2011年1月3日 星期一

Blunt Aortic Injury



Blunt Aortic Injury
N Engl J Med  2008;359:1708-16.

Pathophysiology
  • Sudden increase in intra-abdominal pressure may explain the association between blunt aortic injury and diaphragmatic rupture.
  • "Water-hammer" effect: simultaneous occlusion of the aorta and a sudden elevation in blood pressure
  • "Osseous pinch" effect: entrapment of the aorta between the anterior chest wall and the vertebral column.
Diagnosis
  • The absence of the following signs on CXR were valuable to exclude the diagnosis of aortic injury:
  • loss of the aortico-pulmonary window
  • abnormality of the aortic arch
  • rightward tracheal shift
  • widening of the left para-spinal line without associated fracture
  • Between 7.3% and 44% of patients with blunt aortic injury may have a normal mediastinum on CXR.
  • Helical CT of the thorax is now the diagnostic test of choice (sensitivity 100%).
  • Minimal Aortic Injury was defined as an intimalflap of less than 1 cm with no or minimal peri-aortic hematoma, 50% of minimal aortic injuries that were followed up had developed pseudo-aneurysms by 8 weeks after injury.
  • If the injury is associated with significant thrombus, peri-aortic hematoma, lumen encroachment, or pseudo-aneurysm, it is our practice to proceed with endograft coverage.
Surgical Repair
  • Advantages of the veno-arterial bypass include the ability to cool the patient, which potentially enhances spinal-cord protection.
Endovascular Repair
Advantages
  • No physiological burden
  • In brain injury, the device can be deployed with the head of the bed elevated
  • Not require single-lung ventilation
  • Minimal or no heparin
  • No need for a bypass of any kind
  • No cause of paraplegia
Technical Limitations to Endografting
  • Injuries that occur adjacent to a sharp bend in the aorta may result in poor apposition of the covered stent to the aortic wall.
  • Lesions adjacent to the left subclavian artery.
  • Coverage of the left subclavian artery can result in ischemia of the upper extremity or territory perfused by the left vertebral artery.

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