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Background: The study was conducted to investigate the implications of anthropometry in school-aged children on the degree of respiratory sinus arrhythmia observed in clinical settings., Methods: In a cohort study, 626 healthy children (52% male) aged 10.8 ± 0.5 years attending primary school in a single town underwent a 12-lead electrocardiogram coupled with measurements of height, weight and blood pressure. Indices of respiratory sinus arrhythmia (pvRSA, RMSSD, RMSSDc) were derived from semi-automatic measurements of RR intervals. Height, weight, BMI, blood pressure as well as waist and hip circumferences were compared between subjects with rhythmic heart rate and respiratory sinus arrhythmia, and correlations between indices of sinus arrhythmia and anthropometry were investigated., Results: Respiratory sinus arrhythmia was recognized in 43% of the participants. Subjects with sinus arrhythmia had lower heart rate ( p < 0.001), weight ( p = 0.009), BMI ( p = 0.005) and systolic ( p = 0.018) and diastolic ( p = 0.004) blood pressure. There were important inverse correlations of heart rate and indices of sinus arrhythmia (r = -0.52 for pvRSA and r = -0.58 for RMSSD), but not the anthropometry., Conclusion: Lower prevalence of respiratory sinus arrhythmia among children with overweight and obesity is a result of higher resting heart rate observed in this population.

Background: The aim of this study was to investigate syncope recurrence in patients with a 2A cardioinhibitory response to the head up tilt testing (HUT)., Methods: In this study, we enrolled 72 consecutive patients affected by syncope with cardioinhibitory response without asystolic significant pause to HUT (2A type). In these patients, we randomly performed electrophysiological study (ES). In case of sino-atrial node, atrio-ventricular node dysfunction, and sustained arrhythmias induction, the ES resulted positive. ES was positive in 9 patients (group A), then treated by catheter ablation, and/or by devices implants. Otherwise, ES resulted negative (group B), and these patients did not receive an interventional treatment. However, after ES, we evaluated syncope recurrence during 360 days follow-up., Results: There was a lower statistical significant syncope recurrence at follow-up, comparing group A to group B of patients [n of events 9 (40.9%) vs 8 (57.1%), P < .05]. At multivariate analysis, ES result was the only factor predicting syncope recurrence at follow-up (hazard ratio = 27.63, 95% confidence interval = 1.02-54.24, P < .005)., Conclusion: The positivity to ES study, and successful interventional therapies may reduce the burden of syncope recurrence at 360 days follow-up in 2A HUT subjects.Clinical trial number: NCT02861274.

Common physiological manifestations of cocaine are related to its adrenergic effects, due to inhibition of dopamine and norepinephrine uptake at the postsynaptic terminal. Few studies have documented bradycardia secondary to cocaine use, representing the antithesis of its adrenergic effects. We assessed the prevalence of sinus bradycardia (SB) in habitual cocaine users and postulated a mechanism for this effect. One hundred sixty-two patients with a history of cocaine use were analyzed and compared with age- and gender-matched controls. SB was defined as a rate of <60 beats/min and habitual cocaine use as 2 or more documented uses >30 days apart. Propensity score-matching analysis was applied to balance covariates between cocaine users and nonusers and reduce selection bias. Patients with a history of bradycardia, hypothyroidism, or concomitant beta-blocker use were excluded. Mean age of study patients was 44 ± 8 years. SB was observed in 43 of 162 (27%) cocaine users and in 9 of 149 (6%) nonusers (p = 0.0001). Propensity score-matching analysis matched 218 patients from both groups. Among matched patients SB was observed in 25 of 109 (23%) cocaine users and in 5 of 109 (5%) nonusers (p = 0.0001). Habitual cocaine use was an independent predictor of SB and associated with a sevenfold increase in the risk of SB (95% CI 2.52 to 19.74, p = 0.0002). In conclusion, habitual cocaine use is a strong predictor of SB and was unrelated to recency of use. A potential mechanism for SB may be related to cocaine-induced desensitization of the beta-adrenergic receptor secondary to continuous exposure. Symptomatic SB was not observed; thus, pacemaker therapy was not indicated., (Copyright © 2017 Elsevier Inc. All rights reserved.)

Approximately 121,000 bariatric surgical procedures are performed annually, and salutary effects include a reduction in cardiovascular morbidity and mortality, risk factor modification, and improvement in sympathovagal tone. There are anecdotal accounts of unexplained sinus bradycardia (SB) after significant weight loss but no systematic studies have been conducted. The purpose of this study was to determine the frequency of incident SB, its timing, and association with weight loss, clinical characteristics, and predictors. We evaluated various clinical characteristics including resting heart rate, blood pressure, body mass index (BMI), heart rate reserve (HRR), basal metabolic rate, and exercise regimen in 151 consecutive patients who underwent bariatric surgery. Multiple logistic regression analysis was performed to determine predictors of SB. Twenty-five of 137 patients (18%) experienced postoperative SB. Patients with SB had significantly greater reduction in BMI than those without bradycardia (35 ± 9.6% and 25.7 ± 13%, respectively, p = 0.002). HRR was significantly greater in patients with SB (116 ± 14 beats/min) compared with those without bradycardia (105 ± 14 beats/min, p = 0.007). Multiple logistic regression analysis revealed that the odds of developing SB were 1.96 and 1.91 and associated with the percent decrease in BMI (95% confidence interval 1.3 to 3.0, p = 0.002) or increase in HRR (95% confidence interval 1.28 to 2.85, p = 0.002), respectively. In conclusion, SB occurred 14 ± 11 months postoperatively and its predictors were the percent reduction in BMI or increase in HRR., (Copyright © 2014 Elsevier Inc. All rights reserved.)

Theoretical and empirical models describe respiratory sinus arrhythmia (RSA) as a peripheral biomarker of emotion regulation and social competence. Recent findings also link RSA to individual differences in social functioning within autism spectrum disorder (ASD). However, associations between RSA and symptoms of internalizing/externalizing psychopathology in ASD have not been explored. We assessed RSA, social functioning, and internalizing/externalizing symptoms among boys with and without ASD. Compared with controls, participants with ASD evidenced reduced parasympathetic cardiac control, which correlated with social behavior. Symptoms were associated with deficiencies in RSA, over-and-above the contribution of social functioning. These findings yield a more nuanced understanding of parasympathetic function in ASD, and suggest a role for integrative intervention strategies that address socioemotional difficulties.

