Our Technique For Transradial Coronary Angiography And Interventions
Stefano Rigattieri, Cristian Di Russo, Pasquale Silvestri, Silvio Fedele, Paolo Loschiavo,
Interventional Cardiology Unit, “Sandro Pertini” Hospital, Rome, ITALY

INTRODUCTION
The history of transradial approach (TRA) for coronary angiography and interventions began twenty years ago . Despite being more difficult as compared to the standard transfemoral approach (TFA), requiring a steep learning curve, TRA has become increasingly popular essentially because it 1) simplifies the hemostasis after the procedure; 2) significantly reduces access-related bleedings and vascular complications; 3) increases patient’s comfort , .
Dedicated equipment has been developed by industries and a growing number of operators have adopted TRA; yet, the prevalence of TRA in the daily practice is still low, being about 10% in the United States, 15% in India and 30% in European countries, with the only exception of France (50%) .
Emerging evidence suggests that TRA could impact on hard clinical end-points, i.e. major adverse cardiovascular events, especially in high-risk clinical subsets such as acute coronary syndromes , , .
However, in our opinion, neither the availability of sound clinical data nor recommendations issued by international societies will be able to persuade “femoral” operators to switch to TRA, unless they feel confident with it.
To reach this goal, TRA technique needs to be fully explained, with “tips and tricks” to overcome difficulties  but also with some advices about which patient is better not to do by TRA unless the operator is a very experienced one.

METHODS
Patient selection
First of all, a good candidate for TRA is a patient that is a bad candidate for TFA, mainly because of the expected risk of bleeding/vascular complications; this holds true for obese patients , anticoagulated patients , patients with peripheral vascular disease , , patients under aggressive anti-thrombotic treatment and elderly patients , .
In our practice, every patient is suitable for TRA as long as he or she has a “good” pulse (according to the operator) and a patent palmar arch, as documented by the Allen’s test or by plethysmography. Delayed recruitment of collaterals has been demonstrated even after initial negative results of these tests , which explains why hand ischemia with necrosis has never been reported after TRA. Despite some operators have stopped performing the Allen’s test, our suggestion is to do it, to implement it with plethysmography if the result is not clear and, finally, to switch to the controlateral radial artery.A flow chart for the selection of vascular access is reported in Figure 1. Unless the operator is very experienced, we recommend caution in the selection of TRA in hemodynamically unstable patients (e.g. cardiogenic shock, large ST-elevation myocardial infarction with advanced Killip class), even if, in these settings, TRA could be helpful in the case a femoral access is needed for the placement of an intra-aortic balloon pump or an Impella device. Angiography through a Pigtail catheter placed in the abdominal aorta from the arm may show the iliac-femoral anatomy and help in device implantation.

Figure 1: Flow chart for the selection of vascular access. TRA: transradial approach; TFA: transfemoral approach; PCI: percutaneous coronary intervention; PVD: peripheral vascular disease.

As far as primary percutaneous coronary intervention (PCI) is concerned, there are several reports about the safety and feasibility of TRA, but only two small randomized trials comparing TRA with TFA , .
The issue of bleedings in patients undergoing primary PCI has been outlined in the recent HORIZONS-AMI trial, in which bivalirudin was shown to be superior as compared to glycoprotein IIb/IIIa blockers in a large population of patients mostly treated by TFA .
TRA has the potential to be the approach of choice in primary PCI, since it offers clear advantages in the management of the vascular access and it allows “additive” procedures, such as manual thrombus aspiration, which are now fully 6 French compatible.
The drawback is a ~5% rate of switch to TFA, even in the hands of very expert operators , and a possible increase in reperfusion time; these issues, together with the effective clinical impact of TRA on hard end-points after primary PCI, should be addressed by a properly designed randomized clinical trial.
Another clinical condition in which we discourage TRA is moderate-to-severe chronic renal failure, since in these patients the radial artery should be preserved for the creation of arteriovenous fistulae for hemodialysis.

