Intra-aortic balloon pump assembly

Abstract

The blood pump assembly includes a balloon defining an elongated inflatable chamber with an opening at its proximal end. The proximal region of the balloon is substantially cylindrically conical and tapered toward the proximal end of the balloon, and the central region of the balloon is substantially cylindrical with a substantially uniform outer diameter. The distal region of the balloon is substantially cylindrically conical and tapered toward the distal end of the balloon. The length of the distal region of the balloon is greater than about 15% of the combined length of the proximal and central regions of the balloon. The drive system may have a connecting element coupleable to the opening and disposed at the proximal end of the drive system. A radiopaque marker may be integrated into the drive system at the distal end of the drive system.

Description

[Technical Field]

[0001] The present technology relates to mechanical circulatory assist devices, and more particularly to blood pump assemblies and related devices, systems, and methods. [Background technology]

[0002] The prevalence of heart failure (HF) is increasing worldwide, representing an expensive burden for healthcare providers. Despite medical advances, the prognosis for HF remains poor, especially in advanced stages. Heart transplantation remains limited by the supply of donor organs. The use of left ventricular assist devices (LVADs) has stagnated at approximately 5,000 transplants per year due, among other reasons, to the need for major surgical intervention and the use of cardiopulmonary bypass (CPB). Additionally, the high cost of these devices has prevented their adoption in a large potential market, with some countries deciding not to fund routine LVAD use.

[0003] Globally, the most common assist device for acute heart failure is the intra-aortic balloon pump (IABP), which is used clinically for limited periods of time, from a few hours to a few days. The IABP (also referred to herein as a "blood pump," "balloon," or "expandable member") is part of an IABP assembly, which includes a drive system with two ends. One end is connectable to the IABP, and the other end is connectable, often indirectly, to an external drive unit. The drive unit is a source of working fluid (e.g., ambient air or helium), which is delivered to the IABP via the drive system for inflation. The drive unit is also responsible for deflation of the working fluid from the IABP via the drive system. More than 150,000 patients worldwide receive IABP therapy each year. IABPs are much simpler than current LVADs, and the therapeutic benefits of counterpulsation therapy are well established. Counterpulsation does not require direct cannulation of the heart, resulting in easier implantation and explantation. Counterpulsation therapy is also less expensive than LVAD therapy.

[0004] Counterpulsation therapy is achieved by rapidly inflating the balloon (diplocarpon) immediately after aortic valve closure and rapidly deflating the balloon just before the onset of systole. Diplocarpon can be detected using a pressure sensor located at the tip of the IABP, and the onset of systole can be detected using an electrocardiogram (ECG). However, both inflation and deflation are triggered by either the pressure sensor or ECG data. An example of an IABP with a pressure sensor located at the tip is the Arrow Ultra 8 Fiber-Optic IAB Catheter manufactured by Teleflex. Rapid inflation of the balloon increases aortic pressure during diastole by 20% to 70%, improving end-organ and coronary perfusion. Rapid deflation of the balloon reduces native ventricular ejection pressure, reducing afterload and left ventricular external work. Counterpulsation therapy has been shown to be most effective in patients with a systolic aortic pressure between 40 mmHg and 70 mmHg, a native heart rate between 80 bpm and 110 bpm, and a counterpulsation volume (i.e., balloon volume) equal to the native left ventricular stroke volume.

[0005] IABPs are used in HF patients awaiting transplantation and in patients undergoing coronary artery bypass surgery. The balloon is typically implanted in the descending aorta with a drive system extending through the femoral artery. This implantation is sometimes referred to herein as "femoral implantation," and the process leading to femoral implantation is sometimes referred to herein as the "femoral technique." The femoral technique is simpler for the implanting clinician because there are no significant arterial twists or curvatures to work with. However, IABPs implanted via the femoral technique require the patient to remain supine during treatment with their legs immobilized because (1) changes in posture have been shown to reduce the effectiveness of treatment, (2) walking can cause the balloon or balloon drive system to twist due to leg movement, which leads to cyclical fatigue and eventual failure of the balloon assembly, and (3) walking increases the risk of arterial access bleeding within the femoral artery. As a result, patients are unable to ambulate or benefit from IABPs as long-term therapy for myocardial support. Lack of ambulation has been demonstrated to result in poorer outcomes and prolong patient recovery and hospital stays. Issues with arterial access, biocompatibility, and durability limit the use of IABPs to short periods of time (typically 2 to 4 days). While IABP supports have been used for long periods, the incidence of vascular complications, infections, and bleeding is high.

[0006] More recently, IABPs have been implanted in the descending aorta with the drivetrain extending through the axillary / subclavian arteries. This implantation is sometimes referred to as "axillary implantation," and the process leading to axillary implantation is sometimes referred to as the "axillary technique." When an IABP is implanted using the axillary technique, certain mobility issues associated with femoral implantation are alleviated, facilitating patient ambulation. However, with axillary implantation, the natural buoyancy of the balloon when inflated can cause it to flex, subjecting it to periodic fatigue and failure. Axillary implantation is typically performed surgically by entering the chest and making an incision down to the axillary / subclavian arteries.

[0007] Current IABPs are not optimally sized. They are either too small for effective treatment, or too long, wide, or otherwise awkward, resulting in the IABP occluding the aorta itself or branch vessels. Furthermore, current IABPs are not designed to navigate the twists and turns of the aorta from the axillary artery to the thoracic aorta. In particular, conventional IABPs have rigid, unreinforced drive systems. Similarly, drive systems typically cannot withstand the forces typical of pulling a delivery dilator connected to an IABP drive system through the vasculature. This can lead to increased balloon malfunction, drive system kinking, and other adverse events when performing IABP delivery to the axilla. These adverse events have been reported to be as high as 30% in clinical trials and include increased rates of balloon exchange and repositioning, bleeding, pseudoaneurysm, arterial dissection / injury, and hematoma. Finally, radiopaque materials are typically added to the outer surface of the drive system to provide markers for proper placement of the balloon / drive system within the vasculature. However, adding such material to the exterior surface of the drive system can create undesirable air pockets within the vasculature, making it more difficult to thread the drive system through an introducer sheath for placement of the IABP (or conversely, requiring a larger size introducer sheath than would otherwise be needed). [Brief explanation of the drawings]

[0008] Many aspects of the present technology can be better understood with reference to the following drawings. The components in the drawings are not necessarily to scale, emphasis instead being placed upon clearly illustrating the principles of the present disclosure.

[0009] [Figure 1] FIG. 1 illustrates an embodiment of an IABP assembly implanted in the aortic arch vasculature according to an embodiment of the PiVAS technology. [Figure 2A] FIG. 2A illustrates various stages of an exemplary procedure for intravascularly implanting an IABP assembly into a patient's vasculature that may be useful in the present disclosure. [Figure 2B]FIG. 2B illustrates various stages of an exemplary procedure for intravascularly implanting an IABP assembly into a patient's vasculature that may be useful in the present disclosure. [Figure 2C] FIG. 2C illustrates various stages of an exemplary procedure for intravascularly implanting an IABP assembly into a patient's vasculature that may be useful in the present disclosure. [Figure 2D] FIG. 2D illustrates various stages of an exemplary procedure for intravascularly implanting an IABP assembly into a patient's vasculature that may be useful in the present disclosure. [Figure 3A] FIG. 3A illustrates various exemplary features of an elongate delivery dilator that may be useful in the present disclosure. [Figure 3B] FIG. 3B illustrates various exemplary features of an elongate delivery dilator that may be useful in the present disclosure. [Figure 3C] FIG. 3C illustrates various exemplary features of an elongate delivery dilator that may be useful in the present disclosure. [Figure 4A] FIG. 4A illustrates various features of a drivetrain 116 that may be useful in the present disclosure. [Figure 4B] FIG. 4B illustrates various features of drivetrain 116 that may be useful in the present disclosure. [Figure 4C] FIG. 4C illustrates various features of drivetrain 116 that may be useful in the present disclosure. [Figure 5] FIG. 5 illustrates an exemplary top view of a balloon pump assembly according to an embodiment of the present disclosure. [Figure 6] FIG. 6 illustrates an exemplary enlarged view of a region 600 of the balloon pump assembly of FIG. [Figure 7A] FIG. 7A shows an exemplary plan view of the balloon of FIG. [Figure 7B] FIG. 7B shows an exemplary cross-sectional view of the balloon of FIG. 7A taken at section line 702 and looking toward the proximal region of the balloon. [Figure 8] FIG. 8 shows an exemplary plan view of the drive train of FIG. [Figure 9] FIG. 9 shows an exemplary cross-section of the drivetrain of FIG. 8 taken at section line 802 and looking toward the distal region of the drivetrain. [Figure 10] FIG. 10 shows an exemplary longitudinal cross section of the drivetrain of FIG. 5 taken at the proximal end of the drivetrain. [Figure 11] FIG. 11 shows another exemplary longitudinal cross section of the drivetrain of FIG. 5 taken at the proximal end of the drivetrain. [Figure 12] FIG. 12 shows an exemplary longitudinal cross section of the drivetrain of FIG. 5 taken at the distal end of the drivetrain. [Figure 13A] FIG. 13A shows a top view of the balloon pump assembly of FIG. 5 with various exemplary support structures embedded within the balloon. [Figure 13B] FIG. 13B shows a top view of the balloon pump assembly of FIG. 5 with various exemplary support structures embedded within the balloon. [Figure 14] FIG. 14 shows a top view of the balloon pump assembly of FIG. 5 with various exemplary support structures embedded within the balloon. [Figure 15] FIG. 15 shows a top view of the balloon pump assembly of FIG. 5 with various exemplary support structures embedded within the balloon. DETAILED DESCRIPTION OF THE INVENTION

[0010] Specific details of several embodiments of the present technology are described herein with reference to FIGS. 1 through 15. Other applications and other embodiments in addition to those described herein are within the scope of the present technology. It should be noted that other embodiments in addition to those disclosed herein are also within the scope of the present technology. Furthermore, those skilled in the art will understand that embodiments of the present technology may have configurations, components, and / or procedures in addition to those shown or described herein, and that these and other embodiments may be without some of the configurations, components, and / or procedures shown or described herein without departing from the present technology. Throughout this specification, reference to “one embodiment,” “one embodiment,” “one or more embodiments,” “nth embodiment,” “some embodiments,” or phrases of similar effect means that a particular feature, structure, or characteristic described in connection with an embodiment is included in at least one embodiment of the present disclosure. Thus, use of such terms does not necessarily refer to the same embodiment. For example, it is expressly contemplated that features described herein may be combined in any suitable manner in one or more embodiments.

