Medical Microrobots

Scientists around the world have long aimed to produce miniature robots that can be controlled inside the human body to aid doctors in identifying and treating diseases. Such microrobots hold the potential to access hard-to-reach areas of the body through the natural lumina. Wireless access has the potential to overcome drawbacks of systemic therapy, as well as to enable completely new minimally invasive procedures. The aim of this review is fourfold: first, to provide a collection of valuable anatomical and physiological information on the target working environments together with engineering tools for the design of medical microrobots; second, to provide a comprehensive updated survey of the technological state of the art in relevant classes of medical microrobots; third, to analyze currently available tracking and closed loop control strategies compatible with the in-body environment; and fourth, to explore the challenges still in place, to steer and inspire future research.

A vibrating capillary for ultrasound rotation manipulation of zebrafish larvae

Multifunctional micromanipulation systems have garnered significant attention due to the growing interest in biological and medical research involving model organisms like zebrafish (Danio rerio). Here, we report a novel acoustofluidic rotational micromanipulation system that offers rapid trapping, high-speed rotation, multi-angle imaging, and 3D model reconstruction of zebrafish larvae. An ultrasound-activated oscillatory glass capillary is used to trap and rotate a zebrafish larva. Simulation and experimental results demonstrate that both the vibrating mode and geometric placement of the capillary contribute to the developed polarized vortices along the long axis of the capillary. Given its capacities for easy-to-operate, stable rotation, avoiding overheating, and high-throughput manipulation, our system poses the potential to accelerate zebrafish-directed biomedical research.

SonoTransformers: Transformable acoustically activated wireless microscale machines

Shape transformation, a key mechanism for organismal survival and adaptation, has gained importance in developing synthetic shape-shifting systems with diverse applications ranging from robotics to bioengineering. However, designing and controlling microscale shape-shifting materials remains a fundamental challenge in various actuation modalities. As materials and structures are scaled down to the microscale, they often exhibit size-dependent characteristics, and the underlying physical mechanisms can be significantly affected or rendered ineffective. Additionally, surface forces such as van der Waals forces and electrostatic forces become dominant at the microscale, resulting in stiction and adhesion between small structures, making them fracture and more difficult to deform. Furthermore, despite various actuation approaches, acoustics have received limited attention despite their potential advantages. Here, we introduce "SonoTransformer," the acoustically activated micromachine that delivers shape transformability using preprogrammed soft hinges with different stiffnesses. When exposed to an acoustic field, these hinges concentrate sound energy through intensified oscillation and provide the necessary force and torque for the transformation of the entire micromachine within milliseconds. We have created machine designs to predetermine the folding state, enabling precise programming and customization of the acoustic transformation. Additionally, we have shown selective shape transformable microrobots by adjusting acoustic power, realizing high degrees of control and functional versatility. Our findings open new research avenues in acoustics, physics, and soft matter, offering new design paradigms and development opportunities in robotics, metamaterials, adaptive optics, flexible electronics, and microtechnology.

Ultrasound robotics for precision therapy

In recent years, the application of microrobots in precision therapy has gained significant attention. The small size and maneuverability of these micromachines enable them to potentially access regions that are difficult to reach using traditional methods; thus, reducing off-target toxicities and maximizing treatment effectiveness. Specifically, acoustic actuation has emerged as a promising method to exert control. By harnessing the power of acoustic energy, these small machines potentially navigate the body, assemble at the desired sites, and deliver therapies with enhanced precision and effectiveness. Amidst the enthusiasm surrounding these miniature agents, their translation to clinical environments has proven difficult. The primary objectives of this review are threefold: firstly, to offer an overview of the fundamental acoustic principles employed in the field of microrobots; secondly, to assess their current applications in medical therapies, encompassing tissue targeting, drug delivery or even cell infiltration; and lastly, to delve into the continuous efforts aimed at integrating acoustic microrobots into in vivo applications.

Steerable acoustically powered starfish-inspired microrobot

Soft polymeric microrobots that can be loaded with nanocargoes and driven via external field stimuli can provide innovative solutions in various fields, including precise microscale assembly, targeted therapeutics, microsurgery, and the capture and degradation of unwanted wastewater fragments. However, in aquatic environments, it remains challenging to operate with microrobotic devices due to the predominant viscous resistances and the robots' limited actuation and sensing capabilities attributed to their miniaturization. The miniature size prevents the incorporation of onboard batteries that can provide sufficient power for propulsion and navigation, necessitating a wireless power supply. Current research examines untethered microrobot manipulation using external magnetic, electric, thermodynamic, or acoustic field-guided technologies: all strategies capable of wireless energy transmission towards sensitive and hard-to-reach locations. Nonetheless, developing a manipulation strategy that harnesses simple-to-induce strong propulsive forces in a stable manner over extended periods of time remains a significant endeavor. This study presents the fabrication and manipulation of a microrobot consisting of a magnetized soft polymeric composite material that enables a combination of stable acoustic propulsion through starfish-inspired artificial cilia and magnetic field-guided navigation. The acousto-magnetic manipulation strategy leverages the unique benefits of each applied field in the viscous-dominated microscale, namely precise magnetic orientation and strong acoustic thrust.

