet mobility. Balloon dilation, depending on the disease process, may result not only in the development of numerous flexible hinge points within fibrosed and calcified leaflets but, in addition, separation of fused commissures can take place. After the leaflets have been dilated, the balloon is deflated and removed from the patient's cardiovascular system.

In many current instances, valvuloplasty is performed with polyethylene balloon catheters which can achieve relatively high pressures at a fixed diameter. Balloons made of non-distensible plastic materials are expanded using fluid pressure up to a certain diameter after which, increases in fluid pressure within the balloon produce very little change in balloon diameter. These balloons can achieve high pressures for an effective therapy, but inherent to this plastic material are several limitations. The profile of these balloons can be somewhat reduced by prefolding during the manufacturing process. However, once inflated, the folded balloon segments are expanded within the vascular system and when deflated for removal, do not return to their compact, prefolded state but to a flattened state with a much larger profile. Withdrawal of these balloons therefore requires larger vascular introductory sheaths and thereby increases the risk of trauma to the vessels, resulting in compromised blood flow to an extremity or post operative bleeding. Additionally, non-distensible balloons also have thick conesâ€”transitions from the cylindrical diameter to the catheter shaft diameter. These regions of the balloon make the catheter stiff increasing the risk of vascular trauma and making it difficult to advance through tortuous peripheral arterial anatomy.

Since the radial dimensions of the catheter balloon must greatly increase when inflated to achieve aortic valve dilation, a highly elastic material such as latex can be used, but with significant limitations. Distensible balloons use these elastic materials and generally have excellent initial profiles and improved flexibility for introduction and travel through the vascular system. In addition, they possess good deflated profiles for removal from the vascular system. However, elastic materials such as this continue to expand in diameter as pressure increases and therefore have no inherent limit on maximal diameter as with non-distensible balloons. Thus, distensible balloons can be unsafe for such a purpose as valvuloplasty, as the elastic limit can easily be exceeded when the balloon is fully inflated, potentially causing the balloon to rupture within the patient. Additionally, the balloon diameters can become too large for the valve being dilated causing rupture and tearing of both the valve and its adjacent structures.

In addition, prior art catheter balloons have been associated with mechanical injury to the cardiac chambers, especially near the ventricular apex, due to the forceful longitudinal movement of the inflated balloon across the valve and within the cardiac chamber as the heart beats. Blood, and the vascular wall surface, are inherently slippery against common catheter balloons further increasing the risk of significant balloon migration. As inflation fluid (contrast media) is introduced, the catheter balloon enlarges and eventually assumes a cylindrical or ovoid shape. This creates a tendency for the balloon to suddenly and uncontrollably pop in and out of the valve site and migrate deep into the left ventricle. In some situations, this sudden balloon movement following inflation has not only made it difficult to position accurately within the valve leaflets but again has led to damage and even catastrophic puncturing of the left ventricle.

Further, typical catheter balloon shapes tend to completely obstruct the flow of blood through the heart while inflated. Without perfusion through or around the catheter, the catheter balloon inflation time is limited to a few seconds before risking complications due to profound hypotension.

A further disadvantage of prior art valvuloplasty balloons is their frequent failure to restore adequate flexibility to the aortic valve leaflets. That is, mere dilation with these previous balloon designs may not be enough to adequately open the severely fibrosed and calcified leaflets. The prior art balloon catheters are cylindrical in shape when fully inflated and thus have their maximal inflated diameter limited by the narrower sinotubular ridge and valve annulus at the proximal and distal margins of the aortic root sinuses. Efforts to expand beyond these limits for enhanced valve opening can result in tearing of the aortic valve annulus, catastrophic aortic insufficiency or rupture of the aortic root. In addition, traditional balloon catheter methods generally result in eventual restenosis of the aortic valve leaflets, negating some or all of the regained flexibility.

Examples of some of these prior art catheter designs, as well as other related catheter designs are discussed and disclosed in the following U.S. patent documents: U.S. Pat. Nos. 4,327,736; 4,777,951; 4,787,388; 4,878,495; 4,819,751; 4,909,252; 4,986,830; 5,352,199; and 5,947,924.

What is needed is a balloon valvuloplasty catheter that overcomes all of the these disadvantages of the prior art. Indeed, what is needed is an invention that not only overcomes the disadvantages of the prior art in treating calcific aortic stenosis but also aortic stenosis resulting from congenitally abnormal valves and/or rheumatically injured valves.

Of particular need is a balloon configuration that has expansion characteristics that not only stabilize the valvuloplasty catheter at a desired location but that also provides the necessary a-traumatic expansion force to successfully perform the valvuloplasty. Moreover, it is desired to meet this need either with a single reinforced balloon configuration or a dual balloon configuration.

OBJECTS AND SUMMARY OF THE INVENTION

It is an object of the present invention to provide a balloon catheter that overcomes the shortcomings of the prior art.

It is a further object of the present invention to provide a catheter that can anchor itself so as to create a stable catheter position during valvuloplasty.

It is an object of the present invention to provide a tapered distal balloon catheter segment which is better able to anchor itself within the left ventricular outflow tract. Anchoring to create stable catheter positions for valvuloplasty can also be accomplished by other novel embodiments introduced in this patent application.

It is a further object of the present invention to provide a balloon catheter segment that conforms more accurately to the valve annular ring to prevent over stretching, mechanical trauma, or even tearing of this supporting structure.

It is yet a further object of the present invention to provide a rounded proximal balloon catheter segment that conforms to the shape of the aortic root to improve leaflet opening by creating broader and more effective hinge points on the aortic valve leaflets.

