Improved vascular access sheath and dilator assembly

Abstract

The present invention provides an improved vascular sheath and dilator assembly designed to enhance operability, accuracy, and safety during vascular access. [Solution] This assembly comprises a vascular sheath with side ports and a dilator featuring a closed distal end and an in-luminal deflection section. The deflection section smoothly reguides the guidewire toward the dilator's side port, which aligns with the side port of the vascular sheath, when the dilator is properly positioned within the vascular sheath, thereby facilitating precise navigation of the guidewire to the side vessels of the vascular structure. The assembly also incorporates visual markers in both the vascular sheath and the dilator to ensure accurate alignment of the side ports. These features, together, improve the overall effectiveness and safety of vascular procedures.

Description

Technical Field

[0001]

[0001] The present invention relates to a medical device, specifically, an assembly of a vascular access sheath and a dilator designed to facilitate vascular access procedures.

Background Art

[0002]

[0002] Vascular access is important for many medical procedures such as diagnostic angiography, angioplasty, and insertion of various intravascular devices. Conventional vascular sheaths and dilators are commonly used to access and maintain access to blood vessels. However, current devices lack features that facilitate precise navigation and alignment at the entry point required in certain situations.

[0003]

[0003] With the increasing number of patients having complex vascular histories, the demand for antegrade access to the femoral artery for ipsilateral lower extremity arterial intervention is increasing. Specifically, the number of patients who have previously undergone aortic bypass graft or endovascular aortic stent graft treatment and who are complicated by progressive peripheral arterial disease (PAD) is increasing. This trend indicates that the method of accessing the femoral artery for therapeutic procedures has changed decisively.

[0004]

[0004] Conventionally, in the initial approach to lower extremity arterial intervention, access has been made retrograde from the contralateral common femoral artery. This method is based on passing through the aortic bifurcation and migrating to the diseased limb to facilitate the intervention. However, in patients who have previously undergone endovascular aortic stent graft treatment or open aortic surgery using a Dacron bypass graft, this technique becomes infeasible. In such cases, antegrade access (ipsilateral approach) to the femoral artery on the same side as the lesion becomes an essential alternative means.

[0005]

[0005] Anterior access to the femoral artery is essential in certain clinical cases, but presents several technical challenges that make the procedure more complex compared to the conventional reverse approach. 1) The common femoral artery is often short in the portion available for catheter manipulation, which can limit maneuverability. The limited length of the artery makes it difficult to effectively advance and position the instrument. 2) During antegrade access, the initial guidewire is likely to enter the deep femoral artery (also known as the deep femoral artery) or its bifurcation instead of the target superficial femoral artery (also known as the femoral artery). Reguiding the guidewire to the femoral artery is a delicate operation that can be unreliable, lead to inaccessibility, or prolong the procedure time. 3) The femoral artery is often at an acute angle to the insertion point of the access needle. This anatomical challenge makes it difficult to secure a straight and stable route for the guidewire and catheter, increasing the risk of procedural complications. 4) Atherosclerotic disease at the origin of the femoral artery can cause stenosis or occlusion, obstructing the guidewire passage and complicating access. This makes initial access difficult and increases the likelihood of treatment failure.

[0006]

[0006] In recent years, interventional techniques have advanced to address these challenges. Imaging techniques such as intravascular ultrasound (IVUS) and optical coherence tomography (OCT) have improved, enabling visualization of vascular structures and assistance in guidewire placement. Furthermore, increased attention to training and simulation of antegrade access techniques allows practitioners to better prepare for the complexity of these procedures, reducing the likelihood of errors and improving overall outcomes. Despite these achievements, challenges remain. For example, advanced imaging techniques are costly and have limited availability, advanced skills are required to effectively use new tools and techniques, and access to complex anatomical structures remains difficult. While double-lumen catheters with deflection features on the guidewire exist, these catheters are not intended for initial access and are not suitable as vascular sheaths for entering the superficial femoral artery.

