Hormonal Changes as a Potential Cause for Monthly Fluid Status Variation as Indicated by Intrathoracic Impedance

Early detection of decompensated heart failure enables clinicians to tailor medical therapy to individual patient needs. The utility of transthoracic impedance assessment in the early diagnosis of volume overload has been documented in the literature. We describe the case of a young woman without congestive heart failure who was noted to have cyclical variations of transthoracic impedances that correlated with her menstrual cycle and discuss other factors that may confound proper diagnosis of volume overload in patients with implantable cardioverter-defibrillators.