Monophasic Waveforms Research Articles

Pulse Wave Doppler Ultrasound in Unmasking of Venous Obstructions Highlighting Diagnostic Utility and Clinical Implications.

Venous obstructions and thrombosis can present diagnostic challenges due to their varied presentations and potential for significant complications if untreated. Pulse wave doppler ultrasound via identification of damping or loss of cardiac pulsatility and/ or respiratory phasicity of venous waveforms serves as a practical, noninvasive, fast, and efficient diagnostic tool for identifying venous obstructions in the presence of compressible veins beyond the point of evaluation.We present two cases demonstrating the effectiveness of pulse wave doppler ultrasound in identifying significant and life-threatening venous obstructions. The first case involves a 68-year-old male with an incidental finding of a compressible left subclavian vein showing a monophasic waveform. Further investigation revealed significant compression of the left brachiocephalic vein by an aortic arch aneurysm. The second case describes a 65-year-old male with a compressible right femoral vein but a monophasic waveform, leading to the discovery of extensive thrombosis from the iliac veins to the inferior vena cava. This series proposes to always assess cardiac pulsatility and respiratory phasicity during doppler ultrasound procedure such as thyroid ultrasounds, deep vein thrombosis (DVT) evaluations, and pre-central vein catheterizations for identifying any venous obstructions, whether they are intrinsic or extrinsic, and for reducing the risk of thromboembolic complications.

Arrhythmogenicity of monophasic and biphasic PFA waveforms in a porcine model.

The potential risk of inducing ventricular arrhythmias was explored by employing pulsed field ablation (PFA) through the administration of both monophasic and biphasic waveform deliveries. PFA was applied to specific locations in the right ventricle (RV, n = 5 sites) in swine (n = 2), utilizing identical settings with consistent amplitude, pulse width, and a number of pulses for both monophasic and biphasic waveforms. PFA deliveries were precisely timed in 10-ms intervals across the entire T wave. Using monophasic waveforms, ventricular fibrillation (VF) was induced 7/7 times when PFA pulses were delivered during the T wave. Biphasic waveforms resulted in no ventricular arrhythmias when PFA was delivered across the entire duration of T wave. Our findings indicate that VF can be consistently induced with monophasic pulse waveforms, but not with biphasic pulse waveforms in a porcine model.

Combined Color-Doppler Flow and Angio Planewave UltraSensitive™ Imaging for Analysis of Hemodynamic Characteristics of Normal Upper Limb Arteries

BackgroundTo evaluate the hemodynamic characteristics of normal upper extremity arteries from the brachial artery to the fingertip arterioles.MethodsWe analyzed the characteristics and changes in the regularities of ultrasonic parameters in the upper extremity arteries of 104 healthy volunteers using color Doppler flow imaging and Angio Planewave UltraSensitive™ imaging. The measured ultrasonic parameters included the vessel diameter, blood-flow spectrum waveform, peak systolic velocity, end-diastolic velocity, resistance index, pulsatility index, ratio of PSV to EDV, blood-flow volume, along with systolic acceleration of each BA, radial artery, superficial palmar arch artery, palmar proper digital artery, and third-grade artery arch of the fingernail bed.ResultsFrom BA to FN3AA, the diameter, PSV, RI, S/D, VFlow, and slope of the artery significantly decreased (P < 0.001), and size of the parameters significantly correlated with the anatomic position of the arteries. The blood-flow spectrum gradually changed from various waveforms to fixed monophasic waves. There was a linear relationship between the distribution of monophasic waveforms and arterial groups (R = -0.453; P < 0.001). When the blood-flow spectrum of BA and RA showed a monophasic waveform, their branch arteries showed the same. The waveforms of PPDA and FN3AA were also monophasic.ConclusionRegular changes in the blood-flow spectrum waveform and hemodynamic parameters are related to the anatomic position of the upper limb arteries. CDFI combined with Angio PLUS accurately and systematically evaluates the hemodynamic characteristics of the upper extremity arteries.

