Open aortic surgery

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Open aortic surgery ("OAS", also known as Open aortic repair, "OAR") describes a surgical technique whereby a surgical incision is used to visualize and control the aorta for purposes of repair. OAS is used to treat aneurysms of the abdominal and thoracic aorta, aortic dissection, acute aortic syndrome, and aortic ruptures. In 2003, OAS was surpassed by Endovascular aneurysm repair(EVAR) as the most common technique for repairing abdominal aortic aneurysms in the United States.[1] In OAS for AAA, the aneurysmal portion of the aorta is replaced with a graft, usually made of dacron or PTFE.

Open aortic surgery is distinct from heart valve repair and aortic valve replacement, as OAS focuses on diseases of the aorta itself, rather than the heart valves.

Uses[edit]

OAS is used to treat patients with aortic aneurysms greater than 5.5 cm in diameter, to treat ruptured aortic aneurysms of any size, to treat aortic dissections, and to treat acute aortic syndrome. It is used to treat infrarenal aneurysms as well as juxta- and pararenal aneurysm and thoracoabdominal aneurysms, as well as non-aneurysmal aortic pathology.

Prior to the advent of EVAR, OAS was the only surgical treatment available for aortic aneurysms. It is still preferred at some institutions and by some patients as it may be more durable than EVAR[2] and does not require post-operative surveillance CT scans.

Contra-Indications[edit]

The shift away from open aortic surgery towards endovascular surgery since 2003 has been driven by worse perioperative mortality associated with OAS, particularly in patients in relatively frail health.[3] Unlike endovascular repair, there are no strict anatomic contra-indications to open repair; Rather, open repair is viewed as a last resort for patients with unfavorable anatomy for endovascular repair.[4]

Technique[edit]

Approach[edit]

The infrarenal aorta can be approached via a transabdominal midline or paramedian incision, or via a retroperitoneal approach. The paravisceral and thoracic aorta are approached via a left-sided posteriolateral thoracotomy incision in approximately the 9th intercostal space.[5]

Sequential aortic clamping[edit]

At medical centers with a high volume of open aortic surgery, the fastest option for open aortic surgery was sequential aortic clamping or "clamp-and-sew", whereby the aorta was clamped proximally and distally to the diseased segment, and a graft sewn into the intervening segment.[6] This technique leaves the branches of the aorta un-perfused during the time it takes to sew in the graft, potentially increasing the risk of ischemia to the organs which derive their arterial supply from the clamped segment. Critics of this technique advocate intra-operative aortic perfusion.[7] In infrarenal aneurysms, the relative tolerance of the lower extremities to ischemia allows surgeons to clamp distally without undue concern.

Intra-operative aortic perfusion[edit]

A number of techniques exist for maintaining perfusion to the viscera during open thoracoabdominal aortic aneurysm repair, including left heart bypass, balloon perfusion catheter placement in the visceral arteries, and cold crystalloid renal perfusion.[8] Selective spinal drainage is also employed to reduce the incidence of spinal cord ischemia.

Risks/Complications[edit]

Open aortic surgery is widely recognized as having higher rates of perioperative morbidity and morality than endovascular procedures for comparable segments of the aorta. For example, in infrarenal aneurysms, perioperative mortality with endovascular surgery is approximately 0.5%, vs 3% with open repair.[9]

Other risks/complications with aortic surgery depend on the segment of aorta involved, and include renal failure, spinal cord ischemia leading to paralysis, buttock claudication, ischemic collitis, embolization leading to acute limb ischemia, infection, and bleeding.

References[edit]

  1. ^ Impact of hospital market competition on endovascular aneurysm repair adoption and outcomes. PMID 23684424. 
  2. ^ Long-term durability of open abdominal aortic aneurysm repair. PMID 17903647. 
  3. ^ Long-term comparison of endovascular and open repair of abdominal aortic aneurysm. PMID 23171095. 
  4. ^ Endovascular repair of abdominal aortic aneurysm. PMID 24453068. 
  5. ^ Coselli, Joseph (2008). "Tips for successful outcomes for descending thoracic and thoracoabdominal aortic aneurysm procedures.". Semin Vasc Surg. PMID 18342730. 
  6. ^ Descending thoracic aortic aneurysm repair: 12-year experience using distal aortic perfusion and cerebrospinal fluid drainage. PMID 16181856. 
  7. ^ Descending thoracic aortic aneurysm repair: 12-year experience using distal aortic perfusion and cerebrospinal fluid drainage. PMID 16181856. 
  8. ^ Coselli, Joseph (2008). "Tips for successful outcomes for descending thoracic and thoracoabdominal aortic aneurysm procedures.". Semin Vasc Surg. PMID 18342730. 
  9. ^ Schermerhorn, Marc (2008). "Endovascular vs. open repair of abdominal aortic aneurysms in the Medicare population.". N England J Med. PMID 18234751.