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Purpose Retrograde type A aortic dissection (RTAD) represents a serious complication of endovascular treatment for type B aortic dissection (TBAD). To avoid RTAD, it is recommended to land the proximal end of the stent graft in a non-dissected aortic segment. In this study, we investigated whether landing in the dissection area increased the number of events at the proximal site. Methods We conducted a retrospective review of endovascular treatments for TBAD at a single institution between 2009 and 2022. Patients were divided into two groups: group A, with a proximal landing zone entirely within the dissected area, and group B, with the proximal extent of the seal zone in the non-dissected area. We evaluated the occurrence of proximal events, including RTAD, and examined long-term outcomes to assess the validity of landing in the dissection area. Results The study included eighty-nine patients who underwent endovascular treatment for TBAD. New intimal tears in the proximal landing site occurred in 3 cases (3.4%), with 1 case (2%) in group A and 2 cases (5.1%) in group B, showing no significant difference. Among the three cases, one (1.1%) in group B with zone 2 landing resulted in RTAD. At 60 months, the overall survival was 85%, and freedom from aorta-related mortality was 88%, with no significant difference between the groups. Conclusion Even if the proximal landing is in a dissected area, a treatment strategy performed in zone 3 without proximal landing in zone 2, seeking a non-dissected area, can still provide sufficient therapeutic effects. Level of Evidence 3 Retrospective single-center cohort analysis. Graphical Abstract

This issue of the ( ) focuses on Big Data and precision analytics in medical research. At the Aortic Institute at Yale New Haven Hospital, the vast majority of our investigations have emanated from our large, prospective clinical database of patients with thoracic aortic aneurysm (TAA), supplemented by ultra-large genetic sequencing files. Among the fundamental clinical and scientific discoveries enabled by application of advanced statistical and artificial intelligence techniques on these clinical and genetic databases are the following: . 1. Ascending aortic aneurysms should be resected at 5 cm to prevent dissection and rupture. 2. Indexing aortic size to height improves aortic risk prognostication. 3. Aortic root dilatation is more malignant than mid-ascending aortic dilatation. 4. Ascending aortic aneurysm patients with bicuspid aortic valves do not carry the poorer prognosis previously postulated. 5. The descending and thoracoabdominal aorta are capable of rupture without dissection. 6. Female patients with TAA do more poorly than male patients. 7. Ascending aortic length is even better than aortic diameter at predicting dissection. 8. A \"silver lining\" of TAA disease is the profound, lifelong protection from atherosclerosis. : 1. Machine learning models for TAA: outperforming traditional anatomic criteria. 2. Genetic testing for TAA and dissection and discovery of novel causative genes. 3. Phenotypic genetic characterization by Artificial Intelligence. 4. Panel of RNAs \"detects\" TAA. Such findings, based on (a) long-standing application of advanced conventional statistical analysis to large clinical data sets, and (b) recent application of advanced machine learning/artificial intelligence to large genetic data sets at the Yale Aortic Institute have advanced the diagnosis and medical and surgical treatment of TAA.

The optimal cannulation strategy for patients with acute type A aortic dissections (ATAAD) is unclear. A systematic search was performed to identify all studies comparing aortic and non-aortic cannulation in patients undergoing ATAAD repair. The primary endpoint was overall survival. The secondary endpoints were operative mortality, postoperative stroke, renal failure, renal replacement therapy, paraplegia, and mesenteric ischemia. Pooled meta-analyses with aggregated and reconstructed time-to-event data were performed. Twenty-three studies were included (aortic: 3904; non-aortic: 10,719). Ten-year overall survival was 61.1 ​% and 58.4 ​% for aortic and non-aortic cannulation, respectively (HR 1.07; 95 ​% CI 0.92–1.25; p ​= ​0.38). No statistically significant difference was observed for operative mortality (p ​= ​0.10), stroke (p ​= ​0.89), renal failure (p ​= ​0.83), or renal replacement therapy (p ​= ​0.77). Patients undergoing surgery for ATAAD can undergo aortic cannulation with similar outcomes to those who undergo non-aortic cannulation. •Aortic cannulation is safe in patients undergoing surgery for acute type A aortic dissection (ATAAD).•Overall and operative mortality favor aortic cannulation in ATAAD, though this difference was not statistically significant.•In patients undergoing aortic cannulation for ATAAD repair, female gender was associated with operative mortality.