It is yet a further object of the present invention to provide a balloon catheter which allows antegrade (forward) perfusion of blood.

It is a further object of the present invention to overcome the disadvantages of the prior art.

It is a further object of the present invention to provide a drug delivery device for providing local anti-restenotic therapies and therapies to result in stenosis regression.

The present invention achieves these objects by providing an aortic valvuloplasty catheter which, in one preferred embodiment, has a tapered distal balloon segment that anchors within the left ventricle outflow track of the a patient's heart and a more proximal rounded segment to broadly dilate the aortic valve leaflets into the aortic root sinuses. In addition, this embodiment of the valvuloplasty catheter may include a fiber-based balloon membrane to aid in achieving a lower profile, higher pressure balloon with a specific geometric shape. In addition, this embodiment may be configured to permit distal perfusion while the balloon is inflated. It may have a pigtail distal tip to minimize any likelihood of intracardiac trauma. The entire catheter may be advanced through an elongated sheath to assure greater stability and permit measurement of central aortic pressures.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1

illustrates a side view of an valvuloplasty catheter according to the present invention;

FIGS. 2A-2B

illustrate a side view of the valvuloplasty catheter of

FIG. 1

;

FIG. 3

illustrates a side view of a catheter sheath according to the present invention;

FIG. 4

illustrates a side view of a valvuloplasty catheter with a debris basket according to the present invention;

FIGS. 5A-5C

illustrate side views of a single balloon valvuloplasty catheter according to the present invention;

FIGS. 5D-5L

illustrate side view of a single balloon valvuloplasty catheter using various fiber reinforced balloon characteristics in accordance with the present invention;

FIGS. 6A-6C

illustrate side views of a ring and balloon catheter according to the present invention;

FIG. 7A

illustrates a side view of a longitudinal wire catheter according to the present invention;

FIG. 7B

illustrates a top view of a wire mounting ring of the longitudinal wire catheter of

FIG. 7A

;

FIG. 8

illustrates a side view of a center channel catheter according to the present invention;

FIG. 9

illustrates a side view of a center channel catheter according to the present invention;

FIGS. 9A-9B

illustrates a side view and a top view of a center channel catheter according to the present invention;

FIG. 10A

illustrates a side view of a valvuloplasty perfusion catheter according to the present invention;

FIG. 10B

illustrates a bottom view of the valvuloplasty perfusion catheter of

FIG. 10A

;

FIG. 11A

illustrates a side view of a dual balloon valvuloplasty catheter according to the present invention;

FIG. 11B

illustrates a top view of the dual balloon valvuloplasty catheter of

FIG. 11A

;

FIGS. 12A-12C

illustrate side views of an valvuloplasty catheter according to the present invention;

FIGS. 13A-13B

illustrate side views of an valvuloplasty catheter according to the present invention;

FIG. 14A

illustrates a side view of a petal anchoring catheter according to the present invention;

FIG. 14B

illustrates a top view of petals of the petal anchoring catheter of

FIG. 14A

;

FIGS. 15A-15B

illustrate a petal anchoring catheter according to the present invention;

FIG. 15C

illustrates a top view of petals of the petal anchoring catheter of

FIG. 15A

;

FIG. 16

illustrates a side view of a drug eluting device according to the present invention;

FIG. 17A

illustrates a side view of a drug eluting device according to the present invention;

FIG. 17B

illustrates a top view of the drug eluting device according in

FIG. 17A

;

FIG. 18

illustrates a top view of a drug eluting device according to the present invention;

FIG. 19

illustrates a side view of a drug eluting device according to the present invention;

FIG. 20A

illustrates a side view of a drug eluting device according to the present invention;

FIG. 20B

illustrates a side view of the membrane of the drug eluting device of

FIG. 20A

;

FIG. 20C

illustrates a side view of a locking post of the drug eluting device of

FIG. 20A

;

FIG. 21A

illustrates a side view of an valvuloplasty catheter according to the present invention;

FIG. 21B

illustrates a bottom view of the valvuloplasty catheter of

FIG. 21A

;

FIG. 21C

illustrates a side view of the valvuloplasty catheter of

FIG. 21A

;

FIG. 21D

illustrates a side view of the valvuloplasty catheter of

FIG. 21A

;

FIGS. 21E-21K

illustrate various top and side views of a valvuloplasty catheter that has perfusion channels which are formed by fiber reinforced structures in accordance with the present invention;

FIG. 22

illustrates a side view of an off center valvuloplasty catheter according to the present invention; and

FIGS. 23A-23C

illustrate a side view of a mesh anchoring valvuloplasty catheter according to the present invention.

DETAILED DESCRIPTION OF THE INVENTION

During a typical valvuloplasty procedure, a balloon catheter is inserted percutaneously within a patient's vessel and advanced to a stenotic valve, for example, the aortic valve which is contiguous with the left ventricle of the heart. Once in a desired position within a valve, the catheter balloon is inflated with liquid contrast media, expanding the diameter of the balloon and forcing the valve leaflets open. By forcing the valve open for a brief time, the leaflets are able to regain at least a portion of their original flexibility, allowing for more normal cardiovascular function.

