A Fast Multimodal Ectopic Beat Detection Method Applied for Blood Pressure Estimation Based on Pulse Wave Velocity Measurements in Wearable Sensors.

Automatic detection of ectopic beats has become a thoroughly researched topic, with literature providing manifold proposals typically incorporating morphological analysis of the electrocardiogram (ECG). Although being well understood, its utilization is often neglected, especially in practical monitoring situations like online evaluation of signals acquired in wearable sensors. Continuous blood pressure estimation based on pulse wave velocity considerations is a prominent example, which depends on careful fiducial point extraction and is therefore seriously affected during periods of increased occurring extrasystoles.

Lagged segmented Poincaré plot analysis for risk stratification in patients with dilated cardiomyopathy.

The objectives of this study were to introduce a new type of heart-rate variability analysis improving risk stratification in patients with idiopathic dilated cardiomyopathy (DCM) and to provide additional information about impaired heart beat generation in these patients. Beat-to-beat intervals (BBI) of 30-min ECGs recorded from 91 DCM patients and 21 healthy subjects were analyzed applying the lagged segmented Poincaré plot analysis (LSPPA) method. LSPPA includes the Poincaré plot reconstruction with lags of 1-100, rotating the cloud of points, its normalized segmentation adapted to their standard deviations, and finally, a frequency-dependent clustering.

Blood pressure variability as sign of autonomic imbalance in patients with idiopathic dilated cardiomyopathy.

Background: The problem of identifying idiopathic dilated cardiomyopathy (IDC) patients who are at risk of sudden death is still unsolved. The presence of autonomic imbalance in patients with IDC might predict sudden death and tachyarrhythmic events. The aim of this study was to analyze the suitability of blood pressure variability (BPV) compared to heart rate variability (HRV) for noninvasive risk stratification in IDC patients.

Electrocardiologic and related methods of non-invasive detection and risk stratification in myocardial ischemia: state of the art and perspectives.

Background: Electrocardiographic methods still provide the bulk of cardiovascular diagnostics. Cardiac ischemia is associated with typical alterations in cardiac biosignals that have to be measured, analyzed by mathematical algorithms and allegorized for further clinical diagnostics. The fast growing fields of biomedical engineering and applied sciences are intensely focused on generating new approaches to cardiac biosignal analysis for diagnosis and risk stratification in myocardial ischemia.

Detection of U wave activity in healthy volunteers by high-resolution magnetocardiography.

Introduction: The purpose of our study was to prove the existence of the U wave using magnetocardiograms (MCGs).

Methods: The 31-channel MCGs of 25 healthy volunteers were recorded. The onset of the U wave was defined by newly developed spatial correlation analysis; and the end, by different approaches.

Unsuccessful alloplastic esophageal replacement with porcine small intestinal submucosa.

In general, there is no perfect method for esophageal replacement under consideration of the numerous associated risks and complications. The aim of this study was to examine a new material--small intestinal submucosa (SIS)--in alloplastic esophageal replacement. We implanted tubular SIS prosthesis about 4 cm in length in the cervical esophagus of 14 piglets (weight 9-13 kg).

Magnetocardiography based spatiotemporal correlation analysis is superior to conventional ECG analysis for identifying myocardial injury.

Electrocardiogram (ECG) particular from tiny, non Q-wave myocardial infarction may lack striking infarct pattern. Spatiotemporal correlation analysis (SCA) of multichannel magnetocardiogram (MCG) is a high-resolution "magnifying glass" to analyze homogeneity of repolarization. SCA involves full 4D spatiotemporal information to identify abnormalities as empirically done by eye in conventional ECG-but on an advanced level of analysis.

Peripheral arterial disease alters heart rate variability in cardiovascular patients.

Background: Autonomic regulation analysis is useful in risk stratification of ventricular tachycardia and sudden cardiac death in chronic heart failure (CHF). Heart rate variability (HRV) reflects the condition of autonomic regulation. For analyzing the autonomic control the whole cardiovascular system has to be considered.

Stress testing in coronary artery disease by Magnetic Field Imaging: a 3D current distribution model.

Objective: Magnetic field imaging (MFI) combines depolarization and repolarization registration of the cardiac electromagnetic field with a 3D current distribution model. An interesting application for MFI is the possibility to detect myocardial ischemia under stress.

Methods: Using a new reconstruction technique, it is possible to generate a pseudo-current distribution on the epicardial surface: the comparison of the time evolution of such current distributions at rest and under stress shows difference in coronary artery disease (CAD).

Comparison of nonlinear methods symbolic dynamics, detrended fluctuation, and Poincare plot analysis in risk stratification in patients with dilated cardiomyopathy.

Dilated cardiomyopathy (DCM) has an incidence of about 20100 000 new cases per annum and accounts for nearly 10 000 deaths per year in the United States. Approximately 36% of patients with dilated cardiomyopathy (DCM) suffer from cardiac death within five years after diagnosis. Currently applied methods for an early risk prediction in DCM patients are rather insufficient.

Spatiotemporal correlation analyses: a new procedure for standardisation of DC magnetocardiograms.

There is a lack of standard methods for the analysis of magnetocardiograms (MCGs). MCG signals have a shape similar to the ECG (P wave, QRS complex, T wave). High-quality multichannel recordings can indicate even slight disturbances of de- and repolarisation.

Low HRV entropy is strongly associated with myocardial infarction.

Heart rate variability (HRV) is a marker of autonomous activity in the heart. An important application of HRV measures is the stratification of mortality risk after myocardial infarction. Our hypothesis is that the information entropy of HRV, a non-linear approach, is a suitable measure for this assessment.

Multivariate and multidimensional analysis of cardiovascular oscillations in patients with heart failure.

Within 5 years of first diagnosis, nearly 60% of patients with heart failure (HF) suffer from cardiac death. Early diagnosis of HF and reliable risk prediction are still required. Therefore, the objective of this study was to develop a parameter set for enhanced risk stratification in HF patients.

Altered autonomic cardiac control predicts restenosis after percutaneous coronary intervention.

Background: Early and late restenosis in up to 30% remains a major problem for long-term success after percutaneous coronary intervention (PCI). Compared to bare metal stents, the use of drug-eluting stents reduces restenosis below 10%, but implant coasts have to be considered. In restenosis noninvasive testing lacks diagnostic power.

Vortex shaped current sources in a physical torso phantom.

Recent studies reported differential information in human magnetocardiogram and in electrocardiogram. Vortex currents have been discussed as a possible source of this divergence. With the help of physical phantom experiments, we quantified the influence of active vortex currents on the strength of electric and magnetic signals, and we tested the ability of standard source localization algorithms to reconstruct vortex currents.

Iohexol contrast medium induces QT prolongation in amiodarone patients.

Aims: Amiodarone is widely used in ventricular tachyarrhythmias and atrial fibrillation, known to prolong QT-intervals. Concurrent administration of drugs prolonging QT- time can induce life-threatening ventricular tachyarrhythmia.

Methods: QT-interval changes following use of Iohexol contrast-medium for coronarangiography were observed comparing 21 patients taking long-term amiodarone therapy with 21 controls not taking amiodarone or QT-prolonging drugs retrospectively.