title: Elimination of central sleep apnea by cardiac valve replacement: a continuous follow-up study in patients with rheumatic valvular heart disease.
abstract: BACKGROUND
  Recent studies have suggested that cardiac surgery may affect sleep-disordered breathing (SDB) in chronic heart failure patients. However, the dynamic changes in sleep apnea and heart function after cardiac surgery and the mechanisms responsible for these changes remain unknown.
  
  
  METHODS
  Patients with rheumatic valvular heart disease (RVHD) and SDB were enrolled and followed up at three, six and 12 months after cardiac valve replacement (CVR). Baseline and follow-up clinical data consisting of NYHA classification, 6min walk distance (6-MWD), medications, echocardiography, electrocardiography, chest X-ray, arterial blood gas, lung-to-finger circulation time (LFCT), and sleep data were collected and evaluated.
  
  
  RESULTS
  Twenty-four central sleep apnea (CSA) patients and 15 obstructive sleep apnea (OSA) patients completed three follow-up assessments. Comparison of the baseline parameters between OSA patients and CSA patients showed that CSA patients had a worse baseline cardiac function assessed by higher NYHA class, shorter 6-MWD, larger left atrial diameter, longer LFCT, and enhanced chemosensitivity (higher pH and lower arterial carbon dioxide tension (PaCO2)). A continuous significant elevation in 6-MWD and left ventricular ejection fraction and decrease in NYHA class, plasma BNP, and left atrial diameter were found in both CSA and OSA patients. When comparing CSA and OSA patients, the CSA indices were remarkably reduced at month 3 post CVR and sustained throughout the trial, whereas there were no significant decreases in OSA index and hypopnea index. pH values and LFCT were markedly decreased and PaCO2 markedly increased in patients with CSA at the end of the third months following CVR. These changes were sustained until the end of the trial.
  
  
  CONCLUSIONS
  CSA patients with RVHD had a worse baseline cardiac function, enhanced chemosensitivity and disordered hemodynamic as compared with OSA patients with RVHD. CSA were eliminated after CVR; however, there were no changes in OSA. The elimination of CSA, post CVR, is associated with the combined efficacies of improvement of cardiac function, normalized chemosensitivity, and stabilized hemodynamic.
authors.affiliation: Department of Respiratory Medicine, The First Affiliated Hospital of Nanjing Medical University, Nanjing, China.
authors.forename: Ning
authors.initials: N
authors.lastname: Ding
authors.affiliation: Department of Cardiothoracic Surgery, The First Affiliated Hospital of Nanjing Medical University, Nanjing, China.
authors.forename: Bu-Qing
authors.initials: BQ
authors.lastname: Ni
authors.affiliation: Department of Respiratory Medicine, The First Affiliated Hospital of Nanjing Medical University, Nanjing, China.
authors.forename: Xi-Long
authors.initials: XL
authors.lastname: Zhang
authors.affiliation: Department of Respiratory Medicine, The First Affiliated Hospital of Nanjing Medical University, Nanjing, China.
authors.forename: Wang-Jian
authors.initials: WJ
authors.lastname: Zha
authors.affiliation: Morsani College of Medicine, Tampa, FL, USA.
authors.forename: Sean Z
authors.initials: SZ
authors.lastname: Hutchinson
authors.affiliation: Department of Geriatric Medicine, The First Affiliated Hospital of Nanjing Medical University, Nanjing, China.
authors.forename: Wei
authors.initials: W
authors.lastname: Lin
authors.affiliation: Department of Respiratory Medicine, The First Affiliated Hospital of Nanjing Medical University, Nanjing, China.
authors.forename: Mao
authors.initials: M
authors.lastname: Huang
authors.affiliation: Department of Cardiothoracic Surgery, The First Affiliated Hospital of Nanjing Medical University, Nanjing, China. Electronic address: shijiangzhang@hotmail.com.
authors.forename: Shi-Jiang
authors.initials: SJ
authors.lastname: Zhang
authors.affiliation: Department of Respiratory Medicine, The First Affiliated Hospital of Nanjing Medical University, Nanjing, China.
authors.forename: Hong
authors.initials: H
authors.lastname: Wang
mesh_terms: D004452:Echocardiography; D005260:Female; D006349:Heart Valve Diseases / Q000150:complications / Q000601:surgery*; D006801:Humans; D008297:Male; D008875:Middle Aged; D017286:Polysomnography; D012214:Rheumatic Heart Disease / Q000150:complications / Q000601:surgery*; D020182:Sleep Apnea, Central / Q000209:etiology / Q000601:surgery*; D020181:Sleep Apnea, Obstructive / Q000209:etiology / Q000601:surgery
keywords: Cardiac function; Cardiac valve replacement; Central sleep apnea; Obstructive sleep apnea; Rheumatic valvular heart disease; Sleep-disordered breathing