Noninvasive investigation of autonomic activity after carotid stenting or carotid endarterectomy

Effects of different types of carotid endarterectomy on the course of resistant arterial hypertension

OBJECTIVE

Analysis of the dynamics of systolic blood pressure (SBP) and the results of various types of carotid endarterectomy (СЕЕ) (classical with plasty of the reconstruction zone with a patch, eversion, formation of a new bifurcation, autoarterial reconstruction, glomus-saving techniques) in patients with resistant arterial hypertension (RAH).

MATERIALS AND METHODS

The actual cohort, comparative, retrospective, open research for the period from January 2013 to December 2021 includes 1577 patients with significant hemodynamic stenosis of the internal carotid artery Depending on revascularization strategy five groups were formed: Group 1: 18.3% (n = 289) - classical Carotid endarterectomy with plasty of the reconstruction zone with a patch (from diepoxy-treated xenopericardium or synthetic); Group 2: 29.9% (n = 472) - eversional CEE with cut-off of carotid gloomus (CG); Group 3: 6.9% (n = 109) - the formation of a new bifurcation; Group 4: 7.4% (n = 117) - autoarterial reconstruction; Group 5: 37.4% (n = 590) - glomus-saving CEE (1 technique - according to A.N. Kazantsev; two technicians - according to R.A. Vinogradov; three technicians - according to K.A.Antsupov). According to the 24-h blood pressure monitor in the preoperative period, the following degrees of AH were identified: 1° - 5.7% (n = 89); 2° - 64.2% (n = 1013); and 3° - 30.1% (n = 475).

RESULTS

In the postoperative period, no significant differences were obtained in the frequency of deaths, myocardial infarction, stroke, hemorrhagic transformation. However, according to the frequency of the combined endpoint (death + myocardial infarction + ischemic stroke + hemorrhagic transformation), the lowest rates were observed in the group of classical carotid endarterectomy with plasty of the reconstruction zone with a patch and glomus-sparing CEE (group 1: 1.03% (n = 3); group 2: 3.6% (n = 17); group 3: 3.67% (n = 4); group 4: 2.56% (n = 3); group 5: 0.5% (n = 3); p = 0.10). This is due to the absence of cases of labile AH and hypertensive crises among patients of groups 1 and 5, which was ensured by the preservation of carotid glomus (CG). As a result, the number of patients with 2 and 3 degrees of hypertension in these groups decreased statistically significantly. The vast majority of patients after these operations achieved a stable target SBP. In groups 2, 3, and 4, there was a statistically significant increase in the number of patients with 2 and 3 degrees of AH, which is associated with excision of the CG.

CONCLUSION

Classical CEE and glomus-sparing CEE techniques make it possible to achieve a stable target SBP level in patients with RAH as a result of CG preservation. Removal or traumatization of the latter during eversional CEE, the formation of a new bifurcation, autoarterial reconstruction is accompanied by the development of labile hypertension, an increase in the degree of hypertension and a high risk of hemorrhagic transformation in the brain. Thus, the most effective and safe types of CEE in the presence of RAH are classical CEE with plasty of the reconstruction zone with a patch and glomus-sparing CEE, accompanied by the lowest incidence of adverse cardiovascular events caused by postoperative hypertensive crisis and hyperperfusion syndrome.

Interplay between baroreflex sensitivity, obesity and related cardiometabolic risk factors (Review)

The baroreflex represents a rapid negative feedback system implicated in blood pressure regulation, which aims to prevent blood pressure variations by regulating peripheral vascular tone and cardiac output. The aim of the present review was to highlight the association between baroreflex sensitivity (BRS) and obesity, including factors associated with obesity, such as metabolic syndrome, hypertension, cardiovascular disease and diabetes. For the present review, a literature search was conducted using the PubMed database until August 21, 2021. The searched terms included ‘baroreflex’, and other terms such as ‘sensitivity’, ‘obesity’, ‘metabolic syndrome’, ‘hypertension’, ‘diabetes’, ‘gender’, ‘aging’, ‘children’, ‘adolescents’, ‘physical activity’, ‘bariatric surgery’, ‘autonomous nervous system’ and ‘cardiometabolic risk factors’. Obesity and its related metabolic disorders can influence baroreflex functionality and decrease BRS, mostly by potentiating sympathetic nervous system activity. Obesity induces inflammation, which can increase sympathetic system activity and lead to a higher incidence of cardiovascular events. Obesity also represents an important risk factor for hypertension through numerous mechanisms; in this setting, dysfunctional baroreceptors are not able to protect against constantly elevated blood pressure. Furthermore, diabetes mellitus and oxidative stress result in deterioration of BRS, whereas aging is also generally related to reduced cardiovagal BRS. Differences in BRS have also been observed between men and women, and overall cardiovagal BRS in healthy women is less intense compared with that in men. BRS appears lower in children with obesity compared with that in children of a healthy weight. Notably, physical exercise can increase BRS in both hypertensive and normotensive subjects, and BRS can also be significantly improved following bariatric surgery and weight loss. In conclusion, obesity and its related metabolic disorders may influence baroreflex functionality and decrease BRS, and baroreceptors cannot protect against the constantly elevated blood pressure in obesity. However, following bariatric surgery and weight loss, BRS can be significantly improved. The present review summarizes the role of obesity and related metabolic risk factors in BRS, providing details on possible mechanisms and shedding light on their interplay leading to autonomic neuropathy.

