Cerebral Oxygenation Responses to Standing in Young Patients with Vasovagal Syncope

Vasovagal syncope (VVS) is common in young adults and is attributed to cerebral hypoperfusion. However, during active stand (AS) testing, only peripheral and not cerebral hemodynamic responses are measured. We sought to determine whether cerebral oxygenation responses to an AS test were altered in young VVS patients when compared to the young healthy controls. A sample of young healthy adults and consecutive VVS patients attending a Falls and Syncope unit was recruited. Continuous beat-to-beat blood pressure (BP), heart rate, near-infrared spectroscopy (NIRS)-derived tissue saturation index (TSI), and changes in concentration of oxygenated/deoxygenated Δ[O₂Hb]/Δ[HHb] hemoglobin were measured. BP and NIRS-derived features included nadir, peak, overshoot, trough, recovery rate, normalized recovery rate, and steady-state. Multivariate linear regression was used to adjust for confounders and BP. In total, 13 controls and 27 VVS patients were recruited. While no significant differences were observed in the TSI and Δ[O₂Hb], there was a significantly smaller Δ[HHb] peak-to-trough and faster Δ[HHb] recovery rate in VVS patients, independent of BP. A higher BP steady-state was observed in patients but did not remain significant after multiple comparison correction. Young VVS patients demonstrated a similar cerebral circulatory response with signs of altered peripheral circulation with respect to the controls, potentially due to a hyper-reactive autonomic nervous system. This study sets the grounds for future investigations to understand the role of cerebral regulation during standing in VVS.

Asymptomatic orthostatic hypotension and risk of falls in community-dwelling older people

INTRODUCTION

Many older people with orthostatic hypotension (OH) may not report typical symptoms of dizziness, light-headedness or unsteadiness. However, the relationships between OH and falls in the absence of typical symptoms are not yet established.

METHODS

Continuous orthostatic blood pressure (BP) was measured during active stand using a Finometer at Wave 1 of The Irish Longitudinal Study on Ageing in participants aged ≥ 70 years.OH, with and without dizziness, was defined as a sustained drop in systolic BP ≥ 20 and/or diastolic BP ≥ 10 mm Hg at 30, 60 and 90 seconds post-standing.The association between symptoms of dizziness and orthostatic BP was assessed with multi-level mixed-effects linear regression; logistic regression models assessed the longitudinal relationship between OH and falls at 6-year follow-up (Waves 2-5).

RESULTS

Almost 11% (n = 934, mean age 75 years, 51% female) had OH, two-thirds of whom were asymptomatic.Dizziness was not associated with systolic BP drop at 30 (β = 1.54 (-1.27, 4.36); p = 0.256), 60 (β = 2.64 (-0.19, 5.47); p = 0.476) or 90 seconds (β = 2.02 (-0.91, 4.95); p = 0.176) after standing in adjusted models.Asymptomatic OH was independently associated with unexplained falls (odds ratio 2.01 [1.11, 3.65]; p = 0.022) but not explained falls (OR 0.93 [0.53, 1.62]; p = 0.797) during follow-up.

CONCLUSIONS

Two-thirds of older people with OH did not report typical symptoms of light-headedness. Dizziness or unsteadiness after standing did not correlate with the degree of orthostatic BP drop or recovery. Participants with asymptomatic OH had a significantly higher risk of unexplained falls during follow-up, and this has important clinical implications for the assessment of older people with falls.

336 ASYMPTOMATIC ORTHOSTATIC HYPOTENSION AND RISK OF FALLS IN COMMUNITY-DWELLING OLDER PEOPLE

Background

Many older people with Orthostatic Hypotension (OH) may not report typical symptoms of dizziness, light-headedness, or unsteadiness. However, the relationships between OH and falls in the absence of typical symptoms are not yet established.

Methods

Continuous orthostatic BP was measured during active stand using a Finometer at Wave 1 of TILDA in participants aged≥70 years. OH, with and without dizziness, was defined as a sustained drop in systolic BP≥20 and/or diastolic BP≥10 mm Hg at 30, 60 and 90 seconds post-standing. The association between symptoms of dizziness and orthostatic BP was assessed with multi-level mixed-effects linear regression; logistic regression models assessed the longitudinal relationship between OH and falls at 6-year follow-up (Waves 2-5).

Results

Almost 11% (n=934; mean age: 75 years; 51% female) had OH, two-thirds of whom were asymptomatic. Dizziness was not associated with systolic BP drop at 30 (β=1.54; –1.27, 4.36; p=0.256), 60 (β=2.6; –0.19, 5.47; p =0.476) or 90 (β=2.02; –0.91, 4.95; p=0.176) seconds after standing in adjusted models. Asymptomatic OH was independently associated with unexplained falls (Odds Ratio: 2.01; 1.11, 3.65; p=0.022) but not explained falls (OR 0.93; 0.53, 1.62; p=0.797) during follow-up.

Conclusion

Two-thirds of older people with OH did not report typical symptoms of light-headedness. Dizziness or unsteadiness after standing did not correlate with the degree of orthostatic BP drop or recovery. Participants with asymptomatic OH had a significantly higher risk of unexplained falls during follow-up, and this has important clinical implications for the assessment of older people with falls.

302 MONITORING FALLS RISK IN THE COMMUNITY USING AN IMPLANTABLE CARDIAC MONITOR WITH EMBEDDED ACCELEROMETER

Background

Falls are the most common cause of injury amongst older adults. Falls can lead to hospitalisation, functional decline and are associated with increased morbidity and mortality. The holy grail for clinicians would be to predict increased likelihood of falls occurring and intervene before the event. Understanding underlying dynamic biophysiological changes may therefore inform novel predictor models and falls prevention. This study examines activity and cardiac data acquired from an implanted Medtronic Reveal LINQ™ Insertable Cardiac Monitor (ICM) with an embedded tri-axial accelerometer.

