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We comment on the series solutions presented in the paper "Newtonian Poiseuille flow in ducts of annular-sector cross-sections with Navier slip" for the no-slip case. [ABSTRACT FROM AUTHOR]

Black women have been underrepresented in left ventricular assist device (LVAD) clinical trials and published reports. The aim of this study was to examine the outcomes of Black women undergoing LVAD implantation. We retrospectively identified Black women who underwent LVAD implantation at a single center between January 1, 2007 and October 31, 2020. Outcomes of patients who received HeartMate II (HMII), HeartWare (HVAD), and HeartMate 3 (HM3) devices were compared. Adverse events (AEs) for all patients were calculated as events per patient-year (EPPY). Reasons for readmissions, including incidence and rates, were reviewed. A total of 154 Black female patients underwent LVAD implantation during the study period. Sixty-six received HVAD, 36 received HMII, and 52 received HM3 devices (Figure 1). Median age for all patients was 57.7 years (IQR 46.9-64). At baseline, patients supported with HMII and HM3 were more likely to have diabetes compared to those supported with HVAD (HM3 50% vs HMII 50% vs HVAD 22.7%, p=0.003). HM3 recipients had a higher incidence of stroke pre-operatively (17.3% vs HMII 13.9% vs HVAD 3%, p=0.03). Post-operatively, HM3 recipients were on inotropes for longer duration (14 days vs HMII 9 days vs HVAD 8.5 days (IQR 5.3-16), p=0.004) and were placed on Epoprostenol at higher frequency (65.4% vs HMII 27.8% vs HVAD 39.4%, p=0.001). In regards to AEs, the incidence of LVAD-related infections was 25.3%, gastrointestinal bleeding was 33.8%, and cerebrovascular accidents was 14.3%. Twenty-nine pump thrombosis events occurred in 20 (13%) patients. Overall, patients supported with HM3 demonstrated lower rates of pump thrombosis (EPPY: 0.008 vs HMII 0.216 vs HVAD 0.062, p<0.001 and p=0.034, respectively)(Figure 1). HM3 patients experienced fewer readmissions for LVAD infection compared to HMII patients (EPPY: 0.19 vs HMII 0.49, p=0.001) as well as for cardiac arrhythmias (EPPY: 0.07 vs HMII 0.26, p=0.003). Hospitalization for LVAD alarms was significantly higher in the HM3 population (44% vs. HMII 19.4%, p<0.001). Black Women LVAD recipients experienced differential outcomes post-LVAD by device type including rates of pump thrombosis, infection, and hospitalization for LVAD alarms. Additional studies are warranted to further examine racial and sex disparities in pre- and post-LVAD clinical outcomes. [ABSTRACT FROM AUTHOR]

Thermal response of thin films under pulse heating, resembling laser pulses, is considered and the semi-analytical solution of phonon radiative transport is presented. Temperature pulsation is introduced at the film edge resembling the laser pulses and silicon thin film is used as the film material. Since the film thickness is comparable to the mean free path of silicon, equation for radiative phonon transport is incorporated in the analysis. Temperature findings from the semi-analytical solution are compared to that obtained from the numerical solution. Equivalent equilibrium temperature is introduced to quantify the phonon intensity distribution in the film. It is found that equivalent equilibrium temperature obtained from the semi-analytical solution agrees well with its counterpart obtained from the numerical simulations. The semi-analytical solution correctly predicts the temperature jump at the film edges. The semi-analytical solution reduces the computation efforts significantly in terms of run time and memory size, which are required for the numerical simulations. Temporal distribution of temperature inside the film at various locations does not follow exactly the temperature pulses introduced at one edge of the silicon film. [ABSTRACT FROM AUTHOR]

Abstract: An exact solution of the problem of heat conduction in the annulus between eccentric isothermal spheres with internal heat generation is obtained. The solution is given in terms of the temperature distribution and local and average Nusselt numbers. [Copyright &y& Elsevier]