Aortic Valvuloplasty Catheter

Turning to

FIGS. 1

, 2A, and 2B, a preferred embodiment of an aortic valvuloplasty catheter 100 is illustrated in accordance with the present invention, having an elongated catheter shaft 106 with a proximal, aortic sinus dilatation balloon 102 and a distal LVOT anchoring balloon 104 at the distal end of the catheter shaft 106. The distal anchoring balloon 104 provides anchoring support to the valvuloplasty catheter 100 by expanding within the left ventricular outflow tract 130 (LVOT), thus allowing the aortic sinus balloon 102 to maintain a desired position to expand against the aortic valve leaflets 126.

The catheter shaft 106 has multiple lumens (not shown) positioned axially within the catheter shaft 106 body, similar to those used for balloon angioplasty catheters. Each of the lumens opens at a proximal end of the catheter shaft 106, within the control hub 116, and terminates at varying points near the distal end of the catheter shaft 106, such as at a proximal aortic sinus balloon port 110 or a distal anchoring balloon port 112. Typically, the catheter shaft 106 has at least 3 lumens: a lumen for a guide wire 118, a lumen to communicate an inflation media to the aortic sinus balloon port 110, and a lumen to communicate an inflation media to the anchoring balloon port 112. Note that connecting fittings 120 and 122 can be seen in

FIG. 1

, which connect the two inflation lumens to external media supplies (not shown). Additional lumens for pressure measurement could be added to this catheter for simultaneous aortic and left ventricular pressures to derive aortic valve gradients pre and post valvuloplasty.

Additionally, radiopaque markers 114 are positioned at various locations on the catheter shaft 106, to mark, for example, the proximal and distal boundaries of the aortic sinus balloon 102 and the distal anchoring balloon 104. As such, the radiopaque markers 114 serve as visual guides during a valvuloplasty procedure to further assist positioning the enhanced aortic valvuloplasty catheter 100 of the present invention in a desired position within a patient's vascular system.

An angulated pigtail 108 is located at the distal end of catheter shaft 106 to prevent mechanical damage to the patient while the enhanced valvuloplasty catheter 100 is operated. The angulated pigtail 108 has a single hole (not shown) at its immediate distal end for passage of a guide wire and pressure measurement after the guide wire is removed. The single end hole design provides a more accurate pressure measurement when the balloon segments are retracted proximal to the aortic valve, leaving just the pigtail within the left ventricle. In comparison, a pigtail 108 with multiple side holes disposed along the length of the pigtail section can leave some of the holes proximal as well as distal to the valve, leading to inaccurate valve gradient measurements. It should be noted, however, that multiple side holes can be included in the angulated pigtail 108 for additional uses, such as radiopaque dye injections, or other purposes.

The distal anchoring balloon 104 is located at the distal end of catheter shaft 106, near angulated pigtail 108. The distal anchoring balloon 104 inflates with media communicated by anchoring balloon port 112, so as to press against the structure of the LVOT, fixing the longitudinal position of the aortic valvuloplasty catheter 100. Preferably, the cross sectional surface contour of the distal anchoring balloon 104 does not engage the LVOT throughout its entire circumference. This will permit perfusion around the distal anchoring balloon 104. For example, the distal anchoring balloon 104 may have a cross sectional shape of a star, spiral, or donut, of which additional details and examples are discussed in greater detail below. However, a distal anchoring balloon 104 that engages the entire circumference of the LVOT may be used so long as it is operated by quick inflation followed by quick deflation.

Prior art catheter balloons have been associated with mechanical injury to the heart, especially near the ventricular apex, due to the strong tendency for the inflated balloon to abruptly migrate back and forth across the aortic valve, darting in and out of the left ventricle due to phasic blood flow. Accordingly, the distal anchoring balloon 104 of the catheter 100 of the present invention preferably has a reverse taper distally where it would be larger in diameter. In this manner, the distal anchoring balloon 104 more closely conforms to the anatomical structure of the LVOT, preventing abrupt back and forth movement. It should be noted that the distal LVOT anchoring balloon 104 can be shaped to many different forms, who's purpose it is again to more tightly engage the LVOT for longitudinal fixation. An example includes an hour glass configuration to accommodate the hypertrophic, i.e. proximal, left ventricle septal bulge seen in many patients. A more adhesive balloon surface can be created by an external balloon fiber or other implants to prevent balloon slippage.

Preferably, the distal anchoring balloon 104 functions under low inflation pressure, for example less than about 3 atm. The distal anchoring balloon 104 is sized to engage the LVOT of a patient, having the preferable exemplary dimensions of about 15-20 mm in length, 24-28 mm in diameter for the distal end and 20-24 mm in diameter for the proximal end. However, since the size and shape of a LVOT may vary from patient to patient, the final distal anchoring balloon 104 size and shape may be selected to more closely conform to each LVOT.

The aortic sinus balloon 102 is located proximal to the distal anchoring balloon, having a sinus balloon port 110 to communicate media for inflating the aortic sinus balloon 102 against the valve leaflets 126. When inflated, the aortic sinus balloon 102 preferably conforms to the rounded shape of the aortic sinuses (as best seen in

FIG. 2B

), enabling the leaflets 126 to be opened as broadly as possible. This rounded proximal segment 192 would in fact permit hyperextension of the valve leaflets 126 into the aortic sinuses 123, yielding greater valve leaflet opening and consequently greater reduction in aortic valve gradient. It preferably is distensible through a wide range of predetermined diameters to take advantage of the range of diameters seen for the aortic sinuses in various patients. For example, the inflated aortic sinus balloon 102 may preferably be capable of achieving a balloon diameter of about 24 mm at about 4 ATMs of pressure and about 28 mm at 6 ATMs of pressure. Alternately, the aortic sinus balloon 102 can be primarily volume driven so that the balloon will achieve a range of diameters determined by the volume of media instilled. Preferably, the aortic sinus balloon 102 is about 18 mm in length, with a maximal diameter of about 24-30 mm.