Analysis of thermal effects from pulsed field ablation

Abstract Background Pulsed field ablation (PFA) has been described as non-thermal, but abundant data exist in oncology applications [1-3], and growing data are emerging in cardiology [4], highlighting that thermal effects are in fact present with PFA. The particular parameters (such as voltage, pulse gap, pulse number) that most influence the development of thermal energy during PFA are less clear. Purpose We sought to evaluate the thermal effects arising from pulsed field ablation of myocardial and esophageal tissue over a range of typical peak voltage operating conditions. Methods Using a three-dimensional computer model of the left atrium and esophagus, we quantified the thermal effects from PFA applications over a range of peak voltage operating conditions (1 kV, 1.5 kV, and 2 kV). Bipolar electroporation was simulated using one electrode as the anode and the other as a grounded cathode. Far-field and symmetry boundaries were set as electrically insulating. A monophasic waveform with a pulse duration of 100 µs and pause between pulses of 1 s was applied for a total of 50 pulses in a single train. Myocardial thickness was 1.5 mm, esophageal thickness was 2 mm, and the pericardial fat layer was varied between 0.3 and 0.75 mm. Results Minimal temperature rise in the esophagus was seen with 1 kV pulses (corresponding to 13.4 J input). With 1.5 kV and 2 kV peak voltages (corresponding to 32.3 J and 66.2 J), temperature elevations reaching 46.3 °C and &amp;gt; 62 °C were seen, respectively. These elevations occurred after only a single pulse train of 50 pulses, implying that further elevations in temperature would be seen with subsequent applications. Conclusions Thermal effects from PFA depend on total energy deposited, of which peak voltage is an important component. Current commercially available systems appear to have the potential to induce collateral thermal injury, particularly with a thin pericardial fat layer, and with repeated applications of pulsed field energy.

Design of Dual-Configuration Dual-Mode Stimulator in Low-Voltage CMOS Process for Neuro-Modulation.

A dual-configuration dual-mode stimulator for neuro-modulation is proposed and designed. All the electrical stimulation patterns that frequently used for neuro-modulation can be generated by the proposed stimulator chip. Dual-configuration represents the bipolar or monopolar structure, meanwhile dual-mode stands for the current or voltage output. No matter what stimulation circumstance is chosen, biphasic or monophasic waveforms can be fully supported by the proposed stimulator chip. The stimulator chip with 4 stimulation channels has been fabricated in 0.18-μm 1.8-V/3.3-V low-voltage CMOS process with common grounded p-type substrate, which is suitable for SoC integration. The design has conquered the overstress and reliability issues in the low-voltage transistors under the negative voltage power domain. Each channel in the stimulator chip only occupies the silicon area of 0.052 mm2, and the maximum output level of stimulus amplitude is up to ±3.6 mA and ±3.6 V. With the built-in discharge function, bio-safety concern of unbalanced charge in neuro-stimulation can be dealt with properly. Moreover, the proposed stimulator chip has been applied on both imitation measurement and in-vivo animal test successfully.

Duplex Studies of Amplatzer Vascular Plug II as a Foreign Body: Detection and Localization Following Migration From the Heart to the Extremities

This case report illustrates the most unique feature of ultrasound that distinguishes it from other imaging modalities: hemodynamic analysis of blood flow by spectral Doppler waveforms. Duplex evaluation of the patient presented showed the different resulting hemodynamic impacts of the Amplatzer Vascular Plug II (AVP II), an embolic device, as a foreign body in the upper extremity versus the lower extremity: monophasic Doppler waveforms in the upper extremity distal to the location of the AVP II versus multiphasic Doppler waveforms in the comparable lower extremity distal location. This hemodynamic analysis illustrates the different impacts of the migrated AVP II as a foreign body. It is possible that paroxysmal atrial fibrillation could have been a cause of AVP II migration in this case, since there was no surgical manipulation following placement, but that would be a topic for further investigation.

Versatile electrical stimulator for cardiac tissue engineering-Investigation of charge-balanced monophasic and biphasic electrical stimulations.