[0007]

[0007] Therefore, there is a need for a vascular sheath that provides a simple, reliable, and easy method for accessing the femoral artery via an antegrade approach. Furthermore, such a sheath should not only facilitate initial arterial access but also be designed to integrate seamlessly with another guide catheter. These guide catheters can re-guide the guidewire 180 degrees in the opposite direction, making them suitable for a variety of applications such as arteriovenous (AV) fistula imaging and interventions. This dual function is essential for improving the effectiveness of procedures that require precise access and navigation of complex vascular structures. [Overview of the project]

[0008]

[0008] The present invention provides an assembly of a vascular access sheath and dilator designed to facilitate vascular access procedures. According to one embodiment, one or more embodiments provide a vascular access sheath and dilator, each configured to have side ports designed to align with each other when the dilator is inserted into the vascular sheath. The assembly of the vascular sheath and dilator comprises a vascular sheath including a tubular structure having a proximal end, a distal end, and a lumen extending longitudinally between the two ends. The vascular sheath also has side ports located on the sides of the tubular structure, extending into the lumen. The assembly further comprises a dilator configured to be inserted into the lumen of the vascular sheath. The dilator consists of a cylindrical device having a proximal end, a distal end, and a lumen extending longitudinally along its length. The dilator also includes side ports located on the sides of the cylindrical device, which align with the side ports of the vascular sheath when the dilator is fully inserted. Furthermore, the distal end of the dilator is closed to prevent a guidewire from passing through the distal end and coming out.

[0009]

[0009] The dilator also has a deflection section in its lumen to facilitate the navigation of the guidewire through the dilator and the side ports of the vascular access sheath. Radiopaque markers are also integrated into the vascular sheath to indicate the location of the side ports. Markers placed outside both the vascular sheath and the dilator allow for proper alignment of the side ports.

[0010]

[0010] The present invention aims to improve the efficiency and safety of vascular access procedures through improved device alignment and navigation functions. This is not only convenient for healthcare providers and support staff, but more importantly, it enhances patient safety.

[0011]

[0011] Other aspects and advantages of the present invention will become apparent from the following description and the appended claims. [Brief explanation of the drawing]

[0012]

[0012] Embodiments of the present disclosure will be described in detail below with reference to the drawings. These and other features, aspects and advantages of the present disclosure will be better understood by referring to the following description, the appended claims and the appended drawings. The drawings described herein are for illustrative purposes only of selected embodiments and do not show all possible embodiments and are not intended to limit the scope of the present disclosure.

[0013] [Figure 1]

[0013] This is a diagram illustrating a conventional vascular sheath and dilator. [Figure 2]

[0014] This diagram illustrates the interaction between conventional vascular sheaths and dilators. [Figure 3]

[0015] This diagram illustrates cross-sections along the centerlines of conventional vascular sheaths and dilators. [Figure 4]

[0016] This diagram illustrates a guidewire positioned within a vascular sheath, passing through a conventional dilator. [Figure 5]

[0017] This is a perspective view of a vascular sheath and dilator assembly according to one embodiment of the present invention. [Figure 6]

[0018] This figure illustrates an assembly of a vascular sheath and dilator shown in Figure 5, which are interconnected, according to one embodiment. [Figure 7]

[0019] This figure illustrates a cross-section along the centerlines of a vascular sheath and a dilator according to one embodiment. [Figure 8]

[0020] This diagram illustrates a guidewire positioned within a vascular sheath, passing through a dilator, according to one embodiment. [Modes for carrying out the invention]

[0014]

[0021] The above summary of the invention, the modes for carrying out the invention, the claims below, and the accompanying drawings describe specific features of the invention (including method steps). The disclosure of the invention in this specification is understood to include all possible combinations of such specific features. For example, if a specific feature is disclosed in the context of a particular aspect or embodiment of the invention or a particular claim, that feature may, to the extent possible, be used in combination with and / or in the context of other particular aspects and embodiments of the invention, and also in the invention as a whole.

[0015]

[0022] As used herein, “comprises” and its equivalent grammatical expression mean that other components, ingredients, steps, etc., may optionally be present. For example, an article “comprising” (or which comprises) components A, B, and C may consist of components A, B, and C only (i.e., may consist only of these), or it may consist of components A, B, and C as well as one or more other components.