Despite guideline recommendations, transfer rates to high-volume aortic centers (high-VACs) for acute type A aortic dissections (TAAD) remain suboptimal. This may be because the benefit of undergoing surgical repair of TAAD at high-VACs remains poorly quantified. Medicare beneficiaries undergoing surgical repair of TAAD from 1999-2019 were identified. Hospital and surgeon annual aortic case volumes in Medicare beneficiaries were determined. Long-term survival after surgical repair of TAAD at low-volume aortic centers (low-VACs; <6 annual aortic cases), intermediate-volume aortic centers (intermediate-VACs; 6-27 annual aortic cases), and high-VACs (>27 annual aortic cases) was compared. Overlap propensity score weighting adjusted for measured confounding variables. 15,375 Medicare beneficiaries underwent surgical repair of TAAD from 1999-2019: 4119 (26.8%) at low-VACs, 7193 (46.8%) at intermediate-VACs, and 4063 (26.4%) at high-VACs. Over the study duration, the percentage of patients transferred from an outside medical facility for TAAD increased from 33% in 1999 to 50% in 2019 (Cochran-Armitage p<0.001). Transferred patients comprised 19% of cases performed at low-VACs, 43% at intermediate-VACs, and 64% at high-VACs. Risk-adjusted median survival at high-VACs was 6.6[6.3-7.1] years compared to 4.1[3.6-4.6] years at low-VACs, an advantage of 2.5[1.8-3.0] years. Risk-adjusted median survival at high-VACs was 6.7[6.4-7.1] years compared to 5.2[4.9-5.5] years at intermediate-VACs, an advantage of 1.5[0.9-1.9] years. Survival after surgical repair of TAAD is substantially improved at high-VACs compared to both low-VACs and intermediate-VACs. Although the prevalence of transfer for TAAD has increased since 1999, policy measures aimed at improving transfer rates have the potential to further enhance outcomes in TAAD.

Acute aortic syndromes comprise a group of potentially fatal conditions that result from weakening of the aortic vessel wall. Pre-emptive surgical intervention is currently reserved for patients with severe aortic dilatation, although abundant evidence describes the occurrence of dissection and rupture in aortas with diameters below surgical thresholds. Modern imaging techniques (such as hybrid PET-CT and 4D flow MRI) afford the non-invasive assessment of anatomic, hemodynamic, and molecular features of the aorta, and may provide for a more accurate selection of patients who will benefit from preventative surgical intervention. In the current review, we summarize evidence and considerations regarding predictive aortic imaging and highlight evolving imaging modalities that have shown promise to improve risk assessment for the occurrence of dissection and rupture.Key Points• Guidelines for the preventative management of aortic disease depend on maximal vessel diameters, while these have shown to be poor predictors for the occurrence of catastrophic acute aortic events.• Evolving imaging modalities (such as 4D flow MRI and hybrid PET-CT) afford a more comprehensive insight into anatomic, hemodynamic, and molecular features of the aorta and have shown promise to detect vessel wall instability at an early stage.

Few studies have explored the impact of different primary entry tear sites in acute type A aortic dissection. We aimed to evaluate the effect of the primary entry tear location on presentation, treatment, and outcome in this condition. We retrospectively reviewed acute type A aortic dissection repair surgical records at our institution (2004 and 2020) ( n  = 213). The patients were classified into the ascending aorta entry (As-E), aortic arch entry (Ar-E), and descending thoracic aorta or downstream entry (Dd-E) groups. The As-E group was the oldest ( P  < 0.01) and included the fewest males ( P  < 0.01). Pre-operative neurological complication rates were highest in As-E, 16%; Ar-E, 5%; and Dd-E, 0% ( P  = 0.03). Malperfusion syndrome rates were as follows: As-E, 10%; Ar-E, 2%; and Dd-E, 0% ( P  = 0.05). As-E was associated with the highest in-hospital mortality (As-E, 13%; Ar-E, 8%; Dd-E, 0%; P  = 0.27). In-hospital mortality risk factors included pre-operative neurological complications, malperfusion syndrome, and concomitant procedures. Subanalysis revealed that ascending aortic entry was an independent risk factor for pre-operative acute neurological complications. The primary entry site may indirectly affect outcomes, by mediating the risks of pre-operative complications, which are linked to mortality.

