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 Basic Mechanisms in Mesenteric Ischemia

Anatomy

  • Normal arterial and venous anatomy of the mesenteric circulation.
  • Collateral circulation.
  • More frequently encountered anatomic variations.

Regulation of mesenteric blood flow

  • Intrinsic control of the mesenteric circulation (metabolic theory, myogenic theory).
  • Reactive and postprandial hyperemia.
  • Extrinsic control of the mesenteric circulation (neural mechanisms, hormonal mechanisms).

Intestinal ischemia

  • Histologic injury.
  • Biochemical – metabolic events.

Reperfusion injury

  • Formation of reactive oxygen species (redox reactions, enzyme-substrate reactions, activation/degranulation of inflammatory cells).
  • Mechanisms of reactive oxygen species cell and tissue injury.
  • Polymorphonuclear leukocytes in reperfusion injury.

V. New approaches to diagnosis and treatment of mesenteric ischemia/reperfusion.

  • 1. Recent laboratory efforts in quantifying the effects of mesenteric ischemia-reperfusion (ICAM-1, ELAM-1, alkaline phosphatase).
  • 2. New approaches to treatment of mesenteric ischemia/reperfusion (changes in the nature of the reperfusate, alterations in the adherence or activation of polymorphonuclear cells and the administration of pharmacologic scavengers of reactive oxygen species).

References

Rosenblum JD, Boyle CM, Schwartz LB. The mesenteric circulation. Anatomy and physiology. Surg Clin North Am 1997;77:289-306.

This article reviews the angiographic appearance of the major visceral arteries, the more common variants, their embryologic origins, and some of the most common sources of collateral flow. A brief review of the physiology of the mesenteric circulation is also provided, including a discussion of the intrinsic and extrinsic mechanisms of splanchnic blood flow control.

Matheson PJ, Wilson MA, Garrison RN. Regulation of intestinal blood flow. J Surg Res 2000;93:182-196.

This review summarizes the current understanding regarding the regulatory mechanisms of intestinal blood flow in fasted and fed conditions and during pathological stress. The role of absorbed nutrients, enteric nervous system effects and reflexes, gastrointestinal hormones and peptides and local nonmetabolic and metabolic vasoactive mediators is discussed. Alterations of intestinal blood flow in pathologic conditions, including septic shock, hemorrhagic shock, cardiogenic shock and portal hypertension are also described.

Patel A, Kaleya RN, Sammartano RJ. Pathophysiology of mesenteric ischemia. Surg Clin North Am 1992;72:31-41.

Intestinal ischemia can result from a host of pathophysiologic disturbances and, in turn, may produce a variety of adverse local and systemic consequences. Mechanisms of ischemic injury and the central role of vasoconstriction are discussed.

Haglund U, Bergqvist D. Intestinal ischemia - the basics. Langenbecks Arch Surg 1999;384:233-238.

In this review the physiology of the intestinal circulation is briefly outlined, followed by a discussion of nonocclusive intestinal ischemia and reperfusion injury. The clinical causes, diagnostic process and therapeutic options of intestinal ischemia are also outlined.

Kurland B, Brandt LJ, Delany HM. Diagnostic tests for intestinal ischemia. Surg Clin North Am 1992;72:85-105.

The various diagnostic tests for intestinal ischemia are presented in this study. These include serum biochemical markers, peritoneal fluid analysis, tonometry, radionuclide imaging, laparoscopy, and endoscopic techniques. Newer techniques, including radionuclide-labeled antibodies, tonometry, and reflectance spectrophotometry, are also discussed.

Posted June 2010