Hybrid hemodynamic modeling for optimization of mechanical circulatory support systems

Mechanical circulatory support (MCS) systems are implantable devices designed to assist or replace the pumping function of a failing heart, ensuring adequate systemic circulation. Because they must operate continuously and under variable physiological loads, these systems require compact and energy-efficient electric drives. This study examines an MCS configuration that integrates a dual axial-flux permanent magnet synchronous motor (dual-AFPMSM) and operates it with a load-sharing strategy to improve overall efficiency and extend battery life. In the proposed approach, the torque demanded by the axial-flow pump is distributed between two identical AFPMSMs so that each motor operates closer to its high-efficiency region, thereby reducing AFPMSM losses; this is the fundamental mechanism behind the efficiency gain. The AFPMSM was integrated into the axial-flow pump with priority given to volumetric efficiency and unobstructed blood flow, and application-specific constraints were considered during the mechanical design. Finite element analysis (FEA) was used to validate motor performance under the target operating conditions. A comparison of single- and dual-AFPMSM operation shows that, under rest conditions, load sharing improves efficiency by 11.8%–17.4%, while under exercise conditions it improves efficiency by 6.5%–14.7%. This reduction in electrical power demand translates into up to a 14.6% increase in battery operating time during exercise. These results indicate that a dual-AFPMSM architecture with explicit load sharing is a promising option for next-generation MCS devices, providing reliable circulatory support with improved energy utilization and longer runtime.

Impaired hemostasis in mechanical circulatory support systems: Monitoring with T-TAS® 01, in vitro correction with VWF concentrates, and impact of membrane oxygenators.

Mechanical circulatory support (MCS) systems are increasingly employed in cardiogenic shock and advanced heart failure. A thorough understanding of the complex interactions occurring among heart, vasculature, and device is essential to optimize patient's management. The aim of this study is to explore non-invasive haemodynamic profiling of patients undergoing MCS based on pressure-strain (PS) analysis. Clinical and echocardiographic data from consecutive patients undergoing different MCS systems positioning/implantation admitted to the third level cardiological intensive care unit of Siena Hospital from August 2021 to November 2021 were retrospectively reviewed. Patients without a useful echocardiographic exam or without arterial blood pressure recording at the time of echocardiography were excluded. Myocardial work analysis was performed in the included patients. We reviewed 18 patients, of which nine were excluded. Included patients were three patients with intra-aortic balloon pump (IABP), two patients with durable left ventricular assist device (dLVAD), two patients with Impella®, one patient with extracorporeal membrane oxygenation (ECMO), and one patient with ECMO and IABP. Myocardial work analysis was feasible in each included patient. The use of IABP shifted the PS curve rightward and downward. Global work index (GWI) and global wasted work (GWW) decreased after IABP positioning, whereas global work efficiency (GWE) increased. The use of continuous-flow pumps, whether temporaneous (Impella®) or long term (dLVAD), induced a change in the PS loop morphology, with a shift towards a triangular shape. ECMO positioning alone resulted in a narrowing of the PS loop, with a decrease in GWI and GWE and an increase in GWW and mean arterial pressure. The combined used of IABP with ECMO widened the PS loop and improved GWI and GWE. PS loops analysis in patients undergoing MCS seems to be feasible and may unveil MCS-induced haemodynamic variations. Myocardial work could be used to monitor ventricular-arterial-device coupling and guide tailored MCS management.

We Enter the Bridge and Start to Run Out of Time

Does Mechanical Circulatory Support Prior to Heart Transplantation Influence Early Onset of Coronary Allograft Vasculopathy

