Initial experience with left distal transradial access for invasive coronary procedures

Introduction: The recently described distal puncture of the left radial artery through the anatomical snuffbox (radial fossa) can be considered a refinement of the original technique. Its potential benefit is greater comfort to patients and operators, as well as maintenance of blood flow through the superficial palmar arch, in case of radial artery occlusion. Our goal was to evaluate the safety and feasibility of this new approach. Methods: A prospective registry of patients who underwent invasive diagnostic or therapeutic coronary procedures through the left distal radial artery. The primary endpoints were the access crossover rate and in-hospital accesssite related complications. Results: Between September 2017 and January 2018, 70 patients were screened, of which 61 (87%) were selected. In 4.9% of cases, left distal radial access cannulation was unsuccessful. The mean age was 62.2±11.6 years, 67.2% were male and 37.9% diabetic. Diagnostic procedures were performed in 79.3% of sample, using 5-French sheaths in 67.2% of cases. The duration of the procedure was 24.8±15.2 minutes and fluoroscopy time was 9.6±11.3 minutes. There was one (1.7%) case of access crossover, and no major vascular complications. In one patient, mild ecchymosis was observed, with concomitant asymptomatic distal artery occlusion. Conclusions: Left distal transradial access is feasible and safe in selected cases, when performed by experienced operators. Larger case series and randomized trials are required to determine its efficacy in reducing vascular complications when compared to the traditional technique.


IntroductIon
Transradial approach is the current choice for invasive coronary procedures, with prognostic impact on patients' morbidity and mortality, particularly for those at higher risk of vascular complications and major bleeding. 1Although right radial approach ensures greater comfort to the operator, anatomical variations and tortuosity in the right subclavian artery are more frequent, leading to greater use of contrast medium and longer fluoroscopy time, when compared to the left radial access. 2 In addition, some conditions, such as previous coronary artery bypass graft, morbid obesity, advanced age, short stature, patient preference or prior failure of right radial access, require using the left radial artery, reserving transfemoral approach for selected cases. 3istal puncture of the left radial artery through the anatomical snuffbox, 4 a triangular cavity on the dorsal aspect of the hand, delimited medially by the extensor pollicis longus tendon, and laterally by the extensor pollicis brevis and the abductor pollicis longus tendons, with a floor formed by the scaphoid and trapezium bones, 5 has been recently introduced as a refinement of the technique described 25 years ago. 6Its potential benefit is offering greater comfort to patient and operator during the procedure, besides maintaining blood flow through the superficial palmar arch in case of radial artery occlusion.
The objective of this study is to report the initial experience with left distal transradial access performed by experienced radialists, focusing on the feasibility and safety of the procedure.

metHods
Patients referred for diagnostic or therapeutic invasive coronary procedures, and selected for left transradial approach, were checked for the presence of pulse suited for puncture and cannulation through the anatomical snuffbox.The patency of the superficial palmar arch by the modified Allen test or the Barbeau test was not routinely evaluated.
The left arm was placed on the abdomen, comfortably supported by a cushion, with the operator standing to the right, close to the patient's head (Figure 1).Patients were asked to hold their thumb with four fingers and slightly abduct their hand to bring the distal portion of the radial artery to surface.After injecting 2 to 3mL of 2% xylocaine, filling the radial fossa, the artery was punctured using a 22-gauge polyethylene catheter over the needle, at an angle of 30 to 45° pointing medially, avoiding transfixation (Figure 2).A 0.19-inch guidewire was inserted, followed by a small skin incision with a scalpel blade no.11 for insertion of a short 5-or 6-French (Fr) hydrophilic introducer sheath (Figure 3).A solution containing 5,000IU of heparin sulfate and 10mg of isosorbide mononitrate was infused through the introducer system.During the procedure, the left upper arm was bent over towards the pa-tient's right groin, allowing the operator to keep at a safe distance from the radiation source (Figure 4).Hemostasis was obtained by compression with a porous elastic adhesive bandage and gauze or a selective radial compression device (Figure 5).
The feasibility of the technique was determined by the need for access crossover to complete the procedure.Vascular complications, such as hematoma, pseudoaneurysm, arterial occlusion, ischemic injury of the hand, compartment syndrome, arteriovenous fistula, infection or the need for vascular surgery repair were evaluated upon hospital discharge.
Absolute and relative frequencies were presented for categorical variables, and summary-measures (mean and standard deviation) for numerical variables.This study was approved by the Institutional Review Board of Faculdade de Medicina de Marília, number 5413, with registration in Plataforma Brasil (CAAE: 90126418.1.0000.5413).The Informed Consent Form was obtained from all subjects.

results
Between September 2017 and January 2018, 70 patients were screened for left distal transradial access, of which 61 (87%) were selected.The reason for excluding other patients was the presence of a pulse not suited for punc ture upon physical examination of the anatomical snuffbox.Access failure occurred in three (4.9%)cases, and the final sample consisted of 58 patients.The clinical characteristics of the study population are shown in table 1.The mean age was 62.2 years, 67.2% were male and 37.9% had diabetes mellitus.Stable clinical presentation accounted for 56.9% of indications, and 20.7% of patients had a history of coronary artery bypass graft.Diagnostic procedures were performed in 79.3% of sample, and 5Fr intro ducer sheaths were used in 67.2% of cases (Table 2).Hemostasis was predominantly obtained by local compression with semi-elastic adhesive bandage and gauze.

