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- cardiac catheterization and angiography
- percutaneous coronary intervention
- transcatheter valve interventions
Learning objectives
To choose the most appropriate access site for a cardiovascular intervention.
Learn how to gain access and achieve closure of the radial and femoral arteries.
Learn how to minimise vascular complications.
Introduction
Selective coronary angiography initially required surgical cut down to access the brachial artery.1 Subsequently, in 1967 Melvin Judkins described a direct percutaneous approach via the femoral artery,2 an easily palpated vessel with high procedural success that would go on to become the default arterial access route. However, despite decades of experience with femoral access, vascular complications and bleeding remain a concern and are still a significant cause of mortality in cardiovascular intervention.3 Percutaneous coronary intervention (PCI) via the radial artery was first described by Kiemeneij in 1993,4 and early studies appeared to show a virtual elimination of access site complications.5 Initially the technique remained a niche interest of early radial pioneers, but usage in the United Kingdom has increased from 14% in 2005 to 84% in 2016 replacing the femoral artery as the most popular access site for intervention.6
Selection of radial or femoral arterial access
Radial artery access reduces vascular complications across all patient groups7 and is now recommended as the standard route for PCI.8 However, there are groups where the benefit is more pronounced. The superficial course and small calibre of the radial artery simplifies haemostasis allowing early ambulation9 and reducing cost10 making it ideal for patients who cannot tolerate prolonged bed rest, on anticoagulants or are undergoing PCI in the day case setting. A mortality benefit for radial access has been shown in patients with acute coronary syndrome and ST elevation myocardial infarction in both large randomised controlled trials11 and meta-analysis12 making this a strong indication for radial PCI. However, there remain procedural reasons when femoral access is required (large-bore access for transcatheter aortic valve intervention (TAVI), mechanical circulatory support or complex coronary interventional procedures), and in a small proportion of patients unfavourable radial approach anatomy results in cross-over to femoral access. For this reason, interventional cardiologists must be familiar with best practice for both access sites.
Radial artery access: patient preparation
The right radial approach is most commonly used for ergonomic reasons. The right arm is placed alongside the body in a supine position supported by a dedicated arm board. Contralateral venous access should be obtained in case of vasovagal reaction requiring resuscitation and to allow administration of analgesia or sedation. The right groin should also be prepared in high-risk cases to facilitate rapid central venous and femoral arterial access if needed.
The left radial is a feasible alternative and is preferred if there is a requirement to image a left internal mammary artery (LIMA) graft or if the right radial pulse is absent. Accessing the left radial may be uncomfortable in larger patients while the left arm is at the patient’s side in which case the arm is extended at 80° for arterial cannulation and then positioned back across the body for the remainder of the procedure. Catheter orientation from the left radial approach more closely approximates that of the femoral approach and the operator is three times less likely to encounter subclavian tortuosity.13 This may account for evidence that the left radial route is associated with lower fluoroscopy time in elderly patients or with operators in training.14 In a randomised controlled trial of 1493 patients undergoing coronary angiography, there was no difference in operator radiation exposure from femoral or right radial access but it was higher with left radial access.15 There is often a requirement to stand closer to the patient to manipulate catheters from the left radial artery so if using this access, extension tubing to allow the operator to maintain distance should be used.
Routine preprocedural sedation is administered by 58% of operators.16 The radial artery has a muscular wall with numerous α-adrenergic receptors that make it prone to developing intense spasm.17 A randomised controlled trial of 2013 patients showed lower rates of spasm and femoral cross-over after fentanyl and midazolam18 so while not used universally it remains a useful adjunct in patients with high adrenergic states such as those with acute myocardial infarction or heightened anxiety.
