Changes in waiting time, need for mechanical circulatory support and outcomes in paediatric heart transplant recipients.

AIMS: Heart transplantation is a well-established treatment for end-stage heart failure in paediatric patients, demonstrating excellent long-term outcomes. METHODS: This retrospective study analyses 35 years of data on 244 paediatric recipients (<18 years) at a single institution from 1986 to 2022. The analysis explores changes in diagnoses, survival, waiting times and mechanical circulatory support (MCS) over three decades (1991-2000, 2001-2010 and 2011-2020). RESULTS: Survival outcomes significantly improved over the study period, with 1-year survival rates increasing from 79.3% (1991-2000) to 92.3% (2011-2020, P = 0.041). The median overall survival was 18.0 years, and median conditional survival to 1 year post-transplant was 20.9 years. Survival differences were noted among age groups, with infants under 1 year of age experiencing higher early mortality, and adolescents (aged 11-17 years) facing increased long-term risks, possibly linked to adult donor characteristics. Waiting times for heart transplantation increased, especially for younger age groups (0-5 and 6-10 years), reflecting the growing demand for donor organs. The use of MCS, including ventricular assist devices (VAD), surged, with 67% of recipients in the most recent decade receiving pre-transplant VAD support. Importantly, despite prolonged waiting times and increased VAD use, overall survival continued to be favourable. CONCLUSIONS: Early and long-term results after paediatric heart transplantation have been continuously improving over the past decades. Despite an increased demand for donor organs and the growing reliance on VAD as bridge to transplantation, post-transplantation survival is not compromised.

Value of nutritional indices in predicting survival free from pump replacement and driveline infections in centrifugal left ventricular assist devices.

Objective: There is a paucity of data assessing the impact of nutritional status on outcomes in patients supported with the HeartMate 3 (HM3) left ventricular assist device (LVAD). Methods: Patients ≥18 years of age who underwent HM3 LVAD implantation between 2015 and 2020 were identified from a single tertiary care center. The primary outcome assessed was death or device replacement. A secondary outcome of driveline infection was also evaluated. Kaplan-Meier survival analysis and a multivariate Cox-proportional hazards model were used to identify predictors of outcome. Results: Of the 289 patients identified, 94 (33%) experienced a primary outcome and 96 (33%) a secondary outcome during a median follow-up time of 2.3 years. Independent predictors of the primary outcome included peripheral vascular disease (hazard ratio [HR], 3.40; 95% confidence interval [CI], 1.66-6.97, P < .01), diabetes mellitus (HR, 0.46; 95% CI, 0.27-0.80, P < .01), body mass index ≥40 kg/m2 (HR, 2.63 per 1 kg/m2 increase; 95% CI, 1.22-5.70, P < .05), preoperative creatinine level (HR, 1.86 per 1 mg/dL increase; 95% CI, 1.31-2.65, P < .01), and preoperative prognostic nutritional index (PNI) score (HR, 0.88 per 1-point increase; 95% CI, 0.81-0.96, P < .01). Independent predictors of driveline infection included age at the time of implantation (HR, 0.97; 95% CI, 0.96-0.99, P < .01) and diabetes mellitus (HR, 1.79; 95% CI, 1.17-2.73, P < .01). Conclusions: Preoperative PNI scores may independently predict mortality and the need for device replacement in patients with HM3 LVAD. Routine use of the PNI score during preoperative evaluation and, when possible, supplementation to PNI >33, may be of value in this population.

Veno-arterial ECMO ventricular assistance as a direct bridge to heart transplant: A single center experience in a low-middle income country.

