Negative Tap Research Articles

SIMPLIFID LUNG ULTRASOUND IN DIAGNOSIS OF HEART FAILURE WITH PRESERVED EJECTION FRACTION IN ARTERIAL HYPERTENSION

Objective: About 30% of patients with heart failure (HF) have normal Ejection Fraction (HFpEF). Pulmonary congestion is useful marker of HFpEF. The aim of this study was to determine the efficacy of ultrasound in patients with DHF. Design and method: We studied 250 patients with Arterial Hypertension and III-IV NYHA class HF from which 70 patients had HFpEF (group 1) and 100 patients Left Ventricular Diastolic Dysfunction but without signs of HF (control, group 2). All participants undergone standard Echo Cardiography. Sonographic evaluation of a lung was done in horizontal or vertical positions of patient, from 10 points of thoracic wall (5 points from each side), which corresponded to the projection of lower, middle and upper lobes of a right lung and upper and lower lobes of left lung. Results: In patients with HFpEF we significantly often found multiple (3 or more) B-lines or Comet tail Phenomenon (CTPh), which was registered in 91.1%. In 40.0% of control group patients, we also registered B-lines, but the count of them was less than 3 lines per each registration point (the difference between control an HF groups was significant). The count of points from where the CTPh was registered was 6.8 in HFpEF gr. and 0.7 in control. The B-lines were registered from 3 or more points of thoracic wall in 82.86% of patients of I gr and only 5% in II gr participants. In HF groups CTPh was prominent and multiple while in the control group it was single and short lasting, like lightening. There was good correlation between the count of B-line registration points from the thoracic wall and the heart failure NYHA class (r=0.56), left ventricular systolic (r=0.40) and diastolic (r=0.32) diameters and negative MAPS and TAPS (r=-0.42 and 0.41 respectively). Conclusions: Thoracic US is a sensitive and accurate method for evaluation pulmonary congestion in patients with AH and HFpEF. The US sign of pulmonary congestion in HF are B-lines or Comet tail phenomenon, which is protracted, prominent, multiple and registered from larger area of thoracic wall (3 points or more).

Symplified pulmonary ultrasound in heart failure patients with preserved systolic function

Abstract Funding Acknowledgements Type of funding sources: None. Background About 1/3 of patients with heart failure (HF) have normal Ejection Fraction (HFpEF). Pulmonary congestion and Oedema is useful marker of HFpEF. The aim of this study was to determine the place of pulmonary ultrasound in patients with DHF. Methods We studied 250 patients with II-IV NYHA class HF from which 70 patients had HFpEF (I gr) and 100 patients Left Ventricular Diastolic Dysfunction but without signs of HF (control, II gr). All participants undergone standard EchoCG examination. Sonographic evaluation of a lung was done in horizontal or vertical positions of patient, from 10 points of thoracic wall (5 points from each side), which corresponded to the projection of lower, middle and upper lobes of a right lung and upper and lower lobes of left lung. Results In patients with HF we significantly often found multiple (3 or more) B-lines or "Comet tail Phenomenon" (CTPh), which was registered in 91.1%. In 40.0% of control group patients we also registered B-lines, but the count of them in was less than 3 lines per each registration point (the difference between control an HF groups was significant). The count of points from where the CTPh was registered was 6.8 in HFpEF gr. and 0.7 in control gr. The B-lines where registered from 3 or more points of thoracic wall in 82.86% of patients of I gr and only 5% in II gr participants. In HF groups CTPh was prominent, protracted and multiple while in the control group it was single and short lasting, like lightening. There was good correlation between the count of B-line registration points from the thoracic wall and the heart failure NYHA class (r=0.56), left ventricular systolic (r=0.40) and diastolic (r=0.32) diameters and negative MAPS and TAPS (r=-0.42 and 0.41 respectively). Conclusion Thoracic US is sensitive and accurate method for evaluation pulmonary congestion in patients with HFpEF. The US sign of pulmonary congestion in HF are B-lines or "Comet tail phenomenon", which is protracted, prominent, multiple and registered from larger area of thoracic wall (3 points or more).

INPH and parkinsonism: A positive shunt response with a negative tap test.

