Ulnar Artery Access
The TRA may be difcult or associated with increased risk of complications in the presence of signicant radial artery abnormalities, severe loops and curvatures, after failed radial artery cannulation and when the radial artery was repeatedly used previously.
Transulnar artery cannulation (TUA) has been proposed as an alternative access for interventions in patients with a small-calibre radial artery or a thin radial pulse and stronger pulsation of the ulnar artery. Larger studies have further conrmed the safety and effectiveness of TUA as an alternative wrist approach to TRA for coronary interventions.16,53
The procedural success, advantages and complication rates for transulnar interventions appear similar to those from the TRA.15,53 Adding the ulnar artery access expertise could further reduce the crossover rate to TFA and lower the intrinsic risk of bleeding and vascular complications associated with the TFA. When the TRA is not possible or fails, the TUA may be considered as a safe alternative before reverting to the TFA.16 The TUA is a viable option for the high-volume radial centres, when performed by the expert radial operators who are skilled in ulnar artery cannulation.53
Limitations of the Transradial Access for Complex Percutaneous Coronary Intervention in Acute Coronary Syndrome
onger procedure duration and radiation exposure during the learning curve, and the potential influence on radial artery patency have slowed down acceptance of the TRA. Technique of TRA requires a specific set of skills, and is associated with a significant learning curve. With appropriate training, similar success rates with the TRA and TFA may be achieved even in complex ACS cases. The learning curve is highly individual and more experienced operators may become proficient sooner.
To achieve the best results in TRA interventions, individual operators and institutional teams should aim at maintaining the highest feasible rate of TRA. After the learning curve has been completed, for over 50% TRA in routine practice, a minimum of 80 procedures per year per operator is recommended.54
A stepwise approach to learning is proposed according to clinical characteristics and PCI difculty. ACS-PCI is proposed as the last step (NSTEACS and STEMI patients), due to multifaceted clinical settings and PCI complexity. The highest level of competency is obtained when patients requiring complex clinical management can be managed with timely and technically procient control of PCI, irrespective of vascular access anatomy.54
The TRA is associated with very low incidence (0.2 %) of major vascular complications.10 Haematomas are usually minor, affecting only subcutaneous tissue. Unlike groin bleeding, subcutaneous bleeding after TRA is rapidly noticed and can be controlled by local compression. Major vascular complications like compartment syndrome are completely avoidable.
Radial artery occlusion (RAO) is the most common complication, affecting 1.5-33.0 % shortly after the procedure, depending on the antithrombotic regimen, sheath size and protocol for haemostasis.55 Although usually asymptomatic, RAO is an important consequence of TRA, as it prohibits future ipsilateral TRA. Preserving radial artery patency is of paramount importance. Proper anticoagulation, downsizing of material (sheathless catheters) and shorter and less forceful 'patent haemostasisÔÇÖ of the radial artery with the emphasis on maintaining adequate arterial ow, considerably reduces the risk of RAO. It is important to remember that almost all potential complications are preventable by accurate preprocedural evaluation, meticulous technique and optimal post-procedural management.
The incidence of RAS has varied considerably (4-30 %) depending on its denition, study population and the expertise of the operators.54 Spasm is the second most common cause of radial access failure after anatomical variations. The incidence of moderate/severe RAS is low in centres with a default TRA (2.7 %). Its development and procedural failure (0.7 %) appears strongly related to the numbers of puncture attempts and the use of larger-bore sheaths.56
Technical Recommendations for Complex Percutaneous Coronary Intervention in Acute Coronary Syndrome
Challenging anatomy must be avoided to minimise the risk of complications and shorten the duration of both the procedure and radiation exposure. For this reason, a systematic preliminary angiogram of the forearm arteries through the radial introducer is recommended. The nal choice of procedure will depend on the level of expertise of the operator, and the equipment required. In patients with cardiogenic shock, TRA procedures can be performed if the radial artery is palpable while leaving two potential femoral accesses for IABP counterpulsation or more complex cardiac-assist devices (see Figures 1-4).
The right side is usually more ergonomic to the operator; however, the left radial approach might be more convenient in the learning phase because of similar catheter handling when compared to the femoral approach. Even if dedicated catheter shapes are available, traditional femoral shapes accommodate the radial approach easily. Coaxial alignment with the target coronary artery is mandatory and requires different handling for the right radial versus femoral approach. The choice of guiding catheter (diameter, shape, size) is essential for adequate back-up. Most PCIs can be performed through 6 Fr guiding catheters, including complex cases, thrombus aspiration, post-CABG and left main bifurcations.
In selected patients of large stature, larger catheters (7 or even 8 Fr) or sheathless guiding catheters can be considered, allowing for large-lumen guiding catheters to be used in a small radial artery. However, these catheters, though useful in selected cases, are more difcult to handle in complex procedures due to lower back-up.
RAO should be prevented during and after the procedure with systematic assessment of the arterial patency.57 Spasm prevention with 3-5 milligrams (mg) verapamil administered intra-arterially through the sheath is routinely recommended. Specic early and delayed post-procedural attention to forearm haematomas is mandatory.