The Analysis And Research Of Risk Factors For Distal Aortic Enlargement After 1-stage Surgical Treatment Of Aortic Dissection

BACKGROUND Patients with successful initial treatment of both Stanford type A and type B aortic dissection(AD)by treating the proximal entry tear and placing stent-graft in descending aorta has shown unsatisfactory long-term outcomes,with almost one third of patients developing aortic enlargement in the remaining dissected aorta following the initial repair,and up to nearly 30%-62.5% of patients require re-intervention to the distal aorta in the following 5 to 10 years.Many patients with AD have persistent flow to the false lumen(FL)after 1-stage repair through small intimal tears in the uncovered portion of the aorta distal to the stent graft,however,remains at risk of continuous enlargement.Previous studies have indicated that persistent patency FL is strongly associated with poor prognosis because the persistent filling in the FL maintains pressurization of the thin,weak FL wall causing aortic enlargement and potentially aortic rupture,necessitating re-intervention.However,many patients with distal intimal tears after 1-stage repair remained stable.Therefore,analyzing the risk factors for late aortic enlargement in the long-term would be beneficial in identifying patients who need further interventions.OBJECTIVE To analyze the growth rate of remaining affected distal segmental aorta,the clinical and radiological factors influencing its enlargement,and to investigate the association between the morphologic changes of distal tears and remaining aortic dissection remodeling following 1-stage repair of extensive aortic dissection.MATERIALS & METHODS 1)A systematic review: Retrograde review of the literature concentrated on aortic remodeling after 1-stage repair was performed.The type of aortic morphology measurements made and the methods used to make them were characterized.Nineteen articles were met the inclusion criteria,but only 3 used three-dimensional reconstruction software.True lumen,and false lumen diameters,areas and in some cases volumes were measured.2)Distal segmental aortic enlargement(DSAE)patients treated with surgical or endovascular repair which only covered the proximal entry tear and had stent-graft placement in the descending aorta were evaluated.Those with a computed tomography angiography(CTA)obtained preoperatively,postoperatively and at least after 6-month of follow-up before their second treatment were included(1999-2014)for analysis.Morphological characteristics were analyzed using Tera Recon Vascular workstation(Aquarius i Ntuition Edtion,Tera Recon,Foster City,California).Logistic regression analyses were used to investigate the risk factors for distal segmental aortic enlargement.3)Analyze the treatment methods of distal tears: Summarize the limitations of current treatment methods and their limitations.Review the results of therapy for DSAE patients after 1-stage repair of AD.Based on the risk factors and the limitations of each therapy,to guide surgeons pay closer attention on these patients,and make a better suggestion for these patients in the operative timing and method of treatment.RESULTS 1)Studies assessed the aorta at a variety of different levels and over different periods of follow-up,so statistical analysis can't be reached.Acute dissection patients displayed more consistent degree(thoracic aortic thrombosis of the false lumen in 80% to 90%)of remodeling than in patients with chronic widespread(38% to 91%).Less remodeling was showed below the diaphragm in all patients.2)Included were 964 patients(129 DSAE patients,833 non-DSAE patients)with a mean age 52.46±12.87 years.The mortality of DSAE after 1-stage repair was 13.41%.In these patients,there are 419 patients analyzed their morphological characteristics(75 DSAE patients,344 non-DSAE patients).The mean duration of follow-up was 6.33 years(range 1.5 to 17 years).Of all postoperative patients,99.76% remained distal tears,and 79.97% of them remained more than 3 tears.There are 58.1% of the patients without any tears in the N2-area,while 23.6% without any tears in the V3-area.The shape of tears is mostly spindle(72.0%).Compared with non-DSAE patients,the diameter of aorta increased more in the DSAE patients.And in the DSAE patients,it increased mainly