[0011] Related technologies The present applicant / assignee, NuPulseCV, Inc. of Raleigh, North Carolina, has developed a percutaneously delivered intravascular ventricular assist system (PiVAS) that functions as a chronic counterpulsation device as generally described in U.S. Patent Application No. 16 / 876,110, the contents of which are incorporated herein by reference in their entirety. The PiVAS includes an expandable member that is implanted in the descending aorta via a modified axillary technique using minimally invasive surgical techniques. Once implanted, the drive system of the PiVAS extends through the axillary or subclavian artery. The PiVAS offers an alternative therapy for HF patients by providing partial circulatory support that can be minimally invasively implanted without entering the chest and does not require cardiopulmonary bypass (CPB) or blood products.

[0012] NuPulseCV also relates to (1) an IABP assembly having one or more sensors (sensor technology) generally as described in U.S. patent application Ser. No. 09 / 109,499, filed on the same date as this disclosure, entitled "Intra-Aortic Balloon Pump Assembly With Pressure Sensor," identifying Joshua Ryan Woolley, Sonna Manubhai Patel-Raman, and Guruprasad Anapathur Giridharan as inventors, and attorney docket number 8018US00 / 236533-30034; and (2) an IABP assembly having one or more sensors (sensor technology) generally as described in U.S. patent application Ser. No. 09 / 109,499, filed on the same date as this disclosure, entitled "Intra-Aortic Balloon Pump Assembly With Pressure Sensor," identifying Joshua Ryan Woolley, Sonna Manubhai Patel-Raman, and Guruprasad Anapathur Giridharan as inventors, and attorney docket number 8018US00 / 236533-30034. The present inventors have developed a blood pump support structure for a blood pump assembly (blood pump support structure technology) as generally described in U.S. patent application Ser. No. 09 / 2009,599, filed Sept. 2, 2009, and assigned to the Attorney Docket No. 8020US00 / 236533-30035, the contents of both of which are incorporated by reference herein in their entireties. The sensor technology, among other issues, addresses particular challenges associated with implanting an IABP assembly in the axilla using a pressure sensor located at the tip (or distal end) of the IABP, and the blood pump support structure technology, among other issues, addresses particular challenges associated with blood pumps being rotated, folded, or otherwise developing gaps during surgery (e.g., when positioned within the descending aorta).

[0013] FIG. 1 illustrates an embodiment of an IABP assembly implanted in an aortic arch vasculature 100 in accordance with an embodiment of the PiVAS technology. The aortic arch vasculature 100 includes a heart 102, an aortic arch 104, an axillary / subclavian artery 106, a thoracic aorta 108, an abdominal aorta 109 (collectively referred to as the thoracic aorta 108 and the descending aorta 108, 109), two branches of the renal arteries 110, and two branches of the common iliac arteries 112. The thoracic aorta 108 originates approximately at the axillary / subclavian artery 106 and extends approximately to the abdomen. The abdominal aorta 109 originates approximately at the abdomen and extends approximately to the two branches of the common iliac arteries 112. The IABP assembly can include an IABP or balloon 114 and a drive system 116, with the balloon 114 positioned within the thoracic aorta 108. The balloon 114 can include a marker 118 disposed at a distal end 120 of the balloon 114, the marker 118 being made of a radiopaque material suitable for tracking the position of the balloon 114 during radiological intervention (e.g., with x-ray or fluoroscopy).

[0014] In one embodiment, the balloon 114 may be a pneumatically-driven expandable member defining an elongated inflatable chamber, and the balloon 114 is designed for long-term biocompatibility and safety. A proximal end 122 of the balloon 114 may be coupled to a distal end 124 of the drive system 116. In one embodiment, the proximal end 122 of the balloon 114 includes an engagement region sized and shaped to fit over the distal end 124 of the drive system 116. The balloon 114 may be coupled to the drive system 116 using an attachment mechanism such as a compression ring or other suitable element that provides an airtight connection / pneumatic seal between the engagement region and the drive system. The proximal end of the drive system 116 may be coupled to a drive unit (e.g., an external driver), not shown.

[0015] Balloon 114 may be constructed from a biocompatible, non-thrombogenic elastomeric material (e.g., Biospan®-S) or other suitable material and may have the features described in U.S. Pat. No. 8,066,628, the disclosure of which is incorporated herein by reference in its entirety. In one embodiment, maximum device displacement volume can be closely matched to the cardiac stroke volume, a parameter that can be varied to provide effective counterpulsation therapy. Balloon 114 may have a displacement volume of about 20 ml to about 60 ml. In some embodiments, the displacement volume is about 50 ml. Balloon 114 may have a length of about 15 cm to about 30 cm.

[0016] The balloon may be placed within the descending aorta 108, 109 (e.g., the thoracic aorta 108) via a modified axillary technique, and once implanted, the drivetrain 116 extends through the axillary / subclavian artery 106. As described below, an arterial-skin interface / stopper device may be utilized to enable long-term implantation using minimally invasive surgical techniques. The balloon 114 may be non-occlusive and, when deflated, may lie at least substantially flat within the thoracic aorta 108 without folds or gaps. This allows the device (e.g., an IABP assembly or PiVAS system) to be turned off for extended periods of time; for example, a patient may routinely turn the device off for 60 minutes or more without adverse consequences, and the balloon 114 may be durable for over 2.5 years of use.

[0017] The drive system 116 may be a thin (e.g., 4.2 mm outer diameter) drive system that shuttles a working fluid (e.g., air, gas, etc.) between the balloon 114 and a drive unit (not shown) via a lumen ( FIG. 4B , element 404). The relatively small diameter of the drive system 116 compared to the relatively large axillary / subclavian artery 106 reduces the risk of limb ischemia. The drive system 116 may include an inner drive system and an outer drive system. The inner drive system may be an elongated support structure having a lumen extending therethrough for delivering working fluid to and from the balloon 114. The inner drive system may be at least partially disposed within the patient's vasculature (e.g., between the aorta and the axillary / subclavian artery). After implantation, the inner drive system may have a distal end portion 124 coupled to the balloon 114 and positioned within the patient's vasculature (e.g., the thoracic aorta 108), and a proximal end portion coupled to the outer drive system and positioned outside the patient's vasculature, for example, at an arteriotomy in the axillary / subclavian artery 106 or other suitable vessel. The proximal end portion of the inner drive system may be coupled to the distal end of the outer drive system using any suitable technique (e.g., compression rings, suturing, adhesive, stitching, etc.).

[0018] An arterial interface device or stopper device ("AID") can be used to provide hemostasis to the vasculature at the arteriotomy where the internal drive system resides. The AID can include one or more fixation elements used to secure the device in a desired orientation or position and one or more ports. For example, one port can provide a wire shaft into the patient's vasculature. The AID can have features similar to those described in U.S. Pat. No. 7,892,162, the disclosure of which is incorporated herein by reference in its entirety. The AID can be deployed or advanced beyond the internal drive system (e.g., the portion externalized from the vasculature) via a shaft within the AID that defines a lumen. The internal drive system can be inserted into and extend through the shaft. An external drive system can be coupled to the internal drive system at a location proximal to the AID.

[0019] The external drive system may be an elongated structure having a lumen extending therethrough. The external drive system may be disposed at least partially subcutaneously but external to the patient's vasculature. After implantation, a proximal end portion of the external drive system may be coupled to a skin interface device (described below). The drive system lumens (e.g., inner and outer drive systems) may be coupled to lumens of the blood pump to transport working fluid to and from the blood pump.

[0020] The drive unit may be a small, portable device that operates the balloon pump by generating a flow of working fluid (e.g., gas or other fluid, such as ambient air or helium) into and out of the balloon 114 via the drive train 116. For example, the drive unit may generate positive pressure to accelerate the working fluid within the balloon 114, thereby inflating the balloon 114, and induce negative pressure to withdraw the working fluid from the balloon 114, thereby deflating the balloon 114. The drive unit may utilize a bellows, blower, compressor, accelerator, or other similar mechanism to direct the flow of working fluid into and out of the balloon 114. The drive unit may also include a mechanism to prevent over-inflation of the balloon 114.

[0021] The skin interface device ("SID") may be a transcutaneous device that allows a drive unit to drive the movement of the balloon. The SID may provide a stable and / or safe exit site for the drive system 116 (e.g., an outer drive system). In embodiments in which the drive system 116 comprises an inner drive system and an outer drive system, the proximal end of the outer drive system may be coupled to an inner-facing portion of the SID, and the drive unit may be coupled to an outer-facing portion of the SID. The SID may thus direct gas received from the drive unit to the outer drive system for delivery to the balloon 114. The SID may be similar to the interface device described in U.S. Pat. No. 10,137,230, the disclosure of which is incorporated herein by reference in its entirety.

