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.

Reliability of orthostatic beat-to-beat blood pressure tests: implications for population and clinical studies.

OBJECTIVE: To assess the test-retest reliability of orthostatic beat-to-beat blood pressure responses to active standing and related clinical definitions of orthostatic hypotension. METHODS: A random sample of community-dwelling older adults from the pan-European Survey of Health, Ageing and Retirement in Europe, Ireland underwent a health assessment that mimicked that of the Irish Longitudinal Study on Ageing. An active stand test was performed using continuous blood pressure measurements. Participants attended a repeat assessment 4-12 weeks after the initial measurement. A mixed-effects regression model estimated the reliability and minimum detectable change while controlling for fixed observer and time of day effects. RESULTS: A total of 125 individuals underwent repeat assessment (mean age 66.2 ± 7.5 years; 55.6% female). Mean time between visits was 84.3 ± 23.3 days. There was no significant mean difference in heart rate or blood pressure recovery variables between the first and repeat assessments. Minimum detectable change was noted for changes from resting values in systolic blood pressure (26.4 mmHg) and diastolic blood pressure (13.7 mmHg) at 110 s and for changes in heart rate (10.9 bpm) from resting values at 30 s after standing. Intra-class correlation values ranged from 0.47 for nadir values to 0.80 for heart rate and systolic blood pressure values measured 110 s after standing. CONCLUSION: Continuous orthostatic beat-to-beat blood pressure and related clinical definitions show low to moderate reliability and substantial natural variation over a 4-12-week period. Understanding variation in measures is essential for study design or estimating the effects of orthostatic hypotension, while clinically it can be used when evaluating longer term treatment effects.

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.

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.

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.

Bifunctional bisphosphonate complexes for the diagnosis and therapy of bone metastases.

Easily synthesised and structurally well-defined novel imaging/therapeutic radiopharmaceutical agents for bone metastases are described.

A comparison of covert and overt attention as a control option in a steady-state visual evoked potential-based brain computer interface.

EEG data were recorded from occipital scalp regions of subjects who attended to an alternating checkerboard stimulus in one visual field while ignoring a similar stimulus of a different frequency in the opposite visual field. Classification of left/right spatial attention is attempted by extracting steady-state visual evoked potentials (SSVEPs) elicited by the stimuli to assess the potential use of such a spatial selective attention paradigm in a brain computer interface (BCI). Experimental setup and analysis procedure in a previous study in which eye movement is permitted are replicated in order to quantify differences in classification performance using overt and covert attention. Four variations of the basic paradigm, involving both feedback and addition of extra mental load, are studied for comparison. The average accuracy is found to be reduced by approximately 20% in the switch from overt to covert attention when no other specifications of the task are changed.