Comparison of open thoracoabdominal repair for chronic aortic dissections and aneurysms.

OBJECTIVE: Aortic dissection is common in patients undergoing open surgical repair of thoracoabdominal aortic aneurysms (TAAAs). Most often, dissection is chronic and is associated with progressive aortic dilatation. Because contemporary outcomes in chronic dissection are not clearly understood, we compared patient characteristics and outcomes after open TAAA repair between patients with chronic dissection and those with non-dissection aneurysm. METHODS: We retrospectively analyzed data from 3470 open TAAA repairs performed in a single practice. Operations were for non-dissection aneurysm in 2351 (67.8%) and chronic dissection in 1119 (32.2%). Outcomes included operative mortality and adverse events, a composite variable comprising operative death and persistent (present at discharge) stroke, paraplegia, paraparesis, and renal failure necessitating dialysis. Logistic regression identified predictors of operative mortality and adverse events. Time-to-event analyses examined survival, death, repair failure, subsequent progressive repair, and survival free of failure or subsequent repair. RESULTS: Compared with patients with non-dissection aneurysm, those with chronic dissection were younger, had fewer atherosclerotic risk factors, and were more likely to have heritable thoracic aortic disease and undergo extent II repair. The operative mortality rate was 8.5% (n = 296) overall and was higher in non-dissection aneurysm patients (n = 217; 9.2%) than in chronic dissection patients (n = 79; 7.1%; P = .03). Adverse events were less frequent (P = .01) in patients with chronic dissection (n = 145; 13.0%), 22 (2.0%) of whom had persistent paraplegia. Chronic dissection was not predictive of operative mortality (P = .5) or adverse events (P = .6). Operative mortality and adverse events, respectively, were independently predicted by emergency repair (odds ratio [OR], 3.46 and 2.87), chronic kidney disease (OR, 1.74 and 1.81), extent II TAAA repair (OR, 1.44 and 1.73), increasing age (OR, 1.04/year and 1.04/year), and increasing aortic cross-clamp time (OR, 1.02/minutes and 1.02/minutes). Patients with chronic dissection had lower 10-year unadjusted mortality (42% vs 69%) but more frequent repair failure (5% vs 3%) and subsequent repair for progressive aortic disease (11% vs 5%) than patients with non-dissection aneurysm (P < .001); these differences were no longer statistically significant after adjustment. CONCLUSIONS: Outcomes of open TAAA repair vary by aortic disease type. Emergency repairs and atherosclerotic diseases most commonly occur in patients with non-dissection aneurysm and independently predict operative mortality. Repair of chronic dissection is associated with low rates of adverse events, including operative mortality and persistent paraplegia, along with reasonable late survival and good durability. However, patients with chronic dissection tend to more commonly undergo subsequent repair to treat progressive aortic disease, which emphasizes the need for robust long-term imaging surveillance protocols.

Outcomes After Extent I Thoracoabdominal Aortic Repair: Focus on Heritable Aortic Disease.

BACKGROUND: Crawford extent I thoracoabdominal aortic aneurysm (TAAA) repairs are increasingly performed by an endovascular approach, including in patients with heritable thoracic aortic disease (HTAD). We evaluated outcomes after open extent I TAAA repair in patients with and without HTAD. METHODS: This retrospective study included 992 patients (median age, 67 years; quartile 1-quartile 3, 57-73 years) who underwent extent I TAAA (1990-2022), stratified by the presence of HTAD (n = 177 [17.8%]). Patients with HTAD had genetic aortopathies or presented at age ≤50 years, and 35% (62 of 177) had Marfan syndrome. Logistic regression was used to identify predictors of operative death and adverse event, a composite of operative death and persistent (present at discharge) stroke, paraplegia, paraparesis, and renal failure necessitating dialysis. Long-term outcomes were analyzed with competing risks analysis. RESULTS: Patients with HTAD had lower rates of operative mortality (1.7% vs 7.0%, P = .01) and composite adverse event (2.8% vs 12.3%, P < .001) than non-HTAD patients. Most HTAD patients were discharged home (92.6% vs 76.9%, P < .001). Predictors of operative death were increasing age, aortic dissection, tobacco use, chronic symptoms, and rupture. Predictors for adverse event were increasing age, acute symptoms, chronic dissection, and rupture. Patients with HTAD had substantially better repair-failure-free survival (P < .001). CONCLUSIONS: Open extent I TAAA repair was effective in patients with HTAD, with low operative mortality and adverse event rates, better late survival, and excellent long-term durability, making a compelling argument for preferring open repair in these patients.

