Five-year follow-up of patients after thromboendarterectomy of the internal carotid artery: Relevance of baroreceptor sensitivity

Redefining postoperative hypertension management in carotid surgery: a comprehensive analysis of blood pressure homeostasis and hyperperfusion syndrome in unilateral vs. bilateral carotid surgeries and implications for clinical practice

Background

This study evaluates the implications of blood pressure homeostasis in bilateral vs. unilateral carotid surgeries, focusing on the incidence of postoperative hypertension, hyperperfusion syndrome, and stroke as primary outcomes. It further delves into the secondary outcomes encompassing major adverse cardiovascular events and all-cause mortality.

Methods

Spanning two decades (2002-2023), this comprehensive retrospective research encompasses 15,369 carotid referrals, out of which 1,230 underwent carotid interventions. A subset of 690 patients received open carotid procedures, with a 10-year follow-up, comprising 599 unilateral and 91 bilateral surgeries. The Society for Vascular Surgery Carotid Reporting Standards underpin our methodological approach for data collection. Both univariate and multivariate analyses were utilized to identify factors associated with postoperative hypertension using the Statistical Package for the Social Sciences (SPSS) Version 22 (SPSS®, IBM® Corp., Armonk, N.Y., USA).

Results

A marked acute elevation in blood pressure was observed in patients undergoing both unilateral and bilateral carotid surgeries (p < 0.001). Smoking (OR: 1.183, p = 0.007), hyperfibrinogenemia (OR: 0.834, p = 0.004), emergency admission (OR: 1.192, p = 0.005), severe ipsilateral carotid stenosis (OR: 1.501, p = 0.022), and prior ipsilateral interventions (OR: 1.722, p = 0.003) emerged as significant factors that correlates with postoperative hypertension in unilateral surgeries. Conversely, in bilateral procedures, gender, emergency admissions (p = 0.012), and plaque morphology (p = 0.035) significantly influenced postoperative hypertension. Notably, 2.2% of bilateral surgery patients developed hyperperfusion syndrome, culminating in hemorrhagic stroke within 30 days. Intriguingly, postoperative stage II hypertension was identified as an independent predictor of neurological deficits post-secondary procedure in bilateral CEA cases (p = 0.004), attributable to hyperperfusion syndrome. However, it did not independently predict myocardial infarction or mortality outcomes. The overall 30-day stroke rate stood at 0.90%. Lowest incidence of post operative hypertension or any complications were observed in eversion carotid endartrertomy.

Conclusion

The study identifies postoperative hypertension as a crucial independent predictor of perioperative stroke following bilateral carotid surgery. Moreover, the study elucidates the significant impact of bilateral CEA on the development of post-operative hyperperfusion syndrome or stroke, as compared to unilateral CEA. Currently almost 90% of our carotid practice is eversion carotid endartrerectomy.

Severe blood pressure elevation following ephedrine administration during carotid endarterectomy under general anesthesia: A CARE-compliant case report

RATIONALE

During carotid endarterectomy (CEA) surgery, blood pressure management is particularly important to prevent cerebrovascular and cardiac complications. Ephedrine is a commonly used vasopressor, however, we report the case of a patient with unusually severe blood pressure elevation following intravenous ephedrine administration during CEA.

PATIENT CONCERNS

A 72-year-old man diagnosed with right proximal internal carotid artery stenosis underwent CEA under general anesthesia. After declamping the common carotid artery, blood pressure rapidly increased by 125 mm Hg (from 90 to 215 mm Hg) after ephedrine (4 mg) was administered, but the heart rate was stable.

DIAGNOSES

There was an ordinal increase in blood pressure after the same small dose of ephedrine was administered at the early stage of the surgery. And the surgical approach was difficult because he had a high location of carotid bifurcation and a prominent mandibular angle. Because of the anatomical proximity of the cervical sympathetic trunk to the carotid bifurcation and the particularly complicated surgical process in the present case, we postulate the reason for this adverse reaction as transient sympathetic denervation supersensitivity.

INTERVENTIONS

Perdipine (0.5 mg) was administered repeatedly to reduce blood pressure.

OUTCOMES

After surgery, he was diagnosed with right hypoglossal nerve palsy, and no other abnormal signs were found.

CONCLUSION

This case highlights the need for caution in the use of ephedrine, which is commonly used in CEA surgery, wherein blood pressure management is particularly important. Although it is a rare and unpredictable case, α-agonists are considered safer in situations where sympathetic supersensitivity is possible.

