Comparison of cardiac output estimates obtained from the Antares oscillometric pulse wave analysis algorithm and from Doppler transthoracic echocardiography.

BACKGROUND: In cardiology, cardiac output (CO) is an important parameter for assessing cardiac function. While invasive thermodilution procedures are the gold standard for CO assessment, transthoracic Doppler echocardiography (TTE) has become the established method for routine CO assessment in daily clinical practice. However, a demand persists for non-invasive approaches, including oscillometric pulse wave analysis (PWA), to enhance the accuracy of CO estimation, reduce complications associated with invasive procedures, and facilitate its application in non-intensive care settings. Here, we aimed to compare the TTE and oscillometric PWA algorithm Antares for a non-invasive estimation of CO. METHODS: Non-invasive CO data obtained by two-dimensional TTE were compared with those from an oscillometric blood pressure device (custo med GmbH, Ottobrunn, Germany) using the integrated algorithm Antares (Redwave Medical GmbH, Jena, Germany). In total, 59 patients undergoing elective cardiac catheterization for clinical reasons (71±10 years old, 76% males) were included. Agreement between both CO measures were assessed by Bland-Altman analysis, Student's t-test, and Pearson correlations. RESULTS: The mean difference in CO was 0.04 ± 1.03 l/min (95% confidence interval for the mean difference: -0.23 to 0.30 l/min) for the overall group, with lower and upper limits of agreement at -1.98 and 2.05 l/min, respectively. There was no statistically significant difference in means between both CO measures (P = 0.785). Statistically significant correlations between TTE and Antares CO were observed in the entire cohort (r = 0.705, P<0.001) as well as in female (r = 0.802, P<0.001) and male patients (r = 0.669, P<0.001). CONCLUSIONS: The oscillometric PWA algorithm Antares and established TTE for a non-invasive estimation of CO are highly correlated in male and female patients, with no statistically significant difference between both approaches. Future validation studies of the Antares CO are necessary before a clinical application can be considered.

Age, sex, endurance capacity, and chronic heart failure affect central and peripheral factors of oxygen uptake measured by non-invasive and continuous technologies: support of pioneer work using invasive or non-continuous measures.

Introduction: It is known that maximum oxygen uptake depends on age, sex, endurance capacity, and chronic heart failure. However, due to the required invasive or often applied non-continuous approaches, less is known on underlying central and peripheral factors. Thus, this study aimed to investigate the effects of age, sex, endurance capacity, and chronic heart failure on non-invasively and continuously measured central and peripheral factors of oxygen uptake. Methods: 15 male children (11 ± 1 years), 15 male (24 ± 3 years) and 14 female recreationally active adults (23 ± 2 years), 12 male highly trained endurance athletes (24 ± 3 years), and 10 male elders (59 ± 6 years) and 10 chronic heart failure patients (62 ± 7 years) were tested during a cardiopulmonary exercise test on a cycling ergometer until exhaustion for: blood pressure, heart rate, stroke volume, cardiac output, cardiac power output, vastus lateralis muscle oxygen saturation, and (calculated) arterio-venous oxygen difference. For the non-invasive and continuous measurement of stroke volume and muscle oxygen saturation, bioreactance analysis and near-infrared spectroscopy were used, respectively. A two-factor repeated measure ANOVA and partial eta-squared effect sizes (ηp2) were applied for statistical analyses at rest, 80, and 100% of oxygen uptake. Results: For the age effect, there were statistically significant group differences for all factors (p ≤ .033; ηp2≥.169). Concerning sex, there were group differences for all factors (p ≤ .010; ηp2≥.223), except diastolic blood pressure and heart rate (p ≥ .698; ηp2≤.006). For the effect of endurance capacity, there were no group differences for any of the factors (p ≥ .065; ηp2≤.129). Regarding chronic heart failure, there were group differences for the heart rate and arterio-venous oxygen difference (p ≤ .037; ηp2≥.220). Discussion: Age, sex, endurance capacity, and chronic heart failure affect central and peripheral factors of oxygen uptake measured by non-invasive and continuous technologies. Since most of our findings support pioneer work using invasive or non-continuous measures, the validity of our applied technologies is indirectly confirmed. Our outcomes allow direct comparison between different groups serving as reference data and framework for subsequent studies in sport science and medicine aiming to optimise diagnostics and interventions in athletes and patients.

