Long-term outcomes after aortic root replacement for bicuspid aortic valve-associated aneurysm.

OBJECTIVE: Patients with congenital bicuspid aortic valve often require root replacement. This study aims to describe their long-term rates of mortality and reoperation. METHODS: This is a multicenter retrospective study of 747 patients with bicuspid aortic valve who underwent aortic root replacement for aortic aneurysm between 2004 and 2020. Cumulative incidence curves for aortic valve and aortic reoperations were graphed. A Kaplan-Meier survival curve for the patient cohort was created alongside an age- and sex-matched curve for the US population. Multivariable Cox regression was used to determine characteristics associated with long-term mortality. RESULTS: The median age of our cohort was 54 [43-64] years old, and 101 (13.5%) patients were female. In patients with bicuspid aortic valve dysfunction, 274 (36.7%) had aortic insufficiency, 187 (25.0%) had aortic stenosis, and 142 (19.0%) had both. In-hospital mortality occurred in 10 (1.3%) patients. There were 56 aortic valve reoperations and 19 aortic reoperations, with a combined cumulative incidence of 35% (95% confidence interval [CI], 23%-46%) at 15 years. In addition, there was comparable survival between the patient cohort and the age- and sex-matched US population. Age (hazard ratio [HR], 1.04; 95% CI, 1.01-1.06), concomitant CABG (HR, 2.28; 95% CI, 1.29-4.04), and bypass time (HR, 1.01; 95% CI, 1.00-1.01) were associated with increased mortality. CONCLUSIONS: Patients who undergo aortic root replacement with bicuspid aortic valve have an increased rate of aortic reoperation (35%; 95% CI, 23%-46%) while their survival appears to be comparable to the general US population (79%; 95% CI, 73%-87%) at 15 years.

Defect turbulence in a dense suspension of polar, active swimmers.

We study the effects of inertia in dense suspensions of polar swimmers. The hydrodynamic velocity field and the polar order parameter field describe the dynamics of the suspension. We show that a dimensionless parameter R (ratio of the swimmer self-advection speed to the active stress invasion speed [Phys. Rev. X 11, 031063 (2021)2160-330810.1103/PhysRevX.11.031063]) controls the stability of an ordered swimmer suspension. For R smaller than a threshold R_{1}, perturbations grow at a rate proportional to their wave number q. Beyond R_{1} we show that the growth rate is O(q^{2}) until a second threshold R=R_{2} is reached. The suspension is stable for R>R_{2}. We perform direct numerical simulations to characterize the steady-state properties and observe defect turbulence for R

Is surgical risk of aortic arch aneurysm repair underestimated? A novel perspective based on 30-day versus 1-year mortality.

OBJECTIVES: The decision to undergo aortic aneurysm repair balances the risk of operation with the risk of aortic complications. The surgical risk is typically represented by perioperative mortality, while the aneurysmal risk relates to the 1-year risk of aortic events. We investigate the difference in 30-day and 1-year mortality after total arch replacement for aortic aneurysm. METHODS: This was an international two-centre study of 456 patients who underwent total aortic arch replacement for aneurysm between 2006 and 2020. Our primary end-point of interest was 1-year mortality. Our secondary analysis determined which variables were associated with 1-year mortality. RESULTS: The median age of patients was 65.4 years (interquartile range 55.1-71.1) and 118 (25.9%) were female. Concomitantly, 91 (20.0%) patients had either an aortic root replacement or aortic valve procedure. There was a drop in 1-year (81%, 95% confidence interval (CI) 78-85%) survival probability compared to 30-day (92%, 95% CI 90-95%) survival probability. Risk hazards regression showed the greatest risk of mortality in the first 4 months after discharge. Stroke [hazard ratio (HR) 2.54, 95% CI (1.16-5.58)], renal failure [HR 3.59 (1.78-7.25)], respiratory failure [HR 3.65 (1.79-7.42)] and reoperation for bleeding [HR 2.97 (1.36-6.46)] were associated with 1-year mortality in patients who survived 30 days. CONCLUSIONS: There is an increase in mortality up to 1 year after aortic arch replacement. This increase is prominent in the first 4 months and is associated with postoperative complications, implying the influence of surgical insult. Mortality beyond the short term may be considered in assessing surgical risk in patients who are undergoing total arch replacement.

