e-ISSN 2329-0072




Spectral techniques for determining autonomic nervous activity through heart rate variability in morbidly obese patients undergoing bariatric surgery

Isabella de Carvalho Aguiar, Roger A. O. Peixoto, Israel dos Reis Santos, Sergio Roberto Nacif, Luciana Maria Molosa Sampaio, Wilson Rodrigues de Freitas Junior, Carlos Alberto Malheiros, Daniel P. B. Chaves, Marcio Magini, Luis Vicente Franco Oliveira

Med Sci Tech 2012; 53(4): RA175-180

ID: 883654

Available online:

Published: 2012-12-17


Background:    Obesity is a major public health problem in both developed and developing countries alike and leads to a series of changes in cardiorespiratory physiology. There is a strong correlation between obesity and sleep disorders. Weight loss among such patients leads to a reduction in these pathological alterations, but clinical treatment is not effective over the long-term. Thus, bariatric surgery is a viable option. Morbid obesity is also associated with cardiomyopathy, increased left ventricular wall stress, left ventricular hypertrophy, and diastolic dysfunction. This process stimulates the autonomic nervous system (ANS), leading to systemic vasoconstriction and arterial hypertension. The heart rate variability (HRV) has been incorporated as an important method of assessment of ANS. The objective of this study was to analyze HRV in morbidly obese patients undergoing bariatric surgery before and 60 days after surgery.
    Material/Methods:    The study included 14 patients (11 females), and data collection included BMI classification, abdominal and neck circumferences, Epworth sleepiness scale, a sleep study, and HRV analysis.
    Results:    The mean age was 36.07±10.97. The mean BMI before surgery was 48.68±5.64 and after surgery it was 41.92±5.72 Kg/m2. Our findings demonstrate gains in HRV in all patients after surgery.
    Conclusions:    We conclude that obese patients have a high prevalence of obstructive sleep apnea syndrome and unstable HRV during sleep, with a predominance of sympathetic activity. However, with weight reduction, after 60 days of bariatric surgery there is significant improvement in anthropometric, and sleep variables, and HRV.

Keywords: heart rate variability (HRV), Bariatric Surgery, Sleep Disorder Breathing, Spectral analysis