Cath Lab setup, access technique and dedicated hardware
The correct positioning of the patient is a very important issue for a successful TRA, since both the patient and the operator must be comfortable throughout the procedure. Although dedicated hardware has been developed (i.e. sideward extensions of the catheterization table), we suggest a simple patient preparation both for right (Figure 2) and left (Figure 3) TRA.
Another crucial issue, still debated among radial operators, is which side is better for TRA, i.e. right or left side. In our practice we prefer right TRA, performing left TRA only in patients with left internal thoracic artery grafts or when the Allen’s test is negative on the right arm. Our choice is dictated by better comfort and, probably, less radiation exposure for the operator, who is working closer to the X-ray source in left TRA. Nevertheless, left TRA may be better because catheter manipulation is easier as compared to TRA, especially for “femoral”, not dedicated shapes, and also because the left subclavian artery usually presents a less tortuous course as compared to the brachiocephalic trunk. This translated into a reduction in both procedural time and fluoroscopy time in a randomized study, restricted to diagnostic coronary angiography . The ongoing TALENT trial will provide new data about the impact of the laterality of TRA on success rate and radiation exposure, both in diagnostic and interventional procedures .
Proper selection of the puncture kit is another issue of paramount importance. There are several available devices, and one must select between: 1) open metal needle, needing a spring mini guide-wire, or entry venous catheter/cannula, which allows for the use of plastic, hydrophilic wires; 2) short (from 7 cm) or long sheaths (up to 25 cm), hydrophilic or not.
Some operators prefer to use the entry venous catheter with long hydrophilic wires and sheaths, since these devices allow for an easier puncture of the artery and an easier advancement of the sheath, that, being long and hydrophilic, minimizes the problem of spasm both during catheter manipulation and during retrieval of the sheath at the end of the procedure.
We prefer to use a short (10 cm), non hydrophilic 6F sheath together with a 22G metal needle and a 0.018”, 45 cm-long spring wire (Radifocus II, Terumo Corporation, Tokyo, Japan).
We selected this system many years ago because both the needle and the guide-wire have a very low profile, which in our opinion minimizes traumatism to the vessel wall and reduces the risk of spasm during the puncture. The other advantage is that, in case of radial tortuosity in the forearm or even loops associated with a remnant artery, usually the

guidewire does not advance but allows for a partial introduction of the sheath, through which it is possible to assess back  flow, blood pressure as well as to inject contrast medium in order to reveal the anatomy.
Using an hydrophilic wire blindly in this setting could be harmful, since the wire, and possibily the hydrophilic sheath too, could progress in a side branch or remnant vessel, leading to the risk of vessel avulsion/perforation with bleeding and forearm hematoma.
Another possible drawback of hydrophilic sheaths is the formation of sterile abscesses, reported in about 2-3% of patients 2-3 weeks after the procedure .

The choice of a short, non hydrophilic sheath makes obligatory the administration of a spasmolytic drug; we use verapamil, 5 mg into the side branch of the sheath, with adjunctive boluses of nitroglycerin (200 mcg) in the case of persistent spasm documented at angiography.
The issue of anticoagulation is also very important in order to reduce the risk of radial occlusion, which has been reported to be as high as 32% in patients receiving only 2-3000 units of heparin, despite the use of 5F catheters . We administer a total dose of 70 UI/Kg of heparin, giving half dose after the sheath insertion and the remaining after having reached the ascending aorta, so that, in case of technical difficulties requiring a switch to femoral approach, manual hemostasis can be obtained at the end of the procedure.

Reaching the coronary ostia: how to deal with anomalous anatomy
After the radial sheath is in place, obtaining an angiogram before advancing the angiographic wire should be considered in order to assess the presence of anatomic variants and the size of the artery. This could be helpful especially in urgent procedures, where a rapid switch to an alternative access is recommended if a difficult anatomy is encountered; besides that, it is possible to assess the size of the radial artery and the possibility to use large guiding catheters (> 6F).
In a recent large series, the overall incidence of radial artery anomaly was 13.8%, including high-bifurcating radial origin (7.0%), full radial loop (2.3%) and extreme radial artery tortuosity  (2.0%). It is worth noting that, even in the hands of experienced high-volume radial operators, procedural failure was more common in patients with anomalous anatomy than in patients with normal anatomy (14.2% vs 0.9%, p<0.001) .
If time is not an issue, we try to overcome difficult anatomies with the aid of hydrophilic wires (0.035” Glidewire, Terumo Corporation, Tokyo, Japan) or 0.014” coronary guidewires. Care must be taken to avoid vessel perforation, both at the arm level and more proximally, since rare complications such as mediastinal hematomas have been reported .
Tortuosity of the brachiocephalic trunk can be managed by advancement of the guidewire mounted on a Judkins right catheter, asking the patient to take a deep breath. In the case of severe tortuosity, we suggest to manipulate the catheters with the guidewire inside, in order to avoid kinking; a Y connector for angioplasty may be useful to check the pressure and inject dye.
Retro-oesophageal right subclavian artery (arteria lusoria) is a rare anatomical variant, with a prevalence of 0.45% in a recent series . Engagement of coronary ostia is still possible, but the procedural success rate is low (60%) even for expert operators. Therefore, especially when a PCI is needed, our suggestion is to switch to an alternative approach.