The aim of this study was to compare clinical and functional performances of idiopathic normal pressure hydrocephalus (INPH) patients with and without parkinsonism at the initial evaluation, 72 h after the cerebrospinal fluid tap test (CSF TT), and 6 months after ventriculoperitoneal shunt (VPS) surgery. This is an observational prospective study on patients with INPH who underwent VPS. Patients were classified into INPH with parkinsonism (INPH-P+) and without parkinsonism (INPH-P-). We used the time up and go (TUG) test, Tinetti Performance-Oriented Mobility Assessment (POMA) test, INPH grading scale (INHPGS), and modified Rankin scale (mRS) at baseline, 72 h after CSF TT, and 6 months after VPS surgery. A total of 64 patients with probable INPH were included, 12 patients with INPH-P+ and 52 controls with INPH-P-. Patients with INPH showed significant improvement in all clinical and neurological parameters after VPS including TUG, Tinetti POMA, INPHGS, and mRS (p < 0.001) with the exception of mRS where there was no significant change 72 h after CSF TT compared to baseline for patients with INPH (p = 0.182). Patients with INPH-P+ performed significantly worse than patients with INPH-P- on Tinetti POMA and mRS at baseline, at 72 h post-CSF TT, and at 6 months post-VPS with INPHGS being worst at 72 h post-CSF TT. There was no difference between patients with INPH-P+ and patients with INPH-P- for TUG at baseline (p = 0.270), at 72 h post-CSF TT (p = 0.487), and at 6 months post-VPS (p = 0.182). Patients with INPH-P+ did not show any change in any of the parameters at 72 h post-CSF TT compared to baseline; however, there was a trend toward improvement on TUG (p = 0.058), Tinetti gait (p = 0.062), and Tinetti total (p = 0.067). INPH-P+ significantly improved in all parameters 6 months post-VPS compared to baseline except for mRS (p = 0.124). Patients with INPH-P- significantly improved in all parameters at 72 h post-CSF TT and at 6 months post-VPS compared to baseline, respectively, except on mRS 72 h after CSF TT (p = 0.299). Patients with INPH and parkinsonism overall do worse than patients without parkinsonism. An unsatisfying response to the CSF tap test in INPH patients with parkinsonism should not be used as an exclusion criterion from VPS surgery since patients with and without parkinsonism showed significant improvement post-VPS.

The PUMCH Evaluation System of Idiopathic Normal Pressure Hydrocephalus and Clinical Practice

Differentiating idiopathic normal pressure hydrocephalus (iNPH) from other neurodegenerative diseases is challenging. Only a portion of the patients clinically suspected of iNPH would respond to surgical intervention. A cerebrospinal fluid (CSF) tap test is usually used to predict surgery outcomes and hence aid clinical decision-making, but the workup varies. We introduce the CSF tap test conducted at our center and examine its power by analyzing data from a series of iNPH cases that underwent shunt placement. We analyze common features in the past medical history of our patients and investigate whether they are related to the etiology of iNPH. Data from 20 patients who were positive in the tap tests preoperatively and received ventriculoperitoneal shunting (VPS) were retrospectively analyzed. Preoperative and postoperative performance data were analyzed. History of any underlying medical conditions was taken into consideration. Patients with negative tap test results of the same period were also followed up. We performed VPS placement in 20 NPH patients from October 2019 to February 2022. Of these, 90% exhibited improvement in at least 1 of the clinical triad, proving the predictive power of the Peking Union Medical College Hospital test workflow. The underlying conditions like hypertension, diabetes and insufficiency in cerebral blood supply were also found to be associated with the onset of NPH. Our evaluation system is a valid tool for NPH assessment and can guide clinical decision-making. Comorbidities should be taken into consideration as they contribute to the pathogenesis and progression of NPH. Better identification of potential iNPH patients will lower the burden exerted on the family and the aging society.

Evaluation of Surgical Treatment Effect on Idiopathic Normal Pressure Hydrocephalus

