Continuous Doppler Research Articles

Utility of the average pixel intensity method for the detection of moderate-severe mitral regurgitation in comparison with the area of the regurgitant orifice

Abstract Background and purpose The "average pixel intensity" (API) method, which is applied to the continuous Doppler spectral signal in mitral regurgitation (MR), has been proposed as a new method for automated MR grading. The objective of this study is to compare the API method with the effective regurgitant orifice area (EROA) for the detection of moderate-severe or severe MR (grades III or IV/IV) using open-source software (ImageJ). Methods Prospective single-center study (n=267) including patients with different degrees of MI, with a subgroup with cardiac magnetic resonance (CRM, n=55). Of the total sample, API was measured in 148 patients, and EROA in 159. Significant MR by echocardiography was defined according to a multiparameter criterion (American Society of Echocardiography - ASE algorithm), and by CRM according to regurgitant volume (≥50 ml) or regurgitant fraction (≥40%). The association between quantitative parameters (API and EROA) and the diagnosis of moderate-severe MI according to each imaging technique (echocardiography vs CMR) was evaluated using ROC curves. Results The prevalence of significant MR was 34.1% by echocardiography, and 21.8% by CMR. In 24% of cases the MR mechanism was functional. The median [Q1-Q3] API was 112 [141-166] units, and EROA 0.17 [0.10-0.30] cm2. The correlation between API and EROA was low (r = 0.34; p < 0.01). For the diagnosis of moderate-severe MR, EROA performed better than API taking the ASE algorithm as a reference (AUC 0.89 vs 0.75; Figure 1A), but both parameters showed a similar performance when compared to the CMR criterion ( AUC 0.80 vs 0.75; Figure 1B). Conclusions The low correlation between the API method and EROA raises their potential complementarity in the diagnosis of MR. Regarding the ASE multiparametric criterion by echocardiography, the EROA is superior to the API (being a key element in this algorithm). However, both methods present a similar association with the diagnosis of moderate-severe MR by CMR, and the assessment of both parameters could improve the agreement between echocardiography and CMR.

A hands-free carotid Doppler can identify spontaneous circulation without interrupting cardiopulmonary resuscitation: an animal study

BackgroundIdentifying spontaneous circulation during cardiopulmonary resuscitation (CPR) is challenging. Current methods, which involve intermittent and time-consuming pulse checks, necessitate pauses in chest compressions. This issue is problematic in both in-hospital cardiac arrest and out-of-hospital cardiac arrest situations, where resources for identifying circulation during CPR may be limited. The fraction of chest compression plays a pivotal role in improving survival rates. To address this challenge, we evaluated a newly developed hands-free, continuous carotid Doppler system (RescueDoppler), designed to identify spontaneous circulation during chest compressions. In our study, we utilized a porcine model of cardiac arrest to investigate sequences of ventricular fibrillation, followed by defibrillation, and monitoring for the return of spontaneous circulation during chest compressions with the carotid Doppler system. We explored both manual compressions at 100 and 50 compressions per minute and mechanical compressions. To estimate the detection rate (i.e., sensitivity), we employed a logistic mixed model with animal identity as random effect.ResultsOffline analysis of Doppler color M-mode and spectral display successfully identified spontaneous circulation during chest compressions in all compression models. Spontaneous circulation was detected in 51 of 59 sequences, yielding an expected sensitivity of 98% with a 95% confidence interval of 59% to 99%.ConclusionThe RescueDoppler, a continuous hands-free carotid Doppler system, demonstrates an expected sensitivity of 98% for identifying spontaneous circulation during both manual and mechanical chest compressions. Clinical studies are needed to further validate these findings.

Left Ventricular Geometry Indicators in Patients with Arterial Hypertension with Vitamin D Deficiency

