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Descending thoracic aneurysm and thoracoabdominal aneurysm repairs

Measures to reduce spinal cord injury include cerebrospinal fluid drainage, reimplantation of intercostal arteries, partial bypass, and mild hypothermia. A left thoracotomy or a thoracoabdominal incision is performed. The aorta is cross-clamped either just beyond the left subclavian or between the left carotid and left subclavian for Crawford types I and II. The cross clamp is placed more distally for Crawford types III and IV.

Atrial femoral bypass is established with a Bio-Medicus circuit, and the patient is cooled to 32-34°C (89.6-93.2°F). Distal cross-clamping is performed at T4-T7 to allow continued spinal cord, visceral, and renal perfusion. The proximal anastomosis is performed with running 4-0 Prolene and a strip of felt. When complete, the proximal clamp is released and reapplied more distally on the tube graft. The distal cross clamp is moved sequentially down, if feasible, to allow visceral and renal perfusion. The intercostal arteries may be reimplanted, if desired, or oversewn. If sequential cross-clamping is not feasible, direct catheters may be placed in the visceral and renal vessels to allow continuous perfusion.

If the distal aneurysm extends to the renals, then the distal anastomosis may be beveled to incorporate the visceral and renal vessels and distal aorta. If the distal aneurysm extends to the bifurcation, the visceral and renal vessels are reattached to the tube graft. The left renal artery typically requires a separate anastomosis, but the celiac, superior mesenteric, and right renal arteries are often incorporated as a single island. The patient is rewarmed, and the partial bypass is discontinued as the tube graft perfuses the intercostals and abdominal vessels. The distal anastomosis at the bifurcation is performed as an open distal procedure.

For appropriate descending thoracic aortic aneurysms, endovascular stent grafting is a good alternative. Depending on the size of the patient's femoral or iliac arteries and size of the stent graft required, femoral or iliac artery exposure is performed under general or local anesthesia plus sedation. A sheath is placed and a wire guided under fluoroscopy into the arch. When in proper position, the floppy wire is exchanged with a soft catheter and rewired to a stiffer wire for device placement. The sheath is exchanged for the appropriate device sheath. The contralateral groin is used for angiocatheter placement.

After angiography and determination of stent placement, the device is loaded and, under fluoroscopic guidance, is positioned and deployed. More than one stent may be used, with as much overlap as is feasible, for stability. The proximal and distal landing zones are ballooned to seal the endograft to the aorta. The overlapping stent-graft segments are also ballooned. Angiography is performed to check for endoleaks. Endoleaks may require additional stents.

Thoracoabdominal aortic aneurysms may involve arteries supplying the abdominal viscera. In this case, for a completely endovascular repair, aortic stent grafts with fenestrations or branches oriented towards the intended covered arteries have been devised. These grafts previously have been individualized to the specific anatomy of the patient, although recent data have demonstrated that noncustomized branch grafts may work for most patients.[33]



Initial placement of the aortic stent graft ensues, carefully aligning the fenestrations or branches to the abdominal viscera. The abdominal visceral arteries are then cannulated with separate guidewires in a retrograde fashion for cranially oriented arteries, or through the brachial artery for in an antegrade fashion for caudally oriented arteries. A bridging covered stent is then deployed to create a visceral seal zone.

Ross procedure (pulmonary autograft)

The aortic root and proximal ascending aorta are replaced with a pulmonary autograft.[25] The pulmonary valve is then replaced with a pulmonary homograft. Most commonly performed in children with congenital disease, the Ross operation may be used for active young adults with aneurysmal disease (excluding those with connective tissue disorders), women of childbearing age who desire pregnancy, or patients with contraindications to anticoagulation.


Date: 2015-12-11; view: 720


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