Sinusoidal neck suction at 0.1 Hz increased low-frequency RR interval fluctuations in heart transplant recipients (from 0.73 to 1.30 ln ms2, P<0.001), indicating functional sympathetic reinnervation.
Cross-Sectional (n=42)
Does carotid baroreflex modulation by sinusoidal neck suction demonstrate cardiac reinnervation in heart transplant recipients?
Carotid baroreflex modulation demonstrates functional, sympathetic autonomic reinnervation in patients after heart transplantation.
p-value: p=<0.001
BACKGROUND: After heart transplantation, respiration-synchronous fluctuations (0.18 to 0.35 Hz, high frequency HF) in RR interval may result from atrial stretch caused by changes in venous return, but slower fluctuations (0.03 to 0.15 Hz, low frequency LF) not due to respiration suggest reinnervation. In normal subjects, sinusoidal neck suction selectively stimulates carotid baroreceptors and causes reflex oscillations of RR interval. METHODS AND RESULTS: To evaluate the presence of reinnervation, we measured the power of RR-LF and RR-HF in 26 heart transplant recipients and 16 control subjects before and during sinusoidal neck suction at 0.1 Hz and 0.20 Hz (similar to but distinct from that of controlled respiration, 0.25 Hz) and before and during administration of atropine or beta-blocker (esmolol hydrochloride) by spectral analysis. All transplant recipients showed small respiratory HF fluctuations. Nonrespiratory LF fluctuations were present in 13 of 26 transplant recipients and increased with months since transplantation (r = .53, P < .01). HF neck suction induced a 0.20-Hz component in all 16 control subjects and none of the 26 transplant subjects. LF neck suction increased RR-LF (from 0.73 +/- 0.20 to 1.30 +/- 0.26 ln ms2, P < .001), similar to but less than in control subjects (from 6.12 +/- 0.21 to 8.27 +/- 0.21 ln ms2, P < .001). Atropine reduced all fluctuations in control subjects and blocked the HF increase caused by 0.20-Hz neck suction but not the LF increase during 0.10-Hz stimulation. Neck suction-induced changes in LF fluctuations persisted after administration of atropine in transplant recipients but were attenuated by esmolol hydrochloride, suggesting sympathetic rather than vagal reinnervation. CONCLUSIONS: The presence of baroreceptor-induced RR oscillations is evidence of functional, although incomplete, autonomic reinnervation.
Bernardi et al. (Wed,) conducted a cross-sectional in Heart transplantation (n=42). Sinusoidal neck suction vs. Control subjects and baseline measurements was evaluated on Power of low-frequency (RR-LF) and high-frequency (RR-HF) RR interval fluctuations (p=<0.001). Sinusoidal neck suction at 0.1 Hz increased low-frequency RR interval fluctuations in heart transplant recipients (from 0.73 to 1.30 ln ms2, P<0.001), indicating functional sympathetic reinnervation.