Impedance Cardiography Research Articles

Low Caloric Intake Confers Cardiovascular Protection and Improves Functional Capacity Without Affecting Immunological Response in Sedentary Older Adults.

Aging is characterized by a decline in the cardiovascular hemodynamic response, which may be aggravated by undernutrition. However, no study has evaluated whether low caloric intake may affect cardiovascular hemodynamics and its possible relation with functional capacity and immune response in older adults. Sixty-one older adults of both genders were enrolled in this study and were classified as normocaloric (n = 18) and hypocaloric (n = 43). All volunteers were evaluated for cardiovascular hemodynamics using impedance cardiography (PhysioFlow®); functional capacity by the 1' sit-to-stand test with SpO2 monitoring; whole-blood analysis using an automated hematocytometer (Sysmex®); and levels of IL-6, TNF-alpha, IL-10, and Klotho by ELISA. The hypocaloric group presented impaired functional capacity, measured by a reduced number of sit-to-stand repetitions (p < 0.0251) and impaired delta of SpO2 (p < 0.0307). In contrast, the hypocaloric group presented an improved stroke volume (p < 0.0352), systemic vascular resistance (p < 0.0075), and systemic vascular resistance index (p < 0.0184). In addition, no changes were observed in the whole-blood analysis (p > 0.05) or for IL-6 (p > 0.05), TNF-alpha (p < 0.05), IL-10 (p < 0.05), and Klotho (p > 0.05). A long-term hypocaloric diet in eutrophic older adults' resulted in an enhanced cardiovascular hemodynamic response but was associated with reduced functional capacity without changes in the immune response.

Pharmacologic treatment of hypertension guided by non-invasive haemodynamics in primary care improves blood pressure control

Abstract Background Current guidelines on hypertension (HTN) provide blood pressure (BP) targets and therapeutic algorithms but ignore the potential to treat individual patients according to their haemodynamic profile. We have shown that use of non-invasive haemodynamic information obtained by impedance cardiography (ICG) can improve BP control in the primary care setting. Purpose To investigate whether improved rates of BP control by matching patients’ non-invasive haemodynamics to specific pharmacologic treatments and increasing patient engagement translates into improved clinical outcome measures. Methods Electronic medical records (EMR) were obtained for 14,698 patients from two US primary care groups between 2014 and 2023. ICG was done when BP exceeded 140/90 mmHg. Haemodynamic measurements included mean arterial pressure (MAP), cardiac index (CI), cardiac power index (CPI), total peripheral resistance index (TPRI), stroke index (SI) and heart rate (HR) (Figure 1). Haemodynamic ICG profiles were classified as: Vasoconstriction, Hyperdynamic, or Mixed pattern. Printed clinical decision support (CDS) tools and later an EMR integrated CDS application were used to communicate recommendations to physicians. Printed reports were shared with patients to increase their engagement. Pharmacological therapy was tailored based on haemodynamic information. Rates of successful BP treatment and the occurrence of myocardial infarction (MI) or stroke were tracked through the EMR. Results Of 14,698 patients, 50% were women, 17% were Black and 17% were aged 18-49 years, 45% aged 50-69 years, and 38% age ≥ 70 years. A total of 21,246 ICGs were performed classifying patients as Vasoconstriction 47%, Hyperdynamic with high heart rate (HR) or high stroke index (SI) 24%, and Mixed Haemodynamic (combination of Vasoconstriction and Hyperdynamic) 29% (Figure 1). Demographic features were not strongly associated with haemodynamic classification. Within 2-3 years of inclusion, &amp;gt;85% of patient achieved BP control (&amp;lt;140/90 mmHg), which was sustained during follow-up. Over a median (IQR) follow-up of 8 (2016-2023) years, there were 14 (5) MI and 34 (16) strokes. These event rates appear to be lower than those reported in other large cohorts of patients with HTN. Conclusions Treating patients with HTN according to their individual haemodynamic profile is associated with high rates of BP control. Further analysis will determine whether the rates of MI, stroke and death are lower than expected based on the patients baseline risk profile.Haemodynamic Status (ICG Test Results)

Cardiac morphology and function in patients with primary biliary cholangitis (PBC) without cirrhosis

