Optimization of photon counting CT for cardiac imaging in patients with left ventricular assist devices: An in-depth assessment of metal artifacts.

PURPOSE: Photon counting CT (PCCT) holds promise for mitigating metal artifacts and can produce virtual mono-energetic images (VMI), while maintaining temporal resolution, making it a valuable tool for characterizing the heart. This study aimed to evaluate and optimize PCCT for cardiac imaging in patients during left ventricular assistance device (LVAD) therapy by conducting an in-depth objective assessment of metal artifacts and visual grading. METHODS: Various scan and reconstruction settings were tested on a phantom and further evaluated on a patient acquisition to identify the optimal protocol settings. The phantom comprised an empty thoracic cavity, supplemented with heart and lungs from a cadaveric lamb. The heart was implanted with an LVAD (HeartMate 3) and iodine contrast. Scans were performed on a PCCT (NAEOTOM Alpha, Siemens Healthcare). Metal artifacts were assessed by three objective methods: Hounsfield units (HU)/SD measurements (DiffHU and SDARTIFACT), Fourier analysis (AmplitudeLowFreq), and depicted LVAD volume in the images (BloomVol). Radiologists graded metal artifacts and the diagnostic interpretability in the LVAD lumen, cardiac tissue, lung tissue, and spinal cord using a 5-point rating scale. Regression and correlation analysis were conducted to determine the assessment method most closely associated with acquisition and reconstruction parameters, as well as the objective method demonstrating the highest correlation with visual grading. RESULTS: Due to blooming artifacts, the LVAD volume fluctuated between 27.0 and 92.7 cm3. This variance was primarily influenced by kVp, kernel, keV, and iMAR (R2 = 0.989). Radiologists favored pacemaker iMAR, 3 mm slice thickness, and T3D keV and kernel Bv56f for minimal metal artifacts in cardiac tissue assessment, and 110 keV and Qr40f for lung tissue interpretation. The model adequacy for DiffHU SDARTIFACT, AmplitueLowFreq, and BloomVol was 0.28, 0.76, 0.29, and 0.99 respectively for phantom data, and 0.95, 0.98, 1.00, and 0.99 for in-vivo data. For in-vivo data, the correlation between visual grading (VGSUM) and DiffHU SDARTIFACT, AmplitueLowFreq, and BloomVol was -0.16, -0.01, -0.48, and -0.40 respectively. CONCLUSION: We found that optimal scan settings for LVAD imaging involved using 120 kVp and IQ level 80. Employing T3D with pacemaker iMAR, the sharpest allowed vascular kernel (Bv56f), and VMI at 110 keV with kernel Qr40 yields images suitable for cardiac imaging during LVAD-therapy. Volumetric measurements of the LVAD for determination of the extent of blooming artifacts was shown to be the best objective method to assess metal artifacts.

Assistance Device Based on SSVEP-BCI Online to Control a 6-DOF Robotic Arm.

This paper explores the potential benefits of integrating a brain-computer interface (BCI) utilizing the visual-evoked potential paradigm (SSVEP) with a six-degrees-of-freedom (6-DOF) robotic arm to enhance rehabilitation tools. The SSVEP-BCI employs electroencephalography (EEG) as a method of measuring neural responses inside the occipital lobe in reaction to pre-established visual stimulus frequencies. The BCI offline and online studies yielded accuracy rates of 75% and 83%, respectively, indicating the efficacy of the system in accurately detecting and capturing user intent. The robotic arm achieves planar motion by utilizing a total of five control frequencies. The results of this experiment exhibited a high level of precision and consistency, as indicated by the recorded values of ±0.85 and ±1.49 cm for accuracy and repeatability, respectively. Moreover, during the performance tests conducted with the task of constructing a square within each plane, the system demonstrated accuracy of 79% and 83%. The use of SSVEP-BCI and a robotic arm together shows promise and sets a solid foundation for the development of assistive technologies that aim to improve the health of people with amyotrophic lateral sclerosis, spina bifida, and other related diseases.

Incremental Value of Global Longitudinal Strain to Michigan Risk Score and Pulmonary Artery Pulsatility Index in Predicting Right Ventricular Failure Following Left Ventricular Assist Devices.

