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The purpose of this study is to compare measurement errors in two commercially available multi-frequency bioimpedance analyzers, a Xitron 4000B and an ImpediMed SFB7, including electrode impedance mismatch. The comparison was made using resistive electrical models and in ten human volunteers. We used three different electrical models simulating three different body segments: the right-side, leg and thorax. In the electrical models, we tested the effect of the capacitive coupling of the patient to ground and the skin-electrode impedance mismatch. Results showed that both sets of equipment are optimized for right-side measurements and for moderate skin-electrode impedance mismatch. In right-side measurements with mismatch electrode, 4000B is more accurate than SFB7. When an electrode impedance mismatch was simulated, errors increased in both bioimpedance analyzers and the effect of the mismatch in the voltage detection leads was greater than that in current injection leads. For segments with lower impedance as the leg and thorax, SFB7 is more accurate than 4000B and also shows less dependence on electrode mismatch. In both devices, impedance measurements were not significantly affected (p > 0.05) by the capacitive coupling to ground.

Cardiac tissue engineering, which combines cells and biomaterials, is promising for limiting the sequelae of myocardial infarction (MI). We assessed myocardial function and scar evolution after implanting an engineered bioactive impedance graft (EBIG) in a swine MI model. The EBIG comprises a scaffold of decellularized human pericardium, green fluorescent protein‐labeled porcine adipose tissue‐derived progenitor cells (pATPCs), and a customized‐design electrical impedance spectroscopy (EIS) monitoring system. Cardiac function was evaluated noninvasively by using magnetic resonance imaging (MRI). Scar healing was evaluated by using the EIS system within the implanted graft. Additionally, infarct size, fibrosis, and inflammation were explored by histopathology. Upon sacrifice 1 month after the intervention, MRI detected a significant improvement in left ventricular ejection fraction (7.5% ± 4.9% vs. 1.4% ± 3.7%; p = .038) and stroke volume (11.5 ± 5.9 ml vs. 3 ± 4.5 ml; p = .019) in EBIG‐treated animals. Noninvasive EIS data analysis showed differences in both impedance magnitude ratio (−0.02 ± 0.04 per day vs. −0.48 ± 0.07 per day; p = .002) and phase angle slope (−0.18° ± 0.24° per day vs. −3.52° ± 0.84° per day; p = .004) in EBIG compared with control animals. Moreover, in EBIG‐treated animals, the infarct size was 48% smaller (3.4% ± 0.6% vs. 6.5% ± 1%; p = .015), less inflammation was found by means of CD25+ lymphocytes (0.65 ± 0.12 vs. 1.26 ± 0.2; p = .006), and a lower collagen I/III ratio was detected (0.49 ± 0.06 vs. 1.66 ± 0.5; p = .019). An EBIG composed of acellular pericardium refilled with pATPCs significantly reduced infarct size and improved cardiac function in a preclinical model of MI. Noninvasive EIS monitoring was useful for tracking differential scar healing in EBIG‐treated animals, which was confirmed by less inflammation and altered collagen deposit. Stem Cells Translational Medicine 2017;6:647–655

SUMMARY BACKGROUND & AIMSApplication of bioelectrical impedance vector analysis (BIVA) requires comparison of an impedance vector to reference intervals derived from healthy subjects. The aim of this work is to obtain reference nomograms of bioimpedance vectors from healthy subjects living in Santiago de Cuba. METHODSA sample of 4030 healthy people, ages 2-80 y, was measured using a tetra-polar whole-body bioimpedance analyzer at 50 kHz. BIVA method uses the 50, 75 and 95% confidence ellipses of reference populations to classify individual and group vectors. RESULTSThe 95% confidence ellipses derived among boys and girls (2-12 y) were similar (P > 0.05) with significant gender differences (P < 0.05) throughout adulthood. Furthermore, we can observe a progressive decrease in the modulus of the impedance with age with the same phase angle from 13 to 59 y. However, in both genders on subjects >60 y we also observed a phase downfall, possibly due to the reduction of mass and structure, by sarcopenia. CONCLUSIONSReference ellipses are provided, distributed in six sets resulting in age separation intervals (not in gender) for children from 2 to 12 y; two gender specific reference ellipses for teenagers in the range of 13-16 y, for adults from 17 to 59 y and for elderly people from 60 to 80 y.

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