Invasive Measurements Research Articles

Comparison of Ensemble Method Performance in Classifying Blood Sugar Levels Output from Non-Invasive Device

Diabetes Mellitus (DM) is a persistent health issue in many countries and is a leading cause of heart disease, kidney failure, and blindness The International Diabetes Federation (IDF) estimated in 2019 that at least 463 million people worldwide aged 20-79 suffer from diabetes. This number is expected to rise to 578 million by 2030 and 700 million by 2045. Machine learning is a type of machine learning that is very helpful in various fields, including healthcare. In classification cases, ensemble methods classify by combining decisions from several other models, one way being through majority voting. Ensemble methods often produce more accurate classification or prediction results. Several ensemble methods include random forest, extra trees, rotation forest, and double random forest. The data used in this study is part of research on the development and clinical testing of a prototype non-invasive blood glucose monitoring device by the non-invasive biomarking team at IPB. The data includes both invasive and non-invasive blood glucose measurements collected in 2019. This study compares the performance of the random forest, extra trees, rotation forest, and double random forest models on blood glucose level data obtained from non-invasive devices. The research results show that the Rotation Forest algorithm is the best model, with the highest average accuracy compared to the other three algorithms, achieving an accuracy level of 0.7142857 (71.42%).

Invasive assessment of coronary microvascular dysfunction and cardiovascular outcomes across the full spectrum of CHD: a meta-analysis

Introduction and objectivesCoronary microvascular dysfunction (CMD) is highly prevalent and is recognized as an important clinical entity in patients with coronary heart disease (CHD). Nevertheless, the association of CMD with adverse cardiovascular events in the spectrum of CHD has not been systemically quantified. MethodsWe searched electronic databases for studies on patients with CHD in whom coronary microvascular function was measured invasively, and clinical events were recorded. The primary endpoint was major adverse cardiac events (MACE), and the secondary endpoint was all-cause death. Estimates of effect were calculated using a random-effects model from published risk ratios. ResultsWe included 27 studies with 11 404 patients. Patients with CMD assessed by invasive methods had a higher risk of MACE (RR, 2.18; 95%CI, 1.80-2.64; P<.01) and all-cause death (RR, 1.88; 95%CI, 1.55-2.27; P<.01) than those without CMD. There was no significant difference in the impact of CMD on MACE (interaction P value=.95) among different invasive measurement modalities. The magnitude of risk of CMD assessed by invasive measurements for MACE was greater in acute coronary syndrome patients (RR, 2.84, 95%CI, 2.26-3.57; P<.01) than in chronic coronary syndrome patients (RR, 1.77, 95%CI, 1.44-2.18; P<.01) (interaction P value<.01). ConclusionsCMD based on invasive measurements was associated with a high incidence of MACE and all-cause death in patients with CHD. The magnitude of risk for cardiovascular events in CMD as assessed by invasive measurements was similar among different methods but varied among CHD populations.

Correlation of Noninvasive Cardiac MRI Measures of Left Ventricular Myocardial Function and Invasive Pressure-Volume Parameters in a Porcine Ischemia-Reperfusion Model.

Purpose To assess the correlation between noninvasive cardiac MRI-derived parameters with pressure-volume (PV) loop data and evaluate changes in left ventricular function after myocardial infarction (MI). Materials and Methods Sixteen adult female swine were induced with MI, with six swine used as controls and 10 receiving platelet-derived growth factor-AB (PDGF-AB). Load-independent measures of cardiac function, including slopes of end-systolic pressure-volume relationship (ESPVR) and preload recruitable stroke work (PRSW), were obtained on day 28 after MI. Cardiac MRI was performed on day 2 and day 28 after infarct. Global longitudinal strain (GLS) and global circumferential strain (GCS) were measured. Ventriculo-arterial coupling (VAC) was derived from PV loop and cardiac MRI data. Pearson correlation analysis was performed. Results GCS (r = 0.60, P = .01), left ventricular ejection fraction (LVEF) (r = 0.60, P = .01), and cardiac MRI-derived VAC (r = 0.61, P = .01) had a significant linear relationship with ESPVR. GCS (r = 0.75, P < .001) had the strongest significant linear relationship with PRSW, followed by LVEF (r = 0.67, P = .005) and cardiac MRI-derived VAC (r = 0.60, P = .01). GLS was not significantly correlated with ESPVR or PRSW. There was a linear correlation (r = 0.82, P < .001) between VAC derived from cardiac MRI and from PV loop data. GCS (-3.5% ± 2.3 vs 0.5% ± 1.4, P = .007) and cardiac MRI-derived VAC (-0.6 ± 0.6 vs 0.3 ± 0.3, P = .001) significantly improved in the animals treated with PDGF-AB 28 days after MI compared with controls. Conclusion Cardiac MRI-derived parameters of MI correlated with invasive PV measures, with GCS showing the strongest correlation. Cardiac MRI-derived measures also demonstrated utility in assessing therapeutic benefit using PDGF-AB. Keywords: Cardiac MRI, Myocardial Infarction, Pressure Volume Loop, Strain Imaging, Ventriculo-arterial Coupling Supplemental material is available for this article. © RSNA, 2024.