[0022] The balloon 114 may be implanted via the femoral artery and explanted via the axillary / subclavian artery 106 without the need to enter the chest. In one embodiment, the intravascular implantation procedure is as described in U.S. Patent Application No. 16 / 876,110. Briefly, and with reference to FIGS. 2A-2D , FIGS. 2A-2D illustrate various stages of a procedure for intravascularly implanting an IABP assembly into a patient's vasculature, in which introducer sheaths 204, 206 may be inserted into the femoral artery 202 and the axillary and / or subclavian arteries 106, respectively. A guidewire 208 is introduced into either of the introducer sheaths 204, 206 and advanced through the patient's vasculature such that the guidewire 208 extends between the femoral artery 202 and the axillary / subclavian artery 106, thereby establishing a "rail." This process is sometimes referred to as "flossing" the patient. After the rail is established, an elongate delivery dilator (sometimes called a delivery shaft, delivery catheter, or interceptor dilator) 210 can be advanced over the guidewire 208 to extend between the introducer sheaths 204, 206. In one embodiment, the elongate delivery dilator has a small lumen running throughout that is sized to allow the guidewire 208 (e.g., a 0.035 inch guidewire) to slide through the delivery dilator. 3, the elongate delivery dilator 210 can have an inwardly blunt or pointed distal end region to help guide it into the introducer sheath 204, 206 (e.g., the introducer sheath 206 positioned in the axillary or subclavian artery 106), and the delivery dilator 210 is advanced through the vasculature such that the proximal end 214 of the delivery dilator 210 is externally accessible in the axillary or subclavian artery 106 and the distal end 212 of the delivery dilator 210 is externally accessible in the femoral artery 202. The guidewire 208 may be removed once the delivery dilator 210 is so positioned.

[0023] The portion of the exteriorized distal end 212 of the elongate delivery dilator 210 can then be removably connected to the drive system 116 using a connector or other mechanism. For example, the distal end 212 of the delivery dilator 210 can have a threaded male connecting element, and the proximal end 216 of the drive system 116 can have a threaded female connecting element sized and shaped to match the threaded male connecting element on the distal end 212 of the delivery dilator 210. The distal end 212 of the delivery dilator 210 can then be secured to the proximal end 216 of the drive system 116 by threading the threaded male connecting element into the threaded female male connecting element, as shown in FIG. 2C. For the avoidance of doubt, FIG. 2C shows the threaded connecting element just prior to connection and after the guidewire 208 has been removed.

[0024] In one embodiment, the distal end 212 of the delivery dilator 210 includes a removable portion that covers the threaded male connection element, optionally having an inwardly blunted or pointed end region as described above. In such an embodiment, the practitioner can remove the removable portion to expose the threaded male connection element after the distal end 212 of the delivery dilator 210 is exteriorized by the introducer sheath 204 in the femoral artery 202.

[0025] The drive system 116 and balloon 114 can then be moved into the patient's vasculature by pulling on the proximal end 214 of the delivery dilator 210, which is exteriorized in the axillary and / or subclavian arteries 106. In this process, the drive system 116 is first retracted into the body through the introducer sheath 204 in the femoral artery 202. The drive system 116 may be exteriorized through the introducer sheath 206 in the axillary and / or subclavian arteries 106, and the delivery dilator 210 may be unscrewed. As the drive system 116 is withdrawn from the axillary and / or subclavian arteries 106, the balloon 114 is retracted into the introducer sheath 204 in the femoral artery 202, allowing the balloon 114 to be moved through the vasculature in a direction counter to blood flow. The practitioner continues to pull on the drive system 116 until the balloon 114 is in the desired location (e.g., within the thoracic aorta 108). The positioning of the balloon 114 can be confirmed by bone landmarks from CT and / or by contrast angiography, using, for example, a 5F Omni™ flush or pigtail catheter inserted through the introducer sheath 204 in the femoral artery 202. The above has been described with reference to embodiments in which the drive system 116 is at least as long as the vasculature from the femoral artery 106 to the axillary and / or subclavian arteries 106. In embodiments in which the drive system 116 is not long enough to extend such vasculature, the balloon 114 can be pulled into the introducer sheath 204 in the femoral artery 202 before the drive system 116 is withdrawn from the axillary and / or subclavian arteries 106, and the delivery dilator 210 does not have to be unscrewed until after the pulling process (e.g., until the balloon 114 is in the desired location, e.g., within the thoracic aorta 108).

[0026] In some embodiments, the balloon 114 may be deflated before being drawn through the introducer sheaths 204, 206 (e.g., the introducer sheath 204 of the femoral artery 202) and into the vasculature (e.g., the femoral artery 202). For example, a practitioner can attach a Y-connector to the proximal end 214 of the elongate delivery dilator 210. Because the lumen of the elongate delivery dilator 210 is in fluid communication with the interior of the balloon 114 (via the drive system 116), the practitioner can use a syringe or other pumping element to remove any air from the balloon 114. The practitioner can then close the Y-connector (e.g., using a stopcock) to maintain negative pressure within the balloon 114, the drive system 116, and the elongate delivery dilator 210. Without being bound by theory, it is expected that deflating the balloon 114 reduces and / or minimizes the profile of the balloon 114, making it easier to draw the balloon 114 through the introducer sheaths 204, 206 and into the patient's vasculature.

[0027] In some embodiments, the balloon 114 is folded, twisted, or otherwise placed into a delivery state having a reduced cross-sectional area before or while being pulled through the introducer sheath 204 and into the femoral artery 202. For example, the balloon 114 may be pulled through a delivery sheath, such as a funnel assembly or other collapsible tube, to reduce one or more dimensions of the balloon 114. Exemplary delivery sheaths are described in U.S. Patent Application No. 16 / 876,110. In some embodiments, the balloon 114 may be manually folded or twisted in addition to, or instead of, using a delivery sheath. Reducing the dimensions (e.g., cross-sectional dimension, outer diameter, etc.) of the balloon 114 may facilitate pulling the balloon 114 through the introducer sheaths 204, 206 and into the patient's vasculature. In some embodiments, the delivery sheath may be docked onto the introducer sheaths 204, 206 (e.g., the introducer sheath 204 in the femoral artery 202). The delivery sheath is configured so that (1) the balloon 114 can be folded and kept compact during insertion, (2) the balloon 114 can breach hemostatic valves on the docked introducer sheaths 204, 206, and (3) the inner diameter of the delivery sheath is substantially the same as the inner diameter of the introducer sheaths 204, 206, such that the balloon 114 experiences a smooth or seamless transition from the delivery sheath to the introducer sheaths 204, 206 during insertion as the introducer sheaths are docked. (i.e., from the perspective of the balloon 114, the balloon 114 passes through the same conduit / lumen during insertion.) In some embodiments, the folding and / or twisting may be performed in combination with the degassing process described above. In other embodiments, the folding and / or twisting may be performed in place of the degassing process described above. In some embodiments, the folding process may be performed immediately prior to retracting the balloon 114 into the vasculature. In other embodiments, the balloon 114 may be preloaded within the delivery sheath. However, in some embodiments, a delivery sheath is not used and the balloon 114 is loaded / pulled directly into and through the introducer sheaths 204,206.

[0028] 3A-3C, various features of the elongate delivery dilator 210 are shown. The delivery dilator 210 forms a generally tubular conduit, shaft, pipe, etc. having a lumen 302 extending therethrough. The lumen 302 is sized such that the elongate delivery dilator 210 can be advanced over a guidewire 208 (e.g., a 0.035 inch wire). As previously described, the elongate delivery dilator 210 can include a proximal end 214 and a distal end 212. In some embodiments, the proximal end 214 can include a valve or port 304 (e.g., a check valve, a luer lock, a sealable silicone port, etc.) to provide controlled access to the lumen 302. For example, as previously described, a syringe, Y-connector, three-way stopcock, etc. can be attached to the drive system 116 with the valve 304 to deflate the balloon 114 before retracting it into the patient's vasculature. In embodiments that include port 304, port 304 remains external to the patient (e.g., at the axillary artery access site) during the implantation process. The distal end 212 of elongate delivery dilator 210 can be designed to penetrate a hemostatic valve in an introducer sheath (e.g., introducer sheath 206) when inserted retrograde into the introducer sheath. For example, in the illustrated embodiment, distal end 212 is at least partially pointed and / or inwardly beveled to aid in penetrating the hemostatic valve.

[0029] The distal end 212 of the elongate delivery dilator 210 may include a detachable portion 306 (e.g., a detachable distal tip). The detachable portion 306 may be secured to the elongate delivery dilator 210 at an attachment interface 308, which will be described in detail below with reference to Figures 3B and 3C. During the intravascular implantation process described herein, the detachable portion 306 is removed from the elongate delivery dilator 210 after the distal end 212 is exteriorized in the introducer sheath 204 adjacent the femoral artery 202. The drive system 116 is then connected to the elongate delivery dilator 210 at the attachment interface 308.

[0030] 3B and 3C illustrate additional features of the elongate delivery dilator 210 connected at the attachment interface 308. More specifically, FIG. 3B shows the detachable portion 306 connected to the elongate delivery dilator 210 at the attachment interface 308, and FIG. 3C shows the detachable portion 306 spaced (e.g., disconnected) from the elongate delivery dilator 210 at the attachment interface 308. Referring together to FIGS. 3B and 3C, the elongate delivery dilator 210 includes a first connecting element 310A and a second connecting element 310B connected at the attachment interface 308. The first connecting element 310A and the second connecting element 310B engage to removably secure the detachable portion 306 to the elongate delivery dilator 210. In the illustrated embodiment, the first connecting element 310A is a threaded female connecting element and the second connecting element 310B is a threaded male connecting element. During surgery, the removable portion 306 can be removably secured to the elongate delivery dilator 210 by threading the threaded male connecting element into the threaded female connecting element. The removable portion 306 can be removed from the elongate delivery dilator 210 by unscrewing the threaded female connecting element from the threaded male connecting element. In other embodiments, the first connecting element 310A is a threaded male connecting element and the second connecting element 310B is a threaded female connecting element. Nevertheless, the first connecting element 310A and the second connecting element 310B can include a gap 312 extending through the connecting elements to allow the elongate delivery dilator 210 to be advanced over a wire.

[0031] The first connecting element 310A and the second connecting element 310B may be constructed of a generally inflexible material (e.g., stainless steel). Because the first connecting element 310A and the second connecting element 310B are constructed of a generally inflexible material, the elongate delivery dilator 210 cannot bend or curve at the attachment interface 308. Therefore, the first connecting element 310A and the second connecting element 310B may have a relatively short combined length when connected to ensure that the elongate delivery dilator 210 can be routed through various curves within the patient's vasculature despite the stiffness at the attachment interface 308. For example, the first connecting element 310A and the second connecting element 310B may have a combined length of less than about 2 cm and / or less than about 1 cm.

