INTRODUCER

CROSS-REFERENCE TO RELATED APPLICATIONS

[0001] The subject application claims benefit under 35 U. S. C. §119(e) to pending U.S. provisional patent application nos. 61/046,207 filed April 18, 2008 and 61/046,707 filed April 21, 2008, each disclosure of which in their entirety, is herein incorporated by reference.

FIELD OF THE DISCLOSURE

[0002] Embodiments of the present disclosure are directed to systems, methods, and devices for accessing mammalian hearts without blood loss.

BACKGROUND OF THE DISCLOSURE

[0003] Cardiovascular disease or cardiovascular diseases refers to the class of diseases that involve the heart or blood vessels (arteries and veins). This class of diseases thus refers to any disease that affects the cardiovascular system; any may include atherosclerosis (arterial disease), coronary artery disease, valvular heart disease, ischemic heart disease (IHD), or myocardial ischaemia. These diseases are characterized by reduced blood supply to the heart muscle, usually due to coronary artery disease (atherosclerosis of the coronary arteries). Depending on the symptoms and risk, treatment may be with medication, percutaneous coronary intervention (angioplasty) or conventional open-heart surgery.

[0004] Best known of the current techniques for the treatment of severe cardiovascular disease is conventional open-heart surgery, which may be used to perform coronary artery bypass grafting, mitral valve replacement, or aortic valve replacement. Coronary artery bypass grafting is a relatively invasive technique wherein a thoracotomy is performed to expose the patient's heart, and one or more coronary arteries are replaced with synthetic grafts. Valve replacement is a cardiac surgery procedure in which a patient's aortic or mitral valve is replaced by a different valve. Mitral valve replacement therapy is typically performed when the valve becomes too tight (mitral valve stenosis) for blood to flow into the left ventricle, or too loose (mitral valve regurgitation) in which case blood can leak into the left atrium and back up into the lung. Some individuals have a combination of mitral valve stenosis and mitral valve regurgitation or simply one or the other. Aortic valve replacement is a cardiac surgery procedure in which a patient's aortic valve is replaced by a different valve. The aortic valve

can also become leaky (aortic insufficiency / regurgitation) or partially blocked (aortic stenosis).

[0005] Conventional approaches for cardiac valve replacement require the cutting of a relatively large opening in the patient's sternum ("sternotomy") or thoracic cavity ("thoracotomy") in order to allow the surgeon to access the patient's heart. For example, conventional open-heart surgery or cardiac valve replacement is most frequently done through a median sternotomy, meaning the chest-bone is sawed in half. Once the pericardium has been opened, the patient is placed on cardiopulmonary bypass machine, also referred to as the heart- lung machine. This machine takes over the task of breathing for the patient and pumping their blood around while the surgeon replaces the heart valve. Additionally, these approaches require arrest of the patient's heart and a cardiopulmonary bypass. These techniques are thus extremely invasive and are accompanied risk of death or serious complications, depending on the health and age of the patient, as well as the skill of the surgeon. Older patients, as well as more fragile ones, are sometimes ineligible for surgery because of elevated risks.

[0006] In recent years, efforts have been made to establish a less invasive cardiac valve replacement procedure, by delivering and implanting a cardiac replacement valve via a catheter percutaneously (i.e., through the skin) via either a transvascular approach — delivering the new valve through the femoral artery, or by transapical route, where the replacement valve is delivered between ribs and directly through the wall of the heart to the implantation site. For example, percutaneous heart valve replacement therapies (e.g., cardiac catheterization, coronary angiography, left ventricle angiography) may involve the insertion of a catheter into a chamber or vessel of the heart. Once the catheter is in place, it can be used to perform a number of procedures including angioplasty, angiography, and balloon septostomy. To perform this technique, a small puncture is made in a vessel in the groin, the inner bend of the elbow, or neck area (the femoral vessels or the carotid/jugular vessels), then a guidewire is inserted into the incision and threaded through the vessel into the area of the heart that requires treatment, visualized by fluoroscopy or echocardiogram, and a catheter is then threaded over the guidewire. If X-ray fluoroscopy is used, a radiocontrast agent will be administered to the patient during the procedure. When the necessary procedures are complete, the catheter is removed. Firm pressure is applied to the site to prevent bleeding. This may be done by hand

or with a mechanical device. Other closure techniques include an internal suture. Cardiac interventions such as the insertion of a stent prolong both the procedure itself as well as the post-catheterization time spent in allowing the wound to clot.

