External Validation of the ARCH Score in Patients Undergoing Aortic Arch Reconstruction Under Circulatory Arrest.

BACKGROUND: Aortic arch surgery with hypothermic circulatory arrest (HCA) carries a higher risk of morbidity and mortality compared to routine cardiac surgical procedures. The newly developed ARCH score (Arch Reconstruction under Circulatory arrest with Hypothermia) has not been externally validated. We sought to externally validate this score in our local population. METHODS: All consecutive open aortic arch surgeries with HCA from 2014-2023 were included. Univariable and multivariable analyses were performed. Model discrimination was assessed by C-statistic with 95% confidence intervals as part of the Receiver Operating Characteristic (ROC) analysis. Model performance was visualized by calibration plot and quantified by the Brier score. RESULTS: A total of 760 patients were included. The mean age was 61 years (±13.6) with 56.4% of patients over the age of 60 years; 38.3% were females. The procedures were carried out mostly emergently or urgently (59.6%). Total arch replacement was performed in 32.5% of patients while aortic root procedures were carried out in 74.6% of patients. In-hospital death was observed in 64 (8.4%) patients while stroke was present in 5.4%. The C-statistic revealed low discriminatory ability for predicting in-hospital mortality (area under the ROC curve 0.62; 95%CI 0.54-0.69; p=0.002); however, the model calibration was found to be excellent (Brier score of 0.07). CONCLUSION: The ARCH score for in-hospital mortality showed low discriminatory ability in our local population although with excellent ability for prediction of mortality.

Acute Aortic Dissection after Transcatheter Aortic Valve Replacement.

Acute aortic dissection (AAD) is a rare and potentially fatal complication associated with transcatheter aortic valve replacement (TAVR). Due to the paucity of existing institutional data, we sought to assess the incidence of post-implant AAD in patients who underwent TAVR at a single institution. All patients who underwent TAVR from 2013 - 2022 were retrospectively reviewed to identify patients who possessed clinical or radiologic evidence of post-TAVR AAD. Follow-up and survival data were retrieved for all included patients. A total of 4317 patients underwent TAVR, of which 9 (0.2%) sustained an AAD. These patients had a mean age of 80 (range 53 - 92) years, mean STS 30-day mortality risk of 5.7% (2.4-16.7%), and mean effective aortic valve area of 0.8 (0.4-1.5) cm2. Preoperative maximum aortic diameter was 3.9 (2.6-4) cm. Of these 9 patients, 6 (67%) showed evidence of Stanford type A dissection, while 3 (33%) were diagnosed with Stanford type B dissection. The most common causes of dissection were posterior annular rupture by the transcatheter valve (THV) (44%) and THV embolization or "pop-out" into the ascending aorta (22%). A total of six (66.7%) patients, comprised of five (55.6%) type A and one (11.1%) type B aortic dissections, died within 30 days of AAD. The median time to follow-up in those surviving TAVR with intra-operative AAD was 1042 (range: 648-2666) days. Surviving patients were managed via thoracic endovascular aortic repair (TEVAR) and medical management. In conclusion, in this highly selected cohort of patients, our experience demonstrates that AAD following TAVR is a rare, but often lethal, intraprocedural sequelae of THV implantation, especially in cases of type A aortic dissection.

High-Index NiO Particle Synthesis in Alkali Chloride Salts: Nonclassical Crystallization Pathways and Thermally-Induced Surface Restructuring.

The formation mechanism(s) of high-index facets in metal oxides is not widely understood but remains a topic of interest owing to the challenges of stabilizing high-energy surfaces. These metal oxide crystal surfaces are expected to provide unique physicochemical characteristics; therefore, understanding crystallization pathways may enable the rational design of materials with controlled properties. Here the crystallization of NiO via thermal decomposition of a nickel source in excess of alkali chlorides is examined, focusing on KCl, which produces trapezohedral NiO (311) particles that are difficult to achieve through alternative methods. Trapezohedral NiO crystals are confirmed to grow via a molten eutectic where NiO nucleation is followed by nonclassical crystallization through processes resembling colloidal assembly. Aggregates comprised of NiO nanocrystals form mesostructures that ripen with heating time and exhibit fewer grain boundaries as they transition into single-crystalline particles. At temperatures higher than those of NiO crystallization, there is a restructuring of (311) facets into microfacets exposing (111) and (100) surfaces. These findings illustrate the complex crystallization processes taking place during molten salt synthesis. The ability to generate metal oxide particles with high-index facets has the potential to be a more generalized approach to unlock the physicochemical properties of materials for diverse applications.

