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HOUSTON, May 15, 2017 /PRNewswire/ -- Millar, Inc., is pleased to announce that the University of Chicago Medicine has purchased the CD Leycom® Inca® Pressure-Volume (PV) Loop System – sold in North America exclusively by Millar, Inc. – to improve understanding of the physiology of...


Stehlin E.,University of Auckland | Malpas S.C.,University of Auckland | Malpas S.C.,Millar Inc. | Budgett D.M.,University of Auckland | And 9 more authors.
Journal of Applied Physiology | Year: 2013

Measurements of left ventricular pressure (LVP) in conscious freely moving animals are uncommon, yet could offer considerable opportunity for understanding cardiovascular disease progression and treatment. The aim of this study was to develop surgical methods and validate the measurements of a new high-fidelity, solid-state pressure-sensor telemetry device for chronically measuring LVP and dP/dt in rats. The pressure-sensor catheter tip (2-Fr) was inserted into the left ventricular chamber through the apex of the heart, and the telemeter body was implanted in the abdomen. Data were measured up to 85 days after implant. The average daytime dP/dt max was 9,444 ± 363 mmHg/s, ranging from 7,870 to 10,558 mmHg/s (n = 7). A circadian variation in dP/dt max and heart rate (HR) was observed with an average increase during the night phase in dP/dt max of 918 ± 84 mmHg/s, and in HR of 38 ± 3 bpm. The β-adrenergic- agonist isoproterenol, β1-adrenergic agonist dobutamine, Ca 2+ channel blocker verapamil, and the calcium sensitizer levosimendan were administered throughout the implant period, inducing dose-dependent time course changes and absolute changes in dP/dt max of-6,000 to +13,000 mmHg/s. The surgical methods and new technologies demonstrated long-term stability, sensitivity to circadian variation, and the ability to measure large drug-induced changes, validating this new solution for chronic measurement of LVP in conscious rats. Copyright © 2013 the American Physiological Society.


Stehlin E.F.,University of Auckland | McCormick D.,University of Auckland | McCormick D.,Millar Inc. | Malpas S.C.,University of Auckland | And 5 more authors.
Journal of Magnetic Resonance Imaging | Year: 2015

Purpose To investigate the potential patient risk and interactions between a prototype implantable pressure monitoring device and a 3T clinical magnetic resonance imaging (MRI) machine to guide device design towards MR Conditional safety approval. Materials and Methods The pressure monitor device contained a catheter-mounted piezo-resistive pressure sensor, rechargeable battery, wireless communication system, and inductive pickup coil. Standard testing methods were used to guide experiments to investigate static field induced force and torque, radiofrequency (RF)-induced heating, image artifacts, and the MR?s effect on device function. The specific clinical application of intracranial pressure monitoring was considered. RF-induced heating experiments were supported by numerical modeling of the RF body coil, the device, and experimental phantom. Results Sensing catheter lead length and configuration was an important component of the device design. A short 150 mm length catheter produced a heating effect of less than 2°C and a long 420 mm length catheter caused heating of 7.2°C. Static magnetic field interactions were below standard safety risk levels and the MR did not interfere with device function; however, artifacts have the potential to interfere with image quality. Conclusion Investigation of MR interactions at the prototype stage provides useful implantable device design guidance and confidence that an implantable pressure monitor may be able to achieve MR Conditional safety approval. © 2015 Wiley Periodicals, Inc.


Clark T.M.,University of Auckland | Clark T.M.,Millar Inc. | Malpas S.C.,University of Auckland | McCormick D.,University of Auckland | And 2 more authors.
IEEE Sensors Journal | Year: 2015

Hydrocephalus is the single most common pediatric neurosurgical problem worldwide. Current treatment of this life-threatening disorder involves diverting excess fluid from the ventricles of the brain via a prosthetic shunt. While many hydrocephalus sufferers rely heavily on their ventriculo-distal shunt to maintain a healthy intracranial pressure, shunts carry a high risk of failure. Current methods of assessing shunt patency are performed within the hospital, and many patients and their families feel bound to remaining within close proximity of a hospital in order to receive timely medical intervention in the event of a shunt failure. There is a need for a system which can detect shunt malfunction, simply and reliably. We present a novel method of obtaining flow measurements from a piezoresistive pressure transducer. This builds on an earlier development of obtaining simultaneous temperature and pressure measurement from the single ultra-miniature solid-state transducer. The flow measurement system is capable of measurements in the range 0-35 ml/h, typical of the fluid flow rates through a hydrocephalus shunt. Within the flow range 0-14 ml/hour the resolution is 2 ml/hour. For flow rates greater than 16 ml/hour the resolution is 5 ml/hour. Employing a thermal flow sensing technique, the maximum heating of the local fluid is 0.65 ± 0.02 °C. The flow signal is independent of ambient temperature. The sensor would be implanted in the shunt to allow the detection of the flow rate of fluid through it, enabling the clinician to measure the patency of a shunt in real time. © 2015 IEEE.


