Patent Application
20230037979
This patent document relates to medical devices. More particularly, but not by way of limitation, the patent document relates to catheters.
Dual (or double) lumen pigtail catheters can be used in interventional procedures to measure a pressure gradient across native valves or bioprosthetic valves of the heart, across stenoses within native vascular lumens of the body, or across other narrowings found within non-vascular cavities or tubular members of the body. A distal region of a pigtail catheter that is adapted to measure a distal pressure can be placed distal to a stenosis or narrowing, and a proximal region of the pigtail catheter that is adapted to measure a proximal pressure can be placed proximal to the stenosis or narrowing to allow measurement of a pressure gradient across the stenosis or narrowing. Measurement of a pressure gradient across an aortic valve, for example, can be accomplished by placing a distal region of a pigtail catheter into the left ventricle (LV) to measure the LV pressure and positioning a more proximal region of the pigtail catheter in the ascending aorta to measure the aortic pressure. A high-pressure gradient across the aortic valve is indicative of aortic valve stenosis, which can be treated via valvuloplasty, transcatheter aortic valve replacement, surgical valve replacement, medications, or other treatment methods. Other stenoses can be treated via placement of a stent, for example, to enlarge a stenosis found in a native arterial or prosthetic conduit or other non-vascular organ conduit of the body.
Dual lumen pigtail catheters in current use are formed with a catheter shaft including coaxial lumens and are associated with drawbacks. Such catheters are susceptible to recording less reliable pressure signals from the ascending aorta or left ventricle, for example, to a pressure transducer that is connected to a proximal end of the pigtail catheter. Often the pigtail portion or adjacent distal region of the catheter shaft can be susceptible to kinking which, in combination with a smaller transmission lumen, can result in attenuated signal transmission leading to unreliable pressure gradients. Torqueability of the catheter shaft for distal positioning is also lacking.
The present inventors recognize that what is needed is a low-profile double lumen pigtail catheter that will accurately transmit pressure signals from a region both proximal and distal to a stenosis or narrowing to a proximal end of the catheter. When using such a pigtail catheter for measurement of a pressure gradient across a stenotic aortic valve, for example, the pigtail catheter should be able to transmit a highly accurate, non-attenuated, and frequency responsive pressure signal simultaneously from the LV and the ascending aorta to the proximal end of the catheter. The pigtail portion of the catheter should be resistant to kinking, have excellent torque transmission to the distal catheter shaft, have a biased distal catheter shaft bend, and/or optimal LV pigtail signal transmission. In some instances, the pigtail catheter should be able to be delivered to the LV over a low-profile diagnostic cardiology catheter, for example, that can be used to provide safer and less traumatic access across a stenotic aortic valve.
Measuring a pressure gradient across a stenotic intra LV cavity segment, such as hypertrophic obstructive cardiomyopathy (HOCM), can be difficult to accurately localize and measure proximal and distal pressures. A hypertrophic region of cardiac muscle can protrude from the proximal septal wall of the LV, for example, and extend into the left ventricular outflow tract (LVOT) adjacent to the anterior mitral valve leaflet. This protrusion can cause blood flow through the LVOT to have a higher velocity than normal, thereby producing a localized low-pressure region that can pull the anterior mitral leaflet toward the protrusion resulting in an even greater restriction to blood flow than that cause by the protrusion alone. The result is a dynamic pressure drop across the LVOT narrowing.
Typically, the hypertrophic segment of cardiac muscle can be treated surgically or ablated by transcatheter alcohol ablation. Intra LV pressures need to be discretely localized in segment proximal and distal to the dynamic obstruction. This is often made difficult by the short distance between the aortic valve and proximal segment of the septal hypertrophy, which need to be localized for proximal pressure measurement. Localizing the pressure to proximal to the LVOT gradient is especially relevant in patients that have combined HOCM and aortic stenosis. In the clinical scenario where there are two distinct systolic gradients, they need to be quantified separately to determine appropriate treatment strategies, such as HOCM septal ablation, TAVR, or both. In addition, patients with HOCM frequently have hyperdynamic LV systolic function that can result in distal cavity-end systolic collapse which can impinge on the distal orifice and impair accurate pressure measurement.
The present inventors recognize that what is needed is a gradient catheter having a coil with distal orifices or a distal opening located distal to the obstruction; the coil can have a small diameter and be shaped to prevent impingement of the distal orifices or distal opening. Proximal orifices located proximal to the obstruction should be accurately positioned in the proximal LVOT and distal to the aortic valve. Proximal and distal pressures can be measured simultaneously to quantitate the dynamic stenosis. The baseline gradient will determine the severity of the obstruction. The pressure gradient can be measured from a location within the LV to a location just below or adjacent to the aortic valve within the LVOT. The catheter should be able to place the proximal orifice proximal to the stenotic aortic leaflets within the aorta while maintaining the coil proximal to the dynamic obstructive segment in the LVOT without orifice blockage, thereby providing an ability to measure a separate end-systolic gradient across a stenotic aortic valve.
