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Changing practice to a new-generation triple-taper collared femoral component reduces periprosthetic fracture rates after primary total hip arthroplasty.

Periprosthetic femoral fracture (PPF) is a major complication following total hip arthroplasty (THA). Uncemented femoral components are widely preferred in primary THA, but are associated with higher PPF risk than cemented components. Collared components have reduced PPF rates following uncemented primary THA compared to collarless components, while maintaining similar prosthetic designs. The purpose of this study was to analyze PPF rate between collarless and collared component designs in a consecutive cohort of posterior approach THAs performed by two high-volume surgeons. This retrospective series included 1,888 uncemented primary THAs using the posterior approach performed by two surgeons (PKS, JMV) from January 2016 to December 2022. Both surgeons switched from collarless to collared components in mid-2020, which was the only change in surgical practice. Data related to component design, PPF rate, and requirement for revision surgery were collected. A total of 1,123 patients (59.5%) received a collarless femoral component and 765 (40.5%) received a collared component. PPFs were identified using medical records and radiological imaging. Fracture rates between collared and collarless components were analyzed. Power analysis confirmed 80% power of the sample to detect a significant difference in PPF rates, and a Fisher's exact test was performed to determine an association between collared and collarless component use on PPF rates. Overall, 17 PPFs occurred (0.9%). There were 16 fractures out of 1,123 collarless femoral components (1.42%) and one fracture out of 765 collared components (0.13%; p = 0.002). The majority of fractures (n = 14; 82.4%) occurred within 90 days of primary THA. There were ten reoperations for PPF with collarless components (0.89%) and one reoperation with a collared component (0.13%; p = 0.034). Collared femoral components were associated with significant decreases in PPF rate and reoperation rate for PPF compared to collarless components in uncemented primary THA. Future studies should investigate whether new-generation collared components reduce PPF rates with longer-term follow-up.

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Abstract 12925: MICU Overflow Patients in the Cardiac Intensive Care Unit: Insights From the Critical Care Cardiology Trials Network Registry

Background: The cardiac intensive care unit (CICU) is designed to manage critically ill patients (pts) with acute cardiovascular (CV) conditions, but may be the site of care for pts with non-CV critical illness when medical ICU (MICU) beds are unavailable. Methods: The Critical Care Cardiology Trials Network (CCCTN) is a multicenter registry of consecutive admissions to CICUs in North America coordinated by the TIMI Study Group. Pts with no acute or major cardiac issues were designated as MICU overflow and were compared to those admitted with acute CV illness. A generalized mixed-effect regression model was used to adjust for age, sex, Sequential Organ Failure Assessment (SOFA) score and cardiac arrest while accounting for variability among centers. Results: Among 18,006 CICU admissions, 778 (4.3%) were MICU overflow, with a range of 0% to 26% among centers. MICU overflow rates trended lower over time (Fig-A) . In comparison to admissions with acute CV illness, MICU overflow patients were younger (60.0 vs 67.0 y, p<0.001) and more likely to be female (45.6 vs 36.7%, p<0.001). Comorbidities differed markedly between the 2 groups (Fig-B) . Presentation with cardiac arrest was more common among admissions with acute CV illness (12.9% vs 4.5%, p<0.001). MICU overflow admissions had higher SOFA scores than those with acute CV illness (5.0 vs 3.0, p<0.001). Resource utilization is shown in Fig-C . ICU LOS was similar (2.0 vs 2.2d, p=0.4). MICU overflow status was associated with a trend in CICU mortality (adj-OR 1.19, 95% CI 0.93-1.53, p=0.16) and significantly higher hospital mortality (adj-OR 1.69, 95% CI 1.36-1.73, p<0.001) (Fig-D) . Conclusions: MICU overflow pts constitute a meaningful number of admissions to CICUs. These pts have more multi-system disease, greater baseline organ dysfunction, and higher hospital mortality than pts with acute CV illness. These findings reinforce the need for multidisciplinary CICU teams with expertise in all facets of critical care.

