Distal radial access in interventional cardiology: technique, pitfalls and recommendations

Introduction

To date, 14 years have passed since distal radial access (DRA) was first described in interventional cardiology (1) and 8 years since its widespread use (2). Subsequently, several large registries have confirmed the feasibility and safety of DRA in different clinical scenarios (3-10), demonstrating advantages such as a low incidence of radial artery occlusion (RAO), short hemostasis time, high patient and operator comfort, and low rates of access-related complications, even in emergency scenarios (11). However, some randomized trials have shown controversial results on the rate of RAO and a higher incidence of crossover compared to traditional transradial access (TRA) (12-15). Conversely, meta-analyses carried out to date confirm most of the advantages of DRA, with a consistently higher crossover rate (16-19). As a result, DRA has been extended to noncoronary procedures (20-23). Although DRA is gaining popularity, it faces specific challenges that have decelerated its integration into clinical practice. These challenges are likely due to the lengthy learning curve associated with the technique, which can be attributed to the anatomical characteristics of the distal radial artery (DRart) and its relationship to the anatomical snuffbox (AS), which could make access more difficult (24-26). The objective of this review is to provide interventional cardiologists with a comprehensive step-by-step guide to DRA. This document will address essential aspects, including anatomical fundamentals, criteria for patient and material selection, procedural techniques, and post-procedure management. The purpose is to adequately equip operators with the requisite expertise and resources to develop proficiency in this approach and successfully navigate the associated learning curve.

Anatomy

A complete understanding of the anatomy of the radial artery and AS is essential for the development of DRA, as it allows accurate identification of the DRart and precise location of adjacent anatomical structures that interact in this approach (25-28) (Figure 1).

Figure 1 Image of the left hand and its relationship to the radial artery and visible anatomical structures associated with distal radial access. The puncture sites used in the distal radial access are highlighted, in the area of the AS (yellow arrow) and in the dorsal area, distal to the extensor pollicis longus tendon (white arrow), which forms the medial side of the AS (triangle with dotted lines). AS, anatomical snuffbox; CV, cephalic vein; DPA, deep palmar arch; DRart, distal radial artery; EPB, extensor pollicis brevis; EPL, extensor pollicis longus; PRart, proximal radial artery; SPA, superficial palmar arch.

Course of the radial artery

The radial artery descends laterally in the forearm to the wrist, where it lies medial to the carpi radialis flexor tendon and the anterior border of the radial bone, the usual puncture site for TRA (25-27,29,30). Beyond this location, the superficial palmar branch arises and connects ventrally with the corresponding branch of the ulnar artery, forming the superficial palmar arch (SPA) (25-27,29,30). The proximal radial artery (PRart) then runs dorsally over the carpus (scaphoid and trapezium) and under the tendons of the abductor pollicis longus (APL) and the extensor pollicis brevis (EPB) (lateral) and extensor pollicis longus (EPL) (medial), which form the vertices of AS, to continue dorsally into the first intermetacarpal space, medially in the first dorsal interosseous muscle and returning to the palmar region, where it anastomoses with the deep palmar artery of the ulnar artery, forming the deep palmar arch (DPA), located under the tendon sheath of the flexor digitorum muscles (25-27,29,30). The SPA has branches exclusively from its convex surface, while the DPA has ascending, descending, and perforating branches, both showing a high degree of anatomical variability (25). Together, they create a complex anastomotic network that ensures that the hand receives adequate blood supply (25).

Anatomical consideration for distal radial access

To better identify AS, it is recommended that the patient is placed in a neutral position and asked to lift the thumb so that the tendons that define the medial and lateral borders of AS can be observed (25-27). Puncture in the DRA can be performed at two sites where the DRart can be palpated, in the AS and in the dorsal region of the hand, just after the DRart has crossed the EPL tendon (25-27) (Figure 1). At both puncture sites, the DRart passes over a bone base, usually the scaphoid for the first site and the trapezium for the second (25-27). These anatomical references are important because they allow for more effective hemostasis (25-27).

Anatomy of the anatomical snuff box by Doppler ultrasound (US)

It is recommended to familiarize yourself with the anatomy of AS and the course of DRart in the hand by Doppler US (Figure 2).

