Professor & Chairman Houston Methodist Hospital Houston, Texas
Objectives: Procedural time and radiation exposure for fenestrated endovascular aortic repair (FEVAR) are typically reported cumulatively. Our objective is to perform a stepwise analysis of FEVAR workflow, specifically to study the distribution of time and radiation spent on individual procedural steps.
Methods: Retrospective review of consecutive FEVAR cases done between May 2020 and September 2021 was performed. All FEVAR cases were performed in hybrid operating rooms (Artis Pheno VE10®, Siemens) using CT-fluoroscopy image fusion. Total procedure time was defined as the time from cone-beam CT imaging to closure of femoral arterial access. Time spent on individual pre-defined seven main procedural steps was noted by reviewing the operating room video recordings. Radiation exposure associated with procedures steps were analyzed after exporting the radiation data from DICOM structured dose reports using commercially available software (CAREAnalytics®, Siemens).
Results: Total radiation dose for all 10 FEVAR procedures performed during the study period was 1344 mGy (mean AK-air-kerma, range, 191-3850 mGy) and 24428 μGym² (mean DAP-Dose-area-product, range 1915 – 82770 μGym²) with a total procedural time of 223 minutes (range, 120 - 445).
Median radiation dose for renal cannulation with stenting (step#4) was 544 mGy (142-1645 mGy, AK) and 6772 μGym² (814-1718 μGym², DAP), that accounted for 56% of total dose (range, 21 – 74%). Median time for renal cannulation and stenting was 50.7 minutes (range,25-87) that accounted for 25% of total procedural time (range, 15-42%).
Median radiation dose for distal EVAR stent deployment (step#5) was 308 mGy (21-836 mGy, AK) and 3705 μGym² (251-2885 μGym², DAP), that accounted for 13% of total dose (range, 9-66%). Median time for distal EVAR deployment (including gate cannulation) step was 25.9 minutes (range,16-88), that accounted for 14% of total procedural time (range, 3-48%).
Figures 1 and 2 illustrate the distribution of radiation dose and time spent on individual procedural steps for all 10 FEVAR cases .
Conclusions: Our stepwise analysis showed that during FEVAR cases, the proportion of time and radiation spent on renal artery cannulation with stenting was highest followed by distal EVAR graft deployment. Such stepwise approach to study the surgical workflow, allows for an in-depth understanding of which stages of the procedure contribute to higher radiation exposure and procedural time. Although patient-specific anatomical factors define procedural complexity, such workflow analysis methods may help in identifying and addressing procedural challenges with ‘relevant’ technological, logistical, or educational solutions.