Introduction and Objectives: In patients with heart failure, left ventricular ejection fraction ≤35% and sinus rhythm without conditions such as atrial fibrillation, thrombus or history of thromboembolic events, the use of anticoagulation is controversial. Our objective was to evaluate the anticoagulation strategy in these patients, variables associated with its use, and its effects on various cardiovascular events., Methods: Of the patients included in the REDINSCOR registry with left ventricular ejection fraction ≤35% and sinus rhythm without other anticoagulation indications (including patients with heart failure from 19 Spanish centres), we compared those who received this treatment with the remaining patients., Results: Between 2007 and 2010, 2263 patients were included, of whom 902 had left ventricular ejection fraction ≤35% and sinus rhythm. Of these, 237 (26%) were receiving anticoagulation therapy. Variables associated with this treatment were a lower left ventricular ejection fraction, ischemic etiology, advanced functional class, wider QRS, larger left atrial diameter, and hospitalization. After 21(11-32) months of median follow-up, there were no significant differences in total mortality (14% versus 12.5%) or stroke (0.8% versus 0.9%). A propensity score adjusted multivariate analysis showed a reduction in a combined end-point including cardiac death, heart transplantation, coronary revascularization, and cardiovascular hospitalization (hazard ratio: 0.74; 95% confidence interval, 0.56-0.97; P=.03) in patients receiving anticoagulation therapy. No information regarding bleeding was collected in the follow-up., Conclusions: In a large and contemporary series of patients with heart failure, left ventricular ejection fraction ≤35% and sinus rhythm, 26% received anticoagulation therapy. This was not associated with lower mortality or stroke incidence, although there was a reduction in major cardiac events., (Copyright © 2011 Sociedad Española de Cardiología. Published by Elsevier Espana. All rights reserved.)

The present study examined the role of cardiovascular regulation in predicting pediatric obesity. Participants for this study included 268 children (141 girls) obtained from a larger ongoing longitudinal study. To assess cardiac vagal regulation, resting measures of respiratory sinus arrhythmia (RSA) and RSA change (vagal withdrawal) to three cognitively challenging tasks were derived when children were 5.5 years of age. Heart period (HP) and HP change (heart rate (HR) acceleration) were also examined. Height and weight measures were collected when children were 5.5, 7.5, and 10.5 years of age. Results indicated that physiological regulation at age 5.5 was predictive of both normal variations in BMI development and pediatric obesity at age 10.5. Specifically, children with a cardiovascular regulation profile characterized by lower levels of RSA suppression and HP change experienced significantly greater levels of BMI growth and were more likely to be classified as overweight/at-risk for overweight at age 10.5 compared to children with a cardiovascular regulation profile characterized by high levels of RSA suppression and HP change. However, a significant interaction with racial status was found suggesting that the association between cardiovascular regulation profile and BMI growth and pediatric obesity was only significant for African-American children. An autonomic cardiovascular regulation profile consisting of low parasympathetic activity represents a significant individual risk factor for the development of pediatric obesity, but only for African-American children. Mechanisms by which early physiological regulation difficulties may contribute to the development of pediatric obesity are discussed.

The authors illustrate how their work on mother-infant "relational psychophysiology" might inform psychotherapy research. They examined psychophysiology in 18 mother-infant dyads (infants' age: 5 months) during normal interaction and a still-face perturbation. They measured respiratory sinus arrhythmia (RSA) as an index of emotion regulation and explored whether skin conductance (SC) concordance, previously linked to therapist empathy, occurs in mothers and infants. During the still-face episode, SC concordance correlated to infant negative engagement. Upon reengagement, when mothers often soothe their infants, concordance instead correlated to behavioral synchrony, an index of maternal sensitivity. Furthermore, maternal RSA became correlated to infant negative engagement. These findings suggest that a mother trying to calm her infant calms herself physiologically and her sensitivity on a behavioral level becomes coherent physiologically. Implications for psychotherapy research are discussed.

Introduction: Atrial electromechanical dysfunction might contribute to the development of atrial fibrillation (AF) in patients with sinus node disease (SND). The aim of this study was to investigate the prevalence and impact of atrial mechanical dyssynchrony on atrial function in SND patients with or without paroxysmal AF., Methods: We performed echocardiographic examination with tissue Doppler imaging in 30 SND patients with (n = 11) or without (n = 19) paroxysmal AF who received dual-chamber pacemakers. Tissue Doppler indexes included atrial contraction velocities (Va) and timing events (Ta) were measured at midleft atrial (LA) and right atrial (RA) wall. Intraatrial synchronicity was defined by the standard deviation and maximum time delay of Ta among 6 segments of LA (septal/lateral/inferior/anterior/posterior/anterospetal). Interatrial synchronicity was defined by time delay between Ta from RA and LA free wall., Results: There were no differences in age, P-wave duration, left ventricular ejection fraction, LA volume, and ejection fraction between with or without AF. Patients with paroxysmal AF had lower mitral inflow A velocity (70 +/- 19 vs 91 +/- 17 cm/s, P = 0.005), LA active empting fraction (24 +/- 14 vs 36 +/- 13%, P = 0.027), mean Va of LA (2.6 +/- 0.9 vs 3.4 +/- 0.9 cm/s, P = 0.028), and greater interatrial synchronicity (33 +/- 25 vs 12 +/- 19 ms, P = 0.022) than those without AF. Furthermore, a lower mitral inflow A velocity (Odd ratio [OR]= 1.12, 95% Confidence interval [CI] 1.01-1.24, P = 0.025) and prolonged interatrial dyssynchrony (OR = 1.08, 95% CI 1.01-1.16, P = 0.020) were independent predictors for the presence of AF in SND patients., Conclusion: SND patients with paroxysmal AF had reduced regional and global active LA mechanical contraction and increased interatrial dyssychrony as compared with those without AF. These findings suggest that abnormal atrial electromechanical properties are associated with AF in SND patients.

Objective: To determine whether patients with different types of anxiety disorder (panic disorder, social phobia, generalized anxiety disorder) have higher heart rate and lower heart rate variability compared with healthy controls in a sample that was sufficiently powered to examine the confounding effects of lifestyle and antidepressants., Methods: The standard deviation of the normal-to-normal intervals (SDNN), heart rate (HR), and respiratory sinus arrhythmia (RSA) were measured in 2059 subjects (mean age = 41.7 years, 66.8% female) participating in The Netherlands Study of Depression and Anxiety (NESDA). Based on the Diagnostic and Statistical Manual of Mental Disorders, 4th Edition (DSM-IV) and Composite International Diagnostic Interview (CIDI), NESDA participants were classified as healthy controls (n = 616), subjects with an anxiety diagnosis earlier in life (n = 420), and subjects with current anxiety diagnosis (n = 1059)., Results: Current anxious subjects had a significantly lower SDNN and RSA compared with controls. RSA was also significantly lower in remitted anxious subjects compared with controls. These associations were similar across the three different types of anxiety disorders. Adjustment for lifestyle had little impact. However, additional adjustment for antidepressant use reduced all significant associations between anxiety and HRV to nonsignificant. Anxious subjects who used a tricyclic antidepressant, a selective serotonin reuptake inhibitor, or another antidepressant showed significantly lower mean SDNN and RSA compared with controls (effect sizes = 0.20-0.80 for SDNN and 0.42-0.79 for RSA). Nonmedicated anxious subjects did not differ from controls in mean SDNN and RSA., Conclusion: This study shows that anxiety disorders are associated with significantly lower HR variability, but the association seems to be driven by the effects of antidepressants.

