Artificial organs
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Long-term mechanical circulatory assistance opened new problems in ventricular assist device-patient interaction, especially in relation to autonomic controls. Modeling studies, based on adequate models, could be a feasible approach of investigation. The aim of this work is the exploitation of a hybrid (hydronumerical) cardiovascular simulator to reproduce and analyze in vivo experimental data acquired during a continuous flow left ventricular assistance. ⋯ Results show that the simulator is able to reproduce animal-specific hemodynamic status both in physiological and pathological conditions, to reproduce cardiovascular left ventricular assist device (LVAD) interaction and the progressive unloading of the left ventricle for different pump speeds, and to investigate the effects of the LVAD on baroreflex activity. Results in chronic heart failure conditions show that an increment of LVAD speed from 20 000 to 22 000 rpm provokes a decrement of left ventricular flow of 35% (from 2 to 1.3 L/min). Thanks to its flexibility and modular structure, the simulator is a platform potentially useful to test different assist devices, thus providing clinicians additional information about LVAD therapy strategy.
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Letter Case Reports
HVAD implantation in right atrium-to-right pulmonary artery configuration.
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Membrane oxygenator (MO) failure is a known hazard during venovenous extracorporeal membrane oxygenation (v-v ECMO) therapy. Knowledge about technical and performance details of different ECMO systems (Maquet, Rastatt, Germany; Medos, Stolberg, Germany; Sorin, Modena, Italy) licensed for adults with acute lung failure might improve their handling. This retrospective study comprises 186 adult patients (Regensburg ECMO Registry) treated with v-v ECMO. ⋯ Despite different performances, all current commercially available adult v-v ECMO systems produce adequate blood flow without an increased risk in technical-induced hemolysis. Familiarity with the specific properties of individual systems allows early detection of technical complications. Additionally, the choice of an adequate cannula requires a closer consideration of the individual patient situation.
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Bivalirudin is a direct thrombin inhibitor that is increasingly used in patients undergoing mechanical circulatory support as it presents many advantages compared with unfractionated heparin. The aim of this study was to describe our experience with bivalirudin as primary anticoagulant in patients undergoing ventricular assist device (VAD) implantation. An observational study was performed on 12 consecutive patients undergoing VAD implantation at our institution. ⋯ Bivalirudin is a valuable option for anticoagulation in patients with a VAD and can be easily monitored with aPTT. The use of a bivalirudin-based anticoagulation strategy in the early postoperative period may overcome many limitations of heparin and, above all, the risk of HIT, which is higher in patients undergoing VAD implantation. Bivalirudin should no longer be regarded as a second-line therapy for anticoagulation in patients with VAD. [Correction added on 6 December 2013, after first online publication: The dose of bivalirudin in the Abstract to 0.025 mg/kg/h].
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Pulmonary changes in veno-venous extracorporeal membrane oxygenation (VV-ECMO) are rarely determined. We compared the contribution of VV-ECMO and cannulation based on the observation of pulmonary inflammatory reaction and parenchymal construction in a porcine model of low tidal volume (VT ) ventilation. We also evaluated the effect of adding continuous renal replacement therapy (CRRT) to the ECMO circuit, because CRRT is known to reduce systemic cytokine release induced by VV-ECMO. ⋯ In group 3, the pulmonary parenchyma and blood-air barrier were well preserved. We concluded that in a porcine model of low-VT ventilation, both VV-ECMO and VV-ECMO in combination with CRRT provided adequate oxygenation and carbon dioxide removal. Compared with VV-ECMO alone, VV-ECMO in combination with CRRT better preserved the lung parenchyma by eliminating systemic cytokines.