Methods

Thirty participants with at least one unexplained fall in the previous two years were prospectively recruited. All met criteria for ICM insertion following comprehensive assessment. Participants were followed for one year and attended every three-months for cardiac and gait assessment. Information pertaining to activity levels, posture changes and cardiac parameters were collected daily from the device. Summary metrics and trends were collected for inclusion in a continual assessment of falls risk.

Results

Mean age of participants was 68.0 years (±9.3). 19/30 (63.3%) were female. 22/30 (73.3%) had at least one cardiovascular condition documented in their medical history. There was seasonal variation in activity levels. Twelve participants had falls and cardiovascular, gait and activity variables were examined at the time of a fall to determine any trends in biophysiological changes.

Conclusion

Causes of falls are usually multifactorial. A holistic approach is necessary to manage and minimise risk factors. The use of an ICM with an embedded tri-axial accelerometer allows clinicians to formulate an algorithm to determine if a person is at an increased risk of falling based on biophysiological changes. This may create an opportunity for falls to be predicted and prevented.

136 DIABETES IS ASSOCIATED WITH IMPAIRED PERIPHERAL AND CEREBRAL HAEMODYNAMIC RESPONSES IN OLDER ADULTS

Background

Diabetes is associated with slower gait speed and adverse brain health outcomes in older adults. However, the putative mechanisms underlying these associations remain poorly explored. One such mechanism is via altered cerebral perfusion, which may represent an important intermediate phenotype in the association between diabetes and slower gait. We assessed the impact of diabetes on peripheral and cerebral haemodynamic responses during active stand as part of The Irish Longitudinal Study of Ageing (TILDA).

Methods

We assessed: (i) peripheral haemodynamic responses (heart rate, blood pressure, cardiac output) using finometry and (ii) Tissue Saturation Index (TSI) using Near-Infrared Spectroscopy (NIRS) during active stand in older adults.

Function-on-scalar regressions were used to model the impact of diabetes on the dynamic response to standing. Subsequently, multivariable linear models were used to model usual gait speed.

Results

Of 3,011 older adults (mean age: 64.2; 55.2% female) completing active stand, diabetes (n =193, 6.4%) was associated with significantly higher heart rate (mean 3.2, s.e. 0.02 bpm), higher cardiac output (mean 0.16, s.e. 0.04 L/min) and lower systolic blood pressure (mean –6.9, s.e. 1.8 mmHg) during standing. Additionally, diabetes was associated with significantly lower TSI from 10 seconds post-stand (mean –1.2%, s.e. 0.49%). Associations persisted following robust covariate adjustment. Diabetes was associated with significantly slower gait speed (-5.3 cm/s, CI (-8.4,-2.1)). In analysing the relationship between cerebral perfusion and gait speed, poorer recovery of TSI at 60-120 seconds post standing was associated with slower gait speed (0.53 cm/s slower gait speed per unit increase in TSI, p = 0.007).

Conclusion

Diabetes is associated with impaired peripheral and cerebral haemodynamic responses in addition to slower gait speed in community-dwelling older adults. Neuro-cardiovascular instability and altered cerebral perfusion may represent an important intermediate phenotype between diabetes and adverse health outcomes in older adults.

Increased multimorbidity is associated with impaired cerebral and peripheral hemodynamic stabilization during active standing

Background

Age‐related morbidities and frailty are associated with impaired blood pressure (BP) and heart rate (HR) recovery after standing. Here we investigate how multimorbidity affects cerebral and peripheral hemodynamics during standing in a large sample of older patients.

Methods

Patients were recruited from a national Falls and Syncope Unit. They underwent an active stand test (5–10 min lying +3 min standing) with monitoring of continuous BP, HR, total peripheral resistance (TPR), stroke volume (SV), and a near‐infrared spectroscopy (NIRS) derived cerebral tissue saturation index (TSI). A multimorbidity count was derived from a 26‐item list of conditions. Features derived from the signals included: nadir, overshoot, value at 30 s, steady‐state and recovery rate. Robust linear regression was used to assess the association between multimorbidity, TSI and peripheral hemodynamics while correcting for covariates. A p‐value <0.05 was considered statistically significant.

Results

Multimorbidity was associated with poorer recovery of TSI at 30 s after standing (β: −0.15, CI:[−0.25–0.06], p = 0.009) independent of all peripheral hemodynamics. Impaired diastolic BP (DBP) recovery at 30s (β:−1.34, CI:[−2.29–0.40], p = 0.032), DBP steady‐state (β:−1.18, CI:[−2.04–0.32], p = 0.032), TPR overshoot‐to‐nadir difference (β:−0.041, CI:[−0.070–0.013], p = 0.045), and SV at 30s (β:1.30, CI:[0.45 2.15], p = 0.027) were also associated with increasing multimorbidity. After sex stratification, only females demonstrated impaired TSI with multimorbidity at overshoot (β: −0.19, CI: [−0.32 ‐0.07], p = 0.009), 30 s (β: −0.22 [−0.35–0.10], p = 0.005) and steady‐state (β: −0.20, CI:[−0.35–0.04], p = 0.023), independent of peripheral hemodynamics.

Conclusions

Transient cerebral oxygenation and peripheral hemodynamic responses are impaired with multimorbidity (frailty) in older patients, particularly in females. This study demonstrates the feasibility of using NIRS in this clinical context and may inform the development of clinical management strategies targeting both cerebral oxygenation and blood pressure impairments in patients with faints and falls.

239 IS ORTHOSTATIC HYPOTENSION ASSOCIATED WITH ALTERED CEREBRAL PERFUSION DURING ACTIVE STANDING?

Background

Orthostatic Hypotension (OH) is associated with poor health outcomes in later life including depression, cognitive impairment, frailty and falls. Whilst it is hypothesised that OH compromises cerebral autoregulation leading to hypoperfusion, this has not been robustly demonstrated to date. This study investigated the association between OH and cerebral perfusion during orthostasis using a non-invasive surrogate of cerebral perfusion, Near Infrared Spectroscopy (NIRS).

