No abstract available.
Baroreflex* ; Cyclosporine* ; Rabbits*

Heart failure (HF) is the endstage of multiple cardiovascular diseases.Impaired autonomic regulation and sympathetic-parasympathetic imbalance are considered key factors in HF progression.Baroreflex activation therapy (BAT),a novel device-based therapy which stimulates the carotid sinuses and regulates autonomic function,has demonstrated good efficacy in treating HF and improving prognosis.This review summarized the results of the latest relevant studies to provide support for further study of BAT.
Baroreflex/physiology* ; Heart Failure/therapy* ; Humans

Graded infusion and bolus injection methods of vasoactive drugs have both been used to measure baroreflex sensitivity. To determine whether the two methods produce the same values of baroreceptor sensitivity, phenylephrine and nitroglycerin was administered intravenously by both graded infusion and bolus injection methods to 11 rabbits. To evaluate the baroreflex control of heart rate(HR), a logistic sigmoid function model was used. The range of HR and baroreflex gain by the bolus method(100.53+/-0.62, 0.113+/-0.011) were significantly(p<0.05) larger than those measured by the graded infusion method(108.49+/-1.66, 0.126+/-0.013). However, there were no significant changes in the pressure at the midrange of the baroreflex curve. Thus my results indicate that baroreflex control of HR by the graded infusion and bolus injection methods is not equivalent and that baroreflex-induced HR response to a gradual change in pressure is less than that seen with a repid change.
Baroreflex* ; Colon, Sigmoid ; Heart ; Heart Rate ; Nitroglycerin ; Phenylephrine ; Pressoreceptors ; Rabbits*

BACKGROUND: The sequence method of determining baroreflex sensitivity (BRSSEQ) has been reported to correlate poorly with the phenylephrine method of determining BRS in individuals with attenuated BRS. Inhalation anesthetics are also known to decrease BRS. We therefore assessed the effect of varying the systolic blood pressure (SBP) and R-R interval (RRI) thresholds on BRSSEQ values and compared these results with the BRS obtained by the modified Oxford technique (BRSMODOX). METHODS: The average number of valid sequences and BRSSEQ values were derived by varying the SBP threshold from 0.5 to 2.5 mmHg and the RRI threshold from 1 to 6 ms, and the relation of BRSSEQ values to BRSMODOX values using sequential administration of nitroprusside and phenylephrine was assessed in 40 healthy individuals during sevoflurane anesthesia. RESULTS: Increasing either the SBP thresholds or RRI thresholds resulted in a decrease in the number of valid sequences. As the SBP thresholds were decreased and the RRI thresholds were increased, BRSSEQ values increased. When the SBP threshold exceeded 1 mmHg, no significant correlations were observed between BRSSEQ and BRSMODOX values. Significant correlations between the two methods were observed for an SBP threshold of 0.5 mmHg and RRI thresholds of 1, 2, 3 and 4 ms. Biases between the two methods were 2.1, 2.1, 0.4, and 0.4 ms/mmHg for 0.5 mmHg and 1, 2, 3 and 4 ms. CONCLUSIONS: These findings suggest that adjusting the SBP threshold to 0.5 mmHg and the RRI threshold to 3 or 4 ms may improve BRSSEQ validity during sevoflurane anesthesia, when compared to BRSMODOX.
Anesthesia* ; Anesthetics, Inhalation ; Baroreflex* ; Bias (Epidemiology) ; Blood Pressure* ; Nitroprusside ; Phenylephrine

