Left Ventricular Assist Device Speed Research Articles

A Computational Investigation of the Effects of Temporal Synchronization of Left Ventricular Assist Device Speed Modulation with the Cardiac Cycle on Intraventricular Hemodynamics.

Patients with advanced heart failure are implanted with a left ventricular assist device (LVAD) as a bridge-to-transplantation or destination therapy. Despite advances in pump design, the risk of stroke remains high. LVAD implantation significantly alters intraventricular hemodynamics, where regions of stagnation or elevated shear stresses promote thrombus formation. Third generation pumps incorporate a pulsatility mode that modulates rotational speed of the pump to enhance in-pump washout. We investigated how the timing of the pulsatility mode with the cardiac cycle affects intraventricular hemodynamic factors linked to thrombus formation. Computational fluid dynamics simulations with Lagrangian particle tracking to model platelet behavior in a patient-specific left ventricle captured altered intraventricular hemodynamics due to LVAD implantation. HeartMate 3 incorporates a pulsatility mode that modulates the speed of the pump every two seconds. Four different timings of this pulsatility mode with respect to the cardiac cycle were investigated. A strong jet formed between the mitral valve and inflow cannula. Blood stagnated in the left ventricular outflow tract beneath a closed aortic valve, in the near-wall regions off-axis of the jet, and in a large counterrotating vortex near the anterior wall. Computational results showed good agreement with particle image velocimetry results. Synchronization of the pulsatility mode with peak systole decreased stasis, reflected in the intraventricular washout of virtual contrast and Lagrangian particles over time. Temporal synchronization of HeartMate 3 pulsatility with the cardiac cycle reduces intraventricular stasis and could be beneficial for decreasing thrombogenicity.

Impact of Interventricular Interaction on Ventricular Function: Insights From Right Ventricular Pressure-Volume Analysis

BackgroundInterventricular interactions may be responsible for the decline in ventricular performance observed in various disease states that primarily affect the contralateral ventricle. ObjectivesThis study sought to quantify the impact of such interactions on right ventricular (RV) size and function using clinically stable individuals with left ventricular assist devices (LVADs) as a model for assessing RV hemodynamics while LV loading conditions were acutely manipulated by changing device speed during hemodynamic optimization studies (ie, ramp tests). MethodsThe investigators recorded RV pressure-volume loops with a conductance catheter at various speeds during ramp tests in 20 clinically stable HeartMate3 recipients. ResultsWith faster LVAD speeds and greater LV unloading, indexed RV end-diastolic volume increased (72.28 ± 15.07 mL at low speed vs 75.95 ± 16.90 at high speed; P = 0.04) whereas indexed end-systolic volumes remained neutral. This resulted in larger RV stroke volumes and shallower end-diastolic pressure-volume relationships. Concurrently, RV end-systolic pressure decreased (31.58 ± 9.75 mL at low speed vs 29.58 ± 9.41 mL at high speed; P = 0.02), but contractility, as measured by end-systolic elastance, did not change significantly. The reduction in RV end-systolic pressure was associated with a reduction in effective arterial elastance from 0.65 ± 0.43 mm Hg/mL at low speed to 0.54 ± 0.33 mm Hg/mL at high speed (P = 0.02). ConclusionsInterventricular interactions resulted in improved RV compliance, diminished afterload, and did not reduce RV contractility. These data challenge the prevailing view that interventricular interactions compromise RV function, which has important implications for the understanding of RV-LV interactions in various disease states, including post-LVAD RV dysfunction.

HeartWare Left Ventricular Assist Device Exercise Hemodynamics With Speed Adjustment Based on Left Ventricular Filling Pressures.