[A multicenter study on the influence of different kinds of carotidal endarterectomy on the course of resistant arterial hypertension]

OBJECTIVE

To analyze the dynamics of systolic blood pressure (SBP) and the results of various types of carotid endarterectomy (CEE) in patients with resistant arterial hypertension (RAH).

MATERIALS AND METHODS

The study included 1577 patients with hemodynamically significant stenosis of the internal carotid artery (ICA) and RAH for more than 3 years. Patients were enrolled from January 2014 to December 2020. Depending on the implemented revascularization strategy, 5 groups were formed: group 1 (n=289 (18.3%)) with classical CEE with plasty of the reconstruction zone with a patch, group 2 (n=472 (29.9%)) with eversional CEE with cut-off of carotid glomus (CG); group 3 (n=109 (6.9%)) with the formation of a new bifurcation; group 4: (n=117 (7.4%)) with autoarterial reconstruction; group 5: (n=590 (37.4%)) with glomus-saving CEE.

RESULTS

In the postoperative period, no significant differences were obtained in the frequency of deaths (0.34% for group 1; 0.63% for group 2; 0% for groups 3, 4 and 5), myocardial infarction (0.34%, 0.84%, 1.83, 0.85%, 0.33%, respectively); ischemic stroke (0.34%, 1.27%, 0.91%, 0.85%, 0.17%, respectively), hemorrhagic transformation (0%, 0.84%, 0.91%, 0.85%, 0%, respectively). However, according to the frequency of the combined endpoint (death + myocardial infarction + ischemic stroke + hemorrhagic transformation), the lowest rates were observed in the group of classical carotid endarterectomy with plasty of the reconstruction zone with a patch and glomus-sparing CEE (1.03%, 3.6%, 3.67%, 2.56%, 0.5%, respectively). This is due to the absence of cases of labile AH and hypertensive crises among patients of groups 1 and 5, which was ensured by the preservation of carotid glomus (CG). As a result, the number of patients with 2 and 3 degrees of hypertension in these groups decreased statistically significantly. The vast majority of patients after these operations achieved a stable target SBP. In groups 2, 3, and 4, there was a statistically significant increase in the number of patients with 2 and 3 degrees of AH, which is associated with excision of the CG.

CONCLUSION

Classical CEE and glomus-sparing CEE techniques make it possible to achieve a stable target SBP level in patients with RAH as a result of CG preservation. Removal or traumatization of the latter during eversional CEE, the formation of a new bifurcation, autoarterial reconstruction is accompanied by the development of labile hypertension, an increase in the degree of hypertension and a high risk of hemorrhagic transformation in the brain. Thus, the most effective and safe types of CEE in the presence of RAH are classical CEE with plasty of the reconstruction zone with a patch and glomus-sparing CEE.

Predisposing Factors and Management of Hemodynamic Depression Following Carotid Artery Stenting

Carotid artery stenting (CAS) involves dilatation of carotid bulb which can trigger a series of neuronal responses resulting in hemodynamic depression that might influence the outcome of the procedure. This is a frequent but underdiagnosed complication of CAS. Although it is mild, transient and self-limiting in majority of cases, it can result in significant morbidity and mortality if persistent. Neurologists should be aware of the predisposing factors and management of this common complication. In patients who present with stroke following carotid stenting, neurologists should be aware of hypoperfusion secondary to hemodynamic depression as a cause of stroke apart from the stent thrombosis and occlusion.

Predictors of Carotid Artery Stenting-Induced Hemodynamic Instability

BACKGROUND

To address the predictors of hemodynamic instability (HI) related to carotid artery stenting (CAS) and evaluate the association between HI and periprocedural adverse outcomes.

METHODS

This study comprised all consecutive patients who underwent CAS for atherosclerotic carotid artery stenosis from March 2014 to May 2018. A standardized dose of atropine (0.4 mg) was given prior to stent deployment. Changes in heart rate, blood pressure, and neurological status were monitored and recorded. Potential predictors of HI were tested in multivariate analysis using binary logistic regression model.