Human-black bear conflict: crop raiding by Asiatic black bear (Ursus thibetanus) in Azad Jammu and Kashmir, Pakistan

Abstract Asiatic black bear has long been in conflict with human beings crop raiding is a major cause of this conflict frequently noted in South Asia. Crops raided by black bears affected by temporal, spatial and anthropogenic attributes. Insight in this conflict and its mitigation is vital for the conservation of this threatened species. Present study aimed to evaluate crop raiding by black bears in the mountainous region of Azad Jammu and Kashmir. Field surveys were carried out to observe spatial and temporal crop raiding features between 2015-2020 and data gathered using designed questionnaires randomly tailored in villages nearby the forests. Results revealed that maize was the sole crop raided by black bears. A total of 28-acre area was raided by black bear in the fall season (Aug-November) resulting in a damage of 51 metric tons, whole raiding was carried out at night. Each respondent received crop damage on 0.09 acre with a loss of 0.17 metric ton yield. Crop quantity and area were significantly correlated to each other. District Neelum shared 49% of the total crop loss, while 47% of the maize was raided at the altitudinal range of 2100-2500 m. crop raiding was highly significantly ( χ 2 = 1174.64 ; d f = 308 ; p < 0.01) dependent upon distance to the forest. Linear regression revealed that maize quantity was determined by area, time and the total field area. Farmers faced 3.8 million PKRs loss due to crop damage by black bears. Despite the huge loss, the majority (23%) of the respondents did not respond to the query on mitigation measures indicating a poor adaptation of preventive measures. Preferred strategy to avoid crop damage was making noise (27.8%) when bears attacked their crops. A start of compensation scheme to the farmers is recommended that will have turned their negative attitude into a positive one toward the wildlife and black bear particularly. Study provides a new insight in human-bear conflict, particularly in spatial and temporal context of crop raiding in AJ&K.

An acoustically controlled helical microrobot

As a next-generation toolkit, microrobots can transform a wide range of fields, including micromanufacturing, electronics, microfluidics, tissue engineering, and medicine. While still in their infancy, acoustically actuated microrobots are becoming increasingly attractive. However, the interaction of acoustics with microstructure geometry is poorly understood, and its study is necessary for developing next-generation acoustically powered microrobots. We present an acoustically driven helical microrobot with a length of 350 μm and a diameter of 100 μm that is capable of locomotion using a fin-like double-helix microstructure. This microrobot responds to sound stimuli at ~12 to 19 kHz and mimics the spiral motion of natural microswimmers such as spirochetes. The asymmetric double helix interacts with the incident acoustic field, inducing a propulsion torque that causes the microrobot to rotate around its long axis. Moreover, our microrobot has the unique feature of its directionality being switchable by simply tuning the acoustic frequency. We demonstrate this locomotion in 2D and 3D artificial vasculatures using a single sound source.

Ultrasound trapping and navigation of microrobots in the mouse brain vasculature

The intricate and delicate anatomy of the brain poses significant challenges for the treatment of cerebrovascular and neurodegenerative diseases. Thus, precise local drug delivery in hard-to-reach brain regions remains an urgent medical need. Microrobots offer potential solutions; however, their functionality in the brain remains restricted by limited imaging capabilities and complications within blood vessels, such as high blood flows, osmotic pressures, and cellular responses. Here, we introduce ultrasound-activated microrobots for in vivo navigation in brain vasculature. Our microrobots consist of lipid-shelled microbubbles that autonomously aggregate and propel under ultrasound irradiation. We investigate their capacities in vitro within microfluidic-based vasculatures and in vivo within vessels of a living mouse brain. These microrobots self-assemble and execute upstream motion in brain vasculature, achieving velocities up to 1.5 µm/s and moving against blood flows of ~10 mm/s. This work represents a substantial advance towards the therapeutic application of microrobots within the complex brain vasculature.

Aneurysmal growth in type-B aortic dissection: assessing the impact of patient-specific inlet conditions on key haemodynamic indices

Type-B aortic dissection is a cardiovascular disease in which a tear develops in the intimal layer of the descending aorta, allowing pressurized blood to delaminate the layers of the vessel wall. In medically managed patients, long-term aneurysmal dilatation of the false lumen (FL) is considered virtually inevitable and is associated with poorer disease outcomes. While the pathophysiological mechanisms driving FL dilatation are not yet understood, haemodynamic factors are believed to play a key role. Computational fluid dynamics (CFD) and 4D-flow MRI (4DMR) analyses have revealed correlations between flow helicity, oscillatory wall shear stress and aneurysmal dilatation of the FL. In this study, we compare CFD simulations using a patient-specific, three-dimensional, three-component inlet velocity profile (4D IVP) extracted from 4DMR data against simulations with flow rate-matched uniform and axial velocity profiles that remain widely used in the absence of 4DMR. We also evaluate the influence of measurement errors in 4DMR data by scaling the 4D IVP to the degree of imaging error detected in prior studies. We observe that oscillatory shear and helicity are highly sensitive to inlet velocity distribution and flow volume throughout the FL and conclude that the choice of IVP may greatly affect the future clinical value of simulations.

Acoustic microbubble propulsion, train-like assembly and cargo transport

Achieving controlled mobility of microparticles in viscous fluids can become pivotal in biologics, biotechniques, and biomedical applications. The self-assembly, trapping, and transport of microparticles are being explored in active matter, micro and nanorobotics, and microfluidics; however, little work has been done in acoustics, particularly in active matter and robotics. This study reports the discovery and characterization of microbubble behaviors in a viscous gel that is confined to a slight opening between glass boundaries in an acoustic field. Where incident waves encounter a narrow slit, acoustic pressure is amplified, causing the microbubbles to nucleate and cavitate within it. Intermittent activation transforms microbubbles from spherical to ellipsoidal, allowing them to be trapped within the interstice. Continuous activation propels ellipsoidal microbubbles through shape and volume modes that is developed at their surfaces. Ensembles of microbubbles self-assemble into a train-like arrangement, which in turn capture, transport, and release microparticles.

'This is hardcore': a qualitative study exploring service users' experiences of Heroin-Assisted Treatment (HAT) in Middlesbrough, England

BACKGROUND

Heroin-Assisted Treatment (HAT) is well evidenced internationally to improve health and social outcomes for people dependent on opioids who have not been helped by traditional treatment options. Despite this evidence base, England has been slow to implement HAT. The first service outside of a trial setting opened in 2019, providing twice-daily supervised injections of medical-grade heroin (diamorphine) to a select sample of high-risk heroin users in Middlesbrough. This paper explores their experiences, including the negotiation of the strict regularly controls required of a novel intervention in the UK context.