Objective: Little attention has been paid to possible cardiovascular involvement in patients with chronic fatigue syndrome (CFS), although many of their symptoms and signs suggest cardiovascular dysfunction. Possible cardiovascular symptoms and cardiac function were investigated in CFS patients., Methods: Cardiovascular symptoms were intensively investigated and cardiac function was evaluated echocardiographically., Patients: Fifty-three patients (23 men and 30 women, mean age: 31+/-7 years) with CFS under 50 years were studied., Results: Slender build (body mass index <20 kg/m(2)) was common (47%). Possible cardiovascular symptoms including shortness of breath (32%), dyspnea on effort (28%), rapid heartbeat (38%), chest pain (43%), fainting (43%), orthostatic dizziness (45%) and coldness of feet (42%), were all frequent complaints. Hypotension (28%) was occasionally noted. Electrocardiograms frequently revealed right axis deviation (21%) and severe sinus arrhythmia (34%) suggesting accentuated parasympathetic nervous activity. Small heart shadow (cardiothoracic ratio

Background: To clarify the distinction between anxiety and depression, the tripartite model was introduced. According to this model, physiological hyperarousal (PH, i.e. autonomic hyperactivity) is specific for anxiety and not depression. Research on the relation between anxiety, depression and physiological measures representing arousal is lacking., Methods: Parent- and self-reported anxiety and depressive problems were assessed using the CBCL and RCADS. Heart rate (HR), heart rate variability in the low frequency (HRV LF) and respiratory sinus arrythmia (RSA) were used as indices for autonomic arousal., Results: Parent-reported anxiety was associated with low RSA in supine posture. This association was also found for self-reported anxiety problems, but only in boys. These findings point towards high arousal in anxiety. Self-reported depressive problems were associated with low HRV LF in standing posture and high RSA in supine posture in boys, pointing towards low arousal in depression. However, self-reported depressive problems were also associated with high HR in standing posture and with low HRV LF in supine posture in girls, suggesting high arousal in depression., Limitations: Although HRV LF in standing posture is primarily sympathetically mediated, and HRV LF in supine posture is primarily vagally mediated, the association between HRV LF and sympathetic versus vagal function is not exclusive. Thus, HRV LF measures are merely approaches of high or low arousal., Conclusions: Some evidence was found for hyperarousal in anxiety, but also for hyperarousal in depression. Apparently, the idea of hyperarousal in anxiety and not in depression is too simple to reflect the more complex reality.

Objective: To determine whether foster children showed different autonomic nervous system activity on separation and reunion than control children. Autonomic nervous system activity in foster children was examined in relation to time in placement and disinhibited attachment., Method: The sample included 60 foster and 50 control children between 2 and 7 years of age who participated with their caregivers in a modified Strange Situation. Heart rate, respiratory sinus arrhythmia (RSA), and pre-ejection period were monitored continuously. Foster caregivers reported disinhibited symptoms on the Disturbances of Attachment Interview., Results: The Strange Situation elicited less RSA reactivity in foster children. Differences in RSA, heart rate, and pre-ejection period responses on the specific separation and reunion episodes were not significant. RSA responses on separation from the stranger and on reunion with the foster caregiver were partly explained by time in placement and disinhibited attachment., Conclusions: Early experiences of relationship disruptions in foster children as well as short placements may have an impact on children's adaptation to environmental and relational challenges. Stable placement may facilitate adaptive affect regulation, except for children with disinhibited symptoms.

In this study, we evaluated predictors of resilience among 8- to 12-year-old children recruited from primarily low socioeconomic status neighborhoods, 117 of whom suffered from clinical levels of conduct problems and/or depression, and 63 of whom suffered from no significant symptoms. Tests of interactions were conducted between (a) paternal antisocial behavior and maternal depression and (b) several physiological indices of child temperament and emotionality in predicting (c) children's conduct problems and depression. Both internalizing and externalizing outcomes among children were associated specifically with maternal melancholic depression, and not with nonmelancholic depression. In addition, low levels of respiratory sinus arrhythmia (RSA) among children conferred significant risk for depression, regardless of maternal melancholia, whereas high RSA offered partial protection. Furthermore, high levels of maternal melancholia conferred significant risk for child depression, regardless of paternal antisocial behavior, whereas low levels of maternal melancholia offered partial protection. Finally, low levels of electrodermal responding (EDR) conferred significant risk for conduct problems, regardless of paternal antisocial behavior, whereas high EDR offered partial protection. None of the identified protective factors offered complete immunity from psychopathology. These findings underscore the complexity of resilience and resilience-related processes, and suggest several potential avenues for future longitudinal research.

Objective: To investigate whether externalizing and internalizing problems are related to lower and higher heart rate (HR), respectively, and to explore the relationship of these problems with respiratory sinus arrhythmia (RSA) and baroreflex sensitivity (BRS). Moreover, to study whether problems present at both preschool and preadolescent age show stronger associations with autonomic function than those that were not., Method: In a population cohort of 10- to 13-year-old children (N = 931; 11.6 +/- 0.5 years; 47% boys), autonomic measurements in supine and standing position were performed at school. RSA and BRS were determined by spectral analysis. Current externalizing and internalizing problems were assessed by the Child Behavior Checklist and problems at age 4 to 5 retrospectively by the Preschool Behavior Questionnaire., Results: At supine rest, current externalizing problems were associated with lower HR and higher RSA, but not with BRS and current internalizing problems with higher HR and lower RSA, but not with BRS. These results were specifically found in children with problems that were retrospectively reported to have been also present at preschool age. Standing-induced changes in autonomic parameters were unrelated to the behavioral dimensions., Conclusions: Externalizing and internalizing problems are associated with divergent autonomic patterns, suggesting autonomic underarousal and overarousal, respectively. Problems starting early in life may specifically account for this. This should be confirmed in prospective studies.

Cardiovascular diseases appear to be the most frequent complication and death cause in patients with various forms of occupational diseases. Autonomous nervous system could play significant role in genesis of those complications.

Background: Physiologic pacing has been demonstrated to be effective in preventing atrial fibrillation recurrences in patients with sinus bradycardia. Aim of the study was to evaluate long-term incidence of atrial fibrillation in a large population of patients affected by sinus node disease receiving physiologic pacing. Furthermore, predictors of arrhythmia recurrence and effect of pacing mode were investigated., Population: Four hundred twenty-five patients (220 Male, 77 +/- 9 years) were retrospectively analyzed: implanted system was AAI in 20.5% and DDD in 79.5%. Thirty-four percent had atrial fibrillation before implant., Results: Follow-up lasted on average 51 +/- 36 months (median 42, range 1 month-18 years). Sixty-six percent were on antiarrhythmic drug therapy. After 5 years, 89% survived, 74.5% had at least one episode of atrial fibrillation, 39.9% were submitted to electrical cardioversion, 67.2% were hospitalized because of cardiac causes, 33.3% developed permanent atrial fibrillation. Primary conduction system disease and valvular heart disease were independent predictors for atrial fibrillation recurrence. Preimplant atrial fibrillation predicted arrhythmia recurrence during the follow-up, but it did not predict development of permanent atrial fibrillation. AAI pacing, when compared with DDD, was associated to a lower rate of atrial fibrillation recurrences (AAI 28.7%, DDD 53.3%, P < 0.001)., Conclusion: In spite of expected benefits of physiologic pacing, the development of atrial fibrillation and permanent atrial fibrillation were quite common. The additional benefits of multifunction pacemakers designed to prevent and treat atrial fibrillation should be evaluated in controlled studies.

