Left distal transradial access in the anatomical snuffbox
for percutaneous coronary intervention
JAVIER COURTIS, MAGDALENA DIMITROFF, ANALÍA GONZÁLEZ
Instituto Oulton (Córdoba, Argentina).
Facultad de Biología y de
Cs. Exactas, Físicas y Naturales, Universidad Nacional de Córdoba.
Córdoba Capital, Argentina E-mail
Recibido 18-DIC-2018 – ACEPTADO después de revisión el 27-ENERO-2019.
There are no conflicts of interest to disclose.
Left distal transradial access (ldTRA) in the anatomical snuffbox (AS) has advantages over standard radial access in terms of comfort levels for the patient and lower risk of thrombotic occlusion of the proximal radial artery. The aim of the present study was to test the feasibility and safety of the procedure. Methods and Results - 51 consecutive patients assigned to a single operator underwent a diagnostic or therapeutic coronary intervention through ldTRA access from the proximal portion of the AS. The procedures were successfully performed in 82% of the cases; The most common cause of failure was the impossibility of advancing the 0.025” wire beyond the puncture site. Conclusions: The ldTRA approach from the anatomical snuffbox is an attractive and feasible option for both, patients and operators. Additional studies are needed to evaluate the clinical benefits.
Since the first publication in 1989 about the radial artery access for coronary cineangiography (CCA)  and in 1993 for transluminal coronary angioplasty (TCA) , this technique may still become the “gold standard” over time to perform coronary catheterizations [3-5]. Its main advantages with regard to femoral access are: a) greater safety (reduction of vascular complications and major bleeding); b) more wellbeing and comfort (immediate movements after the procedure and less discomfort in general and at the puncture site); and c) more preference by intervened individuals [6,7].
Historically, the most widely used radial access has been the right one, with the main reason to choose it being the simple fact that the position for the interventionist cardiologist to work is more comfortable on that side. However, on numerous occasions, left transradial access is required to be used, namely: a) right radial artery occlusion; b) underdeveloped right radial artery; c) little experience with transcubital access; d) tortuosity, sclerosis or marked vascular calcifications; e) aberrant right subclavian artery; f) arteriovenous fistulae in the right arm or forearm; g) patients with myocardial revascularization surgery and requirement of left internal mammary artery bypass angiography; and h) preference by the patient. Undoubtedly, left radial access could be very convenient in all the conditions mentioned above . Moreover, an overlooked factor, but very important nonetheless, is the fact that the left access could be more advantageous in right-handed patients, as there would be no transient disability in the dominant hand due to the hemostasis process and possible painful symptoms after the procedure. In terms of feasibility and results, both accesses (left and right) are similar ; however, left radial access may be more cumbersome for the operator, particularly in obese patients, as he/she needs to lean over the patient, which is ergonomically uncomfortable and exposes the operator to more doses of radiation. A simple solution for these problems, is to access from the left side but through the distal radial artery; i.e. from the dorsal part of the hand and at the level of the anatomical snuffbox (foveola radialis), which has been called left distal transradial access (ldTRA).
The anatomical snuffbox (ASB) is a depression on the radial side of the wrist when the thumb extends, which is laterally limited by two tendons, one of the thumb’s abductor pollicis and the other the abductor pollicis brevis. In turn, medially it is limited by the pollicis longus and the radial artery crosses through the floor of the ASB, which is constituted by the scaphoid and trapezium bones . Figures 1-2.
Figure 1. Posterior view of the radial portion of the left wrist. 1 = extensor pollicis longus muscle tendon; 2 = extensor pollicis brevis muscle tendon; 3 = head of the first metacarpal bone; 4 = anatomical snuffbox.
Figure 2. Posterior view of the radial part of the left wrist. 1 = abductor pollicis longus muscle tendon; 2 = extensor pollicis brevis muscle tendon; 3 = extensor pollicis longus muscle tendon; 4 = cephalic vein; 5 = terminal branches of the superficial branch of the radial nerve; 6 = radial artery; 7 = superficial branch of the radial nerve; 8 = extensor retinaculum; 9 = extensor carpi radialis longus muscle tendon; 10 = extensor carpi radialis brevis muscle tendon.
