Blood pressure responses after carotid surgery: relationship to postoperative baroreceptor sensitivity

Carotid Artery Revascularization Improves Cardiac Sympathetic Nerve Activity in Patients With Carotid Artery Stenosis

BACKGROUND

The carotid sinus baroreceptor reflex controls the neural regulation of blood pressure. Baroreceptor disorders due to carotid sinus atherosclerosis have detrimental cardiovascular effects. This study investigated the medium-term effects of carotid artery revascularization (CAR) on sympathetic and cardiac function and systemic blood pressure variability in patients with carotid artery stenosis.

METHODS

This study included 21 consecutive patients (median age 70 years, 18 men) with carotid artery stenosis scheduled for CAR. ¹²³I metaiodobenzylguanidine (MIBG) scintigraphy, echocardiography, brain natriuretic peptide levels, 24-h Holter electrocardiography (ECG), and ambulatory blood pressure monitoring assessed approximately 3 months postoperatively were compared to preoperative data.

RESULTS

All 21 enrolled patients underwent CAR. Carotid artery stenting was done in three patients with cardiovascular risk or anatomical difficult for carotid endarterectomy. The mean common carotid artery end-diastolic velocity improved significantly (P < 0.01) by 1.6-fold, from 10.8 ± 3.2 to 16.1 ± 7.1 cm/s. In ¹²³I-MIBG scintigraphy, the heart-to-mediastinum (H/M) count ratio was significantly higher than preoperatively (from 2.66 ± 0.48 to 2.86 ± 0.56, P = 0.03). Holter ECG analysis revealed a significant decrease in the low-frequency/high-frequency (LF/HF) ratio compared to preoperatively (from 2.17 ± 1.20 to 1.62 ± 0.68, P = 0.04). These findings suggest decreased myocardial sympathetic activation. In echocardiography, the tissue Doppler-derived e' increased, and E/e' decreased significantly (P < 0.05) from 11.7 ± 5.1 to 10.1 ± 4.0, suggesting an improved left ventricular diastolic capacity. The mean 24-h and nighttime blood pressures were unchanged.

CONCLUSIONS

CAR in patients with carotid stenosis may provide medium-term improvement in cardiac sympathetic nerve activity and left ventricular diastolic dysfunction.

Carotid Endarterectomy with Autoarterial Remodeling of Bifurcation of the Common Carotid Artery and Carotid Endarterectomy with Patch Closure: Comparison of Methods

BACKGROUND

The objectives of our research were to identify whether the new method of carotid endarterectomy (CEA) with autoarterial remodeling of bifurcation of the common carotid artery (ARBCCA) influences daily parameters of blood pressure and heart rate (HR) while monitoring them on a daily basis and to assess the efficacy of the suggested method.

MATERIALS AND METHODS

It is a prospective randomized comparative study. The first group (n = 100) included patients that underwent ARBCCA, the second group (n = 100) included patients that underwent "classic" CEA with xenopericardial patch closure. Diurnal Holter recording of blood pressure and (HR) was performed before and after the surgical treatment in both groups.

RESULTS

Surgical treatment in both groups leads to an increase of HR, arterial hypertension time index by systolic blood pressure, and arterial hypertension time index by diastolic arterial blood pressure. The damage of carotid artery bulb increases sympathetic innervation and causes dysregulation of the baroreceptor mechanism.

CONCLUSIONS

In our study, we did not reveal a significant difference in the incidence of postoperative hypertension and the dependence of HR on the choice of surgical technique. Thus, the proposed ARBCCA method does not lead to an increased risk of pre-existing arterial hypertension development. A significant difference is found out on the parameter of the clamping time of carotid arteries in favor to ARBCCA group. Another advantage of the suggested technique is the number of restenosis greater than 50% during the 2-year follow-up (4 [4%] cases (ARBCCA group) versus 12 [12%] cases ["classic" CEA], respectively, P = .037).

Autonomic function testing: Compliance and consequences

BACKGROUND

The deep breathing test (DB) and Valsalva maneuver (VM) are used to detect autonomic dysfunction. The VM induces sympathetically mediated changes in blood pressure (phase II late, phase IV, and recovery time) and both tests induce vagally mediated heart rate changes. There is limited information on effects of key variables, compliance with testing and the effects of non-compliance This study has twin goals of evaluating compliance with standard instructions and the effects of changes in key variables. We also evaluated the effect of position on the VM.

MATERIAL AND METHODS

Forty healthy males performed DB at air exchange volumes of 50, 80, and 100% of vital lung capacity (VLC). The VM was performed at 40 and 30mmHg expiratory pressure for 15 and 10s in sitting and supine position, respectively.

RESULTS

Participants performed DB at lower volumes than intended and were not able to maintain 100% VLC for the duration of the test. The DB heart rate response decreased 6.3beats/min per liter below VLC. During the VM, subjects blew at lower pressures than instructed. The VM responses were significantly larger with longer expiration durations, higher expiratory pressures and when performed sitting. Performing the VM at 40mmHg for 10s in supine position increased the odds ratio of experiencing flat-top responses.