The present invention includes a pigtail catheter formed from a double lumen extrusion, for example, that does not have coaxial lumens. The double lumen tubing can provide two lumens having separate axes that run parallel to each other but are not coaxial. It is believed that this double lumen arrangement can provide a greater hydraulic diameter for each of the two lumens in comparison to a dual lumen catheter having coaxial lumens, thereby providing improved pressure signal transmission from a distal shaft segment to a manifold located at a proximal end of the pigtail catheter.
A proximal shaft segment, which includes the double lumen shaft tubing, can be braided to provide torque transmission characteristics to the distal shaft segment of the catheter. The catheter shaft can have a shaft bend in the axial direction of the LV thereby allowing the catheter to extend into the LV without impinging upon the LV inferior and septal segments, most notably, which could result in arrhythmic abnormalities that would render unreliable assessment of both pressure gradient and left ventricular systolic function. The distal shaft segment of the catheter adjacent to the pigtail coil can be supported by either braiding or an elastic member that resists kinking and provides torque transmission to the distal shaft segment, while preserving flexibility to the coil preventing trauma to submitral valve structures and having less resistance to wire exchanges.
The pigtail coil of a catheter embodiment can form a coil plane that is coplanar with a bend plane formed by the catheter shaft on the proximal and distal sides of the shaft bend; the coil plane can be directed toward the anterolateral left ventricular chamber by applying counterclockwise torque to the proximal portion of the catheter to optimize contrast opacification of the LV. In another embodiment, the pigtail catheter can form a coil plane that is not coplanar with the bend plane. The coil plane can be angled relative to the shaft bend plane to position the pigtail. In an embodiment, the distal pressure lumen can be sized and shaped to have a diameter that will allow passage of a low-profile diagnostic cardiology catheter that may be used to assist in delivery of a straight-tipped or other guidewire followed by a diagnostic catheter from the aorta to the LV across a stenotic aortic valve. Such diagnostic cardiology catheters may include Amplatz Left (AL), multipurpose catheters, right Judkins catheters, and other catheter configurations and will hereinafter be referred to as cardiac diagnostic catheters. Advancement of the pigtail catheter over the cardiac diagnostic catheter after first pulling the straight tipped crossing wire back into the diagnostic catheter can provide a less traumatic method, whereby the pigtail catheter uses the diagnostic catheter as a rail to deliver the pigtail catheter without a straight-tip guidewire freely exposed to the LV apex.
The pigtail catheter can undergo some specific modifications to provide a catheter to accurately measure a dynamic obstruction within the LV chamber present in hypertrophic obstructive cardiomyopathy (HOCM) in the LVOT secondary to a hypertrophic segment in the proximal LV septum. The HOCM pigtail catheter may have any of the features that are described for any embodiment of the cardiac pigtail catheter, including a braided shaft for various shaft regions to enhance torqueability and provide anti-kinking character, a double lumen shaft to enhance pressure signal transmission via two lumens of adequate hydraulic diameter within the double lumen shaft, a flexible coil located at the distal end of the pigtail catheter, orifices located along portions of the shaft or in the coil, a distal opening in the coil that has adequate diameter to allow passage over a guidewire and provide an opening for pressure signal transmission from the body chamber to the shaft lumen, orifice diameter that allow pressure signal transmission from the body chamber to the shaft lumen, and/or a shaft bend angle that positions the coil within the LV without eliciting ectopic signals from the myocardium which renders dynamic LVOT obstructions spurious.
The HOCM pigtail catheter of the present invention can have orifices and a distal opening that are protected from myocardial tissue impingement onto the orifices or distal opening during systolic contraction of the heart. Such systolic contraction can cause myocardial tissue to partially block the orifice or distal opening resulting in attenuated pressure signal transmission from the heart chamber to the shaft lumen resulting in an error in the pressure gradient measurement. Protection to the orifices can be obtained by placing the orifices on the innermost edge of the circular or oval shaped coil. The orifices can have an oval shape to enhance the area of the opening and make them harder for myocardial tissue to block signal transmission. The distal opening at the end of the coil can be protected by placing the distal opening near or abutting the proximally adjacent catheter shaft that can assist in holding myocardial tissue away from the distal opening. Since the distance from the hypertrophic cardiac muscle to the aortic valve can be short, about 5 mm (range of 2-10 mm), the proximal orifice region can contain only about one or two orifices such that the proximal orifice region can be accurately placed below the aortic annulus and proximal to the hypertrophic septal segment. A radiopaque marker can be located about 1 mm proximal to the proximal orifice region, for example, to allow the operator to visualize the location of the proximal orifice region under fluoroscopy.
A coil diameter for the HOCM pigtail catheter can be smaller in diameter with a diameter of 5 mm (range 3-10 mm, for example). The smaller coil diameter can better localize the pressure distal of the LVOT obstruction during the hyper dynamic systolic contraction generally seen in HOCM patients in the more distal LV chamber. To better avoid occlusion of the distal orifice by the myocardial tissue during systole, the post-bend region of the pigtail catheter can have a length of about 4 cm, for example, to maintain the coil at about 2-3 cm from the apex of the LV. A radiopaque marker located at the coil distal opening can aid in the accurate fixing of the catheter segment for measuring the distal pressure distal to the obstructive segment. Additionally, a radiopaque marker can be located near the proximal orifice that is positioned adjacent to the aortic valve in the LVOT.