BACKGROUND AND OBJECTIVES: Heart rate variability (HRV) illustrates the autonomic integration of the heart. Depressed HRV has been proven to be associated with an increased risk of cardiac death, whereas heart rate turbulence (HRT) is believed to reflect baroreflex sensitivity and it was recently introduced as another noninvasive tool for risk stratification. The aim of this study was to determine the relationship between the HRT and HRV parameters in Korean adults with a structurally normal heart. SUBJECTS AND METHODS: We studied 61 adults (males: 31) who showed ventricular premature complexes on 24 hour Holter recording and who were found to have normal hearts on full noninvasive investigation. We calculated the mean heart rate (RR interval), the number of VPBs, the time- and frequency-domain HRV parameters and two HRT parameters: turbulence onset (To) and turbulence slope (Ts). RESULTS: Ts showed a strong correlation with the HRV parameters (LF/HF ratio: r=0.35, p=0.006; VLF: r=0.32, p=0.013; LF: r=0.27, p=0.035; SDNN: r=0.28, p=0.029; SDANN: r=0.32, p=0.012), but To showed no significant correlation with the HRV parameters. CONCLUSION: The HRT parameters, and especially Ts, correlate strongly with the HRV parameters; therefore, Ts should be considered as a parameter that reflects the overall cardiac autonomic tone.
Adult* ; Baroreflex ; Death ; Heart Rate* ; Heart* ; Humans ; Ventricular Premature Complexes

BACKGROUND: The phase relationship indicates the time delay between the input signal (systolic blood pressure, SBP) and output signal (R-R interval, RRI). In contrast to the awake state, little is known about the effects of general anesthesia on the phase shift. In the present study, we tested the hypothesis that sevoflurane anesthesia causes a phase change between the two signals. METHODS: We assessed changes in phase, coherence, and baroreflex sensitivity between SBP and RRI by the use of transfer function analysis in 50 ASA 1 patients during the awake state and during end-tidal 2% sevoflurane-50% N2O anesthesia. RESULTS: SBP and RRI decreased significantly during sevoflurane anesthesia (P < 0.001). The phase in the low frequency (LF) region remained unchanged, but the phase in the high frequency (HF) region changed significantly from -29.52 +/- 50.70 to 27.28 +/- 80.22 degrees during sevoflurane anesthesia (P < 0.001). Coherence and baroreflex sensitivity between the two signals in the LF and HF regions decreased significantly during sevoflurane anesthesia (P < 0.001, respectively). CONCLUSIONS: We found that in the HF region and not in the LF region, sevoflurane anesthesia provokes the shift of the SBP-RRI phase relationship, suggesting that this change is inconsistent with a vagally mediated response.
Anesthesia* ; Anesthesia, General ; Baroreflex ; Blood Pressure* ; Heart Rate* ; Heart* ; Humans

BACKGROUND: In the previous studies, remifentanil reduces the hemodynamic change induced by endotracheal intubation. We studied the optimal effect site concentration of remifentanil for endotracheal intubation using light wand. METHODS: Sixty ASA 1 or 2 patients scheduled for elective surgery under general anesthesia were classified in three groups according to the TCI (target controlled infusion) dose of remifentanil. Each group was administered 4microgram/ml of propofol TCI, rocuronium, with 2 ng/ml (group 1), 4 ng/ml (group 2), 6 ng/ml (group 3) of remifentanil TCI. Blood pressure, heart rate and bispectral index score were measured before induction, 3 minutes after remifentanil and propofol TCI, after endotracheal intubation using light wand, and 3 minutes after endotracheal intubation. Statistical analysis was done for comparison of time and dose dependant change among the groups. RESULTS: After endotrachal intubation, blood pressure and heart rate were significantly increased in group 1, and decreased in group 2 and 3. 3 minute after endotracheal intubation, heart rate significantly decreased in group 3, but there were no changes in group 2. CONCLUSIONS: The spontaneous BRS was decreased during ketamine induction of general anesthesia. These results suggest that anesthesia induction with ketamine impairs baroreflex control of heart rate, which may provoke hemodynamic instability.
Anesthesia ; Anesthesia, General ; Baroreflex ; Blood Pressure ; Heart Rate ; Hemodynamics* ; Humans ; Intubation ; Intubation, Intratracheal* ; Ketamine ; Propofol