Functional capacity remains limited in heart failure patients with left ventricular assist devices (LVADs) due to fixed pump speed and inability to offload the left ventricle adequately. We hypothesized that manually adjusting LVAD speed during exercise based on pulmonary capillary wedge pressures would increase total cardiac output and maximal oxygen consumption. Two participants with a HeartWare LVAD underwent an invasive ramp study at rest followed by an invasive cardiopulmonary stress test exercising in two randomized phases: fixed speed and adjusted speed. In the latter phase, speed was adjusted every 1 minute during exercise at ±20 rpm/1 mm Hg change from baseline pulmonary capillary wedge pressure. There was no difference in maximal oxygen consumption between the two phases, with a modest increase in total cardiac output during speed adjustment. Filling pressures were initially controlled during speed adjustment until speed was capped at 4,000 rpm, at which point filling pressures increased. Blood pressure was variable. The pressure across the head of the pump (ΔP) was higher with speed adjustment. Contrary to our hypothesis, LVAD speed adjustment during exercise did not improve total cardiac output and functional capacity. This variable response may be attributed to the native cardiac reserve and baroreceptor response; however, additional studies are needed.

Abstract 15773: The Forgotten Ventricle: Insight Into Dynamic Effects of Left Ventricular Assist Device Ramp on Right Ventricle Function

Introduction: Left ventricular assist devices (LVAD) with magnetically levitated impellers have become standard due to hemocompatibility and survival profile. To optimize LVAD speeds, we previously introduced simultaneous right and left heart (RH/LH) catheterization during ramp studies. Here, we report pairing of this approach with pressure-volume (PV) assessment in a patient with a HeartMate 3 LVAD with mitral regurgitation (MR). The combined approach evaluated left ventricular (LV) hemodynamics and right ventricular (RV) PV-relationships during ramp testing. Methods: A 68-year-old male with ischemic cardiomyopathy, two years following HeartMate3 implantation, presented with NYHA class III symptoms. To evaluate for dyspnea, he underwent a RH/LH catheterization ramp study. RV PV-loops were created by use of a conductance catheter system, allowing creation of PV loops. Results: At the baseline LVAD speed of 5300 rotations per minute (RPM), right atrial pressure was elevated at 16 mmHg and pulmonary artery (PA) pressure of 26 mmHg. Left-end diastolic pressure (LVEDP) was elevated (16mmHg). Baseline cardiac index (CI) was 2.01 L/min/m 2 . Ramp testing was performed, increasing speeds from 5300 to 5800 RPM. Progressive LV unloading was observed with a 5 mmHg drop in LVEDP and a 3 mmHg drop in PA pressure. However, RV PV loop monitoring revealed a negative impact on RV contractility with the maximal elastance (Emax) slope demonstrating a 22% reduction. Furthermore, a 17% reduction in RV stroke volume was documented, while diastolic function remained unchanged. Thus, despite excellent LV offloading and diminishment of RV afterload, the significant negative impact on Emax resulted in no net increase in CI (+0.04 L/min/m 2 ) during the ramp evaluation. Inotrope therapy was initiated for RV function with increased LVAD RPM to outcompete MR. Conclusions: While RH/LH catheterization provides a real-time perspective of the interventricular relationship during ramp, the impact of increasing LVAD speeds on RV function has yet to be directly measured. Here, the RV PV loop relationship during LVAD ramp showed that although LVAD speed increases in the setting of MR may facilitate LV unloading, a drop in RV afterload did not compensate for reduction in RV contractility.

Abstract 15140: Cerebral Hemodynamics During Left Ventricular Assist Device Speed Titration

Introduction: Left ventricular assist device (LVAD) speed may be titrated to optimize cardiopulmonary hemodynamics, but the impact on cerebral blood flow remains poorly understood. Hypothesis: Here, we monitored cerebral hemodynamics during ramp studies, to test the hypothesis that LVAD speed correlates with cerebral blood flow and cerebral autoregulation. Methods: Patients with HeartMate3 LVADs underwent ramp study for optimization, during which cerebral blood flow velocity (CBFv) was continuously monitored by transcranial Doppler (TCD), and blood pressure was continuously monitored by finger plethysmography. Mx index was used a measure of autoregulation which correlates blood pressure and CBFv (i.e. high Mx index indicates poor autoregulation). The treating cardiologist determined the optimal speed based on cardiopulmonary dynamics (other speeds were categorized as sub-optimal). Results: Of 23 patients, 5 did not undergo speed changes. At least two speeds were explored in the remaining 18 patients. When comparing the lowest and highest speeds for each patient, higher speeds resulted in higher CBFv (p=0.02; Figure 1a ), but no change in autoregulation (p=0.38; Figure 1b ). However, when comparing the optimal and suboptimal LVAD speeds, CVFv was similar (p=0.89; Figure 2a ,), whereas the optimal speed was associated with a trend toward favorable autoregulation (p=0.09; Figure 2b ). Conclusions: Cerebral blood flow velocity is sensitive to LVAD speed titration, and cardiopulmonary optimization may improve cerebral autoregulation. A larger cohort and a broader range of speeds may further clarify the impact of speed titration on cerebral hemodynamics.