Figure 2 Anatomy of the distal radial artery by Doppler ultrasound. White arrow, proximal radial artery; yellow arrows, distal radial artery. APL, abductor pollicis longus tendon; CV, cephalic vein; EPB, extensor pollicis brevis tendon; EPL, extensor pollicis longus tendon; MB, metacarpal bones; RB, radial bone; RN, radial nerve; SB, scaphoid bone; TB, trapezium bone.

Due to the superficiality of the anatomical structures in the AS, a linear probe with an ultrahigh frequency of 6–18 MHz is recommended (28,31). Once the gel has been applied to the probe, it is gently placed and aligned perpendicularly in the first dorsal web space (intermetacarpal space), where the DRart and the branches of the metacarpals and DPA can be located (28). The DRart is deep at this site and is surrounded by the first and second metacarpals. A proximal screening is performed where the DRart becomes progressively more superficial until it reaches the position where it is on the trapezium bone, which is one of the puncture sites for punction in the DRA (28). At this point, the EPL tendon can be seen medially, as well as the cephalic vein and the branches of the radial nerve (10,28,31). The probe is then directed towards the AS, where the classic puncture site is located in the DRA. At this point, the DRart is still superficial and its course continues over the base of the trapezium and, on more proximal axes, over the scaphoid, where the DRart begins to deepen toward the palmar part of the wrist. On this axis, the EPB and APL tendons are also observed laterally and the EPL medially, as well as the cephalic vein and the branches of the radial nerve (25,28).

The anatomy of AS is new to most operators and the way to learn about it is through US, which involves overcoming a learning curve for its use in DRA. Operators who perform routine US-guided punctures of the different accesses in interventional cardiology will find it easier to overcome this curve. However, those who have not experienced its use should have patience and assurance that in some cases they will be able to develop the skills to identify the anatomical landmarks of AS. This will allow for the improvement of the success of DRart punctures and thus also reduce access-related complications. Therefore, it is highly recommended that the first cases be performed under US guidance (10,26,28,29).

Patient selection

Optimal patient selection is fundamental to the success of DRA. Essential parameters include the presence of a palpable pulse in the AS and an adequate diameter of the radial artery evaluated by the US (26,28,29,31). A minimum luminal diameter of approximately 1.8 mm is recommended for the acceptance of coronary catheters. Diameters less than this threshold increase the risk of access failure, radial artery spasm (RAS), and access-related complications (10,26,28). Severe arterial tortuosity can contradict DRA due to the complexity of catheter navigation, increasing the probability of procedural failure and arterial injury (31). The presence of a preexisting proximal or distal RAO contraindicates DRA. Arterial patency can be assessed using the Allen or Barbeau test, but these have been shown to be inconsistent predictors of the risk of hand ischemia (26,28). The use of Doppler US may be particularly useful in these cases, to assess the presence of arterial tortuosity and to evaluate patients with weak or absent arterial pulse (10,28,29,31). There are factors associated with the presence of an unfavorable pulse that do not necessarily imply RAO, such as arterial hypotension, small artery size, and depth of the DRart (10,26). The DRA puncture site is 5 cm distal to the conventional TRA puncture site, which could result in an inadequate length of coronary angiography catheters (commonly sized at 100 cm), in cases such as patients of taller stature, in the presence of pronounced tortuosity of the subclavian artery, or in scenarios involving ascending dilated aortas (10,26,32). Nonetheless, this occurrence is infrequent and usually does not hinder the performance of the coronary procedure. Consequently, it is recommended to maintain a limited inventory of 110-cm catheters to prevent the necessity of crossover in situations where continuation of the procedure is rendered unfeasible (10,32).

Pre-procedure preparation

Palpation of the DRart

Palpation of the DRart continues to be an essential skill; however, the integration of US guidance is progressively acknowledged as a fundamental complement, especially in patients with complex anatomical features. Palpation enables operators to assess the pulse intensity and approximate the course of the artery; however, anatomical variations or decreased pulse strength may present challenges for this methodology (10,26). The intensity of the DRart pulse is used, evaluated on a scale ranging from 1 to 4, where 1 indicates an absence of pulse, 2 denotes a weak pulse, 3 represents a normal pulse, and 4 corresponds to a strong pulse (10).