A Machine Learning Approach for Predicting Early Phase Postoperative Hypertension in Patients Undergoing Carotid Endarterectomy

BACKGROUND

This study aimed to establish and validate a machine learning-based model for the prediction of early phase postoperative hypertension (EPOH) requiring the administration of intravenous vasodilators after carotid endarterectomy (CEA).

METHODS

Perioperative data from consecutive CEA procedures performed from January 2013 to August 2019 were retrospectively collected. EPOH was defined in post-CEA patients as hypertension involving a systolic blood pressure above 160 mm Hg and requiring the administration of any intravenous vasodilator medications in the first 24 hr after a return to the vascular ward. Gradient boosted regression trees were used to construct the predictive model, and the featured importance scores were generated by using each feature's contribution to each tree in the model. To evaluate the model performance, the area under the receiver operating characteristic curve was used as the main metric. Four-fold stratified cross-validation was performed on the data set, and the average performance of the 4 folds was reported as the final model performance.

RESULTS

A total of 406 CEA operations were performed under general anesthesia. Fifty-three patients (13.1%) met the definition of EPOH. There was no significant difference in the percentage of postoperative stroke/death between patients with and without EPOH during the hospital stay. Patients with EPOH exhibited a higher incidence of postoperative cerebral hyperperfusion syndrome (7.5% vs. 0, P < 0.001), as well as a higher incidence of cerebral hemorrhage (3.8% vs. 0, P < 0.001). The gradient boosted regression trees prediction model achieved an average AUC of 0.77 (95% CI 0.62 to 0.92). When the sensitivity was fixed near 0.90, the model achieved an average specificity of 0.52 (95% CI 0.28 to 0.75).

CONCLUSIONS

We have built the first-ever machine learning-based prediction model for EPOH after CEA. The validation result from our single-center database was very promising. This novel prediction model has the potential to help vascular surgeons identify high-risk patients and reduce related complications more efficiently.

Blood Pressure Management in Afferent Baroreflex Failure: JACC Review Topic of the Week

Afferent baroreflex failure is most often due to damage of the carotid sinus nerve because of neck surgery or radiation. The clinical picture is characterized by extreme blood pressure lability with severe hypertensive crises, hypotensive episodes, and orthostatic hypotension, making it the most difficult form of hypertension to manage. There is little evidence-based data to guide treatment. Recommendations rely on understanding the underlying pathophysiology, relevant clinical pharmacology, and anecdotal experience. The goal of treatment should be improving quality of life rather than normalization of blood pressure, which is rarely achievable. Long-acting central sympatholytic drugs are the mainstay of treatment, used at the lowest doses that prevent the largest hypertensive surges. Short-acting clonidine should be avoided because of rebound hypertension, but can be added to control residual hypertensive episodes, often triggered by mental stress or exertion. Hypotensive episodes can be managed with countermeasures and short-acting pressor agents if necessary.

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.

[Postoperative blood pressure alterations after carotid endarterectomy : Implications of different reconstruction methods]

BACKGROUND

Postoperative blood pressure alterations after carotid endarterectomy (CEA) are associated with an increased risk of morbidity and mortality.

OBJECTIVE

To outline the influence of the two commonly used surgical reconstruction techniques, conventional CEA with patch plasty (C-CEA) and eversion CEA (E-CEA), as well as the innovative carotid sinus-preserving eversion CEA (SP-E-CEA) technique on postoperative hemodynamics, taking the current scientific knowledge into consideration.

METHODS

Assessment of the current clinical and scientific evidence on each operative technique found in the PubMed (NLM) database ranging from 1974 to 2017, excluding case reports.

RESULTS

A total of 34 relevant papers as well as 1 meta-analysis, which scientifically dealt with the described topic were identified. The results of the studies and the meta-analysis showed that E‑CEA correlates with an impairment of local baroreceptor functions as well as with an elevated need for vasodilators in the early postoperative phase, whereas C‑CEA and SP-E-CEA seem to have a more favorable effect on the postoperative blood pressure.

CONCLUSION

The CEA technique influences the postoperative blood pressure regulation, irrespective of the operative technique used. Accordingly, close blood pressure monitoring is recommended at least during the postoperative hospital stay. Further studies are mandatory to evaluate the importance of SP-E-CEA as an alternative to the classical E‑CEA.

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.