Left ventricular hypertrophy (LVH) and left ventricular diastolic dysfunction (LVDD) are important prognostic factors that increase the risk of cardiovascular complications and mortality. Even with asymptomatic arterial hypertension (AH), patients with LVH have a worse prognosis than without it. It has been proven that the diagnosis of LVH is very important in clinical practice, because early detection of LVH and adequately prescribed treatment, which is aimed at restoring the parameters of the geometry, is of great importance to reduce the frequency of cardiovascular events. The objective: to analyze the features of the structural and functional state of the heart and LV diastolic function in patients with hypertension against the background of vitamin D deficiency or insufficiency. Materials and methods. 97 patients aged 45 to 74 years with uncomplicated hypertension of stage II of the 1st and 2nd degrees and 25 practically healthy people were examined, they were randomized by age and sex, the persons were included in the control group to determine normative reference values. Patients with hypertension were divided into three groups depending on the level of vitamin D in blood serum according to the Endocrine Practice Guidelines Committee. To assess the structural and functional state of the myocardium and LVDD, patients underwent transthoracic echocardiography with the study of transmitral blood flow in pulsed and continuous tissue Doppler mode. Results. An analysis of the frequency and structure of LVH showed that patients with hypertension with vitamin D deficiency have the highest frequency of detection of severe LVH, which is determined more often by 55.3% than in patients with vitamin D deficiency, and more often by 93.8% than in patients with a normal level of vitamin D (р < 0.05). For hypertensive patients with vitamin D deficiency the detection of cavity dilatation is more common – eccentric LVH with dilatation is 4.1 times more frequent than in the group of patients with a normal level of vitamin D and 2.1 times more often with vitamin D deficiency (p < 0.05). It has been proven that the indicators of LV myocardial mass (LVMM) and LV myocardial mass index (LVMMI) in patients with hypertension when combined with vitamin D deficiency reliably outweigh the corresponding indicators in patients with vitamin D insufficiency and a normal level, namely: LVMM by 10.9% and 22.3%, and LVMMI by 12.1% and 24.4%, respectively (p < 0.05). Similar changes are typical for the indicators of the thickness of the interventricular membrane, which were higher by 5.1% and 16.9%, respectively (p < 0.05), and the thickness of the back wall of the LV – by 9.8% and 30.2% (p < 0.05) respectively. The results of the study indicate that not only the age of the patients and the duration of hypertension, but also the low vimtain D concentration causes LV hypertrophy – an increase in the size and mass of cardiomyocytes and an increase in the amount of intercellaurl matrix. Conclusions. When combining hemodynamic and metabolic changes in hypertension with vitamin D deficiency, there is a potentiation of negative effects that affect the development of LV hypertrophy and dialytic dysfunction. In hypertensive patients combined with vitamin D deficiency a high frequency of LVH (93.9%) is determined, the structure of which is dominated by a severe form of LVH, as well as the inherent prognostically most unfavorable eccentric type of LVH with LV dilatation.

Abstract 4139982: Ventricular Pre-excitation Related Cardiac Dysfunction Secondary to Accessory Pathway in the Absence of Tachyarrhythmia: A Systematic Review

INTRODUCTION: Asynchronous ventricular pre-excitation over an accessory pathway (AP) in the absence of tachyarrhythmia is sometimes reported to cause left ventricular dysfunction (LVD). AIMS: To analyze the pathophysiological mechanism, role of AP location, evaluation modalities, and management of pre-excitation-related LVD. Methods: PubMed and Google Scholar databases were searched for reports on pre-excitation-induced LVD regardless of patient's age, and publication date. Results: Out of 11,775 citations retrieved, 53 met inclusion criteria, including 41 case reports and 12 observational studies with 611 total participants, age range of 1.14-60.8 years, and M: F of 325:265 (Table). At initial presentation, acute HF was common in pediatric patients, with poor response to medical therapy; while adults were more often asymptomatic. Right septal and right free wall were the commonest APs location associated with LVD. Amiodarone and propafenone achieved improvement in HF status by causing AP block and restoring ventricular synchrony in pediatric patients deemed unfit for catheter ablation (CA). Septal dyskinesia (SD) and intra-LV dyssynchrony (ILVD) were the key pathophysiological mechanisms causing LVD, leading to regional myocardial wall thinning and hypotrophy. Two-dimensional strain echocardiography (2D-STE) was used in quantifying regional myocardial strain, noninvasive localization of APs, and assessing therapeutic response to CA. Systolic intervals ratio [(pre-ejection period (PEP)/LV ejection time (LVET)] assessed via continuous Doppler detected derangement in LVEF with high accuracy. Preexcitation-induced myocardial changes were usually reversible after CA of APs with recovery of LV function. However, irreversible myocardial tissue damage even after CA was reported, especially in adults. Resolution of ILVD and SD in the immediate post-CA period was predictive of response to CA. Conclusions: We report the largest aggregation of data regarding preexcitation-induced LV dysfunction. Long-term asynchronous activation of the LV via an AP, even without tachyarrhythmias, can causes adverse myocardial changes leading to cardiac dysfunction, especially in children with right-sided APs. 2D-STE and systolic intervals (PEP/LVET) are efficient tools for evaluation. Ablation of APs usually restores cardiac function largely; however, irreversible myocardial fibrosis can ensue. Based on these data, early CA of the APs associated with LV dysfunction is, therefore, recommended.