Non-invasively measured central and peripheral factors of oxygen uptake differ between patients with chronic heart failure and healthy controls.

BACKGROUND: Maximum oxygen uptake is an established measurement of diagnosing chronic heart failure and underlies various central and peripheral factors. However, central and peripheral factors are little investigated, because they are usually measured invasively. The aim of this study was to compare non-invasively measured central and peripheral factors of oxygen uptake between patients with chronic heart failure and healthy controls. METHODS: Ten male patients with heart failure with reduced ejection fraction (62 ± 4 years; body mass index: 27.7 ± 1.8 kg/m2; ejection fraction: 30 ± 4%) and ten male healthy controls (59 ± 3 years; body mass index: 27.7 ± 1.3 kg/m2) were tested for blood pressure, heart rate, stroke volume, cardiac output, and cardiac power output (central factors) as well as muscle oxygen saturation of the vastus lateralis and biceps brachii muscle (peripheral factors) during an incremental cycling test. Stroke volume and muscle oxygen saturation were non-invasively measured by a bioreactance analysis and near-infrared spectroscopy, respectively. Additionally, a maximum isometric strength test of the knee extensors was conducted. Magnitude-based inferences were computed for statistical analyses. RESULTS: Patients had a likely to most likely lower oxygen uptake, mean arterial pressure, and heart rate at maximum load as well as very likely lower isometric peak torque. Contrary, patients had a possibly to likely higher stroke volume and muscle oxygen saturation of the vastus lateralis muscle at maximum load. Differences in cardiac output, cardiac power output, and muscle oxygen saturation of the biceps brachii muscle at maximum load were unclear. CONCLUSIONS: Non-invasively measured central and peripheral factors of oxygen uptake differ between patients with chronic heart failure and healthy controls. Therefore, it is promising to measure both types of factors in patients with chronic heart failure to optimize the diagnosis and therapy.

Increased levels of laminin and collagen type VI may reflect early remodelling in patients with acute myocardial infarction.

OBJECTIVE: The development of left ventricular remodelling (LVR) after acute myocardial infarction (AMI) is a predictor of heart failure and mortality. The extracellular matrix (ECM) is highly susceptible to ischaemic injury. Laminin and collagen type VI (CVI) contribute to ECM formation in the infarct zone. To determine whether these markers can be detected in blood samples, we measured laminin and CVI in patients with AMI and control subjects. METHODS: A total of 60 patients scheduled for coronary angiography and 31 patients with AMI were included. We subdivided the patients into three groups: (1) AMI, (2) stable coronary artery disease (CAD) and (3) exclusion of CAD. Laminin and CVI serum concentrations were recorded using the ELISA-technique. RESULTS: Laminin was significantly higher in patients with AMI than in subjects with stable CAD (36.5 vs. 23.9, P < 0.01) or without CAD (36.5 vs. 24.6 ng/ml, P < 0.05). CVI-levels were significantly elevated in patients with AMI compared to subjects without CAD (7.5 ng/ml vs. 5.4 ng/ml, P < 0.05) or stable CAD (7.5 ng/ml vs. 5.7 ng/ml, P = 0.01). Laminin and CVI were significantly higher in patients with severely reduced left ventricular function. Laminin and CVI values were significantly correlated (r = 0.6). CONCLUSION: Our data suggest that laminin and CVI serum levels can be potential surrogate parameters of ECM remodelling after AMI. We hypothesize that serum laminin reflects early ECM-remodelling involved in the process of postischaemic tissue degradation and repair, and CVI may be a marker of collagen denaturation and shifts in the collagen phenotype ratios.