Abstract Background Primary biliary cholangitis (PBC) is a chronic, autoimmune liver disease causing destruction of the small intralobular bile ducts in the liver. PBC patients can also develop extrahepatic manifestations. Though patients with PBC have often elevated levels of serum lipids, data concerning cardiac involvement is inconsistent and cardiovascular changes may be underdiagnosed. Purpose The purpose of the study was to assess cardiac morphology and function in patients with PBC without cirrhosis and comparison with control subjects. Methods We studied 52 females with PBC, and included in the analysis 22 females without cirrhosis, who were compared to 44 healthy female controls matched for age (53.4 ± 9.2 and 51 ± 8.3 yrs., respectively, p =0.312). Transthoracic echocardiography (TTE) was performed with the analysis of the left ventricular (LV) global longitudinal strain (GLS) and myocardial work. Additionally, impedance cardiography was conducted, with the analysis of the autonomic function using BRS (baroreceptor sensitivity), HRV (heart rate variability) and BPV (blood pressure variability). Results Systolic blood pressure (SBP), diastolic blood pressure (DBP) and heart rate (HR) differed between PBC and control group (128 ± 17 mmHg vs. 116 ± 11 mmHg, p=0.007 and 78± 12 mmHg vs. 75 ± 8 mmHg, p=0.024, and 73.5 ± 12 bpm vs. 71 ± 8 bpm , p=0.024, respectively). PBC group had larger diameter of the cardiac chambers when adjusted for body surface area (BSA), including left atrium (LA/BSA) and right ventricle (RV/BSA), as well as left ventricular mass (LWMI) and relative wall thickness (RWT), with no difference in the left ventricular end diastolic diameter (LVEDD/BSA). LV ejection fraction (EF) measured by bi-plane Simpson method was higher in PBC group. LV diastolic function parameters (E/A, E/e’) differed in patients with PBC when compared with controls, however, without signs of diastolic dysfunction. LV GLS indices (GLSAVG, GLSLAX, GLS4C, GLS2C) were significantly higher in PBC group, as well as global myocardial work indexes: global myocardial work (GWI) and global constructive work (GCW). Non-invasive autonomic assessment showed lower BPV in patients with PBC without cirrhosis, but no differences in baroreceptor sensitivity and HRV. Impedance cardiography did not show differences between both groups. Conclusion Our study shows that PBC patients without cirrhosis are characterized by remodeling and functional changes of the heart, when compared to age-matched controls. These changes could imply hyperkinetic circulation even before the development of cirrhosis in PBC patients.

Signal-morphology impedance cardiography is a non-invasive tool to predict responses to exercise based cardiac rehabilitation in chronic heart failure patients

Abstract Background All the studies and meta-analyses showed beneficial effects of the exercise based cardiac rehabilitation (ExBCR) on peak value of oxygen uptake (VO2peak) in patient with chronic heart failure (CHF). It is widely recognized that changes in VO2peak induced by training (ΔVO2peak) have a prognostic value. A 5.0% increase in ΔVO2peak has been associated with a significant clinical improvement1. However, 20 to 30 % of CHF are non-responders to ExBCR. The Signal-Morphology Impedance Cardiography (SM-ICGTM) technology has allowed previous researchers to show the role of cardiac output (CO) on DVO2peak2. CO responses may be partly attributed to the peak ejection flow velocity that can explain the impaired response to ExBCR. Purpose The study aimed to establish whether SM-ICGTM is an appropriate technology to predict responses to ExBCR in CHF patients. Methods A retrospective study was conducted on 65 CHF patients (LVEF: 29.0±8.3%). All patients performed a cardiopulmonary exercise test (CPET) on bicycle to determine ventilation (VE) and VO2peak before and after 20 ExBCR sessions. In addition, stroke volume (SV), heart rate (HR), and CO were continuously monitored by SM-ICGTM (PhysioFlow® Lab1). The value of peak ejection flow velocity, so called CTi by the manufacturer, was calculated as the peak of the first mathematical derivative over the time of the impedance waveform during the systole and measured by PhysioFlow® throughout the test. For the analysis of training response patients were divided in two groups: the normal CTi profile which was characterized by an initial increase followed by a plateau until CPET exhaustion, and the abnormal CTi response if CTi decreased at the onset of CPET or increased then decreased before exhaustion. Statistical analyses were performed with JASP. The significant level was set at p value &amp;lt; 0.05 for 95% confidence interval. Results Our study population consisted in 32 patients who presented a normal CTi profile and 33 with an abnormal CTi profile. As shown in Table 1, no significant difference was found at baseline between both groups. ExBCR induced significant changes in VO2peak even if 29 % patients were non-responders. Patients with normal CTi profile presented a greater DVO2peak compared to patients with abnormal CTi profile (28 ± 30 vs. 14 ± 19 %, p&amp;lt;0.01). 78% of patients with normal CTi profile versus only 64% of patients with abnormal CTi profile were ExBCR responders. The logistic regression showed that patient with normal CTi profile were 3.3 time more likely to present a ΔVO2peak ≥ 5%. Conclusion Exercise CTi profiles determined by SM-ICGTM prove to be an interesting tool to help predicting ExBCR responses in CHF patients and maybe highlighting the hemodynamic determinants of VO2 responses to exercise training.

