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Background: Temporal trends of routinely obtained parameters may provide valuable information for predicting BSIs, but this association has not yet been established in LVAD patients. Methods: This retrospective analysis included data from 347 consecutive recipients of three rotary LVAD types. Study endpoints included the incidence of BSI, the association of temporal trends of routinely obtained blood biomarkers with the development of BSIs, the incidence of BSIs, and survival on LVAD support. Results: During follow‐up, 47.8% (n = 166) of the patients developed BSI. In multivariate analyses, the development of BSI was a significant predictor of mortality (HR 5.78, 95% CI 4.08–8.19, p < 0.0001). In univariate analyses, after adjusting for potential confounders, albumin (SHR 0.94, 95% CI 0.91–0.97, p < 0.00010), creatinine (SHR 1.49, 95% CI 1.03–2.15, p = 0.033), and C‐reactive protein (SHR 1.19, 95% CI 1.08–1.32, p = 0.0007) significantly predicted the development of BSIs during LVAD support. Notably, the strength of the association of parameter changes with the prediction of BSIs demonstrated a time‐dependent correlation in the cases of albumin (p = 0.045) and creatinine (p = 0.003). Conclusion: Bloodstream infections are highly prevalent among LVAD recipients and are independent predictors of mortality. Temporal biomarker trends significantly predict the development of BSIs. These findings suggest opportunities for interventions aiming to reduce the incidence of BSIs. [ABSTRACT FROM AUTHOR]

A series of aryl‐substituted ortho‐quinone methides (oQMs) was synthesised and structurally characterised. Kinetic studies of the nucleophilic additions of carbanions (reference nucleophiles) to oQMs were used to determine second‐order rate constants k2 for the carbon‐carbon bond forming reactions (20 °C, DMSO) at the oQMs’ exocyclic π‐bond. Analysing the kinetic data by the linear free energy relationship lg k2=sN(N+E) revealed the Mayr electrophilicities E of the oQMs. The electrophilicities E of oQMs correlate linearly with Hammett substituent constants and experimentally determined reduction potentials Epred as well as with quantum‐chemically calculated methyl anion affinities (MAAs), which provides valuable tools for prediciting the reactivity of further types of oQMs. Embedding the oQMs in Mayr's reactivity scales enables to predict novel nucleophilic reaction partners for oQMs and can productively be used to prepare simple Michael adducts as well as 4+2 or 4+1 cyclisation products as demonstrated in this work by several novel reactions with neutral or negatively charged C‐, N‐, and S‐nucleophiles. [ABSTRACT FROM AUTHOR]

The development of glass‐ceramic materials is often achieved using an elementary microstructural strategy that splits the tasks of seed formation and functionality between two types of crystals. This strategy requires customized time‐temperature ceramization protocols, which have been so far implemented using empirical parameters. Here, a more fundamental approach is proposed: the extent of overlap Oe between seed formation and volume crystallization is evaluated by calorimetric and dilatometric measurements, targeting the computation of a threshold heating rate qt for effective single‐stage heat treatments. The applicability of this novel parameter is tested in TiO2‐doped lithium magnesium aluminosilicate glass‐ceramics, whose seed formation stage is thoroughly characterized by Raman spectroscopy and STEM. High‐temperature X‐ray diffraction demonstrates that insufficient seeding results in potentially weaker performances of the final products, due to large sizes and silica deficiency of the functional quartz solid solution crystals. [ABSTRACT FROM AUTHOR]

Suction of the left ventricle can lead to potentially life‐threatening events in left ventricular assist device (LVAD) patients. With the resolution of currently available clinical LVAD monitoring healthcare professionals are unable to evaluate patients' suction occurrences in detail. This study investigates occurrences and durations of suction events and their associations with tachycardia in stable outpatients. Continuous high‐resolution LVAD data from HVAD patients were analyzed in the early outpatient period for 15 days. A validated suction detection from LVAD signals was used. Suction events were evaluated as suction rates, bursts of consecutive suction beats, and clusters of suction beats. The occurrence of tachycardia was analyzed before, during, and after suction clusters. Furthermore, blood work, implant strategy, LVAD speed setting, inflow cannula position, left ventricular diameters, and adverse events were evaluated in these patients. LVAD data of 10 patients was analyzed starting at 78 ± 22 postoperative days. Individuals' highest suction rates per hour resulted in a median of 11% (range 3%‐61%). Bursts categorized as consecutive suction beats with n = 2, n = 3‐5, n = 6‐15, and n > 15 beats were homogenously distributed with 10.3 ± 0.8% among all suction beats. Larger suction bursts were followed by shorter suction‐free periods. Tachycardia during suction occurred in 12% of all suction clusters. Significant differences in clinical parameters between individuals with high and low suction rates were only observed in left ventricular end‐diastolic and end‐systolic diameters (P <.02). Continuous high‐resolution LVAD monitoring sheds light on outpatient suction occurrences. Interindividual and intraindividual characteristics of longitudinal suction rates were observed. Longer suction clusters have higher probabilities of tachycardia within the cluster and more severe types of suction waveforms. This work shows the necessity of improved LVAD monitoring and the implementation of an LVAD speed control to reduce suction rates and their concomitant burden on the cardiovascular system. [ABSTRACT FROM AUTHOR]