Diagnostics of acute compartment syndrome : Current gold standard and the state of science of noninvasive assessment methods

Acute compartment syndrome (ACS) is defined by a disorder of the microcirculation due to a persistent pathological pressure increase within amuscle compartment. The ischemia of the tissue leads to an initially reversible functional impairment and finally irreversible damage of the musculature, nerves and other structures. Based on the understanding of the pathophysiology, the current diagnostic concepts and treatment using the so-called dermatofasciotomy of the affected muscle compartments can be derived. In addition to the suspicion of a possible ACS based on the medical history of the patient, the findings of the clinical examination are decisive. This review article gives a summary of all the essential aspects of the diagnostics. In clinically uncertain cases and for monitoring, an objectification of the findings using instrument-based techniques is increasingly required. Nowadays, invasive needle pressure measurement is available; however, due to limited reliability, specificity and sensitivity, these measurements only represent an aid to decision guidance supporting or advising against the indications for dermatofasciotomy. The increasing demands on making a certain diagnosis and justification of a surgical intervention from a legal point of view, substantiate the numerous scientific efforts to develop noninvasive instrument-based diagnostics. These methods are based either on detection of increasing intracompartmental pressure or decreasing perfusion pressure and microcirculation. The various measurement principles are summarized in a lucid form.

LVSP and LBBP result in similar or improved LV synchrony and hemodynamics compared to biventricular pacing

Abstract Background The effect of left ventricular myocardial septal pacing (LVSP) and left bundle branch pacing (LBBP) on ventricular synchrony and LV hemodynamics is poorly understood in unselected cardiac resynchronization therapy (CRT) patients. Aim To investigate the impact of LBBP and LVSP on ultra-high-frequency ECG (UHF-ECG) ventricular synchrony and hemodynamics in CRT patients. Methods In consecutive CRT patients with LBBB, ventricular synchrony was assessed using UHF-ECG. LV hemodynamics was assessed using invasive systolic blood pressure measurement during multiple transitions between LBBP, LVSP, and biventricular pacing (BVP). LV synchrony was assessed by LV lateral wall delay (LVLWd) from the first to the last from V5-V8 activations. Hemodynamic effects were expressed as relative changes in systolic blood pressure. Results Thirty patients with an LVEF of 29 ± 6% and mean QRSd of 169 ± 24 ms were included. Twenty had non-ischemic cardiomyopathy. QRSd during BVP, LVSP, and LBBP was the same, but LBBP provided shorter LVLWd than BVP (-9 ms (-16; -4), p = 0.004); the difference between LVSP and BVP was not significant (-4 ms (-10;2), p = 0.2). LBBP was associated with higher systolic blood pressure than BVP (4% (2; 5) p &amp;lt; 0.001), while LVSP was not (1% (1; 2), p = 0.1. LV hemodynamic improvements during LBBP and LVSP vs. BVP were more pronounced in non-ischemic than ischemic patients. Conclusion The differences in ventricular synchrony between LBBP, LVSP, and BVP were demonstrated using UHF-ECG but not QRSd. LBBP, but not LVSP, was associated with better LV synchrony and hemodynamics than BVP.Local activation times in V1–V8Ventricular dyssynchrony and hemodynamic

Acute hemodynamic effects of the Marshall-Plan ablation on left and right atrial pressure: does 'respecting atrial physiology' prevent stiff left atria? A retrospective single- center analysis

Abstract Introduction Stiff left atrium (STILA)-syndrome is a relevant concern after extensive ablation in the left atrium (LA) e.g. in persistent atrial fibrillation (AF). STILA often causes disabling heart failure symptoms worse than the initial arrhythmia symptoms. Therefore preventing adverse ablation-induced hemodynamic effects is of utmost concern. Methods This single-center study retrospectively analyzed data from 89 consecutive patients who underwent biatrial ablation for AF following the Marshall-Plan between February 2022 and November 2023. The procedures included ablation of the CTI and PVI where necessary followed by ablation of a LA roof line and ablation of the lateral mitral isthmus after previously performed ethanol ablation of the vein of Marshall. This lesion set is considered to maintain physiological activation of the LA. This study evaluates acute hemodynamic changes following the Marshall-Plan. Invasive hemodynamic measurements of mean left and right atrial pressure, as well as A- and V-waves were performed in all patients before and after the ablation. We assessed the acute changes of atrial hemodynamics in these procedures. Continuous data are given as mean ± standard deviation, categorical data are expressed as number and percentages. Differences between groups were determined by Student’s t-test, chisquare-test, and Fisher’s exact test using SPSS software. A p-value of &amp;lt;0.05 was deemed significant. Results The patients' mean age was 70.1 ± 7.5 years and 39.0% were female. Mean BMI was 28.9 ± 5.2 kg/m². Procedures were performed under general anesthesia (with a PEEP of 5.5cmH2O (2-10 cmH2O)) and took 181 minutes on average. Left atrial mean pressure averaged at 15.7mmHg before the procedure. The overall average change of left atrial mean pressure was +1,8mmHg. The average change in left atrial A- and V-Wave amounted to -1.9mmHg and -0.9mmHg respectively. The pre-procedural average right atrial mean pressure was 12.1mmHg. Right atrial mean pressure inclined by +1.6mmHg. The average change in right atrial A- and V-Wave was +0.6mmHg and +1.1mmHg respectively. The i.v. administered volume averaged 1900 ± 285ml. 3.3% of patients showed an increase of mean LA-pressure &amp;gt;9mmHg. Those patients tended to be older (74.3years), were all male (100%) and had a higher BMI (31.5 kg/m²) as well as higher amount of i.v. administered volume (2333ml) and a longer procedure (213min). Discussion Complex and extensive biatrial ablation following the Marshall-Plan does not lead to acute significant increases in left or right atrial pressures. The administered i.v. volume might explain the slight increases observed. In our observation, the rate of significant increases in LA-pressure is low. This suggests that disrupting the (left) atrial activation pattern might play a role in the development of diastolic dysfunction and thereby STILA-syndrome. Respecting atrial physiology may be beneficial for preventing adverse hemodyamic changes after ablation.