Methods

Four hundred and ninety one participants (58% female, median age 65, IQR 38–92) attending a falls and syncope service underwent measurement of beat-to-beat blood pressure (BP) by finometry and real-time frontal lobe perfusion (% TSI: Tissue Saturation Index) by NIRS during the active stand manoeuvre. We examined the association between OH and change in cerebral perfusion (delta TSI) using mixed-effects linear regression, with adjustment for important clinical covariates.

Results

Nearly two-fifths of the sample (189/491,38.5%) met criteria for OH occurring between 30 and 120 seconds after standing. Using mixed effects linear regression models, we observed a significant relationship between OH and TSI at the same timepoint (β −0.53, −0.59 to −0.46, p &lt; 0.001) which persisted following adjustment for confounders including age, sex, baseline blood pressure, cerebrovascular and cardiovascular disease, depression/anxiety, diabetes, systolic blood pressure, antihypertensives, and antidepressants (β −0.51, −0.58 to −0.44, p &lt; 0.001). Cerebral perfusion levels differed for those with OH compared to those without.

Conclusion

OH is independently associated with lower frontal lobe cerebral perfusion. This association may indicate disruption to dynamic cerebral autoregulation and explain the significant link between OH and poor health outcomes.

Impaired autonomic function after incomplete revascularisation

Introduction

Incomplete cardiac revascularisation (ICR) assessed by residual SYNTAX score (rSs) is associated with increased 5-year mortality. Furthermore, in the general population, our group has demonstrated that impaired autonomic function determined by heart rate recovery time between 10 and 20 s (HRR_10–20) following an active stand is associated with increased all-cause mortality.

Purpose

We hypothesised that ICR would be associated with impaired autonomic function determined by HRR_10–20.

Methods

After ethical approval and informed consent, consecutive patients attending cardiac rehabilitation in a tertiary referral centre were enrolled. All patients had percutaneous coronary revascularisation. During an active stand, real-time heart rate, blood pressure and ECG recordings were taken using non-invasive digital photoplethysmography and HRR_10–20 determined. Assessment of autonomic function was performed by determining speed of HRR_10–20 post-orthostatic challenge.

Patients with an rSs >0 were considered incompletely revascularised and those with an rSs of 0 fully revascularised. Demographic data were recorded and statistical analysis performed.

Results

Patients (n=53) comprised those with complete revascularisation (CR) (n=37) and ICR (n=16). In the ICR group, mean rSs was 9.4.

HRR_10–20 was impaired in the ICR group (−3±0.60) compared with the CR cohort (−6.56±0.52) (p<0.0001). Completeness of revascularisation was strongly associated with HRR_10–20 (Pearson’s correlation coefficient 0.529; p<0.0001). Baseline demographics did not differ significantly. Use of rate-limiting medication was similar between cohorts (beta blockers, calcium channel blockers, ivabradine).

Conclusions

Our data confirm significant correlation between ICR and impaired autonomic function determined by speed of heart rate recovery. Thus, determining autonomic dysfunction post-ICR may identify those at increased mortality risk.

Frailty is associated with impaired cerebral oxygenation recovery during

 

Frailty is associated with impaired peripheral circulatory responses to standing in older adults. However, little is known about how frailty affects cerebrovascular function during such activities of daily living. Here we investigate the association between frailty and cerebral oxygenation during standing in a large clinical cohort of fallers and fainters.

Participants were recruited from a national Falls and Syncope unit and underwent an active stand test (5–10 minutes lying supine, 3 minutes standing) with concurrent monitoring of continuous blood pressure (BP) and heart rate (HR) and tissue saturation index (TSI) using near-infrared spectroscopy (NIRS). Frailty was measured using a count of deficits (27 morbidities). Robust linear regression was applied to study the association between features of dynamic cerebral oxygenation (changes from baseline at nadir, overshoot, 30s and steady state; and recovery rate) and frailty while correcting for covariates. A p-value &lt;0.05 was considered significant.

Frailty was associated with deficits in TSI at 30s after standing (β: −0.165, CI: (−0.261, −0.069), p=0.005), as well as a lower diastolic BP at 30s (β: −1.346, CI: (−2.287, −0.405), p=0.032) and standing steady-state (β: −1.182, CI: (−2.038, −0.325), p=0.032). When stratified by gender, frailty was associated in women with a lower TSI at overshoot (β: −0.174, CI: (−0.312, −0.037), p=0.043) and 30s (β: −0.216 (−0.344, −0.089), p=0.010), and impaired DBP recovery at overshoot (β: −1.623, CI: (−2.865, −0.391), p=0.045) and attenuated HR response at 30s (β: −0.701, CI: (−1.246, −0.155), p=0.036). No associations were found in men.

Impaired cerebral oxygenation and BP responses to standing are associated with frailty in patients with falls and syncope, with stronger effects in women, suggesting that frailty may increase risk of hypoperfusion and consequent syncope, falls, and brain ageing. Our results demonstrate the clinical utility and feasibility of using NIRS in this context which can be used to further personalise patient management.

Funding Acknowledgement

Type of funding sources: Public grant(s) – National budget only. Main funding source(s): Irish Research Council Cerebral oxygenation and frailty

Cerebral perfusion responses to active standing are attenuated in patients with vasovagal syncope

Funding Acknowledgements

Type of funding sources: Public grant(s) – National budget only. Main funding source(s): Irish Research Council (IRC): Government of Ireland Postgraduate Scholarship Programme 2018, Dublin, Ireland Fundació Universitària Agustí Pedro i Pons, Universitat de Barcelona, Barcelona, Spain

Background

Syncope is a transient loss of consciousness due to cerebral hypoperfusion. While traditionally peripheral haemodynamics are monitored during clinical assessment of syncope, relatively little is known about cerebrovascular haemodynamics during orthostasis in patients with syncope.