Pre-procedure US evaluation

A pre-procedure US evaluation is recommended before the puncture attempt to assess patency, size, and depth of DRart and PRart, presence of arterial calcification, anatomical landmarks surrounding DRart in AS, and arterial tortuosity (7,10,26-29,31).

The US evaluation is performed from distal to proximal, starting in the first dorsal web space of the hand, continuing towards the AS (Video 1), and then following the entire PRart course to its anastomosis with the brachial artery (Video 2) (26,28).

Patient positioning

The right or left DRA is equally valid for coronary procedures and can be selected according to the operator’s preference and the specific conditions of each case (7). For the right DRA, the ipsilateral hand should be in a natural position such that the thumb is flexed and the wrist shows a slight ulnar deviation (Figure 3A-3D) (7,26,27). On the contrary, when performing a left DRA, the ipsilateral hand should be comfortably oriented toward the right groin in a pronated position, ensuring that the thumb remains flexed, the wrist exhibits a slight ulnar deviation, the arm is fully abducted, and the wrist is hyperextended to a degree ranging from approximately 30 to 45 degrees (2,7,28). Note that the left DRA is more comfortable for the operator compared to the conventional left TRA. The improvement of the hyperextension position can involve the placement of a specially designed arm board or rolled towel under the wrist to optimize the exposure to AS (Figure 3E-3G) (29). Accurate arm and wrist alignment is imperative as it minimizes the potential for arterial twisting and simplifies access to the DRart, thus increasing the likelihood of success in the first attempts. Additionally, it is of utmost importance to prioritize patient comfort, as involuntary movements could potentially compromise the procedure.

Figure 3 Position of the patient in the distal radial access left and right. (A) Position of the right hand for puncture, resting on a gauze package, where hyperextension of the wrist is observed. (B,C) Right-hand position supported with the designed arm board, with which the position is more precise. (D) Final position of the right hand once the sterile drape is in place. (E,F) The left hand positioned for puncture, using the usual technique (E) and supported by the designed arm board (F), with which the position is more precise and the comfort is greater for the patient. (G) Final position of the left hand after placing the sterile drape, highlighting that the hole used is the one corresponding to the left femoral access, for better organization of the work area.

Puncture techniques

Selection of the introducer sheath and puncture kit

The curved course of the DRart in the AS, as it turns ventral to its usual position in the forearm, and the smaller diameter of the DRart than the PRart make the selection of the introducer sheath important in this approach (26). This is why hydrophilic coated thin-walled sheaths with sufficient radial strength are recommended to avoid kinking. Intravascular imaging has shown that introducer sheaths with hydrophilic coatings can potentially mitigate RAS and dissection by offering protective coverage throughout access and manipulation (33).

In most DRA procedures, a 5 or 6-French (F) sheath is considered suitable. It must be considered to select the smallest practical size to minimize arterial wall trauma (sheath/DRart ratio <1) (7,9,10,26,27,31).

In scenarios requiring larger bore guiding catheters, such as during complex percutaneous coronary interventions, the use of sheathless guiding catheters, slender sheath technologies, or dedicated systems that convert standard 7F guiding catheters into sheathless configurations (e.g., the Railway Sheathless Access System, Cordis, USA) offers a practical strategy to minimize the outer diameter of the access system while preserving an adequate inner lumen for device delivery (34-37). Alternatively, dedicated thin-walled 7F introducer sheaths can be considered in patients with favorable anatomy of the DRart. In particular, a DRart diameter threshold of 2.4 mm has been identified as a negative predictor of RAO when using large-bore catheters, including 8F balloon guide catheters (38). Therefore, pre-procedure US evaluation is essential to guide patient selection and optimize 7F access safety through DRA (38,39).

Introducer sheath kits normally contain puncture needles and mini guidewires (Figure 4). 21-gauge needles are recommended for this approach for greater puncture precision, especially in small arteries, which can reduce the incidence of radial spasm (26). Mini guidewires generally measure 45 cm in length and are accessible in diameters of 0.018”, 0.021”, and 0.025”. Their production involves a range of materials, such as stainless-steel mandrels, spring-coiled configurations, nitinol-palladium alloys, or plastic-coated designs. The selection of puncture kits is determined by the preferences of the operator and the availability at the center.