Quantitative and qualitative assessment of left atrial cardiomyopathy as well as prediction of atrial fibrillation recurrences upon PVI using machine learning

Abstract Introduction Atrial fibrillation (AF) is one of the most common heart pathologies in daily clinical practice and confers significant mortality and morbidity. However, AF ablation often proves ineffective - even after successful pulmonary vein isolation (PVI). The prediction of PVI failure for the long-term treatment of AF as well as the improved assessment of the underlying substrate appears pivotal. We hypothesize, that ML can be applied to better characterize the substrate and recurrence in AF patients upon PVI. Methods &amp; Results We retrospectively evaluated data from 205 patients that underwent AF ablation between 2019 and 2023, including high-density 3D electroanatomic maps (sinus rhythm), LA rotational angiography, invasive LA hemodynamic measurements (after transseptal passage), echocardiography, 12-lead ECG and laboratory testing. A neuronal net was trained on selected features extracted from those datasets using supervised learning and employed to predict measures of atrial cardiomyopathy and AF recurrence. Patients were 66±1 years old and received first or second pulmonary vein isolation (PVI) for paroxysmal atrial fibrillation with 18% documented recurrences upon a mean follow-up of 23±1months. First, we extensively refined or developed tools for automated P-wave analysis from 12-lead ECGs as well as local LA voltage and volume quantification. Next, LA hemodynamics and volumes were assessed: Mean LA volume as derived from rotational angiography significantly correlated with LA volume index as obtained using echocardiography. Interestingly, LA size showed no correlation with NT-proBNP, LA low voltage or LA hemodynamics. In addition, global (25±2% of total LA area) and local (i.e. anterior, posterior, roof) LA voltage was determined and shown to be an independent predictor of AF recurrence. In our first unselected subset of 136 patients with 2nd PVI for atrial fibrillation, our ML models predicted LA fibrosis (i.e. low voltage regions; Utah stage) from 12-lead ECGs with an accuracy of 90%. Accuracy was 87% for the prediction of AF recurrences from LA pressure and low-voltage regions. In addition, the algorithm predicted AF recurrences from 12-lead SR ECGs obtained before PVI with an accuracy of 91%. Conclusion Artificial neural networks allow to quantitatively and qualitatively predict measures of atrial cardiomyopathy and atrial fibrillation recurrence probability upon complete PVI with high accuracy.Figures

Machine-learning guided differentiation between photoplethysmography waveforms of supraventricular and ventricular origin

Abstract Aims To test, whether a neural network-based classifier could aid in distinguishing photoplethysmographic (PPG) pulse waveforms of ventricular from those of supraventricular origin. Methods Thirty patients undergoing invasive electrophysiological studies for documented narrow complex tachycardias between May and December 2021 at a university medical centre were included in the trial. PPG waveforms were recorded using a PPG wristband (Empatica E4) in parallel to 12-lead surface electrograms (ECGs) and intracardiac electrograms from diagnostic catheters. Pulse waves were then annotated to either supraventricular (sinus rhythm, atrial pacing) or ventricular origin (ventricular pacing) based on invasive electrogram recordings, ECGs and stimulation protocols. 21147 data sets were split into test, training and validation data sets and used to develop, train and validate a convolutional neural network (CNN) for classifying PPG waveforms according to their origin into sinus rhythm, atrial or ventricular pacing. Results Datasets were complete for 27 patients. 74% were female and median age was 53 (range 18, 78) years, median BMI was 27±5, 19% had arterial hypertension, 11% had diabetes and 15% had coronary artery disease. During the electrophysiological study, typical AV-nodal re-entrant tachycardias could be induced in 63% of patients, 15% had inducible atrial tachycardias and the other patients had no inducible tachyarrhythmias. Our CNN-based classifier was able to correctly predict the origins of pulse waves in 95±1% for sinus rhythm, 96±1% for atrial paced rhythms and 95±1% for ventricular rhythms. Conclusion A neural network-based classifier trained on ground truth PPG data obtained by using invasive EP measurements for annotation could accurately predict atrial or ventricular origin from PPG waveforms alone.Graphical abstract