Purpose

Here we investigated whether young patients with syncope present an altered cerebral perfusion when compared to healthy controls. Given potential hyper-reactivity of the autonomic nervous system previously reported in these patients, we hypothesise that an overly active cerebral autoregulation will be present in patients with syncope.

Methods

Consecutive patients were prospectively recruited from a National Falls and Syncope Unit, and a convenience sample of young healthy community dwelling adults was recruited from a local university (16-30 years). Participants performed a 3 minute active stand test with continuous measurement of beat-to-beat peripheral haemodynamics (blood pressure (BP), heart rate (HR)) and changes in concentration of oxygenated Δ[O2Hb] and deoxygenated Δ[HHb] haemoglobin were derived from a near-infrared spectroscopy (NIRS) monitor. Baseline, steady state and other time domain features were derived for Δ[O2Hb] (nadir, overshoot, overshoot-to-nadir, overshoot-to-nadir recovery rate) and Δ[HHb] (peak, trough, peak-to-trough, peak-to-trough recovery rate) and multiple linear regression was used to compare differences between the two groups correcting for covariates (p &lt; 0.05 significant).

Results

Patients (n = 40) were younger (20(5.5) vs 23(1) years, p = 0.003) than controls (n = 17) and were well matched in gender, weight, height, BMI and resting haemodynamics. Patients had a smaller Δ[O2Hb] overshoot-to-nadir difference (β: -0.749, CI:(-1.593 0.094), p = 0.08), a slower Δ[O2Hb] recovery rate (β: -0.186, CI:(-0.388 0.016), p = 0.071), and smaller Δ[HHb] peak-to-trough difference (β: -0.530, CI:( -0.921 0.138), p = 0.018) and slower Δ[HHb] recovery rate (β: -0.151, CI: (0.244 0.057), p = 0.008).

Conclusion

Patients with syncope had signs of an attenuated cerebral oxygenation response to an AS when compared to controls. We hypothesise that this is due to hyper-reactive cerebral autoregulation mechanism, which might be related to a hyper-sensitive autonomic system. Furthering our understanding of vasovagal syncope physiology can help inform future interventions and treatments. This study shows the clinical value of measuring cerebral perfusion using NIRS, an easy to use and readily applicable tool, in the assessment of syncope. Abstract Figure. Cerebral oxygenation upon standing

Do patients with syncope have a hyper-reactive autonomic nervous system?

Funding Acknowledgements

Type of funding sources: Public grant(s) – National budget only. Main funding source(s): Irish Research Council (IRC): Government of Ireland Postgraduate Scholarship Programme 2018, Dublin, Ireland Fundació Universitària Agustí Pedro i Pons, Universitat de Barcelona, Barcelona, Spain.

Background

The origin of syncope, a transient loss of consciousness due to cerebral hypoperfusion, remains unclear. Recent studies suggest that a hypersensitive autonomic nervous system might be involved in the pathophysiology of vasovagal syncope (VVS).

Purpose

Here we test the hypothesis that patients with VVS have a hyper-reactive autonomic nervous system by investigating the peripheral haemodynamic responses during a standing (AS) test in a group of young VVS patients vs a control group.

Methods

A prospective sample of consecutive patients from a National Falls and Syncope Unit was recruited, and a convenience sample of young healthy community dwelling adults was recruited from a local university (16-30 years). Participants performed a 3 minute AS with continuous measurement of beat-to-beat blood pressure (BP), heart rate (HR), and cerebral oxygenation measured with near infrared spectroscopy. Baseline, steady-state and other time domain features were obtained for systolic BP (SBP) (i.e. nadir, overshoot, overshoot-to-nadir, overshoot-to-nadir recovery rate) and for HR (i.e. peak, trough, peak-to-trough, peak-to-trough recovery rate). Multiple linear regression was used to compare these features between patients and controls while correcting for covariates (p &lt; 0.05 significant).

Results

Forty patients and 17 controls were included, the former group being younger ((20(5.5) vs 23(1) years, p = 0.003). During steady-state standing SBP was higher as compared to controls (β: 6.853, CI: (0.713 12.993), p = 0.029). Patient data trended toward lower steady-state HR (β: -5.262, CI:(-11.201 0.677), p = 0.081), together with a larger peak-to-trough difference (β: 7.212, CI:(1.329 -15.754), p = 0.096).

Conclusion

These results tend to support the hypothesis and previous literature suggesting the presence of autonomic hyper-reactivity in patients with syncope, presenting as an exaggerated peripheral circulatory response to standing. Understanding the pathophysiology of VVS can help us improve its assessment and develop better treatment pathways for these patients. Abstract Figure.

Near-infrared spectroscopy in evaluating psychogenic pseudosyncope-a novel diagnostic approach

BACKGROUND

Psychogenic pseudosyncope (PPS), a conversion disorder and syncope mimic, accounts for a large proportion of 'unexplained syncope'. PPS is diagnosed by reproduction of patients' symptoms during head-up tilt (HUT). Electroencephalogram (EEG), a time consuming and resource intensive technology, is used during HUT to demonstrate absence of cerebral hypoperfusion during transient loss of consciousness (TLOC). Near-infrared spectroscopy (NIRS) is a simple, non-invasive technology for continuous monitoring of cerebral perfusion. We present a series of patients for whom PPS diagnosis was supported by NIRS during HUT.

METHODS

Eight consecutive patients with suspected PPS referred to a syncope unit underwent evaluation. During HUT, continuous beat-to-beat blood pressure (BP), heart rate (HR) and NIRS-derived tissue saturation index (TSI) were measured. BP, HR and TSI at baseline, time of first symptom, presyncope and apparent TLOC were measured. Patients were given feedback and followed for symptom recurrence.

