Acute mesenteric ischemia pathophysiology
Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1]; Associate Editor(s)-in-Chief: Rim Halaby
Overview
Pathophysiology
- The main mechanism underlying mesenteric ischemia is decreased blood flow to the small intestine. The decrease blood flow can be caused by:
- Occlusion
- Systemic hypoperfusion
- Spasm in the mesentery
- When blood flow to the mesentery decreases, collaterals try to compensate. However, following prolonged decrease in blood flow, vasoconstriction of the mesenteric vessels occurs leading to decrease blood flow in the collaterals, which were initially the main protective mechanism against ischemia.[1]
- It is worth mentioning that mesenteric vessel vasoconstriction can persist after the blood flow is restored which explains the use of vasodilator in the management of acute mesenteric ischemia.[1]
- Ischemia associated injury to the mesentery is either reperfusion injury when the ischemia occurs for a brief period or hypoxic injury when the ischemia occurs for a prolonged time.[1][2]
Mesenteric Arterial Occlusion
- Decrease blood flow in arterial occlusion occurs when the vessel, mainly superior mesenteric vessel, is blocked by an embolism that has originated from the left heart or from a thrombus that has formed secondary to atherosclerosis, trauma or infection.[1][3] (?)
Mesenteric Venous Occlusion
- Decrease blood flow to the mesentery in venous occlusion occurs with a sequence of events different from that of arterial occlusion. In hypercoagulable states, whether inherited or acquired, a blood clot is formed in the venous mesenteric vaculature. When the venous blood clot is formed, the resistance in the venous blood flow of the mesentery increases with subsequent increase in the fluid movement across the blood vessels. The result is bowel edema and systemic hypotension that leads to systemic hypoperfusion to the different organs, including the mesentery.[4]
Non Occlusive Mesenteric Ischemia
- Non occlusive mesenteric ischemia occurs when the blood flow to the mesentery decreases secondary to systemic hypoperfusion complicated by secondary mesenteric vasospasm. Non occlusive acute mesenteric ischemia occurs mainly in elderly with multiple cardiovascular risks and cardiovascular comorbidities in the setting of hypotension secondary to medication use, sepsis, myocardial infarction, congestive heart failre, kidney or liver failure. When hypotension occurs, the blood flow to the mesentery decreases and then it is complicated by further constriction of the mesenteric vasculature.[5]
- Cocaine can be a cuase of non occlusive acute mesenteric ischemia.[6]
References
- ↑ 1.0 1.1 1.2 1.3 Reinus JF, Brandt LJ, Boley SJ (1990). "Ischemic diseases of the bowel". Gastroenterol Clin North Am. 19 (2): 319–43. PMID 2194948.
- ↑ Lapchak PH, Kannan L, Ioannou A, Rani P, Karian P, Dalle Lucca JJ; et al. (2012). "Platelets orchestrate remote tissue damage after mesenteric ischemia-reperfusion". Am J Physiol Gastrointest Liver Physiol. 302 (8): G888–97. doi:10.1152/ajpgi.00499.2011. PMID 22301111.
- ↑ Rosenblum JD, Boyle CM, Schwartz LB (1997). "The mesenteric circulation. Anatomy and physiology". Surg Clin North Am. 77 (2): 289–306. PMID 9146713.
- ↑ McKinsey JF, Gewertz BL (1997). "Acute mesenteric ischemia". Surg Clin North Am. 77 (2): 307–18. PMID 9146714.
- ↑ Trompeter M, Brazda T, Remy CT, Vestring T, Reimer P (2002). "Non-occlusive mesenteric ischemia: etiology, diagnosis, and interventional therapy". Eur Radiol. 12 (5): 1179–87. doi:10.1007/s00330-001-1220-2. PMID 11976865.
- ↑ Sudhakar CB, Al-Hakeem M, MacArthur JD, Sumpio BE (1997). "Mesenteric ischemia secondary to cocaine abuse: case reports and literature review". Am J Gastroenterol. 92 (6): 1053–4. PMID 9177533.