Carotid sinus syncope

Anterior cervical pseudomeningocele causing syncope after spinal surgery: A case report

INTRODUCTION AND IMPORTANCE

Pseudomeningocele formation from incidental durotomy is a known risk in spine surgery. We present a case of incidental durotomy leading to anterior neck pseudomeningocele, compressing the carotid body (CB) resulting in syncopal episodes. To our knowledge, this is the first case report implicating syncopal episodes to CB compression via a pseudomeningocele.

CASE PRESENTATION

A mid sixty-year-old patient with history of obesity, hypertension, and diabetes presented with gait impairment and hand weakness. Ossification of posterior longitudinal ligament (OPLL) was diagnosed with computed tomography imaging (CT) and magnetic resonance imaging (MRI). Elective surgery was completed with an anterior and posterior approach for decompression and fusion. Hospital course (San Jose, CA, USA) was complicated by respiratory depression and incomplete tetraplegia. On post-operative day (POD) six, CT revealed anterolateral soft tissue neck swelling; subsequent CT and MRI showed fluid collection expansion, with associated syncopal episodes on POD thirty-nine. Despite interventional radiology drainage, the fluid collection and symptoms returned five days later. The patient ultimately underwent durotomy revision and repair with muscle patch.

CLINICAL DISCUSSION

This case highlights the challenges in managing anterior cervical dural tears resulting in pseudomeningocele. Risk factors include anterior cervical corpectomy and decompression, as well as an underlying diagnosis of OPLL. Untreated dural tears may develop into pseudomeningoceles which can contribute to life-threatening outcomes.

CONCLUSION

This case report presents the serious consequences of incidental durotomy, the unique post-surgical complication of syncope due to compression of the CB from a pseudomeningocele, and the challenges of managing a persistent pseudomeningocele.

Should We Ever Pace for Carotid Sinus Syndrome?

Carotid sinus syndrome has been associated with transient loss of consciousness for millennia, and while steeped in cardiovascular lore, there is little in the way of solid evidence to guide its main treatment modality, permanent cardiac pacing. This article reviews the history of the condition in the context of its contemporary understanding before examining three key concepts in the consideration of what constitutes a manageable disease: first, is there a pathophysiologic rationale for the disease (in this case carotid sinus syndrome)? Second, is there a good diagnostic test that will identify it reliably? And finally, is there a convincingly evidence-based treatment for the disease? Relevant literature is reviewed, and recommendations made in how we view pacing in the context of this intriguingly opaque condition.

A Legal and Forensic Medicine Approach to Police Physical Intervention Techniques in High-Risk Situations

Background: The physical intervention techniques (PITs) typically used by the police in troublesome situations are examined in terms of injuring potential depending on whether they target a body zone of high, medium or low vulnerability. Based on legal and forensic considerations, and principles of congruence, opportunity and proportionality, a need exists to favor opponent locking and arrest techniques targeting non-vulnerable zones to minimize the risk of severe damage. Methods: A search of the training manuals for the different kind of law of enforcement officers was carried out. Revision of injuries was available from electronic databases of academic o medical journals. Results: Three different locking and arrest PITs based on operational tactical procedures (OTP) that avoid zones of high or medium vulnerability are proposed. The new techniques use blocking, diverting and grabbing of the upper and lower limbs, followed by dislocation and locking of the same targets. Conclusions: The damaging potential of such PITs was assessed in terms of anatomical region and most were found to have a high risk of severe damage. The alternative PITs proposed here, which rely on OTP, improve in legal and forensic medical terms on existing choices and dramatically reduce the risk of injuring arrestees.

Reflex Atrioventricular Block

Reflex atrioventricular block is well-recorded although it is considered rare. Recent data suggests that it is less rare than has been supposed. It has been shown to occur in both vasovagal and carotid sinus reflexes. It has to be distinguished from paroxysmal atrioventricular block due to ventricular conduction tissue disease. Low chronic adenosine levels combined with adenosine release may mimic reflex atrioventricular block. Explanations of the mechanism of these phenomena have been lacking until the recent past. The relevance of reflex atrioventricular block to clinical decision-making is as a possible indication for pacing the heart with consideration given to the vasodepressor component of the reflex.

Carotid Sinus Nerve: A Comprehensive Review of Its Anatomy, Variations, Pathology, and Clinical Applications

The carotid sinus nerve branches off the glossopharyngeal nerve just after its appearance from the jugular foramen, descends along the internal carotid artery, and enters the carotid sinus. There have been many studies of the pathway and the course of the carotid sinus nerve and its communications with surrounding nerves. The intercommunication is exceedingly complicated. Acknowledgment of its anatomic diversity can be important in specific operations dealing with this area. Herein we review the anatomy, variations, pathology, and clinical applications of the carotid sinus nerve.

Prevalence and One-year Outcome of Carotid Sinus Hypersensitivity in Unexplained Syncope: A Prospective Cohort Study from South India

BACKGROUND

Carotid sinus syndrome accounts for one third of patients who presents with unexplained syncope. Prevalence of carotid sinus hypersensitivity (CSH) in Indians has not been studied till now.

OBJECTIVES

To assess the prevalence and associations of CSH in symptomatic patients above 50 years and to study its prognostic significance pertaining to sudden cardiac death, syncope, recurrent pre syncope and falls on 1 year follow up.

METHODS

Patients above 50 years who presented with unexplained syncope, recurrent syncope or falls were considered cases and those without these symptoms were considered as controls. All the patients underwent carotid sinus massage and their responses noted. All symptomatic patients were followed up and observed for events like sudden cardiac death, syncope, recurrent pre syncope and falls during 1 year follow up. Patients with recurrent syncope and predominant cardioinhibitory syncope were advised permanent pacemaker implantation.

RESULTS

A total of 252 patients were screened, 130 patients constituted cases and 49 patients constituted controls. CSH was demonstrable in 32% (n = 42) of cases as compared to 8% (n = 4) in controls (p < 0.001). Cardioinhibitory response was the predominant response (88%, n = 38) followed by mixed response (12%, n = 4). CSH was associated with advancing age, male gender (93%, n = 39, p < 0.001) and history of smoking (63%, n = 27, p = 0.009). Composite outcomes of sudden cardiac death, syncope, recurrent pre syncope and falls were significantly higher in patients with symptomatic CSH than in those without it (45%, n = 16 vs. 6.8%, n = 6; p < 0.001).