The application of biomimetic physical stimuli replicating the in vivo dynamic microenvironment is crucial for the in vitro development of functional cardiac tissues. In particular, pulsed electrical stimulation (ES) has been shown to improve the functional properties of in vitro cultured cardiomyocytes. However, commercially available electrical stimulators are expensive and cumbersome devices while customized solutions often allow limited parameter tunability, constraining the investigation of different ES protocols. The goal of this study was to develop a versatile compact electrical stimulator (ELETTRA) for biomimetic cardiac tissue engineering approaches, designed for delivering controlled parallelizable ES at a competitive cost. ELETTRA is based on an open-source micro-controller running custom software and is combinable with different cell/tissue culture set-ups, allowing simultaneously testing different ES patterns on multiple samples. In particular, customized culture chambers were appositely designed and manufactured for investigating the influence of monophasic and biphasic pulsed ES on cardiac cell monolayers. Finite element analysis was performed for characterizing the spatial distributions of the electrical field and the current density within the culture chamber. Performance tests confirmed the accuracy, compliance, and reliability of the ES parameters delivered by ELETTRA. Biological tests were performed on neonatal rat cardiac cells, electrically stimulated for 4days, by comparing, for the first time, the monophasic waveform (electric field = 5V/cm) to biphasic waveforms by matching either the absolute value of the electric field variation (biphasic ES at ±2.5V/cm) or the total delivered charge (biphasic ES at ±5V/cm). Findings suggested that monophasic ES at 5V/cm and, particularly, charge-balanced biphasic ES at ±5V/cm were effective in enhancing electrical functionality of stimulated cardiac cells and in promoting synchronous contraction.

New Approach to Measuring the Ankle and Toe Brachial Indices as New Markers for Early Detection of Lower Extremity Peripheral Artery Disease

Background: Lower extremity Peripheral artery disease (PAD) is caused by atherosclerosis, or Plaque buildup, that reduces the blood flow to the legs and feet. PAD affects approximately 230 million adults worldwide and is associated with an increased risk of coronary heart disease, stroke, and leg amputation. The first-line method for diagnosis of PAD is the Ankle Brachial Index (ABI), which is the ratio of ankle to brachial higher systolic pressure measured in ankles and arms. The Toe Brachial Index (TBI), which is the ratio of the toe systolic pressure to brachial higher systolic pressure measured in both arms, is considered to be an alternative to the ABI in screening for PAD. The ABI and TBI are measured on the right and left side, and the lower of these numbers is the patient’s overall ABI and TBI. Clinical studies and meta-analysis reviews have shown that the conventional ABI measurement, which uses a cuff, and handheld sphygmomanometer and continuous-wave Doppler tracings, provides an acceptable-to-high specificity level but low sensitivity when compared with vascular color Doppler ultrasound, and/or angiography methods. Another study has shown that the TBI measurement has greater sensitivity but lower specificity than the ABI when compared with vascular color Doppler ultrasound diagnostic based on waveforms. The aim of this clinical study was to evaluate the specificity and sensitivity of the VasoPad System comparing its results to the vascular color doppler ultrasound waveforms. Materials and Methods: The VasoPad System is an automated device using the pulse wave method to measure the arms and ankles dorsalis and tibial posterior artery blood pressures, the photoplethysmography second derivative (PTGSD) to estimate the toe systolic pressure, a patented photoplethysmography (PTG) index marker and volume plethysmography via cuffs during deflation. Vascular Color Doppler ultrasound can diagnose stenosis through the direct visualization of atherosclerosis or plaques and through waveform analysis. The vascular color Doppler ultrasound provides 3 waveform types. The type 1, triphasic waveform is normal blood flow and no atherosclerosis or plaque, the type 2, diphasic waveform is seen when there are atherosclerosis plaques, but normal blood flow, and the type 3, monophasic waveform reflects stenosis with diameter reduction > 50%. Results: The sum of the overall ABI and TBI VasoPad values, called Sum of Brachial Indices (SBI), gave a specificity of 88.89% and sensitivity of 100% for detecting vascular color Doppler ultrasound biphasic and monophasic waveforms versus triphasic waveforms with a cutoff ≤ 1.36 (P 50% (Doppler monophasic waveforms) but also early stage of atherosclerosis plaque of the lower extremities (Doppler biphasic waveforms). The VasoPad method provided a remarkable sensitivity of 100% and a specificity level similar to those of the conventional ABI test method compared with the vascular color Doppler ultrasound. In addition to being useful to screen and detect PAD, the VasoPad offers early detection of lower extremity atherosclerosis, with normal blood flow (Doppler biphasic waveforms), which could provide greater treatment options and thus reduce the overall number of lower extremity complications.

Techniques improving electrical cardioversion success for patients with atrial fibrillation: a systematic review and meta-analysis.