Significance of isolated postoperative atrial fibrillation in thoracic aortic aneurysm repair.

OBJECTIVE: Although postoperative atrial fibrillation has been shown to be associated with worse survival after thoracic aortic surgery, its effect on outcomes independently from other postoperative complications is not well understood. METHODS: This is a single-center retrospective study of patients who underwent open thoracic aortic aneurysm repair between March 2005 and March 2021. Postoperative atrial fibrillation was defined as new-onset atrial fibrillation that developed during the index hospital stay. Patients with preoperative atrial fibrillation were excluded. Postoperative major complications included reoperation for bleeding, respiratory failure, acute renal failure, and stroke. Variables associated with postoperative atrial fibrillation were analyzed with multivariable regression. Survival of patients without major complications was compared between patients without atrial fibrillation and patients with postoperative atrial fibrillation after propensity score matching for baseline and intraoperative characteristics. RESULTS: Of 1454 patients, 520 (35.8%) were observed to have postoperative atrial fibrillation. Patients with postoperative atrial fibrillation had a higher rate of postoperative major complications than those without atrial fibrillation (20.2% vs 12.2%, P < .001). Ten-year survival was 82.0% in patients with postoperative atrial fibrillation and 87.0% in patients without atrial fibrillation (P = .008). In the cohort of patients without complications, 10-year survival was similar between patients with and without postoperative atrial fibrillation after propensity score matching (83.6% vs 83.8%, P = .75). CONCLUSIONS: Postoperative atrial fibrillation is common after open proximal thoracic aortic aneurysm repair. Although development of major postoperative complications is associated with postoperative atrial fibrillation and decreased long-term survival, isolated postoperative atrial fibrillation does not appear to influence long-term survival.

Reintervention after valve-sparing aortic root replacement: A comprehensive analysis of 781 David V procedures.

OBJECTIVE: Studies of reintervention after valve-sparing aortic root replacement (VSRR) are limited by sample size and failure to evaluate all types of reinterventions, including distal aorta and transcatheter interventions. In this report, reintervention after VSRR using a large patient cohort was comprehensively analyzed. METHODS: In a series involving 2 academic aortic centers, 781 consecutive patients from 2005 to 2020 undergoing David V VSRR for aortic aneurysm (91%) or dissection (9%) were included. Median age was 50 years, and 23% had a bicuspid aortic valve (AV). Median follow-up was 7.0 years. Open or transcatheter reintervention on the AV, proximal, or distal thoracic aorta was identified. Cumulative incidence was calculated, and subdistribution hazard models identified factors associated with reintervention. Time-dependent incidence of reintervention was plotted using risk-hazard functions. RESULTS: Sixty-eight reinterventions (57 open, 11 transcatheter) were performed. Reinterventions were divided by indication into degenerative AV (n = 26, including 1 transcatheter aortic valve replacement), endocarditis (n = 11), proximal aorta (n = 8), and distal aorta (n = 23, including 10 thoracic endovascular aortic repairs). Risk of reintervention for endocarditis peaked 1 to 3 years after VSRR, whereas other indications had stable, low rates of occurrence throughout the follow-up period. The cumulative incidence of reintervention was 12.5% whereas the cumulative incidence of AV reintervention was 7.0% at 10 years and was associated with residual postoperative aortic insufficiency. In-hospital mortality after reintervention was 3%. CONCLUSIONS: Reintervention rates after VSRR are relatively low in long-term follow-up and can be performed with acceptable operative risk. The majority of reinterventions are performed for indications other than AV degeneration, with the timing of reintervention varying by the specific clinical indication.

Dynamical Approach to the Jamming Problem.

