Wave reflection analysis of the human cerebral circulation during syncope

Diehl, Rolf R.

doi:10.1016/j.autneu.2006.08.005

Cited by 2 publications

(2 citation statements)

References 19 publications

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“…In recent years we [ 1 , 22 , 23 ] and others [ 24 – 26 ] have been working on algorithms, taking into account photoplethysmogram (PPG) morphology features, towards a better characterization of patient status in different settings. In line with previous studies, we found that pulse wave characteristics are useful to characterize BP changes [ 22 , 27 ]. In this context, the pulse arrival time (PAT) is a simple and reliable parameter to characterize blood pressure changes ( Figure 1 ).…”

Section: Syncope Predictionsupporting

confidence: 91%

Wearable Sensors in Syncope Management

et al. 2015

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Syncope is a common disorder with a lifetime prevalence of about 40%. Implantable cardiac electronic devices, including implantable loop recorders (ILR) and implantable cardioverter-defibrillators (ICD), are well established in syncope management. However, despite the successful use of ILR and ICD, diagnosis and therapy still remain challenging in many patients due to the complex hemodynamic interplay of cardiac and vascular adaptations during impending syncopes. Wearable sensors might overcome some limitations, including misdiagnosis and inappropriate defibrillator shocks, because a variety of physiological measures can now be easily acquired by a single non-invasive device at high signal quality. In neurally-mediated syncope (NMS), which is the most common cause of syncope, advanced signal processing methodologies paved the way to develop devices for early syncope detection. In contrast to the relatively benign NMS, in arrhythmia-related syncopes immediate therapeutical intervention, predominantly by electrical defibrillation, is often mandatory. However, in patients with a transient risk of arrhythmia-related syncope, limitations of ICD therapy might outweigh their potential therapeutic benefits. In this context the wearable cardioverter-defibrillator offers alternative therapeutical options for some high-risk patients. Herein, we review recent evidence demonstrating that wearable sensors might be useful to overcome some limitations of implantable devices in syncope management.

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Section: Syncope Predictionsupporting

confidence: 91%

Wearable Sensors in Syncope Management

et al. 2015

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“…The summation with the reflected pressure wave(s) will increase systolic pulse amplitude or area, yet serve to impede forward flow. There is some evidence that pressure reflections are evident even very early in systole, perhaps deriving from some cerebral site [68][69][70]. This was one of the primary motivations for developing the Initial Systolic Pulse (ISP) measure described above-one that would be expected to be largely uncontaminated by reflected activity.…”

Section: Discussionmentioning

confidence: 97%

Decoding carotid pressure waveforms recorded by laser Doppler vibrometry: Effects of rebreathing

Casaccia

Sirevaag

Richter

et al. 2014

AIP Conference Proceedings

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The principal goal of this study was to assess the capability of the laser Doppler vibrometry (LDV) method for assessing cardiovascular activity. A rebreathing task was used to provoke changes within individuals in cardiac and vascular performance. The rebreathing task is known to produce multiple effects, associated with changes in autonomic drive as well as alterations in blood gases. The rise in CO 2 (hypercapnia), in particular, produces changes in the cerebral and systemic circulation. The results from a rebreathing task (involving rebreathing the same air in a rubber bag) are presented for 35 individuals. The LDV pulse was measured from a site overlying the carotid artery. For comparison and validation purposes, several conventional measures of cardiovascular function were also obtained, with an emphasis on the electrocardiogram (ECG), continuous blood pressure (BP) from the radial artery, and measures of myocardial performance using impedance cardiography (ICG). During periods of active rebreathing, ventilation increased. The conventional cardiovascular effects included increased mean arterial BP and systemic vascular resistance, and decreased cardiac stroke volume (SV) and pulse transit time (PTT). These effects were consistent with a pattern of -adrenergic stimulation. During the immediate post-rebreathing segments, in contrast, mean BP was largely unaffected but pulse BP increased, as did PTT and SV, whereas systemic vascular resistance decreased-a pattern consistent with -adrenergic effects in combination with the direct effects of hypercapnia on the vascular system. Measures of cardiovascular activity derived from the LDV pulse velocity and displacement waveforms revealed patterns of changes that mirrored the results obtained using conventional measures. In particular, the ratio of the maximum early peak in the LDV velocity pulse to the maximum amplitude of the LDV displacement pulse (in an early systolic interval) closely mirrored the conventional SV effects. Additionally, changes in an augmentation ratio (computed as the maximum amplitude of the LDV displacement pulse during systole / amplitude at the end of the incident wave) were very similar to changes in systemic vascular resistance. Heart rates measured from the ECG and LDV were nearly identical. These preliminary results suggest that measures derived using the non-contact LDV technique can provide surrogate measures for those obtained using impedance cardiography.

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Wave reflection analysis of the human cerebral circulation during syncope

Cited by 2 publications

References 19 publications

Wearable Sensors in Syncope Management

Wearable Sensors in Syncope Management

Decoding carotid pressure waveforms recorded by laser Doppler vibrometry: Effects of rebreathing

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