WO2002072170A2

WO2002072170A2 - Balloon catheter and method of use

Info

Publication number: WO2002072170A2
Application number: PCT/US2002/007070
Authority: WO
Inventors: Robert C. Gallagher
Original assignee: Gallagher Robert C
Priority date: 2001-03-08
Filing date: 2002-03-07
Publication date: 2002-09-19
Also published as: WO2002072170A3; AU2002336270A1

Abstract

A retrograde venous cardioplegia balloon catheter (20) has a flexible cannula (22) on which is mounted an inflatable, tapered balloon (34) which divides the flexible cannula (22) into a proximal portion (22a) which is stiffer than a distal portion (22b). Balloon (34) may be inserted into a body opening, such as the ostium (46) of a human heart (52) to position soft, flexible distal portion (22b) within the coronary sinus (44). Balloon (34) is inflated to seal the ostium (46) and force may be applied by means of the stiff proximal portion (22a) to maintain the turgid balloon (34) in place to seal the ostium and leave substantially the entire coronary sinus (44) open to infusion by cardioplegia solution. A method of using the balloon catheter (20) includes positioning inflatable balloon (34) within the ostium (46) and imposing a force (e.g., by collapsing the right atrial wall) via distal portion (22b) on balloon (34) in its turgid condition, to maintain it in place within ostium (46).

Description

BALLOON CATHETER AND METHOD OF USE

BACKGROUND OF THE INVENTION

Field of the Invention

[0001] The present invention generally concerns balloon catheters and a method of use thereof. In particular, the present invention concerns balloon catheters and a method of using the same for administering a treatment fluid from an external source into a bodily passageway, for example, a balloon catheter of the type used for retrograde infusion of cardioplegic fluid into a patient's heart.

Related Art

[0002] U.S. Patent 5,021,045, issued June 4, 1991 to G.D. Buckberg et al and entitled "Retrograde Venous Cardioplegia Catheters And Methods Of Use And Manufacture", discloses a catheter containing two lumens. One lumen is an infusion lumen through which the cardioplegic solution flows, and the second lumen is a pressure-sensing lumen for monitoring the fluid pressure at the point where the solution exits the catheter. See the description at column 7, lines 19-55, wherein the flexibility of the cannula 12 and the provision of the dual lumens is described. As illustrated in Figures 1 and 2 of this patent, the catheter 10 (Figure 1) contains an infusion lumen 18 and pressure-sensing lumen 20, both of which are occluded by a soft, rounded tip 14, and a self-filling balloon 22 which has a taper in the range of from about 25 to about 35 degrees (see column 8, lines 44-53). Figure 4 illustrates the inflated balloon 22 positioned "just within coronary sinus orifice 54 of right atrial wall 56..." of a human heart. (See column 12, lines 39-42.) The flow of cardioplegic solution is through a plurality of small infusion lumen outlets 28. See column 12, lines 39-46 of this patent, concerning inflation of the balloon 22, and column 9, line 61 et seq, concerning infusion of the cardioplegic solution. [0003] U.S. Patent 5,226,427, issued My 13, 1993 to G.D. Buckberg et al, is entitled "Removable Stylet For Retrograde Cardioplegia Catheter And Methods For Use". This patent issued on a continuation-in-part of the application which resulted in U.S. Patent 5,021,045 and is concerned with the stylet used in connection with the balloon catheter disclosed in U.S. Patent 5,021,045.

[0004] U.S. Patent 5,423,745, issued June 13, 1995 to R.J. Todd et al, is entitled "Irregular Surface Balloon Catheters For Body Passageways and Methods of Use". This patent discloses a balloon catheter having an exterior surface from which a plurality of protuberances project. For example, see Figures 3, 5 and 6-9. As described at column 4, lines 13-26, the protrusions or knobs on the outer surface of the balloon serve to more securely grip the walls of a body passageway and form a seal within the body passageway when the balloon is inflated. [0005] The publication Advances In Cardiac Surgery, Volume 10 (1998), Mosby, Inc., 11830 Westline Industrial Drive, St. Louis, MO 63146, contains at pages 119-125 a section entitled "Retrograde Cardioplegia Distribution" by Richard N. Gates and Hillel Laks. This article describes certain findings to the effect that, with the use of retrograde cardioplegia, relatively less cardioplegia solution is obtained in the right ventricle as compared to that obtained in the left ventricle. In the last paragraph on page 123, the article attributes the reduced right ven- tricular distribution of the cardioplegia solution to the anatomy of the heart and the fact that the balloon of the catheter lies well past the connection point of the posterior descending coronary ("PDC") vein in the body of the coronary sinus. As a result, cardioplegia solution must travel through venovenous connections from more distal veins into the PDC vein, rather than directly from the coronary sinus into the PDC vein. Further, a good deal of the delivered cardioplegia flow is siphoned off by drainage of the PDC vein into the right atrium, which is at reduced pressure. The result is that right ventricular profusion of cardioplegia fluid was found to be about one-fourth of left ventricular profusion. This poor infusion of the right side of the heart increases the risk of fibrillation of the right side of the heart during surgery, and of failure to restart the heart thereafter.