CONCLUSIONS

In conclusion, the prevalence of CSH in patients above 50 yrs with unexplained syncope was high in our population. Patients with CSH and baseline symptoms developed recurrent syncope during follow up. Carotid sinus massage should be a part of routine examination protocol for unexplained syncope.

The accuracy of anatomical landmarks for locating the carotid sinus

BACKGROUND

carotid sinus massage (CSM) is a valuable clinical test for carotid sinus syndrome (CSS) and relies on accurately locating the carotid sinus (CS).

OBJECTIVE

in this study, we sought to examine the accuracy of using anatomical landmarks for locating the CS.

METHODS

consecutive patients (n = 20) were recruited prospectively. Two clinicians, trained in CSM, were asked to locate the CS using anatomical landmarks. A point on the skin overlying the CS was then marked by a vascular technician using ultrasound. Accuracy of techniques was compared using intra-class correlation coefficients and Bland-Altman statistics.

RESULTS

anatomical landmarks underestimated the CS location by 1.5 ± 1.3 cm. Error extremes ranged from 4 cm below to 2 cm above CS using anatomical landmarks. A moderate correlation between ultrasound and anatomical landmarks was found, r = 0.371 (P = 0.031).

CONCLUSION

this is the first study to characterise the accuracy of standard anatomical landmarks used in CSM. Results suggest that the point of maximal pulsation has the lowest associated error. Future work should examine CSM yield across this and a range of other methodological factors.

Carotid sinus syndrome

Carotid sinus hypersensitivity, first described less than 65 years ago, is an important and often undiagnosed cause of syncope in the elderly. Its pathophysiology is complex and certain aspects are not completely understood. The timely diagnosis and treatment of this condition can improve morbidity and prevent complications in the elderly. In this article, the prevalence, risk factors, pathophysiology, diagnosis, aspects of carotid sinus massage, and treatment options for the different kinds of carotid sinus hypersensitivity are discussed.

Carotid sinus syndrome: Progress in understanding and management

Carotid sinus syndrome (CSS) is a disease of the autonomic nervous system presenting with syncope, especially in older males who often have cardiovascular disease. The aetiology is unknown and epidemiological data is limited. Forty new patients/million population have been estimated to require pacing for CSS and these patients represent ∼9% of those presenting syncope to a specialist facility. CSS is defined as a response to carotid sinus massage (CSM) that includes reproduction of spontaneous symptoms. Cardioinhibitory CSS shows 3s asystole on CSM and vasodepressor CSS shows >50 mmHg fall in blood pressure (BP), there are mixed forms. The methodology of CSM requires correct massage in the supine and upright with continuous ECG and BP. Assessment of the vasodepressor component implies the ‘method of symptoms’ using atropine to prevent asystole. Carotid sinus hypersensitivity (CSH) is a related condition where CSM is positive in an asymptomatic patient. CSH cannot be assumed to respond to pacing. CSS patients present syncope with little or no warning. If no cause is revealed by the initial evaluation, CSM should be considered in all patients >40 years. CSM carries a small risk of thromboembolism. Therapy for cardioinhibitory CSS is dual chamber pacing, which is most effective in patients with a negative tilt test. Syncope recurrence is ∼20% in 5 years in paced patients. Therapy for the vasodepressor component of CSS, as pure vasodepression or mixed, where tilt testing will likely be positive, is often unrewarding: alternative therapeutic measures may be needed including discontinuation/reduction of hypotensive drugs.

Falls

In the context of an aging population, the importance of falls and their prevention has arguably never been greater. Both injurious and non-injurious falls are a frequent occurrence resulting in potentially devastating physical and social consequences. In recent years, there has been a marked expansion in falls research, meta-analysis, and local and national management guidelines, reflecting increased multidisciplinary professional and public awareness of falls.

Neurally mediated syncope and unexplained or nonaccidental falls in the elderly

Falls and syncope are among the leading causes for which older patients seek hospital admissions. The prevalence of unexplained or nonaccidental falls is high in this group. The clinical spectrum of falls and syncope has been shown to overlap significantly in the elderly. Carotid sinus syndrome and vasovagal syncope, the two common examples of neurally mediated syncope (NMS), have been increasingly recognised as important attributable causes for unexplained falls and syncope. However, in clinical practice NMS is not widely investigated as a cause of fall and is likely to be underdiagnosed.

Treatment of vasodepressor carotid sinus syndrome with midodrine: a randomized, controlled pilot study

OBJECTIVES

To evaluate the efficacy of treatment of the vasodepressor form of carotid sinus hypersensitivity (carotid sinus syndrome (CSS)) with midodrine.

DESIGN

A prospective, double-blind, randomized, controlled trial of crossover design.

SETTING

A dedicated outpatient facility with access to tilt-table, digital arterial photoplethysmography, and 24-hour ambulatory blood pressure (BP) monitoring equipment.

PARTICIPANTS

Ten older adults (4 male, 6 female, mean age 75, range 66-86 years) with a history of unexplained syncope who displayed an asymptomatic decrease in systolic BP (SBP) of more than 50 mmHg or a symptomatic decrease of more than 30 mmHg within 30 seconds of carotid sinus massage (CSM).

MEASUREMENTS

Symptom reproduction and BP and heart rate changes were evaluated after CSM in supine and semierect positions on the right and then left sides. These measurements were performed on the final day of placebo and active-treatment phases. Ambulatory 24-hour BP monitoring took place on the penultimate and final days of each treatment phase.

RESULTS

Eight patients were symptomatic after their initial CSM. The mean+/-standard deviation SBP decrease after initial CSM was 54+/-22 mmHg. Initial mean 24-hour ambulatory BP was 127/70+/-7/5 mmHg. Eight patients reported symptoms after CSM at the end of the placebo phase. The mean SBP decrease at the end of the placebo phase was 49+/-12 mmHg. The mean 24-hour ambulatory BP was 127/69+/-9/7 mmHg. One patient reported symptoms after CSM at the end of the active-treatment phase. The mean SBP decrease at the end of the active-treatment phase was 36+/-9 mmHg. The mean 24-hour ambulatory BP at the end of the treatment phase was 133/75+/-7/6 mmHg. The differences in symptom reporting and mean SBP decrease after CSM were both significant (P<.01 and P=.03, respectively).