Journal of
The main indications for left distal transradial approach are reported in table  Traditional ENtry point and Distal puncturE of Radial Artery), initiated in 2015 with results expected in 2018, in which 830 patients were randomized to traditional vs. distal transradial approach.The primary endpoint of the study is the incidence of radial artery occlusion 12 months after the procedure.As potential benefits of the new technique, we highlight the greater comfort to patients and operators, since it eliminates the need to place the upper arm in supine position, and the arm can be comfortably positioned towards the right inguinal region.With the introducer sheath on the dorsal aspect of the hand, visible to the operator, catheters approach.One patient (1.7%) required access crossover, and the right femoral artery was chosen due to tortuous aortic arch and impossibility of selective coronary cannulation.All patients were evaluated upon discharge, with no complications, such as hematoma, ischemic injury, functional deficit or left radial artery occlusion at the usual site of palpation.In one case, mild ecchymosis was observed with no distal pulse.dIscussIon Our initial experience with left distal transradial approach through the anatomical snuffbox showed that this technique is not only feasible, with only 13% of the initially selected patients not being candidates, and less than 2% requiring access crossover, but also safe, with only one case of distal arterial occlusion, with no major access siterelated complications.
Described in 2011 by Avtandil Babunashvili as an alternative for early retrograde recanalization of occluded right radial artery after elective coronary angiography in two patients, 7 the technique is now advocated by the same author as a preferred strategy for coronary procedures.His aim is to reduce access site-related complications and more than 700 cases were included in his series up to January 2017 (personal communication).The author is currently conducting the TENDERA trial (Comparison between can be more easily handled without the need to bend over the patient, especially the obese, and operators can keep at a safe distance from the radiation source.In addition, since distal puncture is performed after the point of emergence of the superficial palmar branch, in case of arterial occlusion, blood flow through the palmar arch would not be compromised and the risk of ischemic injury would be minimal.Also, by avoiding the usual puncture site and subsequent related complications seen on imaging studies, such as negative arterial remodeling, decreased lumen diameter or thrombotic occlusions, access would be preserved for possible future percutaneous interventions or as an option for surgical grafting in coronary artery bypass graft procedures. 8imilar to other recently introduced techniques, there is a learning curve characterized by greater difficulty of arterial puncture, which decreased with a larger number of procedures and did not lead to excessive duration of the procedure or fluoroscopy time, nor greater need for access crossover. 9,10The absence of dedicated devices to obtain hemostasis with the new access route, the insufficient length of the catheters used in the procedure -particularly in taller individuals, a smaller arterial diameter and the absence of a suitable pulse upon physical examination are currently considered limitations of the method, although vascular ultrasound guidance may attenuate the latter two. 11he only case series publish to date on the topic, by Kiemeneij, 4 reports the results of 70 patients submitted to invasive diagnostic and therapeutic coronary procedures, and all had an indication for using left transradial approach, which was the same criterion adopted and advocated by our group.Except for a higher access crossover rate (11%), we found similar data regarding duration of the procedure (24.8±15.2minutes), fluoroscopy time (9.6±11.3minutes) and puncture site-related complications (1.5%).
The non-random nature of our work and the small number of patients enrolled were limitations of this study.

conclusIons
The initial experience with left distal transradial ap proach for invasive coronary procedures demonstrates it is a fea-sible and safe technique in selected cases, when performed by experienced radialists operators.Larger case series and randomized trials are required to determine the efficacy of this approach in reducing vascular complications when compared to the traditional technique.

Figure 1 .
Figure 1.Left upper arm placed on the abdomen, and operator standing to the right, close to the patient's head.

Figure 2 .
Figure 2. Distal puncture of the left radial artery through the radial fossa, using a catheter over the needle.

Figure 3 .
Figure 3.A 5-French sheath inserted in the distal left radial artery (image obtained in the end of the procedure).

Figure 4 .
Figure 4. Left upper arm placed on a cushion, pointing to the right groin with no need for supine position.

Figure 5 .
Figure 5. Hemostasis obtained by compressive dressing with semi-elastic adhesive bandage and gauze.

Table 2 .
Angiographic and procedure characteristics 3, and the most common reason was a previous failed attempt to use the right transradial PCI: percutaneous coronary intervention; CAD: coronary atherosclerotic disease.

Table 3 .
Indication for left distal transradial approach LIMA: left internal mammary artery.