Short-term results are favorable for EndoVascular Aneurysm Repair (EVAR) compared to open surgery. One of the major drawbacks to this shift is the need for fluoroscopy and contrast dyes to visualise endovascular devices. The use of fluoroscopy exposes both patients and caregivers to harmful ionizing radiation. Because of the harmful effects of radiation, recent radiation protection guidelines strongly recommend as low as reasonably achievable (ALARA) principle. The need for additional radiation-reducing navigation techniques is high, with the ultimate goal of performing endovascular procedures without radiation at all.

In response to these challenges, Centerline Biomedical (Cleveland, Ohio, USA) has developed a proprietary electromagnetic tracking and positioning system called the Intra-Operative Positioning System (IOPS). This medical device provides surgeons with 3D visualization for increased surgical precision while reducing the radiation exposure for patients and healthcare professionals. IOPS provides 3D electromagnetic navigation of interventional devices as an adjunct to fluoroscopy. During the intervention, the IOPS devices can be visualized with on-screen image guidance. The IOPS guidewires and catheters can be used together or combined with off-the-shelf 0.035-inch catheters and guidewires, as needed.

This study aims to describe the influence of IOPS technology on radiation exposure during cannulation of the contralateral limb (CL) during standard EVAR.

Background:

The current standard of care for abdominal aortic aneurysm (AAA) is endovascular aneurysm repair (EVAR) which has been suggested as the treatment of choice by both European and American guidelines . Although short-term results are favorable for EVAR compared to open surgery, one of the major drawbacks to this shift is the need for fluoroscopy and contrast dyes to visualise endovascular devices. The contrast dyes used during these procedures can induce renal failure in patients with preexisting renal dysfunction. Meanwhile, the use of fluoroscopy exposes both patients and caregivers to harmful ionizing radiation. Because of the harmful effects of radiation, recent radiation protection guidelines strongly recommend as low as reasonably achievable (ALARA) principle.

In response to these challenges, Centerline Biomedical (Cleveland, Ohio, USA) has developed a proprietary electromagnetic tracking and positioning system called the Intra-Operative Positioning System (IOPS). This medical device provides surgeons with 3D visualization for increased surgical precision while reducing the use of contrast dye and radiation exposure for patients and healthcare professionals alike. IOPS provides 3D electromagnetic navigation of interventional devices as an adjunct to fluoroscopy. Image guidance is provided using 3D maps of the vasculature, generated from thin-slice contrast-enhanced preoperative computerised tomography angiography (CTA). At the start of the procedure, a self-adhesive sterile fiducial tracking pad is attached to the patient's lumbar region, and the angiography system is used to perform a non-contrast-enhanced cone-beam CT scan. The cone beam CT volume is then loaded onto the IOPS cart and manually aligned with the preoperative CT volume. This work can be performed in parallel with achieving vascular access, with minimal effects on the procedure time. During the intervention, the IOPS devices can be visualized with on-screen image guidance. The console is operated by a technician under a physician's instruction. The IOPS guidewires and catheters can be used together or combined with off-the-shelf 0.035-inch catheters and guidewires, as needed. This technology has been used by other centres for visceral and renal cannulation during complex aortic aneurysm procedures.

Previously there have been publications on the use of Fiber Optic Real Shape (FORS) Technology with both complex and standard endovascular aneurysm repair (EVAR) showing the potential benefit of this technology in procedural time and radiation reduction. However, the need for additional radiation-reducing navigation techniques is high, with the ultimate goal of performing endovascular procedures without radiation at all.

This study aims to describe the influence of IOPS technology on radiation exposure during cannulation of the contralateral limb (CL) during standard EVAR.

