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Objective: Evaluate long-term outcomes in patients undergoing the Convergent procedure (CP) for the treatment of atrial fibrillation (AF)., Background: The CP provides a multidisciplinary approach, combining endoscopic creation of epicardial linear lesions followed by endocardial mapping and ablation and targets persistent and longstanding persistent AF patients who are at increased risk of heart failure, stroke, and mortality., Methods: Outcomes from a prospective nonrandomized study were recorded for consecutive patients by interrogation of implanted Reveal monitors. Rhythm status and AF burden were quantified 6-24 months postprocedure, and compared relative to AF type, gender, age, body mass index, left atrial size, left ventricular ejection fraction, and congestive heart failure, hypertension, age >75 years, age between 65 and 74 years, stroke/TIA/TE, vascular disease (previous MI, peripheral arterial disease or aortic plaque), diabetes mellitus, female (CHA(2) DS(2) VASc)., Results: A total of 50 patients were enrolled with 94% having persistent or longstanding persistent AF. There were 2 atrioesophageal fistulas reported. In one patient, the fistula resulted in death at 33 days postprocedure; in the second, the fistula was surgically repaired but patient died 8 months postprocedure from a CVI. After CP, 95% of patients were in sinus rhythm at 6-month follow-up; 88% at 12 months; and 87% at 24 months. The median AF burden recorded with Reveal XT monitors was 0.0%, 0.1%, and 0.1% at 6, 12, and 24 months with 81%, 81%, and 87% of patients reporting a burden less than 3%, respectively., Conclusion: Using 24 × 7 continuous loop recording, the CP demonstrated success in treating persistent and longstanding persistent AF patients. Endocardial mapping and catheter ablation with diagnostic confirmation of procedural success complemented the endoscopic creation of epicardial linear lesions in restoring sinus rhythm., (© 2012 Wiley Periodicals, Inc.)

Background: Advanced nonlinear methods of measuring heart rate variability (HRV) derived from the mathematics of complex dynamics and fractal geometry have provided new insights into the abnormalities of heart rate behavior in various pathologic conditions. These methods have provided additional prognostic information compared with traditional HRV measures and clearly have complemented the conventional linear methods. Knowledge about the behavior of complex cardiac dynamics indices after different cardiac procedures is very limited, however. We aimed to clarify how nonlinear heart rate dynamics are affected by beating-heart revascularization (off-pump coronary artery bypass graft [CABG] surgery) within the first week after the procedure., Methods: Included in the study were 66 patients who had isolated stable multivessel coronary artery disease and were in normal sinus rhythm. The patients were on chronic beta-blocker therapy and were scheduled for off-pump CABG. We performed 15-minute high-resolution electrocardiographic recordings preoperatively and on the third and seventh postoperative days to assess linear and nonlinear heart rate dynamics. Frequency-domain measurements, detrended fluctuation analysis (DFA) with short-term (11 beats, alpha2) correlation properties of RR-intervals, and fractal dimension (FD) measurements (average, high, and low) were made. Arrhythmia was monitored preoperatively with 24-hour Holter recordings, postoperatively by continuous monitoring for the first 4 days after the procedure, and subsequently by clinical monitoring; 24-hour Holter recordings were obtained again on the seventh postoperative day. We used the paired-samples Student t test, the Mann-Whitney U test, and the Fisher exact test for statistical analyses. Differences in arrhythmia occurrence before and after the procedure were tested with the Wilcoxon signed rank test and the McNemar test. A P level < .05 was considered statistically significant., Results: Values for all frequency-domain parameters decreased significantly after off-pump CABG (P< .001). Values for the alpha1 and high FD parameters decreased significantly after the procedure (P= .028 and .001, respectively), whereas alpha2 increased significantly (P= .023). DFA alpha1 was significantly lower in patients with postoperative atrial fibrillation than in patients remaining in sinus rhythm (mean +/- SD, 0.79+/-0.32 versus 1.13+/-0.45 [P= .003] on the third postoperative day; 0.89+/-0.31 versus 1.22+/-0.34 [P< .001] on the seventh postoperative day), whereas low and average FDs were significantly higher (1.84+/-0.16 versus 1.68+/-0.19 [P= .003] on the third postoperative day and 1.77+/-0.18 versus 1.66+/-0.17 [P= .01] on the seventh postoperative day for the low FD; 1.83+/-0.09 versus 1.76+/-0.10 [P= .011] on the third postoperative day and 1.80+/-0.11 versus 1.73+/-0.10 [P= .014] on the seventh postoperative day for the average FD). The low FD was significantly higher on the third postoperative day in patients with postoperative deterioration of ventricular ectopy than in patients with improved ventricular ectopy (1.74+/-0.17 versus 1.48+/-0.08, [P= .03])., Conclusion: The decreases in alpha1, average FD, and high FD indicate that a profound decay of cardiac complexity and fractal correlation can be observed after off-pump CABG. Furthermore, a more extensive impairment of nonlinear indices was observed in patients who developed postoperative arrhythmias than in those who remained in stable sinus rhythm. Our findings suggest that the postoperative hyperadrenergic setting acts as a preliminary condition in which both reduced and enhanced vagal activity may predispose patients to arrhythmia, indicating that postoperative rhythm disturbances are an end point associated with divergent autonomic substrates.

