RESEARCH: Novel therapeutic strategy against central baroreflex failure: a bionic baroreflex system

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Circulation 1999 Jul 20;100(3):299-304

Novel therapeutic strategy against central baroreflex failure: a bionic

baroreflex system.

Sato T, Kawada T, Shishido T, Sugimachi M, J Jr, Sunagawa K.

Department of Cardiovascular Dynamics, National Cardiovascular Center

Research Institute, Osaka, Japan. tacsato@...

BACKGROUND: Central baroreflex failure in Shy-Drager syndrome and traumatic

spinal cord injuries results in severe orthostatic hypotension and often

confines the patient to the bed. We proposed a novel therapeutic strategy

against central baroreflex failure: implementation of an artificial feedback

control system able automatically to regulate sympathetic vasomotor tone,

that is, a bionic baroreflex system (BBS). With the use of a rat model of

central baroreflex failure, we developed the BBS and tested its efficacy.

METHODS AND RESULTS: Our prototype BBS for the rat consisted of a pressure

sensor placed into the aortic arch, stimulation electrodes implanted into

the greater splanchnic nerve, and a computer-driven neural stimulator. By a

white noise approach for system identification, we first estimated the

dynamic properties underlying the normal baroreflex control of systemic

arterial pressure (SAP) and then determined how the BBS computer should

operate in real time as the artificial vasomotor center to mimic the dynamic

properties of the native baroreflex. The open-loop transfer function of the

artificial vasomotor center was identified as a high-pass filter with a

corner frequency of 0.1 Hz. We evaluated the performance of the BBS in

response to rapid-progressive hypotension secondary to sudden sympathetic

withdrawal evoked by the local imposition of a pressure step on carotid

sinus baroreceptors in 16 anesthetized rats. Without the BBS, SAP rapidly

fell by 49+/-8 mm Hg in 10 seconds. With the BBS placed on-line with

real-time execution, the SAP fall was suppressed by 22+/-6 mm Hg at the

nadir and by 16+/-5 mm Hg at the plateau. These effects were statistically

indistinguishable from those of the native baroreflex system. CONCLUSIONS:

These results suggest the feasibility of a BBS approach for central

baroreflex failure.

PMID: 10411856 [PubMed - indexed for MEDLINE]