CONCLUSION

The results of this pilot study suggest that treatment of vasodepressor CSS with midodrine significantly reduced the rate of symptom reporting and attenuated SBP decreases after CSM but increased mean 24-hour ambulatory BP.

Setting up a falls and syncope service for the elderly

Establishing a neurocardiovascular investigation unit for the investigation of falls and syncope in the elderly is feasible. With the increasing growth in the elderly population, these units will be required to play an equally increasing role in both the clinical management of patients and the ongoing clinical research into the conditions that cause falls and blackouts in the elderly.

Pacing interventions for falls and syncope in the elderly

There is a high prevalence of cardiovascular disorders among elderly patients with recurrent falls or syncope, and cardiovascular causes are implicated in a significant proportion of three cases. Common cardiovascular causes of falls and syncope include carotid sinus syndrome, vasovagal episodes, sick sinus syndrome, and atrioventricular block. A comprehensive history and physical examination supplemented by electrocardiographic monitoring, carotid sinus massage, and tilt-table testing in appropriately selected patients form the basis of the diagnostic evaluation to exclude a significant cardiovascular disorder. Patients with documented symptomatic bradycardia often benefit from pacemaker implantation, as evidenced by a reduction in recurrent events and improved quality of life. Although dual-chamber pacemakers, particularly those with rate responsiveness, provide more physiologic pacing than single-chamber ventricular devices, the superiority of dual-chamber pacemakers in reducing major clinical events has not been demonstrated. The efficacy of an aggressive evaluation and patient-management strategy that includes pacemaker implantation for elderly patients with recurrent falls has been validated only by one prospective clinical trial; however, available data are compelling. For a variety of cardiovascular conditions, permanent pacemaker implantation has a demonstrated efficacy to prevent symptoms that arise from transient hypotension and decreased cerebral perfusion. The implication of these data is that many falls may be preventable through permanent pacemaker implantation in appropriately selected patients.

Diagnostic yield and development of a neurocardiovascular investigation unit for older adults in a district hospital

BACKGROUND

Dizziness, syncope, and falls are common occurrences in elderly people. Neurocardiovascular investigation units aim to detect those patients who fall due to disturbances of blood pressure control or cardiac conduction. Specialist units have a high diagnostic yield in the investigation of these problems. Does this translate to less specialized centers? We report on the diagnostic findings of a district general hospital neurocardiovascular investigation unit.

METHOD

A total of 120 consecutive patients over the age of 65 presenting to a single geriatrician were assessed. After a full history and physical examination, patients underwent neurocardiovascular investigation: blood pressure and heart rate response to active stand, carotid sinus massage, and 30-minute head-up tilt.

RESULTS

The 120 patients assessed had a mean age of 78 years (range 66-94 years); in this group, 85 were women. Of these patients, 23% presented with falls, 14% with blackouts, and 30% with dizziness. The remaining 33% had overlap of symptoms. Neurocardiovascular investigations produced a diagnosis in 57% of the patients: 22% had cardioinhibitory carotid sinus syndrome (CSS): 15% had vasodepressor CSS; 29% had orthostatic hypotension; and 3% had vasovagal syncope. Thirteen percent had more than one neurocardiovascular abnormality, and 18% had benign positional vertigo. Five patients had postural instability causing falls. Hyperventilation syndrome, aortic stenosis, dysrhythmia, cervical spondylosis, and epilepsy each accounted for one case. Seventeen percent of the subjects remained undiagnosed after integrated neurocardiovascular assessment.

CONCLUSION

Management of falls requires access to neurocardiovascular assessment. It is feasible to provide such a service in the district general hospital setting, with a comparable diagnostic yield to tertiary referral centers.

Diagnosis of carotid sinus hypersensitivity in older adults: carotid sinus massage in the upright position is essential

OBJECTIVE

To assess the diagnostic value of supine and upright carotid sinus massage in elderly patients.

DESIGN

Prospective controlled cohort study.

SETTING

Three inner city accident and emergency departments and a dedicated syncope facility.

PATIENTS

1375 consecutive patients aged > 55 years presenting with unexplained syncope and drop attacks; 25 healthy controls.

INTERVENTIONS

Bilateral supine carotid sinus massage, repeated in the 70 degrees head up tilt position if the initial supine test was not diagnostic of cardioinhibitory and mixed carotid sinus hypersensitivity.

MAIN OUTCOME MEASURES

Diagnosis of cardioinhibitory or mixed carotid sinus hypersensitivity; clinical characteristics of supine v upright positive groups.

RESULTS

226 patients were excluded for contraindications to carotid sinus massage. Of 1149 patients undergoing massage, 223 (19%) had cardioinhibitory or mixed carotid sinus hypersensitivity; 70 (31%) of these had a positive response to massage with head up tilt following negative supine massage (95% confidence interval, 25.3% to 37.5%). None of the healthy controls showed carotid sinus hypersensitivity on erect or supine massage. The initially positive supine test had 74% specificity and 100% sensitivity; these were both 100% for the upright positive test. The clinical characteristics of the supine v upright positive subgroups were similar.

CONCLUSIONS

The diagnosis of carotid sinus hypersensitivity amenable to treatment by pacing may be missed in one third of cases if only supine massage is performed. Massage should be done routinely in the head up tilt position if the initial supine test is negative.

Diagnostic utility of mechanical, pharmacological and orthostatic stimulation of the carotid sinus in patients with unexplained syncope

OBJECTIVES

The purpose of the present study was to systematically evaluate the diagnostic utility of mechanical, pharmacological and orthostatic stimulation of the carotid sinus in a consecutive series of patients with recurrent unexplained syncope.

BACKGROUND

Carotid sinus hypersensitivity (CSH) is an infrequently recognized cause of recurrent unexplained syncope usually diagnosed by carotid sinus massage (CSM) in the supine position. The diagnostic utility of systematic assessment of mechanical, pharmacological and orthostatic stimulation of the carotid sinus has not been clearly established.

