Competence in EVAR techniques

Lars Lönn (L) and Michael Strøm (R)

Endovascular aneurysm repair (EVAR) is a highly specialised and potentially complicated procedure requiring knowledge and skills from several cognitive domains. Indeed, EVAR involves several intricate procedural steps, which have been reflected in a flat learning curve for entry into practice. The technical outcome is dependent not only of the technical skills and the experience of the surgical team, but also on careful preoperative planning ensuring that a stent graft compatible with the anatomy is chosen, write Michael Strøm and Lars Lönn. 

EVAR has been reserved for physicians with a high degree of experience in endovascular procedures. Training has been through the classical master-apprentice method. Proficiency has in this model been judged by the supervisor. However, trainees learn at different paces and a certain number of procedures do not ensure competency.

There has been a shift in medical education towards competency-based education where the learner trains to a predetermined level of proficiency based on validated tests. Basically, the concept is to train to a predefined standard. The purpose is to demonstrate skilful application of knowledge by performing the relevant skills at a proficient level.

Implementing competency-based education in training requires validating evidence for the assessment. The contemporary framework endorsed by the American Educational Research Association requires validating evidence from five sources: content, response process, internal structure, relationship to other variables and consequences to be explored.

Performing an EVAR procedure while handling the X-ray equipment and more (ie. C-arm, table contrast pump) with the goal of producing acceptable working images while abiding by the ALARA (as low as reasonably achievable) principle may be overwhelming for a physician entering the practice. Combining this with planning and sizing may result in cognitive overload impairing the effect of training.

Procedural skills represent the ability to follow a given protocol closely. Due to the nature of EVAR (eg. bilateral femoral artery access) the methodical introduction of equipment through the arteriotomy according to protocol allows successful results. Failure to do so may render hours of preparatory work meaningless as the necessary instrument may not be able to be deployed properly causing lost cath lab time, wasted equipment and extended risk of exposure for the patient. Literally speaking, there is no room for error.

Thus, to put the procedure into key components, each of them can be addressed by structured and validated assessment tools. That is, planning and sizing at the workstation as one focal point, and the technical procedure as another.

Simulation-based training has been shown to reduce medical errors and to cut the learning curves. In the skills centre repetition of training activities is feasible as is direct objective feedback to the learners and debriefing. Structured feedback has been shown to increase the learning and performance of trainees. Deliberate practice of isolated procedural steps allows for direct and targeted training in special areas of interest.

Case rehearsal is a training modality in which original patient DICOM (Digital Imaging and Communications in Medicine) data are uploaded to the simulated environment. In a comprehensive environment individualised training cases and content can be created. The technique allows the physician to size, plan and perform a complete immersive case prior to the actual procedure by matching the content to the need. Ultimately, success of EVAR depends on precise anatomical fit of the prosthesis delivered by trained and certified operators. In conclusion, learning a skill and perfecting it are two different phases in the pursuit of mastery of manual skills training.

Michael Strøm and Lars Lönn are at the University of Copenhagen, Copenhagen, Denmark


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