METHODS

We conducted in-depth interviews with service providers and users of the Middlesbrough HAT service between September and November 2021. Data from each group were thematically analysed and reported separately. This paper details the experiences of the twelve heroin dependent men and women accessing HAT.

RESULTS

Participants' accounts of HAT treatment evidenced a tension between the regulatory constraints and uncertainty of treatment provision, and the positive outcomes experienced through supportive service provision and an injectable treatment option. Limited confidence was held in treatment efficacy, longevity of funding, and personal capacity for treatment success. This was counteracted by a strong motivation to cease engagement with the illicit drug market. While attendance requirements placed restrictions on daily activities, participants also experienced benefits from strong, supportive bonds built with the service providers through their continued engagement.

CONCLUSIONS

The Middlesbrough HAT programme provided benefits to a high-risk population of opioid dependent people who were unable or disinclined to participate in conventional opioid substitution treatments. The findings in this paper highlight the potential for service modifications to further enhance engagement. The closure of this programme in 2022 prohibits this opportunity for the Middlesbrough community, but holds potential to inform advocacy and innovation for future HAT interventions in England.

Rolling microswarms along acoustic virtual walls

Rolling is a ubiquitous transport mode utilized by living organisms and engineered systems. However, rolling at the microscale has been constrained by the requirement of a physical boundary to break the spatial homogeneity of surrounding mediums, which limits its prospects for navigation to locations with no boundaries. Here, in the absence of real boundaries, we show that microswarms can execute rolling along virtual walls in liquids, impelled by a combination of magnetic and acoustic fields. A rotational magnetic field causes individual particles to self-assemble and rotate, while the pressure nodes of an acoustic standing wave field serve as virtual walls. The acoustic radiation force pushes the microswarms towards a virtual wall and provides the reaction force needed to break their fore-aft motion symmetry and induce rolling along arbitrary trajectories. The concept of reconfigurable virtual walls overcomes the fundamental limitation of a physical boundary being required for universal rolling movements.

A robot-assisted acoustofluidic end effector

Liquid manipulation is the foundation of most laboratory processes. For macroscale liquid handling, both do-it-yourself and commercial robotic systems are available; however, for microscale, reagents are expensive and sample preparation is difficult. Over the last decade, lab-on-a-chip (LOC) systems have come to serve for microscale liquid manipulation; however, lacking automation and multi-functionality. Despite their potential synergies, each has grown separately and no suitable interface yet exists to link macro-level robotics with micro-level LOC or microfluidic devices. Here, we present a robot-assisted acoustofluidic end effector (RAEE) system, comprising a robotic arm and an acoustofluidic end effector, that combines robotics and microfluidic functionalities. We further carried out fluid pumping, particle and zebrafish embryo trapping, and mobile mixing of complex viscous liquids. Finally, we pre-programmed the RAEE to perform automated mixing of viscous liquids in well plates, illustrating its versatility for the automatic execution of chemical processes.

Light-driven high-precision cell adhesion kinetics

Existing single-cell adhesion kinetics methods are performed under conditions highly unlike the physiological cell adhesion conditions. Now, researchers have developed a new optical technique for high-precision measurement of cell lateral adhesion kinetics in complex clinical samples.

In vivo acoustic manipulation of microparticles in zebrafish embryos

In vivo micromanipulation using ultrasound is an exciting technology with promises for cancer research, brain research, vasculature biology, diseases, and treatment development. In the present work, we demonstrate in vivo manipulation of gas-filled microparticles using zebrafish embryos as a vertebrate model system. Micromanipulation methods often are conducted in vitro, and they do not fully reflect the complex environment associated in vivo. Four piezoelectric actuators were positioned orthogonally to each other around an off-centered fluidic channel that allowed for two-dimensional manipulation of intravenously injected microbubbles. Selective manipulation of microbubbles inside a blood vessel with micrometer precision was achieved without interfering with circulating blood cells. Last, we studied the viability of zebrafish embryos subjected to the acoustic field. This successful high-precision, in vivo acoustic manipulation of intravenously injected microbubbles offers potentially promising therapeutic options.

Ultrasound-activated ciliary bands for microrobotic systems inspired by starfish

Cilia are short, hair-like appendages ubiquitous in various biological systems, which have evolved to manipulate and gather food in liquids at regimes where viscosity dominates inertia. Inspired by these natural systems, synthetic cilia have been developed and utilized in microfluidics and microrobotics to achieve functionalities such as propulsion, liquid pumping and mixing, and particle manipulation. Here, we demonstrate ultrasound-activated synthetic ciliary bands that mimic the natural arrangements of ciliary bands on the surface of starfish larva. Our system leverages nonlinear acoustics at microscales to drive bulk fluid motion via acoustically actuated small-amplitude oscillations of synthetic cilia. By arranging the planar ciliary bands angled towards (+) or away (-) from each other, we achieve bulk fluid motion akin to a flow source or sink. We further combine these flow characteristics with a physical principle to circumvent the scallop theorem and realize acoustic-based propulsion at microscales. Finally, inspired by the feeding mechanism of a starfish larva, we demonstrate an analogous microparticle trap by arranging + and - ciliary bands adjacent to each other.

Evaluation of a calculation model to estimate the impact of the COVID-19 pandemic lockdown on visual acuity in neovascular AMD

Purpose

A model was calculated during the first Austrian coronavirus disease-2019 (COVID-19) pandemic lockdown to estimate the effect of a short-term treatment interruption due to healthcare restrictions on visual acuity (VA) in neovascular age-related macular degeneration (nAMD). The model was compared to the real-life outcomes before treatment re-started.

Methods

Retrospective data-collection of 142 eyes in 142 patients receiving repeated intravitreal injections with anti-VEGF at a retina unit in Vienna in a personalized pro-re-nata regimen prior to the COVID-19 associated lockdown, when treatment was deferred between March 16 and May 4, 2020. During the lockdown, the preliminary data was integrated into pre-existing formulae based on the natural course of the disease in untreated eyes in the long term. Patients were re-scheduled and treated after gradually opening operating rooms. The calculation model was compared to the effective VA change.