[0016]

[0023] Where a method comprising two or more prescribed steps is described herein, these prescribed steps may be performed in any order or simultaneously (unless the context excludes such possibility), and the method may include one or more additional steps performed before any of the prescribed steps, between two of the prescribed steps, or after all of the prescribed steps (unless the context excludes such possibility).

[0017]

[0024] In this specification, the term "at least" preceding a number indicates the starting point of a range that begins with that number (which may be an upper limit range or an upper limit range, depending on the specified variable). For example, "at least one" means one or greater than one. In this specification, the term "at most" preceding a number indicates the ending point of a range that ends with that number (which may be a lower limit range of one or zero, or an upper limit range, depending on the specified variable). For example, "at most four" means four or less than four, and "at most 40%" means 40% or less than 40%. In this specification, when a range is defined as "(first number) to (second number)" or "(first number) ~ (second number)", it means a range where the lower limit is the first number and the upper limit is the second number. For example, 25 to 100 mm means a range where the lower limit is 25 mm and the upper limit is 100 mm.

[0018]

[0025] In the following explanation, certain terms and their derivatives may be used for convenience of reference, but these are not limiting. For example, terms such as "up," "down," "left," and "right" refer to directions in the drawings being described, unless otherwise specified. Similarly, terms such as "inward" and "outward" refer to directions toward and away from the geometric center of a device or range and a designated portion thereof, respectively. Unless otherwise specified, singular expressions include plural forms, and vice versa.

[0019]

[0026] As used herein, the term "connected" may mean a direct connection or an indirect connection through one or more components.

[0020]

[0027] The present disclosure generally describes one or more embodiments for an assembly of a vascular sheath and a dilator designed to facilitate vascular access procedures. Vascular access is an important element in various medical procedures such as catheter insertion, angiography, and endovascular surgery. Conventional vascular sheaths and dilators, such as those shown in FIGS. 1 through 4, typically lack a mechanism for accessing collateral or branch vessels that branch off from the main vessel, which can be inefficient and may cause complications during the procedure. The present invention solves these problems by providing a vascular sheath and a dilator having side ports that align during assembly, promising efficient treatment accuracy. The present invention includes a vascular sheath having side ports, a dilator having a lumen with side ports and a deflection portion, and a radiopaque marker indicating the position of the side ports on the vascular sheath. Further, the markers on the vascular sheath and the dilator are designed such that when the two markers are aligned during insertion of the dilator into the vascular sheath, the side ports on both components are aligned. The present invention aims to improve the efficiency and safety of vascular access procedures by improving device alignment and navigation functions. The embodiments described herein may be used for multiple purposes, including but not limited to improving the accuracy and safety of vascular access. This will be described in more detail with reference to the drawings.

[0021]

[0028] Referring to the drawings, FIGS. 1 through 4 show an assembly 500 of a prior art vascular sheath and dilator. This assembly consists of a vascular sheath 510 and a corresponding dilator 520, both designed for basic vascular access procedures. The vascular sheath 510 is a tubular structure having a proximal end 512 and a distal end 514 and a longitudinally extending lumen 516 between the two ends. The lumen 516 is configured to receive the dilator 520 during insertion into the vascular structure. The distal end 514 of the sheath 510 is typically tapered to facilitate smooth entry into the blood vessel and minimize damage to the vessel wall.

[0022]

[0029] A conventional dilator 520 is intended to be inserted into the lumen 516 of a vascular sheath 510 and has a proximal end 522 and a distal end 524, with a lumen 526 extending along its entire length. The distal end 524 of the dilator 520 is designed to be open so that a guidewire 600 can be passed through the open distal end 524 and inserted into the vascular structure during the procedure. The open distal end 524 helps guide the vascular sheath 510 to a predetermined position in the vascular system by allowing the guidewire 600 to pass through the dilator 520 and enter the target vessel.