CONCLUSION

The ability of subjects to strictly comply with methodological guidelines significantly improves results. Recording of both test parameters and ensuing results is suggested.

[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.

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.

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.

Carotid artery stenting and endarterectomy have different effects on heart rate variability

OBJECTIVE

Due to their close proximity to the carotid sinus baroreceptor region, carotid endarterectomy (CEA) and carotid angioplasty/stenting (CAS) carry an inherent risk of affecting baroreflex-mediated regulation of the heart rate. Variations in the heart rate can be studied by measuring heart rate variability (HRV), in which distinct frequency bands in the power spectrum represent sympathetic and parasympathetic modulations on sinus node pacemaker activity. We aimed to investigate the influence of CEA and CAS on HRV.

METHODS

One-hour recordings of R-R intervals on ECG were obtained before and after CEA (10 patients) or CAS (12 patients). The power spectrum of the R-R time series was estimated using the FFT technique. The power in low frequency (LF) and high frequency (HF) bands were computed and normalized to their total power (TP). The LF/HF ratio, an index of sympathovagal balance, was calculated.

RESULTS

Compared to preoperative levels, LF/HF exhibited 85%, 96%, and 70% increase on the second, third, and fourth days after CEA, respectively. In contrast, LF/HF decreased by 26%, 32%, and 26% on the respective days following CAS; the difference between groups was significant (p=0.0069). Normalized LF increased after CEA and decreased after CAS, while the opposite was observed for normalized HF (p=0.0217). There was no significant change in TP.

CONCLUSIONS

CEA and CAS have differential effects on the sympathovagal balance on the heart. The relative increase in sympathetic modulation after CEA and parasympathetic modulation after CAS are likely mediated by alterations in the sensitivity of carotid sinus baroreceptors. Altered cardiac autonomic modulation may play a role in the occurrence of cardiac disturbances following carotid interventions.

Cerebral hyperperfusion syndrome

Cerebral hyperperfusion syndrome (CHS) after carotid endarterectomy is characterised by ipsilateral headache, hypertension, seizures, and focal neurological deficits. If not treated properly it can result in severe brain oedema, intracerebral or subarachnoid haemorrhage, and death. Knowledge of CHS among physicians is limited. Most studies report incidences of CHS of 0-3% after carotid endarterectomy. CHS is most common in patients with increases of more than 100% in perfusion compared with baseline after carotid endarterectomy and is rare in patients with increases in perfusion less than 100% compared with baseline. The most important risk factors in CHS are diminished cerebrovascular reserve, postoperative hypertension, and hyperperfusion lasting more than several hours after carotid endarterectomy. Impaired autoregulation as a result of endothelial dysfunction mediated by generation of free oxygen radicals is implicated in the pathogenesis of CHS. Treatment strategies are directed towards regulation of blood pressure and limitation of rises in cerebral perfusion. Complete recovery happens in mild cases, but disability and death can occur in more severe cases. More information about CHS and early institution of adequate treatment are of paramount importance in order to prevent these potentially severe complications.

Characteristics of 100 consecutive patients presenting with orthostatic hypotension

OBJECTIVE

To elucidate the demographic and clinical characteristics of a consecutive series of patients who presented for evaluation of orthostatic hypotension.

PATIENTS AND METHODS

From January 1, 1997, through September 30, 2001, we assessed retrospectively the demographic and clinical characteristics, antihypertensive medication use, and blood pressure variability in 100 consecutive patients with orthostatic hypotension who underwent 24-hour ambulatory blood pressure monitoring (OH group) and in a convenience sample of 100 age-matched patients who underwent 24-hour ambulatory blood pressure monitoring for evaluation of hypertension (HTN group).

RESULTS

The OH group had a mean +/- SD age of 71.6 +/- 9.4 years, and 42% were women. The most common symptoms were light-headedness and weakness. Comorbid conditions included neurologic diseases (38%), preexisting hypertension (36%), hyperlipidemia (31%), cardiac arrhythmias and coronary artery disease (45%), and neoplasm (28%). During ambulatory blood pressure monitoring, postprandial decreases in blood pressure were noted in 83% of the OH group, supine or sleep hypertension in 84%, and noncompensatory heart rate variability in 75%. Findings on autonomic testing were abnormal in 99% of patients, serum creatinine value was increased in 30%, proteinuria was present in 27%, and left ventricular hypertrophy was present in 20%.

CONCLUSIONS

Orthostatic hypotension is present in a heterogeneous group of disease states, is usually symptomatic, and is often associated with an abnormal blood pressure profile of reversal of circadian pattern, postprandial hypotension, and noncompensatory heart rate variability. Consequent target organ (kidney) damage can be as frequent as in patients who undergo 24-hour ambulatory blood pressure monitoring for evaluation of hypertension.

