Iatrogenic embolization of the superior mesenteric artery: arteriographic observations and clinical implications.

Following sudden occlusion of the superior mesenteric artery, there is a characteristic and predictable pattern of blood flow through the instantaneously activated collateral channels. On the left, the first patent jejunal or ileal branch utilizes the central tier of the mesenteric arcades to revascularize the distal trunk of the occluded superior mesenteric artery. On the right, the anastomotic connection between the middle colic, right colic, and ileocolic arteries provides an efficient collateral pathway. These two collateral channels supplement each other and the distal trunk of the occluded superior mesenteric artery is usually rapidly reconstituted. Superior mesenteric artery embolization is frequently an asymptomatic event. There appears to be a variable tolerance of cardiac and non-cardiac patients to the effect of superior mesenteric embolization. Non-cardiac patients may tolerate embolization of the superior mesenteric artery quite well. Cardiac patients frequently respond with an ischemic crisis. The site of embolization is another determining factor. An embolus below the origin of the middle colic artery provides an incomparably more favorable hemodynamic situation than an embolus proximal to the origin of this vessel. The excellent tolerance of our group of patients to superior mesenteric embolization appears to be closely related to these two main factors.