Total aortic arch replacement using a frozen elephant trunk device: Results of a 1-year US multicenter trial

OBJECTIVE

In this prospective US investigational device exemption trial, we assessed the safety and 1-year clinical outcomes of the Thoraflex Hybrid device (Terumo Aortic) for the frozen elephant trunk technique to repair the ascending aorta, aortic arch, and descending thoracic aorta.

METHODS

For the trial, which involved 12 US sites, 65 patients without rupture were recruited into the primary study group, and 9 patients were recruited into the rupture group. All patients underwent open surgical repair of the ascending aorta, aortic arch, and descending thoracic aorta in cases of aneurysm and/or dissection. The primary end point was freedom from major adverse events (MAE), defined as permanent stroke, permanent paraplegia/paraparesis, unanticipated aortic-related reoperation (excluding reoperation for bleeding), or all-cause mortality.

RESULTS

In the primary study group, 2 patients were lost to follow-up at 1 year. Freedom from MAE at 1 year was 81% (51/63). Seven patients (11%) died (including 2 before 30 days or discharge), 3 patients (5%) suffered permanent stroke, and 3 (5%) developed permanent paraplegia/paraparesis. Twenty-six patients (41%) underwent planned extension procedures, including 22 endovascular procedures within a median of 122 (interquartile range, 64-156) days. In the aortic rupture group, 2 patients were lost to follow-up at 1 year. Freedom from MAE at 1 year was 71% (5/7). One patient (14%) died, 2 patients (29%) had permanent stroke, and none had permanent paraplegia/paraparesis. No extension procedures were performed in the rupture group.

CONCLUSIONS

One-year results with the Thoraflex Hybrid device are acceptable. Long-term data are necessary to assess the durability of these repairs.

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.

Early and late outcomes of surgical repair of mycotic aortic aneurysms: A 30-year experience

OBJECTIVE

Mycotic aortic aneurysm and its associated complications are often catastrophic. In this study, we examined the early and late outcomes of surgical repair of mycotic aortic aneurysm at our center over the last 3 decades.

METHODS

We retrospectively reviewed our prospectively maintained aortic surgery database with supplemental adjudication of medical records. Aortic infection was confirmed through clinical, radiological, intraoperative, pathological, and treatment evidence.

RESULTS

Seventy-five patients (median age, 68 years; interquartile range, 62-74) who underwent surgical repair of a mycotic aortic aneurysm between 1992 and 2021 were included. Almost all patients (n = 72; 96%) presented with symptoms, including 26 patients (35%) with rupture, and many underwent urgent or emergency repair (n = 64; 85%). Sixty-one patients underwent open repair, and 14 patients underwent hybrid or endovascular repair. Infection-specific adjunct techniques included rifampin-soaked grafts (n = 16), omental pedicle flaps (n = 21), and antibiotic irrigation catheters (n = 8). There were 15 early deaths (20%), including 10 of the 26 patients (38%) who presented with rupture; however, persistent stroke, paraplegia or paraparesis, and renal failure necessitating dialysis were uncommon (each <5%). Almost all early survivors (52/60; 87%) were discharged with long-term antibiotic therapy. Estimated survival at 2, 6, and 10 years was 55.7% ± 5.8%, 39.0% ± 5.7%, and 26.9% ± 5.5%, respectively.

CONCLUSIONS

A substantial proportion of patients with mycotic aortic aneurysm present with rupture and generally require urgent or emergency repair. Operative mortality and complications are common, especially for patients who present with rupture, and late survival is poor.

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.

Racial disparities in thoracic aortic surgery: Myth or reality?

OBJECTIVE

We examined the relationship between Black or White race and adverse outcomes in patients who underwent surgery of the ascending aorta, aortic root, or aortic arch at our center.

METHODS

We analyzed 2335 consecutive patients who identified as Black (n = 217, 9.3%) or White (n = 2118, 90.7%) and underwent proximal aortic surgery. Patient zip codes were used to determine community socioeconomic (CSE) characteristics. The composite adverse outcome comprised mortality, persistent neurologic injury, and renal failure necessitating dialysis at discharge. We performed multivariable analysis, Kaplan-Meier analysis, and propensity score matching adjusted for CSE factors.

RESULTS

Median follow-up time was 3.7 years. Compared with White patients, Black patients lived in areas characterized by a higher percentage living below poverty level, lower income, and lower education level (P < .0001). Black patients had higher rates of emergency presentation (P < .0001) and lower 5- and 10-year survival rates (P = .0002). Short-term outcomes were similar between groups, except for respiratory failure and length of stay (P < .0001), which were higher in the Black population. After propensity score matching adjusted for CSE factors, Black and White patients (n = 204 each) had similar short-term outcomes and 5- and 10-year survival rates (P = .30). Multivariable analysis stratified by race showed that CSE factors independently predicted adverse outcomes in Black but not White patients.

CONCLUSIONS

This is among few studies that have analyzed the relationship between race and proximal aortic surgery. Although outcomes were similar between Black and White patients in our cohort after adjusting for CSE factors, unfavorable CSE factors predicted adverse outcomes in Black but not White patients. More patient-specific studies are needed.

The intersection of community socioeconomic factors with gender on outcomes after thoracic aortic surgery

OBJECTIVE

We evaluated the relationship among community socioeconomic factors (poverty, income, and education), gender, and outcomes in patients who underwent ascending aortic, root, and arch surgery.

METHODS

For 2634 consecutive patients, we associated patients' ZIP codes with community socioeconomic factors. The composite adverse outcome comprised death, persistent neurological injury, and renal failure necessitating dialysis at discharge. Multivariable analysis and Kaplan-Meier survival curves were used. Men and women from the full cohort and from the elective patients were propensity matched.

RESULTS

Median follow-up was 3.6 years (interquartile range, 1.2-9.3). Men lived in areas characterized by less poverty (P = .03), higher household income (P = .01), and more education (P = .02) than women; likewise, in the elective cohort, all community socioeconomic factors favored men (P ≤ .009). Female gender predicted composite adverse outcome (P = .006). In the propensity-matched women and men (820 pairs), the composite adverse outcome rates were 14.2% and 11%, respectively (P = .06). In 583 propensity-matched pairs of elective patients, men had less composite adverse outcome (P = .02), operative mortality (P = .04), and renal (P = .02) and respiratory failure (P = .0006). The 5- and 10-year survivals for these men and women were 74.2% versus 71.4% and 50.2% versus 48.2%, respectively (P = .06). All community socioeconomic factors in both propensity-matched groups nonsignificantly favored men.

