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Background: It is inevitable for patients to have a temporary or permanent pacemaker implanted during or after radiofrequency catheter ablation (RFCA) for treatment of atrial fibrillation (AF) in some cases. The aim of our study was to evaluate the incidence of pacemaker implantation (PMI) during or within 3 months of RFCA for AF and to identify the risk factors that were associated with PMI. Methods: We performed a retrospective analysis of consecutive AF patients who underwent RFCA between August 2018 and October 2020 at our center. The incidence of PMI within 3 months during or after RFCA were assessed. A multivariate logistic regression model was performed to identify predictors of PMI. Results: One thousand and five patients (mean age, 60.2 ± 10.3 years; 37.6% women) were included in this analysis. PVI was performed in all patients. A total of 23 (2.3%) patients had a pacemaker implanted within 3 months during or after ablation. Multivariable logistic regression analysis revealed that older age (OR: 1.08 [95% CI 1.03‐1.13], p =.003), female sex (OR: 3.08 [95% CI 1.28‐7.45], p =.012), paroxysmal AF (OR: 4.71 [95% CI 1.09‐20.45], p =.038) and repeated ablation (OR: 2.78 [95% CI 1.04‐7.40], p =.041) were the independent predictors for PMI. Conclusions: Older age, female sex, paroxysmal AF and repeated ablation were identified as predictive risk factors for PMI after RFCA in patients with AF. A "watch and wait" strategy could be taken for patients with temporary PMI after ablation, especially for those with prolonged sinus pause after AF termination. [ABSTRACT FROM AUTHOR]

Open in new tab Download slide Open in new tab Download slide OBJECTIVES This study aimed to clarify the incidence of sinoatrial nodal artery (SANa) injury in thoracoscopic epicardial surgical ablation for atrial fibrillation (AF) and its impact on postoperative outcomes, which have not been previously elucidated. METHODS We enrolled 103 consecutively patients with AF who underwent thoracoscopic epicardial ablation at our institution. In these patients, we evaluated the postoperative incidence of SANa injury by using enhanced cardiac computed tomography. For patients with confirmed SANa injury, 3-day continuous electrocardiographic monitoring and exercise stress tests were performed to assess the sinus rhythm maintenance and sinus node function. RESULTS Thirteen patients (12.6%) had a confirmed SANa injury (left anterior type in 6 patients, left posterior type in 2 patients and double-branch type in 5 patients). After a median follow-up of 24 months, the patients with SANa injury were not found to be associated with lower sinus rhythm maintenance (hazard ratio 1.09, 95% confidential interval 0.36–3.31) as compared with those without SANa injury after adjustment for patient characteristics. Sinus node function was evaluated in 7 patients with SANa injury who remained in sinus rhythm after the procedure, and no sinus node dysfunction was confirmed in the 3-day electrocardiographic monitoring and exercise stress tests at a median follow-up of 12 months. CONCLUSIONS The prevalence of SANa injury in the patients who underwent thoracoscopic epicardial ablation for AF was relatively low, and the incidence of SANa injury was not associated with postoperative restoration of sinus rhythm and sinoatrial node dysfunction. More studies are required to better understand SANa injury. [ABSTRACT FROM AUTHOR]

Background and Objectives: Sinus pause association of paroxysmal atrial fibrillation (PAP) is generally considered a sinus node dysfunction (SND) known as tachycardia-bradycardia syndrome (TBS). Cure of tachyarrhythmias in some patients with prolonged pauses on termination of tachyarrhythmia resulted in an improvement in sinus node function and/or a return to normal ranges thus avoiding the need for permanent pacing. The purpose of this study was to investigate the electrophysiological and clinical characteristics as well as their sinus node function in patients with prolonged pauses and PAP. Methods and Results: Of 1266 PAP patients undergoing radiofrequency catheter ablation (RFCA), 122 patients with pauses (>2 s) were studied. The mean maximum symptomatic prolonged pause on termination of tachycardias was 2.67 ± 1.4 s (2.0–12.6 s). SND developed in 32 patients. There was no difference between the patients with and without SND in terms of the age and sex. Patients were divided into two groups based on the intracardiac electrophysiology study after the RFCA procedure. Eleven patients (8 men, 3 women; age 30–72 years, mean 48.2 ± 9.3 years) were placed in a normal sinus node function (NSF) group, and 17 patients (12 men, 5 women; age 37–75 years, mean 62.2 ± 7.5 years) were in an SND group. There was no significant difference in gender, left atrial dimension, left ventricular ejection fraction, blood pressure, or the longest pause between the two groups. RFCA was successful in 28 patients. Electrophysiological data show that corrected sinus node recovery time (CSNRT) was 409 ± 152 ms in NSF group patients and 558 ± 178 ms in SND group before the ablation procedure (P < 0.001). After ablation, SNRT was 1312 ± 387 ms, with CSNRT 2 cycle lengths in 12 patients. In the multivariate analysis, prolonged pauses on termination of tachyarrhythmia, frequency of pauses, and mean heart rate after ablation were independent predictors of SND. Conclusions: (1) Catheter ablation of atrial fibrillation (AF) is effective in treating paroxysmal AF-related TBS; (2) in some patients, there is progressive improvement of sinus node function after elimination of AF, an indication that these sinus pauses may be a manifestation of tachycardia-mediated remodeling of the sinus node, and that permanent pacemaker implantation is unnecessary; (3) among the extrinsic and intrinsic causes of SND, intrinsic causes are seldom reversible and some causes of extrinsic SND may be reversible; and (4) prolonged pauses on termination of PAF, frequency of pauses (>2.0 s), and mean heart rate after ablation were independent predictive factors of SND.

