Pulse Curve Research Articles

Novel techniques for quantifying oxygen pulse curve characteristics during cardiopulmonary exercise testing in tetralogy of fallot

BackgroundCardiopulmonary exercise testing (CPET) is used in evaluation of repaired tetralogy of Fallot (rTOF), particularly for pulmonary valve replacement need. Oxygen pulse (O2P) is the CPET surrogate for stroke volume and peripheral oxygen extraction. ObjectivesThis study assessed O2P curve properties against non-invasive cardiac output monitoring (NICOM) and clinical testing. MethodsThis cross-sectional study included 44 rTOF patients and 10 controls. Three new evaluations for O2P curve analysis during CPET were developed. Best fit early and late regression slopes of the O2P curve were used to calculate: 1) the early to late ratio, or “O2 pulse response ratio” (O2PRR); 2) the portion of exercise until slope inflection, or “flattening fraction” (FF); 3) the area under the O2P response curve, or “O2P curve area”. ResultsrTOF patients (median age 35.2 (27.6–39.4); 61% female) had a lower VO2 max (23.4 vs 45.6 ml/kg/min; p < 0.001) and O2P max (11.5 vs 19.1 ml/beat; p < 0.001) compared to controls. Those with a FF occurring <50% through exercise had a lower peak cardiac index and stroke volume, but not VO2 max, compared to those >50%. FF and O2P curve area significantly correlated with peak cardiac index, stroke volume, left and right ventricular ejection fraction, and right ventricular systolic pressure. ConclusionCPET remains an integral part in the evaluation of rTOF. We introduce three non-invasive methods to assess exercise hemodynamics using the O2P curve data. These evaluations demonstrated significant correlations with stroke volume, cardiac output, and right ventricular pressure.

Americium-241 in peat bogs as a global marker of the beginning of the Anthropocene: examples from Europe and North America.

Fallout radionuclides, potential global indicators of the Anthropocene, raise questions about their preservation in bogs. This study evaluates the reliability of &lt;sup&gt;241&lt;/sup&gt;Am records in acidic, ombrotrophic peat cores. The &lt;sup&gt;241&lt;/sup&gt;Am source is the radioactive decay of the short-lived &lt;sup&gt;241&lt;/sup&gt;Pu (half-life 14.29 years) present in fallout from atmospheric nuclear weapons testing. We assessed 35 peat cores from 30 European and North American sites, collected over three decades for trace metal deposition studies. Each core underwent independent &lt;sup&gt;210&lt;/sup&gt;Pb dating. We excluded 10 cores due to significant &lt;sup&gt;241&lt;/sup&gt;Am peak quantification uncertainty. Of the remaining 25 cores, 22 displayed a single &lt;sup&gt;241&lt;/sup&gt;Am peak and 3 exhibited two peaks with similar activities. Among the 22 single-peak cores, 18 were within 10 years of AD 1963, with 10 within 5 years. For 10 of these 22 cores, &lt;sup&gt;14&lt;/sup&gt;C dates from the atmospheric bomb pulse curve were compared, showing ≤ 10 years of difference, with 7 cores ≤ 5 years from the &lt;sup&gt;210&lt;/sup&gt;Pb CRS model AD 1963. Factors contributing to age discrepancies included analytical limitations in &lt;sup&gt;241&lt;/sup&gt;Am measurements, peat accumulation rates affecting &lt;sup&gt;241&lt;/sup&gt;Am activities, post-depositional migration of &lt;sup&gt;241&lt;/sup&gt;Pu and/or &lt;sup&gt;241&lt;/sup&gt;Am, uncertainties in &lt;sup&gt;210&lt;/sup&gt;Pb age-modelling, and limited &lt;sup&gt;14&lt;/sup&gt;C samples. The utility of &lt;sup&gt;241&lt;/sup&gt;Am as an Anthropocene marker depends on the accepted uncertainty level in defining this epoch. The detection of &lt;sup&gt;241&lt;/sup&gt;Am in 35 cores, validated in 22 cores, suggests a hemispheric Anthropocene onset. The bomb pulse curve of &lt;sup&gt;14&lt;/sup&gt;C in bogs could serve as an alternative marker. Common &lt;sup&gt;137&lt;/sup&gt;Cs post-depositional migration in ombrotrophic peatlands contrasts with its immobility in minerotrophic peatlands, suggesting the latter may also retain nuclear weapons test fallout, including &lt;sup&gt;241&lt;/sup&gt;Am.