Abstract: The phenomenon of secondary motion (acoustic streaming) created by the oscillation of a fluid past a sphere is investigated through numerically solving the full Navier–Stokes equations. The main parameters that affect the structure of acoustic streaming are Reynolds number and Strouhal number. The results are presented in the form of steady streaming patterns as well as the relation between Reynolds and Strouhal numbers and the dimensions of the streaming region. [Copyright &y& Elsevier]

• Steady-state solution of the flow in anisotropic porous media between two cylinders is given as a sum of infinite series. • The analysis shows that the anisotropy and ratio between two radii of inner and outer cylinder have a significant impact on the pressure distribution. • The modified approach for the experimental procedure utilizes the proposed solution to determine the anisotropy parameters in the lab from the holed core experiment. Anisotropy is a common feature for most of fibrous and porous media. This article reports a new method for measuring the 2D anisotropic permeability of a porous rock utilizing the measurements obtained from the steady-state flow between two concentric cylinders. The mathematical analysis of the experimental data is based on the general solution of the pressure equation derived for the steady-state flow equation for an anisotropic porous medium between two concentric cylinders. The general solution, incorporating the degree of anisotropy and the ratio between inner and outer cylinder radii, is presented in a dimensionless form. The solution shows that pressure distribution between the two cylinders is composed of an isotropic part plus a series representing the contribution of the anisotropy. The solution is validated through the comparison against numerically derived results and the analytical solution of two extreme cases; when the clearance between the two cylinders vanishes, and when the material is isotropic. The validation shows a perfect performance of the proposed solution even in the vicinity of the inner cylinder not like the approximate solutions existing in the literature. The validation also shows that the truncation of the series part has an impact on the results specially in the case of extreme anisotropy. Two experimental procedures 1) basic approach and 2) modified approach, utilizing the "pear" and "tent" charts derived from the general solution, demonstrate how to obtain the principle permeabilities and their directions. The applicability of the proposed experimental techniques is attained through the application of the modified approach over real experimental data from a holed core experiment to estimate anisotropic permeability parameters. The application of the proposed technique and the required modifications for measuring the anisotropy in tight cores are discussed. Also, the relation between the three-dimension anisotropy and the presented plane anisotropy is presented. [ABSTRACT FROM AUTHOR]

The incidence of atrial fibrillation increases with age, and therefore many elderly patients presenting for cardiac surgery have atrial fibrillation. In recent publications, increasing age has been recognized as a predictor for ablation failure. Furthermore, many surgeons are reluctant to perform a surgical ablation in elderly patients. We investigated the safety and efficacy of concomitant surgical atrial fibrillation ablation in elderly patients. Between 2003 and 2013, 556 patients underwent concomitant surgical atrial fibrillation ablation at the University Heart Center Hamburg and served as our primary study cohort. During follow-up, rhythm monitoring was established by 24-hour Holter electrocardiogram (70.5%) or an implantable loop recorder (29.5%) at 3, 6, and 12 months postoperatively. The primary end point of the study was freedom from atrial fibrillation at 12 months follow-up and the detection of deviations from a linear association between age and risk of atrial fibrillation recurrence. A multiple logistic regression model including age as a linear term was used to identify predictors for rhythm outcome. Mean patients' age was 68.4 ± 9.07 years, and 67.3% of the patients were male. Mean duration of atrial fibrillation was 3.5 ± 3.3 years, and mean left atrium diameters were enlarged with 50.5 ± 8.8 mm. There were no major ablation-related complications. The 30-day and 1-year survivals were 97.7% and 95.8%, respectively. The overall rate of freedom from atrial fibrillation ranged from 62% to 72% and was independent of age. The age-dependent risk of atrial fibrillation at 12 months was significantly increased in elderly patients undergoing a concomitant coronary artery bypass grafting surgery. Multiple logistic regression model revealed double valve procedures (odds ratio, 3.48; P =.020), preoperative persistent atrial fibrillation (odds ratio, 2.43; P =.001), and coronary artery bypass grafting surgery in elderly patients (odds ratio, 2.03; P =.009) as risk factors for recurrence of atrial fibrillation. Sinus rhythm at discharge (odds ratio, 0.39; P <.001) and bipolar ablation (odds ratio, 0.32; P <.001) were significant predictors for successful ablation. Surgical atrial fibrillation ablation was safe and effective independently of age. Sinus rhythm at discharge and bipolar ablation were significant predictors for successful ablation, whereas double valve procedures, preoperative persistent atrial fibrillation, and coronary artery bypass grafting surgery in elderly patients were risk factors for recurrence of atrial fibrillation. [Display omitted] [ABSTRACT FROM AUTHOR]

