Biomechanical Aspects of Closing Approaches in Postcarotid Endarterectomy

The carotid bifurcation tends to develop atherosclerotic stenoses which might interfere with cerebral blood supply. In cases of arterial blockage, the common clinical solution is to remove the plaque via carotid endarterectomy (CEA) surgery. Artery closure after surgery using primary closures along the cutting edge might lead to artery narrowing and restrict blood flow. An alternative approach is patch angioplasty which takes longer time and leads to more during-surgery complications. The present study uses numerical methods with fluid-structure interaction (FSI) to explore and compare the two solutions in terms of hemodynamics and stress and strain fields developed in the artery wall.

Syncope and hypotension associated with carotid sinus hypersensitivity in a patient with nasopharyngeal carcinoma: A case report

RATIONALE

Carotid sinus hypersensitivity (CSH) is traditionally classified into 3 subgroups: cardioinhibitory, vasodepressor, and mixed subtypes. However, the underlying mechanism of CSH in head and neck cancer is controversial. Several pathological mechanisms of CSH have been proposed: atherosclerotic noncompliance, sternocleidomastoid proprioceptive denervation, and generalized autonomic dysfunction.

PATIENT CONCERNS

We reported a 75-year-old man who had recurrent syncope attacks secondary to hypotension and reduced plasma norepinephrine (NE) levels. CSH was suspected when carotid massage induced syncope-like symptom.

DIAGNOSES

Nasopharynx carcinoma with regional lymph node involvement and CSH.

INTERVENTIONS

On admission, dopamine was administered to maintain the blood pressure. When NE deficiency was confirmed, intravenous NE combined with oral midodrine replaced the dopamine treatment.

OUTCOMES

The syncopal episodes completely resolved with periodic occurrence of hypertension.

LESSONS

Our case suggests a potential role of carotid sinus in regulating the release of NE in adrenal gland and that the monitoring of catecholamine level is recommended in the CSH cases either from head and neck tumors or other mechanical manipulation of carotid sinus.

Usefulness of Tilt Testing and Carotid Sinus Massage for Evaluating Reflex Syncope

Thirty years ago Tilt Testing (TT) was described as a tool in the diagnostic work-up of vasovagal syncope; after its initial success, some flaws have become evident. The concept of hypotensive susceptibility has provided the test a new relevance, shifting from diagnosis only, to therapeutic management. Carotid Sinus Massage (CSM) was introduced at the beginning of the XX century; the technique has evolved over years, whereas the concept of carotid sinus syndrome (CSS) has remained unchanged and uncontested for more than half a century. Nowadays, CSS is a matter of debate, with new classifications and criteria coming on the scene. Recently, a common central etiological mechanism has been hypothesized for reflex syncope, manifesting as CSS, vasovagal syncope or both. In this context, TT and CSM acquire an important role in clinical practice, being essential for a complete diagnosis and treatment. Recalling their historical background, the present paper illustrates an actual interpretation of TT and CSM.

Endovascular Baroreflex Amplification for Resistant Hypertension

Purpose of review

Most hypertension devices have been designed to interrupt or modify the sympathetic nervous system, which seems to be unbalanced in hypertension. Carotid baroreceptors play a pivotal role in maintaining adrenergic balance via a direct feedback interface and would be an exceptional target for intervention. The purpose of this review is to define the role of the baroreceptor in hypertension, to examine device-based therapies targeting the baroreflex and to explore future promises of endovascular baroreflex amplification (EBA).

Recent findings

In the last two decades, two therapeutic strategies targeting the carotid baroreceptor have evolved: baroreflex activation therapy (BAT) and EBA. Both therapies enhance baroreceptor activity, either directly by electrical stimulation or indirectly by changing the geometric shape of the carotid sinus and increasing pulsatile wall strain.

Summary

By showing a significant, sympathetic inhibition-mediated effect on blood pressure, BAT has laid the foundation for baroreflex-targeting therapies for resistant hypertension. EBA is a less invasive therapy with promising first-in-man study results. Ongoing randomized sham-controlled trials are needed to better understand efficacy, durability, and long-term safety and define phenotypes that may most benefit from this treatment.

Electronic supplementary material

The online version of this article (10.1007/s11906-018-0840-8) contains supplementary material, which is available to authorized users.

[A severe stroke following carotid sinus massage]

BACKGROUND

Carotid sinus massage is a widely used method for diagnosis and treatment of supraventricular tachycardia and carotid sinus hypersensitivity. Complications, mostly neurological, can occur but are rare. Carotid stenosis is a risk factor for complications. Hearing a carotid bruit on auscultation indicates stenosis, and is a contraindication for performing carotid sinus massage. However, the sensitivity of auscultation is insufficient.

CASE DESCRIPTION

A 71-year-old man with a history of hypertension and hypercholesterolemia presented to the cardiology accident and emergency department with palpitations. A supraventricular tachycardia was found on examination, for which carotid sinus massage was performed. The patient developed severe aphasia and right-sided hemiparesis caused by an extensive stroke, and died a few days later.

CONCLUSION

The chance of complications following carotid sinus massage is slight; however, this type of complication can have severe consequences. Safer alternative methods may be used for patients with supraventricular tachycardia. In older patients with vascular risk factors, more extensive diagnostic investigations for carotid stenosis should be considered in the diagnostic workup for carotid sinus hypersensitivity.

