In silico study of the dynamic interaction between extracorporeal circulation and native circulation

An in silico investigation of modelled Extracorporeal Life Support (ECLS) via a femoral arterial cannula revealed the existence of both a defined separation zone between the opposing flows (ECLS, native flow) and different ranges dependent on flow distribution. The interaction between pulsating native circulation and constant ECLS flow is dynamic. A transient simulation model was developed to investigate the dynamic influence on this fluid mechanical interaction. The in silico model is based on a CT-generated 3D model derived from a life-sized silicon aorta. A geometric standard cannula (16Fr) is inserted femoral. Inlet boundary conditions such as the temporal flow profile of a subject from the left ventricle (native circulation) and the flow from the femoral cannula are varied such that during transient simulations the summed flow (total perfusion) is 5.5 l/min. The outlet pressure boundary conditions at the branching arteries are selected such as to model the downstream vascular system. Transient simulations revealed the dynamic effects of different flow fractions (Heart - ECLS) on the flow. Stationary simulations show a separation zone between the two flows, the position of which respectively the ECLSrange, oscillates dependent of the native circulation. Furthermore, it was noted that a raised pulse was impedimental to ECLS. This can be partly compensated by increasing the length of cannula inserted. At the same time the ECLS supply for the brain can improve at the cost of performance post-bifurcation. Increasing the ECLS fraction to above 50% flow led to retrograde flow combined with blood suction from the femoral artery. The EMPAC project model has been further developed to include investigation of the dynamic effects of blood flow. This has made it possible for the first time to analyse in detail and evaluate the temporal effects of both opposing flows streams. A subsequent investigation explains whether aortic elasticity plays a significant role

Cardiac surgery with crystalloid cardioplegia: Improved functional recovery due to molecular adaptations in adult rat hearts

Background: The effect of aging on functional recovery after a period of crystalloid cardioplegic arrest is still a matter of debate. We hypothesized that age-dependent differences in the polyamine metabolism may contribute to such differences. Methods: Hearts from juvenile and adult Wistar rats were placed in a perfused beating heart model and given Bretschneider's cardioplegia for an ischemia period of 60 min. During reperfusion, recovery of contractile function and coronary blood flow were measured for 90 min. In addition, adult hearts received putrescine to bypass polyamine metabolism during the 1st min of reperfusion. In comparison, the effect of putrescine was analyzed from hearts reperfused after 45-min flow arrest for 90 min. The rate-limiting enzyme of the polyamine metabolism, ornithine decarboxylase (ODC), the proapoptotic enzyme bax, and the relation between SR-calcium-ATPase (SERCA2a) and a natrium-calcium-exchanger enzyme were determined on mRNA-level through real-time polymerase chain reaction. Results: Adult hearts had lower basal performance and lower SERCA mRNA expression compared to juvenile hearts. However, after a 60-min aortic clamping period, recovery of left ventricular developed pressure (105.6 ± 39.7% of baseline) in the adult group was better than in the young group (61.3 ± 34.1% of baseline). ODC mRNA was significantly (P = 0.04228) lower in adult hearts (0.60 ± 0.09-fold vs. juvenile rats). Similar, bax mRNA was significantly (P = 0.01662) lower in adult hearts (0.22 ± 0.03-fold vs. juvenile rats). Addition of putrescine to adult hearts during reperfusion attenuated a better outcome of these hearts suggesting a detrimental effect of polyamine metabolism after cardioplegic arrest. In contrast, putrescine improved recovery in postischemic hearts without exposure to cardioplegic solution. Conclusion: Adult rat hearts tolerate cardioplegia-mitigated ischemia better than juvenile hearts because they express less ODC during resubstitution of normal calcium levels

Diagnostic dilemma of perioperative myocardial infarction after coronary artery bypass grafting: A review

Coronary artery bypass grafting (CABG) is one of the most commonly performed cardiac procedures in the United States (US) and Europe. In the US, perioperative morbidity and mortality related to CABG are below 5%. One of the most significant complications following CABG, however, is perioperative myocardial infarction (PMI). Cardiac biomarkers, intra- and post-operative echocardiography, and electrocardiography are routinely used to monitor for evidence of PMI. In this review, we seek to summarize how each of these modalities is used in the clinical setting to differentiate PMI from expected procedure-related changes, and how these findings impact patients' outcomes. We conclude that while no perfect diagnostic test for the detection of clinically meaningful PMI exists, using a combination of existing modalities with knowledge of expected post-procedure changes allows for early and reliable detection. Future development is needed to create more sensitive and specific modalities for the detection of PMI in patients undergoing CABG

Additional file 1: of Impact of prophylactic administration of Levosimendan on short-term and long-term outcome in high-risk patients with severely reduced left-ventricular ejection fraction undergoing cardiac surgery – a retrospective analysis

Generalized linear models Symbolic representation of the linear models used to estimate the effect of prophylactic Levosimendan and other predictors on 30-days survival, on postoperativ acute kidney injury (AKIN I-III) and on postoperative new-onset atrial fibrillation respectively. (DOCX 81 kb