Numerical and Experimental Investigation of Vascular Suture Closure

Purpose — In order to optimize the performance of the suture for tissue closure, it is essential to develop strategies for devising new and improved techniques that can visualize and compare various suturing techniques. This paper describes an experimental and numerical investigation on the performance of sutured tissue. Methods — In the experiments, two pieces of glutaraldehyde cross-linked bovine pericardium were sutured together through simple running suture and tensioned to study the performance of the sutured tissue. During testing, the tension load and the total displacement of the specimen were recorded. The strain field of the specimen was simultaneously captured using two high speed cameras and post processed using its associated image processing software. In addition, nonlinear hyperelastic material models for Shelhigh patch and cryopreserved human aorta were derived through least-square fitting into the tensile testing data. Three dimensional finite element models were developed to replicate the behavior of wound closure. Results — The effect of tissue material mismatch, and stiffness of the suture thread on the mechanical behavior of sutured tissue was examined. The stain distributions obtained from simulation agrees with the captured surface strain map from experiments. A relative softer suture thread could reduce the peak stress concentrations at the knotting location. Conclusions — The mechanical performance of sutured tissue depends on the level of mismatch in material stiffness between the native tissue and the replacement materia

Implementation and performance of SIBYLS: a dual endstation small-angle X-ray scattering and macromolecular crystallography beamline at the Advanced Light Source.

The SIBYLS beamline (12.3.1) of the Advanced Light Source at Lawrence Berkeley National Laboratory, supported by the US Department of Energy and the National Institutes of Health, is optimized for both small-angle X-ray scattering (SAXS) and macromolecular crystallography (MX), making it unique among the world's mostly SAXS or MX dedicated beamlines. Since SIBYLS was commissioned, assessments of the limitations and advantages of a combined SAXS and MX beamline have suggested new strategies for integration and optimal data collection methods and have led to additional hardware and software enhancements. Features described include a dual mode monochromator [containing both Si(111) crystals and Mo/B(4)C multilayer elements], rapid beamline optics conversion between SAXS and MX modes, active beam stabilization, sample-loading robotics, and mail-in and remote data collection. These features allow users to gain valuable insights from both dynamic solution scattering and high-resolution atomic diffraction experiments performed at a single synchrotron beamline. Key practical issues considered for data collection and analysis include radiation damage, structural ensembles, alternative conformers and flexibility. SIBYLS develops and applies efficient combined MX and SAXS methods that deliver high-impact results by providing robust cost-effective routes to connect structures to biology and by performing experiments that aid beamline designs for next generation light sources

Williams Syndrome and Neonatal Cardiac Surgery for Congenital Single Ventricle

Williams syndrome (WS) is an arteriopathic derangement associated with supravalvular aortic stenosis and branch pulmonary stenosis. We describe double-outlet right ventricle with mitral atresia and aortic arch hypoplasia in an infant with WS. This case demonstrates the difficulty in managing patients with WS with complex cardiac defects. To our knowledge, this is the first reported single-ventricle physiology in a patient with WS. (Level of Difficulty: Advanced.)

Infundibular sparing versus transinfundibular approach to the repair of tetralogy of Fallot

IntroductionThe right ventricular infundibular sparing approach (RVIS) to the repair of tetralogy of Fallot (TOF) avoids a full‐thickness ventricular incision, typically utilized in the transinfundibular (TI) method.MethodsWe performed a retrospective, age‐matched cohort study of patients who underwent RVIS at Texas Children’s Hospital or TI at Children’s Hospital Medical Center in Nebraska and subsequently underwent cardiac magnetic resonance imaging (CMR). We compared right ventricular end‐diastolic and systolic volumes indexed to body surface area (RVEDVi and RVESVi) and right ventricular ejection fraction (RVEF) as primary endpoints. Secondary endpoints were indexed left ventricular diastolic and systolic volume (LVEDVi and LVESVi), left ventricular ejection fraction (LVEF), right ventricular (RV) sinus ejection fraction (EF) and RV outflow tract EF (RVOT EF).ResultsSeventy‐nine patients were included in the analysis; 40 underwent RVIS and 39 underwent TI repair. None of the patients in the TI repair group had an initial palliation with a systemic to pulmonary arterial shunt compared to seven (18%) in the RVIS group (P < .01). There was no appreciable difference in RVEDVi (122 ± 29 cc/m2 vs 130 ± 29 cc/m2, P = .59) or pulmonary regurgitant fraction (40 ± 13 vs 37 ± 18, P = .29) between the RVIS and TI groups. Compared to the TI group, the RVIS group had higher RVEF (54 ± 6% vs 44 ± 9%, P < .01), lower RVESV (57 ± 17 cc/m2 vs 67 ± 25 cc/m2, P = .03), higher LVEF (61 ± 11% vs 54 ± 8%, P < .01), higher RVOT EF (47 ± 12% vs 41 ± 11%, P = .03), and higher RV sinus EF (56 ± 5% vs 49 ± 6%, P < .01)ConclusionsIn this selected cohort, patients who underwent RVIS repair for TOF had higher right and left ventricular ejection fraction compared to those who underwent TI repair.Peer Reviewedhttps://deepblue.lib.umich.edu/bitstream/2027.42/152818/1/chd12863_am.pdfhttps://deepblue.lib.umich.edu/bitstream/2027.42/152818/2/chd12863.pd

Prevention of arteriovenous shunt occlusion using microbubble and ultrasound mediated thromboprophylaxis.