CONCLUSIONS

This study is among the first to examine the association among community socioeconomic factors, gender, and outcomes in patients who undergo proximal aortic surgery. Female gender predicted a composite adverse outcome. In the elective patients, most adverse outcomes were significantly less in men. In the propensity-matched patients, all community socioeconomic factors favored men, although not significantly. Larger studies with patient-level socioeconomic information are needed.

Outcomes of thoracoabdominal aortic aneurysm repair in patients with a previous myocardial infarction

OBJECTIVE

Many patients undergoing thoracoabdominal aortic aneurysm (TAAA) repair have had a previous myocardial infarction (MI). To address the paucity of data regarding outcomes in such patients, we aimed to compare outcomes after open TAAA repair in patients with and without previous MI.

METHODS

From 1986 to 2022, we performed 3737 consecutive open TAAA repairs. Of these, 706 (18.9%) were in patients with previous MI. We used multivariable logistic regression to identify predictors of operative death. Propensity score matching analyzed preoperative and select operative variables to create matched groups of patients with or without a previous MI (n = 704 pairs). Late survival was determined by Kaplan-Meier analysis and compared by log rank test.

RESULTS

Overall, operative mortality was 8.5% and the adverse event rate was 15.2%; these were elevated in patients with MI (11.0% vs 7.9% [P = .01] and 18.0% vs 14.6% [P = .02], respectively). In the propensity score-matching cohort, the MI group had a greater rate of cardiac complications (32.4% vs 25.4%; P = .005) and delayed paraparesis (5.1% vs 2.4%; P = .1); however, there was no difference in operative mortality (11.1% vs 10.9%; P = 1) or adverse event rate (18.0% vs 16.8%; P = .6). Overall, previous MI was not independently associated with operative mortality in multivariable analysis (P = .1). The matched MI group trended toward poorer 10-year survival (29.8% ± 1.9% non-MI vs 25.0% ± 1.8% MI; P = .051).

CONCLUSIONS

Although previous MI was not associated with early mortality after TAAA repair, patients with a previous MI had greater rates of cardiac complications and delayed paraparesis. Patients with a previous MI also trended toward poorer survival.

Vertebral Tortuosity Is Associated With Increased Rate of Cardiovascular Events in Vascular Ehlers-Danlos Syndrome

Background Arterial tortuosity is associated with adverse events in Marfan and Loeys-Dietz syndromes but remains understudied in Vascular Ehlers-Danlos syndrome. Methods and Results Subjects with a pathogenic COL3A1 variant diagnosed at age <50 years were included from 2 institutions and the GenTAC Registry (National Registry of Genetically Triggered Thoracic Aortic Aneurysms and Cardiovascular Conditions). Height-adjusted vertebral artery tortuosity index (VTI-h) using magnetic resonance or computed tomography angiography was calculated. Associations between VTI-h and outcomes of (1) cardiovascular events (arterial dissection/rupture, aneurysm requiring intervention, stroke), or (2) hollow organ collapse/rupture at age <50 years were evaluated using receiver operator curve analysis (using outcome by age 30 years) and mixed-effects Poisson regression for incidence rate ratios. Of 65 subjects (54% male), median VTI-h was 12 (interquartile range, 8-16). Variants were missense in 46%, splice site in 31%, and null/gene deletion in 14%. Thirty-two subjects (49%) had 59 events, including 28 dissections, 5 arterial ruptures, 4 aneurysms requiring intervention, 4 strokes, 11 hollow organ ruptures, and 7 pneumothoraces. Receiver operator curve analysis suggested optimal discrimination at VTI-h ≥15.5 for cardiovascular events (sensitivity 70%, specificity 76%) and no association with noncardiovascular events (area under the curve, 0.49 [95% CI, 0.22-0.78]). By multivariable analysis, older age was associated with increased cardiovascular event rate while VTI-h ≥15.5 was not (incidence rate ratios, 1.79 [95% CI, 0.76-4.24], P=0.185). However, VTI-h ≥15.5 was associated with events among those with high-risk variants <40 years (incidence rate ratios, 4.14 [95% CI, 1.13-15.10], P=0.032), suggesting effect modification by genotype and age. Conclusions Increased arterial tortuosity is associated with a higher incidence rate of cardiovascular events in Vascular Ehlers-Danlos syndrome. Vertebral tortuosity index may be a useful biomarker for prognosis when evaluated in conjunction with genotype and age.

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.

Current approaches to spinal cord protection during open thoracoabdominal aortic aneurysm repair

Spinal cord deficit (SCD) is a feared complication after thoracoabdominal aortic aneurysm repair. Vigilant management throughout the perioperative period is necessary to reduce the risk of SCD. Measures for preventing SCD during the intraoperative period include preoperative optimization and recognizing patients at a higher risk of SCD. In this manuscript, we discuss intraoperative adjuncts including utilization of cerebrospinal fluid drainage, left heart bypass, mild hypothermia, selective reimplantation of intercostal and lumbar arteries, and renal and visceral vessel perfusion. From the operative to the postoperative period, careful attention to avoiding hypotension and anemia is important. If SCD is recognized early, therapeutic intervention may be implemented to mitigate injury.

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.

Contemporary Midterm Outcomes After Primary Repair of Chronic Type A Aortic Dissection

BACKGROUND

Without surgical repair, acute type A aortic dissection (TAAD) is usually fatal. However, some patients survive without an early operation and progress to the chronic phase. Contemporary outcomes of primary surgical repair of chronic TAAD are unclear, so we evaluated them at our single-practice service.

METHODS

During 1990 to 2021, 205 patients underwent repair of TAAD in the chronic phase (>60 days after onset). The 2 relevant DeBakey classifications were nearly equally represented: type I, 52% (n = 107), and type II, 48% (n = 98). The median interval between dissection onset and repair was 7 months (interquartile range, 3-25 months). Kaplan-Meier and competing-risk analyses provided time-dependent outcomes.

