Transradial Access for Peripheral and Cerebrovascular Interventions

Abstract: Objectives. In the present review, we report indications, equipment, techniques, results, and complications of transradial access (TRA) in peripheral as well as in cerebrovascular interventions. Background. Percutaneous peripheral and cerebrovascular interventions are usually performed using transfemoral access; however, the risk of vascular complications with this approach is not negligible. Moreover, femoral access may be precluded by advanced vascular disease, and brachial access has been traditionally used as an alternative approach despite the risk of local complications. While TRA has gained wide acceptance for coronary procedures, little is known about its use for peripheral and cerebrovascular interventions. Thanks to dedicated equipment, most vascular territories may now also be treated by TRA. Conclusions. TRA may become the alternative access of choice for peripheral and cerebrovascular interventions when femoral access is precluded. In addition, TRA may become the preferred access for the treatment of selected peripheral lesions.

J INVASIVE CARDIOL 2013;25(10):529-536

Key words: transradial access, cerebrovascular intervention, peripheral intervention

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Most percutaneous peripheral and cerebrovascular interventions are performed using transfemoral access (TFA). However, this approach is associated with a non-negligible rate of local vascular and bleeding complications.^1,2 Moreover, common femoral artery cannulation is sometimes precluded by severe local atherosclerosis. In these cases, brachial artery access has been used as an alternative route.^3-5 Nonetheless, brachial access is also associated with a sizable risk of local complications,⁶ especially if performed by operators with limited experience with this arterial entry site.⁷ The experience in percutaneous coronary interventions showed that transradial access (TRA) may be as effective and safer than TFA, and that a lower rate of local hemorrhagic complications may even translate into a lower morbidity and mortality.⁸ Consequently, TRA is an increasingly used approach for percutaneous coronary angiography and interventions, and the 2012 European Society of Cardiology guidelines for the treatment of ST-segment elevation myocardial infarction state that, if performed by an experienced operator, this access should be preferred over TFA.⁹

Therefore, TRA may also represent an opportunity for vascular non-coronary interventions. This approach, in addition of becoming the best alternative when femoral access is not possible, may become the preferred access site for selective peripheral procedures. The aim of this manuscript is to review indications, equipment, techniques, results, and complications of TRA for peripheral as well as extracranial cerebrovascular interventions. 

Radial Artery Access

A detailed description of the TRA technique is beyond the scope of this manuscript and may be found elsewhere.^10,11 While both right and left radial arteries can be used for TRA, the right access is usually considered more comfortable for the operator, while the left access allows the operator to reach more distal districts and offers more precise catheter manipulations due to less tortuosity at the level of the supraaortic vessels and aortic arch. The use of left TRA as suggested by Lorenzoni et al,¹² with the patient rotated upside down on the angiographic table with the left arm open wide, can be a valuable compromise for below-the-arch interventions. In fact, the operator can work comfortably and possibly receive less radiation exposure.

After the completion of a transradial catheterization, hemostasis can be easily accomplished with a self-made tourniquet or, better, with one of the dedicated devices. 

Complications related to TRA are rare and in most cases clinically irrelevant.¹³ Radial artery spasm is the most common complication, occurring in 5%-10% of patients. Spasms are more frequent in the presence of small arteries, in females, when using large sheaths, and after prolonged catheter manipulation.¹⁴ However, this complication can in most cases be treated with vasodilators or sedation and only in rare cases does it preclude the pursuit of the procedure.

Radial artery occlusion may be encountered in 2%-18% of cases, the rate depending mainly on sheath size.^13,15 However, almost invariably, early radial occlusions are asymptomatic and half of them recanalize spontaneously at 30 days. Adequate anticoagulation at the time of catheterization¹⁶ and Doppler-assisted patent hemostasis are effective strategies for reducing the risk of vessel occlusion.¹⁷ The rate of radial artery access-site bleeding is commonly below 5%; hematoma encompassing the entire forearm is encountered in less than 0.1% of cases and a compartment syndrome is an exceedingly rare event (less than 0.01%).¹⁸

Transradial Access for Percutaneous Interventions on Lower-Extremity Arteries

Angioplasty of lower-extremity arteries is usually performed using TFA. Iliac lesions can be treated either by retrograde ipsilateral femoral access or by contralateral femoral access with the crossover technique. Infrainguinal lesions are commonly treated by the crossover technique if located in the femoropopliteal segment and by antegrade femoral access if located below the knee. However, sometimes the crossover technique cannot be performed due to occlusion, severe tortuosities, or calcification of the iliac arteries, or to a very acute angle of the aortoiliac bifurcation. In addition, crossover may not be feasible due to previously placed kissing stents at the aortic bifurcation. Finally, in cases of iliac occlusion, it may not be possible to cannulate a hypoperfused ipsilateral common femoral artery for a retrograde recanalization.