INTRODUCTION: The use of veno-arterial extracorporeal membrane oxygenation (VA-ECMO) as a direct bridge to heart transplantation (BTT) is not common in adults worldwide. BTT with ECMO is associated with increased early/mid-term mortality compared with other interventions. In low- and middle-income countries (LMIC), where no other type of short-term mechanical circulatory support is available, its use is widespread and increasingly used as rescue therapy in patients with cardiogenic shock (CS) as a direct bridge to heart transplantation (HT). OBJECTIVE: To assess the outcomes of adult patients using VA-ECMO as a direct BTT in an LMIC and compare them with international registries. METHODS: We conducted a single-center study analyzing consecutive adult patients requiring VA-ECMO as BTT due to refractory CS or cardiac arrest (CA) in a cardiovascular center in Argentina between January 2014 and December 2022. Survival and adverse clinical events after VA-ECMO implantation were evaluated. RESULTS: Of 86 VA-ECMO, 22 (25.5%) were implanted as initial BTT strategy, and 52.1% of them underwent HT. Mean age was 46 years (SD 12); 59% were male. ECMO was indicated in 81% for CS, and the most common underlying condition was coronary artery disease (31.8%). Overall, in-hospital mortality for VA-ECMO as BTT was 50%. Survival to discharge was 83% in those who underwent HT and 10% in those who did not, p < .001. In those who did not undergo HT, the main cause of death was hemorrhagic complications (44%), followed by thrombotic complications (33%). The median duration of VA-ECMO was 6 days (IQR 3-16). There were no differences in the number of days on ECMO between those who received a transplant and those who did not. In the Spanish registry, in-hospital survival after HT was 66.7%; the United Network of Organ Sharing registry estimated post-transplant survival at 73.1% ± 4.4%, and in the French national registry 1-year posttransplant survival was 70% in the VA-ECMO group. CONCLUSIONS: In adult patients with cardiogenic shock, VA-ECMO as a direct BTT allowed successful HT in half of the patients. HT provided a survival benefit in listed patients on VA-ECMO. We present a single center experience with results comparable to those of international registries.

A fluid-structure interaction simulation on the impact of transcatheter micro ventricular assist devices on aortic valves.

BACKGROUND AND OBJECTIVE: The implantation of ventricular assist devices (VADs) has become an important treatment option for patients with heart failure. Aortic valve insufficiency is a common complication caused by VADs implantation. Currently, there is very little quantitative research on the effects of transcatheter micro VADs or the intervention pumps on the aortic valves. METHODS: In this study, the multi-component arbitrary Lagrange-Eulerian method is used to perform fluid-structure interaction simulations of the aortic valve model with and without intervention pumps. The effects of intervention pumps implantation on the opening area of the aortic valves, the stress distribution, and the flow characteristics are quantitatively analyzed. Statistical results are consistent with clinical guidelines and experiments. RESULTS: The implantation of intervention pumps leads to the valve insufficiency and causes weak valve regurgitation. In the short-term treatment, the valve regurgitation is within a controllable range. The distribution and variation of stress on the leaflets are also affected by intervention pumps. The whirling flow in the flow direction affects the closing speed of the aortic valves and optimizes the stress distribution of the valves. In the models with whirling flow, the effects of intervention pumps implantation on valve motion and stress distribution differ from those without whirling flow. However, the valve insufficiency and valve regurgitation caused by intervention pumps still exist in the models with whirling flow. Conventional artificial bioprosthetic valves have limited effectiveness in treating the valve diseases caused by intervention pumps implantation. CONCLUSIONS: This study quantitatively investigates the impact of intervention pumps on the aortic valves, and investigates the effect of blood rotation on the valve behavior, which is a gap in previous research. We suggest that in the short-term treatment, the implantation of intervention pumps has limited impact on aortic valves, caution should be exercised against valve regurgitation issues caused by intervention pumps.

Obesity, Challenges, and Weight-Loss Strategies for Patients With Ventricular Assist Devices.

For adults with advanced heart failure, class II/III obesity (body mass index ≥35 kg/m2) represents major challenges, and it is even considered a contraindication for heart transplantation (HT) at many centers. This has led to growing interest in preventing and treating obesity to help patients with advanced heart failure become HT candidates. Among all weight-loss strategies, bariatric surgery (BSx) has the greatest weight loss efficacy and has shown value in enabling select patients with left ventricular assist devices (LVADs) and obesity to lose sufficient weight to access HT. Nevertheless, both BSx and antiobesity medications warrant caution in the LVAD population. In this review, the authors describe and interpret the available published reports on the impact of obesity and weight-loss strategies for patients with LVADs from general and HT candidacy standpoints. The authors also provide an overview of the journey of LVAD recipients who undergo BSx and review major aspects of perioperative protocols.

