Impaired vagal heart rate control in coronary artery disease.

Abstract

SUMMARY Heart rate variation in deep breathing, a sensitive non-invasive measure of cardiac parasympathetic activity, was measured in 63 patients with coronary artery disease, in 22 patients with atypical chest pain, and in 20 healthy symptom free volunteers. There was significantly less heart rate variation in deep breathing in the patients with coronary artery disease than in the healthy subjects. Twenty patients (32%) with coronary artery disease had lower than normal variation in heart rate. The patients with chest pain showed an intermediate heart rate response to deep breathing. Sinus arrhythmia in the patients with coronary artery disease was not related to the functional class, medication, number or location of narrowed vessels, or to the left ventricular ejection fraction, and end diastolic pressure.These results suggest that impairment of the parasympathetic nervous function is common in coronary artery disease.The harmful effects of increased sympathetic activity after myocardial infarction are well established and the beneficial effects of sympathetic blockade in reducing mortality in high-risk patients have been recognised.'`3 Recently, attention has also been directed toward the electrophysiological effects of the parasympathetic nervous system. Reduced vagal activity is associated with an increased frequency of cardiac death,46 and parasympathetic blockade may precipitate ventricular arrhythmias including ventricular fibrillation.7 8 The majority of patients with acute myocardial infarction show evidence of autonomic disturbances during the acute stage of the attack.9 10 The suggestion that there is dysfunction of the parasympathetic nervous system in stable coronary artery disease" 12 and after myocardial infarction" 14 is, however, more controversial and based on relatively small series of patients. We have evaluated parasympathetic nervous function in coronary artery disease by standard non-invasive cardiovascular tests and have related our findings to the clinical and angiographic features of coronary artery disease.

Association Between Silent Coronary Artery Disease, Diabetes, and Autonomic Neuropathy: Fact or Fallacy?

“…However, it must be remembered that autonomic neuropathy cannot be diagnosed on the basis of one abnormal cardiovascular reflex. Furthermore, myocardial infarction is associated with autonomic dysfunction (35)(36)(37)(38), which may cause similar alterations in Valsalva ratio as diabetic autonomic neuropathy (35). Therefore, in a critical interpretation the findings described by Niakan et al may only reflect the often disregarded effect of myocardial infarction on autonomic nervous function.…”

“…One limitation on any clinical evaluation of the association of autonomic neuropathy with the lack of cardiac pain is that this part of autonomic function is difficult to assess. The heartrate responses used for the conventional diagnosis of autonomic neuropathy mainly reflect the integrity of cardiac parasympathetic activity, and an additional problem with the heart-rate tests is the confounding effect of coronary artery disease and myocardial infarction (35)(36)(37)(38)40,41). Preliminary studies suggest that the distribution of myocardial sympathetic nerves may be assessed with radiolabeled metaiodobenzylguanidine (43).…”

Comparison of Effect of 5 Recumbent Positions on Autonomic Nervous Modulation in Patients With Coronary Artery Disease

“…1,2 In patients with CAD or congestive heart failure (CHF) or both, the short-term heart rate variability (HRV) is significantly lower in those with inducible ventricular tachycardia than in those without clinical or electrocardiographic (ECG) evidence of ventricular tachycardia; and the probability of developing sudden death increases substantially when short-term HRV decreases below 50 ms. 3 It has also been shown that the very-low-frequency power (VLFP) of HRV is an independent risk predictor in patients with CHF. 4 In addition, vagal enhancement has been shown to have an antiarrhythmic effect in acute ischemic animal models, 5,6 and can terminate ventricular tachycardia in humans.…”

Single Dose of Tiotropium Does Not Effect Heart Rate Variability

“…Reduced parasympathetic activity in these patients have been found to be associated with malign ventricular arrhythmias and sudden cardiac death. Patients who have marked autonomic dysfunction leading to reduced HRV are at increased risk of premature death (8)(9)(10)(11)(12)(13)(14). Hypoxia in chronic respiratory disease can also induce autonomic abnormalities leading to reduced HRV (25).…”

“…Abnormal cardiac autonomic function was identified with HRV in left ventricular dysfunction, diabetes mellitus and after myocardial infarction (8)(9)(10)(11)(12)(13)(14).…”