[0007] While less invasive and arguably less complicated, percutaneous heart valve replacement therapies (PHVT) still have various shortcomings, including the inability for a surgeon to ensure proper positioning and stability of the replacement valve within the patient's body. Specifically, if the replacement valve is not placed in the proper position relative to the implantation site, it can lead to poor functioning of the valve. For example, in an aortic valve replacement, if the replacement valve is placed too high, it can lead to valve regurgitation, instability, valve prolapse and/or coronary occlusion. If the valve is placed too low, it can also lead to regurgitation and mitral valve interaction.

[0008] Off-pump trans left ventricular approach provides a precise deployment of stented aortic valve of any size with respect to the endovascular replacement. See e.g., Tozzi et al, Eur J Cardiothorac Surg. 2007 Jan;31(l):22-5. One of the key steps of the transventricular approach, however, is the introduction of implants through the ventricular defect. Safely acessing a hole in the free wall of the ventricle can be a challenging procedure if there is no support of the extracorporeal circulation. Moreover, since all the procedure is done percutaneously, the access of the ventricle defect is all the more difficult - for example, the use of conventional introducers can result in a significant amount of blood loss. Thus, despite the progress made in the development of trans-apical valve replacement, reliable systems for delivering stents, stent-valve, or other implants via ventricular access {e.g., left ventricle access) remains a major issue. Accordingly, there remains a need for devices and methods that can aid the trans-apical delivery of implantation devices.

[0009] Throughout this description, including the foregoing description of related art, any and all publicly available documents described herein, including any and all U. S. patents, are specifically incorporated by reference herein in their entirety. The foregoing description of related art is not intended in any way as an admission that any of the documents described therein, including pending United States patent applications, are prior art to the present invention. Moreover, the description herein of any disadvantages associated with the described products, methods, and/or apparatus, is not intended to limit the invention. Indeed, aspects of

the invention may include certain features of the described products, methods, and/or apparatus without suffering from their described disadvantages.

SUMMARY OF THE DISCLOSURE

[0010] The present invention provides introducers used to access the heart of a patient without significant blood loss. According to some embodiments, the invention provides introducers used for ventricular access to the heart. According to some embodiments, the invention provides introducers used to access the left ventricle of the heart.

[0011] According to some embodiments, the introducer at least comprises the following four elements: (1) a sheath 10; (2) a sealing valve assembly 20; (3) a vacuum seal assembly 30, 60; and (4) a relief pressure valve 40.

[0012] According to some embodiments, the introducer at least comprises the following four elements: (1) a tubular shaft or sheath having a proximal end and a distal end 10; (2) a sealing valve assembly 20, 50; (3) a vacuum seal assembly 30, 60; and (4) a relief pressure valve 40.

[0013] According to some embodiments, the introducer at least comprises a) a proximal valve assembly or hub portion having an interior lumen 50; b) a tubular shaft or sheath extending distally from the hub portion and having a lumen in communication with the interior lumen of the hub portion 10; c) a sealing valve disposed within the lumen of the hub 20; (3) a vacuum seal assembly 30, 60; and (4) a relief pressure valve 40.

[0014] According to some embodiments, the introducer comprises four elements: (1) a sheath 10, encompassing an access lumen penetrating the heart wall V; (2) a sealing valve 20, preferably capable of preventing blood leaks; (3) a vacuum seal 30, 60, preferably capable of allowing the introducer to stay in an appropriate position without additional manual or mechanical positioning; and (4) a relief pressure valve 40, preferably capable of integrating to the introducer, thus preventing any blood overpressure in the left ventricle, which occurs during ballooning of a calcified aortic valve, without rapid pacing.

[0015] According to some embodiments, the introducer comprises four elements: (1) a sheath 10, encompassing an access lumen up to the surface of the heart wall V, with the

advantage in the reduction of the access hole diameter; (2) a sealing valve 20, preferably capable of preventing blood leaks; (3) a vacuum seal 30, 60, preferably capable of allowing the introducer to stay in an appropriate position without additional manual or mechanical positioning; and (4) a relief pressure valve 40, preferably capable of integrating to the introducer, thus preventing any blood overpressure in the left ventricle, which occurs during ballooning of a calcified aortic valve, without rapid pacing.