RESULTS

At the time of intervention, most patients (40%) had chronic symptoms. Type I patients were younger than type II patients; however, comorbidities were similar. Most patients (n = 183 [87%]) underwent hemiarch or total arch repair, although total arch replacement was more common in type I dissection (P < .001). There were 15 operative deaths (7%), and 7 strokes (3%) persisted to the time of death or discharge. No patient had persistent paraplegia. Median follow-up was 5 years (interquartile range, 2-11 years). The 5-year reoperation-free survival was 61% (95% CI, 54%-68%), and the incidence of reoperation was 3% (95% CI, 0.4%-5%). Patients with type I and type II dissection did not differ significantly in survival (P = .2).

CONCLUSIONS

Durable repair can be achieved with reasonable operative risk. Treatment is individualized and is associated with low rates of persistent neurologic complications. Despite differing operative approaches by DeBakey type, early and late outcomes were similar.

Outcomes of aortic root replacement in patients with Marfan syndrome: the role of valve-sparing and valve-replacing approaches

BACKGROUND

Marfan syndrome (MFS) is a heritable thoracic aortic disease with pervasive cardiovascular effects, including commonly, a dilated aortic root. Traditionally, the root is replaced using a mechanical composite valve graft (CVG); however, this valve-replacing (VR) approach necessitates a lifelong regimen of anticoagulation with a potential for late bleeding complications. In time, valve-sparing (VS) approaches were developed. Today, several options for aortic root replacement (ARR) exist; each has advantages and disadvantages that helps inform choice. The Aortic Valve Operative Outcomes in Marfan Patients (AVOMP) is a multi-center international registry to analyze clinical outcomes of ARR in MFS patients using either VR or VS techniques to better elucidate choice. We summarize outcomes of AVOMP and present our own experience.

METHODS

We performed 223 consecutive elective ARR [1991-2023] in patients with MFS; 15 such repairs were included in AVOMP. Repairs included 113 (51%) using a mechanical CVG, 62 (28%) using a VS approach, and 48 (22%) using a bioprosthetic root. Many patients underwent aortic arch repair (30% to 54% by type).

RESULTS

The median patient age was 38 [29-52] years. In comparing VS and VR groups, patients were similar in age and rates of major comorbidities and symptoms. Patients with VR repair had a more complex aortic history. The rate of redo sternotomy was 24% (n=54). Operative death was uncommon [4% overall (10/223); ranging from 2% to 8% by type], and stroke was rare [1/223 (<1%)]. Late survival and reoperation differed by operative approach; survival was improved in patients who underwent VS repair.

CONCLUSIONS

We found that repair in patients with MFS undergoing ARR resulted in low operative risk. Our late results were similar to those of AVOMP in that patients undergoing VS repair tended to experience greater rates of valvular-structural deterioration, although this did not appear to impact survival.

Genome-wide association study of thoracic aortic aneurysm and dissection in the Million Veteran Program

The current understanding of the genetic determinants of thoracic aortic aneurysms and dissections (TAAD) has largely been informed through studies of rare, Mendelian forms of disease. Here, we conducted a genome-wide association study (GWAS) of TAAD, testing ~25 million DNA sequence variants in 8,626 participants with and 453,043 participants without TAAD in the Million Veteran Program, with replication in an independent sample of 4,459 individuals with and 512,463 without TAAD from six cohorts. We identified 21 TAAD risk loci, 17 of which have not been previously reported. We leverage multiple downstream analytic methods to identify causal TAAD risk genes and cell types and provide human genetic evidence that TAAD is a non-atherosclerotic aortic disorder distinct from other forms of vascular disease. Our results demonstrate that the genetic architecture of TAAD mirrors that of other complex traits and that it is not solely inherited through protein-altering variants of large effect size.

Dispersion of NIH Funding to Departments of Surgery is Contracting

INTRODUCTION

NIH funding to departments of surgery reported as benchmark Blue Ridge Institute for Medical Research (BRIMR) rankings are unclear.

METHODS

We analyzed inflation-adjusted BRIMR-reported NIH funding to departments of surgery and medicine between 2011 and 2021.

RESULTS

NIH funding to departments of surgery and medicine both increased 40% from 2011 to 2021 ($325 million to $454 million; $3.8 billion to $5.3 billion, P < 0.001 for both). The number of BRIMR-ranked departments of surgery decreased 14% during this period while departments of medicine increased 5% (88 to 76 versus 111 to 116; P < 0.001). There was a greater increase in the total number of medicine PIs versus surgery PIs during this period (4377 to 5224 versus 557 to 649; P < 0.001). These trends translated to further concentration of NIH-funded PIs in medicine versus surgery departments (45 PIs/program versus 8.5 PIs/program; P < 0.001). NIH funding and PIs/program in 2021 were respectively 32 and 20 times greater for the top versus lowest 15 BRIMR-ranked surgery departments ($244 million versus $7.5 million [P < 0.01]; 20.5 versus 1.3 [P < 0.001]). Twelve (80%) of the top 15 surgery departments maintained this ranking over the 10-year study period.

CONCLUSIONS

Although NIH funding to departments of surgery and medicine is growing at a similar rate, departments of medicine and top-funded surgery departments have greater funding and concentration of PIs/program versus surgery departments overall and lowest-funded surgery departments. Strategies used by top-performing departments to obtain and maintain funding may assist less well-funded departments in obtaining extramural research funding, thus broadening the access of surgeon-scientists to perform NIH-supported research.

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 (TAAAs), defined as aneurysms confined to the segment below the diaphragm.

METHODS

This retrospective analysis included 721 extent IV TAAA 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 (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 TAAA repair, chronic kidney disease, previous myocardial infarction, urgent or emergency repair, and longer cross-clamp times during surgery were independently associated with operative mortality. Among early survivors (n=672), competing risk regression modeling revealed that cumulative incidence of mortality and reintervention rates at 10 years were 74.8% (95% CI: 71.4%-78.5%) and 3.3% (95% CI: 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 cross-clamping, 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 TAAAs 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-β (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.

AIM2 Inflammasome Activation Contributes to Aortic Dissection in a Sporadic Aortic Disease Mouse Model

BACKGROUND

The absent in melanoma 2 (AIM2) inflammasome induces pyroptosis, tissue inflammation, and extracellular matrix destruction. We tested the hypothesis that the AIM2 inflammasome contributes to aortic aneurysm and dissection (AAD) development by promoting pyroptosis in smooth muscle cells (SMCs).

