Evaluation of autonomic functions by heart rate variability after stenting in patients with carotid artery stenosis

Prolonged Autonomic Fluctuation Derived from Parasympathetic Hypertonia after Carotid Endarterectomy but not Stenting

BACKGROUND

Carotid endarterectomy (CEA) is a standard treatment for carotid artery stenosis, but the incidence after periprocedural myocardial infarction (MI) is not negligible. The mechanism for the higher risk of MI following CEA compared with the carotid artery stenting (CAS) is unclear. We hypothesized that it may be explained by different autonomic nervous responses.

METHODS

This prospective, nonrandomized, observational study enrolled 50 patients from 2 centers: 25 underwent CEA and 25 CAS. Cardiac autonomic nervous activity was evaluated using 24-hour high-resolution ambulatory electrocardiography with parameters such as deceleration capacity (DC) and heart rate variability before the procedure, and at 1 week and 1-3 months after the procedure.

RESULTS

One week after CEA, decreased DC and increased acceleration capacity were recognized. Standard deviation of sequential 5-minute NN interval means and the low-frequency and high-frequency components were all decreased. By the later phase measurement, these changes returned to baseline or beyond. The results suggest that diminished autonomic activity reversed to excessive parasympathetic dominance. In contrast, the patients treated by CAS showed no remarkable autonomic modification in the early or later phases.

CONCLUSIONS

Distinct changes of sympathovagal response observed after CEA coincides with the time at which MI onset occurs, suggesting prolonged autonomic fluctuation may be a factor in the MI incidence after CEA.

Cardiovagal and adrenergic function tests in unilateral carotid artery stenosis patients-a Valsalva manoeuvre tool to show an autonomic dysfunction?

BACKGROUND

The stability of an arterial baroreflex depends also upon the integrity of the afferent limb. For its quantification, we can use a noninvasive test such as baroreceptor sensitivity estimation during Valsalva manoeuvre. The aim of this study was to evaluate potential autonomic dysfunction in patients with unilateral severe carotid disease and compare the results to the results obtained from an age and gender matched group of healthy volunteers.

METHODS

We evaluated dynamic changes during Valsalva manoeuvre (Valsalva ratio, cardiovagal and adrenergic baroreceptor sensitivity, sympathetic indexes and its dynamic ranges) in 41 patients (29 males; 62.9 ± 7.4 years) and compared the results to results obtained from volunteers (62.8 ± 7.0 years).

RESULTS

Valsalva ratio between the patients and control group revealed no significant difference, as well as cardiovagal and adrenergic baroreceptor sensitivity. Sympathetic indexes, except for sympathetic index 2, reflecting the sympathetic vasoconstrictor baroreceptor response in late phase 2 of Valsalva manoeuvre (7.1 ± 13.1 mmHg in patients vs. 11.4 ± 10.2 mmHg in control group; p = 0.012) showed no significant differences between the studied groups. The most prominent dynamic range between the groups was within the sympathetic index 2.

CONCLUSION

With some Valsalva manoeuvre test results, we were not able to show severe autonomic dysfunction in unilateral severe carotid stenosis patients except for lower vasoconstriction response within the late phase 2 of the manoeuvre.

Analysis of short-term heart rate and diastolic period variability using a refined fuzzy entropy method

BACKGROUND

Heart rate variability (HRV) has been widely used in the non-invasive evaluation of cardiovascular function. Recent studies have also attached great importance to the cardiac diastolic period variability (DPV) examination. Short-term variability measurement (e.g., 5 min) has drawn increasing attention in clinical practice, since it is able to provide almost immediate measurement results and enables the real-time monitoring of cardiovascular function. However, it is still a contemporary challenge to robustly estimate the HRV and DPV parameters based on short-term recordings.