[0023]

[0030] Assembly 500 is primarily designed to provide a conduit for introducing a guidewire into the vascular system. While this conventional design ensures structural integrity and facilitates basic vascular access, it lacks another feature that would enable maneuverability within the sheath. The conventional vascular sheath and dilator assembly 500 has certain limitations, particularly in procedures requiring access to branch vessels branching from a main vessel. In such cases, the physician must rely heavily on manual manipulation of the guidewire 600 as it passes through the open distal end 524 of the dilator 520 in order to navigate it from the main vessel to the branch vessel.

[0024]

[0031] Conventional assembly 500 lacks special features to assist in precise positioning, forcing physicians to rely on a trial-and-error approach. This process often involves repeatedly advancing and retracting the guidewire 600, and rotating and repositioning the entire assembly 500 to locate the opening of the side vessel. The lack of visual or positional cues from the assembly 500 forces physicians to rely on tactile feedback and imaging techniques, which can be time-consuming and inaccurate.

[0025]

[0032] As shown in Figures 5 to 8, one or more embodiments of the vascular sheath and dilator assembly 100 of the present invention address the limitations of prior art devices. The vascular sheath and dilator assembly 100 comprises a vascular sheath 110 and a dilator 120. The term “vascular sheath and dilator assembly” may also be called “assembly,” and regardless of any specific terminology used throughout this specification, it encompasses all components described herein, such as the vascular sheath, dilator, and any related parts or features.

[0026]

[0033] Specifically, the assembly 100 is configured to facilitate the precise navigation of the guidewire 600 to the side branch vessels branching from the main vessel, thereby improving the accuracy, efficiency, and safety of the procedure.

[0027]

[0034] The vascular sheath 110 is a tubular structure having a proximal end 112, a distal end 114, and a lumen 116 extending longitudinally between them. The lumen 116 is configured to receive a dilator 120 to facilitate vascular access procedures. In this specification, the term “vascular sheath” is also referred to as “vascular access sheath,” “introducer sheath,” “access sheath,” or simply “sheath,” and all of these terms refer to the same component throughout this specification.

[0028]

[0035] The vascular sheath 110 further has a side port 118 strategically positioned between the proximal end 112 and the distal end 114. This side port 118 is an opening on the side of the vascular sheath 110 and is specifically configured to allow controlled access to a side branch or vessel. In other words, the position of the side port 118 is optimized to enhance the controllability of the procedure, such as access to a side branch vessel during a vascular access procedure.

[0029]

[0036] Furthermore, the vascular sheath 110 is provided with a radiopaque marker 140. The radiopaque marker 140 is positioned close to the side port 118 of the vascular sheath. This alignment allows the operator to accurately locate the side port 118 using imaging techniques and position it in a side branch vessel, thereby improving the safety and precision of the procedure. The radiopaque marker 140 ensures that the side port 118 is reliably positioned relative to anatomical structures during insertion and positioning within the vascular system.

[0030]

[0037] The dilator 120 is a cylindrical device designed to be inserted into the lumen 116 of a vascular sheath 110. The dilator 120 has a proximal end 122, a distal end 124, and a lumen 126 extending longitudinally between the two ends. The lumen 126 is sized to allow a guidewire, fluid, or other medical instrument to pass through during the procedure as needed. The dilator 120 of the present invention features a closed distal end 124, in contrast to the open distal end 524 of the conventional lumen 526 shown in Figures 1 to 4.

[0031]

[0038] The dilator 120 has a side port 128 located near its distal end 124. The side port 128 is also an opening on the side of the dilator 120 and is positioned to align with the side port 118 of the vascular sheath 110 when the dilator 120 is fully inserted into the sheath 110. This alignment is facilitated by the design of the dilator 120, which includes a deflection section 127 located within the lumen 126 near the side port 128. The deflection section 127 is specifically designed to guide and re-direct the guidewire 600 laterally through the side port 128 to the aligned side port 118 of the vascular sheath 110.

[0032]

[0039] The deflection section 127 located within the lumen 126 of the dilator 120 is a key feature of the present invention and is designed to facilitate the smooth and controlled deflection of the guidewire 600 toward the side ports 128 and 118. The design of the closed distal end 124 enhances the structural integrity of the dilator 120, preventing the guidewire 600 from unintentionally dislodging from the distal end 124 and ensuring that the guidewire 600 is reliably and precisely guided through the side ports 128 into the branch vessels. The deflection section 127 is integrally formed within the lumen 126 of the dilator 120 and is located close to the side ports 128. This deflection section 127 is characterized by a specially rounded, gently sloping, smooth surface that guides the guidewire 600 toward the side ports 128 from the central axis of the lumen 126, without causing abrupt changes in direction or excessive friction.