The main active factor in the progression of chronic heart failure (CHF) is a renin-angiotensin system (RAS), namely its main hormone angiotensin-II, which induces variety effects of given neurohormonal system (vasoconstriction, increased arterial pressure, hypertrophy, and fibrosis). It diminishes the role of the etiological factor and determines the quality to life and prognosis of the disease. Prestarium as an angiotensin-converting enzyme inhibitor significantly improved the functional class (FC) and increased the 6 min distance of walking. In addition, patients reported a slight improvement of life quality. Prestarium consistently improved all major parameters of central hemodynamics, with a statistically significant improvement of end systolic volume and LV ejection fraction by 3 months. Therefore Prestarium improved the clinical status and exerted beneficial effects on LV volumes and LV contractile capability in patients with CHF.

The electrocardiographic parameters of 40 healthy alpacas (Lama pacos) were recorded with a base-apex lead system to establish the normal resting electrocardiographic parameters in this species. The following parameters were measured: heart rate and rhythm, QRS and T morphology, ST segment position, P amplitude and duration, QRS duration and PQ and QT intervals. The heart rate varied between 50 and 110 bpm, with a mean (sd) of 80 (17.8) bpm, and no significant differences were observed between males and females or between alpacas of different ages. Sinus arrhythmia was observed in 35 of the animals, and a regular sinus rhythm was recorded in the other five. The QRS morphology was variable, with an 'rS' pattern observed in 29 animals, 'RS' in six, 'Rs' in three and 'QS' in the other two. A variable morphology was also observed for the T wave, which was positive in 27 animals, negative in seven and biphasic in the other six. All the electrocardiographic parameters were normally distributed and no significant differences were observed between the sexes, except that the amplitude of the P wave was higher in males. The PQ interval was significantly shorter in animals less than six months old.

Several studies on the acute effect of cardiac resynchronization in patients with advanced heart failure (HF) and left bundle branch block (LBBB) have shown that left and biventricular stimulation increase pulse pressure and contractility, while patients with a QRS complex <150 ms may deteriorate during stimulation. Patients with LBBB, severe HF and a QRS width >150 ms underwent right, left and biventricular stimulation at different AV delays. Acute response was defined as > or =10% pulse pressure increase. 165 of 188 patients (88%) in sinus rhythm (47 women, mean age 62.5+/-10 years, ejection fraction 23+/-8%, NYHA class 3.1+/-0.3) were regarded acute responders. 10% of 103 patients with dilated cardiomyopathy and 16.5% of 79 patients with coronary artery disease were considered non-responders. 29 patients (81%) with 2 posterolateral veins were acute responders with 10 of them (33%) being responders in only one vein. 54 patients had a higher pulse pressure increase (10.7+/-10.6%) with atrio-left ventricular stimulation, 48 patients with atrio-biventricular stimulation (9.8+/-6.4%). At one-year follow-up, heart failure had significantly (p<0.0001) improved from NYHA class 3.1+/-0.4 to 2.1+/-0.7, VO(2)peak from 12.7+/-2.8 to 15.9+/-3.6 ml/min/kg. Left ventricular enddiastolic diameter being an indicator of reverse remodeling decreased from 80.5+/-10.5 to 73.3+/-13 (p<0.0001). Hemodynamic testing before CRT allows for the identification of acute non-responders as well as the best mode and site of stimulation and the optimal atrioventricular delay in responders.

Background: This study aims to clarify midterm results of chronic atrial fibrillation elimination after pulmonary vein isolation and provides an evaluation of factors influencing results., Methods: Forty-nine patients were enrolled in this study. We performed a simple pulmonary vein isolation with the aid of cryoablation or radiofrequency ablation directed towards the left posterior remnant of the posterior left atrium. Results were evaluated using elimination rates of atrial fibrillation during the postoperative follow-up for > 12 months. We also examined factors influencing the recurrence of atrial fibrillation., Results: There were no hospital deaths or serious complications among the 49 patients. The total follow-up duration was 137.2 patient years. Forty-seven patients (96%) were followed with serial consultations, but 2 patients were dropped from this study because of changes in residence. Thirty-five of 49 patients (71.4%) showed regular sinus or nodal rhythms at discharge. In 4 patients atrial fibrillation recurred during the follow-up period, whereas in another 4 patients sinus rhythm was restored, although they showed atrial fibrillation at discharge. The cumulative elimination rate was 70.2% (33 of 47 patients), which was determined at the last follow-up period. Large left atrial diameters, a long history of atrial fibrillation, and low-voltage fibrillatory waves in V1 leads were preoperative indicators of recurrence of atrial fibrillation., Conclusions: Pulmonary vein isolations were effective in the treatment of chronic atrial fibrillation patients and sinus rhythms were restored within the follow-up period.

The author examined whether respiratory sinus arrhythmia (RSA) responses to stress predicted resting RSA approximately 3 years later in children and adolescents. A total of 149 children and adolescents (49% girls and women, 44% African Americans) participated in 2 laboratory protocols approximately 3 years apart. RSA reactivity during tasks was consistent within participants across tasks during each session. Resting RSA at Visit 1 explained 17% of the variance in resting RSA at Visit 2 when body mass index, duration between visits, race, gender, and age were controlled for. Visit 1 RSA reactivity explained an additional 5% of the variance in resting RSA at Visit 2. The positive relationship between Visit 1 reactivity and Visit 2 resting levels suggests that larger decreases in RSA during stress predicted lower resting RSA. Conversely, increases in RSA during stress were associated with higher resting RSA an average of 3 years later.

The stability of children's baseline respiratory sinus arrhythmia (RSA) and RSA regulation were examined longitudinally, with a 2-year lag between each of two waves of data collection. Associations between baseline RSA and RSA regulation also were examined in this study. During two laboratory sessions, 2 years apart, children were exposed to two stressors: exposure to an audiotaped conflict between two adults and a problem-solving task in which the child had to trace a star while looking into a mirror. Measures of baseline RSA and RSA regulation during the two stressors were obtained. Baseline RSA and, to a lesser extent, RSA regulation to the star-tracing task were stable over time. Furthermore, baseline RSA was associated with increased RSA suppression to the laboratory stressors. These results augment the scant longitudinal literature on psychophysiological development in elementary-school-age children and young adolescents, and support the proposition that some aspects of RSA constitute stable individual differences at the ages examined., (2004 Wiley Periodicals, Inc)

