Trans-radial access (TRA) is now the preferred access site for percutaneous.

coronary interventions (PCI) in experienced radial centers. It decreases access site bleeding and vascular complications, reduces post-procedural costs and allows same day discharge [ ].

TRA is of particular benefit in patients with increased risk of bleeding and vascular complications: acute coronary syndrome patients, female patients, the elderly, obese, hypertensive and low weight patients, with renal failure, low platelet count and anemia [ ].

Particularly in ST-segment elevation myocardial infarction (STEMI) patients, TRA has proven to be better than trans-femoral access (TFA) in reducing access site bleeding and overall major adverse cardiac events (MACE) and mortality [ , ].

Furthermore, in patients with acute coronary syndromes (ACS) undergoing invasive management, TRA is associated with a lower risk of acute kidney injury than TFA [ ].

The mechanisms by which TRA reduced the incidence of AKI might be due to a reduction of bleeding events [ ], by a reduction in embolization in the renal circulation, or by a combination of both [ , ].

According to the recommendations given by the European Society of Cardiology (ESC) and the latest guidelines for treatment of NSTEMI [ ], STEMI [ ] and most recently Myocardial revascularization [ ] TRA should be the default approach for PCI in experienced transradial centers (class I, level of evidence A). Therefore, more attention should be paid to strategies for achieving successful TRA.

Still TRA is considered a technically more complex procedure than TFA, associated with physician’s learning curve for TRA [ ]. It has limited compatibility with larger devices and can be challenging in cases with radial artery (RA) anomalies and/or high degree spasm.

It is important to understand any issues that could influence the success of TRA percutaneous interventions.

The reported overall failure in TRA procedures is between 1% and 10% [ ].

Prior studies have also reported that arterial anomalies found from wrist to aorta influences the success of TRA and are cause for access crossover from TRA to other access sites [ ].

In this issue of the CRM, Rigatou Aggeliki et al. present a review of various strategies how to increase utilization of forearm approach for cardiac catheterization in challenging group of patients: post-coronary artery bypass graft surgery patients, patients with chronic kidney disease and end stage renal disease, patients undergoing complex procedures (CTO, rotablator, bifurcation lesions), elderly and patients with cardiogenic shock.

Studies demonstrating feasibility and safety of radial and ulnar approach and the importance of an alternative access site after initial access site failure have been reviewed.

Studies have also addressed technical aspects of the procedure delineating best practices and tips for radial access, traversing difficult arm vasculature, and radial artery hemostasis. These studies have broadened the application of TRA, improved the transradial technique, and favorably impacted patient outcomes [ ].

The most important parameter that should be taken into account when a challenging and complex coronary lesion is being faced is the operator’s experience. In experienced hands, the rate of crossover from forearm to femoral access is minimized, even after the inclusion of complex lesions, without sacrificing procedural outcome.

Considering the complex and elegant arterial circulation of the human arm and hand, which provides extensive superficial and deep collaterals, suggests another route for angiography—the ulnar artery.

The ulnar artery is the continuation of the brachial artery and was the initial access site used by Zimmerman in 1949 [ ], for retrograde catheterization of the left ventricle. It is frequently larger and has a straighter course compared with the radial artery and rarely has anomalies.

A case series from a high-volume center demonstrated the feasibility and safety of utilizing ipsilateral trans-ulnar access (TUA) even if initial radial artery access fails [ ].

Expertise with transulnar procedures could reduce femoral crossover rates and thus further affect bleeding and vascular complications, particularly in high-risk patients such as those undergoing primary PCI for STEMI [ ].

Recently, we have reported 6% crossover rate from 30,848 consecutive patients with primarily chosen TRA. Crossover direction was primarily done to ipsilateral TUA 3,8%, left radial access 1,5% with only 0,6% of patients transferred to TFA. Despite higher rate of crossover to ipsilateral ulnar access, there was no single case of hand ischemia registered post-procedurally or at follow up [ ].

Furthermore, routine pre-procedural radial artery angiography was associated with reduced overall procedural time and TRA crossover rate and lower rate of access site bleeding complications [ , ].

Lately, the distal radial artery, in the anatomical snuffbox has been demonstrated as an alternative access site for cardiac catheterization.

It seems a feasible option, having the advantage of faster hemostasis and probably lower risk of RAO [ ].

Left distal radial access in the anatomical snuffbox seems particularly ergonomic and more patient and operator friendly. Also, it could be elegantly used in CTO PCIs as a part of a bilateral radial access.

The main complication of the forearm approach for cardiac catheterization is radial artery occlusion (RAO), with an incidence of 1–10% in different trials [ ]. There is need to establish strategies for minimizing radial peri -procedural injury, in order to accomplish the patency of the RA used for future procedures. Slender techniques using lower profile of introducers and smaller size catheter are less aggressive and associated with lower RAO rate.

Percutaneous cardiac procedures begin and end with access site management. The use of so-called patent hemostasis method and simultaneous ipsilateral ulnar artery compression, may further decrease the rates of radial occlusion [ , ].

Although, total wrist access might be safely achieved in most patients,

procedural time and success should not be sacrificed by forcing wrist access and assessment should be done individually.

The femoral access expertise should be preserved despite adopting the default radial-first approach. The British Cardiovascular Intervention Society (BCIS) Registry results showed reassuringly that high-volume TRA PCI centers do not lose femoral skills overtime [ ].

For coronary angiography and intervention, radial access has emerged as the dominant approach because of its superior safety. The data supporting TRA have evolved from examining “hard” clinical outcomes such as bleeding, vascular complications, and MACE, to patient-oriented endpoints such as functional outcomes. It is clear that, from the available evidence radial access not only improves clinical outcomes and reduces costs, but also has no adverse effects on arm or hand function [ ].

With the extensive complex arterial circulation available in the upper extremity and the emerging data on ulnar access, we may well be approaching the post-femoral era for coronary angiography and intervention.