SUMMARY OF THE INVENTION [0006] Generally, the present invention provides a balloon catheter which is capable of being retained in sealing engagement with an entry, e.g., the ostium, to a body passageway, e.g., the coronary sinus, by an applied force, and which lodges in the entry to prevent further, and excessive, travel into the body passageway, and a method of use of the catheter. The method includes applying retaining force to the balloon catheter while infusing the patient with a treatment fluid supplied by the catheter. In general terms, the balloon catheter of the invention has a relatively soft distal portion and a relatively rigid proximal portion with an inflatable balloon therebetween. The inflatable balloon, in its turgid condition, is dimensioned and configured to seal an entry into a body passageway, e.g., the ostium, and to be retained in place within the opening by a force transmitted along the proximal portion of the catheter. [0007] More specifically, in accordance with the present invention, there is provided an improvement in a retrograde venous cardioplegia balloon catheter for administering cardioplegic fluid from an external source into a patient's heart through the coronary sinus via the ostium, the catheter comprising the following components. A flexible cannula has a distal portion separated from a proximal portion thereof by an inflatable balloon. The distal portion of the cannula is dimensioned and configured to be inserted through the patient's ostium into the coronary sinus and at least one distribution aperture is formed therein for introducing cardioplegic fluid conducted through the cannula into the patient's coronary sinus. The inflatable balloon has a longitudinally tapered configuration which provides an apex end adjoining the distal portion of the cannula and a base end adjoining the proximal portion of the cannula, the base end having a diameter which is greater than the diameter of the apex end. At least one inflation aperture is disposed within the balloon for introducing an inflating fluid into the balloon to inflate the bal- loon into a turgid condition. The improvement comprises that the balloon is dimensioned and configured so. that, when inflated into a turgid condition, the diameter of the base end is sufficiently greater than the diameter of the ostium whereby travel of the catheter into the coronary sinus is arrested as the turgid balloon lodges in and seals the ostium, thereby limiting the extent of travel of the balloon into the coronary sinus. [0008] In another aspect of the present invention there is provided an improvement in a retrograde venous cardioplegia balloon catheter for administering cardioplegic fluid from an external source into a patient's heart through the coronary sinus via the ostium, the catheter comprising the following components. A flexible cannula has a distal portion separated from a proximal portion thereof by an inflatable balloon. The distal portion of the cannula is dimen- sioned and configured to be inserted through the patient's ostium into the coronary sinus, and at least one distribution aperture is formed therein for introducing cardioplegic fluid conducted through the cannula into the patient's coronary sinus. The inflatable balloon has at least one inflation aperture within it for introducing an inflating fluid into the balloon to inflate the balloon into a turgid condition, the resulting turgid balloon being dimensioned and configured to seal the ostium. The improvement comprises that the proximal portion of the flexible cannula is sufficiently rigid to transmit force applied thereto to the balloon whereby to hold the turgid balloon in place to seal the ostium against fluid flow therethrough.

[0009] One aspect of the present invention provides that the features of the two above- described catheters may be contained in a single device. [0010] In one aspect of the invention, the flexible cannula comprises a supply lumen dimensioned and configured to be connected to a source of cardioplegic fluid and an auxiliary lumen dimensioned and configured to be connected to a source of inflating fluid, and wherein the at least one distribution aperture is formed in the supply lumen, and the at least one inflation aperture is formed in the auxiliary lumen and is in fluid flow communication with the interior of the balloon.

[0011] Other aspects of the invention provide the following features, alone or in combination of any two or more thereof: the distal portion of the flexible cannula may be sufficiently flexible to preclude penetration of heart tissue by the distal portion; the proximal portion of the catheter may have a higher flexural modulus than the distal portion of the catheter; the proximal portion of the catheter may carry thereon a stiffening structure to enhance its flexural modulus; the inflatable balloon may have a smooth outer surface; and when the inflatable balloon is in its turgid condition, the base end of the balloon may have a diameter of from about 10 to 20 milli- meters, the apex end of the balloon has a diameter less than that of the base end and from about 6 to 10 millimeters, and the length of the balloon measured longitudinally between the base end and the apex end may be from about 20 to 25 millimeters.

[0012] A method aspect of the present invention provides a method for infusion of a cardioplegic fluid from an external source into a patient's heart through the coronary sinus via the ostium. The method utilizes a retrograde venous cardioplegia balloon catheter having the following components. A flexible cannula comprised of a distal portion and a proximal portion separated from the distal portion by an inflatable balloon; the inflatable balloon being inflatable into a turgid condition, and having a longitudinally tapered configuration providing an apex end adjoining the distal portion of the cannula and a base end adjoining the proximal portion of the cannula, the base end having a diameter which is greater than the diameter of the apex end and greater than the diameter of the ostium when the balloon is in its turgid condition. The distal portion has at least one distribution aperture therein for dispensing the cardioplegic solution and is sufficiently flexible to preclude penetration of heart tissue by the distal portion. The method comprises the steps of inserting the distal portion of the flexible cannula into the patient's coro- nary sinus to position the inflatable balloon within the ostium, inflating the inflatable balloon to its turgid condition and advancing the catheter into the coronary sinus until travel of the catheter into the coronary sinus is arrested by lodgment of the turgid balloon in the ostium, and flowing the cardioplegic fluid through the cannula and the distribution aperture into the patient's heart through the coronary sinus. [0013] Another method aspect of the present invention provides a method for infusion of a cardioplegic fluid from an external source into a patient's heart through the coronary sinus via the ostium. The method utilizes a retrograde venous cardioplegia balloon catheter having the following components. A flexible cannula comprised of a distal portion and a proximal portion separated from the distal portion by an inflatable balloon which is inflatable into a turgid con- dition, the distal portion having at least one distribution aperture therein for dispensing the cardioplegic solution, and the balloon having an inflation aperture disposed within it. The proximal portion of the flexible cannula is sufficiently rigid to transmit force applied thereto to the balloon in its turgid condition, and the distal portion of the cannula is less rigid than the proxi- mal portion and sufficiently flexible to preclude penetration of heart tissue by the distal portion. The method comprises the steps of inserting the distal portion of the flexible cannula into the patient's coronary sinus to position the inflatable balloon within the ostium, inflating the inflatable balloon to its turgid condition in which the inflatable balloon is dimensioned and configured to seal the ostium against fluid flow therethrough, imposing a force on the proximal por- tion of the flexible cannula to maintain the turgid inflatable balloon in sealing position within the ostium, and flowing the cardioplegic fluid through the cannula and the distribution aperture into the patient's heart through the coronary sinus.

