Key result
The baroreflex index decreased with progression of baroreflex dysfunction (control 2.00, partial SAD 1.28, total SAD 0.06; P<0.05) and was linearly correlated with reference gain (R2=0.91, P<0.01).
Why the study?
Baroreflex dysfunction contributes to cardiovascular pathogenesis, but no method exists to evaluate the pressure-stabilizing gain of the baroreflex total loop in a clinical setting.
Does derivation of the baroreflex index (BRI) using power spectral analysis of continuous arterial pressure recordings accurately estimate baroreflex total loop gain in rats with graded baroreflex dysfunction?
Does derivation of the baroreflex index (BRI) using power spectral analysis of continuous arterial pressure recordings accurately estimate baroreflex total loop gain in rats with graded baroreflex dysfunction?
The baroreflex index derived from power spectral analysis of continuous arterial pressure recordings accurately estimates baroreflex total loop gain in a rat model, suggesting potential as a clinical tool.
May enable clinical baroreflex gain assessment; hypothesis-generating pending validation in patient cohorts.
Baroreflex dysfunction contributes to the pathogenesis of cardiovascular diseases. The baroreflex comprises a negative feedback loop to stabilize arterial pressure (AP); its pressure-stabilizing capacity is defined as the gain ( G) of the transfer function ( H) of the baroreflex total loop. However, no method exists to evaluate G in a clinical setting. A feedback system with H attenuates pressure disturbance (PD) to PD/(1 + H). We hypothesized that the baroreflex attenuates the power spectrum density (PSD) of AP in the baroreflex functioning frequency range. We created graded baroreflex dysfunction in rats using a modified sinoaortic denervation (SAD) method [SAD; control (no SAD): n = 9; partial SAD (SAD in the right carotid sinus): n = 6, and total SAD (SAD in the bilateral carotid sinuses): n = 6] and evaluated the PSD of 12-h telemetric AP recordings in the light phase. Using the ratio of PSD at 0.01–0.1 Hz (PSD slope), we normalized them with the PSD in rats with complete baroreflex failure and derived the baroreflex index (BRI), which directly reflects G. We compared BRI and G obtained from a baroreflex open-loop experiment (reference G). The PSD slope became steeper with progression of baroreflex dysfunction. BRI (control: 2.00 ± 0.31, partial SAD: 1.28 ± 0.30, and total SAD: 0.06 ± 0.10, P < 0.05) was linearly correlated with reference G ( R 2 = 0.91, P < 0.01). BRI accurately estimated G of the baroreflex and may serve as a novel tool for estimating the pressure-stabilizing capacity of the baroreflex in clinical settings. NEW & NOTEWORTHY This study proposed a novel method to estimate the gain of the baroreflex total loop, the so-called “baroreflex index” (BRI). BRI focuses on action potential variability in the frequency domain, considering baroreflex low-pass filter characteristics within 0.01–0.1 Hz. We demonstrated that BRI was linearly correlated with the reference gain of baroreflex in rats. Thus, BRI may contribute greatly to the development of a clinical tool for estimating baroreflex pressure-stabilizing capacity.
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Mannoji et al. (2019) studied Baroreflex dysfunction (n=21). Sinoaortic denervation (SAD) vs. Control (no SAD) was evaluated on Baroreflex index (BRI) and its correlation with reference gain (G) (R2 = 0.91, p=<0.01). The baroreflex index decreased with progression of baroreflex dysfunction (control 2.00, partial SAD 1.28, total SAD 0.06; P<0.05) and was linearly correlated with reference gain (R2=0.91, P<0.01).
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