The study included 45 patients with coronary heart disease (CHD) and chronic heart failure (CHF) of functional class I-IV. Increased cardiac troponin T(cTnT) level could be used in verification and assessment of CHF decompensation severity. In CHF, increase in cTnT level was influenced by CHF decompensation, left ventricular systolic dysfunction and remodeling. At the same time, essential arterial hypertension, post-infarctial cardiosclerosis, permanent atrial fibrillation, left ventricular diastolic dysfunction, left atrium pathologic remodeling did not significantly influence cTnT concentration in patients with CHD and CHF.

INTRODUÇÃO: O acesso cirúrgico por esternotomia mediana e atriotomia subseptal clássica pode, em certos casos, resultar em má exposição da valva mitral. Incisões atriais alternativas otimizam a exposição da valva mitral mas podem interferir na atividade elétrica atrial pós-operatória. OBJETIVO: Padronizar método para investigar a atividade elétrica atrial para emprego em estudos comparativos de diferentes atriotomias em cardiopatas sumetidos à cirurgia cardíaca. MÉTODOS: Análise com eletrocardiograma convencional e de 24 h (sistema Holter), pré e pós-operatória, e cardioestimulação epicárdica pós-operatória pelo método de Narula, em 10 pacientes submetidos à correção de valvopatias mitrais. RESULTADOS: No pré-op., os pacientes em ritmo sinusal apresentaram ectopias supraventriculares, com episódios de taquicardia supraventricular em 57% dos casos, "flutter" atrial em 10% e ritmo juncional em 10%. Todos apresentaram ectopias ventriculares, de baixa incidência em 70% dos casos, e taquicardia ventricular não sustentada foi detectada em 30% dos pacientes. No pós-operatório, houve 40% de novas arritmias supraventriculares (fibrilação atrial, ritmo juncional, ritmo atrial baixo e taquicardia supraventricular paroxística), mas não ocorreram arritmias ventriculares. No pós-op. a função do nó sinusal não se alterou, ocorreu redução significativa das ectopias supraventriculares, com reversão de FA para ritmo sinusal em 1 paciente, mas não houve redução significativa das ectopias ventriculares. O tempo de condução inter-atrial correlacionou-se com o tamanho do átrio esquerdo. CONCLUSÃO: A metodologia mostrou-se adequada e segura, e poderá ser empregada na comparação de diferentes incisões atriais para exposição valvar mitral.INTRODUCTION: The selection of the surgical approach to the mitral valve is a critical factor in obtaining good exposure and minimizing lesions of the surrounding structures. The classical right lateral subseptal access may sometimes provide difficult exposure, so that alternative approaches are used whose effects on atrial electrical activity are contradictory. OBJECTIVE:To standardize an investigative method to evaluate heart electrical activity post-op. METHODS: Ten consecutive adult patients with mitral valve disease were operated on. Surface electrocardiogram and continuous electrocardiographic monitoring (Holter system) pre and post-op., and epicardical cardioestimulation post-op. were used to study cardiac electric activity. RESULTS: There was no mortality. All patients with sinus rhythm presented supraventricular ectopia, with episodes of supraventricular tachycardia in 57%, atrial flutter in 10%, and junctional rhythm in 10%. All patients presented ventricular ectopia, with a low incidence in 70% of them and with unsustained ventricular tachycardia in 30%. During the postoperative period there was a 40% rate of new supraventricular arrhythmias (atrial fibrillation, junctional rhythm, low atrial rhythm, and paroxistic supraventricular tachycardia), with no ventricular arrhythmias. Post-op. sinus node function was preserved. There was a significant reduction of supraventricular ectopia, with reversal of atrial fibrillation to sinus rhythm in one patient. Although there was a significant reduction in left atrium size post-op, P wave duration, as well as ventricular ectopia rate remained unchanged. Interatrial conduction time correlated with left atrium size measured pre and post-op. CONCLUSION: The methods proved useful to evaluate atrial electric activity in patients operated upon by the classic subseptal access, thus permitting future comparisons with other surgical approaches to the mitral valve.

