Pulse Wave Amplitude Research Articles

17. Aberrant corpus luteum number as a contributor to altered maternal vascular health in early pregnancy and preeclampsia risk after assisted reproduction

Introduction Pregnancies conceived after utilization of assisted reproductive technologies (ART) are associated with an increased risk for preeclampsia. The pathophysiologic reasons are mainly unknown. Objective We sought to determine if a non-physiologic hormonal milieu influenced by the number of corpora lutea (CL) and the mode of conception affects maternal vascular health in early pregnancy. Methods Blood pressure, endothelial function, circulating endothelial progenitor cell numbers (CPCs), lipid levels, and CL hormones were compared in a prospective cohort of women at 11 to 14 weeks’ gestation by number of CL and mode of conception (N = 57): 0 CL (programmed frozen embryo transfer (FET), N = 18); 1 CL (spontaneous pregnancy after infertility [N = 16] and modified natural cycle FET [N = 12]); or >3 CL associated with in vitro fertilization [N = 11]. Results Women with 0 or >3 CL lacked the drop in mean arterial blood pressure compared to women with 1 CL (P = 0.05; P = 0.05). Reactive Hyperemia Index (RHI) was impaired in patients lacking a CL compared to women with 1 CL (P = 0.04). Baseline pulse wave amplitude (BPWA) was higher in subjects with >3 CL compared to 1 CL (P = 0.01) or zero (P = 0.01). Suppression of CL development in FET cycles was associated with a lower RHI compared with FETs in a natural cycle (P = 0.03). The number of angiogenic and non-angiogenic CPCs was lower in the absence of a CL in FETs (P = 0.02 and P = 0.04). Relaxin levels correlated with the number of angiogenic CPCs (r = 0.31; P = 0.03). Discussion Maternal vascular health in early pregnancy is altered in women with aberrant numbers of CL (0 or >3), and might represent insufficient cardiovascular adaption leading to an increased risk of preeclampsia.

The strategy of improving anesthesia in septoplasty by the use of new adjuvants

The aim of the study was to find methods for optimizing perioperative analgesia, stabilizing hemodynamics, improving control of inMaterials and methods: The study included 53 patients, divided into 2 groups: primary (n=28) and control (n=25). In the main group, infusion of dexmedetomidine and intravenous form of paracetamol was carried out. The hemodynamic parameters, the general blood test, the coagulogram, the volume of blood loss, the duration of anesthesia and surgical intervention, the dose of anesthetics and analgesics, the pain level according to the VAS were investigated.Results: In the "P + D" group mean arterial pressure, heart rate and systolic index during induction of anesthesia, intubation, surgical intervention and after awakening of patients are significantly lower than in the control (p<0,001). The level of ANI at all stages of observation is significantly higher in the group "P + D" (p<0,001). The level of hemoglobin, hematocrit and erythrocytes in the postoperative period is lower in the "K" group than in the "P + D" group (p<0,001). In the "P + D" group, the blood loss is significantly less than in the control group (p<0,001). In the "P + D" group, the duration of surgery and anesthesia, the dose of anesthetics and narcotic analgesics is significantly lower than in the control (p<0,001). In the "P + D" group, Duke bleeding time and Lee-White coagulation time (p<0,001) is significantly shorter. Responses of patients are higher in the "P + D" group. The quality of visualization of the operating field is better in the group "P + D" (p<0,001).In the future, it is planned to conduct BIS studies to identify correlation with ANI and other indicators and compare ANI scores with such methods of objectifying the intraoperative level of pain as assessment of skin conductivity, determination of pupillary response, measurement of pulse wave amplitude and the like.However, this study is limited in renal, hepatic insufficiency and unstable hemodynamics. ANI is not interpreted in the following situations: atrial fibrillation, absence of breathing, respiratory rate less than 9 per 1 minute, presence of a pacemaker, use of atropine, adrenaline.The intravenous form of paracetamol and dexmedetomidine can be recommended for use in practical activities in nasal surgery to optimize anesthetic maintenance.Conclusion: Combination of dexmedetomidine and paracetamol with septoplasty allows to provide a reliable analgesia in the perioperative period. The introduction of dexmedetomidine and paracetamol correlates with the stabilization of hemodynamics in the perioperative period. Infusion of dexmedetomidine and paracetamol helps to reduce intraoperative blood loss and improve the visualization of the operating field

Reliability of autonomic activations as surrogates of cortical arousals in ventilated patients affected by amyotrophic lateral sclerosis.