RESULTS

A total of 728 patients were enrolled. Two hundred twenty seven patients (31.2%) developed periprocedural HI. The presence of hypertension (OR, 2.037; 95% CI, 1.292-3.211; P = 0.0022), symptomatic carotid lesions (OR, 1.704; 95% CI, 1.057-2.747; P = 0.0287), right sided lesions (OR, 3.090; 95% CI, 1.934-4.935; P ≤ 0.0001), hyperechoic/calcified plaques (OR, 2.195; 95% CI, 1.458-3.304; p P = 0.0002), and longer lesions (OR, 1.043; 95% CI, 1.012-1.076; P = 0.0072) were significant predictable factors for the occurrence of HI. On the other hand, smoking was significantly associated with a 48.1% decrease in risk of development of HI (OR, 0.519; 95% CI, 0.358-0.754; P = 0.0006). There were no statistically significant differences in periprocedural morbidity or mortality between patients with and without HI.

CONCLUSION

HI occurs in a considerable percentage of patients undergoing CAS. Hypertension, right sided, symptomatic carotid lesions, calcified plaques, and longer lesions were shown to be independent risk factors for the development of periprocedural HI. Conversely, smoking demonstrated a protective effect. HI did not appear to predispose to periprocedural adverse events.

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.

Prolonged hypotension after carotid artery stenting: incidence, predictors and consequences

BACKGROUND

Hemodynamic changes frequently occur after carotid artery stenting (CAS), and in some patients these changes, particularly hypotension, may be prolonged. There are discrepant results for predicting patients at high risk for these prolonged hemodynamic changes and identifying the effect on clinical outcome. In this study, we aimed to determine the frequency, predictors and consequences associated with prolonged hypotension (PH) after CAS in our center.

METHODS

We retrospectively analyzed the demographics, risk factors, nature of carotid disease, degree of stenosis of both internal carotid arteries, stent diameter and site of dilatation during stenting in 137 CAS procedures. After CAS, duration of hospital stay, complications during hospital stay and major vascular events or death in a 3-month period were evaluated. PH was defined as a systolic blood pressure <90 mmHg lasting more than 1 h despite adequate treatment after CAS.

RESULTS

PH occured in 23 (16.8%) patients. The presence of contralateral stenosis ≥70% and absence of diabetes mellitus were significantly associated with PH. Duration of hospital stay was significantly longer in patients with PH. No patients with PH had a periprocedural complication or major vascular events in the follow-up period.

CONCLUSION

PH was more prevalent in patients with contralateral high-degree carotid stenosis and patients without diabetes mellitus after CAS. PH did not cause any post-procedural complications or major vascular events at follow-up, but it resulted longer hospital stays. Further studies are needed to better define the pathophysiologic mechanisms underlying these hemodynamic alterations.

Autonomic control of blood circulation in patients undergoing elective carotid endarterectomy

BACKGROUND

Internal carotid artery stenosis (ICAS) is associated with significantly higher risk of stroke. Autonomic function can be impaired in the presence of atheroma in the carotid sinus region. Two parameters of autonomic nervous system (ANS) function e.g. heart rate variability (HRV) and baroreflex sensitivity (BRS) are respected predictors of cardiovascular prognosis. We assessed the effect of elective unilateral carotid endarterectomy (CEA) on cardiovascular autonomic functions as a major prognostic factor for cardiovascular health.

METHODS

Nineteen patients indicated for CEA underwent formal autonomic assessment in the laboratory. Hemodynamic profiles, HRV and BRS were evaluated with the dedicated high-tech device Task Force Monitor before surgery (day-1) and postoperatively (day 3±1). Data were obtained during 5 min orthostatic challenge and subsequent 5 min in a supine position.

RESULTS

There were no significant early postoperative changes in evaluated parameters after CEA. There was a mild decrease of blood pressure and therefore only a slight increase in BRS. It was also possible to observe a rise in the value of total power and high frequency power.

CONCLUSION

In the early postoperative period, healing processes are occurring and the sympatho-vagal interaction is probably still unbalanced. Given the considerable clinical potential of BRS and HRV measurement, further short-term and, more importantly, long-term investigations are needed.

Beneficial effects of prolonged blood pressure control after carotid artery stenting

Objectives

The main purpose of this study was to investigate whether carotid artery stenting (CAS) plus medicine in patients with severe carotid artery stenosis provide a better long-term blood pressure (BP) control compared to other medical treatments alone. The other aim was to explore the correlation between post-CAS hypotension within 6 h and long-term BP reductions after CAS.

Materials and methods

Patients with severe carotid stenosis were recruited either in the CAS group or in the medication group. BPs and the number of classes of antihypertensive agents were recorded at baseline, 6, and 12 months. Extra BP information was collected at 6 h, 3 days, and 1 month after CAS. Univariate and multivariate linear regressions were performed to test the relationship of BP changes among CAS and medication groups after 6 and 12 months of follow-up. Univariate linear regressions were also used to determine the correlations between the mean or maximal systolic BP (SBP) reductions at 6 h and 1 year post-CAS.