Background:We aimed to observe the long-term effectiveness and safety of the ventriculoperitoneal (VP) shunt in treating idiopathic normal pressure hydrocephalus (iNPH).MethodsA total of 65 patients with iNPH were retrospectively analyzed. All the patients were treated with VP shunt and the clinical efficacy was assessed using follow-up questionnaire, the Modified Rankin Scale (mRS), and iNPH grading scale (iNPHGS) after operation.ResultsThe mean mRS and iNPHGS scores were 1.18 ± 0.83 points and 2.98 ± 1.96 points, respectively, which were statistically significantly different from those before operation [(2.89 ± 0.92) points and (6.49 ± 2.30) points, respectively]. Besides, the patients were divided into the non-improvement group (n = 8, 12.3%), the improvement group (n = 16, 24.6%), and the marked improvement group (n = 41, 63.1%) based on the preoperative and postoperative mRS scores and the total effective rate of the VP shunt was 87.7%. Next, seven patients with negative cerebrospinal fluid tap test (tap test) received the active VP shunt and the score on walking disorder was 2.71 ± 0.76 points before operation and 1.86 ± 0.90 points after operation, showing a statistically significant difference. Moreover, 12 (18.4%) patients had complications after operation, among whom 5 (7.7%) patients manifested ameliorated symptoms after replacing shunt tube and receiving anti-infection treatment, but 3 (4.6%) patients showed no alleviation following pressure adjustment due to advanced age and multiple complications. Six (9.2%) cases of death were recorded during follow-up and only 1 (1.5%) case of sudden death occurred within 2 weeks after operation. In addition, it was found through more than 5 years of follow-up after operation that 12 out of the 23 (52.2%) patients had a good effect at 5 years after operation, 1 (4.3%) patient had been confined to bed due to advanced age and pulmonary infection, and 1 (4.3%) patient died of pulmonary infection and heart failure.ConclusionThe VP shunt is effective in treating iNPH and it results in a preferable long-term prognosis.

The Kuopio idiopathic normal pressure hydrocephalus protocol: initial outcome of 175 patients

BackgroundThe Kuopio University Hospital (KUH) idiopathic normal pressure hydrocephalus (iNPH) cerebrospinal fluid (CSF) shunting protocol is described together with the initial outcomes of 175 patients with probable iNPH treated according to this protocol from a defined population. Our secondary aim was to display the variety of differential diagnoses referred to the KUH iNPH outpatient clinic from 2010 until 2017.MethodsPatients were divided into four groups according to the prognostic tests: tap test (positive or negative) and infusion test (positive or negative). The short-term outcome was compared between groups. The 3-month outcome following shunt surgery was assessed by measuring gait speed improvement, using a 12-point iNPH grading scale (iNPHGS) and the 15D instrument.ResultsFrom 341 patients suspected of iNPH, 88 patients were excluded from further research mostly due to deviation from the protocol’s gait assessment guidelines. Hence 253 patients with suspected iNPH were included in the study, 177/253 (70%) of whom were treated with a CSF shunt. A favorable clinical outcome following surgery was observed in 79–93% of patients depending on the prognostic group. A moderate association (Cramer’s V = 0.32) was found between the gait speed improvement rate and the prognostic group (X2, p = 0.003). Patients with a positive tap test had the highest gait speed improvement rate (75%). In addition, an improvement in walking speed was observed in 4/11 patients who had both a negative tap test and a negative infusion test. Other outcome measures did not differ between the prognostic groups. Conditions other than iNPH were found in 25% of the patients referred to iNPH outpatient clinic, with the most prevalent being Alzheimer’s disease.ConclusionsOur results emphasize the importance of a systematic diagnostic and prognostic workup especially in cases with an atypical presentation of iNPH. Additional diagnostic testing may be required, but should not delay adequate care. Active surgical treatment is recommended in patients with a high clinical probability of iNPH. Other neurological conditions contributed to most of the non iNPH diagnoses.

Advanced Adaptive Photonic RF Filters with 80 Taps Based on an Integrated Optical Micro-Comb Source

We demonstrate a photonic radio frequency (RF) transversal filter based on an integrated optical micro-comb source featuring a record low free spectral range of 49 GHz yielding 80 micro-comb lines across the C-band. This record-high number of taps, or wavelengths for the transversal filter results in significantly increased performance including a QRF factor more than four times higher than previous results. Further, by employing both positive and negative taps, an improved out-of-band rejection of up to 48.9 dB is demonstrated using Gaussian apodization, together with a tunable centre frequency covering the RF spectra range, with a widely tunable 3-dB bandwidth and versatile dynamically adjustable filter shapes. Our experimental results match well with theory, showing that our transversal filter is a competitive solution to implement advanced adaptive RF filters with broad operational bandwidths, high frequency selectivity, high reconfigurability, and potentially reduced cost and footprint. This approach is promising for applications in modern radar and communications systems.