Research on motion impedance cardiography de-noising method based on two-step spectral ensemble empirical mode decomposition and canonical correlation analysis

Impedance cardiography (ICG) is essential in evaluating cardiac function in patients with cardiovascular diseases. Aiming at the problem that the measurement of ICG signal is easily disturbed by motion artifacts, this paper introduces a de-noising method based on two-step spectral ensemble empirical mode decomposition (EEMD) and canonical correlation analysis (CCA). Firstly, the first spectral EEMD-CCA was performed between ICG and motion signals, and electrocardiogram (ECG) and motion signals, respectively. The component with the strongest correlation coefficient was set to zero to suppress the main motion artifacts. Secondly, the obtained ECG and ICG signals were subjected to a second spectral EEMD-CCA for further denoising. Lastly, the ICG signal is reconstructed using these share components. The experiment was tested on 30 subjects, and the results showed that the quality of the ICG signal is greatly improved after using the proposed denoising method, which could support the subsequent diagnosis and analysis of cardiovascular diseases.

Echocardiographic and Impedance Cardiography Analysis of Left Ventricular Diastolic Function in Acromegaly Patients

Echocardiographic and Impedance Cardiography Analysis of Left Ventricular Diastolic Function in Acromegaly Patients

Signal-morphology impedance cardiography is a non-invasive tool for predicting responses to exercise-based cardiac rehabilitation

Exercise based cardiac rehabilitation (EBCR) is highly beneficial to improve the outcome and quality of life of patients suffering from cardiac diseases. Most of the time, it increases cardiorespiratory and muscle capacity. However, not all patients show these benefits because of the high variability in their response to EBCR. In this context, the present study aimed to determine the potential of a specific parameter, the contractility index (CTi), to predict the response of cardiac patients to EBCR during the baseline cardiopulmonary exercise test (CPET) using signalmorphology based impedance cardiography (SM-ICGTM). Methods: 58 cardiac patients (50 ± 10 years old) were prospectively enrolled in this study and admitted to EBCR, and 57 could be analyzed. Results: The patients were finally divided into 2 groups based on their CTi response during CPET (normal versus altered or compromised). After a EBCR program there was an overall increase in peak oxygen uptake (VO2peak) (+13.6 ± 22.9 %). EBCR induced a higher VO2peak improvement in patients with normal CTi response compared to their counterparts with altered or compromised CTi profiles (+24.1 ± 21.4 % vs. + 3.36 ± 19.5 %, p5% improvement in VO2peak (odds ratio 8.7, p = 0.012) and benefit from EBCR than the patients in the altered or compromised CTi group. Conclusion: This study demonstrated the predictive potential of the CTi profile during the baseline CPET to anticipate the response to EBCR in cardiac patients.

Correlation Analysis of Activity Levels and Risk Factors in Patients with Stroke: Variations in Cardiac Function According to the Longshi Scale.

This study examined the link between physical activity levels, as measured by the Longshi Scale, and cardiac function and N-terminal pro-brain natriuretic peptide (NT-proBNP) levels in stroke patients, aiming to find correlations with stroke risk factors. The study involved 123 apoplexy patients divided into four groups based on the Longshi Scale: bedridden (31), domestic (32), community (30), and health (30). Clinical data was collected, and hemodynamic assessments were performed using impedance cardiography. Cardiac output time index (CTI) and estimated ejection fraction (EF est) were significantly reduced in both the domestic and community groups compared to the health group (P < 0.05), while diastolic arterial blood pressure (DABP) and systemic vascular resistance index (SVRi) were increased. In the bedridden group, stroke volume (SV), cardiac output (CO), CTI, left cardiac work index (LCWi), and EF est were all lower compared to the health group (P < 0.05), with SVRI and NT-proBNP levels being higher. Additionally, the bedridden group exhibited lower SV, CO, DABP, LCWi, CTI, and EF est when compared to the domestic and community groups (P < 0.05), but higher end-diastolic filling rate (EDFR) and NT-proBNP levels. The Longshi Scale grading positively correlated with SV (r = 0.536, P < 0.01), and NT-proBNP, EF, and cognitive dysfunction were found to be associated with activity levels in stroke patients. The Longshi Scale correlates with cardiac function indicators like NT-proBNP and EF, and can help identify stroke patients at risk of cardiac dysfunction. Moreover, cognitive dysfunction was identified as a significant factor influencing the range of activity in patients with stroke.