[0032] FIGS. 4A-4C illustrate various features of the drive system 116. FIGS. 4A and 4B are perspective and cross-sectional views, respectively, of the drive system 116. As shown in FIGS. 4A and 4B, the drive system 116 can have a generally tubular wall 402 defining a lumen 404 extending therethrough. The generally tubular wall 402 can be gas impermeable to prevent gas from escaping the lumen 404 and entering the patient's vasculature. In some embodiments, the generally tubular wall 402 can comprise multiple layers. In the illustrated embodiment, for example, the generally tubular wall 402 includes an inner membrane 406 and an outer membrane 408 concentrically surrounding the inner membrane 406. A coil or other helically wound kink-resistant element 410 (shown alone in FIG. 4C) can be disposed between and / or partially within the inner membrane 406 and the outer membrane 408. The inner membrane 406 and the outer membrane 408 may be at least partially constructed from a flexible material. Additionally, the outer membrane 408 may be constructed from an anti-thrombogenic material, such as elastin-S, to reduce and / or prevent thrombus formation on the drivetrain 116 when implanted in a patient's vasculature. The coil 410 may be constructed from nitinol or another suitable kink-resistant material, such as stainless steel. In one embodiment, the coil 410 is a biocompatible material. In some embodiments, the coil 410 may have a pitch P of less than about 1 mm (e.g., about 0.5 mm). Without being bound by theory, the incorporation of the coil 410 into the tubular wall 402 provides several advantages, including (1) providing additional stability to the generally tubular wall 402, (2) reducing the required thickness of the generally tubular wall 402 to achieve the desired stability, and (3) reducing and / or preventing the drivetrain 116 from kinking or folding. In some embodiments, the coil 410 extends only along a portion of the drivetrain 116, dividing the drivetrain 116 into a "reinforced" section and an "unreinforced" section. In other embodiments, the coil 410 extends along the entire length or nearly the entire length of the drivetrain 116.

[0033] The proximal end 216 of the drive system 116 can include a connecting element 412 for connecting the drive system 116 to the elongate delivery dilator 210 ( FIGS. 5A-5C ). Accordingly, the connecting element 412 can also be referred to as the elongate delivery dilator connecting element 412. The connecting element 412 can be a threaded female connecting element sized and shaped to receive a corresponding threaded male connecting element 310B on the elongate delivery dilator 210. In other embodiments, the connecting element 412 can be a threaded male connecting element sized and shaped to receive a corresponding threaded female connecting element on the elongate delivery dilator 210. In yet other embodiments, the connecting element 412 is another suitable fastening mechanism for securing the first drive system 120 to the elongate delivery dilator 280. In some embodiments, the connecting element 412 includes an aperture 412A or other feature that allows air to flow through and / or around the connecting element 412 and into the lumen 404. Thus, when the drive system 116 is connected to the elongate delivery dilator 210 via the connecting element 412, gas can flow through the elongate delivery dilator 210 and into the lumen 404 via the aperture 412A, and vice versa.

[0034] The drive system 116 can have a substantially uniform outer diameter 414. In one embodiment, the outer diameter 414 of the drive system 116 is less than about 6 mm. For example, in some embodiments, the outer diameter 414 is about 4.2 mm. In other embodiments, the outer diameter 414 is less than about 4.2 mm. In particular, the outer diameter 414 of the drive system 116 can be selected to fit through one or both of the introducer sheaths 204, 206 during the intravascular implantation procedures described herein. For example, in some embodiments, the drive system 116 has an outer diameter of 4.2 mm (e.g., 12.6 Fr), the introducer sheath 204 proximal to the femoral artery 202 is a 16 Fr sheath, and the introducer sheath 206 proximal to the axillary and / or subclavian arteries 106 is a 14 Fr sheath. In such an embodiment, the drive system 116 fits through both introducer sheaths 204, 206. The outer diameter 214 may be small enough to fit within various patient anatomies. (For example, a larger driveline may be implanted only in patients with axillary artery diameters above a certain threshold.) The driveline 116 may have an inner diameter 416 (i.e., the diameter of the lumen 404, as defined by the intima 406) of approximately 2 mm to 5 mm. For example, in some embodiments, the inner diameter 416 is approximately 3.3 mm. In other embodiments, the inner diameter 416 is less than 3.3 mm.

[0035] The drive system 116 can have a relatively long length. For example, the drive system 116 may be longer than about 100 cm (e.g., about 150 cm). For example, having a relatively long length ensures that a portion of the drive system 116 remains external to the patient during the implantation process. If the drive system 116 is disconnected from the elongate delivery dilator 210 during the implantation process, the portion of the drive system 116 remaining external to the patient can be used to retrieve the drive system 116 and balloon 114 from the patient's vasculature. Due to its relatively long length, the drive system 116 is typically disconnected before securing the drive system 116 to a second drive system (not shown). For example, a portion of the proximal end 222 is removed, thereby allowing removal of the portion of the drive system 116 having the connecting element 412, which is no longer needed because the drive system 116 was in place prior to disconnecting the drive system 116.

[0036] In embodiments in which only a portion of the drivetrain 116 is reinforced, the reinforced portion may have a first outer diameter that is larger than a second outer diameter of the unreinforced portion. For example, the reinforced portion may have an outer diameter of approximately 4.2 mm, and the unreinforced portion may have an outer diameter of approximately 4 mm. In such embodiments, the reinforced portion may have a length greater than approximately 30 cm, and the unreinforced portion may have a length greater than approximately 10 cm. In some embodiments, the transition between the first outer diameter and the second outer diameter may be tapered or otherwise gradual.

[0037] 3A to 3C, the second connecting element 310B can be used to connect the drive system 116 to the elongate delivery dilator 210 (once the detachable portion 306 is removed) by engaging the elongate delivery dilator connecting element 412 on the drive system 116. Accordingly, the second connecting element 310B may also be referred to as the drive system connecting element 312B. In embodiments in which the elongate delivery dilator connecting element 412 on the drive system 116 is a threaded male connecting element, the second connecting element 310B is a threaded female connecting element. Similarly, in embodiments in which the elongate delivery dilator connecting element 412 is a threaded female connecting element, the second connecting element 310B is a threaded male connecting element. The aperture 312 on the second connection element 310B aligns with the aperture 412A on the elongate delivery dilator connection element 412 to place the elongate delivery dilator 210 in fluid communication with the lumen 404 of the drive system 116 (and the interior volume of the balloon 114). This allows gas to be drawn from the balloon 114, through the drive system 116 and the elongate delivery dilator 210, for example, during a degassing process.

[0038] The elongate delivery dilator 210 may include an outer membrane 314. The outer membrane 314 may be gas impermeable and may be constructed of any suitable biocompatible and / or anti-thrombogenic material. For example, in some embodiments, the outer membrane 314 is constructed of elastin-S. In some embodiments, the elongate delivery dilator 210 also includes one or more stiffening wires 316. In some embodiments, the stiffening wires 316 are generally similar to the coils 410 in the drivetrain 116. For example, the stiffening wires 316 may be one or more helically wound nitinol coils that are generally kink-resistant. Although shown only proximate the attachment interface 308, the stiffening wires 316 may extend along the entire length or substantially the entire length of the elongate delivery dilator 210. A length is a substantial length of the elongate delivery dilator 210 if it is within 95%, 90%, 85%, 80%, 75%, 70%, 65%, 60%, 55%, 50%, 45%, 40%, 35%, 30%, 25%, 20%, 15%, or 10% of the length of the elongate delivery dilator 210. However, in other embodiments, the stiffening wire 316 is positioned only proximate the attachment interface 308 to provide additional stability at the attachment interface 308.

[0039] The elongate delivery dilator 210 may have an outer diameter 318 (excluding the port 304, in embodiments where it is included) of less than about 6 mm. For example, in some embodiments, the outer diameter 318 is about 4.2 mm. In other embodiments, the outer diameter 318 is less than about 4.2 mm. In particular, the outer diameter 318 of the elongate delivery dilator 210 can be selected to fit through one or both of the introducer sheaths 204, 206 during the implantation process described herein. For example, in some embodiments, the elongate delivery dilator 210 has an outer diameter of 4.2 mm (e.g., 12.6 Fr), the introducer sheath 204 proximal to the femoral artery 202 is a 16 Fr sheath, and the introducer sheath 206 proximal to the accessory artery and / or subclavian artery 106 is a 14 Fr sheath. Thus, the elongate delivery dilator 210 is able to fit through both of the introducer sheaths 204, 206. The outer diameter 318 may also be small enough to allow the elongate delivery dilator 210 to fit within and maneuver through a variety of patient anatomy. In some embodiments, the elongate delivery dilator 210 has an outer diameter 318 that is the same as and / or approximately the same as the outer diameter 414 of the drivetrain 116. In one embodiment, the elongate delivery dilator 210 also has a relatively long length. For example, the elongate delivery dilator 210 may have a length greater than about 100 cm (e.g., about 150 cm). As discussed above, having a relatively long length ensures that the elongate delivery dilator 210 can extend between the introducer sheath 204 and the introducer sheath 206.

[0040] The balloon 114 can be actuated, at least in part, by pressure sensor data (e.g., from a pressure sensor element associated with the balloon 114 and / or from the patient's ECG via a surface ECG sensor). The associated ECG sensor can be coupled to the SID via ECG leads, which relay measurements received from the sensor to the drive unit via a wired or wireless connection. In other embodiments, the ECG sensor can be wirelessly connected to the drive unit and transmit sensed measurements directly to the drive unit without the use of the SID. The ECG sensor can be implanted, external, or both implanted and external. For example, the ECG sensor can be an implantable bipolar electrode placed on and / or adjacent to the heart 102 or other suitable tissue to determine when the left ventricle is contracting or relaxing. Counterpulsation therapy can be achieved by rapidly inflating the balloon 114 within the aorta 108, 109 immediately after aortic valve closure (diploication) and by using the drive unit to rapidly deflate the balloon 114 just prior to the onset of deflation. The dicrotic ridge may be sensed by a pressure sensor and the onset of contraction may be predicted or sensed using an ECG signal.