It is no longer considered necessary to perform an Allen’s test to determine the patency of the ulnar-palmar arch prior to radial access6 and relying on this will likely exclude a significant number of patients who would benefit from radial access unnecessarily. Multiple studies have used radial access in patients with an abnormal Allen’s test and none developed any clinical or subclinical consequences.11 19 Ischaemic complications have been described in patients with connective tissue disease and severe Raynaud’s disease,20 but are very rare and in these patients the balance of risk with the reduction in vascular complications should be considered when choosing access.
Radial artery access technique
The radial artery is usually accessed 2 cm proximal to the styloid process (figure 1). A small amount (1–2 mL) of local anaesthetic is administered initially at the puncture site to avoid distorting the anatomy. A short micropuncture needle is then advanced on a shallow trajectory until the anterior wall of the artery is punctured. A small calibre guidewire is then advanced through the needle with a rotating motion to avoid small side branches. At this point, the entry site can be further infiltrated with local anaesthetic and a skin nick made while the micropuncture needle is in situ to prevent inadvertent damage to the guidewire. The micropuncture needle is removed, and the sheath is inserted over the guidewire.
An alternative technique is to transfix the radial artery with a ‘through and through’ puncture. This is usually performed with a catheter-over-needle system. Here, the needle is advanced through both the anterior and posterior wall of the artery. The needle is withdrawn, and the catheter pulled back slowly until arterial flow is seen. At this point, the guidewire is inserted. In a randomised trial of these two techniques in 412 patients, there was no difference in access site complications but the ‘through and through’ technique was associated with faster access and fewer attempts required.21 The radial artery is usually easy to palpate so ultrasound guidance is uncommon. However, a prospective randomised controlled trial of 698 patients has shown that routine use of ultrasound almost halved the average number of cannulation attempts required from 3.1 to 1.7.22
Overcoming difficulties with catheter advancement in the radial artery
Radial spasm was the most common reason for transradial failure in a series of 2100 patients (1.6% of cases).23 The majority of radial operators (86%) use a spasmolytic agent following sheath insertion,16 and meta-analysis reveals that a combination of verapamil and nitroglycerin is the most effective.24 To reduce radiation exposure, it is permissible to initially advance the guidewire and catheters up the arm without fluoroscopy.25 However, if resistance or patient discomfort is felt, then an arm angiogram should be performed. Due to the frequency of anomalous anatomy (occurring in 14% of a series of 1540 patients), some operators routinely perform minimal contrast volume arm angiograms to avoid trauma or spasm in tortuous or small calibre arm vessels.26 Anatomical anomalies range from those that have a minimal effect on success rate such as high bifurcation of the radial artery (present in 7%) often associated with smaller calibre arteries and a tendency to spasm which resulted in failure in only 4.6% of cases, to full 360° radial loops present in only 2.3% but resulting in failure 37.1% of the time and requiring reducing before a guiding catheter can be advanced26 (figure 2).
Even if areas of adverse anatomy or spasm have been negotiated with a hydrophilic wire or a 0.014-inch angioplasty wire, it may not be possible to advance a guide catheter due to the ‘razor’ effect of the edge of the catheter on the arterial wall.27 To overcome this the distal end of the guiding catheter needs to be tapered. This can be achieved in a standard guiding catheter using two techniques, balloon-assisted tracking (BAT)27 and the ‘5 in 6’ technique (figure 3). These techniques have been used with high rates of success in different clinical situations and importantly can be used to maintain radial access in primary PCI with no increase in door to balloon times compared with switching to the femoral route.28
Finally, in one series 0.9% of radial access cases failed because of subclavian tortuosity23 and in another a retro-oesophageal right subclavian was present in 0.3% of cases29 (figure 4). In these cases, the angle of advancement can be made more favourable by asking the patient to take a deep inspiration. If the guidewire remains biased towards the descending aorta, then it can usually be directed with a Judkins right catheter towards the aortic root, which will be to the left of the descending aorta on a 30° LAO projection. There can be difficulty in catheter engagement of the coronary ostia, and it is often necessary to keep the 0.035 guidewire within the catheter to facilitate catheter manipulation and prevent kinking. Although the wire can be kept in the catheter right up to engagement of the coronaries, it is important to ensure that there is a free backflow of blood and normal arterial pressure trace before injecting any contrast. If there has been any difficulty advancing the catheter into the aortic root, catheter exchanges should be performed with a long 260 cm guidewire in the aortic root so that wire position is not lost.