Mechanical characteristics of both the healthy ascending aorta and acute type A aortic dissection were investigated using in vitro biaxial tensile tests, in vivo measurements via transoesophageal echocardiography and histological characterisations. This combination of analysis at tissular, structural and microstructural levels highlighted the following: (i) a linear mechanical response for the dissected intimomedial flap and, conversely, nonlinear behaviour for both healthy and dissected ascending aorta; all showed anisotropy; (ii) a stiffer mechanical response in the longitudinal than in the circumferential direction for the healthy ascending aorta, consistent with the histological quantification of collagen and elastin fibre density; (iii) a link between dissection and ascending aorta stiffening, as revealed by biaxial tensile tests. This result was corroborated by in vivo measurements with stiffness index, β, and Peterson modulus, Ep, higher for patients with dissection than for control patients. It was consistent with histological analysis on dissected samples showing elastin fibre dislocations, reduced elastin density and increased collagen density. To our knowledge, this is the first study to report biaxial tensile tests on the dissected intimomedial flap and in vivo stiffness measurements of acute type A dissection in humans.

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.

Type A Aortic Dissection (TAAD) is a surgical emergency with a time-dependent rate of mortality. We hypothesized that a direct-to-operating room (DOR) transfer program for patients with TAAD would reduce time to intervention. A DOR program was started at an urban tertiary care hospital in February 2020. We performed a retrospective study of adult patients undergoing treatment for TAAD before (n = 42) and after (n = 84) implementation of DOR. Expected mortality was calculated using the International Registry of Acute Aortic Dissection risk prediction model. Median time from acceptance of transfer from emergency physician to operating room arrival was 1.37 h (82 min) faster in DOR compared to pre-DOR (1.93 h vs 3.30 h, p < 0.001). Median time from arrival to operating room was 1.14 h (72 min) faster after DOR compared to pre-DOR (0.17 h vs 1.31 h, p < 0.001). In-hospital mortality was 16.2% in pre-DOR, with an observed-to-expected (O/E) ratio of 1.03 (p = 0.24) and 12.0% in the DOR group, with an O/E ratio of 0.59 (p < 0.001). Creation of a DOR program resulted in decreased time to intervention. This was associated with a decrease in observed-to-expected operative mortality. The transfer of patients with acute type A aortic dissection to centers with direct-to-OR programs may result in decreased time from diagnosis to surgery.

Thoracic aortic dissections involving the ascending aorta represent one of the most dramatic and lethal emergencies in cardiovascular surgery. It is therefore critical to identify the mechanisms driving them and biomechanical analyses hold great clinical promise, since rupture/dissection occur when aortic wall strength is unable to withstand hemodynamic stresses. Although several studies have been done on the biomechanical properties of thoracic aortic aneurysms, few data are available about thoracic aortic dissections. Detailed mechanical tests with measurement of tissue thickness and failure properties were performed with a tensile-testing device on 445 standardized specimens, corresponding to 19 measurement sites per inner (intima with most of media)/outer layer (leftover media with adventitia); harvested from twelve patients undergoing emergent surgical repair for type A dissection. Our data suggested inherent differences in tissue properties between the origin of dissection and distal locations, i.e. thinner and stiffer inner layers that might render them more vulnerable to tearing despite their increased strength. The strength of tissue circumferentially was greater than that longitudinally, likely determining the direction of tear. The relative strengths of the inner: ∼{65,40}N/cm2 and outer layer: ∼{350,270}N/cm2 in the two principal directions of dissected tissue were differentiated from the intima: ∼{100,75}N/cm2, media: ∼{150,55}N/cm2, and adventitia: ∼{270,190}N/cm2 of non-dissected ascending aortic aneurysms (Sokolis et al., 2012), in favor of weaker inner and stronger outer layers, allowing an explanation as to why the presently-studied tissue suffered dissection, i.e. tear of the inner layers, and not rupture, i.e. full tearing across the entire wall thickness.