Although ldTRA was published for the first time in 2011 by Babunashvili et al, with the aim of opening a retrograde way into the previously occluded left radial artery , with the passing of time small studies arose that proved its feasibility, and that it could be used as an access site for coronary procedures with sheaths and catheters of 4, 5 and 6 Fr [8,12]. Other features that make this technique relevant are: a) one occlusion in this puncture site does not alter the distal flow of the hand, as this is preserved through the superficial palmar arch; b) the risk of retrograde thrombosis in the main radial artery is reduced, thus preventing ischemia and forearm and hand disability; and c) the technical difficulty to make the catheters advance through marked tortuosity in the supraaortic arteries; and therefore, failure to complete the test is more common through this access site; i.e. the right access ; as well as rupture of atherosclerotic plaques with distal embolization due to sudden maneuvers in arteries at the base of the neck ; besides the fact that when the procedure through the right radial access extends due to the tortuosity of the subclavian artery, there could be an additional embolic source added; and d) an inexperienced operator should consider the left radial access as it demands a shorter learning curve than the right radial access due to similarities to the femoral artery access .
All that has been previously mentioned, besides that in our area and to this date there are few data on the feasibility of ldTRA puncture, has led to the performance of this study, with the aim of investigating the efficacy and safety of the ldTRA for percutaneous coronary interventions.
METHODS The presence of a well-developed distal radial artery is detected by manual palpation of the pulse, and to prevent pricking a terminal branch, the puncture is made in the most proximal portion of the ASB.
Position and preparation of the patient (Figure 3). With previous asepsis in all the possible puncture areas (left ASB, right radial and both femoral arteries), the left upper limb is placed comfortably on the left side of the patient, with the hand slightly flexed to the inside and looking to the right groin, then the patient is asked to hold his/her thumb below the other four fingers. After disinfecting, the patient is covered with sterile clothes that contain four holes (two radial ones and two femoral ones) due to the possible need of other accesses. The operator takes a position at the right side of the patient and injects subcutaneously into the left ASB, 2-3 ml of lidocaine at 1% along with 100 µg of nitroglycerin.
Once local anesthesia is applied, the arterial puncture is done using preferably a 20-gauge needle, which is led to the strongest point of the radial pulse in the proximal portion of the ASB, in a 45-degree angle, and in a direction from the lateral to the medial. It is recommended not to make very deep punctures, as the needle when touching the periosteum of the scaphoid or trapezium bones may cause pain. Once the artery has been punctured, and following the Seldinger technique, a 0.025” hydrophilic guidewire with flexible tip and J-shaped is introduced. To prevent damages to the tip of the introducer and therefore to the artery, a small incision is made on the skin, followed by the placement of a 5 or 6 Fr introducer sheath, according to the type of procedure. After the administration of a spasmolytic (200 µg of nitroglycerin) and a dose of sodium heparin adjusted to the weight of the patient (70 Ul/Kg) through the side arm of the introducer, the operator may hold a position at the level of the knees of the intervened individual, always from the right side, and thus start the procedure by introducing the necessary catheters according to the case. On some occasions, the fact of having the left elbow flexed could trigger an arterial spasm which makes the manipulation of catheters difficult and causes pain to the patient; in such situations it is advisable to stretch the joint as much as possible and to use smaller and hydrophilic material, besides performing a manipulation as gentle as possible.
Figure 3. ldTRA. A) The left hand of the patient is placed on his/her right groin, with the thumb covered by the rest of the fingers exposing the ASB and the back of the hand. B) The operator is placed at the right side of the patient and performs the puncture on the proximal part of the ASB, at the point where the pulse feels strongest; and subsequently a small incision is made on the skin before placing the introducer sheath chosen according to the case. C) The operator, from the right side of the patient and at the level of the his/her knees approximately, performs the procedure following the usual techniques. D-F) Once the test is finished, hemostasis is ensured through a compressive bandage, in such a way that it would ensure a normal plethysmographic curve and a proximal radial pulse remains palpable.
