Altered autonomic neural control of the cardiovascular system in patients with polycystic ovary syndrome
Introduction
Polycystic ovary syndrome (PCOS) is a common endocrine disorder of women in their reproductive years, with a prevalence of up to 10% [1]. It is characterized by chronic anovulation and hyperandrogenism, and is frequently accompanied by the presence of cardiovascular risk factors. Specific risk factors that have been reported include hyperlipidemia [2], obesity [3], insulin resistance [4] and elevations in C-reactive protein [5]. That, in turn, has led to concern about the effect of PCOS on long-term health, particularly with regard to diabetes, hypertension and coronary heart disease. In addition, women with PCOS have been found to exhibit endothelial dysfunction [6] and increased atherosclerosis in cross-sectional studies involving angiography [7], increased coronary calcium by computed tomography [8] and increased carotid intima-media thickness by ultrasound [6], [9]. Yet, it is not clear that these findings translates into increased cardiovascular mortality [10].
It has been also recognized that there is a significant relationship between the autonomic nervous system and cardiovascular mortality [11]. Heart rate recovery (HRR) after exercise is a marker of parasympathetic activity [12], [13], and attenuation of this parameter has been shown to be associated with increased long-term mortality [14], [15]. A delayed recovery of systolic blood pressure (SBP) after peak exercise has been found to have diagnostic value [16] and might reflect sympathetic hyperactivity [17], [18]. In addition, the analysis of variations in heart rate has also been used to determine the balance between sympathetic and vagal nerve activities in the heart [19]. Although activation of the sympathetic neurons innervating the ovary might precede the development of cystic ovaries [20], there is limited data on sympathetic and parasympathetic activity in women with PCOS [21]. Therefore, in the present study, we sought to determine the autonomic activity in patients with PCOS utilizing the parameters derived from a treadmill exercise test and a 24 h-Holter recording.
Section snippets
Study population
Study population consisted of 26 untreated patients with PCOS and 24 healthy controls. PCOS is defined as the presence of all of following three criteria: (i) polycystic ovaries; (ii) oligo-/anovulation; and (iii) clinical or biochemical evidence of hyperandrogenism after the exclusion of adrenal enzymatic deficiencies, Cushing's syndrome and tumors. Anovulation was defined as serum progesterone < 3 ng/ml. Clinical hyperandrogenism was defined by the presence of hirsutism, acne, or androgenic
Results
The baseline clinical characteristics of patients with PCOS and controls are given in Table 1. Both groups included young subjects with a mean age of around 26 years. The groups were well matched with respect to age, body mass index and physical activity. The biochemical parameters of patients with PCOS were comparable with those of control subjects. However, patients with PCOS had nonsignificantly higher levels of triglycerides, testosterone, insulin and LH than that of controls.
Exercise test
Discussion
The major findings of this study are that the patients with PCOS have an attenuted HRR1, an exaggerated SBP response to exercise which is delayed to recover and a depressed HRV.
The increase in heart rate that accompanies exercise is due in part to a reduction in vagal tone. Recovery of the heart rate immediately after exercise, especially during the first minute, is a function of vagal reactivation [12], [13]. Thus, HRR1 after treadmill exercise has been widely accepted as an indicator of
References (47)
- et al.
Endothelial dysfunction in PCOS: role of obesity and adipose hormones
Am J Med
(2006) - et al.
Intima-media thickness of elastic and muscular arteries of young women with polycystic ovaries
Atherosclerosis
(2004) - et al.
Vagally mediated heart rate recovery after exercise is accelerated in athletes but blunted in patients with chronic heart failure
J Am Coll Cardiol
(1994) - et al.
Diagnostic value of postexercise systolic blood pressure response for detecting coronary artery disease in patients with or without hypertension
Am Heart J
(1993) - et al.
Delayed recovery of postexercise blood pressure in patients with chronic heart failure
Am J Cardiol
(1997) - et al.
Mechanism of abnormal postexercise systolic blood pressure response and its diagnostic value in patients with coronary artery disease
Am Heart J
(1990) - et al.
Is systolic blood pressure recovery after exercise a predictor of mortality?
Am Heart J
(2004) - et al.
Follow-up of normotensive men with exaggerated blood pressure response to exercise
Am Heart J
(1983) - et al.
Early prediction of hypertension using exercise blood pressure
Prev Med
(1981) - et al.
Cardiovascular disease in the polycystic ovary syndrome: new insights and perspectives
Atherosclerosis
(2006)