Haemodynamics of hyperthyroidism: increased cardiac work and findings related to vasodilatation.

Hyperthyroidism increases cardiovascular morbidity and mortality, but the underlying mechanisms are not fully understood. In this study we compared non-invasive haemodynamics between 20 hyperthyroid patients and 60 euthyroid subjects. The measurements were performed median 6 days after the initiation of antithyroid medication when the patients were still hyperthyroid. Three controls matched for age, sex, body mass index, and smoking status were selected for each patient. Recordings were performed during rest and passive head-up tilt using whole-body impedance cardiography, radial pulse wave analysis, and finger blood pressure measurements. Systolic and diastolic blood pressures in the aorta and radial artery were similar in hyperthyroid and euthyroid subjects, while finger blood pressure was 16/12 mmHg lower in hyperthyroidism (p<0.001). Pulse wave velocity and aortic pulse pressure were similar, but radial pulse pressure was ~5 mmHg higher in hyperthyroidism (p=0.040) due to augmented amplification (p=0.045). Systemic vascular resistance was reduced (-18%), whereas heart rate (+19 beats/min), cardiac index (+28%), and left cardiac work (+31%) were increased in hyperthyroidism (p<0.001). Subendocardial viability ratio, reflecting the balance between coronary perfusion and pressure load, was reduced by 19% in hyperthyroidism (p<0.001). Compared with euthyroid subjects, hyperthyroid patients presented with reductions in systolic and diastolic finger blood pressures (p<0.001), and higher increase in heart rate (p=0.014) during upright posture. Hyperthyroid patients exhibited hyperdynamic circulation, reduced vascular resistance, reduced peripheral but not central blood pressure, and higher pulse pressure amplification. Furthermore, left cardiac workload was increased in parallel with unfavourable changes in coronary perfusion conditions.

Prognostic Value of Transthoracic Impedance Cardiography, Amino-Terminal Pro-B-Type Natriuretic Peptide Levels, The Six-Minute Walk Test, and Chest X-Ray in Elderly Patients with Chronic Heart Failure: A Comparative Study in Lithuania.

BACKGROUND Chronic heart failure (CHF) is a complex clinical syndrome associated with frequent, recurrent, and long-term hospitalizations. This study from a single center in Lithuania aimed to evaluate outcomes in 87 elderly patients hospitalized with CHF. The methods used included comparing transthoracic impedance cardiography (ICG), amino-terminal pro-B-type natriuretic peptide (NT-proBNP) levels, the six-minute walk test (6MWT), and dilatation of the right pulmonary artery on chest X-ray (dRPAcXR). MATERIAL AND METHODS The study sample consisted of 87 patients (49 men and 38 women). All subjects underwent 6MWT and ICG in addition to the standard CHF tests. The median duration of the follow-up was 23 months. Data about patient outcomes were gathered from the National Medical Record Database. RESULTS By multivariate Cox proportional analysis, thoracic fluid content (TFC) ≥41.1 1/kΩ (hazard ratio [HR] 32.354, 95% confidence interval [CI] 2.758-379.488), NT-proBNP ≥332.0 pmol/L (HR 4.739, 95% CI 1.656-13.559), 6-minute walk distance (6MWD) ≤203.5 m (HR 3.975, 95% CI 1.002-15.770), and dRPAcXR (HR 5.555, 95% CI 1.714-18.005) were associated with a poor prognosis in CHF patients (all P<0.05). The correlations between ICG and 6MWD and other non-invasive diagnostic tests examined in this study were weak to moderate. CONCLUSIONS TFC ≥41.1 1/kΩ, NT-proBNP ≥332.0 pmol/L, 6MWD ≤203.5 m, and dRPAcXR had a combined prognostic value in predicting cardiovascular death in patients with CHF. Therefore, these parameters may be of value in the assessment of the diagnosis and prognosis in this patient cohort.