RESULTS

Eight predominantly female patients (6/8, 75%) aged 31 years (16-54) were studied with (5/8, 63%) having comorbid psychiatric diagnoses, and (5/8, 63%) presenting with frequent episodes of prolonged TLOC with eyes closed (6/8, 75%). All patients experienced reproduction of typical events during HUT. Systolic BP (mmHg) increased from baseline (129.7 (interquartile range [IQR] 124.9-133.4)) at TLOC (153.0 (IQR 146.7-159.0)) (P-value = 0.012). HR (bpm) increased from baseline 78 (IQR 68.6-90.0) to 115.7 (IQR 93.5-127.9) (P-value = 0.012). TSI (%) remained stable throughout, 71.4 (IQR 67.5-72.9) at baseline vs. 71.0 (IQR 68.2-73.0) at TLOC (P-value = 0.484).

CONCLUSIONS

NIRS provides a non-invasive surrogate of cerebral perfusion during HUT. We propose HUT incorporating NIRS monitoring in the diagnostic algorithm for patients with suspected PPS.

Orthostatic Hypotension, Cardiovascular Outcomes, and Adverse Events: Results From SPRINT

Orthostatic hypotension (OH) is frequently observed with hypertension treatment, but its contribution to adverse outcomes is unknown. The SPRINT (Systolic Blood Pressure Intervention Trial) was a randomized trial of adults, age ≥50 years at high risk for cardiovascular disease with a seated systolic blood pressure (BP) of 130 to 180 mm Hg and a standing systolic BP ≥110 mm Hg. Participants were randomized to a systolic BP treatment goal of either <120 or <140 mm Hg. OH was defined as a drop in systolic BP ≥20 or diastolic BP ≥10 mm Hg 1 minute after standing from a seated position. We used Cox models to examine the association of OH with cardiovascular disease or adverse study events by randomized BP goal. During the follow-up period (median 3years), there were 1170 (5.7%) instances of OH among those assigned a standard BP goal and 1057 (5.0%) among those assigned the intensive BP goal. OH was not associated with higher risk of cardiovascular disease events (primary outcome: hazard ratio 1.06 [95% CI, 0.78-1.44]). Moreover, OH was not associated with syncope, electrolyte abnormalities, injurious falls, or acute renal failure. OH was associated with hypotension-related hospitalizations or emergency department visits (hazard ratio, 1.77 [95% CI, 1.11-2.82]) and bradycardia (hazard ratio, 1.94 [95% CI, 1.19-3.15]), but these associations did not differ by BP treatment goal. OH was not associated with a higher risk of cardiovascular disease events, and BP treatment goal had no effect on OH's association with hypotension and bradycardia. Symptomless OH during hypertension treatment should not be viewed as a reason to down-titrate therapy even in the setting of a lower BP goal. Clinical Trial Registration URL: https://www.clinicaltrials.gov. Unique identifier: NCT01206062.

75 Is Cerebral Autoregulation Altered in Ageing? A Review

Introduction

Cerebral autoregulation (CA) ensures constant cerebral blood flow (CBF) in the face of blood pressure (BP) disturbances. While CA impairment is often implicated in the aetiology of age-related disorders e.g. falls, syncope, and brain ageing, there is conflicting evidence on the effect of normal or healthy ageing on cerebral autoregulation. Here we present results of a review investigating the effect of ageing on CA.

Methods

A search was performed in Pubmed using the search terms “cerebral autoregulation” AND (“ageing” OR “age” OR “older” OR “elderly”). Studies were included if they were human studies in English assessing CA in healthy volunteers (free from disease) in which the effect of ageing on CAR was studied. Exclusion criteria included non-human studies, diseased cohorts and studies not measuring CA.

Results

26 studies (n=1326 total participants, age range 12-88) meeting the inclusion/exclusion criteria were identified. Significant heterogeneity was noted in applied methodologies with 88% of studies using static and 53% using dynamic protocols to measure CA. Transcranial Doppler (88%) and Near Infrared Spectroscopy (NIRS) (11%) were the most commonly used. Transfer function analysis (TFA) (38%), the Autoregulatory Index (ARI) (15%), and wavelet analysis (11%) were used to derive CA metric. The majority of studies suggested that CA is preserved (n=15) with ageing. However, a smaller number of studies (n=7) noted that CA is impaired or altered with ageing.

Conclusions

There is a paucity of literature examining the relationship between CA and chronological ageing, with 60 per cent of studies reviewed suggesting that CA is preserved. Current hypotheses suggest that preservation of CA with ageing serves as a ‘reserve’ to compensate for impairment of other systems. Future work should investigate the role of impaired CA as potential biomarker of biological ageing.

P5678Near-infrared spectroscopy (NIRS) in the evaluation of psychogenic pseudosyncope - Moving towards a simplified diagnostic pathway

Background

Psychogenic pseudosyncope (PPS) is a conversion disorder that often mimics syncope, is commonly referred to cardiology clinics and accounts for a large proportion of patients admitted with “unexplained syncope”. Unlike syncope, PPS is characterized by normal blood pressure (BP) and heart rate (HR) values at TLOC inferring the absence of cerebral hypoperfusion. The current gold standard for the diagnosis of PPS is the reproduction of patients' symptoms during a head-up tilt test (HUTT) with concurrent electroencephalogram (EEG) monitoring showing normal haemodynamic and brainwave measurements. However, EEG is time consuming, resource intensive and many syncope units lack ready access, thereby solely relying on absence of peripheral haemodynamic changes to diagnose PPS.

Purpose

Near-infrared spectroscopy (NIRS) is a non-invasive technology used for continuous monitoring of cerebral oxygenation. Measuring adequacy of tissue oxygenation is an appropriate surrogate for cerebral perfusion. In this study, we present a case series of patients for whom the diagnosis of PPS was confirmed by NIRS during TLOC. We propose use of NIRS in routine clinical assessment of suspected PPS.