The severity of chronic obstructive pulmonary disease is associated with adverse outcomes after open thoracoabdominal aortic aneurysm repair.

OBJECTIVE: We assessed associations between outcomes after open thoracoabdominal aortic aneurysm (TAAA) repair and preoperative airflow limitation stratified by the Global Initiative for Chronic Obstructive Lung Disease (GOLD) spirometric classification of chronic obstructive pulmonary disease (COPD) severity. METHODS: Among 2368 open elective TAAA repairs in patients with spirometric data, 1735 patients had COPD and 633 did not. Those with COPD were stratified by preoperative respiratory dysfunction as GOLD 1 (forced expiratory volume in the first second of expiration [FEV1] ≥80% of predicted; n = 228), GOLD 2 (50% ≤ FEV1 < 80% of predicted; n = 1215), GOLD 3 (30% ≤ FEV1 < 50% of predicted; n = 260), or GOLD 4 (FEV1 < 30% of predicted; n = 32). Early outcomes included operative mortality and adverse events (operative death or persistent stroke, spinal cord deficit, or renal failure requiring dialysis); associations of outcomes were determined using logistic regression models. Kaplan-Meier analysis compared late survival by the log-rank test. RESULTS: Pulmonary complications occurred in 38.4% of patients with COPD versus 30.0% without COPD (P < .001). Operative mortality and adverse events were more frequent in patients with COPD than without COPD (7.9% vs 3.8% [P < .001] and 14.9% vs 9.8% [P = .001], respectively). Worsening GOLD severity was independently associated with operative death and adverse event. Survival was poorer in patients with COPD than in those without (61.9% ± 1.2% vs 73.6% ± 1.8% at 5 years; P < .001), particularly in patients with increasing GOLD severity (68.7% ± 3.2% vs 63.7% ± 1.4% vs 51.4% ± 3.2% vs 31.3% ± 8.2% at 5 years; P < .001). CONCLUSIONS: Patients with COPD are at elevated risk for operative death and adverse events. Staging by GOLD severity aids preoperative risk stratification. Patients with airflow limitations may benefit from optimization before TAAA repair.

Epigenetic Induction of Smooth Muscle Cell Phenotypic Alterations in Aortic Aneurysms and Dissections.

BACKGROUND: Smooth muscle cell (SMC) phenotypic switching has been increasingly detected in aortic aneurysm and dissection (AAD) tissues. However, the diverse SMC phenotypes in AAD tissues and the mechanisms driving SMC phenotypic alterations remain to be identified. METHODS: We examined the transcriptomic and epigenomic dynamics of aortic SMC phenotypic changes in mice with angiotensin II-induced AAD by using single-cell RNA sequencing and single-cell sequencing assay for transposase-accessible chromatin. SMC phenotypic alteration in aortas from patients with ascending thoracic AAD was examined by using single-cell RNA sequencing analysis. RESULTS: Single-cell RNA sequencing analysis revealed that aortic stress induced the transition of SMCs from a primary contractile phenotype to proliferative, extracellular matrix-producing, and inflammatory phenotypes. Lineage tracing showed the complete transformation of SMCs to fibroblasts and macrophages. Single-cell sequencing assay for transposase-accessible chromatin analysis indicated that these phenotypic alterations were controlled by chromatin remodeling marked by the reduced chromatin accessibility of contractile genes and the induced chromatin accessibility of genes involved in proliferation, extracellular matrix, and inflammation. IRF3 (interferon regulatory factor 3), a proinflammatory transcription factor activated by cytosolic DNA, was identified as a key driver of the transition of aortic SMCs from a contractile phenotype to an inflammatory phenotype. In cultured SMCs, cytosolic DNA signaled through its sensor STING (stimulator of interferon genes)-TBK1 (tank-binding kinase 1) to activate IRF3, which bound and recruited EZH2 (enhancer of zeste homolog 2) to contractile genes to induce repressive H3K27me3 modification and gene suppression. In contrast, double-stranded DNA-STING-IRF3 signaling induced inflammatory gene expression in SMCs. In Sting-/- mice, the aortic stress-induced transition of SMCs into an inflammatory phenotype was prevented, and SMC populations were preserved. Finally, profound SMC phenotypic alterations toward diverse directions were detected in human ascending thoracic AAD tissues. CONCLUSIONS: Our study reveals the dynamic epigenetic induction of SMC phenotypic alterations in AAD. DNA damage and cytosolic leakage drive SMCs from a contractile phenotype to an inflammatory phenotype.