Impact of age and sex on heart rate variability and cardiometabolic function in healthy adults

Heart rate variability (HRV) is a non-invasive measure of cardiac autonomic function. A clearer understanding as to whether resting autonomic function represented by HRV could be associated with changes in peak exercise cardiac function remains unanswered. This study evaluated the effect of age and sex on HRV, cardiometabolic function, and determined the correlation between HRV and cardiac function in healthy individuals. Sixty-eight participants (age range: 19–78 years old, females, n = 28) were recruited. Participants were stratified according to age (younger (<40 years old, n = 43, females, n = 17) and older age groups (>55 years old, n = 25, females, n = 11). Firstly, HRV was measured using non-invasive impedance cardiography method (TaskForce, CNSystems, Graz, Austria) and recorded at rest (supine position) for 30 min. HRV measures included: low frequency (LF) power, high frequency (HF) power (both normalised (nu) and absolute units (ms2)) and LF/HF ratio. Participants then completed a progressive cardiorespiratory exercise test using a semi-recumbent cycle ergometer (Corival, Lode, Groningen, Netherlands) with simultaneous gas exchange measurements (Metalyzer 3B, Cortex, Leipzig, Germany). Cardiac function was represented by peak exercise cardiac power output index (CPO). After controlling for body mass index and physical activity, males had significantly higher mean vales of RR interval than females (males = 1043 ± 165; females = 952 ± 128 ms, p = 0.02). There was no significant main effect of age, sex or their interaction on any of the other HRV measures. In younger and older females, resting RR interval had a significant relationship with peak exercise CPO (young females: r = 0.54, p < 0.05; old females: r = 0.81, p < 0.01). There was also a significant relationship between resting HF power and peak exercise CPO in younger females (r = 0.70, p < 0.01). HRV was not influenced by age but RR interval was associated with peak exercise CPO in females regardless of age, whilst HF power was significantly associated with CPO in younger females only.

Acromegaly: The Relationship between Hemodynamic Profiles Assessed via Impedance Cardiography and Left Ventricular Systolic Function Assessed via Echocardiography.

Background/Objectives: Acromegaly-induced prolonged exposure to growth hormone and insulin-like growth factor 1 may have significant cardiovascular effects. The purpose of this study was to assess the relationship between hemodynamic parameters measured via impedance cardiography (ICG) and parameters of systolic left ventricular function measured via echocardiography in patients with acromegaly. Methods: The observational cohort study included 33 patients with newly diagnosed acromegaly, with a mean age of 47 years and without significant comorbidities. Correlation analysis (Spearman's rank correlation coefficient R) was performed on parameters obtained by ICG and left ventricular systolic function parameters obtained by echocardiography. ICG assessment included indices of (1) cardiac function as a pump: stroke volume index (SI), cardiac index (CI), Heather index (HI), velocity index (VI), and acceleration index (ACI); (2) afterload: systemic vascular resistance index (SVRI) and total arterial compliance index (TACI); and (3) thoracic fluid content (TFC). Echocardiographic examinations evaluated left ventricular ejection fraction (LVEF) and global longitudinal strain (GLS). Results: A lower LVEF was associated with a lower SI (R = 0.38; p = 0.03) and a higher SVRI (R = -0.35; p = 0.046), whereas lower GLS was associated with lower SI (R = 0.43; p = 0.02), CI (R = 0.62; p < 0.001), VI (R = 0.59; p < 0.001), ACI (R = 0.38; p = 0.048), HI (R = 0.59; p < 0.001), and TACI (R = 0.50; p = 0.006) and a higher SVRI (R = -0.59; p < 0.001). No significant correlation was observed between either LVEF or GLS and TFC. Conclusions: In patients with acromegaly, poorer echocardiographic parameters of left ventricular systolic function are associated with impaired function of the heart as a pump and higher afterload as assessed via ICG.

Thoracic Fluid Content as an Indicator of High Intravenous Diuretic Requirements in Hospitalized Patients with Decompensated Heart Failure.