The study aims to evaluate the performance of autonomic activations as a tool to assess sleep fragmentation and to recognize hypopneas in patients with amyotrophic lateral sclerosis (ALS) under non-invasive mechanical ventilation and secondarily, to evaluate, in patients with the same disease, the relationship between disruption of autonomic nervous system (ANS) activity and the usefulness of the autonomic activations as surrogates of cortical arousals. Sixteen ALS patients underwent simultaneous polysomnography and portable cardiorespiratory monitoring (PM). On the polysomnography, standard rules were used for scoring arousals and respiratory events. On the PM, autonomic arousals were scored as ≥15% heart rate (HR) increase with a ≥35% pulse wave amplitude (PWA) reduction, HR increase ≥20%, or PWA decrease ≥40%. Nocturnal HR variability was analyzed in the ALS patients and in 11 control subjects as an index of ANS activity. Synchronized epoch by epoch analysis of the polysomnography and PM recordings showed that only 31.0 (22.5-58.7)% cortical and 36.1 (20.5-47.2)% autonomic arousals were associated with one another. Among hypopneas scored at polysomnography, 71.7% were associated with a cortical arousal but not with a desaturation. On average, HR variability in ALS showed signs of depressed ANS activity that was particularly evident in the patients where the cortical arousals exceeded the autonomic ones. In ventilated ALS patients, autonomic activations may hardly have a role as surrogates of cortical arousals for assessment of sleep fragmentation and for respiratory scoring. Depression of ANS activity may be related to their poor performance.

Objective detection of chronic stress using physiological parameters.

The aim of this study was to design a system to diagnose chronic stress, based on blunted reactivity of the autonomic nervous system (ANS) to cognitive load (CL). The system concurrently measures CL-induced variations in pupil diameter (PD), heart rate (HR), pulse wave amplitude (PWA), galvanic skin response (GSR), and breathing rate (BR). Measurements were recorded from 58 volunteers whose stress level was identified using the State-Trait Anxiety Inventory. Number-multiplication questions were used as CLs. HR, PWA, GSR, and PD were significantly (p < 0.05) changed during CL. CL-induced changes in PWA (16.87 ± 21.39), GSR (- 13.71 ± 7.86), and PD (11.56 ± 9.85) for non-stressed subjects (n = 36) were significantly different (p < 0.05) from those in PWA (2.92 ± 12.89), GSR (- 6.87 ± 9.54), and PD (4.51 ± 10.94) for stressed subjects (n = 22). ROC analysis for PWA, GSR, and PD illustrated their usefulness to identify stressed subjects. By inputting all features to different classification algorithms, up to 91.7% of sensitivity and 89.7% of accuracy to identify stressed subjects were achieved using 10-fold cross-validation. This study was the first to document blunted CL-induced changes in PWA, GSR, and PD in stressed subjects, compared to those in non-stressed subjects. Preliminary results demonstrated the ability of our system to objectively detect chronic stress with good accuracy, suggesting the potential for monitoring stress to prevent dangerous stress-related diseases. Graphical abstract Chronic stress degrads the autonomic nervous system reaction to cognitive loads. Measurement of reduced changes in physiological signals during asking math questions was useful to identify people with high STAI score (stressed subjects).

Pulse wave amplitude and heart period variability in children with upper airway obstruction

ObjectiveThe aim of this study was to assess cardiovascular autonomic modulation in children with upper airway obstruction (UAO), to compare this modulation to that of non-snoring children and to investigate the effect of adenotonsillectomy (AT). MethodsECG and finger photoplethysmographic signals obtained from overnight polysomnographic (PSG) recordings of 31 children with mild-to-moderate UAO and 34 non-snoring children were analysed. The extent of autonomic modulation was assessed by symbolic analysis of heart period (HP), pulse wave amplitude (PWA), and their joint dynamics during non–rapid eye movement (NREM) sleep and rapid eye movement (REM) sleep. ResultsChildren with UAO showed more frequent patterns of monotonically increasing and decreasing HP in NREM sleep and monotonically increasing and decreasing joint PWA-HP patterns in REM and NREM sleep at baseline compared to controls, even when considering only periods of sleep free of discrete respiratory events. Following AT, HP, and joint PWA-HP dynamics significantly altered towards levels observed in the control group. ConclusionsIn children with mild-to-moderate UAO, cardiovascular autonomic modulation is more prevalent, even during quiet, event-free sleep. AT appears to reverse this pattern.