Study Objectives: To compare the frequency of daytime and nocturnal cardiac arrhythmias and ST-segment depression episodes among patients with obstructive sleep apnea-hypopnea syndrome (OSAHS), snoring subjects, and healthy subjects, and to analyze the relationship between the cardiac disturbances, sleep characteristics, and sympathetic tone in patients with OSAHS., Patients and Interventions: Twenty-one consecutive patients with OSAHS, 12 snorers without hypersomnolence, and 15 healthy subjects were selected. Polysomnography, 24-h Holter ECG recording, and urinary catecholamine determination were simultaneously performed on all subjects., Results: Patients with OSAHS had more daytime and nocturnal episodes of sinus and supraventricular arrhythmias and couplets than the snoring and control groups. Moreover, nocturnal ST-segment depression episodes were more frequent in the OSAHS group than in control subjects (0.565 +/- 0.826/h vs 0 +/- 0/h [mean +/- SD]). In patients with OSAHS, arousal index and daytime epinephrine levels were related to daytime and nocturnal ST-segment depression episodes, whereas minimum arterial oxygen saturation was related to nocturnal sinus bradycardia and supraventricular tachycardia. Epinephrine and norepinephrine urinary concentrations correlated with sinus and supraventricular arrhythmias., Conclusions: Patients with OSAHS have a higher frequency of cardiac rhythm disturbances and ST-segment depression episodes than snoring and control subjects. Moreover, ST-segment changes are related to sympathetic tone and sleep fragmentation, whereas most of the rhythm disturbances in patients with OSAHS are associated with sleep fragmentation, nocturnal hypoxemia, and sympathetic tone.

The present study examines the associations between narrative processing, narrative production, and cardiac rate and variability in children. Heart period (HP) and vagal tone (VT) were computed for fifty-eight 7-year-olds (29 males) during a resting baseline and during epochs in which the children listened to and completed a selected set of story-stems from the MacArthur Story-Stem Battery (I. Bretherton, D. Oppenheim, H. Buchsbaum, R. N. Emde, & the MacArthur Narrative Group, 1990). Significant decreases in HP and VT were observed between a resting baseline and epochs of story-stem presentation by the experimenter. In addition, HP was shorter and VT lower during children's narrative production to emotionally laden story-stems compared with narration to a neutral story-stem. Furthermore, narrative and cardiac responses to stories containing separation-reunion themes reflected increased emotional and cognitive load compared with responses to stories that did not contain such themes. Finally, children who showed VT suppression in response to emotion-laden stories produced more coherent and adaptive narratives compared to those of children who did not show VT suppression. The findings suggest interplay between the cognitive-emotional processes associated with narrative processing and production and cardiac activation patterns., (Copyright 2004 Wiley Periodicals, Inc. Dev Psychobiol 44: 238-249, 2004.)

The aim of our study is to provide data on the prevalence of disturbances of rhythm in the general population of children. Accurate estimates of true prevalence of such disturbances of rhythm from large samples are mandatory if we are to interpret properly electrocardiographic abnormalities. We analysed prevalence of disturbances of rhythm in a population of 152,322, comprised of 71,855 elementary school students, 36,692 males and 35,163 females, aged from 5 to 6 years, and 80,467 students of junior high school, 41,842 males and 38,625 females, aged from 12 to 13 years. We analysed the prevalence of premature atrial and ventricular contractions, first, second and third degree atrioventricular block, incomplete and complete right bundle branch block, Wolff-Parkinson-White syndrome, and prolongation of the QT interval. The prevalence of disturbances of rhythm in total rose with age, being found in 1.25% of elementary school students and 2.32% of junior high school students, and was higher in males than females, at 2.00% as opposed to 1.38%, both values being statistically significant at a level of less than 0.0001. Prevalences of all types of rhythmic disturbances were higher in junior high school students than elementary school students (p < 0.0001). Premature atrial and ventricular contractions and prolongation of the QT interval were higher in female than male students, at percentages of 0.089, 0.497, and 0.02 for males, and 0.123, 0.534 and 0.027 in females (p < 0.0001). In contrast, incomplete and complete right bundle branch blocks were higher in males than females, at 0.983% and 0.083% in males versus 0.410% and 0.161% in females (p < 0.0001). Disturbances of rhythm increased with age, and conduction disturbances were higher in male students than female, although premature atrial and ventricular contractions and prolongation of the QT interval were more frequent in female. These data may be useful for future comparative studies of disturbance of rhythm in children.

Introduction: Reports suggest that coronary sinus (CS) or left atrial ablations may be necessary for treatment of AV nodal reentrant tachycardia (AVNRT) with earliest retrograde atrial activation in the CS. We assessed the efficacy of standard right atrial catheter ablation approaches in these tachycardias and determined the incidence of earliest activation in the CS in AVNRT., Methods and Results: We retrospectively evaluated intracardiac recordings from 225 consecutive patients who underwent electrophysiologic studies and radiofrequency (RF) ablation for AVNRT in two institutions. Atrial activation during AVNRT was evaluated using multiple catheters according to standard protocol used in our laboratories. RF ablations in the triangle of Koch were performed in all patients. Eighteen of 225 patients (8%) had earliest activation in one of the CS poles. The demographics and AVNRT characteristics of these 18 patients were similar to those of the other 207 patients who did not have CS as earliest activation site and included both typical and atypical AVNRT. Following RF ablation, none of the 18 patients had inducible AVNRT., Conclusion: Successful RF ablation can be performed at standard sites in the triangle of Koch regardless of earliest site of atrial activation. The incidence of CS as earliest retrograde atrial activation site in AVNRT is 8%.

Atrial fibrillation is the most common sustained cardiac arrhythmia. Treatment strategies are focused on reducing symptoms and minimizing the risks of atrial fibrillation like stroke and heart failure. First choice therapy is the rhythm control strategy, with restoration of sinus rhythm. Drawback of this approach is the low success rate for maintenance of sinus rhythm. Outcome will improve with the use of antiarrhythmic drugs after electrical cardioversion, unfortunately exposing the patient to the risks of life threatening pro-arrhythmia. The second alternative, a rate control strategy, is easy to achieve but it is unknown whether this treatment strategy results in higher morbidity and mortality rates. RACE (RAte Control versus Electrical cardioversion for persistent atrial fibrillation) was a prospective randomized trial comparing both strategies. The primary end point was a composite of death from cardiovascular causes, heart failure, thromboembolic complications, bleeding, pacemaker implants and severe adverse effects of drugs. After a mean follow-up of 2.3 years, the primary end point occurred in 44 of the 256 rate control patients (17.2%) and 60 of the 266 rhythm control patients (22.6%). Other trials as the AFFIRM (Atrial Fibrillation Follow-up Investigation of Rhythm Management), PIAF (Pharmacological Intervention in Atrial Fibrillation) and STAF (Strategies of Treatment of Atrial Fibrillation) also found that rate control was not inferior to rhythm control in terms of morbidity, mortality and quality of life. These four randomized trials demonstrated that a rate control strategy is an acceptable alternative to rhythm control in patients with recurrent atrial fibrillation. For those with severely symptomatic atrial fibrillation, continued rhythm control is unavoidable. For these patients, safer and more effective methods of maintaining sinus rhythm are needed to reduce morbidity related to palpitations and atrial fibrillation-induced heart failure.Furthermore, the randomized studies showed that rhythm control therapy does not prevent stroke. It was observed from RACE that 21 of the 35 thromboembolic complications occurred under rhythm control, the majority while receiving inadequate anticoagulation therapy. Also in AFFIRM, with patients with one or more stroke risk factors, more strokes were present under rhythm control. Therefore, one of the main lesson learned from the randomized studies is that anticoagulation must be continued if stroke risk factors are present even if patients maintain sinus rhythm.

