| 1. |
- Pirozzi, I., et al.
(författare)
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Electrohydraulic Vascular Compression Device (e-VaC) with Integrated Sensing and Controls
- 2023
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Ingår i: Advanced Materials Technologies. - : Wiley. - 2365-709X. ; 8:4, s. 2201196-
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Tidskriftsartikel (refereegranskat)abstract
- Right ventricular (RV) failure remains a significant clinical burden particularly during the perioperative period surrounding major cardiac surgeries, such as implantation of left ventricular assist devices (LVADs), bypass procedures or valvular surgeries. Device solutions designed to support the function of the RV do not keep up with the pace of development of left-sided solutions, leaving the RV vulnerable to acute failure in the challenging hemodynamic environments of the perioperative setting. This work describes the design of a biomimetic, soft, conformable sleeve that can be prophylactically implanted on the pulmonary artery to support RV ventricular function during major cardiac surgeries, through afterload reduction and augmentation of flow. Leveraging electrohydraulic principles, a technology is proposed that is non-blood contacting and obviates the necessity for drivelines by virtue of being electrically powered. In addition, the integration of an adjacent is demonstrate, continuous pressure sensing module to support physiologically adaptive control schemes based on a real-time biological signal. In vitro experiments conducted in a pulsatile flow-loop replicating physiological flow and pressure conditions show a reduction of mean pulmonary arterial pressure of 8 mmHg (25% reduction), a reduction in peak systolic arterial pressure of up to 10 mmHg (20% reduction), and a concomitant 19% increase in diastolic pulmonary flow. Computational simulations further predict substantial augmentation of cardiac output as a result of reduced RV ventricular stress and RV dilatation.
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| 2. |
- Dual, Seraina A., 1991-, et al.
(författare)
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Elucidating tricuspid Doppler signal interpolation and its implication for assessing pulmonary hypertension
- 2022
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Ingår i: Pulmonary Circulation. - : Wiley. - 2045-8932 .- 2045-8940. ; 12:3, s. e12125-
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Tidskriftsartikel (refereegranskat)abstract
- Doppler echocardiography plays a central role in the assessment of pulmonary hypertension (PAH). We aim to improve quality assessment of systolic pulmonary arterial pressure (SPAP) by applying a cubic polynomial interpolation to digitized tricuspid regurgitation (TR) waveforms. Patients with PAH and advanced lung disease were divided into three cohorts: a derivation cohort (n = 44), a validation cohort (n = 71), an outlier cohort (n = 26), and a non-PAH cohort (n = 44). We digitized TR waveforms and analyzed normalized duration, skewness, kurtosis, and first and second derivatives of pressure. Cubic polynomial interpolation was applied to three physiology-driven phases: the isovolumic phase, ejection phase, and “shoulder” point phase. Coefficients of determination and a Bland−Altman analysis was used to assess bias between methods. The cubic polynomial interpolation of the TR waveform correlated strongly with expert read right ventricular systolic pressure (RVSP) with R2 > 0.910 in the validation cohort. The biases when compared to invasive SPAP measured within 24 h were 6.03 [4.33; 7.73], −2.94 [1.47; 4.41], and −3.11 [−4.52; −1.71] mmHg, for isovolumic, ejection, and shoulder point interpolations, respectively. In the outlier cohort with more than 30% difference between echocardiographic estimates and invasive SPAP, cubic polynomial interpolation significantly reduced underestimation of RVSP. Cubic polynomial interpolation of the TR waveform based on isovolumic or early ejection phase may improve RVSP estimates.
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| 3. |
- Boudreau, Mathieu, et al.
