Bayesian inference of multi-sensors impedance cardiography for detection of aortic dissection

Purpose This paper aims to introduce a non-invasive and convenient method to detect a life-threatening disease called aortic dissection. A Bayesian inference based on enhanced multi-sensors impedance cardiography (ICG) method has been applied to classify signals from healthy and sick patients. Design/methodology/approach A 3D numerical model consisting of simplified organ geometries is used to simulate the electrical impedance changes in the ICG-relevant domain of the human torso. The Bayesian probability theory is used for detecting an aortic dissection, which provides information about the probabilities for both cases, a dissected and a healthy aorta. Thus, the reliability and the uncertainty of the disease identification are found by this method and may indicate further diagnostic clarification. Findings The Bayesian classification shows that the enhanced multi-sensors ICG is more reliable in detecting aortic dissection than conventional ICG. Bayesian probability theory allows a rigorous quantification of all uncertainties to draw reliable conclusions for the medical treatment of aortic dissection. Originality/value This paper presents a non-invasive and reliable method based on a numerical simulation that could be beneficial for the medical management of aortic dissection patients. With this method, clinicians would be able to monitor the patient’s status and make better decisions in the treatment procedure of each patient.

Cross-Entropy Learning for Aortic Pathology Classification of Artificial Multi-Sensor Impedance Cardiography Signals

An aortic dissection, a particular aortic pathology, occurs when blood pushes through a tear between the layers of the aorta and forms a so-called false lumen. Aortic dissection has a low incidence compared to other diseases, but a relatively high mortality that increases with disease progression. An early identification and treatment increases patients’ chances of survival. State-of-the-art medical imaging techniques have several disadvantages; therefore, we propose the detection of aortic dissections through their signatures in impedance cardiography signals. These signatures arise due to pathological blood flow characteristics and a blood conductivity that strongly depends on the flow field, i.e., the proposed method is, in principle, applicable to any aortic pathology that changes the blood flow characteristics. For the signal classification, we trained a convolutional neural network (CNN) with artificial impedance cardiography data based on a simulation model for a healthy virtual patient and a virtual patient with an aortic dissection. The network architecture was tailored to a multi-sensor, multi-channel time-series classification with a categorical cross-entropy loss function as the training objective. The trained network typically yielded a specificity of (93.9±0.1)% and a sensitivity of (97.5±0.1)%. A study of the accuracy as a function of the size of an aortic dissection yielded better results for a small false lumen with larger noise, which emphasizes the question of the feasibility of detecting aortic dissections in an early state.

568 Echocardiography and impedance cardiography as determinants of successful slow Levosimendan infusion in patients with acute advanced heart failure