Acute Device-Based Blood Pressure Reduction: Electrical Activation of the Carotid Baroreflex in Patients Undergoing Elective Carotid Surgery

Carotid sinus baroreceptors are involved in controlling blood pressure (BP) by providing input to the cardiovascular regulatory centers of the medulla. The acute effect of temporarily placing an electrode on the carotid sinus wall to electrically activate the baroreflex was investigated. We studied 11 patients undergoing elective carotid surgery. Baseline BP was 146+30/66±17 mm Hg and heart rate (HR) 72±7 bpm (mean ± standard deviation). An electrode was placed upon the carotid sinus and after obtaining a steady state baseline of BP and HR, an electric current was applied and increased in 1-volt increments. A voltage dependent and highly significant reduction in BP was observed which averaged 18±26* and 8.0±12 mm Hg for systolic BP and diastolic BP, respectively. Maximal reductions occurred at 4.4±1.2 V: 23±24 mm Hg*, 16±10 mm Hg* and 7±12 bpm* for systolic BP, diastolic BP and HR, respectively (= p <.05). Thus, electrical stimulation of the carotid sinus activates the carotid baroreflex resulting in a reduction in BP and HR. This presents a proof of concept for device based baroreflex modulation in acute BP regulation and adds to the available data which provide a rationale for evaluating this system in the context of chronic BP reduction in hypertensive patients.

Safety and tolerability of Tilt Testing and Carotid Sinus Massage in the octogenarians

OBJECTIVE

to evaluate the safety and tolerability of Tilt Testing (TT) and Carotid Sinus Massage (CSM) in octogenarians with unexplained syncope.

METHODS

patients consecutively referred for transient loss of consciousness to the 'Syncope Units' of three hospitals were enrolled. TT and CSM were performed according to the European Society of Cardiology guidelines on syncope. Complications were evaluated in each group. An early interruption of TT was defined as 'intolerance' and considered as a non-diagnostic response.

RESULTS

one thousand four hundred and one patients were enrolled (mean age 72 ± 16 years, male 40.8%). Six hundred and ninety-four patients (49.5%) were 80 years old or older (mean age 83 ± 3 years) and 707 (50.5%) were younger (mean age 60 ± 17 years). Complications after TT occurred in 4.5% of older patients and in 2.1% of the younger ones (P = 0.01). All complications were 'minor/moderate', as prolonged hypotension, observed in ∼3% of patients ≥80 years. Major complications such as sustained ventricular tachycardia, ventricular fibrillation, asystole requiring cardiac massage, transient ischaemic attack, stroke and death were not observed in any patient. The presence of orthostatic hypotension and the mean number of syncopal episodes were predictors of TT complications. Intolerance was reported in 2.4% of older patients and 1% of the younger ones (P = 0.08), mainly due to orthostatic intolerance. No complications occurred after CSM.

CONCLUSIONS

TT and CSM appear to be safe and well tolerated in octogenarians, who should not be excluded by age from the diagnostic work-up of syncope.

[The risk of death caused by cardioinhibitory reflex mechanism is very small]

Danish forensic reports concerning manual strangulation routinely state that any strangulation attempt may pose a danger to life due to a cardioinhibitory reflex mechanism. There are, however, only few case reports in which a cardioinhibitory reflex mechanism was stated as a possible cause of death. Carotid stimulation may induce syncope in patients with carotid sinus syndrome, but is not associated with increased mortality. Experiments with inflatable neck collars has not led to life-threatening arrhythmias. Neck holds used in martial arts are rarely associated with any complications.

Cardioinhibitory Carotid Sinus Syndrome - a mathematical model

Carotid sinus massage (CSM) is a simple clinical test for stimulating the carotid sinus reflex. During CSM, firm longitudinal massage is applied at the point of maximal pulsation over the carotid bifurcation resulting in relative bradycardia. CSM is used to diagnose Cardioinhibitory Carotid Sinus Syndrome (CICSS). CICSS is an age-related disorder, characterized by profound symptomatic cardioinhibition (> 3 seconds pause) following CSM. CICSS prevalence increases with age and is responsible for 1 to 20% of all pacemaker implantations per year. Treatment options for CSS are limited and much debate still remains around its underlying etiology. In this paper we present a first computer simulation of carotid sinus massage (CSM) in older adults and demonstrate its ability to simulate normal heart rate responses to CSM. Importantly we demonstrate that our mathematical model requires inclusion of model elements to simulate autonomic control of perinodal T-cell activity in order to replicate the profound cardioinhibitory response observed in CICSS. Our model findings implicate CSS as a candidate biomarker of biological aging and frailty.

Baroreflex activation for the treatment of hypertension: principles and practice

This article reviews the history and current status of an innovative nonpharmacological approach for the treatment of resistant hypertension - chronic electrical activation of the afferent limb of the carotid baroreflex. Recent studies in both normotensive and hypertensive canine models have unambiguously demonstrated sustained and clinically relevant reductions in arterial pressure and sympathetic activity in the course of prolonged baroreflex activation. Clinical trials designed to evaluate the efficacy and safety of this therapy in patients with resistant hypertension are now underway in both Europe and the USA.