Validation of a hand-held ultrasound device in the evaluation of aortic stenosis

Abstract Introduction Hand-held Ultrasound devices (HHUD) are increasingly used in routine clinical practice, although until recently they did not have continuous Doppler. There is no evidence on the usefulness of an HHUD for the assessment of aortic stenosis (AS) in real life. Objective To validate the use of a new HHUD device in a real-life scenario. Material and methods Observational, single-center and prospective study, including patients diagnosed with AS with a previous standard echocardiography. Patients were randomly recruited from a tertiary cardiac imaging laboratory. Immediately after the reference echocardiography performed by an imaging expert, a Cardiology trainee with ASE level II repeated the study blindly with an HHUD. Agreement between the two tests was evaluated by measuring the mean aortic valve gradient (mAG). An intraclass correlation coefficient (ICC) test, linear regression, and Bland-Altman test were performed to compare the two methods. Results 101 patients were recruited. The reference test calculated a mAG of 29 mmHg (19.8 - 42.2) versus a mAG of 27.2 mmHg (16.2 - 43.9) in HHUD. The statistical analysis showed a good correlation between both tests (ICC: 0.87 (95% CI: 0.79 -0.94) and r=0.89 (95% CI: 0.85-0.94) (Figure). The Bland-Altman test showed a non-significant underestimation (1.61 ± 0.9 mmHg; p= 0.09). The HHUD classified 29 cases as severe or major AS compared to 31 in the reference test (kappa= 0.81; 95% CI: 0.68 - 0.94). The HHUD showed an excellent agreement for classification of AS in at least severe AS grade. The kappa analysis had a value of 0.81 (95% CI 0.68 – 0.94) with a global agreement of 92.1%. The positive predictive value was 89.6%. The negative predictive value was 93.1%. Sensitivity and specificity were 83.8% and 95.7%. The rest of the variables evaluated showed poorer agreement. In those patients with obesity, worse acoustic window, atrial fibrillation and critical AS, the agreement was worse. Conclusions The new HHUD evaluated by an operator with limited experience showed good agreement with the reference echocardiographic device in determining the mean aortic gradient.Central picture

Differences in myocardial work across functional class strata in a severe aortic stenosis AHA D1 population. A cross-sectional study

Abstract Background Aortic stenosis is the most prevalent degenerative valvopathy. [1,2] The contractile state of the left ventricle has prognostic value in these patients. Global longitudinal strain (GLS) is the most accurate method for the estimation of myocardial performance. However, its value depends on the left ventricular afterload, [3,4] making GLS values challenging to interpret for decision-making purposes. The global myocardial work index (GWI) is an innovative echocardiographic technique for assessing myocardial function.[5] From these values, other indices representing constructive work, wasted work, and myocardial efficiency can be calculated.[6] Purpose The objective of our study was to measure the GWI and its derivatives using transthoracic echocardiography and relate them to the patient's functional class. Methods We conducted an observational, cross-sectional, and analytical study, including patients with severe aortic stenosis AHA D1, aged over 45 years, hypertensive, without coronary lesions. We exclude patients with other associated valvulopathies and rhythm disorders. All patients underwent transthoracic echocardiography, with measurements of GLS and GWI. Systolic blood pressure was added to the mean gradient of the aortic valve obtained by continuous Doppler. The population was divided into those with NYHA functional classes I/II and those with NYHA III/IV. Results Between May 2022 and August 2023, we included 152 patients, average age was 68 +/- 9 years. Of these, 54% were male, 38% had type 2 diabetes, 36% had dyslipidemia, and 30% had a history of smoking. Regarding functional class, 21% were in NYHA class I, 37% in NYHA II, 32% in NYHA III, and 9% in NYHA IV. The mean LVEF of 60 +/- 5%, GLS strain of -15.1 +/- 3.1; mean GWI was 2251 +/- 595 mmHg%, while the global constructive work index was 2526 +/- 596 mmHg%. The median wasted work index was 198.2 (196-204.2) mmHg%, and the mean myocardial efficiency was 89.9 +/- 4.7%. The global myocardial work index was 2455 +/- 582 in patients with NYHA I/II vs 1978 +/- 527 mmHg% in patients with NYHA III/IV (p<0.001) (Table 1). For the global constructive work, patients in NYHA I/II had a mean of 2708 +/- 590 mmHg, while those in NYHA III/IV had 2281 +/- 542 mmHg% (p<0.001). There were no significant differences in wasted work (190 +/- 11 mmHg%, NYHA I/II vs 210 +/- 113 mmHg%, NYHA III/IV, p=0.27). Marginally statistically significant difference was observed for myocardial efficiency (91 +/- 4.8%, NYHA I/II vs 89 +/- 4.5%, NYHA III/IV, p=0.49). Conclusions Patients with severe aortic stenosis have supranormal myocardial work indices.[7] However, as the disease progresses and patients experience greater clinical deterioration, these indices decrease, showing a significant difference between functional classes I/II and III/IV. Further studies are needed to determine the utility of these indices as prognostic indicators in this patient group.Table 1.Differences in myocardial workBulley

