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Lookup NU author(s): Professor Raj Kalaria,
Dr Clive Ballard
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Neurocardiovascular instability (NCVI, neurally mediated disorders causing hypotension with or without bradycardia) represents abnormal neural control of the cardiovascular system and presents as dizziness, syncope, or falls. The mechanisms underpinning NCVI are incompletely understood. The three most common disorders are carotid sinus syndrome (CSS), orthostatic hypotension (OH), and vasovagal syndrome (VVS): CSS, cardioinhibition > 3 s and/or vasodepressor response greater than or equal to 50 mmHg drop in systolic pressure during carotid sinus stimulation; OH: fall in systolic blood pressure > 20 mmHg during standing; V VS: cardioinhibition > 3 s and/or vasodepressor response > 50 mmHg during prolonged head-up tilting. In fallers with cognitive impairment or dementia, the prevalence of NCVI is 70%. Multifactorial interventions, including treatment of NCVI, significantly reduce falls and syncope. The predominant components of NCVI in fallers with cognitive impairment and dementia are CSS and OH. In Lewy body and Alzheimer's dementia, the prevalence of NCVI is up to 60%, again predominantly CSS and OH. The prevalence of cardio-inhibitory carotid sinus hypersensitivity is particularly high in Lewy body dementia-41% compared with 12% in Alzheimer's disease and 3% in case controls. In addition, patients with Lewy body dementia have greater heart rate slowing (>2 s) and falls in systolic blood pressure (>20 mmHg) than those with Alzheimer's disease or controls during carotid sinus stimulation. The extent of deep white matter hyperintensities on MRI correlates with systolic fall during carotid sinus stimulation (R = 0.58; p < 0.005), suggesting a possible causal association between bradyarrhythmia-induced hypotension and microvascular pathology. NCVI is common in patients with dementia and may be a reversible cause of falls and syncope. Repeated hypotensive episodes may exaggerate cognitive decline in these patients.
Author(s): Kenny RAM, Kalaria R, Ballard C
Editor(s): DeLaTorre, J.C., Kalaria, R., Nakajima, K., Nagata, K.
Publication type: Conference Proceedings (inc. Abstract)
Publication status: Published
Conference Name: Alzheimer's Disease: Vascular Etiology and Pathology
Year of Conference: 2002
Publisher: New York Academy of Sciences
Library holdings: Search Newcastle University Library for this item
Series Title: Annals of the New York Academy of Sciences