Aim: Evaluation of sinus and atrioventricular nodes function as a potential factor responsible for prolonged bradycardia, asystole, or both in patients with cardioinhibitory and non-cardioinhibitory vasovagal syncope (VVS). The study included 258 patients (mean age = 47.7 ± 17.2 years; range 18–62; 147 females) with a history of VVS. They were divided among four groups, according to results of head-up tilt test (HUTT). Methods: All patients underwent standard HUTT, carotid sinus massage (CSM), and rapid transesophageal atrial pacing for evaluation of total sinus node recovery time (SNRT), and corrected sinus node recovery time (CNRT), resting and intrinsic heart rate (IHR), and Wenckebach point (WP). Values of SNRT > 1,500 ms, CNRT > 525 ms, WP < 130 bpm, and CSM-induced pause >3 seconds were considered abnormal. Results: SNRT, CNRT, and WP before and after pharmacological blockade, resting heart rate, and IHR did not differ significantly among the study groups. The prevalence of mild sinus node dysfunction (SND), decreased value of WP, and cardioinhibitory carotid sinus hypersensitivity was similar among all study groups. Conclusions: The prevalence of mild SND, abnormal atrioventricular conduction, and carotid sinus hypersensitivity (CSH) was similar among patients with VVS regardless of the type of vasovagal reaction. SND and CSH do not seem to play an important role in the pathogenesis of cardioinhibitory vasovagal reaction. [ABSTRACT FROM AUTHOR]

Effects of enalapril on canine sinus node (SN) dysfunction induced by long-term rapid atrial pacing were investigated. Methods and Results: Seventeen beagles were pretreated with either placebo (group I, n = 9) or enalapril 1 mg/kg/day (group II, n = 8) and paced at 500/min from the right atrial appendage for 4 weeks. Every week, corrected sinus node recovery time (CSNRT) and sinus cycle length (SCL) were measured. Quantitative analysis of interstitial fibrosis (IF) and adipose tissue (AT) in the SN was performed with Masson's trichrome stain, and apoptosis of the sinus nodal cells were detected with terminal deoxynucleotidyl transferase nick end-labeling. In group I, rapid atrial pacing prolonged both CSNRT and SCL. After 4 weeks of pacing, CSNRT and SCL were significantly shorter in group II (CSNRT, 410 ± 37 msec; SCL, 426 ± 34 msec) than in group I (CSNRT, 717 ± 52 msec, P < 0.005; SCL, 568 ± 73 msec, P < 0.05). Both IF and AT of the SN were greater in group I (IF, 9.7 ± 1.9%; AT, 32.6 ± 5.9%) than in seven sham dogs (IF, 2.4 ± 0.9%, P < 0.05; AT, 4.0 ± 1.7%, P < 0.05) and in group II dogs (IF, 4.0 ± 2.0%, P < 0.05; AT, 4.0 ± 1.7%, P < 0.05). End-labeling assay was positive in three of nine dogs in group I, but negative in group II and sham dogs. Conclusions: Rapid atrial pacing impaired SN function through IF and AT of the SN. Enalapril prevented these pacing-induced degenerative changes and improved SN function. [ABSTRACT FROM AUTHOR]