A review regarding the article 'Effectiveness of mechanical circulatory support devices in reversing pulmonary hypertension among heart transplant candidates: A systematic review.'

Pulmonary hypertension (PH) with high pulmonary vascular resistance (PVR) is a very often diagnosed contraindication for orthotopic heart transplantation (OHT). It is a direct consequence of left ventricle failure characterized by high diastolic pressure obstructing the collection of blood from the pulmonary vessels. The occurrence of this situation grows with the increasing time of waiting for OHT, and with the progression of heart failure. Mechanical circulatory support (MCS) devices, particularly left ventricular assist devices (LVADs), have emerged as pivotal interventions for patients with fixed PH, offering a potential bridge to transplantation. The pathophysiological impact of PH in heart transplant candidates is profound, as it is associated with increased perioperative risk and heightened mortality post-transplantation. The selection of heart transplant candidates thus mandates a careful evaluation of PH, with an emphasis on distinguishing between reversible and fixed forms of the condition. Reversible PH can often be managed with medical therapies; however, fixed PH presents a more daunting challenge, necessitating more aggressive interventions like MCS. Patients are supported with LVADs until evidence of pulmonary afterload reversal is evident and then can be considered for heart transplantation. However, in those who are non-responders or have complications while being supported, their option for transplant is revoked. Despite these advancements, the heterogeneity of MCS devices and their mechanisms of action necessitates a nuanced understanding of their efficacy.

"When I do have some time, rather than spend it polishing silver, I want to spend it with my grandkids": a qualitative exploration of patient values following left ventricular assist device implantation.

BACKGROUND: Values are broadly understood to have implications for how individuals make decisions and cope with serious illness stressors, yet it remains uncertain how patients and their family and friend caregivers discuss, reflect upon, and act on their values in the post-left ventricular assist device (LVAD) implantation context. This study aimed to explore the values elicitation experiences of patients with an LVAD in the post-implantation period. METHODS: Qualitative descriptive study of LVAD recipients. Socio-demographics and patient resource use were analyzed using descriptive statistics and semi-structured interview data using thematic analysis. Adult (> 18 years) patients with an LVAD receiving care at an outpatient clinic in the Southeastern United States. RESULTS: Interviewed patients (n = 27) were 30-76 years, 59% male, 67% non-Hispanic Black, 70% married/living with a partner, and 70% urban-dwelling. Three broad themes of patient values elicitation experiences emerged: 1) LVAD implantation prompts deep reflection about life and what is important, 2) patient values are communicated in various circumstances to convey personal goals and priorities to caregivers and clinicians, and 3) patients leverage their values for strength and guidance in navigating life post-LVAD implantation. LVAD implantation was an impactful experience often leading to reevaluation of patients' values; these values became instrumental to making health decisions and coping with stressors during the post-LVAD implantation period. Patient values arose within broad, informal exchanges and focused, decision-making conversations with their caregiver and the healthcare team. CONCLUSIONS: Clinicians should consider assessing the values of patients post-implantation to facilitate shared understanding of their goals/priorities and identify potential changes in their coping.

Perceptions of Bedside Nurses Caring for Patients with Left Ventricular Assist Devices (LVAD): A Qualitative Study.

Introduction: Bedside nurses in the intensive care units are exposed to multiple challenges in their regular practice and recently have taken in ventricular assist device care in Lebanon since its introduction as a fairly new practice. Objectives: To explore the experiences of nursing staff who work in Lebanese hospitals with Left Ventricular Assist Devices (LVAD). Methods: This study employed a qualitative phenomenological research design, where semi-structured interviews were carried out among fifteen LVAD nurses in an acute care hospital. Results: The qualitative data analysis produced six main themes. The first theme prevalent was "LVAD incompetence and shortage" and it reflected the deficit in properly structured training and the number of specialized LVAD nurses. The second theme that resulted from the analysis was titled, "Patient and family knowledge", which indicated the misconceptions that families and patients usually hold about LVAD which usually sugarcoats the situation. This was followed by "Burden of complications", "LVAD patient selection", "Perception of the LVAD team as invulnerable", and "High workload and patient frailty" which reflected the perspectives of LVAD nurses. Conclusion: This study shows that the Lebanese LVAD nurses who participated in this study perceived inadequate competence, yet lacked proper training and induction. The nurses reported multiple challenges relating to care tasks, workload, and patient and family interactions which need to be addressed by coordinators.