Outcomes of Valve-in-Valve Transcatheter Aortic Valve Replacement.

Structural valve degeneration is increasingly seen given the higher rates of bioprosthetic heart valve use for surgical and transcatheter aortic valve replacement (TAVR). Valve-in-valve TAVR (VIV-TAVR) is an attractive alternate for patients who are otherwise at high risk for reoperative surgery. We compared patients who underwent VIV-TAVR and native valve TAVR through a retrospective analysis of our institutional transcatheter valve therapy (TVT) database from 2013 to 2022. Patients who underwent either a native valve TAVR or VIV-TAVR were included. VIV-TAVR was defined as TAVR in patients who underwent a previous surgical aortic valve replacement. Kaplan-Meier survival analysis was used to obtain survival estimates. A Cox proportional hazards regression model was used for the multivariable analysis of mortality. A total of 3,532 patients underwent TAVR, of whom 198 (5.6%) underwent VIV-TAVR. Patients in the VIV-TAVR cohort were younger than patients who underwent native valve TAVR (79.5 vs 84 years, p <0.001), with comparable number of women and a higher Society of Thoracic Surgeons risk score (6.28 vs 4.46, p <0.001). The VIV-TAVR cohort had a higher incidence of major vascular complications (2.5% vs 0.8%, p = 0.008) but lower incidence of permanent pacemaker placement (2.5% vs 8.1%, p = 0.004). The incidence of stroke was comparable between the groups (VIV-TAVR 2.5% vs native TAVR 2.4%, p = 0.911). The 30-day readmission rates (VIV-TAVR 7.1% vs native TAVR 9%, p = 0.348), as well as in-hospital (VIV-TAVR 2% vs native TAVR 1.4%, p = 0.46), and overall (VIV-TAVR 26.3% vs native TAVR 30.8%, p = 0.18) mortality at a follow-up of 1.8 years (0.83 to 3.5) were comparable between the groups. The survival estimates were also comparable between the groups (log-rank p = 0.27). On multivariable Cox regression analysis, VIV-TAVR was associated with decreased hazards of death (hazard ratio 0.68 [0.5 to 0.9], p = 0.02). In conclusion, VIV-TAVR is a feasible and safe strategy for high-risk patients with bioprosthetic valve failure. There may be potentially higher short-term morbidity with VIV-TAVR, with no overt impact on survival.

Radial artery vs right internal mammary artery as a second conduit during coronary artery bypass grafting.

OBJECTIVE: To compare the clinical outcomes of radial artery (RA) grafts during CABG to those of right internal mammary artery (RIMA) grafts. METHODS: This was a retrospective, single-institution cohort study of isolated CABG with multiple grafts between 2010-2022. To balance graft cohorts, propensity score matching (PSM) was performed using a 1:1 match ratio. Long-term postoperative survival was compared among RA and RIMA groups. Similarly, major adverse cardiac and cerebrovascular events (MACCE) were compared among both cohorts, with MACCE comprising death, myocardial infarction (MI), coronary revascularization, and stroke. Kaplan-Meier estimation was performed for mortality, while cumulative incidence estimation was utilized for MACCE. RESULTS: A total of 8,774 patients underwent CABG. Of those, 1,674 (19.1%) patients who underwent multiarterial CABG were included in this analysis. 326 (19.5%) patients received RA grafts and 1,348 (80.5%) received RIMA grafts. PSM yielded a cohort of 323 RA patients and 323 RIMA patients. After matching, groups were well-balanced across all baseline variables. No significant differences were observed in immediate postoperative complications or long-term survival, with 5-year survival estimates of 89.5% for the RA group vs 90.1% for the RIMA group. There was a nonsignificant trend toward a higher incidence of MACCE at 5 years in the RA group compared to the RIMA group (31.3% in the RA group vs 24.1% in the RIMA group), especially after 1-year follow-up (21.6% in the RA group vs 15.1% in the RIMA group). Specifically, for RA patients, there were higher rates of repeat revascularization in the 5-year postoperative period (14.7% in the RA group vs 5.3% in the RIMA group), particularly in the territory revascularized by the RA during the index operation (45.7% in the RA group vs 10.3% in the RIMA group). CONCLUSION: Overall, RA and RIMA secondary conduits for CABG were associated with comparable immediate postoperative complications, 5-year MACCE, and 5-year survival after PSM. RA grafting was associated with significantly higher rates of repeat coronary revascularization at 5 years, specifically in the territory revascularized by the RA during the index operation.

