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BACKGROUND: Finger plethysmography derived stroke volumes are frequently measured during tilt table testing. There are two algorithms to determine stroke volumes: Modelflow and Nexfin CO Trek. Most tilt studies used Modelflow, while there are differences between the two algorithms. OBJECTIVE: To compare stroke volume indices by Nexfin CO Trek (SVINexfinCOTrek) with suprasternal Doppler derived SVI (SVIDoppler) in healthy controls (HC) and myalgic encephalomyelitis/chronic fatigue syndrome (ME/CFS) patients during tilt testing. These patients may have a large SVI decrease during the tilt enabling a large range of SVI to be studied. METHODS: One hundred and fifty-four patients and 39 HC with a normal tilt test were included. Supine and end-tilt SVIDoppler and SVINexfinCOTrek were compared using the Bland-Altman analysis. Also, the effect of calibrating supine SVINexfinCOTrek to SVIDoppler was studied. RESULTS: Supine and end-tilt SVINexfinCOTrek were significantly higher than SVIDoppler: both P< 0.005. Bias, limits of agreement, and percent error (PE) were high with PE’s between 37 and 43%. The calibration procedure resulted in an acceptable variance with a PE of 29%. CONCLUSIONS: SVINexfinCOTrek overestimates stroke volumes compared to SVIDoppler, leading to high PE’s. Calibration reduced variance to an acceptable level, allowing SVINexfinCOTrek to be used for assessment of SVI changes during tilt testing.

Background: Both endothelial dysfunction and low circulating androgen levels predict cardiovascular disease in men. Endothelial function evaluation is commonly performed by measuring flow-mediated vasodilatation of the brachial artery. However, studies have suggested that compared with evaluation of large arteries, microvascular function evaluation of peripheral arteries is a better predictor of increased cardiovascular disease risks. Although circulating levels of androgens, such as testosterone and dehydroepiandrosterone sulfate (DHEA-S), positively correlate with cardiovascular function, the association between circulating androgen levels and microvascular function is unknown. In this study, we investigated whether serum androgen levels correlate with microvascular endothelial function in men. Methods: The study included 105 Japanese men (age 59 ± 1 years) in whom we measured serum testosterone and DHEA-S levels. The reactive hyperemia index (RHI) determined by the Endo-PAT system (finger plethysmography) was used to evaluate microvascular endothelial function. Results: Serum testosterone levels were significantly correlated with the RHI (r = 0.32, P < 0.01). The association between serum testosterone levels and the RHI remained significant even after adjustment for confounders, including age and body mass index (β = 0.31, P < 0.01). Notably, serum DHEA-S levels were not associated with the RHI (r = 0.01, n.s.). Conclusion: This study showed that serum testosterone levels were positively correlated with microvascular endothelial function in men. These results suggest that endogenous testosterone level is one of the determinants of microvascular endothelial function and may become a biomarker reflecting lifestyle modifications-induced improvement in cardiovascular function in men.

Aging is associated with reductions in endothelial function, observations primarily reported using brachial artery ultrasound. There is growing interest in the use of peripheral artery tonometry (PAT) of microvessels in the fingertip to assess endothelial function because it is less technically demanding and has a high sensitivity and specificity for assessing coronary endothelial function. Moreover, similar to brachial artery flow-mediated dilation (FMD), PAT predicts cardiovascular disease outcomes. However, the relationship between PAT and FMD have yet to be examined in the context of aging. To address this question, reactive hyperemic index (RHI) using EndoPAT and FMD using brachial artery ultrasound were assessed after 5 min of forearm ischemia in 20 younger (18–40 yr old; 29 ± 4 yr) and 20 older (60–75 yr old; 65 ± 4 yr) healthy adult men. Higher values of both FMD and RHI indicate better endothelial function. Endothelial function assessed via brachial artery FMD was lower in older (4.8 ± 2.1%), compared with younger (7.5 ± 1.6%) men (P < 0.001). In contrast, the RHI assessed via PAT was greater in older (2.2 ± 0.6), compared with younger (1.8 ± 0.5) men (P = 0.014). FMD and RHI were not correlated (r = –0.15; P = 0.35). We conclude that PAT may not be an appropriate measure to evaluate age-associated changes in endothelial function. NEW & NOTEWORTHY Microvessel endothelial function assessed via finger plethysmography may not reflect age-associated reductions in large artery endothelial function assessed via brachial artery flow-mediated dilation.

