A novel, fully implantable, multichannel biotelemetry system for measurement of blood flow, pressure, ECG, and temperature.

Biotelemetry provides high-quality data in awake, free-ranging animals without the effects of anesthesia and surgery. Although many biological parameters can be measured using biotelemetry, simultaneous telemetric measurements of pressure and flow have not been available. The objective of this study was to evaluate simultaneous measurements of blood flow, pressure, ECG, and temperature in a fully implantable system. This novel system allows the measurement of up to four channels of blood flow, up to three channels of pressure, and a single channel each of ECG and temperature. The system includes a bidirectional radio-frequency link that allows the implant to send data and accept commands to perform various tasks. The system is controlled by a base station decoder/controller that decodes the data stream sent by the implant into analog signals. The system also converts the data into a digital data stream that can be sent via ethernet to a remote computer for storage and/or analysis. The system was chronically implanted in swine and alligators for up to 5 wk. Both bench and in vivo animal tests were performed to evaluate system performance. Results show that this biotelemetry system is capable of long-term accurate monitoring of simultaneous blood flow and pressure. The system allows, within the room, recordings, since the implant transmission range is between 6 and 10 m, and, with a relay, backpack transmission distance of up to 500 m can be achieved. This system will have significant utility in chronic models of cardiovascular physiology and pathology.

[1]  Craig E. Franklin,et al.  Physiology: An actively controlled heart valve , 2000, Nature.

[2]  Craig E. Franklin,et al.  From anatomy to angioscopy: 164 years of crocodilian cardiovascular research, recent advances, and speculations , 1997 .

[3]  R. L. Citters,et al.  Blood Velocity telemetered from Untethered Animals , 1964, Nature.

[4]  G. Shelton,et al.  THE PHYSIOLOGY OF THE ALLIGATOR HEART: THE CARDIAC CYCLE , 1991 .

[5]  T. Nakayama,et al.  Radio telemetry directional ultrasonic blood flowmeter for use with unrestrained animals , 1992, Medical and Biological Engineering and Computing.

[6]  M Axelsson,et al.  Gut blood flow in the estuarine crocodile, Crocodylus porosus. , 1991, Acta physiologica Scandinavica.

[7]  G. Shelton,et al.  The physiology of the alligator heart: left aortic flow patterns and right-to-left shunts , 1993 .

[8]  J W Knutti,et al.  Totally implantable directional Doppler flowmeters. , 1979, Biotelemetry and patient monitoring.

[9]  M Siebes,et al.  Role of Variability in Microvascular Resistance on Fractional Flow Reserve and Coronary Blood Flow Velocity Reserve in Intermediate Coronary Lesions , 2001, Circulation.

[10]  T B Fryer,et al.  A multichannel implantable telemetry system for flow, pressure, and ECG measurements. , 1975, Journal of applied physiology.

[11]  J Jossinet,et al.  Detailed description of an implantable directional Doppler flowmeter. , 1976, Biotelemetry.

[12]  R D Rader,et al.  An implantable blood pressure and flow transmitter. , 1973, IEEE transactions on bio-medical engineering.

[13]  Douglas A Syme,et al.  Delayed depolarization of the cog-wheel valve and pulmonary-to-systemic shunting in alligators. , 2002, The Journal of experimental biology.

[14]  Y Yonezawa,et al.  A miniaturized ultrasonic flowmeter and telemetry transmitter for chronic animal blood flow measurements. , 1989, Biomedical sciences instrumentation.

[15]  J L Fuller,et al.  The Radio Inductograph--A Device for Recording Physiological Activity in Unrestrained Animals. , 1948, Science.

[16]  S. R. Winters.  Diagnosis by Wireless , 1921 .

[17]  K Matre,et al.  Comparison of transit-time and Doppler ultrasound methods for measurement of flow in aortocoronary bypass grafts during cardiac surgery. , 1994, The Thoracic and cardiovascular surgeon.

[18]  Gordon C. Grigg,et al.  At the Crocodilian Heart of the Matter , 2000, Science.

[19]  J. Hicks,et al.  Characterization and cardiovascular actions of endothelin-1 and endothelin-3 from the American alligator. , 2002, American journal of physiology. Regulatory, integrative and comparative physiology.

[20]  W. Einthoven,et al.  Die galvanometrische Registrirung des menschlichen Elektrokardiogramms, zugleich eine Beurtheilung der Anwendung des Capillar-Elektrometers in der Physiologie , 1903, Archiv für die gesamte Physiologie des Menschen und der Tiere.

[21]  J.J. Cupal,et al.  A system to acquire and record physiological and behavioral data remotely from nonhuman primates , 1991, IEEE Transactions on Biomedical Engineering.

[22]  E R Greene,et al.  Central vascular flow patterns in the alligator Alligator mississipiensis. , 1995, The American journal of physiology.

[23]  M Axelsson,et al.  Flow dynamics of the crocodilian heart. , 1989, The American journal of physiology.

[24]  Patrick J Butler,et al.  Biotelemetry: a mechanistic approach to ecology. , 2004, Trends in ecology & evolution.

[25]  James D. Meindl,et al.  Integrated circuits for a bidirectional implantable pulsed Doppler ultrasonic blood flowmeter , 1978 .

[26]  D. R. Jones,et al.  Crocodilian Cardiac Dynamics: A Half-Hearted Attempt , 1995, Physiological Zoology.