Hemostasis and control. Once the procedure ends, the introducer is withdrawn, having previously applied 200 µg of nitroglycerin through the side arm of the introducer sheath, and a gauze swab is placed on the puncture site along with a semi-elastic bandage, which should compress in such a way that it should prevent bleeding, besides preserving the radial pulse palpable, and should obtain a plethysmographic curve of the pulse oximeter as normal as possible. Two to three hours later, compression is moderately loosened, and instructions are given to the patient to withdraw the semi-compressive bandage 12 hours later. Before discharge, the presence of radial pulse is verified in the distal forearm and an evaluation is made on the intensity of pain after the procedure through the visual analogue scale (VAS) .
Data collection. Besides the demographic, clinical and procedure data, the total duration of the procedure was recorded (since the puncture to the introducer withdrawal), as well as the puncture time (since local anesthesia until the placement of the introducer sheath), the time of total radioscopy and the amount of contrast material used. Also, the presence of major adverse cardiovascular events (MACE) was analyzed, defined as the presence of any of the following clinical situations: cardiac death, myocardial infarction, stroke, and the need to repeat TCA in the treated vessel within 24 hours after the procedure.
Moreover, the severe complication of the arterial puncture site was assessed, defined as forearm bruise ≥ degree III (when it extends more than 10 cm from the puncture site and is accompanied by forearm blood muscular infiltration) with requirement of blood transfusion or to repeat the compression. Finally, the presence of major bleeding was also examined, defined according to the GUSTO criterion . Both MACE and bruising ≥ degree III and major bleeding were evaluated during the first 24 h of the procedure.
From the beginning of April until the end of June 2018, 51 of 125 patients (41%) assigned to the operative program of the author (JC), underwent left distal transradial access. The main reasons why ldTRA was not conducted in the remaining 74 patients were: a) weak or absent pulse in ASB; b) logistic reasons; c) venous cannula near the ASB; d) patients with left dominant hand (left-handed); and e) preference of the patient.
The characteristics of the patients and the procedures are summarized in Table 1. From the 51 patients who underwent ldTRA, most were men (78%), with an average age of 63 years, average height 171 cm, weight 87 kg, and slightly hypertensive at the moment of the test. The procedure had a general average duration of 29 minutes; the average time of puncture was 3.1 minutes; that of radioscopy 6.2 minutes and the amount of contrast material used was 95 ml. In average, two catheters were used per patient, and in most (88%) with a 5 Fr size. Although almost all the procedures were diagnostic (96%), 6 cases (12%) were therapeutic, from which 2 (4%) were scheduled and 4 (8%) ad hoc TCA. After the procedure and immediately before discharge, left radial pulse was present in 100% of cases and the pulse oximeter plethysmographic curve in the left thumb was normal in all the population studied (100%). No case was recorded of MACE (0%), a severe complication of the site of arterial puncture and major bleeding, and 44 (86%) patients displayed a VAS between 0 and 3 points (nothing or a little pain) when leaving the center.
Table 1. Characteristics of patients (n=51)
Total duration of the procedure (min)
Puncture time (min)
Radioscopy time (min)
Amount of contrast material (ml)
Number of catheters used
ad hoc TCA
Requirement of another Access
Radial pulse palpable before discharge
Normal plethysmographic curve before discharge
Severe complication of the arterial puncture site
Major bleeding (GUSTO criterion)
Intensity of pain (0-3) according to VAS
In 9 (18%) patients, the introducer sheath could not be placed form the ldTRA, being necessary to find another access, so the “traditional” right transradial access was used in all cases. In 2/9 (22%) patients, it was not possible to puncture the artery, in spite of presenting a good pulse (this occurred during the first 10 cases of this study); in 6/9 (67%) cases, although it was possible to puncture the artery, the 0.025” guidewire could not be made to advance beyond the puncture site (most of them within the first 25 cases of this study); and a single case (11%), although it was possible to place the introducer sheath and obtain access to the aortic root from the ldTRA, the great tortuosity of the left subclavian artery and the coronary anomaly present (aberrant right coronary artery) led to the right radial artery puncture in the usual site, thus achieving a proper cannulation and with a catheter dedicated to the origins of both coronary arteries.