Acute haemodynamic changes during left atrial appendage closure

Abstract Purpose Left atrial appendage closure (LAAC) presents an alternative treatment for stroke prevention in atrial fibrillation (AF) in patients with contraindication for long-term anticoagulation. However, even in patients in AF, left atrial appendage plays an important role in reservoir function of left atrium. The purpose of this study was to assess acute hemodynamic effects during LAAC. Methods Consecutive patients indicated for LAAC from January 2022 to October 2023 were enrolled. The invasive hemodynamic measurements were done at the beginning of the procedure after transseptal puncture, and at the end from the procedure after device deployment. Following parameters were measured: systolic, and diastolic blood pressure, and pressure in left atrium (LA), all measurements were done at rest and after 3 minute isometric exercise (handgrip). Results Thirty-two patients were included (age 76,2+7,1 yrs, 22 (69%) males, 23 (72%) permanent AF, left ventricular ejection fraction 52+11,8%). No patients experienced moderate/severe mitral insufficiency, the saline intake during procedure was 738 ml. Isometric exercise significantly increased the LA pressure: the LA pressures (rest/exercise) were 13.7+6.7 mmHg/16.7+8.8 mmHg (p=0.003) at the beginning of the procedure, and 17.0+7.3mmHg/20.0+7.3 mmHg (p=0.005) after device deployment. The LA pressure obtained after device deployment (both rest/exercise) were significantly higher compared to values obtained at the beginning of the procedure. (p=0.003). Conclusions LAAC is associated acute increase of both rest and exercise LA pressure. Whether its acute negative effect remains over time needs further investigation.

Increased left atrial pressure is associated with fibrosis, elevated mechanical load and ventricular diastolic dysfunction in patients undergoing AF catheter ablation

Abstract Background Increased left atrial filling pressures might be a hallmark feature of atrial cardiomyopathy which has been associated with an increased incidence of atrial fibrillation (AF) recurrence even after successful pulmonary vein isolation (PVI). The interplay between left atrial pressure, measured during the ablation procedure, and other parameters characterising atrial and ventricular remodelling in patients with AF remains elusive. Methods and Results Between 2018 and 2022, 182 patients undergoing PVI for paroxysmal or persistent AF were included in the study. Mean left atrial pressure (mLAP) was measured invasively during the ablation procedure after transseptal puncture. A mLAP higher than 15 mmHg was considered the cut-off value for LA hypertension. Bipolar high-density 3D electro-anatomical maps (Carto) obtained during the procedure were used to manually quantify low-voltage (&amp;lt;0.5 mV) and normal voltage areas of the LA surface and a global low-voltage/normal voltage ratio index was derived. Contemporary transthoracic echocardiography data were included to evaluate LV systolic and diastolic function and blood samples were obtained post-procedurally from all patients. In bivariate linear regression analysis, mLAP reached only modest correlation with E/e’ as an imaging marker of diastolic dysfunction (R=0.31, p=0.005) (Figure 1A), with particular differences in mLAP values between patients with marked diastolic impairment (E/e’ &amp;gt; 15) vs. subgroups with mild dysfunction ( 8 &amp;lt; E/e’ ≤ 15) or normal diastolic function (E/e’ ≤ 8 ) (Figure 1B), log NT proBNP (R=0.34, p&amp;lt;0.001) (Figure 1C) and low-voltage/normal voltage ratio index (R=0.21, p=0.014) (Figure 1D). For a total of 158 patients, data about 1 year recurrence of AF were available, of these 22 (13.9%) had a recurrence after two procedures using cryo-energy for the index PVI and radiofrequency ablation for the re-PVI (second procedure). A Kaplan-Meier analysis and log-rank test showed a trend but no statistical significance regarding an increased AF recurrence rate between patients with and without LA hypertension (χ2 = 2.63, p= 0.09) (Figure 2). Conclusion Direct intra-procedural invasive measurement of LA pressures can offer an important and convenient novel piece of information for patients undergoing catheter ablation procedures for AF, with potential implication for post-procedural recurrence risk stratification. Atrial hypertension is only partially related to LV diastolic impairment, atrial fibrosis and myocardial mechanical load burden.