[0016| In some embodiments of the introducers of the invention, the introducer is used to access the left ventricle of the heart through the heart wall without blood loss.

[0017] In some embodiments of the introducers of the invention, the introducer is used to provide access to a failed native aortic valve in need of replacement.

[0018] According to some embodiments, the vacuum seal 30, 60, of the introducer preferably is fixed to the introducer sheath 10, allowing the introducer to stay in appropriate position without additional manual or mechanical positioning as would be needed with introducers known in the art. By using vacuum, the introducer sheath is preferably fixed to the external heart surface.

[0019] According to some embodiments of the invention, a relief pressure valve 40, is preferably integrated to the introducer, preventing any blood overpressure in the left ventricle, which occurs during ballooning of a calcified aortic valve, without rapid pacing. The overflowing blood may even be re-perfused to the patient. This system preferably allows ballooning of calcified native valves or post-dilatation of stented valves without rapid pacing to reduce the cardiac output. Avoiding rapid pacing preferably reduces the procedure related risks for this class of patients.

[0020] In some embodiments of the invention, the introducer is used to exchange catheters, if required, by a surgical procedure, e.g. , insertion of a balloon catheter for native valve dilatation, exchange with stented valve delivery system for valve implantation, and again exchange with balloon catheter for stented valve post-dilatation.

[0021] In some embodiments of the invention, the introducer of the invention is used in conjunction with the introduction of a collapsible stent- valve, by means of a catheter through the wall of the heart to replace a damaged heart valve in a patient.

[0022] According to some embodiments, the present invention provides a method for cardiac valve replacement comprising: 1) providing an introducer comprising: a) a proximal valve assembly having an interior lumen 50, wherein a sealing valve 20 is disposed within the lumen 50; b) a sheath extending distally from the hub portion and having a lumen 10, in communication with the interior lumen of the valve assembly 20, 50; c) a vacuum seal assembly 30, 60, wherein the vacuum assembly comprises a flange portion 60, having a flange surface; and d) a relief pressure valve 40; 2) creating a vacuum seal between the flange surface of the vacuum seal assembly and an outer ventricular wall; 3) introducing a stent- valve into the sheath; 4) advancing the stent- valve to the desired position; and 5) removing the sheath, leaving the stent- valve disposed within the heart of the patient.

[0023] According to some embodiments, the cardiac valve is a mitral valve or an aortic valve.

[0024] According to some embodiments, the stent- valve may be covered with a sheath to maintain the stent-valve in a collapsed configuration. According to some embodiments, the stent- valve may be inserted in a collapsed configuration through the introducer and into the heart without contacting the ascending aorta or aortic arch. According to some embodiments, the stent-valve may be partially expanded by sliding the sheath towards the left ventricle of the heart after it has passed through the introducer at the heart wall. According to some embodiments, the stent-valve may be passed through the lumen of the introducer sheath. According to some embodiments, the stent-valve may be positioned by passing it through the introducer by means of a catheter.

[0025] According to some embodiments, the present invention provides a method for delivering a cardiac implantation device to an cardiac implantation site in a patient, comprising the steps of: 1) providing an introducer comprising: a) a sealing valve 20, assembly having an interior lumen, wherein a sealing valve 20, is disposed within the lumen; b) a sheath extending distally from the hub portion and having a lumen 10, in communication with the interior lumen

of the valve assembly 50,; c) a vacuum seal assembly 30, 60, wherein the vacuum assembly comprises a flange portion having a flange surface; and d) a relief pressure valve 40; 2) creating a vacuum seal between the flange surface of the vacuum seal assembly and an outer ventricular wall; 3) introducing a medical device into the sheath; 4) advancing the medical device to the desired position; and 5) removing the sheath, leaving the medical device disposed within the heart of the patient.

BRIEF DESCRIPTION OF THE DRAWINGS

[0026] For a better understanding of the present invention, reference is made to the following description, taken in conjunction with the accompanying drawings, in which like reference characters refer to like parts throughout, and in which:

[0027) FIG. 1 is a side view of an introducer comprising four elements and the heart wall: (1) a sheath 10, encompassing an access lumen penetrating the heart wall and a hub 50; (2) heart wall through which the access lumen penetrates through (V); (3) a sealing valve 20; (4) a vacuum seal 30; and (5) a relief pressure valve 40.

