title: Heart rate variability in beta-thalassemia patients.
abstract: BACKGROUND
  Cardiac failure remains the major cause of death in beta-thalassemia major (TM). Reduced heart rate variability (HRV) is associated with a higher risk of arrhythmias after myocardial infarction and heart failure. We evaluated HRV in TM patients and its relationship with hemodynamics and echocardiographic parameters during a 6-month follow-up.
  
  
  METHODS
  Thirty-four TM patients (19 +/- 10 yr) and 20 healthy subjects (17 +/- 6 yr) were evaluated. Hematologic, biochemical, echocardiographic and HRV parameters were determined at entry and at 6-month follow-up. Time and frequency domain HRV parameters were analyzed from 24-h recorded electrocardiograms. All TM patients received blood transfusion and chelation therapy.
  
  
  RESULTS
  Both time and frequency domain HRV parameters were markedly reduced in TM patients, compared to the control. The significantly improved HRV was seen in correlation with higher hemoglobin (Hb) level when compared within TM group at different time point. No correlation was seen between HRV and serum ferritin, reactive oxygen species (ROS) and non-transferrin bound iron (NTBI).
  
  
  CONCLUSIONS
  HRV is depressed in TM patients. HRV was significantly correlated with Hb level, suggesting that anemia greatly influences the cardiac autonomic balance.
authors: Cardiac Electrophysiology Unit, Department of Physiology, Faculty of Medicine, Chiang Mai University, Chiang Mai, Thailand.
authors: Wasarut
authors: W
authors: Rutjanaprom
authors: Natnicha
authors: N
authors: Kanlop
authors: Pimlak
authors: P
authors: Charoenkwan
authors: Rekwan
authors: R
authors: Sittiwangkul
authors: Somdet
authors: S
authors: Srichairatanakool
authors: Adisak
authors: A
authors: Tantiworawit
authors: Arintaya
authors: A
authors: Phrommintikul
authors: Siriporn
authors: S
authors: Chattipakorn
authors: Suthat
authors: S
authors: Fucharoen
authors: Nipon
authors: N
authors: Chattipakorn
mesh_terms: D000293:Adolescent; D000328:Adult; D002648:Child; D005260:Female; D005293:Ferritins / Q000097:blood; D005500:Follow-Up Studies; D006333:Heart Failure / Q000097:blood / Q000209:etiology / Q000401:mortality / Q000503:physiopathology / Q000628:therapy; D006339:Heart Rate; D006454:Hemoglobins / Q000032:analysis; D006801:Humans; D007501:Iron / Q000097:blood; D008297:Male; D009203:Myocardial Infarction / Q000209:etiology / Q000401:mortality / Q000503:physiopathology / Q000628:therapy; D017382:Reactive Oxygen Species / Q000097:blood; D017086:beta-Thalassemia / Q000097:blood / Q000150:complications / Q000401:mortality / Q000503:physiopathology* / Q000628:therapy
chemical_list: D006454:Hemoglobins; D017382:Reactive Oxygen Species; D005293:Ferritins; D007501:Iron