A multi-scale cardiovascular system model can account for the load-dependence of the end-systolic pressure-volume relationship.

in BioMedical Engineering OnLine (2013), 12(1), 8

ABSTRACT: BACKGROUND: The end-systolic pressure-volume relationship is often considered as a load-independent property of the heart and, for this reason, is widely used as an index of ventricular ... [more ▼]

ABSTRACT: BACKGROUND: The end-systolic pressure-volume relationship is often considered as a load-independent property of the heart and, for this reason, is widely used as an index of ventricular contractility. However, many criticisms have been expressed against this index and the underlying time-varying elastance theory: first, it does not consider the phenomena underlying contraction and second, the end-systolic pressure volume relationship has been experimentally shown to be load-dependent. METHODS: In place of the time-varying elastance theory, a microscopic model of sarcomere contraction is used to infer the pressure generated by the contraction of the left ventricle, considered as a spherical assembling of sarcomere units. The left ventricle model is inserted into a closed-loop model of the cardiovascular system. Finally, parameters of the modified cardiovascular system model are identified to reproduce the hemodynamics of a normal dog. RESULTS: Experiments that have proven the limitations of the time-varying elastance theory are reproduced with our model: (1) preload reductions, (2) afterload increases, (3) the same experiments with increased ventricular contractility, (4) isovolumic contractions and (5) flow-clamps. All experiments simulated with the model generate different end-systolic pressure-volume relationships, showing that this relationship is actually load-dependent. Furthermore, we show that the results of our simulations are in good agreement with experiments. CONCLUSIONS: We implemented a multi-scale model of the cardiovascular system, in which ventricular contraction is described by a detailed sarcomere model. Using this model, we successfully reproduced a number of experiments that have shown the failing points of the time-varying elastance theory. In particular, the developed multi-scale model of the cardiovascular system can capture the load-dependence of the end-systolic pressure-volume relationship. [less ▲]

Structural model of the mitral valve included in a cardiovascular closed loop model. Static and dynamic validation

in proceedings of 8th IFAC Symposium on Biological and Medical Systems, Budapest 29-31 août 2012 (2012, August 31)

The new 2011 ACCF/AHA Guidelines on Coronary Artery Bypass Grafting Surgery: are they different from the 2010 ESC/EACTS Guidelines on Myocardial Revascularisation?

in EuroIntervention : Journal of EuroPCR in Collaboration with the Working Group on Interventional Cardiology of the European Society of Cardiology (2012), 8(1), 33-4

Retrospective medical record evaluation: reliability in assessing causation, preventability, and disability of adverse events.

in International Journal of Health Care Quality Assurance (2012), 25(8), 649-62

PURPOSE: The purpose of this article is to assess the reliability of an in-depth analysis on causation, preventability, and disability by two separate review teams on five selected adverse events in acute ... [more ▼]

PURPOSE: The purpose of this article is to assess the reliability of an in-depth analysis on causation, preventability, and disability by two separate review teams on five selected adverse events in acute hospitals: pressure ulcer, postoperative pulmonary embolism or deep vein thrombosis, postoperative sepsis, ventilator-associated pneumonia and postoperative wound infection. DESIGN/METHODOLOGY/APPROACH: The analysis uses a retrospective medical record review of 1,515 patient records by two independent teams in eight acute Belgian hospitals for the year 2005. The Mann-Whitney U-test is used to identify significant differences between the two review teams regarding occurrence of adverse events as well as regarding the degree of causation, preventability, and disability of found adverse events. FINDINGS: Team 1 stated a high probability for health care management causation in 95.5 per cent of adverse events in contrast to 38.9 per cent by Team 2. Likewise, high preventability was considered in 83.1 per cent of cases by Team 1 versus 51.7 per cent by Team 2. Significant differences in degree of disability between the two teams were also found for pressure ulcers, postoperative pulmonary embolism or deep vein thrombosis and postoperative wound infection, but not for postoperative sepsis and ventilator-associated pneumonia. ORIGINALITY/VALUE: New insight on the degree of and reasons for the huge differences in adverse event evaluation is provided. [less ▲]

ESC Guidelines for the diagnosis and treatment of acute and chronic heart failure 2012: The Task Force for the Diagnosis and Treatment of Acute and Chronic Heart Failure 2012 of the European Society of Cardiology. Developed in collaboration with the Heart Failure Association (HFA) of the ESC.

in European Heart Journal (2012), 33(14), 1787-847

Strengths and limits of risk stratification models in vascular surgery.

in European journal of vascular and endovascular surgery : the official journal of the European Society for Vascular Surgery (2012), 44(1), 62-3

2012 focused update of the ESC Guidelines for the management of atrial fibrillation: an update of the 2010 ESC Guidelines for the management of atrial fibrillation. Developed with the special contribution of the European Heart Rhythm Association.

in European Heart Journal (2012), 33(21), 2719-47

Assessment of ventricular contractility and ventricular-arterial coupling with a model-based sensor.

in Computer Methods & Programs in Biomedicine (2012)

Estimation of ventricular contractility and ventricular arterial coupling is clinically important in diagnosing and treating cardiac dysfunction in the critically ill. However, experimental assessment of ... [more ▼]

Estimation of ventricular contractility and ventricular arterial coupling is clinically important in diagnosing and treating cardiac dysfunction in the critically ill. However, experimental assessment of indexes of ventricular contractility, such as the end-systolic pressure-volume relationship, requires a highly invasive maneuver and measurements that are not typical in an intensive care unit (ICU). This research describes the use of a previously validated cardiovascular system model and parameter identification process to evaluate the right ventricular arterial coupling in septic shock. Model-based ventricular arterial coupling is defined by the ratio of the end systolic right ventricular elastance (E(esrvf)) over the pulmonary artery elastance (E(pa)) or the mean pulmonary inflow resistance (R(pulin)). Results are compared to the clinical gold-standard assessment (conductance catheter method). Six anesthetized healthy pigs weighing 20-30kg received a 0.5mgkg(-1) endotoxin infusion over a period of 30min from T0 to T30, to induce septic shock and veno-venous hemofiltration was used from T60 onward. The results show good agreement with the gold-standard experimental assessment. In particular, the model-based right ventricular elastance (E(esrvf)) correlates well with the clinical gold standard (R(2)=0.69) and the model-based non-invasive coupling (E(esrvf)/R(pulin)) follow the same trends and dynamics (R(2)=0.37). The overall results show the potential to develop a model-based sensor to monitor ventricular-arterial coupling in clinical real-time. [less ▲]

Cardiovascular modelling and the Intensive Care Unit clinician

in Proceedings of BMS 2012 (2012)

Analysis of Aortic Energetics from Pulse Wave Examination in a Porcine Study of Septic Shock

in Prceedings of BMS 2012 (2012)