BackgroundPediatric heart transplantation stays the gold standard treatment for end-stage heart failure, but outcomes are influenced by pre-transplant status and bridging strategies, particularly mechanical circulatory support (MCS).ObjectivesTo evaluate early outcomes following pediatric heart transplantation and assess the impact of pre-transplant MCS on survival and complications.MethodsWe retrospectively analyzed all pediatric patients (<14 years) who underwent orthotopic heart transplantation at a single tertiary center between January 2020 and January 2025. Demographics, pre-transplant support, intraoperative data, and early outcomes were collected. Primary outcome was 30-day survival; secondary outcomes included acute rejection, infection, acute kidney injury (AKI), neurologic complications, and ICU/hospital length of stay (LOS). Comparative analyses were performed between patients having ECMO- and ventricular assist devises (VAD) using Fisher's exact and Wilcoxon rank-sum tests. Kaplan–Meier survival estimates were generated.ResultsThirty patients were transplanted (median age 9 years, 63.3% female). Most (96.7%) needed MCS, including 11 ECMO and 18 VAD. Thirty-day survival was 28/30 (93.5%, 95% CI 78–99). Acute rejection occurred in 3 (10%), infections in 4 (13.3%), AKI in 8 (26.7%), with two requiring CRRT, and neurologic complications in 3 (10.3%). Median ICU and hospital LOS were 20 and 37 days, respectively. ECMO patients had longer post-transplant ventilation (12 vs 6 days, p = 0.04) and ICU length of stay (LOS) compared to VAD patients. Total Ischemic time, and CPB times were associated with increased morbidity.ConclusionsEarly outcomes after pediatric heart transplantation prove high short-term survival but substantial morbidity. ECMO bridging was associated with greater resource use than VAD. Improving donor heart ischemic time, donor-recipient matching, perioperative management, and early initiation of durable MCS may further improve outcomes.

Mechanical cardiac support 2000: current applications and future trial design: June 15-16, 2000 Bethesda, Maryland.

Implantable mechanical circulatory support (MCS) systems for ventricular assist device (VAD) therapy have emerged as an important strategy due to a shortage of donor organs for heart transplantation. A growing number of patients are receiving permanent assist devices, while fewer are undergoing heart transplantation (Htx). Continuous-flow (CF) pumps, as devices that can be permanently implanted, show promise for the treatment of both young and old patients with heart failure (HF). Further improvement of these devices will decrease adverse events, enable pulse modulation of continuous blood flow, and improve automatic remote monitoring. Ease of use for patients could also be improved. We herein report on the current state of the art regarding implantable CF pumps for use as MCS systems in the treatment of advanced refractory HF.

Purpose Mechanical circulatory support through left ventricular assist devices (LVAD) and extracorporeal membrane oxygenators (ECMO) is a reliable and useful support for bridge-to-transplantation (BTT) therapy. The purpose of this study was to investigate the impact of mechanical circulatory support on post-transplant prognosis and its changes during recent years. Methods The United Network for Organ Sharing (UNOS) database was used to identify adults patients (≥18 yrs) undergoing orthotopic heart transplantation (OHT) from 1987 to 2010. The cohort was separated into 5 groups according to the era of OHT: before '91, '92 to '96, '97 to '01, '02 to '06, and after '07. We compared two-year post-OHT survival of patients initially supported by an LVAD only and those with biventricular mechanical circulatory support at the time of OHT. Patients who required the additional use of ECMO during LVAD support and those with urgent assist device placement for right and left ventricule were considered as biventricular support group. Results A total of 17257 patients underwent OHT under mechanical circulatory support. Post-transplant mortality of patients with biventricular support was worse compared to patients with LVAD support alone after 1997 (Biventricular vs. LVAD alone, ’97-‘01, 56.3 vs. 77.0%, p=0.014; ’02-’06, 58.6% vs. 83.7%, p&lt;0.001; ’07- 60.9% vs. 87.7%, p&lt;0.001, respectively). Comparison among 5 groups by time period showed that post-transplant mortality of patients with LVAD support showed significant improvement after 1997. The mortality of patients with biventricular support, however, showed no improvement over time (Figure). Conclusion Post-transplant mortality in patients with LVAD BTT support improved significantly during the recent era of OHT. Patients undergoing biventricular support prior to OHT, especially those with hemodynamic instability requiring urgent ECMO placement on top of LVAD support remain to have poor outcome in any era of OHT.