Management of radial access complications
Vascular complications during radial access are rare and with early recognition and prompt management clinically significant sequelae can be avoided30 (table 1). Dissection can occur from guidewire trauma or advancement of an oversized sheath or catheter in a small calibre artery. As these are retrograde to arterial flow they are usually self-limiting and require no specific treatment apart from careful observation. However, as they are usually accompanied by intense spasm (figure 4) they may require change to an alternative access. More significant arterial trauma can lead to vessel perforation, usually due to inadvertent advancement of a guidewire into a small side branch or radial anomaly (figure 4). Previously, these would be managed with immediate manual compression; however, if the segment has been traversed with a guiding catheter the procedure can be completed as the presence of the catheter prevents excess bleeding from the perforation site which will usually seal without further intervention by the time the procedure is completed and the catheter withdrawn.31 Patients should be monitored closely afterwards for the evidence of forearm haematoma. If detected early, this can be managed with conservative measures but if not addressed can lead to compartment syndrome which is very rare (1:25 000) but requires urgent surgical fasciotomy.30
Limitations of radial access
The radial artery is usually between 2 and 3 mm in diameter and is generally larger in men than in women.32 This has the potential to limit the ability to perform complex intervention requiring larger bore (>6F) guiding catheters. Saito et al found in 260 patients that the radial artery diameter was smaller than the outer diameter of a standard 7F sheath (Terumo, Japan) (2.95 mm) in 29% of males and 60% of females.32 If a 7F guide catheter is required, one option is to use 7F Glidesheath (Terumo) which can accommodate a 7F guiding catheter but has an outer diameter of 2.79 mm (equivalent to a standard 6F sheath). Another is a 7F Sheathless guide catheter (Sheathless Eaucath; Asahi Intecc, Japan), and these have an outer diameter of 2.49 mm and have been used to successfully complete complex interventions including crush stent bifurcations and rotational atherectomy.33 Finally, the Railway system (Cordis, a Cardinal Health company) consists of dedicated introduction and exchange inserts that allow conventional 7F guides to be used without a sheath.
Radial artery closure
The radial artery is easily compressible allowing immediate sheath removal independent of any anticoagulants given. Traditionally a compressive dressing or bracelet compression device (the most common being the TR band (Terumo) (figure 1) is used to give 2 hours of continuous compression. Radial artery occlusion has been reported in around 5% of cases after compression haemostasis but is likely under-reported as is virtually always asymptomatic.34 However, it is important as occlusion limits options for repeat arterial access and loss of a potential conduit in the future for coronary artery bypass grafting. Steps to reduce radial artery occlusion include anticoagulation25 and patent haemostasis35 and are listed in table 2.