METHODS

Eighty consecutive patients (63 +/- 12 years) with a history of recurrent unexplained syncope (mean episodes: 6 +/- 3); 30 age-matched controls (65 +/- 14 years) and 16 patients (59 +/- 12 years) with syncope not related to CSH were studied. Pharmacological stimulation of the carotid sinus was achieved by randomly administering bolus injections of nitroprusside and phenylephrine. Mechanical stimulation of the carotid sinus was performed by CSM applied for 5 s in the supine position and after 2 min at 60 degrees. A 60 degree low-dose isoproterenol head-up tilt test (HUTT) was also performed for a total duration of 30 min.

RESULTS

Carotid sinus hypersensitivity was elicited by CSM in the supine position in seven (8.7%) patients, two (6.6%) controls and one (6.3%) patient with syncope unrelated to CSH, compared with 48 (60%) patients, two (6.6%) controls and one (6.3%) syncope unrelated to CSH patient after 60 degree HUTT, increasing the diagnostic yield by 51%. Baroreceptor gain was significantly reduced in the CSH group. Head-up tilt test was positive in 12 (25%) patients with CSH, two (6.6%) controls and two (12%) with documented syncope but not positive in any of the patients in which syncope remained unexplained. Diagnostic accuracy was enhanced by 38% (31% supine vs. 69% upright) when CSM was performed at 60 degrees.

CONCLUSIONS

CSH was documented in 68% of patients, 8.7% in the supine position and 60% in the upright position. Sensitivity was increased by 51%, and diagnostic accuracy was enhanced by 38% by performing CSM in the upright position. Decreased baroreceptor gain was documented and may play a role in the pathophysiology of CSH.

The overlap between syncope and falls in the elderly

Syncope and falls are often considered to be two separate diagnoses with two separate sets of aetiologies. However, although it remains controversial, the existence of an overlap between syncope and falls is becoming increasingly acknowledged. In the elderly, determining the cause of a fall can be difficult. Approximately 30% of cognitively normal elderly people are unable to recall documented falls three months later and a witness account for syncopal events is unavailable in about 50% of patients. We have found that in almost 40% of patients in whom an attributable diagnosis of carotid sinus syndrome was made, the only presenting symptoms were falls alone or falls with dizziness; syncope was denied. Amnesia for loss of consciousness can be demonstrated in over 20% of all patients with a diagnosis of carotid sinus syndrome and in 50% of those patients who present only with falls or falls and dizziness. There is a suggestion from studies in postprandial hypotension and orthostatic hypotension, where similar haemodynamic changes are found in patients complaining of either syncope or falls, that this phenomenon may be generalisable. The importance of the presence of an overlap between syndrome and falls in the elderly lies in the healthcare implications of missed diagnoses of cardiovascular syncope for which there are established effective treatments. Consideration of syncope in the differential diagnosis of unexplained falls should reduce the numbers of falls for which no attributable diagnosis is found and result in an improved standard of health care for elderly patients who fall.

A study comparing VVI and DDI pacing in elderly patients with carotid sinus syndrome

OBJECTIVE

To determine whether single chamber ventricular demand (VVI) pacing is adequate for elderly patients with carotid sinus syndrome.

DESIGN

Prospective double blind randomised cross over study.

SETTING

Tertiary referral centre.

PATIENTS

30 consecutive patients aged over 60 years with carotid sinus syndrome referred for cardiac pacing.

INTERVENTION

Patients underwent dual chamber pacemaker implantation and were then randomised to two three-month periods of VVI and DDI pacing.

MAIN OUTCOME MEASURES

Responses to cardiovascular tests (vasodepression during carotid sinus massage, pacemaker effect, postural blood pressure measurements, and response to head up tilt), and symptoms.

RESULTS

11 patients developed profound hypotension during upright carotid sinus massage while pacing VVI compared with only two while pacing DDI. The upright pacemaker effect was greater in VVI (VVI, -31 (SD 19) mm Hg v DDI, -4 (12) mm Hg; P < 0.001). Postural blood pressure measurements and responses to head up tilt did not vary. Eleven patients were unable to tolerate VVI pacing and had to be withdrawn early from this limb of the study (group A). Fourteen of the remainder completed diary cards and did not express a preference (group B). No patient preferred VVI. Group A patients were older (group A, 78 (6) years v group B, 70 (9) years; P < 0.05), were more likely to be female (group A, 73% v group B, 14%; P < 0.01), and were more likely to have orthostatic hypotension while pacing DDI (group A, 46% v group B, 0%; P < 0.01). Group A and B patients could not be differentiated by other prepacing clinical or haemodynamic variables.

CONCLUSIONS

Elderly patients with carotid sinus syndrome are likely to develop symptomatic hypotension following VVI pacing. The optimum pacing mode for individual patients cannot be predicted by simple cardiovascular tests before pacing.

Syncope in the elderly

Age-related physiologic changes and disease-related abnormalities predispose older adults to syncope. It is important to know the physiologic changes that occur with normal aging to understand better their interaction with disease processes and to facilitate better evaluation and treatment of syncope when it occurs. Attention to situational stresses, such as posture changes, meals, or medications, is also likely to increase the diagnostic yield and improve therapeutic strategies that can reduce morbidity and potential mortality of recurrent episodes. Therapy should be directed toward minimizing multiple factors that contribute to syncope, avoiding iatrogenic medication effects, and treating specific contributory diseases.

Mechanisms of heart rate and arterial blood pressure control: implications for the pathophysiology of neurocardiogenic syncope

Neurocardiogenic syncope is a general term that describes syncope resulting from altered autonomic activity, as manifested by abnormal regulation of peripheral vascular resistance and heart rate. Although there has been great interest in the contribution of heart rate to this form of syncope, the peripheral circulation plays the dominant role in the induction of neurocardiogenic syncope in most patients. We review in this brief article the physiology of cardiovascular reflexes, which are important for short-term arterial pressure control, and their potential contribution to the pathophysiology of neurocardiogenic syncope. This type of syncope represents a profound failure of the normal mechanisms for short-term regulation of arterial pressure. Any therapeutic strategies for the management of neurocardiogenic syncope must deal with alterations in vascular control, which contribute to its pathogenesis.

