The autonomic nervous system (ANS) and cardiovascular function are intricately and closely related. One of the most frequently used diagnostic and prognostic tools for evaluating cardiovascular function is the exercise stress test. Exercise is associated with increased sympathetic and decreased parasympathetic activity and the period of recovery after maximum exercise is characterized by a combination of sympathetic withdrawal and parasympathetic reactivation, which are the two main arms of the ANS. Heart rate recovery after graded exercise is one of the commonly used techniques that reflects autonomic activity and predicts cardiovascular events and mortality, not only in cardiovascular system disorders, but also in various systemic disorders. In this article, the definition, applications and protocols of heart rate recovery and its value in various diseases, in addition to exercise physiology, the ANS and their relationship, will be discussed.

ÖZETArteriyel kan basıncı sabahın erken saatlerinde zirveye, gece saatlerinde en düşük değerlere ulaşan sirkadiyen bir ritim paterni izlemektedir. Geceleri arteriyel kan basıncındaki düşüş normal sirkadiyen paternin bir parçasıdır. Bu düşüşün görülmediği "non-dipping" olarak adlandırılan sirkadiyen kan basıncı paterni, özellikle hipertansif hastalarda, daha şiddetli hedef organ hasarı ve artmış kardiyovasküler olaylarla birliktedir. Her ne kadar altta yatan mekanizmalar tam olarak bilinmese de "non-dipping" paterni olan kişilerde anormal parasempatik ve sempatik aktiviteleri içeren otonom sistem bozukluğunun olduğu öne sürülmüştür. "Non-dipping" fenomeninde otonom sinir sisteminin rolü birçok çalışmada incelenmiştir. Bu yazıda, sirkadiyen arteriyel kan basıncı paterni ile kardiyak otonomik işlevlerin göstergeleri arasındaki ilişkiyi değerlendiren çalışmaları derlemeyi amaçladık. ( ABSTRACTArterial blood pressure fluctuates with a pattern that follows a circadian rhythm, with a peak in the early morning hours and a trough during nighttime. Nocturnal dipping of arterial blood pressure is part of this normal circadian pattern, and its absence, which is called non-dipping is associated with more severe end-organ damage and increased risk of cardiovascular events, especially in hypertensive patients. Although pathologic mechanisms are still unclear, it has been suggested that non-dippers show impairment in the autonomic system functions that include abnormal parasympathetic and sympathetic activities. Several studies have examined the role of the autonomic nervous system in the non-dipping phenomenon. In this paper, we aimed to review the studies evaluating the relationship between circadian arterial blood pressure pattern and indices of cardiac autonomic functions. (Anadolu Kardiyol Derg 2011; 2: 168-73)

Background: Catheter ablation of atrial fibrillation is recommended for patients with symptomatic paroxysmal atrial fibrillation (PAF) despite anti-arrhythmic drugs (AADs (HR = 60, p < 0.001)

Patients with AS has lower HRR and HRV indices with respect to normal subjects. Cardiac autonomic functions might be involved in AS patients even in patients without cardiac symptoms.

One of the major complications of arsenic on human health is hypertension. Arsenic-related hypertension and negative effects of arsenic on arterial system such as oxidative stress and vasoconstriction/vasorelaxation imbalance may lead to impair aortic elasticity. The aim of this study was to evaluate the effects of arsenic on aortic elasticity parameters including aortic strain and distensibility. One hundred twelve (112) workers were occupationally exposed to arsenic and 60 healthy control subjects were enroled. All patients underwent transthoracic echocardiography for detecting aortic strain and aortic distensibility. There were no differences in baseline demographic and echocardiographic characteristics between the groups. Aortic strain (10.3±3.9 vs 12.1±2.7%, P=0.001) and aortic distensibility (0.45±0.17 vs 0.54±0.15 cm per dyn, P=0.001) were decreased in arsenic-exposure group compared with controls. Urinary arsenic level was found to be negatively and significantly correlated with aortic strain (r=-0.306, P=0.001) and aortic distensibility (r=-0.259, P=0.006). Duration of arsenic exposure was also found to be negatively and significantly correlated with aortic strain (r=-0.386, P<0.001) and aortic distensibility (r=-0.333, P<0.001). This study suggests that arsenic exposure is related to impairment of aortic elasticity parameters even in subjects without overt cardiovascular disease.

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Objective: To assess exercise heart rate recovery (HRR) indices in patients with systemic sclerosis (SSc) for an assessment of their cardiac autonomic function. Subjects and Methods: Thirty-five patients with diffuse or limited SSc and 35 healthy controls were enrolled. All subjects underwent exercise testing and transthoracic echocardiography. The HRR indices were calculated by subtracting the first- (HRR1), second- (HRR2) and third-minute (HRR3) heart rates from the maximal heart rate. Results: The SSc and control groups were similar in age (45.2 ± 11.6 vs. 43.9 ± 10.0 years), had identical gender ratios (31 female/4 male in both groups) and similar left ventricular ejection fraction (66.5 ± 5.1 vs. 67.7 ± 5.9%). The mean HRR1 (21.8 ± 4.4 vs. 27.7 ± 4.3 bpm, p = 0.001), HRR2 (43.8 ± 6.3 vs. 47.6 ± 4.4 bpm, p = 0.004) and HRR3 (58.8 ± 10.3 vs. 63.6 ± 7.3 bpm, p = 0.031) values were significantly lower in the SSc group than in the healthy controls. HRR indices were similar in the limited and diffuse SSc subgroups. Conclusions: The patients with SSc had lower HRR indices than normal subjects. Cardiac autonomic functions might be involved in SSc, even in patients without cardiac symptoms.

The aims of this study were to measure the levels of interleukin-33 (IL-33) and soluble Suppression of Tumorigenicity 2 (sST2) in patients with newly diagnosed primary hypertension (HT) and to determine the relationship between carotid intima-media thickness (CIMT) and IL-33/sST2. Eighty-two patients with newly diagnosed primary HT and ninety healthy volunteers were included in the study. CIMT ⩾0.9 mm was considered as significant for subclinical atherosclerosis. The sST2 levels of patients with primary HT were higher than those of the control group, whereas the IL-33 levels of these patients were much lower than those of the control group. The sST2 levels were higher in patients with subclinical atherosclerosis than in control subjects or patients with primary HT but not with subclinical atherosclerosis. In the primary HT group, sST2 had a positive correlation with CIMT, 24-h systolic-diastolic blood pressure, low-density lipoprotein and C-reactive protein, whereas sST2 had a negative correlation with the IL-33 level. A stepwise multivariable logistic regression analysis revealed that sST2 is an independent risk factor for subclinical atherosclerosis. Although the diagnostic predictive value of HT risk was determined as >51.8 pg l(-1) in the receiver operating characteristic curve analysis in respect of the sST2 level, the diagnostic predictive value for subclinical atherosclerosis risk was determined to be >107.2 pg l(-1). The sST2 level displays a positive correlation with atherosclerotic changes, and is an independent risk factor for subclinical atherosclerosis expressed as increased CIMT.