[Case report of cardiac arrest during carotid body tumor resection]

We report a case of 30-second cardiac arrest that occurred during carotid body tumor resection due to the carotid sinus reflex. The patient was a 20-year-old man diagnosed with a carotid body tumor and scheduled for tumor resection. General anesthesia was induced and maintained with target controlled infusion of propofol. Analgesia was achieved with continuous administration of remifentanil. When the surgery was initiated, 1% lidocaine 3 ml was locally injected into the carotid bifurcation. When surgery was initiated in the neck region, the patient developed sudden cardiac arrest. Chest compression was immediately initiated, and atropine 0.5 mg was administered; subsequently circulation was restored. Surgery was resumed after placing a temporary pacemaker through the left subclavian vein. The surgery was successfully performed without any other bradycardia complications, and the patient recovered from general anesthesia without sequelae. Thus, the findings indicate the importance of considering the pacemaker placement before carotid body tumor resection.

Carotid body denervation prevents the development of insulin resistance and hypertension induced by hypercaloric diets

Increased sympathetic activity is a well-known pathophysiological mechanism in insulin resistance (IR) and hypertension (HT). The carotid bodies (CB) are peripheral chemoreceptors that classically respond to hypoxia by increasing chemosensory activity in the carotid sinus nerve (CSN), causing hyperventilation and activation of the sympathoadrenal system. Besides its role in the control of ventilation, the CB has been proposed as a glucose sensor implicated in the control of energy homeostasis. However, to date no studies have anticipated its role in the development of IR. Herein, we propose that CB overstimulation is involved in the etiology of IR and HT, core metabolic and hemodynamic disturbances of highly prevalent diseases like the metabolic syndrome, type 2 diabetes, and obstructive sleep apnoea. We demonstrate that CB activity is increased in IR animal models and that CSN resection prevents CB overactivation and diet-induced IR and HT. Moreover, we show that insulin triggers CB, highlighting a new role for hyperinsulinemia as a stimulus for CB overactivation. We propose that CB is implicated in the pathogenesis of metabolic and hemodynamic disturbances through sympathoadrenal overactivation and may represent a novel therapeutic target in these diseases.

Recurrent episodes of asystole from carotid sinus hypersensitivity triggered by positioning for head and neck surgery

BACKGROUND

We present a case report of a patient with recurrent thyroid carcinoma, previously treated with surgery and radiotherapy, who developed asystolic episodes on 2 occasions as the result of positioning of the neck in hyperextension for head and neck surgery.

METHODS AND RESULTS

In carotid sinus hypersensitivity (CSH), the carotid sinus reflex is greatly exaggerated, resulting in profound bradycardia and asystole. Predisposing risk factors for the development of CSH in this patient included history of previously treated head and neck cancer and the presence of tight surgical scars. His negative cardiovascular history, the time sequence between neck positioning and asystole, and the fact that asystole recurred during the second surgery strongly suggest that CSH was precipitated by hyperextension of the neck during positioning.

CONCLUSIONS

A heightened awareness of this syndrome, close monitoring, and preparedness for timely diagnosis and management are essential for a successful outcome.

Chronic lowering of blood pressure by carotid baroreflex activation: mechanisms and potential for hypertension therapy

Recent technical advances have renewed interest in device-based therapy for the treatment of drug-resistant hypertension. Findings from recent clinical trials regarding the efficacy of electric stimulation of the carotid sinus for the treatment of resistant hypertension are reviewed here. The main goal of this article, however, is to summarize the preclinical studies that have provided insight into the mechanisms that account for the chronic blood pressure-lowering effects of carotid baroreflex activation. Some of the mechanisms identified were predictable and confirmed by experimentation. Others have been surprising and controversial, and resolution will require further investigation. Although feasibility studies have been promising, firm conclusions regarding the value of this device-based therapy for the treatment of resistant hypertension awaits the results of current multicenter trials.

[Permanent cardiac pacing in vasovagal syncope and carotid sinus syndrome]

Vasovagal syncope and carotid sinus syndrome are common conditions in young and elderly people, respectively, mostly with benign prognosis. Nevertheless, severe or "malignant" syncopal attacks in some patients may be associated with life-threatening injury. Unfortunately, up to now almost all drug trials have failed to demonstrate any benefit in preventing syncope and interventional approach (pacemaker) may be appropriate. This article contains literature review and discussion of indications for pacing in vasovagal syncope and carotid sinus syndrome.

Chronic electrical stimulation of the carotid sinus baroreflex improves left ventricular function and promotes reversal of ventricular remodeling in dogs with advanced heart failure

BACKGROUND

Autonomic abnormalities exist in heart failure and contribute to disease progression. Activation of the carotid sinus baroreflex (CSB) has been shown to reduce sympathetic outflow and augment parasympathetic vagal tone. This study tested the hypothesis that long-term electric activation of the CSB improves left ventricular (LV) function and attenuates progressive LV remodeling in dogs with advanced chronic heart failure.

METHODS AND RESULTS

Studies were performed in 14 dogs with coronary microembolization-induced heart failure (LV ejection fraction ≈25%). Eight dogs were chronically instrumented for bilateral CSB activation using the Rheos System (CVRx Inc, Minneapolis, Minn) and 6 were not and served as controls. All dogs were followed for 3 months, and none received other background therapy. During follow-up, treatment with CSB increased LV ejection fraction 4.0±2.4% compared with a reduction in control dogs of −2.8±1.0% (P<0.05). Similarly, treatment with CSB decreased LV end-systolic volume -2.5±2.7 mL compared with an increase in control dogs of 6.7±2.9 mL (P<0.05). Compared with control, CSB activation significantly decreased LV end-diastolic pressure and circulating plasma norepinephrine, normalized expression of cardiac β(1)-adrenergic receptors, β-adrenergic receptor kinase, and nitric oxide synthase and reduced interstitial fibrosis and cardiomyocyte hypertrophy.