[0028] FIG. 2 is a side view of an introducer comprising four elements and the heart wall: (1) a sheath, encompassing an access lumen up to the surface of the heart wall 10 and a hub 50; (2) heart wall through which, according to some of the embodiments, the access lumen does not penetrate (V); (3) a sealing valve 20; (4) a vacuum seal 30; and (5) a relief pressure valve 40.

DETAILED DESCRIPTION OF THE INVENTION

[0029] For the purposes of promoting an understanding of the principles of the invention, reference will now be made to the embodiments illustrated in the drawings, and specific language will be used to describe the same. It should nevertheless be understood that no limitation of the scope of the invention is thereby intended, such alterations and further modifications in the illustrated device, and such further applications of the principles of the invention as illustrated therein being contemplated as would normally occur to one skilled in the art to which the invention relates.

[0030] In the following discussion, the terms "proximal" and "distal" will be used to describe the opposing axial ends of the inventive sheath, as well as the axial ends of various component features. The term "proximal" is used in its conventional sense to refer to the end of the apparatus (or component thereof) that is closest to the operator during use of the apparatus. The term "distal" is used in its conventional sense to refer to the end of the apparatus (or component thereof) that is initially inserted into the patient, or that is closest to the patient.

[0031] According to some embodiments, the introducers of the present invention are used in medical procedures accessing the inner organs or other tissues. Preferably, the introducers of the present invention are used in medical procedures accessing the heart, such as the apex of the heart or left ventricle apex.

[0032] According to some embodiments, the left ventricle is access using any known method in the art. Such methods of accessing the left ventricle include, but are not limited to partial inferior sternotomy, complete sternotomy, or anterolateral minithoracotomy (preferably in the fifth or sixth intercostal space). For positioning of the introducer, the inner organ (e.g., left ventricle) may be punctured with a guide wire. Next, the introducer assembly may be threaded over the guide wire. The introducer assembly may then be advanced through the tissue to the desired position. Once the sheath is installed, a lead, catheter, or similar diagnostic or therapeutic device may then introduced into the sheath and advanced to the desired position for the desired effect on the heart. Conventionally, a sheath inserted in the above fashion provides a passage for the free flow of blood and generally results in significant blood loss to the patient. The introducers of the present invention, however, are designed prevent the free flow of blood through the introducer sheath.

[0033] Thus, according to some embodiments, the present invention provides introducers used to access the heart of a patient with little or no significant blood loss. According to some embodiments, the introducer at least comprises the following four elements: (1) a sheath 10; (2) a sealing valve assembly 20, 50; (3) a vacuum seal assembly 30, 60; and (4) a relief pressure valve 40.

[0034] According to some embodiments, the introducer at least comprises the following four elements: (1) a tubular shaft or sheath having a proximal end and a distal end 10; (2) a sealing valve assembly 20, 50; (3) a vacuum seal assembly 30, 60; and (4) a relief pressure valve 40.

[0035] According to some embodiments, the introducer at least comprises a) a proximal valve assembly or hub portion having an interior lumen 50; b) a tubular shaft or sheath extending distally from the hub portion and having a lumen 10, in communication with the interior lumen of the hub portion 50; c) a sealing valve disposed within the lumen of the hub 20; (3) a vacuum seal assembly 30, 60; and (4) a relief pressure valve 40.

Sheath

[0036] Figures 1 and 2 show two embodiments of the introducers of the present invention. The introducer shown in Figure 1 comprises an access lumen or sheath 10, penetrating the heart wall (V) whereas the introducer shown in Figure 2 comprises an access lumen 10, up to the surface of the heart only. The advantage thereby is the reduction of the access hole diameter. Both introducers comprise a sheath 10 and a sealing valve 20 preventing or reducing blood leaks.

[0037] According to some embodiments, the sheath is either rigid or flexible, wherein the sheath may be an elongated tubular shaft having a proximal and distal end, comprising an interior access lumen.

[0038] According to some embodiments, the introducer comprises a sheath 10, wherein the sheath encompasses an access lumen penetrates the heart wall. In some other embodiments of the invention, the sheath encompassing an access lumen does not penetrate the heart wall, 10 in Figure 2.