Mechanical circulatory support in patients with congenital heart disease: a European Registry for Patients with Mechanical Circulatory Support (EUROMACS) study.

OBJECTIVES: This study aims to explore characteristics and clinical outcomes of patients with congenital heart disease (CHD) in the European Registry for Patients with Mechanical Circulatory Support (EUROMACS). METHODS: This is a retrospective study of EUROMACS participants receiving MCS as bridge-to-transplant, possible bridge-to-transplant, or rescue therapy/bridge-to-recovery from 2011 to 2023 (n = 5340). Adult and paediatric cohorts were analysed separately. The primary outcome was mortality on MCS; secondary outcomes included recovery, transplant and complications including bleeding, cerebrovascular events, and sepsis. RESULTS: Among adult patients, mortality at 1-year was 33.3% among the CHD cohort vs 22.1% in the non-CHD cohort. Adult CHD patients had higher hazards of mortality within the first year after MCS implantation [hazard ratios 1.98, 95% confidence interval (CI) 1.35-2.91, P < 0.001] and bleeding events (subdistribution hazard ratios 2.10, 95% CI 1.40-3.16, P < 0.001) compared with non-CHD patients. Both associations remained significant after accounting for multiple mediators. Among paediatric patients, mortality at 1 year was 22.1% in the CHD cohort vs 17.3% in the non-CHD cohort (hazard ratios 1.39, 95% CI 0.83-2.32, P = 0.213). CONCLUSIONS: Adult and paediatric patients with CHD on MCS have higher adverse event risk compared with non-CHD MCS patients, though children did not have greater risk of mortality. As the number of CHD patients requiring advanced heart failure management continues to grow, these findings can enhance informed decision-making. CLINICAL TRIAL REGISTRATION NUMBER: Registry name: EUROMACS.

Advanced heart failure therapies in the Eastern Mediterranean Region: current status, challenges, and future directions.

While there has been a global decrease in rates of heart failure (HF) prevalence between 1990 and 2019, the Eastern Mediterranean region (EMR) is experiencing an increase. In 2019, approximately 1,229,766 individuals lived with moderate to severe HF in the EMR. Despite the growth in the utilization of advanced heart failure (AHF) therapies in the EMR in the past two decades, current volumes are yet to meet the growing AHF burden in the region. Heart transplantation (HT) volumes in EMR have grown from 9 in the year 2000 to 179 HTs in 2019. However, only a few centers provide the full spectrum of AHF therapies, including durable mechanical circulatory support (MCS) and HT. Published data on the utilization of left ventricular assist devices (LVAD) in the EMR are scarce. Notably, patients undergoing LVAD implantation in the EMR are on average, 13 year younger, and more likely to present with critical cardiogenic shock, as compared to their counterparts in the Western world. Furthermore, AHF care in the region is hampered by the paucity of multidisciplinary HF programs, inherent costs of AHF therapies, limited access to short and long-term MCS, organ shortage, and lack of public awareness and acceptance of AHF therapeutics. All stakeholders in the EMR should work together to strategize tackling the challenging AHF burden in the region.

Effectiveness of mechanical circulatory support devices in reversing pulmonary hypertension among heart transplant candidates: A systematic review.