Ulnar artery and left distal radial artery access
Ulnar artery access is a potential alternative to the radial artery. However, the ulnar artery is situated deeper in the forearm and runs alongside the ulnar nerve making inadvertent nerve injury and forearm haematoma a risk. A meta-analysis comparing radial and ulnar approaches with coronary angiography and PCI showed no significant difference in access-site complications, but access-site cross-over was significantly higher with ulnar access.36 More recently, Kiemeneij has described the technique of using the smaller left distal radial artery within the anatomical snuffbox for alternative access. The technique is technically challenging making it only suitable for selected cases but has the potential advantage of greater operator and patient comfort.37
Femoral arterial access: patient preparation
The key to reducing femoral access site complications is ensuring that sheath insertion is within the optimal site in the common femoral artery (CFA).38 The CFA runs within the femoral sheath, adjacent to the femoral vein and nerve and is bordered superiorly by the inguinal ligament and inferiorly branches into the superficial femoral and profunda femoris arteries (figure 5A). Low punctures below the bifurcation result in more bleeding, pseudoaneurym39 and arteriovenous fistula formation40 due to the smaller artery size, superficial relationship of the femoral vein tributaries and absence of bony prominence for compression. High punctures above the inguinal ligament in the external iliac artery are not compressible risking retroperitoneal haemorrhage.41
Supplementary file 1
Historically, operators have relied on a combination of palpation, surface anatomy and fluoroscopic landmarks to puncture the CFA. The point of maximal pulsation allows easy vessel cannulation and in one study correlated 93% of the time with the location of the CFA. The skin crease is readily identified but is frequently (72% of cases) located below the bifurcation.42 Using the bony landmarks of the anterior superior iliac spine and the pubic tubercle as a proxy for the inguinal ligament, a puncture 2–3 cm below the mid-inguinal point has been proposed; however, the correlation of the bony landmarks in cadaveric studies is poor.43 There is some evidence that a fluoroscopy-guided approach can reduce femoral vascular complications.44 Studies have shown that 95% of the time the bifurcation of the CFA is at or below the mid-femoral head leading to a proposed mid-femoral head fluoroscopic target zone45 (figure 5B). Some operators advocate the use of a micropuncture kit (Cook Medical) to minimise complications. The evidence base for this is limited and observational studies have not shown clear benefit.46 However, this is intuitively attractive as it allows a 4F sheath to be placed and femoral sheath angiography undertaken to confirm position before a larger sheath is introduced (figure 5C).
Surrogate anatomical markers for the identification of the CFA can be misleading in cases of anatomical variation. In particularly challenging anatomy such as morbid obesity or peripheral vascular disease, it may better to consider the radial approach. If this not possible, then direct visualisation of the CFA with ultrasound guidance should be performed (figure 5).
Ultrasound-guided femoral arterial access
Ultrasound allows for real-time visualisation of vessel cannulation.47 As far back as 2002, the National Institute for Health and Care Excellence concluded that the evidence base for ultrasound-guided central line insertion was sufficiently robust to mandate its use in this setting across the National Health Service in England and Wales. Ultrasound guidance in femoral vascular access was compared with traditional techniques in randomised controlled trials,48 and a recent meta-analysis49 involving 1422 subjects showed a 49% reduction in overall complications and a 42% improvement in the likelihood of first-pass success. Although TAVI operators are increasingly recognising its utility, uptake in the general interventional community has been slow as demonstrated in a recent small survey where only 13% of interventionists used it for femoral access.50 There is a learning curve associated with ultrasound-guided puncture; nevertheless usage is likely to grow given its proven efficacy in reducing vascular access complications.
Femoral artery access technique
Femoral access is uncomfortable for the patient so consider sedation, especially if gaining large-bore access. Local anaesthetic is infiltrated, initially with a 25G needle to form a skin bleb, then using a 22G needle to just above the CFA and the tissue track. After making a small nick in the skin, an 18G needle is introduced at an angle of between 30° and 45° until it rests above the CFA where it may be observed to ‘dance’ with the arterial pulse. A single anterior wall puncture is made and once good pulsatile flow through the needle is established, then the needle is lowered to become more coaxial with the vessel and a 0.035-inch J tip guidewire introduced followed by a sheath.
If the sheath will not advance over the guidewire, exclude a kinked guidewire and readjust wire position if feasible. If scar tissue is the problem, consider sequential dilatation with smaller dilators or exchange for a more supportive guidewire through the dilator. If there is resistance to advancement of the guidewire or catheter, then an angiogram should be taken. Unlike the radial artery, spasm or anomalies of the femoral artery are not usually encountered. However, there may be a tortuous ileofemoral system (figure 6A). This may need to be negotiated with a hydrophilic 0.035-inch guidewire. If catheter advancement or manipulation is not possible, exchange over a diagnostic catheter for a stiffer guidewire (eg, Amplatz Extra-Stiff, Cook Medical) and consider the use of a long armoured sheath (eg, Super Arrow-Flex, Teleflex Medical).