0889 Sleep Determinants of Incident Hypertension in a Population-Based Cohort: The CoLaus-HypnoLaus Study

An association between sleep-disordered breathing and cardiovascular risk factors such as hypertension has been suggested. Potential mechanisms underlying this association include sleep fragmentation, intermittent hypoxia and autonomic activations. The aim of this study was to analyze the sleep determinants of incident hypertension in a population-based cohort. CoLaus is a prospective population-based cohort in which cardiovascular profile was assessed at baseline and 2 subsequent follow-ups. Hypertension was defined as systolic blood pressure (SBP) ≥140 mm Hg, diastolic blood pressure (DBP) ≥90 mm Hg, or antihypertensive drug use. HypnoLaus study analyzed sleep characteristics in a subset of CoLaus population at the first follow-up (6.4 ± 0.2 years after baseline). All HypnoLaus participants underwent a full polysomnography (PSG) at home. The apnea/hypopnea index (AHI) was determined according to the recommended AASM-2012 criteria. The autonomic activation during sleep was assessed using pulse wave amplitude (PWA) drops based on the photoplethysomnographic signal of PSG. Of the 1304 participants (mean age 49.1 ± 9.6 y.o., 56% women) without hypertension at baseline, 338 (25.5%, mean age 51.6 ± 16.8 y.o., 51% women) developed hypertension at the second follow-up (10.8 ± 0.1 years interval). After adjustment for age, sex, BMI, delta BMI (between baseline and PSG), baseline SBP and DBP, the following sleep parameters were independently associated with incident hypertension: PWA drops duration (OR for 1 second: 1.10 [1.04–1.16], p=0.001), AHI in REM sleep (OR for 1 event/h: 1.02 [1.01–1.03], p=0.001), and %time spent with an oxygen saturation <90% (OR for 1%: 1.01 [1.00–1.03], p=0.042). In a stepwise multivariate logistic regression including all significant parameters in bivariate analysis, PWA drop duration (p=0.0001) and REM-AHI (p=0.003) were the only sleep parameters that remained associated with incident hypertension. Nocturnal autonomic activation and AHI during REM sleep seem to contribute to incident hypertension in the middle-to-older-age CoLaus-HypnoLaus cohort. Faculty of Biology and Medicine of Lausanne, the Swiss National Science Foundation (grants 3200B0-105993, 3200B0-118308, 33CSCO-122661, 33CS30-139468 and 33CS30-148401), Leenaards Foundation, and Vaud Pulmonary League (Ligue Pulmonaire Vaudoise).

Reactive hyperemia-peripheral arterial tonometry is useful for assessment of not only endothelial function but also stenosis of the digital artery

BackgroundAlthough reactive hyperemia-peripheral arterial tonometry (RH-PAT) is widely used for assessment of endothelial function, RH index (RHI) cannot be measured in some cases when pulse wave amplitude (PWA) is very low. Decrease in PWA is mainly caused by proper palmar digital artery (PPDA) stenosis. The purpose of this study was to evaluate the relationship between PWA measured by RH-PAT and stenosis of the PPDA measured by digital subtraction angiography and to evaluate the limitation of assessment of endothelial function measured by RHI in patients with PPDA stenosis. MethodsWe measured baseline PWA in 51 fingers including the first to third fingers of both hands in 10 patients who had PPDA stenosis and in 66 fingers that were the first fingers of both hands in 33 subjects who had no PPDA stenosis. Severe stenosis was defined as over 75% by lower percent diameter stenosis between two PPDAs in a finger. ResultsPWA was significantly correlated with stenosis of the digital artery (r=−0.55; P<0.0001). A PWV value of 300mV was the optimal cut-off value for severe stenosis (sensitivity, 84.0%; specificity, 88.5%). Log RHI was significantly lower in patients with PPDA stenosis than in subjects without PPDA stenosis (0.33±0.27 versus 0.73±0.27, P=0.007). ConclusionsRH-PAT may be useful for assessment of not only endothelial function but also PPDA stenosis. RHI may be underestimated in patients with PPDA stenosis. We should pay attention to low baseline PWA when measuring RHI. Clinical trial registration informationURL for clinical trial: http://UMIN; registration number for clinical trial: UMIN000003409.