Independent associations with early mortality after open repair of Crawford extent IV thoracoabdominal aortic aneurysms.

OBJECTIVE: We aimed to identify outcomes and factors that independently associate with early mortality after open repair of Crawford extent IV thoracoabdominal aortic aneurysms, defined as aneurysms confined to the segment below the diaphragm. METHODS: This retrospective analysis included 721 extent IV thoracoabdominal aortic aneurysm repairs performed in our institution from 1986 to 2021. Indications for repair were aneurysm without dissection in 627 cases (87.0%) and aortic dissection in 94 cases (13.0%). Overall, 466 patients (64.6%) were symptomatic preoperatively; 124 (17.2%) procedures were performed in patients with acute presentation, including 58 (8.0%) ruptured aneurysms. RESULTS: Operative death occurred after 49 (6.8%) repairs. Persistent renal failure necessitating dialysis occurred after 43 (6.0%) repairs. Binary logistic regression modeling revealed that previous extent II thoracoabdominal aortic aneurysm repair, chronic kidney disease, previous myocardial infarction, urgent or emergency repair, and longer crossclamp times during surgery were independently associated with operative mortality. Among early survivors (n = 672), competing risk analysis revealed that cumulative incidence of mortality and reintervention rates at 10 years were 74.8% (95% confidence interval, 71.4%-78.5%) and 3.3% (95% confidence interval, 2.2%-5.1%), respectively. CONCLUSIONS: Although patient comorbidities contributed to operative mortality, factors associated with the repair, such as urgent or emergency status, the duration of aortic crossclamping, and certain types of complex reoperation, also played prominent roles. Patients who survive the operation can expect a durable repair that usually is free from late reintervention. Expanding our collective knowledge regarding patients who undergo open repair of extent IV thoracoabdominal aortic aneurysms will enable clinicians to establish best practices and improve patient outcomes.

Aortic Stress Activates an Adaptive Program in Thoracic Aortic Smooth Muscle Cells That Maintains Aortic Strength and Protects Against Aneurysm and Dissection in Mice.

BACKGROUND: When aortic cells are under stress, such as increased hemodynamic pressure, they adapt to the environment by modifying their functions, allowing the aorta to maintain its strength. To understand the regulation of this adaptive response, we examined transcriptomic and epigenomic programs in aortic smooth muscle cells (SMCs) during the adaptive response to AngII (angiotensin II) infusion and determined its importance in protecting against aortic aneurysm and dissection (AAD). METHODS: We performed single-cell RNA sequencing and single-cell sequencing assay for transposase-accessible chromatin (scATAC-seq) analyses in a mouse model of sporadic AAD induced by AngII infusion. We also examined the direct effects of YAP (yes-associated protein) on the SMC adaptive response in vitro. The role of YAP in AAD development was further evaluated in AngII-infused mice with SMC-specific Yap deletion. RESULTS: In wild-type mice, AngII infusion increased medial thickness in the thoracic aorta. Single-cell RNA sequencing analysis revealed an adaptive response in thoracic SMCs characterized by upregulated genes with roles in wound healing, elastin and collagen production, proliferation, migration, cytoskeleton organization, cell-matrix focal adhesion, and PI3K-PKB/Akt (phosphoinositide-3-kinase-protein kinase B/Akt) and TGF-ß (transforming growth factor beta) signaling. ScATAC-seq analysis showed increased chromatin accessibility at regulatory regions of adaptive genes and revealed the mechanical sensor YAP/transcriptional enhanced associate domains as a top candidate transcription complex driving the expression of these genes (eg, Lox, Col5a2, Tgfb2). In cultured human aortic SMCs, cyclic stretch activated YAP, which directly bound to adaptive gene regulatory regions (eg, Lox) and increased their transcript abundance. SMC-specific Yap deletion in mice compromised this adaptive response in SMCs, leading to an increased AAD incidence. CONCLUSIONS: Aortic stress triggers the systemic epigenetic induction of an adaptive response (eg, wound healing, proliferation, matrix organization) in thoracic aortic SMCs that depends on functional biomechanical signal transduction (eg, YAP signaling). Our study highlights the importance of the adaptive response in maintaining aortic homeostasis and preventing AAD in mice.