Electrical cardioversion is commonly used to restore sinus rhythm in patients with atrial fibrillation (AF), but procedural technique and clinical success vary. We sought to identify techniques associated with electrical cardioversion success for AF patients. We searched MEDLINE, EMBASE, CENTRAL, and the grey literature from inception to October 2022. We abstracted data on initial and cumulative cardioversion success. We pooled data using random-effects models. From 15 207 citations, we identified 45 randomized trials and 16 observational studies. In randomized trials, biphasic when compared with monophasic waveforms resulted in higher rates of initial [16 trials, risk ratio (RR) 1.71, 95% CI 1.29-2.28] and cumulative success (18 trials, RR 1.10, 95% CI 1.04-1.16). Fixed, high-energy (≥200 J) shocks when compared with escalating energy resulted in a higher rate of initial success (four trials, RR 1.62, 95% CI 1.33-1.98). Manual pressure when compared with no pressure resulted in higher rates of initial (two trials, RR 2.19, 95% CI 1.21-3.95) and cumulative success (two trials, RR 1.19, 95% CI 1.06-1.34). Cardioversion success did not differ significantly for other interventions, including: antero-apical/lateral vs. antero-posterior positioned pads (initial: 11 trials, RR 1.16, 95% CI 0.97-1.39; cumulative: 14 trials, RR 1.01, 95% CI 0.96-1.06); rectilinear/pulsed biphasic vs. biphasic truncated exponential waveform (initial: four trials, RR 1.11, 95% CI 0.91-1.34; cumulative: four trials, RR 0.98, 95% CI 0.89-1.08) and cathodal vs. anodal configuration (cumulative: two trials, RR 0.99, 95% CI 0.92-1.07). Biphasic waveforms, high-energy shocks, and manual pressure increase the success of electrical cardioversion for AF. Other interventions, especially pad positioning, require further study.

Open aortic reconstruction for middle aortic syndrome associated with right renal artery poststenotic aneurysm.

A 24-year-old woman was diagnosed with high blood pressure when she was 14 years old. During the last 4 years, she has experienced progressive symptoms of lower extremity weakness and fatigue and cannot do any heavy exercise. On physical examination, she presented with absent bilateral femoral pulses. Ultrasound ankle-brachial index (ABI) with Doppler of the lower extremities showed diffuse monophasic waveforms and diminished ABI bilaterally (right ABI = 0.68, left ABI = 0.65). A computed tomography angiography confirmed a severe narrowing of the aorta just distal to the origin of the left renal artery consistent with the diagnosis of middle aortic syndrome.

Anterior-Posterior versus anterior-lateral electrodes position for electrical cardioversion of atrial fibrillation: A meta-analysis of randomized controlled trials.

BackgroundThe optimal electrodes position for elective direct current (DC) cardioversion of patients with atrial fibrillation (AF) remains uncertain.MethodsAn electronic search of MEDLINE, EMBASE and COCHRANE databases was performed through March 2022 for randomized trials that examined the outcomes of anterior-posterior (AP) versus anterior-lateral (AL) electrodes position during cardioversion of (AF). The main outcome was the success rate of cardioversion. Data were pooled using random effects model.ResultsThe final analysis included 10 RCTs with a total of 1677 patients. There was no difference in the rate of successful cardioversion between the AP versus AL groups (86.6 vs 87.9 %; RR 1.00; 95 % Confidence Interval (CI) 0.95 to 1.06). Subgroup analysis by the shock waveform showed no significant interaction between monophasic and biphasic waveforms (Pintercation = 0.23). meta-regression analyses showed no effect modification of primary outcome according to body mass index (p = 0.15), left atrial diameter (p = 0.64), valvular heart disease (p = 0.34), lone AF (p = 0.58), or the duration of AF (p = 0.70). There was no significant difference between the AP and AL electrode position groups in successful cardioversion at low energy (RR 0.94; 95 % CI 0.74 to 1.19), the number of the delivered shocks (standardized mean difference [SMD] −0.03; 95 % CI −0.32 to 0.26) or the mean energy of the delivered shocks (SMD −0.11 and 95 % CI −0.30 to 0.07). There was lower transthoracic impedance with AP versus AL electrode position (SMD −0.28; 95 %CI −0.47 to −0.10).ConclusionMeta-analysis of randomized data showed no difference between AP and AL electrode positions in the success rate of DC cardioversion of AF. Either AP or AL electrode positions should be acceptable approaches for elective DC cardioversion of patients with AF.

Parametric Study of Pulsed Field Ablation With Biphasic Waveforms in an In Vivo Heart Model: The Role of Frequency.

