Influence of Autonomic Nervous Dysfunction Characterizing Effect of Diabetes Mellitus on Heart Rate Response and Exercise Capacity in Patients Undergoing Cardiac Rehabilitation for Acute Myocardial Infarction

Abstract

ype 2 diabetes mellitus (DM) is not only an independent risk factor for the development of coronary artery disease, but also contributes to mortality through the induction of arrhythmias or sudden death after acute myocardial infarction (AMI). 1 Furthermore, recent epidemiological surveys have shown that the morbidity of DM has rapidly increased in Japan in the past decade and in consequence the incidence of AMI complicated by DM has also increased remarkably. 2 Because exercise capacity is reduced after AMI in patients with DM in comparison with similar patients without DM, comprehensive cardiac rehabilitation (CR) should be instituted in these patients after the onset of AMI. 3,4 It is important to clarify the mechanisms underlying the decline of exercise capacity after AMI in patients with DM, in order to offer the appropriate exercise training program to them.Heart rate (HR) response to exercise is regulated by the balance between sympathetic and parasympathetic nerve (SN and PN) activities in the human body. 5 An insufficient HR response to exercise caused by autonomic nervous dysfunction seems to be an important mechanisms in patients with DM who show decreased exercise capacity. 3,6 It is well known that norepinephrine (NE) secretion from the terminals of the SNs decreases during exercise in patients with DM, as compared with normal subjects. 7 A previous study concerning the relationship between HR response and SN activity during exercise showed that the HR response corresponding to NE secretion is reduced in AMI patients with DM, resulting in a decline in exercise capacity. 3 In addition, it has been reported that patients with DM have not only SN dysfunction but also PN dysfunction, which is shown by a decrease in the high-frequency power (HF) in HR variability (HRV). 8 However, there are few reports evaluating the influence of PN activity separately from SN activity on the HR response to exercise and exercise capacity of patients with AMI, and moreover, the impact of DM in causing insufficient HR response to exercise. It is very important to clarify the mechanism of HR response to exercise regulated by SN and PN activities in order to prescribe appropriate CR that takes in to account the decreased exercise capacity in AMI patients with DM. It is reported that an imbalance of autonomic nervous activities causes excessive elevation of blood pressure and HR during exercise training in patients with AMI 9 and that the marked activation of SN induces ventricular arrhythmias in patients with coronary artery disease. 10 Background The aim of this study was to clarify the influence of sympathetic and parasympathetic nerve (SN and PN) dysfunction on the heart rate (HR) response to exercise and the exercise capacity of patients with acute myocardial infarction (AMI) and diabetes mellitus (DM). Methods and ResultsFifty-two male patients who underwent cardiopulmonary exercise testing (CPX) 1 month after onset of AMI were divided into 2 groups: (DM (+) group, n=20; DM (-) group, n=32). HR, peak oxygen uptake (V •...

Impaired β-cell function attenuates training effects by reducing the increase in heart rate reserve in patients with myocardial infarction

“…In this study, exercise tolerance was positively correlated with HR reserve and its increase was limited in patients with attenuated pancreatic b-cell function. As in our previous studies on MI complicated with DM [2,5,6], HR reserve may already be attenuated during b-cell dysfunction (the prediabetic phase).…”

Benefit of Combined Cardiac Rehabilitation on Exercise Capacity and Cardiovascular Parameters in Patients with Type 2 Diabetes

“…Its compliance plays an important role in the coronary artery blood flow modulation, the myocardial workload capacity, and therefore also in the global exercise capacity (Kingwell 2002;Cortigiani et al 2007). As well, impaired exercise capacity in type 2 diabetes is associated not only with anthropometrical parameters, such as age, sex or BMI, but also with left ventricle dysfunction and impairment of cardiac autonomic regulation (Fang et al 2005;Sargin et al 2005;Kasahara et al 2006). Lower RPP peak in DM group can be explained by the assumptive presence of various stages of diabetic cardiovascular autonomic neuropathy (CAN).…”

Effectiveness of Moderate Intensity Interval Training as an Index of Autonomic Nervous Activity

“…It is assumed that load was strong to activate the vagus nerve activity. Current of heart disease rehabilitation is not possible to activate the vagus nerve activity [23], leaving a challenge to the setting of the program.…”