Mesentric Ischemia Flashcards
Mesenteric ischemia definition
Reduction in blood flow for intestinal circulation of
sufficient magnitude to compromise the viability of the affected portion, leading to ischemia cellular damage or even entire bowel wall necrosis.
Classification of Mesenteric ischemia
Acute
Chronic
Causes of acute Mesenteric ischemia
- SMA embolic occlusion
- SMA thrombotic occlusion
- non- occlusive Mesenteric ischemia
- Mesenteric vein thrombosis
Embolic occlusion can originate from ?
the left atrium, as in atrial fibrillation
left ventricle if there is myocardial
dysfunction associated with poor
ejection fraction
cardiac valves due to endocarditis.
Occasionally emboli generated from
an atherosclerotic aorta with or without
aneurismal dilatation.
Thrombotic occlusion occur in pre-existing stenosis due to ?
Atherosclerosis
Affected vessels in thrombotic occlusion ?
Terminal branches and collateral arteries ( which is poorly developed)
Orpington of visceral arteries
Mesenteric vein ischemia virchows triad ?
Hypercoagubility: congenital: as protein S deficiency, protein C deficiency, antithrombin
deficiency, and antiphospholipid syndrome.
Thrombophilia may also be acquired due to malignancies, hematologic disorders, and oral
contraceptives.
Stasis: Portal HTN
Acute non occlusive Mesenteric ischemia
Ischemia NOMI occurs in approximately 20% of cases
Is usually a consequence of SMA vasoconstriction
associated with low splanchnic blood flow (as in
hypovolemic and cardiogenic shock specially with the use of vasoconstrictor drugs).
The compromised SMA blood flow often involves the
proximal colon as well due to involvement of the ileocolic artery.
Clinical features
signs early
Minimal abdominal findings as slight distension with no tenderness
Pain out of proportion to abdominal signs must raise suspicion
(hallmark)
Late signs
Late: with established severe ischemia ± perforation and peritonitis
• Systemic toxicity, septic shock
• Abdominal distention
• Generalized peritonitis
• Blood in stool
Lab investigations
Imaging CTA finding ?
- Arterial calcification, embolism, thrombosis
- Vein thrombosis
- Signs of bowel infarction: intestinal dilatation and thickness, absence of enhancement of the affected loops, pneumatosis intestinalis, and portal venous gas
- Perforation: free intraperitoneal air
Sign of bowel infarction
intestinal dilatation and thickness, absence
of enhancement of the affected loops, pneumatosis intestinalis, and portal venous gas
D.D of Mesenteric Ischemia
Acute pancreatitis
• Intestinal obstruction
• Peptic ulcer disease
• Gastroenteritis
• Perforated viscus
Treatment of Mesenteric ischemia - ER Care
ABC
• Fluid resuscitation
• NGT decompression
• NPO
• Correct electrolyte disturbance
• ICU care
• Monitor vital signs
• Input output fluid chart
Treatment- medication
Anticoagulation therapy with intravenous unfractionacted heparin.
• Antibiotics – broad spectrum
• Analgesia
• Antiemetic
• Control medical problems: Embolic? Thrombotic? NOMI? Venous?
When NOMI is suspected, the focus is to?
correct the underlying
cause wherever possible and to improve mesenteric perfusion
Indication of surgery
Signs of peritonitis
• CT signs of bowel infarction
Exploratory laparotomy
• Re-establishment blood supply to the ischemic bowel
• Resection of all non-viable regions
Surgical option to Mesenteric arterial embolism ?
- Embolectomy then distal bypass graft
- Resect necrotic bowel
Surgery of Mesenteric arterial thrombosis ?
Bypass graft or stenting
Resect necrotic bowel
Surgery of NOMI
Treat the underlying cause
Fewer surgical options
Papaverine or glycerol infusion
Resect necrotic bowel
Mesenteric venous thrombosis
Depends on extent of ischemia
Difficult for surgical management if diffuse thrombosis
Mild ischemia: treat with bowel resection of necrotic segment
Endovascular options for Mesenteric vascular occlusion
percutaneous transluminal angioplasty and stent placement
• Remains controversial but may have a role with partial arterial occlusion
Complications of Mesenteric ischemia
• Perforation • Septic shock • Multiple organ failure • Malnutrition • Short bowel syndrome • Complications of parenteral nutrition
• Mortality rates reach 80%
Clinical features of intestinal angina
Recurrent abdominal postprandial pain with increasing frequency and severity
• Weight loss
Signs:
• Abdominal bruit
Investigations of chronic ischemia
• Duplex u/s • CTA • MRA • Conventional angiography
Treatment of chronic ischemia
• Surgical :
• Trans aortic endarterectomy
• Bypass
• Angioplasty
• Endovascular:
• PTA: percutaneous transluminal angioplasty
• Stent