Pulsed field ablation (PFA) is a novel nonthermal cardiac ablation technology based on irreversible electroporation. Unfortunately, the characteristics of the electric field waveforms used in clinical and experimental PFA are not typically reported. This study examines the effect of the frequency of biphasic waveforms and compares biphasic to monophasic waveforms. A total of 29 Sprague-Dawley rats were treated with PFA using an epicardial monopolar electrode. Biphasic waveforms with three different frequencies, 90, 260, and 450 kHz (10 bursts of 100 µs duration at 500 V or 800 V) and monophasic waveforms (10 pulses of 100 µs duration at 500 V) were studied. Collateral neuromuscular stimulation and temperature increase in the point of application were directly measured. Lesion formation was assessed 3 weeks after treatment by histopathologic analysis. Computer simulations were used to estimate the electric field lethal threshold for each condition. A previous in vitro study was performed to draw a complete characterization of the studied dependencies. Morphometric analysis demonstrated a significant association between chronic lesion size and waveform characteristics. For the same voltage level, monophasic waveforms yielded the largest lesions compared with any of the biphasic protocols (P<0.05). Increasing PFA frequency was associated with reduced neuromuscular stimulation but also with reduced ablation efficacy. Maximum absolute temperature increase recorded along a complete treatment was 3 °C. Vascular structures inside the lesions were preserved for all conditions. Computer simulation-based analysis showed that waveform frequency had a graded effect on the lethal electric field threshold, with threshold of 600 V/cm for monophasic waveforms versus 2000 V/cm for biphasic waveforms with a frequency of 450 kHz. Frequency is a major determinant of efficacy in biphasic PFA. Our results highlight the critical need of disclosing waveform characteristics when reporting the results of different PFA systems.

B-mode and color Doppler ultrasonography of normal external jugular vein in donkeys (Equus asinus)

BackgroundAlthough the jugular vein is a major important blood vessel in equine, the literature lacks this vessel's normal B-mode and Doppler ultrasonographic examinations in donkeys. Therefore, this study aimed to determine the reference ranges of B-mode and Doppler ultrasonographic indices of jugular veins in healthy adult donkeys (Equus asinus) and the possible effect of examination side (left and right), gender, and body condition on the ultrasonographic measurements of this vessel. B-mode and Doppler ultrasound imaging of the external jugular vein was conducted on 20 adult healthy donkeys of both sexes.ResultsIn all donkeys, the jugular vein was 4.01 to 8.1 mm from the body surface. The longitudinal and transverse venous diameters ranged from 3.94 to 10.5 mm and from 0.88 to 1.9 cm, respectively. Moreover, the vein areas varied from 0.61 to 2.83 cm2. The reference values of superficial and deep wall thickness (SWT and DWT) were 0.56 ± 0.2 and 0.6 ± 0.13 mm, respectively. The blood velocity, blood follow rate, and congestion index of the external jugular vein can be expected in adult healthy donkeys as a range value from 8.4 to 13.5 cm/sec, from 0.33 to 1.78 ml/min, and from 0.06 to 0.27 cm.sec, respectively. Generally, the vein showed laminar monophasic waveforms. The examination side and gender have no significant effect on the ultrasound measurements of the vein (P > 0.05). Donkeys with a body condition score (BCS) ≥ 3 revealed increases in the depth of the vein (P < 0.05).ConclusionsThe results of this study can be used as reference values and provide a basis for comparison when evaluating donkeys with diseases that affect blood flow in the external jugular vein.

Duplex Analysis of Cannulated Vessels in Peripheral Veno-Arterial Extracorporeal Membrane Oxygenation.

Background and objectives: Veno-arterial extracorporeal membrane oxygenation (V-A ECMO) cannulas have major repercussions on vascular hemodynamics that can potentially lead to limb ischemia. Duplex ultrasound enables the non-invasive analysis of vascular hemodynamics. This study aims to describe the duplex parameters of the femoral vessels during V-A ECMO support, investigate differences between cannulated and non-cannulated vessels, and analyze the variations in the case of limb ischemia and intra-aortic balloon pumps (IABPs). Methods: Nineteen adults (≥18 years), supported with femoro-femoral V-A ECMO, underwent a duplex analysis of the superficial femoral arteries (SFAs) and veins (FVs). Measured parameters included flow velocities, waveforms, and vessel diameters. Results: 89% of patients had a distal perfusion cannula during duplex analysis and 21% of patients developed limb ischemia. The mean peak systolic flow velocity (PSV) and end-diastolic flow velocity (EDV) of the SFAs on the cannulated side were, respectively, 42.4 and 21.4 cm/s. The SFAs on the non-cannulated side showed a mean PSV and EDV of 87.4 and 19.6 cm/s. All SFAs on the cannulated side had monophasic waveforms, whereas 63% of the SFAs on the non-cannulated side had a multiphasic waveform. Continuous/decreased waveforms were seen in 79% of the FVs on the cannulated side and 61% of the waveforms of the contralateral veins were respirophasic. The mean diameter of the FVs on the cannulated side, in patients who developed limb ischemia, was larger compared to the FVs on the non-cannulated side with a ratio of 1.41 ± 0.12. The group without limb ischemia had a smaller ratio of 1.03 ± 0.25. Conclusions: Femoral cannulas influence flow velocities in the cannulated vessels during V-A ECMO and major waveforms alternations can be seen in all SFAs on the cannulated side and most FVs on the cannulated side. Our data suggest possible venous stasis in the FV on the cannulated side, especially in patients suffering from limb ischemia.