The double lumen shaft of the present invention can alternately be formed without a braid contained within its outer wall. In an alternate embodiment, a fiber or ribbon can be placed into the outer shaft wall during the extrusion process or via other processing methods at a location close to the center of the oval proximal pressure lumen, for example. The presence of such a fiber or ribbon can enable and direct any bending incurred by the double lumen shaft such that the minor diameter of the oval proximal pressure lumen is not reduced. Thus, the fidelity of the pressure signal delivered by the proximal pressure lumen can be retained when the catheter shaft is being bent.
In another embodiment, the outer surface of the double lumen shaft can be formed with an oval shape. The outer major axis can be directed along a line extending through a center of the distal pressure lumen and through the center of the proximal pressure lumen. Such an oval outer surface shape can provide the proximal pressure lumen of the double lumen shaft to have a greater minor diameter than can be attained with a round double lumen shaft of the same perimeter and thereby maintain the perimeter of the outer surface of the double lumen shaft at a minimum. The oval double lumen shaft can pass through a smaller introducer catheter than a round double lumen shaft having the same minor diameter for the proximal pressure lumen. The result can be a greater pressure signal fidelity while passing the double lumen shaft through a smaller profile introducer sheath.
Several factors can affect the fidelity of the pressure signal that is transmitted back to the pressure transducer located at or near the manifold. Fluid resistance created by the viscosity of a fluid moving through a small diameter proximal pressure lumen, for example, can reduce the magnitude of the pressure signal that is transmitted to the pressure transducer. The hydraulic diameter of the proximal pressure lumen should therefore be maintained at a dimension of at least about 0.018 inches to ensure a fidelity signal transmission capability. A long tubing length can affect the inertia of the fluid moving through the catheter shaft and result in a phase delay of the pressure signal that is being transmitted back to the pressure transducer. Tubing compliance can cause the pressure signal to become attenuated, and phase delayed in reaching the pressure transducer. Such variables can be examined mathematically and chosen to optimize the fidelity of the signal that is transmitted from the proximal orifices to the proximal pressure lumen of the present double lumen catheter to the pressure transducer located at the manifold.
These and other examples, features and findings of the present catheters and related methods will be set forth, at least in part, in the following Detailed Description. This Summary is intended to provide non-limiting examples of the present teachings—it is not intended to provide an exclusive or exhaustive explanation. The Detailed Description below is included to provide further information about the present catheters and related methods.
The drawings illustrate generally, by way of example, but not by way of limitation, various embodiments discussed in this patent document.
The drawing figures are not necessarily to scale. Certain features and components may be shown exaggerated in scale or in schematic form, and some details may not be shown in the interest of clarity and conciseness.
While the pigtail catheters of the present invention can be used to measure a pressure gradient across a narrowing in a tubular member or chamber of the body, much of the following description will be focused on a cardiac pigtail catheter that is configured to measure a pressure gradient across a stenotic aortic valve.
Further, the pressure ports on the catheter manifold can be used alternately for intravascular contrast injection and thus provide opacification to define structure and function of a lumen, a chamber, or a valve. Contrast can be injected into the proximal pressure port and delivered via the proximal pressure lumen to exit the proximal orifices into a vascular lumen or a chamber proximal to a narrowing. Alternately, contrast can be injected into the distal pressure port and delivered via the distal pressure lumen to exit via the distal orifices or distal opening into a vascular lumen or a chamber distal to a narrowing. It is noted that when delivering contrast via the proximal or distal pressure port, back pressure generated via a syringe or other pressure generating device (for delivering contrast under pressure) is needed to create adequate flow of contrast to opacify a specific chamber. The back pressure can cause disengagement of the pressure port from the pressure generating device if the pressure lumen diameter or orifice diameter are not of a sufficient diameter or hydraulic diameter. The hydraulic diameter of the pressure lumens, in many examples, should be at approximately 0.020 inches (range 0.018-0.038 inches, for example) to ensure that contrast delivery does not generate excessive back pressure.
For the embodiment intended for measurement of pressure gradient across a stenotic aortic valve, for example, the distal shaft segment is configured to permit entry into a multitude of arterial and venous entry sites, for example, the femoral artery access site, and reside within the aorta and the LV such that the distal shaft segment extends across the narrowing or stenosis found in the tubular or chamber-like member of the body. The distal shaft segment can be conceptually divided into several regions, the proximal orifice region, the braided pre-bend region, the shaft bend, the braided post-bend region, the linear segment, and the coil region. The coil and adjacent flexible linear region contain only a single distal pressure lumen that can transmit a distal pressure signal from a body lumen distal to the narrowing to the distal pressure port located on the catheter manifold. The post-bend region extends from the shaft bend to the distal end of the pigtail catheter. Note that the proximal pressure lumen found in the proximal shaft segment can be easily removed from or not included within the distal shaft segment; the oval lateral wall of the proximal pressure lumen can be skived away, thermally removed, or otherwise rendered incapable of transmitting an accurate proximal pressure signal from the coil or the flexible linear region of the distal shaft segment.
