What is the assessment and plan for an older adult with chronic superior mesenteric and celiac artery thrombosis, a newly identified 6.3 cm descending thoracic aortic aneurysm with large intramural thrombus, and imaging showing dilated small‑bowel loops with stasis consistent with low‑grade small‑bowel obstruction?

Assessment and Plan for Chronic Mesenteric Thrombosis with Thoracic Aortic Aneurysm and Bowel Dilation

This patient requires urgent multidisciplinary vascular surgery and cardiothoracic surgery consultation for simultaneous management of a life-threatening 6.3 cm descending thoracic aortic aneurysm with intramural thrombus and chronic mesenteric ischemia with evolving low-grade obstruction. 1

Assessment

1. Descending Thoracic Aortic Aneurysm (6.3 cm) with Large Intramural Thrombus - HIGHEST PRIORITY

• The 6.3 cm aneurysm exceeds surgical intervention thresholds and represents imminent rupture risk, particularly given the extensive intramural thrombus which increases wall stress and rupture potential 1
• The presence of intramural thrombus in this setting is a high-risk feature that demands urgent intervention regardless of symptom status 1
• This takes precedence over the chronic mesenteric disease in terms of immediate mortality risk, though both require coordinated management 1

2. Chronic Superior Mesenteric Artery and Celiac Artery Thrombosis

• The patient has established chronic mesenteric ischemia (CMI) from atherosclerotic thrombosis affecting both major mesenteric vessels 1, 2
• The chronic nature is evidenced by the extensive collateral development that has prevented acute bowel infarction despite dual-vessel involvement 1, 3
• Typical CMI presentation includes postprandial abdominal pain, weight loss, food aversion (sitophobia), and gastrointestinal disturbances 1, 4
• The atherosclerotic thrombotic etiology (versus embolic) is suggested by the chronic presentation and likely presence of calcified plaque 2

3. Dilated Small Bowel Loops with Stasis - CONCERNING EVOLUTION

• The new finding of dilated small bowel with stasis without transition point suggests either functional ileus from chronic hypoperfusion or evolving low-grade mechanical obstruction 1
• Absence of wall thickening or acute inflammatory changes argues against acute mesenteric ischemia with bowel infarction 1, 2
• This may represent chronic intestinal dysmotility from repeated ischemic insults or early decompensation of collateral circulation 4
• The lack of peritoneal signs is reassuring but does not eliminate the need for urgent intervention 2, 4

Plan

Immediate Actions (Within 24 Hours)

A. Vascular Surgery and Cardiothoracic Surgery Consultation - STAT

• Obtain urgent multidisciplinary consensus on staged versus simultaneous repair strategy 1
• The 6.3 cm thoracic aneurysm requires intervention, but mesenteric revascularization may need to precede or accompany aortic repair to prevent bowel ischemia during the perioperative period 1, 5

B. Laboratory Assessment

• Obtain lactate level immediately - elevated lactate indicates advanced bowel gangrene and would mandate emergency laparotomy rather than staged approach 2, 4
• Check D-dimer (96% sensitivity for ruling out acute mesenteric ischemia if negative, though poor specificity) 2
• Complete metabolic panel, CBC with differential (leucocytosis may indicate evolving ischemia) 1, 2
• Coagulation studies in preparation for potential anticoagulation 2

C. Imaging Optimization

• Review existing CTA with vascular surgery to assess:
  • Extent of mesenteric collateralization 1, 3
  • Anatomic suitability for endovascular mesenteric revascularization 1
  • Thoracic aortic aneurysm anatomy for endovascular versus open repair planning 1
  • Presence of peritoneal free fluid, bowel wall thickening, or pneumatosis (would indicate acute ischemia requiring emergency surgery) 2, 4

D. Medical Optimization

• NPO status with nasogastric decompression if significant nausea/vomiting or abdominal distension 4
• Aggressive IV hydration to optimize mesenteric perfusion 4
• Initiate systemic anticoagulation with unfractionated heparin (unless contraindicated by aneurysm characteristics or bleeding risk) given thrombotic etiology 2
• Hold oral intake to minimize mesenteric oxygen demand 4

Definitive Management Strategy

Option 1: Staged Approach (Most Likely Scenario)

Step 1: Mesenteric Revascularization First

• Endovascular revascularization of SMA and/or celiac artery via percutaneous transluminal angioplasty with stent placement is the preferred initial approach 1, 4, 6
• Endovascular therapy has supplanted open surgical repair with lower mortality and morbidity, though higher reintervention rates 4, 6
• Stenting provides superior long-term secondary patency (100% at 10 years) compared to angioplasty alone (86%) 6
• Even single-vessel revascularization provides sustained symptom relief in 73% of CMI patients with confirmed mucosal ischemia 3
• Catheter-directed vasodilator infusion should be considered to address associated vasospasm 2

Step 2: Thoracic Aortic Aneurysm Repair (2-4 Weeks Post-Mesenteric Revascularization)

• Thoracic endovascular aortic repair (TEVAR) is preferred if anatomically suitable given lower perioperative risk 1
• Open repair if anatomy precludes endovascular approach 1
• Custom fenestrated devices may be required if aneurysm extends to involve visceral vessels 5, 7

Option 2: Simultaneous Repair (If Aneurysm Deemed Unstable)

• If imaging suggests impending rupture (rapid expansion, symptomatic aneurysm, contained rupture), simultaneous repair may be necessary 1, 5
• Requires custom fenestrated endograft with mesenteric vessel preservation or hybrid open approach 5, 7
• Higher perioperative risk but may be unavoidable given aneurysm size 1

Option 3: Emergency Surgery (If Acute Decompensation Occurs)

• If patient develops peritoneal signs, septic shock, or markedly elevated lactate suggesting bowel infarction, proceed directly to emergency laparotomy 4
• Open mesenteric revascularization with bowel viability assessment and resection of non-viable segments 1, 2
• Retrograde open mesenteric stenting (ROMS) offers shorter operative time alternative 1

Post-Intervention Management

A. Anticoagulation/Antiplatelet Therapy

• Lifelong anticoagulation is essential given thrombotic etiology and underlying atherosclerotic disease 1, 2
• Most patients require lifelong anticoagulant/antiplatelet therapy to prevent recurrence 1
• Specific regimen depends on surgical versus endovascular approach and concurrent atrial fibrillation status 1, 2

B. Surveillance Protocol

• CTA or duplex ultrasound within 6 months post-mesenteric revascularization 1
• Society for Vascular Surgery recommends duplex at 1,6, and 12 months, then annually thereafter 1
• Recurrent acute mesenteric ischemia after revascularization accounts for 6-8% of late deaths 1
• Thoracic aneurysm surveillance per standard TEVAR or open repair protocols 1

C. Secondary Prevention

• Aggressive atherosclerotic risk factor modification with high-intensity statin therapy 1
• Blood pressure control, smoking cessation, diabetes management 1, 4
• Nutritional rehabilitation given likely significant weight loss from chronic symptoms 4, 3

Critical Pitfalls to Avoid

• Do not delay intervention for elevated creatinine - mortality risk of missing mesenteric ischemia or aneurysm rupture far outweighs contrast nephropathy risk 2, 4
• Do not rely on normal lactate or absence of peritoneal signs to exclude evolving ischemia - these are late findings 2, 4
• Do not address the aneurysm without considering mesenteric perfusion - perioperative hypotension during aneurysm repair could precipitate acute mesenteric ischemia in setting of chronic occlusions 1, 5
• Do not attempt thrombolysis if bowel infarction cannot be confidently excluded 2
• Time to diagnosis and intervention is the most important predictor of outcome 2