Results

In total, 72 members in the CAS group and 82 members in the medication group were recruited. Compared with the medication group, patients in the CAS group had greater BP reductions at 6 and 12 months of follow-up after adjusting for confounding factors (13.56 mmHg at 6 months, P=0.0002; 16.98 mmHg at 12 months, P<0.0001). This study also shows significant positive correlations between the mean or maximal SBP reductions 6 h post-CAS and SBP reductions 1 year post-CAS (β =0.20±0.07, P=0.0067 and β =0.47±0.10, P<0.0001, respectively).

Conclusion

As compared to medical treatment alone, CAS may provide significant beneficial effect on long-term BP control 1 year post-CAS. Furthermore, SBP reductions 6 h post-CAS may predict the SBP reductions 1 year post-CAS.

Long-Term Effect of the Type of Carotid Endarterectomy on Blood Pressure

BACKGROUND

The dissection of the carotid sinus nerve in eversion carotid endarterectomy (eCEA) has been hypothesized to cause an increase in postoperative blood pressure (BP). The objective of this study is to evaluate the effect of eCEA on BP and changes in BP medications over the course of year-long follow-up after eCEA compared with longitudinal incision carotid endarterectomy patch angioplasty (pCEA).

METHODS

A retrospective review of patients who underwent CEA between July 1, 2009 and June 30, 2014 in the Vascular Surgery Department at The University of Iowa Hospital and Clinics was conducted. Demographics, comorbidities, BP, and number, dosage, and type of antihypertensive medications were collected preoperatively, at 30 days, and at 12 months. The differences in BP and medications between pCEA and eCEA patients were compared. Demographic data and comorbidities were compared using t-tests and chi-squared analysis. Differences in BP and medication dosages were analyzed using multivariate analysis of variance.

RESULTS

In total, 363 CEA procedures were performed during the study period, of which 275 procedures were included in the final analysis. Thirty percent of the patients underwent eCEA. Fifty-four percent of the patients who underwent eCEA and 60% of the patients who underwent pCEA were symptomatic. Thirty-day mortality was 1.4% and 12-month mortality was 6.4% for the entire population. No postoperative neurologic deficits, including stroke, were observed. Analysis of BP did not yield a significant difference among preoperative, 30-day, and 12-month follow-up measurements (P = 0.893). There was no significant change to the number and total daily dose of BP medications preoperatively, at 30 days, or at 12 months.

CONCLUSIONS

There is no statistical difference in mortality, morbidity, and patency rates at 30 days and 12 months between pCEA and eCEA. eCEA is also not associated with long-term BP changes compared with pCEA.

Carotid baroreceptor stimulation blood pressure response mapped in patients undergoing carotid endarterectomy (C-Map study)

OBJECTIVE

Continuous stimulation of the carotid baroreceptors has been shown to evoke a sustained systolic blood pressure (SBP) reduction in hypertensive subjects. This study conducted a detailed mapping of the SBP and heart rate response to electrical stimulus at different locations in the carotid sinus region in patients undergoing a carotid endarterectomy (CEA).

METHODS

The Carotid Sinus Autonomic Response Mapping (C-Map) Study is a multicenter, prospective, non-randomized, acute feasibility study conducted in 10 hypertensive subjects undergoing CEA. Electrode pairs were placed in multiple locations in the region of the carotid sinus for acute stimulation, and the tests were repeated after plaque removal and vessel repair.

RESULTS

The configuration that elicited the largest pressure reduction in 8 of 10 patients was with the electrodes arranged longitudinally along the medial (in relation to the bifurcation) wall of the internal carotid artery (ICA) near the bifurcation (11.2±8.1mmHg, p<0.05). There was no difference in average maximum response pre vs. post plaque removal. Spontaneous baroreflex sensitivity increased from 6.0±3.2ms/mmHg pre-CEA to 8.2±5.4ms/mmHg post-CEA (p=0.040).

CONCLUSIONS

Endarterectomy surgery did not affect maximal acute stimulation response but improved baroreflex sensitivity acutely. Acute extravascular baroreceptor stimulation (BRS) mapping demonstrated that blood pressure reductions are dependent on electrode location and orientation. In most subjects, the largest SBP reductions were elicited in the region of the medial wall of the ICA. This area can be targeted for future BRS lead design and implant.

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.

Simple cardiovagal and adrenergic function tests in carotid artery stenosis patients as a potential tool for determining a transient autonomic dysfunction

PURPOSE

The arterial baroreflex depends on the integrity of the afferent limb, which can be quantified using the baroreceptor's sensitivity (BRS) during the Valsalva maneuver (VM). The aim of this study was to evaluate, using autonomic nervous system tests, the autonomic function in patients after a carotid artery angioplasty (CAS).