The objective of this study was to evaluate the pump performance of the third-generation Medos diagonal pump, the Deltastream DP3, on hemodynamic profile and pulsatility in a simulated pediatric mechanical circulatory support (MCS) system. The experimental circuit consisted of a Medos Deltastream DP3 pump head and console (MEDOS Medizintechnik AG, Stolberg, Germany), a 14-Fr Terumo TenderFlow Pediatric arterial cannula and a 20-Fr Terumo TenderFlow Pediatric venous return cannula (Terumo Corporation, Tokyo, Japan), and 3 ft of tubing with an internal diameter of in. for both arterial and venous lines. Trials were conducted at flow rates ranging from 250 mL/min to 1000 mL/min (250-mL/min increments) and rotational speeds ranging from 1000 to 4000 rpm (1000-rpm increments) using human blood (hematocrit 40%). The postcannula pressure was maintained at 60 mm Hg by a Hoffman clamp. Real-time pressure and flow data were recorded using a Labview-based acquisition system. The pump provided adequate nonpulsatile and pulsatile flow, created more hemodynamic energy under pulsatile mode, and generated higher positive and negative pressures when the inlet and outlet of the pump head, respectively, were clamped. After the conversion from nonpulsatile to pulsatile mode, the flow rates and the rotational speeds increased. In conclusion, the novel Medos Deltastream DP3 diagonal pump is able to supply the required flow rate for pediatric MCS, generate adequate quality of pulsatility, and provide surplus hemodynamic energy output in a simulated pediatric MCS system.

Introduction: Due to the shortage of donor organs, mechanical circulatory support systems (MCS) are now widely used as a treatment option to bridge the failing heart to transplant. It has been observed that MCS patients show a higher frequency of antibody-mediated rejection (AMR) episodes. The latter is thought to represent an immune reaction directed against the device in terms of allosensitation. Hypothesis: Capillary C4d and/or C3d depositions are required to diagnose AMR in cardiac allografts. We aimed to analyze the effect of MCS on pre- and post-HTx HLA antibodies and their correlation to cardiac AMR with due regards to capillary C3d and C4d depositions. Methods: We evaluated all consecutive right ventricular protocol endomyocardial biopsies (EMBs) of cardiac allografts which fulfilled the ISHLT- criteria (254 patients) during two consecutive calendar years. With regards to pre- transplant MCS treatment patients were divided into two groups (MCS group n=82 patients, non MCS group n= 138 patients). Conventional histology and immunohistochemical stains were used on formalin-fixed paraffin-embedded tissue sections (FFPE) to evaluate the EMBs regarding AMR (complements C3d and C4d). Permutation test (x 2 ) was performed to analyze the relationship between C4d and C3d and pre-and post-transplant HLA-antibodies, measured using Luminex assay, in all patient subgroups. Cochran-Mantel-Haenzsel was performed to assure the significance of the difference of interactions in both tables. Results: The statistical analysis showed in the MCS group a highly significant positive correlation between C3d and Pre-Tx-HLA (p=0.012, Pre-Tx-HLA Class I and II p= 0.042, respectively vs p=0.884 and p=0.349 in non-MCS group), which levelled out following HTx (p= 0.867 and 0.697 for HLA Class I and II, vs p=0.212 and p=0.682 in non-MCS group, respectively). Statistical significance was not reached between C4d and pre-or post Tx HLA-antibodies in any group (p=0.349 vs. p=0.694 for entire study population). Conclusions: We demonstrated that C3d correlates solely in the MCS group with pre-Tx HLA antibodies and could therefore add to the diagnosis of AMR if the pre-transplant treatment is being considered in the diagnostic setting.

The cardiovascular system (CVS) is a complex and multifunctional system, the control of the parameters of which is a complex task. This study is aimed at solving the problem of analyzing the biotechnical system, consisting of CVS with an univentricular circulation and mechanical circulatory support systems. For this study, a specialized rotary mechanical circulation device was developed. In the course of experimental studies, the hydraulic characteristics of this device were obtained. We studied the biotechnical system at various configurations of the total cavopulmonary connection (TCPC-1, TCPC-2 and TCPC-3) and in the range of impeller rotations of 7000–14000 rpm. Based on the results of this study, we came to the conclusion that the TCPC-3 configuration better normalizes the parameters of the biotechnical system of mechanical circulatory support, and the range of the impeller operation is also determined, at which the system parameters do not exceed the critical level. By maintaining all parameters in a safe physiological range, cardiac output in the CVC with an univentricular circulation is increased by 20%. The results of this work can be used to optimize the control parameters of the circulatory support systems.

The field of pediatric heart failure is evolving, and the patient population is growing as survival after complex congenital heart surgeries is improving. Mechanical circulatory support and extracorporeal respiratory support in critically ill children has progressed to a mainstay rescue modality in pediatric intensive care medicine. The need for mechanical circulatory support is growing, since the number of organ donors does not meet the necessity. This article aims to review the current state of available mechanical circulatory and respiratory support systems in acute care pediatrics, with an emphasis on the literature discussing the challenges associated with these complex support modalities.