Both the aortic sinus balloon 102 and the distal anchoring balloon 104 may be composed of a semi-elastic plastic. However, as higher pressures are utilized, especially for the aortic sinus balloon 102, the balloon membrane typically must substantially increase in thickness to guard against rupture of the balloon 102. Furthermore, the resultant need for a larger vascular entry sheath results in the inherent risk for percutaneous vascular injury. In this regard, fiber-based membranes are preferably used for both balloons 102 and 104 to increase the balloon membrane strength without the need to substantially increase thickness. The fabric reinforced balloon is also capable of allowing the formation of a specified geometric shape to the expanded balloon. Examples of such fiber based balloon membranes can be seen in the currently pending and commonly owned U.S. patent application Ser. No. 09/974,220, entitled Material Useable For Medical Balloons And Catheters, filed Oct. 9, 2001, the contents of which are herein incorporated by reference.

As seen in

FIGS. 2A-3

, an elongated sheath 124 may be used to introduce the valvuloplasty catheter 100 and assist in stabilizing it across the aortic valve during inflation, by preventing back and forth motion. Additionally, the sheath 124 can be used to measure the central aortic pressure which is useful for perioperatively monitoring and in determining the aortic valve pressure gradient following valve dilation. The sheath 124 may be used with the present preferred embodiment or any other of the subsequent embodiments described within this application.

In operation, the aortic valvuloplasty catheter 100 of the present invention is introduced through the femoral or brachial artery using a Seldinger technique to place a vascular sheath introducer in the peripheral vessel. After placement of a guidewire (not shown) across the aortic valve, the aortic valvuloplasty catheter 100 of the present invention is advanced retrograde over the guidewire such that the pigtail 108 is positioned in the left ventricle. Next, the distal anchoring balloon 104 is positioned using fluoroscopy within the LVOT 130, just underneath the valve annulus 125. The distal anchoring balloon 104 is inflated with fluid, e.g., contrast media, which is communicated through anchoring balloon inflation port 112, best seen in

FIG. 2A

. The distal anchoring balloon 104 expands in diameter as contrast media is added, allowing the distal anchoring balloon 104 to engage and press against the walls of the LVOT 130, thus longitudinally securing the position of the enhanced aortic valvuloplasty catheter 100. Once the distal anchoring balloon 104 is anchored securely within the LVOT 130, the aortic sinus balloon 102 is inflated, as seen in

FIG. 2B

, hyper-extending the valve leaflets 126 into the rounded aortic sinuses 123. In this regard, it may be necessary to inflate the aortic sinus balloon 102 at several different diameters to achieve the desired valve leaflet 126 flexibility and therefore the desired pressure gradient reduction. To ensure these goals have been achieved, the pressure gradient is measured using the distal guidewire lumen after the balloons 102, and 104 are withdrawn proximal to the aortic valve, leaving the pigtail 108 within the LVOT distal to the valve leaflets 126. A lumen within the sheath 124 may then be connected to a pressure transducer (not shown) at the proximal end of the sheath 124. Simultaneous central aortic and left ventricle pressure can then be measured to derive the valve gradient.

Microporous Filter Basket

FIG. 4

illustrates another preferred embodiment of the present invention, in which an aortic valvuloplasty catheter 100 in accordance with the present invention includes a microporous filter basket 143. The aortic valvuloplasty catheter 100 is configured and operated in an almost identical manner as described previously. However, a microporous filter basket 143 is included proximal to the aortic sinus balloon 102 to catch any debris resulting from the valvuloplasty procedure and thereby prevent embolic complications in the patient. For example, aortic root or valve leaflet debris or thrombus may dislodge with the inflation of aortic sinus balloon 102. If these deposits or thrombus are not captured, e.g. by the microporous filter basket 143, such particles can travel to the brain, as well as other organs systems, causing stroke or other ischemic injury.

The microporous filter basket 143 is made up of multiple basket arms 142 which are pre-set in an expanded, open position. The proximal ends of the basket arms 142 are fixed to an anchor point on the enhanced aortic valvuloplasty catheter 100, while the distal ends of the basket arms 142 are self deployed against the ascending aorta 128. A microporous filter 141 is secured to the basket arms 142, creating an enclosed basket shape.

In operation, the microporous filter basket 143 remains packed within the sheath 124 while in a pre-deployed state. During this time, the basket arms 142 are pressed against the catheter body 106, while the microporous filter 141 is packed between the catheter body 106 and the sheath 124. When a user has positioned the aortic valvuloplasty catheter 100 at a desired location and wishes to deploy the microporous filter basket 143, the sheath 124 is retracted in a proximal direction, exposing the microporous filter basket 143 and allowing the pre-set basket arms 142 to expand and engage the aortic wall 128. Thus, if debris breaks loose during the valvuloplasty procedure, the filter basket 143 prevents this debris from traveling downstream into the vascular system. When the user removes the aortic valvuloplasty catheter 100, the sheath 124 is moved in a distal direction toward the filter basket 143 or the catheter 100 is retracted into the sheath 124, causing the filter basket 143 to compress in diameter and slide within the sheath 124.

The material constituting the filter basket may be comprised of the nanoskin material as disclosed in co-pending application Ser. No. 10/314,086, filed Dec. 6, 2002, entitled Covering And Method Using Electrospinning Of Very Small Fibers, the contents of which are incorporated by reference.