Results

The model calculated an overall VA loss of 3.5 ± 0.8 letters early treatment diabetes retinopathy study (ETDRS) (p < 0.001 [95% CI:3.3;3.6]) on average compared to 2.5 ± 6 letters ETDRS (p < 0.001 [95% CI:1.5;3.5]) as measured with a mean treatment delay of 61 ± 14 days after previously scheduled appointments. The total difference between the model exercise and the real-life outcomes accounted for 1 ± 5.9 letters ETDRS (p = 0.051 [95% CI: 0.1;1.9]).

Conclusion

The herein presented calculation model might not be suitable to estimate the effective VA loss correctly over time, although untreated eyes and eyes under therapy show similarities after short-term treatment interruption. However, this study demonstrated the potentially negative impact of the COVID-19 pandemic lockdown on patients compromised by nAMD.

Comparison of different diagnostic modalities for isolation of Mycobacterium Tuberculosis among suspected tuberculous lymphadenitis patients

Tuberculosis is a communicable disease with high morbidity and mortality rates in developing countries. The study's primary objective is to compare conventional methods such as acid-fast bacillus (AFB) culture and microscopy with rapid diagnostic methods. The secondary objective is to compare histopathological and microbiological findings in suspected patients with tubercular lymphadenitis. A total of 111 samples (August 2018 to September 2019) of lymph nodes were processed for AFB microscopy, AFB cultures, drug-susceptibility testing (DST), histopathology, and Xpert Mycobacterium Tuberculosis (MTB)/resistance to Rifampin (RIF) assays. Out of 111 lymph node samples, 6 (5.4%) were positive for AFB smear microscopy, 84 (75.6%) were positive for AFB culture, 80 (70.7%) were positive on Gene Xpert, and 102 (91.8%) were indicative of tuberculosis for histopathology studies. Mycobacteria growth indicator tube (MGIT) culture positivity was 84 (75.6%) higher than solid Lowenstein-Jensen (LJ) culture 74 (66.6%). Positive cultures underwent phenotypic DST. Two cases were Multidrug-resistant (MDR) on DST, while three cases were Rifampicin resistant on Gene Xpert. The sensitivity of Genexpert was (62%) against the conventional AFB culture method. The poor performance of conventional lymphadenitis diagnostic methods requires early and accurate diagnostic methodology. Xpert MTB/RIF test can help in the treatment of multidrug-resistant TB cases. Nonetheless, rapid and conventional methods should be used for complete isolation of Mycobacterium tuberculosis.

The Effect of Treatment Discontinuation During the COVID-19 Pandemic on Visual Acuity in Exudative Neovascular Age-Related Macular Degeneration: 1-Year Results

Introduction

To evaluate the effect of a 9-week treatment deferral due to healthcare restrictions caused by Austria’s first governmental lockdown associated with the coronavirus disease 2019 (COVID-19) pandemic on visual acuity (VA) in eyes compromised by exudative neovascular age-related macular degeneration (nAMD) after 1 year.

Methods

Retrospective data collection of 98 eyes (98 patients) with a treatment discontinuation at a tertiary eye care center (Clinic Landstraße, Vienna Healthcare Group, Austria) between March 16 and May 4, 2020. Prior to the lockdown, patients received multiple intravitreal injections (IVI) of anti-vascular endothelial growth factor with a personalized treatment interval for 3 years on average and at least three IVI after the lockdown.

Results

When the treatment interval doubled to 117.6 ± 31.4 days in spring 2020, patients lost 2.2 ± 4.6 ETDRS letters (p = 0.002) on average before reinitiating therapy. In total, 4.1 ± 8.1 letters (p < 0.0001) were lost despite continuous individual re-treatment over the course of the next year. In a univariate analysis, the extended interval time remained statistically significant (p < 0.0001), indicating a larger VA reduction within intervals with increasing interval time in days.

Conclusion

The short-term treatment interruption had a persistent negative impact on the VA course of eyes under therapy after 1 year. Continuous therapy independent of the underlying treatment regimen remains of utmost importance in exudative nAMD. Our data should create awareness to regulators regarding future decisions despite the global pandemic.

Supplementary Information

The online version contains supplementary material available at 10.1007/s40123-021-00381-y.

Age-related macular degeneration (AMD) is the leading cause of legal blindness in developed countries. Wet AMD refers to the existence of new vessel growth in the macular, the part of the retina with the highest concentration of photoreceptors and hence the best visual acuity. The gold standard therapy of wet AMD consists of repeated injections of an antibody against new vessel formation into the eye to stabilize the disease. The sudden break of a treatment regimen for an individual person has never been investigated as it is ethically not acceptable. The coronavirus disease 2019 (COVID-19) pandemic and its associated lockdown led to an emerging situation in spring, 2020. We were forced by governmental restrictions to minimize contact with the most vulnerable patient cohort—the elderly. As an initial consequence, the Medical Retina Unit of Department of Ophthalmology (Clinic Landstraße, Vienna Healthcare Group, Austria) postponed appointments of patients with only one eye afflicted by wet AMD. This study examined the effect of a short-term treatment deferral caused by the first national COVID-19 lockdown in eyes of patients with ongoing therapy of wet AMD in Austria. The break led to a persistent visual loss despite re-treatment, which was still evident after 1 year. Our findings provide further support for an adequate and permanent therapy of wet AMD and regard intravitreal injections as urgent standard of care. It should be taken into consideration by authorities in future pandemic planning.