MO784: Racial Differences in Vascular Access for Dialysis—Why are Black Patients Prone to Fewer Vascular Access Options?

Abstract BACKGROUND AND AIMS Vascular access (VA) represents a major component for dialysis outcomes, like mortality, morbidity, hospital admission and economical costs. A well-described phenomenon, is the racial disparity concerning vascular access care, as black patients are associated with fewer fistulae construction and a higher rate of access dysfunction. Different clinical and socio-economical factors have been pointed to explain this association, however concrete vascular data has not been explored. We analyse the anatomical and haemodynamic data, obtained by preoperative ultrasound mapping, in order to prove whether vascular differences explain racial disparities. METHOD Retrospective study that included patients referred for the first VA construction and evaluated through ultrasound vascular mapping. Sociodemographic, clinical, vascular data (arterial diameter and peak systolic velocity, PSV; presence of mono or biphasic flow and significant calcification) and vascular mapping conclusions (type of possible VA) were collected. For racial comparison of collected data, two groups were created, blacks and non-blacks. Appropriate tests for continuous and categorical variables were applied, recurring to SPSS v21.0. Unadjusted and adjusted multivariate logistic regression models were fitted to determine if races are associated with clinical or vascular features. RESULTS A total of 102 patients were included. The mean age was 67 ± 16 years, 54% were male and 14% were black and 36% were already on dialysis or kidney transplantation. Hypertension, diabetes mellitus, cardiac insufficiency, coronary disease, peripheral arterial disease and obesity were noted at 94, 48, 34, 25, 17 and 35%, respectively. Among these, non-black patients presented a higher risk for cardiac insufficiency (P = 0.025). Concerning arterial evaluation: 16% presented upper brachial bifurcation in one or both arms; 31% presented monophasic or biphasic waveform in any of the principle arterial vessels and 26% presented significant arterial calcification. These qualitative and the radial and brachial diameters and PSV showed no differences between black and non-black patients. Finally, the feasibility for radiocephalic or brachiocephalic was noted in 67%, whilst in 33% only brachiobasilic or prosthetic fistulae was possible. Black race was found as a predictor for these differences, accounting for a higher probability of scarce options (P = 0.042), the effect that was reinforced when evaluating prosthetic fistulae as the only option (P = 0.027); both conclusions persisted in a multivariate analysis including cardiac insufficiency. CONCLUSION Black patients are associated with scarce VA options, such as brachiobasilic or prosthetic fistulas. No substantial differences were identified in arterial, clinical and sociodemographic features, remaining the venous system as the most disabling component in VA construction. The underlying biology is an area to explore, for academic and practical purposes. A larger sample should be collected to confirm these findings and establish if peripheral venous features underlie racial differences related to VA care in haemodialysis.

The sonographer's use of spectral Doppler in the common femoral vein for the assessment of iliac vein obstructions: A retrospective audit

AbstractIntroductionIliac vein obstructions account for 2%–3% of all lower limb deep vein thromboses (DVT). Delayed diagnosis can lead to a higher risk of limb ischemia in the acute setting and post‐thrombotic syndrome in the chronic setting. The purpose of this audit was to determine whether sonographers were taking and interpreting waveforms correctly at the common femoral vein (CFV).MethodsA retrospective audit was performed of all the DVT patients (n = 375) over the course of 3 months. Changes in phasicity during Valsalva, respiration or augmentation of the spectral waveform at the CFV was recorded.ResultsWithin the cohort group of 375 examinations assessed. Only 277 (74%) patients had spectral traces taken at the level of the CFV. 29 (10%) patients had persistent monophasic waveforms that did not change significantly when a Valsalva manoeuvre was performed, eight patients (2%) had confirmed iliofemoral vein obstruction with either ultrasound or computed tomography venogram.ConclusionThe audit results show that spectral traces at the CFV are not always being taken or assessed effectively in clinical practice for various reasons; highlighting a potential clinical risk. With a combination of education, improved department protocols and workflow strategies, the standard of sonography should be improved.