Aims Despite new therapeutic options, patients with heart failure (HF) still progress to advanced stage. Among new therapeutic options, Levosimendan was recently approved in order to treat patients hospitalized for acute decompensated heart failure (ADHF) with severe systolic dysfunction. The pharmacological effects of Levosimendan consist of inotropy, vasodilatation, and cardioprotection through the increase of calcium sensitivity. These effects should be monitored with echocardiography and in particular with speckle tracking and tri-dimensional echocardiography which appear to be useful in LV systolic function detection and monitoring. In this study we aim to evaluate the effect of slow infusion of Levosimendan on the non-invasive measurement of cardiac output, the speckle tracking parameters and the tri-dimensional echocardiography measurements in advanced ADHF patients. Methods and results This is a prospective observational study evaluating Levosimendan efficacy through advanced echocardiography. We enrolled 11 patients with diagnosis of ADHF who respect the recent ESC criteria of ‘advanced heart failure’. Patients underwent to blood sample examination to measure electrolytes, creatinine, and NTproBNP. Patients underwent to advanced echocardiography examination (performed for each patient pre- and post-Levosimendan infusion) with tri-dimensional echocardiography and global longitudinal strain assessment. Furthermore patients underwent to non-invasive cardiac output and cardiac index collection through impedance cardiography pre- and post-Levosimendan infusion. All patients were followed for 30 days after discharge for all cause of mortality and HF re-hospitalization. A total of 11 patients affected by advanced ADHF were included in this study. Mean age was 73.8 ± 4.7 years. 72.7% (n 8) patients were men. 81.9% (n 9) of patients recognize ischaemic heart disease as HF etiology. At admission mean systolic arterial pressure was 100 ± 17 mmHg, mean NTproBNP was 24 445 ± 12 194 pg/ml and mean serum creatinine was 1.55 ± 0.84 mg/dl. At tri-dimensional echocardiography mean LV ejection fraction (LVEF) was 19.7 ± 5.7% and at bi-dimensional echocardiography mean tricuspid anular plane systolic excursion (TAPSE) and pulmonary arterial systolic pressure (PASP) were, respectively, 12.5 ± 2.7 mm and 48 ± 16 mmHg. Mean LV global longitudinal strain (GLS) was −3.0 ± 1.8. Mean furosemide in-hospital infusion was 306 ± 102 mg/die and mean urine output 1436 ± 496 ml. None developed significant ventricular or supraventricular arrhythmias. All patients were treated with betablockers during infusion. At 30 days of follow-up two patients died and 1 patient was re-hospitalized. Evaluating the differences among our variables pre- and post-Levosimendan infusion, we found that NTproBNP was significantly reduced post-Levosimendan infusion (P = 0.01). Among ICG non-invasive measurement, we found significant differences in stroke volume (SV) and cardiac output (CO) in terms of significant improvement (P = 0.001 for both). Analysing tri-dimensional echocardiography variables, we observed a significant improvement of LVEF (P = 0.003), SV (P = 0.03) and 3-D LV GLS (P = 0.002). Furthermore, we observed a significant reduction in end-systolic volume (ESV) post-Levosimendan infusion (P = 0.02). Among bi-dimensional echocardiography measurements, there was a significant reduction in end-diastolic diameter of right ventricle (EDDRV) and in B-lines count (respectively, P = 0.02 and P = 0.002). Moreover, we observed a significant improvement in TAPSE (P = 0.003) and in LV GLS (P = 0.004). Conclusions Our study showed that slow Levosimendan infusion (12.5 mg at velocity of 0.05–1 mcg/kg/min) without bolus could be considered in advanced ADHF patients to improve cardiac performance without severe adverse events. ICG and echocardiography in-hospital evaluation seemed to be necessary to understand treatment success and patients status improvement as well as cardiac function benefit.

Cushing’s Disease: Assessment of Early Cardiovascular Hemodynamic Dysfunction With Impedance Cardiography

BackgroundCushing’s disease is a rare condition associated with a high cardiovascular risk and hypercortisolemia-related hemodynamic dysfunction, the extent of which can be assessed with a noninvasive method, called impedance cardiography. The standard methods for hemodynamic assessment, such as echocardiography or ambulatory blood pressure monitoring may be insufficient to fully evaluate patients with Cushing’s disease; therefore, impedance cardiography is being currently considered a new modality for assessing early hemodynamic dysfunction in this patient population. The use of impedance cardiography for diagnosis and treatment of Cushing’s disease may serve as personalized noninvasive hemodynamic status assessment and provide a better insight into the pathophysiology of Cushing’s disease. The purpose of this study was to assess the hemodynamic profile of Cushing’s disease patients and compare it with that in the control group.Material and MethodsThis observational prospective clinical study aimed to compare 54 patients with Cushing’s disease (mean age 41 years; with 64.8% of this population affected with arterial hypertension) and a matched 54-person control group (mean age 45 years; with 74.1% of this population affected with arterial hypertension). The hemodynamic parameters assessed with impedance cardiography included the stroke index (SI), cardiac index (CI), systemic vascular resistance index (SVRI), velocity index (VI), (ACI), Heather index (HI), and thoracic fluid content (TFC).ResultsThe Cushing’s disease group was characterized by a higher diastolic blood pressure and a younger age than the control group (82.9 vs. 79.1 mmHg, p=0.045; and 41.1 vs. 44.9 years, p=0.035, respectively). Impedance cardiography parameters in the Cushing’s disease group showed: lower values of SI (42.1 vs. 52.8 ml/m2; p ≤ 0.0001), CI (2.99 vs. 3.64 l/min/m2; p ≤ 0,0001), VI (42.9 vs. 52.1 1/1000/s; p=0.001), ACI (68.7 vs. 80.5 1/100/s2; p=0,037), HI (13.1 vs. 15.2 Ohm/s2; p=0.033), and TFC (25.5 vs. 27.7 1/kOhm; p=0.006) and a higher SVRI (2,515 vs. 1,893 dyn*s*cm-5*m2; p ≤ 0.0001) than those in the control group.ConclusionsCushing’s disease is associated with significantly greater vasoconstriction and left ventricular systolic dysfunction. An individual assessment with impedance cardiography may be useful in Cushing’s disease patients in order to identify subclinical cardiovascular complications of chronic hypercortisolemia as potential therapeutic targets.