The isolated left gastric artery: A shape-shifting pitfall for neuroangiographers

Safe and efficient angiography requires a sound knowledge of the relevant vascular anatomy. A unique feature of spinal angiography is that it necessitates, besides a robust understanding of spinal vessels, familiarity with the vascularization of a wide range of neighboring structures in the cervical, thoracic, abdominal, and pelvic regions.

Direct origin of the left gastric artery (LGA) from the aorta—or isolated LGA—is a well-described anatomical variant that is unlikely to escape the attention of body angiographers, notably because LGAs are involved in most cases of gastric hemorrhage. ¹ However, we have seen an isolated LGA labeled as an intersegmental artery (ISA) more than once while reviewing spinal angiograms performed by neuroangiographers. This error has significant potential consequences. Misidentifying an LGA as an ISA leads to incomplete spinal angiography since at least one ISA remains unexplored, an oversight that may conceal an important radiculomedullary contribution or a spinal vascular malformation. Mistaking an LGA for a pathological vessel during embolotherapy (e.g., preoperative embolization of a vertebral tumor) is also concerning, because unwarranted occlusion of the vessel can lead to significant complications (e.g., gastric necrosis). ²

As an additional challenge for neuroangiographers unfamiliar with their morphology, the angiographic appearance of visceral branches can change, sometimes rapidly and markedly, with the position and inflation of the organs they supply. This is notably the case for the LGA, one of the most mobile celiac branches. ³ To illustrate this, we present angiographic images of a 28-year-old patient referred to our center for progressive myelopathy with unremarkable CSF analysis. An outside spinal angiogram suggested a low-flow perimedullary arteriovenous fistula of the conus medullaris, but second readings of that study remained inconclusive, leading to repeat angiography at our institution. The first study mislabeled an LGA as a left T11 ISA (the latter remaining uninvestigated) (Figure 1). The second study also documented the variant, but its appearance was different owing to a lesser degree of gastric inflation (Figure 2). Sundgren described this phenomenon in his 1970 monograph on LGA angiography, in which he advised using deliberate stomach distention to spread LGA branches and optimize their analysis. ⁴

Figure 1.

28-year-old patient with progressive myelopathy, first angiogram. (A) DSA, isolated left gastric injection (LGA), posteroanterior projection, arterial phase. A large arrow indicates the trunk of the LGA. Its anterior and posterior branches are spread through gastric distention. An esophageal branch has a typical ascending course (black arrowhead), and the left inferior phrenic artery (gray arrowhead) is partially opacified via small anastomotic rami (i.e., cardioesophageal branches). ⁵ The posterior branch of the LGA is connected to the right gastric artery, which opacifies in a retrograde manner (white arrowhead). (B) Non-subtracted posteroanterior view. This image shows marked gastric distension.

Figure 2.

28-year-old patient with progressive myelopathy, second angiogram. (A) DSA, isolated left gastric injection (LGA), posteroanterior projection, early arterial phase. The LGA (large arrow) has a typical craniolateral course. Its anterior and posterior branches project over each other owing to a lesser degree of gastric distension. Note the presence of several esophageal branches (black arrowheads). The inferior phrenic artery is visible (gray arrowhead). The right gastric artery (white arrowhead) begins to opacify via its distal connections with the posterior branch of the LGA. This image presents a more characteristic angiographic appearance of the LGA. (B) DSA, isolated LGA, posteroanterior projection, late arterial phase. The mucosal blush is more pronounced and the right gastric artery is better delineated (arrowheads). Anastomoses with the right gastric artery represent an important diagnostic clue. (C) DSA, isolated LGA, posteroanterior projection, venous phase. The venous phase shows the left gastric (or coronary) vein (large arrow), which drains into the portal vein (small arrow). Observing the portal vein system is a critical angiographic clue. (D) Non-subtracted posteroanterior view. The stomach is less distended than during the initial study (compare with Figure 1(B)).