Improvement in preservation and transportation conditions has the potential to enhance organ quality at the time of transplant, optimize patient outcomes, and prolong the acceptable maximum allograft ischemic time. Herein, we describe our initial successful experience with the static hypothermic preservation system (Paragonix) for a donor heart. Our storage period and allograft ischemic time are the longest reported in the literature. A 68-year-old woman with HF was listed for transplantation. A donor heart was procured from a hospital located 3.5 hours away. The donor allograft was secured and packaged using the SherpaPak™ device (Fig. 1) ; total storage period was 283 mins. Heart transplantation was performed in standard fashion. AV conduction and normal sinus rhythm were regained after 7 mins of reperfusion. Total ischemic time was 330 mins, including a warm ischemic time of 20 minutes. The recipient CPB time and aortic cross clamp time were 153 and 50 mins, respectively. The patient recovered well and was discharged on postoperative day 10. At three months post-transplant, the patient continues to have excellent graft function without any evidence of rejection. Historically, Shumway et al. initially obtained donor hearts from operating rooms immediately adjacent to a recipient. Over time, donor distance and allograft ischemic times have increased with advances in cardiac preservation. However, long cold ischemic times may induce PGD, cardiac allograft vasculopathy, and contribute to increased length of stay. Maintaining storage temperatures within the narrow range of 4-8°C is optimal for the preservation of high energy phosphate stores and avoids the risk of cold ischemic injury at temperatures below 2°C. By expanding geographic boundaries and total ischemic times, we believe that regulated static hypothermic preservation is a useful addition to a growing armamentarium of devices and strategies to increase access to transplantation. [ABSTRACT FROM AUTHOR]

As the world responds to the global crisis of the COVID-19 pandemic an increasing number of patients are experiencing increased morbidity as a result of multi-organ involvement. Of these, a small proportion will progress to end-stage lung disease, become dialysis dependent, or both. Herein, we describe the first reported case of a successful combined lung and kidney transplantation in a patient with COVID-19. Lung transplantation, isolated or combined with other organs, is feasible and should be considered for select patients impacted by this deadly disease. [ABSTRACT FROM AUTHOR]

Abstract: We show that the two dimensional Navier–Stokes equations in the stream function and vorticity form with nonhomogeneous boundary conditions have a unique solution with a stream function having two space derivatives. [Copyright &y& Elsevier]

Motivated essentially by their possible need in a fairly large number of physical and chemical contexts, Mavromatis and Alassar [1] derived several associated Laguerre integral results by eliminating an unnecessary constraint used in an earlier paper on the subject by Mavromatis [2]. The main object of the present sequel to these recent works is to investigate and apply much more general families of integral formulas, involving products of two or more Laguerre polynomials, which have been considered in the mathematical literature rather extensively. [Copyright &y& Elsevier]

The donor shortage poses a major limitation to use of heart transplantation. Novel strategies such as use of expanded-criteria donors with prolonged ischemia times are being employed to address this need. Recent developments in static hypothermia have allowed for the safe use of cardiac allografts with prolonged ischemic times. We present the case of a 68-year-old woman with valvular cardiomyopathy refractory to medical therapy who underwent orthotopic heart transplantation with a cardiac allograft exposed to elevated ischemic times. This was achieved through use of the federally approved SherpaPak Cardiac Transport System for transportation of the allograft. This method of static hypothermic organ preservation allowed for a 330-minute total ischemic time, including 283 minutes of storage within the preservation system. The patient tolerated the procedure well and was discharged on postoperative day 10, with excellent graft function and no evidence of rejection 3 months postoperatively. Though traditionally ischemic times of 240 minutes or less are recommended for cardiac allografts, we demonstrate, to our knowledge, the longest reported ischemic time of 330 minutes via use of a novel method of static hypothermia for organ preservation. The recipient had an excellent outcome postoperatively, demonstrating the potential for this new organ preservation system to expand the donor pool and improve access and use of heart transplantation. [ABSTRACT FROM AUTHOR]