Abstract 18267: Successful C-Section Delivery at 36 Weeks in a Patient With a Heartmate 3 LVAD

Introduction: Pregnancy in patients with advanced heart failure requiring left ventricular assist device (LVAD) support is risky and discouraged, though there are cases of successful deliveries. Hypothesis: A 29-year-old G3P2002 female with history of embolic cerebrovascular accident, postpartum hemorrhage, peripartum cardiomyopathy status-post HeartMate 3 (HM3) LVAD, became pregnant after intrauterine device dislodgement. She elected to continue the pregnancy against the advice of maternal-fetal medicine (MFM). A multidisciplinary team convened to plan for delivery. Methods: Warfarin and sacubitril-valsartan were stopped due to teratogenicity. Therapeutic anticoagulation with enoxaparin injections was started. Aspirin was continued. Low-dose digoxin was added for right ventricular support. A multidisciplinary team involving anesthesiology, MFM, and advanced heart failure (AHF) was convened. Through patient-centered shared decision-making, cesarean delivery was planned for 36 weeks. She was seen by MFM and AHF every two weeks with LVAD speed optimization under transthoracic echocardiogram (TTE) guidance and anti-Xa monitoring. Results: The patient was electively admitted at 35 weeks for pre-delivery optimization. Enoxaparin was switched to an unfractionated heparin infusion. Betamethasone was administered to facilitate fetal lung maturation. Twice-daily fetal non-stimulation tests were performed. LVAD speed was optimized with TTE guidance. Continuous hemodynamic monitoring was performed perioperatively with a Swan-Ganz catheter and arterial line. Femoral veno-arterial sheaths were placed in case extracorporeal membrane oxygenation was needed. Anesthesia was administered via spinal-epidural approach. LVAD speed was modulated as needed. A healthy neonate was delivered by cesarean section without complication at 36 weeks and 3 days. Conclusions: Pregnancy during LVAD support remains an extremely high-risk clinical situation, though this case demonstrates that it is possible to carry such a pregnancy to near-term.

Abstract 16737: Explantation of LVAD in Recovered Alcohol Induced Cardiomyopathy

Durable Left Ventricular Assist Device (LVAD) is an important modality for bridge or destination therapy for patients with end-stage heart failure. However, there is a paucity of evidence guiding management for LVAD explantation in patients with sufficient myocardial recovery as this only occurs in 1-3% of cases. We present a case of a patient with LVAD placement due to alcoholic cardiomyopathy with subsequent removal of his LVAD three years later. Description of Case: A 51-year-old male with a history of alcohol induced cardiomyopathy with an LV ejection fraction of 10% s/p Heartmate II LVAD implant 3 years ago was evaluated for LVAD explantation. Over the course of one year, LVAD speed was decreased and ejection fraction (EF), cardiac output (CO) and cardiac index (CI) were monitored. Prior to explantation, the patients EF was 50% with a CO of 5.6L/min and CI 2.7 L/min/m2. Following successful explantation, a repeat echocardiogram 3 months later revealed an EF of 45%. Right heart catheterization revealed CO of 5.3L/min and CI 2.6L/min/m2. Patient was discharged on guideline directed medical therapy with continued improvement. Discussion: Mechanical, histological, and biochemical myocardial improvement has been described in LVAD recipients. There is a paucity of data to guide recovery assessment and candidacy for explantation. The 2023 ISHLT guidelines have attempted to synthesize the available data and outline the major considerations. Assessment should be done at low LVAD speeds with incorporation of data from patient’s clinical status, echocardiography, right heart catheterization, and cardiopulmonary exercise testing. Utilization of LVAD as a bridge to recovery was feasible in our patient given careful assessment of recovered cardiac function as outlined by aforementioned criteria. LVAD explantation after heart recovery remains a rare phenomenon. As access to cardiac transplantation remains limited, consistent use of guideline directed medical therapy allows for the possibility of heart recovery along with explantation. We present a case of successful and maintained myocardial recovery after LVAD explantation. Cases such as this would benefit from standardization of LVAD explantation guidelines for optimal long-term survival for patients.