Non-linear analyses of heart rate dynamics reveal subtle changes not evident from conventional heart rate variability measures. Traditionally, the information was inferred from 24-hour ECG recordings, making it less suitable for clinical application. Moreover, only few studies have attempted to evaluate the reliability of non-linear analyses in relation to varying proportion of artifacts in tracings. In 67 patients revascularized with beating-heart technique, fractal dimension and detrended fluctuation analyses were obtained from 24-hour Holter and 15-minute high-resolution ECG recordings pre and postoperatively. We found strong correlations of non-linear indices between 24-hour and 15-minute recordings (0.54-0.77, p<0.001), unaffected by proportion of artifacts.

Background: Altered autonomic regulation after cardiac operations precipitates cardiac arrhythmias, affects repolarization, and increases the risk of sudden cardiac death. We sought to clarify how the 2 different techniques of coronary artery bypass grafting (CABG), namely conventional CABG using cardiopulmonary bypass (on-pump) and beating-heart CABG without cardiopulmonary bypass (off-pump), affect cardiac autonomic regulation and arrhythmic disturbances postoperatively., Methods: We included 57 consecutive patients, 28 in the on-pump group and 29 in the off-pump group. The electro-cardiographic recordings were performed on the preoperative day and the fourth, seventh, and twenty-eighth day after operation. Fifteen-minute digital recordings were taken; one channel was used to record electrocardiogram and the other breathing. Detailed analyses of arrhythmia, heart rate, and heart rate variability indices were performed on respective days to assess sympathetic and parasympathetic modulation of the heart and relate it to detected arrhythmic disturbances., Results: Total power, low-frequency power, which indicates baroreceptor-mediated sympathetic modulation, and high-frequency power, indicating parasympathetic vagal modulation, declined significantly in both groups after CABG (P < .001); however, 7 days after CABG, total and high-frequency power were better preserved in the off-pump group. Mean RR interval was longer in the off-pump group at 7 (P= .006) and 28 days (P= .008) after surgery. The total incidence of arrhythmic events was higher in the on-pump group on the seventh day (P = .017, adjusted odds ratio = 8.6, 95% confidence interval 1.4-80.3)., Conclusions: The results show profound impairment of cardiac autonomic regulation after CABG, showing better preserved cardiac autonomic modulation 7 days after beating-heart revascularization. Evidence suggests that slower restoration of heart rate and increased incidence of arrhythmic events after CABG using cardiopulmonary bypass are the result not only of impaired cardiac autonomic regulation but also of the involvement of additional factors of nonautonomic origin.