(författare)
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Repeat it without me: Crowdsourcing the T1 mapping common ground via the ISMRM reproducibility challenge
- 2024
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Ingår i: MAGNETIC RESONANCE IN MEDICINE. - 0740-3194 .- 1522-2594. ; 92:3, s. 1115-1127
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Tidskriftsartikel (refereegranskat)abstract
- Purpose T-1 mapping is a widely used quantitative MRI technique, but its tissue-specific values remain inconsistent across protocols, sites, and vendors. The ISMRM Reproducible Research and Quantitative MR study groups jointly launched a challenge to assess the reproducibility of a well-established inversion-recovery T-1 mapping technique, using acquisition details from a seminal T-1 mapping paper on a standardized phantom and in human brains. Methods The challenge used the acquisition protocol from Barral et al. (2010). Researchers collected T-1 mapping data on the ISMRM/NIST phantom and/or in human brains. Data submission, pipeline development, and analysis were conducted using open-source platforms. Intersubmission and intrasubmission comparisons were performed. Results Eighteen submissions (39 phantom and 56 human datasets) on scanners by three MRI vendors were collected at 3 T (except one, at 0.35 T). The mean coefficient of variation was 6.1% for intersubmission phantom measurements, and 2.9% for intrasubmission measurements. For humans, the intersubmission/intrasubmission coefficient of variation was 5.9/3.2% in the genu and 16/6.9% in the cortex. An interactive dashboard for data visualization was also eveloped: https://rrsg2020.dashboards.neurolibre.org. Conclusion The T-1 intersubmission variability was twice as high as the intrasubmission variability in both phantoms and human brains, indicating that the acquisition details in the original paper were insufficient to reproduce a quantitative MRI protocol. This study reports the inherent uncertainty in T-1 measures across independent research groups, bringing us one step closer to a practical clinical baseline of T-1 variations in vivo.
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| 4. |
- Dual, Seraina A., et al.
(författare)
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The Future of Durable Mechanical Circulatory Support : Emerging Technological Innovations and Considerations to Enable Evolution of the Field
- 2024
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Ingår i: Journal of Cardiac Failure. - : Elsevier BV. - 1071-9164 .- 1532-8414. ; 30:4, s. 596-609
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Forskningsöversikt (refereegranskat)abstract
- The field of durable mechanical circulatory support (MCS) has undergone an incredible evolution over the past few decades, resulting in significant improvements in longevity and quality of life for patients with advanced heart failure. Despite these successes, substantial opportunities for further improvements remain, including in pump design and ancillary technology, perioperative and postoperative management, and the overall patient experience. Ideally, durable MCS devices would be fully implantable, automatically controlled, and minimize the need for anticoagulation. Reliable and long-term total artificial hearts for biventricular support would be available; and surgical, perioperative, and postoperative management would be informed by the individual patient phenotype along with computational simulations. In this review, we summarize emerging technological innovations in these areas, focusing primarily on innovations in late preclinical or early clinical phases of study. We highlight important considerations that the MCS community of clinicians, engineers, industry partners, and venture capital investors should consider to sustain the evolution of the field.
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| 5. |
- Kight, Ali, et al.
(författare)
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Decoupling Transmission and Transduction for Improved Durability of Highly Stretchable, Soft Strain Sensing : Applications in Human Health Monitoring
- 2023
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Ingår i: Sensors. - : MDPI AG. - 1424-8220. ; 23:4
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Tidskriftsartikel (refereegranskat)abstract
- This work presents a modular approach to the development of strain sensors for large deformations. The proposed method separates the extension and signal transduction mechanisms using a soft, elastomeric transmission and a high-sensitivity microelectromechanical system (MEMS) transducer. By separating the transmission and transduction, they can be optimized independently for application-specific mechanical and electrical performance. This work investigates the potential of this approach for human health monitoring as an implantable cardiac strain sensor for measuring global longitudinal strain (GLS). The durability of the sensor was evaluated by conducting cyclic loading tests over one million cycles, and the results showed negligible drift. To account for hysteresis and frequency-dependent effects, a lumped-parameter model was developed to represent the viscoelastic behavior of the sensor. Multiple model orders were considered and compared using validation and test data sets that mimic physiologically relevant dynamics. Results support the choice of a second-order model, which reduces error by 73% compared to a linear calibration. In addition, we evaluated the suitability of this sensor for the proposed application by demonstrating its ability to operate on compliant, curved surfaces. The effects of friction and boundary conditions are also empirically assessed and discussed.
