Correlations of Cerebrospinal Fluid Pressure with Hemodynamic Parameters During Thoracoabdominal Aortic Aneurysm Repair

A minimally invasive approach for open surgical thoracoabdominal aortic replacement: experimental concept for a novel surgical procedure

Objectives

We aimed to develop a simple, reliable, and timesaving technique for the therapy of thoracoabdominal aortic (TAA) aneurysms that are not suitable for endovascular repair.

Methods

In this pilot study, we sought to combine the advantages of classic open vascular procedure with the use of endoscopic surgical tools and small skin incisions to develop a minimally invasive approach for TAA replacement. The following procedures were used: endoscopic exposure and closure of the lower intercostal arteries; small posterolateral thoracotomy and left retroperitoneal incisions to expose the anastomotic regions of the aorta; partial anticoagulation; passive bypass and sequential aortic clamping; tunnelling of the graft through the native aortic lumen (endoaneurysmorrhaphy) and open performance of vascular anastomosis.

Results

Five mixed-breed dogs (25-35 kg) underwent minimally invasive TAA replacement. All animals survived the operation without blood transfusion (lowest Hb = 5.5 mg/dl). Total operation time was 364 ± 46.3 min. Clamping times were 17.6 ± 3.2 min for proximal anastomosis, 33.2 ± 2.48 min for visceral patch and 11 ± 2.3 min for distal anastomosis. The pull-through procedure of graft through the native aorta was performed during the visceral clamp time.

Conclusions

Surgical replacement of the TAA through small transverse incisions of the thoracic and abdominal wall is feasible and allows open performance of all vascular anastomosis with no leakage at any anastomotic site. Further experimental studies and clinical implementation are needed to establish the safety and long-term outcome of minimally invasive TAA replacement as a possible primary therapeutic tool for complex aneurysms that are not suitable for endovascular treatment and require open surgical repair.

Spinal cord perfusion after extensive segmental artery sacrifice: can paraplegia be prevented?

OBJECTIVE

Understanding the ability of the paraspinal anastomotic network to provide adequate spinal cord perfusion pressure (SCPP) critical for both surgical and endovascular repair of thoracoabdominal aortic aneurysms (TAAA).

METHODS

To monitor pressure in the collateral circulation, a catheter was inserted into the distal end of the divided first lumbar segmental artery (SA) of 10 juvenile Yorkshire pigs (28.9+/-3.8kg). SA pairs from T3 through L5 were serially sacrificed at 32 degrees C; SCPP and function - using motor-evoked potentials (MEPs) - were continuously monitored until 1h after clamping the last SA. Intermittent aortic and SCPP monitoring was continued for 5 days postoperatively, along with evaluation of motor function.

RESULTS

A mean of 14.4+/-0.7 SAs were sacrificed without loss of MEP. SCPP (mmHg) dropped from 68+/-7 before SA clamping (77% of aortic pressure) to 22+/-6 at end clamping, and 21+/-4 after 1h, reaching its lowest point - 19+/-4 - after 5h. Postoperatively, SCPP recovered to 33+/-6 at 24h; 42+/-10 at 48h; 56+/-14 at 72h; 62+/-15 at 96h, returning to baseline (63+/-20) at 120h. Despite comparable SCPP patterns, four pigs did not fully regain the ability to stand. Six animals recovered: two could stand and four could walk.

CONCLUSIONS

Interruption of all SAs at 32 degrees C in this pig model results in a spectrum of cord injury, with normal function in a majority of pigs postoperatively. The short duration of low SCPP suggests that hemodynamic manipulation lasting only 24-48h may allow routine complete preservation of normal cord function despite sacrifice of all SAs.