[0039] According to some embodiments, the introducer comprises a proximal hub portion having an interior lumen 50, an elongated sheath extending distally from the hub portion with a lumen in communication with the interior lumen of the hub portion 10, and a sealing valve 20, disposed within the lumen of the hub portion 50. The introducers of the invention further provide the advantages of a vacuum seal and a relief pressure valve.

Sealing Valve

[0040] According to some embodiments, a sealing valve 20, assembly is positioned proximally on the introducer. The sealing valve assembly may comprise a hub 50, with an interior lumen in communication with the interior lumen of the sheath 10. The sealing valve assembly preferably comprises a sealing valve component that is made up of a material or mixture of material that is capable of permitting the passage of catheters and/or guidewires {e.g., capable of being punctured and passed thru). The sealing valve component may include a sealing flap. The sealing valve component may comprise a polymeric plug, a slit valve, a haemostatic valve, a foldable haemostatic valve, foam, polymeric sponge filling, or a self- sealing silicone.

[0041] According to some embodiments, the sealing valve component seals the lumen of the sheath against hydrostatic pressure, but preferably allows passage of a needle, probe, balloon catheter or any tissue operative instrument known to those in the art, by way of a slit, for operation. Preferably, the sealing valve component resiliently closes after removal of any operative instrument.

Vacuum Seal

[0042] A vacuum seal assembly 30 is fixable to the introducer sheath 10 and enables the introducer to stay in appropriate position without additional manual or mechanical positioning as is needed with introducers known in the art. By using vacuum, the introducer sheath is fixed to the external heart surface. According to some embodiments, the introducer creates a vacuum seal between the introducer and the wall of the tissue {e.g., heart or ventricle wall). The tubular shaft of the introducer extends past the point of the vacuum shaft and extends proximally in to the wall of the tissue. The tublar shaft may penetrate the tissue wall and into the tissue cavity (FIG. 1), or may be extended to a length equal to the thickness of the tissue wall {e.g., ventricular wall), thereby reducing the tissue access hole diameter (FIG. 2).

[0043] According to some embodiments, the introducer a vacuum seal assembly that comprises a flange portion 60 having a flange surface with an opening therein. The vacuum seal assembly may be fixed to the introducer sheath or may be slidable along the tubular shaft of the sheath 10 and locked into position. The flange portion may be placed against the outer

surface of the ventricular wall and suction applied thereby generating a seal between the flange portion and the tissue wall. Such a vacuum seal allows the introducer to stay in appropriate position without additional manual or mechanical positioning.

[0044] According to some embodiments, an air line of an air suction device may be connected to the vacuum seal 30 (e.g., via a the nipple connector) and a vacuum is generated in the space between the vacuum seal flange 60 and the outer surface of the tissue wall. The introducer is thus securely positioned to the tissue wall.

[0045] Preferably, the length of the flange 60, the portion extending outward from the sheath that comes into contact with the tissue, is greater then about 5 mm. According to some embodiments, the length of the flange 60 is between about 5 to about 50 mm (e.g., about 5 mm, about 6 mm, about 7 mm, about 8 mm, about 9 mm, about 10 mm, about 11 mm, about 12 mm, about 13 mm, about 14 mm, about 15 mm, about 20 mm, about 22 mm, about 24 mm, about 25 mm, about 26 mm, about 28 mm, about 30 mm, about 32 mm, about 34 mm, about 36 mm, about 38 mm, about 40 mm, about 42 mm, about 44 mm, about 45 mm, about 46 mm, about 48 mm, and about 50 mm). According to some embodiments, the length of the flange 60 may range from about 5 to about 40 mm, about 5 to about 30 mm, about 5 to about 20 mm, about 5 to about 10 mm, about 10 to about 50 mm, about 10 to about 40 mm, about 10 to about 30 mm, about 10 to about 20 mm, about 15 to about 50 mm, about 15 to about 40 mm, or about 15 to about 30 mm.

[0046] The vacuum created by the introducer is preferably between about 200-800 mm Hg (e.g., about 200 mm Hg, about 250 mm Hg, about 300 mm Hg, about 350mm Hg, about 375 mm Hg, about 400 mm Hg, about 425 mm Hg, about 450 mm Hg, about 475 mm Hg, about 500 mm Hg, about 550 mm Hg, about 600 mm Hg, about 650 mm Hg, about 700 mm Hg, and about 650 mm Hg). According to some embodiments, the vacuum created by the introducer is preferably between about 300-500 mm Hg. According to some embodiments, the vacuum created by the introducer is preferably between about 350-400 mm Hg. According to some embodiments, the vacuum created by the introducer is preferably about 400 mm Hg.

