What are the markers and management of visceral malperfusion?

Markers and Management of Visceral Malperfusion

Visceral malperfusion is a life-threatening complication of aortic dissection that requires immediate intervention with a combined surgical and endovascular approach to restore perfusion and prevent organ failure. Approximately 30% of patients with acute type A aortic dissection (TAAD) develop malperfusion syndrome, which significantly increases mortality risk 1.

Markers of Visceral Malperfusion

Clinical Markers

• Abdominal pain disproportionate to physical examination findings, which should raise immediate suspicion of mesenteric ischemia 1
• Unexplained abdominal distension or gastrointestinal bleeding, which may be the only signs in approximately 25% of cases, particularly in sedated ICU patients 1
• Right-sided abdominal pain associated with maroon or bright red blood in stool is highly suggestive of non-occlusive mesenteric ischemia (NOMI) 1
• Bacteremia and diarrhea in patients who have survived cardiopulmonary resuscitation 1
• In ventilated patients, negative changes in physiology including new onset organ failure, increased vasopressor requirements, and nutrition intolerance 1

Laboratory Markers

• Elevated lactate levels, though not specific to visceral ischemia 1
• Elevated D-dimer levels may assist in diagnosis 1
• Metabolic acidosis and hyperkalemia may result from bowel infarction and reperfusion 1
• No single laboratory test is sufficiently accurate to identify ischemic or necrotic bowel 1

Imaging Markers

• Computed Tomography Angiography (CTA) should be performed immediately in any patient with suspicion of mesenteric ischemia 1
• Point-of-care ultrasonography (POCUS) is recommended for patients with thoracoabdominal injuries 1
• Contrast extravasation on CT may help identify patients requiring angiography 1
• Evidence of elevated pressure in the false lumen causing compression of the true lumen 1
• Static "stenosis-like" blockage from intimal flap extension into peripheral arteries 1

Management of Visceral Malperfusion

Initial Resuscitation

• Immediate fluid resuscitation to enhance visceral perfusion 1
• Correction of electrolyte abnormalities and acid-base status 1
• Nasogastric decompression 1
• Cautious use of vasopressors; dobutamine, low-dose dopamine, and milrinone have less impact on mesenteric blood flow 1
• Broad-spectrum antibiotics should be administered immediately 1
• Unless contraindicated, anticoagulation with intravenous unfractionated heparin 1

Management Algorithm for Aortic Dissection with Visceral Malperfusion

For Type A Aortic Dissection:

1. Check for complications including mesenteric malperfusion and lower extremity malperfusion 1
2. Consider invasive diagnostics and/or percutaneous malperfusion repair or TEVAR/EVAR (Class IIa recommendation) 1
3. Direct admission to hybrid operating room with onsite aortic team 1
4. Anesthesiological monitoring and intraoperative TOE (if feasible) 1
5. Immediate aortic surgery (ascending and consider aortic arch or FET based on extension) (Class I recommendation) 1
6. If malperfusion persists after surgery, perform angiographic control and/or percutaneous malperfusion repair/TEVAR/EVAR (Class IIa recommendation) 1

For Type B Aortic Dissection with Visceral Malperfusion:

• TEVAR or EVAR and/or percutaneous malperfusion repair is indicated 1
• In case of retrograde aortic dissection, immediate aortic surgery is recommended 1
• If malperfusion persists, angiographic control and/or percutaneous malperfusion repair or TEVAR/EVAR should be performed 1

Special Considerations for Mesenteric Malperfusion

• Mesenteric malperfusion is a life-threatening complication with mortality rates of 65-95% 1
• Treatment approaches vary between centers - some prefer early direct reperfusion before aortic surgery, while others favor conventional central aortic repair 1
• For NOMI, treatment should focus on correcting the underlying cause and restoring mesenteric perfusion 1
• Infarcted bowel should be resected promptly 1
• Damage control surgery is an important adjunct for patients requiring intestinal resection 1
• Planned re-laparotomy is essential to reassess bowel viability 1

Prognostic Factors and Outcomes

• Operative mortality correlates with the number of affected organs 1
• Visceral malperfusion is the strongest predictor of postoperative mortality (odds ratio: 25.09) 2
• In-hospital mortality for acute type B aortic dissection with visceral ischemia is approximately 30.8% compared to 9.1% without visceral ischemia 3
• Medical management alone for visceral ischemia is associated with higher mortality (OR 5.91) 3
• Early diagnosis and intervention are crucial for improved outcomes 3
• The International Registry of Acute Aortic Dissection (IRAD) supports a combined surgical and hybrid approach over medical or endovascular therapy alone 1

Pitfalls and Caveats

• Visceral malperfusion may be difficult to diagnose, especially in sedated ICU patients 1
• Overly aggressive fluid resuscitation may increase intra-abdominal pressure and worsen inflammatory response 1
• Vasopressors like norepinephrine and epinephrine might impair mucosal perfusion 1
• The ischemic time (interval between onset of dissection and visceral arterial revascularization) is critical - longer times are associated with worse outcomes 4
• The optimal timing for central aortic repair after restoration of end-organ perfusion remains unknown, with persistent risk of rupture before repair 5
• Conventional plain X-ray films have limited diagnostic value in evaluating mesenteric ischemia 1