Feasibility of decoding covert speech in ECoG with a Transformer trained on overt speech

Several attempts for speech brain–computer interfacing (BCI) have been made to decode phonemes, sub-words, words, or sentences using invasive measurements, such as the electrocorticogram (ECoG), during auditory speech perception, overt speech, or imagined (covert) speech. Decoding sentences from covert speech is a challenging task. Sixteen epilepsy patients with intracranially implanted electrodes participated in this study, and ECoGs were recorded during overt speech and covert speech of eight Japanese sentences, each consisting of three tokens. In particular, Transformer neural network model was applied to decode text sentences from covert speech, which was trained using ECoGs obtained during overt speech. We first examined the proposed Transformer model using the same task for training and testing, and then evaluated the model’s performance when trained with overt task for decoding covert speech. The Transformer model trained on covert speech achieved an average token error rate (TER) of 46.6% for decoding covert speech, whereas the model trained on overt speech achieved a TER of 46.3% (p>0.05;d=0.07)\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$( p > 0.05; d=0.07)$$\\end{document}. Therefore, the challenge of collecting training data for covert speech can be addressed using overt speech. The performance of covert speech can improve by employing several overt speeches.

Bioreactance assessment of cardiac output lacks reliability for the follow-up of patients with pulmonary hypertension.

Cardiac output (CO) is one of the primary prognostic factors evaluated during the follow-up of patients treated for pulmonary hypertension (PH). It is recommended that it be measured using the thermodilution technique during right heart catheterization. The difficulty to perform iterative invasive measurements on the same individual led us to consider a non-invasive option. The aims of the present study were to assess the agreement between CO values obtained using bioreactance (Starling™ SV) and thermodilution, and to evaluate the ability of the bioreactance monitor to detect patients whose CO decreased by more than 15% during follow-up and, accordingly, its usefulness for patient monitoring. A prospective cohort study evaluating the performance of the Starling™ SV monitor was conducted in patients with clinically stable PH. Sixty patients referred for hemodynamic assessment were included. CO was measured using both the thermodilution technique and bioreactance during two follow-up visits. A total of 60 PH patients were included. All datasets were available at the baseline visit (V0) and 50 of them were usable during the follow-up visit (V1). Median [IQR] CO was 4.20 l/min [3.60-4.70] when assessed by bioreactance, and 5.30 l/min [4.57-6.20] by thermodilution (p<0.001). The Spearman correlation coefficient was 0.51 [0.36-0.64], and the average deviation on Bland-Altman plot was -1.25 l/min (95% CI [-1.48-1.01], p<0.001). The ability of the monitor to detect a variation in CO of more than 15% between two follow-up measurements, when such variation existed using thermodilution, was insufficient for clinical practice (AUC = 0.54, 95% CI [0.33-0.75]).

Ultrasound Guided Measurement of Inferior Vena Cava Diameter, Common Carotid Artery Diameter versus Central Venous Pressure for Estimation of Intravascular Volume Status in Septic Shock Patients

Background: In critically ill patients, the fluid resuscitation is crucial and is the first step in treatment protocol. Invasive CVP measurement was used to guide fluid resuscitation. However, it is time consuming and invasive maneuver. Ultrasound measurement of inferior vena cave and common carotid arteries are suggest to predict the fluid response as well as CVP or even better. The current work designed to compare inferior vena cava diameter and common carotid artery diameter with central venous pressure for estimation of intravascular volume status in septic shock. Patients and Methods: The study included 60 subjects with septic shock who received vasopressor support. CVP and ultrasound were performed before and after fluid challenge test. Values of inferior vena cava and common carotid arteries were documented and compared to CVP values. This was performed after full clinical assessment by detailed clinical examination and laboratory workup. Results: The MAP was significantly increased and HR decreased after than before procedure. In addition, CVP, (inferior vena cava), ICVmax, ICV min and common carotid artery diameter (CCAD) were significantly increased, IVC CI (%) was significantly reduced after procedure than basal values. There was significant decrease of IVCmax, IVCmin and CCAD while there was significant increase of IVC CI% with lower (&lt;8) than higher (&gt; 8) CVP values. CVP was positively and significantly correlated with IVCmax, IVCmin and CCAD, while it was inversely correlated with IVC CI%. The AUC was over 0.75 for IVCmax, IVCmin and CCAD for prediction of CVP while it was lower than 0.7 for IVC CI%. These data reflected the better predictive power of IVCmax, IVCmin and CCAD. The best cutoff value was 1.35, 1.25, 10.45 and 4.15 for IVCmax, IVCmin, IVC CI% and CCAD successively. Conclusion: IVC and CCA diameters measurement by US may replace CVP measurement for estimation of intravascular volume status in septic shock patients.

Using Artificial Intelligence to Improve the Accuracy of a Wrist-Worn, Noninvasive Glucose Monitor: A Pilot Study.

Self-monitoring of glucose is important to the successful management of diabetes; however, existing monitoring methods require a degree of invasive measurement which can be unpleasant for users. This study investigates the accuracy of a noninvasive glucose monitoring system that analyses spectral variations in microwave signals. An open-label, pilot design study was conducted with four cohorts (N = 5/cohort). In each session, a dial-resonating sensor (DRS) attached to the wrist automatically collected data every 60 seconds, with a novel artificial intelligence (AI) model converting signal resonance output to a glucose prediction. Plasma glucose was measured in venous blood samples every 5 minutes for Cohorts 1 to 3 and every 10 minutes for Cohort 4. Accuracy was evaluated by calculating the mean absolute relative difference (MARD) between the DRS and plasma glucose values. Accurate plasma glucose predictions were obtained across all four cohorts using a random sampling procedure applied to the full four-cohort data set, with an average MARD of 10.3%. A statistical analysis demonstrates the quality of these predictions, with a surveillance error grid (SEG) plot indicating no data pairs falling into the high-risk zones. These findings show that MARD values approaching accuracies comparable to current commercial alternatives can be obtained from a multiparticipant pilot study with the application of AI. Microwave biosensors and AI models show promise for improving the accuracy and convenience of glucose monitoring systems for people with diabetes.