A simple dynamical model, biased random organization (BRO), appears to produce configurations known as random close packing (RCP) as BRO's densest critical point in dimension d=3. We conjecture that BRO likewise produces RCP in any dimension; if so, then RCP does not exist in d=1-2 (where BRO dynamics lead to crystalline order). In d=3-5, BRO produces isostatic configurations and previously estimated RCP volume fractions 0.64, 0.46, and 0.30, respectively. For all investigated dimensions (d=2-5), we find that BRO belongs to the Manna universality class of dynamical phase transitions by measuring critical exponents associated with the steady-state activity and the long-range density fluctuations. Additionally, BRO's distribution of near contacts (gaps) displays behavior consistent with the infinite-dimensional theoretical treatment of RCP when d≥4. The association of BRO's densest critical configurations with random close packing implies that RCP's upper-critical dimension is consistent with the Manna class d_{uc}=4.

Valve-sparing aortic root replacement versus composite valve graft with bioprosthesis in patients under age 50.

BACKGROUND: Although the unique risks of implanting a prosthetic valve after aortic valve (AV) surgery in young patients are well established, studies of aortic root replacement (ARR) are lacking. We investigated long-term outcomes after valve-sparing root replacement (VSRR) versus the use of a composite valve graft with bioprosthesis (b-CVG) in patients age <50 years. METHODS: A total of 543 patients age <50 years underwent VSRR (n = 335) or b-CVG (n = 208) between 2004 and 2021 from 2 aortic centers, excluding those with dissection or endocarditis. Endpoints included mortality over time, reoperative aortic valve replacement (AVR), and development of greater than moderate aortic insufficiency (AI) or aortic stenosis (AS). Fine and Gray competing risk regression was used to compare the risk of reintervention. Propensity score matching (PSM) balanced patient comorbidities, and landmark analysis isolated outcomes beginning 4 years postoperatively. RESULTS: Compared with VSRR, b-CVG was associated with lower 12-year survival (88.6% vs 92.9%; P = .036) and a higher rate of AV reintervention (37.6% vs 12.0%; P = .018). After PSM, survival was similar in the 2 arms (93.4% for b-CVG vs 93.0% for VSRR; P = .72). However, both Fine and Gray multivariable risk regression and PSM showed that b-CVG was independently associated with AV reintervention at >4 years postoperatively (Fine and Gray: subdistribution hazard ratio, 4.3 [95% confidence interval, 1.8-10.2; P = .001]; PSM: 35.7% for b-CVG versus 14.3% for VSRR; P = .024]). PSM rates of greater than moderate AI/AS at 10 years were more than 2-fold greater in the b-CVG arm compared with the VSRR arm (37.1% vs 15.9%; P = .571). CONCLUSIONS: b-CVG in young patients is associated with early valvular degeneration, with increasing rates of reoperative AVR occurring even within 10 years. In contrast, VSRR is durable with excellent survival. In eligible young patients, every effort should be made to retain the native AV.

Reoperative aortic root replacement for prosthetic aortic valve endocarditis: impact of aortic graft.

OBJECTIVES: Existing aortic graft complicates the surgical management of prosthetic valve endocarditis (PVE); yet, its impact has not been well studied. We compared outcomes of patients with prior aortic valve replacement (AVR) versus aortic surgery plus AVR, who underwent reoperative aortic root replacement (ARR) for PVE of the aortic valve. METHODS: All patients who underwent reoperative ARR for PVE between 2004 and 2021 from 2 aortic centres were included. Two groups were formed based on the presence/absence of aortic graft: prior aortic surgery (AO) and prior AVR (AV) alone. Inverse propensity treatment weighting matched the groups. The Kaplan-Meier method was used to analyse long-term survival, and Fine and Gray model was used to compare the cumulative incidence of reoperation. RESULTS: A total of 130 patients were included (AO n = 59; AV n = 71). After matching, AO patients had increased stroke incidence (12.4% vs 0.9%) and renal failure requiring dialysis (11.5% vs 2.5%). In-hospital mortality was comparable (21.5% AO and 18.6% AV). Survival over 5 years was 68.9% (56.6-83.8%) in AO and 62.7% (48.1-81.7%) in AV (P = 0.70). The cumulative incidence of reoperation was similar [AO 6.3% (0.0-13.2%) vs AV 6.1% (0.0-15.1%), P = 0.69]. CONCLUSIONS: Reoperative ARRs for prosthetic valve/graft endocarditis are high-risk procedures. AO patients had higher incidence of postoperative morbidity versus AV patients. For all patients surviving operative intervention, survival and reoperation rates over 5 years were comparable between groups.

