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

A Case of Carotid Sinus Reflex Caused by Manual Aspiration Thrombectomy Using a Balloon Guide Catheter

When starting a mechanical thrombectomy, manual aspiration with balloon guide catheters inserted into the internal carotid artery (ICA) is an efficient method for thrombus aspiration. However, no complications associated with this procedure have been reported. This study describes the case of a 76-year-old man who presented to our hospital with total aphasia and complete right-sided paralysis due to chronic atrial fibrillation and left occlusion of the ICA. When the balloon guide catheter was inserted and inflated at the origin of the left ICA, the patient's systolic blood pressure suddenly decreased from 114 mm Hg to 44 mm Hg. This sudden hypotension may have been caused by the carotid sinus reflex. Hypotension improved following balloon deflation. The procedure was continued, resulting in complete recanalization of the left ICA. The patient died from acute exacerbation of interstitial pneumonia. Although this complication is rare, similar phenomena have been recognized in carotid artery stenting and the use of flow-diverting devices. To the best of our knowledge, this is the first report of a case wherein the carotid sinus reflex was induced by manual aspiration using a balloon guide catheter placed in the ICA. Clinicians should recognize the importance of ensuring that the proximal end of the balloon crosses the carotid sinus when dilating and occluding the ICA with a balloon to avoid the carotid sinus reflex.

Carotid Sinus Massage in Syncope Evaluation: A Nonspecific and Dubious Diagnostic Method

BACKGROUND

Carotid sinus hypersensitivity (CSH) is a frequent finding in the evaluation of syncope. However, its significance in the clinical setting is still dubious. A new criterion was proposed by Solari et al. with a symptomatic systolic blood pressure (SBP) cut-off value of ≤ 85 mmHg to refine the vasodepressor (VD) response diagnosis.

OBJECTIVE

To determine and compare the response to carotid sinus massage (CSM) in patients with and without syncope according to standard and proposed criteria.

METHODS

CSM was performed in 99 patients with and 66 patients without syncope. CSH was defined as cardioinhibitory (CI) for asystole ≥ 3 seconds, or as VD for SBP decrease ≥ 50 mmHg.

RESULTS

No differences in the hemodynamic responses were observed during CSM between the groups, with 24.2% and 25.8% CI, and 8.1% and 13.6% VD in the symptomatic and asymptomatic groups, respectively (p = 0.466). A p value < 0.050 was considered statistically significant. During the maneuvers, 45 (45.45%) and 34 (51.5%) patients in the symptomatic and asymptomatic groups achieved SBP below ≤ 85 mmHg. Symptoms were reported especially in those patients in whom CSM caused a SBP decrease to below 90 mmHg and/or asystole > 2.5 seconds, regardless of the pattern of response or the presence of previous syncope.

CONCLUSION

The response to CSM in patients with and without syncope was similar; therefore, CSH may be an unspecific condition. Clinical correlation and other methods of evaluation, such as long-lasting ECG monitoring, may be necessary to confirm CSH as the cause of syncope.

Geriatric hypotensive syndromes are not explained by cardiovascular autonomic dysfunction alone

BACKGROUND

Though highly prevalent, the pathophysiology of orthostatic hypotension (OH), postprandial hypotension (PPH), and carotid sinus hypersensitivity (CSH) are rarely studied together. Therefore, we conducted such a comprehensive study focusing on the common role of the cardiovascular autonomic system. We hypothesized that in geriatric patients, OH, PPH, and CSH are manifestations of cardiovascular autonomic dysfunction and investigated state-of-the-art cardiovascular autonomic function indices in a group of geriatric falls or syncope patients.

METHODS

In a cross-sectional study of 203 consecutive eligible falls clinic patients, we compared heart rate variability (HRV), blood pressure variability (BPV), and baroreflex sensitivity (BRS) as potential autonomic function determinants of the three different hypotensive syndromes.

RESULTS

OH, PPH, and CSH were diagnosed in 53%, 57%, and 50% of the patients, respectively. In a population relevant for geriatric practice, we found no differences in HRV, BPV, and BRS between patients with and without OH, with and without PPH, and with and without CSH, respectively, nor between patients with and without falls, dizziness, or syncope as presenting symptom, respectively.