Spontaneous BRS estimates may considerable vary according to the technique of blood pressure and heart rate assessment. To optimise and standardise BRS estimation for clinical use we evaluated possible differences between spontaneous BRS indices estimated from either finger plethysmography or radial tonometry. Forty-five healthy volunteers underwent simultaneous recordings of electrocardiogram, finger plethysmography and radial tonometry in supine position and during 60° head-up tilt. BRS was computed by spectral analysis from either R-R time series and/or arterial pressure pulse. Radial tonometry generated higher mean BRS estimates than finger plethysmography. The difference decreased upon postural change from supine to upright. In the upright position, BRS estimates based on R-R interval proved to be generally lower compared to BRS indices estimated from arterial pressure pulse. The ratio of low-to-high-frequency power of inter-systolic interval and systolic blood pressure from tonometry was lower than that from plethysmography in supine and approximated in upright position. Spectral parameters of inter-systolic interval and R-R interval did not differ in supine but diverged in upright position. Changes of spectral parameters were most pronounced in R-R interval. Arterial pressure pulse is adequate for estimation of BRS under resting conditions but it may distort BRS estimates under physical load. We, therefore, recommend using an ECG signal for BRS estimation especially in non-stationary conditions.

A major symptom of hand-arm vibration syndrome is a secondary Raynaud’s phenomenon—vibration white finger (VWF)—which results from a vasospasm of the digital arteries caused by work with vibration devices leading to occupational disease. Pharmacotherapy of VWF is often ineffective or has adverse effects. The aim of this work was to verify the influence of inhalation of partially ionized oxygen (O2•−) on peripheral blood vessels in the hands of patients with VWF. Ninety one (91)patients with VWF underwent four-finger adsorption plethysmography, and the pulse wave amplitude was recorded expressed in numeric parameters—called the native record. Next, a cold water test was conducted following with second plethysmography. The patients were divided in to the three groups. First and second inhaled 20-min of ionized oxygen O2•− or oxygen O2 respectively. Thirth group was control without treatment. All three groups a follow-up third plethysmography—the post-therapy record. Changes in the pulse wave amplitudes were evaluated. Inpatients group inhaling O2•− a modest increase of pulse wave amplitude was observed compared to the native record, patients inhaling medical oxygen O2 and the control showed a undesirable decline of pulse wave amplitude in VWF fingers. Strong vasodilatation were more frequent in the group inhaling O2•− compare to O2 (p &lt, 0.05). Peripheral vasodilatation achieved by inhalation of O2•− could be used for VWF treatment without undesirable side effect in hospital as well as at home environment.

Objective:Flow-mediated vasodilation (FMD) has become one of the most widely assessed parameter to analyze endothelial function. However, some techniques used to measure FMD have limitations. Recently, finger plethysmography (EndoPAT) failed to show any kind of reproducibility. A semi-automatic devi

Aims: We sought to determine the accuracy of finger plethysmography using pulse waveform analysis with brachial calibration for measurement of cardiac output during submaximal exercise by comparing it against an acetylene (C2H2) uptake technique. Methods: The study included 24 healthy volunteers (12 males, age 35 ± 8 years). Testing was performed on an upright cycle ergometer using an incremental protocol. Cardiac output measurements were performed at rest and during sub-maximal exercise using a single breath C2H2uptake technique and continuously using finger plethysmography with brachial calibration. Results: Valid results at rest and during sub-maximal exercise were achieved in 20 of 24 participants. Cardiac output at rest was 5·3 ± 1·1 and 5·2 ± 1·2 l min-1for finger plethysmography and C2H2,respectively, P = 0·712. Mean difference between techniques was -0·1 ± 0·5 l min-1. Cardiac output during submaximal exercise was 10·2 ± 2·3 and 10·3 ± 2·1 l min-1for finger plethysmography and C2H2,respectively, P = 0·898. Mean difference between techniques was 0·1 ± 1·5 l min-1. The overall correlation between finger plethysmography and C2H2data obtained during rest and exercise was r2= 0·872, P

A B S T R A C T In the fight against cardiovascular diseases, preventive strategies are becoming the focus of attention. One of these strategies proposes to identify individuals who are at a high risk of developing cardiovascular disease. Endothelial dysfunction could improve patient risk stratification and the implementation of preventive strategies. In this review we focus on noninvasive techniques that have recently become available to assess endothelial function: flow-mediated vasodilation as measured by ultrasound of the brachial artery, pulse wave analysis, and finger plethysmography during postischemic hyperemia. We describe the basic principles, the main protocols to perform these techniques, and their clinical value based on the scientific evidence.