Figure 4 Equipment used for ultrasound-guided distal radial artery cannulation and sheath insertion. (A) Setup for the DRA puncture, including US probe, introducer sheath, 21-G needle, micro guidewire, and local anesthesia. (B,C) Comparison of the sheaths and needles of the Prelude [1] and Radifocus [2] introducers. (D) Different guidewires used for the distal radial access, spring-coiled wire (white arrow) and stainless-steel wire (yellow arrow). DRA, distal radial access; US, ultrasound.

Puncture of the DRart

An anterior single-wall puncture is advised for both puncture techniques. Conversely, the double-wall puncture technique involves penetrating both the anterior and posterior walls of the DRart, which can increase the risk of puncture-related complications and patient discomfort due to potential contact with the underlying bone surface (26,31).

US-guided puncture

Once the puncture site is located, US-guided infiltration is recommended to avoid pain in contact with the carpal bone periosteum by applying 3–8 mL of 2% mepivacaine (10,26,28,29). The probe is positioned at the designated puncture site, in the axial or longitudinal plane. A 21-gauge needle is utilized, angled approximately 30° for a dorsal puncture and between 30–60° within the AS, where the DRart can be located at a higher depth. Both planes are viable; however, longitudinal puncture presents a steeper learning curve due to the necessity for the needle to remain within the narrow US beam for continuous visibility (28). During an axial plane puncture, only the segment of the needle that intersects the beam is visible (Video 3). A hybrid approach involves scanning in the longitudinal plane and transitioning to an axial view as the needle nears the artery to corroborate the anterior puncture. The needle should be introduced into the skin close to the probe to improve visualization (Figure 5). Gentle pressure is advised with the probe to prevent compression of superficial structures, and probe movements should be restricted to in-plane tilting rather than sliding, to preserve alignment and puncture precision (10,26,28,29). US-guided puncture of the DRart can be performed with or without color Doppler. In the absence of color Doppler, the needle is advanced under real-time visualization until tenting of the anterior wall is observed. Successful entry into the lumen is confirmed by continuous blood flow or pulsatile backflow through the needle hub, at which point the mini guidewire can be introduced (26,28). When color Doppler is used, needle entry into the artery is indicated by the appearance of an aliasing signal within the vessel, confirming intraluminal placement (Video 4).

Figure 5 Puncture technique blind by palpation (left) and ultrasound-guided (right). (A,B) Application of anesthesia with both techniques. (C,D) Palpation and ultrasound-guided puncture of the distal radial artery. (E) Sharp needle angulation and rotation on its own axis for correct guidewire advance. (F) Final position of the introducer sheath in the anatomical snuffbox.

Occasionally, despite continuous blood flow, the guidewire may not be able to advance towards the needle and the DRart; this could be due to a straighter cannulation of the needle relative to the DRart or the bevel position, so it is recommended to rotate the needle on its own axis and tilt the needle at a sharper angle (Figure 5E), which may resolve this situation (10,26-29,31). The US-guided dynamic tip positioning technique is an alternative method of puncture. First, the puncture site is identified with the US probe, then the needle is punctured through the skin, and the needle remains fixed at that level. Next, the probe is moved toward the needle until the hyperechoic tip is observed and the needle is advanced toward the artery until it disappears from the US plane. The advance is then stopped and the position of the probe is modified until the hyperechoic point of the tip is located. This movement is repeated until the needle punctures the DRart. This technique can be modified to avoid missing the most appropriate puncture site by tilting the probe on its own axis until the tip of the needle is located and adjusting this tilt as the needle is inserted into the artery (Figure 6).

Figure 6 Alternative technique for ultrasound-guided arterial puncture. From top to bottom, progressive angulation of the ultrasound probe on its own axis (left), the course of the needle (right, arrows) from the most superficial to contact with the distal radial artery and the tenting observed during its puncture are observed.

