A Contactless Sensor for Pacemaker Pulse Detection: Design Hints and Performance Assessment

A smart approach to EMG envelope extraction and powerful denoising for human-machine interfaces

Electromyography (EMG) is widely used in human-machine interfaces (HMIs) to measure muscle contraction by computing the EMG envelope. However, EMG is largely affected by powerline interference and motion artifacts. Boards that directly provide EMG envelope, without denoising the raw signal, are often unreliable and hinder HMIs performance. Sophisticated filtering provides high performance but is not viable when power and computational resources must be optimized. This study investigates the application of feed-forward comb (FFC) filters to remove both powerline interferences and motion artifacts from raw EMG. FFC filter and EMG envelope extractor can be implemented without computing any multiplication. This approach is particularly suitable for very low-cost, low-power platforms. The performance of the FFC filter was first demonstrated offline by corrupting clean EMG signals with powerline noise and motion artifacts. The correlation coefficients of the filtered signals envelopes and the true envelopes were greater than 0.98 and 0.94 for EMG corrupted by powerline noise and motion artifacts, respectively. Further tests on real, highly noisy EMG signals confirmed these achievements. Finally, the real-time operation of the proposed approach was successfully tested by implementation on a simple Arduino Uno board.

Comparation of quality of life in Chinese patients undergoing leadless versus conventional pacemaker implantation

BACKGROUND

Leadless pacemakers are widely used, but the quality of life assessment of patients with leadless pacemakers is still unclear.

HYPOTHESIS

Assume that leadless pacemakers can improve the patients' quality of life.

METHODS

Total of 119 patients who received pacemaker implantation at Beijing Anzhen Hospital from January 2020 to March 2022 were selected, including 35 leadless pacemakers and 84 conventional pacemakers. The SF-36 questionnaire was used to evaluate quality of life at baseline, 1 month and 3 months after surgery. We also used a questionnaire consisted of 4 specific questions related to the implant procedure to assess the surgery.

RESULTS

There were no differences in baseline characteristics between the two groups, except for age and oral anticoagulant treatment. There was no difference in baseline SF-36 scores. At the 3-month follow-up, patients in leadless pacemakers group were significantly better at physical function (63.63 vs 47.50, p = .000), role physical (60.20 vs 40.23, p = .000), bodily pain (65.57 vs. 61.69, p = .042), physical component summary (61.25 vs. 50.57, p = .000), vitality (56.26 vs 49.57, p = .001), social function (80.14 vs 74.70, p = .004), role emotional (76.14 vs. 71.42, p = .015), mental health (75.46 vs. 68.18, p = .000), mental component summary (72.00 vs. 65.97, p = .000), even after adjusting for clinical baseline and SF-36 baseline. Pacemaker-related discomfort and mobility limitations were significantly reduced in leadless pacemakers group.

CONCLUSIONS

Leadless pacemakers is associated with better quality of life with less activity limitations due to surgical discomfort and less emotional distress. However, current use of leadless pacemakers in China is limited due to the high cost.

Contactless Electrocatheter Tracing within Human Body via Magnetic Sensing: A Feasibility Study

During surgical procedures, real-time estimation of the current position of a metal lead within the patient's body is obtained by radiographic imaging. The inherent opacity of metal objects allows their visualization using X-ray fluoroscopic devices. Although fluoroscopy uses reduced radiation intensities, the overall X-ray dose delivered during prolonged exposure times poses risks to the safety of patients and physicians. This study proposes a potential alternative to real-time visualization of a lead inside the human body. In principle, by making a weak current flow through the lead and measuring the related magnetic field generated outside the body, it is possible to trace the position of the lead. This hypothesis was verified experimentally via two tests: one carried out on a curved copper wire in air and one carried out on a real pacemaker lead in a saline solution. In the second test, a pacemaker lead and a large return electrode were placed in a tank filled with a saline solution that reproduced the mean resistivity of the human torso. In both tests, a current flowed through the lead, which consisted of square pulses with short duration, to avoid any neuro-muscular stimulation effects in a real scenario. A small coil with a ferrite core was moved along a grid of points over a plastic sheet and placed just above the lead to sample the spatial amplitude distribution of the magnetic induction field produced by the lead. For each measurement point, the main coil axis was oriented along the x and y axes of the plane to estimate the related components of the magnetic induction field. The two matrices of measurements along the x and y axes were further processed to obtain an estimate of lead positioning. The preliminary results of this study support the scientific hypothesis since the positions of the leads were accurately estimated. This encourages to deepen the investigation and overcome some limitations of this feasibility study.