Patients supported with a left ventricular assist device (LVAD) have impaired cardiovascular adaptations during exercise, resulting in reduced total cardiac output and exercise intolerance. The aim of this study is to report associations among these impaired cardiovascular parameters and exercise hemodynamics, and to identify in which conditions an LVAD speed increase can provide substantial benefits to exercise. A cardiorespiratory simulator was used to reproduce the average hemodynamics of LVAD patients at exercise. Then, a sensitivity study was conducted where cardiovascular parameters were changed individually ±20% of their baseline value at exercise (heart rate, left/right ventricular contractility, total peripheral resistance, and valve pathologies). Simulations were performed at a baseline LVAD speed of 2700 rpm and repeated at 3500 rpm to evaluate the benefits of a higher LVAD support on hemodynamics. Total cardiac output (TCO) was mostly impaired by a poor left ventricular contractility or vasodilation at exercise (−0.6 L/min), followed by a poor chronotropic response (−0.3 L/min) and by a poor right ventricular contractility (−0.2 L/min). LVAD speed increase better unloads the left ventricle and improves total cardiac output in all the simulated conditions. The most substantial benefits from LVAD speed increase were observed in case of poor left ventricular contractility (TCO + 1.6 L/min) and vascular dysfunction (TCO + 1.4 L/min) followed by lower heart rate (TCO + 1.3 L/min) and impaired right ventricular contractility (TCO + 1.1 L/min). Despite the presence of the LVAD, exercise hemodynamic is strongly depending on the ability of the cardiovascular system to adapt to exercise. A poor left ventricular inotropic response and a poor vascular function can strongly impair cardiac output at exercise. In these conditions, LVAD speed increase can be an effective strategy to augment total cardiac output and unload the left ventricle. These results evidence the need to design a physiological LVAD speed controller, tailored on specific patient's needs. [ABSTRACT FROM AUTHOR]

Lithium borate (LB) glasses and crystals with x = Li/(Li + B) = mole fraction of Li2O of 0.2–0.5 have been synthesized by the quenching method. The thermodynamics of these materials were analyzed by high‐temperature oxide melt solution calorimetry. The formation enthalpies from oxides of glasses range from −33.6 to −67.3 kJ/mol and those of crystals range from −42.1 to −77.4 kJ/mol, where compositions are given on the basis of one mole of (Li2O + B2O3). The formation enthalpies of both glasses and crystals become more negative with increasing Li2O mole fraction up to 0.5. The enthalpies of formation of glasses can be fit over the entire composition range (0 < x < 1) by a quadratic polynomial). The vitrification enthalpies were derived for x = 0.2 to 0.5 and ranged from 8.5 to 17.6 kJ/mol. The main factors controlling energetics are the strongly exothermic acid–base reaction between the network former (B2O3) and the network modifier (Li2O) and the formation of tetrahedrally coordinated boron in the glasses and crystals. [ABSTRACT FROM AUTHOR]

Continuous flow left ventricular assist devices (cfLVADS) result in a significant reduction in aortic valve (AV) opening, which has been associated with several complications. Reliable monitoring of AV opening is needed to determine whether pump speed adjustment may be able to minimize adverse outcomes. We assessed AV status continuously by echocardiography for 4 minutes in 3 states in 18 HeartWare HVAD patients: 2 minutes at rest, and 1 minute each following Valsalva maneuver and supine leg‐raising. Using a previously described algorithm, beat‐to‐beat AV status was compared with the area under the curve of the normalized power spectral density analysis (PSD‐AUC) for the corresponding beats of the pump speed waveform. Five thousand five hundred twenty‐seven beats were analyzed. AV opening varied between 0% and 100% for the cohort with the median AV opening frequency 21.5%, and median duration of opening of 124 msec (range 0–279). The receiver operating characteristic (ROC) curve area for AV opening by the PSD‐AUC algorithm was 0.95 (P < 0.0001). A PSD‐AUC cut‐off of 0.82 distinguished between an open and closed AV with 86% sensitivity and 93% specificity. Accuracy was similar in regular cardiac rhythm, atrial fibrillation or with frequent ventricular ectopic beats. Valsalva maneuver and leg‐raising had no impact on accuracy. The PSD‐AUC was strongly predictive of AV opening duration (P < 0.0001). We found that AV status and opening duration can be determined with high accuracy on a beat‐to‐beat basis irrespective of cardiac rhythm and with low level exercise and changes in filling. [ABSTRACT FROM AUTHOR]

Left ventricular assist devices (LVADs) restore cardiovascular circulatory demand at rest with a spontaneous increase in pump flow to exercise. The relevant contribution of cardiac output provided by the LVAD and ejected through the aortic valve for exercises of different intensities has been barely investigated in patients. The hypothesis of this study was that different responses in continuous recorded pump parameters occur for maximal and submaximal intensity exercises and that the pump flow change has an impact on the oxygen uptake at peak exercise (pVO2). Cardiac and pump parameters such as LVAD flow rate (QLVAD), heart rate (HR), and aortic valve (AV) opening were analyzed from continuously recorded LVAD data during physical exercises of maximal (bicycle ergometer test) and submaximal intensities (6‐min walk test and regular trainings). During all exercise sessions, the LVAD speed was kept constant. Cardiac and pump parameter responses of 16 patients for maximal and submaximal intensity exercises were similar for QLVAD: +0.89 ± 0.52 versus +0.59 ± 0.38 L/min (P = 0.07) and different for HR: +20.4 ± 15.4 versus +7.7 ± 5.8 bpm (P < 0.0001) and AV‐opening with 71% versus 23% of patients (P < 0.0001). Multi‐regression analysis with pVO2 (R2 = 0.77) showed relation to workload normalized by bodyweight (P = 0.0002), HR response (P = 0.001), AV‐opening (P = 0.02), and age (P = 0.06) whereas the change in QLVAD was irrelevant. Constant speed LVADs provide inadequate support for maximum intensity exercises. AV‐opening and improvements in HR show an important role for higher exercise capacities and reflect exercise intensities. Changes in pump flow do not impact pVO2 and are independent of AV‐opening and response in HR. An LVAD speed control may lead to adequate left ventricular support during strenuous physical activities. [ABSTRACT FROM AUTHOR]