LVSP and LBBP Result in Similar or Improved LV Synchrony and Hemodynamics Compared to BVP

BackgroundThe effect of left ventricular septal myocardial pacing (LVSP) and left bundle branch pacing (LBBP) on ventricular synchrony and left ventricular (LV) hemodynamic status is poorly understood. ObjectivesThe aim of this study was to investigate the impact of LVSP and LBBP vs biventricular pacing (BVP) on ventricular electrical synchrony and hemodynamic status in cardiac resynchronization therapy patients. MethodsIn cardiac resynchronization therapy candidates with LV conduction disease, ventricular synchrony was assessed by measuring QRS duration (QRSd) and using ultra-high-frequency electrocardiography. LV electrical dyssynchrony was assessed as the difference between the first activation in leads V1 to V8 to the last from leads V4 to V8. LV hemodynamic status was estimated using invasive systolic blood pressure measurement during multiple transitions between LBBP, LVSP, and BVP. ResultsA total of 35 patients with a mean LV ejection fraction of 29% and a mean QRSd of 168 ± 24 ms were included. Thirteen had ischemic cardiomyopathy. QRSd during BVP, LVSP, and LBBP was the same, but LBBP provided shorter LV electrical dyssynchrony than BVP (−10 ms; 95% CI: −16 to −4 ms; P = 0.001); the difference between LVSP and BVP was not significant (−5 ms; 95% CI: −12 to 1 ms; P = 0.10). LBBP was associated with higher systolic blood pressure than BVP (4%; 95% CI: 2%-5%; P < 0.001), whereas LVSP was not (1%; 95% CI: 0%-2%; P = 0.10). Hemodynamic differences during LBBP and LVSP vs BVP were more pronounced in nonischemic than ischemic patients. ConclusionsUltra-high-frequency electrocardiography allowed the documentation of differences in LV synchrony between LBBP, LVSP, and BVP, which were not observed by measuring QRSd. LVSP provided the same LV synchrony and hemodynamic status as BVP, while LBBP was better than BVP in both.

Evaluation of a new transpalpebral tonometer for self-measuring intraocular pressure.

We developed a novel transpalpebral self-tonometer called the TapEye tonometer (TET) based on palpation of the upper eyelid. Our goal was to evaluate a method for improving the accuracy of measuring intraocular pressure (IOP) through the eyelid. Participants underwent standardized training by technicians and were required to be able to use the TET for study inclusion. Subsequently, a noncontact tonometer and Goldmann applanation tonometer (GAT) were used. All participants were instructed to measure their IOPs using the three tonometers at baseline (visit 1) and at 1 month (visit 2). At visit 2, the corrected IOP value measured by the TET (c-TET) was calculated using the difference between the TET and GAT measurements obtained at visit 1. No significant correlations were found between the TET and GAT measurements at any visit, but the correlation between the c-TET and GAT measurements at visit 2 was significant. The mean difference between the c-TET and GAT measurements was 0.4 ± 3.7 mmHg in the right eye and 0.5 ± 3.4 mmHg in the left eye. After correcting the IOP based on the difference between the TET and GAT measurements at the initial visit, the corrected IOP value of the TET was correlated with that of the GAT at the second visit. The TET has the potential to address an unmet need by providing a tool for minimally invasive IOP measurements. Clinical trial registration number: jRCTs032220268.

Comparing the compensatory reserve metric obtained from invasive arterial measurements and photoplethysmographic volume-clamp during simulated hemorrhage.

The compensatory reserve metric (CRM) is a novel tool to predict cardiovascular decompensation during hemorrhage. The CRM is traditionally computed using waveforms obtained from photoplethysmographic volume-clamp (PPGVC), yet invasive arterial pressures may be uniquely available. We aimed to examine the level of agreement of CRM values computed from invasive arterial-derived waveforms and values computed from PPGVC-derived waveforms. Sixty-nine participants underwent graded lower body negative pressure to simulate hemorrhage. Waveform measurements from a brachial arterial catheter and PPGVC finger-cuff were collected. A PPGVC brachial waveform was reconstructed from the PPGVC finger waveform. Thereafter, CRM values were computed using a deep one-dimensional convolutional neural network for each of the following source waveforms; (1) invasive arterial, (2) PPGVC brachial, and (3) PPGVC finger. Bland-Altman analyses were used to determine the level of agreement between invasive arterial CRM values and PPGVC CRM values, with results presented as the Mean Bias [95% Limits of Agreement]. The mean bias between invasive arterial- and PPGVC brachial CRM values at rest, an applied pressure of -45mmHg, and at tolerance was 6% [-17%, 29%], 1% [-28%, 30%], and 0% [-25%, 25%], respectively. Additionally, the mean bias between invasive arterial- and PPGVC finger CRM values at rest, applied pressure of -45mmHg, and tolerance was 2% [-22%, 26%], 8% [-19%, 35%], and 5% [-15%, 25%], respectively. There is generally good agreement between CRM values obtained from invasive arterial waveforms and values obtained from PPGVC waveforms. Invasive arterial waveforms may serve as an alternative for computation of the CRM.