Intra-aortic balloon pump (IABP) therapy is often used to bridge patients to durable left ventricular assist device (LVAD). We examined the hemodynamic changes following IABP insertion in cardiogenic shock patients requiring LVAD therapy. We performed a retrospective observational study of patients receiving an IABP as a bridge to LVAD from 2015-2021. Hemodynamic metrics including right atrial pressure (RAP), pulmonary artery pressures (PAP), mixed venous oxygen saturation (SvO2), and cardiac output/indices (CO/CI) were collected at 1-hour, 24-hours, and 48-hours post-IABP insertion as well as day of insertion of the LVAD. Post-IABP hemodynamic measures were compared to the pre-IABP state. Heart failure-related labs were drawn prior to IABP and compared to 48 hours post-IABP. All p values < 0.05 were considered significant. A total of 104 patients were analyzed. Mean (SD) age was 55.8 (11.9) years old and median (IQR) days on IABP support was 4.5 (3.1). Improvement in RAP and PAP was noted at 24- and 48-hours post-IABP placement and on the day of LVAD placement. SvO2 and CO/CI were higher at all time points following IABP (Figure). All labs with the exception of sodium were improved at the 48-hour interval (Table). IABP therapy improves hemodynamic profiles in cardiogenic shock patients bridged to LVAD as early as 1-hour post-placement and persists until the day of LVAD implantation. IABPs can serve as an effective platform to bridge selected patients to durable LVAD. Future research should be focused on the identification of predictors of IABP hemodynamic response in advanced heart failure patients. [ABSTRACT FROM AUTHOR]

Short-term mechanical circulatory support (MCS) plays an increasing role in patients in acute cardiogenic shock as a bridge-to-decision strategy for potential left ventricular assist device (LVAD) implantation. Microaxial flow pump (MFP) therapy thereby is gaining increasing importance as a complement to venoarterial extracorporeal membrane oxygenation (VA-ECMO) therapy for left ventricular unloading. The aim of the study was to compare VA-ECMO vs. VA-ECMO + MFP therapy as short-term MCS prior to LVAD implantation. 183 patients with advanced heart failure underwent LVAD implantation at our center between 2010 - 2020. Of these, 34 patients had short-term MCS with VA-ECMO (n=16, group 1) or VA-ECMO + MFP (n=18, group 2) before LVAD implantation. Data were retrospectively analysed. Both groups consisted only of patients in acute cardiogenic shock (INTERMACS profile 1 + 2, age (group 1 vs. group 2: 50.1±9.8 vs. 52.7±7.3 years, p=0.1)). Short-term MCS was performed until LVAD implantation. Time on short-term MCS (6.6±3.8 vs. 8±4.9 days, p=0.4) showed no significant difference between the groups. Implanted permanent devices were HVAD and Heart Mate 3 (HM3) (group 1: HVAD: 88%, HM3: 12%; group 2: HVAD: 55%, HM3: 45%). Procedural characteristics showed no significant differences in terms of access, procedure time or volume management. Rates of in-hospital stroke (5.5 vs. 0%, p=1.0) and major bleeding (0 vs. 0%, p=1.0) were low in both groups. Rate of concomitant temporary RVAD implantation was similar in both groups (43.7 vs. 38.8%, p=1.0). Consecutive right heart failure in the first 3 months occurred in both groups (6,3 vs.5.5%, p=1.0). 30-day (12.5 vs. 17%, p=1.0) and 1-year mortality (31.3 vs. 22.2%, p=0.7) revealed no significant differences between groups. Our study shows a similar outcome after short-term MCS and LVAD implantation in both groups resulting in a 30-day survival of >80% in our high-risk cohorts. The effect of additional MFP needs to be proven in further studies. [ABSTRACT FROM AUTHOR]