METHODS

We evaluated the changes in blood pressure (BP) during the VM (Valsalva ratio, BRS, sympathetic indexes) in 41 patients with symptomatic, unilateral, internal carotid artery stenosis.

RESULTS

The Valsalva ratio between the baseline and the post-procedural day (1.3 ± 0.1 vs 1.44 ± 0.3; P = 0.002) and the post-procedural day and a month later (1.44 ± 0.3 vs 1.3 ± 0.3; P = 0.0002) revealed significant differences. This was confirmed with a cardiovagal BRS test. However, the adrenergic BRS did not reveal any differences. Sympathetic indexes [BP fall (SI1) and recovery during phase 2 (SI2)] showed differences for the periods before and a day after the treatment (36.9 ± 18.0 vs 27.2 ± 21.4 and 7.1 ± 13.1 vs 3.0 ± 8.2, respectively; P = 0.004) and for SI1 a day and a month after the treatment (27.2 ± 21.4 vs 37.1 ± 21.8; P = 0.036). The dynamic ranges between S1 and S3 (the difference in the BP between the baseline and the end of phase 2) were also different (P = 0.007 and P = 0.044, respectively).

CONCLUSION

We found heterogeneous responses in the BP regulation obtained with the Valsalva maneuver in our patients; however, we could not confirm that CAS provoked any long-term autonomic dysfunction, except for 1 day after the procedure.

Episodes of flushing, dyspnea and hypertension after carotid stenting for severe carotid stenosis

INTRODUCTION

Carotid angioplasty and stenting (CAS) is a treatment option for carotid stenosis in high surgical risk patients. As it implies instrumentation of the carotid bulb, baroreceptors dysfunction may be provoked with consequent hemodynamic instability.

REPORT

An 83-year-old woman treated by CAS presented with episodes of flushing, dyspnea and palpitations accompanied by transitory desaturation, hypertension, agitation and anxiety. Symptoms started 12h after the procedure. Each episode lasted 10 min. Five episodes in 3 days were observed.

DISCUSSION

A dysfunction of the carotid baroreceptors and chemoreceptors was hypothesized.

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.

Role of Stent Selection in the Incidence of Persisting Hemodynamic Depression After Carotid Artery Stenting

Purpose: To investigate the possible role of stent selection and procedure-related vessel diameter changes in the development of persisting hemodynamic depression (PHD) and to demonstrate the effectiveness and safety of permanent pacemaker implantation in patients with refractory PHD. Methods: Data from 584 procedures performed in 542 patients (398 men; mean age 67.3 years) between 2008 and 2011 using Wallstent, Precise, and Xact stents in a nonrandomized fashion were analyzed retrospectively. Cardiovascular risk factors and lesion, stent, and balloon characteristics were collected, and the pre- and postprocedure diameters of the common carotid artery (CCA) and internal carotid artery were measured. PHD was defined as any episode of hypotension (systolic blood pressure <90 mm Hg) and/or bradycardia (heart rate <60/min) lasting >6 hours. Risk factors for PHD were sought using logistic regression analyses; the results are presented as the odds ratio (OR) and 95% confidence interval (CI). Results: The incidence of PHD was 37.0% (216/584). Refractory PHD was encountered in 9 patients; among these, 6 were successfully treated with pacemaker implantation. A history of prior ipsilateral carotid endarterectomy (OR 0.44, 95% CI 0.22 to 0.87, p=0.019) and the presence of a contralateral high-grade stenosis (OR 0.12, 95% CI 0.02 to 0.95, p=0.045) were independent protective factors, while calcification (OR 1.5, 95% CI 1.03 to 2.18, p=0.034), involvement of the carotid bulb (OR 2.56, 95% 1.62 to 4.03, p<0.001), and implantation of a nitinol stent (adjusted OR 1.62, 95% CI 1.12 to 2.34, p=0.011) were independent risk factors for developing PHD after carotid artery stenting. The ratio of the post-/preprocedure CCA diameter (p=0.002), the stent to CCA diameter ratio (p=0.009), and the presence of residual stenosis (p=0.009) were significantly higher in the PHD group. Conclusion: Stent selection and procedure-related changes in vessel diameter may have an influence on the development of PHD. Permanent pacemaker implantation is an effective treatment option in patients with refractory PHD.

Spectral analysis related to bare-metal and drug-eluting coronary stent implantation

BACKGROUND

The autonomic nervous system plays a central role in cardiovascular regulation; sympathetic activation occurs during myocardial ischemia.

OBJECTIVE

To assess the spectral analysis of heart rate variability during stent implantation, comparing the types of stent.