Abstract 17322: Closing the Loop: Use of Amplatzer PFO Occluder Device in Case of LVAD-Associated Aortic Insufficiency

Description of Case: A 72-year-old woman with destination therapy Heartmate 3 left ventricular assist device (LVAD) presented with NYHA Class III symptoms. Review of her echocardiograms since LVAD implantation revealed progressive central aortic insufficiency (AI) with subsequent LV dilatation, managed with reduction in LVAD speed. Patient declined surgical aortic valve replacement and/or repair. After a multidisciplinary discussion, the patient opted to pursue percutaneous aortic valve closure. Cardiac CT demonstrated no aortic valve thrombus and identified appropriate anatomy for closure with an 18x25 mm Amplatzer PFO Occluder device (Graphic 1). Preoperative TEE revealed LV ejection fraction of 15% with moderate to severe AI and fibrosis of the aortic valve commissures with no aortic valve movement. The aortic valve was closed with the Amplatzer PFO Occluder with an 18mm disk that sat on the LV side of the aortic valve within the AV annulus and the 25mm disk sitting on the aortic side of the aortic valve within the sinus of Valsalva. TEE and intracardiac echocardiography demonstrated excellent device placement with two residual trace AI jets at the non-left and left-right commissure. Following LVAD speed increase, the degree of AI remained unchanged and she was discharged with improved symptoms. Discussion: Moderate-severe AI develops in about 15-25% of patients within 1 year of LVAD implantation. There are previous reports of LVAD-associated AI closure with an Amplatzer cribiform device. We describe the first known use of the Amplatzer PFO Occluder device for the management of LVAD-associated AI. While transcatheter aortic valve replacement (TAVR) is an attractive option to treat LVAD-associated AI, securing the transcatheter heart valve in the absence of calcifications remains a challenge.

Pumping for Two: Pregnancy in Patients Supported With a Left Ventricular Assist Device.

This review discusses the challenges and outcomes associated with pregnancy during left ventricular assist device (LVAD) support. Women account for a third of the heart failure population in the United States. Left ventricular assist devices have emerged as a safe and effective treatment option for patients with advanced heart failure. Pregnancy during LVAD support can occur, and it presents significant risks to both mother and fetus, including hemodynamic stress, thrombotic events, medication-associated teratogenicity, and uterine impingement. This literature review identified 10 cases of confirmed pregnancy during LVAD support, of which eight resulted in successful births. Maternal and fetal mortality occurred in one case, and there was a spontaneous abortion in one case. The review highlights the importance of a multidisciplinary approach, promotion of shared decision-making, thoughtful anticoagulation, adjustment of LVAD speed, and medication optimization to maintain hemodynamic support during pregnancy. Hemodynamic changes during pregnancy include increased cardiac output, heart rate, and plasma volume, as well as decreased systemic vascular resistance, which can impact LVAD support. Despite reduced pulsatility in LVAD-supported patients, ovulation and reproductive capacity might be preserved, and viable pregnancies may be achieved with appropriate management. The review provides insights into the risks and considerations for a viable pregnancy during LVAD support, including the need for ongoing research to inform joined decision-making.

Determinants of exercise performance in heart failure patients with extremely reduced cardiac output and left ventricular assist device.