CONCLUSIONS

In dogs with advanced heart failure, CSB activation improves global LV function and partially reverses LV remodeling both globally and at cellular and molecular levels.

[A case of carotidynia with carotid sinus hypersensitivity]

A 71-year-old man presented with acute, right-sided neck pain and marked falls in blood pressure in response to cervical extension/rotation. Enhanced CT of the right carotid artery showed wall thickening and soft tissue enhancement surrounding the vessel. Ultrasonography demonstrated wall thickening and marked acceleration of the blood flow velocity. [18F] fluorodeoxyglucose (18F-FDG) positron-emission tomography (PET)-CT revealed increased FDG activity in the area of the right carotid bulb. The patient's symptoms resolved in 2 weeks with nonsteroidal anti-inflammatory drug; regression of wall thickening and decreased velocity were observed on follow-up ultrasonography. A carotid inflammatory process due to carotidynia in addition to atherosclerosis may increase carotid sinus baroreceptor stimulation, resulting in the onset of carotid sinus hypersensitivity.

Results of carotid sinus massage in a tertiary referral unit--is carotid sinus syndrome still relevant?

BACKGROUND

carotid sinus hypersensitivity (CSH) is associated with syncope, drop attacks and unexplained falls in older people. However, a recent study has also reported a prevalence of 35% in asymptomatic community-dwelling older people.

OBJECTIVE

we conducted a retrospective observational study to investigate the haemodynamic and symptom responses of a large cohort of patients undergoing carotid sinus massage (CSM).

METHODS

the electronically stored haemodynamic data of 302 consecutive patients, aged 71 +/- 11 years, investigated with CSM for unexplained falls and syncope was analysed. Bilateral sequential CSM was performed in the supine and upright positions with continuous electrocardiogram (ECG) and non-invasive beat-to-beat blood pressure monitoring (Taskforce, CN Systems, Austria). CSH (CSH) was defined by maximal R-R interval > or =3 s (cardioinhibitory) and/or a systolic blood pressure drop of > or =50 mmHg (vasodepressor).

RESULTS

a total of 74/302 (25%) subjects had CSH, 37 (50%) of which were cardioinhibitory (CI) and 37 (50%) were vasodepressor (VD) subtypes. Subjects with positive CSM were significantly older (75.2 vs 70.2 years, P < 0.001), and more likely to be male (32% vs 19%, P < 0.01). CSH was diagnosed with right-sided CSM alone in 45 (61%) subjects and erect CSM only in 36 (49%) subjects. Symptom reproduction was more likely with the CI than the VD subtypes (82% vs 28%; P < 0.001).

CONCLUSION

CSH was diagnosed in 25% of patients investigated with CSM at our specialist unit, lower than the prevalence of 39% reported for community-dwelling older individuals. This discrepancy may be explained by selection bias and demographic differences, but raises the possibility of CSH being an age-related epiphenomenon rather than a causal mechanism for syncope, drop attacks and unexplained falls. Our observations have important implications for clinical practice and the development of future research strategies.

Determinants of a positive response to carotid sinus massage and head-up tilt testing

BACKGROUND

Orthostatic hypotension (OH) and carotid sinus hypersensitivity (CSH) are common causes of syncope in older people. The aim of this study was to determine if patient's age, sex and presenting symptoms influence the result of carotid sinus massage and head-up tilt testing.

METHODS

Retrospective analysis of the database and reports was carried out between 1995 and 2006 at a tertiary referral centre. Patient's age, sex, presenting symptoms and test result were examined. Presenting symptoms were classified as syncope, falls or dizzy spells.

RESULTS

Of the 1583 tests reported, OH was present in 402 patients (25.4%), of whom 175 (11.1%) were symptomatic. 188 of 1464 (12.8%) patients undergoing carotid sinus massage had evidence of CSH, of which 156 were symptomatic. Male patients were significantly more likely to have symptomatic CSH than female patients (odds ratio 2.28, 95% CI 1.54 to 3.04, p<0.01). There were non-significant trends to increased diagnosis of symptomatic OH with increasing age, male sex and referral with syncope. There were non-significant trends to increased diagnosis of symptomatic CSH with increasing age and referral with syncope.

CONCLUSION

Male sex, increasing age and being referred with syncope were all associated with an increased likelihood of receiving a diagnosis of either OH or CSH. The overall prevalence of CSH was lower than in previous studies, which may reflect different patient populations.

Effective surgical treatment of the carotid sinus sindrome

Elderly patients frequently suffer from dizziness and syncope; however, an underlying disease may not always be identified. Three patients aged 69, 71 and 56, respectively, experienced spells of dizziness and syncope. Massage of the carotid sinus demonstrated the presence of a carotid sinus syndrome (CSS), an abnormal baroreflex response of the carotid sinus that leads to asystole and extreme hypotension. Conventional treatment is generally by insertion of a pacemaker. These patients, however, were referred to the vascular surgery department of our hospital for removal of adventitial layers of proximal portions of the internal carotid artery. Recovery was uneventful; all three are now free of symptoms. CSS should be considered in the differential diagnosis of dizziness and syncope. Surgical denervation of the carotid artery is a valid treatment option, especially in the vasodepressive or mixed type of CSS.