Low left ventricular outflow tract velocity time integral predicts normotensive shock in patients with acute pulmonary embolism

Abstract Funding Acknowledgements None. Introduction In patients with intermediate-risk acute pulmonary embolism (PE) outcomes vary widely, with mortality rates ranging from 3-15% and rates of normotensive shock up to 30%.1-3 Current risk models don't fully capture those at higher risk and identify patients who may benefit from advanced therapies. The left ventricular outflow tract (LVOT) velocity time integral (VTI), a surrogate marker of cardiac output, has been associated with increased mortality in acute PE.4 Our objective was to determine the association between LVOT VTI and its predictive value in identifying normotensive shock in this patient population. Methods Patients who underwent percutaneous mechanical thrombectomy (MT) between August 2020 and March 2023 at a large academic public hospital were considered for the study. Inclusion criteria comprised of normotensive patients (SBP ≥ 90 mmHg) with invasive measures of cardiac index (CI). VTI was obtained by pulsed wave doppler at the LVOT in either the apical 3 or apical 5 chamber view. The primary outcome was the association between LVOT VTI and normotensive shock and a cut off of 15 cm was used to examine this association based on prior studies.4 Results A total of 49 patients with intermediate-risk PE underwent MT, 16 patients had incomplete data, resulting in a final cohort of 33 patients (mean age: 57 ± 13yrs; 38% female). Patients with LVOT VTI of &amp;lt;15 cm were younger (53 vs 62 years p=0.02), had lower systolic blood pressure at presentation (122 vs 134 mmHg, p=0.047), higher heart rate (112.6 vs 96.2 beats/min, p=0.008), a higher composite shock score (CPES) (5 vs 3, p=0.012), lower cardiac index (1.9 vs 3.1 L/min/m2, p&amp;lt;0.001), a higher PASP (61.4 vs 48.9 mmHg, p=0.018), and higher rates of elevated lactate (90% vs 42%, p=0.027). LVOT VTI threshold of &amp;lt;15cm effectively identified patients with normotensive shock (90% vs 8% p&amp;lt;0.001). There was no statistically significant difference in the rates of saddle emboli, left ventricular ejection fraction, sPESI and BOVA scores in patients with VTI above or below 15cm. In patients with normotensive shock, 19/20 (95%) had LVOT VTI ≤ 15cm with a median of 13 cm (IQR 12, 14) (Figure). In patients without normotensive shock, 11/13 (84%) had LVOT VTI &amp;gt;15 with a median of 18 (IQR 17, 21). The area under the curve for LVOT VTI ≤ 15 cm in predicting normotensive shock was 0.89. The sensitivity and specificity of LVOT VTI ≤ 15 cm in predicting normotensive shock was 91.6% and 90.4% respectively. Conclusion Our study suggests that LVOT VTI is a reliable surrogate for cardiac output in patients with acute PE and can effectively identify those in the intermediate-risk group who are at risk for normotensive shock. A LVOT VTI &amp;lt;15cm may identify intermediate-risk patients at higher risk for hemodynamic decompensation and further studies are needed to evaluate whether these patients would benefit from upfront catheter-based therapies.

McConnell's sign predicts normotensive shock in patients with acute pulmonary embolism

