Samuel. C. K. Lee

Progressive gait impairments remain a major challenge for children with cerebral palsy (CP), often limiting independence and quality of life. Although neuromuscular electrical stimulation (NMES) has shown promise for improving gait, most NMES-assisted gait studies in children with CP have targeted only a single muscle. In this exploratory study, we characterized acute biomechanical responses of six children with CP to seven NMES protocols during treadmill walking. The protocols comprised multi-muscle stimulation, single-muscle stimulation, and an individualized physical therapist-derived (PT-derived) condition. Each protocol was compared with a no-stimulation baseline and typically developing (TD) reference data. The primary and secondary outcomes were the Gait Deviation Index (GDI) and Coefficient of Variation (CV), complemented by the targeted outcome measures, including lower-limb joint kinematics using phase-by-phase Dynamic Time Warping (DTW), maximum knee extension, and stride length. We found that the comparison between multi-muscle and single-muscle conditions did not identify a statistically significant difference in GDI. CV analyses showed smaller distances from TD reference values for multi-muscle conditions, although not significant. Stimulation conditions significantly affected maximum knee extension and DTW during loading response at the ankle and pre-swing at the hip; however, no individual condition differed significantly from no stimulation after false discovery rate correction. The PT-derived condition showed favorable directional changes in selected outcomes, but no consistent advantage over the other protocols. These preliminary observations characterize acute response patterns and generate hypotheses for future studies; they do not establish the comparative efficacy of multi-muscle, single-muscle, or individualized NMES protocols.

Progressive gait impairments remain a major challenge for children with cerebral palsy (CP), often limiting independence and quality of life. While neuromuscular electrical stimulation (NMES) shows promise for improving gait, prior studies in this population have largely targeted only a single muscle. To address this gap, we examined multi-muscle versus single-muscle NMES during treadmill walking in six children with CP, comparing seven protocols, including an individualized physical-therapist-derived (PT-derived) protocol against a no-stimulation baseline and typically developing controls. Gait quality was assessed using the Gait Deviation Index (GDI) as the primary outcome, alongside the Coefficient of Variation (CV) and targeted kinematic measures. Results were mixed: group-level GDI differences were not significant, though CV analyses showed multi-muscle conditions produced more consistently favorable gait patterns than single-muscle stimulation. Stimulation condition significantly affected maximum knee extension and Dynamic Time Warping during ankle loading response and hip pre-swing; however, after correction for multiple comparisons, no protocol differed significantly from baseline. The PT-derived condition showed favorable directional trends across several outcomes, though not consistently significant. These preliminary findings suggest multi-muscle, individualized NMES strategies may produce phase- and joint-specific biomechanical effects, but larger studies with better gait-phase detection and longer exposure are needed before drawing clinical conclusions.

Background: Outcomes >2 years after transcatheter aortic valve replacement (TAVR) for bicuspid aortic valves (BAV) are scarce, and differences between balloon‐expandable transcatheter heart valves (THVs) and self‐expandable (SE‐THVs) are not yet well established. Methods: This study aims to report midterm outcomes after TAVR in patients with BAV and includes 92 patients undergoing TAVR for BAV stenosis at the University Hospital Cologne between 2018 and 2023. The primary outcomes were all‐cause death, cardiovascular death, and stroke over a mean follow‐up of 2.9 years. Results: Among 92 consecutive patients undergoing TAVR for BAV stenosis (median age: 78.8 years), the incidence of all‐cause death, cardiovascular death, and stroke was 26.1%, 18.5%, and 14.1%, respectively, at 2.9 years, with no differences between balloon‐expandable THVs and SE‐THVs. Pacemaker implantation tended to be more frequent in the SE‐THV group. Periprocedural complications were rare, as reflected by a high Valve Academic Research Consortium‐3 technical success rate of 96.7%. Postprocedural transvalvular gradients were favorable, with SE‐THV showing lower values than balloon‐expandable THV (8.0 versus 10.5 mm Hg, P =0.007). Moderate or severe paravalvular regurgitation was uncommon, with no differences between groups, although a trend toward more relevant paravalvular regurgitation with SE‐THV was observed. Conclusions: TAVR for BAV is feasible with both SE‐THV and balloon‐expandable ‐THV, achieving high technical success and low complication rates. Hemodynamic differences were observed, but mortality and stroke did not differ significantly between groups. Overall outcomes remain suboptimal, highlighting the need for randomized trials comparing valve types and TAVR with surgery for patients with BAV.