The management of syncope in older adults

Syncope is a frequent symptom in older patients. The diagnostic and therapeutic management may be complex, particularly in older adults with syncope and comorbidities or cognitive impairment. Morbidity related to syncope is more common in older persons and ranges from loss of confidence, depressive illness and fear of falling, to fractures and consequent institutionalization. Moreover, advan-ced age is associated with short and long-term morbidity and mortality after syncope. A standardized approach may obtain a definite diagnosis in more than 90% of the older patients with syncope and may reduce diagnostic tools and hospitalizations. The initial evaluation, including anamnesis, medical examination, orthostatic hypotension test and electrocardiogram (ECG), may be more difficult in the elderly, specially for the limited value of medical history, particularly for the certain diagnosis of neuro-mediated syncope. For this reason neuroautonomic assessment is an essential step to confirm a suspect of neuromediated syncope. Orthostatic blood pressure measurement, head up tilt test, carotid sinus massage and insertable cardiac monitor are safe and useful investigations, particularly in older patients. The most common causes of syncope in the older adults are orthostatic hypotension, carotid sinus hypersensitivity, neuromediated syncope and cardiac arrhythmias. The diagnostic evaluation and the treatment of cardiac syncope are similar in older and young patients and for this reason will not be discussed. In older patients unexplained falls could be related to syncope, particularly in patients with retrograde amnesia. There are no consistent differences in the treatment of syncope between older and younger population, but a specific approach is necessary for orthostatic hypotension, drug therapy and pacemaker implantation.

Carotid baroreflex testing using the neck collar device

A neck chamber device for stimulation of carotid sinus baroreceptors by changing carotid transmural pressure was first described in 1957 by Ernsting and Parry and, with several modifications, has been extensively used in a number of physiological and clinical studies. This article outlines the evolution of neck chamber devices and describes some of the advantages and limitations of the technique. We also describe the responses in healthy subjects and the changes observed in patients with some disorders affecting the autonomic nervous system.

Recurrent syncope due to carotid sinus hypersensitivity and sick sinus syndrome

Syncope is a sudden and brief loss of consciousness with postural tone. Its recovery is usually spontaneous. There are various causes of syncope including cardiac, vascular, neurologic, metabolic and miscellaneous origins. The tracing is usually time-consuming and costly. The diagnosis of carotid sinus syncope may sometimes be difficult since the symptoms are nonspecific, especially in older persons. Here, we report the case of a 72-year-old woman who sought medical attention at our hospital due to repeated syncope episodes over the previous 5 years. Neurologic examinations showed negative results (including brain computed tomography). Twenty-four-hour ambulatory electrocardiogram monitoring showed atrial and ventricular premature contractions only. Electrophysiologic study disclosed prolonged corrected sinus node recovery time (1,737 ms) with poor atrioventricular conduction. Drop of blood pressure together with sinus bradycardia developed after left side carotid sinus massage. Both carotid sinus hypersensitivity with sick sinus syndrome contributed to this patient's syncope, and after pacemaker placement together with selective serotonin reuptake inhibitor treatment, she was free from syncope thereafter.

Ginkgolide B inhibits carotid sinus baroreflex in anesthetized male rats

The effects of ginkgolide B on the carotid sinus baroreflex (CSB) were studied in the perfused isolated carotid sinus of 30 anesthetized Sprague-Dawley male rats. The results were as follows. (1) By perfusing with ginkgolide B (0.1, 1, 10 μmol/L), the functional curve of the baroreflex was shifted to the right and upward. There was a marked decrease in peak slope (PS) and reflex decrease (RD) in mean arterial pressure (P<0.01), while the threshold pressure (TP), equilibrium pressure (EP) and saturation pressure (SP) were significantly increased (P<0.05, P<0.01). Among the functional parameters of CSB, the changes in PS, RD, TP, EP and SP were dose-dependent. (2) Pretreatment with Bay K8644 (500 nmol/L), an agonist of L-type calcium channel, completely eliminated the effects of ginkgolide B (1 μmol/L) on the CSB. (3) Pretreatment with tetraethylammonium (TEA, 1 mmol/L), an inhibitor of potassium channel, completely abolished the above effects of ginkgolide B (1 μmol/L) on the CSB. These results suggest that ginkgolide B inhibits the CSB in anesthetized rats, which is mediated by decreased calcium influx and increased potassium efflux in baroreceptor nerve endings.

[Therapeutic novelties in the management of arterial hypertension]

Arterial hypertension is one of the major risk factors for the development of cardiovascular diseases such as heart failure, ischemic heart disease, chronic kidney disease and cerebrovascular events. Adequate blood pressure control is vital for the management of patients with vascular disease. New therapeutic alternatives are appearing on the horizon to improve the degree of blood pressure control in these patients, such as direct renin inhibitors, beta-blockers with additional properties, carotid receptor- stimulating devices and vaccination against arterial hypertension. Direct renin inhibitors are a new family of antihypertensive drugs that have so far shown a good antihypertensive effect and an additive effect on reduction of proteinuria in patients with diabetic nephropathy. Recent meta-analyses suggest that betablockers used as first-line treatment for uncomplicated arterial hypertension could have a less beneficial effect on the development of cardiovascular disease than other antihypertensive drugs. However, the emergence of new subtypes of beta-blockers with other hemodynamic and metabolic properties could change this conception. Carotid receptor-stimulating devices and vaccination against arterial hypertension, although not totally new therapies, are being revitalized, with preliminary results that suggest that they could be used for the treatment of arterial hypertension in patients with a specific profile. Although scientifically stimulating, the long-term beneficial effects of these new therapeutic alternatives on target-organ protection still need to be confirmed.