The correct position of the guidewire can most often be confirmed by US fluoroscopy before the advance to the introducer sheath (Figure 7 and Video 5), as the mini-guidewire may occasionally be directed toward the SPA or metacarpal branches, requiring an adjustment to align its orientation with the proper PRart. Finally, the introducer sheath is placed. Although some authors advocate for a small skin incision to facilitate the insertion of the introducer sheath (26,28), this carries the risk of an overly deep cut, which could injure superficial anatomical structures. In most cases, sheath advancement, particularly with hydrophilic sheaths, can be performed without difficulty. If resistance is encountered, it can usually be overcome with the aid of the dilator. Therefore, routine skin incisions are not recommended for DRA (7,9,10).

Figure 7 Fluoroscopic and ultrasound guidance verification. (A) Dorsal puncture in which the guidewire has advanced to a metacarpal branch. (B) Puncture in the anatomical snuffbox of the same patient in whom the guide wire has corrected its course towards the proximal radial artery. (C,D) Cross-sectional and longitudinal ultrasound verification of the correct position of the guidewire within the lumen of the artery (arrows). SB, scaphoid bone; TB, trapezium bone.

Blind with pulse palpation puncture

After the preferred puncture site (dorsal or AS) is identified, anesthetic infiltration is performed with 3–8 mL of 2% mepivacaine. The puncture technique is then started by placing the left fingers of the operators at the site of the highest distal pulse intensity, and with the right hand, using a 21-gauge needle, the puncture is started from lateral to medial with angulation of 30 degrees (9,26,40). From this point on, the procedure to advance the guidewire and introducer sheath is the same as described above. In some cases, a double wall puncture of the DRart may be performed inadvertently, and it may be possible to advance the guidewire by simply withdrawing the needle progressively until we observe blood flow through the needle. For both types of punctures, it is also useful to rotate the needle and give it a sharp angle (26).

Regardless of the puncture technique, the advancement of the guidewire must be gentle and controlled, avoiding forceful manipulation, especially if resistance is encountered. Recall the importance of confirming the progress of the guidewire with fluoroscopy or US. Advancing the guidewire in the presence of resistance without verifying its position increases the risk of complications (26-28,31).

In challenging DRart cannulations, a 0.014’’ hydrophilic coronary guidewire can function as a bail-out tool to navigate tortuous or spasmodic segments. Nevertheless, advancing a sheath directly over it poses a risk of kinking due to insufficient support. To mitigate this risk, the coronary wire should be exchanged for the sheath’s mini guidewire utilizing the dilator or a 20-G angiocatheter. This method ensures safe sheath advancement and reduces vascular trauma.

Patient comfort associated with DRA

When a DRart puncture is performed, adjacent anatomical structures such as the carpal bones and the radial nerve may be contacted, potentially causing discomfort in the patient (25,28,39,41). Comparative analysis of pain perception levels between TRA and DRA indicates that patients undergoing DRA report higher pain levels, attributed to prolonged access time and technique crossover (41). However, this disparity decreases as practitioners become more adept with DRA (41). This finding is corroborated by registries in which operators proficient in DRA demonstrate significantly low crossover rates and a reduction in patient-reported pain perception (3,10,24,42).

After successful DRA, an intraarterial bolus of the spasmolytic agent and a weight adjusted dose of unfractionated heparin are administered, according to the standard practice of each catheterization laboratory.

Hemostasis techniques

Ensuring effective hemostasis after DRA is essential to prevent bleeding-related complications. Dedicated hemostatic devices are recommended, as they provide targeted compression at the puncture site while maintaining distal blood flow, thus helping to reduce the risk of RAO (12,43,44). Bandages should be applied with adequate pressure to stop bleeding without obstructing radial artery circulation, and the duration of compression should be customized according to the characteristics of the patients, including their anticoagulation status (12).

Dedicated hemostatic devices specifically designed for DRA, such as the PreludeSYNC DISTAL compression device (Merit Medical Systems, South Jordan, UT, USA), are recommended to ensure safe and effective hemostasis (Figure 8) (43). When such devices are not available, standard dedicated hemostatic devices for conventional TRA can often be adapted for use in DRA (45). In the absence of dedicated equipment, hemostasis can also be achieved using manual techniques, including gauze packing with bandaging (Figure 9), adhesive tape fixation, or manual compression (5).

