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Accurate activity classification is essential for the advancement of closed-loop control for left ventricular assist devices (LVADs), as it provides necessary feedback to adapt device operation to the patient’s current state. Therefore, this study aims at using deep neural networks (DNNs) to precisely classify activity for these patients. Recordings from 13 LVAD patients were analyzed, including heart rate, LVAD flow, and accelerometer data, classifying activities into six states: active, inactive, lying, sitting, standing, and walking. Both binary and multiclass classifiers have been trained to distinguish between active and inactive states and to discriminate the remaining categories. The models were refined by testing several architectures, including recurrent and convolutional layers, optimized via hyperparameter search. Results demonstrate that integrating LVAD flow, heart rate, and accelerometer data leads to the highest accuracy in both binary and multiclass classification. The optimal architectures featured two and three bidirectional long short-term memory layers for binary and multiclass classifications, respectively, achieving accuracies of 91% and 84%. In this study, the potential of DNNs has been proven for providing a robust method for activity classification that is vital for the effective closed-loop control of medical devices in cardiac care.

Effective treatment of heart failure with preserved ejection fraction (HFpEF) remains an unmet medical need. Although left atrial decompression using mechanical circulatory support devices was previously suggested, the heterogeneous HFpEF population and the lack of tailored devices have prevented the translation into clinical practice. This study aimed to evaluate the feasibility of left atrial decompression in HFpEF patients with a HeartMate 3 (HM3, Abbott Inc, Chicago, USA) in silicoand in vitro. Anatomic compatibility of the HM3 pump was assessed by virtual device implantation into the left atrium through the left atrial appendage (LAA) and left atrial posterior wall (LAPW) of 10 HFpEF patients. Further, the efficacy of left atrial decompression was investigated experimentally in a hybrid mock loop, replicating the hemodynamics of an HFpEF phenotype at rest and exercise conditions. Virtual implantation without substantial intersection with surrounding tissues was accomplished through the LAA in 90% and 100% through the LAPW. Hemodynamic analysis in resting conditions demonstrated normalization of left atrial pressures without backflow at a pump speed of around 5400 rpm, whereas a range of 6400–7400 rpm was required during exercise. Therefore, left atrial decompression with the HM3 may be feasible in terms of anatomic compatibility and hemodynamic efficacy.

Objective: This study evaluated the ergonomics and time requirements of using a novel automated suturing and titanium fastener deployment technology for chordal replacement in human heart specimens in open and minimally invasive cardiac surgery (MICS) simulators.Methods: Five cardiac surgeons used novel, manually powered expanded polytetrafluoroethylene (ePTFE) suturing devices to automate suture placement between mitral leaflets and papillary muscles in explanted cadaver hearts, along with customized titanium fastener delivery devices to secure suture and trim suture tails. This mitral chordal replacement test was conducted using surgical models simulating open and MICS mitral repair access. The study was approved by the institutional ethical board.Results: After a brief introduction to this technique using plastic models, study surgeons performed 48 chordal replacements in human mitral valves, placing 18 in an open model and 30 in a right minithoracotomy model. The time range to complete a single chordal replacement was between 55 s and 8 min, with an overall mean duration of 3.6 ± 1.5 min. No difference in duration of implantation was recorded for the MICS and open sternotomy simulators used. Good control of suture delivery was reported in 95.8% (n= 46) of leaflet aspect of the sutures and in 100% (N= 48) of papillary muscle sutures.Conclusions: Automated mitral chordal ePTFE suturing simulated through open and MICS access demonstrated quality handling and accurate placement of sutures in human heart specimens. A clinical trial using this technology is currently ongoing. This innovation may present an important advance facilitating enhanced minimally invasive mitral valve repair.

Ventricular suction is a frequent adverse event in patients with a ventricular assist device (VAD). This study presents a suction module (SM) embedded in a hybrid (hydraulic-computational) cardiovascular simulator suitable for the testing of VADs and related suction events. The SM consists of a compliant latex tube reproducing a simplified ventricular apex. The SM is connected on one side to a hydraulic chamber of the simulator reproducing the left ventricle, and on the other side to a HeartWare HVAD system. The SM is immersed in a hydraulic chamber with a controllable pressure to occlude the compliant tube and activate suction. Two patient profiles were simulated (dilated cardiomyopathy and heart failure with preserved ejection fraction), and the circulating blood volume was reduced stepwise to obtain different preload levels. For each simulated step, the following data were collected: HVAD flow, ventricular pressure and volume, and pressure at the inflow cannula. Data collected for the two profiles and for decreasing preload levels evidenced suction profiles differing in terms of frequency (intermittent vs.every heart beat), amplitude (partial or complete stoppage of the HVAD flow), and shape. Indeed different HVAD flow patterns were observed for the two patient profiles because of the different mechanical properties of the simulated ventricles. Overall, the HVAD flow patterns showed typical indicators of suctions observed in clinics. Results confirmed that the SM can reproduce suction phenomena with VAD under different pathophysiological conditions. As such, the SM can be used in the future to test VADs and control algorithms aimed at preventing suction phenomena.

