Aortic arch surgery is probably one of the clearest examples of how technological progress has transformed surgical practice, allowing intraoperative challenges to be addressed through increasingly sophisticated solutions. The introduction of the frozen elephant trunk (FET) technique radically changed this paradigm by enabling simultaneous treatment of the aortic arch and proximal descending thoracic aorta, while also creating a stable platform for subsequent endovascular interventions when required. Today, FET has become a fundamental tool in the management of complex acute and chronic aortic dissection, and its use continues to expand as specialised teams gain experience.

However, the progressive technical refinement of FET has highlighted a factor that often remains in the background: aortic arch surgery depends not only on the disease being treated, but also on the anatomy in which the procedure must be performed. Two patients with type A dissection may have virtually identical lesions yet require specific and substantially different technical modifications simply because their aortic arch configurations differ. Although this may appear self-evident to any experienced surgeon, it has rarely been systematically examined in the scientific literature.

This is precisely the main point of interest in the study by Leone et al., who analysed the influence of four anatomical arch variants—bovine trunk, an independently originating vertebral artery or four-vessel arch, aberrant right subclavian artery, and gothic arch—on total arch replacement using FET in patients with aortic dissection. Rather than merely comparing outcomes between patients with normal anatomy and those with congenital variants, the authors attempted to answer a much more practical question: do these anatomical configurations require modification of the surgical technique, and do they genuinely affect clinical outcomes?

The study reports the experience of one of Europe’s highest-volume aortic surgery groups, the Bologna team led by Davide Pacini. Over a 17-year period, they performed 401 FET procedures, selecting 285 patients treated for acute, chronic, or residual dissection. Of these, 69 had an aortic arch anomaly, representing almost 25% of the cohort. This proportion is considerably higher than the prevalence reported in the general population and, in itself, again raises the possibility of an association between certain anatomical variants and thoracic aortic disease. Although this relationship had previously been suggested, a cohort of this size provides a level of evidence that is unusual in this field.

One of the most notable findings is that the study challenges an intuitive assumption. Despite the greater technical complexity associated with these anatomical variants, in-hospital mortality, neurological complications, and long-term survival were comparable to those observed in patients with conventional arch anatomy. In other words, complex anatomy does not necessarily translate into a worse prognosis when surgical planning is appropriate and the procedure is performed at an experienced centre. This message has considerable educational value because it reminds us that technical difficulty should not be equated with an inevitably poorer clinical outcome. Team experience and the ability to adapt the operative strategy remain far more influential than the anatomical variant itself.

Nevertheless, reducing the study’s message to this conclusion would oversimplify its contribution. Its most interesting finding becomes apparent during follow-up. Patients with anatomical variants, particularly those undergoing surgery for chronic dissection, required significantly more secondary endovascular procedures with TEVAR. This observation changes the way in which aortic arch surgery should be assessed. The success of FET can no longer be measured exclusively by immediate survival or the absence of perioperative complications. It must also be evaluated according to its ability to promote stable remodelling of the entire thoracic aorta and minimise the need for future interventions.

Against this background, one of the article’s most thought-provoking concepts emerges: the distinction between anatomy and geometry. Surgeons have traditionally focused closely on variants of the supra-aortic vessels because they affect vascular reconstruction. However, this study suggests that the central problem may lie less in the branching pattern itself than in the three-dimensional geometry of the arch. FET is a hybrid graft containing a self-expanding stent graft whose behaviour is directly influenced by the angle of curvature, the length of the sealing or landing zone—when one is available—and the spatial relationship between the ascending and descending aorta.

This is particularly evident in patients with a gothic arch. Whereas a bovine trunk or independently originating vertebral artery primarily requires modification of supra-aortic vessel reconstruction, a gothic arch alters the interaction between the stent graft and the aortic wall itself. The authors reported a higher incidence of stent-graft kinking, functional pseudocoarctation, and the need for early TEVAR extension during the index hospital stay. This is not simply an intraoperative technical difficulty, but a direct consequence of implanting a relatively rigid device within an anatomy characterised by extremely acute curvature. The image accompanying the article is particularly illustrative.

This observation deserves broader consideration because it probably reflects one of the most important conceptual changes currently taking place in aortic surgery. For years, preoperative planning focused on determining aortic diameter, the location of the intimal tear, and the length of the segment requiring replacement. We now know that these parameters are insufficient. Modern planning requires an understanding of how the stent graft will actually deploy within a complex three-dimensional structure. Diameter is no longer the only relevant variable; arch curvature, angulation, spatial torsion, and blood-flow orientation must also be considered. This transition resembles the evolution already seen in structural cardiology, where three-dimensional reconstruction and patient-specific modelling have moved from research tools to routine components of procedural planning.

This may be where the study by Leone and colleagues makes its most important contribution. Beyond presenting a well-documented clinical series, it obliges surgeons to abandon the concept that a single technique is appropriate for every patient. FET is no longer simply a standardised procedure, but an operation whose execution must be tailored to individual anatomical characteristics. The central message of the article can therefore be summarised in one sentence: when anatomy changes, technique must change with it. This principle extends well beyond the four anatomical variants studied and points towards increasingly personalised aortic arch surgery, in which understanding aortic biomechanics will become as important as mastering the surgical technique itself.