Single Balloon Valvuloplasty Catheter

Referring now to

FIGS. 5A-5B

, a single balloon valvuloplasty catheter 200 is illustrated, having a single catheter balloon 202 instead of two distinct balloons as in previously described embodiments.

Generally speaking, the single balloon valvuloplasty catheter 200 is configured with a similar structure to previously described embodiments. The single balloon valvuloplasty catheter 200 has a multi-lumen catheter body 204 with radiopaque markers 203 located at reference points on the distal portion of catheter body 204. A guidewire is positioned through a lumen within the catheter body 204 and extends out the distal end of the catheter body 204, which terminates in a pigtail shape 206. The catheter body 204 has a media port 201, positioned in the mid section of the catheter balloon 202, so as to allow communication with the media lumen in the catheter body 204.

The catheter balloon 202 preferably allows for progressive inflation, so that the distal anchoring section 202b of the catheter balloon 202 inflates before the proximal aortic portion 202a. This progressive inflation may be accomplished with catheter balloon sections having differing compliancy. For example, the distal anchoring portion 202b may have a relatively high compliance (e.g. about 24 ATM), while the proximal aortic portion 202a may have a relatively low compliance (e.g. about 4-8 ATM). Thus, as inflation media enters the catheter balloon 202, the more compliant section (i.e. the distal anchoring portion 202b) expands first. When the more compliant section fully expands, the pressure within the catheter balloon begins to increase further, allowing the less compliant section to begin expanding (i.e. the proximal aortic portion 202a). The balloon diameter of the proximal portion of the LVOT segment 202b, adjacent to the valve annulus 125, is restricted from growing substantially beyond the diameter of the annulus 125 by strategically positioning circumferential fiber reinforcement. In this manner, a user can precisely control the expansion sequence and maximal achieved diameter for each of the catheter balloon sections 202a, 202b.

When expanded, the proximal catheter balloon section 202a substantially conforms to the rounded contour of the aortic sinus root 123. By conforming closely to the aortic sinus root 123, the proximal catheter balloon section 202a may open the leaflets 126 by hyperextending them open as broadly as possible, reducing the possibility of tearing the valve annulus 125.

The compliance of each of the catheter balloon sections 202a, 202b can be obtained by utilizing fabric reinforcements at areas requiring additional strength. Preferably, fiber based membranes, as previously described in this application and in pending application Ser. No. 09/974,220 entitled Material Usable for Medical Balloons and Catheters (incorporated by reference), can be used to control the varying compliancy of the catheter balloon 202.

For example, referring to

FIGS. 5D-5F

, the balloon 202 in one embodiment may be designed such that the LVOT segment 202b of the balloon 202 is not fiber-reinforced and thus displays compliant characteristics as pressure is introduced into the balloon 202 while the proximal aortic portion 202a is fiber-reinforced (e.g., with yarns) and thus displays non-compliant characteristics. More specifically, in this one embodiment, the LVOT segment 202b is unreinforced and expands compliantly during an introduction of pressure P1 while the proximal aortic portion 202a includes a yarn reinforced sleeve configuration that forecloses expansion of the proximal aortic portion 202a until pressure within the balloon 202 reaches a predetermined pressure P2. Moreover, the fibers are configured so as to mechanically limit the enlargement of the proximal aortic portion to a predetermined size and shape, namely a size shape that conforms the proximal aortic portion 202a to the aortic root sinuses. Hence, in operation, when pressure P1 is introduced into the balloon 202, the LVOT segment 202b expands into the LVOT in a compliant manner and thus anchors the catheter in the LVOT. Then, when pressure P2 is reached, the proximal aortic segment 202a expands in a manner to perform the valvuloplasty, the yarn of the sleeve mechanically limiting the expansion (and thereby protecting the valve) to a predetermined shape and size.

In this regard, a taper zone 602 is designed into the balloon 200 configuration discussed above between the proximal aortic portion 202a and the LVOT segment 202b. This taper zone 602 has a narrower diameter than each of its adjacent sections and controls the medial â€œhipâ€ shape of the balloon that is used to seat the balloon within the annulus of the valve and prevent excessive loads from being exerted by the balloon on the annulus during inflation.

Further in this regard, the fiber reinforcement in this embodiment could include polymeric yarns that are either fully oriented or partially oriented. Fully oriented yarns have characteristics that provide a high pressure mechanical â€œstopâ€ and thus are particularly suited to creating balloon shape. Partially oriented yarns (POY) are slightly more compliant in the initial expansion stages and thus introduce a slight â€œstretchâ€ characteristic into the expansion of the proximal aortic portion 202a. However, as the POY fibers become drawn, they become stronger. Therefore, the POY fibers can be configured on the proximal aortic portion 202a such that the POY fibers reach this â€œstrongerâ€ state at the same time the proximal aortic portion 202a reaches its desired size and shape and thereby mechanically limit further expansion of the proximal aortic portion 202a.

In the embodiment using the fully oriented yarns, it is preferable to use a knit structure since the knit structure could inherently introduce a degree of â€œstretchinessâ€ into the sleeve that the fully oriented yarns may not otherwise provide. In the embodiment using the POY fibers, it is preferable to use a braid or weave of about 100-200 denier polyester yarns at 20-5-picks per inch for the braid embodiment and 40-6-picks per inch for the weave embodiment.