As shown in
The shaft bend angle may not be required for other embodiments of the present invention, such as for pigtail catheters used for measuring a pressure gradient across narrowings in the vasculature or in tubular members of the body other than the narrowing (e.g., between the LV and the aorta across a stenotic aortic valve). The shaft bend forms a shaft bend plane with the braided pre-bend region and the braided post-bend region on each side of the shaft bend. The braided structure of the catheter shaft can extend distal to the shaft bend for 2.0 cm (range 0.5-4 cm, for example) to reach the distal end of the braided structure to provide adequate torque transmission capabilities from the proximal shaft segment to the distal shaft segment. The length of the catheter shaft distal to the shaft bend may not extend into the apex of the LV chamber to avoid potential for pre-ventricular contractions (PVC's).
The proximal shaft segment can have a braided structure applied to the lateral walls of the double lumen tubing; the braided structure can have about a 0.004-inch diameter metallic wire or polymeric fiber, for example. The braided structure can extend into various regions of the distal shaft segment to allow the operator to apply a torque to the catheter manifold and proximal shaft segment externalized outside of the body and transmit the torque to the distal shaft segment, including regions that are located distal to the shaft bend. The regions of the distal shaft segment that can be braided include the proximal orifice region, the braided pre-bend region, the shaft bend, the braided post-bend region, and distal orifice region, as shown in
One or more proximal orifices located in the pre-bend region about 3 cm (range 2-8 cm, for example) proximal to the shaft bend and above the sinotubular ridge of the aorta provide fluid communication and aortic pressure transmission from the aorta to the oval proximal pressure lumen and further signal transmission to the proximal pressure port, for example, located on the manifold. Positioning the proximal orifices above the sinotubular ridge and proximal to the shaft bend can avoid inaccurate measurement of the pressure gradient across a stenosis; such inaccurate measurement can result from lack of pressure recovery downstream of the stenosis due to placement of the proximal orifices too close to a vena-contracta jet associated with blood flow through stenotic valve leaflets. A pressure transducer connected to the proximal pressure port and distal pressure port of the manifold can simultaneously measure a pressure difference between the proximal pressure port and the distal pressure port thereby measuring a pressure gradient across the narrowing, for example, of an aortic valve or other stenosis found in the chambers of the heart or other vascular lumen, non-vascular lumen, or chambers of the body.
The proximal orifice holes can be located between openings of the braided structure, which provide individual braided fibers that are spaced apart (between fibers of the braided structure) to allow about four (range approximately 1-8, for example) 0.020-inch diameter (range 0.018-0.028 inches, for example) proximal orifices to be placed into the proximal shaft portion. The proximal orifice holes can be in fluid communication with an oval proximal pressure lumen, which can have a major diameter of about 0.035 inches and a minor diameter of about 0.016 inches; the hydraulic diameter of this oval or elliptical proximal pressure lumen can be about 0.020 inches (range 0.018-0.025 inches, for example) to ensure fully accurate transmission of the pressure signal from the aorta and accurate determination of the pressure gradient across the aortic valve. The hydraulic diameter for the oval proximal pressure lumen is determined from the equation: DH=(4BC(64−16E2))/((B−C)(64−3E4)), where 2B is the major diameter, 2C is the minor diameter, DH is the hydraulic diameter, and E=(B−C)/(B+C).
The double lumen shaft can be formed, for example, from polyurethane, Pebax (block copolymers composed of rigid polyamide blocks and soft polyether block and sold by Arkema), polyethylene, or other polymer that is extrudable, thermally reformable, and found in medical catheter devices; the polymer should be resilient and preferably soft enough such that properties of the double lumen shaft and single lumen shaft can be obtained (but not necessarily obtained) from a single shaft extrusion for both the double and single lumen shafts, if possible, with a thermal post-extrusion step to form the single lumen shaft. The double lumen shaft should at least allow thermal or other joining process to be performed, if necessary, to join the double lumen shaft to the single lumen shaft.
The double lumen shaft extends to a shaft junction distal to which the single lumen shaft extends distally containing a single (only one lumen that is able to provide adequate pressure transmission capabilities) distal pressure lumen that is able to provide adequate pressure transmission of a distal luminal pressure to a distal port located on the catheter manifold, as shown in
The flexible linear region can also have distal shaft orifices located just proximal to the floppy and more flexible pigtail coil which can be located on the single lumen shaft, and the distal orifices extend over an axial length of the single lumen shaft of about 1 cm (range 5-20 mm, for example). One or more distal orifices (about 4 orifices; range of approximately 1-6, for example) can extend within the coil and up to about 2 cm (range 1-4 cm, for example) adjacent and proximal to the coil and can be located within the coil; the orientation of the distal orifices should be circumferential around the catheter shaft both proximal to the coil and within the coil. The distal orifices have a diameter of about 0.020 inches (range 0.018-0.028 inches, for example) to provide adequate transmission of a pressure signal from the LV to the distal pressure port located on the manifold. The single lumen shaft can be formed from polyurethane, Pebax, polyethylene or other polymer that can be extruded and formed into a coil shape and retain its shape resiliently.