Selection and manipulation of catheters
Although dedicated curves have been designed for TRA, in our laboratory we prefer to use standard, “femoral” curves. For the right coronary artery, JR 4 is our preferred catheter both for diagnostic and PCI cases; less frequently we use Amplatz and Hockey-Stick catheters. For the left coronary artery, JL 3,5 is the workhorse catheter, especially for right TRA; for PCI we mostly use extra back-up curves (XB Vista Brite Tip, Cordis Corporation, Miami, FL), usually 3.5 or 3.0 when the left main is short and a better alignment with the LAD is desired.
Adequate engagement of coronary ostia is of paramount importance to ensure adequate support for interventional procedures. Our standard technique is to loop the guidewire against the aortic valve and to gently push the catheter. Then, to engage the right coronary ostium the wire is retracted and the catheter, flushed and attached to the 3-way stopcock, is retracted and turned clockwise; to engage the left main, we leave a small portion of the J-guidewire outside the catheter and gently turn it clockwise while retrieving the wire; in 90% of cases this simple manoeuvre allows for a progressive, non traumatic engagement of the left main.
For the engagement of aorto-coronary bypass, the multipurpose catheter is very good for bypass to the right coronary artery, whereas Amplatz catheters are our first choice for grafts to the left system. We recommend an angiography of the ascending aorta, possibly in two projections (LAO and RAO), since it helps in catheter selection and, paradoxically, can save contrast medium avoiding multiple test injections.
For the left internal thoracic artery, the Judkins right catheter is our first choice, since we prefer to perform sub-selective injections provided the angiographic quality is acceptable. If this is not the case or a PCI is needed, coaxial engagement is usually achieved with a mammary catheter, although the 3D RC catheter may represent a good alternative .
For catheter exchanges, we strongly suggest an over-the-wire technique, which does not necessarily need long guidewires (e.g. 260-300 cm) since it can be easily done also with standard-length guidewires (175 cm) under fluoroscopic guidance.

Haemostasis and post-procedural issues
Haemostasis following TRA is easily achieved, since the artery is superficial and can be compressed by a pressure bandage made with a piece of gauze and elastic adhesive tapes. This system is simple and cheap, but it compresses the ulnar artery and can result in venous congestion of the hand with discomfort for the patient. Several mechanical compressive devices are now available . In our Cath Lab we are using since 2003 the TR Band (Terumo Corporation, Tokyo, Japan), which consist of a plastic blade with inflatable balloons. The system allows selective compression of the radial artery and is well tolerated by the patient; we recommend progressive deflation of the balloon in order to minimize occlusive compression of the artery.
Indeed, post-procedural occlusion of the radial artery is the most frequent vascular complication of TRA, although it is usually clinically silent as long as the ulnar artery and palmar arch are patent. Reported rates of radial artery occlusion vary from 3% to 10% in anticoagulated patients .In a recent series, the 30-day rate of radial artery occlusion with the TR band was 3.2% .
Interestingly, the use of hydrophilic sheaths was not shown to reduce the occlusion rate as compared to standard sheaths .

Besides radial artery occlusion, another very infrequent complication that can be seen during follow up after TRA is represented by causalgia, or complex regional pain syndrome, which may cause serious regional pain with disability and is probably due to compressive damage to the median nerve .

CONCLUSIONS
In our experience a simple technique, not requiring modification of the angiographic suite or dedicated catheters, allowed us to progressively introduce TRA in our Cath Lab (since 2003) , achieving an overall TRA rate of 70%, with a rate of switch to TFA of 4%.
The growing body of evidence about the reduction of bleeding and, as a consequence, of major adverse events in patients with acute coronary syndromes receiving intense antithrombotic treatments will probably enforce the clinical role of TRA, making it a clinical necessity and not only an “exotic” technique.

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