Embedded Microbubbles for Acoustic Manipulation of Single Cells and Microfluidic Applications

Acoustically excited microstructures have demonstrated significant potential for small-scale biomedical applications by overcoming major microfluidic limitations. Recently, the application of oscillating microbubbles has demonstrated their superiority over acoustically excited solid structures due to their enhanced acoustic streaming at low input power. However, their limited temporal stability hinders their direct applicability for industrial or clinical purposes. Here, we introduce the embedded microbubble, a novel acoustofluidic design based on the combination of solid structures (poly(dimethylsiloxane)) and microbubbles (air-filled cavity) to combine the benefits of both approaches while minimizing their drawbacks. We investigate the influence of various design parameters and geometrical features through numerical simulations and experimentally evaluate their manipulation capabilities. Finally, we demonstrate the capabilities of our design for microfluidic applications by investigating its mixing performance as well as through the controlled rotational manipulation of individual HeLa cells.

Bioaccumulation of heavy metals in the tissues of Schizothorax plagiostomus at River Swat

Snow trout (Schizothorax plagiostomus) is an economically important freshwater fish, mostly found in northern areas of water reservoirs of Pakistan. The current study was conducted in River Swat to analyze the bioaccumulation of heavy metals (Pb, Cr, Ni, and Zn) in tissues of Schizothorax plagiostomus. Tissues were extracted and dissolved in perchloric acid (HClO4) and nitric acid (HNO3) along with hotplate. The heavy metals, zinc (Zn), lead (Pb), chromium (Cr), and Nickel (Ni) were determined using Perkin Elmer 2380 atomic absorption spectrophotometer. Results shows great variation in the content of the metal related to tissue type and sampling sites. A high concentration of bioaccumulation was reported at Charbagh, whereas lowest at Odigram: Charbagh>Landakai>Odigram. In the same way, Cr was the most accumulated heavy metal followed by lead, nickel, and Zinc.

ProGlide venous closure device facilitates early ambulation following cryoablation of atrial fibrillation

Funding Acknowledgements

Type of funding sources: Foundation. Main funding source(s): Heart Foundation

Background

Same-day discharge following atrial fibrillation (AF) ablation is increasingly common. ProGlide device suture-mediated vascular closure (PD) offers a technique that may expedite mobilisation following large-bore (&gt;12F) venous access. The utility of PD closure following cryoablation of AF has not been reported.

Purpose

We sought to evaluate haemostasis and early ambulation outcomes in patients receiving the ProGlide compared with conventional techniques.

Methods

104 consecutive patients undergoing cryoballoon pulmonary vein isolation (PVI) for paroxysmal or persistent at a single high-volume institution were included. PVI was  performed via a standardised approach including sedation, ultrasound-guided vascular access for 14F Cryosheath and second 7F sheath, anticoagulation protocol, transeptal puncture, 28mm cryoballoon and nurse-led same-day discharge protocol. Haemostasis was achieved using the Perclose Proglide device (PD) in the 14F access point ("pre-closure" technique) plus 5 minutes manual pressure at the 7F sheath site. Alternatively, a figure-of-eight/Z-suture (ZS) was employed for closure according to operator preference. Protamine was used for heparin reversal in all patients. Safety outcomes of major bleeding, haematoma and minor bleeding were assessed. Time to ambulation (TTA), time to discharge (TTD), same-day discharge and complications at initial follow-up were measured.

Results

Overall, mean age was 64 ± 11 years, 65 (64%) were male and 52 (50%) of patients had paroxysmal AF, there were no significant differences between group demographics, with 31 patients (30%) in the PD group and 73 (70%) in the ZS group. All patients had uninterrupted oral anticoagulation throughout the periprocedural period. No major femoral bleeding complications requiring intervention occurred in either group. Haematomas occurred in none of the PD group compared with 2 (2.8%) in the ZS group. Incidence of minor bleeding was not significantly different between groups (PD: 3 [9.7%] vs ZS: 2 [2.7%], p = 0.155). Mean TTA was significantly shorter in the PD group (3.3 ± 1.1 vs 4.1 ± 1.7 hrs, p = 0.025). However, there was no significant difference in same-day discharge (PD: 25 [81%] vs ZS: 53 [73%], p = 0.386) and TTD (5.0 ± 3.6 vs 6.1 ± 4.2 hrs, p = 0.275) between groups. 1 patient complained of groin pain which delayed discharge in the ZS group not seen in the PD group. After a mean follow-up of 2.2 ± 1.4 months, there were no differences in major or minor complications.

Conclusion

Use of the Proglide closure device was associated with significant reductions in time to ambulation compared with Z-suture haemostasis following cryoablation of AF, and groin access complications were uncommon across groups.  PD closure may contribute to further streamlining patient pathways in day-case AF ablation.

Swept Source-Optical Coherence Tomography Angiography for Management of Secondary Choroidal Neovascularization in Punctate Inner Choroidopathy

The purpose was to demonstrate the diagnostic and therapeutic feasibility of swept source-optical coherence tomography angiography (SS-OCTA) by picturing neovascular changes secondary to a rare white dot syndrome following long-term intravitreal ranibizumab (IVR). A 28-year-old Caucasian myopic female presented with visual loss in her right eye only. The clinical examination and multimodal imaging including spectral domain (SD)-OCT, blue-peak autofluorescence, fluorescein, and indocyanine green angiography (HRA Spectralis, Heidelberg Engineering; Heidelberg, Germany) as well as SS-OCTA (DRI Triton, Topcon; Tokyo, Japan) led to the diagnosis of idiopathic punctate inner choroidopathy with secondary subfoveal choroidal neovascularization (CNV). In addition to oral corticosteroids, a pro re nata regimen with IVR was initiated and guided by repeated SD-OCT and SS-OCTA. Six IVR were administered based on functional SS-OCTA en face scans illustrating vessel transformation and downsizing of the CNV area while SD-OCT B-scans were inconclusive as indirect signs of activity were absent throughout the follow-up period. SS-OCTA provided new possibilities for monitoring vessel development. IVR was managed based on vessel density as displayed by SS-OCTA.