[0033]

[0040] The deflection section 127 is set with a gentle curve. This smooth curvature allows the guidewire 600 to transition seamlessly and be reguided laterally as it advances through the lumen 126. The absence of sharp edges or steep angles minimizes the risk of the guidewire 600 twisting or being damaged, promoting stable and controlled movement within the lumen. The smooth surface of the deflection section 127 is further optimized to reduce resistance, allowing the guidewire 600 to glide effortlessly along its curvature. Once the guidewire 600 reaches the deflection section 127, the gentle slope allows it to gradually move towards the side port 128, facilitating a smooth and uninterrupted passage from the side port 128 to the aligned side port 118 of the vascular sheath 110.

[0034]

[0041] This design of the deflection section 128 allows the guidewire 600 to maintain integrity and a precise path when transitioning from the dilator 120 to a side vessel. Thus, the deflection section 127 plays a crucial role in improving the overall performance of the assembly, providing a reliable and efficient means of guiding the guidewire 600 while minimizing operator effort and maximizing procedure accuracy.

[0035]

[0042] Furthermore, the vascular sheath 110 and the dilator 120 are equipped with a first marker 119 and a second marker 129, respectively. The dilator 120 has the second marker 129 at its proximal end 122. When the dilator 120 is properly aligned within the vascular sheath 110, the second marker 129 is configured to coincide with the first marker 119 on the vascular sheath 110.

[0036]

[0043] These markers 119, 129 may be visual markers such as lines, arrows, or colored indicators. These allow for clear and immediate visual confirmation of proper alignment. Alternatively, the markers 119, 129 may be tactile markers such as raised surfaces, protrusions, or notches. These allow the user to sense when the dilator and sheath are properly aligned. This is particularly useful for users who rely on sensory feedback during insertion. In another configuration, the markers 119, 129 may take the form of mechanical features such as notches or protrusions. When the dilator 120 is inserted into the vascular sheath 110, these mechanical features align properly when they engage with each other. This allows the side ports 118, 128 to align accurately, which is essential for accessing the side vessels. If the features do not align properly, the side ports remain misaligned.

[0037]

[0044] The alignment of the side ports 118 and 128 in this manner allows for precise control during the procedure, guiding the guidewire 600 into the side vessel while minimizing the risk of displacement. By incorporating markers 119 and 129, whether visual, tactile, or mechanical, the device reliably and securely orients the dilator 120 within the vascular sheath 110, enhancing both ease of use and procedure safety.

[0038]

[0045] The combination of these feature components—side ports 118, 128, markers 119, 129, and deflection section 127—creates a robust and reliable system for vascular access, enabling controlled and precise guidewire placement and positioning, thereby enhancing both the accuracy and safety of the procedure.

[0039]

[0046] During the vascular access procedure, the physician advances the guidewire 600 within the lumen 126 of the dilator 120. As the guidewire 600 approaches its distal end 124, it encounters a deflection section 127. The deflection section 127 smoothly reguides the guidewire 600 toward the side port 128 of the dilator 120. After exiting the side port 128, the guidewire 600 passes through the aligned side ports 118 of the vascular sheath 110 and is guided toward a side branch vessel branching off from the main vessel.

[0040]

[0047] This guide deflection of the guidewire 600 offers several important advantages. The alignment of the side ports 118 and 128, combined with the action of the deflection section 127, reliably and accurately guides the guidewire 600 into the side vessel. This eliminates the trial-and-error operation commonly required in conventional assemblies lacking such features.

[0041]

[0048] Because the Guidewire 600 can always be accurately guided to the side branch vessel in a single attempt, the overall procedure time is significantly reduced. Physicians can efficiently position the Guidewire 600 without repeated adjustments, allowing for more efficient procedures.