[0047] Analog systems may be used for performing beating heart, minimal invasive coronary by-pass surgeries (e.g., the Octopus system) thereby stabilizing the heart surface during suturing.

Relief Pressure Valve

[0048] According to some embodiments, a relief pressure valve 40 is integrated to the introducer that prevents any blood overpressure in the left ventricle, which may occur, for example, during ballooning of a calcified aortic valve, without rapid pacing. The overflowing blood may be re-perfused to the patient. This system allows ballooning of calcified native valves or post-dilatation of stented valves without rapid pacing to reduce the cardiac output. Avoiding rapid pacing reduces the procedure related risks for this class of patients.

Methods of Implantation

[0049] The introducers of the present invention are designed to maximize access and stabilization of the ventricular apex for off-pumping cardiac repair procedures. In preferred embodiments, the introducer of the invention is used in conjunction with the introduction of a stent (e.g., collapsible stent), stent- valve, or other implantation device known in the art to be useful for treating a defect in the heart. Preferably, the implantation device is delivered by means of a catheter through the wall of the heart. According to some embodiments, the introducers are used in a method to replace a damaged heart valve (e.g., mitral valve or aortic valve) in a patient.

[0050] In preferred embodiments, the introducer of the invention is used in conjunction with the introduction of a collapsible stent- valve, by means of a catheter through the wall of the heart of replace a damaged heart valve in a patient. The stent-valve may be covered with a sheath in order to maintain the stent-valve in a collapsed configuration. The stent-valve may then be inserted in the collapsed configuration into the human body, through the introducer of the invention, without contacting the ascending aorta or aortic arch. The stent-valve may be partially expanded by sliding the sheath towards the left ventricle of the heart after it has passed through the introducer of the invention at the heart wall. The stent-valve is passed through the lumen of the introducer sheath 10. In preferred embodiments, the stent-valve is positioned by passing it through the introducer of the invention by means of a catheter.

[0051] The sliding of the sheath towards the left ventricle may cause expansion of a distal end of the stent- valve while the proximal end of the stent- valve remains constrained by the sheath. The sheath may be further slid towards the left ventricle of the heart in order to cause full expansion of the stent- valve. In some embodiments, the stent- valve may be recaptured prior to its full expansion by sliding the sheath in the opposite direction.

[0052] In some embodiments, a method for cardiac valve replacement is provided that includes releasing a distal end of a stent- valve from a sheath, where the distal end includes a radiopaque marker positioned thereon.

[0053] The stent- valve may be rotated, if necessary, to orient the stent-valve appropriately with respect to the coronary arteries (e.g., to prevent the commissures from facing the coronary arteries). Arches of the stent-valve may be released from the sheath, in order to cause the arches to contact the aorta. A first conical crown of the stent-may be released from the sheath, in order to cause the first conical crown to contact the native valve leaflets. A second crown of the stent-valve is released from the sheath, in order to cause the second crown to contact an annulus/inflow tract. The second crown may be the proximal section of the stent-valve such that releasing the second crown causes the stent-valve to be fully released from the sheath. After positioning and release of the stent-valve, the catheter is withdrawn through the shaft of the introducer of the invention.

[0054] In some embodiments, a stent-valve, delivery system, and method for delivering the stent-valve to an implantation site are provided in which the stent-valve is expanded at the implantation site, after passing through the introducer shaft of the invention, in a stepwise manner from its distal end towards its proximal end. For example, the release procedure for causing expansion of the stent-valve may involve pulling back a sheath constraining the stent- valve towards the left ventricle of the heart. According to this procedure, there may be no interaction of the delivery system with the anatomy of the ascending aorta/aortic arch. For example, the sheath constraining the stent-valve and the tip of the delivery system may not be required to enter the aortic arch during the release procedure, which is beneficial since such entry potentially can cause a bending moment acting onto the stent-valve and result in inaccurate positioning of the implant (e.g., tilting).

[0055] Variances in size or shape of the introducers are also intended to encompass pediatric uses, although the preferred use is for adult human hearts. It is well recognized that pediatric uses may require reductions in size of the various components of the introducers.