Methods

We describe nine consecutive patients with suspected PPS referred to a dedicated syncope unit for investigation of recurrent unexplained syncope. All patients underwent evaluation in accordance with European Society of Cardiology guidelines including HUTT. Continuous beat-to-beat BP and HR measurements were recorded using finger plethysmography. In addition, continuous NIRS-derived tissue saturation index (TSI) - a measure of percentage oxygenation - was recorded using an optical sensor applied to the left lateral forehead to assess cerebral perfusion. Absolute values of BP, HR and TSI at baseline, time of first symptom onset, presyncope and apparent TLOC were recorded. The evaluation was diagnostic for PPS when apparent TLOC occurred in the absence of typical haemodynamic or cerebral perfusion changes.

Results

The median age was 35 years (range 14–54). Clinical features were consistent with those previously described in PPS literature - female preponderance, comorbid psychiatric diagnosis, frequent attack history, with prolonged TLOC and eyes closed during events. During HUTT, all patients experienced an apparent TLOC which they recognised as reproductive of typical events. BP and HR measurements increased significantly at time of TLOC. There was no significant change in TSI at any of the time points throughout HUTT. (Figure 1 shows averaged absolute values of systolic and diastolic BP, HR and TSI with median values represented by thickened lines.)

Figure 1. Measurements during HUTT

Conclusion

NIRS is readily available, easily accessible and provides an appropriate surrogate measure of cerebral perfusion during HUTT. We propose that HUTT incorporating concurrent NIRS monitoring will enhance diagnostic yield and patient management providing important biofeedback.

A practical guide to active stand testing and analysis using continuous beat-to-beat non-invasive blood pressure monitoring

PURPOSE

The average adult stands approximately 50-60 times per day. Cardiovascular responses evoked during the first 3 min of active standing provide a simple means to clinically assess short-term neural and cardiovascular function across the lifespan. Clinically, this response is used to identify the haemodynamic correlates of patient symptoms and attributable causes of (pre-)syncope, and to detect autonomic dysfunction, variants of orthostatic hypotension, postural orthostatic tachycardia syndrome and orthostatic hypertension.

METHODS

This paper provides a set of experience/expertise-based recommendations detailing current state-of-the-art measurement and analysis approaches for the active stand test, focusing on beat-to-beat BP technologies. This information is targeted at those interested in performing and interpreting the active stand test to current international standards.

RESULTS

This paper presents a practical step-by-step guide on (1) how to perform active stand measurements using beat-to-beat continuous blood pressure measurement technologies, (2) how to conduct an analysis of the active stand response and (3) how to identify the spectrum of abnormal blood pressure and heart rate responses which are of clinical interest.

CONCLUSION

Impairments in neurocardiovascular control are an attributable cause of falls and syncope across the lifespan. The simple active stand test provides the clinician with a powerful tool for assessing individuals at risk of such common disorders. However, its simplicity belies the complexity of its interpretation. Care must therefore be taken in administering and interpreting the test in order to maximise its clinical benefit and minimise its misinterpretation.

Quantitative Ultrasound of the Mandible as a Novel Screening Approach for Osteoporosis

This study used an axial transmission quantitative ultrasound (QUS) device to assess mandibular bone strength. The aim of the study was first to establish the precision and repeatability of the axial transmission QUS measurement for a range of mandibular anatomic sites, and second to investigate the ability of the modality to differentiate between osteoporotic subjects and a control group. Three groups of adult Caucasian women were recruited: (1) healthy premenopausal women (n = 26), (2) healthy postmenopausal women (n = 48), and (3) women with osteoporosis (n = 53). Subjects were excluded from groups 1 and 2 if they had any pre-existing bone conditions. Speed of sound (SOS) measurements were taken from the mandible using an OmniSense multisite QUS device. Group 3 had dual-energy X-ray absorptiometry scans of the lumbar spine and femur. The most suitable site on the mandible was determined by repeat SOS measurements in 10 healthy premenopausal subjects, at 5 different sites. The parasymphysis site had the lowest root mean squared coefficient of variation at 0.74%, and was chosen as the most suitable site for mandibular SOS measurements. Group 1 and group 2 had significantly higher mean SOS measurements than the osteoporotic subjects (group 3), with means of 3683 m/s (210), 3514 m/s (221), and 3312 m/s (264), respectively. A 1-way analysis of variance confirmed a statistically significant difference between mean SOS measurements from the 3 groups (p < 0.0001). Axial transmission QUS of the mandible can differentiate between subjects with osteoporosis and a healthy control group, and shows potential for use as a screening tool for osteoporosis.

Time to Refocus Assessment of Vision in Older Adults? Contrast Sensitivity but Not Visual Acuity Is Associated With Gait in Older Adults

Background

The relationship between measures of visual function and gait related risk factors for falls is unclear. In this study, we examine the relationship between visual function (visual acuity [VA] and contrast sensitivity [CS] at multiple spatial frequencies) and quantitative spatiotemporal gait, using a large, nationally representative sample of community dwelling older adults.

Methods

Participants aged 50 and over were recruited as part of The Irish Longitudinal Study on Ageing (TILDA). VA was measured with the LogMAR chart according to the Early Treatment of Diabetic Retinopathy Study protocol. CS was measured at five spatial frequencies ranging 1.5 to 18 cycles per degree (cpd) using the Functional Acuity Contrast Test. Gait speed, cadence, and stride length were measured using the GAITRite system. Multivariate analysis examined associations between gait and visual performance parameters adjusting for socioeconomic, physical, cognitive, and mental health covariates.

Results

Data from 4,678 participants were analyzed (age 61.7 ± 8.3 years, 54.1% woman). Poorer CS at 1.5 cpd and 3.0 cpd (low spatial frequency) was independently associated with decreased stride length (CS at 1.5 cpd: β = .031; p = .001 and CS at 3.0 cpd: β = .020; p = .001) but not cadence or gait speed. There was no evidence of an association between VA and any of the gait variables considered (p > .05).