Bentall versus valve-sparing aortic root replacement for root pathology with moderate-to-severe aortic insufficiency: a propensity-matched analysis.

OBJECTIVES: To examine short- and long-term outcomes of patients with moderate-to-severe aortic insufficiency (AI) undergoing either a Bentall aortic root replacement (ARR) or valve-sparing root replacement (VSRR). METHODS: A two-centre retrospective database of patients undergoing ARR from 2004 to 2021 was reviewed. Patients <18 years old were excluded. A total of 1527 adult patients underwent Bentall ARR (n = 1150, 75%) or VSRR (n = 377, 25%). Propensity score matching based on preoperative comorbidities was used and 195 matched pairs were identified. Perioperative outcomes, reoperation rates, recurrence of AI and long-term survival were evaluated. RESULTS: ARR patients had more concomitant ascending aortic replacement (35% vs 20%, P = 0.002) and shorter cardiopulmonary bypass (189 vs 233 min, P < 0.0001) and aortic cross-clamp (170 vs 204 min, P < 0.0001) times than the VSRR group. Postoperatively, outcomes were similar between groups, including stroke (3% vs 2%) and in-hospital mortality (1.5% vs 2.1%), all P > 0.05. Indications for and rates of reoperation (4% vs 5%, P = 0.62) of the aortic valve and proximal aorta were similar between ARR and VSRR groups with reoperations occurring a mean of 3.2 years after initial root replacement. The ARR group had less moderate-to-severe AI than the VSRR group (1.6% vs 14%, P = 0.002) a mean of 3 years after surgery. Ten-year survival was similar between ARR (84%) and VSRR (82%) (P = 0.69) groups. CONCLUSIONS: Both ARR and VSRR can be performed with acceptable short- and long-term outcomes in patients with moderate-to-severe AI.

Valve-sparing root replacement versus composite valve graft root replacement: Analysis of more than 1500 patients from 2 aortic centers.

OBJECTIVES: The long-term outcomes comparing valve-sparing root replacement, composite valve graft with bioprosthesis, and mechanical prosthesis have yet to be explored. We investigated the long-term survival and reintervention rates after 1 of 3 major aortic root replacements in patients with tricuspid aortic valves and patients with bicuspid aortic valves. METHODS: A total of 1507 patients underwent valve-sparing root replacement (n = 700), composite valve graft with bioprosthesis (n = 703), or composite valve graft with mechanical prosthesis (n = 104) between 2004 and 2021 in 2 aortic centers, excluding those with dissection, endocarditis, stenosis, or prior aortic valve surgery. End points included mortality over time and cumulative incidence of aortic valve/proximal aorta reintervention. Multivariable Cox regression compared adjusted 12-year survival. Fine and Gray competing risk regression compared the risk and cumulative incidence of reintervention. Propensity score-matched subgroup analysis balanced the 2 major groups (composite valve graft with bioprosthesis and valve-sparing root replacement), and landmark analysis isolated outcomes beginning 4 years postoperatively. RESULTS: On multivariable analysis, both composite valve graft with bioprosthesis (hazard ratio, 1.91, P = .001) and composite valve graft with mechanical prosthesis (hazard ratio, 2.62, P = .005) showed increased 12-year mortality risk versus valve-sparing root replacement. After propensity score matching, valve-sparing root replacement displayed improved 12-year survival versus composite valve graft with bioprosthesis (87.9% vs 78.8%, P = .033). Adjusted 12-year reintervention risk in patients receiving composite valve graft with bioprosthesis or composite valve graft with mechanical prosthesis versus valve-sparing root replacement was similar (composite valve graft with bioprosthesis subdistribution hazard ratio, 1.49, P = .170) (composite valve graft with mechanical prosthesis subdistribution hazard ratio, 0.28, P = .110), with a cumulative incidence of 7% in valve-sparing root replacement, 17% in composite valve graft with bioprosthesis, and 2% in composite valve graft with mechanical prosthesis (P = .420). Landmark analysis at 4 years showed an increased incidence of late reintervention in composite valve graft with bioprosthesis versus valve-sparing root replacement (P = .008). CONCLUSIONS: Valve-sparing root replacement, composite valve graft with mechanical prosthesis, and composite valve graft with bioprosthesis demonstrated excellent 12-year survival, with valve-sparing root replacement associated with better survival. All 3 groups have low incidence of reintervention, with valve-sparing root replacement showing decreased late postoperative need for reintervention compared with composite valve graft with bioprosthesis.