Experimental study of true triaxial high pressure subcritical water impact fracturing

A new fluid alternative to slick water for fracturing shale gas can reduce the waste of water resources and improve the extraction efficiency, enabling volumetric fracturing. For the new fracturing technique, the experiments of different release pressures under pre-injection and for pre-injection were conducted using a self-designed true triaxial experimental system, and the pressure pulse curves were plotted to analyze the fracturing principle. The experimental results showed that: (1) the pressure rise curve in the reactor can be divided into five stages: initial reaction, linear pressure rise, rate slowdown, instantaneous pressure release, and residual pressure stages; (2) Pre-filling fracturing requires a smaller expansion ratio, weaker pressure degradation, resulting in better fracturing effect; (3) The increase in the initial fracture length leads to an increase in the pressure required to extend the fracture, and high-pressure subcritical water impact fracturing achieved fracture extension at a lower fluid pressure; (4) The fractal dimension has a strong linear relationship with fracture complexity, which is a new option when evaluating the fracturing effect. Volumetric fracturing allows for the creation of more tiny trenches that increase reservoir permeability, leading to better recovery of the reservoir’s energy resources.

O2 pulse slope correlates with stroke volume during exercise in patients with a Fontan circulation

BackgroundPeak oxygen pulse (O2pulse=oxygen consumption/heart rate) is calculated by the product of stroke volume (SV) and oxygen extraction. It has been shown to be reduced in patients with a Fontan...

Peripheral perfusion index in critically ill COVID-19 and its association with multiorgan dysfunction

Introduction: Severe cases of COVID-19 presented a high incidence of multi-organ dysfunction syndrome (MODS) during their evolution. This was attributed to a theoretical cytokine storm, where microcirculatory disorders would play a fundamental role, causing these patients to present a sepsis-like pattern as observed in sublingual microcirculation studies. The evidence in this regard is controversial. The Peripheral Perfusion Index is a reliable method to continuously and non-invasively assess the microcirculatory bed, which assesses the pulsatile (PPI) component of the plethysmographic pulse curve. Methods: We conducted a prospective observational study to evaluate the behavior of the PPI in patients with severe respiratory failure due to SARS-CoV-2 and its association with SDOM. Results: We evaluated 60 patients with APACHE II 14.6 ± 4.4 and SOFA 4.7 ± 2.1. 55% of the patients presented SDOM. Perfusion monitoring showed IP values of 5.32 ± 1.87 that were associated with normal lactate levels of 1.49 mmol/L (min 0.89/ max 2.20 mmol/L). The PPI values between the living and the dead did not show a significant difference (p = 0.854) or the presence of SDOM. The PPI values between the patients who presented renal failure, hemodynamics, or perfusion disorders were determined by the presence of hyperlactatemia, and for those who did not present these characteristics, no statistical difference was found; neither when stratified by PaFiO2 ratio. Mortality was 55%. Conclusion: In our series of patients with severe pneumonia due to COVID-19, we found high PPI values, which would correspond to a pattern of capillary recruitment, and the associated organ injury could not be substantiated by this phenomenon.