Background: The Valve Academic Research Consortium (VARC) has updated criteria for periprocedural bleeding after transcatheter aortic valve replacement. However, clinical validation of the VARC‐3 bleeding definition is scarce. The aim of this study was to evaluate incidence, associated variables, and clinical impact of VARC‐3 bleeding. Methods: The study included 2227 patients with severe aortic stenosis undergoing transcatheter aortic valve replacement between 2018 and 2023 at the University Hospital Cologne. VARC‐3 bleeding during the index hospitalization were analyzed. Incidence, variables associated with bleeding, and impact on 30‐day mortality were evaluated by comparison to the VARC‐2 criteria. All data were prospectively collected. Results: VARC‐3 bleeding was 2.5 times more prevalent than VARC‐2 (13.9% versus 34.4%), as VARC‐3 includes nonattributable blood loss >3 g/dL as a bleeding event. Chronic kidney disease, thoracotomy access, dual antiplatelet therapy ( P P =0.023) were variables associated with VARC‐3 bleedings. Type 3 bleeding (VARC‐3) was associated with an increased 30‐day mortality (hazard ratio [HR], 2.89 [95% CI, 1.35–6.19], P =0.006). VARC‐2 major and life‐threatening bleeding events were associated with increased 30‐day mortality as well (HR, 2.74 [95% CI, 1.26–5.95], P =0.011 and HR, 29.60 [95% CI, 17.42–50.30], P <0.001). Conclusions: The VARC‐3 criteria present a refined classification for bleeding with prognostic relevance. However, the VARC‐2 criteria demonstrate precision and clear correlation with increasing mortality risk proportional to the severity of bleeding too, showing even greater predictive accuracy in the transfemoral cohort. These findings require further validation with similar or even larger patient cohorts.

Background: Patients ≥80 years old were underrepresented or excluded from landmark trials demonstrating the superiority of primary percutaneous coronary intervention (PCI) in ST‐segment–elevation myocardial infarction. The current meta‐analysis assessed the effects of an invasive strategy with intended PCI compared with conservative treatment in older people (≥80 years) with ST‐segment–elevation myocardial infarction. Methods: A structured literature search was performed. The primary outcome was overall survival. Secondary outcome analyses included but were not limited to 30‐day and 1‐year mortality. Results: Thirteen studies reporting on 102 158 older adults were included. Of these, 31 629 (31%) were assigned to PCI and 70 529 (69%) were treated conservatively. The overall survival was 76.5% in PCI and 67.2% in conservative treatment at the time of longest available follow‐up (odds ratio [OR], 2.18 [95% CI, 1.79–2.66], P I ² =88%, favoring PCI). The follow‐up period ranged from 30 days to 26.5 months. The 30‐day. (OR, 0.39 [95% CI, 0.31–0.50], P I ² =0%) and 1‐year mortality (OR, 0·34 [95% CI, 0.25–0.46], P I ² =0%), were lower in the PCI group. Conclusions: This meta‐analysis indicates a potential underuse of PCI in older adults with ST‐segment–elevation myocardial infarction. PCI was advantageous in short‐ and long‐term survival, but these results were affected by confounding. Nonetheless, every second patient not referred for invasive treatment survived at least 1 year. These findings have hypothesis generating implications, but they indicate ageism and emphasize that PCI should not be automatically withheld in older patients.

