Aaron M. Kyle

LifeShirt ® acquisition system to monitor ECG from ambulatory swine and the implementation of an arrhythmia detection algorithm

A wearable cardiopulmonary monitoring system, a LifeShirt®, was used to acquire continuous electrocardiograms (ECGs) from ambulatory swine. The animals received intracoronary injections of autologous mesenchymal stem cells, and the LifeShirt® was used for long-duration ECG monitoring in pre-defined periods post cell infusion. The system used here was developed for measurements from non-human primates and canines; however, we demonstrated that it could be used to non-invasively measure ECGs from swine without creating undue stress or restricting movement. A MATLAB-based analysis algorithm was developed to automatically detect premature ventricular contractions (PVCs) that arose 8-10 hours after cell delivery with spontaneous resolution 2-3 days post-infusion. Template based cross-correlation was used to detect the PVCs and identify regions of consecutive ventricular rhythm. The final algorithm was highly specific and sensitive when tested on records from the MIT-BIH arrhythmia database. The algorithm was subsequently used to automatically identify and quantify PVCs from over 200 hours of ECG data obtained from nine ambulatory swine.

Intravenous xenogeneic transplantation of human adipose-derived stem cells improves left ventricular function and microvascular integrity in swine myocardial infarction model

The potential for beneficial effects of adipose‐derived stem cells (ASCs) on myocardial perfusion and left ventricular dysfunction in myocardial ischemia (MI) has not been tested following intravenous delivery.

Field-testing of a novel color indicator added to chlorine solutions used for decontamination of surfaces in Ebola Treatment Units

Disinfection with chlorine solution was used in West Africa to prevent transmission of Ebola virus disease. This study surveyed 94 healthcare personnel and community leaders in Liberia and Guinea to assess understanding of disinfection and evaluate feedback on the perceived usefulness of Highlight, a new colour indicator designed to improve chlorine disinfection procedures. Using a Likert-type scale questionnaire, respondents agreed or strongly agreed (P<0.0001) that Highlight improved coverage of chlorine solution and feelings of confidence.

Bioinstrumentation: A Project-Based Engineering Course

This paper presents the development, implementation, and assessment of a project-based Bioinstrumentation course. All course lectures and hands-on laboratory activities are related to a central project theme: a cardiac pacemaker. The students create a benchtop cardiac pacemaker by applying instrumentation knowledge acquired in the course to each stage of device development. This approach emphasizes both conceptual and practical student learning: The students must apply theory learned in the course to create their devices. Indirect and direct assessment performed with respect to the major course objective demonstrated that course participants were able to successfully design, construct, and test a bioinstrumentation system. The students perceived a marked increase in their instrumentation knowledge, objectively corroborated by their performance on specific exercises related to the creation of their benchtop pacemakers. The outcomes of the course development presented here, along with the course structure and pedagogical methodology, may enhance engineering education by acting as a guideline for the creation of courses in which a central project theme is used as a platform for concept instruction.

Novel color additive for chlorine disinfectants corrects deficiencies in spray surface coverage and wet-contact time and checks for correct chlorine concentration

&NA; Bleach sprays suffer from poor surface coverage, dry out before reaching proper contact time, and can be inadvertently over‐diluted to ineffective concentrations. Highlight®, a novel color additive for bleach that fades to indicate elapsed contact time, maintained >99.9% surface coverage over full contact time and checked for correct chlorine concentration.

Computer Simulation Tool for Predicting Sound Propagation in Air-Filled Tubes with Acoustic Impedance Discontinuities

A computer tool, based on an acoustic transmission line model, was developed for modeling and predicting sound propagation and reflections in cascaded tube segments. This subroutine considered the number of interconnected tubes, their dimensions and wall properties, as well as medium properties to create a network of cascaded transmission line model segments, from which the impulse response of the network was estimated. Acoustic propagation was examined in air-filled cascaded tube networks and model predictions were compared to measured acoustic pulse responses. The model was able to accurately predict the location and morphology of reflections. The developed code proved to be a useful design tool for applications such as the guidance of catheters through compliant air-filled biological conduits.

Potential of gallium-based leads for cardiac rhythm management devices

We propose the use of gallium (Ga), a metal that is liquid at physiological temperatures, or one of its alloys, for use as the conducting material in the leads of implantable pacemakers or cardioverter defibrillators. It is proposed that a liquid conductor will make these leads more pliable and thus less susceptible to fracture in situ. As an initial step towards utilizing liquid gallium in leads, the biocompatibility of Ga was investigated via cytotoxicity, hemocompatibility, and intracutaneous injection testing. Unipolar pacing Ga prototypes were fabricated by adapting existing pacemaker leads. The electrical impedance and pulse transmission ability of these leads were examined. Ga was well tolerated both in vitro and in vivo. Additionally, the Ga prototypes conductors behaved as low magnitude resistances that did not distort pulses as generated by conventional pacemakers. These results indicate that Ga is an appropriate material for implantable cardiac stimulators and will be a focus of our liquid metal prototypes.

Wave propagation in liquid‐filled tubes: Measurements and model predictions

Wave propagation in liquid‐filled pipes was investigated using time‐ and frequency‐domain techniques. Water‐ and ethanol‐filled copper and PVC pipes having inner diameters of 1.44 and 1.19 cm, and wall thicknesses of 0.0686 and 0.208 cm, respectively, were driven with tone bursts from a submerged hydrophone, and the resultant acoustic pressures in the liquid were measured. Group velocities in the copper pipe were observed to decrease with increasing frequency: velocities were 1124 m/s at 10 kHz and 1039 m/s at 50 kHz in water and 1052 m/s at 10 kHz and 902 m/s at 40 kHz in ethanol. Propagation in the PVC pipe was significantly slower, e.g., the estimated water group velocity at 10 kHz was 593 m/s. The estimated group velocities were then compared to those predicted by an acoustic transmission line model of the pipes. The predicted group velocities were within 13% of the estimated values for the copper tube for both liquids. The pipe systems were also excited with Gaussian noise, and exhibited bands of low...