Visceral Ischemic Syndromes
Visceral ischemic syndromes can be categorized as either acute or chronic. Both of these conditions are most often associated with the presence of atherosclerotic lesions obstructing the visceral arteries which include the celiac trunk, superior mesenteric artery, and inferior mesenteric artery. However, other causes such as embolism, mesenteric venous thrombosis, or aneurysms may also be causative factors. Acute mesenteric ischemia often occurs in association with chronic pre-existing atherosclerotic lesions. Blood flow through the diseased artery may become so compromised that thrombosis occurs and the blood supply to the intestine is suddenly interrupted. This event is an immediate life threatening condition. Prompt diagnosis and surgical intervention may offer the only opportunity to salvage not only the patient's intestine but also their life. Early signs and symptoms of acute mesenteric ischemia characteristically involve severe diffuse abdominal pain. The severity of pain is often out of proportion to the physical findings on examination. The possibility of acute mesenteric artery embolism must also be kept in mind. In either of these circumstances, other physical findings such as chronic atrial fibrillation and markedly elevated white blood count or lactic acidosis must be viewed as indicators that acute mesenteric infarction is a possible diagnosis. Definitive diagnosis can be made with a promptly performed mesenteric arteriogram. Timely surgical intervention by embolectomy or bypass reconstruction of the obstructing lesions is usually necessary to avoid extensive intestinal necrosis or death related to severe metabolic derangements.
In contrast, chronic mesenteric ischemia is characteristically associated with abdominal pain after meals. The onset of pain is usually insidious and progressive. Eventually, this situation results in substantial weight loss and a marked alteration in dietary intake. Many different gastrointestinal studies may be performed before the suspicion of chronic mesenteric ischemia becomes evident. Typically, the patient will have complete obstruction of at least two of the three main mesenteric blood vessels. Once the syndrome is suspected, arteriography is usually diagnostic.
Treatment: Treatment may include surgery such as endarterectomy which removes the atherosclerotic obstructions from the orifices of the arteries or bypass reconstruction utilizing either autogenous vein or prosthetic grafts or minimally invasive interventions including angioplasty and stenting.