Prevalence of cardioinhibitory carotid sinus hypersensitivity in patients 50 years or over presenting to the accident and emergency department with "unexplained" or "recurrent" falls

To study the prevalence of Cardioinhibitory Carotid Sinus Hypersensitivity (CICSH) in patients 50 years or over presenting to casualty with "unexplained" or "recurrent" falls. The prospective study was from October 1, 1995 to April 30, 1996 in the Inner City Accident and Emergency Departments, Newcastle Upon Tyne, U.K. Ten thousand four hundred forty-three patients 50 years and over presented, of which 4,051 (39%) were fallers. Fallers were excluded if they lived over 15 miles from the hospital (81), were registered blind (17), were unable to speak English (22), were unable to previously walk (27), if there was a history of only one accidental fall (1,659) or were cognitively impaired (776: Mini Mental State Examination < 24 [30]) or if there was a clear attributable medical diagnosis for the fall (871). Five hundred ninety-eight "unexplained" or "recurrent" fallers (defined as three or more falls in the previous 12 months) were assessed for carotid sinus massage (CSM). One hundred forty-five patients declined CSM (24%), 70 (12%) had relative contraindications to CSM and 13 already had pacemakers in situ (2%). Two hundred seventy-nine underwent CSM, of whom 65 had CICSH (23%), which might be amenable to treatment with pacemakers. The prevalence of CICSH (a potentially treatable condition) in "unexplained" or "recurrent" fallers who present to the accident and emergency department is 23%. A randomized control study to assess benefit from pacemaker intervention in these patients is underway.

The heart rate response to carotid artery massage in a sample of healthy elderly people

Carotid artery massage was carried out in a cross-section of 95 healthy elderly subjects (51 men and 44 women, mean age of 74 years) to assess the heart rate response and associated symptoms. These subjects were drawn from a larger group of randomly selected healthy elderly people living in Southampton. They had no history of myocardial infarction or stroke and were not taking any drugs that might enhance the carotid sinus reflex. A continuous distribution of response to carotid artery massage was seen with a median percent change in RR interval of 11.6% (IQR 22.9%); 66% had a percent change in RR interval of < 20%, 90% had a change of < 50%, and 9.5% a change of > 100%. Carotid sinus hypersensitivity (sinus arrest > 3 s) was found in 4 previously asymptomatic subjects; a prevalence of 4.2% (95% CI 1.2%-10.4%), and this was associated with dizziness in 2 of these 4 subjects. Dizziness also occurred in one other subject who had a change in RR interval of 178%. The definition of an abnormal carotid sinus reflex is arbitrary given the continuous RR interval response to carotid artery massage. In diagnosing carotid sinus syndrome, the RR interval response to carotid artery massage alone is not sufficient, as this maneuver must also reproduce the patient's presenting symptoms.

Temporary Cardiac Pacing in the Intensive Care Unit

Indications for temporary cardiac pacing have increased substantially in the last several years. Although most temporary cardiac pacing is still carried out to treat symptomatic bradycardia due to atrioventricular conduction system disease or atrial bradycardia (i.e., sinus node dysfunction), temporary pacing is currently used to induce and to terminate some supraventricular tachyarrhythmias, prevent pause-dependent ventricular tachycardia (usually torsades de pointes), and vagally mediated atrial fibrillation, to allow the maintenance of hemodynamic competence in postoperative cardiac patients and to evaluate selected patients with hypertrophic and dilated cardiomyopathies who might benefit hemodynamically from cardiac pacing. The roles of transcutaneous and esophageal pacing have also expanded; transcutaneous pacing is now commonly used in patients at high risk for the development of atrioventricular block, such as those with acute myocardial infarction and bifascicular block. We review available types of temporary pacing leads and pulse generators, the methods by which temporary pacing is accomplished, complications of pacing system insertion, and current indications for this therapy. Guidelines for troubleshooting normal and abnormal pacemaker function in the intensive care unit setting are provided.

Pathophysiology of carotid sinus hypersensitivity in elderly patients

Carotid sinus hypersensitivity (CSH) is recognised in up to 45% of elderly patients with syncope, falls, and dizziness that may not be attributed to specific myocardial sinus node dysfunction, various diseases that affect pacemaker activity, cardiac output and blood supply to the brain. The pathophysiology of CSH is unclear but it is associated with ageing, hypertension, and ischaemic heart disease. CSH is potentially treatable with dual chamber pacing for prolonged sinus arrest (cardio-inhibitory CSH) but therapy for the more prevalent hypotension (vasodepressor CSH) is unsatisfactory. However, hypersensitivity of the carotid sinus is not consistent with the known blunting effects of senescence and hypertension on baroreflex sensitivity. The present hypothesis proposes that CSH in elderly patients results from up-regulation of brainstem postsynaptic alpha-2 adrenoceptors. Reduced carotid sinus compliance in elderly arteriosclerotic hypertensive patients will reduce afferent impulse traffic in the baroreflex pathway. Such relative deafferentation may be expected to cause baroreflex postsynaptic hypersensitivity, mediated by up-regulation of the dominant postsynaptic receptor population in the baroreflex pathway, ie, alpha-2 adrenoceptors. Vigorous carotid sinus stimulation, eg, massage, could thus cause an overshoot baroreflex efferent response, resulting in profound hypotension and bradycardia. Hypotension and bradycardia are compounded by the effects of age, hypertension, ischaemic heart disease and arteriosclerosis on rapid cardiovascular compensation, resulting in cerebral hypoperfusion and syncope. Thus CSH in elderly patients should be considered as a clinical marker of widespread arteriosclerotic disease, rather than as a distinct disease entity. If correct, this hypothesis has potentially important implications for the pharmacotherapy of hypotension-related symptoms in elderly arteriosclerotic patients.

The clinical spectrum of neurocardiogenic syncope

Neurocardiogenic syncope is a collective term used to describe the clinical syndromes of syncope that result from inappropriate, and often excessive, autonomic reflex activity, and manifest as abnormalities in the control of vascular tone and heart rate. These include carotid sinus syndrome, vasovagal syncope, and the syndromes of cough, deglutition, and micturition syncope. Orthostatic hypotension, which, in contrast, results from a failure of autonomic reflexes, is not considered part of this family of closely related syndromes. This review will focus on vasovagal and carotid sinus syndromes.

