PD is widely known as one of the most challenging procedure in general surgery, whose complexity may be significantly increased by the concomitant presence of vascular anomalies of the periampullary region. Nevertheless, no unanimous data are currently present in the literature on the potential impact of vascular variants on perioperative outcomes, and scarce and contrasting evidences are currently present in particular on the potential role of an aberrant RHA.
According to our findings, the presence of an anomalous vascular pattern did not significantly influence the incidence rate of post-operative complications. In addition, no difference was evidenced between APV and MPV patients in terms of pathological findings, here including the rate of positive resection margins.
The potential correlation between an aberrant RHA and the onset of post-operative complications has been the focus of several studies. In particular, the accidental damage of aberrant vessels, as well as the alteration of local vascularization due to the excessive skeletonization of the aberrant arteries, have been proposed as the main predisposing features to post-operative complications, in particular BF. Indeed, as reported by Northover et al.,[17] the proximal extra-hepatic biliary tree is vascularized by the RHA for almost the 40% of the total, while the remaining blood flow comes from the retroduodenal, the retroportal and the gastroduodenal arteries. In this context, the presence of a RHA originating from the SMA and running along the posterior aspect of the retroportal lamina, that needs to be skeletonized in order to guarantee oncological radicality, may hypothetically increase the risk of bile duct (and subsequent hepatico-jejunostomy) ischemia, potentially leading to a higher rate of BF. This issue has already been enlightened by Traverso in 1989[5] and assessed by several authors in recent years. However, the majority of them did not evidence any statistical difference between MPV and APV patients. Indeed, Eshuis and Rammohan showed that, despite higher intra-operative technical difficulty, the presence of an rRHA or aRHA, did not affect perioperative outcomes, including BF incidence[18, 19]. More recently, Alexakis conducted a matched analysis only on patients who underwent surgery for benign diseases, reporting similar rates of complications[20]. Our findings further corroborate these evidences since no differences were detected between APV and MPV patients both in terms of postoperative complications and, in particular, BF incidence rate (p = 0.2 and p = 0.58 respectively).
Great concern has been also expressed about the potential role that an aberrant RHA may have on the oncological radicality, especially in terms of resection margins. For instance, an aRHA or rRHA generally arise from the SMA and run along the posterior aspect of the duodeno-cephalopancreatic block through the retroportal lamina. This last is widely recognized as the most frequent site of R1 and local tumor recurrence in case of infiltration or incomplete removal[21, 22]. In this scenario, the need of preservation of the anomalous artery, such as an aRHA and rHA, might hinder a proper oncological dissection, thus paving the way to a positive retropancreatic margin and to a dismal oncological result, increasing at the same time the risk of PPH due to the necessary skeletonization of the anomalous artery. Although the oncological role of vascular arterial resection is highly debated, some authors[23] advise a vascular resection of the aberrant artery when the tumor is closer than 10mm to the artery in order to achieve an R0 resection, eventually performing a vascular reconstruction through the interposition of the gastroduodenal stump[24, 25]. According to our findings, no difference has been evidenced between the MPV and APV cohorts in terms of resection margin positivity (here including the mesopancreas margin), in line with Turrini et al. that reported no difference in terms of margin status when the variant right hepatic artery was not directly infiltrated[26]. Moreover, no arterial vascular resections were needed intraoperatively and PPH rate was similar between the two study cohorts. These outcomes may find justification in the importance of performing such complex procedure in high-volume referral centers[27, 28]. Specifically, the preoperative assessment of tumor resectability and vascular anatomy, performed in a multidisciplinary and specialized setting, has permitted to adequately select patients for PD, excluding those with evidence of tumor involvement of major vessels, notably candidate to neoadjuvant treatment. Similarly, the surgical expertise developed over the years has permitted to achieve similar PPH rate between the MPV and APV populations (p = 0.6), with even comparable operative time detected in two study cohorts (p = 0.79) and no accidental vascular resection during surgery.
This study presents several limitations especially due to its retrospective study design as well as to the relatively small sample size of the study cohort. On the counterpart, to our knowledge, this is the first study in the literature on this topic based on a PSM-derived cohort that has significantly limited the potential selection biases, making the two populations homogenous for the majority of confounding factors. Moreover, our findings derive from a high-volume tertiary referral center for the surgical treatment of pancreatic diseases, giving an objective and real picture of clinical outcomes when PDs with APV are performed in specialized centers.
In conclusion, the present analysis has confirmed that the presence of anomalies of the RHA does not significantly modify the post-operative clinical course nor the quality of surgical dissection. It is, however, implicit the need to perform this more complex procedure in high-volume centers and in a multidisciplinary setting. Nevertheless, additional studies with larger series are necessary to further corroborate our results.