Bioelectrical signals improve cardiac function and modify gene expression of extracellular matrix components

Beyond the influence of stimulating devices on cardiac excitation, their use in treating patients with heart failure has positive effects on the myocardium at the molecular level. Electrical signals can induce a wide spectrum of effects in living tissue. Therefore, we sought to determine whether applying electrical microcurrent directly to failing hearts leads to functional improvement. Methods and results Sixteen male spontaneously hypertensive rats (SHRs) with heart failure underwent application of a patch electrode to the left ventricular epicardium and placement of a subcutaneous counter electrode. The electrode delivered a 0.35 A microcurrent to nine of the SHRs for 45 3 days; the other seven SHRs were used as controls. At baseline and before the SHRs were humanely put to death, we measured the left ventricular ejection fraction (LVEF) and the thickness of the LV posterior wall during systole and diastole (LVPWs/d). We used quantitative PCR to determine extracellular matrix parameters [collagen IIII, matrix metalloproteinase (MMP)2, MMP9, tissue inhibitor of metalloproteinases 3 (TIMP3), TIMP4, connexins (Cxs) 40/43/45, transforming growth factor (TGF), and interleukin (IL)6]. Among SHRs undergoing microcurrent application, LVEF normalized (mean decrease, 22.8%; P = 0.009), and LVPWs decreased (mean, 35.3%; P = 0.001). Compared with the control group, the SHRs receiving microcurrent exhibited a mean decrease in the gene expression of collagen I (10.6%, P = 0.003), TIMP3 (18.5%, P = 0.005), Cx43 (14.3%, P = 0.003), Cx45 (12.7%, P = 0.020), TGF (13.0%, P = 0.005), and IL6 (53.7%, P = 0.000). Microcurrent application induced no changes in the expression of collagen III, MMP2, MMP9, TIMP4, or Cx40. Conclusions Applying microcurrent to the LV epicardium of SHRs leads to statistically significant functional improvement and alterations in the levels of inflammatory and extracellular matrix components.(VLID)483914

External cardiac defibrillation during wet-surface cooling in pigs

Objective: During surface cooling with ice-cold water, safety and effectiveness of transthoracic defibrillation was assessed. Methods: In a pig ventricular fibrillation cardiac arrest model, once (n = 6), defibrillation was done first in a dry and then in a wet condition using the ThermoSuit System (Life Recovery Systems, HD, LLC, Kinnelon, NJ), which circulates a thin layer of ice-cold water (≈4°C) over the skin surface. Another time (n = 6), defibrillation was done first in a wet and then in a dry condition. Success of defibrillation was defined as restoration of spontaneous circulation, and the current and voltage of the defibrillation signal was measured. Results: There was a tendency toward less number of shocks needed for achieving restoration of spontaneous circulation in the wet condition as compared with the number of shocks needed in the dry condition. The energy delivered in both dry and wet conditions was 144 ± 3 J. Discussion: Transthoracic defibrillation is safe and effective in a wet condition after cooling with ice-cold water. © 2007 Elsevier Inc. All rights reserved