Postoperative arrhythmia is a major cause of morbidity and mortality after cardiac surgery for congenital heart disease. Rhythm disturbances that may be well tolerated in a normal heart often cause hemodynamic instability when they occur in the immediate postoperative period. In the face of pre-existing myocardial dysfunction resulting from preoperative pressure or volume overload, patients with congenital heart conditions are especially vulnerable to rhythm disturbances after cardiac surgery. Cardiopulmonary bypass, intraoperative injury to the conduction system and myocardium, postoperative metabolic abnormalities, electrolyte disturbances, and increased adrenergic tone in response to the stress of the surgery or inotropic agents are also known factors associated with increased risk of arrhythmia in the immediate postoperative period. Surgically related arrhythmia can also present in the late postoperative period, particularly in association with surgical incision sites and surgically induced hemodynamic abnormalities. Early and late postoperative arrhythmias are important risk factors for morbidity and mortality after surgical treatment of many forms of congenital heart disease. This review describes the incidence of the most common forms of arrhythmia and recent advances in their diagnosis and treatment.

Introduction: Striated myocardial connections between the venous wall of the coronary sinus (CS) and the left atrium have been described in humans. This aim of this study was to investigate the conduction properties and potential arrhythmogenicity of CS and left atrial myocardial connections in patients with and patients without paroxysmal atrial fibrillation (PAF)., Methods and Results: Thirty-eight patients with PAF, 52 patients with other arrhythmias, and 44 patients without arrhythmia underwent catheter mapping of the CS from the distal superoposterior part to the ostium. Catheterization of the superoposterior CS was feasible in 21, 32, and 25 subjects in the three groups, respectively (P = 0.82). Discrete double potentials or fractionated electrograms were recorded during proximal CS or right atrial pacing in 14 (66.7%), 11 (34.4%), and 5 (20.0%) patients, respectively (P = 0.004). In 29 patients, double or fractionated potentials were recorded at the distal superoposterior CS, in 3 at the mid-CS, and in 4 at the ostium. Spontaneous or induced atrial ectopy and/or tachyarrhythmias were recorded in 18 (85.7%), 12 (37.5%), and 2 (8.0%) patients in the three groups, respectively (P < 0.001) and originated from the CS in 6, 3, and 0 patients, respectively (P = 0.010)., Conclusion: Recording of double potentials is possible within the CS, particularly at its distal superoposterior part, near the left superior pulmonary vein. Their prevalence is higher in patients with PAF than in subjects with other or no arrhythmias, and their presence denotes possible sources or substrate for atrial arrhythmia.

Introduction: Studies in Europe and America showed that tachycardia, less often bradycardia, frequently accompanied partial seizures in Caucasian patients. We determine frequency, magnitude and type of ictal heart rate changes during partial seizures in non-Caucasian patients in Singapore., Methods: Partial seizures recorded during routine EEGs performed in a tertiary hospital between 1995 and 1999 were retrospectively reviewed. All routine EEGs had simultaneous ECG recording. Heart rate before and during seizures was determined and correlated with epileptogenic focus. Differences in heart rate before and during seizures were grouped into 4 types: (1) >10% decrease; (2) -10 to +20% change; (3) 20-50% increase; (3) >50% increase., Results: Of the total of 37 partial seizures, 18 were left hemisphere (LH), 13 were right hemisphere (RH) and 6 were bilateral (BL) in onset. 51% of all seizures showed no significant change in heart rate (type 2), 22% had moderate sinus tachycardia (type 3), 11% showed severe sinus tachycardia (type 4), while 16% had sinus bradycardia (type 1). Asystole was recorded in one seizure. Apart from having more tachycardia in bilateral onset seizures, there was no correlation between side of ictal discharge and heart rate response. Compared to Caucasian patients, sinus tachycardia was considerably less frequent. Frequency of bradycardia was similar to those recorded in the literature., Conclusions: Significant heart rate changes during partial seizures were seen in half of Singaporean patients. Although sinus tachycardia was the most common heart rate change, the frequency was considerably lower compared to Caucasian patients. This might be due to methodological and ethnic differences. Rates of bradycardia are similar to those recorded in the literature.

Systemic lupus erythematosus is a disease in which inflammatory process provoked by different antibodies affects many organs and systems. The circulatory system is one of them. In patients with systemic lupus erythematosus cardiac disorders are generally known and well proved. It is known that this disease has heritage background. Thus, the offsprings of patients suffering from systemic lupus erythematosus belong to a risk group. Moreover, it is thought that maternal antibodies crossing transplancentally to the fetus cause damages of tissues including the heart. The aim of this study was to evaluate cardiological status of 38 children whose mothers suffered from systemic lupus erythematosus. In all sick mothers the diagnosis fulfilled criteria of the American Rheumatism Association. The mothers have been remaining under medical treatment while the children have been under control and simultaneously prophylaxis of lupus has been undertaken. The study was undertaken in 17 girls and 21 boys aged 3 to 18 years (average: 12 +/- 4.5 years). Physical development of presented children was satisfactory. During cardiological examination all subjects were in good general condition, without any clinical evidence of collagen disease and infection. Obtained results were compared with the ones found in control group of 38 children of healthy mothers, being at the same age. Study methods were: physical examination, arterial blood pressure measurement, standard and 24 hours according to Holter method ECG record, echocardiographic and Doppler examination, and physical performance test according to Bruce's protocol. In children of sick mothers examined laboratory parameters were within the normal limits excluding the presence of antinuclear antibodies (controlled by indirect immunofluorescence test), result of which was positive in 15 studied children (39%). In the group of the children of sick mothers the abnormalities of sinus node function were detected in 12 cases (32%), significantly more often than in the control. There were found abnormalities of atrio-ventricular and intraventricular conduction in 15 subjects (40%). The premature beats of ventricular origin were noticed in 3 cases (8%). These disturbances were significantly different from the control group. In addition, correlation between the presence of antinuclear antibodies and the cardiac abnormalities was taken into consideration. So, significant correlation between antinuclear antibodies and heart rhythm disorders was proved. During echocardiographic examination structural and functional abnormalities were found. They were: ventricular septal defect (muscular part) (1), pericarditis effusion (1), prolapse of the mitral valve anterior leaflet (2), mitral valve regurgitation of the second degree (2) and increased diameter of left atrium (8). One girl from the studied group, suffering from atrio-ventricular block of III* was operated on because of persistent ductus arteriosus still in the newborn's period. At the same time the permanent pace-maker was implanted. After 1 year of age this girl was operated on because of atrial septal defect (ASD II). In studied group of children echocardiographic global indices of left ventricular systolic function were normal. The subclinical impairment of diastolic left ventricle function was found in 8 children with increased left atrium-aorta index. Both the theoretical knowledge and the results of the studies suggest that the offsprings of mothers suffering from SLE need a careful cardiological observation.

