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Aortic dissection often initiates a few centimeters distal to the coronary ostia in the right lateral wall, with an intimal-medial tear that tends to be transversely directed and occupy half of the aortic circumference, sometimes less, but seldom the entire circumference. To elucidate these clinical observations, tear tests were presently used to determine the layer-specific resistance to tear propagation in ascending thoracic aortic aneurysms, assessing variations over the four circumferential quadrants and two directions. Aneurysmal tissue strips of standardized dimensions from sixteen patients were anatomically separated into layers (seven hundred and twelve) and an incision made along one-third of their length. They underwent tear testing via uniaxial loading and then unloading before crack propagation had proceeded along their complete length. The average tear tension and tear energy per reference area generated were many-fold greater in outer- (adventitial) compared to inner- (intimal with small medial portion) and middle-layer (medial) strips, explaining why the tear is restricted to the inner wall. They were greater in inner- compared to middle-layer strips of the anterior and left lateral quadrants, suggesting that the tear will propagate to the less-resistant media even if initiated in the intima. In most longitudinally-cut middle- and inner-layer strips, the cracks deviated toward the circumferential direction and tore out through the side, justifying the circumferential course of the tear. Both fracture parameters were significantly higher in the right than the left lateral quadrant in outer-layer strips and the anterior quadrant in middle-layer strips, potentially affecting the circumferential extent of the tear.

Aortic dissection (AD) is one of the most catastrophic cardiovascular diseases. AD occurs when a layer inside the aorta is disrupted and gives rise to the formation of a true lumen and a false lumen. These lumens can be connected through tears in the intimal flap which are known as entries. Despite being known for about two centuries, the effects of many factors on the morbidity and mortality of this disease are still unknown. As the blood interaction with the aorta is crucial in the severity and the progression of the aortic dissection, a biomechanical approach is chosen to investigate the influence of different morphologies on the severity of this disease. Using the finite element method (FEM) and the fluid–structure interaction (FSI) approach, we have evaluated the blood flow characteristics along the diseased aorta, in conjunction with the deformation of the aortic wall. In this study, an idealized geometry of a dissected descending aorta (type B) with two entries has been studied. The values for the diameter of the entry tear were chosen to be 5 mm and 10 mm. Therefore, a total of four conditions were investigated. According to our results, the retrograde flow through the proximal tear is dependent on the size of the distal re-entry and vice versa. Our results revealed that when both entry and re-entry tears are 10 mm in diameter, the flow passes through the true and false lumens with smaller resistance, resulting in a smaller flutter of the intimal flap, and therefore more stable intimal flap. Major oscillation frequencies of 2.5 Hz and 7.4 Hz were observed for the oscillation of the intimal flap, and amplitudes of the waves with higher frequencies were negligible.

Uncomplicated acute type B aortic dissections are usually treated medically, but they can become acutely complicated by rapid expansion, rupture and malperfusion syndromes and in the longer term by chronic dilatation and aortic aneurysm formation. The objective of this study is to use computational fluid dynamics reconstructions of type B aortic dissections to compare geometric and haemodynamic factors between the cases selected for medical treatment and the cases selected for thoracic endovascular aortic repair (TEVAR), and to examine whether any of these factors are associated with the outcome of the medically treated group. This study includes eight type B dissection cases, with four in each group. Aortic flow analyses were carried out based on patient-specific anatomy at initial presentation before treatment. Comparisons between the two groups show that the false lumen to true lumen volume ratio is considerably higher in patients selected for TEVAR. Results from the four medically treated cases indicate that the size of the primary entry tear is the key determinant of the false lumen flow rate, which may influence the long-term outcome of medically treated patients. Potential relations between flow related parameters based on initial anatomy and subsequent anatomical changes in the medically treatment group were examined. Our initial findings based on the limited cases are that high relative residence time is a strong predictor of subsequent false lumen thrombosis, whereas pressure difference between the true and false lumen as well as the location of the largest pressure difference may be associated with the likelihood of subsequent aortic expansion.