Background: The main cause of hospitalization in patients with heart failure is hypervolemia. Therefore, the primary treatment strategy involves diuretic therapy using intravenous loop diuretics to achieve decongestion and euvolemia. Some patients with acutely decompensated heart failure (ADHF) do not respond well to diuretic treatment, which may be due to diuretic resistance (DR). Such cases require high doses of diuretic medications and combination therapy with diuretics of different mechanisms of action. Although certain predisposing factors for diuretic resistance have been identified (such as hypotension, type 2 diabetes, impaired renal function, and hyponatremia), further research is needed to identify other pathophysiological markers of DR. Objective: This study aims to identify admission markers that can predict a high requirement for intravenous diuretics in hospitalized patients with decompensated heart failure. Methods: This study included 102 adult patients hospitalized for ADHF. At admission, patients underwent clinical assessment, laboratory parameter evaluation (including the N-terminal prohormone of brain natriuretic peptide [NT-proBNP] levels), and hemodynamic assessment using impedance cardiography (ICG). Hemodynamic profiles were based on the use of parameters such as heart rate (HR), blood pressure (BP), and thoracic fluid content (TFC) as markers of volume status. The analysis included 97 patients with documented doses of intravenous diuretic use. Patients were stratified into two groups based on median diuretic consumption (equivalent to 540 mg of intravenous furosemide): the high-loop diuretic utilization (LDU) group (n = 49) and the low-LDU group (n = 48). Results: Compared to low-LDU patients, high-LDU patients had greater thoracic fluid content at admission, both quantitatively (37.4 ± 8.1 vs. 34.1 ± 6.9 kOhm-1; p = 0.024) and qualitatively (TFC ≥ 35 kOhm-1: 59.2% vs. 33.3%; p = 0.011). Anemia was more common in the high-LDU group (67.4% vs. 43.8%; p = 0.019), as was elevated NT-proBNP (≥median of 3952 pg/mL: 60.4% vs. 37.5%; p = 0.024). High LDU was associated with a significantly longer hospitalization duration (12.9 ± 6.4 vs. 7.0 ± 2.6 days; p < 0.001). Logistic regression analysis identified anemia, elevated NT-proBNP, and high TFC as predictors of high LDU (HR: 2.65, 2.54, and 2.90, respectively). In a multifactorial model, only high TFC remained an independent predictor (HR: 2.60, 95% CI 1.04-6.49; p = 0.038). Conclusions: TFC was the sole independent admission marker of a high requirement for intravenous diuretics in patients hospitalized for decompensated heart failure. An objective assessment of volume status by impedance cardiography may support intensive personalized decongestion therapy.

Enhancing cardiovascular health monitoring: Simultaneous multi-artery cardiac markers recording with flexible and bio-compatible AlN piezoelectric sensors

Continuous monitoring of cardiovascular parameters like pulse wave velocity (PWV), blood pressure wave (BPW), stiffness index (SI), reflection index (RI), mean arterial pressure (MAP), and cardio-ankle vascular index (CAVI) has significant clinical importance for the early diagnosis of cardiovascular diseases (CVDs). Standard approaches, including echocardiography, impedance cardiography, or hemodynamic monitoring, are hindered by expensive and bulky apparatus and accessibility only in specialized facilities. Moreover, noninvasive techniques like sphygmomanometry, electrocardiography, and arterial tonometry often lack accuracy due to external electrical interferences, artifacts produced by unreliable electrode contacts, misreading from placement errors, or failure in detecting transient issues and trends. Here, we report a bio-compatible, flexible, noninvasive, low-cost piezoelectric sensor for continuous and real-time cardiovascular monitoring. The sensor, utilizing a thin aluminum nitride film on a flexible Kapton substrate, is used to extract heart rate, blood pressure waves, pulse wave velocities, and cardio-ankle vascular index from four arterial pulse sites: carotid, brachial, radial, and posterior tibial arteries. This simultaneous recording, for the first time in the same experiment, allows to provide a comprehensive cardiovascular patient's health profile. In a test with a 28-year-old male subject, the sensor yielded the SI = 7.1 ± 0.2 m/s, RI = 54.4 ± 0.5 %, MAP = 86.2 ± 1.5 mmHg, CAVI = 7.8 ± 0.2, and seven PWVs from the combination of the four different arterial positions, in good agreement with the typical values reported in the literature. These findings make the proposed technology a powerful tool to facilitate personalized medical diagnosis in preventing CVDs.