[0042]

[0049] The controlled deflection of the guidewire 600 to the side vessel reduces the need for extensive manipulation, thus minimizing the risk of damaging the vessel wall. This is particularly advantageous in procedures involving delicate or tortuous vascular structures, where the risk of damage is higher.

[0043]

[0050] The aligned side ports 118 and 128 also facilitate targeted delivery of fluids and contrast agents directly to side vessels. This feature is important in procedures requiring precise administration of therapeutic agents or imaging contrast agents, further improving the outcomes of the procedure.

[0044]

[0051] The vascular sheath and dilator assembly 100 of the present invention offers a superior solution to the limitations of prior art devices. By incorporating side ports 118, 128 together with deflection section 127, the present invention enables precise and controlled access to side branch vessels, thereby increasing procedure accuracy, reducing time, and minimizing the risk of complications. The enhanced functionality of this assembly represents a significant advance in the field of vascular access and brings substantial benefits to both physicians and patients. Many other advantages and applications are provided by one or more systems described herein.

[0045]

[0052] The corresponding structures, materials, actions, and equivalents of all means-plus-function or step-plus-function elements in the following claims shall include any structures, materials, or actions that, in combination with any other element specifically claimed, perform that function. The description of the invention is illustrative and descriptive, and is not exhaustive or limited to the disclosed forms of the invention. Many variations and modifications will be apparent to those skilled in the art without departing from the scope and spirit of the invention.

[0046]

[0053] The embodiments have been selected and described in such a way as to best illustrate the principles and practical applications of the present invention, and so that a person skilled in the art may understand the invention for various modified embodiments suitable for specific intended applications. The invention may be practiced by one or more embodiments described herein with modifications and changes within the spirit and scope of the appended claims. Therefore, this specification is not limiting to the invention but is exemplary.

Claims

1. It is a vascular sheath, A tubular structure having a proximal end, a distal end, and a lumen extending longitudinally between them, A vascular sheath including a side port located on the side of the tubular structure and extending into the lumen of the tubular structure, A dilator configured to be inserted into the lumen of the vascular sheath, A cylindrical device having a proximal end, a distal end, and a lumen extending longitudinally between them, A side port located on the side of the cylindrical device and extending into the lumen of the cylindrical device, wherein the side port aligns with the side port of the vascular sheath when the dilator is fully inserted into the sheath, A dilator including a closed distal end designed to prevent the guidewire from slipping out of the distal end of the dilator, A vascular sheath and dilator assembly comprising [the specified features].

2. The assembly according to claim 1, wherein the vascular sheath comprises a radiopaque marker positioned adjacent to the side port of the vascular sheath.

3. The assembly according to claim 1, wherein the dilator further comprises a deflection portion in the lumen adjacent to the side port of the dilator, the deflection portion having a surface for guiding a guidewire laterally from the central axis of the lumen through the side port of the dilator and into the aligned side ports of the vascular sheath.

4. The assembly according to claim 3, wherein the deflection portion of the dilator is characterized by a gently sloping, smooth surface that minimizes abrupt changes in direction and reduces friction, thereby allowing the guide wire to slide smoothly toward the side port of the dilator.

5. A first marker is provided on the proximal end of the vascular sheath, and a second marker is provided on the proximal end of the dilator. The assembly according to claim 1, wherein when the dilator is appropriately positioned within the vascular sheath, the second visual marker on the dilator is positioned to align with the first visual marker on the vascular sheath, thereby ensuring that the side port is accurately aligned.

6. The assembly according to claim 5, wherein the first marker and the second marker are selected from the group consisting of visual markers, tactile markers and mechanical markers, and the mechanical marker includes corresponding notches or projections that allow the dilator to be inserted into the vascular sheath and ensure the side port is aligned by fitting the mechanical features of each other.

7. The assembly according to claim 1, wherein the side ports are aligned such that the guide wire is guided laterally from the lumen of the dilator through the side port to the side port of the vascular sheath, thereby facilitating precise access to a side branch vessel branching from a main vessel.

8. The assembly according to claim 1, wherein the side ports of the vascular sheath and the side ports of the dilator are configured to facilitate the positioning of the guidewire to the side branch vessel.