Systematic analysis of leisler's bat Nyctalus leisleri (Kuhl, 1817) captured from FATA region, Pakistan

Extensive field surveys were carried out to explore the distribution of Leisler's Bat Nyctalus leisleri (Kuhl, 1819) in selected area of FATA regions, Pakistan. Specimens of Leisler's Bat Nyctalus leisleri (Kuhl, 1819) (n5) were collected from Kurram Agency (Shublan) (N33.8229788 E70.1634414) at elevation 1427m and Khyber Agency (Landi Kotel) (N34.0909899 E71.1457517) at elevation 1091m for two years survey extending from May 2013 through August 2015. The mean head and body length, hind foot length, ear length and tail length the Nyctalus leisleri specimens captured from the study area was 65.08 ± 1.58 mm, 44.06 ± 0.52 mm, 8.38 ± 0.60 mm, 13.20 ± 0.99 mm and 39.46 ± 1.46 mm, respectively. For molecular analysis the sequences of COI gene were obtained and analyzed. The mean intraspecific divergences of Nyctalus leisleri was 0.04%. The mean interspecific divergences of Nyctalus noctula and Nyctalus leisleri was 0.2%. The mean concentration of each nucleotides was A = (26.3%), T = (32.8%), G = (15.9%) and C = (25.0%). The mean A+T contents were 59.2%and C+G were 40.9%. In the phylogenetic tree Nyctalus leisleri and Nyctalus noctula clustered with significant bootstrap support value.

3D mechanical characterization of single cells and small organisms using acoustic manipulation and force microscopy

Quantitative micromechanical characterization of single cells and multicellular tissues or organisms is of fundamental importance to the study of cellular growth, morphogenesis, and cell-cell interactions. However, due to limited manipulation capabilities at the microscale, systems used for mechanical characterizations struggle to provide complete three-dimensional coverage of individual specimens. Here, we combine an acoustically driven manipulation device with a micro-force sensor to freely rotate biological samples and quantify mechanical properties at multiple regions of interest within a specimen. The versatility of this tool is demonstrated through the analysis of single Lilium longiflorum pollen grains, in combination with numerical simulations, and individual Caenorhabditis elegans nematodes. It reveals local variations in apparent stiffness for single specimens, providing previously inaccessible information and datasets on mechanical properties that serve as the basis for biophysical modelling and allow deeper insights into the biomechanics of these living systems.

Effect of different protein based feed on the growth of mahseer

For the proper growth of fish, it is necessary to feed the fish with a proper and balanced diet. A study was conducted to find out the effect of different protein-based diets on fingerlings of Tor putitora (mahseer). A feed with dietary protein levels of 35%, 40%, 45%, and 50% were prepared. The effect of different protein-based feed on weight gain, standard growth rate (SGR), food conversion ratio (FCR), percent weight gain, food conversion efficiency (FCE), and protein efficiency ratio (PER) was studied. An increase was observed in the growth rate with an increase in protein concentration up to 45%. The fingerlings fed a 45% protein diet shown the highest growth, followed by 50%, 40%, and 35%. The SGR value was greatest for 45% protein diet (8.56) followed by 50% and 40%, while the least values were observed for 35% protein feed (1.57). The same trend was observed for FCE. The highest PER values was observed in fishes fed 45% protein-based feed (0.65) followed by 50% (0.56), 40% (0.38) and35% (0.17). The food conversion ratio was lowest for 45% protein diet (3.41), while the greatest for 35% protein feed (16.85). It was concluded that a 45% protein-based diet was the best feed formulation for higher production of Tor putitora. However, research on the same percentage of protein diet is recommended for yearlings.

Comparison of macular neovascularization lesion size by the use of Spectral-Domain Optical Coherence Tomography Angiography and Swept-Source Optical Coherence Tomography Angiography versus Indocyanine Green Angiography

PURPOSE

To compare the lesion sizes of macular neovascularization (MNV) imaged with spectral-domain (SD) and swept-source (SS) optical coherence tomography angiography (OCTA) as well as indocyanine green angiography (ICGA).

METHODS

In this prospective, observational case series, patients showing a secured diagnosis of MNV on ICGA or Fluorescein Angiography, were imaged by SD-OCTA and SS-OCTA on the same day. Lesion size was measured on 3 × 3-mm² and 6 × 6-mm² scans using the Maestro 2 SD-OCTA (Topcon Corporation, Tokyo Japan) and the Triton SS-OCTA device (Topcon Corporation, Tokyo Japan) and compared to ICGA (Spectralis HRA, Heidelberg, Germany).

RESULTS

Twenty eyes from 20 patients (11 females, 55%) were enrolled. The neovascularization area measured on 6 × 6-mm² SD-OCTA was lower compared to that outlined on SS-OCTA, however, not reaching statistical significance (p = 0.094). Regarding 3 × 3-mm² measurements, the median lesion sizes between the two OCTA devices were comparable (p = 0.492). Indocyanine green angiography depicted a larger lesion area than both OCTA devices, however, not reaching statistical significance.

CONCLUSION

SD-OCTA tends to show smaller areas of MNV extension than SS-OCTA regarding 6 × 6 mm² scans. The lesion size of MNV can be very well compared between the different devices, emphasizing the use of OCTA for monitoring neovascular area. Lesion measurements on SS-OCTA correlate better with ICGA than SD-OCTA.

Bio-inspired Acousto-magnetic Microswarm Robots with Upstream Motility

The ability to propel against flows, i.e., to perform positive rheotaxis, can provide exciting opportunities for applications in targeted therapeutics and non-invasive surgery. To date, no biocompatible technologies exist for navigating microparticles upstream when they are in a background fluid flow. Inspired by many naturally- occurring microswimmers such as bacteria, spermatozoa, and plankton that utilize the non-slip boundary conditions of the wall to exhibit upstream propulsion, here, we report on the design and characterization of self-assembled microswarms that can execute upstream motility in a combination of external acoustic and magnetic fields. Both acoustic and magnetic fields are safe to humans, non-invasive, can penetrate deeply into the human body, and are well-developed in clinical settings. The combination of both fields can overcome the limitations encountered by single actuation methods. The design criteria of the acoustically-induced reaction force of the microswarms, which is needed to perform rolling-type motion, are discussed. We show quantitative agreement between experimental data and our model that captures the rolling behaviour. The upstream capability provides a design strategy for delivering small drug molecules to hard-to-reach sites and represents a fundamental step toward the realization of micro- and nanosystem-navigation against the blood flow.