Summary Background: The aims of this study were to establish the optimum duration of blood flow occlusion to obtain maximal response and to compare the response after lower-arm and upper-arm occlusion. Methods: Pulse wave amplitude was analysed using a novel finger plethysmograph (EndoPat; Itamar). For measuring reactive hyperaemic index (RHI) induced by forearm cuff occlusion, 30 healthy subjects were examined at different days in a random order of four cuff occlusion times (1·5, 3, 5 and 8 min). RHI induced by 5 min upper-arm cuff occlusion was also measured in 20 subjects. Results: Average RHI was lower with 1·5 and 3 min forearm occlusion compared with 8 min forearm occlusion (P = 0·002 and P = 0·024). There was no significant difference between values of 5 min and 8 min forearm occlusion and between 5 min forearm and 5 min upper-arm occlusion (P = 0·1). All subjects reported less discomfort after forearm occlusion compared with upper-arm occlusion. Conclusion: Maximum response was reached after 5 min of blood flow occlusion and therefore this occlusion time is recommended. The response after forearm and upper-arm occlusion did not differ significantly. Forearm occlusion might be preferred as this caused less discomfort.

Successful treatment of cough syncope depends on the correction of various pathogenetic mechanisms among different patients. The valsalva maneuver (VM), which elicits hemodynamic responses mimicking coughs, has potential for investigating the individual pathogenesis of cough syncope. Eighteen consecutive patients suffering from cough-induced syncope were examined. All patients were asked to cough and to perform VM several times under continuous cerebral blood-flow velocity and blood pressure (BP) monitoring by transcranial Doppler and finger plethysmography. Eight patients demonstrated abnormal VM characterized by the absent BP overshoot following the relief of straining. Patients demonstrating abnormal VM had delayed BP recovery after cough (median, 16.4; range, 8.7–25.6 seconds) compared to those demonstrating normal VM (2.6, 1.3–3.8 seconds, p < 0.001). Seven of the 10 patients exhibiting normal BP overshoot during VM had stenotic arterial lesions in the cerebral or coronary circulation, whereas only one of the eight patients demonstrating absent BP overshoot had coronary artery disease (70% vs. 12.5%, p = 0.025). Other clinical profiles, body mass index, frequency of obstructive pulmonary disease and valsalva ratio did not differ between patients featuring normal and absent BP overshoot. In conclusion, the pathogenesis of cough syncope could be different between patients with normal and abnormal VM responses. Patients who had no BP overshoot during VM sustained prolonged hypotension after cough. The VM helps in discriminating among pathogenic mechanisms and guiding investigation and treatment for cough syncope patients.

We tested a simple noninvasive method for cardiac resynchronization therapy (CRT) optimization using standard finger photoplethysmography (FPPG).CRT can increase left ventricular cardiac output in patients with heart failure and ventricular conduction delay. Optimal therapy delivery depends on an appropriate AV delay. Multiple invasive and noninvasive methods have been attempted to identify patients and the best AV delay for CRT, but all suffer from a combination of high patient risk, cost, complexity, and low reproducibility.FPPG and invasive aortic pressure data were simultaneously collected from 57 heart failure patients during intrinsic rhythm alternating with very brief periods of pacing at 4 to 5 AV delays. After correcting data for artifacts, the median percentage responses for each AV delay were classified as positive, negative, or neutral compared to baseline (Wilcoxon rank test).FPPG correctly identified positive aortic pulse pressure responses with 71% sensitivity (95% CI: 60-80%) and 90% specificity (95% CI: 84-94%) and negative aortic pulse pressure responses with 57% sensitivity (95% CI: 44-69%) and 96% specificity (95% CI: 91-98%). The magnitude of FPPG changes were strongly correlated with positive aortic pulse pressure changes (R(2) = 0.73, P.0001) but less well correlated with negative aortic pulse pressure changes (R(2) = 0.43, P.0001). FPPG selected 78% of the patients having positive aortic pulse pressure changes to CRT and identified the AV delay giving maximum aortic pulse pressure change in all selected patients.FPPG can provide a simple noninvasive method for identifying significant changes in aortic pulse pressure with high specificity, including identifying patients in whom aortic pulse pressure increases with CRT and the AV delay giving the maximum aortic pulse pressure.