Intraoperative management of carotid endarterectomy

First reports on surgical treatment of cerebrovascular atherosclerosis date to the early 1950s. With advancements in surgical technique, carotid endarterectomy (CEA) has become the treatment of choice for patients with both symptomatic and asymptomatic severe carotid stenosis. Given the benefits that surgery offers beyond medical management, the number of CEA procedures continues to increase. The intraoperative management of patients undergoing CEA is challenging because of the combination of patient and surgical factors. This article explores and reviews the literature on anesthetic management and considerations of patients undergoing CEA.

Favorable effects of carotid endarterectomy on baroreflex sensitivity and cardiovascular neural modulation: a 4-month follow-up

Carotid surgery variably modifies carotid afferent innervation, thus affecting arterial baroreceptor sensitivity. Low arterial baroreflex sensitivity is a well-known independent risk factor for cardiovascular diseases. The aim of this study was to assess the 4-mo effects of carotid endarterectomy (CEA) on arterial baroreceptor sensitivity and cardiovascular autonomic profile in patients with unilateral carotid stenosis. We enrolled 20 patients (72 ± 8 yr) with unilateral >70% carotid stenosis. ECG, beat-by-beat blood pressure, and respiration were continuously recorded before and 126 ± 9 days after CEA, at rest and during a 75° head-up tilt. Both pharmacological (modified Oxford technique, BRS) and spontaneous (index α, spectral analysis) arterial baroreflex sensitivity were assessed. Cardiovascular autonomic profile was evaluated by plasma catecholamines and spectral indexes of cardiac sympathovagal modulation [low-frequency R-R interval (LFRR), low frequency-to high frequency ratio (LF/HF), high-frequency R-R interval (HFRR)] and sympathetic vasomotor control [low-frequency systolic arterial pressure (LFSAP)] obtained from heart rate and SAP variability. After CEA, both the index α and BRS were higher (P < 0.02) at rest. SAP variance decreased both at rest and during tilt (P < 0.02). Before surgery, tilt did not modify the autonomic profile compared with baseline. After CEA, tilt increased LF/HF and LFSAP and reduced HFRR compared with rest (P < 0.02). Four months after CEA was performed, arterial baroreflex sensitivity was enhanced. Accordingly, the patients' autonomic profile had shifted toward reduced cardiac and vascular sympathetic activation and enhanced cardiac vagal activity. The capability to increase cardiovascular sympathetic activation in response to orthostasis was restored. Baroreceptor sensitivity improvement might play an additional role in the more favorable outcome observed in patients after carotid surgery.

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. 

Carotid Sinus Nerve Blockade to Reduce Blood Pressure Instability Following Carotid Endarterectomy: A Systematic Review and Meta-analysis

OBJECTIVES

Local anaesthetic infiltration into the carotid sinus during carotid endarterectomy (CEA) has been recommended to minimise blood pressure fluctuations but its use remains controversial. The aim of this meta-analysis was to determine whether intra-operative administration of local anaesthetic reduces the incidence of haemodynamic instability following CEA.

MATERIALS AND METHODS

A search of the Medline, Pubmed and Embase databases and the Current Controlled Trials register identified four trials, which met the pre-defined inclusion criteria for data extraction. Pooled odds ratios with 95 per cent confidence intervals (c.i.) for the development of post-operative hypotension and hypertension were calculated using a random-effects model.

RESULTS

Outcomes of 432 patients were studied. Local anaesthetic blockade of the carotid sinus was associated with a pooled odds ratio of 1.25 (95 per cent c.i. 0.496 to 3.15); p=0.216) and 1.28 (95 per cent c.i. 0.699 to 2.33; p=0.428) for the development of post-operative hypotension and hypertension respectively. Although none reach significance there was a trend towards increased risk of developing a complication in those patients who received local anaesthetic.

CONCLUSIONS

There are insufficient data to determine the role of intra-operative local anaesthetic administration in reducing post-operative blood pressure lability following CEA. Conversely, the possibility of harm cannot be excluded on the basis of the currently available data.

Noninvasive investigation of autonomic activity after carotid stenting or carotid endarterectomy

OBJECTIVE

Carotid artery stenting (CAS) has been introduced as an alternative to carotid endarterectomy (CEA) for the treatment of carotid artery stenosis. Both techniques seem to be associated with postoperative hemodynamic lability. Both may induce baroreceptor dysfunction, possibly leading to transient impairment of cardiovascular autonomic activity and resulting in hemodynamic instability. This instability might contribute to postoperative morbidity. To elucidate these phenomena, we studied the cardiac baroreflex and autonomic cardiovascular control after CAS and CEA.

