Chapter 31

### INTRODUCTION

The mesenteric arterial bed receives 10% to 35% of total cardiac output. Diseases of this extensive arterial bed can be a cause of significant mortality and morbidity. Ischemia of the mesenteric vasculature is caused by a reduction in the blood flow either from a systemic low flow state or from local impairment of the flow. Sudden onset of intestinal hypoperfusion from occlusive or nonocclusive obstruction of arterial or venous blood flow causes acute mesenteric ischemia. Chronic mesenteric ischemia is the result of episodic or constant intestinal hypoperfusion usually among patients with systemic atherosclerosis.

### ANATOMY

Mesenteric circulation has numerous variations in its blood supply to the visceral organs. Delineation and understanding of these various patterns of mesenteric circulation is important. Fortunately, with the advent of current imaging technology and digital angiography, it is now quite possible to accurately study the major vessels, pathologies, and aberrations of these vessels as well their branches, and the collaterals in every patient.

#### Embryology

The mesenteric vessels arise from the primitive ventral segmental arteries. All but three of these segmental arteries regress as development proceeds.1 The 10th, 13th, and 21st or 22nd artery give rise to the celiac, superior mesenteric, and inferior mesenteric artery (IMA) to supply the foregut, midgut, and the hindgut, respectively. Figure 31.1 shows the embryologic origin of mesenteric arteries.

###### FIGURE 31-1.

Embryologic origin of the visceral arteries. (A) The celiac trunk and the superior mesenteric artery arise from the 10th and 13th segmental arteries, respectively. (B) The arc of Buhler residual communications between the 10th and 13th segmental arteries.

Reproduced, with permission, from Rosenblum GD, Boyle CM, Schwartz LB. The mesenteric circulation. Anatomy and physiology. Surg Clin North Am. 1997;77:289-307.

#### Arterial Supply of the Intestines

Arterial supply of the mesenteric bed is characterized by a unique, well-developed network of collateral circulation. Presence of this collateral network is protective to a great extent against transient perturbation in the vascular supply of the intestines. Ischemia can develop even in the background of this rich collateral network if the insult persists for a prolonged period or if the insult affects a large area of vasculature.2,3

The blood supply predominantly occurs through three major branches of the abdominal aorta. Figure 31.2 shows the splanchnic arteries and the collateral circulation.

###### FIGURE 31-2.

Collateral circulation of the splanchnic circulation. (A) The marginal artery of Drummond and the arc of Riolan, which form anastomotic communications between the SMA and IMA. (B) Collaterals between the celiac and superior mesenteric artery via pancreaticoduodenal arteries.

Reproduced, with permission, from Rosenblum GD, Boyle CM, Schwartz LB. The mesenteric circulation: Anatomy and physiology. Surg Clin North Am 1997;77:289-307.

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