Study outcome and sample size:

Technical success of using IOPS technology during cannulation of CL Navigation time expressed through total procedural time, CL cannulation time, fluoroscopy time (overall and during CL cannulation) Radiation exposure parameters that were described in the latest European Society for Vascular Surgery (ESVS) radiation guidelines: cumulative air kerma (CAK), kerma area product (KAP), fluoroscopy time (FT) (4) To ensure sufficient statistical power to answer hypothetical questions, 80 subjects will be entered into the database. Navigation time and radiation exposure parameters are used to calculate the sample size. Assuming the difference in terms of both parameters, 30 patients are required in each arm to achieve a statistical power of 85% at p=0.05. With two arms (conventional and IOPS group), assuming a 20% rate of missing data, a total N of 80 patients is required.

Research Design:

This prospective study includes patients with standard AAA undergoing EVAR within instructions for use (IFU) treated from September 1st, 2024 until May 1st, 2025 at the Clinic for Vascular and Endovascular Surgery, University Clinical Centre of Serbia.

Procedures Involved:

This study will not impact the care that patients receive. Patient data will be compiled and analyzed to accomplish the proposed study objectives. Data collection will include demographic information, patient-related factors, comorbidities, diagnostic imaging information (describing the morphology of the aortoiliac segment), and periprocedural information related to the timing and radiation.

Data management:

After the data has been collected at a participating institution, the data will be transmitted to an online database which will be available only to a central analytic center located at the Clinic for Vascular and Endovascular Surgery/University Clinical Center of Serbia/Medical Faculty, University of Belgrade.

Risks to Subjects:

As this is a prospective observational study performing EVAR in standard AAA using new radiation protection technology for visualisation of wires and catheters in a newly equipped angio suite, there are minimal potential physical risks to subjects. There is also a minimal risk of breach of confidentiality that could occur when patient information is collected and analyzed for the proposed study. However, appropriate measures will be taken to minimize the risk as much as possible. All information recorded will be de-identified. This study will abide by all regulations related to protecting human subjects and protected health information.

Potential Benefits to Subjects:

There is a potential benefit to the subjects involved in the IOPS group. Hypothetically they will have lower procedural times and lower radiation doses during CL cannulation. Future patients treated with this technology might have reduced radiation and cannulation times. This will make it possible to perform more and more procedures with a minimal amount of radiation, or even without radiation at all.

Statistics and Data Analysis:

Continuous variables will be described using the median and interquartile range or mean and standard deviation. Categorical variables will be described using frequencies and percentages. Group comparisons will be performed by using the Student t-test or Mann-Whitney U test, as appropriate. Categorical data will be expressed as percentages and will be compared using the chi-square test or Fisher exact test. Differences will be considered statistically significant at p < 0.05. Analyses will be performed using SPSS software, version 28.0 (SPSS, Chicago, ILLINOIS, USA).

Conflict of Interest:

Since this is a physician-initiated trial, the investigators have no conflict of interest to report.

Funding Source:

There are no plans to apply for additional grants or additional funding. No funding is required for the completion of this study.

Publication Plan:

All research personnel included in this project will be eligible for authorship in any resulting abstracts and publications following the qualifications outlined by the International Committee of Medical Journal Editors. The order of authors will be determined prior to manuscript development and depend on each individual's contribution to the study.

Inclusion Criteria:

- All patients (over 18 years of age) with infrarenal AAA treated between 1st September 2024 and 1st May 2025 undergoing standard EVAR according to the IFU

Exclusion Criteria:

• Patients who are pregnant
• Patients who are under 40 years of age
• Patients who have symptomatic or ruptured AAA
• Patients with more advanced AAA: juxtarenal, pararenal, suprarenal, thoracic, thoracoabdominal AAA
• Non-atherosclerotic origin of disease: dissection, connective tissue disorders, mycotic AAA, posttraumatic AAA
• Patients who were treated in a conservative manner
• Patients undergoing open surgery
• Patients undergoing more advanced treatment options: fenestrated/branched EVAR, endostaplers, chimney EVAR, iliac branch devices, etc.

Patients with infrarenal AAA undergoing standard EVAR according to the IFUs of the manufacturer will be stratified into two groups:

1. IOPS group (used during CL cannulation)
2. Conventional group (as usual using a standardised approach for EVAR)

This will be decided among the study group, once study has been completed.