METHODS

In this study, a refined fuzzy entropy (rFuzzyEn) was developed by substituting a piecewise fuzzy membership function for the Gaussian function in conventional fuzzy entropy (FuzzyEn) measure. Its stability and robustness against additive noise compared with sample entropy (SampEn) and FuzzyEn, were examined by two well-accepted simulation models-the [Formula: see text] noise and the Logistic attractor. The rFuzzyEn was further applied to evaluate clinical short-term (5 min) HRV and DPV of the patients with coronary artery stenosis and healthy volunteers.

RESULTS

Simulation results showed smaller fluctuations in the rFuzzyEn than in SampEn and FuzzyEn values when the data length was decreasing. Besides, rFuzzyEn could distinguish the simulation models with different amount of additive noise even when the percentage of additive noise reached 60%, but neither SampEn nor FuzzyEn showed comparable performance. Clinical HRV analysis did not indicate any significant differences between the patients with coronary artery disease and the healthy volunteers in all the three mentioned entropy measures (all p > 0.20). But clinical DPV analysis showed that the patient group had a significantly higher rFuzzyEn (p < 0.01) than the healthy group. However, no or less significant difference was observed between the two groups in either SampEn (p = 0.14) or FuzzyEn (p = 0.05).

CONCLUSIONS

Our proposed rFuzzyEn outperformed conventional SampEn and FuzzyEn in terms of both stability and robustness against additive noise, particularly when the data set was relatively short. Analysis of DPV using rFuzzyEn may provide more valuable information to assess the cardiovascular states than the other entropy measures and has a potential for clinical application.

Hemodynamic changes and baroreflex sensitivity associated with carotid endarterectomy and carotid artery stenting

Atherosclerotic carotid lesion is a major cause of stroke which accounts for up to 20% of ischemic stroke. Aggressive treatment of carotid stenosis may prevent stroke. Currently, carotid endarterectomy (CEA) and carotid artery stenting (CAS) are the first-line treatments for severe carotid stenosis. CEA is superior to medical therapy in preventing stroke and cardiovascular death. CAS has emerged as an alternative to CEA in recent years due to its less invasive nature. However, both CEA and CAS may be associated with adverse hemodynamic changes as well as a variation of carotid baroreflex sensitivity. There is no consensus on which of these two methods is more advantageous concerning the procedure-related hemodynamic changes. This article reviews the hemodynamic changes and baroreflex sensitivity after CEA and CAS.

Effect of penehyclidine hydrochloride on heart rate variability in hysteroscopy

In order to evaluate the effect of different doses of penehyclidine hydrochloride (penehyclidine) on heart rate (HR) and HR variability (HRV) in hysteroscopy, 180 patients (American Society of Anesthesiologists grade I-II) were randomized equally to three groups: 0.5 mg penehyclidine and intravenous anesthesia (group I), 1.0 mg penehyclidine and intravenous anesthesia (group II) and saddle anesthesia combined with intravenous anesthesia (control group). HR and HRV, including total power (TP), low-frequency power (LF), high-frequency power (HF) and the LF to HF ratio (LF/HF), were recorded prior and subsequent to the induction of anesthesia (T₀ and T₁, respectively), following the start of surgery (T₂) and following completion of surgery (T₃). HR was lower at T₂ than at T₀ in the control patients, but no differences were observed in groups I and II. The HR at T₂ was increased in group II compared with that in group I. TP in group II was significantly higher compared with that in group I at T₂. At T₁ and at T₂, the LF and HF values were lower in group I than those in the controls. Patients in group II also had higher LF and HF at T₂ than patients in group I. The HF was higher at T₂ than that at T₀ in the controls; however, the HF and LF did not change significantly within groups I and II. No significant differences were observed in the LF/HF ratio among the three groups. At a dose of 0.5 mg, penehyclidine stabilized HRV and did not alter the autonomic nervous modulation of HR. A penehyclidine dose of 1.0 mg may be superior to a dose of 0.5 mg in maintaining HR, but is less effective at balancing sympathetic and parasympathetic activity.