Figure 8 Hemostasis using the dedicated pneumatic device. (A) Dedicated pneumatic wristband and syringe. (B) Introducer sheath in anatomic snuff box after coronary procedure. (C) Gentle removal of the introducer sheath and application of the dedicated wristband. (D) Fixation of parts 1 and 2 of the strap around the wrist. (E) Final fastening with the three fixation strips. (F) Progressive removal of the introducer sheath and simultaneous inflation of the wristband. (G) Complete removal of the introducer sheath and simultaneous complete inflation of the 10-cc air. (H) Final position of the hemostatic device after inflation adjustment to avoid occlusive compression.

Figure 9 Hemostasis by bending technique and rolled gauze packing. (A) Introducer sheath in the anatomical snuff box after coronary intervention. (B) Progressive removal of the introducer sheath with simultaneous manual compression until complete exit (C). (D) Manual compression and application of the gauze pack to the puncture site. (E) Placement of the elastic bandage securing the gauze pack. (F) Alternative elastic bandage around the thumb.

Monitoring and follow-up

Post-procedure monitoring is highly recommended to assess both the patency of the radial artery and to detect early signs of complications.

Radial artery patency

Maintaining the patency of the radial artery is important, especially in patients who may require future transradial procedures. Routine evaluation after removal of hemostasis devices by clinical examination with Doppler US can help assess arterial patency (Figure 10). Routine outpatient follow-up is also recommended due to the likelihood of detecting RAO in the intermediate term. Suboptimal anticoagulation is a risk factor for the presence of RAO, so adequate anticoagulation should not be avoided in each case. Treatment with anticoagulation or percutaneous treatment should only be considered in cases of symptomatic RAO.

Figure 10 Patency of the distal radial artery by Doppler ultrasound. (A) Long-axis ultrasound view of the radial artery at the anatomical snuffbox. The yellow box delineates the color Doppler region of interest, demonstrating intraluminal arterial flow (in red), confirming vessel patency. (B) Corresponding spectral Doppler waveform analysis showing a characteristic arterial triphasic flow pattern, consistent with a patent radial artery.

Access-related complications

Access-related complications of TRA can be transferred to DRA by adjusting the adapted classification of bleeding (15). Complications may occur intra-procedure or post-procedure (46). Intra-procedure complications include RAS, arterial dissection, and arterial perforation. Post-procedure complications include, in addition to the RAO already mentioned, hematomas, lesions of the radial nerve, and, less frequently, pseudoaneurysms or AV fistulas.

RAS

RAS in DRA is predominantly associated with multiple puncture attempts, a smaller diameter of the DRart, the application of larger catheters, female sex, and a low body mass index (9,31,47). In certain cases, pain induced by an accidental carpal puncture can lead to RAS. In both TRA and DRA, multiple catheter exchanges can be correlated with the onset of RAS (47). Preventive strategies can be used to reduce RAS, including the administration of adequate anesthesia and analgesia, the use of an appropriate preprocedural spasmolytic cocktail, topical, intravenous, or subcutaneous nitroglycerin, and the selection of hydrophilic introducer sheaths (31,46-48). Non-pharmacological measures include local heat application to the forearm or flow-mediated dilation with a blood pressure cuff (46). The use of US-guided puncture techniques may be helpful in avoiding repeated attempts by improving the evaluation of DRart (31,49). To avoid unnecessary catheter manipulation, the implementation of a single catheter-based strategy has been associated with a reduced incidence of RAS (49).

Arterial perforation

These are rare but serious complications that can occur during catheter or wire manipulation and can lead to compartment syndrome (46). They are more common in tortuous or calcified arteries. Pre-procedure US evaluation can help identify such angiographic conditions and avoid the approach if necessary (Figure 11). Prevention focuses on the careful introduction of soft-tipped, jack-shaped guides and hydrophilic sheaths. If the patient experiences resistance or discomfort during advancement, the position of the wire should be checked with US or angiography (Videos 6,7) (46). The use of protamine, balloon-assisted tracking, and longer sheaths can help reduce the risk of this complication. Most perforations can be sealed in minutes simply by advancing a longer introducer or the coronary catheter itself. If the guidewire cannot be advanced, manual compression and bandaging should be used to prevent compartment syndrome (46,50).