The distal coil should be soft enough to allow straightening of the pigtail coil and the distal shaft segment when passing over a guidewire and should be able to return to the coiled shape once the guidewire has been removed. The coil can be formed from a soft polymeric material that will unfold with a force of about 25 grams or less to ensure that cordae tendineae, for example, when entrapped by the coil are not stretched or torn. The coil can have a round shape, as shown in
As shown in
When the pigtail catheter of the present invention is used to measure a pressure gradient across the aortic valve, for example, as shown in
Alternately, as shown in
To form such a catheter shaft, the skiving of the oval lateral wall of the oval proximal pressure lumen can occur prior to placement of a braid over both the double lumen shaft and single lumen shaft. Axial extension of the braided structure in the single lumen shaft would place the braided structure into intimate contact with the wall of the single lumen shaft. Subsequent thermal reflow of the braided material into the outer wall of the catheters shaft by application of heat and an outer shrink wrap that applies an inward force onto the braided structure, and further by protecting the proximal pressure lumen and distal pressure lumen with shaped mandrels (that match the lumen shapes), such as Teflon (a synthetic fluoropolymer of tetrafluoroethylene made by Chemours) mandrels, for example, can form the braided catheter shaft. The reflow of polymer shaft material can allow the braid to penetrate the circular lateral wall and oval lateral wall of the double lumen shaft and allow penetration into the circular lateral wall and common wall of the double lumen shaft, as shown in
Even further alternately, as shown in
To form this distal shaft portion, a braid can be located only within the double lumen shaft, as shown in
A standard procedure for advancing a straight-tip guidewire and diagnostic cardiology catheter across a stenotic aortic valve is described along with its limitations. One diagnostic cardiology catheter, for example, that is currently being used to deliver a straight-tip guidewire, for example, from the aorta to the LV across a stenotic aortic valve is a single lumen Amplatz Left (AL) catheter such as that shown in
It should be noted that the cardiac diagnostic catheter can have a distal end configuration which has a tip generally pointed toward the LV apex. This configuration may result in a straight-tip wire being inadvertently forcefully advanced into the LV apex when advancing the cardiac diagnostic catheter into the LV resulting in perforation. The circular lumen of a pigtail embodiment of the present invention can accommodate a low profile cardiac diagnostic catheter, which can be used to exchange the pigtail catheter mitigating the risk of exchange of catheters over the straight tip guidewire only.
As shown in
The pigtail catheter can have a distal lumen diameter of 0.052 inches (range 0.045-0.060 inches), for example, to accommodate passage of a 4 F cardiac diagnostic catheter (range 3.5 F-4.5 F, for example); the pigtail catheter can be formed with an overall profile of 8F while maintaining hydraulic diameters for the proximal and distal lumens greater than or equal to 0.018 inches and providing highly accurate pressure signal transmission. Alternately, the pigtail catheter can have a distal lumen diameter of 0.069 inches (range 0.065-0.075 inches), for example, to accommodate passage of a 5 F cardiac diagnostic catheter (range 4.5 F-5.5 F, for example) that is able to follow over a 0.032-inch guidewire, for example; the pigtail catheter can be formed with an overall profile of 9-10 F while maintaining hydraulic diameters for the proximal and distal lumens greater than 0.018 inches and providing highly accurate pressure signal transmission. Further alternately, the pigtail catheter of the present invention can track directly over a 0.035-inch guidewire with a profile for the pigtail catheter of 7 F-8 F and with highly accurate pressure signal transmission.
A J-tipped guidewire can be advanced leading a cardiac diagnostic catheter via a vascular access sheath and advanced into the aortic root. A straight-tip guidewire can then be exchanged for the J-tipped guidewire to be advanced across the stenotic aortic valve and advanced into the LV.
The coil can have a coil diameter of about 5 cm (range 3-8 cm, for example) which is smaller than the coil diameter for other cardiac pigtail catheter coils of the present invention. The smaller 5 mm coil diameter is better suited to not interfere with the systolic contraction of the LV in a HOCM patient that often has direct contact of the LV opposing walls near the LV apex during systolic contraction. During systolic LV contraction, the orifices located along the coil, or the distal opening found at the end of the coil can be blocked by the myocardial tissue. Normally such a distal opening can have a diameter of 0.038 inches (range 0.025-0.040 inches, for example) to allow passage of a guide wire and to allow transmission of pressure signal to the distal lumen of the pigtail catheter. Such orifice or distal opening blockage can result in diminution of the pressure signal that is normally transmitted through the orifices or distal opening to the distal lumen of the pigtail catheter shaft. This reduced pressure signal can result in an inaccurate measurement of the pressure within the LV. As shown in
Orifices can also be placed at other locations along the coil of the HOCM pigtail catheter, as shown in
The profile of such a HOCM pigtail catheter that has a distal lumen able to follow a 0.035 guidewire and provide a proximal and distal pressure lumen with a hydraulic diameter of at least 0.018 inches (to provide accurate pressure signal transmission through the proximal and distal pressure lumens) is about 6 F-7 F.