Abstract P294: Greater Peripheral Vasoconstriction During Mental Stress Predicts Adverse Cardiovascular Outcomes

Introduction: Peripheral arterial vasoconstriction during mental stress (MS) has been associated with mental stress-induced myocardial ischemia, which in turn has been linked with worse cardiovascular outcomes. It is unknown whether the magnitude of peripheral vasoconstriction with MS is predictive of long term outcomes. Hypothesis: We hypothesized that greater peripheral arterial vasoconstriction during MS would be associated with adverse events among patients with coronary artery disease (CAD). Methods: Four hundred sixty-three patients with stable CAD and normal left ventricular function, (age 63±9, 75% male, 27% Black, EF 60±8 %) underwent MS testing with a standardized public speaking stressor. Digital pulse wave amplitude was continuously measured at baseline and during MS using peripheral arterial tonometry (PAT), and the PAT ratio of pulse wave amplitude (during mental stress/ baseline) was calculated. Cox proportional hazard models were calculated to examine the association between the PAT ratio and outcomes. Results: Median PAT ratio during MS was 0.68, indicating 32% average constriction with MS compared to rest. Subjects with greater peripheral constriction [low (&lt;median) PAT ratio] were more likely to be male (80% vs. 70%, P=0.008) compared to those with PAT ratio ≥median, but their risk factor profiles were similar. During 2.8±0.5 year follow-up, 64 patients had adverse cardiac events including 7 cardiovascular deaths, 19 MI, and 54 revascularization events. After adjusting for age, sex, race, hypertension, diabetes, current smoking status, and prior MI, those with low PAT ratio had a greater risk of CV death/MI (HR[hazard ratio] 2.49, 95% CI [1.04-5.99]) and CV death/MI/revascularization (HR 1.77, 95% CI [1.03-3.04]) compared to those with high PAT ratio. Conclusion: Greater peripheral arterial vasoconstriction with MS is associated with a higher risk of adverse cardiovascular outcomes in patients with CAD.

Morning cortisol and fasting glucose are elevated in women with chronic widespread pain independent of comorbid restless legs syndrome.

Chronic widespread pain (CWP) is associated with poor quality of sleep, but the detailed underlying mechanisms are still not fully understood. In this study we investigated the influence of CWP on morning cortisol and fasting glucose concentrations as well as sleep disordered breathing. In this case-control study, subjects with CWP (n=31) and a control group without CWP (n=23) were randomly selected from a population-based cohort of women. Current pain intensity, sleep quality, excessive daytime sleepiness [Epworth sleepiness scale (ESS)], psychiatric comorbidity and occurrence of restless legs syndrome (RLS) were assessed. Overnight polygraphy was applied to quantify sleep apnoea, airflow limitation and attenuations of finger pulse wave amplitude (>50%) as a surrogate marker for increased skin sympathetic activity. Morning cortisol and fasting glucose concentrations were determined. Generalised linear models were used for multivariate analyses. CWP was associated with higher cortisol (464±141 vs. 366±111 nmol/L, p=0.011) and fasting glucose (6.0±0.8 vs. 5.4±0.7 mmol/L, p=0.007) compared with controls. The significance remained after adjustment for age, body mass index, RLS and anxiety status (β=122±47 nmol/L and 0.89±0.28 mmol/L, p=0.009 and 0.001, respectively). The duration of flow limitation in sleep was longer (35±22 vs. 21±34 min, p=0.022), and pulse wave attenuation was more frequent (11±8 vs. 6±2 events/h, p=0.048) in CWP subjects compared with controls. RLS was associated with higher ESS independent of CWP (β=3.1±1.3, p=0.018). Elevated morning cortisol, impaired fasting glucose concentration and increased skin sympathetic activity during sleep suggested an activated adrenal medullary system in subjects with CWP, which was not influenced by comorbid RLS. CWP is associated with activated stress markers that may deteriorate sleep.

