Intestinal Ischemia

Acute Mesenteric Ischemia

Definition and causes (NEJM 2016;374:959)

  • Reduced or absent blood flow to small intestine, typically caused by arterial (ie, SMA or its branches) occlusion or transient hypoperfusion or less often by venous occlusion
  • Arterial embolism (~40–50%): embolic occlusion to SMA (has narrow take-off angle), often in setting of AF, valvular disease incl. endocarditis, atherosclerotic plaque in aorta
  • SMA thrombosis (~20–30%): typically due to atherosclerosis at origin of SMA; other risk factors incl. vascular injury from abd trauma, infxn, or mesenteric dissections/aneurysms
  • Nonocclusive mesenteric ischemia (~10%): transient intestinal hypoperfusion athero, sepsis, drugs that ↓ gut perfusion (pressors, cocaine, amphetamines)