9. A method for accessing blood vessels using the assembly described in claim 1, Insert the vascular sheath into the blood vessel, and align the side port of the vascular sheath with a side branch vessel branching from the main blood vessel. Insert the dilator into the lumen of the vascular sheath until the side port of the dilator aligns with the side port of the vascular sheath, The guide wire is advanced through the lumen of the dilator, A method comprising guiding the guidewire through the side port of the dilator and laterally into the aligned side ports of the vascular sheath, thereby guiding the guidewire into a side branch vessel branching from the main vessel.

10. The method according to claim 9, wherein the guide wire is advanced through the dilator until it engages with a deflection portion within the lumen of the dilator, the deflection portion being characterized by a gently sloping smooth surface so that the guide wire can slide smoothly toward the side port of the dilator.

11. The method according to claim 9, wherein the closed distal end of the dilator prevents the guidewire from coming out of the distal tip, ensuring accurate placement of the guidewire and minimizing the risk of unintended guidewire dislodgement during the procedure.

12. It is a vascular sheath, A tubular structure having a proximal end, a distal end, and a lumen extending longitudinally between both ends, A side port located on the side of the tubular structure and extending into the lumen of the tubular structure, A vascular sheath including a first marker positioned on the proximal end aligned with the side port, A dilator configured to be inserted into the lumen of the vascular sheath, A cylindrical structure having a proximal end, a distal end, and a lumen extending longitudinally between both ends, The side of the cylindrical structure has a side port extending into the lumen of the cylindrical structure, which aligns with the side port of the vascular sheath when the dilator is fully inserted into the vascular sheath. A dilator including a second marker on the proximal end of the dilator that is aligned with the side port of the dilator, A vascular sheath and dilator assembly comprising [the specified features].

13. The assembly according to claim 12, wherein when the dilator is inserted into the vascular sheath, the second marker on the dilator aligns with the first marker on the vascular sheath, so that the dilator and the side port of the vascular sheath are reliably and accurately aligned.

14. The assembly according to claim 12, wherein the first marker and the second marker are selected from the group consisting of visual markers, tactile markers and mechanical markers, and the mechanical marker includes corresponding notches or projections that allow the dilator to be inserted into the vascular sheath and ensure the side port is aligned by fitting the mechanical features of each other.

15. The assembly according to claim 12, wherein the dilator further comprises a deflection portion in the lumen adjacent to the side port of the dilator, the deflection portion having a surface for guiding a guidewire laterally from the central axis of the lumen through the side port of the dilator to the aligned side port of the vascular sheath.

16. The assembly according to claim 15, wherein the deflection portion of the dilator is characterized by a gently sloping smooth surface that minimizes abrupt changes in direction and reduces friction, thereby allowing the guide wire to slide smoothly toward the side port on the dilator.

17. The assembly according to claim 12, wherein the side ports on the dilator and the side ports on the vascular sheath are aligned such that a guidewire is laterally guided from the lumen of the dilator through the side ports of the dilator to the side ports of the vascular sheath, thereby facilitating precise access to a side branch vessel branching from a main vessel.

18. A method for accessing blood vessels using the assembly described in claim 12, Insert the vascular sheath into the blood vessel, and align the side port of the vascular sheath with a side branch vessel branching from the main blood vessel. Insert the dilator into the lumen of the vascular sheath until the side port of the dilator aligns with the side port of the vascular sheath, The guide wire is advanced through the lumen of the dilator, A method comprising guiding the guidewire through the side port of the dilator and laterally into the aligned side ports of the vascular sheath, thereby guiding the guidewire into a side branch vessel branching from the main vessel.

19. The method according to claim 18, wherein the guide wire is advanced through the dilator until it engages with a deflection portion within the lumen of the dilator, the deflection portion being characterized by a gently sloping smooth surface so that the guide wire can slide smoothly toward the side port of the dilator.

20. The method according to claim 18, wherein the alignment of the first and second markers on the proximal ends of the vascular sheath and the dilator ensures proper positioning of the side ports of the dilator relative to the side ports of the vascular sheath for accurate guidewire placement.

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