METHODS

We examined AIM2 expression in aortic tissues from patients with ascending thoracic aortic aneurysm (ATAA) and aortic dissection (ATAD) and from organ donor controls. AIM2's role in AAD development was evaluated in AIM2-deficient mice in a sporadic AAD model induced by challenging mice with a high-fat diet and angiotensin II infusion. The direct effects of dsDNA on SMC death in vitro were studied.

RESULTS

Western blot analyses showed that AIM2 was increased in ATAD compared to ATAA and control tissue. Immunofluorescence demonstrated increased AIM2 in SMCs and macrophages in the aortic media and adventitia of dissected tissue. Increased AIM2 abundance was associated with increased cleavage of caspase-1 and cleavage of gasdermin-D, indicating activation of pyroptosis. In a mouse model of sporadic AAD induced by high-fat diet and angiotensin II infusion, AIM2-deficient mice showed significant reduction in aortic dissection, but not aneurysm formation in all aortic segments, versus wild-type mice. Finally, treating cultured human aortic SMCs with double-stranded DNA induced AIM2 expression, caspase-1 cleavage, and gasdermin-D cleavage; these effects were reduced by silencing AIM2 and caspase-1 genes, suggesting involvement of the AIM2 inflammasome in cytosolic DNA-induced activation of SMC pyroptosis.

CONCLUSIONS

Activation of the AIM2 inflammasome cascade contributes to aortic degeneration and dissection, in part, by activating pyroptosis.

Ciprofloxacin accelerates aortic enlargement and promotes dissection and rupture in Marfan mice

OBJECTIVE

Aortic aneurysm and dissection are major life-threatening complications of Marfan syndrome. Avoiding factors that promote aortic damage is critical in managing the care of these patients. Findings from clinical and animal studies raise concerns regarding fluoroquinolone use in patients at risk for aortic aneurysm and dissection. Therefore, we examined the effects of ciprofloxacin on aortic aneurysm and dissection development in Marfan mice.

METHODS

Eight-week-old Marfan mice (Fbn1C1041G/+) were given ciprofloxacin (100 mg/kg/d; n = 51) or vehicle (n = 59) for 4 weeks. Mice were monitored for 16 weeks. Aortic diameters were measured by using ultrasonography, and aortic structure was examined by using histopathologic and immunostaining analyses.

RESULTS

Vehicle-treated Fbn1C1041G/+ mice showed progressive aortic enlargement, with aortic rupture occurring in 5% of these mice. Compared with vehicle-treated Fbn1C1041G/+ mice, ciprofloxacin-treated Fbn1C1041G/+ mice showed accelerated aortic enlargement (P = .01) and increased incidences of aortic dissection (25% vs 47%, P = .03) and rupture (5% vs 25%, P = .005). Furthermore, ciprofloxacin-treated Fbn1C1041G/+ mice had higher levels of elastic fiber fragmentation, matrix metalloproteinase expression, and apoptosis than did vehicle-treated Fbn1C1041G/+ mice.

CONCLUSIONS

Ciprofloxacin accelerates aortic root enlargement and increases the incidence of aortic dissection and rupture in Marfan mice, partially by suppressing lysyl oxidase expression and further compromising the inherited defect in aortic elastic fibers. Our findings substantiate that ciprofloxacin should be avoided in patients with Marfan syndrome.

Second Heart Field-derived Cells Contribute to Angiotensin II-mediated Ascending Aortopathies

Background: The ascending aorta is a common location for aneurysm and dissection. This aortic region is populated by a mosaic of medial and adventitial cells that are embryonically derived from either the second heart field (SHF) or the cardiac neural crest. SHF-derived cells populate areas that coincide with the spatial specificity of thoracic aortopathies. The purpose of this study was to determine whether and how SHF-derived cells contribute to ascending aortopathies. Methods: Ascending aortic pathologies were examined in patients with sporadic thoracic aortopathies and angiotensin II (AngII)-infused mice. Ascending aortas without overt pathology from AngII-infused mice were subjected to mass spectrometry assisted proteomics, and molecular features of SHF-derived cells were determined by single cell transcriptomic analyses. Genetic deletion of either low-density lipoprotein receptor-related protein 1 (Lrp1) or transforming growth factor-β receptor 2 (Tgfbr2) in SHF-derived cells was conducted to examine the impact of SHF-derived cells on vascular integrity. Results: Pathologies in human ascending aortic aneurysmal tissues were predominant in outer medial layers and adventitia. This gradient was mimicked in mouse aortas following AngII infusion that was coincident with the distribution of SHF-derived cells. Proteomics indicated that brief AngII infusion, prior to overt pathology, evoked downregulation of SMC proteins and differential expression of extracellular matrix proteins, including several LRP1 ligands. LRP1 deletion in SHF-derived cells augmented AngII-induced ascending aortic aneurysm and rupture. Single cell transcriptomic analysis revealed that brief AngII infusion decreased Lrp1 and Tgfbr2 mRNA abundance in SHF-derived cells and induced a unique fibroblast population with low abundance of Tgfbr2 mRNA. SHF-specific Tgfbr2 deletion led to embryonic lethality at E12.5 with dilatation of the outflow tract and retroperitoneal hemorrhage. Integration of proteomic and single cell transcriptomics results identified plasminogen activator inhibitor 1 (PAI1) as the most increased protein in SHF-derived SMCs and fibroblasts during AngII infusion. Immunostaining revealed a transmural gradient of PAI1 in both ascending aortas of AngII-infused mice and human ascending aneurysmal aortas that mimicked the gradient of medial and adventitial pathologies. Conclusions: SHF-derived cells exert a critical role in maintaining vascular integrity through LRP1 and TGF-β signaling associated with increases of aortic PAI1.

Racial and Ethnic Disparities in Abdominal Aortic Aneurysm Evaluation and Treatment Rates in Texas

INTRODUCTION

Screening identifies intact abdominal aortic aneurysm (iAAA) before progression to ruptured AAA (rAAA). However, screening efforts have been limited by low overall diagnostic yield and by unequal screening among minority populations. The goal was to identify equitable AAA screening strategies for both majority and minority populations.

METHODS

We performed epidemiological and geospatial analyses of inpatient and outpatient procedures for iAAA or rAAA at Texas hospitals from 2006 through 2014 at all non-federal hospitals and clinics in Texas. Data were aggregated by area (metropolitan statistical area or rural region), then supplemented by six additional data sources to estimate AAA repair incidence rates, rates of AAA-related clinic and ultrasonography visits, distance to providers, and location and number of unrecognized AAAs.

