Case 5

Chronic Dissection of Aneurysmal Descending Aorta

A 65 year old gentleman who sustained a type B aortic dissection 7 years previously that was treated conservatively has been followed up annually with CT scans to monitor his aorta. He has no symptoms. The most recent scan revealed that his descending aorta was now 7cm, having increased markedly in the last year. CT scanning reveals that the dissection extends from mid aortic arch down to and including both iliac arteries. Only the mid to lower third of the descending aorta is aneurysmal though. It is thought that one iliac originates from the true lumen and the other from the false lumen. What would you do ?

Due to the size increase some type of intervention is needed.

From the information given he needs his descending aorta replaced, via a left thoracotomy. 

By some means a tube graft needs to be inserted distal to the left subclavian if possible to the level of the diaphragm. 

Both proximal and distal fenestrations need to be performed. 

Patch or selective insertion of intercostals needs to be considered to try and reduce the risk of paraplegia.

Cardiac evaluation via echocardiography and coronary angiography is probably wise prior to operative intervention on the descending aorta.

Bypass options

Option 1 

Left heart bypass from left superior or inferior pulmonary vein to femoral artery. Keep the patients temperature above 32^oC to avoid VF. Clamp below left subclavian and just above diaphragm.

Option 2

Full bypass via femoral - femoral cannulation and cool to 18^oC and perform circulatory arrest. If you have to go into the arch proximal to the left subclavian this is probably the option or in the case of redo surgery.

Perfusion catch

Depending on true and false lumen communication cannulating one femoral may not result in 100% tissue perfusion and both femorals may need cannulating. (If the true and false lumen are completely separate from the point at which the lower clamp is applied to the descending aorta).