Influence on fluid dynamics of coronary artery outlet angle variation in artificial aortic root prosthesis

<p>Abstract</p> <p>Background</p> <p>Because of higher life expectancy, the number of elderly patients today with degenerative aortic diseases is on the increase. Often artificial aortic roots are needed to replace the native tissue. This surgical procedure requires re-implantation of the previous separated coronary arteries into the wall of the prosthesis. Regardless of the prosthesis type, changes in the reinsertion technique, e.g., the variation of the outlet angle of the coronary arteries, could influence the coronary blood flow. Whether the prosthesis type or the outlet angle variation significantly improves the blood circulation and lowers the risk of coronary insufficiency is still an open question. The numerical calculations presented can help to clear up these disputable questions.</p> <p>Methods</p> <p>Two simplified base geometries are used for simulating the blood flow in order to determine velocity and pressure distributions. One model uses a straight cylindrical tube to approximate the aortic root geometry; the other uses a sinus design with pseudosinuses of Valsalva. The coronary outlet angle of the right coronary artery was discretely modified in both models in the range from 60° to 120°. The pressure and velocity distributions of both models are compared in the ascending aorta as well as in the right and the left coronary artery.</p> <p>Results</p> <p>The potentially allowed and anatomic limited variation of the outlet angle influences the pressure only a little bit and shows a very slight relative maximum between 70° and 90°. The sinus design and variations of the outlet angle of the coronary arteries were able to minimally optimize the perfusion pressure and the velocities in the coronary circulation, although the degree of such changes is rather low and would probably not achieve any clinical influence.</p> <p>Conclusion</p> <p>Our results show that surgeons should feel relatively free to vary the outlet angle within the anatomic structural conditions when employing the technique of coronary reinsertion.</p

Efficacy and Safety of Low-Dose Cyclosporine with Everolimus and Steroids in de novo Heart Transplant Patients: A Multicentre, Randomized Trial

A six-month, multicenter, randomized, open-label study was undertaken to determine whether renal function is improved using reduced-exposure cyclosporine (CsA) versus standard-exposure CsA in 199 de novo heart transplant patients receiving everolimus and steroids ± induction therapy. Mean C2 levels were at the low end of the target range in standard-exposure patients (n = 100) and exceeded target range in reduced-exposure patients (n = 99) throughout the study. Mean serum creatinine at Month 6 (the primary endpoint) was 141.0 ± 53.1 μmol/L in standard-exposure patients versus 130.1 ± 53.7 μmol/L in reduced-exposure patients (P = 0.093). The incidence of biopsy-proven acute rejection ≥3A at Month 6 was 21.0% (21/100) in the standard-exposure group and 16.2% (16/99) in the reduced-exposure group (n.s.). Adverse events and infections were similar between treatment groups. Thus, everolimus with reduced-exposure CsA resulted in comparable efficacy compared to standard-exposure CsA. No renal function benefits were demonstrated; that is possibly related to poor adherence to reduced CsA exposure

Focal Report 4: Risk Analysis: Cooperation in Civil Protection: EU, Spain, and the UK

The fourth focal report focuses on cooperation in civil protection and looks at institutional cooperation arrangements at the intergovernmental/supranational level (European Union) and the national level (Spain and UK). The first part is dedicated to civil protection in the European Union (EU). The EU Community Mechanism for Civil Protection is explored with a focus on the Mechanism s tools that aim to facilitate coordination and cooperation. The second part looks at the civil protection systems of Spain and the UK. It highlights different cooperation arrangements between local, regional, and central administrative levels, and between various actors involved in civil protection (multi-agency cooperation, interdepartmental cooperation). The third part draws on the insights of the two previous parts to discuss possible lessons for Switzerland. The report concludes with an annotated bibliography on civil protection in Spain, the UK, and the EU, including government documents, online sources, and academic literature

Adenylate-cyclase VI transforms ventricular cardiomyocytes into biological pacemaker cells