A Coupling Optimization Method of Vehicle Structure and Restraint System for Occupant Injury Protection in Traffic Accidents

Vehicle front-end structure has the characteristic of symmetry. The damage of occupants in the crash process is determined by the combined effect of the front-end structure and the restraint system of the vehicle. In this paper, the coupling relationship and an optimized method for the vehicle front-end structure and restraint system are studied based on vehicle crash dynamics, to reduce occupant injury. A fast solution algorithm for occupant motion response was established using a crash analytical model. Then, an occupant response database was established using the algorithm, to analyze the coupling relationship between the crash pulse and the restraint specific stiffness, with respect to the curve shape and parameters. The results showed that the combination of the concave crash pulse and upward restraint stiffness curve was the best coupling. Subsequently, a coupled optimization method of a concave pulse and upward restraint stiffness was proposed and combined with a crash analytical model and genetic algorithm (GA). The crash pulse and restraint stiffness of vehicle crash data from the NHTSA databases were optimized, as an example, to verify the effectiveness of the method. The optimal occupant acceleration was reduced by 44%. In addition, the feasibility of the optimal result is discussed, to provide a reference for occupant injury protection in traffic accidents.

A high performance RC-INV triggering SCR under 0.25 µm process

PurposeAs it is known, the electrostatic discharge (ESD) protection design of integrated circuit is very important, among which the silicon controlled rectifier (SCR) is one of the most commonly used ESD protection devices. However, the traditional SCR has the disadvantages of too high trigger voltage, too low holding voltage after the snapback and longer turn-on time. The purpose of this paper is to design a high-performance SCR in accordance with the design window under 0.25 µm process, and provide a new scheme for SCR design to reduce the trigger voltage, improve the holding voltage and reduce the turn-on time.Design/methodology/approachBased on the traditional SCR, an RC-INV trigger circuit is introduced. Through theoretical analysis, TCAD simulation and tape-out verification, it is shown that RC-INV triggering SCR can reduce the trigger voltage, increase the holding voltage and reduce the turn-on time of the device on the premise of maintaining good robustness.FindingsThe RC-INV triggering SCR has great performance, and the test shows that the transmission line pulse curve with almost no snapback can be obtained. Compared with the traditional SCR, the trigger voltage decreased from 32.39 to 16.24 V, the holding voltage increased from 3.12 to 14.18 V and the turn-on time decreased from 29.6 to 16.6 ns, decreasing by 43.9% the level of human body model reached 18 kV+.Originality/valueUnder 0.25 µm BCD process, this study propose a high-performance RC-INV triggering SCR ESD protection device. The work presented in this paper has a certain guiding significance for the design of SCR ESD protection devices.

A MODERN MULTICENTENNIAL RECORD OF RADIOCARBON VARIABILITY FROM AN EXACTLY DATED BIVALVE CHRONOLOGY AT THE TREE NOB SITE (ALASKA COASTAL CURRENT)

ABSTRACTQuantifying the marine radiocarbon reservoir effect, offsets (ΔR), and ΔR variability over time is critical to improving dating estimates of marine samples while also providing a proxy of water mass dynamics. In the northeastern Pacific, where no high-resolution time series of ΔR has yet been established, we sampled radiocarbon (14C) from exactly dated growth increments in a multicentennial chronology of the long-lived bivalve, Pacific geoduck (Paneopea generosa) at the Tree Nob site, coastal British Columbia, Canada. Samples were taken at approximately decadal time intervals from 1725 CE to 1920 CE and indicate average ΔR values of 256 ± 22 years (1σ) consistent with existing discrete estimates. Temporal variability in ΔR is small relative to analogous Atlantic records except for an unusually old-water event, 1802–1812. The correlation between ΔR and sea surface temperature (SST) reconstructed from geoduck increment width is weakly significant (r2= .29, p = .03), indicating warm water is generally old, when the 1802–1812 interval is excluded. This interval contains the oldest (–2.1σ) anomaly, and that is coincident with the coldest (–2.7σ) anomalies of the temperature reconstruction. An additional 3214C values spanning 1952–1980 were detrended using a northeastern Pacific bomb pulse curve. Significant positive correlations were identified between the detrended14C data and annual El Niño Southern Oscillation (ENSO) and summer SST such that cooler conditions are associated with older water. Thus,14C is generally relatively stable with weak, potentially inconsistent associations to climate variables, but capable of infrequent excursions as illustrated by the unusually cold, old-water 1802–1812 interval.