[Sinus caroticus syndrome diagnosed after 43 years]

A 63-years-old male suffered from palpitations, syncope and near syncope for 43 years. He had diagnosed paroxystic atrial fibrillation and was treated with betablocade, calcium antagonists, and flecanide with potentially severe complications. Blood tests, electrocardiography, echocardiography and myocardial scintigraphy were all normal. The patient was admitted for drug cessation, and at admittance sinus caroticus massage was performed. The patient developed an 11 second pause in heart rhythm and was diagnosed with sinus caroticus syndrome. After pacemaker implantation, he was free of symptoms.

Chronic baroreceptor activation enhances survival in dogs with pacing-induced heart failure

Much of the current pharmacological therapy for chronic heart failure targets neurohormonal activation. In spite of recent advances in drug therapy, the mortality rate for chronic heart failure remains high. Activation of the carotid baroreceptor (BR) reduces sympathetic outflow and augments vagal tone. We investigated the effect of chronic activation of the carotid BR on hemodynamic and neurohormonal parameters and on mortality in dogs with chronic heart failure. Fifteen dogs were instrumented to record hemodynamics. Electrodes were applied around the carotid sinuses to allow for activation of the BR. After 2 weeks of pacing (250 bpm), electrical carotid BR activation was initiated in 7 dogs and continued for the remainder of the study. The start of BR activation was used as a time reference point for the remaining 8 control dogs that did not receive BR activation. Survival was significantly greater for dogs undergoing carotid BR activation compared with control dogs (68.1+/-7.4 versus 37.3+/-3.2 days, respectively; P<0.01), although arterial pressure, resting heart rate, and left ventricular pressure were not different over time in BR-activated versus control dogs. Plasma norepinephrine was lower in dogs receiving BR activation therapy 31 days after the start of BR activation (401.9+/-151.5 versus 1121.9+/-389.1 pg/mL in dogs not receiving activation therapy; P<0.05). Plasma angiotensin II increased less in dogs receiving activation therapy (plasma angiotensin II increased by 157.4+/-58.6 pg/mL in control dogs versus 10.1+/-14.0 pg/mL in dogs receiving activation therapy; P<0.02). We conclude that chronic activation of the carotid BR improves survival and suppresses neurohormonal activation in chronic heart failure.

Withdrawal of fall-risk-increasing drugs in older persons: effect on tilt-table test outcomes

OBJECTIVES

To determine whether outcomes of tilt-table tests improved after withdrawal of fall-risk-increasing drugs (FRIDs).

DESIGN

Prospective cohort study.

SETTING

Geriatric outpatient clinic.

PARTICIPANTS

Two hundred eleven new, consecutive outpatients, recruited from April 2003 until December 2004.

MEASUREMENTS

Tilt-table testing was performed on all participants at baseline. Subsequently, FRIDs were withdrawn in all fallers in whom it was safely possible. At a mean follow-up of 6.7 months, tilt-table testing was repeated in 137 participants. Tilt-table testing addressed carotid sinus hypersensitivity (CSH), orthostatic hypotension (OH), and vasovagal collapse (VVC). Odds ratios (ORs) of tilt-table-test normalization according to withdrawal (discontinuation or dose reduction) of FRIDs were calculated using multivariate logistic regression analysis.

RESULTS

After adjustment for confounders, the reduction of abnormal test outcomes (ORs) according to overall FRID withdrawal was 0.34 (95% confidence interval (CI)=0.06-1.86) for CSH, 0.35 (95% CI=0.13-0.99) for OH, and 0.27 (95% CI=0.02-3.31) for VVC. For the subgroup of cardiovascular FRIDs, the adjusted OR was 0.13 (95% CI=0.03-0.59) for CSH, 0.44 (95% CI=0.18-1.0) for OH, and 0.21 (95% CI=0.03-1.51) for VVC.

CONCLUSION

OH improved significantly after withdrawal of FRIDs. Subgroup analysis of cardiovascular FRID withdrawal showed a significant reduction in OH and CSH. These results imply that FRID withdrawal can cause substantial improvement in cardiovascular homeostasis. Derangement of cardiovascular homeostasis may be an important mechanism by which FRID use results in falls.

Excessive vomiting abolished by carotid denervation

The carotid sinus syndrome (CSS) is characterized by repetitive syncope due to prolonged heart rate slowing or a profound drop in systolic blood pressure. CSS is due to an inappropriate response of a hypersensitive carotid sinus following pressure on or stretching of the neck. We report on a patient with excessive gagging and vomiting elicited by pressure on the right side of the neck as an aberrant presentation of the carotid sinus syndrome. Her incapacitating symptoms were abolished by a surgical carotid denervation.

Atrial fibrillation induced by carotid sinus massage

A case of atrial fibrillation paroxysm induced by carotid sinus massage is reported in a patient with recurrent episodes of syncope. Despite extensive investigations, no cause for the syncopal episodes was determined.