Referring to

FIGS. 5G-51

, in a second embodiment, the LVOT segment 202b of the balloon 202 is fiber-reinforced such that it is either non-compliant or only partially compliant while the proximal aortic portion 202a is fiber-reinforced such that it exhibits compliant characteristics but only after a threshold pressure is reached. For example, the LVOT segment 202b may be comprised of a non-compliant or partially compliant PET or nylon plastic material while the proximal aortic portion 202a may be comprised of elastic filaments (e.g., spandex) that are compliant only after a threshold pressure. As a result, when pressure P1 is introduced into the balloon 202, the LVOT segment will resist expansion or only slightly expand until a pressure P1 is achieved, at which point the LVOT segment 202 will expand to a shape constrained by its PET or nylon plastic construction and which conforms to the LVOT. Then, when pressure increases to P2, the LVOT segment 202b will remain in its expanded state while proximal aortic portion 202a begins to expand in a compliant way as governed by the compliant properties of the elastic filaments. In other words, the elastic filaments hold or restrain the expansion of the proximal aortic portion 202a until the LVOT segment 202b expands and P2 is reached. Then the elastic filaments become loaded and start to stretch and expand in a compliant manner thereafter.

The elastic filaments in this second embodiment also create a textured surface that facilitates stability of the balloon 200 during the valvuloplasty. Furthermore the elastic filaments greatly assist in compressing the proximal aortic portion 202a to its initial uninflated sized so as to also greatly assist removal of the catheter after the valvuloplasty is complete.

In this second embodiment, the elastic filaments could comprise a braid of about 200 denier polyurethane filaments. In this regard, a braided fabric of elastic filaments would facilitate a greater range of expansion capabilities for the proximal aortic portion 202a. On the other hand, a woven fabric of elastic filaments would facilitate a more stable length expansion of the proximal aortic portion 202a. Furthermore, it should be recognized that the arrangement and makeup of the elastic filaments used in the proximal aortic portion 202a, e.g., filament size, fabric density, yarn tension, can be used to control the overall size and shape and inflation progression of the LVOT section 202b as well as the P2 activation pressure.

Referring to

FIGS. 5J-5L

, in a third embodiment, the balloon 200 may be a composite of a balloon membrane and a fabric with the fabric covering essentially the entire balloon membrane. The makeup of the fabric would control and govern the shape ultimately achieved by the balloon membrane and the makeup of the balloon membrane would control and govern the expansion system of the fabric. More specifically, the fabric would include fibers that limit the expansion of the balloon to certain predetermined shapes and sizes and the balloon membrane would include either different thicknesses or different material elasticity along its length so that the LVOT portion 202a expands prior to expansion of the proximal aortic properties 202b.

In this regard, in a preferred embodiment the fabric could be comprised of a 200-300 denier PET yarn that could be woven, knitted or braided and wherein the fibers are configured to control the expansion shape of the fabric. In a weave embodiment, the fabric is woven to match the expanded shapes as depicted in the Figures. In a braid embodiment, the fabric would be made by changing the braid angles over a shaped mandrel.

Also in this embodiment, the balloon membrane could be comprised of one material (e.g., silicone, polyurethane or some other highly elastic polymer) wherein the wall thickness at its LVOT portion is around 0.015 to 0.02 inches and the wall thickness in the proximal aortic portion is about 0.025 to 0.03 inches. Or in the alternative, the balloon membrane could be comprised of one material such as silicone but configure the silicone such that it has a durometer of around 10-15 A at the LVOT portion and a durometer of around 15-25 A at the proximal aortic portion. In some applications, it is conceivable that a durometer as high as 60 A could be used. Although a material with a durometer of this magnitude may be thick, it is conceivable that it could be used in a very thin cross section. In any event, a balloon membrane configured using this concept can control the preferential expansion of the LVOT section before the proximal aortic portion. In one embodiment, there may be no fabric at all and the expansion and shape characteristics of the balloon 200 are controlled by using different balloon materials, different balloon material hardnesses, and/or wall thicknesses to govern the expansion of the balloon.

With regard to the third embodiment of this section, a dual yarn system fabric could be used to create a compliant balloon system. â€œWrappedâ€ yarns typically comprise a polyurethane filament, such as spandex, with a high wrap per inch of polyester wrapped around it. As the polyurethane filament is stretched, the polyester yarns begin to unwraps or untwists from around the polyurethane until the polyester yarn is in tension. When this happens, the polyester yarn becomes a limitation on further stretching of the polyurethane. A woven, braided, or knitted wrapped yarn system using this approach would create a highly stretchy fabric with stretch limiting elements, namely, the polyester yarns. Changing the yarn density, or size of the yarns in the fabric will govern the activation pressures P1 and P2. Higher density fabric would require a higher activation pressure.

With regard to the fiber reinforcement constructions discussed above and elsewhere in the specification, it is likely that braids and weaves would be used although knits are possible as well. Braids and waves typically lead to more stable fabrics than knits an thus are better able to resist tension until a target pressure, e.g., P2, is reached, after which they will stretch and allow expansion.

With further regard to the fiber reinforcement constructions discussed above (and with regard to other embodiments of the present invention discussed elsewhere), it is noted that the fiber reinforcement approach allows the sealed portion of the device (the part that receives and contains the pressure for the purpose of expansion) can be very thin walled compared to prior art balloons and still tolerate high pressures. With the above described embodiments (and others not specifically identified), the wall of the sealed chamber can be as thin as 0.002 inches thick and can work in a pressure range of 2-20 atm.

It is also noted that the above embodiments (as well as other embodiments discussed in this application) could be configured such that the balloon 200 is actually comprised of two separate balloons instead of one balloon with two sections. In a two balloon embodiment, the same fiber reinforcement aspects discussed above could be used to achieve the expansion, shape and size characteristics that optimize the valvuloplasty being performed.