[0041] Rapid inflation of the balloon 114 increases aortic pressure during diastole, improving end-organ and coronary perfusion. Rapid deflation of the balloon 114 reduces native ventricular ejection pressure, reducing afterload and left ventricular external work. This embodiment of PiVAS provides counterpulsation therapy in patients that is more effective than a 40 ml 1ABP device due to the larger displacement volume. PiVAS has enhanced durability, reduces or eliminates thrombogenic and / or occlusive risks, and is an overall lower cost, less invasive device implantation / explantation procedure without the need to enter the chest. PiVAS also reduces the serious adverse event (AE) burden, allowing for non-obligatory support for less sick heart failure populations. (The device can be "on" or "off" as needed.)

[0042] Balloon and Drive System Embodiments

[0043] 5 through 11 (and FIG. 1 for reference to the aortic arch vasculature 100), various features are disclosed for the novel balloon 502, the novel elongate delivery dilator connecting element 810, and the novel driveline marker element 1102. It is expressly contemplated that aspects and features of the balloon 114, driveline 116, and the elongate delivery dilator 210, SID, and drive unit described above may be used in or with the features described in FIGS. 5 through 11, including the balloon 502, the elongate delivery dilator connecting element 810, and the driveline marker element 1102. For example, the balloon 502 may be constructed from a biocompatible, non-thrombogenic elastomeric material (e.g., Biospan®-S) or other suitable material and may have the features described in U.S. Pat. No. 8,066,628.

[0044] 5-6, a top view (FIG. 5) and an enlarged view (FIG. 6) of region 600 of a balloon pump assembly 500 are shown, each of which may include a balloon 502 and a drivetrain 504, according to one embodiment of the present disclosure. The balloon 502 is an elongated, inflatable member comprising a chamber having a distal region 506, a central region 508, and a proximal region 510. The interior volume of the balloon 502 may be 20 cc to 60 cc, and for the adult population, 40 cc to 60 cc. The proximal region 510 may be substantially cylindrically conical, tapering toward the proximal end 514 of the balloon 502. A cylindrically conical shape is a conical tank shape. Also, a shape may be substantially cylindrically conical, as long as the base is elliptical, circular, or only slightly deviating from an elliptical or circular shape, and the height is generally conical in shape. The height may indicate a nominal deviation from a conical shape. For example, the proximal region 510 may be substantially cylindrically conical in shape, insofar as it generally resembles a conical reservoir. The proximal region 510 may have an opening at the proximal end 514 ( FIG. 7 , element 712). In one embodiment, the substantially cylindrically conical region 510 includes a tubular proximal end 514 that defines, in part, the opening 712.

[0045] The central region 508 of the balloon 502 may be substantially cylindrical in shape with a substantially uniform outer diameter 513 sized to be less than the width of the patient's thoracic aorta 108. A shape is substantially cylindrical as long as the base is oval, circular, or only slightly deviates from oval or circular, and the height is generally tubular in shape. The height may indicate a nominal deviation from tubular. For example, as long as the central region 508 generally resembles a cylinder or tube, it is substantially cylindrical in shape. A diameter (here, outer diameter 513) is "substantially uniform" if the diameter across the applicable region (e.g., central region 508 of balloon 502) does not deviate by more than about 0.001 inches (about 0.025 mm) across the applicable region (here, balloon 502). In one embodiment, outer diameter 513 is about 12 mm to 20 mm. In one embodiment, the outer diameter is about 17.5 mm.

[0046] The distal region 506 of the balloon 502 may be substantially cylindrically conical, tapering toward the distal end 512 of the balloon 502. The distal end 512 of the balloon 502 may be rounded, bullet-shaped, or nipple-shaped.

[0047] In one embodiment, the combined length of the proximal region 510 and the central region 508 is sized such that the combined length is substantially equal to the length of the descending aorta 108, 109 from a point proximal to the axillary / subclavian arteries 106 to approximately the two bifurcations of the renal arteries 110. In adults, this length may be 18 to 25 cm, and in pediatric patients, this length may be 10 cm or less. If the combined length of the proximal region 510 and the central region 508 is within 95%, 90%, 85%, 80%, 75%, 70%, 65%, 60%, 55%, or 50% of the length of the descending aorta 108 from a point near the axillary / subclavian artery 106 to approximately the two bifurcations 110 of the renal arteries, then the combined length of the proximal region 510 and the central region 508 is approximately equal to the length of the descending aorta 108, 109 from a point near the axillary / subclavian artery 106 to approximately the two bifurcations 110 of the renal arteries. In another embodiment, the combined length of the proximal region 510 and the central region 508 is sized substantially equal to (i.e., within 95%, 90%, 85%, 80%, 75%, 70%, 65%, 60%, 55%, or 50% of) the length of the portion of the descending aorta 108, 109 below or behind the axillary / subclavian artery 106 that has a diameter greater than 80%, 85%, 90%, or 95% of the maximum diameter of the thoracic aorta 108. For example, the combined length of the proximal region 510 and the central region 508 may be between about 100 mm and 220 mm. In one embodiment, the combined length of the proximal region 510 and the central region 508 may be between about 160 mm and 220 mm, or between about 180 mm and 220 mm.

[0048] In one embodiment, the taper of the distal region 506 substantially matches the taper of the descending aorta 108, 109 beginning proximate to or after the bifurcation of the renal arteries 110. By substantially matches, it is meant that the taper angle of the distal region 506 is within 10% of the taper angle of the descending aorta 108, 109 beginning proximate to or after the bifurcation of the renal arteries 110. The length of the distal region 506 of the balloon 502 may be greater than about 15% of the combined length of the proximal region 510 and the central region 508. In one embodiment, the length of the distal region 506 of the balloon 502 is greater than about 15% but less than about 40% of the combined length of the proximal region 510 and the central region 508. The degree of taper may correspond to or exceed the stenosis of the descending aorta 108, 109 and may be sized so as not to occlude the renal arteries 110 when the balloon 502 is positioned within the descending aorta 108, 109 for surgery. For the avoidance of doubt, when positioned within the descending aorta 108, 109, the balloon 502 may be positioned to span a greater vertical distance than the balloon 114 of FIG. 1 . In particular, the distal region 506 may extend beyond (i.e., behind) the two bifurcations 110 of the renal arteries. In one embodiment, the distal region 506 can extend beyond (i.e., behind) the two bifurcations 110 of the renal arteries when the proximal region 510 of the balloon 502 is positioned in a corresponding position to the proximal region of the balloon 114 as shown in FIG. 1 , i.e., when the proximal region 510 of the balloon 502 is positioned adjacent the aortic arch 104.

[0049] In one embodiment, the length of the proximal region 510 is approximately 63 mm, the actively tapered portion of the proximal region 510 is approximately 43 mm, and the tubular proximal end 514 is approximately 20 mm. In one embodiment, the central region 508 is approximately 160 mm. In one embodiment, the distal region 506 is approximately 55 mm. The distal end 512 portion of the distal region 502 may be rounded, bullet-shaped, or nipple-shaped and may be approximately 30 mm. In one embodiment, the entire balloon 502 is approximately 277 mm ± 2 mm.

[0050] In one embodiment, the length of proximal region 510 is about 15 to 30% of the length of balloon 502. In one embodiment, the length of central region 508 is about 55 to 65% of the length of balloon 502. In one embodiment, the length of distal region 512 is about 15 to 30% of the length of balloon 502.

[0051] The balloon 502 can have a wall, the inner surface of which defines an elongated, inflatable chamber. A working fluid (e.g., air, gas, etc.) can be delivered to the elongated, inflatable chamber to inflate the balloon 502 and can be expelled from the chamber to deflate the balloon 502. The delivery and expulsion of the working fluid can be facilitated by a drive train 504. The outer surface of such a wall can define the exterior of the balloon 502. In one embodiment, the wall of the balloon 502 has a substantially uniform thickness. A thickness (here, the wall thickness of the balloon 502) is "substantially uniform" if the thickness does not vary by more than about 0.001 inch (about 0.025 mm) over the applicable region (here, the balloon 502). The wall thickness of the balloon 502 can be 0.003 inch (0.076 mm) to 0.012 inch (0.305 mm) or 0.014 inch (0.356 mm). In one embodiment, the wall thickness of the balloon 502 may be 0.005 inches (0.127 mm) to 0.007 inches (0.178 mm). In other embodiments, the wall of the balloon 502 has a non-uniform thickness. For example, the wall of the balloon 502 at one or more of the distal region 506 and the proximal region 510 (or portions thereof) has a thickness that exceeds the thickness of the central region 508. In yet other embodiments, the wall of the balloon 502 at only the distal end 512 or only the proximal end 514 has a thickness that exceeds the wall thickness of the balloon 502 at the central region 508. In such embodiments, the distal region 506 and the proximal region 510 (or portions thereof), or their respective ends 512, 514, may have a wall thickness that exceeds the wall thickness of the central region 508. For example, the wall thickness at distal region 506 (or a portion thereof) or distal end 512 may be 0.003 inches (0.076 mm) to 0.016 inches (0.406 mm) thick. In one embodiment, the wall thickness at distal region 506 (or a portion thereof) or distal end 512 may be 0.006 inches (0.152 mm) to 0.009 inches (0.229 mm) thick.Similarly, the wall thickness at the proximal region 510 (or portion thereof) or proximal end 514 may be between 0.003 inches (0.076 mm) and 0.015 inches (0.381 mm) thick. In one embodiment, the wall thickness at the proximal region 510 (or portion thereof) or proximal end 514 may be between 0.006 inches (0.152 mm) and 0.008 inches (0.203 mm) thick.

[0052] In embodiments in which the wall thickness at the distal region 506 (or portion thereof) or distal end 512 exceeds the wall thickness of the remainder of the balloon 502, the wall thickness of the distal region 506 (or portion thereof) or distal end 512 can be substantially uniform. In one embodiment, the thicker portion is proximate the central region 508. In another embodiment, the thicker portion is proximate the distal end 512. The wall thickness of the central region 508 and / or proximal region 510 may also be substantially uniform.