Dialysis Treatment is an Independent Risk Factor for Foot Morbidity.

Aim: To determine the prevalence of foot morbidity among patients with ESRD on dialysis. Methods: A prospective, non-experimental, quantitative time series design was employed. Forty-seven participants were recruited in the study. Medical records were reviewed followed by non-invasive foot assessments which included: Neurological, Arterial, Biomechanical, and Dermatological Assessment. Participants were assessed twice during the study. Results: Foot morbidity was found to be high among participants with ESRD on dialysis. 95.74% of participants presented with foot deformities, 76.60% had skin and nail conditions. 15% of participants had a history of ulceration and amputation. Moreover, active ulceration and history of revascularisation were also observed. Findings demonstrated overall poor foot health and footcare behavior within this population with 40.43% of participants having inappropriate footwear. The majority of participants did not check feet regularly, did not attend to podiatry appointments, and were unable to reach their feet for self-care. The Toe Brachial Pressure Index (TBPI), Spectral Doppler Waveform Analysis, and the Quantitative Sensory Testing (QST) were re-measured at each visit. Monophasic continuous doppler waveforms increased while triphasic waveforms decreased during the study period. Protective sensation did not decrease during the study period. The mean TBPI decreased during the study period. The relationship between the TBPI and duration of dialysis was found to be significant. Both DM and dialysis duration were identified as significant predictors of reduction in TBPI. Conclusion: This study demonstrates a high prevalence of foot morbidity among patients with ESRD on dialysis. This study highlighted the importance of expanding practice by introducing a podiatry service within the renal unit to provide foot screening, foot assessments, and foot care education, with the aim to reduce severe foot complications.

Correlation between Hepatic Vein Wave form Changes on Doppler Ultrasound and the Severity of Diseases in Cirrhotic Patients

Background: Cirrhosis is a common problem and is a leading cause of chronic liver disease. Early diagnosis with assessment of severity of diseases may help prevent the associated complications and patients’ sufferings. Now a days Hepatic venous Doppler can be a tool for diagnosis of cirrhosis and to assess correlation between waveform changes and severity of diseases. Objective: The purposes of this study was to determine the significance of hepatic vein waveform changes on doppler ultrasound in cirrhotic patients and to correlate with liver dysfunction. Materials and methods: This study was carried out in the department of Radiology and Imaging of Enam Medical College and Hospital during January 2017 to May 2018. Doppler waveforms were obtained from right hepatic vein in all the cases and classified as triphasic, biphasic and monophasic. Waveform comparisons were made among patients with differing grades of cirrhosis. Child- Pugh class was used to assess severity of cirrhosis. Doppler sonography was done in 80 patients suspecting of having liver cirrhosis. Data on clinical findings, B mode sonographic findings and hepatic vein doppler ultrasound findings were collected and documented in structured forms. Analysis was done using SPSS - 20. Results: Total of 80 patients who met the inclusion criteria are included in the study with mean age of 45.37±7.64 (range 25-75) years. Among these 57 (71%) were males while 23(29%) were females. On the basis of hepatic function 25 (31%) patients presented in Child-Pugh Class A, 31(39%) with Class B and 24(30%) patients had Class C. Hepatic venous waveform was triphasic in 22 (27.5%), biphasic in 28(35%), and monophasic in 30 (37.5%) cases. Our study revealed 88% (21) of Child- Pugh Class C, 23% (7) of Class B and 8% (2) of class A patients had monophasic HV waveform. The hepatic venous waveform progressively changed from triphasic to biphasic to monophasic with advancing grade of cirrhosis. The relationship of these waveforms change had significant relation with hepatic dysfunction (p &lt; 0.022). Conclusion: Hepatic vein wave form changes reflects the change in hepatic circulation associated with progression of liver cirrhosis. It can be used as a new parameter in the assessment of severity of liver cirrhosis. Thus, alteration in hepatic venous blood flow pattern on doppler ultrasound can be a useful noninvasive tool for evaluating diseases severity in patients with cirrhosis. J MEDICINE 2021; 22: 100-106

Implantable, Programmable, and Wireless Device for Electrical Stimulation of the Dorsal Root Ganglion in Freely-Moving Rats: A Proof of Concept Study.