O84 BLOOD PRESSURE MEASUREMENT VIA IMPEDANCE CARDIOGRAPHY: AN ARTIFICIAL INTELLIGENCE BASED PROOF-OF-CONCEPT

Objective: Accurate blood pressure (BP) measurement is crucial for the diagnosis, risk assessment, treatment decision-making, and monitoring of cardiovascular diseases. Unfortunately, the gold-standard, cuff-based BP measurement suffer from inaccuracies and discomfort. As a result, continuous, cuff-less, and non-invasive BP assessment methods are merging as promising alternatives. This study is the first to comprehensively assess impedance cardiography (ICG) for Machine Learning enabled BP measurement. Methods: We analysed ICG data from 71 young and healthy adults. Nine different Machine Learning algorithms were evaluated for their BP estimation performance. Accuracy measures comprised mean difference, standard deviation, Limits of Agreement, mean absolute error, and root mean squared error. Additionally, the B-Score was calculated to evaluate the “true”, relative performance of the best-performing model. Results: The Multi-Linear Regression model showed the highest performance (mean difference = -0.01, r = 0.82) for systolic BP. The Support Vector Regressor model achieved the best results (mean difference = 0.15, r = 0.51) for diastolic BP. Both models exhibited positive B-Scores, indicative of their predictive capability. All tested models’ estimations correlated with both systolic and diastolic reference BP (r &gt; 0.72 / r &gt; 0.34, p &lt; 0.001). Conclusion: The study highlights the potential of ICG based Machine Learning algorithms for accurately estimating arterial BP. Such algorithms can provide accurate and continuous BP data. This offers the possibility of enhancing patient care, timely diagnostics, and treatment decision-making. Our approach is especially promising for post-surgical and intensive care environments.

Non-invasive hemodynamic monitoring during initiation of positive airway pressure treatment in patients with obstructive sleep apnea: a feasibility study

BackgroundThe association of obstructive sleep apnea (OSA) with cardiovascular morbidity has been repeatedly reported in numerous studies and argues for treatment initiation even in the absence of significant day time sleepiness. While the long-term consequences of positive airway pressure (PAP) treatment on OSA related comorbidities like secondary hypertension are based on substantial clinical evidence, less is known about the immediate hemodynamic effects.MethodsThis study tried to investigate the impact of PAP treatment on different hemodynamic parameters in 48 patients with OSA by extending the standard polysomnographic assessment with non-invasive hemodynamic monitoring using impedance cardiography (ICG). On two consecutive nights under diagnostic and therapeutic conditions, polysomnographic and hemodynamic data were acquired. In addition, we subdivided the participants according to their treatment related change in stroke volume (SV) and assigned the hemodynamic measurements to the corresponding sleep stage.ResultsComparing both conditions, a non-statistically significant decrease in SV and cardiac output (CO) was observed for all participants. Treatment initiation was associated with a statistically significant prolongation of the pre-ejection period (PEP) for the entire study population (p = 0.001) and the subgroup with decreasing SV (p = 0.008). In addition, systolic blood pressure (SBP) (p = 0.026) and pulse pressure (PP) (p = 0.041) were lowered significantly for patients with a therapeutically reduced SV under treatment conditions. A higher BMI (p = 0.020) and a more pronounced reduction of the respiratory distress index (RDI) (p = 0.030) and the arousal-index (p = 0.021) were observed for patients with decreasing SV. Correlational analysis revealed a negative relationship between the diagnostic values for both SBP (r=-0.324, p = 0.025) and PP (r=-0.407, p = 0.004) with the change in SV and a positive correlation with the change of the SBP (r = 0.317, p = 0.028) for all participants.ConclusionsTo conclude, our results indicate that treatment with a PAP device in patients with OSA can lead to a decrease in SV which is associated with a lowering of the SBP. This may be caused by a reduced sympathetic tone due to less respiratory events and an improved sleep profile.

ICG signal denoising based on ICEEMDAN and PSO-VMD methods.

Impedance cardiography (ICG) plays a crucial role in clinically evaluating cardiac systolic and diastolic functions, along with various other cardiac parameters. However, its accuracy heavily depends on precisely identifying feature points reflecting cardiac function. Moreover, traditional signal processing techniques used to mitigate random noise and breathing artifacts may inadvertently distort the amplitude and temporal characteristics of ICG signals. To address this issue, this study investigates a noise and artifact elimination method based on Improved Complete Ensemble Empirical Mode Decomposition with Adaptive Noise (ICEEMDAN) and Particle Swarm Optimization-based Variational Mode Decomposition Algorithm (PSO-VMD). The goal is to preserve the amplitude and temporal features of ICG signals to ensure accurate feature point extraction and computation of associated cardiac parameters. Comparative analysis with signal processing methods employing various wavelet families and Ensemble Empirical Mode Decomposition (EEMD) in ICG signal processing applications reveals that the proposed method achieves superior signal-to-noise ratio (SNR) and lower root-mean-square error (RMSE), while demonstrating enhanced correlation and waveform consistency with the original signal.