The recent commercial availability of stacked dielectric elastomer actuators (SDEAs) has unlocked new opportunities for their application as “artificial skeletal muscles” in rehabilitation robots and powered exoskeletons. Composed of multiple layers of thin, elastic capacitors, these actuators present a lightweight, soft, and acoustically noiseless alternative to traditional DC motor actuators commonly used in rehabilitation robotics, thereby enhancing the natural feel of such systems. Building on our previous research, this study aimed to evaluate the most recent version of commercial SDEAs to assess their potential for mechanizing rehabilitation robots. We quantified the stress and strain behavior and stiffness of these actuators in both single and 1 × 3 configurations (with three SDEAs connected in series). The actuators demonstrated the capability to generate up to 25 N of force and 115 KPa, a value surpassing human biceps, with a longitudinal strain measured at about 11%. The significant increase in force generation from 10 N in the previous version to 25 N and displacement from 3.3% to 11% substantially enhances the applicability of this actuator in rehabilitation robotics. SDEAs’ high force generation capability, combined with their strain and stress characteristics comparable to that of human biological muscles, make them ideal alternative actuators for biomimetic robots and applications where actuators must operate in the vicinity of the human body.

The recent commercial availability of stacked dielectric elastomer actuators (SDEAs) has unlocked new opportunities for their application as "artificial skeletal muscles" in rehabilitation robots and powered exoskeletons. Composed of multiple layers of thin, elastic capacitors, these actuators present a lightweight, soft, and acoustically noiseless alternative to traditional DC motor actuators commonly used in rehabilitation robotics, thereby enhancing the natural feel of such systems. Building on our previous research, this study aimed to evaluate the most recent version of commercial SDEAs to assess their potential for mechanizing rehabilitation robots. We quantified the stress and strain behavior and stiffness of these actuators in both single and 1x3 configurations (with three SDEAs connected in series). The actuators demonstrated the capability to generate up to 25 N of force, 103 KPa, a value closely resembling human biceps, with a longitudinal strain measured at about 11%. The significant increase in force generation from 10 N, in the previous version, to 25 N and displacement from 3.3% to 11% substantially enhances the applicability of this actuator rehabilitation robotics. SDEAs' high force generation capability, combined with their strain and stress characteristics comparable to that of human biological muscles make them ideal alternative actuators for biomimetic robots and applications where actuators must operate in the vicinity of the human body.

Conventional passive ankle foot orthoses (AFOs) have not seen substantial advances or functional improvements for decades, failing to meet the demands of many stakeholders, especially the pediatric population with neurological disorders. Our objective is to develop the first comfortable and unobtrusive powered AFO for children with cerebral palsy (CP), the DE-AFO. CP is the most diagnosed neuromotor disorder in the pediatric population. The standard of care for ankle control dysfunction associated with CP, however, is an unmechanized, bulky, and uncomfortable L-shaped conventional AFO. These passive orthoses constrain the ankle’s motion and often cause muscle disuse atrophy, skin damage, and adverse neural adaptations. While powered orthoses could enhance natural ankle motion, their reliance on bulky, noisy, and rigid actuators like DC motors limits their acceptability. Our innovation, the DE-AFO, emerged from insights gathered during customer discovery interviews with 185 stakeholders within the AFO ecosystem as part of the NSF I-Corps program. The DE-AFO is a biomimetic robot that employs artificial muscles made from an electro-active polymer called dielectric elastomers (DEs) to assist ankle movements in the sagittal planes. It incorporates a gait phase detection controller to synchronize the artificial muscles with natural gait cycles, mimicking the function of natural ankle muscles. This device is the first of its kind to utilize lightweight, compact, soft, and silent artificial muscles that contract longitudinally, addressing traditional actuated AFOs’ limitations by enhancing the orthosis’s natural feel, comfort, and acceptability. In this paper, we outline our design approach and describe the three main components of the DE-AFO: the artificial muscle technology, the finite state machine (the gait phase detection system), and its mechanical structure. To verify the feasibility of our design, we theoretically calculated if DE-AFO can provide the necessary ankle moment assistance for children with CP—aligning with moments observed in typically developing children. To this end, we calculated the ankle moment deficit in a child with CP when compared with the normative moment of seven typically developing children. Our results demonstrated that the DE-AFO can provide meaningful ankle moment assistance, providing up to 69% and 100% of the required assistive force during the pre-swing phase and swing period of gait, respectively.