Under these circumstances, an approach from the arm may be needed, and brachial artery access has been often chosen to that purpose.⁵ However, as mentioned, the complication rate associated with transbrachial access is not negligible and TRA may represent a valid alternative. While new extra-long equipment now allows the treatment of above-the-knee (ATK) lesions by TRA, below-the-knee arteries remain inaccessible by this route.

Angioplasty of above-the-knee arteries by transradial access. Table 1 and Figure 1 illustrate percutaneous interventions on ATK arteries by TRA, which require extra-long equipment.¹² In order to have sufficient support, the common iliac arteries should be selectively engaged with long introducer systems. Device diameters also matter, since they have to be as small as possible in order to progress within radial arteries, but have an inner diameter large enough to accommodate all needed devices. 

For infrainguinal interventions by TRA, only extra-long, 0.018˝-compatible equipment should be used. Due to the distance between the entry site and the target lesions, 300-400 cm-long wires with good torque control and a high crossing capacity are needed. To dilate lesions in the infrainguinal arteries by TRA, two over-the-wire, 0.018˝-compatible balloons with a 180 cm-long shaft are available, while only one stent system with a 180 cm-long shaft exists for cases of flow-limiting dissection after dilatation. 

For suprainguinal angioplasty, both 0.035˝- and 0.018˝- compatible equipment may be used. In fact, lesions can be dilated with the cited 180 cm-long, 0.018˝-compatible balloons. However, commonly available 135 cm-long, 0.035˝-compatible balloons may be adequate for dilating the common iliac arteries and, depending on the height of the patient, also the external iliac arteries. In the necessity of stenting the iliac arteries via TRA, more opportunity is available than for the infrainguinal territory. In fact, although suprainguinal vessels can also be stented with the cited 180 cm-long, 0.018˝-compatible stent, 135-150 cm-long stents can be of sufficient length for stenting up to the external iliac arteries, depending on the height of the patient. Finally, commercially available 135 cm-long balloon-expandable stents can be used to treat the proximal common iliac arteries and the aortic bifurcation.

Nonetheless, some limitations of TRA for ATK interventions have to be mentioned. First, the long distance from the entry site to the target lesion implies a diminished support for the advancement of devices; this drawback may become relevant when crossing occlusions or tight stenoses. Second, the choice of balloons and stents with a long shaft is limited and not all equipment is available in the United States (Table 1). Third, should distal embolization occur, it cannot be treated using the same access site. Last, no available debulking device has a shaft long enough to be used via TRA.

Published reports of lower-extremity angioplasty by transradial approach. In 2005, Flachskampf et al¹⁹ first reported the successful angioplasty of a common iliac artery by TRA. In 2008, Sanghvi et al²⁰ published a retrospective series of 15 patients with poor femoral access and iliac or superficial femoral artery lesions treated by TRA. They described a success rate of 93% and no local complications. In 2009, Trani et al²¹ described 12 patients with in-stent restenosis of the superficial femoral artery treated with balloon angioplasty by TRA, compared with 12 matched patients treated by TFA. While the success and complication rates in the two groups were 100% and 0%, respectively, the use of contrast media was reduced by 30% in the TRA group. In 2010, Staniloae et al²² reported the outcome of a retrospective series of 68 patients undergoing an aortoiliac intervention, of whom 27 were treated by TRA and 41 by TFA. They had a trend toward a lower procedural success rate in the TRA group (88% vs 98%; P=NS), but in the TRA group there was a significantly higher proportion of total occlusions. On the contrary, there were no access-site complications in the TRA group versus 7.3% in the TFA group (P=NS). In 2010, Trani et al first published the stenting of the superficial femoral artery via TRA in 2 patients.²³ In 1 of these 2 cases, bilateral lesions were treated in the same session. In a prospective feasibility study, Lorenzoni et al²⁴ treated 25 consecutive patients with a broad variety of ATK lesions. They deployed 16 stents in 12 patients and had a success rate of 81% in suprainguinal lesions (91% success rate in 11 stenoses and 60% in 5 occlusions; P=NS) and of 81% in femoropopliteal lesions (100% success rate in 13 stenoses, 0% in 3 occlusions; P<.01). No hemorrhagic or vascular complications were reported. 

