Year: 2012
Type: dissertation
Study design: Observational Study
Abstract: This study evaluated the stability over time and the effect of non-sinus beats on the shortterm heart rate (HR) dynamics analyses.In addition, HR variability was used to study the effect of acute carbon monoxide (CO) exposure.Finally, the possibility was assessed of using non-linear HR dynamics to predict the occurrence of postoperative atrial fibrillation (AF) after coronary artery by-pass grafting.Every two weeks during six months, 131 subjects with stable coronary artery disease (CAD) went through a 40-min ECG recording during a standardised protocol.A set of both conventional and non-linear HR dynamics was analysed; the non-linear HR dynamics with different ways of editing the non-sinus beats.The stability of HR dynamics was analysed by examining the coefficient of variation for repeated measurements.Six subjects with severe CAD underwent simultaneous recordings of ambulatory ECG and CO levels three times with one-week interval.The differences between HR variability preceding and during the CO peaks were analysed.One hundred patients went through a standardised protocol of 10-min rest, paced breathing and head-up tilt one day before coronary surgery.The potential of non-linear HR dynamics to predict the postoperative AF was evaluated.The results indicated that HR dynamics were stable over a period of three to four months.One exception was noted in the standard deviation of normal-to-normal intervalsparameter.In addition, the stability of short-term scaling exponent of detrended fluctuation analysis (DFA ΅1) and approximate entropy remained only moderate.Nonsinus beats remarkably affected non-linear HR dynamics and their stability.The higher levels of acute CO exposure were associated with increased HR variability.The preoperatively reduced DFA ΅1 during rest was an independent predictor of postoperative AF after coronary surgery.In conclusion, most measures of HR dynamics showed acceptable stability among subjects with stable CAD.However, more standardised editing practises are needed.The acute CO altered cardiac autonomic regulation in subjects with severe CAD.Therefore, HR dynamics analysis appears to be feasible for use in air pollution epidemiology.The preoperative non-linear HR dynamics might provide additional information about the pathophysiological factors predisposing to postoperative AF after coronary surgery.
Author: Tuula H. Tarkiainen
Language: English
Subfield: Cardiology and Cardiovascular Medicine
Field: Medicine
Domain: Health Sciences
Open Access status: green
OpenAlex ID: W3095046705