BACKGROUND: The incremental utility of right ventricular (RV) strain on predicting right ventricular failure (RVF) following left ventricular assist device (LVAD) implantation, beyond clinical and haemodynamic indices, is not clear. METHODS: Two hundred and forty-six (246) patients undergoing LVAD implantation, who had transthoracic echocardiograms pre and post LVAD, pulmonary artery pulsatility index (PAPI) measurements and Michigan risk score, were included. We analysed RV global longitudinal strain (GLS) using speckle tracking echocardiography. RVF following LVAD implantation was defined as the need for medical support for >14 days, or unplanned RV assist device insertion after LVAD implantation. RESULTS: Mean preoperative RV-GLS was -7.8±2.8%. Among all, 27% developed postoperative RVF. A classification and regression tree analysis identified preoperative Michigan risk score, PAPI and RV-GLS as important parameters in predicting postoperative RVF. Eighty per cent (80%) of patients with PAPI <2.1 developed postoperative RVF, while only 4% of patients with PAPI >6.8 developed RVF. For patients with a PAPI of 2.1-3.2, having baseline Michigan risk score >2 points conferred an 81% probability of subsequent RVF. For patients with a PAPI of 3.3-6.8, having baseline RV-GLS of -4.9% or better conferred an 86% probability of no subsequent RVF. The sensitivity and specificity of this algorithm for predicting postoperative RVF were 67% and 93%, respectively, with an area under the curve of 0.87. CONCLUSION: RV-GLS has an incremental role in predicting the development of RVF post-LVAD implantation, even after controlling for clinical and haemodynamic parameters.

First experience with the jump-starting robotic assistance device Cirq.

Since spinal navigation became applicable, including robotic assistance into standard navigational setups seems reasonable. A newly released modular robotic assistance for drill stabilization (Cirq, Brainlab) was used in a 74-year-old man undergoing dynamic stabilization of L3-4 via navigated transfascial pedicle screws. The authors demonstrate the second worldwide surgery with this device and the second case performed in their department. They provide insight in its applicability to estimate its further potential in spinal robotics. Although being just the first step of this universal platform, the authors already see clinical benefit by its ease of use and drill support. The video can be found here: https://youtu.be/oN2ZiHFRFkU .

Withdrawal of Left Ventricular Assist Device in Dementia: A Case Report.

Left ventricular assistance devices (LVADs) are one type of life support with the unique quality of allowing recipients to live outside the hospital. This case report explores the decision by a patient and their family to withdraw LVAD therapy in the setting of dementia and consultant team recommendations at odds with one another due to the patient's simultaneous alertness and lack of decisional capacity. It then discusses the guiding principles that led to the withdrawal of LVAD therapy and lessons drawn from the experience by the care team.

Deactivation of cardiac implantable electronic devices in palliative patients: When and how.

Cardiac implantable electronic devices have transformed medicine as they improve quality of life and prevent premature death. In palliative care settings, deactivation of these devices must be discussed, particularly at end-of-life. In terminally ill patients it is consensual to recommend implantable cardioverter defibrillator deactivation once shocks are frequent and painful. Concerning pacemakers, the decision to deactivate is controversial and it usually is not an option at patients' end-of-life, since in pacing-dependent patients, such low heart rates might induce symptoms of bradycardia, with no impact on survival. Regarding cardiac resynchronization therapy, deactivation is not recommended as it can worsen symptoms. Left ventricular assistance device deactivation at end-of-life is a well-accepted practice, since it has the benefit of ending the physical burden associated with the device. Advance care planning should be encouraged and patients should be informed that deactivation is possible.

Pressure sore incidence and treatment in left ventricular assist device (LVAD)-equipped patients: Insights from a prospective series.

INTRODUCTION: A left ventricular assistance device (LVAD) is indicated in patients with end-stage heart failure. Due to the non-physiologic blood flow, a LVAD may favor pressure sores with a devastating risk of infection. This work shows the prevalence and treatment of pressure sores in LVAD patients, to optimize their management. MATERIAL AND METHODS: We retrospectively investigated all LVAD implantations at the Lausanne University Hospital (CHUV) from 2015 to 2019. We detected patients who developed a pressure sore and evaluated the timeline, management, and outcomes. RESULTS: Forty-two patients benefited from LVAD, among whom 5 (12%) developed a stage III/IV pressure sore, within a mean time of 25 days. Due to their poor overall condition, 4/5 patients were treated surgically and 1/5 conservatively. Half of the patients treated with surgery had major complications requiring reoperation. After flap coverage, the mean time to healing for patients was 6 weeks. DISCUSSION: The rapid development of deep pressure sores seen in 12% of patients may be a manifestation of the maladaptive blood flow induced by LVADs, combined with their bedridden condition. Initial signs of pressure sores should be considered seriously, as they are rapidly evolving and needing an aggressive surgical treatment whenever possible (80%). Complication rate was similar compared to standard pressure sore flap treatment. All patients benefiting from flap surgery achieved effective coverage after a mean follow-up of 24 months. No patient developed a LVAD infection. CONCLUSION: Surgery must be considered early in this population to prevent potential device infection.