METHODS

This study assessed 61 patients (mean age, 64.0 years; 35 men) with ischemic heart disease and indication for stenting. Stent implantation was performed under Holter monitoring to record the spectral analysis of heart rate variability (Fourier transform), measuring the low-frequency (LF) and high-frequency (HF) components, and the LF/HF ratio before and during the procedure.

RESULTS

Bare-metal stent was implanted in 34 patients, while the others received drug-eluting stents. The right coronary artery was approached in 21 patients, the left anterior descending, in 28, and the circumflex, in 9. As compared with the pre-stenting period, all patients showed an increase in LF and HF during stent implantation (658 versus 185 ms2, p = 0.00; 322 versus 121, p = 0.00, respectively), with no change in LF/HF. During stent implantation, LF was 864 ms2 in patients with bare-metal stents, and 398 ms2 in those with drug-eluting stents (p = 0.00). The spectral analysis of heart rate variability showed no association with diabetes mellitus, family history, clinical presentation, beta-blockers, age, and vessel or its segment.

CONCLUSIONS

Stent implantation resulted in concomitant sympathetic and vagal activations. Diabetes mellitus, use of beta-blockers, and the vessel approached showed no influence on the spectral analysis of heart rate variability. Sympathetic activation was lower during the implantation of drug-eluting stents.

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

OBJECTIVE

Although carotid stenting is an effective treatment for severe carotid stenosis, it has been associated with alterations in autonomic functions during or shortly after the procedure. Heart rate variability (HRV) is an established tool for the asessment of autonumic functions. In this study, our aim was to investigate the relation between the alterations in autonomic functions and HRV by Holter monitoring parameters.

METHODS

Patients (19 male, 8 female) that are suitable for carotid artery stenting, without a history of hypertension, diabetes mellitus, severe coronary artery or valvular heart disease, were enrolled to our study. Short-term HRV analysis recordings were obtained at the beginning, and after the procedure. The square root of the mean squared differences of successive NN intervals (RMSSD), total frequency, low frequency (LF), high frequency (HF), normalized units LF (LFnu), normalized units HF (HFnu), LF/HF ratios were analyzed. Results were statistically analysed by using Wilcoxon test.

RESULTS

Total frequency did not show any significant changes after the procedure (1101 ± 829, 981 ± 855). While RMSSD and HFnu values significantly increased respectively (23 ± 12/33 ± 22, and 22 ± 10/35 ± 10, p < 0.05) after the procedure, HF values increased nonsignificantly after the procedure (82 ± 92/92 ± 108). LF, LFnu, and LF/HF values were significantly decreased after the procedure. (228 ± 166/112 ± 100, 70 ± 15/55 ± 18, 4 ± 2.5/2.1 ± 2, respectively, p < 0.05)

CONCLUSIONS

While RMSSD and HF are used as markers of vagal activity, LF is a marker of sympathetic modulation and LF/HF ratio shows sympathovagal balance. In our study, we showed that carotid artery stenting is associated with increase in parasympathetic activation, and this finding is demonstrated by HRV parameters.

P-wave dispersion by 12-lead electrocardiography in carotid artery stenting

OBJECTIVE

Although carotid artery stenting (CAS) is an effective treatment for severe carotid stenosis, it has been associated with alterations in autonomic functions during or shortly after the procedure. And, autonomic functions influence P-wave durations. In this study, our aim was to investigate P-wave durations on 12-lead surface electrocardiography after CAS.

METHODS

Patients (19 male, 8 female) who are suitable for CAS, without a history of hypertension, diabetes mellitus, severe coronary artery or valvular heart disease, were enrolled in our study. 12-lead surface electrocardiography recordings were obtained at the beginning, immediately after and at the 24 h of the procedure. P-wave maximum, minimum and dispersion durations were analyzed by double-blinded observers. Results were statistically analysed using Friedman and Wilcoxon tests.

RESULTS

The P maximum and P dispersion values were significantly increased immediately after the procedure and continued with high levels at 24-h recordings, respectively (128 ± 10/19 ± 7, 143 ± 14/37 ± 11, and 137 ± 11/30 ± 7 ms, p value <0.05). The P minimum value was significantly decreased immediately after the procedure (109 ± 11/105 ± 10 ms, p value <0.05). At 24-h recordings, a nonsignificant increase occured in P minimum values (106 ± 8 ms).

CONCLUSIONS

P maximum and dispersion durations were significantly increased after the CAS and continued with high levels at 24-h recordings, which may be associated with the alterations in autonomic functions via augmented parasympathetic activity by vagally mediated stimulus. Overall, these findings suggest that decline in cardiovascular activity is prolonged at least 24 h after CAS.

Cerebral hemodynamics and baroreflex sensitivity after carotid artery stenting

OBJECTIVES

The long-term hemodynamic effects of carotid angioplasty and stenting (CAS) are unclear. We performed a longitudinal study to investigate the variations in cerebral hemodynamics in patients undergoing CAS.