Carotid sinus syncope: the most frequent neurally mediated syncope in the elderly

The present work reviews current literature and the authors' experience of carotid sinus syndrome (CSS), which is considered to be the most common cause of neurally mediated acute disorders of consciousness in the elderly. Although no definitive consensus about its nosology has yet been reached, most groups agree that three features fulfill the diagnosis: anamnestic presence of syncope or its minor equivalents, and their reproduction by carotid sinus massage associated with defined values of cardioinhibition or vasodepression or both. The technique for performing carotid sinus massage used by the authors is described; this manoeuvre seems very safe and reproducible as long as simple rules are followed, and it allows the classification of CSS types. The treatment of CSS is varied, according to several factors. No pharmacological therapy has yet been demonstrated to be effective. While severe cardioinhibitory forms require an appropriate pacing, vasodepressive ones and types with only minor symptoms show a more favourable natural history. Pacing is advised in mixed CSS with either frequent and invalidating relapses, or 'high risk' attacks (severe, abrupt, with major traumas, etc.). Finally, the protocol for choosing the adequate mode of pacing is illustrated. In most cases VVI is sufficient, but the decision requires a careful individual examination.

Incidence of complications after carotid sinus massage in older patients with syncope

OBJECTIVE

To review the incidence of neurological complications occurring after carotid sinus massage performed for diagnostic purposes.

DESIGN

Case review and comparison with previously published work.

SETTING

Syncope Clinic, Royal Victoria Infirmary, Newcastle-upon-Tyne, and Chelsea and Westminster Hospital, London.

PARTICIPANTS

Patients undergoing investigation of dizziness, syncope, or unexplained falls.

METHODS

Carotid sinus massage performed for 5 seconds in both supine and erect postures, both before and after atropine. Contraindications to carotid sinus massage were the presence of carotid bruits, recent myocardial or cerebral ischemia, or previous ventricular tachyarrhythmias.

RESULTS

Two cases of neurological complications were reported from a total of 500 patients (2000 massage episodes) investigated in one center, giving an incidence of 0.1%. Combining this data with another center performing investigations in a similar fashion, seven neurological complications arose from a total of 5000 massage episodes, an incidence of 0.14%. Reported complications were pyramidal signs in five cases and visual field defects in two. Pyramidal weakness persisted in one case with a pre-existing stroke on the same side, and a visual field loss was permanent in one.

CONCLUSIONS

Neurological complications following carotid sinus massage for diagnosis of the carotid sinus syndrome are uncommon and usually transient. Contraindications to carotid sinus massage should be respected and the standardized technique used.

Carotid sinus hypersensitivity and syndrome in patients with chronic atrial fibrillation

Carotid sinus hypersensitivity (CSH) has been studied in subjects in sinus rhythm, but it has never been studied in patients with chronic atrial fibrillation (AF). After a finding of CSH in a patient with chronic AF and syncope, we studied the effects of carotid sinus stimulation in a group of patients with AF. Ten patients with chronic AF and normal ventricular rates who complained of dizziness or loss of consciousness underwent right and left carotid sinus massage (CSM) during ECG monitoring. A control group of ten patients with AF but without neurological symptoms was likewise investigated. CSH was present in eight symptomatic patients (5 patients presented right CSH, 1 left and 2 bilateral CSH), but only in three of the control patients. The mean duration of asystole induced by right CSM was 5.94 +/- 2.10 seconds; the mean asystolic interval induced by left CSM lasted 8.58 +/- 1.42 seconds. Six patients in the symptomatic group had a recurrence of spontaneous symptomatology during CSM, so that a diagnosis of carotid sinus syndrome was established. All symptomatic patients (8 patients with CSH, 2 patients with ventricular standstills but without CSH) received a permanent ventricular pacemaker. Following pacing, all patients, except for one with a significant drop of systolic blood pressure during CSM, became completely asymptomatic. In elder patients with chronic AF, CSH can induce prolonged ventricular asystole, which may be responsible for neurological symptoms such as dizziness, presyncope, or syncope, as observed in patients in sinus rhythm with carotid sinus syndrome.(ABSTRACT TRUNCATED AT 250 WORDS)

Permanent pacing for cardioinhibitory malignant vasovagal syndrome

OBJECTIVE

To evaluate the effect of permanent pacing in cardioinhibitory malignant vasovagal syndrome.

PATIENTS AND METHODS

37 patients with permanent pacemakers for cardioinhibitory malignant vasovagal syndrome. All presented with syncope (median six episodes, median frequency two episodes a year) and after conventional investigation and invasive electrophysiological assessment they remained undiagnosed, and without a generally accepted indication for pacemaker implantation. In all vasovagal syncope with cardioinhibition (heart rate at syncope < 60 beats/min) developed during tilt tests performed according to the Westminster protocol (head up tilt at 60 degrees with a footplate support for 45 minutes or until syncope intervenes). Dual chamber pacemakers were implanted in 35 (95%) and VVI pacemakers in the remaining two (5%).

RESULTS

Over a mean (SD) follow up since implantation of 50.2 (23.9) months symptomatic improvement occurred in 89%: 62% remained free of syncope and 27% were completely symptom free. The collective syncopal burden of these 37 patients was reduced from 136 to 11 episodes each year. During follow up three patients died from unrelated causes. Patients who become asystolic during the tilt test (sinus pause of at least four seconds) experienced no greater benefit from pacing than those with less extreme cardioinhibition. Patients who remained free of syncope since implantation were younger than those who continued to experience syncope. Patients who remained completely symptom free after implantation were younger, more likely to be male, and had had fewer syncopal episodes before implantation than those who continued to experience syncope or presyncope. No other demographic, clinical, investigative, or pacing variable suggested a more favourable outcome after implant.

CONCLUSIONS

This retrospective and uncontrolled experience suggests a possible role for permanent pacing in selected patients with cardioinhibitory malignant vasovagal syndrome. Improved acquisition of tilt test data may enable better selection of patients who are suitable for permanent pacing. A randomised prospective study to compare permanent pacing with no treatment or with medical treatment in cardioinhibitory malignant vasovagal syndrome is indicated.

