0071643192.pdf

MESENTERIC ISCHEMIA

Mesenteric ischemia can be divided into arterial and venous disease as well as
occlusive versus nonocclusive (see Table 11.16). Full-gut necrosis can occur as
fast as in 6 hours. This is a disease with a high rate of morbidity and mortality
(30–100%), so early identification and treatment are prudent. Acute mesenteric
ischemia is most commonly (>50%) due to occlusive embolism and involves
the superior mesenteric artery (SMA). Ischemic colitis is a nonocclusive process
involving the inferior mesenteric artery (IMA) secondary to low-flow states.

SYMPTOMS

■ Acute disease presents with abdominal pain out of proportionto clinical
exam. Pain is severe, colicky, and poorly localized.
■ History of “intestinal angina”
■ Chronic disease can present as pain after eating, weight loss, or change in
bowel pattern.

EXAM

■ Initially soft abdomen
■ Peritoneal signs once complete transmural infarct develops
■ Blood on rectal exam
■ Chronic mesenteric ischemia may present with an abdominal bruit.

DIFFERENTIAL

■ Diverticulitis, appendicitis, MI, IBD, perforated viscous, aortic dissection,
abdominal aortic aneurysm
ABDOMINAL AND GASTROINTESTINAL

EMERGENCIES

Consider acute mesenteric

ischemia in patients with

abdominal pain out of

proportion to exam or with a

persistently elevated lactate

without other underlying

causes.

Elderly patients often present

atypically with presentations

that mimic other diseases.

TABLE 11.16. Causes of Mesenteric Ischemia

Occlusive Disease

Embolism Atrial fibrillation, myxoma, valvular disease

Arterial thrombosis Atherosclerosis, low-flow state

Venous thrombosis Hypercoaguable state

Arterial disease AAA, AD, fibromuscular dysplasia, atherolsclerosis

Iatrogenic Drug-induced, eg, epinephrine, post-procedure

(dissection or embolism)

Trauma Penetrating or blunt

Nonocclusive disease

Shock Sepsis, cardiogenic, hypovolemic

Low-flow Myocardial infarction, arrhythmia, CHF

Drug-induced Vasoactive drugs, cocaine, digitalis