Effect of continuous arterial blood flow in patients with rotary cardiac assist device on the washout of a stenosis wake in the carotid bifurcation: a computer simulation study

In recipients of rotary blood pumps for cardiac assist, the pulsatility of arterial flow is considerably diminished. This influences the shear stress patterns and streamlines in the arterial bed, with potential influence on washout and plaque growth. These effects may be aggravated in the recirculation area of stenoses, and therefore, exclude patients with atherosclerosis from the therapy with these devices. A numerical study was performed for the human carotid artery bifurcation with the assumption of a massive stenosis (75% reduction of cross-section area) in the carotid bulb. Four different flow time patterns (no support to full pump support) were applied. Flow patterns and particle residence time within the recirculation region were calculated, once within the relevant volume behind the stenosis and and once within a small region directly at the posterior heel of the stenosis. The flow patterns showed a considerable radial vorticity behind the stenosis. Mean particle residence time in the whole recirculation region was 15% less for high pump support (nearly continuous flow) compared to the natural flow pattern (0.19s compared to 0.22s), and nearly identical for the small heel region (0.28 to 0.27s). The flow simulation demonstrates, that even in the case of a pre-existing stenosis, the local effects of continuous flow on particle residence times are rather minimal (as was shown previously for intact arterial geometries). Therefore, from the point of macroscopic flow field analysis, continuous flow should not enhance the thromboembolic risk in ventricular assist device recipients.

Exaggerated carotid sinus massage responses are related to severe coronary artery disease in patients being evaluated for chest pain

BACKGROUND

Previous studies have reported that carotid sinus massage responses are associated with advancing age and carotid or coronary artery disease.

HYPOTHESIS

This study was undertaken to investigate the potential role of carotid sinus hypersensitivity as a marker for the presence of coronary artery disease, and especially left main stem disease, in patients who were referred for evaluation of chest pain.

METHODS

Toward this end, carotid sinus stimulation with simultaneous recordings of the electrocardiogram and aortic pressure was performed before coronary arteriography in 150 selected consecutive patients (mean age 59.4+/-9 years) who were referred for evaluation of chest pain.

RESULTS

Coronary artery disease was present in 118 patients (78.7%); of these, 35 had single-vessel disease, 35 had double-vessel disease, 33 had triple-vessel disease, and 15 had left main stem with or without such vessel disease. Carotid sinus hypersensitivity was found in 40 patients (26.6%). The incidence of hypersensitivity in patients with single-, double-, or triple-vessel disease and left main stem disease was 8.5, 14.2, 57.5, and 73.3%, respectively. Stepwise multiple logistic regression analysis revealed that left main stem disease was significantly and independently related to the presence of carotid sinus hypersensitivity (p < 0.05). In addition, the presence of hypersensitivity had 73.3% sensitivity, 86.2% specificity, and 96.3% negative predictive value for the presence of left main stem disease.

CONCLUSION

In patients being evaluated for suspected ischemic heart disease, carotid sinus massage responses are related to severe coronary disease. The absence of hypersensitivity may reflect absence of left main stem disease.

Carotid sinus hypersensitivity: an age-related phenomenon

A study on patients aged 15–99 years underlines and better defines the known age dependency of carotid sinus hypersensitivity

Electrical stimulation of the carotid sinus for the treatment of resistant hypertension

Hypertension is a major cause of morbidity and mortality worldwide. Despite a myriad of oral agents, many patients fail to reach their target blood pressure. Electrical stimulation of the carotid sinus, an old therapeutic concept, lowers blood pressure by initiating the baroreflex and reducing sympathetic tone. Recent evidence suggests that the baroreflex is more important in the setting of chronic hypertension than originally believed. The carotid stimulator may be a safe and effective therapeutic option for patients with resistant hypertension.

Carotid sinus hypersensitivity associated with focal alpha-synucleinopathy of the autonomic nervous system

A case of an 82-year-old woman who experienced repeated falls is described. She exhibited a cardioinhibitory carotid sinus hypersensitivity after right carotid sinus massage (CSM), but without evidence of orthostatic hypotension. After a pacemaker was implanted, she did not experience any falls, dizziness or syncope. Her balance eventually deteriorated, but she remained cognitively intact and died from lung cancer at the age of 89 years. Neuropathological examination showed only age-related Alzheimer's disease pathology and a few alpha-synuclein-positive granular deposits and neurites in the dorsal nucleus of the vagus and solitary tract nucleus in the medulla, but a marked alpha-synuclein pathology in the stellate ganglia. The cardioinhibitory element of her CSM was possibly because of the alpha-synuclein pathology in the ganglion, which impaired sympathetic transmission. This case shows another phenotype among patients with alpha-synucleinopathy.

Oxygen Mass Transport in a Compliant Carotid Bifurcation Model

The purpose of the present study was to investigate oxygen mass transfer in the human carotid bifurcation, focusing on the effects of the wall compliance and flow field on the temporal variation and spatial distribution of the oxygen wall flux. Details of unsteady convective-diffusive oxygen transport were examined numerically using a compliant model of the human carotid bifurcation and realistic blood flow waveforms. Results reveal that axial flow separation at the outer common-internal carotid wall can significantly alter the flow field, oxygen tension field, and oxygen wall flux distribution. At the outer wall of the sinus, the Sherwood number, Sh (non-dimensional oxygen wall flux), takes on significantly lower values than at other sites due to the attenuation of transport rates by convective flow away from wall. More specifically, the lowest value of Sh was Sh approximately 6 (in the sinus), which is much lower than the value of the non-dimensional oxygen consumption rate (Damkohler number, Da) in the reactive wall tissue (Da=29-39). At the inner wall of the sinus, Sh approximately 170 is far above the expected value of Da. This implies that flow separation on the outer wall of the sinus provides a very strong fluid mechanical barrier to oxygen transport; whereas at the inner wall of the sinus, the mechanism of transport is controlled by the wall consumption rate.