Simulation of the temporal resolution uniformity of a dilation framing camera.

The temporal resolution uniformity of a time-dilation framing camera is studied, and the ideal photocathode (PC) pulse curve is determined, while the temporal magnification factor is kept constant. To obtain the ideal curve, a series of linear pulses with the same slope are superposed. The variance in the temporal resolution and the number of linear pulses required are compared, while the superposition results with different slopes are used as the PC voltage. As the slope of the linear pulses decreases, the variance decreases, which means that the uniformity of the temporal resolution is improved, but the number of linear pulses required increases. In this study, linear pulses with a slope of 1V/ps are superposed. Nine linear pulses with a front edge time of 200ps, amplitude of 200V, and flat top time of 1ns are superimposed to approximate the ideal PC pulse curve with a constant temporal magnification factor of 10; the trigger times of the pulses are 0, 0, 0, 185, 200, 350, 450, 605, and 790ps. When the superposition result is applied as the PC voltage and the measured signal is synchronized to the PC pulse at 128ps-1ns, the temporal resolution error is within 5%.

Single event effects prediction of MOSFET device using deep learning

Single event effect (SEE) is an important problem in the reliability research of integrated circuits. The study of SEE of traditional MOSFET devices is mainly based on simulation software, which is characterized by slow simulation speed, large computation and time-consuming. In this paper, a SEE research method based on deep learning is proposed. The method relies on 28 nm MOSFET. The complete drain transient current pulse, transient current peak value and total collected charge can be obtained in a short time by inputting relevant parameters that affect the SEE. The accuracy of the network for predicting transient current peak and total collected charge is 96.95% and 97.53% respectively, and the mean goodness of fit of the network for predicting the drain transient current pulse curve is 0.985. Compared with TCAD Sentaurus software, the simulation speed is increased by 5.89 × 103 and 1.50 × 103 times respectively. This method has good prediction effect and provides a new possibility for the study of SEE.

Post Covid MIS-C Myocarditis Medium Term Exercise Limitations

PURPOSE: Myocarditis is one of the presentations of multisystemic inflammatory syndrome in children (MIS-C) following Coronavirus disease 2019 (COVID 19). Good short term prognosis is reported, however, data regarding long term functional capacity are scarce. our purpose was to evaluate exercise capacity and possible limitations in children post myocarditis caused by MIS-C following COVID 19. METHODS: Children with MIS-C myocarditis underwent spirometry and cardiopulmonary exercise testing (CPET) and compared with age, sex, weight and activity level matched control group. RESULTS: Twenty-eight children (14 with MIS-C) completed CPET. No significant differences were noticed between the groups. Pulmonary function tests were similar between the groups (MIS-C FEV1=92±9.4%pred, Control FEV1=95±10%pred) with three patients with abnormal values in the MIS-C group and one in the control group. Peak oxygen uptake (peak VO2) were within the normal range in both groups (MIS-C 89 ±8.9%pred of predicted VO2; Control 87 ±13.7%pred) . However, in the MIS-C group five patients (35%) presented abnormal responses to exercise, necessitating further follow up before returning back to routine activity compared to no patient in the control group. Two patients had flattening of the oxygen pulse curve suggesting possible stroke volume limitation and three patients showed oxygen desaturation (88-92%) at peak effort. CONCLUSIONS: Post MIS-C pediatric patients may present with exercise limitations. Functional assessment (e.g. CPET) should be considered as part of the routine examination before returning to normal active routine in children post MIS-C myocarditis. Larger prospective long-term studies assessing functional capacity and focusing on physiological and molecular mechanisms are needed.

Is Exercise Stress Testing Useful for Risk Stratification in Anomalous Aortic Origin of a Coronary Artery?

