<p>The aim was to study pathophysiological mechanisms and risk factors for developing atrial fibrillation (AF) after coronary artery bypass grafting (CABG), and the effect of thoracic epidural anaesthesia (TEA).</p><p>The study comprised 141 patients undergoing CABG, including 45 patients randomised for TEA intra- and postoperatively. All patients underwent 24-hour Holter monitoring pre- and postoperatively for the analysis of arrhythmias and heart rate variability (HRV). Catecholamines and neuropeptides (reflecting sympathetic and parasympathetic activity), atrial peptides and echocardiographically assessed atrial arias were obtained pre- and postoperatively.</p><p>Logistic regression analysis identified body mass index (BMI), maximum supraventricular beats (SPB) per minute, and total amount of cardioplegia as independent predictors of postoperative AF. Patients developing AF showed limited diurnal variation of HRV preoperatively. All HRV parameters decreased significantly in all patients postoperatively. The significant postoperative increase in atrial areas and atrial peptides did not differ between patients developing AF and those who did not. TEA had no effect on the incidence of postoperative AF, but resulted in lower heart rate, less increase in adrenaline levels, and decreased neuropeptide levels (reflecting sympathetic and parasympathetic activity). AF was initiated by an SPB in 72.4% of non-TEA and 100% of TEA treated patients, whereas changes in heart rate only, before onset, were seen in 17.2% non-TEA patients.</p><p>The observed risk factors, SPB and cardioplegia, may both induce electrophysiological changes known to increase the susceptibility to AF. The observed postoperative atrial dilatation and autonomic imbalance, indicated by HRV and neuropeptide levels, may further favour the development of AF. The observation that a majority of postoperative AF was initiated by a premature atrial contraction supports our hypothesis that latent atrial foci may be a major trigger mechanism of postoperative AF.</p>

The aim was to study pathophysiological mechanisms and risk factors for developing atrial fibrillation (AF) after coronary artery bypass grafting (CABG), and the effect of thoracic epidural anaesthesia (TEA). The study comprised 141 patients undergoing CABG, including 45 patients randomised for TEA intra- and postoperatively. All patients underwent 24-hour Holter monitoring pre- and postoperatively for the analysis of arrhythmias and heart rate variability (HRV). Catecholamines and neuropeptides (reflecting sympathetic and parasympathetic activity), atrial peptides and echocardiographically assessed atrial arias were obtained pre- and postoperatively. Logistic regression analysis identified body mass index (BMI), maximum supraventricular beats (SPB) per minute, and total amount of cardioplegia as independent predictors of postoperative AF. Patients developing AF showed limited diurnal variation of HRV preoperatively. All HRV parameters decreased significantly in all patients postoperatively. The significant postoperative increase in atrial areas and atrial peptides did not differ between patients developing AF and those who did not. TEA had no effect on the incidence of postoperative AF, but resulted in lower heart rate, less increase in adrenaline levels, and decreased neuropeptide levels (reflecting sympathetic and parasympathetic activity). AF was initiated by an SPB in 72.4% of non-TEA and 100% of TEA treated patients, whereas changes in heart rate only, before onset, were seen in 17.2% non-TEA patients. The observed risk factors, SPB and cardioplegia, may both induce electrophysiological changes known to increase the susceptibility to AF. The observed postoperative atrial dilatation and autonomic imbalance, indicated by HRV and neuropeptide levels, may further favour the development of AF. The observation that a majority of postoperative AF was initiated by a premature atrial contraction supports our hypothesis that latent atrial foci may be a major trigger mechanism of postoperative AF.

Background: The ageing process not only increases the risk of coronary artery disease (CAD) but also complicates its diagnosis and treatment. It is therefore important to understand the newer concepts of cardiovascular ageing physiology as well as methods of predicting the outcomes of therapeutic options available for the elderly with severe CAD. Studies of atrioventricular (AV) ring or plane motion have attracted considerable interest in the last few years as a means of assessing ventricular and atrial function. As the displacement of AV rings towards the ventricular apex is a direct reflection of longitudinal fibre contraction, its measurement by echocardiography provides additional information regarding global and regional systolic and diastolic function. Left ventricular (LV) long axis amplitude of motion, referred to as mitral valve annular (MA) motion, is reduced in CAD and to some extent in the elderly as part of the normal ageing process. Objectives &amp; Methods: The aim of the present study was two-fold. First, to investigate the relationship between the timing of MA motion and transmitral and pulmonary venous flow in healthy subjects, and to define the physiological significance of that relationship including its potential diagnostic utility. Second, to investigate the relationship between the clinical outcome and the behaviour of long axis function in patients with severe ischaemic LV dysfunction (SLVD) after percutaneous coronary angioplasty (PTCA). Transmitral early (E) and late (A) filling, and pulmonary venous flow reversal (Ar) were studied by Doppler echocardiography, while at the left lateral AV ring, the MA motion in early (Em) and late (Am) diastole were recorded by Doppler tissue imaging (DTI) and M-mode echocardiography. Results: Healthy subjects – In early diastole the onsets of LV filling (E) and relaxation (Em) were simultaneous, and peak Em preceded peak E by 26 msec in all age groups, constituting a time interval referred to as early diastolic temporal discordance (EDTD). Similarly, the onsets of Am, A and Ar were simultaneous at onset and began approximately 84 msec after the electrocardiographic P wave. Peak Am preceded peak A by 23 msec in the young and by 13 msec in the elderly, a time interval referred to as late diastolic temporal discordance (LDTD). Peak Ar, on the other hand, coincided with peak Am in all age groups. With increasing age and sequential prolongation of isovolumic relaxation time, the peaks of Am, Ar and A converged. This point of convergence is described as atrial mechanical alignment (AMA). Patients – MA total amplitude of motion, rates of shortening and lengthening were all reduced in patients with SLVD. At mid-term, 3-6 months after PTCA, there was improvement in all these variables. A pre-procedure long axis cut off value of ≥5 mm was associated with favourable symptomatic outcome. Overall angiographic success was 95.2%, and event-free survival was 78.4% at one month and declined steadily to 62.3% at one year with 2.5% mortality. Conclusions: EDTD, which reflects ventricular restoring forces (suction) is age independent while the narrowing of LDTD leading to AMA provides a novel method to identify healthy subjects at increased dependency on left atrial contraction for late diastolic filling. Peak atrial contraction (Am) coincides with peak Ar, thus the timing of regional atrial contraction by DTI can be used to estimate corresponding measurements of Ar, which is often difficult to image by transthoracic echocardiography. In patients with SLVD long axis total amplitude of at least 5 mm at the left MA suggests a significant potential for segmental function recovery after PTCA. Keywords: Echocardiography, Doppler tissue imaging, ageing, coronary disease, left ventricular dysfunction, atrial contraction, electromechanical function, coronary angioplasty.