BACKGROUND: Pulmonary hypertension (PH) poses a significant challenge in the selection of candidates for heart transplantation, impacting their eligibility and post-transplant outcomes. Mechanical circulatory support (MCS) devices, particularly left ventricular assist devices (LVADs), have emerged as a therapeutic option to manage PH in this patient population. This systematic review aims to evaluate the effectiveness of MCS devices in reversing fixed pulmonary hypertension in heart transplant candidates. METHODS: A comprehensive literature search was conducted across multiple databases, including PubMed, Scopus, and Web of Science, to identify studies that evaluated the effectiveness of MCS devices in reversing fixed pulmonary hypertension in heart transplant candidates. Data on pulmonary vascular resistance, PH reversal, heart transplant eligibility, and post-transplant outcomes were extracted and synthesized. RESULTS: The review included studies that demonstrated the potential of MCS devices, especially LVADs, to significantly reduce pulmonary vascular resistance and reverse fixed pulmonary hypertension in heart transplant candidates. These findings suggest that MCS devices can improve transplant eligibility and may positively impact post-transplant survival rates. However, the literature also indicates a need for further comparative studies to optimize MCS device selection and treatment protocols. CONCLUSION: MCS devices, particularly LVADs, play a crucial role in the management of fixed pulmonary hypertension in heart transplant candidates, improving their eligibility for transplantation and potentially enhancing post-transplant outcomes. Future research should focus on comparative effectiveness studies to guide clinical decision-making and optimize patient care in this challenging clinical scenario.

Hemodynamic management of cardiogenic shock in the intensive care unit.

Hemodynamic derangements are defining features of cardiogenic shock. Randomized clinical trials have examined the efficacy of various therapeutic interventions, from percutaneous coronary intervention to inotropes and mechanical circulatory support (MCS). However, hemodynamic management in cardiogenic shock has not been well-studied. This State-of-the-Art review will provide a framework for hemodynamic management in cardiogenic shock, including a description of the 4 therapeutic phases from initial 'Rescue' to 'Optimization', 'Stabilization' and 'de-Escalation or Exit therapy' (R-O-S-E), phenotyping and phenotype-guided tailoring of pharmacological and MCS support, to achieve hemodynamic and therapeutic goals. Finally, the premises that form the basis for clinical management and the hypotheses for randomized controlled trials will be discussed, with a view to the future direction of cardiogenic shock.

Preliminary report of extracorporeal blood purification therapy in patients receiving LVAD: Cytosorb or Jafron HA330.

BACKGROUND: Left ventricular assist device (LVAD) candidates are at increased risk of immune dysregulation and infectious complications. To attenuate the elevated proinflammatory cytokine levels and associated adverse clinical outcomes, it has been postulated that extracorporeal blood purification could improve the overall survival rate and morbidity of patients undergoing LVAD implantation. METHODS: We retrospectively reviewed prospectively collected data of 15 patients who underwent LVAD implantation at our center between January 2021 and March 2022. Of these, 15 (100%) who received HeartMate 3™ (St. Jude Medical, Abbott, MN, USA) device were eligible. Intraoperatively, patients were single randomized 1:1:1 to three groups: group 1, patients who received Cytosorb therapy (n = 5; installed in the CPB circuit); group 2, patients who received Jafron HA330 (n = 5; installed in the CPB circuit); and control group 3, patients who did not receive filter (n = 5; usual care, neither Cytosorb nor Jafron during CPB). Baseline patient characteristics and intraoperative data were compared between the groups. Blood sample analyses were performed to assess the levels of inflammatory markers (IL-1, 6, 8; CRP, Leukocyte, Lactate, PCT, NT-proBNP, TNF-α) in both preoperative and postoperative data. RESULTS: Baseline patient characteristics were similar in all three groups. We found that IL1α; IL 6; IL8; Lactatedehydrogenase, PCT, pro-BNP, CRP; Leukocyte, and TNFα levels significantly increased with LVAD implantation and that neither Cytosorb nor Jafron influenced this response. In-hospital mortality and overall survival during follow-up were similar among the groups. CONCLUSION: Our preliminary results showed that hemoadsorption therapy using Cytosorb or Jafron hemoadsorption (HA) 330 may not be clinically beneficial for patients with advanced heart failure undergoing LVAD implantation. Large prospective studies are needed to evaluate the potential role of HA therapy in improving outcomes in patients undergoing LVAD implantation.

Surgical Correction of Left Ventricular Assist Device Outflow Graft Obstruction Caused by a Wrapped Expanded Polytetrafluoroethylene Graft: A Case Report.