Objective: To determine the incidence of and risk factors for unexplained paroxysmal bradycardia in children treated with high-frequency oscillatory ventilation (HFOV)., Design: A nested case-control study., Setting: A university-affiliated children's hospital., Subjects: All children treated with HFOV for at least 3 days during a 2-year period and a randomly chosen comparison group of 50 children treated with only conventional mechanical ventilation (CMV) for at least 3 days during the same time period., Interventions: None., Measurements and Results: Unexplained paroxysmal sinus bradycardia occurred in six children (12%) receiving HFOV, and was significantly more common than in children treated with CMV (0%). The bradycardic events occurred after the lung disease started to improve, and the mean airway pressure (mPaw) at the time of the bradycardias was significantly decreased from the child's maximal mPaw. The bradycardic events were effectively treated acutely with manual ventilation or atropine sulfate, and resolved completely after the patient was changed to a regimen of CMV., Conclusion: Unexplained paroxysmal bradycardia associated with HFOV in children is not uncommon. It completely resolves with conversion to CMV and may be related to overdistention of alveoli as compliance improves.

321 electrocardiographies (ECG) from the staffs exposed to microwave in a radio calling signal station were analysed. The subjects exposed to microwave were female computer operators, who worked over six months in the station. 107 female non-exposers were served as control. The intensities of microwave in work site were below the standard (20-50 mW/m2). The abnormal prevalence of ECG in the exposed group was 27.73%, which was significantly higher than that in the control group (11.21%, P<0.01). The prevalence of sinus arrhythmia in exposed group (19.63%) was significantly higher than that in the control group (5.60%, P<0.01). The P-R intervals were also lengthened in exposed group [(0.1554+/-0.021) ms] than that in control group [(0.1487+/-0.0227) ms, P<0.01]. No significant differences were found in the heart rate, QRS intervals, Q-T intervals, sinus bradycardia, sinus tachycardia and left axis deviation between exposed and control groups (P>0.05). It suggested that computer operators exposed to microwave of lower intensity in the radio calling signal station might lead to sinus arrhythmia, due to the disorder of vegetative nerve system.

The extension of the RAM memories in the latest generation of pacemakers has enabled development of Holter function allowing continuous surveillance of the cardiac rhythm. Between October 1991 and February 1995, 213 patients implanted with a Chorus 6234 or 7034 (Ela Medical) pacemaker, functioning in the DDD (R) mode, were followed up using the implanted continuous Holter function. Of the patients with no documented supraventricular arrhythmia (SVA) before implantation (n = 154), 67 (43.5%) developed SVA during an average period of one year. Male patients (p = 0.01; OR = 7.5 on multivariate analysis), high degrees of AVB (p = 0.03) and the presence of isolated or bursts of atrial extrasystoles (p = 0.004) were independent risk factors for SVA. The average time to detection of SVA was 207 days. In patients with documented SVA before implantation (n = 59), 22 (37.3%) had no recurrence during follow-up; in the other 37 cases, the average period before recurrence was 127 days. Multivariate analysis did not reveal any independent risk factor for recurrence of the arrhythmias. On the other hand, persistent but delayed atrioventricular conduction (1 degree AVB, long H-V interval or bifascicular block), seemed to protect against SVA, independently of other variables and of antiarrhythmic therapy (p = 0.008). These results suggest a high prevalence of SVA in patients on long-term pacemaker therapy, most episodes being asymptomatic. The implanted Holter function would therefore seem to be an essential tool for investigating and following up the natural history of arrhythmias in these patients.

A family was investigated because of heart block and sinus arrhythmia. The electrical characteristics were: (1) adult onset in all members; (2) complete heart block with atrial fibrillation in 2, and first- or second-degree heart block in 7 members; and (3) sinus arrhythmia in 3 members. Human leukocyte antigen (HLA) typing was performed. HLA A2, B39, Cw7, and DR12 were positive in 4 of 5 members in the heart block group. In the sinus arrhythmia group, HLA DR12 was positive in all members. In the normal group, none of these HLA typings was positive except one. These findings indicate a tighter relationship between heart block and the HLA locus than previously thought.

In order to prolong the service life of the generator, the isotopic pacemakers, powered by Pu238, have been developed and implanted since 1970. We report the follow-up of 325 patients (mean age 39 +/- 18 years) implanted with an isotopic pulse generator (Medtronic 9000/9090) between April 1970 and July 1982. The mean follow-up was 12 years (range 6 days to 18.5 years). The generator was highly reliable; the mean value of pacing rate between implantation and last follow-up decreased significantly but no more than 1 beat/min (72.7 vs 71.8 beats/min; P < 0.001) and the pulse width did not change significantly. The actuarial survival of the device was 97% at 18.5 years. During the follow-up period, 122 reoperations were performed in 85 patients: 88 explanations of the entire pacing system and 34 modifications of the lead system. Lead dysfunction accounted for 68% of the 122 reoperations, generator failure for 6%, and miscellaneous reasons for 26%. However, 72% of patients remain free of intervention during the follow-up period and 61 patients (20%) died during this period. Most deaths (52%) were of nonsudden cardiovascular origin, 17% were related to cancer, and 13% to sudden death. After 5, 10, and 18.5 years, 94%, 89%, and 73% of the patients were alive, respectively. No side effect could be attributed to the radioisotope. We conclude that this isotopic pacemaker demonstrated its reliability for long-term cardiac pacing.

Objectives: This study aimed to examine changes over time in sinus mode function after cardiac transplantation; to determine the incidence, natural history and etiology of sinus node dysfunction in transplant recipients; and to identify any early predictors of long-term sinus node function., Background: Bradyarrhythmias caused by sinus node dysfunction are common immediately after cardiac transplantation. Existing electrophysiologic studies have been limited by small numbers and have reported an unexpectedly high incidence of sinus node dysfunction (approximately 50%) compared with the incidence of bradyarrhythmias in other studies. There have been no previous studies reporting serial electrophysiologic data. Thus, the natural history of sinus node dysfunction after transplantation has not been adequately described., Methods: Serial electrophysiologic studies of sinus node function and 24-h ambulatory electrocardiographic recordings were performed at 1, 2, 3 and 6 weeks and 3 and 6 months after transplantation in 40 adult recipients., Results: The overall incidence of sinus node dysfunction was 17.5% (7 of 40). Six patients (15%) had sinus node dysfunction from week 1; one developed sinus node dysfunction at 3 months. Sinus node recovery time returned to normal by 6 weeks in all six patients with early sinus node dysfunction, but abnormalities of sinoatrial conduction persisted in two. Two patients who required pacing during ambulatory monitoring at 2 weeks after transplantation (temporary pacemaker 50 beats/min, demand) received a permanent pacemaker. One patient required pacing at 3 weeks and continued to require pacing 6 months after transplantation., Conclusions: The incidence of sinus node dysfunction after cardiac transplantation is lower than has been previously reported in electrophysiologic studies. Sinus node automaticity improves with time, although abnormalities of sinoatrial conduction may persist. The best predictor of permanent pacing requirements is the temporary pacing requirements during 24-h Holter monitoring 2 and 3 weeks after transplantation, with temporary pacing set at 50 beats/min on demand.