Conclusion

Reduced CS, at low spatial frequencies, is independently associated with shorter stride length, while VA is not associated with any gait measures. This evidence suggests that it may be necessary to consider refocus of the assessment of vision to include the most appropriate measures.

Noninvasive beat-to-beat finger arterial pressure monitoring during orthostasis: a comprehensive review of normal and abnormal responses at different ages

Over the past 30 years, noninvasive beat-to-beat blood pressure (BP) monitoring has provided great insight into cardiovascular autonomic regulation during standing. Although traditional sphygmomanometric measurement of BP may be sufficient for detection of sustained orthostatic hypotension, it fails to capture the complexity of the underlying dynamic BP and heart rate responses. With the emerging use of noninvasive beat-to-beat BP monitoring for the assessment of orthostatic BP control in clinical and population studies, various definitions for abnormal orthostatic BP patterns have been used. Here, age-related changes in cardiovascular control in healthy subjects will be reviewed to define the spectrum of the most important abnormal orthostatic BP patterns within the first 180 s of standing. Abnormal orthostatic BP responses can be defined as initial orthostatic hypotension (a transient systolic BP fall of >40 mmHg within 15 s of standing), delayed BP recovery (an inability of systolic BP to recover to a value of >20 mmHg below baseline at 30 s after standing) and sustained orthostatic hypotension (a sustained decline in systolic BP of ≥20 mmHg occurring 60-180 s after standing). In the evaluation of patients with light-headedness, pre(syncope), (unexplained) falls or suspected autonomic dysfunction, it is essential to distinguish between normal cardiovascular autonomic regulation and these abnormal orthostatic BP responses. The prevalence, clinical relevance and underlying pathophysiological mechanisms of these patterns differ significantly across the lifespan. Initial orthostatic hypotension is important for identifying causes of syncope in younger adults, whereas delayed BP recovery and sustained orthostatic hypotension are essential for evaluating the risk of falls in older adults.

Impaired Orthostatic Blood Pressure Recovery Is Associated with Unexplained and Injurious Falls

OBJECTIVES

Cardiovascular disorders are recognized as important modifiable risk factors for falls. However, the association between falls and orthostatic hypotension (OH) remains ambivalent, particularly because of poor measurement methods of previous studies. The goal was to determine for the first time to what extent OH (and variants) are risk factors for incident falls, unexplained falls (UF), injurious falls (IF) and syncope using dynamic blood pressure (BP) measurements in a population study.

DESIGN

Nationally representative longitudinal cohort study-The Irish Longitudinal Study on Ageing (TILDA)-wave 1 (2009-2011) with 2-year follow-up at wave 2 (2012-2013).

SETTING

Community-dwelling adults.

PARTICIPANTS

Four thousand one hundred twenty-seven participants were randomly sampled from the population of older adults aged ≥50 years resident in Ireland.

MEASUREMENTS

Continuous BP recordings measured during active stands were analyzed. OH and variants (initial OH and impaired orthostatic BP stabilization OH(40)) were defined using dynamic BP measurements. Associations with the number of falls, UF, IF, and syncope reported 2 years later were assessed using negative binomial and modified Poisson regression as appropriate.

RESULTS

Participants had a mean age of 61.5 (8.2) years (54.2% female). OH(40) was associated with increased relative risk of UF (RR: 1.52 95% CI: 1.03-2.26). OH was associated with all-cause falls (IRR: 1.40 95% CI: 1.01-1.96), UF(RR: 1.81 95% CI: 1.06-3.09), and IF(RR: 1.58 95% CI: 1.12-2.24). IOH was not associated with any outcome.

CONCLUSION

With the exception of initial orthostatic hypotension, beat-to-beat measures of impaired orthostatic BP recovery (delayed recovery OH (40) or sustained orthostatic hypotension OH) are independent risk factors for future falls, unexplained falls, and injurious falls.

Antidepressants strongly influence the relationship between depression and heart rate variability: findings from The Irish Longitudinal Study on Ageing (TILDA)

BACKGROUND

Heart rate variability (HRV) is known to be reduced in depression; however, is unclear whether this is a consequence of the disorder or due to antidepressant medication.

METHODS

We analysed data on 4750 participants from the first wave of The Irish Longitudinal Study on Ageing (TILDA). Time [standard deviation of normal to normal intervals (SDNN ms2)] and frequency domain [low frequency (LF) and high frequency (HF)] measures of HRV were derived from 3-lead surface electrocardiogram records obtained during 10 min of supine rest. Depression was assessed using the Center for Epidemiologic Studies - Depression scale.

RESULTS

Participants on antidepressants [with (n = 80) or without depression (n = 185)] differed significantly from controls (not depressed and not taking antidepressants n = 4107) on all measures of HRV. Depressed participants not taking antidepressants (n = 317) did not differ from controls on any measures of HRV. In linear regression analysis adjusted for relevant factors all antidepressants were associated with lower measures HRV. Participants on selective serotonin reuptake inhibitors (SSRIs) had higher measures of HRV relative to participants on tricyclic antidepressants or serotonin-norepinephrine reuptake inhibitors respectively.

CONCLUSIONS

Our results suggest that reductions in HRV observed among depressed older adults are driven by the effects of antidepressant medications. SSRIs have less impact on HRV than other antidepressants but they are still associated with lower measures of HRV. Study limitations include the use of a self-report measure of depression and floor effects of age on HRV could have limited our ability to detect an association between HRV and depression.

Stressful life events and orthostatic blood pressure recovery in older adults

OBJECTIVE

The majority of the literature on stress and blood pressure (BP) concerns the increased risk of cardiovascular morbidity and mortality from high BP. Because the sympathetic nervous system is critical to the maintenance of orthostatic BP, it was hypothesized that older adults who have experienced more stressful life events (SLEs) would be more likely to show impaired recovery of BP in response to orthostatic stress.

