Gastroepiploic Artery - Anatomy and Function

Introduction

The greater omentum and the stomach are supplied by the gastroepiploic artery (GEA). It comprises two arteries. Older publications also referred to the right gastroepiploic artery (RGEA) as the right gastro-omental artery, which is one of the distant vessels that branch from the gastroduodenal artery.

The vessel travels from right to left along the stomach's large curvature. It passes through layers of the larger omentum, producing omental and gastric branches, and joins with the left gastroepiploic artery. Likewise, the left gastroepiploic artery (LGEA) is referred to as the left gastro-omental artery.

What Is the Structure and Function of GEA?

The lower body of the stomach and the anterior and posterior antrum gets blood from the RGEA. The right greater omentum occasionally branches and supplies the last segments of the duodenum, receiving inferior branches from the RGEA. The LGEA feeds blood to the anterior and posterior bodies of the stomach when it reaches the stomach at or around the center of the greater curvature.

1. Embryology:

• Blood islands, also known as islets of Wolff, mark the beginning of the formation of blood vessels. The blood islands in front of the protocordal disk are the source of the intraembryonic blood vessels, which develop into a plexiform network that forms a horseshoe shape around the embryo's cephalic region.

• The dorsal aortas cephalically attach to the plexiform network and are formed simultaneously by two angioblastic cells arranged in a dorsal paramedian position. The ducts of higher caliber are formed as part of the continued growth of the vascular system.

• Both right and left primitive aortas are the largest of these; they are the source of the fetal arterial tree, which evolves concurrently with the cardiac tube.

• Finally, the anastomoses that arise between intra- and extra-embryonic vessels finish the circulatory system.

• The primitive aorta's anterior ventral segmental arteries, located between two layers of the dorsal mesogastrium, are the source of the gastrointestinal system's blood supply.

• The foregut artery originates from the eleventh segmental artery (celiac artery). This artery rotates and migrates caudally with the stomach during embryonic development, supplying blood to all foregut tissues.

• The hepatic and splenic arteries are both derived from the celiac artery.

• The gastroduodenal artery and the hepatic artery subsequently divide to form the RGEA.

• The LGEA then develops from the splenic artery. With the growth of the greater curvature of the stomach and lesser sac, the RGEA and LGEA, as well as other local structures, enlarge.

2. Blood Supply and Lymphatics:

• The gastroduodenal artery is the source of the RGEA, which typically arises posterior to the first section of the duodenum. Although its exact path varies, it frequently traces the gastroduodenal artery laterally down the pylorus before turning medially and passing between the larger omentum and the greater curvature of the stomach.

• The RGEA typically rests two inches below the stomach after turning medially, wedged between layers of the gastrocolic omentum on the anterior and posterior sides. The artery releases superior branches that supply the distal body of the stomach and the anterior and posterior gastric antrum. Additionally, the RGEA emits inferior branches that supply the larger omentum and, in certain cases, the last portions of the duodenum.

• Near the tail, the LGEA arises from the splenic artery or branches from the inferior splenic artery. The artery starts slightly to the gastrosplenic ligament and bends more sharply into the stomach at the anterior pole of the spleen. Then, it turns left to right, releasing posterior omental and superior gastric branches.

3. Nerves: The periarterial sympathetic nerve innervates the gastroepiploic artery, enabling the artery to contract and activate the smooth and endothelium muscle. If alpha2-adrenoceptors are triggered, the artery can contract slowly or quickly if stimulated by alpha1-Adrenoceptors. Nitric oxide synthesis affects whether arterial tone modulation is present. C-type natriuretic peptide affects vasodilation. The activating ion of certain channels, the C-type natriuretic peptide, reduces the arterial tone.

4. Muscles: Alpha-smooth-actin (SMA), which is found in smooth muscle cells, causes the vessel to constrict. Additional proteins, including collagen and elastin, were discovered that affect the vessel's movement. Gamma-smooth actin, another actin, is also present, although in lesser amounts.