The evaluation of exercise capacity and cardiac output (QC) is fundamental in the management of patients with advanced heart failure (AdHF). QC and peak oxygen uptake (VO2) have a pivotal role in the prognostic stratification and in the definition of therapeutic interventions, including medical therapies and devices, but also specific treatments such as heart transplantation and left ventricular assist device (LVAD) implantation. Due to the intertwined relationship between exercise capacity and daily activities, exercise intolerance dramatically has impact on the quality of life of patients. It is a multifactorial process that includes alterations in central and peripheral haemodynamic regulation, anaemia and iron deficiency, pulmonary congestion, pulmonary hypertension, and peripheral O2 extraction. This paper aims to review the pathophysiological background of exercise limitations in HF patients and to examine the complex physiology of exercise in LVAD recipients, analysing the interactions between the cardiopulmonary system, the musculoskeletal system, the autonomic nervous system, and the pump. We performed a literature review to highlight the current knowledge on this topic and possible interventions that can be implemented to increase exercise capacity in AdHF patients-including administration of levosimendan, rehabilitation, and the intriguing field of LVAD speed changes. The present paper confirms the role of CPET in the follow-up of this peculiar population and the impact of exercise capacity on the quality of life of AdHF patients.

HeartMate 3 Snoopy: Noninvasive cardiovascular diagnosis of patients with fully magnetically levitated blood pumps during echocardiographic speed ramp tests and Valsalva maneuvers

The HeartMate 3 (HM3) left ventricular assist device (LVAD) has demonstrated excellent clinical outcomes; however, pump speed optimization is challenging with the available HM3 monitoring. Therefore, this study reports on clinical HM3 parameters collected with a noninvasive HM3 monitoring system (HM3 Snoopy) during echocardiographic speed ramp tests and Valsalva maneuvers. In this prospective, single-center study, the HM3 data communication between the controller and pump was recorded with a novel data acquisition system. Twelve pump parameters sampled every second (1Hz) and clinical assessments (echocardiography, electrocardiogram (ECG), and blood pressure measurement) during speed ramp tests were analyzed using Pearson's correlation (r, median [IQR]). The cause for the occurrence of pulsatility index (PI)-events during ramp speed tests and valsalva maneuvers was investigated. In 24 patients (age: 58.9±8.8years, body mass index: 28.1±5.1kg/m2, female: 20.8%), 35 speed ramp tests were performed with speed changes in the range of ±1000rpm from a baseline speed of 5443±244rpm. Eight HM3 pump parameters from estimated flow, motor current, and LVAD speed together with blood pressure showed positive collinearities (r=0.9 [0.1]). Negative collinearities were observed for pump flow pulsatility, pulsatility index, rotor noise, and left ventricular diameters (r=-0.8 [0.1]), whereas rotor displacement and heartrate showed absence of collinearities (r=-0.1 [0.08]). In this study, the HM3 Snoopy was successfully used to acquire more parameters from the HM3 at a higher sampling rate. Analysis of HM3 per-second data provide additional clinical diagnostic information on heart-pump interactions and cause of PI-events.

Benchtop Models of Patient-Specific Intraventricular Flow During Heart Failure and LVAD Support.

The characterization of intraventricular flow is critical to evaluate the efficiency of fluid transport and potential thromboembolic risk but challenging to measure directly in advanced heart failure (HF) patients with left ventricular assist device (LVAD) support. The study aims to validate an in-house mock loop (ML) by simulating specific conditions of HF patients with normal and prosthetic mitral valves (MV) and LVAD patients with small and dilated left ventricle volumes, then comparing the flow-related indices result of vortex parameters, residence time (RT), and shear-activation potential (SAP). Patient-specific inputs for the ML studies included heart rate, end-diastolic and end-systolic volumes, ejection fraction, aortic pressure, E/A ratio, and LVAD speed. The ML effectively replicated vortex development and circulation patterns, as well as RT, particularly for HF patient cases. The LVAD velocity fields reflected altered flow paths, in which all or most incoming blood formed a dominant stream directing flow straight from the mitral valve to the apex. RT estimation of patient and ML compared well for all conditions, but SAP was substantially higher in the LVAD cases of the ML. The benchtop system generated comparable and reproducible hemodynamics and fluid dynamics for patient-specific conditions, validating its reliability and clinical relevance. This study demonstrated that ML is a suitable platform to investigate the fluid dynamics of HF and LVAD patients and can be utilized to investigate heart-implant interactions.