Quantifying peripheral sympathetic activation during sleep by means of an automatic method for pulse wave amplitude drop detection

Quantifying peripheral sympathetic activation during sleep by means of an automatic method for pulse wave amplitude drop detection

Arousal responses to respiratory events during sleep: the role of pulse wave amplitude.

The study aims at assessing the changes in electroencephalography (as measured by the A-phases of cyclic alternating pattern) and autonomic activity (based on pulse wave amplitude) at the recovery of airway patency in patients with obstructive sleep apnea syndrome. Analysis of polysomnographic recordings from 20 male individuals with obstructive sleep apnea syndrome was carried out in total sleep time, non-rapid eye movement and rapid eye movement sleep. Scoring quantified the combined occurrence (time range of 4s before and 4s after respiratory recovery) or separate occurrence of A-phases (cortical activation), and pulse wave amplitude drops (below 30%) to apneas, hypopneas or flow limitation events. A dual response (A-phase associated with a pulse wave amplitude drop) was the most frequent response (71.8% in total sleep time) for all types of respiratory events, with a progressive reduction from apneas to hypopneas and flow limitation events. The highly significant correlation in total sleep time (r=0.9351; P<0.0001) between respiratory events combined with A-phases and respiratory events combined with pulse wave amplitude drops was confirmed both in non-rapid eye movement (r=0.9622; P<0.0001) and rapid eye movement sleep (r=0.7162; P<0.0006). In conclusion, a dual cortical and autonomic activation is the most common manifestation at the recovery of airway patency. The significant correlation between A-phases and relevant pulse wave amplitude drops suggests a possible role of pulse wave amplitude as a marker of cerebral response to respiratory events.

Multipoint Tissue Circulation Monitoring with a Flexible Optical Probe

Compromised circulation is a potential complication during the postoperative period following tissue transplantation. The use of a monitoring device allows physicians to detect compromised circulation immediately. Such monitoring devices need to be continuously usable, wearable, and area-detectable. However, existing devices fail to satisfy all of these requirements simultaneously. We developed a wearable, multipoint pulse wave-monitoring device. An array of reflective optical sensors implemented on a thin film substrate was used as a lightweight and flexible probe. As a model of tissue transplantation, an inguinal flap in a Wistar rat was dissected and freed from all subcutaneous tissue. By ligating the artery or vein, ischemia or congestion was induced in the tissue. In a human study, ischemia or congestion was induced in the palm by pressing the feeding artery or cutaneous vein, respectively. The amplitude of the pulse wave was evaluated using the power spectrum of Fourier transformed signals. Pulse wave amplitude significantly decreased under compromised circulation in both animal and human models. Moreover, we accomplished 1 week of continuous wireless monitoring in healthy subjects. These results demonstrated the potential utility of the developed device in postoperative blood-flow monitoring to improve the rescue rate of transplanted tissue.

Vascular parkinsonism or idiopathic NPH? New insights from CSF pressure analysis.

Differential diagnosis between vascular parkinsonism (VP) and idiopathic normal pressure hydrocephalus (iNPH) is particularly challenging due to similar clinical and neuroradiological features. The objective of this study is to differentiate VP with radiological evidence of ventricular enlargement (REVE) from iNPH on the basis of cerebrospinal fluid (CSF) hydrodynamics. CSF pressure components were investigated in patients with a clinical diagnosis of VP and REVE. Data of eight patients (seven men; age 76±3.9years; disease duration 26.5±15.6months) were evaluated. CSF opening pressure values were normal in all patients. Also, mean CSF pressure values during short-term monitoring were normal, except in one patient. Four out of the eight patients had raised values of pulse wave amplitude (PWA) during the opening phase (mean±SD 57.1±19.9mmH2O), meanwhile during short-term monitoring, seven out of the eight patients showed raised values of mean PWA (76.8±23mmH2O). We found that most of patients with clinical characteristics of VP and REVE showed elevated PWA during the short-term monitoring of CSF pressure as observed in iNPH patients. Patients clinically identified as VP may be part of the clinical spectrum of iNPH.

