Autonomic impairment after myocardial infarction: Role in cardiac remodelling and mortality

Abstract

1. Impairmant of baroreflex sensitivity (BRS) has been implicated in the reduction of heart rate variability (HRV) and in the increased risk of death after myocardial infarction (MI). In the present study, we investigated whether the additional impairment in BRS induced by sinoaortic baroreceptor denervation (SAD) in MI rats is associated with changes in the low-frequency (LF) component of HRV and increased mortality rate. 2. Rats were randomly divided into four groups: control, MI, denervated (SAD) and SAD + MI rats. Left ventricular (LV) function was evaluated by echocardiography. Autonomic components were assessed by power spectral analysis and BRS. 3. Myocardial infarction (90 days) reduced ejection fraction (by approximately 42%) in both the MI and SAD + MI groups; however, an increase in LV mass and diastolic dysfunction were observed only in the SAD + MI group. Furthermore, BRS, HRV and the LF power of HRV were reduced after MI, with an exacerbated reduction seen in SAD + MI rats. The LF component of blood pressure variability (BPV) was increased in the MI, SAD and SAD + MI groups compared with the control group. Mortality was higher in the MI groups compared with the non-infarcted groups, with an additional increase in mortality in the SAD + MI group compared with the MI group. Correlations were obtained between BRS and the LF component of HRV and between LV mass and the LF component of BPV. 4. Together, the results indicate that the abolishment of BRS induced by SAD in MI rats further reduces the LF band of HRV, resulting in a worse cardiac remodelling and increased mortality in these rats. These data highlight the importance of this mechanism in the prognosis of patients after an ischaemic event.

Role of Training and Detraining on Inflammatory and Metabolic Profile in Infarcted Rats: Influences of Cardiovascular Autonomic Nervous System

“…Twenty-four hours later, the arterial cannula was connected to a strain-gauge transducer (Blood Pressure XDCR; Kent Scientific, Torrington, CT, USA), and arterial pressure (AP) signals were recorded over a 30 min period in conscious animals by a microcomputer equipped with an analog-to-digital converter board (WinDaq, 2 kHz, DATAQ, Springfield, OH, USA). The recorded data were analyzed on a beat-to-beat basis to quantify changes in mean AP (MAP) and heart rate (HR) [19–22]. …”

Role of Exercise Training on Autonomic Changes and Inflammatory Profile Induced by Myocardial Infarction

“…In recent years, our laboratory has investigated the changes induced by MI alone [25, 27] or associated with different risk factors, such as hypertension [69, 70], ovarian hormone deprivation [23], sinoaortic denervation [24], and diabetes [26–28, 71–73]. These studies have also tested different therapeutic approaches in the management of MI-induced changes.…”

Sevoflurane preconditioning during myocardial ischemia-reperfusion reduces infarct size and preserves autonomic control of circulation in rats

“…Although some studies have implied that the LF component of HRV as well as the LF/HF ratio might reflect the parasympathetic cardiac modulation or the baroreflex 13,28 , the LF component has usually been associated with sympathetic activity 29,30 . In the present study, there was an increase in the LF/HF component of HRV in the infarcted animals.…”

“…After the recording period, animal were anesthetized A global index was quantified by the myocardial performance index (MPI) 13 .…”