Insights from the assessment of anatomic valve orifice area after transcatheter aortic valve implantation using transesophageal echocardiography

Abstract Background Although transthoracic echocardiography (TTE) is the gold standard for evaluating effective valve orifice area (EOA) after transcatheter aortic valve implantation (TAVI), the continuous formula is inherently different from anatomic valve orifice area because it implies a minimum jet width through the aortic valve. It has also been reported that the doppler method with TTE overestimates the mean gradient due to pressure recovery and is even less accurate after TAVI. On the other hand, recent technological developments have improved image resolution, making valve morphology possible using transesophageal echocardiography (TEE). Purpose The purpose of this study was to compare transcatheter aortic valve (TAV) area using TEE and TTE to evaluate whether there is a significant difference in each area and to explore factors that influence the difference in area. Methods Patients who underwent TEE-guided TAVI and SAPIEN3 implantation between February 2019 and March 2023 and had aortic valve evaluation with TTE before discharge were included. We retrospectively evaluated the TAV after TAVI using TTE and TEE. Aortic valve orifice area was calculated by two methods: EOA index (doppler-area: DA) calculated by the continuous doppler formula using TTE and t-AVA index (trace-area: TA) derived by the trace method using TEE. TAV tracing was performed in early systole on the short-axis image of the aortic valve. The TAV tracing was performed by physicians specializing in echocardiography, and multiple physicians were blinded to the same case to eliminate inter-rater error. The percentage change between the two groups was calculated from the difference in area by TTE and TEE, and the 75th percentile of the percentage change was defined as the cutoff value for the group with the large difference in TAV area. Results Patients whose TAV was difficult to observe by TEE were excluded, and 464 patients were finally analyzed. TA was significantly larger than DA (1.56±0.28 cm2/m2 vs 1.18±0.26 cm2, p<0.001) and similar for all TAV sizes. However, even though TA expanded as valve size increased, the largest area of DA was observed in the 26mm TAV, and the 29mm TAV was comparable to the 26mm TAV. Only a weak correlation was shown between DA and TA (correlation coefficient: 0.356). There were 43 cases of moderate prosthetic valve-patient mismatch (PPM: EOA-i<0.85cm) in DA, but only 1 case in TA. In multivariate logistic regression analysis, women (OR 2.25, 95% CI 1.17-4.34, p < 0.015) and LV mass index (OR 1.01, 95% CI 1.00-1.02, p < 0.041) were independent factors for the large difference in TAV area. Conclusion After TAVI, the TAV area with TEE was larger than the EOA-i with TTE, and PPM was rarely seen. Depending on valve size, patient background, and cardiac morphology, there are cases of overestimation of postoperative AS in TTE, which may need to be carefully evaluated in women and patients with larger LV mass index.

Perioperative Detection of Cerebral Fat Emboli From Bone Using High-Frequency Doppler Ultrasound

ObjectiveFat embolism syndrome and cerebral fat emboli are rare yet serious conditions arising from systemic distribution of bone marrow emboli. Emboli are known to produce high-intensity transient signals (HITS) in a Doppler signal. We hypothesized that both intramedullary nailing in pigs and median sternotomy in human infants cause bone marrow release, that some of these cause cerebral emboli, and that these were detectable by a new cerebral doppler ultrasound monitoring system (NeoDoppler). We also aimed to describe the intensity of HITS generated during these procedures. MethodsSpecific pathogen-free Norwegian landrace pigs were allocated to either bilateral femoral nailing or injection of autologous bone marrow (positive controls). Testing was carried out under continuous Doppler monitoring. Presence of cerebral emboli was confirmed with histology. NeoDoppler data from infants undergoing sternotomy prior to cardiac surgery were investigated for comparison. ResultsEleven of twelve pigs were monitored with cerebral Doppler ultrasound during femoral surgery. HITS were seen in five (45%). Brain biopsies demonstrated bone marrow emboli in 11 of the 12 (92%). Four positive control pigs received intraarterial injections of bone marrow, saline, or contrast, and strong HITS were detected in all pigs (100%). Median sternotomy in eight human infants was associated with a significant increase in embolic burden; the HITS intensity was lower than HITS in pigs. ConclusionHigh-frequency cerebral Doppler ultrasound is a valuable tool for perioperative monitoring that can detect emboli in real-time, but sensitivity and specificity for bone marrow emboli may be limited and size-dependent.