Data on maximal exercise-stress-testing (m-EST) in anomalous-aortic-origin-of-coronary-arteries (AAOCA) is limited and correlation with stress perfusion imaging has not been demonstrated. AAOCA patients ≤20 years were prospectively enrolled from 6/2014-01/2020. A m-EST was defined as heart rate >85%ile on ECG-EST and respiratory-exchange-ratio ≥1.05 on cardiopulmonary-exercise-testing (CPET). Abnormal m-EST included significant ST-changes or high-grade arrhythmia, V̇O2max and/or O2 pulse <85% predicted, or abnormal O2 pulse curve. A (+) dobutamine-stress cardiac-magnetic-resonance-imaging (+DS-CMR) had findings of inducible-ischemia. Outcomes: (1) Differences in m-EST based on AAOCA-type; (2) Assuming DS-CMR as gold-standard for detection of inducible ischemia, determine agreement between m-EST and DS-CMR. A total of 155 AAOCA (right, AAORCA=126; left, AAOLCA=29) patients with a median (IQR) age of 13 (11-15) years were included; 63% were males and a m-EST was completed in 138 (89%). AAORCA and AAOLCA had similar demographic and m-EST characteristics, although AAOLCA had more frequently evidence of inducible ischemia on m-EST (P = 0.006) and DS-CMR (P = 0.007). Abnormal O2 pulse was significantly associated with +DS-CMR (OR 5.3, 95% CI 1.6-18,P = 0.005). Sensitivity was increased with addition of CPET to ECG-EST (to 58% from 19%). There was no agreement between m-EST and DS-CMR for detection of inducible ischemia. A m-EST has very low sensitivity for detection of inducible ischemia in AAOCA, and sensitivity is increased with addition of CPET. Stress perfusion abnormalities on DS-CMR were notconcordant with m-EST findings and adjunctive testing should be considered for clinical decision making in AAOCA.

Short circuit fault identification and diagnosis analysis of rotor winding for variable speed pumped storage unit

Rotor winding short circuit is a frequent fault type of generator unit. Compared with the traditional fixed-speed unit using DC excitation, the three-phase AC excitation structure of the variable speed pumped storage unit is more complicated, and the fault diagnosis of the rotor winding short circuit is more difficult. Therefore, this paper proposes an offline diagnosis method for variable speed pumped storage units based on the principle of Repetitive Surge Oscillograph (RSO). Firstly, the application scheme of the repeated pulse method in the variable speed pumped storage unit is designed. By injecting low-voltage pulses into three phases simultaneously and detecting the response curve to determine whether the unit has a short-circuit fault. Then, based on the response characteristics of different rotor winding short-circuit fault types, an identification scheme of rotor winding short-circuit fault types and faulty phases is proposed. Subsequently, the variational mode decomposition (VMD)-teager energy operator (TEO) method is used to estimate the injected pulse and characteristic curve’s initial sudden change position and then the fault position is determined by the time difference and the measured wave velocity. The simulation results show that the fault identification and fault location method proposed in this paper can be effectively applied to various rotor winding short-circuit faults of variable speed pumped storage units.

Influence and Optimization Analysis of Servo Stroke Curve Design on Adhesive Wear in Deep Drawing of Tantalum

The degree of wear on a material’s surface after deep drawing has a great influence on the performance and quality of the product; in particular, tantalum plates are prone to adhesive wear during deep drawing. In this paper, we propose a method to improve the surface quality of deep drawing products by optimizing the servo pulse stroke curve to solve the above problems. At the same time, in order to explore the influence of curve parameters on the adhesive wear of tantalum sheets in deep drawing, nine drawing stroke pulse curves are designed, with three levels and four factors. The finite element method is used to analyze the wear depth change of dies and products after drawing with different curve modes. It is found that the wear results obtained under the different curves differ greatly. Considering the actual production efficiency and production quality, the drawing time and the maximum wear depth are taken as optimization objectives. An analysis of variance is carried out using the Minitab software, considering the maximum wear depth and deep drawing time of the product in the finite element analysis results, and the best parameter combination is obtained for each quality characteristic. Then, the optimal drawing stroke curve is obtained using Taguchi grey relational analysis, with its grey relational grade being the highest among all curves. Finally, the optimal curve is compared against a traditional curve on a servo press. The results show that the surface quality of the product and the drawing efficiency can be improved by the use of the optimized mode; in particular, compared with traditional drawing, the maximum wear depth is reduced by 56.67% and the drawing time is reduced by 18.06%.