[0014] A method aspect of the present invention provides that the two above-identified method steps may be both be utilized in the same procedure. [0015] Other method aspects of the present invention provide the following features, alone or in combination of two or more thereof: the flexible cannula may be inserted into the patient's heart by making an incision in the right atrial wall of the heart and passing the flexible cannula through the resulting incision and through the right atrial chamber; the step of imposing a force on the proximal portion of the flexible cannula may be carried out by securing the flexible can- nula to the right atrial wall and collapsing the right atrial wall towards the ostium; the step of collapsing the right atrial wall towards the ostium may be carried out by draining the patient's blood from the right atrial chamber; the flexible cannula may comprise a supply lumen dimensioned and configured to be connected to a source of the cardioplegic fluid and an auxiliary lumen dimensioned and configured to be connected to a source of inflating fluid, and the distri- bution aperture may be formed in the supply lumen, and the inflation aperture formed in the auxiliary lumen and in fluid flow communication with the interior of the balloon, and the method further comprises flowing the inflating fluid through the auxiliary lumen and via the inflation aperture into the inflatable balloon to inflate the balloon to its turgid condition, and flowing the cardioplegic fluid through the supply lumen and out the distribution aperture. [0016] Other aspects of the present invention will be apparent from the following description and the appended drawings. BRIEF DESCRIPTION OF THE DRAWINGS [0017] Figure 1 is a perspective view of a balloon catheter in accordance with one embodiment of the present invention and a known stylet which is insertable into the catheter for use in inserting the catheter into a patient's body; [0018] Figure 1 A is an enlarged perspective view of that portion of the catheter of Figure 1 within the area A, with a cover portion thereof omitted for improved clarity of illustration; [0019] Figure IB is a view, with parts broken away, of that portion of the catheter of Figure 1 within the area B; [0020] Figure 1 C is a side elevation view of a portion of the catheter of Figure 1 ; [0021] Figure 2 is a view corresponding to that of Figure 1C, but partially in cross section, and showing an alternate embodiment of the present invention;

[0022] Figure 3 A is a perspective schematic view showing a portion of the catheter of Figure 1 in an early stage of insertion into a patient's heart; [0023] Figure 3B is a view corresponding to that of Figure 3 A showing the catheter fully inserted into the patient's heart;

[0024] Figure 4A is a perspective rendition of a human heart, partially broken away, showing a balloon catheter of the prior art fully inserted therein;

[0025] Figure 4A-1 is a perspective view, enlarged relative to Figure 4A, of the balloon and distal portion of the catheter of Figure 4A; and [0026] Figure 4B is a view corresponding to Figure 4A, but showing the catheter of Figure 1 fully inserted into the patient's heart.

DETAILED DESCRIPTION OF THE INVENTION AND PREFERRED EMBODIMENTS THEREOF [0027] Referring to Figure 1, there is shown a known cardioplegia stylet 10 and a balloon catheter 20, the latter comprising an embodiment of the present invention. Stylet 10, which is not part of the present invention, is comprised of a curved rod 12 extending from a handle 14, the latter comprising a thumb rest 16 and a finger rest 18 in the form of a wire loop extending from handle 14. The construction of stylet 10 is known in the art, for example, it is shown in the aforementioned U.S. Patent 5,226,427 and in U.S. Design Patent 335,705, issued May 18, 1993 and entitled "Retrograde Cardioplegia Stylet."

[0028] As is known in the art, stylet 10 is employed to insert into a patient's heart during or in preparation for heart surgery any suitable retrograde cardioplegia balloon catheter and it, or any other suitable stylet, may be used in conjunction with the balloon catheter of the present invention. Balloon catheter 20 comprises a flexible cannula 22 comprised of an auxiliary lumen 26 and a supply lumen 28 (Figure 1) which, as best seen in Figure 1 A, are joined in a Y connection to form flexible cannula 22 which terminates in a distal tip 22c thereof. A balloon 34 is mounted on flexible cannula 22 which is divided by an interior wall 32 (Figure 1 A) which serves to separate cannula 22 into an auxiliary lumen channel 26a and a supply lumen channel 28a. A sealing sleeve 30 (Figure 1) is tightly fitted about the Y connection to seal it from the environment. (Sealing sleeve 30 is omitted in Figure 1A for clarity of illustration.) The proximal end 26' of auxiliary lumen 26 is fitted with a two-way valve 27 equipped with an indicator- handle 29 which may be rotated to selectively open one, and thereby close the other, of ports 27a or 27b. Ports 27a and 27b are dimensioned and configured to be comiected, respectively, to a source of inflating fluid for balloon 34 and to monitoring equipment (not shown) to monitor intra-coronary sinus pressure. The position of indicator-handle 29 serves to indicate to the user which of the ports 27a and 27b is open. The proximal end 28' of supply lumen 28 terminates in a connector fitting 24, which is dimensioned and configured to be connected to a source of car- dioplegia fluid. A suture grommet 40 is slidably mounted on flexible cannula 22 between the Y connection covered by sealing sleeve 30 and balloon 34. The suture grommet 40 is dimensioned and configured to grip the outer surface of flexible cannula 22 so that grommet 40 is slidable thereon, but only with some difficulty. That is, while the grommet 40 can be slidably moved to a selected position along the length of flexible cannula 22, it is held in the position in which it is placed by use of a conventional "purse string" stitch to secure the grommet 40 to cannula 22, as described below in conjunction with Figure 3 A of the drawings. In this way suture grommet 40 is fixed relative to flexible cannula 22 even if a moderate force, such as the force imposed by movement of the atrial wall of the heart, as discussed below, is imposed upon it. As best seen in Figure 1C, suture grommet 40 is comprised of a pair of rings 40a, 40b con- nected by a cylinder 40c of lesser diameter than rings 40a, 40b, so as to define between the rings a suture groove (unnumbered).