An adaptive continuous scanning laser Doppler vibrometry technique for measuring vibrational mode shapes of structures with holes

Abstract Continuous Scanning Laser Doppler Vibrometry (CSLDV) enables fast and full-field vibration measurement in an intact area of a structure. This paper further proposes a novel adaptive CSLDV method that can obtain the Operational Deflection Shapes (ODS) and mode shape of structures with holes. Firstly, an adaptive path planning method is applied to the surface of the tested structure, which can automatically adapt to the size and position of round and square holes, as well as the resolution requirements for the measurement. Secondly, based on the symmetry and other characteristics of the planned path, the time domain signal is processed by delay optimization and demodulation to obtain the ODS of each vibration mode. Finally, a modal test is conducted on a flat structure with a square and circle holes as an example. A validation experiment is also performed using SLDV. The results show that the mode shapes obtained from both methods are consistent and the Modal Assurance Criterion (MAC) between them are all above 0.96. The method can realize CSLDV of flat plate structures with arbitrary square and round holes, and has the advantages of high efficiency and dense measurement points, which enhances its engineering applicability.

Instant Detection of Cerebral Blood Flow Changes in Infants with Congenital Heart Disease during Transcatheter Interventions.

Background: Transcatheter interventions are increasingly used in children with congenital heart disease. However, these interventions can affect cardiac output and cerebral circulation. In this pilot study, we aimed to investigate the use of NeoDoppler, a continuous transfontanellar cerebral Doppler monitoring system, to evaluate the impact of transcatheter interventions on cerebral circulation. Methods: Nineteen participants under one year of age (mean age 3.5 months) undergoing transcatheter cardiac interventions were prospectively included. Transfontanellar cerebral Doppler monitoring with the NeoDoppler system was initiated after intubation and continued until the end of the procedure. Results: Instant detection of changes in cerebral blood flow were observed across a spectrum of transcatheter interventions. Balloon aortic valvuloplasty demonstrated temporary cessation of cerebral blood flow during balloon inflation. Increase in cerebral diastolic blood flow velocity and decreased pulsatility were observed during patent ductus arteriosus occlusion. Changes in cerebral blood flow patterns were detected in two patients who encountered complications during their transcatheter interventions. There was no significant change in Doppler parameters before and after the interventions for the entire patient group. High quality recordings were achieved in 87.3% of the monitoring period. Conclusions: Continuous transfontanellar cerebral Doppler is feasible in monitoring cerebral hemodynamic trends and shows instantaneous changes associated with interventions and complications. It could become a useful monitoring tool during transcatheter interventions in infants.

Operational Deflection Shape Measurements on Bladed Disks with Continuous Scanning Laser Doppler Vibrometry.

The continuous scanning laser Doppler vibrometry (CSLDV) technique is usually used to evaluate the vibration operational deflection shapes (ODSs) of structures with continuous surfaces. In this paper, an extended CSLDV is demonstrated to measure the non-continuous surface of the bladed disk and to obtain the ODS efficiently. For a bladed disk, the blades are uniformly distributed on a given disk. Although the ODS of each blade can be derived from its response data along the scanning path with CSLDV, the relative vibration direction between different blades cannot be determined from those data. Therefore, it is difficult to reconstruct the complete vibration mode of the whole blade disk. In order to measure the complete ODS of the bladed disk, a method based on ODS frequency response functions (ODS FRFs) has been proposed. While the ODS of each blade is measured by designing the suitable scanning paths in CSLDV, an additional response signal is obtained at a fixed point as the reference signal to identify the relative vibration phase between the blade and the blade of the bladed disk. Finally, a measurement is performed with a simple bladed disk and the results demonstrate the feasibility and effectiveness of the proposed extended CSLDV method.

Cerebral blood flow dynamics during cardiac surgery in infants.

