Commentary on: “clinical and haemodynamic evaluation of a novel physician modified inner branch iliac branch device for East Asians”

We read with interest the study by Wu et al. evaluating a physician modified inner branch iliac branch device (PM-IIBD) tailored to anatomic constraints in East Asian patients undergoing endovascular aneurysm repair.¹ The integration of computational fluid dynamics with prospective clinical follow up provides a structured framework for early device evaluation. However, several aspects merit further discussion.

Firstly, although favourable haemodynamic indices are reported at 12 months, the interpretation of computational fluid dynamics outputs requires contextual alignment with the post-endovascular aortic repair (EVAR) endograft environment rather than native vessel physiology. Within stent graft systems, flow is governed by graft lumen geometry and boundary conditions derived from inflow and outflow constraints.² Accordingly, vessel wall driven mechanobiology, such as intimal hyperplasia, should be interpreted cautiously, as the native arterial wall is largely excluded except at sealing zones. A more device centric interpretation focusing on intragraft flow stability and branch junction dynamics would enhance translational relevance.

Secondly, the observed increase in mean and maximal time averaged wall shear stress within the main stent and inner branch warrants nuanced interpretation. While elevated shear within grafted segments may reflect streamlined flow, focal high time averaged wall shear stress at branch interfaces may also indicate localised flow acceleration related to geometric transitions rather than uniform haemodynamic optimisation.³ Correlating these findings with duplex derived velocities or branch patency endpoints would strengthen clinical interpretability.

Thirdly, the reported slight reduction in external iliac artery velocity merits clarification in the context of distal outflow definition. In EVAR configurations, distal runoff is functionally determined by femoral outflow rather than isolated iliac segments, particularly when portions of the external and internal iliac arteries are incorporated within the endograft system.⁴ Explicit clarification of how “distal runoff” is defined within the modelling framework would improve physiological interpretation, especially in patients with concomitant peripheral artery disease. This distinction is clinically relevant because current European Society for Vascular Surgery guidelines recommend preservation of at least one internal iliac artery during EVAR whenever feasible.⁵

Fourthly, the biological interface of endografts differs from native vessels. True endothelialisation across the stent graft is not expected; instead, pannus formation and surface thrombotic interactions dominate, which introduce an alternative framework involving platelet activation and potential biofilm formation within graft material.⁶ Integrating this perspective may refine interpretation of shear related findings.

Finally, the physician modified nature of the device introduces procedural variability. Quantitative reporting of fenestration geometry, branch angulation, and deployment reproducibility would facilitate cross centre standardisation and support future transition toward off the shelf inner branch systems.⁷

Overall, Wu et al. provide encouraging early data supporting the feasibility of the PM-IIBD concept. Refining haemodynamic interpretation within the constraints of endograft physiology and clarifying modelling assumptions would further strengthen the translational validity of this work.

Declaration of Generative AI and AI Assisted Technologies in the Writing Process

During the preparation of this work the authors used Grammarly and ChatGPT in order to refine language, grammar, and style. After using this tool/service, the author(s) reviewed and edited the content as needed and take(s) full responsibility for the content of the publication.