Abstract Funding Acknowledgements None. Background Patients with intermediate-risk acute pulmonary embolism (PE) have mortality rates ranging from 3-15%, with incidence of normotensive shock occurring in up to 30% of patients.1-3 Existing risk models often fall short in accurately identifying those at heightened risk of normotensive shock and those who might derive benefit from advanced therapeutic interventions including catheter based therapies. Diagnosis of normotensive shock typically necessitates invasive right heart catheterization, however, McConnell's sign has been associated with higher risk PEs.4 Consequently, our objective was to assess the relationship between McConnell's sign, a readily available bedside point-of-care tool, and its predictive value in identifying normotensive shock in patients diagnosed with acute intermediate-risk PE. Methods All patients with intermediate-risk PE who underwent percutaneous mechanical thrombectomy (MT) between August 2020 and April 2023 at a large academic public hospital were included in the study. Normotensive shock was defined as patients with systolic blood pressure (SBP) ≥ 90mmHg in the absence of vasopressor support with pre-procedural invasive measures of CI £ 2.2 L/min/m2 and clinical evidence of hypoperfusion (i.e. elevated lactate, oliguria). The primary outcome was the association between McConnell’s sign and normotensive shock. Results A total of 49 patients with intermediate-risk PE underwent MT, 9 patients had incomplete data, resulting in a final cohort of 40 patients (mean age: 57 ± 13 years; 45% female). A total of 29/40 (72.5%) patients had McConnell’s sign. Patients with McConnell’s sign had higher rates of obesity (59% vs 18% p=0.02), higher heart rate (114 vs 99 beats/min, p=0.008), higher rates of elevated lactate (86% vs 55%, p=0..038), lower cardiac index (1.9 vs 3.1 L/min/m2, p=0.003), and higher rates of normotensive shock (76% vs 27%, p=0.005). There was no statistically significant difference in age, sex, race, rates of saddle emboli, left ventricular ejection fraction, pulmonary artery systolic pressure, presenting blood pressure, sPESI and composite pulmonary embolism shock score scores in patients with or without McConnell’s sign. In patients with normotensive shock, 22/25 (88%) had McConnell’s sign and only 53.3% had McConnell’s sign without shock (Figure 1). Patients with McConnell’s sign had an increased odds (OR 8.38, CI: 1.73-40.53; p=0.008, AUC 0.70, 95% CI: 0.56-0.85) of normotensive shock. Conclusion This is the first study to suggest that McConnell’s sign can effectively identify those in the intermediate-risk group who are at risk for normotensive shock. Further studies are needed to validate this non-invasive technique that can be rapidly performed at bedside with high reproducibility and whether it can help risk-stratify patients who may benefit from advanced PE therapies.

Chronic Microglia Activation Is Suffcient to Induce Significant Increase in Pulmonary Pressure

Introduction: Microglia, the primary resident immune cells of the brain, can be activated very early in disease. Our previous studies have indicated that microglia activation and neuroinflammation in autonomic brain areas were associated with pulmonary hypertension (PH). Furthermore, we also demonstrated that the attenuation of neuroinflammation by either pharmacological inhibition of microglia with minocycline or genetic disruption of neuro-microglia interaction by CX3CR1 depletion led to protection against pulmonary hypertension. Nuclear factor kappa-light-chain-enhancer of activated B cells (NF-κB) plays a crucial role in controlling inflammatory responses via gene expression regulation. NF-κB signaling in microglia triggers a distinct neuroinflammatory response with increased migration, phagocytosis, and release of proinflammatory cytokines such as IL-6, IL-1β and TNF-α. Thus, in this study we investigated if targeted microglia activation was suffcient to initiate the cascade of events that may contribute to the development of pulmonary hypertension. Study Objective: This study was designed to test the hypothesis that chronic microglia activation is suffcient to induce pulmonary hypertension Methods To evaluate the specific contribution of microglia pro-inflammatory activation to modulate pulmonary pressure, we used a mouse line with inducible expression of the Cre-recombinase directed to the Cx3cr1 promoter crossed with IKKcaflox-flox mice. The breeding scheme CX3CR1creER/+: IKKcaflox-flox allows the Cre-recombination events, as induced by tamoxifen administration, to occur in many myeloid cell types. However, when recombination is followed by at least six weeks of time for the repopulation of cells with high turnover rates, this protocol promotes a relatively selective activation of NF-κB signaling on microglia. First, CX3CR1creER/+:IKKcaflox-flox mice (n=14) were injected with tamoxifen or oil (control) (i.p.) daily at 150 mg/kg body weight for six consecutive days. After 8 weeks, invasive RVSP measurement was performed, and tissues were harvested for following analysis. Briefly, a Millar catheter is inserted into the right ventricle. Ventricle pressures and ECG were recorded and analyzed. PH phenotype also included the measurement of the Fulton index (RV:LV+S) and histological and flow cytometry analyses of lung. Data was collected in two separate experiments with similar results. Results: Activation of NF-κB on microglia was suffcient to induce a slight but significant increase in right ventricular systolic pressure (RVSP), surrogate of pulmonary pressure (RVSP: Tamoxifen: 26.23 ± 0.5861 mmHg; Oil: 23.16 ± 0.4339 mmHg (p = 0.001)), and increased right heart contractility (+dP/dt: Tamoxifen: 1586± 90.18 mmHg/s; Oil: 1250 ± 65.39 mmHg/s (p = 0.0092). Interestingly, activation of NF-κB on microglia also induced a significant increase in lung infiltration of monocytic myeloid-derived suppressor cells (Mo-MDSC, CD11b+Ly6ChiLy6G−) and granulocytic-like MDSCs (PMN-MDSC, CD11b+Ly6Clo Ly6G+). Conclusion: Activation of NF-κB on microglia was suffcient to induce a significant increase in pulmonary pressure and increase lung infiltration of myeloid-derived suppressor cells associated with smooth muscle cell proliferation in pulmonary hypertension. K99 HL165026, R01 HL142776. This is the full abstract presented at the American Physiology Summit 2024 meeting and is only available in HTML format. There are no additional versions or additional content available for this abstract. Physiology was not involved in the peer review process.