The LGA is normally a component of the celiac trunk. A direct takeoff from the aorta, mentioned by von Haller in 1745 and illustrated by Quain in 1844 (Figure 3), represents the LGA's most common origin variant, with reported prevalences ranging from 0.5% to 15% in cadaveric studies ³ and 1.8% and 5.4% in angiographic studies.^4,6 It was present in 328 of the 9829 cases (3.34%) surveyed by Panagouli et al. ⁷ In our patient, the celiac trunk was otherwise unremarkable (i.e., branching off the common hepatic and splenic arteries, i.e., a hepatolienal trunk). In the recent classification proposed by Panagouli et al., ⁷ our variant corresponds to Type II, form 1 (i.e., Type II of the former classification proposed by Lipshutz, Adachi, or Morita) (Figure 4).

Figure 3.

Figure reproduced from Quain's The anatomy of the arteries of the human body, with its applications to pathology and operative surgery: in lithographic drawings with practical commentaries (1844), with the first depiction of an isolated left gastric artery known to the author. Plate 57 illustrates variants in the branching pattern of the abdominal aorta of a 22-year-old woman. It shows separate aortic origins of the left gastric, splenic, and hepatic arteries and variant renal artery origins from the aorta, median sacral artery, and common iliac artery. Relevant original legends: 1—aorta, 2—phrenic arteries, 3—coronary of the stomach [left gastric artery], 4—splenic artery, 5—hepatic artery, 6—renal arteries.

Figure 4.

Figure reproduced from Adachi's Das Arteriensystem der Japaner. Band II. (1928), ⁸ depicting an isolated left gastric artery (LGA) and a hepatolienal trunk, a situation similar to our patient. In Adachi's case (a 72-year-old man), a right accessory hepatic artery originated from the superior mesenteric artery. Note the thin anastomosis between the posterior branch of the LGA and right gastric artery (a branch of the hepatic artery) along the lesser curvature of the stomach.

In adults, aberrant LGAs originate from the ventral aspect of the aorta at the T12-L1 vertebral level,^3,9 but may be slightly higher (e.g., T11 in our first case). After a sharp proximal upward turn, the LGA provides one or more ascending branches to the abdominal segment of the esophagus and a hepatic ramus before dividing into anterior and posterior branches destined for the corresponding gastric walls. ¹⁰ In some instances, the anomalous branch only supplies part of the expected LGA territory (i.e., accessory LGA).

Naidich and colleagues noted, in their series of nine cases, a constant association between LGAs of aortic origin and an inferior phrenic artery. Although not constant in our experience, the presence of ipsilateral, contralateral, or bilateral phrenic branches remains common and represents an added confounding factor during spinal angiography (Figures 5 and 6). Angiographic features that help identify an LGA include opacification of the gastric mucosa (with moving contours matching the gastric bubble), anastomoses with the right gastric artery, and venous drainage into the portal system (Figures 2 and 6).

Figure 5.

Isolated left gastric artery (LGA) with unilateral inferior phrenic branches. (A) DSA, LGA trunk injection, posteroanterior projection, early arterial phase, documenting a duplication of the LGA (small and large arrowheads). (B) DSA, LGA trunk injection, posteroanterior projection, late arterial phase. The LGA trunk provides the right inferior phrenic artery (white arrow) and branches for the right adrenal gland (black arrow).

Figure 6.

Accessory isolated left gastric artery (LGA) with bilateral inferior phrenic branches. (A) DSA, DSA, accessory LGA injection, posteroanterior projection, early arterial phase. The accessory LGA (black arrowheads) is associated with bilateral inferior phrenic arteries (white arrowheads). (B) DSA, accessory LGA injection, posteroanterior projection, late arterial phase. Note the limited gastric blush marking the accessory nature of the LGA and the changing mucosal opacification that matches the gastric contour. The latter is an important clue regarding the identity of the injected vessel.

In conclusion, spinal angiographers must recognize nuances in the angiographic appearance of visceral branches linked to physiological variations in organ shape and position (e.g., breathing pattern and distention). These vessels may mimic an abnormal ISA. For example, if a branch seems to depart from its expected morphology, calling upon a colleague with visceral angiography expertise or consulting a classic angiography textbook can limit the risk of a diagnostic error or therapeutic mishap.