Suicidal Ideation Is Associated with Altered Variability of Fingertip Photo-Plethysmogram Signal in Depressed Patients.

Physiological and psychological underpinnings of suicidal behavior remain ill-defined and lessen timely diagnostic identification of this subgroup of patients. Arterial stiffness is associated with autonomic dysregulation and may be linked to major depressive disorder (MDD). The aim of this study was to investigate the association between arterial stiffness by photo-plethysmogram (PPG) in MDD with and without suicidal ideation (SI) by applying multiscale tone entropy (T-E) variability analysis. Sixty-one 10-min PPG recordings were analyzed from 29 control, 16 MDD patients with (MDDSI+) and 16 patients without SI (MDDSI−). MDD was based on a psychiatric evaluation and the Mini-International Neuropsychiatric Interview (MINI). Severity of depression was assessed using the Hamilton Depression Rating Scale (HAM-D). PPG features included peak (systole), trough (diastole), pulse wave amplitude (PWA), pulse transit time (PTT) and pulse wave velocity (PWV). Tone (Diastole) at all lags and Tone (PWA) at lags 8, 9, and 10 were found to be significantly different between the MDDSI+ and MDDSI− group. However, Tone (PWA) at all lags and Tone (PTT) at scales 3–10 were also significantly different between the MDDSI+ and CONT group. In contrast, Entropy (Systole), Entropy (Diastole) and Tone (Diastole) were significantly different between MDDSI− and CONT groups. The suicidal score was also positively correlated (r = 0.39 ~ 0.47; p < 0.05) with systolic and diastolic entropy values at lags 2–10. Multivariate logistic regression analysis and leave-one-out cross-validation were performed to study the effectiveness of multi-lag T–E features in predicting SI risk. The accuracy of predicting SI was 93.33% in classifying MDDSI+ and MDDSI− with diastolic T-E and lag between 2 and 10. After including anthropometric variables (Age, body mass index, and Waist Circumference), that accuracy increased to 96.67% for MDDSI+/− classification. Our findings suggest that tone-entropy based PPG variability can be used as an additional accurate diagnostic tool for patients with depression to identify SI.

Pulse wave amplitude reduction as a surrogate for cortical arousal during sleep hypopnea in children

ObjectivesThe accuracy of respiratory polygraphy (RP) is limited because of the absence of electroencephalography (EEG). Pulse wave amplitude (PWA) reduction has been shown to be a marker of autonomic activation during arousal, and may represent a substitute for obstructive respiratory-related cortical arousal (RRCA). This study tested the hypothesis that PWA could be a surrogate for RRCA in detecting obstructive hypopnea (OH) in a pediatric population. Materials and methodsTwo experienced readers scored 30 consecutive polysomnographies (PSG) using standard scoring rules. Automatic software detected every 20–90% reduction in PWA. A second scoring of respiratory events using PWA reduction as a surrogate for RRCA was performed (RP with PWA) for each percentage of PWA reduction. The final analysis consisted of determining the concordance between the two methods of detecting OH. ResultsA total of 987 episodes of ≥30% flow reduction were analyzed: 330 with RRCA only, 205 with desaturation (DS) only, 134 with both, and 318 without RRCA or DS. As the percentage of reduction in PWA increased, the sensitivity of PWA as a substitute for RRCA decreased, but the specificity increased. For a decrease in PWA of 60% or 70%, the sensitivities of PWA as a substitute for RRCA were 79% and 57%, and the specificities 51% and 76%, respectively. ConclusionPulse wave amplitude reduction lacks sensitivity and specificity to be used as a surrogate for RRCA to detect OH in children. Polysomnography remains the gold standard for the diagnosis of sleep disordered breathing in children.

Genetic determination of the vascular reactions in humans in response to the diving reflex.