Pump thrombosis (PT) is a serious adverse event in patients receiving left ventricular assist devices (LVAD). The study aims to determine whether pump parameters and clinical data may enable early detection of PT. This retrospective study included 88 patients who received an LVAD between 2012 and 2015 among which those with intra-PT were identified. In a propensity score–matched control group observation, time periods were matched with time before thrombosis. International normalized ratio (INR) time in therapeutic range (TTR) and lactate dehydrogenase (LDH) were analyzed for 60 days preceding PT. Furthermore, pump data (power, flow, and speed) in HeartWare ventricular assist devices (HVAD) patients were analyzed 7 days before PT using a mixed-design analysis of variance to investigate temporal changes in pump data. Pump thrombosis occurred in 15 patients (13 males, age 58 ± 10 years, 7 HeartMate II and 8 HVAD). International normalized ratio therapeutic range (2.0–3.0) and acetylsalicylic acid daily doses (100–200 mg) were similar for both groups, but patients with PT had lower TTR (36% vs.65%; p= 0.025). No significant difference in LVAD power between groups was seen at baseline (p= 0.31), and power did not change in the control group over time (p> 0.99). Lactate dehydrogenase increased already 1 week prior PT and power from 4.4 ± 0.8 W at baseline to 4.9 ± 0.8 W (p= 0.007) 2 days before readmission and to 6.5 ± 1.8 W (p= 0.015) at readmission. Pump thrombosis is associated with a lower percentage of INR TTR and elevated LDH before the event. A better monitoring of pump parameters would enable PT detection already up to 2 days in advance.

In rotary blood pump recipients with low blood pressure pulsatility, current oscillometric methods to measure blood pressure are not applicable. The aim of this study was to use ultrasonic Doppler flow measurements to determine blood pressure in this patient population noninvasively. In 28 rotary blood pump recipients, blood pressure was measured three times with the developed Doppler method and compared to the invasive arterial line (n = 15) or to the oscillometric Terumo Elemano BP monitor (n = 13). Blood velocities in the radial artery were recorded by the new Doppler sensor during cuff deflation. A sigmoid curve was fitted to a preprocessed velocity signal and the systolic and mean arterial pressures were determined. A total of 84 measurements were performed, and 17 recordings were visually excluded from further analysis due to obvious artifacts. Both the systolic and mean pressures derived by the Doppler method were in good accordance with the invasively measured pressure (3.7 ± 6.6 mmHg for the systolic and −2.1 ± 7.3 mmHg for the mean pressure). A good agreement between the oscillometric monitor and the Doppler method for the systolic (0.0 ± 6.0 mmHg) and mean (1.0 ± 5.9 mmHg) pressures was observed. In this study, a new Doppler blood pressure measurement system was developed and clinically validated. The novel sensor allows easier placement above the radial artery compared to commercial probes. An algorithm was developed which processes the Doppler signal robustly and is able to determine the systolic as well as the mean arterial blood pressure.

Various methods of cerebral protection have been used during such aortic arch operations as the Norwood Procedure and operations on the interrupted aortic arch in neonates and infants. Deep hypothermia with circulatory arrest is the most common technique, but has a limited safe period for circulatory arrest. Antegrade cerebral perfusion has been introduced to prolong this safe period. We reviewed our experience with antegrade cerebral perfusion during surgical repair, in a patient with hypoplastic left heart syndrom in stage 1 palliation.

This work presents room temperature single crystal X-ray diffraction measurements of the spin ladder compounds SrCu2O3(Cmmm, a= 3.948(2) Å, b= 11.626(4) Å, c= 3.509(1) Å, Z= 2) and Sr2Cu3O5(Immm, a= 3.395(2) Å, b= 3.941(1) Å, c= 18.662(5) Å, Z= 2), and the evolution of their structures from room temperature down to 100 K. We confirm the structure of SrCu2O3previously described in the literature from X-ray powder and electron diffraction measurements, and report a new modification for Sr2Cu3O5with an unusual CuO5trigonal bipyramidal coordination.

A complementary approach to solve quasi crystalline atomic structures in 3-dimensional (3D) real space is presented: The atomic pair distribution function (PDF) of face centred icosahedral Ho9Mg26Zn65[a(6D) = 2 × 5.18(3) Å] has been obtained from in-house powder X-ray diffraction data (MoKα1). For the first time, full profile PDF refinements of a quasicrystal were performed: Starting with rational approximant models, derived from 1/1- and 2/1-Al—Mg—Zn, its local and medium range structure was refined (r< 27 Å; R= 12.9%) using the PDF data. 85% of all atoms show Frank-Kasper (FK) type coordinations. The basic structural unit is the 3-shell, 104-atom Bergman cluster (d≈ 15 Å) comprising a void at its center. The clusters are interconnected sharing common edges and hexagonal faces of the 3rd shells. The remaining space is filled by some glue atoms (9% of all atoms), yielding an almost tetrahedrally close packed structure. All Ho atoms are surrounded by 16 neighbours (FK-polyhedron “P”). Most of them (89%) are situated in the 2nd shell and form a Ho8cube (edge length 5.4 Å); they are completed by 12 Mg atoms to a pentagon dodecahedron. Cubes in neighbouring clusters are tilted with respect to each other; their superposition generates diffraction symmetry 2/m3̅5̅. The remaining Ho atoms act as glue atoms. As a result and as can be expected for real matter, local atomic coordinations in quasicrystals are similar when compared to common crystalline intermetallic compounds. From our results, the long range quasiperiodic structure of icosahedral Mg—Zn—RE(RE= Y and some rare earths) is anticipated to be a canonical cell tiling (CCT, after Henely) decorated with Bergman clusters.