Updating the Child Restraint Systems Reference List for ASEAN NCAP

&#x0D; &#x0D; &#x0D; Child car occupants must be secured using appropriate Child Restraint Systems (CRS) in order to reduce the risk of severe injuries in the case of crashes or emergency braking. As part of ASEAN NCAP protocol, the so-called "CRS Reference List" of widely available, well performing child seats was established to assess a vehicle’s ability to safely and correctly accommodate child seats. In 2017, ASEAN NCAP introduced a new upper and lower limit crash pulse curve to better represent crashworthiness of cars available in the ASEAN market. With this new curve, the CRS Reference List must be reviewed accordingly; which is the aim of this project. This paper describes the process to update the CRS Reference List, starting from exploring the potential of CRS in three ASEAN markets (i.e., Malaysia, Thailand and Indonesia). The identified CRS were then evaluated based on several selection criteria (i.e., availability, regulation approved, weight group combination, price, size and installation direction). Based on the evaluation, several CRS are shortlisted for further technical assessment following ASEAN NCAP Child Occupant Protection (COP) protocol. The CRS shortlist is presented in this paper. However, the proposed CRS Reference List will not be disclosed in this work.&#x0D; &#x0D; &#x0D;

Crowd jumping load simulation with generative adversarial networks

To mathematically represent crowd jumping loads, the features of the jumping load of each person, including pulse curve patterns, pulse interval sequences, and pulse energy sequences are considered. These features are essentially highdimensional random variables. However, they have to be represented in a practically simplified model due to the lack of mathematical tools. The recently emerged generative adversarial networks (GANs) can model high-dimensional random variables well, as demonstrated in image synthesis and text generation. Therefore, this study adopts GANs as a new method for modelling crowd jumping loads. Conditional GANs (CGANs) combined with Wasserstein GANs with gradient penalty (WGANs*—GP) are used in pulse curve pattern modelling, where a multi-layer perceptron and convolutional neural network are selected as the discriminator and generator, respectively. For the pulse energy sequence and pulse interval sequence modelling, similar GANs are used, where recurrent neural networks are selected as both the generator and discriminator. Finally, crowd jumping loads can be simulated by connected the pulse samples based on the pulse energy sequence samples and interval sequence samples, generated by the three proposed GANs. The experimental individual and crowd jumping load records are utilized in training GANs to ensure their output can simulate real load records well. Finally, the feasibility of the proposed GANs was verified by comparing the measured structural responses of an existing floor to the predicted structural responses.

Effects of estradiol treatments on PGF2α release in beef heifers submitted to estrous resynchronization 14 days after timed-AI