A 70-year-old man with dilated cardiomyopathy underwent left ventricular assist device (LVAD) implantation, using a HeartWare ventricular assist device, as a bridge to candidacy. After 26 months, computed tomography (CT) angiography indicated stenosis in the LVAD outflow graft; however, the patient was asymptomatic, prompting a decision to manage his condition with close monitoring. Ten months later, the patient presented with dizziness and low-flow alerts. Subsequent CT angiography revealed a critical obstruction involving the entire LVAD outflow graft. The patient underwent emergency surgery, during which an organized seroma causing the graft obstruction was found between a wrapped expanded polytetrafluoroethylene (ePTFE) graft and a Dacron outflow graft. The covering of the outflow graft was removed, along with the organized seroma. Following removal of the ePTFE wrap and decompression of the outflow graft, normal LVAD flow was reestablished. The practice of wrapping the outflow graft with synthetic material, commonly done to facilitate later redo sternotomy, may pose a risk for outflow graft obstruction.

Advanced Heart Failure: Therapeutic Options and Challenges in the Evolving Field of Left Ventricular Assist Devices.

Heart Failure is a chronic and progressively deteriorating syndrome that has reached epidemic proportions worldwide. Improved outcomes have been achieved with novel drugs and devices. However, the number of patients refractory to conventional medical therapy is growing. These advanced heart failure patients suffer from severe symptoms and frequent hospitalizations and have a dismal prognosis, with a significant socioeconomic burden in health care systems. Patients in this group may be eligible for advanced heart failure therapies, including heart transplantation and chronic mechanical circulatory support with left ventricular assist devices (LVADs). Heart transplantation remains the treatment of choice for eligible candidates, but the number of transplants worldwide has reached a plateau and is limited by the shortage of donor organs and prolonged wait times. Therefore, LVADs have emerged as an effective and durable form of therapy, and they are currently being used as a bridge to heart transplant, destination lifetime therapy, and cardiac recovery in selected patients. Although this field is evolving rapidly, LVADs are not free of complications, making appropriate patient selection and management by experienced centers imperative for successful therapy. Here, we review current LVAD technology, indications for durable MCS therapy, and strategies for timely referral to advanced heart failure centers before irreversible end-organ abnormalities.

Developments and Challenges in Durable Ventricular Assist Device Technology: A Comprehensive Review with a Focus on Advancements in China.

Heart transplantation is currently the most effective treatment for end-stage heart failure; however, the shortage in donor hearts constrains the undertaking of transplantation. Mechanical circulatory support (MCS) technology has made rapid progress in recent years, providing diverse therapeutic options and alleviating the dilemma of donor heart shortage. The ventricular assist device (VAD), as an important category of MCS, demonstrates promising applications in bridging heart transplantation, destination therapy, and bridge-to-decision. VADs can be categorized as durable VADs (dVADs) and temporary VADs (tVADs), according to the duration of assistance. With the technological advancement and clinical application experience accumulated, VADs have been developed in biocompatible, lightweight, bionic, and intelligent ways. In this review, we summarize the development history of VADs, focusing on the mechanism and application status of dVADs in detail, and further discuss the research progress and use of VADs in China.

Use of a surgically implanted, nondischargeable, extracorporeal continuous flow circulatory support system as a bridge to heart transplant.

INTRODUCTION AND OBJECTIVES: We aimed to describe the clinical outcomes of the use of the CentriMag acute circulatory support system as a bridge to emergency heart transplantation (HTx). METHODS: We conducted a descriptive analysis of the clinical outcomes of consecutive HTx candidates included in a multicenter retrospective registry who were treated with the CentriMag device, configured either for left ventricular support (LVS) or biventricular support (BVS). All patients were listed for high-priority HTx. The study assessed the period 2010 to 2020 and involved 16 transplant centers around Spain. We excluded patients treated with isolated right ventricular support or venoarterial extracorporeal membrane oxygenation without LVS. The primary endpoint was 1-year post-HTx survival. RESULTS: The study population comprised 213 emergency HTx candidates bridged on CentriMag LVS and 145 on CentriMag BVS. Overall, 303 (84.6%) patients received a transplant and 53 (14.8%) died without having an organ donor during the index hospitalization. Median time on the device was 15 days, with 66 (18.6%) patients being supported for> 30 days. One-year posttransplant survival was 77.6%. Univariable and multivariable analyses showed no statistically significant differences in pre- or post-HTx survival in patients managed with BVS vs LVS. Patients managed with BVS had higher rates of bleeding, need for transfusion, hemolysis and renal failure than patients managed with LVS, while the latter group showed a higher incidence of ischemic stroke. CONCLUSIONS: In a setting of candidate prioritization with short waiting list times, bridging to HTx with the CentriMag system was feasible and resulted in acceptable on-support and posttransplant outcomes.

