Symptomatic presentation of carotid sinus hypersensitivity is associated with impaired cerebral autoregulation

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.

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.

Stroke and Falls-Clash of the Two Titans in Geriatrics

Both stroke and falls are common conditions affecting the older adult. Despite stroke being considered a well-established major risk factor for falls, there remains no evidence for effective prevention strategies for falls specifically for stroke survivors. Previous observational studies evaluating falls risk factors in stroke have mainly been uncontrolled and found similar risk factors for stroke populations compared to general older populations. Specific risk factors, however, are likely to play a greater role in stroke survivors including unilateral weakness, hemisensory or visual neglect, impaired coordination, visual field defects, perceptual difficulties and cognitive issues. In addition, individuals with stroke are also more likely to have other associated risk factors for falls including diabetes, falls risk increasing drugs, atrial fibrillation, and other cardiovascular risk factors. While anticoagulation is associated with increased risk of intracranial bleeding after a fall, the risk of suffering a further stroke due to atrial fibrillation outweigh the risk of bleeding from a recurrent fall. Similarly, while blood pressure lowering medications may be linked to orthostatic hypotension which in turn increases the risk of falls, the benefit of good blood pressure control in terms of secondary stroke prevention outweighs the risk of falls. Until better evidence is available, the suggested management approach should then be based on local resources, and published evidence for fall prevention. Multicomponent exercise and individually tailored multifactorial interventions should still be considered as published evidence evaluating the above have included stroke patients in their study population.

Neurocardiovascular Instability and Cognition

Neurocardiovascular instability (NCVI) refers to abnormal neural control of the cardiovascular system affecting blood pressure and heart rate behavior. Autonomic dysfunction and impaired cerebral autoregulation in aging contribute to this phenomenon characterized by hypotension and bradyarrhythmia. Ultimately, this increases the risk of falls and syncope in older people. NCVI is common in patients with neurodegenerative disorders including dementia. This review discusses the various syndromes that characterize NCVI icluding hypotension, carotid sinus hypersensitivity, postprandial hypotension and vasovagal syncope and how they may contribute to the aetiology of cognitive decline. Conversely, they may also be a consequence of a common neurodegenerative process. Regardless, recognition of their association is paramount in optimizing management of these patients.