In this pilot study, we investigated continuous cerebral blood flow velocity measurements to explore cerebrovascular hemodynamics in infants with congenital heart disease undergoing cardiac surgery. A non-invasive transfontanellar cerebral Doppler monitor (NeoDoppler) was used to monitor 15 infants (aged eight days to nine months) during cardiac surgery with cardiopulmonary bypass. Numerical and visual analyses were conducted to assess trends and events in Doppler measurements together with standard monitoring equipment. The mean flow index, calculated as the moving Pearson correlation between mean arterial pressure and time averaged velocity, was utilized to evaluate dynamic autoregulation. Two levels of impaired autoregulation were defined (Mean flow index >0.3/0.45), and percentage of time above these limits were calculated. High quality recordings were achieved during 90.6% of the monitoring period. There was a significant reduction in time averaged velocity in all periods of cardiopulmonary bypass. All patients showed a high percentage of time with impaired dynamic autoregulation, with Mean flow index >0.3 and 0.45: 73.71% ± 9.06% and 65.16% ± 11.27% respectively. Additionally, the system promptly detected hemodynamic events. Continuous transfontanellar cerebral Doppler monitoring could become an additional tool in enhancing cerebral monitoring in infants during cardiac surgery. This pilot study demonstrates the feasibility of continuous transfontanellar Doppler monitoring of cerebral blood flow velocities during cardiac surgery in infants. It also demonstrates a high proportion of time with impaired cerebral autoregulation during cardiac surgery based on the Mean flow index. Continuous transfontanellar Doppler could become a useful tool to improve cerebral monitoring and provide new pathophysiological insight.

Phase angle associated is with low ankle-brachial index in type 2 diabetes patients in Ghana

BackgroundType 2 diabetes (T2DM) is associated with high burden of atherosclerotic macrovascular disease which could be diagnosed with ankle-brachial index (ABI). Phase angle (PhA) from bioelectric impedance analysis is associated with the development of cardiovascular diseases. We investigated the association between low ABI and phase angle in T2DM patients in Ghana. MethodIn a cross-sectional study, 462 T2DM patients were systematically recruited for the study. ABI was measured using an 8 Hz continuous Doppler and ABI≤0.9 was considered to be low ABI. PhA was obtained from resistance and reactance from Bioelectric impedance analysis. ResultsThe prevalence of low ABI was 16 % in the study population. T2DM patients with low ABI have decreased PhA (7.5 ± 1.9 vs 8.3 ± 2.2 units, p = 0.004) compared to those with normal ABI. An increase in phase angle by 1° was associated with a decrease in odds of having low ABI in unadjusted [OR (95 % CI) = 0.79 (0.48 – 0.95), p = 0.007] and adjusted models [0.88 (0.43 – 0.98), p = 0.036]. ConclusionThe prevalence of low ABI in T2DM patients in this study was 16 %. Also, PhA was lower in patients with low ABI compared to those with normal ABI.

Evaluation of hemorrhagic shock and fluid resuscitation in pigs using handless Doppler carotid artery ultrasound.

This study aimed to utilize a hemorrhagic shock pig model to compare two hemodynamic monitoring methods, pulse index continuous cardiac output (PiCCO) and spectral carotid artery Doppler ultrasound (CDU). Additionally, we sought to explore the feasibility of employing CDU as a non-invasive hemodynamic monitoring tool in the context of hemorrhagic shock and fluid resuscitation. Animal experiments. Female pigs were selected, and hemorrhagic shock was induced by rapid bleeding through an arterial sheath. Hemodynamic monitoring was conducted using both PiCCO and CDU during episodes of hemorrhagic shock and fluid resuscitation. Among the 10 female pigs studied, CDU measurements revealed a significant decrease in carotid velocity time integral (cVTI) compared to baseline values under shock conditions. During the resuscitation phase, after the mean arterial pressure (MAP) returned to its baseline level, there was no significant difference between cVTI and baseline values. A similar trend was observed for carotid peak velocity (cPV). The corrected flow time (FTc) exhibited a significant difference only at the time of shock compared to baseline values. In comparison to PiCCO, there was a significant correlation between cVTI and MAP (r = 0.616, P < 0.001), stroke volume (SV) (r = 0.821, P < 0.001), and cardiac index (CI) (r = 0.698, P < 0.001). The carotid Doppler shock index (cDSI) displayed negative correlations with MAP (r = - 0.593, P < 0.001), SV (r = - 0.761, P < 0.001), and CI (r = - 0.548, P < 0.001), while showing a positive correlation with the shock index (SI) (r = 0.647, P < 0.001). Compared to PiCCO, CDU monitoring can reliably reflect the volume status of hemorrhagic shock and fluid resuscitation. CDU offers the advantages of being non-invasive, providing real-time data, and being operationally straightforward. These characteristics make it a valuable tool for assessing and managing hemorrhagic shock, especially in resource-limited settings.