RESULTS

The majority of AAA repairs occurred among 65-84 year-old men in large metropolitan areas categorized as White. Area procedure rates for rAAA and iAAA were strongly correlated (R²=0.47). Two other variables-the proportions of persons categorized as White and persons aged ≥65 years in a region-identified subgroups within the majority population that were at high risk for iAAA (R²=0.46). Lower rates of clinic visits and AAA ultrasonograms were seen among persons categorized as Black. The several areas with disproportionately-higher rAAA:iAAA ratios were found, mainly affecting persons categorized as Black.

CONCLUSIONS

Multiple focused AAA screening strategies may be needed to address disproportionately-lower AAA identification among persons categorized as Black.

Single-Cell Analysis of Aneurysmal Aortic Tissue in Patients with Marfan Syndrome Reveals Dysfunctional TGF-β 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-β signaling, an important pathway in aortic homeostasis. We found that TGFB1 was significantly upregulated in two fibroblast clusters in MFS tissues. However, TGF-β receptor genes (predominantly TGFBR2) and SMAD genes were downregulated in SMCs, fibroblasts, and ECs in MFS, indicating impairment in TGF-β signaling. In conclusion, despite upregulation of TGFB1, the rest of the canonical TGF-β pathway and mature SMCs were consistently downregulated in MFS, indicating a potential compromise of TGF-β signaling and lack of stimulus for SMC differentiation.

Staged Repair of Extensive Aneurysms of the Thoracic Aorta by Using the Elephant Trunk Technique

BACKGROUND

Staged open repair of extensive aortic aneurysm by using the elephant trunk (ET) technique has facilitated the treatment of aortic aneurysms that affect the entire thoracic aorta. We describe our nearly 3-decade experience with classic ET repairs.

METHODS

From 1990 through 2021, we performed 363 stage-1 ET repairs to replace the transverse aortic arch in patients with a median age of 65 years [interquartile range: 56-71]. Fifty-six patients (15.4%) presented with acute symptoms, and 182 (50.1%) underwent redo sternotomy. After a median interval of 3.2 months [IQR: 2.0-7.3], 203 (55.9%) patients underwent stage-2 ET completion; few (n=16; 7.9%) had acute symptoms. Stage-2 repairs comprised 162 (80.6%) extent I or II thoracoabdominal aortic replacements. We examined postoperative outcomes including operative mortality, adverse event (a composite end point), survival, and repair failure.

RESULTS

Operative mortality was 12.4% (45/363) after stage-1 and 10.3% (21/203) after stage-2. The rates of adverse event were 18.5% (67/363) for stage-1 and 18.4% (38/203) for stage-2. Acute symptoms independently predicted operative mortality and adverse event for both stage-1 and stage-2 repairs; additional predictors for stage-2 repairs were older age and extent II repair. Survival was significantly worse for patients who did not receive their stage-2 completion repair than for those who did (p <0.001).

CONCLUSIONS

Treating extensive aortic aneurysms by using the ET technique for staged repair is associated with substantial morbidity and mortality. Patients who present with acute symptoms are at greater risk of operative mortality and adverse event. Diligent surveillance is needed between stages.

Molecular and Cellular Dynamics of Aortic Aneurysms Revealed by Single-Cell Transcriptomics

The aorta is highly heterogeneous, containing many different types of cells that perform sophisticated functions to maintain aortic homeostasis. Recently, single-cell RNA sequencing studies have provided substantial new insight into the heterogeneity of vascular cell types, the comprehensive molecular features of each cell type, and the phenotypic interrelationship between these cell populations. This new information has significantly improved our understanding of aortic biology and aneurysms at the molecular and cellular level. Here, we summarize these findings, with a focus on what single-cell RNA sequencing analysis has revealed about cellular heterogeneity, cellular transitions, communications among cell populations, and critical transcription factors in the vascular wall. We also review the information learned from single-cell RNA sequencing that has contributed to our understanding of the pathogenesis of vascular disease, such as the identification of cell types in which aneurysm-related genes and genetic variants function. Finally, we discuss the challenges and future directions of single-cell RNA sequencing applications in studies of aortic biology and diseases.

Open Repair of Acute Type A Intramural Hematoma in 3 Patients

Acute aortic syndrome encompasses classic aortic dissection and less common aortic phenomena, including intramural hematoma (IMH), a hemorrhage within the aortic media that occurs without a discrete intimal tear. We reviewed our experience with treating acute type A IMH to better understand this acute aortic syndrome. A review of our clinical database identified 1,902 proximal aortic repairs that were performed from January 2006 through December 2018; of these, 266 were for acute aortic syndrome, including 3 (1.1%) for acute type A IMH. Operative technique varied considerably. All IMH repairs involved hemiarch or total arch replacement. In all 3 patients, the IMH extended distally into the descending thoracic aorta. There were no operative deaths or major adverse events (stroke, paraplegia, paraparesis, or renal failure necessitating dialysis) that persisted to hospital discharge. Length of hospitalization ranged from 5 to 20 days. All 3 patients were alive at follow-up (range, 2-6 yr) and needed no aortic reintervention after their index or staged repairs. In our experience, repair of acute type A IMH was infrequent and could be either simple or complex. Despite our limited experience with this disease, we found that it can be repaired successfully in urgent and emergency cases. Following treatment guidelines for aortic dissection appears to be a reasonable strategy for treating IMH.

Midterm outcomes of aortic root surgery in patients with Marfan syndrome: A prospective, multicenter, comparative study

OBJECTIVE

The objective of this study was to compare midterm outcomes of aortic valve-replacing root replacement (AVR) and aortic valve-sparing root replacement (AVS) operations in patients with Marfan syndrome.

METHODS

Patients who met strict Ghent diagnostic criteria for Marfan syndrome and who underwent either AVR or AVS between March 1, 2005 and December 31, 2010 were enrolled in a 3-year follow-up prospective, multicenter, international registry study; the study was subsequently amended to include 20-year follow-up. Enrollees were followed clinically and echocardiographically.

