Bariatric Surgery and Its Effects on Heart Rate Variability

Obesity, ranging from “overweight” to “super obese” (Figure 15.1), is a highly prevalent condition that is fast-approaching epidemic proportions in the developed world. The World Health Organization (2010) reported that approximately 1.6 billion adults worldwide were overweight in 2005, with at least 400 million adults being obese (having a body mass index [BMI] greater than 30 kg/m2). According to the International Association for the Study of Obesity (2010), 22.9% of men and 23.2% of women in Canada were obese (2004 estimates) and 32.2% of men and 35.5% of women in the United States were obese (2007 estimates). Similarly, 25% of adults in the United Kingdom were obese (2008 estimates) (Organization for Economic Co-operation and Development, 2010). A recent study estimated the medical cost of obesity in Canada to be 4.1% of all medical expenditures (Anis et al., 2010). Another study estimated the medical costs of obesity worldwide to be 0.7%–2.8% of the global expenditure on health care and also estimated the lifetime medical cost for an obese individual to be 30% higher than for someone at a healthy weight (BMI less than 25 kg/m2) (Withrow and Alter, 2011). In recent years, bariatric surgery has gained clinical acceptance for the induction of weight loss in individuals who are morbidly obese or super obese. This chapter examines four major bariatric procedures currently used to treat obesity and summarizes the studies that have examined heart rate variability (HRV) and autonomic nervous system (ANS) function before and after these surgeries.