[0029] A clamp 31 is mounted over supply lumen 28 for selectively opening and closing supply lumen 28 in the known manner. [0030] Figure IB shows balloon 34 is sealed onto the exterior of cannula 22 by balloon end gaskets 34a, 34b which provide a fluid-tight seal between the interior of balloon 34 and the exterior of that portion of cannula 22 enclosed by balloon 34. As shown in Figures IB and 1C, the portion of flexible cannula 22 adjacent balloon 34 is divided by balloon 34 into a proximal portion 22a and a distal portion 22b. Within the interior of balloon 34 a series of inflation apertures 36 connect the interior of balloon 34 in fluid flow communication with auxiliary lumen channel 26a. A series of distribution apertures 38 is formed in the distal portion 22b of cannula 22 to open supply lumen channel 28a in fluid flow communication with the exterior of cannula 22. Distribution apertures 38 are isolated from auxiliary lumen channel 26a by interior wall 32 of cannula 22. [0031] Proximal portion 22a of cannula 22 is more rigid than distal portion 22b, that is, proximal portion 22a has a higher flexural modulus than does distal portion 22b. This difference in stiffness (flexural modulus) may be attained by any suitable means, such as by making proximal portion 22a of a material which is inherently stiffer than the material from which distal portion 22b is made, or by making proximal portion 22a of larger diameter, and/or of greater wall thickness than distal portion 22b, or by providing a stiffening structure on or within proximal portion 22a, or by a combination of two or more such expedients. For example, a stiffening fiber, mesh or tube may be embedded within the wall of cannula 22 in proximal portion 22a thereof or it may be used to line all or part of the interior wall of cannula 22 in proximal portion 22a. Alternately, as illustrated in Figure 2 and described in more detail below, an external stiff- ening structure, such as a tube-like jacket, may be provided about proximal portion 22a. The flexural modulus of distal portion 22b is low enough, and distal portion 22b is soft enough, to prevent it from puncturing soft tissue, such as heart tissue.

[0032] Use of the balloon catheter 20 is illustrated in Figures 3 A and 3B, which show an exploded, schematic partial view of the structure of a human heart in that there is shown in cross section a portion of the right atrial wall 42, and in partial perspective view the coronary sinus 44, the ostium 46 of which provides an opening into coronary sinus 44, and branch veins 48 and 50. The right atrial chamber of the heart is indicated at 43.

[0033] As is well known to those skilled in the art, in order to conduct cardiac surgery, it is necessary to drain the blood from the patient's heart and divert it to a heart-lung machine and then to infuse the heart with a cardioplegia solution in order to still the heart to facilitate the surgical work and preclude localized beating or fibrillation. The balloon catheter 20 of the present invention may be utilized to conduct such infusion. In order, however, to compare placement of the balloon catheter of the present invention to that of the prior art, such placement will be described with respect both to the prior art device illustrated in Figure 4A and to the em- bodiment of the present invention illustrated in Figure 4B. Figures 4A and 4B both show, with a portion broken away, a somewhat schematic rendition of a human heart 52. In Figure 4A a prior art balloon catheter 120 is shown emplaced within heart 52 and, in Figure 4B, the balloon catheter 20 of Figure 1 is shown emplaced within heart 52. [0034] Figure 4A shows parts of prior art balloon catheter 120 as being substantially identical to parts of the balloon catheter 20 of the present invention, the differences residing in the construction of inflatable balloon 34, proximal portion 22a and distal portion 22b of balloon catheter 20. Accordingly, those components of prior art balloon catheter 120 which are sub- stantially identical to those of balloon catheter 20 comprising an embodiment of the present invention are numbered in Figure 4A identically to the corresponding components of balloon catheter 20 and function in the identical manner thereto. Therefore, the description of such common parts need not be repeated. In contrast to balloon catheter 20 of the present invention, the prior art balloon catheter 120 has an inflatable balloon 134 which is located much closer to the distal tip 122c of cannula 122 than is the case with the balloon catheter of the present invention. As a consequence, as illustrated in Figure 4A, when inflated, balloon 134 is positioned well inside coronary sinus 44, that is to say, it is not at ostium 46, but is well removed therefrom (to the right thereof as viewed in Figure 4A) within coronary sinus 44. Further, proximal portion 122a is not of greater stiffness (flexural modulus) than distal portion 122b. Insertion of prior art catheter 120 into the heart is attained in the known manner by making a small incision in the right atrial wall 42 and, with the rod 12 of stylet 10 (Figure 1) in place within the cannula 122, using stylet 10 to insert cannula 122 through the incision and to advance it through right atrial chamber 43 to insert distal portion 122b through ostium 46 and into the coronary sinus 44. At this stage, the balloon 134 is still in a flaccid condition, but once cannula 122 is positioned approximately as shown in Figure 4A, two-way valve 27 is opened to a source of suitable inflating fluid which flows through auxiliary lumen 26 into the interior of balloon 134, thereby inflating balloon 134 into the turgid condition shown in Figure 4A. With the inflated balloon 134 retaining flexible cannula 122 in place, cardioplegia solution is flowed through supply lumen 28 and dispensed through distribution apertures 138 (Figure 4A-1) into coronary sinus 44. Prior art balloon 134 is shown in Figure 4A-1 to have thereon external protrusions (unnumbered) to facilitate retention of balloon 134 within coronary sinus 44, in accordance with the teaching of the aforesaid U.S. Patent 5,423,745. It will be appreciated that because balloon 134 must be inflated into a turgid condition in order to securely retain flexible cannula 122 in place within coronary sinus 44, a substantial portion of coronary sinus 44, to the left of turgid balloon 134 as viewed in Figure 4A, is isolated from the flow of cardioplegia fluid dispensed through distribution apertures 138. Further, at least some of any cardioplegia fluid which might manage to bypass balloon 134 to flow in the direction of ostium 46, would flow through ostium 46 and out of coronary sinus 44 rather than into branch veins 48, 50. With this arrangement, it is seen why the prior art devices, such as balloon catheter 120, provide significantly less flow of car- dioplegia fluid into the right side of the heart as described in the above-noted article in Advances in Cardiac Surgery.

