Acute evaluation of transthoracic impedance vectors using ICD leads.

• BACKGROUND: Minute ventilation (MV) has been proven to be very useful in rate responsive pacing. The aim of this study was to evaluate the feasibility of using implantable cardioverter-defibrillator (ICD) leads as part of the MV detection system. METHODS: At implant in 10 patients, the transthoracic impedance was measured from tripolar ICD, tetrapolar ICD, and atrial lead vectors during normal, deep, and shallow voluntary respiration. MV and respiration rate (RespR) were simultaneously measured through a facemask with a pneumotachometer (Korr), and the correlations with impedance-based measurements were calculated. Air sensitivity was the change in impedance per change in respiratory tidal volume, ohms (Omega)/liter (L), and the signal-to-noise ratio (SNR) was the ratio of the respiratory and cardiac contraction components. RESULTS: The air sensitivity and SNR in tripolar ICD vector were 2.70 +/- 2.73 ohm/L and 2.19 +/- 1.31, respectively, and were not different from tetrapolar. The difference in RespR between tripolar ICD and Korr was 0.2 +/- 1.91 breaths/minute. The regressed correlation coefficient between impedance MV and Korr MV was 0.86 +/- 0.07 in tripolar ICD. CONCLUSIONS: The air sensitivity and SNR in tripolar and tetrapolar ICD lead vectors did not differ significantly and were in the range of the values in pacemaker leads currently used as MV sensors. The good correlations between impedance-based and Korr-based RespR and MV measurements imply that ICD leads may be used in MV sensor systems.

Nyckelord

Adult

Aged

Algorithms

Cardiography

Impedance

instrumentation

methods

Defibrillators

Implantable

Diagnosis

Computer-Assisted

instrumentation

methods

Electric Impedance

Electrodes

Implanted

Female

Humans

Male

Middle Aged

Reproducibility of Results

Respiratory Function Tests

instrumentation

methods

Respiratory Mechanics

Sensitivity and Specificity

Young Adult

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