Hemodynamics and cerebral oxygenation during acute exercise in moderate normobaric hypoxia and with concurrent cognitive task in young healthy males.

The present investigation aimed to study the cardiovascular responses and the cerebral oxygenation (Cox) during exercise in acute hypoxia and with contemporary mental stress. Fifteen physically active, healthy males (age 29.0±5.9 years) completed a cardiopulmonary test on a cycle ergometer to determine the workload at their gas exchange threshold (GET). On a separate day, participants performed two randomly assigned exercise tests pedaling for 6 min at a workload corresponding to 80% of the GET: (1) during normoxia (NORMO), and (2) during acute, normobaric hypoxia at 13.5% inspired oxygen (HYPO). During the last 3 min of the exercise, they also performed a mental task (MT). Hemodynamics were assessed with impedance cardiography, and peripheral arterial oxygen saturation and Cox were continuously measured by near-infrared spectroscopy. The main results were that both in NORMO and HYPO conditions, the MT caused a significant increase in the heart rate and ventricular filling rate. Moreover, MT significantly reduced (74.8±5.5vs. 62.0±5.2 A.U.) Cox, while the reaction time (RT) increased (813.3±110.2vs. 868.2±118.1ms) during the HYPO test without affecting the correctness of the answers. We conclude that in young, healthy males, adding an MT during mild intensity exercise in both normoxia and acute moderate (normobaric) hypoxia induces a similar hemodynamic response. However, MT and exercise in HYPO cause a decrease in Cox and an impairment in RT.

Development of an Intelligent Multi-Parameter Sleep Diagnosis and Analysis System

Sleep disordered breathing (SDB) is a common sleep disorder with an increasing prevalence. The current gold standard for diagnosing SDB is polysomnography (PSG), but existing PSG techniques have some limitations, such as long manual interpretation times, a lack of data quality control, and insufficient monitoring of gas metabolism and hemodynamics. Therefore, there is an urgent need in China's sleep clinical applications to develop a new intelligent PSG system with data quality control, gas metabolism assessment, and hemodynamic monitoring capabilities. The new system, in terms of hardware, detects traditional parameters like nasal airflow, blood oxygen levels, electrocardiography (ECG), electroencephalography (EEG), electromyography (EMG), electrooculogram (EOG), and includes additional modules for gas metabolism assessment via end-tidal CO 2 and O 2 concentration, and hemodynamic function assessment through impedance cardiography. On the software side, deep learning methods are being employed to develop intelligent data quality control and diagnostic techniques. The goal is to provide detailed sleep quality assessments that effectively assist doctors in evaluating the sleep quality of SDB patients.

Effects of acute creatine supplementation on cardiac and vascular responses in older men; a randomized controlled trial

In the recent years creatine has been shown promising results in patients with neurodegenerative diseases, myopathies and dystrophies. Cardiovascular diseases could be another pathology that can benefit from creatine supplementation, considering the influence on the risk factors associated with the development of cardiovascular diseases including reduction in chronic inflammation, and improved control of hyperglycemia and dyslipidemia The aim of the present study was to investigate the impact of short-term creatine supplementation on cardiac and vascular health in older adults. Males between the ages of 55-80 were randomly assigned to three groups: creatine, placebo and control. Creatine or placebo was provided for 7-day supplementation, at a dose of 20g/day. Testing was performed at the same time of the day at baseline and on the eighth day. Vascular responses were assessed using an arterial pulse wave velocity equipment, while cardiac assessment was performed using an impedance cardiography device. The placebo group was older (71.1±8.2yr) compared to creatine (61.4±5.2yr) and control (62.5±7.1yr). Cardio-ankle vascular index improved just in the creatine group (8.7±0.5 to 8.2±0.5, p=0.03). While the upstroke time of the placebo and control groups did not change after 7 days, the creatine group had a nonsignificant reduction, 178.9±26.5ms to 158.4±28.6ms, p=0.07. Similar tendency was seen with the systolic blood pressures, while the placebo and control did not change, the creatine group showed nonsignificant improvement, especially on the right, 144.0±12.7mmHg to 136.1±13.4mmHg, p=0.08. All three groups had similar responses in stroke volume (p=0.61), contractility index (p=0.64) and ejection fraction (p=0.72). In older adults, acute creatine supplementation can positively affect vascular parameters of arterial stiffness and atherosclerosis. Creatine supplementation has the potential to serve as a potent adjuvant in the management of CVD for older adults. clinicaltrials.gov; ID: NCT05329480.