[0053] In embodiments in which the wall thickness at the proximal region 510 (or portion thereof) or proximal end 514 exceeds the wall thickness of the remainder of the balloon 502, the wall thickness of the proximal region 510 (or portion thereof) or proximal end 514 can be substantially uniform. In one embodiment, the thicker portion is proximal to the central region 508. In another embodiment, the thicker portion is proximal to the proximal end 515. The wall thickness of the central region 508 and / or distal region 506 can also be substantially uniform.

[0054] In embodiments in which the wall thickness at the distal region 506 (or portion thereof) or distal end 512 exceeds the wall thickness at the remainder of the balloon 502 (e.g., central region 508), and the wall thickness at the proximal region 510 (or portion thereof) or proximal end 514 exceeds the wall thickness at the remainder of the balloon 502 (e.g., central region 508), the wall thickness at the distal region 506 (or portion thereof) or distal end 512 can be substantially uniform, the wall thickness at the proximal region 510 (or portion thereof) or proximal end 514 can be substantially uniform, and the wall thickness at the central region 508 and / or proximal region 510 can be substantially uniform.

[0055] Increased wall thickness in the proximal region 510 (or portion thereof) or proximal end 514 can minimize distortion and twisting in such region (or portion thereof) or end, which may otherwise occur more easily due to the relatively stiffer drivetrain 504 relative to the balloon 502. Therefore, it may be desirable to increase the wall thickness in the proximal region 510 (or portion thereof) or proximal end 514 to minimize distortion and prevent twisting in this region (or portion thereof) or end of the balloon 502. Distortion and twisting in any portion of the balloon 502, including the proximal region 502 (or portion thereof) or proximal end 514, if not minimized, reduced, or eliminated, can cause failure of the balloon.

[0056] The increased wall thickness in the distal region 506 or distal end 512 can minimize distortion of the balloon 502 in embodiments where the balloon 512 is sized and shaped to receive a support structure configured to counteract buoyant forces acting on the balloon 502 during surgery in the descending aorta 108, 109. Such buoyancy forces could otherwise cause the balloon 502 to rotate or fold on itself (or otherwise develop gaps within the balloon 502) along one or more of the balloon's 502 longitudinal axis or the balloon's 502 latitudinal axis, as described in a U.S. patent application filed on the same day as this disclosure, owned by applicant / assignee NuPulseCV, Inc., entitled "BLOOD PUMP SUPPORT STRUCTURE AND METHODS FOR BLOOD PUMP ASSEMBLY," identifying Robert Christopher Hall, Joshua Ryan Woolley, Guruprasad Anapathur Giridharan, and Duane Sidney Pinto as inventors, and having attorney docket number 8020US00 / 236533-30035, the contents of which are incorporated by reference in their entirety. Such a support structure may be embedded in the blood pump assembly 500, and in particular in the balloon 502. Exemplary support structures can take a variety of shapes, including wire loops, wires with flexible tip portions that are curled back onto a portion of the wire support structure when positioned within the balloon 502, and wires with blunt distal ends, as generally shown in FIGS. 13-15. FIGS. 13A and 13B show wire loop support structures 1302 and 1306, respectively, positioned within the balloon 502. The distal end of the support structure 1302 includes a nipple 1304 formed as a pinch point within the wire loop support structure, while the distal end of the wire loop support structure 1306 includes a nipple 1308 formed by the wire crossing itself (e.g., the wire is twisted on itself). FIG. 14 shows a wire support structure 1402 having a flexible tip 1404 and a non-flexible body 1406 positioned within the balloon 502. The flexible tip portion 1404 may include a tail.15 shows a wire support structure 1502 having a blunt distal end 1504 disposed within the balloon 502. In such embodiments, the support structures (e.g., wire support structures 1302, 1306, 1402, and 1502) may operatively apply forces and strains to the wall of the balloon 502, particularly at the distal region 506 (or portion thereof) or distal end 512 of the balloon 502, which may otherwise cause the balloon 502 to fail, particularly at the distal region 506 (or portion thereof) or distal end 512 of the balloon 502. In embodiments of wire loop support structures 1302, 1306, the forces and strains may be induced in part by the distal regions of the nipples 1304, 1308 and / or the wire loops themselves. Similarly, in wire support structure 1402 embodiments, forces and strains may be induced in part by the flexible tip portion 1404 (e.g., when the flexible tip portion 1404 contacts the non-flexible body portion 1406 and / or when the flexible tip portion 1404 contacts along the curled back portion or tail of the flexible tip portion 1404). Also, in wire support structure 1502 embodiments, forces and strains may be induced in part by the blunt distal tip 1504.

[0057] The wall thickness may be related to the width of the inner lumen of the delivery dilator and / or introducer sheath 204, 206. In embodiments in which the distal region 506 (or a portion thereof) or distal end 512 is tapered, the taper may allow for the manufacture of a balloon 502 having a relatively thicker wall in such tapered region as compared to embodiments that are not or are not as tapered. Similarly, in embodiments in which the proximal region 510 (or a portion thereof) or proximal end 514 is tapered, the taper may allow for the manufacture of a balloon 502 having a relatively thicker wall in such tapered region as compared to embodiments that are not or are not as tapered.

[0058] The blood pump assembly 500 may also include a drivetrain 504 having a distal region 515 and a proximal end 516, the distal end 515 of the drivetrain 504 being coupleable to the proximal end 514 of the balloon 502 at a joint 602. The joint 602 may be formed at an engagement region of the proximal end 514 of the balloon 502 that is sized and shaped to fit over the distal end 515 of the drivetrain 504. The balloon 502 may be coupled to the drivetrain 504 using an attachment mechanism such as a compression ring or other suitable element that provides an airtight connection / pneumatic seal between the engagement region and the drivetrain 504. In one embodiment, a BioSpan®-S coating may be applied to the joint 602 to create a smooth joint that promotes laminar fluid flow.

[0059] Although not shown, in one embodiment, the balloon 502 extends beyond the thoracic aorta 108 and is positioned within the descending aorta 108, 109 when properly positioned for surgery.

[0060] 7A and 7B show a plan view and a cross-section of a balloon 502 according to one embodiment, where FIG. 7A is a plan view and FIG. 7B is a cross-section taken at a section line 702 pointing toward the proximal region 510 of the balloon 502, showing the substantially cylindrical-conical proximal region 510 tapering at an opening 712 toward the proximal end 514 of the balloon 502. The central region 508 of the balloon 508 can have a substantially uniform inner diameter 704. The inner diameter of the proximal region 510 may taper to gradually smaller inner diameters 706, 708, 710, consistent with the tapering of the descending aorta 108, 109 beginning near or after the two bifurcations 110 of the renal arteries. In one embodiment, the inner diameter 710 is the inner diameter of any tubular proximal end 514 and the inner diameter 710 of the opening 712. In one embodiment, the inner diameter 710 is about 4.35 mm.

[0061] 8-12 illustrate features of the drive system 504, including an exemplary novel elongate delivery dilator connecting element 810 and a novel drive system marker element 1202. FIG. 8 illustrates a plan view of the drive system 504. FIG. 9 illustrates a cross section of the drive system 504 taken at section line 802 and looking toward the distal end 515 of the drive system 504. FIGS. 10-11 illustrate a longitudinal cross section of the drive system 504 at the proximal region 516, illustrating two exemplary elongate delivery dilator connecting elements 810. FIG. 12 illustrates a longitudinal cross section of the drive system 504 at the distal end 515, illustrating the drive system marker element 1202. Referring to FIGS. 8-12, the drive system 504 can include an outer membrane 902, an inner membrane 904, and a kink-resistant element 908, which can be identical to similarly named components 408, 406, and 410 in FIGS. 4B-4C. The inner membrane 904 can have an inner wall 906 that defines a lumen 910. The lumen 910 can be identical to the lumen 404 of Figure 4B. An anti-kink element 908 can be disposed between the outer membrane 902 and the inner membrane along the first length 804 of the drivetrain 504.

[0062] The elongate delivery dilator connecting element 810 can be disposed at the proximal end 516 of the drive system 502 and can be sized and shaped to mate with a corresponding drive system connecting element associated with the distal end of the elongate delivery dilator (e.g., drive system connecting element 310B). For example, the elongate delivery dilator connecting element 810 can include a threaded female connecting element (as shown in FIG. 10), and the corresponding drive system connecting element (e.g., element 310B) can include a threaded male connecting element, sized and shaped to receive such threaded male connecting element. In another example, the elongate delivery dilator connecting element 810 can include a threaded male connecting element (as shown in FIG. 11), and the corresponding drive system connecting element can include a threaded female connecting element, sized and shaped to receive such threaded female connecting element. Using delivery dilator 210 as an exemplary delivery dilator, the distal end 212 of delivery dilator 210 can be connected to the proximal end 516 of drive system 504 by threading a threaded male connecting element into a threaded female connecting element.

[0063] The elongate delivery dilator connecting element 810 may not be threaded. Alternatively, the connecting element 810 may include other connecting elements, such as a snap-fit ​​connection.

[0064] The elongate delivery dilator connection element 810 may include a conduit 1006 in fluid communication with the lumen 910. Such a fluid connection may be utilized to deflate the balloon 502 during implantation and / or extraction. In some embodiments, the conduit 1006 may also be used during operation of the balloon 502 (e.g., if the drivetrain 504 is not resized after implantation).

[0065] The elongate delivery dilator connecting element 810 may be secured to the proximal end 516 of the drivetrain 504 using means such that the separation force required to separate the elongate delivery dilator connecting element 810 from the proximal end 516 of the drivetrain 504 exceeds at least about 8 pounds of force. In other embodiments, the separation force exceeds 12 to 30 pounds of force. In one embodiment, the elongate delivery dilator connecting element 810 may be a hose barb fitting 1004, 1102 having a threaded connecting element, such as a hose barb fitting 1004 having a threaded female connecting element 1108 or a hose barb fitting 1102 having a threaded male connecting element 1104.