[0035] The utilization of, and the advantages provided by, the balloon catheter 20 representing an embodiment of the invention, are illustrated in Figure 4B, which corresponds to Fig- ure 4A except that the balloon catheter 20 of Figure 1 and not prior art catheter 120 is shown in place within heart 52. Before describing the advantageous placement of balloon catheter 20 into heart 52 as shown in Figure 4B, the method of emplacement thereof will be described with reference to Figures 1, 1C, 3 A and 3B. As shown in Figures 3 A, 3B and 1C, balloon 34 is mounted on flexible cannula 22 and divides proximal portion 22a thereof from distal portion 22b within which distribution apertures 38 are located. Balloon 34 is inflatable by any suitable means separately from and independently of the in-flow of cardioplegic solution. In this way balloon 34 can be kept in its inflated condition when the flow of cardioplegic solution is stopped. [0036] In the illustrated embodiment, balloon 34 is of tapered construction, being of gener- ally frusto-conical configuration having a base 34c having a base diameter D and a (truncated) apex 34d having an apex diameter d which is smaller than base diameter D. The longitudinal length 1 of the body of balloon 34 is measured between the base 34c and apex 34d. The dimension d of turgid balloon 34 is selected to be somewhat smaller than the smallest expected diameter of a patient's ostium 46 and the dimension D is selected to be somewhat larger than the largest expected diameter of ostium 46. Balloon 34 may be provided in two or more sizes, for example, a smaller size or sizes may be provided for pediatric surgery, and a larger size or sizes for adult cardiac surgery. The usual range of diameter of the ostium of a human heart is from about 8 to 15 mm. Accordingly, typical dimensions of base diameter D are from about 10 to 20 millimeters ("mm") and typical dimensions of apex diameter d are from about 6 to 10 mm. The length 1 of balloon 34 is typically about 20 to 25 mm. All measurements are of the balloon in its fully inflated, turgid condition. (Reference herein and in the claims to the "turgid" condition of the inflatable balloon are to its fully inflated, turgid condition.)

[0037] In use, rod 12 of stylet 10 (Figure 1) is inserted through supply lumen 28 and is utilized to insert the distal tip 22c of balloon catheter 20 through the usual small incision formed in the right atrial wall 42 (Figure 3A) with balloon 34 in its uninflated, flaccid condition. Stylet 10 and balloon catheter 20 are advanced to pass distal portion 22b of flexible cannula 22 through the incision in atrial wall 42, through the right atrial chamber 43, thence into ostium 46 of coronary sinus 44. Suture grommet 40 is then secured to flexible cannula 22 at the point where grommet 40 is disposed in abutting contact with the exterior of right atrial wall 42, -li¬