One of the concerns is whether the diameter of the distal radial artery at the level of the ASB is appropriate to allow a safe coronary catheterization and comfortable for the patient. This early experience in our area shows the feasibility of ldTRA for coronary artery procedures with 5 and 6 Fr catheters, and in stable and scheduled patients. In general, this is a well-tolerated procedure, as almost all patients experienced a very low pain intensity. Also, it was proven that this is an extremely safe technique, as none showed major complications on the access site; and finally it was proven that it is a highly efficient technique, as in more than 80% of cases the procedure could be achieved.
The potential advantages of this technique are several: a) right-handed patients are free to use their right arm without restrictions after the procedure; b) the position of the arm during the intervention is comfortable both for patients, as they are not required to expose the palm of the hand; and for the operator, because it allows to work as usual from the right side, not being necessary to lean above the patient to reach the left wrist, particularly in obese patients or operators who are not particularly tall; c) in a similar manner to right radial procedures, the operator may work at a safe distance from the radiation source; d) the risk of total occlusion of the radial artery is reduced with this technique, as the artery does not suffer the trauma by puncture or extended hemostasis, so there is no damage done to the vessel wall; e) anterograde blood flow remains through the superficial palmar arch; even in the case of thrombotic occlusion in the distal radial artery in the ASB; f) catheters of the Judkins or Amplatz types, or other traditionally designed forms for the femoral access, follow a more “natural” shape from the left access, and this is considered by some as an advantage on the radial access; g) another advantage of ldTRA is that if the patient flexes his/her left wrist, hemostasis is still ensured as the puncture site is more distal; h) less congestion in the hand, as hemostatic compression does not obstruct major veins; i) less intense pain in the puncture area as at this level nerve endings are very small.
To this date, few studies have evaluated ldTRA. Babunashvili et al  described this technique for the first time in year 2011, and on such occasion and in two patients, they managed to rechannel the right radial artery (totally occluded after CCA some days before), puncturing the distal end of it and at the height of the anatomical snuffbox. Subsequently, Kiemeneij published a series of 70 selected patients in whom ldTRA was conducted due to CCA (61%), TCA (36%) or evaluation of coronary flow fractional reserve (3%) . The rate of success reported in this study was 89% (n=62), with the difficulty to make the guidewire (0.025”) advance from the puncture site being the main cause of access failure, a situation that could be improved using a smaller guidewire (0.018”), with steel body and soft and very flexible proximal tip [19,12]. In another recently published study, the feasibility and safety of performing ldTRA was also shown in 52 consecutive patients, both for diagnostic and therapeutic procedures, with a rate of success of 90% and using 6 Fr catheters in 96% of cases .
Two aspects that will require more investigation are the use of ldTRA as a potential site for retrograde rechanneling of totally occluded radial arteries and in those patients in whom radial artery should be preserved for subsequent procedures (myocardial revascularization surgeries and arteriovenous fistula by terminal renal disease).
As the distal radial artery is smaller, puncturing it is more difficult, and so it is essential to fulfill a learning curve. In the small series of patients presented, it is shown how a high-volume operator can adopt this technique quickly, taking into account that at the beginning he/she should start by more appropriate patients (palpable pulses, normal blood pressure, with a standard size and clinically stable), and as long as the operator increases his/her case history, his/her technique will improve, as well as the success of the procedures.
Very likely this technique is not appropriate for all patients, for the simple reason that in a considerable number of them, pulse in the ASB is not clearly palpable. Although ldTRA will not replace “traditional” transradial access, it should be considered in patients that prefer or require a procedure through the left arm, in the presence of palpable arterial pulse in the ASB.
On occasions, distal radial artery thrombosis may occur in the ASB, but it is very unlikely for ischemic complications to occur with this technique, as the distal flow of the hand is preserved in these cases due to the superficial palmar arch.
A randomized comparison with the conventional right transradial access would be ideal. The conventional technique has been practiced for more than 25 years and a comparison with ldTRA that is only just starting, puts the latter in an openly disadvantageous position to perform such investigation, due to the need to primarily strengthen the learning curve (puncture and navigation of the material could be different between both techniques) to then be able to compare the two technically different methods.
Left transradial access for percutaneous coronary interventions at the level of the anatomical snuffbox is feasible and safe. This new technique should fulfill a learning curve and it will require thorough investigations that show the advantages both for patients and operators.
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