The purpose of this study was to investigate the genetic mechanisms of the defense vascular reactions in response to the diving reflex in humans with polymorphisms in the genes ADBR2, ACE, AGTR1, BDKRB2, and REN We hypothesized that protective vascular reactions, in response to the diving reflex, are genetically determined and are distinguished in humans with gene polymorphisms of the renin-angiotensin and kinin-bradykinin system. A total of 80 subjects (19 ± 1.4 yr) participated in the study. The intensity of the vascular response was estimated using photoplethysmogram. The I/D polymorphism (rs4340) of ACE was analyzed by PCR. REN (G/A, rs2368564), AGTR1 (A/C, rs5186), BDKRB2 (T/C, rs1799722), and ADBR2 (A/G, rs1042713) polymorphisms were examined using the two-step multiplex PCR followed by carrying allele hybridization on the biochip. Subjects with the BDKRB2 (C/C), ACE (D/D), and ADBR2 (G/G, G/A) genotypes exhibited the strongest peripheral vasoconstriction in response to diving. In subjects with a combination of the BDKRB2 (C/C) plus ACE (D/D) genotypes, we observed the lowest pulse wave amplitude and pulse transit time values and the highest arterial blood pressure during face immersion compared with the heterozygous individuals, suggesting that these subjects are more susceptible to diving hypoxia. This study observed that humans with gene polymorphisms of the renin-angiotensin and kinin-bradykinin systems demonstrate various expressions of protective vascular reactions in response to the diving reflex. The obtained results might be used in estimation of resistance to hypoxia of any origin in human beings or in a medical practice.NEW & NOTEWORTHY Our study demonstrates that the vascular reactions in response to the diving reflex are genetically determined and depend on gene polymorphisms of the kinin-bradykinin and the renin-angiotensin systems.

Associations of intracranial pressure with brain biopsy, radiological findings, and shunt surgery outcome in patients with suspected idiopathic normal pressure hydrocephalus.

It remains unclear how intracranial pressure (ICP) measures are associated with brain biopsies and radiological markers. Here, we aim to investigate associations between ICP and radiological findings, brain biopsies, and shunt surgery outcome in patients with suspected idiopathic normal pressure hydrocephalus (iNPH). In this study, we retrospectively analyzed data from 73 patients admitted with suspected iNPH to Kuopio University Hospital. Of these patients, 71% underwent shunt surgery. The NPH registry included data on clinical and radiological examinations, 24-h intraventricular pressure monitoring, and frontal cortical biopsy. The mean ICP and mean ICP pulse wave amplitude were not associated with the shunt response. Aggregations of Alzheimer's disease (AD)-related proteins (amyloid-β, hyperphosphorylated tau) in frontal cortical biopsies were associated with a poor shunt response (P = 0.014). High mean ICP was associated with Evans' index (EI; P = 0.025), disproportional sylvian and suprasylvian subarachnoid spaces (P = 0.014), and focally dilated sulci (P = 0.047). Interestingly, a high pulse wave amplitude was associated with AD-related biopsy findings (P = 0.032), but the mean ICP was not associated with the brain biopsy. The ICP was not associated with medial temporal lobe atrophy, temporal horn widths, or white matter changes. ICP B waves were associated with less atrophy of the medial temporal lobe (P = 0.018) and more severe disproportionality between the sylvian and suprasylvian subarachnoid spaces (P = 0.001). The EI and disproportional sylvian and suprasylvian subarachnoid spaces were associated with mean ICP. Disproportionality was also associated with ICP B waves. These associations, although rather weak, with elevated ICP in 24-h measurements, support their value in iNPH diagnostics and suggest that these radiological markers are potentially related to the pathogenesis of iNPH. Interestingly, our results suggested that elevated pulse wave amplitude might be associated with brain amyloid accumulation.

Abstract 11582: Vascular, Hemodynamic and Hormonal Response to Mental Stress and Risk of Mental Stress Induced Myocardial Ischemia