METHOD

In 20 patients scheduled for CAS (n = 10) or CEA (n = 10), intra-arterial pressures and electrocardiograms were recorded during 10 minutes before and 8 and 24 hours after the procedure. Spontaneous cardiac baroreflex sensitivity was assessed using the sequence method and cross-spectral analysis. In addition, cardiovascular autonomic activity was investigated using spectral analysis of heart rate variability and systolic arterial pressure variability.

RESULTS

After CAS, we demonstrated an increase of the spontaneous baroreflex sensitivity median (interquartile range) from 5.6 (5.1 to 6.2) ms/mm Hg before the procedure to 8.8 (6.8 to 10.5) ms/mm Hg and 7.7 (3.9 to 8.6) ms/mm Hg (P < .001), 8 and 24 hours after the procedure. This was consistent with the increase of the high frequency component of heart rate variability reflecting cardiac parasympathetic activity and a decrease of the low frequency of systolic arterial pressure variability reflecting sympathetic vascular activity. The postoperative period was also associated with decreased systolic arterial pressure from 173 (162 to 190) mm Hg at baseline to 122 (109 to 143) mm Hg and 136 (121 to 143) mm Hg at 8 and 24 hours after CAS (P < .001). No changes in baroreflex sensitivity or in autonomic activity were observed after CEA.

CONCLUSIONS

These preliminary data suggest that CAS is associated with parasympathetic predominance postoperatively and may probably explain the lower systolic arterial pressure observed after CAS.

Altered Autonomic Cardiovascular Regulation After Combined Deep and Superficial Cervical Plexus Blockade for Carotid Endarterectomy

Compromised cardiac autonomic modulation can produce cardiovascular disturbances. We investigated whether combined deep and superficial cervical plexus (CP) blockade for carotid endarterectomy (CEA) produces changes in autonomic cardiovascular regulation. To estimate alterations in cardiovascular autonomic control before and after combined CP blockade in 22 patients undergoing CEA, the heart rate (HR) variability, systolic blood pressure (SBP) variability, and baroreflex sensitivity were analyzed. We found that SBP (157 +/- 28 mm Hg versus 191 +/- 38 mm Hg before and after combined CP blockade, respectively) and HR (68 +/- 10 bpm versus 84 +/- 9 bpm) increased after combined CP blockade. The high frequency power of HR variability (3.7 +/- 0.9 versus 2.2 +/- 1.2 ln/ms2) decreased (decrease in parasympathetic drive), whereas the low frequency power of SBP variability (5.5 +/- 4.7 versus 8.6 +/- 9.4 mm Hg2) increased (increase in vascular sympathetic outflow). Baroreflex sensitivity decreased, and this decrease was negatively correlated with a SBP increase (r = -0.455). The present results suggest that combined CP blockade impairs autonomic cardiovascular homeostasis and suggests an association between combined CP blockade and intraoperative or postoperative adverse cardiovascular events in high-risk cardiac patients undergoing CEA that merits further studies.

Carotid endarterectomy impairs blood pressure homeostasis by reducing the physiologic baroreflex reserve

OBJECTIVE

To assess the impact of carotid endarterectomy on blood pressure homeostasis and baroreflex function, with particular reference to the presence or absence of significant contralateral carotid artery disease, we conducted a prospective study in 80 patients with symptomatic extracranial carotid disease undergoing carotid endarterectomy in a regional teaching hospital over 2 years.

METHODS

Patients were divided into two groups: the control group (n = 37) had no significant contralateral carotid disease; patients in the diseased group (n = 23) had either >70% stenosis or occlusion of the contralateral carotid artery. Seventeen patients with abnormal heart rhythms, poor quality recordings, or with intermediate degrees of contralateral carotid stenosis were excluded. Three patients who had previously undergone contralateral carotid endarterectomy were separately evaluated. Atheromatous plaque was removed from carotid lumen and the baroreflex mechanism received direct intraoperative stimulation before and after carotid endarterectomy. The main outcome measures were (1) the hemodynamic response to the carotid endarterectomy, baroreflex sensitivity, and operating set point (the resting blood pressure, which the baroreflex mechanism maintains) before and after removal of the atheromatous plaque, and (2) the responsiveness of the ipsilateral baroreceptor mechanism to direct stimulation. The impact of the presence of contralateral carotid stenosis on these variables was also evaluated.

