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Identification of open‐loop baroreflex gain from continuous arterial pressure monitoring
Author(s) -
Mannoji Hiroshi,
Saku Keita,
Nishikawa Takuya,
Tohyama Takeshi,
Oga Yasuhiro,
Abe Kiyokazu,
Kishi Takuya,
Tsutsui Hiroyuki,
Sunagawa Kenji
Publication year - 2017
Publication title -
the faseb journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.709
H-Index - 277
eISSN - 1530-6860
pISSN - 0892-6638
DOI - 10.1096/fasebj.31.1_supplement.848.11
Subject(s) - baroreflex , baroreceptor , denervation , medicine , blood pressure , anesthesia , cardiology , heart rate
Background Although the importance of arterial baroreflex function in cardiovascular disease is well established, the lack of practical methods to identify the open‐loop baroreflex transfer function (H) makes it difficult to serve as a clinical tool. We repeatedly demonstrated that the H approximates a first‐order low pass filter with the corner frequency of 0.05 Hz in rats. In theory, a feedback system with H attenuates disturbance (D) to D/(1+H). We hypothesized that the baroreflex attenuates the power spectrum density (PSD) of arterial pressure (AP) in its operating frequency range (<0.1Hz), thereby H can be identified from the attenuation of PSD as long as D remains unchanged irrespective of baroreflex function. Methods We used 9 Wister‐Kyoto rats. We created graded baroreflex dysfunction by sinoaortic denervation (SAD) (partial: denervation only in right side, n=3 and total: bilateral denervation). One week after SAD, we calculated PSD from continuous AP recording (telemetry, 12hours). To estimate the baroreflex gain, we took the ratio of PSD at 2 frequencies (0.01 Hz/0.1 Hz) and normalized the value by PSD of total SAD. At the end of each experiment, we isolated baroreceptors and measured the open‐loop baroreflex gain. Results Partial SAD increased the lability (standard deviation of AP), and total SAD increased more (sham: 6.41 ± 0.79, partial SAD: 9.16 ± 0.58, total SAD: 20.1 ± 5.00 mmHg, p<0.001). SAD increased PSD below 0.1Hz, whereas did not affect above 0.1 Hz indicating that D remains unchanged regardless of SAD ( Fig. 1). Estimated open loop baroreflex gain linearly correlated with that experimentally determined (y = 0.24x + 0.11, R 2 = 0.87) ( Fig. 2). Conclusion Power spectrum anaysis of AP time series allows us to identify broreflex function. The proposed framework may faclitate the noninvasive estimation of baroreflex function in clinial setting.