Outcomes of Radial Artery Versus Saphenous Vein as A Second Conduit After Coronary Artery Bypass Grafting.

Despite the advantages of multiarterial grafting, saphenous vein (SV) configurations predominate in coronary artery bypass grafting (CABG). In addition, the benefits of radial artery (RA) utilization in multivessel CABG remain unclear. This study aims to compare the clinical outcomes of patients who received RA grafts during CABG with those of patients who received SV grafts. A retrospective, single-institution cohort study was performed in 8,774 adults who underwent isolated CABG surgery with multiple grafts between 2010 and 2022. To balance graft cohorts, propensity score matching (PSM) was performed using a 1:2 (RA/SV) match ratio. Long-term postoperative survival was compared in RA and SV graft groups. Similarly, major adverse cardiac and cerebrovascular event (MACCE) rates were compared in the cohorts, with MACCE comprising death, myocardial infarction (MI), coronary revascularization, and stroke. Kaplan-Meier estimation was performed for both mortality and MACCE. A total of 7,218 patients (82.3%) who underwent multivessel CABG were included in this analysis. Of these patients, 341 (4.7%) received RA grafts, and 6,877 (95.3%) received SV grafts secondary to left internal mammary artery use. PSM yielded a cohort of 335 patients with RA and 670 patients with SV. After matching, groups were well balanced across all baseline variables. No significant differences were observed in either immediate postoperative morbidities or long-term survival. However, Kaplan-Meier estimates of long-term postoperative freedom from MACCE were significantly greater in matched patients with SV (73.3%) than in those with RA (67.4%) (p = 0.044, cluster log-rank), with patients with SV also possessing significantly greater freedom from coronary revascularization and MI. In conclusion, RA and SV secondary conduits for CABG were associated with comparable immediate postoperative complications and long-term survival after PSM. SV grafting was associated with significantly decreased rates of postoperative MACCE, likely owing to lower rates of coronary revascularization and MI than in RA grafting.

Long-Term Outcomes of Valve-in-Valve Transcatheter Aortic Valve Implantation Versus Redo Surgical Aortic Valve Replacement: Meta-Analysis of Kaplan-Meier-Derived Data.

Valve-in-valve (ViV) transcatheter aortic valve implantation (ViV-TAVI) in patients with failed bioprostheses arose as an alternative to redo surgical aortic valve replacement (SAVR). To evaluate all-cause mortality in ViV-TAVI versus redo-SAVR, we performed a study-level meta-analysis of reconstructed time-to-event data from Kaplan-Meier curves of nonrandomized studies published by August 2023. A total of 16 studies met our eligibility criteria, with a total of 4,373 patients (2,204 patients underwent ViV-TAVI and 2,169 patients underwent redo-SAVR). Pooling all the studies, ViV-TAVI showed a lower risk of all-cause mortality in the first 6 months (hazard ratio [HR] 0.58, 95% confidence interval [CI] 0.46 to 0.73, p <0.001), with an HR reversal after this time point favoring redo-SAVR (HR 1.92, 95% CI 1.58 to 2.33, p <0.001). Pooling only the matched populations (which represented 64.6% of the overall population), ViV-TAVI showed a lower risk of all-cause mortality in the first 6 months (HR 0.56, 95% CI 0.43 to 0.73, p <0.001], with a reversal after 6 months favoring redo-SAVR (HR 1.55, 95% CI 1.25 to 1.93, p <0.001). The meta-regression analyses revealed a modulating effect of the following covariates: age, coronary artery disease, history of coronary artery bypass graft surgery, and implanted valves <25 mm. In conclusion, ViV-TAVI is associated with better survival immediately after the procedure than redo-SAVR; however, this primary advantage reverses over time, and redo-SAVR seems to offer better survival at a later stage. Because these results are pooled data from observational studies, they should be interpreted with caution, and randomized controlled trials are warranted.

Self-Expanding Transcatheter Aortic Valves Optimize Transvalvular Hemodynamics Independent of Intra- Versus Supra-Annular Design.