RESULTS

Of the 316 patients enrolled, 77 underwent AVR and 239 underwent AVS; 214 gave reconsent for 20-year follow-up. The median clinical follow-up time for surviving patients was 64 months (interquartile range, 42-66 months). Survival rates for the AVR and AVS groups were similar at 88.2% ± 4.4% and 95.0% ± 1.5%, respectively (P = .1). Propensity score-adjusted competing risk modeling showed associations between AVS and higher cumulative incidences of major adverse valve-related events, valve-related morbidity, combined structural valve deterioration and nonstructural valve dysfunction, and aortic regurgitation ≥2+ (all P < .01). No differences were found for reintervention (P = .7), bleeding (P = .2), embolism (P = .3), or valve-related mortality (P = .8).

CONCLUSIONS

Five years postoperatively, major adverse valve-related events and valve-related morbidity were more frequent after AVS than after AVR procedures, primarily because of more frequent aortic valve dysfunction. No between-group differences were found in rates of survival, valve-related mortality, reintervention on the aortic valve, or bleeding. We plan to follow this homogenous cohort for 20 years after aortic root replacement.

New Technologies With Increased Precision Improve Understanding of Endothelial Cell Heterogeneity in Cardiovascular Health and Disease

Endothelial cells (ECs) are vital for blood vessel integrity and have roles in maintaining normal vascular function, healing after injury, and vascular dysfunction. Extensive phenotypic heterogeneity has been observed among ECs of different types of blood vessels in the normal and diseased vascular wall. Although ECs with different phenotypes can share common functions, each has unique features that may dictate a fine-tuned role in vascular health and disease. Recent studies performed with single-cell technology have generated powerful information that has significantly improved our understanding of EC biology. Here, we summarize a variety of EC types, states, and phenotypes recently identified by using new, increasingly precise techniques in transcriptome analysis.

Effect of sarcopenia on survival and spinal cord deficit outcomes after thoracoabdominal aortic aneurysm repair in patients 60 years of age and older

OBJECTIVE

Sarcopenia (core muscle loss) has been used as a surrogate marker of frailty. We investigated whether sarcopenia would adversely affect survival after thoracoabdominal aortic aneurysm repair.

METHODS

We retrospectively reviewed prospectively collected data from patients aged 60 years or older who underwent thoracoabdominal aortic aneurysm repairs from 2006 to 2016. Imaging was reviewed by 2 radiologists blinded to clinical outcomes. The total psoas index was derived from total psoas muscle cross-sectional area (cm²) at the mid-L4 level, normalized for height (m²). Patients were divided by sex-specific total psoas index values into sarcopenia (lower third) and nonsarcopenia (upper two-thirds) groups. Multivariable modeling identified operative mortality and spinal cord injury predictors. Unadjusted and adjusted survival curves were analyzed.

RESULTS

Of 392 patients identified, those with sarcopenia (n = 131) were older than nonsarcopenic patients (n = 261) (70.0 years vs 68.0 years; P = .02) and more frequently presented with aortic rupture or required urgent/emergency operations. Operative mortality was comparable (sarcopenia 13.7% vs nonsarcopenia 10.0%; P = .3); sarcopenia was not associated with operative mortality in the multivariable model (odds ratio, 1.40; 95% confidence interval, 0.73-2.77; P = .3). Sarcopenic patients experienced more frequent delayed (13.0% vs 4.6%; P = .005) and persistent (10.7% vs 3.4%; P = .008) paraplegia. Sarcopenia independently predicted delayed paraplegia (odds ratio, 3.17; 95% confidence interval, 1.42-7.08; P = .005) and persistent paraplegia (odds ratio, 3.29; 95% confidence interval, 1.33-8.13; P = .01) in the multivariable model. Adjusted for preoperative/operative covariates, midterm survival was similar for sarcopenic and nonsarcopenic patients (P = .3).

CONCLUSIONS

Sarcopenia did not influence early mortality or midterm survival after thoracoabdominal aortic aneurysm repair but was associated with greater risk for delayed and persistent paraplegia.

Sex Differences in Ascending Aortic and Arch Surgery: A Propensity-matched Comparison of 1153 Pairs

BACKGROUND

We investigated the relationship of sex with clinical outcomes after proximal aortic (ascending and arch) operations, and whether sex-specific preoperative factors are associated with mortality.

METHODS

Of 3745 patients who underwent elective, urgent, and emergency proximal aortic operations over a 20-year period, 1153 pairs of men and women were propensity-matched, and their early and long-term outcomes were compared. Kaplan-Meier survival analysis was used to estimate late survival.

RESULTS

Women and men had similar operative mortality (9.1% vs 8.8%, P=0.8), stroke (5.7% vs 5.6%, P=0.9), and renal failure rates (7.0% vs 6.6%, P=0.7). Thirty-day mortality was 7.5% versus 5.6% (P=0.06), respectively. Results were less favorable for women than for men regarding respiratory failure (34.3% vs 29.2%, P=0.008) and intensive care unit length of stay (9.11±11.9 vs 7.87±12.48 days; P=0.023). Long-term survival was not significantly different between women and men: 66.3% (95%CI 62.8-69.5) versus 67.1% (95%CI 63.6-70.4) at 5 years, and 45.9% (95%CI 41.76-50.0) versus 46.2% (95%CI 41.7-50.6) at 10 years (P=0.4). Preoperative factors including diabetes, prior stroke, prior renal insufficiency, and peripheral vascular disease were associated with operative mortality in men, whereas chronic obstructive pulmonary disease was the main risk factor in women.

CONCLUSIONS

No differences were seen between the sexes in life-changing adverse outcomes after ascending aortic and arch procedures, although specific preoperative variables were associated with specific adverse events. Recognizing differences in preoperative risk factors for mortality between the sexes may facilitate targeted preoperative assessment, preparation, and counseling.

Early Detection of Aortic Degeneration in a Mouse Model of Sporadic Aortic Aneurysm and Dissection Using Nanoparticle Contrast-Enhanced Computed Tomography

[Figure: see text].