The Hemodynamic Effects of Aortic Regurgitation in Patients Supported by a HeartMate 3 Left Ventricular Assist Device

Aortic regurgitation (AR) is a common complication following left ventricular assist device (LVAD) implantation. We evaluated the hemodynamic implications of AR in patients with HeartMate 3 (HM3) LVAD at baseline and in response to speed changes. Clinically stable outpatients supported by HM3 who underwent a routine hemodynamic ramp test were retrospectively enrolled in this analysis. Patients were stratified based on the presence of at least mild AR at baseline speed. Hemodynamic and echocardiographic parameters were compared between the AR and non-AR groups. Sixty-two patients were identified. At the baseline LVAD speed, 29 patients (47%) had AR, while 33 patients (53%) did not. Patients with AR were older and supported on HM3 for a longer duration. At baseline speed, all hemodynamic parameters were similar between the groups including central venous pressure, pulmonary capillary wedge pressure, pulmonary arterial pressures, cardiac output and index, and pulmonary artery pulsatility index (p > 0.05 for all). During the subacute assessment, AR worsened in some, but not all, patients, with increases in LVAD speed. There were no significant differences in 1-year mortality or hospitalization rates between the groups, however, at 1-year, ≥ moderate AR and right ventricular failure (RVF) were detected in higher rates among the AR group compared to the non-AR group (45% vs. 0%; p < 0.01, and 75% vs. 36.8%; p = 0.02, respectively). In a cohort of stable outpatients supported with HM3 who underwent a routine hemodynamic ramp test, the presence of mild or greater AR did not impact the ability of HM3 LVADs to effectively unload the left ventricle during early subacute assessment. Although the presence of AR did not affect mortality and hospitalization rates, it resulted in higher rates of late hemodynamic-related events in the form of progressive AR and RVF.

Estimation of Left Ventricular Stroke Work for Rotary Left Ventricular Assist Devices.

Continuous monitoring of left ventricular stroke work (LVSW) may improve the medical management of patients with rotary left ventricular assist devices (LVAD). However, implantable pressure-volume sensors are limited by measurement drift and hemocompatibility. Instead, estimator algorithms derived from rotary LVAD signals may be a suitable alternative. An LVSW estimator algorithm was developed and evaluated in a range of in vitro and ex vivo cardiovascular conditions during full assist (closed aortic valve [AoV]) and partial assist (opening AoV) mode. For full assist, the LVSW estimator algorithm was based on LVAD flow, speed, and pump pressure head, whereas for partial assist, the LVSW estimator combined the full assist algorithm with an estimate of AoV flow. During full assist, the LVSW estimator demonstrated a good fit in vitro and ex vivo (R 2 : 0.97 and 0.86, respectively) with errors of ± 0.07 J. However, LVSW estimator performance was reduced during partial assist, with in vitro : R 2 : 0.88 and an error of ± 0.16 J and ex vivo : R 2 : 0.48 with errors of ± 0.11 J. Further investigations are required to improve the LVSW estimate with partial assist; however, this study demonstrated promising results for a continuous estimate of LVSW for rotary LVADs.

Self-care behaviours of patients with left ventricular assist devices in Israel: changes during the COVID-19 pandemic.