This study sought to characterize transvalvular hemodynamics during the first 30 days after transcatheter aortic valve implantation (TAVI) across various transcatheter heart valves (THVs), while adjusting for annular dimensions. This was an observational study of TAVIs from September 2021 to October 2022. The primary outcome was mean transvalvular pressure gradient (TVPG), measured using transthoracic echocardiography at day 0, day 1, and day 30 post-TAVI, and were compared across 3 THV, including the self-expandable intra-annular Portico (Abbott Vascular, Santa Clara, California) valve, the balloon-expandable SAPIEN 3 Ultra (Edwards Lifesciences, Irvine, California), and the self-expandable supra-annular Evolut Pro+ (Medtronic, Minneapolis, Minnesota). A total of 560 patients who underwent TAVI were identified, of which 106 (18.9%) received a Portico THV, 176 (31.4%) received a SAPIEN THV, and 278 (49.6%) received an Evolut THV. For Portico THV, the TVPG on day 0 increased from 6.0 (4.7 to 9.0) to 7.0 (6.0 to 10.0) by day 30 (p = 0.009). For SAPIEN THV, the TVPG on day 0 increased from 6.5 (5.0 to 8.0) to 12.0 (9.0 to 15.0) by day 30 (p <0.001). For Evolut THV, the TVPG on day 0 increased from 6.0 (5.0 to 9.0) to 7.2 (5.0 to 10.0) by day 30 (p = 0.001). Adjusting for time and annular diameter in a multivariable mixed effects model, the SAPIEN group had a significantly greater increase in TVPG over time than the Evolut reference group (p <0.001), while there was no difference in the change of TVPG over time for the Portico group vs. the Evolut group (p = 0.874). In conclusion, compared with balloon-expandable valves, self-expanding THV may optimize transvalvular hemodynamics across all annular diameters, independent of their supra-annular and intra-annular design.

Valve-in-valve transcatheter aortic valve replacement versus isolated redo surgical aortic valve replacement.

OBJECTIVE: To compare outcomes of patients undergoing valve-in-valve transcatheter aortic valve replacement (ViV TAVR) versus redo surgical aortic valve replacement (SAVR). METHODS: This was a retrospective study using institutional databases of transcatheter (2013-2022) and surgical (2011-2022) aortic valve replacements. Patients who underwent ViV TAVR were compared with patients who underwent redo isolated SAVR. Clinical and echocardiographic outcomes were analyzed. Kaplan-Meier survival estimation and Cox regression were performed. Cumulative incidence functions were generated for heart failure readmissions. RESULTS: A total of 4200 TAVRs and 2306 isolated SAVRs were performed. Of these, there were 198 patients who underwent ViV TAVR and 147 patients who underwent redo SAVR. Operative mortality was 2% in each group, but observed to expected operative mortality in the redo SAVR group was higher than in the ViV TAVR group (1.2 vs 0.32). Those who underwent redo SAVR were more likely to require transfusions and reoperation for bleeding, to have new-onset renal failure requiring dialysis, and to require a permanent pacemaker postoperatively than those in the ViV group. Mean gradient was significantly lower in the redo SAVR group than in the ViV group at 30 days and 1 year. Kaplan-Meier survival estimates at 1 year were comparable, and on multivariable Cox regression, ViV TAVR was not significantly associated with an increased hazard of death compared with redo SAVR (hazard ratio, 1.39; 95% CI, 0.65-2.99; P = .40). Competing-risk cumulative incidence estimates for heart-failure readmissions were higher in the ViV cohort. CONCLUSIONS: ViV TAVR and redo SAVR were associated with comparable mortality. Patients who underwent redo SAVR had lower postoperative mean gradients and greater freedom from heart failure readmissions, but they also had more postoperative complications than the VIV group, despite their lower baseline risk profiles.

Using cardiovascular risk indices to predict mortality in Covid-19 patients with acute respiratory distress syndrome: a cross sectional study.

Covid-19 patients who require admission to an intensive care unit (ICU) have a higher risk of mortality. Several risk factors for severe Covid-19 infection have been identified, including cardiovascular risk factors. Therefore, the aim was to investigate the association between cardiovascular (CV) risk and major adverse cardiovascular events (MACE) and mortality of Covid-19 ARDS patients admitted to an ICU. A prospective cross-sectional study was conducted in a university hospital in Graz, Austria. Covid-19 patients who were admitted to an ICU with a paO2/fiO2 ratio < 300 were included in this study. Standard lipid profile was measured at ICU admission to determine CV risk. 31 patients with a mean age of 68 years were recruited, CV risk was stratified using Framingham-, Procam- and Charlson Comorbidity Index (CCI) score. A total of 10 (32.3%) patients died within 30 days, 8 patients (25.8%) suffered from MACE during ICU stay. CV risk represented by Framingham-, Procam- or CCI score was not associated with higher rates of MACE. Nevertheless, higher CV risk represented by Procam score was significantly associated with 30- day mortality (13.1 vs. 6.8, p = 0.034). These findings suggest that the Procam score might be useful to estimate the prognosis of Covid-19 ARDS patients.