When sinus node or atrioventricular (AV) node cells are damaged by disease, the implantation of an artificial cardiac pacemaker becomes necessary. In search for a biological alternative, the objective of this study was to demonstrate whether in vivo adenoviral gene transfer of Adenylate-Cyclase type VI (AC-VI) can create biological pacemaker activity in a porcine AV node block model. Genetic therapy of arrhythmic disorders of the heart has been subject of extensive studies. Cyclic AMP is generated in response to Beta-adrenergic receptor stimulation and also binds to HCN channels, where it regulates spontaneous rhythmic activity in the sinus node. Adenoviruses encoding either AC-VI or Beta-Galactosidase (lacZ) gene were injected into the lateral wall of the left ventricle of adult pigs via anterolateral thoracotomy at a dose of 10(10) virus particles each. After 12 days, the AV node was ablated and three-dimensional electrophysiological cardiac mapping was performed using the Ensite electro-anatomical system. After rapid ventricular pacing and administration of Isoprenalin, all animals of the AC-VI group exhibited an escape rhythm originating from the area of the left ventricular injection site at a rate of 100 + 7 beats/min (n = 5), whereas the escape rhythms in the control group (n = 4) originated from the right ventricle. Western blot analysis of the injection sites revealed significantly higher expression of AC-VI in the respective group as compared with the control group. Our study demonstrates that AC-VI gene transfer has the potential to create a biological pacemaker system

Ex-Vivo Preservation with the Organ Care System in High Risk Heart Transplantation

Objective: Ex vivo organ perfusion is an advanced preservation technique that allows graft assessment and extended ex situ intervals. We hypothesized that its properties might be especially beneficial for high-risk recipients and/or donors with extended criteria. Methods: We reviewed the outcomes of 119 consecutive heart transplant patients, which were divided into two groups: A (OCS) vs. B (conventional). Ex vivo organ perfusion was performed using the Organ Care System (OCS). Indications for OCS-usage were expected ischemic time of &gt;4 h or &gt;2 h plus given extended donor criteria. Results: Both groups included mostly redo cases (A: 89.7% vs. B: 78.4%; p = 0.121). Incidences of donors with previous cardiac arrest (%) (A: 32.4 vs. B: 22.2; p &lt; 0.05) or LV-hypertrophy (%) (A: 19.1 vs. B: 8.3; p = 0.119) were also increased in Group A. Ex situ time (min) was significantly longer in Group A (A: 381 (74) vs. B: 228 (43); p &lt; 0.05). Ventilation time (days) (A: 10.0 (19.9) vs. B: 24.3 (43.2); p = 0.057), postoperative need for ECLS (%) (A: 25.0 vs. B: 39.2; p = 0.112) and postoperative dialysis (chronic) (%) (A: 4.4 vs. B: 27.5; p &lt; 0.001) were numerically better in the OCS group, without any difference in the occurrence of early graft rejection. The 30-d-survival (A: 92.4% vs. B: 90.2%; p = 0.745) and mid-term survival were statistically not different between both groups. Conclusions: OCS heart allowed safe transplantation of surgically complex recipients with excellent one-year outcomes, despite long preservation times and unfavourable donor characteristics. Furthermore, we observed trends towards decreased ventilation times and fewer ECLS treatments. In times of reduced organ availability and increasing recipient complexity, OCS heart is a valuable instrument that enables otherwise infeasible allocations and contributes to increase surgical safety

Sympathetic vasoconstrictor activity before and after left ventricular assist device implantation in patients with end-stage heart failure

Aims Sympathetic overactivity, which predicts poor outcome in patients with heart failure, normalizes following cardiac transplantation. We tested the hypothesis that haemodynamic improvement following left ventricular assist device (LVAD) implantation is also associated with reductions in centrally generated sympathetic activity. Methods and results In eight patients with heart failure (two women, six men, age 44-66 years), we continuously recorded electrocardiogram, beat-to-beat finger blood pressure, respiration, and muscle sympathetic nerve activity (MSNA) before and after implantation of the continuous-flow LVAD devices HeartWare HVAD (n = 4) and HeartMate II (n = 2), and the non-continuous-flow device HeartMate 3 (n = 2). LVAD implantation increased cardiac output by 1.29 +/- 0.88 L/min (P = 0.060) and mean arterial pressure by 16.2 +/- 7.9mmHg (P < 0.001), while reducing pulse pressure by 25.3 +/- 9.8mmHg (P < 0.001). LVAD implantation did not change MSNA burst frequency (-1.3 +/- 7.5 bursts/min, P = 0.636), total activity (+0.62 +/- 1.83 au, P = 0.369), or normalized activity (+0.63 +/- 4.23, P = 0.685). MSNA burst incidence was decreased (-7.8 +/- 9.3 bursts/100 heart beats, P = 0.049). However, cardiac ectopy altered MSNA bursting patterns that could be mistaken for sympatholysis. Conclusion Implantation of current design LVAD does not consistently normalize sympathetic activity in patients with end-stage heart failure despite haemodynamic improvement