Effectiveness and Safety in Remote Monitoring of Patients with Pacemakers Five Years after an Implant: The Poniente Study

Health-related quality of life (HRQoL) and functional capacity values immediately after pacemaker (PM) implantation have been well established; however, not much has been known about its long-term effects. The present study compared the long-term effectiveness and safety of remote monitoring plus a clinic visit versus clinic visits alone during follow-up of adults implanted with PMs. This study was a single-centre, controlled, non-randomised, non-blinded clinical trial. Data were collected pre-implantation and after 60 months. The patients in the PONIENTE study were assigned to two different groups: remote monitoring (RM) and conventional monitoring (CM). The EuroQol-5D (EQ-5D) questionnaire was used to assess HRQoL and Duke Activity Status Index was used for the functional capacity. After five years, 55 patients completed the study (RM = 21; CM = 34). EuroQol-5D and functional capacity values were improved; however, significant differences were observed only in the EQ5D visual analogue scale (p < 0.001). Remote monitoring was equally feasible, reliable, safe, and clinically useful as CM. The frequencies of rehospitalisations and emergency visits did not differ between the groups. RM was found to be safe and effective in early detection and treatment of medical- and device-related events and in reducing hospital visits. Improved HRQoL was described not only immediately after PM implantation but also extended over a long time.

Wearable Device to Monitor Back Movements Using an Inductive Textile Sensor

Low back pain (LBP) is the most common work-related musculoskeletal disorder among healthcare workers and is directly related to long hours of working in twisted/bent postures or with awkward trunk movements. It has already been established that providing relevant feedback helps individuals to maintain better body posture during the activities of daily living. With the goal of preventing LBP through objective monitoring of back posture, this paper proposes a wireless, comfortable, and compact textile-based wearable platform to track trunk movements when the user bends forward. The smart garment developed for this purpose was prototyped with an inductive sensor formed by sewing a copper wire into an elastic fabric in a zigzag pattern. The results of an extensive simulation study showed that this unique design increases the inductance value of the sensor, and, consequently, improves its resolution. Furthermore, experimental evaluation on a healthy participant confirmed that the proposed wearable system with the suggested sensor design can easily detect forward bending movements. The evaluation scenario was then extended to also include twisting and lateral bending of the trunk, and it was observed that the proposed design can successfully discriminate such movements from forward bending of the trunk. Results of the magnetic interference test showed that, most notably, moving a cellphone towards the unworn prototype affects sensor readings, however, manipulating a cellphone, when wearing the prototype, did not affect the capability of the sensor in detecting forward bends. The proposed platform is a promising step toward developing wearable systems to monitor back posture in order to prevent or treat LBP.

A Modified Wireless Power Transfer System for Medical Implants

Wireless Power Transfer (WPT) is a promising technique, yet still an experimental solution, to replace batteries in existing implants and overcome the related health complications. However, not all techniques are adequate to meet the safety requirements of medical implants for patients. Ensuring a compromise between a small form factor and a high Power Transfer Efficiency (PTE) for transcutaneous applications still remains a challenge. In this work, we have used a resonant inductive coupling for WPT and a coil geometry optimization approach to address constraints related to maintaining a small form factor and the efficiency of power transfer. Thus, we propose a WPT system for medical implants operating at 13.56 MHz using high-efficiency Complementary Metal Oxide-Semiconductor (CMOS) components and an optimized Printed Circuit Coil (PCC). It is divided into two main circuits, a transmitter circuit located outside the human body and a receiver circuit implanted inside the body. The transmitter circuit was designed with an oscillator, driver and a Class-E power amplifier. Experimental results acquired in the air medium show that the proposed system reaches a power transfer efficiency of 75.1% for 0.5 cm and reaches 5 cm as a maximum transfer distance for 10.67% of the efficiency, all of which holds promise for implementing WPT for medical implants that don’t require further medical intervention, and without taking up a lot of space.