title: Investigation of heart rate variability of patients undergoing coronary artery bypass grafting (CABG).
abstract: BACKGROUND
  Myocardial revascularization by coronary artery bypass grafting (CABG) is an effective measure for reducing symptoms and mortality in patients with unstable or severe coronary artery disease (CAD). Autonomic function can be estimated non-invasively using heart rate variability (HRV). HRV of patients undergoing CABG is investigated before and after CABG using a soft-decision wavelet based spectral analysis.
  
  
  OBJECTIVE
  The main purpose of this work is to evaluate non-invasively HRV in patients undergoing CABG before operation; and to monitor the status of patients through HRV investigation on day 6 and day 30 after the CABG operation. The study intends to contribute scientific value to understanding the effect of CABG on the cardiovascular autonomic function and surgical outcome.
  
  
  METHODS
  The soft-decision wavelet-based technique is used in this work in order to measure the power spectral density of the three main bands (VLF, LF, and HF) of HRV in 24 patients undergoing CABG operation, before the operation (Group 1: G1), and 6 days after operation (Group 2: G2) and 30 days after operation (Group 3: G3). The data is obtained from Sultan Qaboos University hospital in Oman.
  
  
  RESULTS
  The HF power increases in 22 out of 24 patients in G2 compared to G1. While the LF power decreases in 21 out of 24 patients in G2 compared to G1. Comparing G3 to G1 the LF power decreases in 20 patients. The sum of the VLF and LF power is reduced in G2 in all 24 subjects compared to G1, and in 19 subjects in G3 compared to G1.
  
  
  CONCLUSIONS
  The power spectral density of the HF shows increase in patients recorded on day 6 after operation compared to patients before the operation. The LF shows a decrease in G2 compared to G1. The results of G3 after 30 days of operation still show an increase of the HF power and a decrease in the LF power in most of the patients compared to their values before operation.
authors.affiliation: Department of Electrical & Computer Engineering, College of Engineering, Sultan Qaboos University, Oman.
authors.forename: A
authors.initials: A
authors.lastname: Hossen
authors.affiliation: Department of Physiology, College of Medicine, Sultan Qaboos University, Oman.
authors.forename: D
authors.initials: D
authors.lastname: Jaju
authors.affiliation: Department of Physiology, College of Medicine, Sultan Qaboos University, Oman.
authors.forename: M
authors.initials: M
authors.lastname: Al-Abri
authors.affiliation: Division of Cardio-Thoracic Surgery, Sultan Qaboos University Hospital, Oman.
authors.forename: H
authors.initials: H
authors.lastname: Al-Sabti
authors.affiliation: Division of Cardio-Thoracic Surgery, Sultan Qaboos University Hospital, Oman.
authors.forename: M
authors.initials: M
authors.lastname: Mukaddirov
authors.affiliation: Department of Physiology, College of Medicine, Sultan Qaboos University, Oman.
authors.forename: M
authors.initials: M
authors.lastname: Hassan
authors.affiliation: Department of Physiology, College of Medicine, Sultan Qaboos University, Oman.
authors.forename: K
authors.initials: K
authors.lastname: Al-Hashmi
mesh_terms: D000368:Aged; D001026:Coronary Artery Bypass; D005260:Female; D006339:Heart Rate / Q000502:physiology*; D006801:Humans; D008297:Male; D008875:Middle Aged; D015233:Models, Statistical; D012815:Signal Processing, Computer-Assisted; D058067:Wavelet Analysis
keywords: CABG; HRV; spectral analysis; wavelet analysis