Monosomy X in Female Mice Influences the Regional Formation and Augments the Severity of Angiotensin II-Induced Aortopathies

OBJECTIVE

Turner syndrome women (monosomy X) have high risk of aortopathies consistent with a role for sex chromosomes in disease development. We demonstrated that sex chromosomes influence regional development of Ang II (angiotensin II)-induced aortopathies in mice. In this study, we determined if the number of X chromosomes regulates regional development of Ang II-induced aortopathies. Approach and Results: We used females with varying numbers of X chromosomes (XX female mice [XXF] or XO female mice [XOF]) on an C57BL/6J (ascending aortopathies) or low-density lipoprotein receptor deficient (Ldlr-/-) background (descending and abdominal aortopathies) compared with XY males (XYM). To induce aortopathies, mice were infused with Ang II. XOF (C57BL/6J) exhibited larger percent increases in ascending aortic lumen diameters than Ang II-infused XXF or XYM. Ang II-infused XOF (Ldlr-/-) exhibited similar incidences of thoracic (XOF, 50%; XYM, 71%) and abdominal aortopathies (XOF, 83%; XYM, 71%) as XYM, which were greater than XXF (XXF, 0%). Abdominal aortic lumen diameters and maximal external diameters were similar between XOF and XYM but greater than XXF, and these effects persisted with extended Ang II infusions. Larger aortic lumen diameters, abdominal aortopathy incidence (XXF, 20%; XOF, 75%), and maximal aneurysm diameters (XXF, 1.02±0.17; XOF, 1.96±0.32 mm; P=0.027) persisted in ovariectomized Ang II-infused XOF mice. Data from RNA-seq demonstrated that X chromosome genes that escape X-inactivation (histone lysine demethylases Kdm5c and Kdm6a) exhibited lower mRNA abundance in aortas of XOF than XXF (P=0.033 and 0.024, respectively). Conversely, DNA methylation was higher in aortas of XOF than XXF (P=0.038).

CONCLUSIONS

The absence of a second X chromosome promotes diffuse Ang II-induced aortopathies in females.

Cholesterol-Induced Phenotypic Modulation of Smooth Muscle Cells to Macrophage/Fibroblast-like Cells Is Driven by an Unfolded Protein Response

OBJECTIVE

Vascular smooth muscle cells (SMCs) dedifferentiate and initiate expression of macrophage markers with cholesterol exposure. This phenotypic switching is dependent on the transcription factor Klf4 (Krüppel-like factor 4). We investigated the molecular pathway by which cholesterol induces SMC phenotypic switching. Approach and Results: With exposure to free cholesterol, SMCs decrease expression of contractile markers, activate Klf4, and upregulate a subset of macrophage and fibroblast markers characteristic of modulated SMCs that appear with atherosclerotic plaque formation. These phenotypic changes are associated with activation of all 3 pathways of the endoplasmic reticulum unfolded protein response (UPR), Perk (protein kinase RNA-like endoplasmic reticulum kinase), Ire (inositol-requiring enzyme) 1α, and Atf (activating transcription factor) 6. Blocking the movement of cholesterol from the plasma membrane to the endoplasmic reticulum prevents free cholesterol-induced UPR, Klf4 activation, and upregulation of the majority of macrophage and fibroblast markers. Cholesterol-induced phenotypic switching is also prevented by global UPR inhibition or specific inhibition of Perk signaling. Exposure to chemical UPR inducers, tunicamycin and thapsigargin, is sufficient to induce these same phenotypic transitions. Finally, analysis of published single-cell RNA sequencing data during atherosclerotic plaque formation in hyperlipidemic mice provides preliminary in vivo evidence of a role of UPR activation in modulated SMCs.

CONCLUSIONS

Our data demonstrate that UPR is necessary and sufficient to drive phenotypic switching of SMCs to cells that resemble modulated SMCs found in atherosclerotic plaques. Preventing a UPR in hyperlipidemic mice diminishes atherosclerotic burden, and our data suggest that preventing SMC transition to dedifferentiated cells expressing macrophage and fibroblast markers contributes to this decreased plaque burden.

Propensity score analysis in patients with and without previous isolated coronary artery bypass grafting who require proximal aortic and arch surgery

OBJECTIVE

The risk posed by previous isolated coronary artery bypass grafting (CABG) in patients who require proximal aortic or aortic arch surgery is unclear. We compared outcomes of ascending aortic and arch procedures in patients with and without previous CABG.

METHODS

Using propensity scores, we created 2 matched groups of patients who underwent proximal aortic surgery, including total arch repairs, at our institution: 126 patients who underwent isolated CABG before the index operation and 126 without previous CABG. Forty-four percent of aortic operations were emergency procedures. Eighty-six patients had a patent previous left internal mammary graft. We compared outcomes between the 2 groups and calculated Kaplan-Meier survival curves.

RESULTS

The following outcomes were recorded for the patients with previous isolated CABG versus no CABG: operative mortality, 15.9% versus 11.1% (P = .3); 30-day mortality, 13.5% versus 7.1% (P = .1); persistent stroke, 6.3% versus 4.8% (P = .6); and renal failure necessitating hemodialysis at discharge, 7.9% versus 4.0% (P = .2). Previous CABG did not independently predict any adverse outcome, even though patients who underwent previous CABG more frequently needed intra-aortic balloon support (P < .01). The P value for the overall intergroup difference in long-term survival was .06.

CONCLUSIONS

This is one of the largest studies yet reported to examine the impact of previous isolated CABG on proximal aortic or arch surgery outcomes. Although these results may be specific to aortic centers of excellence, in this complicated patient cohort, previous isolated CABG did not independently predict any adverse outcome. These results could serve as a benchmark for assessing future endovascular therapies.

A 23-year experience with the reversed elephant trunk technique for staged repair of extensive thoracic aortic aneurysm

OBJECTIVE

The reversed elephant trunk technique permits staged repair of extensive thoracic aortic aneurysm in patients whose distal (ie, descending thoracic and thoracoabdominal) aorta is symptomatic or disproportionately large compared with their proximal aorta (ie, ascending aorta and transverse aortic arch). We present our 23-year experience with the reversed elephant trunk approach.

METHODS

Between 1994 and 2017, 94 patients (median age 62 [46-69] years) underwent stage 1 reversed elephant trunk repair of the distal aorta. Fifty-three patients (56%) had aortic dissection, and 31 patients (33%) had heritable thoracic aortic disease. Eighty-eight operations (94%) were Crawford extent I or II thoracoabdominal aortic repairs. Twenty-seven patients (29%) underwent subsequent stage 2 repair of the proximal aorta; 14 patients (52%) required redo median sternotomy. The median time between the stage 1 and 2 operations was 18.8 (4.8-69.3) months.