Cerebral hyperperfusion syndrome after carotid endarterectomy: predictive factors and hemodynamic changes

PURPOSE

It is believed that cerebral hyperperfusion syndrome (CHS) is caused by loss of cerebral autoregulation resulting from chronic cerebral ischemia and that factors including increased intraoperative cerebral blood flow, ipsilateral or contralateral carotid disease, and postoperative hypertension may cause CHS. We describe our experience with CHS, which diverges from published reports.

MATERIALS AND METHODS

From March 2000 to February 2002 we performed 455 carotid endarterectomy (CEA) procedures in 404 patients at our institution. CHS developed 1 to 8 days (mean, 3.2 +/- 2.5 days) postoperatively in 9 patients (2%), 6 women and 3 men, whose age ranged from 52 to 84 years (mean, 69 +/- 8 years). Indications for surgery in 8 patients without neurologic symptoms were ipsilateral internal carotid artery (ICA) stenoses ranging from 70% to 99% (mean, 80% +/- 7%); the remaining patient had an ipsilateral stroke, with good clinical recovery, 7 weeks before CEA. Only 1 patient had significant contralateral ICA stenosis (70%). However, 5 patients had undergone contralateral CEA within the previous 3 months. CHS symptoms were severe headache in 5 patients, seizures in 3 patients (1 stroke), and visual disturbance and ataxia in 1 patient. All 404 patients (455 cases) underwent intraoperative and early (2 weeks) postoperative carotid artery duplex scanning. The 9 patients with CHS also underwent carotid artery duplex scanning at the time of the neurologic event.

RESULTS

Mean intraoperative ICA volume flow (MICAVF) in the 9 CHS cases was not significantly different from that in the other 446 cases (170 +/- 47 mL/min and 182 +/- 81 mL/min, respectively). However, mean ICA volume flow (481 +/- 106 mL/min) and peak systolic velocity (PSV) (108 +/- 33 cm/s) for the 9 CHS cases measured at onset of symptoms were higher than those for the remaining 446 cases (267 +/- 87 mL/min and 80 +/- 26 cm/s, respectively) (P <.01). Of the 9 patients with CHS, only 3 had systolic blood pressures more than 160 mm Hg at onset of symptoms. Severity of ipsilateral and contralateral ICA stenoses was not significantly different between the 9 CHS cases and the remaining 446 cases.

CONCLUSIONS

These data do not corroborate the common belief that CHS occurs preferentially in patients with severe ipsilateral or contralateral carotid disease, increased intraoperative cerebral perfusion, or severe hypertension. Recently performed contralateral CEA (<3 months) appears to be predictive of CHS.

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.

Acute pulmonary edema associated with placement of waist-high, custom-fit compression stockings

Compression stockings are a safe, noninvasive treatment for patients with symptomatic orthostatic hypotension due to autonomic nervous system dysfunction. In this report, we describe a 75-year-old man who had development of pulmonary edema approximately 45 minutes after placement of compression stockings on the first postoperative day following a carotid endarterectomy. No sudden changes were noted on an electrocardiogram or echocardiogram or in the cardiac isoenzymes associated with the pulmonary edema. The patient had a history of coronary artery disease, diabetes mellitus-induced autonomic nervous system dysfunction, and recent surgery near the carotid baroreceptor. All these factors may have limited his ability to compensate for a rapid increase in central blood volume. The temporal relationship of the patient's respiratory distress to the placement of the compression stockings, in the absence of laboratory findings of primary cardiac dysfunction, make stocking-related fluid shift the likely precipitating event in the formation of acute pulmonary edema. This case suggests that compression stockings should be used with caution in patients with limited cardiac reserve.

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.

Hypertensive encephalopathy after bilateral carotid endarterectomy

BACKGROUND

Hypertension occurs frequently after carotid endarterectomy and may lead to cerebral vascular complications and myocardial infarction. Its pathophysiology has recently been related to surgically induced damage of carotid baroreceptors.

CASE DESCRIPTION

A 45-year-old normotensive man with no history of epilepsy was admitted 3 weeks after bilateral carotid endarterectomy for severe repetitive paroxysmal headaches, vomiting, and agitation that were closely associated with attacks of marked hypertension. During one of these attacks, he had a grand mal seizure. Plasma catecholamine levels during hypertensive attacks were highly elevated despite the absence of pheochromocytoma, reflecting abnormalities in baroreceptor sensitivity that lead to unrestrained activation of the central sympathetic nervous system. Heart rate response to Valsalva maneuver showed suppression of the usual tachycardia, indicating baroreceptor reflex insensitivity.

CONCLUSIONS

We report the first case of hypertensive encephalopathy associated with baroreflex failure syndrome after bilateral carotid endarterectomy. The role of blood pressure monitoring may be critical in revealing carotid baroreceptor insensitivity in such clinical settings.