Two quantitative techniques have been evaluated to examine whether respiratory sinus arrhythmia can be detected in atrial fibrillation. Cyclical changes in heart rate during deep breathing indicating respiratory sinus arrhythmia were seen in 11/15 control patients, but only 1/44 patients with atrial fibrillation. Power spectrum analysis suggested that more subtle variations in heart rate with breathing may be present in some patients with atrial fibrillation where it was not detectable by simpler techniques. These results support the hypothesis that although respiratory sinus arrhythmia is not detectable in atrial fibrillation by conventional means, there may still be some mediation of heart rate either by vagal or extravagal mechanisms.

Two of six domino transplantations performed at our institution required permanent pacemaker implantation as a result of persistent sinoatrial node dysfunction and symptomatic nodal rhythm. Retrospective analysis of several potential etiologic factors showed that the only obvious difference between these two patients and the remaining four domino transplant recipients without this complication was the technique used during harvesting of the cardiac graft. The hearts from the two patients with sinoatrial node dysfunction were harvested using a "right atrial cuff preservation" technique, and the hearts of the remaining four patients were harvested with a standard bicaval division technique. Based on this experience, we think that this right atrial cuff preservation harvesting technique carries a potential risk for sinoatrial node damage, and we do not recommend its use for domino transplantation.

Although rate adaptive pacemakers are now frequently prescribed, there is limited information regarding long-term follow-up of patients with a pacemaker capable of rate adaptation. We have examined our patients in whom a pacemaker capable of rate adaptation via a sensor that determines minute ventilation has been implanted. After following a group of 42 patients for a mean of 13.2 months we have found this to be a reliable rate adaptive pacing system. The sensor was reliable long term, the system is easy to program, and sensor settings were changed infrequently.

Several varieties of pulmonary artery catheters (PACs) with pacing capabilities are now available. Although specific recommendations for prophylactic perioperative placement of pacemakers have been offered previously, the authors believe that those recommendations warrant further examination, taking into consideration the availability of new pacing modalities. Toward this end, the use of pacing PACs in cardiac surgical patients was prospectively examined. In 600 consecutive adult patients with PACs placed prior to cardiopulmonary bypass (CPB), the cardiac anesthesiologist recorded if a pacing PAC was placed, the indications for placing it, and whether the catheter was used to pace. If a pacing PAC was not chosen, the anesthesiologist indicated whether cardiac pacing was needed prior to CPB. In all patients, the presence and specifics of the following five possible indications were documented: sinus node dysfunction/bradydysrhythmias, atrioventricular heart block, fascicular or bundle branch block, cardiac reoperation, and/or valvular heart disease. PACs with pacing capability were placed in 180 of the 600 patients (30.0%) and were used in 34 of these 180 patients (18.8%). In 4 of 420 patients (0.95%) without pacing PACs, cardiac pacing was needed prior to CPB. The following preoperative diagnoses were significant predictors (P less than .05) for the use or need for pacing catheters: sinus node dysfunction/bradydysrhythmias, a history of transient complete atrioventricular block, aortic stenosis, aortic insufficiency, and reoperation. The majority of adult patients undergoing cardiac surgery do not require the use of a pacing PAC prior to CPB.(ABSTRACT TRUNCATED AT 250 WORDS)

We investigated incidence, normalization rates, and clinical significance of sinus node (SN) dysfunction after cardiac transplantation. Thirty-nine of 90 patients systematically evaluated presented with impaired SN function in the postoperative period. Of these, 22 normalized their SN function during follow-up while 17 remained impaired after 3 months. The proportion normalized was higher in patients with prolonged SN recovery time (11/16, 68.8%) and those reverting from escape rhythm to sinus rhythm until discharge (5/8, 62.5%) when compared to patients in escape rhythm throughout the postoperative period (5/11, 45.5%) or pacemaker dependence (1/4, 25%). There was no reliable postoperative predictor of normalization and necessity of long-term pacing. A postoperative heart rate consistently less than 70 beats/min (irrespective of the native rhythm) was significantly related to outcome (P = 0.01), but revealed unacceptable sensitivity (61.5%) and specificity (81%). After all, both patients with severe symptoms (near syncopes and syncope), were derived from this group. These two patients, who had been discharged in sinus rhythm, had late pacemakers implanted. An additional 17 patients had early pacemaker placement, only seven of which were constantly paced during follow-up. Given the low normalization rates, patients with postoperative escape rhythm are those most likely to benefit from pacemaker therapy over the long term. Even those in, or reverting back to, sinus rhythm until discharge may experience severe symptoms, particularly in the setting of a postoperative rate consistently less than 70 beats/min since this indicates a relatively lower probability of recovery.

In 17 controls, and 17 patients with sinus nodal dysfunction, an electrophysiologic study was made of sinus nodal function and atrioventricular nodal conduction in the basal state. The study was then repeated in all patients after atropine. The heart rate, mean sinus cycle length, variations of sinus cycle length, sinus node recovery times, sinuatrial conduction time, AH interval, and atrioventricular nodal Wenckebach threshold were significantly different in patients from those of controls. All these parameters changed significantly in patients after atropine, and were comparable to those of controls except for the atrioventricular nodal Wenckebach threshold. Atropine failed to increase the heart rate beyond 90 beats per minute in 10 of 17 patients (sensitivity of 59%) or by at least 30% above the resting heart rate only in 4 of them (sensitivity of 24%). The variations of sinus cycle length, and their standardized value, could detect sinus nodal dysfunction with sensitivities of 59 and 47%, respectively. From our results, we conclude that there is parasympathetic overactivity in patients with sinus nodal dysfunction. Because of their very low sensitivities, the atropine test and variations of sinus cycle length were not useful in identifying sinus nodal dysfunction noninvasively. The normal response of the heart rate to atropine does not exclude sinus nodal dysfunction, but atropine may help to differentiate abnormalities intrinsic and extrinsic to the sinus node during the electrophysiologic study.

The indications for and timing of permanent pacing were reviewed in all 17 of 154 adult heart transplant recipients at this center who have had permanent pacemakers implanted. Resting 12-lead ECGs recorded during routine follow-up were examined. A prospective study of pacing requirement was then undertaken. Holter monitoring was performed before and after reprogramming the pacemakers to VVI mode at 50 beats/min. Exercise responses in various pacing modes were then assessed in seven patients with rate responsive pacemakers using a standard Bruce protocol treadmill test. The indication for pacing was sinus node dysfunction in 59% (10/17) and atrioventricular (AV) block in 41% (7/17). The majority of pacemakers were implanted between seven and 21 days after transplantation. There was a progressive reduction in the frequency of pacing on 12-lead ECGs with time after transplantation. There was a progressive reduction in the frequency of pacing on 12-lead ECGs with time after transplantation. Eight of 14 patients with empirically selected programming paced during Holter monitoring. After reprogramming to 50 beats/min VVI mode only three of 14 patients, all with sinus node dysfunction, paced. Rate responsive pacing made no difference to exercise time. The requirement for long-term pacing in cardiac transplant recipients is small (3/154) and is limited to patients with sinus node dysfunction. Rate responsive pacing did not increase exercise tolerance.