Utility of Fluid Assessment Based on the Intrathoracic Impedance Monitoring in a Peripartum Woman with Heart Disease

Recently, implantable cardioverter-defibrillators (ICD) have become capable of monitoring intrathoracic impedance to detect an increased fluid volume and heart failure. Pregnancy is a well-known cause of an increased body fluid volume; however, it is not clear whether the measurement of intrathoracic impedance by ICD is clinically useful for precisely detecting heart failure in pregnant women. We herein report the case of a 39-year-old woman with an ICD that had been implanted after an event of ventricular fibrillation due to severe aortic regurgitation with a bicuspid aortic valve. Elevated right ventricular pressure and brain natriuretic peptide levels were detected at 37 weeks of gestation and postpartum. At the same time, the ICD's stored fluid index gradually increased and exceeded the threshold on the 10th day after delivery. She was treated with diuretics and recovered from postpartum heart failure. The physiological volume changed in the perinatal period, but we were still able to detect heart failure by ICD. Intrathoracic impedance monitoring is effective in the perinatal field.