What is acute mesenteric ischemia in adolescents?

What is Acute Mesenteric Ischemia in Adolescents?

Acute mesenteric ischemia (AMI) in adolescents is an extremely rare but life-threatening vascular emergency caused by sudden interruption of blood supply to the intestine, leading to bowel necrosis and death if untreated, with mortality rates of 50-80%. 1, 2

Definition and Pathophysiology

AMI is characterized by sudden interruption of blood supply to varying portions of the intestine, leading to ischemia and secondary inflammatory changes that progress to intestinal necrosis if untreated. 1 While AMI typically affects elderly patients with atherosclerotic disease, it does occur in the pediatric and adolescent population, though it is particularly rare in this age group. 3

Etiologic Categories in Adolescents

The causes of AMI in adolescents differ substantially from the typical adult presentation:

Arterial Occlusive Disease

• Mesenteric arterial thrombosis or stenosis associated with congenital vascular abnormalities, particularly abdominal aortic coarctation and/or renal artery stenoses, which coexist in the majority of pediatric cases. 3
• Arterial emboli are less common in adolescents compared to adults, as this age group typically lacks atrial fibrillation or other embolic sources. 1

Non-Occlusive Causes

• Non-occlusive mesenteric ischemia (NOMI) can occur in critically ill adolescents with sepsis, multi-organ dysfunction, or those requiring high-dose vasopressor support. 4
• Mesenteric venous thrombosis may occur in adolescents with inherited hypercoagulable states (Factor V Leiden, prothrombin mutation, protein C/S deficiency, antithrombin deficiency) or acquired conditions. 1

Clinical Presentation in Adolescents

The clinical spectrum ranges from subtle, nonspecific symptoms to acute abdominal catastrophe:

• Classic presentation: Severe abdominal pain out of proportion to physical examination findings, which should be assumed to be AMI until disproven. 1
• Chronic presentations: Postprandial abdominal pain 30-60 minutes after eating, progressive weight loss, food avoidance, nausea, vomiting, and early satiety may precede acute decompensation. 1, 3
• Acute presentations: Evolving gastrointestinal infarction with peritoneal signs represents advanced disease. 3
• Silent ischemia: Some pediatric patients may have clinically silent ischemia discovered incidentally during evaluation for other conditions. 3

Diagnostic Approach

Imaging

• Computed tomography angiography (CTA) should be performed as soon as possible for any adolescent with suspicion for AMI, as it is the first-line imaging technique. 1
• Conventional angiography remains the reference standard with sensitivity of 74-100% and specificity of 100%, and allows for therapeutic intervention. 1
• Plain radiography has limited diagnostic value, though signs of intestinal perforation may be seen in advanced cases. 1

Laboratory Findings

• No laboratory studies are sufficiently accurate to identify the presence or absence of ischemic bowel, although elevated lactate and D-dimer may assist. 1
• Elevated lactate, acidosis, and leukocytosis are signs of advanced mesenteric ischemia. 5

Management Principles

Initial Resuscitation

• Immediate fluid resuscitation to enhance visceral perfusion, correction of electrolyte abnormalities, and nasogastric decompression. 1
• Broad-spectrum antibiotics should be administered immediately, though evidence specifically for AMI is limited. 1, 6
• Anticoagulation with intravenous unfractionated heparin unless contraindicated. 1

Revascularization Strategy

• Prompt surgical revascularization (embolectomy, thrombectomy, bypass) is preferable to intestinal resection alone when irreversible ischemia or sepsis are not present, as it can prevent mesenteric infarction. 5
• Endovascular approaches have shown improved outcomes with lower mortality rates, decreased bowel resection, and reduced renal and respiratory failure compared to traditional open surgery. 2
• Prompt laparotomy is mandatory for patients with overt peritonitis. 1

Surgical Considerations in Adolescents

• Successful bowel revascularization in pediatric cases has been achieved by superior mesenteric artery reimplantation, bypass procedures, or multiple celiac and superior mesenteric artery bypasses. 3
• Damage control surgery with planned re-laparotomy 24-48 hours later is essential to reassess bowel viability and avoid unnecessary resection. 1
• The goal is to conserve as much bowel as possible, resecting only obviously necrotic segments. 1

Critical Pitfalls

• Delayed diagnosis is the most significant contributor to the 50-80% mortality rate. 2
• In adolescents with renal artery stenosis or renovascular hypertension, adequate evaluation of mesenteric vessels must be performed before renovascular procedures are undertaken, as coexistent visceral artery disease is common. 3
• Failure to consider the diagnosis in young patients due to its rarity leads to catastrophic delays. 3
• Time to diagnosis and intervention is the most critical predictive factor for survival. 5

Prognosis

The mortality rate remains extremely high at 50-80% if untreated, despite advances in diagnostic and treatment modalities. 2 Early diagnosis with contrast-enhanced CT and revascularization can reduce overall mortality by up to 50%. 7 Predictive factors for survival include time duration between symptom onset and therapy, etiology, patient age, and immediate anticoagulation therapy. 5