Figure 11 Ultrasound images showing the presence of calcium (white triangles) in the DRart. (A) Image showing nonsignificant calcium in the anterior and posterior walls of the DRart. (B) Presence of significant calcium in the anterior wall but no calcification around the circumference of the DRart. (C) Image of the deep DRart, small in diameter and with significant calcification. (D) DRArt with significant circumferential calcification. DRArt, distal radial artery.

Arterial dissection

Radial artery dissection can occur at different stages and locations during a procedure and should be interpreted in context. Dissection of the DRart is typically related to the access attempt itself and is often associated with multiple puncture attempts, small vessel caliber, or resistance during sheath insertion. When this occurs, it may prevent the advancement of the wire or sheath and lead to crossover. On the contrary, PRart dissection usually occurs after successful DRA, often during guidewire, sheath, or catheter manipulation. These are generally retrograde dissections, opposite the direction of arterial blood flow, and in most cases, they are clinically insignificant. Antegrade flow within the vessel promotes spontaneous sealing of the dissection flap after the sheath or catheter is withdrawn. In both scenarios, if the devices can be advanced without resistance, the procedure can proceed and a post-procedure angiographic assessment is recommended to confirm vessel integrity (46,50,51).

Access-related hematomas

DRA-related hematomas are classified according to the modified Early Discharge After Transradial Stenting of Coronary Arteries Study Hematoma Classification: I-a, distal to the radius styloid process of radius; I-b, up to 5 cm proximal to the styloid process; II, up to 10 cm proximal to the styloid process; III, forearm; and IV, arm above the elbow (15). The most important is early detection to avoid compartment syndrome, so close post-procedure follow-up of the patient is essential. For small hematomas, manual compression and hemostatic devices are sufficient to treat and prevent progression. For larger hematomas, intermittent inflation of the proximal hematoma sphygmomanometer should be considered when performing hemostasis techniques, always monitoring distal perfusion. If compartment syndrome develops, surgical management should be considered (46). The incidence of hematomas is low and most are reported to be small and treated conservatively (4,5,10).

Arteriovenous fistulas and pseudoaneurysms

Arteriovenous fistulas are very rare in the context of DRA and can occur with inadvertent simultaneous puncture of the cephalic vein and DRart. The US evaluation can identify conditions where the cephalic vein overlaps the DRart, limiting its puncture at certain positions (Figure 12 and Video 8). Treatment is usually conservative or by US-guided compression. Several cases have been reported, most of which were treated conservatively and only a few surgically due to persistent AV and neurovascular involvement (46,52,53).

Figure 12 US visualization of the DRart and cephalic vein. (A) US image of the DRart (red arrow) and its relationship with the cephalic vein (blue arrow). (B) Compression of the cephalic vein with the probe. DRart, distal radial artery; US, ultrasound.

Pseudoaneurysm is a rare complication of DRA and its treatment is individualized most often based on size, symptoms, and patient factors, such as anticoagulation status. Options may include US-guided compression, percutaneous thrombin injection, surgical treatment, or endovascular embolization (46,54,55).

Nerve injury

The proximity of the radial artery to the branches of the radial nerves, especially in the AS, increases the risk of injury during puncture. Using US-guided puncture and avoiding multiple puncture attempts can reduce this complication (28,31,46).

Hand dysfunction in distal radial access

DRA has been reported to be safe, with minimal impact after procedure on hand function, and no significant differences in grip strength or dexterity between distal and TRA, and these findings have been confirmed long-term (56,57).

Distal radial access for recanalization and vascular complication management

The DRA technique has emerged as a valuable approach not only for routine coronary interventions but also for the management of complications involving the radial artery. Its anatomical positioning allows retrograde recanalization of RAO, with procedural success rates ranging from 88% to 100% and low complication rates reported (58-61). In cases of proximal RAO, the distal segment frequently remains patent due to collateral circulation through the palmar arch, allowing for puncture and retrograde wiring. DRA also facilitates the management of radial perforations and pseudoaneurysms, which are conventionally treated with balloon tamponade or extended external compression. In certain cases where conservative interventions are unsuccessful, covered stents may be used as a rescue strategy (62). These capabilities highlight the expanding therapeutic role of DRA in the treatment of complex pathologies of the radial artery.

Emerging techniques and innovations

New techniques in DRA focus on improving the safety and efficacy of the approach, with an emphasis on innovations in puncture methods, a more accurate application of US guidance, and hemostasis.