When to use transradial access for lower-extremity artery angioplasty. TRA may be used for ATK angioplasty in patients with poor femoral access. However, TRA might also be proposed as an alternative route for treating suprainguinal interventions despite favorable femoral access. In fact, for this vascular segment, adequate equipment is available and the safety/effectiveness profile appears favorable. Moreover, TRA may also be used as first-choice access in selected cases, eg, for treating bilateral stenosis on ATK arteries in a single session, or for treating non-occlusive intrastent restenosis. On the contrary, current materials are still suboptimal to address vascular occlusions in the infrainguinal tract.

Transradial Access for Percutaneous Interventions of Renal and Visceral Arteries

Renal artery stenting 

Renal artery stenting (RAS) has been associated with conflicting results in randomized trials.^25,26 Nevertheless, the procedure may be effective in selected patients with renal artery stenosis and uncontrolled hypertension and/or renal failure.²⁷ While RAS is usually performed using TFA and curved guiding catheters, TRA may offer several advantages in this context. For example, in patients with downsloping take-off of the renal arteries, TRA allows for an easier and more stable vessel engagement, thereby reducing the need for catheter manipulations in the aorta and the associated risk of distal embolization, as well as reduced contrast amount.⁴ In addition, the favorable support allows the use of standard 0.014˝ guidewires, with a reduced risk of perforation of distal renal branches. Finally, direct stenting may be more frequently attempted from this approach, with a reduced risk of renal embolization.

As for other percutaneous interventions, TRA may minimize access-site complications during renal interventions.²⁸ This observation may be of particular importance in this setting, because as shown in a randomized clinical trial, the favorable effects of RAS at the renal level may be counterbalanced by access-site complications.²⁵

How to do renal artery stenting by transradial access.²⁸ Table 2 and Figure 2 illustrate RAS by TRA. Renal arteries are easily cannulated with a standard 100 cm, 6 Fr multipurpose guiding catheter using a left TRA. This catheter usually allows an optimal alignment with the renal arteries in case of downsloping take-off of these vessels. For patients with a horizontal take-off of renal arteries, a 6 Fr Judkins right guiding catheter may be more suitable. Alternatively, a 110 cm-long, 5 Fr sheath with different curve tips may also be used (Flexor Ansel; Cook Medical, Inc). RAS is performed using balloon-expandable stents and most 0.014˝-compatible devices fit into 6 Fr guiding catheters and 5 Fr sheaths. In tall patients (>180 cm or 5.9 feet), 6 Fr, 125 cm-long guiding catheters (eg, special catheters by Cordis Corporation) with a plain hemostatic valve (by Cook Medical, Inc or Terumo Corporation) may be required; in that case, stents with a minimum 135 cm shaft length (eg, Herculink Elite by Abbott Vascular) should be used.

Published reports of renal artery stenting by transradial approach. Scheinert et al²⁹ first published a series of 18 patients with renovascular hypertension treated with RAS by TRA. They reported a 100% success rate without access-site complications. Trani et al,²⁸ in 62 consecutive, non-randomized patients undergoing RAS, reported no difference in terms of procedural success rate (both 100%) between TRA and TFA, but they had shorter procedural and fluoroscopy times and a trend toward decreased contrast use in the TRA group.

When to use transradial approach for renal artery stenting. Left TRA may be used as a preferred alternative to transbrachial access to treat renal artery stenosis in patients with poor femoral access, but independently of the ease of TFA, the TRA may become the standard approach for RAS, especially in patients with downsloping renal artery take-off. 

