Changes in myocardial electrical impedance in human heart graft rejection

Abstract

Background: Monitoring of post-transplant heart rejection is currently based on endomyocardial biopsy analysis. This study aimed to assess the effects of heart graft rejection on myocardial electrical impedance. Methods and results: Twenty-nine cardiac transplant patients and 9 controls underwent measurement of myocardial electrical impedance using a specifically designed amplifying system. The module and phase angle of myocardial impedance were measured. Histopathological rejection grading was performed according to ISHLT classification.Fifty impedance tests were performed in transplanted patients. Myocardial impedance (Z) was higher in controls than in transplanted patients (p b 0.001) and followed a progressive decline at increasing current frequencies (p b 0.001). Likewise, the phase angle of impedance in controls ranged from positive values at low frequencies to negative values at higher frequencies (from 2.5 ± 0.9°at 10 kHz to − 3.8 ± 2.1°at 300 kHz, p b 0.001). Rejection was associated with a significant decrease in myocardial impedance (Z) (15 ± 6.6 Ω in grade 0, 13 ± 6.0 Ω in grade 1A, and 3.3 ± 0.9 Ω in grade 3A at 10 kHz, p b 0.003). Conclusions: Mild degrees of cardiac graft rejection are associated with significant changes in myocardial electrical impedance in transplant patients. Further clinical investigation is warranted to assess the potential of cardiac impedance to detect heart graft rejection.

Recognition of Fibrotic Infarct Density by the Pattern of Local Systolic-Diastolic Myocardial Electrical Impedance

“…In contrast, during the healing over process the necrotic scar turns to lower than normal impedance values (Fallert et al, 1993; Wolf et al, 2001; Salazar et al, 2004). In these studies, the technique of measuring the changes in myocardial impedance did not allow to delineate the sequential impedance variations elicited during the systole and diastole phases of the cardiac cycle because of the long time required for the whole impedance spectrum acquisition (Gersing, 1998; Casas et al, 1999; Warren et al, 2000; Cinca et al, 2008). Quite recently, the use of refined fast broadband electrical impedance spectroscopy (EIS; Sanchez et al, 2011) allowed to describe the cyclic pattern of systolic-diastolic impedance changes in a swine model of acute myocardial ischemia (Jorge et al, 2015).…”

Implantable bioimpedance monitor using ZigBee

“…In cardiac tissue characterization applications, electrical impedance spectroscopy (EIS) has been used to detect acute ischemia [2], [3], old infarction scar [4] and rejection in transplanted heart [5], [6]. Measurements are performed in open thorax set-ups [3], through catheter [3], [4] or using a pacemaker-type device [5], [7].…”

Biophysics of recellularized porcine cardiac extracellular matrix for myocardial tissue engineering

“…Again, this result is comparable to the literature that resistivity value for randomly-oriented human heart muscle in the range of 200-600 Ωcm depending on the temperature & applied frequency setting in experiments. [38,[40][41][42] It was clearly shown that with the incorporation of cells, the resistivity of the construct was significantly reduced from 616.01±141.08Ω to 359.77±40.96Ω) (p=0.0023). The conductivity of the construct was improved from 2.37x10 -3 Ω -1 cm -1 to 4.17x10 -3 Ω -1 cm -1 , proving that the presence of cells facilitate electrical propagation.…”

“…[22] Physiological voltage across myocardium has been reported in the range of 3-8V with the resistivity reported to be in the range of 200-600 Ωcm depending on the temperature & applied frequency setting in experiments. [38][39][40][41][42]…”

“…This result is comparable to the literature that resistivity value for randomly-oriented human heart muscle in the range of 200-600 Ωcm depending on the temperature & applied frequency setting in experiments. [38][39][40][41][42] Moreover, to the best of our knowledge, it is the first attempt of electrical conductivity evaluation of a decellularized biological tissue.…”