Comparison of Corneal Power Difference Maps with Achieved Myopic Correction Using Scheimpflug Tomography After LASIK, PRK, and SMILE.

Purpose: To compare corneal power difference maps (∆maps) obtained from the Pentacam in patients with 1 year follow-up after LASIK, PRK, and SMILE with further stratification to low, moderate, and high myopia. Patients and methods: This retrospective study was comprised of patients who had preoperative and 1-year postoperative power maps that were obtained-front sagittal (SagF), refractive power (RP), true net power (TNP), and total corneal refractive power (TCRP)-for evaluation. Measurements were recorded and compared at the 4mm, 5mm and 6mm pupil and apex zones. Comparisons were made between each specific power ∆map and the surgically induced refractive change (SIRC). Further analysis of the ∆maps was performed based on degree of myopia (high, moderate, and low). Correlation and agreement were also assessed with regression and limits of agreement (LoA). Results: There were 172 eyes in the LASIK group, 187 eyes in the PRK group, and 46 eyes in the SMILE group. In the LASIK group, TNP ∆map at 5mm pupil zone had the least absolute mean difference with SIRC (0.007 ± 0.42D). In the PRK group, TNP ∆map at 5mm apex zone was most accurate compared to SIRC (0.066 ± 0.45D). In the SMILE group, TCRP ∆map at 4mm apex zone had the closest absolute value when compared to SIRC (0.011 ± 0.50D). There was good correlation and agreement for all three surgery groups, LASIK: r = 0.975, LoA -0.83D to +0.83D, PRK: r = 0.96, LoA -0.83D and +0.95D, and SMILE: r = 0.922, LoA -0.97 D to +0.99D. Conclusion: TNP ∆maps most accurately measured corneal power in the LASIK and PRK groups while TCRP ∆maps were most accurate in the SMILE group. The degree of myopia may change which ∆map is most accurate.

Outcomes of Transcatheter Aortic Valve Replacement in Patients With Concomitant Aortic Regurgitation.

BACKGROUND: This study sought to evaluate outcomes of transcatheter aortic valve replacement (TAVR) in patients with moderate or greater aortic regurgitation (AR). METHODS: This was an observational study using an institutional database of TAVRs from November 2012 to April 2022. The study compared outcomes of TAVR in patients with isolated aortic stenosis (AS) vs patients with AS and concomitant AR (moderate or greater). Those patients with trace or mild AR were excluded. Clinical and echocardiographic outcomes were compared, with end points established by the Valve Academic Research Consortium 3. Kaplan-Meier survival estimation and Cox regression for mortality were performed. Competing-risk cumulative incidence estimates for heart failure readmissions were also compared. RESULTS: Of 3295 patients, 605 (53.4%) had severe AS with no AR and 529 (46.6%) had severe AS with moderate or severe AR. There were no significant differences in in-hospital mortality, length of stay, stroke, myocardial infarction, permanent pacemaker requirement, transfusion requirement, minor or major vascular complications, or 30-day readmissions between the 2 groups (P > .05). There were also no significant differences in annular dissection or rupture, coronary obstruction, or device embolization. Mean gradient and paravalvular leak rates at 30 days and 1 year were similar between the groups. Survival estimates were comparable, and, on multivariable Cox regression, mixed aortic valvular disease was not associated with an increased hazard of death as compared with isolated AS (hazard ratio, 1.01; 95% CI, 0.81-1.25; P = .962). Cumulative incidence estimates for heart failure readmissions were comparable between groups. CONCLUSIONS: TAVR can be safely performed in patients with mixed valvular disease, with outcomes comparable to those in isolated AS.

COBRA: COde Blue Retrospective Audit in a metropolitan hospital.