as shown in Figure 3 A. As mentioned above, a conventional "purse-string" stitch (not shown) is used to secure grommet 40 to flexible cannula 22 with a length of suture. Balloon 34 is then inflated by rotating indicator-handle 29 to open port 27a and close port 27b in order to supply an inflating fluid through auxiliary lumen 26 and auxiliary lumen channel 26a, thence through inflation apertures 36 (Figure IB) into the interior of balloon 34. In its turgid condition, balloon 34 tapers smoothly from its base 34c to its apex 34d. The inflatable balloon 34, when inflated into its turgid condition, tapers smoothly from a base which faces the proximal portion of the flexible cannula and is of larger diameter than an apex which faces the distal portion of the flexible cannula. The sidewall of the inflatable balloon 34 is preferably smooth as it does not require protrusions to provide a gripping force on the interior of the sinus cavity as do some prior art devices. When balloon 34 is fully inflated, indicator-handle 29 is rotated to close port 27a to shut off the supply of inflating fluid and to open port 27b to contact the auxiliary lumen 26 and auxiliary lumen channel 26a to a monitor which will respond to the pressure within coronary sinus 44. Any suitable arrangement which will permit inflating inflatable balloon 34 to its turgid condition and maintaining it in its turgid condition independently of the flow of treatment fluid, e.g., cardioplegic solution, is utilizable in the teaching of the present invention. [0038] Suture grommet 40 is attached to right atrial wall 42 by a conventional "noose stitch" (not shown) by securing a length of suture within the suture groove (unnumbered) provided between rings 40a, 40b of suture grommet 40. As blood is withdrawn from the patient's heart, including from right atrial chamber 43, the right atrial wall 42 collapses and moves towards the coronary sinus 44 as shown in Figure 3B. Consequently, the collapsing right atrial wall 42 imposes a force, indicated by the arrows F in Figure 3B, which urges turgid balloon 34 into sealing engagement with ostium 46 and positions distal portion 22b within coronary sinus 44. Because proximal portion 22a is of relatively rigid construction, it serves to transmit the force F to balloon 34, thereby seating balloon 34 within the opening provided by ostium 46, as shown in Figure 4B. Obviously, any external force, such as one applied by the surgeon's hand, either directly or by manually pumping blood (or other fluid) out of the right atrial chamber of the heart, may be applied to proximal portion 22a to hold turgid balloon 34 in place. [0039] The flexible cannula 22 of balloon catheter 20 may be inserted into the right atrial chamber 43 as described above either before or after the patient is placed on a heart-lung machine to bypass blood around the heart. Preferably, the flexible cannula 22 is fully inserted and balloon 34 is inflated and secured in place, as described above, before the patient is placed on the heart-lung machine. In this way, the collapse of the right atrial wall 42 as blood is drained from the heart by the heart-lung machine seats turgid balloon 34 in place within ostium 46. If the patient is placed on the heart-lung machine before insertion and securement of flexible cannula 22, the surgeon will manipulate the heart to re-inflate atrial chamber 43 with blood which is drained after placement and securement of the flexible cannula 22, in order to collapse right atrial wall 42 with the effect as described above. [0040] With ostium 46 sealed by turgid balloon 34 as shown in Figure 3B, distal portion 22b lies within coronary sinus 44, substantially the entire length of which is open to inflation apertures 36 of distal portion 22b, thereby fully infusing branch veins 48, 50 and other smaller capillary connections (not shown) to the coronary sinus 44. This provides full and substantially equal distribution of cardioplegic fluid to both the right and left sides of the heart. The gentle but persistent pressure imposed by the collapsing right atrial wall 42 maintains the turgid balloon 34 in sealing position in the ostium 46 and prevents dislodgment thereof and consequent leaking of cardioplegic fluid back out through the ostium 46. Reference herein and in the claims to the turgid balloon sealing the entry to the body passageway, e.g., the ostium, "against fluid flow therethrough", or words of similar import, does not necessarily require perfect seal- ing, i.e., no leakage whatsoever, although that is the preferred condition. It suffices, however, if the sealing substantially reduces or nearly eliminates any such fluid flow. [0041] It will be noted that the prior art device of Figure 4A differs from the embodiment of the invention illustrated in Figure 4B in a number of ways. One difference is that the balloon 134 of the prior art structure is much closer to the distal tip 122c of distal portion 122b of flexi- ble cannula 122 than the balloon 34 of the embodiment of the invention is to distal tip 22c of distal portion 22b of balloon 20. Stated otherwise, the present invention provides for a significantly longer distal portion 22b than do the structures of the prior art. Accordingly, in order to secure balloon 134 of the prior art within coronary sinus 44, it must be emplaced well beyond the ostium 46 and may utilize prior art expedients (such as the unnumbered protruding knobs) on the exterior surface of balloon 134 to hold it in place within the coronary sinus 44. Because of the necessarily advanced (beyond ostium 46) position of balloon 134 within coronary sinus 44, the entire portion of coronary sinus 44 proximal (leftwardly as viewed in Figure 4A) of balloon 134 is isolated by the balloon from the flow of cardioplegic fluid emanating from distribution apertures 138 (Figure 4A-1). Another significant difference between the present in- vention and the prior art is that the prior art balloon catheter 120 does not provide that its proximal portion 122a has a higher flexural modulus (is stiffer) than its distal portion 122b, and therefore cannot avail itself of being held in place by an external force applied to the proximal portion, but must rely on balloon 134 being inflated enough to firmly seat itself within coronary sinus 44. To this end, prior art expedients include the provision of a rough side surface of the inflatable balloon, e.g., the provision of protrusions thereon, to enhance gripping of the balloon by the interior of the coronary sinus. This may result in damage to or irritation of the interior wall of the coronary sinus.

