Vagal Nerve Stimulation Evoked Heart Rate Changes and Protection from Cardiac Remodeling

This study investigated whether vagal nerve stimulation (VNS) leads to improvements in ischemic heart failure via heart rate modulation. At 7 +/- 1 days post left anterior descending artery (LAD) ligation, 63 rats with myocardial infarctions (MI) were implanted with ECG transmitters and VNS devices (MI + VNS, N = 44) or just ECG transmitters (MI, N = 17). VNS stimulation was active from 14 +/- 1 days to 8 +/- 1 weeks post MI. The average left ventricular (LV) end diastolic volumes at 8 +/- 1 weeks were MI = 672.40 mu l and MI + VNS = 519.35 mu l, p = 0.03. The average heart weights, normalized to body weight (+/- std) at 14 +/- 1 weeks were MI = 3.2 +/- 0.6 g*kg(-1) and MI + VNS = 2.9 +/- 0.3 g*kg(-1), p = 0.03. The degree of cardiac remodeling was correlated with the magnitude of acute VNS-evoked heart rate (HR) changes. Further research is required to determine if the acute heart rate response to VNS activation is useful as a heart failure biomarker or as a tool for VNS therapy characterization.