A novel approach to photonic generation of periodic triangular radio frequency waveforms

A novel approach to photonic generation of triangular radio frequency waveforms with a tunable repetition rate is proposed and analyzed. In the proposed system, a continuous-wave light is modulated by a reference microwave signal through a polarization modulator, and then its output optical sidebands are manipulated by a microwave photonic filter with a negative tap. By properly adjusting the system parameters, full-duty-cycle triangular radio frequency waveforms can be generated after optical-to-electrical conversion, and its repetition rate (frequency) can be tuned in a wide range. A model describing the proposed system is derived, which is verified via computer simulations.

Multiband-UWB Signals Generation Based on Incoherent Microwave Photonic Filters

A structure for multiband-UWB waveforms generation is proposed using an N tap microwave photonic filter with positive and negative taps. The system is based on phase inversion in electro-optical modulators and the sliced broadband source optical signal by means of a structure of AWGs, which permits us to obtain a high number of taps. System performance is experimentally shown by the generation of a uniform waveform. Capabilities as reconfigurability and frequency tuning have been also experimentally demonstrated. The flexibility of the system allows us to obtain multiband UWB waveforms, which fulfill the FCC spectral requirements.

Designing PMF with negative tap coefficient

DIRECT global optimization algorithm is innovatively used in design of PMF. Tap coefficient is attained by achieving DIRECT algorithm with C language and Matlab language is employed to simulate the amplitude response of filters. We have designed PMF (photonic microwave filter) with negative tap coefficient and then optimize the design. The minimum shape factor is as low as 1.3180. The results show that the algorithm is highly efficient in designing filter and can produce necessary passband and stopband response characteristics. In the meantime, transition band becomes steeper in the process of further optimization and the shape factor is closer to 1.

Switchable and tunable microwave photonic filter based on reflective semiconductor optical amplifier

ABSTRACTA microwave photonic filter, which can be switched between a high‐Q bandpass filter and a notch filter, is proposed and experimentally demonstrated. It is based on a recirculating delay line loop with a reflective semiconductor optical amplifier, and negative taps are generated employing wavelength conversion. The filter can be also tuned by adjusting an optical variable delay line. © 2014 Wiley Periodicals, Inc. Microwave Opt Technol Lett 56:198–201, 2014

A Photonic Microwave Filter Based on an Asymmetric Silicon Mach-Zehnder Modulator

A new approach for implementing an integrable photonic microwave filter based on exploiting the asymmetry of a CMOS-compatible silicon Mach-Zehnder modulator is demonstrated. The strong dependence of the modulator response with wavelength is exploited for achieving positive and negative taps and, therefore, a fully reconfigurable filter, without the complexity of previous approaches. Two filter responses with two and three taps are experimentally demonstrated, showing the proof-of-principle for frequencies up to 10 GHz and thus going one step further toward a full integration of the complete filter device in the CMOS-compatible silicon photonics platform.

Designing PMF with Negative Tap Coefficient Based on FBG Delay Line

Abstract DIRECT global optimization algorithm is innovatively used in design of PMF. Tap coefficient is attained by achieving DIRECT algorithm with C language and Matlab language is employed to simulate the amplitude response of filters. We have designed PMF (photonic microwave filter) with negative tap coefficient and then optimize the design. The minimum shape factor is as low as 1.3180. The results show that the algorithm is highly efficient in designing filter and can produce necessary passband and stopband response characteristics.

Phase-Modulation-Based Microwave Photonic Bandpass Filter Using a Programmable-Induced Frequency Response

A new optical phase modulator microwave photonic filter that can realize a flat-top radio frequency (RF) bandpass filter with multiple taps and bipolar coefficients is presented. It is based on a spatial light modulator that induces a programmable phase-modulation to intensity-modulation frequency response in combination with an RF phase-modulated multiwavelength signal. It enables the realization of negative taps, and opens up regions for operating the bandpass filter to extremely high frequencies. Experimental results demonstrate a multiple tap flat-top microwave filter at 18.5 GHz. To our best knowledge, this is the first phase modulator-based microwave photonic structure that exhibits multiple taps together with an arbitrary flat-top response.