[0066] The hose barb fittings 1004, 1102 can be at least partially disposed within the driveline 504 at the proximal end 516. With reference to the longitudinal axis 1000 and the transverse axis 1002, the hose barb fittings 1004, 1102 can include an inner surface 1008 or 1106 defining a conduit 1006 disposed along the longitudinal axis 1000, along an angle relative to the longitudinal axis 1000, or substantially along the longitudinal axis 1000 (e.g., within an angle of 45 degrees or less of the longitudinal axis 1000), with at least one barb 1010 extending circumferentially outward from the inner surface 1008, 1106 and defining an outer surface 1009. At least one barb 1010 extends outwardly along the transverse axis 1002, along an angle relative to the transverse axis 1002, or substantially along the transverse axis 1002 (e.g., within an angle of 45 degrees or less of the transverse axis 1002), and the at least one barb 1010 is sized and shaped to be embedded in the inner wall 906 of the drivetrain 504. In one embodiment, the at least one barb 1010 is sized and shaped to be embedded in the inner membrane 904 of the drivetrain 504. In one embodiment, the at least one barb 1010 is sized and shaped to be embedded in the kink-resistant element 908 and optionally the outer membrane 902.

[0067] In addition to defining the conduit 1006, the inner surface 1008 of the hose barb fitting 1004 may be threaded to form a threaded female connection element, while the inner surface 1106 of the hose barb fitting 1102 may be unthreaded but may define the conduit 1106 and the inner surface of the bolt 1105 extending out from the proximal end 516 of the drivetrain 504. The outer surface of the bolt may be threaded 1104 to form a threaded male connection element.

[0068] The hose barb fittings 1004, 1102 can include a flange 1012 disposed at the proximal end of the hose barb fitting 1004, 1102 and can extend circumferentially outwardly substantially along the transverse axis 1002 (e.g., within an angle of 45 degrees of the transverse axis 1002). The flange 1012 can extend circumferentially outwardly along the transverse axis 1002, along an angle relative to the transverse axis 1002, or substantially along the transverse axis 1002 (e.g., when the angle is within 45 degrees of the transverse axis 1002), extend substantially to the outer edge of the proximal end 516 of the driveline 504, and be sized and shaped to seal the lumen 910 or otherwise mate with the outer surface of a driveline connection element associated with the elongate delivery dilator (e.g., driveline connection element 310B). For example, the exterior of the flange 1012 can be configured to mate flush with the delivery dilator (e.g., its corresponding driveline connection element) to minimize blood intrusion while being pulled through the vasculature and to maintain a vacuum or substantial vacuum (i.e., within 95%, 90%, 85%, 80%, 75%, 70%, 65%, 60%, 55%, or 50% of vacuum) after the balloon 502 is deflated. In one embodiment, the circumscribing surface of the flange 510 is rounded at its outermost lateral edges 5014 (both distal and proximal to the proximal end 516 of the driveline wall) to reduce vascular trauma as the driveline 504 is pulled through the patient's vasculature. In one embodiment, the elongate delivery dilator connection element 810 is further adhered to the interior of the driveline 504 (e.g., the inner wall 906). In one embodiment, a heat shrink element (not shown) can be used on the exterior surface of the drive system 504 at the proximal end 516 to further secure the elongate delivery dilator connecting element 810 to the drive system 504. In one embodiment, although shown with the kink resistant element 908 extending to the proximal edge of the proximal end 516, the kink resistant element 908 extends only to the distal edge of the elongate delivery dilator connecting element 810.

[0069] The inner diameter of the drivetrain 504 may be substantially consistent from the distal end 515 to the proximal end 516, including the portion of the proximal end 516 where the elongate delivery dilator connecting element 810 is positioned and secured. That is, the deviation in inner diameter across the drivetrain is 10% or less. A substantially consistent inner diameter can facilitate a consistent flow of working fluid into and out of the balloon 502 during inflation and deflation.

[0070] Although not specifically illustrated as such, the drive line connection element 310B can be secured to the distal end 212 of the delivery dilator 210 using means such that the separation force required to separate the drive line connection element from the distal end 212 of the delivery dilator 210 exceeds at least about 8 pounds of force. In other embodiments, the separation force exceeds 12 to 20 pounds of force. In one embodiment, the drive line connection element can be a hose barb fitting having a threaded connection element, such as a hose barb fitting having a threaded female connection element or a hose barb fitting having a threaded male connection element. The hose barb fitting can have the same structure as the hose barb fittings 1104, 1102.

[0071] As described above, the kink-resistant element 908 can be disposed between the outer membrane 902 and the inner membrane along the first length 804 of the drive system 504. The first length 804 can span a majority of the longitudinal distance of the drive system 504. In one embodiment, the first length 804 extends from the proximal edge of the proximal end 516 to a region within or near the distal end 515 of the drive system 504. In another embodiment, the first length 804 extends substantially (i.e., within 95%, 90%, 85%, 80%, 75%, 70%, 65%, 60%, 55%, or 50%) from the distal edge of the elongate delivery dilator connecting element 810 to a region within or near the distal end 515 of the drive system 504. In another embodiment, the first length 804 may extend less than a majority of the longitudinal distance of the drive system 504, or may cover such a distance intermittently. The first length of driveline 804 may be any length of driveline 504 and may not be continuous.

[0072] Radiopaque material 1202 may be sandwiched between the outer membrane 902 and the inner membrane 904 and disposed along the second length 806 of the drivetrain 504. Radiopaque material may also be disposed on the outside of the drivetrain 504 and secured with a BioSpan®-S coating or applied as part of the joint 602 to create a smooth surface that promotes laminar fluid flow. The radiopaque material 1202 may act as a marker suitable for tracking the position of the drivetrain 504 (and thus the balloon 502) during radiological intervention (e.g., with x-ray or fluoroscopy). The second length 806 of the drivetrain 504 may extend substantially (i.e., within 95%, 90%, 85%, 80%, 75%, 70%, 65%, 60%, 55%, or 50%) from the distal end of the distal edge 515 of the drivetrain 504 to a region proximate the distal end of the first length 804. In another embodiment, the second length 806 of the drivetrain 504 may extend substantially (i.e., within 95%, 90%, 85%, 80%, 75%, 70%, 65%, 60%, 55%, or 50%) from the distal end of the distal edge 515 of the drivetrain 504 to the proximal edge of the distal region 515 of the drivetrain 504. In another embodiment, the second length 806 of the drivetrain 504 may extend substantially (i.e., within 95%, 90%, 85%, 80%, 75%, 70%, 65%, 60%, 55%, or 50%) from the distal end of the distal edge 515 of the drivetrain 504 to a point near the middle of the distal region 515 of the drivetrain 504. In one embodiment, second length 806 may be any length of driveline 504, may be discontinuous, may extend to the distal edge of distal end 515 of driveline 504, or may be limited to distal end 515 of driveline 504. In one embodiment, second length 806 may be the width of radiopaque marker 1202. In one embodiment, first length 804 and second length 806 may comprise substantially (i.e., within 95%, 90%, 85%, 80%, 75%, 70%, 65%, 60%, 55%, or 50%) the length of driveline 504.

[0073] Radiopaque material 1202 may be a band of radiopaque material. Also, in one embodiment, marker 1202 may have substantially the same thickness as kink-resistant element 908 such that the inner and outer diameters of drivetrain 502 are substantially uniform throughout the length of drivetrain 502. In other embodiments, radiopaque material 1202 may be a coil. Radiopaque material 1202 may be continuous or interrupted.

[0074] conclusion The above detailed description of embodiments of the present technology is not intended to be exhaustive or to limit the present technology to the precise form disclosed above. Specific embodiments and examples of the present technology have been described above for illustrative purposes, but those skilled in the art will recognize that various equivalent modifications are possible within the scope of the present technology. The various embodiments described herein can also be combined to provide further embodiments. For example, the above-described embodiments are not mutually exclusive, and features shown in any such embodiment can be combined with features of other embodiments.

[0075] From the foregoing, it will be understood that, although specific embodiments of the present technology are described herein for illustrative purposes, well-known structures and functions have not been shown or described in detail in order to avoid unnecessarily obscuring the description of the embodiments of the present technology.

[0076] Where the context permits, singular or plural terms may include the plural or singular term, respectively. As used herein, the phrase "and / or," such as in "A and / or B," refers to A alone, B alone, and A and B. Additionally, the term "comprising" is used throughout to mean the inclusion of at least the recited features, without excluding any more of the same feature and / or other features of an additional type. Furthermore, any range specified herein is intended to include the numbers defining the range, whether explicitly recited or not. The same applies to approximate ranges. Also, while specific embodiments have been described herein for illustrative purposes, it will be understood that various modifications can be made without departing from the present technology. Furthermore, while advantages associated with some embodiments of the present technology have been described in the context of those embodiments, other embodiments may also exhibit such advantages, and not all embodiments necessarily exhibit such advantages to fall within the scope of the present technology. Thus, the present disclosure and related technology may encompass other embodiments not explicitly shown or described herein.

[0077] From the foregoing, it will be appreciated that, although specific embodiments of the invention have been described herein for purposes of illustration, various modifications may be made without deviating from the scope of the invention. Accordingly, the invention is not limited except as by the appended claims.

[0078] The above-described technology solves several problems associated with the prior art. The specific configuration of the balloon 502 is designed to conform to the configuration of the descending aorta 108, 109 without obstructing any branch vessels, while also allowing for additional volume for greater cardiac support. The reinforced drivetrain 504 and novel connection elements (e.g., the elongated delivery dilator connection element 810) provide reinforcement lacking in the prior art / conventional designs. These reinforcements enable navigation of complex curvatures from the axillary artery to the thoracic aorta (or vice versa). Finally, the integrated radiopaque material 1202 solves various problems associated with conventional radiopaque markers.

