Clinical Study Of The Remodeling Of Stanford B Thoracic Aortic Dissection After Endovascular Exclusion

Objective:1. To observe long term remodeling process of thoracic aortic dissection after endovascular exclusion and study remodeling regularity.2. According to the difference of the remodeling with different grouping such as sex et al, evaluate factors affecting remodeling after endovascular exclusion.Methods:1. From September 1998 to October 2005, endovascular exclusion for Stanford B thoracic aortic dissection were preformed in 192 patients (135 men;149 chronic;mean age 54.6 years, range 26-87). CTA or MRA was used as preoperative evaluation methods. Under DSA guidance, appropriate endovascular stent-grafts were inserted from the femoral or iliac artery to exclude tears of dissection to induce false lumen thrombosis and restore blood flow of true lumen and improve visceral blood supply and prevent the rupture of the aneurysm.The long term follow up records were established for all patients postoperativelv and the patients were followed with contrast enhancedspiral CT at 6 months, 1 year postoperatively and yearly thereafter. From imaging information of CT, different changes were studied including cross section square of true lumen, false lumen and aortic aneurysm, thrombosis formation of false lumen, modality of endovascular stent-graft, endoleak and visceral blood supply, et al.2. For this study, aortae were divided into four segments SI > S2> S3^ S4. S1 was the stented segment of the aorta, S2 was the segment of the aorta between the distal end of the stent-graft and the ostium of the celiac artery, S3 was the segment of the aorta between the ostium of the celiac artery and the orifice of left renal artery and S4 was the segment of the aorta between the orifice of left renal artery and the aortic bifurcation. Cross sections of the middle of above four segments were regarded as observed cross section. 3D—Doctor was applied to outline the profiles of aortic aneurysm, true lumen and false lumen of four observed cross section, and calculate the square of aortic aneurysm, true lumen and false lumen and then calculate ratio value (R) between true lumen and aortic aneurysm. R reflexes the extent of the compression of the true lumen preoperation and reflexes recovery of true lumen postoperation.3. All patients were grouped according to sex, age, the time from onset to operation, compression of the true lumen, distal tears excluded or not respectively and control of blood pressure after operation. Then repeated ANOVA test was applied to study factors affecting aortic remodeling inaccordance with R value.Results:1. Except early death of seven patients and one patient converted to conventional surgery, all of other patients were followed and the mean follow time was 44 months (range 6-87 months). There were not evident complications such as paraplegia, rupture of aneurysm postoperatively relative to endovascular exclusion.2. Aortic aneurysmal remodeling was evident within 24 months after operation. Because of expansion of endovascular stent-graft, remodeling of the proximal aorta was superior to distal aorta. After 48 months follow up, intimal flaps of the distal end of the endovascular stent-grafts in two patients extruded and formatted aneurymal expansion. And then in one patient endovascular exclusion was achieved again. Extrusion of the proximal end of endovascular stent-graft and migration of endovascular stent-graft were not discoveried and there was no formation of Stanford A type thoracic aortic dissection during follow up too.3. The remodeling of aortae after procedure was affected by age, the time from onset to operation, distal tears excluded or not, the extent of the true lumen's compression, and control of blood pressure post operation, while it was not related with sex. The remodeling of the dissected aortae operated within two month after onset was superior to that operated beyond twomonths. The remodeling of the aortae with distal tears excluded simultaneously was superior to that without distal tears excluded.Conclusion:1. Endovascular stent-graft exclusion is a safe and effective treatment for selected patients with Stanford B type thoracic aortic dissection, and the middle term result of remodeling of dissected aortae is satisfactory. Aortic aneurysmal remodeling was evident within 24 months after operation.2. The remodeling of aortae after procedure was affected by age, the time from onset to operation, distal tears excluded or not, the extent of the true lumen's compression, and control of blood pressure post operation, while it was not related with sex. Early operation after formation of aortic dissection would help to remodeling of aneurysm, and with the improvement of stent-grafts, endovascular exclusion would inevitably find a wider application in treatment of TAD and improve the remodeling of aortae.