Impendance cardiography

This study examined autonomic and hemodynamic processes associated with the development of naturally occurring vasovagal responses. Data from a study assessing the physiological correlates of an intervention to reduce vasovagal responses in blood donors were examined (Ditto et al., 2009). Ninety-eight participants were assigned randomly to groups that either practiced applied tension or not. Dependent variables included ratings of vasovagal symptoms, heart rate, blood pressure, and other parameters derived from ambulatory impedance cardiography...

AIMS: Early recognition of impending decompensation and timely intervention may prevent heart failure (HF) hospitalization. We investigated the performance of OptiVol® intrathoracic fluid monitoring for the prediction of HF events in chronic HF patients newly implanted with a device (implantable cardioverter-defibrillator with or without cardiac resynchronization therapy). METHODS AND RESULTS: SENSE-HF was a prospective, multi-centre study that enrolled 501 patients...

PURPOSE OF REVIEW: Heart failure is among the leading causes of morbidity and mortality in the United States. In recent years, implantable devices have been developed that aim to predict impending heart failure events in time to prevent clinical decompensation. This review focuses on these emerging technologies and the implications they hold for the future of heart failure management. RECENT FINDINGS: Many devices have recently been studied in patients with heart failure...

BACKGROUND: Chronic heart failure is associated with frequent hospitalisations which are often due to volume-overload decompensation. Monitoring of intrathoracic impedance, measured from an implanted device, can detect increases in pulmonary fluid retention early and facilitate timely treatment interventions. OBJECTIVE: The DOT-HF trial is designed to investigate if ambulatory monitoring of intrathoracic impedance together with other device-based diagnostic information can reduce morbidity and mortality in patients with chronic heart failure who are treated with cardiac resynchronization therapy (CRT) and/or an implantable defibrillator (ICD)...

BACKGROUND: Hospitalizations due to decompensation are a frequent problem in treating patients with congestive heart failure (CHF). Continuous impedance measurement via implantable devices may detect pulmonary fluid accumulation due to worsening CHF. An acoustic alert might allow an earlier treatment of impending decompensation. An algorithm that implemented impedance measurement into clinical decision making in treating CHF patients was evaluated. METHODS: Forty-two CHF patients (ejection fraction: 27 +/- 6%; New York Heart Association 2...

Ten healthy human volunteers were subjected to progressive lower body negative pressure (LBNP) to the onset of cardiovascular collapse to compare the response of noninvasively determined skin and fat corrected deep muscle oxygen saturation (SmO2) and pH to standard hemodynamic parameters for early detection of imminent hemodynamic instability. Muscle SmO2 and pH were determined with a novel near infrared spectroscopic (NIRS) technique. Heart rate (HR) was measured continuously via ECG, and arterial blood pressure (BP) and stroke volume (SV) were obtained noninvasively via Finometer and impedance cardiography on a beat-to-beat basis...

In patients with chronic heart failure, detecting signs and symptoms of worsening congestion early enough to prevent hospitalization is an ongoing challenge. Intrathoracic impedance monitoring is a new, device-based method for detecting fluid accumulation in the lungs. Small clinical trials have shown that it may provide an early warning of impending decompensation and may be useful when used in conjunction with routine clinical assessment in guiding diuresis during hospitalization. Additional large-scale, prospective, randomized clinical trials are currently underway to further evaluate its clinical utility...

Intrathoracic impedance monitoring (approved by the US Food and Drug Administration) and implantable hemodynamic monitoring (IHM), which is under investigation, are promising techniques for the improved management of heart failure by detecting early changes in fluid status or hemodynamic congestion. Routine outpatient surveillance of intrathoracic impedance data from implanted devices may significantly reduce the currently high rates of hospital admission/readmission for patients with heart failure. IHM systems may extend such monitoring capabilities...

BACKGROUND: Patients with heart failure are frequently hospitalized for fluid overload. A reliable method for chronic monitoring of fluid status is therefore desirable. We evaluated an implantable system capable of measuring intrathoracic impedance to identify potential fluid overload before heart failure hospitalization and to determine the correlation between intrathoracic impedance and standard measures of fluid status during hospitalization. METHODS AND RESULTS: Thirty-three patients with NYHA class III and IV heart failure were implanted with a special pacemaker in the left pectoral region and a defibrillation lead in the right ventricle...

This study was conducted to demonstrate the potentiality of lead field theoretical approach in analyzing bioimpedance (BI) measurements. Anatomically accurate computer models and the lead field theory were used to develop BI measurement configurations capable of detecting more localized BI changes in the human body. The methods were applied to assess the measurement properties of conventional impedance cardiography (ICG) and such BI measurement configurations as can be derived using (i) the 12-lead electrocardiography (ECG) and (ii) the international 10-20 electroencephalography (EEG) electrode systems...

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In a population of ten young normal male subjects (average height of 174.2 cm +/- 3.8, average weight of 70.2 kg +/- 6.16), which was subjectively classified as mainly ectomorph (slightly biased towards the mesomorph type) a good correlation was found between the transthoracic impedance changes due to normal respiratory movements and tidal volume (average r of 0.963 +/- 0.034) and a mean coefficient b1 of 3.64 ohms/liter +/- 1.82. For equal volume, inspiratory and expiratory movements, on the average, produced impedance changes with no significant difference (p less than 0...