Tunable negative-tap photonic microwave filter based on a cladding-mode coupler and an optically injected laser of large detuning

A tunable negative-tap photonic microwave filter using a cladding-mode coupler together with optical injection locking of large wavelength detuning is demonstrated. Continuous and precise tunability of the filter is realized by physically sliding a pair of bare fibers inside the cladding-mode coupler. Signal inversion for the negative tap is achieved by optical injection locking of a single-mode semiconductor laser. To couple light into and out of the cladding-mode coupler, a pair of matching long-period fiber gratings is employed. The large bandwidth of the gratings requires injection locking of an exceptionally large wavelength detuning that has never been demonstrated before. Experimentally, injection locking with wavelength detuning as large as 27 nm was achieved, which corresponded to locking the 36-th side mode. Microwave filtering with a free-spectral range tunable from 88.6 MHz to 1.57 GHz and a notch depth larger than 35 dB was obtained.

Coherence-Free Equivalent Negative Tap Microwave Photonic Notch Filter Based on Delayed Self-Wavelength Conversion

A new coherence-free single-wavelength microwave photonic notch filter, which is widely tuneable, and which is compatible to be inserted in a conventional fiber-optic link, is presented. It is based on self-wavelength cross gain modulation in a semiconductor optical amplifier placed at an off-centre location in a Sagnac loop. The structure can realize a high free spectral-range negative tap notch filter response, and does not have any coherent interference and phase-noise limitations. Moreover, it enables widely tunable notch filtering to be simply realized. Experimental results are presented which demonstrate a large continuous filter tuning range of an octave, robust operation with a narrow linewidth source, and wide passband notch filtering operations.

All-Optical Microwave Filter With High Frequency Selectivity Based on Semiconductor Optical Amplifier and Optical Filter

We propose and experimentally demonstrate a novel all-optical microwave filter with high frequency selectivity. It is based on a recirculating delay line (RDL) loop in which a semiconductor optical amplifier (SOA) is followed by a tunable narrowband optical filter and a 1 × 2 10:90 optical coupler. Converted signal used as a negative tap is generated through wavelength conversion employing the cross-gain modulation (XGM) of the amplified spontaneous emission (ASE) spectrum of the SOA. The converted signal circulating in the RDL loop can realize a high quality factor (Q) response after photo-detection. The 1 × 2 10:90 coupler is employed to extract 10% optical power from the loop as output. A frequency response with a high Q factor of 543, a rejection ratio of 40 dB and a shape factor of 15.4 is experimentally demonstrated.

Polarity- and Shape-Switchable UWB Pulse Generation Based on a Photonic Microwave Delay-Line Filter With a Negative Tap Coefficient

<para xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> A novel and simple scheme to implement a two- or three-tap photonic microwave filter with one negative coefficient for polarity- and shape-switchable ultrawideband (UWB) pulse generation is proposed and demonstrated. The entire system can be reconfigured as a two- or three-tap microwave delay-line filter with one negative coefficient realized by operating a balanced photodetector (BPD) as a single photodetector or a BPD for the generation of UWB monocycle or doublet pulses. The polarity of the generated UWB pulses can be switched by tuning the transmission axis of the arbitrary wave plate. The proposed scheme is experimentally demonstrated. Gaussian monocycle and doublet pulses with fractional bandwidths of about 174% and 141% are generated. </para>

A tunable single-passband microwave photonic filter with positive and negative taps using a fiber Mach–Zehnder interferometer and phase modulation

In this paper, a tunable single-passband microwave photonic filter with positive and negative taps based on phase modulation and a fiber Mach–Zehnder interferometer (FMZI)) is presented, theoretically analyzed and experimentally demonstrated. The FMZI as the slicing filter results in a single-bandpass characteristic for the presented filter, and by using phase modulation, a number of negative taps are generated, thus making the baseband resonance suppressed, which is desirable for microwave photonic filter's application. The wavelength spacing of the FMZI can be tuned by employing an optical variable delay line, making the present filter continuously tunable. A tunable single-passband microwave photonic filter without baseband resonance is achieved in the experiment. The present filter shows an extinction ratio of up to ∼20 dB and good tuning linearity.

A simple microwave photonic notch filter based on a semiconductor optical amplifier

A novel microwave photonic notch filter structure is proposed and experimentally demonstrated. The structure is based on a recirculating delay line loop consisting of an optical variable delay line, a semiconductor optical amplifier (SOA) and a tunable narrowband optical filter. Negative tap is generated using wavelength conversion based on cross-gain modulation of an amplified spontaneous emission spectrum in the SOA. A narrow bandpass response with negative coefficients and a broadband all-pass response are combined to achieve a narrow notch response with flat passband which can eliminate interference with minimal impact on the expected signal. Experimental results show good agreement with theoretical analysis.