Claims

1. 1. A blood pump assembly including: a balloon defining an elongated inflatable chamber having an interior volume, the balloon having a distal region having a distal end, a central region, and a proximal region having a proximal end, the proximal end of the balloon having an opening; the internal volume of the expandable chamber is between about 20 cc and 60 cc, the proximal region of the balloon is substantially cylindrically conical, the proximal region of the balloon tapering toward the proximal end of the balloon; the central region of the balloon is substantially cylindrical with a substantially uniform outer diameter of about 12 mm to 20 mm; the distal region of the balloon is substantially cylindrically conical, the distal region of the balloon tapering toward the distal end of the balloon; the combined length of the proximal and central regions of the balloon is between about 100 mm and 220 mm; A blood pump assembly, wherein the length of the distal region of the balloon is greater than about 15% of the combined length of the proximal and central regions of the balloon.

2. The blood pump assembly of claim 1 , wherein the distal end of the balloon is nipple-radiused.

3. The blood pump assembly of claim 1 , wherein the distal end of the balloon is nipple-shaped.

4. The blood pump assembly of claim 1 , wherein the distal end of the balloon is bullet-shaped.

5. The blood pump assembly of claim 1 , wherein the length of the distal region of the balloon is less than about 40% of the combined length of the proximal and central regions of the balloon.

6. a drive system having a distal end, a proximal end, a central lumen configured to communicate a working fluid for delivery between the elongated expandable chamber, and a connecting element; the distal end of the drivetrain is coupleable to the proximal end of the balloon at the opening; the connecting element is disposed and secured to the proximal end of the driveline, and a separation force required to separate the connecting element from the proximal end of the driveline is greater than at least about 12 to 30 pounds; the connecting element being sized and shaped to receive a corresponding connecting element associated with a delivery dilator configured to pull the drive system through a patient's vasculature; The blood pump assembly of claim 1 , wherein the connection element has a conduit configured to allow fluid to pass through the connection element into and out of the central lumen.

7. The blood pump assembly of claim 6 , wherein the drive train has a substantially uniform outer diameter.

8. the connection element is, at least in part, a hose barb fitting disposed within the driveline at the proximal end of the driveline; The hose barb fitting is a longitudinal axis, a transverse axis, at least one barb on an outer surface, an inner surface defining said conduit, and a flange; the conduit is disposed substantially along the longitudinal axis; the at least one barb extends circumferentially outward from the inner surface substantially along the transverse axis, the at least one barb being sized to be embedded in an inner wall of the drivetrain; 7. The blood pump assembly of claim 6, wherein the flange is disposed at the proximal end of the hose barb fitting and extends circumferentially outward and substantially along the transverse axis, the flange is disposed external to the drivetrain and extends substantially to an outer edge of the proximal end of the drivetrain, and a circumscribing surface of the flange is configured to mate with an outer surface of the corresponding connection element associated with the delivery dilator.

9. The circumscribing surface of the flange is having rounded outermost edges to reduce vascular trauma as the drivetrain is pulled through the patient's vascular system; 9. The blood pump assembly of claim 8, wherein the delivery expander is shaped and sized to be flush with an outer surface of the corresponding connection element associated with the delivery expander and to create at least a substantial vacuum with the outer surface.

10. the drivetrain includes an outer membrane, an inner membrane, and a kink-resistant element disposed between the outer membrane and the inner membrane along a first length of the drivetrain; The blood pump assembly of claim 8 , wherein the at least one barb is embedded in the inner membrane of the drivetrain.

11. The blood pump assembly of claim 10, wherein the kink-resistant element is a helically wound nitinol coil.

12. The blood pump assembly of claim 10 , wherein the outer membrane comprises a biocompatible and anti-thrombogenic material.

13. a radiopaque material is disposed between the outer membrane and the inner membrane along a second length of the drivetrain; The blood pump assembly of claim 10 , wherein the second length of the drivetrain is proximate to or at the distal end of the drivetrain.

14. The blood pump assembly of claim 13 , wherein the radiopaque material is a ring.

15. The blood pump assembly of claim 13 , wherein the radiopaque material has substantially the same thickness as the kink-resistant element.

16. a drive system having a distal end, a proximal end, an outer membrane, an inner membrane, and a central lumen; a kink-resistant element disposed between the outer membrane and the inner membrane along a first length of the drivetrain; The blood pump assembly of claim 1 , wherein a radiopaque material is disposed between the outer and inner membranes along a second length of the drivetrain.

17. 17. The blood pump assembly of claim 16, wherein the second length of the drivetrain is proximate to or at the distal end of the drivetrain.

18. The blood pump assembly of claim 16, wherein the radiopaque material has substantially the same thickness as the kink-resistant element.

19. The blood pump assembly of claim 16, wherein the radiopaque material is a ring.

20. The blood pump assembly of claim 1 , wherein the substantially cylindrical-conical proximal region of the balloon includes a tubular proximal end.

21. 2. The blood pump assembly of claim 1, wherein the balloon has a wall, the inner surface of the wall defining the elongated inflatable chamber, and the wall having a non-uniform thickness.

22. The drivetrain is rigid, 22. The blood pump assembly of claim 21, wherein the wall thickness of the balloon in the proximal region exceeds the wall thickness in the central region to minimize at least one of distortion or twisting in the proximal region of the balloon during operation of the blood pump assembly caused by stiffness of the drive system.

23. the balloon is sized and shaped to receive a blood pump support structure configured to counteract buoyant forces acting on the balloon when the blood pump assembly is implanted in the descending aorta; 22. The blood pump assembly of claim 21, wherein the wall thickness of the balloon in a portion of the distal region exceeds the wall thickness of the balloon in the central region, thereby minimizing distortion in the portion of the distal region of the balloon caused by the blood pump support structure during operation of the blood pump assembly.

24. 1. A blood pump assembly including a balloon defining an elongated inflatable chamber having an interior volume, the balloon having a distal region having a distal end, a central region, and a proximal region having a proximal end, the proximal end of the balloon having an opening; the interior volume of the elongated expandable chamber is between about 20 cc and 60 cc; the proximal region of the balloon is substantially cylindrically conical, the proximal region of the balloon tapers toward the proximal end of the balloon, the proximal region being approximately 15 to 30% of the length of the balloon; the central region of the balloon is substantially cylindrical with a substantially uniform outer diameter, the central region occupying approximately 55 to 65% of the length of the balloon; A blood pump assembly, wherein the distal region of the balloon is substantially cylindrically conical, the distal region of the balloon tapers toward the distal end of the balloon, and the distal region is approximately 15 to 30% of the length of the balloon.

25. 25. The blood pump assembly of claim 24, wherein the combined length of the proximal and central regions of the balloon is between about 100 mm and 220 mm.

26. 25. The blood pump assembly of claim 24, wherein the distal end of the balloon is one of a rounded shape, a nipple shape, and a bullet shape.

27. a drive system having a distal end, a proximal end, a central lumen configured to communicate a working fluid for delivery to or from the elongated expandable chamber, and a connecting element; the distal end of the drivetrain is coupleable to the proximal end of the balloon at the opening; the connecting element is disposed and secured to the proximal end of the driveline, and a separation force required to separate the connecting element from the proximal end of the driveline is greater than at least about 12 to 30 pounds; the connecting element being sized and shaped to receive a corresponding connecting element associated with a delivery dilator configured to pull the drive system through a patient's vasculature; 25. The blood pump assembly of claim 24, wherein the connection element comprises a conduit configured to allow the working fluid to pass through the conduit into and out of the central lumen.

28. the connection element is a hose barb fitting at least partially disposed within the driveline at the proximal end of the driveline; The hose barb fitting includes a longitudinal axis, a transverse axis, at least one barb on an outer surface, an inner surface defining a conduit, and a flange; the conduit is disposed substantially along the longitudinal axis; the at least one barb extends circumferentially outward from the inner surface substantially along the transverse axis, the at least one barb being sized to be embedded in an inner wall of the drivetrain; 28. The blood pump assembly of claim 27, wherein the flange is disposed at the proximal end of the hose barb fitting and extends circumferentially outward and substantially along the lateral axis, the flange is disposed external to the driveline and extends substantially to an outer edge of the proximal end of the driveline, and an outer surface of the flange is configured to mate with an outer surface of the corresponding connection element associated with the delivery dilator.

29. the drivetrain includes an outer membrane, an inner membrane, and a kink-resistant element disposed between the outer membrane and the inner membrane along a first length of the drivetrain; 29. The blood pump assembly of claim 28, wherein the at least one barb is embedded in the inner membrane of the drivetrain.

30. a radiopaque material is disposed between the outer membrane and the inner membrane along a second length of the drivetrain; 30. The blood pump assembly of claim 29, wherein the second length of the driveline is proximate to or at the distal end of the driveline.

31. 31. The blood pump assembly of claim 30, wherein the radiopaque material has substantially the same thickness as the kink-resistant element.

32. a drive system having a distal end, a proximal end, an outer membrane, an inner membrane, and a central lumen; a kink-resistant element disposed between the outer membrane and the inner membrane along a first length of the drivetrain; 25. The blood pump assembly of claim 24, wherein a radiopaque material is disposed between the outer and inner membranes along a second length of the drivetrain.

33. the second length of the driveline is proximate to or at the distal end of the driveline; the radiopaque material has the same thickness as the kink-resistant element; 33. The blood pump assembly of claim 32, wherein the radiopaque material is a ring.

34. 25. The blood pump assembly of claim 24, wherein the balloon has a wall, the inner surface of the wall defining the elongated inflatable chamber, and the wall having a non-uniform thickness.

35. The drive system has rigidity, 35. The blood pump assembly of claim 34, wherein the wall thickness of the balloon in a portion of the proximal region exceeds the wall thickness in the central region to minimize at least one of distortion or twisting in the portion of the proximal region of the balloon during operation of the blood pump assembly caused by stiffness of the drive system.

36. the balloon is sized and shaped to receive a blood pump support structure configured to counteract buoyant forces acting on the balloon when the blood pump assembly is implanted in the descending aorta; 35. The blood pump assembly of claim 34, wherein the wall thickness of the balloon in a portion of the distal region exceeds the wall thickness of the balloon in the central region, thereby minimizing distortion in the portion of the distal region of the balloon caused by the blood pump support structure during operation of the blood pump assembly.

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