BACKGROUND: Vagal cardiac function plays an important role in cardiovascular homeostasis. The purpose of this study was to investigate the association between vagal cardiac function and changes in blood pressure induced by phenylephrine and by thigh cuff deflation after low-dose atropine (LDA)(2microgram/kg) administration. METHODS: Beat-to-beat changes in R-R intervals (RRI) and systolic blood pressures (SBP) were measured in 33 healthy volunteers during spontaneous and controlled (15 min-1) breathing before and after LDA administration. The RMSSD (root mean square of successive differences of RRI), pNN50 (proportion of successive RRI > 50 ms in relation to the total RRI), standard deviation 1 (SD1) from Poincare plots, power spectral densities of heart rate variability (HRV) and SBP variability, and spontaneous baroreflex sensitivity (BRS) by transfer function analysis were assessed. Acute hypertension was induced by phenylephrine (2 microgram/kg), whereas acute hypotension was induced by thigh cuff deflation. RESULTS: RMSSD, pNN50, SD1 of Poincare plots, and the high frequency (HF) power of HRV increased after LDA administration as did spontaneous BRS. Moreover, acute hypertension induced by phenylephrine was significantly attenuated (15.9 +/- 1.9 to 10.8 +/- 3.1 mmHg, P = 0.004) after LDA administration. However, acute hypotension induced by thigh cuff deflation was not significantly changed (13.4 +/- 3.9 to 11.9 +/- 4.2 mmHg, P = 0.62) after LDA administration. Changes in SBP during acute hypertension induced by phenylephrine were significantly correlated with changes in the HF power of HRV (r = -0.60, P < 0.001). CONCLUSIONS: Increasing vagal cardiac function induced by LDA attenuated increased SBP during acute hypertension induced by phenylephrine, but not decreased SBP during acute hypotension induced by thigh cuff deflation in healthy awake subjects.
Atropine* ; Baroreflex ; Blood Pressure ; Healthy Volunteers ; Heart Rate ; Homeostasis ; Hypertension ; Hypotension ; Phenylephrine ; Respiration ; Thigh

OBJECTIVE: Anxiety trait, anxiety and depression states have all been reported to increase risks for cardiovascular disease (CVD), possibly through altering cardiac autonomic regulation. Our aim was to investigate whether the relationship between harm avoidance (HA, an anxiety-related personality trait) and cardiac autonomic regulation is independent of anxiety and depression states in healthy adults. METHODS: We recruited 535 physically and mentally healthy volunteers. Participants completed the Beck Anxiety Inventory (BAI), Beck Depression Inventory (BDI) and Tri-dimensional Personality Questionnaire. Participants were divided into high or low HA groups as discriminated by the quartile value. Cardiac autonomic function was evaluated by measuring heart rate variability (HRV). We obtained the time and frequency-domain indices of HRV including variance (total HRV), the low-frequency power (LF; 0.05-0.15 Hz), which may reflect baroreflex function, the high-frequency power (HF; 0.15-0.40 Hz), which reflects cardiac parasympathetic activity, as well as the LF/HF ratio. RESULTS: The BDI and HA scores showed associations with HRV parameters. After adjustment for the BDI scores and other control variables, HA is still associated with reduced variance, LF and HF power. Compared with the participants with low HA, those with high HA displayed significant reductions in variance, LF and HF power and a significant increase in their LF/HF ratio. CONCLUSION: This study highlights the independent role of HA in contributing to decreased autonomic cardiac regulation in healthy adults and provides a potential underlying mechanism for anxiety trait to confer increased risk for CVD.
Adult* ; Anxiety ; Baroreflex ; Cardiovascular Diseases ; Depression ; Healthy Volunteers ; Heart Rate* ; Heart* ; Humans

This study was Uesigned to evaluate the reflexive heart rate response to acute blood loss during sodium nitroprusside and prostaglandin E1 induced-hypotension in isoflurane anesthetized dogs. The results were as follows: 1) Reflexive increase in heart rate during induced hypotension was significantly greater in sodium nitroprusside than prostaglandin E1. 2) Reflexive increase in heart rate during induced hypotension was significantly greater prostaglandin E1 induced-hypotension than during that wih sodium nitroprusside. From these results, it suggest that prostaglandin E1 induced-hypotension provides a safer margin than with sodium nitroprusside when rapid bleeding occurs during anesthesia and surgery.
Alprostadil ; Anesthesia ; Animals ; Baroreflex* ; Dogs ; Heart Rate ; Hemorrhage ; Hypotension* ; Isoflurane ; Nitroprusside* ; Pressoreceptors* ; Reflex ; Sodium*