demonstrated a correlation between ReDS values and lung fluid levels, 8,9 as well as the clinical implications of ReDSguided heart failure management. 10, 11 The Second Department of Internal Medicine, Toyama University received permission to use the device for the first time in Japan before commercial marketing. The device itself will soon be clinically available in Japan.In the present proof-of-concept study, we investigated the relationship between body posture and ReDS values in healthy volunteers to clarify the physiological proof of fluid shift depending on different body postures. Methods Participant SelectionHealthy volunteers aged >20 years without any past medical history were prospectively included in this single-center proofof-concept study between August and September 2021. This study was approved by the Clinical Research Review Board, University of Toyama (IRB no. MTK2020007), and written informed consent was obtained from all participants.

Ideal heart rate (HR), particularly for those with heart failure with preserved ejection fraction (HFpEF), remains unknown. We hypothesized that cardiac output would be maximum when the overlap between E-wave and A-wave at the trans-mitral flow is "zero" in the Doppler echocardiography. We retrospectively investigated the association among the overlap length between two waves, actual HR, and other echocardiographic parameters to construct a formula for estimating theoretically ideal HR among those with HFpEF. In total, 48 HFpEF patients were included (70-year-olds, 18 males). Given the results of multivariate linear regression analyses, the overlap length was estimated as follows: 1,050 + 8.4 × (HR [bpm]) + 0.6 × (deceleration time [millisecond]) + 1.7 × (A-width [millisecond]), which had a strong agreement with the actually measured overlap length (r = 0.86, P < 0.001). Theoretically ideal HR was calculated by substituting zero into the estimated overlap length as follows: 125 − 0.07 × (deceleration time [millisecond]) − 0.20 × (A-width [millisecond]). In the validation cohort including another 143 HFpEF patients, the estimated overlap using the formula again had a strong agreement with the actually measured overlap (r = 0.72, P < 0.001). In this study, we proposed a novel formula for calculating theoretically ideal HR, consisting of deceleration time and A-width, in the HFpEF cohort. Clinical implication to optimize the HR targeting the theoretically ideal HR should be investigated in prospective studies.

Remote dielectric sensing (ReDS) is a recently introduced non-invasive electromagnetic-based device used to quantify lung fluid levels. Nevertheless, its inter-rater and intra-rater reliability remain uncertain. In 10 healthy volunteers, ReDS values were measured three times successively by the officially trained expert examiner to validate intra-rater reliability. Similar measures were performed by a total of three examiners to validate inter-rater reliability. Intra-class correlation (ICC) was applied to validate each reliability. Ten healthy volunteers [median 34 (32, 40) years old, 10 men, body mass index 23.0 (21.2, 23.9)] were included. Median ReDS value was 28% (25%, 31%). For the intra-rater reliability, ICC (1, 1) and ICC (1, 3) were 0.966 and 0.988, respectively (P < 0.001). For the inter-rater reliability, ICC (2, 1) and ICC (2, 3) were 0.683 and 0.866, respectively (P < 0.001). Given almost perfect intra-rater reliability, an examiner does not need to repeat ReDS measurement. Given substantial inter-rater reliability, ReDS measurements had better be measured by multiple examiners if possible.