Predictors of aortic growth in uncomplicated type B aortic dissection from the Acute Dissection Stent Grafting or Best Medical Treatment (ADSORB) database

Background: The high-risk patient cohort of uncomplicated type B aortic dissections (uTBADs) needs to be clarified. We compared uTBAD patients treated with best medical treatment (BMT), with and without aortic growth, from the Acute Dissection Stent Grafting or Best Medical Treatment (ADSORB) trial database. Furthermore, we looked for trends in outcome for aortic growth and remodeling after BMT and thoracic endovascular aortic repair (TEVAR) and BMT (TEVAR+BMT). Methods: BMT patients with available baseline and a 1-year follow-up arterial computed tomography scan were identified. True lumen and false lumen diameter was assessed at baseline and at follow-up. Patients with false lumen growth (group I) and without false lumen growth (group II) were compared. Predictors of false lumen and total lumen (aortic) growth were identified. Lastly, BMT outcomes were compared with BMT+TEVAR for false lumen thrombosis and change in false lumen and total aortic diameter in four sections: 0 to 10 cm (A), 10 to 20 cm (B), 20 to 30 cm (C), and 30 to 40 cm (D) from the left subclavian artery. Results: The dissection was significantly longer in group I than in group II (43.2 +/- 4.9 cm vs 30.4 +/- 8.8 cm; P = .002). The number of vessels originating from the false lumen at baseline was identified as an independent predictor of false lumen growth (odds ratio, 22.1; 95% confidence interval, 1.01-481.5; P = .049). Increasing age was a negative predictor of total aortic diameter growth (odds ratio, 0.902; 95% confidence interval, 0.813-1.00; P = .0502). The proximal sections A and B showed complete thrombosis in 80.6% in the BMT+TEVAR group compared with 9.5% in the BMT group. In these sections, changes from patent to partial or partial to complete thrombosis were observed in 90.3% of the TEVAR+BMT group vs 31.0% in the BMT group. In sections C and D, the change in thrombosis was 74.1% for the TEVAR+BMT group vs 20.6% for the BMT group. The false lumen diameter increase at section C was larger in the BMT group. Total lumen diameter decreased in sections A and B in the TEVAR+BMT group compared with an increase in the BMT group (-4.8 mm vs +2.9 mm, and -1.5 mm vs +3.8 mm, respectively). Sections C and D showed minimal and comparable expansion in both treatment groups. Conclusions: The new imaging analysis of the ADSORB trial patients identified the number of vessels originating from the false lumen as an independent predictor of false lumen growth in uTBAD patients. Increasing age was a negative predictor of aortic growth. Our analysis may help to identify which uTBAD patients are at higher risk and should receive TEVAR or be monitored closely during follow-up

Standardized Protocol to Analyze Computed Tomography Imaging of Type B Aortic Dissections

Purpose: To propose a standard measuring protocol for type B aortic dissections so as to improve comparability between studies reporting aortic dimensions. Methods: Fifteen computed tomography (CT) scans of type B aortic dissections were measured with a standard protocol by 2 independent observers using postprocessing software. The following parameters were assessed: true, false, and total lumen diameter; true and false lumen volume; and entry tear size, location, and number. Diameters were measured in a perpendicular plane at 2, 10, and 20 cm from the left subclavian artery and 5 cm from the most distal renal artery. True lumen volume was assessed from the left subclavian artery to the aortic bifurcation, while the false lumen volume was from the start to end up to the aortic bifurcation. Entry tear location was assessed in relation to the left subclavian artery. Intra- and interobserver repeatability and agreement were evaluated using the Bland-Altman method, an a priori set of acceptable differences, and Lin’s concordance correlation coefficient (LCCC). Results: Intra- and interobserver mean differences for aortic diameter and true and false lumen volumes were generally within the limits of agreement and the a priori differences; the LCCC showed excellent agreement. Entry tear location, size, and number were difficult to measure in a repeatable manner, with inconsistent correlation coefficients, especially between the 2 observers. Conclusion: This protocol showed acceptable repeatability for aortic diameter and aortic volume measurements. Assessment of entry tears proved challenging and associated with less favorable results. Additionally, investigators are urged to be more transparent regarding the measurement methodology used in studies describing aortic dimensions

A review of follow-up outcomes after elective endovascular repair of degenerative thoracic aortic aneurysms

Long-term outcomes of elective thoracic endovascular aortic repair (TEVAR) for degenerative thoracic aortic aneurysms (TAA) are not well defined. A review of the literature on the follow-up outcomes of elective TEVAR for degenerative TAA resulted in 22 relevant articles. Two- and five-year freedom from aneurysm-related death varied between 93.0% and 100.0%, and 82.4% to 92.7%, respectively. Two-year and five-year all-cause survival ranged between 68.0% and 97.2% and 47.0% to 78.0%, respectively. Follow-up ranged between 17.3 and 66.0 months. Most common endograft-related complication was endoleak, with reported rate between 1.4% and 14.8% during six months up to five years of follow-up. Endovascular reinterventions were reported in 0.0–32.3%, secondary open surgery was needed in 0.0% to 4.7% during follow-up. Aneurysm-related survival rates after elective TEVAR for degenerative TAA are acceptable. However, reported incidences of endograft-related complications vary considerably in the literature, but the majority can be managed with conservative treatment or additional endovascular procedures