Background: Maze surgery is a final solution for intractable atrial fibrillation (AF), but an adverse effect on postoperative sinus node function has been reported. Whether this also applies to other types of cardiac surgery is unclear. Methods: We assessed postoperative rhythm by means of repeated exercise tolerance testing, ambulatory electrocardiography, and non-invasive testing of autonomic function between 1 and 12 months after four types of cardiac surgery. Fourteen patients without structural cardiac disease and medically refractory AF underwent the maze III procedure, 11 patients with mitral valve disease and preoperative AF underwent valvar surgery combined with a (simplified) maze III procedure, and 8 patients with mitral valve disease in sinus rhythm (SR) underwent isolated valvar surgery. The control group consisted of eight patients with sinus rhythm who underwent coronary artery bypass surgery (CABG). Results: One month after surgery, the chronotropic response to exercise was depressed, mean heart rate was high, and heart rate variability (HRV) was low, especially after maze III, combined surgery, and isolated valvar surgery. Twelve months after surgery, moderate improvements were observed. After CABG, considerably fewer abnormalities were observed, and HRV parameters recovered to a large extent. Non-invasive testing of autonomic function indicated disturbed vagal modulation of heart rate in all three groups with atrial incision. Conclusion: Thus, attenuation of HRV and vagal modulation of sinus node function are not confined to maze surgery but also apply to isolated mitral valve surgery. Atrial incision therefore appears to be crucial and presumably produces autonomic nervous damage followed by partial reinnervation. Nevertheless, cardiac surgery in general seems initially to impair sinus node function with partial recovery in the consecutive 12 months. [Copyright &y& Elsevier]

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Copyright of Herzschrittmachertherapie und Elektrophysiologie is the property of Springer Nature and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Objective: This study was designed to evaluate the safety and effectiveness of the combined superior-transseptal approach for mitral valve surgery. Methods: We compared the preoperative status, operative factors, and postoperative outcomes among patients having mitral valve operations with three atrial incisions. The incisions were transseptal (n = 40), combined superior-transseptal (n = 33), and left atrial (n = 22). Results: The cardiopulmonary bypass time and cross-clamp time were significantly higher in the superior-transseptal group compared with the transseptal group. No significant difference in blood loss was found among the three groups. The incidence of sinus node dysfunction in the early postoperative period was more common in the superior-transseptal group. The maintenance of sinus rhythm at the mid-term follow-up in patients with preoperative sinus rhythm was not significantly different among the three groups. On the other hand, a few patients in the superior-transseptal and transseptal groups with the preoperative sinus rhythm developed sick sinus syndrome requiring permanent pacemaker implantation. Conclusions: The use of the combined superior-transseptal approach was safe and effective, and was not associated with a higher incidence of rhythm disturbance. Because this approach provided an optimal exposure of the mitral valve and subvalvular apparatus, it has been positively adopted for use in patients undergoing complex and difficult mitral valve operation. To use this approach for patients undergoing mitral valve surgery through this approach, however, further follow-up study of the sinus node function is necessary. [ABSTRACT FROM AUTHOR]

Implantation of single lead VDD pacemakers is an established therapeutic option in patients with AV block and normal sinus node function. However, related to occurrence of sinus node disease and atrial undersensing, there is concern whether VDD devices are appropriate in physically active young patients. Two hundred thirty-two consecutive patients with isolated A V block and VDD pacemakers were investigated. This population was subdivided into quartiles of 58 patients according to age at time of inclusion: 26.2-59.4 years (group A), 59.5-70.1 years (group B), 70.2-81.0 years (group C], and 81.1-92.5 years (group D). Follow-up visits included pacemaker telemetry, Holter monitoring, and exercise testing. Patients were visited at 2 and 12 weeks after implantation thereafter followed by 6-month intervals. Mean follow-up period was 35 ± 14 months. Three months after implantation, atrial sensing threshold was significantly higher in young patients: 1.18 ± 0.58 mV (group A] versus 0.79 ± 0.35 mV (group B), 0.68 ± 0.33 mV (group C), and 0.60 ± 0.25 mV (group D), P < 0.001 for comparison of group A to all other groups. Atrial undersensing was observed less frequently in young patients: 6.9% (group A) versus 17.2% (group B), 24.1% (group C), and 27.6% (group D), P = 0.025 for intergroup comparisons. Sinus node dysfunction did not occur in group A. Atrial arrhythmias and loss of AV synchronized pacing mode occurred rarely in young patients: 0.6% (0.4%) per year in group A versus 1.3% (1.3%) in group B, 3.9% (3.4%) in group C, and 5.7% (7.4%) per year in group D,P < 0.01 for intergroup comparisons. Our data show good atrial sensing performance, low incidence of sinus node dysfunction, and few atrial arrhythmias in young patients with VDD pacing for AV block. Thus, single lead VDD pacing can be recommended particularly for young patients with AV block. [ABSTRACT FROM AUTHOR]