One of the challenges we face with DRA, especially with novice operators, is the tendency to make more attempts at arterial puncture, even with US assistance, which can lead to a higher rate of crossover and an increased risk of access-related complications (26,27,31,63). The angulation and tortuosity of the DRart may contribute to this difficulty, particularly in advancing the guidewire (25,28,63). Based on this assumption, Tal et al. tested the use of a 0.018- or 0.021-inch core diameter guidewire with an articulating tip designed to deflect up to 180 degrees upon contact with the arterial wall or intraluminal obstructions, with the goal of securing vascular access and reducing the likelihood of arterial trauma, particularly in small arteries (63). The use of such an articulating tip guidewire was feasible, and high access efficiency was achieved on the first attempt with no reported complications, making it a promising device.

GLIDEWIRE^® Baby-J^TM (Terumo Medical Corporation, Somerset, NJ, USA) is a 0.014’’ hydrophilic coated guidewire that is increasingly used as an auxiliary instrument in the treatment of tortuous or spastic radial vascular anatomy. Its soft tip and elevated trackability facilitate atraumatic navigation through vessels, contributing to reduce fluoroscopy time, RAS, and access-related complications (64). When vascular access is secured, it can be safely exchanged for the standard mini guidewire using a sheath dilator or a 20-G angiocatheter.

In terms of hemostasis, different types of devices have been used, from manual compression, bandaging, and gauze pack application to dedicated pneumatic devices, demonstrating that non-occlusive compression is a positive predictor of avoiding RAO in both TRA and DRA. A recent study evaluated the use of manual compression hemostasis of DRA using a calcium alginate pad (65). After compression for 10 minutes with this pad and effective hemostasis was confirmed, a small gauze pack was placed over the pad and secured with a self-adhesive elastic bandage for 2 hours. The mean compression time was 12.4±4.8 min, with hemostasis success in all patients and the presence of a local hematoma in 0.6%. With this technique, hemostasis times could be further reduced to the shorter time demonstrated in DRA, in addition to better patient comfort.

For both the articulated tip guidewire and the new hemostasis technique, further studies are needed to prove its feasibility and safety.

Conclusions

The set of skills for a better understanding of DRA details is crucial to improving procedural success and outcomes. This review provides practical recommendations on all aspects of the DRA technique and key strategies to overcome challenges, while highlighting the importance of post-procedure care and follow-up.

Acknowledgments

None.

Footnote

Peer Review File: Available at https://cdt.amegroups.com/article/view/10.21037/cdt-2025-66/prf

Funding: None.

Conflicts of Interest: All authors have completed the ICMJE uniform disclosure form (available at https://cdt.amegroups.com/article/view/10.21037/cdt-2025-66/coif). J.L.F. reports honoraria for lectures from Eli Lilly Co., Daiichi Sankyo, Inc., AstraZeneca, Pfizer, Abbott, Boehringer Ingelheim, Bistol-Myers Squibb, Rovi, Terumo and Ferrer; consulting fees from AstraZeneca, Eli Lilly Co., Ferrer, Boston Scientific, Pfizer, Boehringer Ingelheim, Daiichi Sankyo, Inc., Bristol-Myers Squibb and Biotronik; and research grants from AstraZeneca. The other authors have no conflicts of interest to declare.

Ethical Statement: The authors are accountable for all aspects of the work in ensuring that questions related to the accuracy or integrity of any part of the work are appropriately investigated and resolved. All procedures performed in this study were in accordance with the ethical standards of the institutional and national research committees and with the Declaration of Helsinki and its subsequent amendments. Written informed consent was obtained from the patient for the publication of this article and accompanying images and videos. A copy of the written consent is available for review by the editorial office of this journal.

Open Access Statement: This is an Open Access article distributed in accordance with the Creative Commons Attribution-NonCommercial-NoDerivs 4.0 International License (CC BY-NC-ND 4.0), which permits the non-commercial replication and distribution of the article with the strict proviso that no changes or edits are made and the original work is properly cited (including links to both the formal publication through the relevant DOI and the license). See: https://creativecommons.org/licenses/by-nc-nd/4.0/.

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