form the false lumen;however,it increased mainly from true lumen in the non-DSAE patients.Patients with factors below seemed to be more likely to have aortic enlargement during the follow-up: younger(DSAE group 49.0 ± 12.9 years VS non-DSAE group 53.0 ± 12.7years),Marfan's syndrome(DSAE VS non-DSAE:22,17.2% VS 24,2.9%),history of other surgery(DSAE VS non-DSAE:7,5.5% VS 14,1.7%),history of endovascular surgery(DSAE VS non-DSAE:3,2.4% VS 1,0.1%),history of alcohol intake(DSAE VS non-DSAE:7,5.5% VS 19,2.3%)?lower systolic blood pressure/diastolic blood pressure(DSAE 131.4 ± 20.7 mm Hg/75.5 ± 15.7 mm Hg VS non-DSAE 140.5 ± 23.5 mm Hg / 79.9 ± 17.1 mm Hg),another stent for treating intra-operative endoleak(DSAE 20,16.0% VS non-DSAE 71,8.8%),shorter length of stent-graft covered descending aorta(DSAE 118.5 ± 30.5 mm VS non-DSAE 140.0 ± 33.6mm),longer length of remaining dissection(DSAE 440.2±75.7mm VS non-DSAE 366.4±91.9mm),short length of thrombosis of false lumen(DSAE 102.6 ± 58.5mm VS non-DSAE 141.2 ± 94.2 mm),longer length of continuous false lumen patency(DSAEVS non-DSAE:338.0 ± 104.8mm VS 255.2 ± 98.1mm),closer distance of the first intimal tear after surgical repair(DSAE 19.16 ± 6.61 cm VS non-DSAE 28.02 ± 8.30cm),more tears in the N2-area(DSAE 2.0 ± 2.2 VS non-DSAE 0.9 ± 1.3),less tears in the N3-area(DSAE 1.1 ± 1.0 VS non-DSAE 2.6 ± 1.4),large tear(short diameter?5.0mm),longer length of maximum distance between two tears(DSAE 11.281 ± 6.265 cm VS non-DSAE 8.745 ± 4.553cm)and larger rotation degree of false lumen(DSAE 204.3°± 135.1° VS non-DSAE 145.1°±82.2°),etc.After multi regress equations for post-operative tears were achieved by multi linearity regress mechanic,significant independent risk factors were verified.For post-operative tears,as compared with the average distance among tears,long diameter of tears,numbers of large tear,and spindle tears,factors as more tears in the N2 area,less tears in the N3 area,closer distance of the first intimal tear,larger of the short diameter of the first tear,longer length of maximum distance between two tears and the maximum of the short diameter among all tears are significant independent risk factors of postdischarge DSAE in these patients.3)There are many methods for remaining distal tears,but no one is perfect.34 cases of DSAE patients were treated,endoleak rate after treatment was 14/34(41.2%),the continued expansion rate is 7/14(50%),and mortality after endovascular repair is 4/34(11.8%).Thus,the current treatments for distal tears in post-operative patients are ineffective.CONCLUSIONS 1)Factors such as length of aortic coverage,and timing of treatment may explain the variation displayed in the chronic aortic dissection patients.Consensus-based reporting standards are required to synthesize evidence for assessing,and inform clinical decisions regarding patient selection and operative timing.2)Younger,Marfan's syndrome,history of endovascular surgery,history of other surgery,history of alcohol intake?lower systolic blood pressure/diastolic blood pressure,another stent for treating intra-operative endoleak,shorter length of stent-graft covered descending aorta,closer distance of the first intimal tear,less tears in the N3-area,longer length of remaining dissection,short length of thrombosis of false lumen,continuous false lumen patency after repair and larger rotation angle of false lumen appear to predict aortic enlargement in DSAE patients after 1-stage repair covering to the proximal tear in the descending aorta during follow-up.More tears in the N2-area,fewer tears in the N3-area,closer distance of the first intimal tear,larger of the short diameter of the first tear,longer length of maximum distance between two tears and the maximum of the short diameter among all tears are significant independent risk factors of postdischarge DSAE in these patients.Patients with these morphologic characteristics may require a more extensive repair and more intensive follow-up to prevent long-term complications.3)The results of secondary repair for DSAE patients were poor.For AD patients with remaining distal tears should be further researched,patients with risk factors in DSAE should be careful for surgical indications.A prognostic score and better treatment are needed.An effective treatment method for AD patients is urgent.