Tolerance of Sustained Ventricular Fibrillation During Left Ventricular Assist Device Support With IMPELLA CP®.

A 64-year-old man was admitted with subacute anterior ST-segment elevation myocardial infarction treated with implantation of four drug-eluting stents in proximal left anterior descending artery. Despite successful percutaneous coronary intervention, the patient developed a significant worsening of left ventricular ejection fraction because of late diagnosis. A percutaneous mechanical circulatory support device (Impella CP; Abiomed) was then required in order to preserve adequate systemic perfusion. Twelve hours later, the patient developed rapid ventricular tachycardia degenerated in ventricular fibrillation, without loss of consciousness. During the arrhythmia, lasting for 10 min, the patient was alert, with preserved mental status. After adequate sedation, a single unsynchronized 200 J DC shock converted the patient to sinus rhythm.

Effect of power-assistance on upper limb biomechanical and physiological variables during a 6-minute, manual wheelchair propulsion test: a randomised, cross-over study.

PURPOSE: Use of a power-assistance wheelchair could reduce the risk of musculoskeletal disorders (MSDs), however, a comprehensive biomechanical evaluation of these systems has not been carried out. This study aimed to evaluate and compare biomechanical UL propulsion variables, and physiological exercise-related variables during the use of a wheelchair with rear drive power assist device (RD-PAD) and a standard manual wheelchair (MW). MATERIALS AND METHODS: Twenty-two adults with spinal cord injury were recruited. RD-PAD (SmartDrive system) was fitted to their own MW. An instrumented wheel was used to measure handrim forces, and gas exchange and heart rate were monitored. Participants performed repeated out and back runs for 6 min on a straight outdoor course. RESULTS: Distance covered was significantly greater with the RD-PAD (538 ± 104 m versus 470 ± 124 m). Peak mechanical effort during the propulsion phase was significantly lower with the RD-PAD (p < 0.001). Heart rate, metabolic equivalent of task (MET), tidal volume, minute volume, oxygen consumption, and peak oxygen consumption were all significantly lower with the RD-PAD (p < 0.001). CONCLUSIONS: The results showed that use of RD-PAD increased the distance covered by MW users and reduced the energy costs of propulsion. The biomechanical results indirectly suggest that RD-PAD may reduce the risk of MSD.Implications for RehabilitationUsing the SmartDrive system as propulsion assistance increases the travel autonomy.The SmartDrive system reduces the biomechanical constraints propelling the wheelchair on a slope and low slope.SmartDrive the system reduces the physiological solicitation related to the propulsion of wheelchair.

The evolution of long-term pediatric ventricular assistance devices: a critical review.

Introduction: The gap between the number of heart failure patients and the number of potential heart donors has never been larger than today, especially among the pediatric population. The use of mechanical circulatory support is seen as a potential alternative for clinicians to treat more patients. This treatment has proven its efficiency on short-term use. However, in order to replace heart transplant, the techniques should be used over longer periods of time.Areas covered: This review aims at furnishing an engineering vision of the evolution of ventricular assistance devices used in pediatrics. A critical analysis of the clinical complications related to devices generation is made to give an overview of the design improvements made since their inception.Expert opinion: The long-term use of a foreign device in the body is not without consequences, especially among fragile pediatric patients. Moreover, the size of their body parts increases the technical difficulties of such procedure. The balance between the living cells of the body is disturbed by the devices, mostly by the shear stress generated. To provide a safe mechanical circulatory support for long-term use, the devices should be more hemocompatible, preserving blood cells, adapted to the patient's systemic grid and miniaturized for pediatric use.

Hemostatic Challenges in Pediatric Critical Care Medicine-Hemostatic Balance in VAD.

Ventricular assist devices (VAD) are used more in children. Safe and effective anticoagulation is required for successful management of children supported with ventricular assist devices. Developmental hemostasis, device hemocompatibility, plastic to body ratio, surgical variable techniques, lack of knowledge on pharmacokinetics of anticoagulants, and wide variability in anticoagulation protocols have all contributed to increased incidence of bleeding and thromboembolic complications. New collaborative learning networks, such as the ACTION network, provide opportunities to define best practices, optimize, and reduce anticoagulation related adverse events. ACTION was established Dec 2017. It consists of expert clinicians in heart failure, as well as researchers, parents, and patients, with goals to improve outcomes, share data, improve education and standard practice for children with heart failure (, n.d). Changes in pediatric VAD anticoagulation strategy from using mainly heparin to DTI such as bivalirudin have helped reduce bleeding and clotting complications.