BACKGROUND: Inhospital cardiac arrest (IHCA) is an uncommon but challenging problem. AIMS: To investigate the management and outcomes of IHCA, and to investigate the effect of introducing a medical emergency team (MET) on IHCA prevalence. METHODS: Retrospective medical record review of 176 adult IHCA episodes at Box Hill Hospital, a university-affiliated public hospital in metropolitan Melbourne, from July 2012 to June 2017. Inpatients receiving cardiopulmonary resuscitation for IHCA, in inpatient wards, intensive care unit, cardiac catheterisation laboratory and operating theatres were included. Data collected included demographics, resuscitation management and outcomes. Average treatment effect (ATE) was derived from margins estimates and linear regression fitted to hospital outcome, adjusted for IHCA factors. An exponentially weighed moving average control chart was used to explore IHCA prevalence over time. RESULTS: There were 65.3% of IHCA patients who died in hospital. IHCA prevalence was unchanged after the introduction of a dedicated MET service. Factors associated with higher likelihood of survival to discharge were initial cardiac of rhythm ventricular tachycardia (VT) (ATE 0.10 (95% CI = -0.03 to 0.25)) or ventricular fibrillation (VF) (ATE 0.28 (95% CI = 0.11-0.46)), cardiac monitoring at the time of arrest (ATE 0.06 (95%CI = -0.04 to 0.16)) and time to return of spontaneous circulation (ATE 0.023 (95% CI = 0.015-0.031)). CONCLUSIONS: IHCA is uncommon and is associated with high mortality. IHCA prevalence was unchanged after the introduction of a dedicated MET service. Factors associated with improved survival to hospital discharge were initial rhythm VT or VF, cardiac monitoring and shorter resuscitation times.

The Relationship Between Exacerbation of Pachymeningitis and Chemotherapy: A Case Report.

Pachymeningitis is a rare disorder that involves the dura mater of the cranial and spinal nerves. It can lead to localized or diffuse thickening of the dura mater as an inflammatory reaction. Very little is known about this uncommon disease, and even less is known about its exacerbating factors and relationship with chemotherapy. In this report, we present a case of an 86-year-old man with metastatic bladder carcinoma on chemotherapy who experienced worsening pachymeningitis with symptoms such as headache, aphasia, weakness, and seizures. The patient responded well to steroids, and his symptoms improved. This association between exacerbation of pachymeningitis and chemotherapy is rarely encountered, and its mechanism of action is poorly understood. We hope this case report will add to the existing literature on this uncommon phenomenon and its exacerbating factors.

Pace of passive margin tectonism revealed by U-Pb dating of fracture-filling calcite.

A growing body of evidence demonstrates that Atlantic-style passive margins have experienced episodes of uplift and volcanism in response to changes in mantle circulation long after cessation of rifting. Passive margins are thus an attractive archive from which to retrieve records of mantle circulation and lithospheric alteration. However, this archive remains under-utilized due to difficulty in deciphering the surficial records of passive margin tectonism and linking them to seismic velocity structure. Here we present a new approach to unraveling the tectonic history of passive margins using U-Pb dating of calcite in faults and fractures along the eastern North American margin. These ages show a 40 Myr long period of continuous fracturing and faulting from ~115 to 75 Ma followed by another episode in Mio-Pliocene time. We argue that the former event represents a response to Cretaceous lithospheric alteration whereas the latter records development of modern relief in the northern Appalachians.

Local Ordering of Molten Salts at NiO Crystal Interfaces Promotes High-Index Faceting.

Given the strong influence of surface structure on the reactivity of heterogeneous catalysts, understanding the mechanisms that control crystal morphology is an important component of designing catalytic materials with targeted shape and functionality. Herein, we employ density functional theory to examine the impact of growth media on NiO crystal faceting in line with experimental findings, showing that molten-salt synthesis in alkali chlorides (KCl, LiCl, and NaCl) imposes shape selectivity on NiO particles. We find that the production of NiO octahedra is attributed to the dissociative adsorption of H2 O, whereas the formation of trapezohedral particles is associated with the control of the growth kinetics exerted by ordered salt structures on high-index facets. To our knowledge, this is the first observation that growth inhibition of metal-oxide facets occurs by a localized ordering of molten salts at the crystal-solvent interface. These findings provide new molecular-level insight on kinetics and thermodynamics of molten-salt synthesis as a predictive route to shape-engineer metal-oxide crystals.

Incidence, Risk, and Visual Outcomes after Repositioning of Acute Non-Traumatic Flap Dislocations Following Femtosecond-Assisted LASIK.