CONCLUSIONS

In geriatric patients with hypotensive syndromes, cardiovascular autonomic function as measured by HRV, BPV, and BRS is comparable to patients without such syndromes. These findings argue against a single or dominant etiological factor, that is, cardiac autonomic dysfunction and underline the structured, broad, and multifactorial approach to elderly patients with falls and/or syncope as proposed in the current evidence-based syncope guidelines.

Head-up tilt testing for diagnosing vasovagal syncope: a meta-analysis

BACKGROUND

A systematic evaluation focused on sensitivity and specificity of head-up tilt testing (HUT) for diagnosing vasovagal syncope has not been previously performed. We conducted a meta-analysis of studies comparing HUT outcome between patients with syncope of unknown origin and control subjects without previous syncope.

METHODS

We searched Pubmed and Embase databases for all English-only articles concerning case-control studies estimating the diagnostic yield of HUT, and selected 55 articles, published before March 2012, including 4361 patients and 1791 controls. The influence of age, test duration, tilt angle, and nitroglycerine or isoproterenol stimulation on tilt testing outcome was analyzed.

RESULTS

Head-up tilt testing demonstrated to have a good overall ability to discriminate between symptomatic patients and asymptomatic controls with an area under the summary receiver-operating characteristics curve of 0.84 and an adjusted diagnostic odds ratio of 12.15 (p<0.001). A significant inverse relationship between sensitivity and specificity of tilt testing for each study was observed (p<0.001). At multivariate analysis, advancing age and a 60° tilt angle showed a significant effect in reducing sensitivity and increasing specificity of the test. Nitroglycerine significantly raised tilt testing sensitivity by maintaining a similar specificity in comparison to isoproterenol.

CONCLUSIONS

The results from this meta-analysis show the high overall performance of HUT for diagnosing vasovagal syncope. Our findings provide useful information for evaluating clinical and instrumental parameters together with pharmacological stressors influencing HUT accuracy. This could allow the drawing of tilt testing protocols tailored on the diagnostic needs of each patient with unexplained syncope.

Recurrent syncope in patients with carotid sinus hypersensitivity

Syncope recurrence in pacemaker-implanted subjects for the cardio-inhibitory response to sinus carotid massage (SCM) was investigated. The study-hypothesis was that recurrences had significant vasodepressor responses that could justify the loss of consciousness. Forty-six patients were enrolled (16 patients and 30 controls), followed and revaluated after 5–7 years. At the end of follow-up, significant differences were found between patients and controls in mean SCM SAP (87 versus 106 mmHg) and reduction in mean SCM SAP (59 versus 38 mmHg); in the number of symptomatic subjects soon after SCM (5 versus 1); and in the number of subjects suffering from orthostatic hypotension. A subgroup of 13 patients showed significantly different hypotensive responses to SCM compared with the values observed at study recruitment. The data showed that some subjects with a defined hemodynamic pattern in response to SCM may change their characteristics and have spontaneous and/or provocative symptoms. These data explain the syncopal relapses, and suggest the presence of autonomic dysregulation in individuals with carotid sinus hypersensitivity.

Carotid sinus syndrome is common in very elderly patients undergoing tilt table testing and carotid sinus massage because of syncope or unexplained falls

BACKGROUND AND AIMS

Although the incidence of falls and syncope increase with age, the underlying mechanisms are not fully understood, particularly in very old patients. We report diagnostic outcomes of tilt table and carotid sinus massage (TT/CSM) testing in a population of older old subjects (82% over 80 years of age) referred for TT/CSM from a falls clinic for assessment of syncope or unexplained falls.

METHODS

Prospective observational study between January 1, 2001 and January 1, 2005 involving 290 consecutive subjects undergoing TT/CSM testing according to European Society of Cardiology guidelines for the diagnosis and management of syncope.