About one or two proximal orifices are placed along the distal shaft segment at a location at or about 1 mm below a radiopaque marker that is placed at the shaft bend. The proximal orifice is intended to measure the pressure at a location between the aortic annulus (or stenotic aortic leaflets) and the hypertrophic cardiac muscle which can be separated by only 5 mm (range 3-8 mm, for example). A single orifice or two orifices positioned at this location cannot extend either downstream past the stenotic native leaflets or upstream from the hypertrophic proximal muscle and therefor this proximal orifice region cannot extend over more than 2 mm.
During measurement of the pressure gradient from the LV across the hypertrophic proximal muscle, the proximal orifice region can be positioned between the aortic valve and the hypertrophic cardiac muscle, and the coil can be positioned about 2-3 cm into the LV chamber from the LV apex; this positioning avoids excessive compression of the HOCM pigtail coil by systolic compression near the LV apex. The HOCM pigtail catheter can also be repositioned such that the proximal orifice region is located downstream of potentially stenotic aortic valve leaflets in the ascending aorta, as shown in
A second shaft bend can be placed into the pigtail catheter shaft thereby providing a proximal shaft bend with a proximal bend angle and a distal shaft bend with a distal bend angle, as shown in
In an alternate embodiment, a circular lateral wall fiber can be place into the circular lateral wall in addition to the oval lateral wall fiber. The circular lateral wall fiber can be placed into the circular lateral wall at a location in line with the distal pressure lumen center and proximal pressure lumen center. The circular lateral wall fiber can be formed into the circular lateral wall during the extrusion process or can be formed via an alternate post processing method. The circular lateral wall fiber can have the same material and dimensional characteristics as the oval lateral wall fiber. The presence of both the circular lateral wall fiber and the oval lateral wall fiber ensures that the double lumen shaft will bend along a plane that is perpendicular to a line that joins the circular lateral wall fiber with the oval lateral wall fiber.
Other methods of placing either the oval lateral wall fiber or the circular lateral wall fiber have been contemplated; an oval lateral wall fiber can be inserted, for example, within a proximal pressure lumen and attached at a desired location along the luminal surface of the proximal pressure lumen via an adhesive, thermal bonding method, or other attachment methods. The oval lateral wall fiber can alternately be attached along the outside of the outer wall to provide similar bending characteristics to the double lumen shaft.
The oval double lumen shaft tends to bend in a plane that is perpendicular to the major axis. The double lumen shaft is often subjected to bending as it extends along its pathway within the body; bending of the double lumen shaft will cause the proximal pressure lumen to enlarge in a direction along the proximal lumen minor axis. Hence the proximal pressure lumen can be formed with an oval shape with the proximal lumen major axis being larger than the proximal lumen minor axis that extends in-line with the catheter shaft major axis. Bending of the double lumen shaft will then result in enlarging the proximal lumen minor axis and will result in enhanced fidelity of transmitted signal as the proximal pressure lumen becomes more rounded and results in a larger hydraulic diameter. The presence of an oval lateral wall fiber or circular lateral wall fiber can be applied to the oval double lumen shaft at locations like that described for the round double lumen shaft to enhance the tendency for the double lumen shaft to bend in a plane that is perpendicular to the shaft major axis.
The equation that describes flow within the proximal pressure lumen as a function of time has two components, a natural component and a forced component that depends upon the nature of the pressure signal being generated by the heart. The natural component describes the natural frequency of the system which includes the double lumen shaft, the shaft compliance, shaft length, and proximal lumen hydraulic diameter. The natural frequency of the system, fo, is described by:
fo=(½Pi)(R2−(4L/C))1/2
In constructing the double lumen shaft of the present invention, one desires fo to be larger than about 40 Hz. If R2>4L/C the system is overdamped, and the transmitted signal delivered to the manifold can be of a smaller amplitude than the actual signal and higher frequency signals being generated by the heart can be missed. If R2<4LC, the system is underdamped, and the transmitted signal can have “ringing” and thereby transmitting signals that are not being generated by the heart but are associated with the natural frequency of the system. The double lumen shaft of the present invention is designed to deliver a critically damped signal along the proximal pressure lumen by setting R2=4L/C. The hydraulic diameter (i.e., two-time R) is one of the most demonstrative factors that determines the ability of the double lumen shaft of the present invention to transmit signals accurately and with fidelity to the pressure transducer located at the manifold. The hydraulic radius of the proximal pressure lumen is equal to (4L/C)1/2.
