title: Decreased autonomic modulation of heart rate and altered cardiac sympathovagal balance in patients with Cushing's syndrome: role of endogenous hypercortisolism.
abstract: OBJECTIVE
  Endogenous Cushing's syndrome is associated with a higher risk of cardiovascular morbidity and mortality. Previous literature suggested multiple possible links by which hypercortisolism may alter the autonomic control of cardiovascular functions. We investigated the impact of chronic endogenous hypercortisolism on the autonomic regulation of cardiac functions by short-term heart rate variability analysis.
  
  
  METHODS
  Eighteen patients with endogenous Cushing's syndrome and 20 age-, gender- and BMI-matched controls participated in the study. ECG signal was acquired in lead II configuration for 5 min and heart rate variability assessment was made in both time and frequency domain using the extracted RR interval data.
  
  
  RESULTS
  All time and frequency domain measures of heart rate variability were significantly (p < 0.05) lower in the patient group compared to the control group. The patient group had an altered sympathovagal balance with low frequency/high frequency band ratio significantly higher than the control group [1.857 (0.6747-2.610) vs. 0.8581 (0.4779-1.352); p = 0.0253]. A significant negative correlation was obtained between normalized high frequency power of heart rate variability and basal cortisol levels (r = -0.6594; p = 0.0029). Multiple linear regression analysis identified age, disease duration (in months), basal cortisol levels and systolic blood pressure as independent predictors of normalized high frequency power.
  
  
  CONCLUSIONS
  Findings of the study clearly portrayed the diminished autonomic modulation of heart rate in endogenous Cushing's syndrome and its possible relationship with hypercortisolism as the main causative factor. Diminished heart rate variability may be an indicator of the increased risk of cardiac mortality in these patients.
authors: Department of Physiology, All India Institute of Medical Sciences, New Delhi, India.
authors: Dinu S
authors: DS
authors: Chandran
authors: Naseer
authors: N
authors: Ali
authors: Ashok Kumar
authors: AK
authors: Jaryal
authors: Viveka P
authors: VP
authors: Jyotsna
authors: Kishore Kumar
authors: KK
authors: Deepak
mesh_terms: D000293:Adolescent; D000328:Adult; D001341:Autonomic Nervous System / Q000503:physiopathology*; D016022:Case-Control Studies; D002648:Child; D003480:Cushing Syndrome / Q000503:physiopathology*; D005260:Female; D006321:Heart / Q000294:innervation / Q000503:physiopathology*; D006331:Heart Diseases / Q000209:etiology / Q000503:physiopathology; D006339:Heart Rate / Q000502:physiology*; D006801:Humans; D006854:Hydrocortisone / Q000502:physiology*; D008297:Male; D013564:Sympathetic Nervous System / Q000503:physiopathology; D055815:Young Adult
chemical_list: D006854:Hydrocortisone