Does arterial cannulation site for aortic dissection repair impact surgical outcomes?

Background: Establishing cardiopulmonary bypass remains critical to the successful repair of an acute type A aortic dissection. A recent trend away from femoral arterial cannulation has occurred in part due to concerns of stroke risk from retrograde perfusion to the brain. The purpose of this study was to determine if arterial cannulation site for aortic dissection repair impacts surgical outcomes. Methods: A retrospective chart review was performed at Rutgers Robert Wood Johnson Medical School from January 1st, 2011 to March 8th, 2021. Of the 135 patients included, 98 (73%) underwent femoral arterial cannulation, 21 (16%) axillary artery cannulation, and 16 (12%) direct aorta cannulation. The study variables included demographic data, cannulation site, and complications. Results: The mean age was 63.6±14 years, with no difference between the femoral, axillary, and direct cannulation groups. Eighty-four patients (62%) were male, with similar percentages amongst each group. The rates of bleeding, stroke, and mortality specifically due to the arterial cannulation did not significantly differ based on cannulation site. None of the patients had strokes that were attributable to cannulation type. No patients died as a direct complication of arterial access. The overall in-hospital mortality was 22%, similar between groups. Conclusions: This study found no statistically significant different in rates of stroke or other complications based on cannulation site. Femoral arterial cannulation thus remains a safe and efficient choice for arterial cannulation in the repair of acute type A aortic dissection.

Bicuspid aortic valve durability with valve-sparing aortic root replacement: comparison to tricuspid valve.

OBJECTIVES: Outcomes beyond 10 years for David V valve-sparing aortic root replacement (VSARR) in bicuspid aortic valve (BAV) patients have yet to be explored. We investigated long-term outcomes after BAV VSARR compared to VSARR for tricuspid aortic valve (TAV) patients. METHODS: A total of 677 patients with BAV (n = 171) and TAV (n = 506) underwent VSARR between 2005 and 2020 from 2 aortic centres, excluding those with dissection, endocarditis, stenosis or prior aortic valve (AV) surgery. Multivariable Cox regression compared adjusted survival over a 12-year period. Fine and Gray competing risk regression compared risk and cumulative incidence of reoperation/reintervention. Propensity score matching created balanced groups, and landmark analysis isolated outcomes beginning 4 years postoperatively. Finally, longitudinal mixed modelling assessed AV deterioration on echocardiogram. RESULTS: No difference was observed in 12-year survival of BAV versus TAV (propensity score matching 92.0% vs 89.9%, P = 0.97; multivariable hazard ratio 0.76, 95% confidence interval 0.34-1.69, P = 0.51). Adjusted 12-year cumulative incidence and risk of AV and/or proximal aorta reoperation/reintervention were not observed to be different (15.7% BAV vs 5.7% TAV, P = 0.37; subdistribution hazard ratio 1.54, 95% confidence interval 0.60-3.94, P = 0.36); however, landmark analysis showed increased incidence of late reoperation/reintervention in BAV versus TAV (11.7% vs 0.0%, P = 0.04). BAV was not associated with AV deterioration over time (BAV coefficient ± standard error: 0 ± 0.30, P = 1). CONCLUSIONS: VSARR for BAV patients has excellent 12-year survival and low reoperation/reintervention rates, which were not observed to be different from TAV patients. However, higher incidence of reoperation/reintervention was observed in the late years after BAV VSARR. Our study provides key information for surgical consultation of patients with bicuspid aortopathy.

