Feasibility of Using an Implantable System to Measure Thoracic Congestion in an Ambulatory Chronic Heart Failure Canine Model

Wang, Li; Lahtinen, Stuart P.; Lentz, Linnea; Rakow, Nancy; Kaszas, Cameron J.; Ruetz, Linda; Stylos, Lee; Olson, Walter H.

doi:10.1111/j.1540-8159.2005.40009.x

Cited by 78 publications

(64 citation statements)

References 22 publications

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“…12 In our early work in dogs, measurement of intrathoracic impedance by a modified pacemaker correlated closely with heart failure severity as reflected by the LV end-diastolic pressure. 13 This report established the foundation of our study to evaluate intrathoracic impedance as a potentially useful clinical tool to monitor fluid status in heart failure patients. Our objectives were to assess whether a reduction in intrathoracic impedance predates the occurrence of heart failure symptoms and admission, to assess whether changes in intrathoracic impedance correlate with changes in pulmonary capillary wedge pressure and intensive diuresis during heart failure hospitalization, and to develop an automated algorithm for early detection of transient decreases in intrathoracic impedance before heart failure hospitalization.…”

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Intrathoracic Impedance Monitoring in Patients With Heart Failure

et al. 2005

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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. Intrathoracic impedance was regularly measured and recorded between the lead and the pacemaker case. During hospitalizations, pulmonary capillary wedge pressure and fluid status were monitored. Ten patients were hospitalized for fluid overload 25 times over 20.7Ϯ8.4 months. Intrathoracic impedance decreased before each admission by an average of 12.3Ϯ5.3% (PϽ0.001) over an average of 18.3Ϯ10.1 days. Impedance reduction began 15.3Ϯ10.6 days (PϽ0.001) before the onset of worsening symptoms. There was an inverse correlation between intrathoracic impedance and pulmonary capillary wedge pressure (

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Intrathoracic Impedance Monitoring in Patients With Heart Failure

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“…An increase in intrathoracic impedance may also indicate a reduction in pulmonary capillary wedge pressure. 7,8 In the present study, both the range of S-IMP values in individual patients and the mean change in the weekly S-IMP in individual patients of the DHF group were significantly greater than those in the NHF group. The NHF group included patients with a history of CHF or with a low Receiver operating characteristic (ROC) curve.…”

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confidence: 64%

“…5,6 Clinical data suggest that changes in intrathoracic impedance and fluid accumulation in the lung are inversely related: 7,8 as fluid accumulates in the lungs, intrathoracic impedance decreases. An increase in intrathoracic impedance may also indicate a reduction in pulmonary capillary wedge pressure.…”

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confidence: 99%

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Daily Shock Impedance Measured by Implantable Cardioverter Defibrillator is Useful in the Management of Congestive Heart Failure

Matsushita

Ishikawa

Sumita

et al. 2006

Circ J

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“…Intrathoracic impedance, measured as the electrical impedance between a right ventricular pacing-or defibrillation-lead and the device-can, offers a novel tool to track changes in the thoracic fluid content [25]. Based on the principle that increased pulmonary fluid retention causes a drop in intrathoracic impedance, this technology has been incorporated into pacemakers or ICDs for continuous monitoring of the fluid status in patients with chronic heart failure.…”

Section: Implanted Monitoring Featuresmentioning

confidence: 99%

Can monitoring of intrathoracic impedance reduce morbidity and mortality in patients with chronic heart failure? Rationale and design of the Diagnostic Outcome Trial in Heart Failure (DOT‐HF)☆

Braunschweig

Ford

Conraads

et al. 2008

European J of Heart Fail

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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).Methods: Approximately 2400 patients will be randomised in a 1:1 fashion to a management strategy with access to the diagnostic information from the implantable device ("access arm"), or a "control arm", where this information is not made available. Study subjects fulfil standard indications for CRT and/or ICD as outlined in current guidelines. In the access arm, a fluid alert algorithm is used to give early warning of decreasing intrathoracic impedance indicating a high risk of an impending volume-overload decompensation. The primary endpoint of DOT-HF is the composite of all-cause mortality or heart failure hospitalisation. Secondary and exploratory endpoints include all-cause mortality, the impact on total health care utilization, quality of life and cost effectiveness. The study is expected to close recruitment during 2010 and to report in 2012.

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Feasibility of Using an Implantable System to Measure Thoracic Congestion in an Ambulatory Chronic Heart Failure Canine Model

Cited by 78 publications

References 22 publications

Intrathoracic Impedance Monitoring in Patients With Heart Failure

Intrathoracic Impedance Monitoring in Patients With Heart Failure

Daily Shock Impedance Measured by Implantable Cardioverter Defibrillator is Useful in the Management of Congestive Heart Failure

Can monitoring of intrathoracic impedance reduce morbidity and mortality in patients with chronic heart failure? Rationale and design of the Diagnostic Outcome Trial in Heart Failure (DOT‐HF)☆

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