COMMENTARY:

In addition to the lessons outlined above, the study itself highlights several limitations that should be carefully considered before its conclusions are extrapolated to clinical practice. The first arises from the definition of the study group. The authors combine four entities with profoundly different anatomical, embryological, and surgical implications under the term “arch anomalies.” Personally, I would describe most of them as normal anatomical variants rather than true anomalies. From a methodological perspective, this grouping increases the sample size, but from a surgical standpoint it introduces substantial heterogeneity. It is unreasonable to assume that a bovine trunk, an independently originating vertebral artery, an aberrant subclavian artery, and a gothic arch exert the same influence on the procedure or on subsequent clinical evolution. In reality, they represent entirely different problems that share only their departure from conventional anatomy.

The bovine trunk is probably the clearest example. Although some epidemiological studies have associated it with a higher incidence of aortic dissection, it rarely represents a major technical challenge during total arch replacement. Selective cerebral perfusion may even be simplified, and vascular reconstruction merely requires adaptation to reimplantation of a common trunk rather than two separate vessels. Alternatively, the individual vessels may be reimplanted independently, disregarding their shared anatomical origin. In experienced hands, it can hardly be considered a factor capable of significantly altering the overall outcome of FET.

A similar principle applies to an independently originating vertebral artery. Its main implication is the need to identify it during preoperative planning and determine how it should be reimplanted to preserve vertebrobasilar perfusion, a strategy that remains advisable even in the presence of codominance or right-sided dominance. The authors demonstrated that this vessel can be systematically reconstructed onto the branch intended for the left carotid artery without increasing neurological complications. This confirms that the principal challenge is not the technical reconstruction itself, but rather recognising the variant beforehand and avoiding inadvertent injury.

The situation changes substantially when an aberrant right subclavian artery is considered. This is a genuine anomaly of aortic arch development and one that can materially alter the operative strategy. Its distal origin requires exclusion of the ostium by the stent graft, followed by reconstruction of the vessel with a separate graft, either by creating a neo-brachiocephalic trunk or by reimplanting it onto a lateral branch of the prosthesis. This reconstruction is not performed solely to restore anatomical continuity; it is also intended to prevent retrograde perfusion, endoleaks, and future endovascular complications.

Even this anomaly, however, is overshadowed by the true protagonist of the study: the gothic arch. It is striking that most of the mechanical complications described by the authors occurred in this subgroup. This is unlikely to be coincidental. The gothic arch does not merely alter the arrangement of the supra-aortic vessels; it modifies the entire geometry within which the stent graft must expand. The immediate consequence is an increased risk of stent kinking, deformation of the hybrid segment, and impaired distal flow. In some patients, these complications required immediate TEVAR extension to restore an adequate lumen. Rather than simply representing a vascular anomaly, the gothic arch constitutes an engineering problem applied to cardiovascular surgery.

Perhaps the most provocative aspect of the article emerges when considering how this complication might be prevented. Over the past decade, most specialised centres have progressively moved the distal anastomosis from Zone 3 to Zone 2. The advantages are clear: shorter circulatory arrest times, improved surgical exposure, reduced risk of recurrent laryngeal nerve injury, and easier reconstruction of the left subclavian artery. This change has become almost a new standard in aortic arch surgery.

However, Leone et al. introduce an extremely important qualification. In patients with a gothic arch, a Zone 2 anastomosis may itself contribute to the problem. By shortening the distance between the distal suture line and the point of maximal arch curvature, the stent graft is forced to adopt a very acute angle immediately after deployment. This increases the risk of kinking, pseudocoarctation, and even visceral malperfusion. The authors therefore suggest considering a more distal Zone 3 anastomosis, which may provide a smoother transition towards the descending aorta. It is paradoxical that a widely accepted trend in arch surgery may require exceptions precisely in patients with the most complex anatomy.

This reasoning extends beyond the specific example of the gothic arch and raises a broader question. For years, surgeons have debated which technique is best for aortic arch replacement. Perhaps the more appropriate question is whether a universal technique truly exists. The answer suggested by this study is no. Contemporary aortic surgery is moving towards individualised procedures in which the distal anastomotic zone, stent-graft length, stent diameter, and even the strategy for supra-aortic vessel reconstruction should be adapted to each patient’s anatomy. The era of uniform solutions appears to be approaching its end.

These findings should nevertheless be interpreted cautiously. The study remains retrospective, single-centre, and based on the experience of a highly specialised unit. The 69 patients with arch variants were also distributed among four different entities, some represented by only 14 cases. The statistical power required to analyse each variant independently was therefore inevitably limited. Indeed, many of the conclusions arise more from clinical observation than from robust statistical differences. This does not diminish the value of the study, but it does mean that its findings should be regarded as hypothesis-generating rather than definitive evidence.

There is another limitation acknowledged by the authors that deserves particular attention. The study examines anatomy but provides only limited quantification of geometry. We know that the gothic arch increases the risk of complications, but we do not know which specific parameter is decisive. Is it the angle between the ascending and descending aorta? The arch height-to-width ratio? The effective landing-zone length? The spatial torsion of the distal segment? Without answering these questions, it is difficult to establish objective criteria for modifying the surgical strategy before entering the operating room. The future will probably involve the integration of advanced three-dimensional reconstructions, computational fluid dynamics, and even virtual simulations of stent-graft deployment before surgery. Personalised planning in aortic arch surgery is still in its early stages.

REFERENCE:

Leone A, Snaidero S, Di Marco L, Nocera C, Pacini D. Total Aortic Arch Replacement With the Frozen Elephant Trunk Technique: Influence of Aortic Arch Anomalies. Interdiscip Cardiovasc Thorac Surg. 2026 May 5;41(5):ivag100. doi: 10.1093/icvts/ivag100.