Although the use of femtosecond lasers instead of mechanical devices has decreased the incidence of flap complications following laser-assisted in situ keratomileusis (LASIK), dislocations and striae still occur. Flap repositioning is an effective intervention to improve visual outcomes after acute flap complications in both microkeratome-assisted and femtosecond-assisted LASIK. This retrospective case series included patients undergoing flap repositioning secondary to acute flap dislocation and/or visually significant striae within the first two weeks following femtosecond LASIK (FS-LASIK) from 2015 to 2020 at a single institution. Preoperative, intraoperative, and postoperative de-identified data were analyzed for incidence, risk factors, and visual acuity outcomes. The incidence of flap repositioning was 0.35% in 21,536 eyes (n = 70). Indications for repositioning included acute flap dislocation (35.7%) and visually significant striae (64.3%). High myopia (OR = 3.04, p = 0.001) and patient age over 50 years (OR = 3.69, p = 0.001) were the strongest risk factors for these complications. Prior to flap repositioning, uncorrected distance visual acuity (UDVA) of 20/20 or better and 20/40 or better occurred in 19% and 57% of eyes, respectively. After repositioning, a final UDVA of 20/20 or better and 20/40 or better occurred in 78% and 98% of eyes, respectively. After repositioning, one line of UDVA was lost in two eyes (2.8%) and two lines were lost in one eye (1.4%). Risk factors for acute flap dislocation included high myopia and age over 50 years. Flap repositioning was effective in salvaging visual outcomes.

Five-Year Incidence, Management, and Visual Outcomes of Diffuse Lamellar Keratitis after Femtosecond-Assisted LASIK.

Femtosecond (FS) lasers initially had a higher incidence of diffuse lamellar keratitis (DLK) compared with microkeratome flap creation. It has been theorized that higher-frequency lower-energy (HFLE) FS lasers would reduce the incidence of DLK. Our study sought to evaluate the incidence of newer HFLE FS lasers with pulse frequencies above 60 kHz. It was a retrospective case-control study evaluating the incidence of DLK following flap creation with one of three FS lasers (AMO iFs, WaveLight FS200, Zeiss VisuMax). Uncomplicated LASIK cases were included as the control group (14,348 eyes) and cases of DLK were recorded in the study group (637 eyes). Of the 637 cases of DLK, 76 developed stage II, 25 progressed to stage III, and only three developed stage IV DLK. The overall incidence rate of DLK was 4.3%; it has fallen with the invention of newer HFLE FS lasers and is approaching the DLK incidence rates of DLK with microkeratome.

Proteinase-activated receptor-2 (PAR2) on blood pressure and electrolyte handling in the late pregnant rat.

NEW FINDINGS: What is the central question of this study? Pregnancy requires marked renal sodium and potassium retention and cumulative plasma volume expansion, in the setting of reduced blood pressure. Research in male rodents has shown that activation of PAR2 can produce peripheral vasodilatation, stimulate renal sodium chloride reabsorption and inhibit renal potassium secretion. Here, we investigate PAR2 activation in virgin and normal pregnant rats. What is the main finding and its importance? PAR2 expression and sensitivity to activation are increased in pregnancy. This implicates a possible role for PAR2 in supporting the renal/vascular adaptations of pregnancy required for normal maternal plasma volume expansion. ABSTRACT: A healthy pregnancy involves renal and systemic haemodynamic adaptations, which allow renal sodium and potassium retention and cumulative plasma volume expansion, accompanied by a decline in blood pressure attributable to a reduction in the total peripheral vascular resistance. When these adaptations do not occur, pregnancy is compromised. The mechanisms permitting these opposing adaptations are largely unknown. Research in male rodents has shown that activation of PAR2 can produce peripheral vasodilatation, stimulate renal sodium chloride reabsorption and inhibit renal potassium secretion. Here, we investigate PAR2 activation in female virgin and normal late pregnant (LP) rats. We measured the mRNA expression of PAR2 in the renal cortex, outer medulla and inner medulla of virgin and LP rats using quantitative real-time PCR. We also measured in vivo blood pressure, natriuretic and kaliuretic responses to PAR2-activating peptide (SLIGRL-NH2 ) in anaesthetized virgin and LP rats. We found that PAR2 mRNA was increased in the inner medulla of LP rats. We also found that LP rats had larger decreases in blood pressure and increases in net sodium retention compared with virgin rats. These findings suggest that pregnancy enhances sensitivity to the blood pressure-lowering and sodium-retaining effects of PAR2.