[0042] In contrast, as viewed in Figure 4B, pressure, e.g., that of the collapsing or collapsed right atrial wall 42, imposed on the rigid proximal portion 22a of cannula 22, in conjunction with the tapered shape of turgid balloon 34, maintains the latter firmly seated in the ostium 46, thereby leaving substantially the entire length of coronary sinus 44 open to the infusion of cardioplegia fluid via distribution apertures 38. As noted above, any suitable construction may be utilized to increase the flexural modulus, i.e., the stiffness, of proximal portion 22a. Figure 2 shows one such stiffening construction. In Figure 2, as in the case of Figure 1C, balloon 34 separates proximal portion 22a of flexible cannula 22 from distal portion 22b thereof, within which distribution apertures 38 are located. The construction of the embodiment of Figure 2 differs from that of Figure 1C in that Figure 2 additionally contains a stiffening member comprising a stiffening tube 33 mounted on the exterior surface of proximal portion 22a. As indi- cated above, any other construction which provides the requisite stiffriess to proximal portion 22a may be utilized. The particular construction illustrated in Figure 2 shows that stiffening tube 33 terminates at the interior of base 34c of inflatable balloon 34. In an alternate embodiment, stiffening tube 33, or one of the other above-described stiffening constructions, may be extended to the apex 34d of inflatable balloon 34. Of course, if stiffening tube 33 is extended to apex 34d, apertures must be provided therein in alignment with inflation apertures 36 in order to permit the flow of inflation fluid into the interior of inflatable balloon 34. The same would, of course, apply to an interior stiffening tube used within the portion of cannula 22 lying within inflatable balloon 34. Extending the stiffening structure, regardless of the type of stiffening structure employed, to apex 34d rather than terminating it at base 34c, has the advantage of providing a more stable support for balloon 34, and to that extent may be considered a preferred construction. The portion of cannula 22 lying within inflatable balloon 34 may be considered to be a transition section of cannula 22 separating proximal portion 22a thereof from distal portion 22b thereof. Desirably, the transition section may have a flexural modulus which is the same as or greater than that of proximal portion 22a, or it may have a flexural modulus intermediate that of proximal portion 22a and distal portion 22b.

[0043] By thus providing for secure retention of turgid balloon 34 in sealing position in ostium 46 by a force imposed via stiff proximal portion 22a, the prior art expedient of positioning the inflatable balloon further within the coronary sinus (as seen in Figure 4A) to eliminate or reduce the likelihood of the balloon's becoming dislodged from the coronary sinus is not needed. Accordingly, with the device of the present invention, as illustrated in Figure 4B, a significant portion of the coronary sinus is not isolated by the balloon from distribution apertures 38 as is the case with the prior art embodiment illustrated in Figure 4A. Accordingly, the present invention enables overcoming the prior art difficulties of insufficient infusion to the right side of the heart as described in the above-noted article in Advances in Cardiac Surgery. [0044] The balloon catheter 20 may be removed from the heart in conventional manner when the procedure is completed.

[0045] While the invention has been described with respect to a specific embodiment thereof, it will be appreciated that numerous alterations thereto may be made, which nonethe- less lie within the spirit and scope of the present invention and the appended claims.

Claims

THE CLAIMSWhat is claimed is:

1. In a retrograde venous cardioplegia balloon catheter for administering cardioplegic fluid from an external source into a patient's heart through the coronary sinus via the ostium, the catheter comprising: a flexible cannula having a distal portion separated from a proximal portion thereof by an inflatable balloon, the distal portion of the cannula (i) being dimensioned and configured to be inserted through the patient's ostium into the coronary sinus, and (ii) having at least one distribution aperture therein for introducing cardioplegic fluid conducted through the cannula into the patient's coronary sinus; the inflatable balloon having a longitudinally tapered configuration providing an apex end adjoining the distal portion of the cannula and a base end adjoining the proximal por- tion of the cannula, the base end having a diameter which is greater than the diameter of the apex end; and at least one inflation aperture disposed within the balloon for introducing an inflating fluid into the balloon to inflate the balloon into a turgid condition; the improvement comprising that the balloon is dimensioned and configured to that, when inflated into a turgid condition, the diameter of the base end is sufficiently greater than the diameter of the ostium whereby travel of the catheter into the coronary sinus is arrested as the turgid balloon lodges in and seals the ostium, thereby limiting the extent of travel of the balloon into the coronary sinus.

2. In a retrograde venous cardioplegia balloon catheter for administering cardioplegic fluid from an external source into a patient's heart through the coronary sinus via the ostium, the catheter comprising: a flexible cannula having a distal portion separated from a proximal portion thereof by an inflatable balloon, the distal portion of the cannula (i) being dimensioned and configured to be inserted through the patient's ostium into the coronary sinus, and (ii) having at least one distribution aperture therein for introducing cardioplegic fluid conducted through the cannula into the patient's coronary sinus; and at least one inflation aperture disposed within the balloon for introducing an inflating fluid into the balloon to inflate the balloon into a turgid condition, the resulting turgid balloon being dimensioned and configured to seal the ostium; the improvement comprising that the proximal portion of the flexible cannula is suf- ficiently rigid to transmit force applied thereto to the balloon whereby to hold the turgid balloon in place to seal the ostium against fluid flow therethrough.

3. The catheter of claim 2 wherein the inflatable balloon has a longitudinally tapered configuration providing an apex end adjoining the distal portion of the cannula and a base end adjoining the proximal portion of the cannula, the base end having a diameter which is greater than the diameter of the apex end, and the improvement further comprises that the balloon is dimensioned and configured so that, when inflated into a turgid condition, the diameter of the base end is sufficiently greater than the diameter of the ostium whereby travel of the distal portion of the catheter into the coronary sinus is arrested as the turgid balloon lodges in and seals the ostium, thereby limiting the extent of travel of the balloon into the coronary sinus.

4. The catheter of claim 1 , claim 2 or claim 3 wherein the flexible cannula comprises a supply lumen dimensioned and configured to be connected to a source of cardioplegic fluid and an auxiliary lumen dimensioned and configured to be connected to a source of inflating fluid, and wherein the at least one distribution aperture is formed in the supply lumen, and the at least one inflation aperture is formed in the auxiliary lumen and is in fluid flow communication with the interior of the balloon.