The distal anchoring section 202b of catheter balloon 202 is shaped similarly to the distal anchoring balloon 104 in

FIG. 1

. In this respect, the distal anchoring section 202b is located near the distal end of catheter body 204 and has a taper that increases in the axial, distal direction to closely conform to the LVOT 130. Note also that modification for the LVOT balloon 104 can be used for this distal LVOT segment 202b. The proximal aortic section 202a is also shaped similarly to the aortic sinus balloon 102 in

FIG. 1

, preferably conforming to the shape of the rounded aortic sinuses 123 when in an inflated state.

A long sheath 124 may be utilized for longitudinal stabilization of the catheter balloon 202 during inflation by abutting and pressing against the catheter balloon 202 in a distal direction. Since the inflated catheter balloon 202 tends to act as a sail, catching the antegrade flow of pulsatile blood flow from the heart, the sheath 124 can provide additional axial stability, reducing the tendency of the catheter balloon 202 to migrate.

In operation the single balloon catheter 200 is introduced through the femoral or brachial artery using a Seldinger technique with a vascular sheath introducer and a guidewire. After placement of the guidewire across the aortic valve, the single balloon catheter 200 is advanced retrograde over the guidewire such that the pigtail 206 is positioned in the left ventricle. Next, the distal anchoring section 202b is positioned, using fluoroscopy in combination with radiopaque markers 203, within the LVOT 130, just underneath the valve annulus 125. The distal anchoring section 202b is inflated with liquid contrast media which is communicated through an inflation port within the catheter balloon 202, best seen in

FIG. 5A

. The distal anchoring section 202b expands in diameter as inflation media is added, allowing it to press against the walls of the LVOT 130, thus longitudinally securing the position of the single balloon catheter 200. Once the distal anchoring balloon 202b is anchored securely within the LVOT 130, the proximal aortic section 202a is inflated by further increasing pressure within balloon 202, as seen in

FIGS. 5B and 5C

. It may be necessary to inflate the proximal aortic section 202a several times and at several graded diameters to achieve improved valve leaflet 126 flexibility and the desired pressure gradient reduction.

Alternatively, the single balloon catheter 200 may use a rapid exchange structure (not shown) having a guide wire which is generally located outside the catheter body 204. A portion of the guide wire passes through a short distal lumen (e.g. about 40 to 50 mm in length) located within the catheter body 204, distal to the catheter balloon 202. Thus, during a valvuloplasty procedure, the guide wire lies predominantly along side the catheter balloon 202 and catheter body 204 within the vessel except at the distal end of the single balloon catheter. This rapid exchange wire compressed between the balloon and vascular structures provides additional traction and stability to the catheter balloon 202 during expansion. Additionally, the catheter body 204 may have a lower profile since a guide wire lumen throughout the catheter body 204 is not needed.

FIGS. 11A and 11B

illustrate yet another variation on the above described preferred embodiments, having two longitudinal and parallel catheter balloons 332 and 339. The overall inflated shape of the dual longitudinal balloon catheter 330 is similar to previously described embodiments, having a distal anchoring portion with an increasing taper in the distal direction for LVOT fixation and a rounded proximal portion for aortic valve dilation. Media ports 336 and 338 supply the inflation media to each catheter balloon 332, 339, while radiopaque markers 334 are used as references when positioning the dual balloon catheter 330. The dual catheter balloons 332, 339 may be inflated in a sequential manner. Sequential balloon inflation allows some antegrade blood flow with inflation of catheter balloon 332 and therefore less distal migration during the initial phase of inflation. Also, the inflated bi-lobed configuration can achieve more radial stretching of the leaflets in its greatest diameter. Also blood flow would be permitted in the recesses of both lobes of catheter balloons 332, 339 when inflated. Multiple sequential inflations can be carried out using radiopaque markers 334 to achieve different radial orientations to further improve valve leaflet flexibility and pressure gradient reduction.

As with the previous embodiment, the dual catheter balloons 332, 339 have differing compliance along their length, creating the overall inflated shape seen in

FIG. 11A

. As described above, the differing compliance is preferably achieved with fiber based membranes.

Referring now to

FIGS. 12A-12C

, a single umbrella balloon catheter 340 is shown, having a modified catheter balloon 342 shape. Single umbrella balloon catheter 340 is similar to the above described single balloon catheter 200 embodiment, except for the overall shape of catheter balloon 342.

As with the previously described embodiment, the differing shape of catheter balloon 342 is preferably controlled with fiber based membranes which allow for varying compliance of different portions of the catheter balloon. In the present preferred embodiment, the distal anchoring section 342b utilizes the fiber based membranes to create a curved â€œupside-down umbrellaâ€ shape, preferably about 6 mm in length with a distal to proximal taper ranging between about 14 mm to about 22-24 mm in diameter. The proximal aortic section 342a of balloon 342 is responsible for valve dilation and has an increasing taper in the distal direction of the catheter 340. The maximum inflated diameter is preferably about 24 mm to 30 mm toward the midsection. The LVOT section requires less media to fill, thus it will fill faster, allowing the arms of the distal anchoring section 342b to lock underneath the annulus 125 in the recess between the annulus 125 and the boundary of the adjacent LVOT.