Single-Cell Analysis of Aneurysmal Aortic Tissue in Patients with Marfan Syndrome Reveals Dysfunctional TGF-ß Signaling.

The molecular and cellular processes leading to aortic aneurysm development in Marfan syndrome (MFS) remain poorly understood. In this study, we examined the changes of aortic cell populations and gene expression in MFS by performing single-cell RNA sequencing (scRNA seq) on ascending aortic aneurysm tissues from patients with MFS (n = 3) and age-matched non-aneurysmal control tissues from cardiac donors and recipients (n = 4). The expression of key molecules was confirmed by immunostaining. We detected diverse populations of smooth muscle cells (SMCs), fibroblasts, and endothelial cells (ECs) in the aortic wall. Aortic tissues from MFS showed alterations of cell populations with increased de-differentiated proliferative SMCs compared to controls. Furthermore, there was a downregulation of MYOCD and MYH11 in SMCs, and an upregulation of COL1A1/2 in fibroblasts in MFS samples compared to controls. We also examined TGF-ß signaling, an important pathway in aortic homeostasis. We found that TGFB1 was significantly upregulated in two fibroblast clusters in MFS tissues. However, TGF-ß receptor genes (predominantly TGFBR2) and SMAD genes were downregulated in SMCs, fibroblasts, and ECs in MFS, indicating impairment in TGF-ß signaling. In conclusion, despite upregulation of TGFB1, the rest of the canonical TGF-ß pathway and mature SMCs were consistently downregulated in MFS, indicating a potential compromise of TGF-ß signaling and lack of stimulus for SMC differentiation.

Site-Specific Incorporation of N-(2'-Deoxyguanosine-8-yl)-6-aminochrysene Adduct in DNA and Its Replication in Human Cells.

The environmental pollutant 6-nitrochrysene (6-NC) is a potent mutagen and a mammary carcinogen in rats. 6-NC is the most potent carcinogen ever tested in the newborn mouse assay. In mammalian cells, it is metabolically activated by nitroreduction and a combination of ring oxidation and nitroreduction pathways. The nitroreduction pathway yields two major adducts with 2'-deoxyguanosine (dG), one at the C8-position, N-(dG-8-yl)-6-AC, and the other at the exocyclic N2-position, 5-(dG-N2-yl)-6-AC. Here, we report the total synthesis of a site-specific oligonucleotide containing the 6-NC-derived C8 dG adduct, N-(dG-8-yl)-6-AC. Pd-catalyzed Buchwald-Hartwig cross coupling of 6-aminochrysene with protected C8-bromo-dG derivative served as the key reaction to furnish protected N-(dG-8-yl)-6-AC in 56% yield. The monomer for solid-phase DNA synthesis was prepared by its deprotection followed by conversion to the corresponding 5'-O-dimethoxytrityl 3'-phosphoramidite, which was used to synthesize a site-specifically adducted oligonucleotide. After purification and characterization, the adduct-containing oligonucleotide was incorporated into a plasmid and replicated in human embryonic kidney (HEK) 293T cells, which showed that N-(dG-8-yl)-6-AC stalls DNA replication as evidenced by 77% translesion synthesis (TLS) efficiency relative to the control and that the adduct is mutagenic (mutation frequency (MF) 17.8%) inducing largely G→T transversions. We also investigated the roles of several translesion synthesis DNA polymerases in the bypass of N-(dG-8-yl)-6-AC using siRNA knockdown approach. TLS efficiency was reduced in hPol η-, hPol κ-, hPol ζ-, and hREV1-deficient HEK 293T cells to 66%, 45%, 37%, and 32%, respectively. Notably, TLS efficiency was reduced to 18% in cells with concurrent knockdown of hPol κ, hPol ζ, and REV1, suggesting that these three polymerases play critical roles in bypassing N-(dG-8-yl)-6-AC. MF increased to 23.1% and 32.2% in hPol κ- and hREV1-deficient cells, whereas it decreased to 11.8% in hPol ζ-deficient cells. This suggests that hPol κ and hREV1 are involved in error-free TLS of this lesion, whereas hPol ζ performs error-prone bypass.