RESULTS

Patients in the two groups were comparable for preoperative demographic, medication, and hemodynamic variables. Carotid endarterectomy led to a rise in mean arterial pressure from 81.3 +/- 3.9 mm Hg to 103.5 +/- 4.6 mm Hg ( P < .00001) and from 87.6 +/- 4.3 mm Hg to 94.0 +/- 4.5 mm Hg ( P < .003) in the diseased and control groups, respectively. The magnitude of blood pressure response was significantly greater in the diseased group than in the control group ( P < .00001). This hypertensive shift was not accompanied by the expected fall in heart rate. Direct baroreflex stimulation prior to carotid endarterectomy caused a significantly greater response in the diseased group, suggesting sensitization of the ipsilateral carotid baroreceptor in the presence of contralateral carotid disease. Furthermore, the baroreflex response was obliterated after endarterectomy. There were significant reductions in baroreflex sensitivity and a hypertensive shift in the operating set point, the magnitude of which was significantly greater in patients with contralateral carotid disease.

CONCLUSIONS

Carotid endarterectomy impairs blood pressure homeostasis through surgical destruction of the ipsilateral carotid baroreflex mechanism. Patients with contralateral carotid stenosis have a reduced baroreflex reserve and show greater baroreflex dysfunction and hemodynamic instability after endarterectomy. These patients are at greater risk of postendarterectomy complications and should be monitored closely.

Comparison of Catecholamine Hormone Release in Patients Undergoing Carotid Artery Stenting or Carotid Endarterectomy

PURPOSE

To investigate the pattern of catecholamine response in patients undergoing carotid endarterectomy (CEA) or carotid artery stenting (CAS).

METHODS

Adrenaline, noradrenaline, and renin levels were measured at 5 time points in 12 patients undergoing 13 CEAs (1 bilateral) and 13 patients undergoing unilateral CAS. Arterial blood samples were taken at the following time points: (1) after induction in CEA patients or 5 minutes following first contrast injection in CAS patients, (2) 5 minutes following ICA clamp release in surgical patients or deflation of the balloon in the CAS cohort, (3) 60 minutes following ICA clamp release in surgical patients or deflation of the balloon in the CAS cohort, and (4) 24 hours following the procedure. Intraoperative blood pressure and heart rate were recorded using radial arterial monitoring. Changes in adrenaline, noradrenaline, and renin levels are expressed as ratios versus baseline.

RESULTS

Patterns of adrenaline and noradrenaline release were significantly different in patients undergoing CAS and CEA, with much higher and more variable surges of adrenaline and noradrenaline occurring in CEA patients. Adrenaline and noradrenaline levels increased significantly over baseline following carotid artery clamping in patients undergoing CEA (noradrenaline ratio before clamping: 1.54+/-1.25, 24 hours after unclamping: 8.38+/-16.35 [p<0.001]; adrenaline ratio before clamping: 1.12+/-0.49, 60 minutes after unclamping: 17.59+/-19.14 [p<0.001]). Conversely, in patients undergoing CAS, catecholamine levels remained unchanged (noradrenaline ratio before dilation: 0.96+/-0.23, 24 hours after the procedure: 0.92+/-0.32 [p=NS]; adrenaline ratio before dilation: 0.83+/-0.33, 60 minutes after balloon deflation: 0.56+/-0.32 [p=NS]).

CONCLUSIONS

CAS is associated with a significantly less marked catecholamine response than CEA, which may reflect down-regulation of the sympathetic nervous system in response to carotid sinus stimulation during carotid angioplasty.

Effect of lignocaine injection in carotid sinus on baroreceptor sensitivity during carotid endarterectomy

OBJECTIVES

This study was undertaken to test the hypothesis that there is a neural basis for baroreceptor deterioration during carotid endarterectomy (CEA), by investigating intraoperative hemodynamic changes induced by intraluminal carotid stretch stimulation, before and after application of local anesthetic to the adventitial layer of the carotid sinus region.

METHODS

This was a prospective study of 20 patients undergoing elective CEA. During CEA, before removal of the atheroma, intraluminal stretch simulation of the carotid baroreceptors (rub test) was performed before and after injection of 1% lignocaine into adventitial tissue of the artery in the region of the carotid sinus. Continuous measurements of mean arterial blood pressure (MAP), electrocardiographic r-r intervals (R-R), heart rate, cardiac vagal tone, and carotid sinus baroreflex were recorded to determine alterations in baroreceptor function.

