Medication Summary
Drug types used in the treatment of acute mesenteric ischemia (AMI) include vasodilators, thrombolytics, anticoagulants, antibiotics, and analgesics. Therapeutic drugs (except for analgesics and prophylactic antibiotics) should be withheld until the type of AMI present has been determined by means of computed tomography (CT) or angiography.
Vasodilators
Class Summary
Vasodilators dilate the mesenteric arterial system, thereby reversing reactive arterial vasospasms in AMI.
Papaverine
Papaverine is a benzylisoquinoline derivative that exerts a direct nonspecific relaxant effect on vascular, cardiac, and other smooth muscle. In the absence of peritoneal signs, it is the drug of choice for AMI of arterial origin if angiography indicates good distal perfusion. Papaverine is advocated for treatment of the widespread vasoconstriction that follows therapy for superior mesenteric artery (SMA) emboli by other modalities.
Thrombolytics
Class Summary
Thrombolytics are angiographically infused to lyse thrombi. They are used in selected patients with embolic AMI.
Alteplase, tissue plasminogen activator (Activase)
Alteplase is a synthetic tissue plasminogen activator (tPA) used to manage acute myocardial infarction (MI), ischemic stroke, and pulmonary embolism. Its use in AMI is controversial and potentially dangerous. Alteplase may be indicated in patients with acute mesenteric arterial embolism (AMAE; ie, embolic AMI) if no signs of peritonitis are present. The safety and efficacy of concomitant administration with aspirin and heparin during the first 24 hours after onset of symptoms have not been investigated.
Reteplase (Retavase)
Reteplase is a recombinant tPA that forms plasmin after facilitating cleavage of endogenous plasminogen. In clinical trials with acute MI, reteplase has been shown to be comparable to tPA in achieving TIMI (thrombolysis in MI risk score) 2 or 3 patency at 90 minutes. Heparin and aspirin usually are given concomitantly and afterward.
Tenecteplase (TNKase)
Tenecteplase is a modified version of alteplase (tPA) made by substituting 3 amino acids of alteplase. It can be given as a single bolus over a 5-second infusion, instead of over 90 minutes as with alteplase. Tenecteplase appears to cause less nonintracranial bleeding than alteplase does, but it poses a similar risk of intracranial bleeding and stroke. The dose should be based on the patient's weight. Because tenecteplase contains no antibacterial preservatives, it must be reconstituted immediately before use.
Anticoagulants
Class Summary
Anticoagulants are indicated for preventing further extension of thrombus in mesenteric venous thrombosis (MVT) or, after revascularization, in arterial occlusive AMI. In arterial occlusive AMI, whether anticoagulant therapy should be started immediately or after 48 hours when infarction is clearly absent is undetermined, because of the risk of gastrointestinal (GI) bleeding. Vitamin K antagonists (eg, warfarin) are used for maintenance therapy because they interfere with hepatic synthesis of vitamin K–dependent coagulation factors.
Heparin
Heparin augments the activity of antithrombin III and prevents conversion of fibrinogen to fibrin. This drug does not actively lyse but is able to inhibit further thrombogenesis. It prevents reaccumulation of clot after spontaneous fibrinolysis.
Warfarin (Coumadin, Jantoven)
Patients with MVT should be switched from heparin to warfarin when possible. Warfarin should be continued for 6 months if no contraindication or identifiable hypercoagulable state exists and for life if a permanent hypercoagulable state exists. Warfarin is also indicated for preventing further embolization in patients with atrial fibrillation. It is used for prophylaxis and treatment of venous thrombosis, pulmonary embolism, and thromboembolic disorders. The dosage should be tailored to keep the international normalized ratio (INR) in the 2-3 range.
Antibiotics
Class Summary
Antibiotics are administered to prevent or treat sepsis caused by breakdown of the mucosal barrier in bowel necrosis or perforation.
Clindamycin (Cleocin)
Clindamycin is a lincosamide used for treatment of serious skin and soft-tissue staphylococcal infections. It is also effective against aerobic and anaerobic streptococci (except enterococci). It inhibits bacterial growth, possibly by blocking dissociation of peptidyl tRNA from ribosomes, causing RNA-dependent protein synthesis to arrest.
Metronidazole (Flagyl, Metro)
Metronidazole is an imidazole ring–based antibiotic active against various anaerobic bacteria and protozoa. It is used in combination with other antimicrobial agents (except for Clostridium difficile enterocolitis).