Guild S.-J.,University of Auckland | Guild S.-J.,Millar Ltd | McBryde F.D.,University of Auckland | Malpas S.C.,University of Auckland | Malpas S.C.,Millar Ltd
Journal of Applied Physiology | Year: 2015

cerebral perfusion pressure (CPP) is known to be fundamental in the control of normal brain function, there have been no previous long-term measurements in animal models. The aim of this study was to explore the stability and viability of long-term recordings of intracranial pressure (ICP) in freely moving rats via a telemetry device. We also developed a repeatable surgical approach with a solid-state pressure sensor at the tip of the catheter placed under the dura and in combination with arterial pressure (AP) measurement to enable the calculation of CPP. Telemeters with dual pressure catheters were implanted in Wistar rats to measure ICP and AP. We found that the signals were stable throughout the 28-day recording period with an average ICP value of 6 ±0.8 mmHg. Significant light-dark differences were found in AP (3.1 ±2.7 mmHg, P = 0.02) and HR (58 ± 2 beats/min, P = 0.003), but not ICP (0.3 ± 0.2 mmHg, P =0.05) or CPP (2.6 ± 2.8 mmHg, P ± 0.05). Use of kaolin to induce hydrocephalus in several rats demonstrates the ability to measure changes in ICP throughout disease progression, validating this new solution for chronic measurement of ICP, CPP, and AP in conscious rats. © 2015 the American Physiological Society.


Clark T.M.,University of Auckland | Malpas S.C.,University of Auckland | Malpas S.C.,Millar Ltd | McCormick D.,University of Auckland | And 5 more authors.
Biomedical Microdevices | Year: 2015

Recent advances in multimodal sensing technology and sensor miniaturization technologies are paving the way for a new era in physiological measurement. Traditional approaches have integrated several transducers on a single silicon chip or packaged several sensing elements within a biocompatible catheter. Thermal and electrical cross-talk between sensors, time-lag between parallel measurements, lower yields associated with the increased complexity, and restrictions on the minimum size are challenges presented by these approaches. We present an alternative method which enables simultaneous measurement of temperature, pressure and heart rate to be obtained from a single ultra-miniature solid-state transducer. For the first time multimodal data were obtained from the sensor located within the abdominal aortas of five rats. The catheter-tip sensor interfaces with a fully implanted and inductively powered telemetry device capable of operating for the lifetime of the animal. Results of this study demonstrate good agreement between the core-temperature measurement from the catheter-tip sensor and the reference sensor with mean difference between the two sensors of 0.03 °C± 0.02 °C (n=5, 7 days). Real-time data obtained in the undisturbed rat, revealed fluctuations associated with the restactivity cycle, in temperature, mean arterial pressure and heart rate. The stress response was shown to elicit an elevation in the core temperature of 1.5 °C. This was heralded by an elevation in mean arterial pressure of 35 mmHg and heart rate of 160 bpm. Obtaining multiple parameters from a single transducer goes a considerable way towards overcoming challenges of the prior art. © Springer Science+Business Media New York 2015.


A method for determining a value of a parameter of an object or an environment includes positioning a device having a balanced circuit in or on an object or within a particular environment, wherein the balanced circuit comprises elements which are operationally sensitive to changes in a parameter of the object or the environment. The method further includes measuring a common mode signal of the balanced circuit and determining, from the common mode signal, a value of the parameter. An exemplary implementation of the method includes determining temperature using a resistive sensor having a Wheatstone bridge circuit with two variable resistors and two fixed resistors. Embodiments of systems and devices configured to employ such methods are provided, particularly medical probes, electronic signal monitoring devices, and systems employing such devices.


Grant
Agency: Department of Health and Human Services | Branch: National Institutes of Health | Program: SBIR | Phase: Phase I | Award Amount: 149.50K | Year: 2016

Heart failure affects over million people in the US alone Every year new cases are diagnosed with a cost approaching $ billion For million of these patients US drugs can no longer control the problem and mechanical support for blood flow is the most accessible treatment However heart pumps need power and percutaneous leads used today remain a significant cause of adverse events We propose eliminating the percutanous lead by using wireless power transfer Millar Houston TX has develped the technology US to receive electrical power from a coil inside the body from a magnetic field generated from a coil located outside the body Our research aim is to show how the merging of the wireless power technology with the Procyrion Houston TX Aortix heart pump can eliminate the risk of percutaneous driveline infections We will measure the heat generated by the wireless power system when delivering W of power over a variable distance of up to mm separation between external and implanted coils This power level is adequate for full pump operation and recharging an internal short term battery Our long term goal is make the Aortix the preferred treatment option for stage III HF patientsHeart failure HF leads to poor renal perfusion resulting in fluid overload edema and difficulty breathing cardio renal syndrome Millar and Procyrion are developing a fully implantable long term mechanical circulatory support device with the pump located in the descending aorta to treat a large population of HF patients


HOUSTON, Nov. 16, 2016 /PRNewswire/ -- Millar, Inc., a leader in technology that enables scientific discovery and increased medical understanding, today announced it has signed a distribution agreement with Taisho Biomed Instruments Co., Ltd. to market and sell the Millar Mikro-CathTM...

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