True redo-aortic root replacement versus root replacement after any previous surgery.

Objective: The impact of previous aortic root replacement (True-Redo) versus any previous operation (Any-Redo) on outcomes after reoperative aortic root replacement (redo-ROOT) is largely unknown. In this first multi-institutional study, the clinical impact True-Redo versus Any-Redo in the setting of redo-ROOT was reviewed. Methods: From 2004 to 2021, 822 patients underwent redo-ROOT at 2 major academic centers: 638 Any-Redo and 184 True-Redo. Matching based on preoperative demographics and concomitant operations resulted in 174 matched pairs. An independent risk factor analysis was performed to determine risk factors for early and late mortality. Results: Patients in the True-Redo group were younger, at 49.9 ± 15.1 versus 55.3 ± 14.7 years, P < .001. Concomitant operations were largely similar between the 2 groups, P > .05. Median cardiopulmonary bypass time (P < .001) and aortic crossclamp time (P = .03) were longer for True-Redo group. In-hospital mortality was 13% (109) and was without significant difference between groups, P = .41. Ten-year survival was 78% versus 76% for True-Redo versus Any-Redo groups respectively, P = .7. Landmark survival analysis at 4 years' postoperatively on the matched groups found that patients in the True-Redo group had improved survival outcomes (P = .046). Risk factors of in-hospital mortality consisted of older age (P < .0001), lower ejection fraction (P = .02), and male patient (P = .0003). Conclusions: Clinical outcomes following redo-ROOT are excellent. Performance of a True-Redo-ROOT does not result in worse in-hospital morbidity or mortality and has improved survival benefit at midterm follow-up when compared with patients in the Any-Redo group. The decision to perform a redo-ROOT must be taken seriously and must be individualized in a patient-specific manner for optimal outcomes.

Model-Free Measurement of Local Entropy Production and Extractable Work in Active Matter.

Time-reversal symmetry breaking and entropy production are universal features of nonequilibrium phenomena. Despite its importance in the physics of active and living systems, the entropy production of systems with many degrees of freedom has remained of little practical significance because the high dimensionality of their state space makes it difficult to measure. Here we introduce a local measure of entropy production and a numerical protocol to estimate it. We establish a connection between the entropy production and extractability of work in a given region of the system and show how this quantity depends crucially on the degrees of freedom being tracked. We validate our approach in theory, simulation, and experiments by considering systems of active Brownian particles undergoing motility-induced phase separation, as well as active Brownian particles and E.coli in a rectifying device in which the time-reversal asymmetry of the particle dynamics couples to spatial asymmetry to reveal its effects on a macroscopic scale.

Emergent synchronization and flocking in purely repulsive self-navigating particles.

Inspired by groups of animals and robots, we study the collective dynamics of large numbers of active particles, each one trying to get to its own randomly placed target, while avoiding collisions with each other. The particles we study are repulsive homing active Brownian particles, self-propelled particles whose orientation relaxes at a finite rate towards an absorbing target in two-dimensional continuous space. For a wide range of parameters, these particles form synchronized system-wide chiral flocks, in spite of the absence of explicit alignment interactions. We show that this dramatic behavior obtains for different system sizes and density, that it is robust against the addition of noise, polydispersity, and bounding walls, and that it can exhibit dynamical topological defects. We develop an analogy to an off-lattice, ferromagnetic XY model, which allows us to interpret the different phases, as well as the topological defects.

Coupled Dynamical Phase Transitions in Driven Disk Packings.

Under the influence of oscillatory shear, a monolayer of frictional granular disks exhibits two dynamical phase transitions: a transition from an initially disordered state to an ordered crystalline state and a dynamic active-absorbing phase transition. Although there is no reason a priori for these to be at the same critical point, they are. The transitions may also be characterized by the disk trajectories, which are nontrivial loops breaking time-reversal invariance.

Relation of Community-Level Socioeconomic Status to Delayed Diagnosis of Acute Type A Aortic Dissection.