Mechanically interlocked 3D multi-material micromachines

Metals and polymers are dissimilar materials in terms of their physicochemical properties, but complementary in terms of functionality. As a result, metal-organic structures can introduce a wealth of novel applications in small-scale robotics. However, current fabrication techniques are unable to process three-dimensional metallic and polymeric components. Here, we show that hybrid microstructures can be interlocked by combining 3D lithography, mold casting, and electrodeposition. Our method can be used to achieve complex multi-material microdevices with unprecedented resolution and topological complexity. We show that metallic components can be combined with structures made of different classes of polymers. Properties of both metals and polymers can be exploited in parallel, resulting in structures with high magnetic responsiveness, elevated drug loading capacity, on-demand shape transformation, and elastic behavior. We showcase the advantages of our approach by demonstrating new microrobotic locomotion modes and controlled agglomeration of swarms.

Mechanically interlocking dissimilar materials, such as metals and polymers, is a challenging yet promising pathway for designing and fabricating complex systems on the small scale. Here, the authors report a novel interlocking fabrication scheme and showcase the fabrication of microrobots via 3D-lithography.

Correction to: Drusen characteristics of type 2 macular neovascularization in age-related macular degeneration

An amendment to this paper has been published and can be accessed via the original article.

Drusen characteristics of type 2 macular neovascularization in age-related macular degeneration

Background

Type 2 macular neovascularization (MNV) is supposed to be a rare condition in age-related macular degeneration (AMD). The main purpose of this study was to assess accompanying factors of type 2 MNV in AMD.

Methods

Retrospective data analysis of eyes previously diagnosed with neovascular AMD in a tertiary eye care center (Medical Retina Unit, Rudolf Foundation Hospital, Vienna, Austria) between June 2008 and December 2017. Drusen subtypes, fibrosis, atrophy and subfoveal choroidal thickness (SFCT) of both eyes in patients with type 2 MNV lesions were categorized based on multimodal imaging.

Results

Type 2 MNV was diagnosed in 27 (3.2%) of 835 eyes (749 patients). Drusen characteristics in type 2 MNV were observed as followed: drusen < 63 μm in 2 eyes (7.4%), drusen ≥63 μm in 10 eyes (37%), subretinal drusenoid deposits (SDD) in 8 eyes (29.6%), cuticular drusen in 2 eye (7.4%) and no drusen were evident in 10 eyes (37%). Drusen distribution in 23 fellow eyes was detected as followed: drusen < 63 μm in 2 eyes (8.7%), drusen ≥63 μm in 9 eyes (39.1%), SDD in 5 eyes (21.7%), cuticular drusen in 1 eye (4.3%) and no drusen were evident in 9 eyes (39.1%). Mean SFCT was 140 ± 49 μm in affected eyes and 152 ± 41 μm in the fellow eyes. Patients with drusen or SDD were significantly younger (mean 70.88 ± 6.85, p = 0.04) than patients without deposits (mean 77.40 ± 5.74).

Conclusions

Type 2 MNV remains a rare entity in AMD. It was frequently seen in the absence of drusen, a hallmark of AMD. These findings contribute to the heterogeneity of phenotypes related to pure type 2 lesions.

Magnetic cilia carpets with programmable metachronal waves

Metachronal waves commonly exist in natural cilia carpets. These emergent phenomena, which originate from phase differences between neighbouring self-beating cilia, are essential for biological transport processes including locomotion, liquid pumping, feeding, and cell delivery. However, studies of such complex active systems are limited, particularly from the experimental side. Here we report magnetically actuated, soft, artificial cilia carpets. By stretching and folding onto curved templates, programmable magnetization patterns can be encoded into artificial cilia carpets, which exhibit metachronal waves in dynamic magnetic fields. We have tested both the transport capabilities in a fluid environment and the locomotion capabilities on a solid surface. This robotic system provides a highly customizable experimental platform that not only assists in understanding fundamental rules of natural cilia carpets, but also paves a path to cilia-inspired soft robots for future biomedical applications.

OPTICAL COHERENCE TOMOGRAPHY ANGIOGRAPHY FOR THE DETECTION OF SECONDARY CHOROIDAL NEOVASCULARIZATION IN VITELLIFORM MACULAR DYSTROPHY

PURPOSE

Optical coherence tomography angiography (OCTA) is used to assess vascular abnormality in advanced stage vitelliform macular dystrophy (VMD2).

METHODS

Multimodal imaging including spectral domain (SD) OCT, autofluorescence (AF), fluorescein (FA) and indocyanine green angiography (ICGA) as well as optical coherence tomography angiography were performed.

PATIENTS

Two eyes in one young patient with diagnosed vitelliform macular dystrophy were investigated for progressive visual dysfunction.

RESULTS

Optical coherence tomography angiography identified neovascular formation within the outer retina and the choriocapillaris respectively while all other imaging methods were inconclusive.

CONCLUSION

Optical coherence tomography angiography was superior to conventional angiography in the detection of choroidal neovascularization (CNV) in advanced retinal disorders like vitelliform macular dystrophy.

P250 Evaluation of coronary endothelial dysfunction by positron emission tomography: does gender make a difference

Funding Acknowledgements

None

Introduction

Endothelial dysfunction (ED) manifested as abnormality of coronary microvasculature is associated with poor prognosis in patients presenting with chest pain. ED can be noninvasively evaluated by assessment of coronary flow reserve with positron emission tomography (PET). Studies directly comparing ED in men and women are limited. The aim of this study is to compare gender differences in ED as measured by CFR on PET myocardial perfusion imaging.