ObjectiveThis was a proof of concept study, based on systematic reviews of the efficacy and safety of the dorsal root ganglion (DRG) stimulation. The main objective was to develop an implantable, programmable, and wireless device for electrical stimulation of DRG and a methodology that can be used in translational research, especially to understand the mechanism of neuromodulation and to test new treatment modalities in animal models of pain.MethodsWe developed and tested a stimulator that uses a battery-powered microelectronic circuit, to generate constant current square biphasic or monophasic pulsed waveform of variable amplitudes and duration. It is controlled by software and an external controller that allows radio frequency communication with the stimulator. The stimulator was implanted in Sprague–Dawley (SD) rats. The lead was positioned at the L5 DRG level, while the stimulator was placed in the skin pocket at the ipsilateral side. Forty-five animals were used and divided into six groups: spinal nerve ligation (SNL), chronic compression injury of the DRG (CCD), SNL + active DRG stimulation, intact control group, group with the implanted sham stimulator, and sham lead. Behavioral testing was performed on the day preceding surgery and three times postoperatively (1st, 3rd, and 7th day).ResultsIn animals with SNL, neurostimulation reduced pain-related behavior, tested with pinprick hyperalgesia, pinprick withdrawal test, and cold test, while the leads per se did not cause DRG compression. The rats well tolerated the stimulator. It did not hinder animal movement, and it enabled the animals to be housed under regular conditions.ConclusionA proof-of-concept experiment with our stimulator verified the usability of the device. The stimulator enables a wide range of research applications from adjusting stimulation parameters for different pain conditions, studying new stimulation methods with different frequencies and waveforms to obtain knowledge about analgesic mechanisms of DRG stimulation.

Abstract 12651: Non-Pharmacological Interventions to Improve Electrical Cardioversion Success in Patients With Atrial Fibrillation: A Scoping Review

Introduction: Electrical cardioversion is used commonly in patients with atrial fibrillation (AF). However, success rates vary and practical guidance is limited. Methods: We searched CENTRAL, Medline and EMBASE from inception to present and the grey literature. We included randomized controlled trials (RCTs) comparing any two interventions. Outcomes were initial and cumulative cardioversion success. We pooled data using random effects models. Results: From 13481 citations, we included 52 RCTs. Biphasic as compared to monophasic waveforms resulted in a higher rate of cardioversion for initial (18 studies, risk ratio [RR] 1.45, 95% confidence interval [CI] 1.10-1.90, I 2 =89%) and cumulative success (21 studies, RR 1.07, 95% CI 1.02-1.13, I 2 =75%). Fixed, maximum-energy shocks as compared to low-dose escalating energy protocols had a higher likelihood of initial (4 studies, RR 1.62, 95% CI 1.33-1.98, I 2 =72%) but not cumulative success (3 studies, RR 1.13, 95% CI 0.97-1.32, I 2 =86%). Initial or cumulative cardioversion success did not differ significantly for several other interventions. This included: antero-apical/lateral vs. anteroposterior positioned pads (initial: 10 studies, RR 1.06, 95% CI 0.89-1.27; cumulative: 13 studies, RR 0.99, 95% CI 0.95-1.04); rectilinear/pulsed biphasic vs. biphasic truncated exponential waveform (initial: 3 studies, RR 1.07, 95% CI 0.76-1.50; cumulative: 3 studies, RR 0.95, 95% CI 0.80-1.12); cathodal vs. anodal configuration (cumulative: 2 studies, RR 1.03, 95% CI 0.97-1.09); magnesium pre-treatment vs. none (initial: 2 studies, RR 1.36, 95% CI 0.82-2.24; cumulative: 2 studies, RR 1.05, 95% CI 0.96-1.14); and patches vs. manual pressure/paddles (initial: 2 studies, RR 1.04, 95% CI 0.26-4.12; cumulative: 2 studies, RR 0.87, 95% CI 0.61-1.25). Conclusions: Biphasic shock waveforms and high-energy shocks increase the efficacy of cardioversion of AF. Other interventions, including pad placement, biphasic waveform properties, electrode polarity, electrolyte pre-treatment, and manual pressure require further study.