Left ventricular assist devices (LVADs) support the hearts of patients with advanced heart failure. Following LVAD implantation, patients face a complex regimen of self-care behaviours including self-care maintenance, self-care monitoring and self-care management. However, during the COVID-19 pandemic, symptoms of anxiety and depression may have interfered with their self-care. Currently, little is known on how specific self-care behaviours of LVAD-implanted patients changed during the COVID-19 pandemic. We aim to describe the changes in self-care behaviours among patients with an implanted LVAD in Israel during the COVID-19 pandemic and explore the factors related to self-care behaviour change. A prospective observational cross-sectional study design. A convenience sample of 27 Israeli LVAD-implanted patients (mean age 62.4±9, 86% male, 78.6% living with a partner) completed the LVAD Self-Care Behaviour Scale (1=never to 5=always) and Hospital Anxiety and Depression Scale (0=not at all to 3=most of the time). Data were collected before and after the onset of the COVID-19 pandemic in Israel. Statistical analyses included paired t-tests, Pearson's correlations, and one-way repeated measures ANOVAs. During the COVID-19 pandemic, a significant decrease was found in patients' adherence to checking and recording their LVAD speed, flow, power and PI (Pulsatility Index) (P=0.05), checking their INR (P=0.01), and daily weighing (P<0.01). The prevalence of some behaviours (e.g. regularly exercising) increased in some patients and decreased in others. Patients living without a partner worsened their adherence to some of the self-care behaviours (e.g. taking medicines as prescribed), compared with those living with a partner (Mb =5.0±0 and Md =5.0±0, delta=0 vs. Mb =5.0±0 and Md =4.6±0.9, delta=-0.4, respectively; F=4.9, P=0.04). Women, and not men, tended to improve their adherence to the self-care behaviour such as avoiding kinking, pulling, or moving the LVAD driveline at the exit site (Mb =4.0±1.0 and Md =5.0±0, delta=1.0 vs. Mb =4.5±0.9 and Md =4.4±1.2, delta=-0.1, F=4.7, P=0.04, respectively). In total, 41% (11) patients reported neither anxiety nor depression, 11% (3) reported anxiety, 15% (4) reported depression, and 44% (12) reported both anxiety and depression. No associations between anxiety and/or depression and self-care behaviours were found. Priorities in self-care behaviours among patients with implanted LVAD changed after the onset of the COVID-19 pandemic. Factors that assisted with adherence to self-care behaviours included living with a partner and being female. The current results may guide further research on identifying behaviours that are at risk of not being maintained during a time of emergency.

Outflow cannula alignment in continuous flow left ventricular devices is associated with stroke.

We sought to evaluate whether differences in left ventricular assist device (LVAD) canula alignment are associated with stroke. There is a paucity of clinical data on contribution of LVAD canulae alignment to strokes. We conducted a retrospective analysis of patients who underwent LVAD implantation at Houston Methodist hospital from 2011 to 2016 and included those who had undergone cardiac computed tomography (CT) with contrast. LVAD graft alignment using X-ray, echocardiography, and cardiac CT was evaluated. The primary outcome was stroke within 1 year of LVAD implantation. Of the 101 patients that underwent LVAD Implantation and cardiac CT scan during the study period, 78 met inclusion criteria. The primary outcome occurred in 12 (15.4%) patients with a median time to stroke of 77 days (interquartile range: 42-132 days). Of these, 10 patients had an ischemic and two had hemorrhagic strokes. The predominant device type was Heart Mate II (94.8%). Patients with LVAD outflow cannula to aortic angle lesser than 37.5° and those with outflow graft diameter of anastomosis less than 1.5 cm (assessed by cardiac CT) had significantly higher stroke risk (p < 0.001 and p = 0.01 respectively). In HMII patients, a lower LVAD speed at the time of CT scan was associated with stroke. Further studies are needed to identify optimal outflow graft configuration to mitigate stroke risk.

In Vitro Investigation of the Effect of the Timing of Left Ventricular Assist Device Speed Modulation on Intraventricular Flow Patterns.