Clinical characteristics of vasodepressor, cardioinhibitory, and mixed carotid sinus syndrome in the elderly

PURPOSE

Carotid sinus syndrome (CSS) is frequently overlooked as a cause of syncope in the elderly. It is diagnosed when carotid sinus massage (CSM) produces asystole exceeding 3 seconds (cardioinhibitory CSS), a reduction in systolic blood pressure exceeding 50 mm Hg independent of heart rate slowing (vasodepressor CSS), or a combination of the two (mixed CSS). Most published data pertain to the cardioinhibitory subtype. The recent availability of noninvasive phasic blood pressure monitoring has allowed accurate routine assessment of the vasodepressor response to CSM. The aim of this study was to assess the clinical characteristics of vasodepressor, cardioinhibitory, and mixed CSS.

PATIENTS AND METHODS

CSM was carried out on 132 consecutive patients over 65 years referred for investigation of dizziness, falls, or syncope. Massage was performed both supine and upright with continuous electrocardiographic and phasic blood pressure monitoring. Patients exhibiting greater than 1.5-second asystole were given 600 micrograms of intravenous atropine to abolish heart rate slowing and allow assessment of the pure vasodepressor response.

RESULTS

Carotid sinus hypersensitivity was documented in 64 patients (mean age 81 +/- 7 years, 31 male). The response was vasodepressor in 37%, cardioinhibitory in 29%, and mixed in 34%. Thirty-six patients had recurrent syncope, 17 presented with unexplained falls, and the remainder had dizziness alone. Symptoms had been present for a median of 24 months, and the median number of syncopal episodes was four. Twenty-five percent had sustained a fracture and, of these, 93% had not experienced a prodrome. Head movement precipitated symptoms in 47% and vagal stimuli in 73%. Episodes were unwitnessed in two thirds of patients. Twelve patients who presented with falls denied syncope but had witnessed loss of consciousness during CSM. Mean cardioinhibition was 5 +/- 2 seconds and mean vasodepression 61 +/- 9 mm Hg. The blood pressure nadir occurred rapidly at 18 +/- 3 seconds after massage, and baseline values were regained at 30 +/- 6 seconds. The clinical characteristics of patients with vasodepressor, cardioinhibitory, and mixed responses were similar.

CONCLUSION

CSS is an underdiagnosed cause of dizziness, falls, and syncope in the elderly. The vasodepressor form occurs more frequently than previously reported and has clinical characteristics similar to those of the cardioinhibitory and mixed subtypes. Elderly patients with this condition may deny syncope and present with recurrent unexplained falls. CSM, ideally with noninvasive phasic blood pressure monitoring, should be routinely performed in elderly patients with unexplained bradycardic or hypotensive symptoms.

Carotid sinus syndrome and wrestling

A 17-year-old boy who lost consciousness during wrestling matches was found to have carotid sinus syndrome. To our knowledge, this report is only the second published case of this entity in an adolescent. Herein we discuss possible implications of this finding for the assessment of syncope in pediatric patients.

Head-up tilt testing with and without isoproterenol infusion in healthy subjects of different ages

Passive head-up tilt testing with or without infusion of isoproterenol is used in the investigation and management of patients with syncope. Twenty-five healthy asymptomatic volunteers prospectively grouped according to age (young [28 +/- 1.7 years]: n = 9; middle [51 +/- 3.3 years]: n = 11; elderly [81 +/- 2.4 years]: n = 5; mean +/- SE) were studied during: (1) supine carotid sinus massage; (2) 60 degrees head-up tilt alone; and (3) infusion of isoproterenol to raise the heart rate 20% above supine baseline, prior to 10-minute repeat tilt. Symptoms occurred in three subjects (12%) and only occurred with passive tilting alone. Two young subjects had syncope with sinus pauses greater than 10 seconds. One elderly subject developed atrial flutter. No subject had symptoms or hypotension during tilt plus isoproterenol or a pause greater than 3 seconds with carotid sinus massage. With passive tilt, mean heart rate increased by 16 +/- 6 beats/min and 18 +/- 7.8 beats/min in the young and middle aged subjects (P < 0.05), but only by 6 +/- 5 beats/min in the elderly (P = NS, supine vs 60 degrees in each group). With head-up tilt plus isoproterenol infusion, the mean heart rate elevation in response to tilt was 17 +/- 9 beats/min, 8 +/- 3 beats/min, and 12 +/- 4 beats/min for the young, middle, and elderly subjects, respectively (P < 0.05, supine vs 60 degrees in each group).(ABSTRACT TRUNCATED AT 250 WORDS)

Autonomic reflexes in patients with cardioinhibitory carotid sinus syncope

Autonomic reflexes were investigated in patients with the cardioinhibitory carotid sinus syndrome. Heart rate, blood pressure and forearm blood flow responses were recorded during prolonged head-up tilt, the Valsalva manoeuvre, lower body negative pressure and sequential respiratory cycles in ten patients and nine age-matched controls. The mean maximum R-R interval prolongation during carotid sinus massage was 4.4 s. Three patients had syncope during prolonged head-up tilt. Heart rate and blood pressure responses were similar for patients and controls who completed tilt. Responses to lower body negative pressure and Valsalva manoeuvre were similar for both groups. Respiratory sinus arrhythmia was significantly less marked in patients, 7 bpm (0 to 20 bpm) versus 15 bpm (6 to 35 bpm; p = 0.05). Therefore, neck massage and deep breathing produce abnormal cardiac vagal responses, whereas other reflexes, including response to lower body negative pressure and the Valsalva manoeuvre are within the normal range in cardioinhibitory carotid sinus syndrome.

Benefits of fludrocortisone in the treatment of symptomatic vasodepressor carotid sinus syndrome

OBJECTIVE

To assess treatment with fludrocortisone in vasodepressor carotid sinus syndrome.

PATIENTS AND METHODS

Eleven patients, mean (SD) age 83 (5) years, with daily dizzy episodes and a median of five (range two to 20) syncopal episodes over a median of one year were studied. All had vasodepressor carotid sinus syndrome (> 50 mm Hg fall in systolic blood pressure during carotid sinus massage independent of bradycardia). Carotid sinus massage was carried out while the patient was supine and upright (tilt table) before and after 600 micrograms intravenous atropine. Phasic heart rate and blood pressure recordings were monitored throughout. The study was repeated after 100 micrograms of fludrocortisone daily by mouth for two weeks. Patients continued to take fludrocortisone for a six month follow up period.

