ASSOCIATION BETWEEN RISK FACTORS FOR ATHEROSCLEROSIS AND SYMBOLIC INDICES AND COMPLEXITY OF CARDIAC AUTONOMIC MODULATION

G. Qualho¹, M. Stuqui¹, R.J. Quitério¹

¹Faculty of Philosophy and Sciences of the Paulista University "Julio de Mesquida Filho", Physiotherapy and Occupational Therapy, Marilia, Brazil

Background: The main risk factors responsible for myocardial infarction, one of the leading causes of death today, include diabetes, dyslipidemia, systemic arterial hypertension and obesity, which can cause damage to cardiac autonomic modulation (CAM), an independent factor for the occurrence of morbidities and increases the risk of mortality. One of the CAM study methods is Heart Rate Variability (HRV), among which the most recent is Symbolic Analysis (SA), which allows non-reciprocal analysis of sympathetic and parasympathetic indices involving autonomic modulation.

Purpose: To investigate the association between risk factors for atherosclerosis and symbolic, non-linear indices, and the complexity of sympathetic and parasympathetic CAM.

Methods: Study approved by the Ethics Committee of Paulista University, number 1106-2014. Sample: 20 adults aged between 46 and 75 years old, with one or more risk factors for atherosclerosis. Blood pressure (BP) was measured in the sitting position, using the auscultatory method, and values equal or greater than 140 and 90 for systolic and diastolic BP were considered systemic arterial hypertension (SAH), respectively. Body mass index (BMI) was calculated and those weighing 30 kg/m² or more were classified as obese. Blood analysis was performed after 12 hours of fasting and the diagnosis of metabolic alterations was performed: glycemia (GLI)>126 mg/dL; triglycerides (TG)>200 mg/dL; total cholesterol (TC)>240; high-density lipoprotein cholesterol (HDL-c)<40; low-density lipoprotein cholesterol (LDL-c)>160. The RR intervals (iRR) of the electrocardiogram were recorded at rest, in the supine position, with spontaneous breathing. The symbolic indices of HRV were calculated: 0V% (sympathetic), 1V% (sympathetic and parasympathetic), 2LV% (parasympathetic) and 2ULV% (parasympathetic) (PORTA et al, 2001 e 2007). MAC complexity was analyzed using Shannon Entropy. The experimental room was maintained at a temperature of 23±2°C and relative humidity of 50±10%. To analyze the correlation between the variables, the multiple correlation test was applied. The significance level adopted was 5%.

Results: Sample characteristics (N=20): Age = 59.4 + 8.8 years; 13 women and 7 men; iRR = 818.5+83.3ms. Absolute number and percentage of risk factors present in the sample: SAH = 6 (30%); increased TG = 5 (25%); Obesity = 5 (25%); Hyperglycemia = 4 (20%); decreased HDL-c = 3 (15%); increased TC = 1 (5%); Increased LDL-c = 1 (5%). There was a significant (P=0.006), negative and very weak correlation (R = 0.11), only between BMI and Shannon's entropy.

Conclusions: The highest level of body mass index is very weak and negatively associated with the complexity of cardiac neural control. However, the other risk factors, analyzed independently, do not correlate with sympathetic and/or parasympathetic cardiac control or with complexity.

Implications: Although all risk factors must be mitigated or eliminated, maintaining body weight within the expected range is of fundamental importance for prevention, rehabilitation and public policy services, since, in addition to being a causal factor of other metabolic factors, it is associated with worse neurocardiac control, which is an independent factor for other morbidities and increased risk of mortality.

Funding acknowledgements: Foundation for the Support of Research in the State of São Paulo, Brazil.
Pro-Rectory of Research at Universidade Paulista, Brazil.

Keywords:
Autonomic nervous system
Atherosclerosis
Risk factors

Topics:
Cardiorespiratory
Innovative technology: information management, big data and artificial intelligence
Disability & rehabilitation

Did this work require ethics approval? Yes

Institution: Paulista University: Faculty of Philosophy and Sciences

Committee: Faculty of Philosophy and Sciences

Ethics number: 11062014