Thromboembolic events remain a common complication for left ventricular assist device (LVAD) patients. To prevent in-pump thrombosis, third-generation LVADs use speed modulation, which is not synchronized with the native left ventricle (LV) contractility. This study aims to investigate the effect of speed modulation on intraventricular flow patterns, and specifically, the impact of timing relative to pressure variations in the LV. Stereo-particle image velocimetry measurements were performed in a patient-derived LV implanted with an LVAD, for different timings of the speed modulation and speed. Speed modulation has a strong effect on instantaneous afterload and flowrate (-16% and +20%). The different timings of the speed modulation resulted in different flowrate waveforms, exhibiting different maxima (5.3-5.9 L/min, at constant average flowrate). Moreover, the timing of the speed modulation was found to strongly influence intraventricular flow patterns, specifically, stagnation areas within the LV. These experiments highlight, once more, the complex relationship between LVAD speed, hemodynamic resistance, and intraventricular pressure. Overall, this study demonstrates the importance of considering native LV contractility in future LVAD controls, to improve hemocompatibility and reduce the risk of thromboembolic complications.

Patient-specific, echocardiography compatible flow loop model of aortic valve regurgitation in the setting of a mechanical assist device.

Aortic regurgitation (AR) occurs commonly in patients with continuous-flow left ventricular assist devices (LVAD). No gold standard is available to assess AR severity in this setting. Aim of this study was to create a patient-specific model of AR-LVAD with tailored AR flow assessed by Doppler echocardiography. An echo-compatible flow loop incorporating a 3D printed left heart of a Heart Mate II (HMII) recipient with known significant AR was created. Forward flow and LVAD flow at different LVAD speed were directly measured and AR regurgitant volume (RegVol) obtained by subtraction. Doppler parameters of AR were simultaneously measured at each LVAD speed. We reproduced hemodynamics in a LVAD recipient with AR. AR in the model replicated accurately the AR in the index patient by comparable Color Doppler assessment. Forward flow increased from 4.09 to 5.61 L/min with LVAD speed increasing from 8,800 to 11,000 RPM while RegVol increased by 0.5 L/min (2.01 to 2.5 L/min). Our circulatory flow loop was able to accurately replicate AR severity and flow hemodynamics in an LVAD recipient. This model can be reliably used to study echo parameters and aid clinical management of patients with LVAD.

Initial clinical validation of a hybrid in silico-in vitro cardiorespiratory simulator for comprehensive testing of mechanical circulatory support systems.

Simulators are expected to assume a prominent role in the process of design—development and testing of cardiovascular medical devices. For this purpose, simulators should capture the complexity of human cardiorespiratory physiology in a realistic way. High fidelity simulations of pathophysiology do not only allow to test the medical device itself, but also to advance practically relevant monitoring and control features while the device acts under realistic conditions. We propose a physiologically controlled cardiorespiratory simulator developed in a mixed in silico-in vitro simulation environment. As inherent to this approach, most of the physiological model complexity is implemented in silico while the in vitro system acts as an interface to connect a medical device. As case scenarios, severe heart failure was modeled, at rest and at exercise and as medical device a left ventricular assist device (LVAD) was connected to the simulator. As initial validation, the simulator output was compared against clinical data from chronic heart failure patients supported by an LVAD, that underwent different levels of exercise tests with concomitant increase in LVAD speed. Simulations were conducted reproducing the same protocol as applied in patients, in terms of exercise intensity and related LVAD speed titration. Results show that the simulator allows to capture the principal parameters of the main adaptative cardiovascular and respiratory processes within the human body occurring from rest to exercise. The simulated functional interaction with the LVAD is comparable to the one clinically observed concerning ventricular unloading, cardiac output, and pump flow. Overall, the proposed simulation system offers a high fidelity in silico-in vitro representation of the human cardiorespiratory pathophysiology. It can be used as a test bench to comprehensively analyze the performance of physically connected medical devices simulating clinically realistic, critical scenarios, thus aiding in the future the development of physiologically responding, patient-adjustable medical devices. Further validation studies will be conducted to assess the performance of the simulator in other pathophysiological conditions.

Hemodynamic Aberrancies in Left Ventricular Assist Device–Associated Heart Failure Syndromes

Hemodynamic Aberrancies in Left Ventricular Assist Device–Associated Heart Failure Syndromes