The present catheter designs provides advantages to existing designs. For example, on a safety front, two lumens contained within a single extrusion cannot be separated by power injection force. The present design offers the opportunity to eliminate the risk of component embolism. Also on a safety front, a single extrusion design can reduce or eliminate dead spaces in a proximal shaft segment of the catheter, thereby simplifying flush preparation and reducing risk of air embolization. On an efficacy front, the single, relatively rigid extrusion containing independent, non-coaxial lumens can overcome the potential for either lumen to be obstructed due to relative movement of one catheter component within the other. The non-coaxial lumen design can also overcome high shear forces inherent to coaxial designs, which has implications for both signal fidelity and injection flow rates.
In the drawings, like numerals can be used to describe similar features and components throughout the several views.
The above Detailed Description includes references to the accompanying drawings, which form a part of the Detailed Description. The Detailed Description should be read with reference to the drawings. The drawings show, by way of illustration, specific embodiments in which the present catheters and related methods can be practiced. These embodiments are also referred to herein as “examples.” The use of “adapted to,” “configured to,” or similar herein is meant as open and inclusive language that does not foreclose devices or components adapted to or configured to perform additional functions. The use of “proximal” and “distal” herein refer to relative positions with respect to a user of the elongate, minimally invasive devices, where “proximal” means relatively towards the user and “distal” means relatively away from the user. Headings, lists, and numbering included herein are for ease of explanation only and are not meant to be limiting. All numeric values are assumed to be modified by the term “about,” whether or not explicitly indicated. The term “about” generally refers to a range of numbers that one of ordinary skill would consider equivalent to the recited value (e.g., having the same function or result). In many instances, the term “about” can include numbers that are rounded to the nearest significant figure. The recitation of numerical ranges by endpoints includes all numbers and sub-ranges within and bounding that range (e.g., 1 to 4 includes 1, 1.5, 1.75, 2, 2.3, 2.6, 2.9, etc. and 1 to 1.5, 1 to 2, 1 to 3, 2 to 3.5, 2 to 4, 3 to 4, etc.).
The Detailed Description is intended to be illustrative and not restrictive. For example, the above-described examples (or one or more features or components thereof) can be used in combination with each other. Other embodiments can be used, such as by one of ordinary skill in the art upon reviewing the above Detailed Description. Also, various features or components have been or can be grouped together to streamline the disclosure. This should not be interpreted as intending that an unclaimed disclosed feature is essential to any claim. Rather, inventive subject matter can lie in less than all features of a particular disclosed embodiment. Thus, the following claim examples are hereby incorporated into the Detailed Description, with each example standing on its own as a separate embodiment:
In Example 1, a pigtail catheter configured to measure a pressure proximal and distal to a narrowing can comprise a proximal shaft segment and a distal shaft segment. The proximal shaft segment can include double lumen tubing defining a proximal pressure lumen and a non-coaxial, distal pressure lumen. The distal shaft segment can be configured to be partially positioned across the narrowing and has a portion that includes the distal pressure lumen but not the proximal pressure lumen. The distal shaft segment can include at least one distal orifice positionable distal to the narrowing and having a diameter of at least about 0.018 inches, and at least one proximal orifice positionable proximal to the narrowing and having a diameter of at least about 0.018 inches.
In Example 2, the pigtail catheter of Example 1 can optionally be configured such that the distal pressure lumen has a generally circular cross-sectional shape, and the proximal pressure lumen has a generally crescent or kidney cross-sectional shape that wraps partially around the distal pressure lumen.
In Example 3, the pigtail catheter of any one of Examples 1 or 2 can optionally further comprise a manifold coupled to a proximal end of the proximal shaft segment. The manifold can include a proximal pressure port in fluid communication with the proximal pressure lumen and a distal pressure port in fluid communication with the distal pressure lumen.
In Example 4, the pigtail catheter of Example 3 can optionally be configured such that the manifold is configured to deliver a proximal pressure signal and a distal pressure signal to a transducer for determination of a pressure gradient across the narrowing.
In Example 5, the pigtail catheter of any one or any combination of Examples 1-5 is optionally configured such that the proximal shaft segment includes a braided structure contained within an outer wall of the double lumen tubing.
In Example 6, the pigtail catheter of Example 5 is optionally configured such that the braided structure comprises metallic or polymeric fibers having a spacing of at least about 0.020 inches to allow for placement of a proximal orifice therebetween.
In Example 7, the pigtail catheter of any one of Examples 5 or 6 is optionally configured such that the braided structure extends to a portion of the distal shaft segment.
In Example 8, the pigtail catheter of any one or any combination of Examples 1-7 is optionally configured such that an outer wall of the double lumen tubing comprises a first wall fiber adjacent to the proximal pressure lumen. The first wall fiber can extend in an axial direction and have a non-extensional characteristic.
In Example 9, the pigtail catheter of Example 8 is optionally configured such that the outer wall of the double lumen tubing comprises a second wall fiber adjacent to the distal pressure lumen. The second wall fiber can extend in an axial direction and have a non-extensional characteristic.