Femoral vascular complications
Vascular complications remain the Achilles heel of femoral access. The use of larger sheaths and more potent antithrombotic medication mean that vascular complications are two to three times higher after PCI than with diagnostic angiography.51 Known risk factors for vascular complications include age >70 years, female sex, body surface area <1.6 m2, renal failure, urgent procedures, complex disease and use of glycoprotein IIb/IIIa inhibitors.52 In addition, punctures outside the target zone of the CFA result in a higher level of complications.38 Arterial dissection is usually caused by advancement of equipment without guidewire support (figure 6B). As they are retrograde they will usually settle with conservative management. Perforation has the potential to be a serious complication if it is not detected promptly (figure 6C). If bleeding occurs into the retroperitoneal space where it may be detected late and will not be controllable with compression, it is associated with a mortality of 10%.53 An overview of femoral access complications and their management is provided in table 3.
Femoral artery closure
Manual compression remains the the most common method of femoral access closure worldwide. It is highly effective for small sheaths but does mean prolonged patient immobilisation. Since the 1990s, there have been ongoing developments of vascular closure devices (VCD) and the latest generation now provide faster haemostasis compared with manual compression. They have not however been proven to reduce vascular complications and indeed concern remains that rare complications such as ischaemia or infection are increased by their use. Compared with manual compression, randomised controlled trial data show no superiority for VCD in risk of bleeding54 and meta analyses reveals that VCD have a significantly shorter recovery time but higher rates of groin infection (0.6% vs 0.2%, p = 0.02 and a trend towards increased risk of ischaemic complications (0.3% vs 0%, p = 0.07) and need for vascular surgery (0.7% vs 0.4%, p = 0.10).55
Manual compression
Effective manual compression requires a relaxed normotensive patient and the table height adjusted for operator comfort. Three fingers should be placed just above the puncture site and the sheath removed under sufficiently gentle pressure to avoid milking any thrombus out of the sheath during removal. Firm pressure is then required for a minimum of 8–10 min with patient ambulation possible 2 hours later. Longer compression times are needed for larger sheaths or with more potent antiplatelet or antithrombotic regimens. The femoral sheath should be removed as soon as safely possible following a procedure as long dwell times are associated with increased complications. If unfractionated heparin has been given, then compression is typically delayed until the activated clotting time (ACT) is less than 180 s. External compression devices can also be used as an alternative or adjunctive device to manual compression. FemoStop (Abbott/St. Jude Medical) is an external clamp device with a clear air-filled plastic bubble which permits variable pressure inflation.
Vascular closure devices
Guidelines support the use of VCD to provide faster haemostasis and early ambulation but not to reduce vascular complications and they also mandate a femoral angiogram to assess suitability.56 A rotational angiogram is recommended for the femoral sheath to identify the puncture position, vessel calibre, adjacent plaque disease and so clarify suitability for device closure. The two most commonly used VCD are the Angio-Seal (Terumo) and the Perclose Proglide (Abbott). The vascular complication rates of these are similar,57 but operator experience and familiarity is important.58 The Angio-Seal comes in 6F and 8F sizes and is popular due to its relatively short learning curve and high success rate. The mechanism relies on an intravascular biodegradable anchor which actively approximates with a collagen plug. The anchor should resorb within 3 months. The principle concern relates to the residual material left behind risking infection or ischaemia. The Perclose Proglide (Abbott) is a suture-based active approximator that aims to mimic a surgical suture. It has a longer learning curve and higher failure rate than the Angio-Seal57 but can be predeployed and used as a single unit or as multiple devices so is also suitable for large bore closure. It uses a pretied polypropylene monofilament suture that allows successful closure to be assessed on the table while maintaining wire access with a standard 0.035′ wire. An overview of current VCD is shown in table 4.