RESULTS

Combination of TT/CSM provided a positive result in 62% of subjects, and was significantly more likely to be positive in subjects over the age of 80 (68% vs 50%, p=0.001). Carotid sinus syndrome (CSS) was the most common diagnosis, and was significantly more common in subjects over 80 (48% vs 34%, p=0.022) particularly due to a higher incidence of mixed CSS (16% vs 7%, p=0.023). There was no significant difference in the diagnosis of subjects referred due to falls and those reporting syncope (p=0.93). No cardiovascular or neurological adverse events occurred.

CONCLUSIONS

In our cohort of very elderly patients, the diagnostic accuracy of tilt testing and carotid sinus massage was high and adverse incidents absent when testing was indicated by a geriatrician experienced in the assessment of falls and syncope. We advocate the use of TT/CSM testing as part of a comprehensive falls/syncope assessment for the diagnostic evaluation of older patients presenting with unexplained falls and/or syncope in whom structured assessment has not identified a cause for their symptoms.

Transcellular and paracellular pathways of transepithelial fluid secretion in Malpighian (renal) tubules of the yellow fever mosquito Aedes aegypti

Isolated Malpighian tubules of the yellow fever mosquito secrete NaCl and KCl from the peritubular bath to the tubule lumen via active transport of Na(+) and K(+) by principal cells. Lumen-positive transepithelial voltages are the result. The counter-ion Cl(-) follows passively by electrodiffusion through the paracellular pathway. Water follows by osmosis, but specific routes for water across the epithelium are unknown. Remarkably, the transepithelial secretion of NaCl, KCl and water is driven by a H(+) V-ATPase located in the apical brush border membrane of principal cells and not the canonical Na(+), K(+) -ATPase. A hypothetical cation/H(+) exchanger moves Na(+) and K(+) from the cytoplasm to the tubule lumen. Also remarkable is the dynamic regulation of the paracellular permeability with switch-like speed which mediates in part the post-blood-meal diuresis in mosquitoes. For example, the blood meal the female mosquito takes to nourish her eggs triggers the release of kinin diuretic peptides that (i) increases the Cl(-) conductance of the paracellular pathway and (ii) assembles V(1) and V(0) complexes to activate the H(+) V-ATPase and cation/H(+) exchange close by. Thus, transcellular and paracellular pathways are both stimulated to quickly rid the mosquito of the unwanted salts and water of the blood meal. Stellate cells of the tubule appear to serve a metabolic support role, exporting the HCO(3)(-) generated during stimulated transport activity. Septate junctions define the properties of the paracellular pathway in Malpighian tubules, but the proteins responsible for the permselectivity and barrier functions of the septate junction are unknown.

Unexplained syncope--is screening for carotid sinus hypersensitivity indicated in all patients aged >40 years?

OBJECTIVE

To determine the frequency, age distribution and clinical presentation of carotid sinus hypersensitivity (CSH) among 373 patients (age range 15-92 years) referred to two autonomic referral centres during a 10-year period.

METHODS

Carotid sinus massage (CSM) was performed both supine and during 60 degree head-up tilt. Beat-to-beat blood pressure, heart rate and a three-lead electrocardiography were recorded continuously. CSH was classified as cardioinhibitory (asystole > or = 3 s), vasodepressor (systolic blood pressure fall > or = 50 mm Hg) or mixed. All patients additionally underwent autonomic screening tests for orthostatic hypotension and autonomic failure.

RESULTS

CSH was observed in 13.7% of all patients. The diagnostic yield of CSM was nil in patients aged < 50 years (n = 65), 2.4% in those aged 50-59 years (n = 82), 9.1% in those aged 60-69 years (n = 77), 20.7% in those aged 70-79 years (n = 92) and reached 40.4% in those > 80 years (n = 57). Syncope was the leading clinical symptom in 62.8%. In 27.4% of patients falls without definite loss of consciousness was the main clinical symptom. Mild and mainly systolic orthostatic hypotension was recorded in 17.6%; evidence of sympathetic or parasympathetic dysfunction was found in none.

CONCLUSIONS

CSH was confirmed in patients > 50 years, the incidence steeply increasing with age. The current European Society of Cardiology guidelines that recommend testing for CSH in all patients > 40 years with syncope of unknown aetiology may need reconsideration. Orthostatic hypotension was noted in some patients with CSH, but evidence of sympathetic or parasympathetic failure was not found in any of them.