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Guanine Functionalization of SWCNTs Using Metalloporphyrin Photosensitizers

Chemical modifications of single-wall carbon nanotubes (SWCNT) have opened new areas in the creation of quantum defects and the tailoring of optical properties for these one-dimensional semiconducting materials. Recent research has revealed a novel and controllable chemical functionalization reaction in which guanine nucleobases of ssDNA coatings react covalently with the SWCNT side wall in the presence of singlet oxygen. Generation of singlet oxygen through photosensitizer optical excitation is a key part of this process. To further explore guanine functionalization of SWCNTs, we have investigated reaction kinetics under various conditions. We replaced the rose bengal photosensitizer by metalloporphyrin dyes. These have greater photostability and more intense and shorter wavelength absorptions, allowing them to be used at micro- to nanomolar concentrations and leaving a wider spectral transparency window for reaction monitoring. Excitation was at 405 nm. Our kinetic studies show that the rates of change of E11 and E22 energies depend linearly on sensitizer concentration, which implies that guanine functionalization is a first order reaction with respect to singlet oxygen. Using a series of oligos with the same length but different guanine contents, we find E11 spectral shifts that increase sub-linearly to an asymptotic value. To help understand the structure of the guanine covalent adduct, we also performed semi-empirical quantum chemistry simulations. These suggest that the lowest energy structure is bonded to two adjacent carbon atoms of the SWCNT sidewall, and that reaction exothermicity is larger for smaller diameter nanotubes. Computations will also be presented for presumed intermediate adducts of guanine peroxide bonded to (6,5) SWCNTs in different orientations relative to the nanotube axis.

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Raman Characterization of Guanine Functionalized SWCNTs

Single-walled carbon nanotubes (SWCNTs) have unique photophysical properties that render them an important class of materials for future nanoelectronics and bio-nano sensor applications. A method was recently discovered for making spatially patterned modifications to SWCNT band gaps and thereby modulating their electronic and optical properties in a controlled manner. The reaction used for this is called guanine functionalization.1 It is achieved by generating singlet oxygen in a dispersion of SWCNTs coated with single-stranded DNA, resulting in covalent bond formation between the guanine nucleobases in the DNA coatings and the nanotube sidewalls. Each of the many covalently bonded guanine sites acts as a weak exciton trap, causing red-shifted SWCNT emission and absorption spectra. Fluorescence spectroscopy shows that the extent of guanine functionalization can depend strongly on SWCNT structure, but spectral broadening can hamper the precise deconvolution of emission features of different (n,m) species. To track such covalent functionalization through Raman scattering, the D to G band ratios are commonly used as a measure of sp3 defect density and therefore of the functionalization extent. However, this conventional Raman method cannot show which (n,m) species in unsorted samples have been functionalized, because they all contribute to the D and G band signals. We will describe a novel Raman analysis based on the relative intensities of bands that have shifts located between the RBM and D regions. These Raman features are found to be diameter-specific, allowing estimation of (n,m)-resolved functionalization extents in unsorted SWCNT samples. In addition, we will present an assignment and interpretation of the relevant Raman features. Zheng, Y.; Bachilo, S. M.; Weisman, R. B., Controlled patterning of carbon nanotube energy levels by covalent DNA functionalization. ACS Nano 2019, 13, 8222-8228.

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(Invited) Kinetics of SWCNT Coating Displacement By ssDNA Depends on SWCNT Structure

Non-covalent hybrids formed by suspending single-wall carbon nanotubes (SWCNTs) in single-stranded DNA (ssDNA) present novel phenomena and suggest potential applications in biomedicine and nanotube sorting. Although the structures of these hybrids have been simulated using molecular dynamics calculations, much more experimental research is needed to understand their properties. In this study, selective interactions between SWCNTs and ssDNA are probed by measuring the kinetics by which ssDNA displaces SDS (sodium dodecyl sulfate) coatings on the nanotube surfaces. We used samples initially suspended in a low concentration of SDS to allow the coating displacement to occur and to suppress formation of free SDS micelles. The displacement process was monitored by time-dependent measurements of SWCNT fluorescence intensities and wavelengths. Our experiments showed very smooth decreases in fluorescence intensity and red-shifts in fluorescence wavelengths during the displacement process. Through a series of measurements, we found that ssDNA sequences with repeated guanine (G) and thymine (T) bases showed systematic patterns in the coating displacement kinetics. One result is that SDS displacement depends strongly on oligo length, with (GT)3 showing an initial rate constant 500 times greater than that of (GT)20. For shorter oligos in the (GT) n series, we observe an inverse dependence of initial rate constant on SWCNT diameter, with SDS displacement from (6,5) more than twice as fast as from (8,7). However, this diameter dependence is not present for (GT) n oligos with n greater than 6. We also find a distinct and systematic dependence of initial rate constant on nanotube chiral angle for (GT)5 and (GT)6. This effect gives a factor of ~3 difference between (9,1) and (6,5) despite their identical diameters. We empirically find these initial rate constants to vary as (SWCNT diameter)-4(cos 3θ)-y with y = -1/2 for (GT)5 and -1 for (GT)6. In addition, the full displacement kinetic traces are well fitted by double exponential kinetics, with rate constants and amplitudes dependent on SWCNT diameter. A two-step kinetic model for the displacement process will be presented to account for these findings.