Comparison of the Diagnostic Yield of Intracoronary Acetylcholine Infusion and Acetylcholine Bolus Injection Protocols During Invasive Coronary Function Testing

Coronary endothelial dysfunction (CED) and coronary artery spasm (CAS) are causes of angina in patients with no obstructive coronary arteries (ANOCA). Both can be diagnosed by invasive coronary function testing (ICFT) using Acetylcholine (ACh). This study aimed to evaluate the diagnostic yield of a 3-minute ACh infusion as compared to a 1-minute ACh bolus injection protocol in testing CED and CAS. In total 220 consecutive ANOCA patients underwent ICFT using continuous Doppler flow measurements. Per protocol, 110 patients were tested using 3-minute infusion and thereafter 110 patients using 1-minute bolus injections, due to a protocol change. CED was defined as a <50% increase in coronary blood flow or any epicardial vasoconstriction in reaction to low dose ACh and CAS according to the COVADIS criteria, both with and without T-wave abnormalities, in reaction to high dose ACh. The prevalence of CED was equal in both protocols (78% vs 79%; p=0.869). Regarding the endotypes of CAS according to COVADIS, the equivocal endotype was diagnosed less often in the 3-minutes vs 1-minute protocol (24% vs 44%; p=0.004). Including T-wave abnormalities to the COVADIS criteria resulted in a similar diagnostic yield of both protocols. Hemodynamic changes from baseline to the low or high ACh doses were comparable between the protocols for each endotype. In conclusion, ICFT using 3-minute infusion or 1-minute bolus injections of ACh showed a similar diagnostic yield of CED. When using the COVADIS criteria, a difference in the equivocal diagnosis was observed. Including T-wave abnormalities as diagnostic criterion reclassified equivocal test results into CAS and decreased this difference. For clinical practice, we recommend the inclusion of T-wave abnormalities as diagnostic criterion for CAS and the 1-minute bolus protocol for practicality.

Effect of continuous 2MHz transcranial ultrasound as an adjunct to tenecteplase thrombolysis in acute anterior circulation ischemic stroke patients: an open labeled non-randomized clinical trial.

The treatment of acute ischemic stroke has improved in last few decades. While meta-analyses of several trials have established the safety and efficacy of Intravenous (IV) Tenecteplase thrombolysis, concomitant continuous transcranial doppler (TCD) ultrasound administration has not been assessed in any clinical trial. The aim of this study was to determine the effects of continuous 2MHz TCD ultrasound during IV Tenecteplase thrombolysis for Middle cerebral artery (MCA) stroke. A total of 19 patients were included, 13 received TCD ultrasound and 6 sham TCD with IV Tenecteplase. TCD spectrum and difference in Pre and post TCD parameters were measured. Asymptomatic hemorrhagic transformation of infarct wasseen in two patients. There was no mortality or clinical worsening in thesonothrombolysis group as against sham sonothrombolysis group. Median of peak systolic velocity wasincreased in both thesonothrombolysis (P = 0.0002) and sham sonothrombolysis group (P-value = 0.001). The difference in change in mean flow velocity between two groups, sonothrombolysis (11cm/sec)and sham sonothrombolysis (3.5cm/sec) were also significantly different (P = 0.014). This pilot work has established safety of continuous 30min TCD application along with IV Tenecteplase thrombolysis and it concludes thatconcomitant 2MHz TCD ultrasound administration significantly increased the MCA blood flow compared to chemothrombolysis alone.CTRI Registered Number: CTRI/2021/02/031418.

Application of Time Synchronous Averaging in Mitigating UAV Noise and Signal Loss for Continuous Scanning Laser Doppler Vibrometry

The laser Doppler vibrometer (LDV) has been shown to be effective for a wide application of vibration assessments that are well accepted. One of the new avenues for exploring alternative measurement scenarios, mounting LDVs on unmanned aerial vehicles (UAVs) is emerging as a potential avenue for remote and harsh environment measurements. Such configurations grapple with the challenge of the LDV sensor head being sensitive to UAV vibration during flight and signal loss due to tracking error. This study investigates the effectiveness of several Time Synchronous Averaging (TSA) techniques to circumvent these obstacles. Through comprehensive evaluations, all three TSA techniques under investigation demonstrated significant potential in suppressing UAV-induced noise and minimising the effects of signal dropout. Traditional TSA showcased a remarkable sixfold enhancement in signal quality when analysed via the mean square error. However, the study also highlighted that while TSA and Multi-Cycle Time Synchronous Average (MCTSA) elevated signal clarity, there is a trade-off between noise suppression and signal duration. Additionally, the findings emphasise the importance of synchronisation between scanning and target vibration. To achieve optimal results in Continuous Scanning Laser Doppler Vibrometer measurements, there is a need for advanced algorithms capable of estimating target vibration and synchronising scanning in real-time. As the study was rooted in steady-state vibrations, future research should explore transient vibration scenarios, thereby broadening the application scope of TSA techniques in UAV-mounted LDV systems.