Numerical simulation analysis of multi-scale computational fluid dynamics on hemodynamic parameters modulated by pulsatile working modes for the centrifugal and axial left ventricular assist devices.

Continuous flow (CF) left ventricular assist devices (LVAD) operate at a constant speed mode, which could result in increased risk of adverse events due to reduced vascular pulsatility. Consequently, pump speed modulation algorithms have been proposed to augment vascular pulsatility. However, the quantitative local hemodynamic effects on the aorta when the pump is operating with speed modulation using different types of CF-LVADs are still under investigation. The computational fluid dynamics (CFD) study was conducted to quantitatively elucidate the hemodynamic effects on a clinical patient-specific aortic model under different speed patterns of CF-LVADs. Pressure distribution, wall shear stress (WSS), time-averaged wall shear stress (TAWSS), oscillatory shear index (OSI), relative residence time (RRT), and velocity were calculated to compare their differences at constant and pulsatile speeds under centrifugal and axial LVAD support. Results showed that pulse pressure on the aorta was significantly larger under pulsatile speed mode than that under constant speed mode for both CF-LVADs, indicating enhanced aorta pulsatility, as well as the higher peak blood flow velocity on some representative slices of aorta. Pulsatile speed modulation enhanced peak WSS compared to constant speed; high TAWSS region appeared near the branch of left common carotid artery and distal aorta regardless of speed modes and CF-LVADs but these regions also had low OSI; RRT was almost the same for all the cases. This study may provide a basis for the scientific and reasonable selection of the pulsatile speed patterns of CF-LVADs for treating heart failure patients.

Computational investigation of outflow graft variation impact on hemocompatibility profile in LVADs.

BACKGROUND: Hemocompatibility-related adverse events (HRAE) occur commonly in patients with left ventricular assist devices (LVADs) and add to morbidity and mortality. It is unclear whether the outflow graft orientation can impact flow conditions leading to HRAE. This study presents a simulation-based approach using exact patient anatomy from medical images to investigate the influence of outflow cannula orientation in modulating flow conditions leading to HRAEs. METHODS: A 3D model of a proximal aorta and outflow graft was reconstructed from a computed tomography (CT) scan of an LVAD patient and virtually modified to model multiple cannula orientations (n = 10) by varying polar (cranio-caudal) (n = 5) and off-set (anterior-posterior) (n = 2) angles. Time-dependent computational flow simulations were then performed for each anatomical orientation. Qualitative and quantitative hemodynamics metrics of thrombogenicity including time-averaged wall shear stress (TAWSS), oscillatory shear index (OSI), endothelial cell platelet activation potential (ECAP), particle residence time (PRT), and platelet activation potential (PLAP) were analyzed. RESULTS: Within the simulations performed, endothelial cell activation potential (ECAP) and particle residence time (PRT) were found to be lowest with a polar angle of 85°, regardless of offset angle. However, polar angles that produced parameters at levels least associated with thrombosis varied when the offset angle was changed from 0° to 12°. For offset angles of 0° and 12° respectively, flow shear was lowest at 65° and 75°, time averaged wall shear stress (TAWSS) was highest at 85° and 35°, and platelet activation potential (PLAP) was lowest at 65° and 45°. CONCLUSION: This study suggests that computational fluid dynamic modeling based on patient-specific anatomy can be a powerful analytical tool when identifying optimal positioning of an LVAD. Contrary to previous work, our findings suggest that there may be an "ideal" outflow cannula for each individual patient based on a CFD-based hemocompatibility profile.