Percutaneous interventions of visceral arteries. Chronic mesenteric ischemia due to stenosis in the visceral arteries can be a cause of malabsorption and postprandial abdominal pain that is encountered with increased frequency in an aging population. In this high-risk patient group, endovascular treatment is frequently preferred over surgery. The same anatomical arguments favoring TRA for RAS do also apply to visceral artery revascularization. In fact, also visceral vessels often have a downsloping take-off from the aorta and may be better cannulated from the arm than from the leg. Visceral artery can usually be accessed with standard equipment such as a 100 cm multipurpose 6 Fr guiding catheter or a 90 cm 6 Fr sheath (eg, Cook Shuttle) advanced over a 125 cm 5 Fr diagnostic catheter. Preliminary favorable results of angioplasty of visceral arteries using TRA have been reported.³⁰

Transradial Access for Percutaneous Interventions of Supraaortic Arteries

Carotid artery stenting

Carotid artery stenting (CAS) has been demonstrated to be an effective and safe alternative to surgical carotid endarterectomy in selected patients when performed by experienced operators.^31,32 This procedure is usually achieved by retrograde femoral access using long sheaths or guiding catheters. The use of emboli cerebral protection, either proximal or distal, is considered standard in most centers. 

In patients with prohibitive femoral access, cervical or transbrachial approach has been proposed as the alternative route. However, cervical access requires direct carotid puncture and is performed only in few surgical centers.³³ Transbrachial CAS, although successfully utilized,³ carries the limitations described in the introduction. Therefore, TRA may become the preferable alternative to transfemoral CAS.

How to do carotid artery stenting by transradial approach. CAS by TRA may be performed using contralateral or ipsilateral radial access (Table 3 and Figure 3). Some operators consider that the left common carotid artery is best engaged using right TRA (especially in the presence of a bovine aortic arch), while the brachiocephalic trunk and right common carotid artery are best cannulated using left TRA (but not in the presence of a type III aortic arch). For other interventionalists, the right radial artery is the default access site for TRA independently of lesion location. 

CAS by TRA may be performed using 8 Fr guiding catheters or 6 Fr sheaths. For CAS by TRA, 90 cm-long, 6 Fr armed sheaths (eg, Destination by Terumo Corporation; Shuttle Select by Cook Medical, Inc) are preferred because of the smaller outer diameter and good kinking resistance. Alternative delivery systems for small-caliber radial arteries (eg, in women) are 5 Fr sheaths (as long as the stent to be deployed is compatible with a 5 Fr sheath) or the 6.5 Fr sheathless multipurpose guiding catheter (Asahi Intecc). This catheter has an outer diameter smaller than a 5 Fr sheath, but has an inner lumen as large as a 6 Fr sheath. When using a long sheath or a sheathless guiding catheter, a 125 cm-long, highly curved 5 Fr diagnostic catheter (most commonly the Simmons catheters) is often needed to engage the supraaortic vessels. With a 0.035˝ wire in the vessel, the sheath or sheathless catheter is then advanced over the diagnostic catheter (ie, the mother-in-child technique) or over a supportive wire parked into the external carotid artery.

Most carotid stents are compatible with 6 Fr sheath or 6.5 Fr sheathless guiding catheter, while some of them are compatible with 5 Fr sheaths. Currently available carotid filters are 5 Fr sheath compatible, permitting distal emboli protection with all the above-mentioned introducer systems. In the presence of a symptomatic lesion or an ulcerated plaque, it may be advisable to use proximal cerebral protection. Many patients with such anatomical conditions have a radial artery large enough to accommodate the 8 Fr MOMA proximal protection system (Medtronic). 

Published reports of carotid artery stenting by transradial approach. Castriota et al³⁴ first reported the use of the TRA for CAS in 3 patients with severe aortoiliac disease or aberrant arch vessel origin; other authors reported isolated case reports.^35-38 Folmar et al,³⁹ in a feasibility study, reported the results of CAS performed by right TRA in 42 patients with an overall success rate of 83%. The investigators had a 97% success rate in patients with right internal carotid artery stenosis, an 80% success rate in patients with left internal carotid artery stenosis in bovine arches, but only a 37% success rate on left internal carotid artery stenosis in normal anatomy aortic arches. They concluded that right TRA represents a safe and effective alternative to the TRA for CAS in patients with right internal carotid disease and left internal carotid disease in the setting of bovine anatomy.