Prediction of right ventricular failure after left ventricular assist device implantation in patients with heart failure: a meta-analysis comparing echocardiographic parameters.

OBJECTIVES: Between 10% and 40% of patients who receive a left ventricular assistance device (LVAD) suffer from right ventricular failure (RVF) shortly after the device is implanted. Patients with post-LVAD RVF tend to have poor outcomes. Only a few predictive factors concerning the right ventricle (RV) have been investigated. Our goal was to search for non-invasive variables that correlate with RV function, focusing on echocardiographic parameters of the RV. METHODS: We selected 3 parameters: tricuspid annular plane systolic excursion, right ventricular fractional area change and right ventricular global longitudinal strain. We searched the literature and pooled relevant studies in a meta-analysis. Finally, we performed a statistical analysis to confirm whether each parameter was a reliable predictor of RVF after LVAD implantation. RESULTS: We retained 19 articles involving a total of 1561 patients. We found a pooled standardized mean deviation of -0.13 cm for the tricuspid annular plane systolic excursion, with the lower and upper tails of -0.21 and -0.04 cm, respectively. Concerning the right ventricular fractional area change, the averaged standardized mean deviation was equal to -2.61%, with the lower and upper extremities of -4.12% and -1.09%, respectively. Finally, regarding the global longitudinal strain, the standardized mean deviation was equal to -2.06% with an uncertainty value between -3.23% and -0.88%. CONCLUSIONS: The tricuspid annular plane systolic excursion could be a reliable parameter in RVF prediction. The right ventricular fractional area change and global longitudinal strain are likely to be stronger predictors of RVF after LVAD implantation. Prospective studies should be carried out to confirm this observation.

Forecasting the Walking Assistance Rehabilitation Level of Stroke Patients Using Artificial Intelligence.

Cerebrovascular accidents (CVA) cause a range of impairments in coordination, such as a spectrum of walking impairments ranging from mild gait imbalance to complete loss of mobility. Patients with CVA need personalized approaches tailored to their degree of walking impairment for effective rehabilitation. This paper aims to evaluate the validity of using various machine learning (ML) and deep learning (DL) classification models (support vector machine, Decision Tree, Perceptron, Light Gradient Boosting Machine, AutoGluon, SuperTML, and TabNet) for automated classification of walking assistant devices for CVA patients. We reviewed a total of 383 CVA patients' (1623 observations) prescription data for eight different walking assistant devices from five hospitals. Among the classification models, the advanced tree-based classification models (LightGBM and tree models in AutoGluon) achieved classification results of over 90% accuracy, recall, precision, and F1-score. In particular, AutoGluon not only presented the highest predictive performance (almost 92% in accuracy, recall, precision, and F1-score, and 86.8% in balanced accuracy) but also demonstrated that the classification performances of the tree-based models were higher than that of the other models on its leaderboard. Therefore, we believe that tree-based classification models have potential as practical diagnosis tools for medical rehabilitation.

Nuclear Imaging in Infective Endocarditis.

Infective endocarditis (IE) is a life-threatening disease with stable prevalence despite prophylactic, diagnostic, and therapeutic advances. In parallel to the growing number of cardiac devices implanted, the number of patients developing IE on prosthetic valves and cardiac implanted electronic device (CIED) is increasing at a rapid pace. The diagnosis of IE is particularly challenging, and currently relies on the Duke-Li modified classification, which include clinical, microbiological, and imaging criteria. While echocardiography remains the first line imaging technique, especially in native valve endocarditis, the incremental value of two nuclear imaging techniques, 18F-fluorodeoxyglucose positron emission tomography with computed tomography (18F-FDG-PET/CT) and white blood cells single photon emission tomography with computed tomography (WBC-SPECT), has emerged for the management of prosthetic valve and CIED IE. In this review, we will summarize the procedures for image acquisition, discuss the role of 18F-FDG-PET/CT and WBC-SPECT imaging in different clinical situations of IE, and review the respective diagnostic performance of these nuclear imaging techniques and their integration into the diagnostic algorithm for patients with a suspicion of IE.

A performance study of a wearable balance assistance device consisting of scissored-pair control moment gyroscopes and a two-axis inclination sensor.