MATERIALS AND METHODS

We performed prospective evaluation of 63 symptomatic male patients (19 patients had transient ischemic attack and 44 had minor stroke; mean age: 77.3 ± 6.3 years [range: 51-86]). The mean blood flow velocities (MBFV) and pulsatility index (PI) of the middle cerebral arteries (MCA) on both sides were evaluated using transcranial color-coded Doppler (TCCD) ultrasonography. Cardiac autonomic activities were evaluated by measuring baroreflex sensitivity (BRS). All parameters were measured at baseline prior to CAS and at 1, 3, 6, and 12 months after CAS.

RESULTS

The preoperative MBFV and PI of the ipsilateral MCA were significantly lower than those of the contralateral side. However, after CAS, MBFV in the ipsilateral MCA increased significantly until 2 weeks after stenting, after which the MBFV gradually decreased and remained stable for 1 year after CAS. Further, we observed a nonsignificant increase in MBFV in the contralateral MCA after CAS. In contrast to the MBFV, the BRS values decreased significantly 1 month after stenting and returned to baseline levels 6 months after CAS.

CONCLUSIONS

Patients with CAS showed improved global cerebral hemodynamic status. However, the BRS did not normalize initially, and baseline value was achieved at 6 months after stenting.

A novel index of sympathovagal balance from independent component analysis of heart rate and blood pressure variability: performance in patients with carotid stenting and in the EuroBavar data set

The authors applied independent component analysis to oscillations of heart rate and blood pressure and obtained a new index of sympathovagal balance. The performance of this index was tested in patients with carotid artery stenting and in the EuroBavar data set according to the following criteria: (1) the index should vary similarly among subjects in response to different autonomic conditions; (2) the variability in the index among subjects exposed to the same autonomic conditions should be small; and (3) the response of the index to various autonomic conditions should reflect the underlying changes in the physiological state and have a meaningful interpretation. The new index from independent component analysis better fulfilled the criteria than the commonly used sympathovagal index, the ratio of low-to-high frequency spectra power of heart rate variability, and had higher discrimination power in distinguishing the autonomic status of the patients who had undergone carotid artery stenting from that of the control subjects.

Acute increase of complexity in the neurocardiovascular dynamics following carotid stenting

OBJECTIVE

Percutaneous carotid angioplasty and stenting (CAS) has been used to improve cerebral circulation and autoregulation. However, whether CAS ameliorates the autonomic regulatory dynamics remains unclear. This prospective study examines the neurocardiovascular dynamics following carotid stenting.

METHODS

Thirty minutes electrocardiograms were recorded at three different time points (pre-operative, 1-h post-operative, 1-day post-operative) on twelve male patients (mean age 70.8 ± 9.6 years) receiving unilateral primary CAS. The HR data were analyzed by the conventional heart rate variability (HRV) and the multiscale entropy (MSE) methods; the former associates with autonomic activities and the latter quantifies the regulatory complexity of heart beat intervals. Loss of complexity at multiple scales has been associated with decoupled regulatory network in vivo.

RESULTS

Conventional HRV indices showed no difference after CAS. Complexity indices increased significantly on scales 2-8 at 1-h and on scales 2-3 1-day post-treatment. The lower scale MSE (1-5) correlated with the frequency components of conventional HRV indices. The increased complexity could imply a restoration of the neurocardiovascular dynamics on the path to a healthier state.

CONCLUSIONS

Primary CAS can induce a recovery in the neurocardiovascular regulatory dynamics in patients with high-grade carotid stenosis.

Autonomic function and cerebral autoregulation in patients undergoing carotid endarterectomy

BACKGROUND

Carotid endarterectomy (CEA) is the first-line treatment in severe carotid stenosis to prevent stroke. Because of methodological limitations, the acute impact of CEA on baroreflex function and cerebral autoregulation is not well defined and was therefore investigated by applying a novel algorithm.

METHODS AND RESULTS

Systemic arterial blood pressure, ECG and respiration during metronomic breathing and Valsalva maneuver were continuously recorded in 18 patients with carotid stenosis before and after CEA, and in 10 healthy controls. Baroreflex sensitivity, frequency spectra of RR intervals and indices for cerebral autoregulation were evaluated by trigonometric regressive spectral analysis. Compared with the controls, patients had impaired baroreflex sensitivity. Baroreflex sensitivity and frequency spectra were not changed by CEA. Cerebral autoregulation of patients with carotid stenosis as calculated by phase shift was reduced compared with controls but it improved significantly after CEA. Improvement of cerebral autoregulation was independent of changes in cerebral blood flow velocity.

CONCLUSIONS

Baroreflex sensitivity and cerebral autoregulation are impaired in patients with carotid stenosis, conferring a high stroke risk. CEA improves cerebral autoregulation, but does not affect baroreflex sensitivity. For further risk reduction, interventional approaches targeting baroreflex function need to be considered. 