Pinter at al⁴⁰ reported the results of CAS by right TRA in 20 patients, with an overall success rate of 90%. They failed in 1 patient with intense radial artery vasospasm and in 1 patient because they were not able to cannulate a left common carotid artery. On the contrary, Patel et al⁴¹ suggested a contralateral approach for transradial CAS. They treated 20 patients with a 100% success rate in the 12 right CASs by left access and a 50% success rate in the 8 left CASs by right access; they had 1 transient ischemic attack but no radial access-site complications. Trani et al⁴² first reported the stenting of internal carotid arteries with proximal protection with the MOMA system by TRA in 3 patients, with a 100% success rate and no complications.

Etxegoien et al recently published the largest series of CAS by right TRA.⁴³ They treated 382 patients with an overall success rate of 91% (93% in right carotid artery stenosis, 88% both in bovine and normal anatomy left carotid artery stenosis). They had cerebral complications in 5 patients (1.3%; 2 major and 3 minor strokes), but no peripheral bleeding complications; a total of 23 radial arteries (6%) were found to be occluded after the procedure, but all patients were asymptomatic. Inadequate sheath support with prolapse of the delivery system was the main cause of failure.

When to use transradial access for carotid artery stenting. Overall, the TRA for CAS has to be considered more challenging than the TFA for most patients. This implies more catheter manipulations and, as a consequence, a higher risk of cerebral embolization. With the exception of a few centers with highly experienced operators in TRA for CAS, this access should be limited to patients with non-revascularizable aortoiliac disease at high risk for carotid endarterectomy. However, right TRA may considered to be the preferable approach for patients with left internal carotid artery stenosis and a bovine aortic arch.

Percutaneous interventions of other supraaortic arteries

Up to 20% of patients with posterior circulation cerebral ischemia may have a critical stenosis of the vertebral artery as the underlying predisposing factor.⁴⁴ While the initial treatment adopted is frequently conservative, vertebral artery revascularization should be considered at the very latest in case of recurrence of symptoms. Since surgery is very demanding and rarely performed, percutaneous treatment is the preferred choice in many centers.⁴⁵ Vertebral artery stenting is usually performed using TFA. TRA has been used in case of poor femoral access or excessive kinking of the brachiocephalic trunk or of the proximal left subclavian artery.⁴⁶ In a prospective feasibility study, Yip et al⁴⁷ successfully treated 24 consecutive patients undergoing vertebral stenting by TRA without procedural complications. The largest cohort of vertebrobasilar lesions treated by TRA is reported by Patel et al.⁴⁸ They treated 47 patients (42 with vertebral artery lesions and 5 with basilar artery lesions) using an internal mammary artery guiding catheter by ipsilateral TRA. They had a 100% success rate; 3 patients had a transient ischemic attack and 1 died after an intracranial hemorrhage; they had no access-site complications.

Stenosis or occlusion of the proximal subclavian artery may cause arm claudication or, more frequently, vertebrobasilar symptoms secondary to the subclavian steal phenomenon. In patients with subclavian lesions and an internal mammary coronary artery bypass grafting, arm exercise may cause myocardial ischemia by diverting blood from the coronary artery to the upper limb.⁴⁹ Subclavian stenosis may be treated either by carotid-subclavian bypass or, more frequently, by percutaneous stenting.⁵⁰ While TFA is commonly used for endovascular treatment, ipsilateral TRA may be used in case of poor femoral access or tortuous proximal supraaortic vessels. The better visualization of the origin of the vertebral and the internal mammary arteries is a further advantage of TRA because the risk of compromising emerging vessels through inaccurate stent placement at the level of the subclavian artery can be reduced. In addition, TRA frequently allows more support than TFA to recanalize total occlusions.

Conclusions

The TRA is associated with fewer access-site complications compared to transbrachial access and could be considered a valuable alternative for peripheral and cerebrovascular interventions in the presence of poor femoral access. In addition, in centers with large experience in TRA, this access may also become a first-choice approach for selective non-coronary vascular interventions, such as for treating iliac artery stenosis, for stenting renal and visceral arteries when they have a downsloping take-off, or for stenting a bovine left carotid artery or the subclavian artery.

However, it is mandatory to underline that most of the studies reported in this review were observational, included a limited number of patients, and were carried out in centers with large experience with TRA access. Therefore, a selection bias cannot be excluded and definitive conclusions about the safety and the effectiveness of this access for non-coronary interventions cannot be drawn.

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