Baroreflex Failure: A Rare Complication of Carotid Paraganglioma Surgery

Multiple head and neck paragangliomas are a rare occurrence. We report a patient with removal of bilateral carotid paragangliomas who subsequently developed baroreflex failure 1 month after surgery. The pathology and physiology of this presentation is extremely interesting because it exhibits the complex homeostatic mechanisms involved in the maintenance of steady-state blood pressure. Although rare, it is important to be aware of baroreflex failure and its variable course. Most postsurgical cases occur within days of surgery but, as this report demonstrates, hypertensive urgency can occur weeks to months after surgery; and if not recognized early, it can lead to disastrous postoperative complications such as stroke and myocardial infarction.

Carotid sinus hypersensitivity in asymptomatic older persons: implications for diagnosis of syncope and falls

BACKGROUND

Carotid sinus hypersensitivity is the most commonly reported cause of falls and syncope in older persons. Recent guidelines recommend 5 to 10 seconds of carotid sinus massage in supine and upright positions with beat-to-beat monitoring. The aim of this study was to determine the prevalence of carotid sinus hypersensitivity in (1) an unselected community sample of older people and (2) a subsample with no history of syncope, dizziness, or falls using recently standardized diagnostic criteria.

METHODS

One thousand individuals older than 65 years were randomly sampled from a single general practice register; 272 participants underwent supine and upright carotid sinus massage with continuous heart rate and phasic blood pressure monitoring. Carotid sinus hypersensitivity was defined as asystole of 3 seconds or greater and/or a drop in systolic blood pressure of 50 mm Hg or greater.

RESULTS

Carotid sinus hypersensitivity was present in 107 individuals (39%); 24% had asystole of 3 seconds or greater during carotid sinus massage; and 16% had symptoms (including syncope) with carotid sinus hypersensitivity. Age (odds ratio, 1.05; 95% confidence interval, 1.00-1.09) and male sex (odds ratio, 1.71; 95% confidence intervals, 1.04-2.82) were the only predictors of carotid sinus hypersensitivity. In 80 previously asymptomatic individuals, carotid sinus hypersensitivity was present in 28 (35%) and accompanied by symptoms in 10. The 95th percentile for carotid sinus massage response was 7.3 seconds' asystole and a 77-mm Hg drop in systolic blood pressure.

CONCLUSIONS

Carotid sinus hypersensitivity is common in older persons, even those with no history of syncope, dizziness, or falls. The finding of a hypersensitive response should not necessarily preclude further investigation for other causes of syncope.

Atrial fibrillation precipitated by carotid sinus massage in a patient with unexplained syncope

BACKGROUND

Carotid sinus massage (CSM) is a useful tool in the investigation of unexplained syncope, but is associated with risks.

AIM

To describe the first reported case of atrial fibrillation precipitated by CSM during the investigation of a patient with recurrent unexplained syncope.

RESULTS

A 58-year-old female underwent CSM as part of a tilt test protocol for the investigation of recurrent unexplained syncope. Left CSM revealed the diagnosis of mixed cardioinhibitory and vasodepressor carotid sinus syndrome but also precipitated atrial fibrillation, an arrhythmia previously unreported as a complication of the procedure.

CONCLUSIONS

CSM is a useful tool in the investigation of patients with recurrent unexplained syncope, but may cause atrial fibrillation in addition to other previously described complications and should, therefore, be used with caution.

Glomectomy in carotid sinus syncope and associated arrythmias: symptomatic bradycardia, atrial flutter and atrial fibrillation

The main causes of neurally mediated syncope (NMS) are carotid sinus syndrome (CSS) and vasovagal syncope. Long before, carotid sinus denervation was performed for different diseases, but for the first time we consider glomectomy (G) as a surgical treatment for NMS and related arrhythmias, alone or associated with cardiac pacing (PM).

METHODS

We used Nakayama's technique for bronchial asthma, modified by us: removal of hypersensitive carotid glomus and presinusal lymphadenectomy. Forty five patients (pts) with recurrent NMS (cardioinhibitory 14 pts, mixed 31 pts) were included: 41 males, 4 females, aged 23-84 (mean 60 yrs). The diagnosis was documented clinically by carotid sinus massage, ECG-Holter, electrophysiologic studies, head-up tilt test. Malignant orthostatic syndrome was present in 4 pts, tussive syncope in one, sick sinus syndrome (SSS) in 6 pts, atrial fibrillation and flutter in 6 pts, AV block in 2 pts. Thirty four pts underwent G alone; 6 pts-G and PM; 5 pts-PM alone, 3 pts-G plus carotid endarterectomy.

RESULTS

of G were excellent. All pts became free of syncope (max. follow-up 10 yrs). In addition, stable sinus rhythm was obtained in two pts (one with severe atrial fibrillation, another with persistent atrial fibrillation). In pts with SSS, A-V block or atrial fibrillation with bradycardia, PM was inserted (DDDR or VVIR). However, in pts with vasodepressor component of NMS, symptoms persist until G was performed.

CONCLUSIONS

We conclude that our data support the efficiency of G in pts with NMS (either cardioinhibitor or vasodepressor), as well as in related arrhythmias. PM is indicated in pts with associated diseases: intrinsic SSS, AV block, atrial fibrillation with bradycardia.