A Method to Calculate Tissue Impedance Through a Standard Bipolar Pacing Lead

Bini, G; Paperini, Luca; Pauletti, M; Pardini, E.; Manfredini, E.; Corbucci, Giorgio

doi:10.1007/s10558-006-9011-7

Cited by 1 publication

(1 citation statement)

References 19 publications

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“…Z measurements were automatically collected through the CRT device along all six vectors (V1 through V6) at 7.5 min intervals throughout the acute study protocols. Using equivalent circuit equations [ 18 ], the measured Z along each vector was modelled as the sum of the near-field contributions from the two measuring electrodes to produce a set of six linear equations (Fig. 1 ).…”

Section: Methodsmentioning

confidence: 99%

Thoracic impedance measures tissue characteristics in the vicinity of the electrodes, not intervening lung water: implications for heart failure monitoring

Charles

Rademaker

Melton

et al. 2014

J Clin Monit Comput

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The rationale for intrathoracic impedance (Z) detection of worsening heart failure (HF) presupposes that changes in Z reflect changes in pulmonary congestion, but is confounded by poor specificity in clinical trials. We therefore tested the hypothesis that Z is primarily affected by tissue/water content in proximity to electrodes rather than by lung water distribution between electrodes through the use of a new computational model for deriving the near-field impedance contributions from the various electrodes. Six sheep were implanted with a left atrial pressure (LAP) monitor and a cardiac resynchronization therapy device which measured Z from six vectors comprising of five electrodes. The vector-based Z was modelled as the summation of the near-field impedances of the two electrodes forming the vector. During volume expansion an acute increase in LAP resulted in simultaneous reductions in the near-field impedances of the intra-cardiac electrodes, while the subcutaneous electrode showed several hours of lag (all p < 0.001). In contrast, during the simulated formation of device-pocket edema (induced by fluid injection) the near-field impedance of the subcutaneous electrode had an instantaneous response, while the intra-cardiac electrodes had a minimal inconsistent response. This study suggests that the primary contribution to the vector based Z is from the tissue/water in proximity to the individual electrodes. This novel finding may help explain the limited utility of Z for detecting worsening HF.

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Section: Methodsmentioning

confidence: 99%