RESULTS

Rub test before injection of lignocaine was associated with a decrease in MAP and heart rate and an increase in R-R, cardiac vagal tone, and carotid baroreflex response, indicating a functioning baroreflex. After lignocaine injection and repetition of the rub test, no significant change was seen in MAP, heart rate, R-R, cardiac vagal tone, or carotid baroreflex response, indicating a nonfunctioning baroreflex. Comparing the peak responses to the rub test stimulus before and after lignocaine injection showed significant differences for all variables (P <.05), with carotid baroreflex response and heart rate being highly significant (P <.0005).

CONCLUSIONS

The baroreflex response to intraluminal stretch stimulation of the carotid sinus area is operational in patients undergoing CEA, and this response is abolished by infiltration of local anesthetic into the periadventitial tissue around the carotid sinus.

Cardiovascular, autonomic, and plasma catecholamine responses in unilateral and bilateral carotid artery stenosis

OBJECTIVE

To determine impairment of baroreceptor afferent activity, which may affect cardiovascular autonomic function in patients with unilateral and bilateral carotid artery stenosis. Comparison was made with normal subjects and hypertensive patients.

METHODS

A series of cardiovascular autonomic function tests along with plasma noradrenaline (norepinephrine) measurements were performed in 46 patients with carotid artery stenosis (CAS); 23 had unilateral and 23 had bilateral stenosis. Comparison was made with 21 hypertensive patients (with a similar degree of raised blood pressure), and 27 normal subjects.

RESULTS

Over a third of patients with unilateral and bilateral CAS had postural hypotension. Heart rate did not rise appropriately in CAS despite the postural fall in blood pressure. Pressor responses in CAS were preserved. Heart rate responses to respiratory stimuli were attenuated. Plasma noradrenaline concentrations rose normally during head up tilt.

CONCLUSION

A substantial proportion with CAS had postural hypotension and attenuated heart rate responses. This was not due to sympathetic vasoconstrictor or cardiac parasympathetic failure, thus suggesting impaired afferent baroreceptor activity, probably secondary to involvement of the carotid sinus. Cardiovascular autonomic testing and assessment of postural hypotension and factors enhancing it may be of clinical relevance in such patients, especially as the symptoms of postural hypotension overlap with those due to thromboembolism.

Kidney transplantation improves baroreceptor sensitivity

Kidney transplant recipients as well as patients on hemodialysis frequently share an increased risk of cardiovascular diseases. Besides other factors, modulations in central neural blood pressure regulation have to be considered as a pathogenetic factor. In this study, baroreceptor function as a possible modulator of blood pressure and the activity of the generating components of the sympathetic nervous system were estimated in 20 kidney transplant recipients, 20 normotensive patients on hemodialysis and 20 age-matched volunteers using the sequence analysis technique and Fast Fourier Transformation (FFT). No blood pressure differences could be measured (83.7+/-2.5 vs. 82.5+/-3.8 vs. 79.2+/-2.4 mm Hg). Pulse interval-blood pressure sequences and the slope of delta pulse interval/delta mean arterial blood pressure of these sequences, representing baroreceptor sensitivity, did not differ between kidney transplant recipients and controls (11.2+/-1.4 vs. 13.4+/-1.3 ms/mm Hg), whereas in hemodialysis patients a reduced baroreceptor sensitivity (5.2+/-1.2 ms/mm Hg) was detected. The 66-129 mHz component (Mayer waves) of heart rate and blood pressure spectrum in normals (650+/-57 and 630+/-70 modulus) significantly (p<0.05) exceeded its equivalent in kidney transplant recipients (430+/-32 and 452+/-27 modulus) and patients on hemodialysis (375+/-38 and 394+/-40 modulus). In conclusion, our study provided evidence that both in kidney transplant and dialysis patients a decreased activity of the generating compounds of the sympathetic nervous system can be detected as compared to healthy volunteers. In contrast to hemodialysis patients, the baroreceptor sensitivity is unaffected in kidney transplant recipients and may, therefore, not contribute to the development of cardiovascular diseases.

Thalamic hemorrhage following carotid endarterectomy-induced labile blood pressure: controlling the liability with clonidine--a case report

Carotid endarterectomy can lead to alterations in baroreceptor sensitivity. Impairment of this sensitivity can in turn lead to volatility of blood pressure (baroreflex failure syndrome--BFS). Rapid elevations in blood pressure can cause hypertensive encephalopathy in a patient with BFS. A patient is presented with hypertensive intracerebral hemorrhage associated with BFS.