A review of follow-up outcomes after elective endovascular repair of degenerative thoracic aortic aneurysms

Long-term outcomes of elective thoracic endovascular aortic repair (TEVAR) for degenerative thoracic aortic aneurysms (TAA) are not well defined. A review of the literature on the follow-up outcomes of elective TEVAR for degenerative TAA resulted in 22 relevant articles. Two- and five-year freedom from aneurysm-related death varied between 93.0% and 100.0%, and 82.4% to 92.7%, respectively. Two-year and five-year all-cause survival ranged between 68.0% and 97.2% and 47.0% to 78.0%, respectively. Follow-up ranged between 17.3 and 66.0 months. Most common endograft-related complication was endoleak, with reported rate between 1.4% and 14.8% during six months up to five years of follow-up. Endovascular reinterventions were reported in 0.0–32.3%, secondary open surgery was needed in 0.0% to 4.7% during follow-up. Aneurysm-related survival rates after elective TEVAR for degenerative TAA are acceptable. However, reported incidences of endograft-related complications vary considerably in the literature, but the majority can be managed with conservative treatment or additional endovascular procedures

Stent-Graft Deployment Increases Aortic Stiffness in an Ex Vivo Porcine Model

Background Aortic stiffness is an independent predictor of cardiovascular mortality. In this study, the effect of thoracic endovascular aortic repair (TEVAR) on aortic stiffness is investigated by measuring aortic pulse wave velocity (PWV) in an ex vivo porcine model. Methods Fifteen fresh porcine thoracic aortas were connected to a benchtop pulsatile system. Intraluminal pressures were recorded in the ascending aorta and at the celiac trunk using a needle connected to a pressure sensor. The distance between the needles was divided by the time difference between the base of the pressure peaks to calculate aortic PWV at baseline and after stent-graft deployment and distal stent-graft extension. Results Mean aortic PWV was 5.0 m/s at baseline. PWV increased by 4% after proximal stent-graft deployment (P = 0.09) and by 18% after stent-graft extension (P < 0.001). Pulse pressure in the nonstented ascending aorta increased by 11.0 ± 1.2 mm Hg after proximal stent-graft deployment (P < 0.001) and by 17.3 ± 1.5 mm Hg after stent-graft extension (P < 0.001). The increases in PWV and pulse pressure showed a positive linear correlation with the percentage of stent-graft coverage (P < 0.001 and P < 0.001). Conclusions In this experimental setup, aortic stiffness increased after stent-graft deployment, dependent on the percentage of the aorta that was covered by stent graft. These results show that TEVAR leads to significant changes in aortic hemodynamics, which merits evaluation in the clinical setting

An experimental investigation of the impact of thoracic endovascular aortic repair on longitudinal strain

OBJECTIVES: To investigate the impact of thoracic endovascular aortic repair (TEVAR) on longitudinal strain and assess aortic tensile properties in order to better understand complications associated with TEVAR. METHODS: Twenty fresh thoracic porcine aortas were harvested and connected to a mock circulatory loop driven by a centrifugal flow pump at body temperature. Length measurements were conducted before and after TEVAR through aortic marking, high-definition imaging and custom-developed software under physiological pressure conditions (i.e. between 100 and 180 mmHg with 20 mmHg increments). Longitudinal strain was derived from length amplitude divided by the baseline length at 100 mmHg. Three groups of stent-graft oversizing were created (0-9, 10-19 and 20-29%). Finally, elastic properties of the aortic samples were assessed in both longitudinal and circumferential directions through uniaxial tensile testing. Longitudinal strain was compared before and after TEVAR, and stress-to-rupture was compared among specimens and locations. RESULTS: TEVAR induced a longitudinal strain decrease from 11.9 to 5.6% (P< 0.001) in the stented segments and a longitudinal strain mismatch between stented (5.6%) and non-stented segments (9.1%, P< 0.001). Stent-graft oversizing did not affect the magnitude of strain reduction (P= 0.77). Tensile testing showed that peak stress-to-rupture was lower for longitudinal (1.4 ± 0.4 MPa) than for circumferential fragments (2.3 ± 0.4 MPa, P< 0.001). In addition, longitudinal fragments were more prone to rupture proximally than distally (P= 0.01). CONCLUSIONS: This experimental study showed that TEVAR acutely stiffens the aorta in the longitudinal direction and thereby induces a strain mismatch, while tensile testing confirmed that longitudinal aortic fragments are most prone to rupture, particularly close to the arch. Such an acute strain mismatch of potentially vulnerable tissue might play a role in TEVAR-related complications, including retrograde dissection and aneurysm formation. The finding that TEVAR stiffens the aorta longitudinally may also shed light on systemic complications following TEVAR, such as hypertension and cardiac remodelling. These observations may imply the need for further improvement of stent-graft designs