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| 6. |
- Korn, Leonie, et al.
(författare)
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Dual-Modality Volume Measurement Integrated on a Ventricular Assist Device
- 2022
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Ingår i: IEEE Transactions on Biomedical Engineering. - : Institute of Electrical and Electronics Engineers (IEEE). - 0018-9294 .- 1558-2531. ; 69:3, s. 1151-1161
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Tidskriftsartikel (refereegranskat)abstract
- Objective: Ventricular assist devices (VADs)are implanted in patients suffering from end-stage heartfailure to sustain the blood circulation. Real-time volumemeasurement could be a valuable tool to monitor patientsand enable physiological control strategies to provide in-dividualized therapy. However, volume measurement usingone sensor modality requires re-calibration in the criticaltime post VAD implantation. Methods: To overcome thislimitation, we have integrated ultrasound and impedancevolume measurement techniques into a cannula of an api-cal VAD. We tested both modalities across a volume rangefrom 140–420 mL using two differently sized and shapedbiventricular silicon heart phantoms, which were subjectedto physiological pressures in an in-vitro test bench. Wecompared results from standard calibrated measurementswith calculations found by a quadratic optimization for thesingle modality and their combination (dual-modality) andvalidated the results using twofold cross-validation. Re-sults: The dual-modality approach resulted in most favor-able limits of agreement (LOA) of −0.83 ± 1.54% comparedto −13.88 ± 5.90% for ultrasound and −43.45 ± 10.28% forelectric impedance, separately. Conclusion: The results ofthe dual-modality approach were as accurate as the stan-dard calibrated measurement and valid over a large rangeof volumes (140–420 mL). In this in-vitro study, we showhow a dual-modality ventricular volume measurement of ul-trasound and electric impedance increases the robustnessand renders calibration obsolete. Significance: Ventricularvolumes could be measured accurately in the critical periodpost VAD implantation despite ventricular remodeling.
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| 7. |
- Nair, Priya J., et al.
(författare)
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Hemodynamics in Patients with Aortic Coarctation : A Comparison of in vivo 4D-Flow MRI and FSI Simulation
- 2023
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Ingår i: Functional Imaging and Modeling of the Heart. - : Springer Nature. ; , s. 515-523
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Konferensbidrag (refereegranskat)abstract
- The analysis of quantitative hemodynamics provides information for the diagnosis and treatment planning in patients with aortic coarctation (CoA). Patient-specific computational fluid dynamics (CFD) simulations reveal detailed hemodynamic information, but their agreement with the clinical standard 4D-Flow magnetic resonance imaging (MRI) needs to be characterized. This work directly compares in vivo CFD fluid-structure interaction (FSI) simulations against 4D-Flow MRI in patients with CoA (N = 5). 4D-Flow MRI-derived flow waveforms and cuff blood pressure measurements were used to tune the boundary conditions for the FSI simulations. Flow rates from 4D-Flow MRI and FSI were compared at cross-sections in the ascending aorta (AAo), CoA and descending aorta (DAo). Qualitative comparisons showed an overall agreement of flow patterns in the aorta between the two methods. The R 2 values for the flow waveforms in the AAo, CoA, and DAo were 0.97, 0.84 and 0.81 respectively, representing a strong correlation between 4D-Flow MRI measurements and FSI results. This work characterizes the use of patient-specific FSI simulations in quantifying and analyzing CoA hemodynamics to inform CoA treatment planning.
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| 8. |
- Perra, Emanuele, et al.