A new method to evaluate carotid blood flow by continuous Doppler monitoring during cardiopulmonary resuscitation in a porcine model of cardiac arrest

AimWe used a wearable carotid Doppler patch to study carotid blood flow patterns in a porcine model of cardiac arrest to identify return of spontaneous circulation (ROSC) and hemodynamics associated with different arrhythmias and the quality of compressions. MethodsTwenty Landrace pigs were used as models of cardiac arrest following a standard protocol. Carotid blood flow was monitored continuously using noninvasive ultrasound. Carotid spectral waveforms were captured during various arrhythmias and CPR. Typical carotid blood flow waveforms were recorded at the time of ROSC, and hemodynamic changes were compared with carotid blood flow parameters. ResultsThe results showed that the carotid blood flow waveforms varied with ventricular arrhythmia type. During CPR, compression depth correlated significantly with carotid maximal velocity (Vmax) (Spearman correlation coefficient (r) = 0.682, P < 0.001) and velocity–time integral (VTI) (r = 0.794, P < 0.001). Vmax and VTI demonstrated moderate predictive value for survival. The regular carotid blood flow pattern towards the brain was observed during ROSC, concurrent with compression waveforms. After ROSC, VTI and carotid pulse volume (cPV) showed similar trends as stroke volume (SV). The carotid minute volume (cMV) exhibited a similar trend as cardiac output (CO). ConclusionsCarotid blood flow monitoring could provide valuable information about different arrhythmias as well as the quality of CPR. Carotid flow monitoring allows for timely and effective identification of ROSC. In addition, it may provide valuable hemodynamic information after ROSC.

Advancing paediatric cardiac imaging: a comprehensive analysis of the feasibility and accuracy of a novel 3D paediatric transoesophageal probe.

Pediatric transoesophageal echocardiography (TOE) probes have remained two-dimensional (2D) limiting their use compared to adults. While critical in pediatrics for interventions and post-surgery assessments, technological advancements introduced a three-dimensional (3D) pediatric TOE probe. This study assessed the new 3D pediatric TOE probe (GE 9VT-D) for feasibility, handling, and imaging quality. At Children's Hospital of Toulouse, 2-month prospective study enrolled children undergoing TOE with the new probe. All imaging modalities were rated by 2 operators using a 5-point Likert-type scale from 1 (very poor) to 5 (very good) quality. Forty-five children, median age 3.7 (range: 2 months-14.7 years) median weight 7.8 kg (range: 4.3-48 kg) underwent 60 TOEs: 25% pre-surgery, 45% post-surgery, 28% during percutaneous procedures, and 2% in intensive care. Probe handling was "very easy" in all cases without adverse events. The median score of 2D, 2D colour, pulsed Doppler and 3D were noted 5 out of 5 and continuous Doppler and 3D colour 4 out of 5. The 3D image quality remained consistent irrespective of the patient weighing above or below 7.8 kg (p = 0.72). Postoperative TOEs identified two cases needing further interventions, emphasizing its value in evaluating surgical outcomes and also for guiding percutaneous interventions. Our comprehensive evaluation demonstrates that the new 3D pediatric TOE probe is feasible and provides high-quality imaging in pediatric patients. The successful integration of this novel probe into clinical practice has the potential to enhance diagnostic accuracy and procedural planning, ultimately optimizing patient outcomes in pediatric cardiac care.

Flexible Conformal Multifunctional Time‐Varying Phase‐Modulated Metasurface with Polarization Control for Radar Feature Transformation

AbstractReconfigurable metasurfaces have shown unprecedented capabilities in controlling electromagnetic (EM) waves in recent years and play an essential role in information manipulation. However, most research on reconfigurable metasurfaces is limited to planar rigid structures, with only one control function and suitable for specific single polarization. Achieving simultaneous control of phase, polarization, and frequency in the conformal structure has significant practical implications in many applications, but remains obviously challenging. In this paper, a flexible multifunctional time‐varying phase‐modulated metasurface (MTPM) with orthogonal polarization control is proposed for conformal applications to manipulate the spectrum distribution. It enables time encoding capability in controlling the phase characteristics of x‐ and y‐polarized EM waves individually by switching the bias voltage of the PIN diode in two directions. Discrete harmonic spectrum and continuous Doppler frequency shifts are implemented separately on two orthogonal polarizations by applying different time coding sequences. As a practical application, a conformal MTPM for radar feature transformation is explored. Multiple discrete false targets and defocusing phenomena can be realized respectively for x‐ and y‐polarized waves. Both simulated and measured results verify the validity of the proposed method and prototype.