Excessive postural sway while standing can lead to falls and injuries. A designed wearable balance assistance device which consists of scissored-pair control moment gyroscopes and a two-axis inclination sensor is introduced to reduce fall risk from excessive sway among the elderly. The prototype has dimensions of H50cm × W44cm × D30cm and weighs 15.03 kg. This study aims to investigate the effects of generated torque of the prototype on human subjects and aims to determine if the two-axis inclination sensor can detect sway amplitude and sway direction during an occurrence of excessive sway. Two healthy male subjects participated in the study. According to the results, the detected body incline angle related to the acquired sway amplitude of COP trajectories with correlation factors of 0.92 and 0.88 for the two subjects. The detected sway angle related to the acquired sway direction of COP trajectories with the correlation factors of 0.99 and 0.98 for the two subjects. The maximum-allowable generated torque of the prototype with an assigned actuating angle varying within ±15.6° from the acquired sway direction of COP trajectories was able to drive the COP of 60-kilogram-weighted healthy subject maintaining balance at posterolateral limits of stability with an average body incline angle of 5.74° to pass his standing secure zone. The results indicate that the prototype has the potential of being a wearable balance assistance device which can reduce fall risk from excessive sway among the elderly; however, some improvements are still required in regards to shape, size, mass, generated torque, and strength.

An application of scissored-pair control moment gyroscopes in a design of wearable balance assistance device for the elderly.

Impaired balance control ability and degraded functional mobility increases the risk of falling in elderly people. The elderly show more postural sway when standing compared with young people. A sway fall occurs when the center of gravity moves outside the limit of stability. In order to reduce the fall risk from the excessive sway, this study presents the design of wearable balance assistance device for the elderly. Scissored-pair control moment gyroscopes were selected as a torque actuator. A two-axis inclination sensor was used to detect the inclined angle of the wearer's body. The direction of sway was calculated from the detected inclined angle. The designed device weighs 8.2 kg with a height of 32 cm × width of 40 cm × depth of 22 cm. A multi-segment model of a standing human was used to investigate the device's performance for balance recovery. According to the simulations, balance recovery in any direction was successfully accomplished with the appropriate initial angle. The relationship between the effective initial angle and detected inclined angle was subsequently established. The stability provided by activation of the device was able to limit the unstable user's sway boundary. The designed device shows promise for use as a balance assistance device for the elderly.

Post-infarct ventricular septal rupture: early Impella implantation to delay surgery and reduce surgical risk.

Ventricular septal rupture (VSR) is a complication of myocardial infarction. Surgery is the only treatment; however, mortality is high, especially if it is performed within 7 days from presentation. The improved outcome with delayed intervention could be related to evolution of the infarct, which allows a more effective surgical repair. However, it is also a representation of survival bias, as an early surgery is usually performed on individuals with hemodynamic instability. We present a case of VSR complicated by cardiogenic shock. An early hemodynamic stabilization was achieved with Impella implantation; the delay in surgery allowed a reduction in surgical risk.

Early reduction of pulmonary arterial hypertension in patients using a long-term mechanical ventricular assistance device: a cross-sectional study

ABSTRACT BACKGROUND: Severe pulmonary arterial hypertension (PAH) is a contraindication for heart transplantation (HT). It has been correlated with increased early and late mortality, mainly associated with right ventricular failure. Ventricular assistance devices (VADs) can promote reduction of intracardiac pressures and consequent reduction of PAH over the medium and long terms, thus enabling future candidature for HT. The diminution of early pulmonary pressure within this scenario remains unclear. OBJECTIVE: To evaluate the reduction of PAH and correlate data from right catheterization with the earliness of this reduction. DESIGN AND SETTING: Cross-sectional study in a general hospital in São Paulo, Brazil. METHODS: This was a retrospective analysis on the medical records of patients undergoing VAD implantation in a single hospital. Patients for whom VAD had been indicated as a bridge to candidature for HT due to their condition of constant PAH were selected. RESULTS: Four patients with VADs had constantly severe PAH. Their mean pulmonary artery systolic pressure (PASP) before VAD implantation was 66 mmHg. Over the 30-day period after the procedure, all the patients evolved with a drop in PASP to below 60 mmHg. Their new average was 36 mmHg, which was a drop of close to 50% from baseline values. The one-year survival of this sample was 100%. CONCLUSION: VAD implantation can reduce PAH levels. Early reduction occurred in all patients. Thus, use of VAD is an important bridge tool for enabling candidature for HT among patients with constantly severe PAH.