Acute type A aortic dissection requires timely diagnosis and intervention. Previous studies have examined risk factors associated with delayed diagnosis; however, the effect of socioeconomic status (SES) has not been previously studied. Our study examined the impact of various SES measures on time to diagnosis. We examined time to diagnosis in consecutive cases of acute type A aortic dissection at a single institution. SES variables included race/ethnicity, Medicaid eligibility, and residence in a zip code with an increased Distressed Communities Index-an aggregate measure of community SES. Delayed diagnosis was defined as time to diagnosis in the upper quartile of the study population (>6.6 hours). A model predicting risk factors for delayed diagnosis was created using multivariable logistic regression. Our study included 124 patients with a median time to diagnosis of 3.36 hours (interquartile range [IQR] 1.83 to 6.63). A total of 92 patients were in the nondelayed cohort (median diagnosis time of 2.59 hours, IQR 1.49 to 4.18) and 32 patients were in the delayed cohort (median diagnosis time of 15.57 hours, IQR 9.34 to 28.75). In multivariable logistic regression, residence in a high-Distressed Communities Index zip code was associated with diagnostic delay (adjusted odds ratio [aOR] 5.108, p = 0.008). Patient age (aOR 0.944, p = 0.011), chest pain at presentation (aOR 0.099, p = 0.004), back pain at presentation (aOR 0.247, p = 0.012), evidence of malperfusion syndrome (aOR 0.040, p <0.001), history of hyperlipidemia (aOR 3.507, p = 0.026), and history of congestive heart failure (aOR 0.061, p = 0.036) were also significantly associated. In conclusion, our findings suggest community-level SES affects time to diagnosis in acute type A aortic dissection.

Risk of Stroke with Impella Placement Is Not Associated with Access Vessel.

Objective: The Impella heart pump is an intravascular microaxial device that provides short-term mechanical circulatory support and can be placed through the femoral, axillary, or central vessels. One of the most feared complications is stroke. It is unclear if patient stroke risk varies based on access vessel. Methods: A retrospective review of consecutive patients who underwent Impella placement at an academic institution from January 1, 2007, through September 15, 2018, was performed. Four groups were compared: (1) minimally invasive Impella (femoral or axillary access), (2) minimally invasive Impella upgraded to another minimally invasive Impella, (3) minimally invasive Impella upgraded to a central Impella (ascending aorta), and (4) central Impella. Patient charts were reviewed to identify baseline characteristics. Outcome measures included length of stay, stroke, and mortality. Results: A total of 349 patients (or 407 Impellas) were identified, and the majority of the devices were inserted through a minimally invasive approach (n = 248, 60.9%), while the remainder were implanted via central access (n = 159, 39.1%). Minimally invasive Impellas were upgraded in 44 patients. The risk of stroke for the entire cohort was 10.3% (n = 36), with no difference observed in any particular group. Overall mortality was 44.4% (n = 155). Of the patients who initially received a minimally invasive Impella, those who were upgraded had higher rates of mortality (56.8% vs 39.4%, P = 0.03), postoperative dialysis (50.0% vs 27.4%, P < 0.01), and sepsis (43.2% vs 20.0%, P < 0.01). Conclusions: This study found no statistically significant difference in rates of postoperative stroke based on initial access vessel.

Random Close Packing as a Dynamical Phase Transition.

Sphere packing is an ancient problem. The densest packing is known to be a face-centered cubic (FCC) crystal, with space-filling fraction ϕ_{FCC}=π/sqrt[18]≈0.74. The densest "random packing," random close packing (RCP), is yet ill defined, although many experiments and simulations agree on a value ϕ_{RCP}≈0.64. We introduce a simple absorbing-state model, biased random organization (BRO), which exhibits a Manna class dynamical phase transition between absorbing and active states that has as its densest critical point ϕ_{c_{max}}≈0.64≈ϕ_{RCP} and, like other Manna class models, is hyperuniform at criticality. The configurations we obtain from BRO appear to be structurally identical to RCP configurations from other protocols. This leads us to conjecture that the highest-density absorbing state for an isotropic biased random organization model produces an ensemble of configurations that characterizes the state conventionally known as RCP.