5. The catheter of claim 1, claim 2 or claim 3 wherein the distal portion of the flexible cannula is sufficiently flexible to preclude penetration of heart tissue by the distal portion.

6. The catheter of claim 1, claim 2 or claim 3 wherein the proximal portion of the catheter has a higher flexural modulus than the distal portion of the catheter, and the distal portion of the catheter is sufficiently flexible to preclude penetration of heart tissue by the distal portion.

7. The catheter of claim 6 wherein the proximal portion of the catheter carries thereon a stiffening structure to enhance its flexural modulus.

8. The catheter of claim 1 , claim 2 or claim 3 wherein the inflatable balloon has a smooth outer surface.

9. The catheter of claim 1 or claim 3 wherein, when the inflatable balloon is in its tur- gid condition, the base end of the balloon has a diameter of from about 10 to 20 millimeters, the apex end of the balloon has a diameter less than that of the base end and from about 6 to 10 millimeters, and the length of the balloon measured longitudinally between the base end and the apex end is from about 20 to 25 millimeters.

10. A method for infusion of a cardioplegic fluid from an external source into a patient's heart through the coronary sinus via the ostium utilizes a retrograde venous cardioplegia balloon catheter having: a flexible cannula, the flexible cannula being comprised of a distal portion and a proximal portion separated from the distal portion by an inflatable balloon; the inflatable balloon (i) being inflatable into a turgid condition, (ii) having a longitudinally tapered configu- ration providing an apex end adjoining the distal portion of the cannula and a base end adjoining the proximal portion of the cannula, the base end having a diameter which is greater than the diameter of the apex end and greater than the diameter of the ostium when the balloon is in its turgid condition, the distal portion (iii) having at least one distribution aperture therein for dispensing the cardioplegic solution and (iv) being sufficiently flexible to preclude penetration of heart tissue by the distal portion; the method comprising the steps of inserting the distal portion of the flexible cannula into the patient's coronary sinus to position the inflatable balloon within the ostium, inflating the inflatable balloon to its turgid condition and advancing the catheter into the coronary sinus until travel of the catheter into the coronary sinus is arrested by lodgment of the turgid balloon in the ostium, and flowing the cardioplegic fluid through the cannula and the distribution aperture into the patient's heart through the coronary sinus.

11. A method for infusion of a cardioplegic fluid from an external source into a patient's heart through the coronary sinus via the ostium utilizes a retrograde venous cardioplegia bal- loon catheter having: a flexible cannula, the flexible cannula being comprised of a distal portion and a proximal portion separated from the distal portion by an inflatable balloon which is inflatable into a turgid condition, the distal portion having at least one distribution aperture therein for dispensing the cardioplegic solution, and the balloon having an inflation aperture disposed within it, the proximal portion of the flexible cannula being sufficiently rigid to trans- mit force applied thereto to the balloon in its turgid condition, and the distal portion of the cannula being less rigid than the proximal portion and sufficiently flexible to preclude penetration of heart tissue by the distal portion; the method comprising the steps of inserting the distal portion of the flexible can- nula into the patient's coronary sinus to position the inflatable balloon within the ostium, inflating the inflatable balloon to its turgid condition in which the inflatable balloon is dimensioned and configured to seal the ostium against fluid flow therethrough, imposing a force on the proximal portion of the flexible cannula to maintain the turgid inflatable balloon in sealing position within the ostium, and flowing the cardioplegic fluid through the cannula and the dis- tribution aperture into the patient's heart through the coronary sinus.

12. The method of claim 11 wherein the inflatable balloon has a longitudinally tapered configuration providing an apex end adjoining the distal portion of the cannula and a base end adjoining the proximal portion of the cannula, the base end having a diameter which is greater than the diameter of the apex end, and greater than the diameter of the ostium, and the method further comprises the steps of inserting the distal portion of the flexible cannula into the patient's coronary sinus to position the inflatable balloon within the ostium, inflating the inflatable balloon to its turgid condition, and advancing the catheter into the coronary sinus until travel of the catheter in the coronary sinus is arrested by lodgment of the turgid balloon in the ostium, and flowing the cardioplegic fluid through the cannula and the distribution aperture into the patient's heart through the coronary sinus.

13. The method of claim 10, claim 11 or claim 12 wherein the flexible cannula is inserted into the patient's heart by making an incision in the right atrial wall of the heart and passing the flexible cannula through the resulting incision and through the right atrial chamber.

14. The method of claim 11 or claim 12 wherein the flexible cannula is inserted into the patient's heart by making an incision in the right atrial wall of the heart and passing the flexible cannula through the resulting incision and through the right atrial chamber, and the step of im- posing a force on the proximal portion of the flexible cannula is carried out by securing the flexible cannula to the right atrial wall and collapsing the right atrial wall towards the ostium.

15. The method of claim 14 wherein the step of collapsing the right atrial wall towards the ostium is carried out by draining the patient's blood from the right atrial chamber.

16. The method of claim 10, claim 11 or claim 12 wherein the flexible cannula comprises a supply lumen dimensioned and configured to be connected to a source of the cardioplegic fluid and an auxiliary lumen dimensioned and configured to be connected to a source of in- flating fluid, and wherein the distribution aperture is formed in the supply lumen, and the inflation aperture is formed in the auxiliary lumen and is in fluid flow communication with the interior of the balloon, and the method further comprises flowing the inflating fluid through the auxiliary lumen and via the inflation aperture into the inflatable balloon to inflate the balloon to its turgid con- dition, and flowing the cardioplegic fluid through the supply lumen and out the distribution aperture.