IntroductionMechanical circulatory support (MCS) is a recognised method of treatment for patients with end-stage chronic or acute heart failure. The POLCAS pulsatile-flow system has been used in our institution for 15 years. Currently, it is being widely replaced by continuous-flow mechanical circulatory support equipment of the second and third generations (HeartMateII, HeartWare). The MCS presented in this study is associated with a significant risk of complications and its use is increasingly considered controversial. The aim of the study was an evaluation of the results of treatment utilising the POLCAS MCS system at our institution in 2014.Material and methodsThe POLCAS system was implanted in 12 patients aged 16-63 years (42 ± 17 years) during a period of 12 months (from January to December, 2014). Full-blown cardiogenic shock was observed in all patients before MCS implantation. Four of the analysed patients (33%) required prior circulatory support with other devices: IABP (n = 2) or ECMO (n = 2). Episodes of cardiac arrest were reported in three patients; three other patients experienced serious arrhythmias, which accelerated the decision to implant MCS. The presented data was retrospectively obtained from the CliniNET system of the Institute of Cardiology. OpenOffice Calc spreadsheet was used for data analysis.ResultsAverage MCS time was 41 days ± 25 (from 15 to 91 days). Survival until transplantation or explantation was 91.67%. The most frequent complications following the therapy were: cardiac tamponade or bleeding requiring an intervention – 25% (n = 3), renal failure requiring dialysis – 25% (n = 3), ischaemic stroke associated with the MCS – 16.6% (n = 2), bacteraemia – 16.6% (n = 2), and wound infection – 8% (n = 1). No malfunctions of the MCS system were reported. Early survival in patients who completed the MCS therapy, defined as discharge, amounted to 63.6% (n = 7).ConclusionsThe POLCAS heart assist system is an effective method of treatment as a bridge to transplantation or recovery in patients with end-stage heart failure. Early survival after the treatment remains at a satisfactory level. The main problem is the large number of complications related to the therapy.

Background: Cardiogenic shock (CS), characterized by inadequate tissue perfusion due to cardiac dysfunction, has a high mortality rate despite advances in treatment. Systemic inflammation and organ failure exacerbate the severity of CS. Extracorporeal hemadsorption techniques such as CytoSorb® have been introduced to control inflammation. However, evidence of their efficacy, particularly in patients on various mechanical circulatory support (MCS) systems, remains limited. Methods: This retrospective study analyzed data from 129 CS patients treated with CytoSorb® at the University Hospital of Marburg between August 2019 and December 2023. Those patients receiving MCS were grouped according to MCS type: (1) Impella, (2) VA-ECMO, and (3) ECMELLA. The hemodynamic parameters of circulatory support (e.g., MCS flow rates and vasoactive inotropic score, VIS) and laboratory and ventilation parameters were assessed 24 h before start of CytoSorb® therapy (T1) and 24 h after completion of CytoSorb® therapy (T2). Results: Of 129 CS patients (mean age: 64.7 ± 13.1 years), 103 (79.8%) received MCS. Comparing T1 and T2, there was a significant reduction in VIS in the entire cohort (T1: 38.0, T2: 16.3; p = 0.002), with a concomitant significant reduction in the level of MCS support in all subgroups, indicating successful weaning. Analysis of laboratory parameters showed significant reductions in lactate (T1: 2.1, T2: 1.3 mmol/L; p = 0.014), myoglobin (T1: 1549.0, T2: 618.0 µg/L; p < 0.01), lactate dehydrogenase (T1: 872.0, T2: 632.0 U/L; p = 0.048), and procalcitonin (T1: 2.9, T2: 1.6 µg/L; p < 0.001). However, a significant decrease in platelets (T1: 140.0, T2: 54.0 tsd/µL; p < 0.001) and albumin (T1: 25.0, T2: 22.0 g/dL; p < 0.001) was also documented. The median SOFA score of the entire cohort was 15.0 (IQR 12.0-16.0), predicting a mortality rate of >80%, which could be reduced to 60.5% in the present study. Conclusions: During CytoSorb® therapy in CS, a significant reduction in VIS was demonstrated, resulting in improved organ perfusion. Therefore, the results of this study underline that CytoSorb® therapy can be considered a useful "component" in the complex management of CS, especially when combined with MCS. To refine and optimize treatment strategies in CS, prospective studies are needed to better define the role of hemadsorption.