BACKGROUND: Palliative shunts in congenital heart disease patients are vulnerable to thrombotic occlusion. High mechanical index (MI) impulses from a modified diagnostic ultrasound (US) transducer during a systemic microbubble (MB) infusion have been used to dissolve intravascular thrombi without anticoagulation, and we sought to determine whether this technique could be used prophylactically to reduce thrombus burden and prevent occlusion of surgically placed extracardiac shunts. METHODS AND RESULTS: Heparin-bonded ePTFE tubular vascular shunts of 4 mm×2.5 cm (Propaten; W.L Gore) were surgically placed in 18 pigs: a right-sided side-to-side arteriovenous (AV, carotid-jugular) shunt, and a left-sided arterio-arterial (AA, carotid-carotid) interposition shunt in each animal. After shunt implantation, animals were randomly assigned to one of 3 groups. Transcutaneous, weekly 30-minute treatments (total of 4 treatments) of either guided high MI US+MB (Group 1; n=6) using a 3% MRX-801 MB infusion, or US alone (Group 2; n=6) were given separately to each shunt. The third group of 6 pigs received no treatments. The shunts were explanted after 4 weeks and analyzed by histopathology to quantify luminal thrombus area (mm2) for the length of each shunt. No pigs received antiplatelet agents or anticoagulants during the treatment period. The median overall thrombus burden in the 3 groups for AV shunts was 5.10 mm2 compared with 4.05 mm(2) in AA (P=0.199). Group 1 pigs had significantly less thrombus burden in the AV shunts (median 2.5 mm2) compared with Group 2 (median 5.6 mm2) and Group 3 (median 7.5 mm2) pigs (P=0.006). No difference in thrombus burden was seen between groups for AA shunts. CONCLUSION: Transcutaneous US with intravenous MB is capable of preventing thrombus accumulation in arteriovenous shunts without the need for antiplatelet agents, and may be a method of preventing progressive occlusion of palliative shunts

Microbubble mediated thrombus dissolution with diagnostic ultrasound for the treatment of chronic venous thrombi.

BACKGROUND: Central venous catheter (CVC) thrombi result in significant morbidity in children, and currently available treatments are associated with significant risk. We sought to investigate the therapeutic efficacy of microbubble (MB) enhanced sonothrombolysis for aged CVC associated thrombi in vivo. METHODS AND RESULTS: A model of chronic indwelling CVC in the low superior vena cava with thrombus in situ was established after feasibility and safety testing in 7 pigs; and subsequently applied for repeated, sonothrombolytic treatments in 9 pigs (total 24 treatments). Baseline intracardiac echocardiography (ICE, 10.5F, Siemens), fluoroscopy and saline flushing confirmed the absence of any pre-existing CVC thrombus. A thrombus was then allowed to form and age over 24 hours. The created thrombus was localized and measured by ICE, and transthoracic image guided high mechanical index (MI) two-dimensional US treatments (1.1-1.7 MI; iE33, Philips) applied intermittently whenever intravenously infused MBs (3% MRX-801; NuVox) were visualized near the thrombus (n = 10; Group A). Control pigs (n = 10; Group B) received US without MB. All treatments were randomized. Post-treatment thrombus area by ICE planimetry was compared with pre-treatment measurements. Thrombus area measurements before and after treatment were 0.22 and 0.10 cm(2) respectively in Group A; compared to 0.24 and 0.21 cm(2) in Group B (p  = 0.0003). Effectiveness of longer duration US and MB thrombolytic treatments were studied (n = 4), which suggested that near complete thrombus dissolution is possible. No pulmonary emboli, alterations in oxygen saturation, or hemodynamics occurred with either treatment. CONCLUSIONS: Guided high MI diagnostic US+systemic MB facilitates reduction of aged CVC associated thrombi in vivo. MB enhanced sonothrombolytic therapy may be a non-invasive safe alternative to thrombolytic agents in treating thrombotic CVC occlusions

A baseline method for benchmarking mortality losses in Atlantic salmon (Salmo salar) production

On-farm databases provide a large diversity of information regarding fish health and stock performance. Mortality records held in on-farm database are indicators of fish health status and of great interest for studying fish health, such as patterns of diseases. Mortality records from a Scottish Atlantic salmon production database of one company were used to develop a method of benchmarking production losses due to mortality. The records used concerned mortality loss numbers of Atlantic salmon in the seawater phase. The median, 10th and 90th percentiles of mortality were calculated for each week of production from 88 production recorded cycles. These values were used to delimit the range of a standard mortality curve through the production cycle. The effects of the different mortality losses from each cycle on production in terms of costs and time consumed were also described. Likewise, substantial interannual variation in mortality time series is described as well as the mortality variation associated with three diseases (Pancreas Disease, Cardiomyopathy Syndrome and Infectious Pancreatic Necrosis)