What Are the Physiologic Variants of GEA?

• Numerous angiogram-based investigations have revealed a 43 to 65 percent anastomosis rate. It has been established that the RGEA has a wide range of origins.

• In cases when there is no development of the gastroduodenal artery, the RGEA may diverge from the superior mesenteric artery.

• Furthermore, according to anatomical investigations, the superior mesenteric artery and the celiac artery send equal-sized branches to the RGEA. The LGEA and the inferior splenic artery frequently form a branch that distally divides into two distinct arteries. It has been demonstrated that the omental branches of the LGEA and the middle colic artery form anastomoses.

1. Surgical considerations:

• As the right gastric arteries and RGEA provide most of the blood supply to the stomach, surgeons avoid causing iatrogenic injury that can jeopardize these vessels throughout the surgery.

• It is important to note that the stomach has a healthy collateral blood supply. Therefore, ischemia is less likely to occur when the stomach vasculature is damaged than bleeding.

• Due to a weakened GEA, gastric walls close to the anastomoses between the LGEA and RGEA on the anterior and posterior greater curvatures of the stomach frequently experience gastrointestinal ischemia.

• When the colonic splenic flexure is surgically mobilized, the LGEA can become susceptible.

• Due to its position posterior to the duodenum, the early RGEA is difficult to access surgically and is not as vulnerable during most procedures.

2. Clinical Significance:

• The RGEA and LGEA are useful landmarks when describing anatomy inside the abdomen.

• Both laparoscopic and open procedures typically make the distal arteries visible.

• In addition, the stomach and the omentum caudad can be found cephalad to each other.

• Traumatic injury that penetrates the skin can impair the LGEA and RGEA, leading to significant bleeding. Such damage would necessitate immediate surgery to halt bleeding.

• A visceral artery aneurysm is one of the rarest forms, and GEA aneurysms account for only 3.5 percent of all visceral artery aneurysms. Atherosclerotic disease is the most common cause. Since aneurysms are often asymptomatic, diagnosis is frequently delayed until they rupture. The guideline is to undertake an elective repair if a non-ruptured lesion is discovered by chance because the vessel carries a higher risk of complications and a high possibility of future rupture.

• The LGEA and RGEA provide a flow of blood to the stomach, which is helpful when a gastric tube needs to be made after an esophagectomy. While other arteries are ligated to mobilize the stomach, many surgeons conserve the RGEA for blood supply. The RGEA can provide enough blood to be the stomach reconstruction's primary source.

• The RGEA and its branches, according to one anatomical research measuring resins injected into the arteries of 30 cadavers, supplied 60 % of the gastric tube directly after esophagectomy. The LGEA and its anastomotic branches supplied another 20 % of the gastric tube.

• According to studies comparing the effects of different neurotransmitters on the RGEA and internal thoracic artery, both arteries constrict in response to Ergotamine, Phenylephrine, norepinephrine, and serotonin. However, in reaction to histamine, the two vessels respond differently and paradoxically, with the ITA contracting and the RGEA dilating. In addition, RGEA blood flow has risen following meals using a Doppler mini-probe. This physiological reaction is assumed to be brought on by the digestive tract's heightened need for blood flow by histamine following meals.

Other Complications:

LGEA could have morphological differences. One study described a relatively uncommon variant found through cadaver dissection. It may pass through the pancreatic parenchyma in its posterior-superficial portion, split into an omental branch, a duplicated LGEA, and another branch terminates in the left gastroepiploic artery's main trunk.

Conclusion

The gastroepiploic artery comprises the artery of the stomach and the greater omentum. It is also known as the right gastroepiploic artery (RGEA). Initially, the blood vessels originate from the islets of Wolffmark, and later splenic and hepatic arteries are formed, which further form the right and left gastroepiploic arteries. The peri-arterial sympathetic nerve supplies these arteries, and the smooth muscle present around it allows the vessels to constrict. Its clinical significance is to distinguish the anatomy inside the abdomen.