Is It the Arc of Riolan or Meandering Mesenteric Artery?

To the Editors:

We have read the article by Donas et al ¹ with great interest. In their article, the inferior mesenteric artery (IMA) chimney endovascular technique can be considered in endovascular aneurysm repair cases with coexistent bilateral internal iliac artery occlusion to minimize the risk for bowel ischemia. They mentioned the major collateral pathways between the IMA and superior mesenteric artery (SMA), such as the arc of Riolan, the marginal artery of Drummond, and the meandering artery. However, confusion still persists about the correct descriptive terminology.

In general, the arc of Riolan or meandering mesenteric artery refers to a connection between the SMA and IMA (Figure 1).^2,3 Both vascular and gastrointestinal surgeons are aware of this collateral mesenteric pathway because inadvertent ligation of this anastomosis may have disastrous consequences during operative procedures. However, there is no consensus on which anatomical structure is represented by this eponym, and there are numerous synonyms, including the arch of Riolan, meandering mesenteric artery, central anastomotic artery of the colon, mesomesenteric artery, middle left colic collateral, intermesenteric artery or arcade, anastomosis (magna) of Riolan, meandering artery of Riolan, great colic artery of Riolan, arch of Treves, artery of Moskovitch, artery of Gonzalez, anastomosis maxima of Haller, and arcus magnus mesentericus.^2,3 It is differentiated from the marginal artery of Drummond in that the marginal artery is never tortuous and runs along the descending colon. Some authors consider that the use of the vague historic term “arc of Riolan” should be discarded for the more precise term meandering mesenteric artery. ² Others propose that the terms arc of Riolan and meandering mesenteric artery should be abolished because these terms do not reflect a distinct anatomical entity but represent an angiographically hypertrophied mesenteric artery and ascending branch of the left colic artery. ³ Further studies are needed to establish a standard descriptive terminology.

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Figure 1.

(A) Three-dimensional volume rendering images show severe stenosis of the celiac artery (CA, arrow), complete occlusion of the proximal superior mesenteric artery (SMA, arrow), and (B) an enlarged, tortuous collateral artery (small arrows) between the SMA and the inferior mesenteric artery (IMA). (C, D) Serial angiographic images show the huge, tortuous collateral artery that connects the proximal segment of the middle colic artery with the proximal branch of the left colic artery. Retrograde perfusion of the SMA and CA is readily recognized.