The effects of 17β‐estradiol (E2) or estradiol benzoate (EB) on PGF2α release were studied in bred-non-pregnant and pregnant Nelore beef heifers. The day of timed artificial insemination (TAI) was designated day 0 (D0), and a single treatment was given on D14. All heifers also received an intravaginal P4 device on D14, and were randomly assigned to three groups: Control (C, P4 device only, n = 12); E2 (1 mg E2 + 9 mg P4, n = 10); or EB (1 mg, n = 10). Blood samples were collected hourly for 8 hours after treatment (Hours 0–8) to measure plasma concentrations (pg/mL) of a PGF2α metabolite (PGFM). The P4 device was removed on D22 and pregnancy was diagnosed on D28. Pregnancy rate was not different among groups (C, n = 7/12; E2, n = 5/10; EB, n = 5/10). More (P < 0.05) heifers had a CV-identified prominent PGFM pulse (peak of > 100 pg/mL) in E2 group (6/10) than in EB (1/10) and C (0/12) groups. Hourly concentration of PGFM for Hours 0 to 8 showed significant effects of group and hour and an interaction of group by hour but did not show an interaction of group or hour with pregnancy status. In preliminary post-hoc analyses, PGFM concentrations during Hours 0 to 8 and pulse characteristics were analyzed within each pregnancy status. For the non-pregnant heifers, a group-by-hour interaction was detected tentatively indicating an increase (P < 0.005) in PGFM concentrations in E2 group from Hours 4 to 6 and in EB group at Hours 5 and 6. Maximum PGFM concentration during Hours 0 to 8 did not differ (P > 0.1) between E2 (124 ± 23) and EB (110 ± 30) groups, but was greater (P < 0.05) in each group than in C (32 ± 3). Furthermore, PGFM concentrations of pulses at the peak, amplitude, and area under pulse curve (pg/mL/h) were greater (P < 0.05) in E2 group than in C group whereas the EB group did not differ (P > 0.1) from the other groups. For pregnant heifers, no effects of group, hour, or their interaction were detected in PGFM concentrations during the hourly sessions, except that maximum PGFM concentration was greater (P < 0.05) in E2 than in EB and C groups. In addition, the number of prominent pulses was greater in E2 group than in Control or EB groups. In conclusion, PGFM increased earlier and in greater concentration combined for bred-non-pregnant and pregnant heifers treated 14 days after TAI with 1 mg E2 plus 9 mg P4 than with 1 mg EB. Tentatively, a positive effect for each of E2 and EB on PGFM concentrations was attenuated in pregnant heifers.

Arrhythmia as an Incidental Finding

Arrhythmia as an Incidental Finding Abstract. An arrhythmic pulse can be determined using clinical or technical examinations such as palpitation and ECG. Due to the rapid spread of wearables, more and more people have the opportunity to derive pulse curves or even ECGs themselves before seeking professional medical care, which increases the number of randomly detected arrhythmic pulse. Incidental findings naturally lead to relevant diagnoses in some of the people affected, but on the other hand they are also psychologically stressful for some individuals. Therefore, it is important to differentiate frequently found common benign causes from the causes with therapeutic consequence and to adequately inform patients about their rhythm. In particular bradyarrhythmias often have no therapeutic consequence as long as the patient remains asymptomatic. Pacemakers are usually only indicated for symptomatic bradycardia. Atrial fibrillation deserves special attention due to its frequency and the fact that, if undetected, this is associated with significantly increased morbidity and mortality. Supraventricular and ventricular extrasystoles increase with age. They are often "idiopathic", but they also can be an expression of still subclinical heart disease.

Development of a hardware-software measurement system for the collection, detection, and processing of photoplethysmograms

A photoplethysmograph with a data acquisition circuit board, using a USB interface and an analog optical sensor, was developed. This study describes an information system for collecting, processing, and storing photoplethysmographic pulse curves. Using a photoplethysmograph, a small sample was collected for processing using a software package written in the MATLAB programming environment.

Clinical and vascular responses to propranolol and candesartan in migraine patients: A randomized controlled clinical trial

Background: Both propranolol and candesartan are prophylactic drugs for migraine, but with unknown mechanisms of action. The objectives of the present study were to investigate these drugs’ effects on arterial wall dynamics and the potential relation between their vascular and clinical effect. Methods: The study was based on data from a previously published randomized, placebo-controlled, triple-blinded, double crossover clinical trial comparing the prophylactic effects of candesartan and propranolol in 72 patients. Finapres noninvasive blood pressure curves were analyzed. On the descending limb of the pulse curve, a notch is produced by pulse wave reflection, and its relative height compared to the top of the curve (the notch ratio) was used as a marker of arterial wall stiffness. Results: Candesartan decreased the notch ratio from baseline ( p = 0.005), reflecting more compliant arteries and vasodilation, whereas propranolol increased the notch ratio ( p = 0.005), reflecting less compliant arteries and vasoconstriction. There was no difference in baseline notch ratio between clinical responders and nonresponders. Conclusion: The drugs are both efficient prophylactic medications, yet they have opposite effects on arterial wall dynamics. This suggests that drug effects other than those on arterial compliance must be responsible for their prophylactic effect in migraine.