Excellent clinical results with pulmonary autografts and experimental evidence that pulmonary valves can withstand the higher stress in the systemic circulation led us to use the cryopreserved pulmonary allograft for aortic valve replacement. From September 1988 until March 1993, 126 consecutive patients (61 ± 10 years; 74 men and 52 women) underwent aortic valve replacement with a cryopreserved pulmonary allograft. All allografts were inserted freehand in the subcoronary position. There were four in-hospital deaths (3.2%), and 1 patient had severe valvular incompetence immediately postoperatively, requiring reoperation after 4 weeks. One hundred twenty-one patients were followed up in 3- to 6-month intervals for 25.3 ±16.3 months (range, 6 to 66 months), and valve performance was assessed routinely by means of color-flow Doppler echocardiography. Nine patients (7.1%) died during follow-up. Two patients died of multiple septic emboli during bacterial endocarditis, and 1 patient died of a massive stroke. The other 6 patients died of myocardial infarction (4), respiratory insufficiency due to chronic obstructive lung disease (1), and carcinoma (1). Ninety-four patients (78%) had absent or trivial aortic valve regurgitation. Valvular incompetence class II was present in 3 patients (2.5%), whereas 5 others (4%) demonstrated class II to III. Severe aortic regurgita tion (class III or IV) could be detected in 10 patients (8.3%). All underwent reoperation and replacement of the valve with a prosthetic device. Bacterial endocarditis caused graft incompetence in 3 patients, valve degeneration was detected in another 3, and technical mistakes at valve implantation caused valve failure in the other 4. We assume that a mismatch in size between the allograft and the aortic annulus could have led to dilation of the allograft valve ring and consequently to central valvular incompetence in the patients without cusp degeneration. Cryopreserved pulmonary allografts achieve acceptable intermediate-term results, which can be improved if initial technical problems can be avoided. Disturbingly, the incidence of endocarditis in our series was higher than expected.

From November 1992 to October 1993 we randomized 101 patients over 60 years of age undergoing elective aortic valve replacement, with or without concomitant coronary artery bypass grafting, to receive either a cryopreserved aortic or pulmonary homograft (n = 38) or a stentless porcine aortic valve xenograft (Edwards Prima 2500) (n = 63). The majority of all valves (92%) were inserted freehand in the subcoronary position. Six homografts (16%) were implanted as a free-root replacement and two xenografts (3%) were used as a mini root. There were four in-hospital deaths (4%), three in the homograft group and one in the xenograft group (homograft, 7.9% versus xenograft, 1.6%; p= not significant). Forty-one patients were followed at 3- to 6-month intervals for 9 ± 2 months (3 to 14 months) and valve pathology was assessed routinely by means of color flow Doppler echocardiography. Two patients in the homograft group developed new aortic insufficiency grade II; all others remained with trivial or no valve incompetence. The mean gradient remained unchanged to immediate postoperative measurements (homograft, 5 ± 1 mm Hg versus xenograft, 11 ± 4 mm Hg; p< 0.001). Despite a slightly higher transvalvular gradient, xenografts achieved excellent initial results when compared to homografts. Ease of implantation and freedom from thromboembolism indicate that xenografts can be an acceptable alternative to homografts, particularly in older patients with small aortic annuli. Long-term studies assessing the durability of the xenograft are necessary for final evaluation.

AbstractMarkets for water quality and other ecosystem services are rapidly emerging across the country. One of the basic requirements that link buyers and sellers of ecosystem services is an agreed upon unit of trade and a way to measure it. The new Nitrogen Trading Tool (NTT) prototype provides a reliable, easy-to-use method of calculating nitrogen credits for water quality.The USDA Natural Resources Conservation Service (NRCS) developed the NTT in close cooperation with the USDA Agricultural Research Service's Soil Plant Nutrient Research Unit and the US Environmental Protection Agency (USEPA), with input from states, land grant universities, environmental brokers, and NRCS Conservation Innovation Grant recipients.In addition, regulators that oversee and certify point to nonpoint water quality trades have helped to guide the content of the NTT output reports. Thus, the USEPA knows how the nitrogen credits are calculated and is cognizant of the conservation measures that generate the credits.Quantifying the loss mechanisms of nutrients such as nitrogen is difficult (Delgado 2002). The NTT couples the scientifically rigorous Nitrogen Loss and Environmental Assessment Package (NLEAP) model (Shaffer and Delgado 2001; Shaffer et al. 2008) with a userfriendly, Web-based interface to allow the producer to easily calculate nitrogen savings from