Background: Altered autonomic regulation precipitates cardiac arrhythmias and increases the risk of sudden cardiac death. This risk is further increased by changes in ventricular repolarization. Autonomic regulation is deranged in patients after myocardial on-pump revascularization. We aimed to clarify how off-pump coronary artery bypass grafting (CABG) affects postoperative cardiac autonomic regulation and ventricular repolarization within 4 weeks after CABG., Methods: Forty-two patients (mean age, 61.9 +/- 9.3 years; mean EURO score 2.6 +/- 1.9) were electively admitted for off-pump CABG. The electrocardiographic and respiratory waveform recordings were performed in the afternoon in the supine position for 10 minutes. Autonomic modulation was assessed using heart rate variability analysis. Power spectra were computed from 5-minute stable RR intervals using Fourier Transform analysis. Total power of spectra was defined in the range of 0.01 to 0.40 Hz, high-frequency power within 0.15 to 0.40 Hz, and low-frequency power within 0.04 to 0.15 Hz. Normalized power was defined as a ratio of power in each band/total power. The high- and low-frequency power as well as their normalized values indicated cardiac vagal and sympathetic modulation, respectively. Ventricular repolarization was assessed using QT interval, QT interval variability, and QT-RR interdependence analysis. QT intervals were determined from the beginning of the 5-minute segments. QT interval variability was evaluated by a T-wave template-matching algorithm. Pearson correlation between length of RR and QT interval was applied to study QT-RR characteristics. The results were tested for significance using the Fisher exact test, nonpaired t test, and analysis of variance; a P <.05 was considered significant., Results: The frequency of arrhythmic events and heart rate increased from the fourth to the seventh postoperative day and returned to preoperative levels 4 weeks after CABG. Heart rate variability measures indicating autonomic modulation remained depressed even 4 weeks after the procedure. QT variability index increased from -1.2 +/- 0.5 to -0.8 +/- 0.4 on the fourth day after the operation (P <.05) and returned to -1.0 +/- 0.5 4 weeks after CABG (P = not significant). QT-RR correlation decreased from 0.41 to 0.23 (P <.05) and remained significantly impaired as long as 4 weeks after CABG., Conclusions: Observed faster heart rates until 1 week after off-pump CABG imply excessive adrenergic activation, which is comparable to on-pump CABG procedure rates. The results indicate profound autonomic derangement and loss of rate-dependent regulation after off-pump CABG even 4 weeks after operation. Restituted repolarization as assessed by QT variability index 4 weeks postoperatively corresponded with decreased frequency of rhythm disturbances 4 weeks after CABG. The loss of coupling between QT and RR intervals shows increased electrical instability postoperatively, which may serve as an additional promoter for postoperative arrhythmias, especially at higher heart rates.

The right lateral body position has been proposed as an effective vagal enhancer. However, the possibility of breathing affecting heart rate power spectra in different body positions has not been assessed. The level of vagal modulation in various body positions in normal subjects was estimated by calculating heart rate power spectra. The results suggest that the levels of vagal modulation do not necessarily reflect a change due to assuming different body position, but might be the consequence of changed breathing patterns. Before adopting the right lateral body position as vagal enhancing, the contribution of varying breathing pattern should be eliminated.

Heart rate variability (HRV) and its assessment using power spectral analysis revealed a possibility to quantify the characteristics of autonomic nervous system, related cardiovascular status and sympathovagal interaction. This study was designed to assess vagal tone in supine and right recumbent position in normal healthy subjects as many maneuvers that potentially increase vagal tone have been sought both in normal subjects and in patients with heart disease. Seven subjects, four male and three female, aged 20-27 years were enrolled in the study. To evaluate the time-dependent stability of short term ECG recordings, every subject participated in six ECG recording sessions (three successive morning and three successive afternoon measurements). Heart rate power spectra were obtained by off-line Fast Fourier Transform analysis. The frequency domain measures, namely very low frequency power (VLF), low frequency power (LF), high frequency power (HF) and total power were determined, and their normalized correlates used in the comparison between supine and right recumbent position. Normalized high frequency (nHF) indicated cardiac vagal activity, normalized low frequency power indexed sympathetic modulated activity, low frequency power/high frequency power ratio (LF/HF) represented sympathovagal balance. The results showed remarkable variation among successive day measurements as well as among study subjects. However, several types of response to adopting right recumbent position could be identified. In the first, in right recumbent position the values of nHF, indicator of vagal activity did not differ appreciably from the values measured in supine position. Secondly, there was a tendency towards higher nHF values and lower LF/HF power ratio in supine position. We were not able to notice any appreciable difference among morning and afternoon short-term measurements. Finally, our results do not suggest higher vagal modulation when lying in right recumbent position.