Effects of chronic baroreceptor stimulation on the autonomic cardiovascular regulation in patients with drug-resistant arterial hypertension

In patients with drug-resistant hypertension, chronic electric stimulation of the carotid baroreflex is an investigational therapy for blood pressure reduction. We hypothesized that changes in cardiac autonomic regulation can be demonstrated in response to chronic baroreceptor stimulation, and we analyzed the correlation with blood pressure changes. Twenty-one patients with drug-resistant hypertension were prospectively included in a substudy of the Device Based Therapy in Hypertension Trial. Heart rate variability and heart rate turbulence were analyzed using 24-hour ECG. Recordings were obtained 1 month after device implantation with the stimulator off and after 3 months of chronic electric stimulation (stimulator on). Chronic baroreceptor stimulation decreased office blood pressure from 185+/-31/109+/-24 mm Hg to 154+/-23/95+/-16 mm Hg (P<0.0001/P=0.002). Mean heart rate decreased from 81+/-11 to 76+/-10 beats per minute(-1) (P=0.001). Heart rate variability frequency-domain parameters assessed using fast Fourier transformation (FFT; ratio of low frequency:high frequency: 2.78 versus 2.24 for off versus on; P<0.001) were significantly changed during stimulation of the carotid baroreceptor, and heart rate turbulence onset was significantly decreased (turbulence onset: -0.002 versus -0.015 for off versus on; P=0.004). In conclusion, chronic baroreceptor stimulation causes sustained changes in heart rate variability and heart rate turbulence that are consistent with inhibition of sympathetic activity and increase of parasympathetic activity in patients with drug-resistant systemic hypertension; these changes correlate with blood pressure reduction. Whether the autonomic modulation has favorable cardiovascular effects beyond blood pressure control should be investigated in further studies.

Can periprocedural hypotension in carotid artery stenting be predicted? A carotid morphologic autonomic pathologic scoring model using virtual histology to anticipate hypotension

SUMMARY

Periprocedural hypotension, which frequently occurs during carotid artery stenting (CAS), is an important risk factor for complications such as stroke or death after CAS. To determine if a scoring model can be established to predict periprocedural hypotension (systolic blood pressure < or = 90 mm Hg) and prolonged periprocedural hypotension (requiring vasopressor for > 3 hours) in CAS, we conducted a prospective cohort study of patients undergoing interventional treatment of cervical carotid artery stenosis in an urban tertiary referral hospital from April 2006 to April 2007. Forty-eight stenotic lesions in 45 consecutive patients treated with CAS were included in the study. Multivariate analysis showed three independent risk factors of periprocedural hypotension; "fibrous plaque on Virtual Histology" (P = 0.029), "stenotic lesion involving both the common carotid artery and internal carotid artery on angiogram" (P = 0.004), and "patients without history of diabetes mellitus" (P = 0.020). Further, "distance between carotid bifurcation and point of minimum lumen size < or = 10 mm on angiogram" (P = 0.003) was an independent risk factor of prolonged periprocedural hypotension. Carotid morphologic autonomic pathologic score (carotid MAPS), determined by adding one point for each of those risk factors (total 0 to 4), had good discrimination for both periprocedural hypotension (area under receiver operating characteristic curve: ROC AUC = 0.876; SE 0.053) and prolonged periprocedural hypotension (ROC AUC = 0.811; SE 0.066). Carotid MAPS is useful for predicting periprocedural hypotension and prolonged periprocedural hypotension during CAS.

Carotid endarterectomy

Carotid endarterectomy (CEA) is performed to prevent embolic stroke in patients with atheromatous disease at the carotid bifurcation. There is now substantial evidence to support early operation in symptomatic patients, ideally within 2 weeks of the last neurological symptoms. Thus, the anaesthetist may be faced with a high risk patient in whom there has been limited time for preoperative preparation. The operation may be performed under local or general anaesthesia. The advantages and disadvantages of both are explored in this review. Carotid shunting may offer a degree of cerebral protection, but carries its own risks and has not been proved to reduce morbidity and mortality. The use of carotid shunts is based on clinical judgement, awake neurological monitoring, and the use of monitors of cerebral perfusion. There is no ideal monitor of cerebral perfusion in the patient receiving general anaesthesia. Both the intraoperative and postoperative periods may be witness to dramatic haemodynamic changes that may compromise the cerebral or myocardial circulations. In particular, postoperative hypotension may compromise both myocardial and cerebral perfusion, and severe hypertension can cause cerebral hyperperfusion. There is as yet limited evidence to guide the management of these problems. In summary, CEA can yield significant benefit, but those with the most to gain from the operation also present the greatest challenge to the anaesthetist.