Introduction: Mental stress-induced myocardial ischemia (MSIMI) has been linked to adverse cardiovascular outcomes in patients with stable CAD. However, the underlying mechanisms are not well understood. We aimed to study vasomotor, hemodynamic and hormonal responses to mental stress (MS) and their relationships with MSIMI. Methods: 660 patients with stable CAD underwent 99mTc sestamibi myocardial perfusion imaging before, and during a public speaking stressor. Hemodynamic parameters (heart rate, BP, rate-pressure product [RPP]), circulating catecholamines, and peripheral arterial tonometry (PAT, Itamar Inc.) were measured at rest, during, and after MS. MSIMI was defined as myocardial perfusion impairment with MS. Results: Participant age was 63±9; 72% male. Overall, 102 (16.1%) patients developed MSIMI. During MS, there was a significant increase in heart rate, BP, RPP and epinephrine, but not norepinephrine levels. The mean PAT ratio, measured as a ratio of the lowest pulse wave amplitude during the speaking task to the final three minutes of pulse wave amplitude during rest, was 0.7 ± 0.3 indicating vasoconstriction with MS. Patients with MSIMI had a greater hemodynamic response (Figure) and a lower PAT ratio (0.6±0.3 vs 0.7±0.3, p=0.008), in comparison to those with no ischemia. After adjustment for age, CAD risk factors and beta blocker use, both higher hemodynamic response (change in RPP≥median) and more vasoconstriction (PAT ratio&lt;median), but not catecholamine response, were independent predictors of MSIMI [OR(95%CI) of 1.8 (1.1-2.9) and 2 (1.2-3.3), p=0.02 and p=0.01, respectively]. A greater hemodynamic response and a lower PAT ratio had an incremental effect on incidence of MSIMI (Figure). Conclusion: A greater hemodynamic response and peripheral vasoconstriction are associated with MSIMI, indicating that both increased myocardial demand and potentially coronary vasoconstriction contribute to this phenomenon.

Relationship between intracranial pressure and phase contrast cine MRI derived measures of intracranial pulsations in idiopathic normal pressure hydrocephalus

Phase contrast cine MRI with determination of pulsatile aqueductal cerebrospinal fluid (CSF) stroke volume and flow velocity has been suggested to assess intracranial pulsations in idiopathic normal pressure hydrocephalus (iNPH). We aimed to compare this non-invasive measure of pulsations to intracranial pressure (ICP) pulse wave amplitude from continuous ICP monitoring. We hypothesised that a significant correlation between these two markers of intracranial pulsations exists. Fifteen patients with suspected iNPH had continuous computerised ICP monitoring with calculation of mean ICP pulse wave amplitude (MWA) from time-domain analysis. MRI measured CSF aqueductal stroke volume and peak flow velocity. Mean MWA was 5.4mmHg (range 2.3–12.4mmHg). Mean CSF stroke volume and peak flow velocity were 65μl (range 3–195μl) and 9.31cm/s (range 1.68–15.0cm/s), respectively. No significant correlation between the invasive and non-invasive measures of pulsations existed (Spearman r=−0.30 and r=−0.27, respectively; p>0.05). We observed marked intra-individual fluctuation of MWA during continuous ICP monitoring of an average of 6.0mmHg (range 2.8–12.2mmHg). The results suggest a complex interplay between measures of pulsations derived from snapshot MRI measurements and continuous computerised ICP measurements, as no significant relationship existed in our data. Further study is needed to better understand the temporal profile of CSF MRI flow studies, as substantial variation in MWA over the course of several hours of ICP monitoring is common, suggesting that these physiologic fluctuations might obscure MRI snapshot measures of intracranial pulsations.

Identifying depressed patients with and without suicidal ideation by finger photo-plethysmography.

Major Depressive Disorder (MDD) is a serious mental disorder that if untreated not only affects physical health but also has a high risk of suicide. While the neurophysiological phenomena that contribute to the formation of Suicidal Ideation (SI) are still ill-defined, clear links between MDD and cardiovascular disease have been reported. The aim of this study is to extract suitable features from arterial pulse signals with a view to predicting SI within MDD and control groups. Sixteen unmedicated MDD patients with a history of SI (MDDSI+), sixteen without SI (MDDSI-) and twenty-nine healthy subjects (CONT) were recruited at a psychiatric clinic in the UAE. Depression severity and SI were assessed using the Hamilton Depression Rating Scale and Beck Depression Inventory. Pulse Wave Amplitude (PWA) was calculated as the difference between the peak (Systole) and the valley (Diastole) of the arterial pulse within each cardiac cycle. Then, 2D Tone-Entropy (TE) features were extracted from the Systole, Diastole and PWA time series. The TE features extracted from Diastole were the best markers for predicting MDDSI+. The overall classification accuracies of Classification and Regression Tree (CART) model by using TE features of Systole, Diastole and PWA were 88.52%, 90.2% and 88.52% respectively. When all TE features were combined, accuracy increased up to 93.44% in identifying MDDSI+/MDDSI-/Control groups.