RESULTS

Baseline systolic blood pressure was (mean (SD)) 169 (31) mm Hg and the RR interval was 770 (150) ms. After carotid sinus massage, systolic blood pressure fell to 113 (27) mm Hg (p < 0.01) and RR was 1060 (210) ms (NS). The vasodepressor response was 56 (12) mm Hg. Baseline systolic blood pressure after two weeks of fludrocortisone treatment was 171 (37) mm Hg (NS); but the fall in systolic blood pressure during carotid sinus massage was significantly reduced (32 (14) mm Hg; p < 0.01). At six months follow up, two patients complained of intermittent dizziness and no patients had syncope.

CONCLUSION

Fludrocortisone effectively reduces the vasodepressor response and relieves the symptoms of vasodepressor carotid sinus syndrome.

Sympathoinhibition and hypotension in carotid sinus hypersensitivity

Carotid sinus reflex hypersensitivity is a known cause of syncope in humans. The condition is characterized by cardioinhibition and vasodepression, each to varying degrees. The extent and importance of sympathoinhibition has not been determined in patients with carotid sinus hypersensitivity. This study reports on the extent of sympathoinhibition measured directly directly during carotid massage with and without atrioventricular sequential pacing, in a patient with symptomatic carotid sinus reflex hypersensitivity. Carotid massage elicited asystole, hypotension and complete inhibition of muscle sympathetic nerve activity. Carotid massage during atrioventricular pacing produced similar sympathoinhibition, but with minimal hypotension. Therefore, sympathoinhibition did not contribute importantly to the hypotension during carotid massage in the supine position in this patient. Further investigations are required to elucidate the relation of sympathoinhibition to hypotension in patients with carotid sinus hypersensitivity in the upright position.

Long-term outcome in symptomatic carotid sinus hypersensitivity

Between 1982 and 1988, we observed 312 patients who were affected by syncope or presyncope and whose spontaneous symptoms could be reproduced by means of carotid sinus massage (CSH); no other definite cause of syncope could be identified. The clinical outcome during a 2- to 8-year follow-up period (mean 44 +/- 24 months) was assessed in 262 of them (mean age, 71 +/- 11 years; 183 men) and was compared with that of a group of 55 patients who were affected by unexplained syncope (control patients) who were matched 4:1 for age and sex with CSH patients. CSH patients had an overall mortality rate of 7.3 per 100 person-years (cardiovascular, 66%; sudden death, 9%); overall predicted cumulative survival rates at 1, 3, 5, and 7 years were 92%, 80%, 66% and 53%. Survival was similar in control patients; mortality rate was 5.8 per 100 person-years (cardiovascular, 82%; sudden death, 18%); cumulative survival rates at 1, 3, 5, and 7 years were 85%, 80%, 73%, and 69%. Standardized mortality rate of the general population with similar age and sex distribution, as calculated by means of Italian Istituto Centrale di Statistica death-rate data (1987 edition) was 8 per 100 person-years. Of 13 clinical variables, age, sex, abnormal electrocardiogram, and heart failure (but not CSH type or related arrhythmias) were independently linked to mortality in CSH patients (Cox model). In the vasodepressor form of CSH, patients were younger than those with other forms of CSH and the percentage of women was higher.(ABSTRACT TRUNCATED AT 250 WORDS)

Spontaneous occurrence of the induced cardioinhibitory vasovagal reflex

ECG recording of spontaneous, neurally-mediated syncope is rare. We have observed ten patients who sustained 70 syncopal episodes in whom: (1) ECG monitoring recorded syncope caused by ventricular asystole (AV block, three patients; sinus arrest; seven patients); (2) syncope and the spontaneously observed arrhythmias were reproducible by carotid sinus massage, upright tilt test, or eyeball pressure; and (3) no discernable cause of precipitating factors were detected. Two patients had a history of cardiac disease and four patients had only mild nonclinical ECG or echocardiographic abnormalities. Syncopal episodes recorded during Holter monitoring were of sudden onset in four patients and preceded by prodromal symptoms in six patients. The maximum RR pause was 9.4 +/- 3.7 seconds (range 4.5-15). Electrophysiological evaluation was normal in seven patients. Slight sinus node dysfunction or atrioventricular conduction abnormalities were noted in three others. The clinical characteristics of spontaneous and induced episodes strongly suggest that increased vagal tone played a role in causing the spontaneous events. Vagal stimulation tests are useful for the diagnosis of syncope of unknown origin.

Validation of a method for choice of pacing mode in carotid sinus syndrome with or without sinus bradycardia

A new method for selection of the pacing mode in 60 consecutive patients with severe cardioinhibitory or mixed carotid sinus syndrome was prospectively validated. DDD pacing was preferred for 26 patients with: (1) the cardioinhibitory form and who had symptomatic pacemaker effect; (2) mixed type I form, (cardioinhibitory and vasodepressor) with symptomatic pacemaker effect, ventriculoatrial conduction or orthostatic hypotension; (3) mixed type II; or (4) severe bradycardia. VVI pacing was selected in the remaining 34 patients without these symptoms. During a 32 +/- 10 month follow-up period syncope and severe dizziness persisted in five patients in the VVI group (15%) and in three patients in the DDD group (12%). Symptomatic relief occurred in 87% (52/60) of patients. Minor symptoms persisted in 47% of the VVI group and 42% of the DDD group. No patient developed cardiac insufficiency or intolerance to pacing. During a 2-month duration a single-blind, randomized, cross-over study compared VVI and DDD pacing, 69% of the patients programmed from DDD to VVI suffered more frequent, severe, and intolerable symptoms. (1) Thirty four of 60 patients (57% of the entire group) in whom VVI pacing was satisfactory were identified prior to pacemaker implant. In the remainder, VVI pacing was contraindicated as it produced frequent side effects. (2) The preimplant predictive value that VVI pacing would be successful was 85% for those eventually receiving VVI pacemakers and the preimplant predictive value that VVI pacing would fail was 69% for those who underwent DDD implant.