Background: The purpose of the present paper was to clarify the etiologic and pathophysiologic bases of periventricular lucency (PVL). Methods: The relationship between PVL severity and hemodynamic variables derived by second-derivative finger plethysmography (SD-PTG) was studied. A total of 307 consecutively examined outpatients 60 years or older (mean age: 77.7 years; 149 men, 158 women) was enrolled. On the basis of brain computed tomography, PVL was classified into four grades (0–3) according to a modification of the classification of van Swieten. The grade of PVL was assessed at two points in each patient: anterior and posterior. The heights of the a, b, and d waves on the SD-PTG waveform were measured from baseline. The b/a ratio, indicating distensibility of the aorta, and the d/a ratio, indicating peripheral resistance, were calculated. Results: An anterior PVL of grade 3 had a significantly higher b/a ratio and a significantly lower d/a ratio than that of grade 0 or grade 1 (both P < 0.05). For posterior PVL, the b/a ratio and the d/a ratio were similar for all four grades. The anterior PVL grade was compared with the posterior PVL grade in individual subjects. This comparison yielded six groups: four in which PVL grade was similar (0, 1, 2 or 3) in both regions, one in which the grade for anterior PVL was higher than that for posterior PVL (predominantly anterior group), and one in which the grade for posterior PVL was higher than that for anterior PVL (predominantly posterior group). In patients with predominantly anterior PVL, the b/a ratio and incidence of lacunae were significantly higher than that in patients with predominantly posterior PVL. Conclusion: These findings indicate that the frontal white matter is susceptible to hemodynamic stress. It is suggested that decreased aortic distensibility may promote fibrohyaline thickening of the medullary arteries, increasing the risk of PVL.

In an investigation of blood-pressure changes during interview, it was found that random emotional stresses were uncovered which had potent pressor effects in normal controls, in hypertensives and in neurotics. It was notable that the diastolic increases were proportionately greater than the systolic, and that those random emotional stresses on average possessed more pressor effect than a deliberately imposed physiological stress such as breath-holding. Certain individuals also showed marked pressor responses to varied stimuli such as being asked to do mental arithmetic, or the desire on micturate. All subjects showed an increase in systolic and diastolic pressures at the start of interview; in the control group this tended to level off symmetrically as the interview closed, but the hypertensive and neurotic groups showed a sustained rise of pressure and the resting levels after interview did not fall as low as the pre-interview resting values. No consistent topics were found to be pressor in effect, but it appeared that pressor responses occurred (1) with novel or “alerting” stimuli; (2) when the subject talked about herself, about illness or about her husband; (3) when the subject's verbal output increased. The heart rate tended to increase along with the blood-pressure, but subjects having higher blood-pressure levels tended to have slower heart rates. Finger plethysmography showed that peripheral vasoconstriction accompanied pressor responses, and vasodilatation occurred as blood-pressure fell. A neurotic patient with labile blood-pressure was interviewed on 24 occasions, and several unusual features are described. No constant or reliable association was discovered to exist between the temporal electro-encephalogram and the blood-pressure changes. It is concluded that two types of emotionally-caused pressor responses may exist; one which may be keyed to the life-situation and is sustained in effect over a period of hours or days or longer, and another which is more transient and may represent a non specifIc alerting reaction.

In patients with heart failure, left ventricular systolic dysfunction and prolonged QRS complex, cardiac resynchronization therapy (CRT) is a treatment method aimed at restoration of myocardial depolarization synchronicity. However, the extent of clinical and echocardiographic improvement depends on anatomical relations in individual patients, on structural changes in the heart, on intrinsic electrical activation, and on the position of pacing leads. Many parameters of CRT devices may be changed in order to tailor the function of CRT to the needs of a particular patient; the most important among them is AV and VV interval. The largest trials studying CRT used various methods for optimization of these intervals but unequivocal proof of the benefit brought by optimization is still lacking. Many methods were evaluated, most frequently based on echocardiography and intracardiac electrogram interval measurement. However, drawbacks in statistics make the studies of limited value for establishing a reference method or guidance for daily practice. Echocardiography has inherent variability of results and is highly operator dependent. Optimization based on intracardiac electrogram intervals has not proved yet to be of clear benefit above arbitrary AV interval. The most promising method is hemodynamic assessment by finger plethysmography. Measured data are highly reproducible and operator-independentA randomized multicenter double-blind study using finger plethysmography is needed to prove the value of this method and of CRT optimization in general. The measurement of information content in any data suitable for CRT optimization, analysis of reproducibility and general usage of confidence intervals may show other methods appropriate for it, too. The cooperation with a statistician is oftentimes a necessity.

A non-invasive method of measuring blood pressure in the finger continuously was developed by Penaz in 1976 [2], Since then the method has been further developed by Wesseling et al. [3] to produce an instrument which is easy to use in the clinical setting.1