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Abstract TP6: Recanalization Of Large Vessel Occlusion After Intravenous Alteplase Therapy In Acute Ischemic Stroke Patients Transferred From Primary Stroke Centers

Background and Purpose: Early recanalization of occluded intracranial arteries predicts favorable outcome in acute ischemic stroke (AIS) patients treated with intravenous alteplase therapy within 4.5 hours from stroke onset. Prior studies have shown recanalization of large vessel occlusion (LVO) with alteplase ranging from 0% for internal carotid artery and 33% for distal blood vessels. We performed an analysis to examine the characteristics of stroke patients and the location of LVO that predicts early recanalization in patients treated with intravenous alteplase alone. Methods: This single-center, retrospective study solely included AIS patients with LVO who were transferred to our institution for mechanical thrombectomy evaluation after treated with alteplase at a primary stroke center between January 2019 and January 2021. Recanalization was identified by repeated computed tomographic angiography (CTA) or digital subtraction angiography (DSA) at our institution upon arrival. Results: One hundred and six patients were included in the analysis, 15 (14.1%) patients had partial or complete recanalization of LVO. Cardioembolic was the most common cause of ischemic stroke (46%), followed by large vessel atherosclerosis (33%) in this group. They were more likely to have a medical history of hypertension (73.3% vs. 59.3%), better baseline function as measured by pre-modified Rankin Score 0-2 (73.3% vs. 68.1%), and receive early treatment (105 minutes vs. 135 minutes), compared to their counterparts with no recanalization. Proximal and distal middle cerebral artery had the same rate of recanalization in this cohort. Conclusion: The highest incidence of early recanalization of occluded intracranial arteries was found in cardioembolic strokes with middle cerebral artery being the most common location of recanalization. Early recanalization with intravenous alteplase was also associated with improved functional recovery at discharge.

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Abstract 12026: A Case of Eosinophilic Endomyocarditis in a Patient With Eosinophilic Leukemia and Hypereosinophilic Syndrome

Background: Eosinophilic (Loeffler’s) endomyocarditis is a restrictive cardiomyopathy caused by eosinophilic infiltration of myocardial. Complications include arrhythmias, intraventricular thrombus formation, and acute heart failure. Clinical Presentation A 37-year-old man with no past medical history presented with two weeks of fatigue and exertional dyspnea. He was found to have acute eosinophilic leukemia with a total white blood cell count of 440 k/mm^3 with 14% myelocytes, hypereosinophilic syndrome with an absolute eosinophil count of 56 k/mm^3, severe anemia and thrombocytopenia. Bone marrow biopsy and peripheral blood FISH analysis confirmed eosinophilic leukemia. He subsequently underwent leukopheresis, followed by treatment with hydroxyurea and imatinib. Cardiac Evaluation Echocardiogram revealed endomyocardial thickening of the left ventricular apex (Figure 1A). Cardiac MRI revealed left ventricular apical subendocardial wall thickness of 16 mm with subendocardial late gadolinium enhancement consistent with endomyocardial fibrosis (Figure 1B). The average global T1 value was 1100 ms and the calculated extracellular volume was 35%. MRI also revealed an apical left ventricular thrombus. The patient was treated with pulse dose of steroids in addition to the cancer-specific regimen. He did not initially receive anticoagulation due to severe anemia and thrombocytopenia. Subsequent echocardiography after three months of treatment revealed complete resolution of endomyocardial thickening and no evidence of a left ventricular thrombus. He had resolution of peripheral leukocytosis, hypereosinophilia, anemia, and thrombocytopenia. Conclusion This case presents the diagnosis and multidisciplinary management of eosinophilic endomyocarditis related to eosinophilic leukemia. Complete clinical and echocardiographic resolution was achieve following treatment with pulse-dose steroids and a cancer-specific regimen.