Methods

All the consecutive patients referred to PET-MPI between May 2011 and June 2018 were reviewed. Patient without known CAD who had normal perfusion were included in the analysis. Patient with abnormal electrocardiogram, significant transient ischemic dilatation, low left ventricular ejection fraction and high calcium score (&gt;1000 AU) and renal failure were excluded. CFR is calculated as the ratio of stress/rest myocardial blood flow. CFR &lt; 2 was considered as abnormal indicating the presence of ED.

Results

1711 patients were included in the analysis (mean age 60.2 ± 10 year, 68% females). Females were older and had higher BMI and diabetes (DM). Both resting and peak myocardial blood flow (MBF) was higher in females (1.16 vs 1.02 (p &lt; 0.0001)) and 3.26 vs 2.9 (p &lt; 0.001)0 respectively.  Around 68% of males had abnormal CFR (&lt;2) compared to 63% of females (p = 0.05). After adjusting for the confounders, female gender was associated with higher peak MBF (Hazard ratio 0.29, 95% CI 0.19 –0.40, p &lt; 0.001) and lower chance of having ED (Hazard ratio -0.15, 95% CI -0.29 - -0.005, p = 0.049)

Conclusions

Endothelial dysfunction as measured noninvasively by CFR on PET is prevalent among both sexes. Higher level of peak MBF in females may call for a different cut-off for abnormal CFR in women. Outcome studies are required to evaluate the clinical utility and prognostic value of such a cut-off.

Magnetic quadrupole assemblies with arbitrary shapes and magnetizations

Magnetic dipole-dipole interactions govern the behavior of magnetic matter across scales from micrometer colloidal particles to centimeter magnetic soft robots. This pairwise long-range interaction creates rich emergent phenomena under both static and dynamic magnetic fields. However, magnetic dipole particles, from either ferromagnetic or paramagnetic materials, tend to form chain-like structures as low-energy configurations due to dipole symmetry. The repulsion force between two magnetic dipoles raises challenges for creating stable magnetic assemblies with complex two-dimensional (2D) shapes. In this work, we propose a magnetic quadrupole module that is able to form stable and frustration-free magnetic assemblies with arbitrary 2D shapes. The quadrupole structure changes the magnetic particle-particle interaction in terms of both symmetry and strength. Each module has a tunable dipole moment that allows the magnetization of overall assemblies to be programmed at the single module level. We provide a simple combinatorial design method to reach both arbitrary shapes and arbitrary magnetizations concurrently. Last, by combining modules with soft segments, we demonstrate programmable actuation of magnetic metamaterials that could be used in applications for soft robots and electromagnetic metasurfaces.

P6158Prognostic value of non-obstructive coronary artery disease detected on coronary computed tomography angiography among subjects with suspected coronary artery disease

Introduction

Coronary Computed Tomography Angiography (CTA) is an established technique for the detection of coronary artery disease (CAD). However, the prognostic value of non-obstructive CAD is not well defined. Thus, the aim of this analysis is to determine the prognostic value of non-obstructive CAD detected on CTA.

Methods

In the Multi-Center Multi-Ethnic Coronary Computed Tomography Angiography (MECCA) Study, 3209 subjects without known CAD underwent CTA. Patients with obstructive CAD were excluded from this analysis. Patients with ≤70% luminal coronary artery stenosis in vessels other than the left main were classified to have non-obstructive CAD while patients without any plaque were considered to have normal CTA. Patients were followed up for a median duration of 3.4 years for all-cause mortality (ACM). Multivariable Cox models were used to determine the independent predictors of event-free survival.

Results

A total of 1455 subjects had non-obstructive CAD and 1382 subjects had normal coronary arteries. Subjects with non-obstructive CAD were older (55.9±11 vs 46.2±11 years, p<0.001) and more likely to be males (56.8% vs 50.5%, p=0.001) and had more prevalent traditional risk factors. A total of 83 ACM were observed (4.4% in the non-obstructive group and 1.3% in the normal group, p<0.001). Patients with clinical events were older (61.8±14 vs 50.9±12 years, p<0.001) and have more prevalence of DM (42.2% vs 31.4%, p=0.031) and HTN (72.3% vs 54.3%, p=0.001). In Multivariable Cox models, non-obstructive CAD was associated with increased event rate (Hazard ratio 1.75, 95% CI 1.01–3.01, p=0.45).

Kaplan-Meier Survival Curves

Conclusions

Patients with non-obstructive CAD on CTA have a higher rate of all-cause mortality. Non-obstructive CAD on CTA enhances risk stratification among subjects suspected with CAD and should call for more aggressive guidelines directed medical therapy.

Acknowledgement/Funding

None

Development of Secondary Choroidal Neovascularization in Focal Choroidal Excavation of Punctate Inner Choroidopathy

Purpose: To elaborate a case of focal choroidal excavation (FCE) in punctate inner choroidopathy (PIC) complicated by secondary choroidal neovascularization (CNV) based on multimodal imaging findings.Methods: In this retrospective case report, multimodal imaging including near-infrared reflectance, blue peak autofluorescence, spectral domain-optical coherence tomography (OCT), fluorescein and indocyanine green angiography (Heidelberg Engineering GmbH, Germany), and swept source-OCT angiography (SS-OCTA; Topcon Corporation, Japan) was performed.Patients: A 27-year-old moderate myopic woman presented with inactive CNV of unknown origin in her left eye, which had been previously treated with intravitreal anti-vascular endothelial growth factor.Results: Multimodal imaging revealed PIC as the causative disease and systemic corticosteroids were administered. Similar complaints 13 months later showed new CNV formation at the already documented FCE. No sign of PIC could be detected at follow-up.Conclusion: This well-documented case highlighted FCE as the preferential location for CNV development in PIC with multimodal imaging emphasizing a chorioretinal entity.Summary: This case report demonstrated the clinical course of focal choroidal excavation in a patient initially diagnosed with punctate inner choroidopathy complicated by choroidal neovascularization and its treatment response, well documented by multimodal imaging including optical coherence tomography angiography.