To evaluate the efficacy of endovascular circulating false lumen occlusion (CFLO) in inducing positive aortic remodeling in chronic aneurysmal descending aortic dissection (AD). This retrospective monocentric study included patients treated by CFLO between 2003 and 2022 in the context of chronic AD with progressive descending aneurysmal evolution and persistent circulating false lumen (FL). The procedure was achieved with coils, plugs, and/or glue at the entry tear or in the FL and/or with covered stenting in the supra-aortic trunk. The primary endpoint evaluated the positive aortic remodeling, defined as stabilization or a decrease in the aortic diameter on a computed tomography scan at the 1-year follow-up after the procedure. The FL circulating status, safety, and occurrence of aneurysm events during follow-up were also evaluated. Twenty patients [median age: 65.4 years, interquartile range (IQR): 58.4–69.9; 13 men] were included, with a median duration from an acute AD of 32.5 months (IQR: 8.8–76.5). Twelve patients (60%) achieved complete FL thrombosis after CFLO, whereas 8/20 patients (40.0%) experienced partial thrombosis. Additionally, positive aortic remodeling was observed in 13 patients (65%). Following the procedure, the aneurysmal aortic diameter decreased in 8/20 patients (40.0%) and remained stable in 5/20 patients (25.0%). Two patients (10%) had complications related to the procedure. Two patients (10%) had secondary aneurysm events during follow-up. CFLO is a feasible and efficient method to induce FL thrombosis and reduce aneurysmal progression in chronic AD. The positive outcomes observed highlight the potential of this technique to improve patient management in complex aortic pathologies. This approach offers a valuable option in the management of chronic AD and emphasizes the importance of endovascular interventions in enhancing patient outcomes.

OBJECTIVES Acute aortic dissection leads to the destabilization of the aortic wall, followed by an immediate increase in aortic diameter. It remains unclear how the aortic diameter changes during the dissection’s acute and subacute phases. The aim of this study was to evaluate the change in aortic geometry within 30 days after the onset of a descending aortic dissection. METHODS Patients with acute type B and non-A non-B dissection who had at least 2 computed tomography angiography scans obtained within 30 days after the onset of dissection were evaluated. Exclusion criteria were a thrombosed false lumen, connective tissue disorders and endovascular or open aortic repair performed prior to the second computed tomography angiography. RESULTS Among 190 patients with acute aortic dissection, 42 patients met our inclusion criteria. Their aortic geometry was analysed according to the computed tomography angiography scans obtained between 0–3 (N = 35), 4–7 (N = 9) and 8–30 (N = 12) days after the dissection onset. The highest aortic diameter growth rate was observed in the first quartile of the thoracic aorta and measured 0.66 (0.06; 1.03), 0.29 (−0.01; 0.41) and 0.06 (−0.13; 0.26) mm/day at 0–3, 4–7 and 8–30 days after the dissection, respectively. Proximal entry location (P = 0.037) and entry located at the arch concavity (P = 0.008) were associated with a higher aortic diameter increase. CONCLUSIONS Early rapid growth occurs during the first week after the descending aortic dissection—most intensely over the first 3 days, and this is associated with the location of the dissection’s entry.

Thoracic endovascular aortic repair (TEVAR) is a common treatment for Stanford type B aortic dissection (TBAD). However, re-entry tears might be found distal to the stented region which transports blood between the true and false lumens. Sealing the re-entry tears, especially for the thoracic tears, could further reduce blood perfusion to the false lumen; however, it might also bring risks by re-intervention or surgery. Wise determination of the necessity to seal the re-entry tears is needed. In this study, patient-specific models of TBAD were reconstructed, and the modified models were established by virtually excluding the thoracic re-entries. Computational hemodynamics was investigated, and the variation of the functional index and first balance position (FBP) of the luminal pressure difference, due to the sealing of the re-entries, was reported. The results showed that the direction of the net flow through the unstented thoracic re-entries varied among cases. Excluding the re-entries with the net flow toward the false lumen may induce the FBP moving distally and the relative particle residence time increasing in the false lumen. This study preliminarily demonstrated that the hemodynamic status of the re-entry tears might serve as an indicator to the necessity of sealing. By quantifying the through-tear flow exchange and shift of FBP, one can predict the hemodynamic benefit by sealing the thoracic re-entries and thus wisely determine the necessity of further interventional management.