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Abstract 14873: Analysis of Heart Failure Re-Admissions and In-Hospital Outcomes in Patients With Takotsubo Syndrome

Background: Takotsubo Syndrome (TTS) is characterized by transient reduction in left ventricular function with in the absence of obstructive coronary artery disease. Clinical presentation often mimics acute myocardial infarction (AMI). Patients with TTS have comparable long-term mortality with AMI patients. However, data on the burden of heart failure (HF) readmissions in patients with TTS are scarce. Methods: This retrospective analysis utilized the US Nationwide Readmission Database for the years 2012-2019 to identify hospitalizations for TTS or AMI. The primary outcome of interest was 6-month readmission due to HF. Secondary outcomes included in-hospital mortality. Results: There were 30,926 hospitalizations with TTS and 2,535,025 hospitalizations with AMI. The proportion of women was 90% among TTS patients and 37.7% among AMI patients (p<0.001). Overall comorbidities were similar between the two groups, but in-hospital mortality during index admission was higher in the AMI arm (6.5% vs 1.5% in TTS, p <0.01) accompanied with increased in-hospital complications. All-cause readmission rates were lower among TTS than among AMI patients (21.9% vs. 29.4%; p <0.01). HF readmissions were also lower among TTS than AMI patients (3.7% vs. 6.7%; p <0.01). After propensity matching, all-cause readmission rate remained lower among TTS than among AMI patients (21.9% vs. 27.9%; p <0.01). HF hospital readmissions rates were also lower among TTS patients (3.7% vs 5.7%; p <0.01). Independent predictors of HF readmission in TTS population included comorbidities such as diabetes mellitus, atrial fibrillation, chronic kidney disease, peripheral vascular disease, and chronic pulmonary disease. Conclusion A substantial proportion of patients (>20%) with TTS suffer a hospital readmission within 6 months, although less than 5% are readmitted with HF. Compared with AMI, all-cause and HF readmission rates are lower in TTS patients.

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Abstract 14807: Effect of Psychiatric Illnesses on the Stress Induced Cardiomyopathy Readmission

Introduction: Stress-induced cardiomyopathy (SIC) is a form of transient non-ischemic cardiomyopathy that is precipitated in the setting of acute emotional or physical stress. Postulated hypothesis implicated catecholaminergic excess and a role of the brain-heart axis behind its pathogenesis. The impact of different psychiatric illnesses on the outcomes of SIC is not clear. Method: We conducted a retrospective study using National Readmission Database (NRD) from 2011 to 2019 using ICD-10-CM (International Classification of Diseases, 10th Edition, Clinical Modification) and ICD-9-CM codes to identify the admissions with the discharge diagnosis of SIC and stratified them based on the presence of psychiatric illnesses. The primary outcome was six-month readmission and predictors of readmission. Result: We included a total of 98,721 admissions with a diagnosis of SIC. Among them, 12.9% had major depression, 1.8% had bipolar disorder, 17.6% had an anxiety disorder, and 0.6% had schizophrenia. Overall, patients with psychiatric illnesses were younger. Patients with psychiatric illnesses had a higher burden of comorbidities. Patients with schizophrenia had higher in-hospital mortality. Patients with psychiatric illnesses had a higher likelihood of getting readmitted within six months (p<0.001). The significant independent positive predictors of readmission within 6 months were history of diabetes [odds ratio (OR):1.21, confidence interval (CI):1.16-1.26], heart failure (OR:1.31, CI:1.26-1.36), CKD/ESRD (OR: 1.44, CI:1.37-1.51), AF (OR: 1.25, CI:1.20-1.31), anemia (OR:1.24, CI: 1.15-1.34), peripheral arterial disease (OR: 1.25, CI:1.18-1.33), chronic obstructive pulmonary disease (OR: 1.35, CI:1.29-1.40), and prior stroke (OR: 1.10, CI: 1.02-1.18). Conclusion: We witnessed that psychiatric illnesses were associated with a higher likelihood of six-month readmission in patients with SIC.

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