RESULTS

The operative mortality was 10% (9/94) for stage 1 repairs and 4% (1/27) for stage 2 repairs; 1 patient with heritable thoracic aortic disease died after stage 1 repair (1/31, 3%), and 1 patient died after stage 2 repair (1/13, 8%). Two patients (2%) had ruptures after stage 1 repair; 1 resulted in death, and 1 precipitated emergency stage 2 repair. In total, 36 patients (38%) who survived stage 1 repair died before stage 2 reversed elephant trunk completion repair could be performed.

CONCLUSIONS

Managing extensive aortic aneurysm with the 2-stage reversed elephant trunk technique yields acceptable short-term outcomes. This technique is useful for the reversed elephant trunk in patients who require distal aortic repair before proximal repair and is particularly effective in patients with heritable thoracic aortic disease. The low number of patients returning for completion repair is concerning. Rigorous surveillance is needed.

Early Gastrointestinal Complications After Open Thoracoabdominal Aortic Aneurysm Repair

BACKGROUND

The present study was done to examine the incidence, predictors, and impact of early gastrointestinal (GI) complications after open thoracoabdominal aortic aneurysm repair.

METHODS

We retrospectively analyzed data from 3587 open thoracoabdominal aortic aneurysm repairs performed at our center from 1986 to 2019. We used univariate analyses and multivariable logistic regression to identify risk factors associated with GI complications, including bleeding, ischemia, obstruction, and acute pancreatitis. Adverse event was defined as operative death or persistent stroke, paraplegia, paraparesis, or renal failure necessitating dialysis.

RESULTS

Gastrointestinal complications developed after 213 repairs (5.9%). Gastrointestinal complications less often developed after extent I repair than after repairs that involved infrarenal abdominal aortic segments (ie, extent II to IV repairs; P = .003). Patients who had GI complications more often underwent endarterectomy, stenting, or bypass of visceral arteries (51.2% vs 42.2%; P = .01). Use of selective visceral perfusion did not differ between groups. Patients who had GI complications had higher rates of operative mortality (34.3% vs 6.6%) and adverse events (44.1% vs 13.2%) and had longer hospitalization (29 vs 11 days; P < .001 for all). Independent predictors of GI complications included incidental splenectomy, rupture, non-extent I repair, older age, and longer aortic cross-clamp time. Short-term, midterm, and long-term survival were poorer for patients who had GI complications (P < .001).

CONCLUSIONS

Although uncommon, early GI complications after open thoracoabdominal aortic aneurysm repair are associated with significant early and late morbidity and mortality. Development of perioperative strategies to mitigate these complications is warranted.

Single-Cell Transcriptome Analysis Reveals Dynamic Cell Populations and Differential Gene Expression Patterns in Control and Aneurysmal Human Aortic Tissue

BACKGROUND

Ascending thoracic aortic aneurysm (ATAA) is caused by the progressive weakening and dilatation of the aortic wall and can lead to aortic dissection, rupture, and other life-threatening complications. To improve our understanding of ATAA pathogenesis, we aimed to comprehensively characterize the cellular composition of the ascending aortic wall and to identify molecular alterations in each cell population of human ATAA tissues.

METHODS

We performed single-cell RNA sequencing analysis of ascending aortic tissues from 11 study participants, including 8 patients with ATAA (4 women and 4 men) and 3 control subjects (2 women and 1 man). Cells extracted from aortic tissue were analyzed and categorized with single-cell RNA sequencing data to perform cluster identification. ATAA-related changes were then examined by comparing the proportions of each cell type and the gene expression profiles between ATAA and control tissues. We also examined which genes may be critical for ATAA by performing the integrative analysis of our single-cell RNA sequencing data with publicly available data from genome-wide association studies.

RESULTS

We identified 11 major cell types in human ascending aortic tissue; the high-resolution reclustering of these cells further divided them into 40 subtypes. Multiple subtypes were observed for smooth muscle cells, macrophages, and T lymphocytes, suggesting that these cells have multiple functional populations in the aortic wall. In general, ATAA tissues had fewer nonimmune cells and more immune cells, especially T lymphocytes, than control tissues did. Differential gene expression data suggested the presence of extensive mitochondrial dysfunction in ATAA tissues. In addition, integrative analysis of our single-cell RNA sequencing data with public genome-wide association study data and promoter capture Hi-C data suggested that the erythroblast transformation-specific related gene(ERG) exerts an important role in maintaining normal aortic wall function.

CONCLUSIONS

Our study provides a comprehensive evaluation of the cellular composition of the ascending aortic wall and reveals how the gene expression landscape is altered in human ATAA tissue. The information from this study makes important contributions to our understanding of ATAA formation and progression.

A Multifaceted Research Engagement Program Improved the Academic Productivity of General Surgery Residents

OBJECTIVE

Surgeon-scientists are becoming increasingly scarce, and therefore, engaging residents in research during their training is important. We evaluated whether a multifaceted research engagement program was associated with increased academic productivity of general surgery residents.

DESIGN

Our research engagement program has 4 pillars: A research requirement, a structured research curriculum, infrastructure to support residents' research, and an annual resident research day to highlight trainees' work. We compared the number of manuscripts published per chief resident during the 4 years before and after program implementation in 2013. We performed subgroup analyses to examine productivity of research track residents and clinical track residents.

SETTING

A general surgery residency program in an academic setting.

PARTICIPANTS

The participants were 57 general surgery residents (23 research track and 34 clinical track) graduating between 2010 and 2017.

RESULTS

There was a significant increase in overall research productivity, with 28 chief residents publishing an average of 2.3 ± 1.0 manuscripts before and 29 chief residents publishing an average of 8.5 ± 3.2 manuscripts after program implementation (p = 0.01). Research track residents had a nonsignificant increase in publications from an average of 6.3 ± 3.1 before to 15.4 ± 8.9 after the new program (p = 0.10). Clinical track residents had a significant increase in publications from a median of 0.9 (interquartile range: 0.5, 1.0) before to a median of 1.3 (interquartile range: 1.2, 8.6) after the new program (p = 0.03).

CONCLUSIONS

Implementation of a multifaceted research engagement program was associated with a significant increase in manuscripts published by general surgery residents, including clinical track residents. Components of our program may be of use to other programs looking to improve resident research engagement and productivity.