In Example 10, the pigtail catheter of any one or any combination of Examples 1-10 can optionally be configured such that an outer surface of the double lumen tubing has an oval cross-sectional shape defining a shaft major axis and a shaft minor axis, and a center of the distal pressure lumen and a center of the proximal pressure lumen are located on the shaft major axis.
In Example 11, the pigtail catheter of Example 10 can optionally be configured such that the outer surface has a shaft minor length that is at least ten percent (10%) less than a shaft major length.
In Example 12, the pigtail catheter of any one or any combination of Examples 1-11 optionally further comprises an elastic member positioned within a distal portion of the proximal pressure lumen and forming an attachment to the distal shaft segment.
In Example 13, the pigtail catheter of Example 12 is optionally configured such that the elastic member extends along a length of the distal shaft segment, including a pigtail coil at the end of the distal shaft segment.
In Example 14, the pigtail catheter of any one or any combination of Examples 1-13 is optionally configured such that the distal shaft segment includes a shaft bend distal to the at least one proximal orifice.
In Example 15, the pigtail catheter of Example 14 is optionally configured such that the shaft bend forms a shaft bend angle ranging from about 145 degrees to about 165 degrees, inclusive.
In Example 16, the pigtail catheter of any one or any combination of Examples 1-15 is optionally configured such that the distal shaft segment includes a pigtail coil having a diameter less than or equal to about 1.5 cm.
In Example 17, the pigtail catheter of Example 16 is optionally configured such that a plane of the pigtail coil is non-coplanar with a plane of a shaft bend located in the distal shaft segment, distal to the at least one proximal orifice.
In Example 18, the pigtail catheter of Example 17 is optionally configured such that the plane of the pigtail coil is angled about 5 degrees to about 45 degrees, inclusive, relative to the plane of the shaft bend.
In Example 19, the pigtail catheter of any one or any combination of Examples 16-18 is optionally configured such that the pigtail coil includes a coil apex at a distal-most coil portion. The distal-most coil portion can have a radius of curvature that is less than a radius of curvature of the remaining portions of the pigtail coil.
In Example 20, the pigtail catheter of any one or any combination of Examples 16-19 is optionally configured such that the pigtail coil includes a coil apex at a distal-most coil portion. A radiopaque marker can be positioned at the coil apex.
In Example 21, the pigtail catheter of any one or any combination of Examples 1-20 is optionally configured such that one or both of the proximal pressure lumen and the distal pressure lumen has a hydraulic diameter of about least about 0.018 inches.
In Example 22, a method can comprise inserting a pigtail catheter into a heart such that a distal shaft segment of the catheter is partially positioned in a left ventricle and determining a pressure gradient across an aortic valve. A proximal shaft segment of the catheter can include double lumen tubing defining a distal pressure lumen having a generally circular cross-sectional shape and a proximal pressure lumen having a generally crescent or kidney cross-sectional shape that wraps partially around the distal pressure lumen. The distal shaft segment can include a portion that includes the distal pressure lumen but not the proximal pressure lumen, at least one proximal orifice positioned proximal to an aortic valve, and at least one distal orifice positioned distal to the aortic valve. Determining the pressure gradient across the aortic valve can include coupling a pressure transducer to a manifold of the pigtail catheter. The manifold can include a proximal pressure port in communication with the proximal pressure lumen and a distal pressure port in communication with the distal pressure lumen.
In Example 23, the method of Example 22 can optionally be configured such that inserting the pigtail catheter into the heart includes inserting the pigtail catheter over a cardiac diagnostic catheter using the distal pressure lumen.
In Example 24, the method of Example 23 can optionally further comprise removing the cardiac diagnostic catheter from the distal pressure lumen.
In Example 25, the method of any one of Examples 22-24 can optionally be configured such that one or both of the proximal pressure lumen and the distal pressure lumen include a hydraulic diameter of at least about 0.018 inches.
The scope of the present catheter and related methods should be determined with reference to the appended claims, along with the full scope of equivalents to which such claims are entitled. In the appended claims, the terms “including” and “in which” are used as the plain-English equivalents of the respective terms “comprising” and “wherein.” Also in the following claims, the terms “including” and “comprising” are open-ended; that is, a catheter or method that includes features, components, or steps in addition to those listed after such a term in a claim are still deemed to fall within the scope of that claim. Moreover, the terms “first,” “second,” “third,” etc. in the following claims are used merely as labels, and such terms not intended to impose numerical requirements on their objects.
The Abstract is provided to allow the reader to quickly ascertain the nature of the technical disclosure. It is submitted with the understanding that it will not be used to interpret or limit the scope or meaning of the claims.
This non-provisional patent document claims the benefit of priority under 35 U.S.C. § 119(e) to Pedersen et al., U.S. Provisional Patent Application Ser. No. 63/229,693, entitled “DOUBLE LUMEN PIGTAIL CATHETER AND HOCM GRADIENT CATHETER” and filed on Aug. 5, 2021, which is herein incorporated by reference in its entirety.
| Number | Date | Country | |
|---|---|---|---|
| 63229693 | Aug 2021 | US |