(författare)
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Showcasing Capabilities of a Hybrid Mock Circulation Loop for Investigation of Aortic Coarctation
- 2023
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Ingår i: Functional Imaging and Modeling of the Heart. - : Springer Nature. ; , s. 505-514
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Konferensbidrag (refereegranskat)abstract
- Congenital heart diseases are the most frequently diagnosed birth defect of the cardiovascular system (CVS), occurring in 1% of live births globally. Mock circulatory loops (MCLs) replicate the physiological boundary conditions of the CVS, which allow for testing of cardiac assist devices (CADs), but also provide valuable in vitro data for optimizing imaging protocols as well as validating computational fluid dynamics simulations. However, innate limitations of traditional MCLs include the difficulty in tuning physical boundary conditions to match the dynamic patient’s physiology. To address these limitations, hybrid mock circulatory loops (HMCLs) incorporate elements of both in vitro and in silico modelling allowing for rapid changes in boundary conditions to be mimicked in closed-loop. In this study, a real-time HMCL testing platform was built, and its use exemplified in the study of aortic coarctation (AoC), a common congenital cardiovascular disorder caused by a narrowing of the descending aorta. Compliant 3D-printed stenosed tubes of varying severity were integrated into the HMCL to represent the AoC model. First their mechanical impedance was quantified using a chirp pressure signal. Second, the effect of the severity of coarctation on the simulated CVS variables (pressure difference, cardiac output) was assessed in dynamic interaction with the closed-loop CVS. This study lays the foundation for future studies into dynamic cardiovascular conditions, imaging improvements, and validation of fluid dynamics modelling.
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| 9. |
- Pirozzi, Ileana, et al.
(författare)
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Circulatory Support : Artificial Muscles for the Future of Cardiovascular Assist Devices
- 2023
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Ingår i: Advanced Materials. - : Wiley. - 0935-9648 .- 1521-4095.
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Tidskriftsartikel (refereegranskat)abstract
- Artificial muscles enable the design of soft implantable devices which are poised to transform the way we mechanically support the heart today. Heart failure is a prevalent and deadly disease, which is treated with the implantation of rotary blood pumps as the only alternative to heart transplantation. The clinically used mechanical devices are associated with severe adverse events, which are reflected here in a comprehensive list of critical requirements for soft active devices of the future: low power, no blood contact, pulsatile support, physiological responsiveness, high cycle life, and less-invasive implantation. In this review, we investigate and critically evaluate prior art in artificial muscles for their applicability in the short and long term. We highlight the main challenges regarding the effectiveness, controllability, and implantability of recently proposed actuators and explore future perspectives for attachment, physiological responsiveness, durability, and biodegradability as well as equitable design considerations.
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| 10. |
- Pirozzi, Ileana, et al.
(författare)
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RVEX : Right Ventricular External Device for Biomimetic Support and Monitoring of the Right Heart
- 2022
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Ingår i: Advanced Materials Technologies. - : Wiley. - 2365-709X. ; 7:8, s. 2101472-2101472
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Tidskriftsartikel (refereegranskat)abstract
- Right ventricular (RV) failure remains a significant burden for patients with advanced heart failure, especially after major cardiac surgeries such as implantation of left ventricular assist devices. Device solutions that can assist the complex biological function of heart muscle without the disadvantages of bulky designs and infection-prone drivelines remain an area of pressing clinical need, especially for the right ventricle. In addition, devices that incur contact between blood and artificial surfaces mandate long-term use of blood-thinning medications, carrying increased risks for the patients. This work describes the design of a biomimetic, elastic sleeve to support RV-specific motion via tuned regional mechanical properties. The RV external device (RVEX) in computational models as well as benchtop models and ex vivo (i.e., explanted heart) setups are evaluated to characterize the device and predict functional benefit. Additionally, long-term implantation potential is demonstrated in mice. Finally, the ability to sensorize the RVEX device to yield resistive self-sensing capabilities to continuously monitor ventricular deformation, as demonstrated in benchtop experiments and in live animal surgeries, is proposed.
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