Search results for "HMI"

Instantaneous Transfer Entropy for the Study of Cardiovascular and Cardio-Respiratory Nonstationary Dynamics

2017

Objective: Measures of transfer entropy (TE) quantify the direction and strength of coupling between two complex systems. Standard approaches assume stationarity of the observations, and therefore are unable to track time-varying changes in nonlinear information transfer with high temporal resolution. In this study, we aim to define and validate novel instantaneous measures of TE to provide an improved assessment of complex nonstationary cardiorespiratory interactions. Methods: We here propose a novel instantaneous point-process TE (ipTE) and validate its assessment as applied to cardiovascular and cardiorespiratory dynamics. In particular, heartbeat and respiratory dynamics are characteriz…

Information transfer in QT-RR dynamics: Application to QT-correction

2018

ABSTRACTThe relation between the electrical properties of the heart and the beating rate is essential for the heart functioning. This relation is central when calculating the “corrected QT interval” — an important measure of the risk of potentially lethal arrhythmias. We use the transfer entropy method from information theory to quantitatively study the mutual dynamics of the ventricular action potential duration (the QT interval) and the length of the beat-to-beat (RR) interval. We show that for healthy individuals there is a strong asymmetry in the information transfer: the information flow from RR to QT dominates over the opposite flow (from QT to RR), i.e. QT depends on RR to a larger e…

Lorcainide; II. Plasma concentration-effect relationship

1979

Five-year follow-up after catheter ablation of persistent atrial fibrillation using the stepwise approach and prognostic factors for success.

2015

Background— In the meantime, catheter ablation is widely used for the treatment of persistent atrial fibrillation (AF). There is a paucity of data about long-term outcomes. This study evaluates (1) 5-year single and multiple procedure success and (2) prognostic factors for arrhythmia recurrences after catheter ablation of persistent AF using the stepwise approach aiming at AF termination. Methods and Results— A total of 549 patients with persistent AF underwent de novo catheter ablation using the stepwise approach (2007–2009). A total of 493 patients were included (Holter ECGs ≥every 6 months). Mean follow-up was 59±16 months with 2.1±1.1 procedures per patient. Single and multiple procedu…

Towards Improved Healthcare Performance: Examining Technological Possibilities and Patient Satisfaction with Wireless Body Area Networks

2009

Published version of an article from the journal: Journal of Medical Systems. he original publication is available at Springerlink. http://dx.doi.org/10.1007/s10916-009-9291-8 This paper investigates the benefits of using less intrusive wireless technologies for heart monitoring. By replacing well established heart monitoring devices (i.e. Holter) with wireless ECG based Body Area Networks (BAN), improved healthcare performance can be achieved, reflected in (1) high quality ECG recordings during physical activities and (2) increased patient satisfaction. A small scale clinical trial was conducted to compare both technologies and the results illustrate that the wireless ECG monitor was able …

Arrhythmia profile in acromegaly.

1992

In a controlled study, the cardiac involvement and arrhythmia profile of 32 patients with acromegaly were correlated with endocrine parameters (somatomedine C, growth hormone), clinical score and duration of the disease. Data were compared with those of 50 controls free of cardiac disease. Stress ECG, 24 h Holter monitoring and echocardiography were performed. Supraventricular premature complexes occurred no more often in acromegalics than in controls. Both prevalence and severity of ventricular arrhythmia, however, were significantly higher in patients compared to controls (P less than 0.01). 15/32 (48%) acromegalic patients had complex ventricular arrhythmias (Lown III-IV) as compared wit…

Effect of intravenous flecainide on atrial vulnerability in man.

1985

Sixteen patients were investigated by means of programmed atrial stimulation at 2 different driving rates: 100/min and 120/min. All patients had an increased atrial vulnerability at both driving rates. After the administration of intravenous flecainide (1 mg/kg bodyweight as a bolus, followed by the same amount infused over a period of 20 minutes), the increased vulnerability was abolished in 11 and 9 patients, respectively. In the remaining patients the rate of induced atrial tachyarrhythmia decreased. These findings correlate with a significant prolongation of the effective refractory period of the right atrium and a corresponding significant shortening of its relative refractory period. …

Effect of intravenous flecainide on atrial vulnerability in man.

1983

Sixteen patients were investigated by means of programmed atrial stimulation at two different driving rates: 100 and 120/min. All patients had an increased atrial vulnerability at both driving rates. After intravenous flecainide application (1 mg/kg body weight as a bolus followed by the same amount given by infusion over a period of 20 min) the increased vulnerability was abolished in 11 and 9 patients respectively. In the remaining patients the rate of induced atrial tachyarrhythmia decreased. These findings correlate with a significant prolongation of the effective refractory period of the right atrium and a significant shortening of the relative refractory period of the right atrium. It…

Increased prevalence of cardiac arrhythmias and transient episodes of myocardial ischemia in hypertensives with left ventricular hypertrophy but with…

1997

To evaluate the behavior of cardiac arrhythmias (CA) and transient episodes of myocardial ischemia (TEMI), in relation to the circadian pattern of blood pressure in patients suffering from arterial hypertension, with or without echocardiographically ascertained left ventricular hypertrophy (LVH), we studied 128 patients, 87 men (M) and 41 women (F), aging from 21 to 76 years, subdivided into two groups: Group I, including 66 patients with LVH (45 M and 21 F; mean age of 53.7 ± 9.1 years; Group II, including 62 patients without LVH ( 42 M and 20 F; mean age of 49.7 ± 9.5 years). Office blood pressure (OBP) as well as nighttime ambulatory blood pressure (ABP) were higher in patients with LVH …

Haemodynamic effects of a single intravenous dose of lorcainide in patients with heart disease

1980

The cardiovascular effects of a single i.v. dose (2 mg/kg over 5 min) of lorcainide were studied in 14 patients with heart disease. In the haemodynamic part of the study (6 patients), the aortic and pulmonary systolic, diastolic and mean pressures, left ventricular systolic and end-diastolic pressures, cardiac output and the rate of rise of left ventricular pressure were measured before and for 30 min after administration of the drug. Lorcainide produced a slight and short-lasting decrease in the aortic and pulmonary systolic pressures, and all other pressure values remained unchanged. The cardiac output and systemic vascular resistance were not altered by lorcainide. It consistently depres…