FIGS. 13A and 13B

illustrate broad wing catheter 350, similar to the previous embodiment except for a broader, wing-shape of the distal anchoring section 352a. This broader wing shape of the distal anchoring section 352a reduces the likely hood of migration in the antegrade direction while the proximal aortic section 352b is being inflated. In addition, there remains a potential space 127 between the distal anchoring section 352a and the inflated proximal aortic section 352b which further reduces antegrade migration when segment 352b is inflated.

Balloon Catheter With Perfusion Channel

Turning to

FIG. 8

, yet another preferred balloon catheter 300 embodiment is shown, having a center perfusion channel 302a and possibly a one-way perfusion valve 304 at the proximal end of the center perfusion channel.

As with previously described embodiments, the catheter balloon 302 has a single chamber (or alternatively may have multiple balloon chambers), with a tapered distal region for engaging the LVOT and a rounded proximal region for expanding against valve leaflets 126 (not shown in

FIG. 8

). The catheter balloon 302 has varying compliance, as described with previous embodiments, to allow the distal region to expand first against the walls of the LVOT, locking the balloon catheter 300 in place. This is followed by expansion of the less compliant proximal region which conforms to the aortic sinuses 125 (not shown in

FIG. 8

), pressing against the valve leaflets 126.

The catheter balloon 302 is fixed to a multi-lumen catheter body in an off-center manner, as seen best in

FIG. 8

. With inflation of the catheter balloon 302 and expansion within the aortic root and LVOT, longitudinal movement is reduced by allowing perfusion through the central channel 302a.

The center channel 302a of catheter balloon 302 allows blood to perfuse distally through the catheter 300, thus increasing the amount of time the catheter balloon can be inflated without causing significant blood flow compromise. In addition, the central perfusion lumen improves longitudinal stability of the catheter balloon 302 position by allowing for a low resistance pathway for antegrade blood flow. To prevent back-flow of blood, a one-way valve 304 may be located at the proximal end of the perfusion channel 302a.

Alternatively, the one-way valve 304 can be located within the center of perfusion channel 302a, the distal end, or anywhere in between. Further, a one-way valve 304 may not be used in such an embodiment, as seen in the perfusion catheter 310 of

FIG. 9

. This perfusion catheter 310 similarly has a single channel 312a within the catheter balloon 312.

In yet a further alternative, the catheter balloon perfusion catheter 310 of

FIG. 9

could be modified such that the catheter balloon 312 no longer has a LVOT distal portion or it has a truncated LVOT distal portion as shown in

FIGS. 9A and 9B

. In this embodiment, the balloon of the perfusion catheter 310 takes on more of a â€œdonutâ€ appearance.

As seen in

FIG. 22

, a balloon perfusion catheter 510 may include an off axis perfusion channel 514, having an opened side 514a extending along the periphery of the anchoring section 512b and another opening at the proximal aortic section 512a. The perfusion channel 514 is positioned peripherally at the distal end of catheter balloon 510b, but is located centrally in the proximal aortic section 512b. Such an off axis perfusion channel 514 readily allows antegrade blood flow during both phases of balloon inflation, as indicated by the arrows seen in

FIG. 22

Referring now to

FIGS. 10A and 10B

, a similar single balloon catheter 320 is illustrated, having two or more side perfusion channels 322a along the periphery of the catheter balloon 322, instead of a single center channel. As with the previously described single chamber balloon catheters, this balloon catheter 320 is variably compliant to allow for initial expansion of the distal portion of balloon 322 to anchor within the LVOT. Further, the variable compliance assists in the creation of the perfusion channels 322a when the catheter balloon 302 is inflated. The perfusion channels 322a are less compliant than the other regions of the catheter balloon 322, which prevents the perfusion channels 322a from expanding outward in the same manner as the other regions of catheter balloon 322.

Additionally, the catheter balloon 322 may include internal supports (not shown) that maintain the inwardly angled shape of the perfusion channels 322a. For example, additional material within the catheter balloon 322 may secure portions of the perfusion channels 322a to the catheter body, preventing the perfusion channels 322a from expanding outward. Radiopaque markers 324 may be positioned on the outer radius of the catheter balloon 322 for reference markers, assisting a user with catheter positioning during a procedure, permitting, for example, multiple balloon inflations through a series of about 45 to 90 degree rotations. This would reduce the likelihood of creating gaps where portions of valve leaflets could migrate and therefore not be rendered more flexible.

As seen in

FIG. 10

b, the perfusion channels may include a membrane 321, covering the length of the perfusion channels 322a, yet leaving both distal and proximal perfusion channel 322a ends open. Thus, the perfusion channels 322a and membranes 321 form tube-like structures, providing greater structural support to the perfusion channels 322a yet still allowing perfusion. Membrane 321 additionally prevents gaps where the inflated balloon would otherwise not come in contact with the valve leaflets 126. Note the rounded and non-eccentric configuration of the catheter tip 323 which can be placed on balloon valvuloplasty catheters that need to be rotated through out a 360 degree arc during multiple inflation. This decreases the likelihood of resistence to rotation created by the previously noted pigtail configurations.

FIGS. 21A-21D

illustrate an enhanced catheter 500 design similar to that shown in

FIGS. 10A and 10B

. However, the enhanced catheter 500 includes a single catheter balloon 502 having perfusion channels 502c along the margins of the distal anchoring section 502b only and specifically do not extend across the aortic segment 502a. As with previous embodiments, the distal anchoring section 502b inflates first, expanding against the LVOT. The perfusion channels 502c are inwardly curved longitudinal conduits which allow blood to flow around the anchoring section 502b during a procedure. The perfusion channels 502c may be enclosed by a membrane 501, as seen in

FIG. 21B