METHOD

A total of 3,765 participants (Mage = 61.6 years, SD = 8.2; 54% female) from the first wave of The Irish Longitudinal Study on Ageing (TILDA) were included in the current analysis. Exposure to lifetime SLEs was ascertained by self-completion questionnaire, and beat-to-beat orthostatic BP measurement was carried out. Individuals who failed to recover at least 95% of their baseline BP by 60 s post stand were characterized as having impaired orthostatic BP recovery.

RESULTS

An independent, dose-response relationship between the number of SLEs reported and the odds of impaired systolic BP recovery was observed after adjustment for covariates (1 event: odds ratio [OR] = 1.19, 95% confidence interval [CI] [0.98, 1.45], p = .078; 2 events: OR = 1.33, 95% CI [1.03, 1.73], p = .031; 3 or more events: OR = 1.56, 95% CI [1.12, 1.73], p = .009). This relationship was not evident for diastolic BP recovery.

CONCLUSION

The reporting of a higher number of SLEs is associated with greater risk of impaired systolic BP recovery from orthostatic stress. Potential clinical implications include an increased risk of cerebral hypoperfusion, which predisposes older adults to falls, faints, and changes in cognitive status.

Age-Related Normative Changes in Phasic Orthostatic Blood Pressure in a Large Population Study

Background—

In this report, we provide the first normative reference data and prevalence estimates of impaired orthostatic blood pressure (BP) stabilization, initial orthostatic hypotension, and orthostatic hypotension based on beat-to-beat blood pressure methods in a population-representative sample.

Methods and Results—

Participants were recruited from a nationally representative cohort study (≥50 years). Beat-to-beat systolic BP, diastolic BP, and heart rate records were analyzed among those who underwent an active stand test (n=4475). Normograms were estimated by use of generalized additive models for location, shape, and scale with Box-Cox power exponential distribution. Prevalence estimates of impaired BP stabilization, initial orthostatic hypotension, and orthostatic hypotension are reported. Orthostatic BP responses in adults aged 50 to 59 years stabilized within 30 seconds of standing, with older groups taking 30 seconds or longer. The total prevalence of impaired BP stabilization was 15.6% (95% confidence interval [CI], 14.1%–17.1%), increasing with age to 41.2% (95% CI, 30.0%–52.4%) in people ≥80 years old. Initial orthostatic hypotension occurred in 32.9% (95% CI, 31.2%–34.6%) of the population aged ≥50 years, with no age gradient evident. The prevalence of orthostatic hypotension was 6.9% (95% CI, 5.9%–7.8%) in the total population, increasing to 18.5% (95% CI, 9.0%–28.0%) in those aged ≥80 years old.

Conclusions—

Significant age-related differences exist in the time course of postural BP responses, with abnormal responses taking longer than 30 seconds to stabilize. Impaired BP stabilization is more common as we age, affecting more than two-fifths of the population aged ≥80 years, and may play a future role in the management of falls and syncope.

Low macular pigment optical density is associated with lower cognitive performance in a large, population-based sample of older adults

Macular pigment (MP) is comprised of the carotenoids lutein (L), zeaxanthin (Z), and meso-zeaxanthin (MZ), which selectively accumulate at the macula (central retina) of the eye and are neuroprotective. These carotenoids are also present in the brain, and evidence suggests a close correlation between retinal and brain concentrations. We investigated the relationship between MP and cognitive function in 4453 adults aged ≥ 50 years as part of The Irish Longitudinal Study on Aging. Macular pigment optical density (MPOD) was determined using customized heterochromatic flicker photometry-a quick and noninvasive way of measuring the concentration of the pigment. Lower MPOD was associated with poorer performance on the mini-mental state examination (p = 0.026) and on the Montreal cognitive assessment (p = 0.016). Individuals with lower MPOD also had poorer prospective memory (p = 0.011), took longer time to complete a trail-making task (p = 0.003), and had slower and more variable reaction times on a choice reaction time task (p = 0.000 and 0.001). These associations were only slightly attenuated following adjustment for physical and mental health. There was no significant association between MPOD and verbal fluency, word recall, visual reasoning, or picture memory. Overall, the findings support the theory that xanthophyll carotenoids impact on cognitive function, underscoring the need for exploration of novel, noninvasive biomarkers for cognitive vulnerability and preventive strategies.

Factors that influence awareness and treatment of atrial fibrillation in older adults

AIM

The aims of this study were to investigate the prevalence of atrial fibrillation (AF), treatment rates of AF and the factors underlying awareness and treatment, in a large nationally representative study.

METHODS

A population sample of people aged 50+, living in the Republic of Ireland, were recruited as part of The Irish longitudinal study on ageing. Ten-minute electrocardiogram recordings were obtained (n = 4890), and analysed to detect AF. Self-reported arrhythmias, subjective and objective health measures (cardiovascular diseases, CHA2DS2-VASc variables and blood pressure) and medications were also recorded. Logistic regressions were used to determine associations with outcomes of presence of AF, lack of awareness and untreated AF.

RESULTS

Overall prevalence of AF was 3% (95% CI: 2.4-3.7%), with a marked age gradient and sex difference [4.8% (men) vs. 1.4% (women); P < 0.0001]. In total, 67.8% were at high risk of stroke (CHA2DS2-VASc ≥ 2), of whom 59.3% were inadequately treated. A high proportion of 38.1% were unaware of having AF. CHA2DS2-VASc nor HAS-BLED score influenced awareness or treatment. Lack of awareness was associated with lower education (P = 0.01), lower cognition (P = 0.04), rural location (OR = 3.67; P = 0.02) and number of general practitioner visits (P = 0.01), whereas untreated AF was influenced by frailty status (P = 0.04).

CONCLUSION

With projected doubling of numbers of persons over 80 in the next 30 years in the British Isles, detection and management of AF is pressing. Two-thirds of adults at high risk of stroke were inadequately treated. More regular screening for AF, application of criteria for stroke and bleeding risk and awareness of factors influencing diagnosis and treatment is recommended.