This study aimed to examine the hemodynamic modifications in uncomplicated type B aortic dissection in relation to the location of re-entry tears using a computational fluid dynamics simulation. The geometry of uncomplicated type B aortic dissection was reconstructed using computed tomography images. Subsequently, 10 virtual models were artificially generated with re-entry tears at various locations. The simulation results indicated that most models with re-entry tears had lower pressure and wall shear stress than those without re-entry tears. The overall pressure distribution of the true lumen was greater than that of the models without re-entry tears when the re-entry tear was placed at the end of the false lumen. Furthermore, the recirculation phenomenon in the false lumen was reduced as the re-entry tear was relocated to the distal region of the aorta. To determine whether and how to perform fenestration surgery in patients with uncomplicated type B aortic dissection, these computational results can be used as supplemental indicators. However, further validation in a larger number of patients through additional investigation is necessary.

(1) Background: This study aimed to morphologically analyze acute type A aortic dissection (aTAAD) patients for potential endovascular treatment candidates. The objective was to specify requirements for aTAAD endovascular devices. (2) Methods: A single-center retrospective analysis included aTAAD patients who underwent open surgical repair between November 2005 and December 2020. Preoperative CTA scans were used for morphological analysis, assessing endovascular repair eligibility. Statistical tests were performed. (3) Results: A total of 129 patients with aTAAD were studied, with 119 included. Entry tear (ET) locations were identified, mainly in the aortic root, 20 mm above the sinotubular junction (STJ) and within the ascending aorta (20 mm above STJ to −20 mm before the brachiocephalic trunk). Endovascular treatment was deemed feasible for 36 patients, with suggested solutions for the aortic arch and descending aorta. Significant differences were observed between eligible and noneligible groups for aortic diameter, false lumen diameter, distance between STJ and entry tear, and more. Dissection extension showed no significant difference. (4) Conclusions: Morphological analysis identified potential aTAAD candidates for endovascular treatment, highlighting differences between eligible and noneligible morphologies. This study offers insights for implementing endovascular approaches in aTAAD treatment and emphasizes the need for research and standardized protocols.

Objective The purpose of this study was to determine the clinical outcomes of thoracic endovascular aortic repair in 8 patients with acute type A aortic dissection with an entry tear in the descending aorta. Subjects and methods From January 2016 to December 2018, eight patients (mean age 76 years; range 54–92 years) were treated by thoracic endovascular aortic repair due to high operative risk for conventional open repair. All patients had significant comorbidities, and two had critical organ malperfusion due to aortic dissection. Surgical outcomes were retrospectively reviewed. Results All procedures were technically successful with complete coverage of the entry tear. The proximal landing zone was Zone 1 in 2, Zone 2 in 1, Zone 3 in 4, and Zone 4 in 1 patient. Patients requiring Zone 1 and 2 thoracic endovascular aortic repair underwent aortic arch bypass simultaneously. Mean operation time was 132 min. There were no hospital deaths and no serious complications, including stroke and spinal cord ischemic injury. All patients had complete thrombosis and shrinkage of the false lumen in the ascending aorta before discharge. During up to 36-month follow-up (mean 20 ± 12 months), there were no adverse aortic events except one who died due to ischemic colitis 4 months after the procedure. Conclusion Thoracic endovascular aortic repair could be a useful alternative surgical option for patients with retrograde acute type A aortic dissection with an entry in the descending aorta who are not suitable for conventional open surgery. Careful follow-up of such patients is mandatory.