The use of heart rate variability measures as indicators of autonomic nervous modulation must be careful in patients after orthotopic heart transplantation.
The precise relation between heart rate variability (HRV) and autonomic re-innervation has not been established explicitly in patients after orthotopic heart transplantation (OHT), but can be inferred from the fact that the HRV is reduced immediately after OHT and may increase gradually with time. The aim of this study was to investigate the residual HRV in patients about 1-2 years after OHT, as compared with patients after coronary artery bypass graft (CABG) surgery. Thirteen patients who had received OHT and 14 patients who had received CABG surgery were recruited. HRV analysis was performed and the HRV measures in supine position were compared between these two groups of patients. We found that the mean (mRRI), standard deviation and coefficient of variation of RR intervals, total power, very low frequency power (VLFP), low frequency power, high frequency power (HFP), normalized VLFP (nVLFP) and low-/high-frequency power ratio in the OHT group were all significantly decreased, while the heart rate (HR) and normalized HFP (nHFP) were significantly increased, as compared with the CABG group. The decrease in HRV was more severe in the VLFP region. A smaller nVLFP and a greater nHFP were associated with a smaller mRRI and a larger HR in the OHT patients. The slope of the power law relation of HRV became positive in OHT patients, instead of negative in CABG patients. We conclude that patients after OHT have residual HRV which were characterized by severely depressed time and frequency domain HRV, increased HR and nHFP, decreased nVLFP, and positive slope of the power-law relation of HRV. The use of nHFP as the indicator of vagal modulation and the use of nVLFP as the indicator of renin-angiotensin modulation, thermoregulation and vagal withdrawal must be careful in the OHT patients.
Laboratory of Biophysics, Department of Medical Research, Taipei Veterans General Hospital, Taipei, 112, Taiwan.|Institute of Cultural Asset and Reinvention, Fo-Guang University, Yilan, 262, Taiwan.
Wan-An
WA
Lu
Department of Internal Medicine, Ten-Chen General Hospital, Yangmei, Tao-Yuan, 326, Taiwan.|Institute of Biomedical Engineering, National Yang-Ming University, Taipei, 112, Taiwan.
Gau-Yang
GY
Chen
Division of Cardiovascular Surgery, Department of Surgery, Taipei Veterans General Hospital, Taipei, 112, Taiwan.
Chun-Che
CC
Shih
Laboratory of Biophysics, Department of Medical Research, Taipei Veterans General Hospital, Taipei, 112, Taiwan. cdkuo23@gmail.com.|Division of Respiratory Therapy, Department of Chest Medicine, Taipei Veterans General Hospital, Taipei, 112, Taiwan. cdkuo23@gmail.com.
Cheng-Deng
CD
Kuo
D000328:Adult; D000368:Aged; D001341:Autonomic Nervous System / Q000503:physiopathology*; D016022:Case-Control Studies; D001026:Coronary Artery Bypass; D004562:Electrocardiography; D005260:Female; D005500:Follow-Up Studies; D006333:Heart Failure; D006339:Heart Rate / Q000502:physiology*; D016027:Heart Transplantation; D006439:Hemodynamics; D006801:Humans; D016014:Linear Models; D008297:Male; D008875:Middle Aged; D008991:Monitoring, Physiologic / Q000379:methods*; D011446:Prospective Studies; D012044:Regression Analysis; D012084:Renin-Angiotensin System; D014630:Vagus Nerve / Q000473:pathology
Autonomic nervous system; Heart rate variability; Heart transplantation; Re-innervation