Role of autonomic evaluation in the diagnosis and management of syncope

There are many causes of syncope that include neurological (autonomic and non-autonomic), cardiac and psychiatric causes, amongst others. Disorders of the autonomic nervous system, either intermittent or fixed, are increasingly recognised as contributing to a large proportion of syncope. However, the majority of guidelines focus on cardiological and neurological evaluation in these disorders. In this overview we focus specifically on the role of autonomic evaluation. This has dual purposes; to aid the diagnosis and cause of syncope, and furthermore to provide information to understand the pathophysiological basis of syncope and thus improve management of such disorders.

The management of patients with carotid sinus syndrome: is pacing the answer?

Carotid sinus syndrome (CSS) is an under recognized cause of recurrent unexplained syncope and potentially of recurrent falls in the elderly. The mechanisms that lead to syncope in patients with CSS remain debated. However, evidence for both peripheral and central alterations have been recently reported. The diagnosis of CSS is challenging and a high clinical suspicion is usually needed to make the diagnosis. Clinical presentation may be typical and characterized by a clear association between accidental manipulation of the carotid sinus and the presentation of syncope. On the other hand, recurrent unexplained syncope and unexplained falls may be the clinical presentation of patients with CSS without a specific trigger. Carotid sinus hypersensitivity documented by carotid sinus massage (CSM) may be the only finding indicating the possibility of CSS as the cause of syncope. In older patients with recurrent unexplained syncope and a negative diagnostic work-up, carotid sinus massage both in the supine and upright positions is recommended. CSS may present primarily as a cardioinhibitory response or a true vasodepressor response. Therapy should address any underlying pathology if present, and be directed to either prevent cardioinhibition, vasodepression or both alterations. A variety of medical therapies have been used with unclear effects. No appropriately designed controlled clinical trials have been performed comparing pacing with medical therapy. Nonetheless, available information indicates that pacing may have a strong beneficial effect and prevents recurrence of syncope in patients with CSS. The present paper critically reviews the latest insights in the pathophysiology, diagnosis and management of CSS.

[Syncope in the elderly: diagnostic utility of carotid sinus massage in the head-up tilt test]

A 71-year-old man presented with a 6-month history of fainting. Consciousness was quickly regained without clouding or confusion. Ancillary investigations were inconclusive and he was treated with carbamazepine. The fainting spells did not cease and he was referred for a tilt-table test exam. In the head-up position (table tilted at 60 degrees), massage of the carotid sinus was immediately followed by asystole, unconsciousness, and a sharp drop in arterial pressure for 5 seconds. The same procedure in the lying position did not elicit clinical symptoms or haemodynamic imbalance. A diagnosis of carotid sinus hypersensitivity with a cardio-inhibitory response pattern was made. Carbamazepine was withdrawn and a double-chamber pacemaker was implanted in his right ventricle. He remained symptom-free for the ensuing 18 months. This case supports the diagnostic utility of carotid sinus massage during the head-up tilt test in patients with unexplained non-convulsive loss of consciousness.

Carotid sinus syndrome

This article reviews the recent literature about carotid sinus syndrome. It looks principally at the various ways in which it may present, the limited knowledge of its pathophysiology, and the role of carotid sinus massage in the investigation of carotid sinus syndrome.

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.

The relationship between health-related quality of life and frequency of spells in patients with syncope

Chronic syncope has a wide range of symptom burden, and anecdotal data suggest substantial but variable physical and psychosocial morbidity. We hypothesized that health-related quality of life (HRQL) is impaired in syncope patients and the degree of impairment is proportional to syncope frequency. The EuroQol EQ-5D was completed by 136 patients (79 female and 57 male) with mean age 40 (SD = 17) prior to assessment. HRQL was substantially impaired in syncope patients compared to population norms in all five dimensions of health measured by the EQ-5D. In patients with six or more lifetime syncopal spells there was a significant (P < 0.001) negative relationship between the frequency of spells and overall perception of health, which was not evident in those who had a history of less than six lifetime spells. These relationships were maintained after controlling for comorbid conditions.