Ticarcillin and clavulanate (Timentin)
Ticarcillin-clavulanate inhibits biosynthesis of cell wall mucopeptide and is effective during the stage of active growth. It consists of an antipseudomonal penicillin plus a beta-lactamase inhibitor and provides coverage against most gram-positive organisms, most gram-negative organisms, and most anaerobes.
Cefotetan
Cefotetan is a second-generation cephalosporin indicated for infections caused by susceptible gram-positive cocci and gram-negative rods. The dose and route of administration depend on the condition of the patient, the severity of the infection, and the susceptibility of the causative organism.
Cefoxitin (Mefoxin)
Cefoxitin is a second-generation cephalosporin that is indicated for infections with gram-positive cocci and gram-negative rods. Infections caused by cephalosporin- or penicillin-resistant gram-negative bacteria may respond to cefoxitin.
Meropenem (Merrem)
Meropenem is a bactericidal broad-spectrum carbapenem antibiotic that inhibits cell-wall synthesis. It is effective against most gram-positive and gram-negative bacteria.
Analgesics
Class Summary
Analgesics are used to relieve pain caused by bowel ischemia.
Morphine (Duramorph, Avinza, Astramorph, Kadian)
Morphine is the drug of choice for analgesia because of its reliable and predictable effects, its safety profile, and the ease with which its effects can be reversed by giving naloxone. Various intravenous doses are used; these are commonly titrated until the desired effect is obtained.
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Pneumatosis intestinalis (black stripes of air) in advanced acute mesenteric ischemia (AMI) with gangrenous bowel.
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CT scan (with contrast) of nonocclusive mesenteric ischemia with resulting bowel wall edema (arrows).
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Aortogram showing narrowing of superior mesenteric artery.
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Radiograph showing bowel spasm (early sign of ischemia).
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Gas in colon wall (typical of advanced ischemia).
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Ischemia stricture.
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Thumbprinting of bowel, characteristic of mesenteric artery ischemia.
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Pathologic findings 2 hours after bowel ischemia starts.
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Microscopic findings 24 hours after ischemia starts.
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Gross specimen showing hemorrhagic dead bowel after resection from patient with acute mesenteric ischemia.
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Pneumatosis intestinalis, one of few radiographic findings in patients with mesenteric ischemia.
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Diagnosis and treatment of intestinal ischemia (mesenteric venous thrombosis and major nonembolic arterial occlusion). Solid lines indicate accepted management plan; dashed lines indicate alternate management plan. DVT=deep vein thrombosis; SMA=superior mesenteric artery. Adapted from Gastroenterology. 2000 May;118(5):954-68.
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Diagnosis and treatment of intestinal ischemia (minor arterial occlusion or embolus, major embolus, and splanchnic vasoconstriction without occlusion). Solid lines indicate accepted management plan; dashed lines indicate alternate management plan. DVT=deep vein thrombosis; SMA=superior mesenteric artery. Adapted from Gastroenterology. 2000 May;118(5):954-68.
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Management of colon ischemia. Solid lines indicate accepted management plan; dashed lines indicate alternative management plan. BE=barium enema; NPO—nil per os (nothing by mouth); PLC=protein-losing colopathy; IBD=inflammatory bowel disease. Adapted from Gastroenterology. 2000 May;118(5):954-68.
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Complete aortic occlusion (Leriche syndrome) with acute embolism of superior mesenteric artery.
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Gross specimen of dead bowel.
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Meandering artery (radiographic sign of preexisting bowel ischemia).
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CT scan demonstrating thrombosis of superior mesenteric vein.
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CT scan demonstrating thrombosis of portal vein.
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CT scan demonstrating cavernous change of superior mesenteric vein as consequence of venous thrombosis.
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Mesenteric venous air (red arrows) and free intraperitoneal air (white arrow.) Mesenteric venous air is common finding in advanced acute mesenteric ischemia. Courtesy of Brandon Dessecker, MD, Melanie Nukula, MD, and Robert Marx, DO.
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Pronounced portal venous air seen within liver (red arrow), as well as free intraperitoneal air (white arrow) and pneumatosis intestinalis throughout bowel wall, which are classic findings for advanced acute mesenteric ischemia. Courtesy of Brandon Dessecker, MD, Melanie Nukula, MD, and Robert Marx, DO.