Large bore femoral artery closure
With the increasing use of large bore femoral access for TAVI and adjunctive haemodynamic support, there has been renewed interest in optimising large bore vessel closure. Traditionally, large femoral arteriotomy sites have been closed surgically or with prolonged manual compression. Manual compression is less effective and prone to complications in this setting and so ‘preclosure’ with a suture-mediated VCD has become commonplace. Perclose Proglide (Abbott) and Prostar XL (Abbott) are the two most commonly used suture-based preclosure devices. The Prostar XL has a longer learning curve, a sliding suture which must be hand tied and needles which move from intravascular to extravascular. Both devices appear equally efficacious in experienced hands. The MANTA (Essential Medical) is a new anchor/plug-based device and has shown promising early results. Irrespective of the closure device used, a deep puncture into a small heavily diseased vessel through anterior wall calcium all predict a higher risk of device failure.
Conclusions
Safe arterial access and closure is a fundamental of interventional cardiology. Transradial access has emerged from a niche interest to the access site of choice in a large number of centres in more than 75 countries worldwide16 and proficiency in it is essential in all those undertaking cardiovascular interventions. However, despite its success, there remains a small proportion of cardiovascular interventions that still require femoral access due to the need for large calibre access or procedural or anatomical constraints. As experience in femoral access decreases, there is the potential for a paradoxical increase in femoral complications.59 This does not seem to have occurred during the widespread adoption of radial access in the United Kingdom60 but given that femoral access in now often only performed in challenging situations it is vital that those undertaking cardiovascular interventions must maintain proficiency in managing femoral arterial access as well as becoming familiar with new developments such as ultrasound guidance.
Key messages
Vascular access site complications are a significant source of morbidity and mortality in cardiovascular intervention performed from the femoral artery.
Strategies to improve femoral puncture in the ‘safe zone’ of the common femoral artery should be employed routinely of which ultrasound guidance is the most effective.
Compared with femoral artery access, radial artery access results in fewer access site complications and a reduction in mortality in patients with acute coronary syndrome.
Radial artery access presents procedural challenges that can be overcome with experience and specialist techniques.
Radial artery access is now the predominant access site for percutaneous coronary intervention, but there remain situations when femoral artery access is required so interventional cardiologists should be proficient at both.
CME credits for Education in Heart
Education in Heart articles are accredited for CME by various providers. To answer the accompanying multiple choice questions (MCQs) and obtain your credits, click on the ‘Take the Test’ link on the online version of the article. The MCQs are hosted on BMJ Learning. All users must complete a one-time registration on BMJ Learning and subsequently log in on every visit using their username and password to access modules and their CME record. Accreditation is only valid for 2 years from the date of publication. Printable CME certificates are available to users that achieve the minimum pass mark.Education in Heart articles are accredited for CME by various providers. To answer the accompanying multiple choice questions (MCQs) and obtain your credits, click on the ‘Take the Test’ link on the online version of the article. The MCQs are hosted on BMJ Learning. All users must complete a one-time registration on BMJ Learning and subsequently log in on every visit using their username and password to access modules and their CME record. Accreditation is only valid for 2 years from the date of publication. Printable CME certificates are available to users that achieve the minimum pass mark.
Acknowledgments
We thank Professor Alex Chase, Morriston Cardiac Centre, Swansea, UK, for the images in Figure 1 and Figure 5C.
References
Footnotes
Contributors SHD and DRO have both co-authored this article.
Funding The authors have not declared a specific grant for this research from any funding agency in the public, commercial or not-for-profit sectors.
Competing interests None declared.
Provenance and peer review Not commissioned; internally peer reviewed.
Author note References which include an * have been selected as key references for this article.
Patient consent for publication Not required.