Malnutrition and cardiac cachexia with low body mass index (BMI) are recognized pre-implant risk factors for adverse post-LVAD outcomes. The obesity paradox has defined a protective effect of higher BMI in terms of outcomes in heart failure (HF) patients. We evaluated the interaction of nutritional state (estimated by albumin) with BMI on LVAD outcomes. A retrospective cohort study of patients implanted with continuous flow LVAD at our center between 2006 and 2022 was performed. Patients were stratified into four quartiles based on nutritional status and BMI. We considered malnourished to be albumin <3.5g/dL and well-nourished as albumin > 3.5g/dL. We considered obesity to be a BMI > 30kg/m2 and non-obese as BMI <30kg/m2. We created 4 groups - malnourished, obese (MN-Obese); malnourished, non-obese (MN-NonObese); well-nourished, obese (N-Obese); and well-nourished, non-obese (N-NonObese). We compared time to first HF exacerbation post-LVAD implantation amongst the 4 groups. 745 patients were included for analysis: 25% (n=185) MN-Obese, 45% (340) MN-NonObese, 14% (105) N-Obese and 16% (117) N-NonObese. Independent of nutritional status, obese patients were more likely to self-report as Black (p = 0.021), and have diabetes, hypertension and OSA (p = < 0.001 for all). Obese patients had higher incidence of first HF exacerbation than non-obese patients regardless of nutritional status (Figure). At 1 year, 20% of MN-NonObese and 13% of N-NonObese patients had been hospitalized compared to 32% of MN-Obese and 37% of N-Obese patients (p < 0.001). One year survival was similar between the groups. Although there was no association with survival, obese LVAD patients have a higher rate of heart failure hospitalizations than non-obese. Malnutrition appears to increase the rate of hospitalization in non-obese LVAD patients, but not in the obese. Further investigation is warranted to understand the impact of BMI and nutritional status on long-term clinical outcomes with LVAD therapy. [ABSTRACT FROM AUTHOR]

Clinical data on patients after left ventricular assist device (LVAD) explantation are scarce. There are several surgical approaches for explantation of an LVAD after recovery of cardiac function. Thus, remaining ventricular assist device components bear significant risks of infection or thrombosis. We hereby report our technique and single-centre experience with explantation of LVADs using a double patch technique. From March 2019 - April 2021, 4 patients underwent LVAD explantation after myocardial recovery (HVAD, n=2; HeartMate 3, n=2). Mean patient age was 50.2 years (100% male) and mean time on LVAD was 19.8 months. Primary heart failure aetiology was dilated cardiomyopathy (n=3) and myocarditis (n=1). LVAD explantation was performed using a median sternotomy and cardiopulmonary bypass. The LVAD was stopped, and the outflow graft clamped. The outflow graft was ligated and sutured close to the aortic anastomosis. The driveline was clipped and removed. Under induced fibrillation the attachment of the LVAD was released from the apical cuff and the LVAD removed. A round pericardial patch was fixed from inner of the ventricle with twelve 3-0 Prolene sutures stitched from the ventricle towards the suture ring of the LVAD. This already seals the apex of the heart. An additional Goretex patch is continuously sutured epicardially over the suture ring. The ventricle is carefully deflated. The patient is then weaned from ECC. The four cases showed technically uncomplicated explantation of the LVADs. During the follow-up, a 30-day survival and 1 year survival of 100% was observed. There were no bleeding complications or thromboembolic events during follow-up. This technique allowed discontinuation of anticoagulation in all patients. LVAD explantation with the double patch technique is feasible and safe. This technique allows discontinuation of anticoagulation. We have had no bleeding or thromboembolic events at our center. Overall, there was a 30-day survival of 100%. Further studies are needed to provide better evidence for LVAD explantation and long-term follow-up. [ABSTRACT FROM AUTHOR]