The purpose of this study was to find out whether transesophageal pacing could be utilized for assessment of sinus node/unction in patients with sick sinus syndrome (SSS). In 17 patients with SSS (study group) we compared the results of sinus node tests obtained both in the basal state and after pharmacological autonomic blockade by endocavitary stimulation and, 24 hours later, by transesophageal pacing. In another group of 17 patients with SSS (control group), we compared the results obtained by two endocavitary studies. In "study group", sinus cycle length (SCL) and corrected sinus node recovery time (CSRT) did not show significant differences between the two studies both in the basal state and after autonomic blockade, whereas sinoatrial conduction time (SACT) was more prolonged during esophageal pacing (P < 0.01). In "control group", sinus node measures did not show significant differences between the two studies. In the "study group," the following coefficients of correlation were obtained in the basal state: SCL, r = 0.65, CSRT, r - 0.57, SACT, r = 0.52 and after autonomic blockade: SCI, r = 0.95, CSRT, r = 0.62 and SACT, r = 0.53. In the basal state, the correlation for SCL and CSRT between the two studies was lower in the "study group" than in the "control group" (P < 0.05), whereas after autonomic blockade the correlation for sinus node measures did not show significant differences between the two groups of patients. These data suggest that transesophageal study influences the autonomic tone regulating the sinus node; however, it is not responsible for important variations in sinus node measures. Thus, this noninvasive method appears useful for assessment of sinus node function in patients with SSS, considering, however, that SACT is more prolonged during pacing from the esophagus. [ABSTRACT FROM AUTHOR]

Many recent studies have shown transesophageal programmed atrial pacing (TP) as a very practical, safe and convenient way for assessment of sinus node function and AV conduction. On the other hand, permanent atrial pacing is known to be superior to ventricular pacing due to arrhythmogenic and hemodynamic reasons. This is the reason why we decided to use TP as a method of choosing patients with sick sinus syndrome (SSS) for permanent atrial pacing. Sixty-three patients with symptomatic (58) and asymptomatic (5) SSS in a variety of clinical situations were examined in this way. The following electrophysioIogical features were examined: sinus cycle length, sinus node recovery time as well as corrected time, secondary pause after overdrive stimulation, sinoatrial conduction time, Wenckebach point, induction of supraventricular arrhythmias by S1, S2, S3 programmed stimulation and burst pacing. Patients with abnormal parameters were examined once more after intravenous atropine 0.2 mg/kg to evaluate parasympathetic component. Standard 12-lead ECG was performed in all, and Holter monitoring in most of patients. Twenty-six patients were candidates for permanent AAI pacing. Failures occurred in eight patients usually due to low P wave amplitude and electrode instability. Eighteen patients received AAI pacing systems: eight with brady-tachycardia syndrome, nine with bradyarrhythmia and one with sinoatrial block. In the follow-up of 5-28 months in one patient occurred high degree AV block (II°) during digitalis therapy. Reduction of doses made this block disappear. Examination of Wenckebach point and possibility of inducation of supraventricular tachyarrhythmias in cases of atrial overexcitability are particularly useful in selecting patients for AAI pacing. [ABSTRACT FROM AUTHOR]

In a group of 50 patients we investigated the daily reproducibility of the resting heart rote (RHR), the maximal corrected sinus node recovery time (CSNRTM), the pacing rate at which the CSNRTM occurred (OP), and the sinoatrial conduction time (SACT) during basal state. The study population was divided into two groups according to the presence or absence [as evidenced during the initial electrophysiologic study) of sinus node disease: group I included 35 patients with normal sinus node function, and group II included 15 patients with sick sinus syndrome. The electrophysiologic study was repeated approximately at the same hour and under similar conditions after an interval of at least two days (mean: 3.2 days for group I and 4.7 days for group II). The results showed good reproducibility with the exception of RHR in group I which slightly but significantly decreased in the second electrophysiologic study. The daily variations of the sinus node parameters appeared to be of similar levels in the two groups except for the CSNRTM; this parameter showed wide variations in single values in both groups, more marked in group II than in group I. Furthermore, if the CSNRTM and/or SACT were normal, it was likely that they would remain normal whatever the electrophysiologic status of the patient. Inversely, the change of status from abnormal to normal CSNRTM or SACT was not uncommon in patients with electrophysiologic signs of sinus node disease. [ABSTRACT FROM AUTHOR]

To determine the evolution with age, of extrinsic and intrinsic sinus node electrophysiological parameters and to assess the role of each component of the autonomic nervous system relative to age in patients with and without sick sinus syndrome, electrophysiological studies of sinus node function were performed in 223 patients subdivided into four groups according to the results of their electrophysiological testings: group I included patients with normal extrinsic and intrinsic sinus node function, group II patients with exclusive extrinsic sinus dysfunction, group III patients with exclusive intrinsic sinus dysfunction and group IV patients with extrinsic and intrinsic sinus node dysfunction. The electrophysiological study was performed twice: at basal state and after autonomic blockade. Whatever the sinus node function (normal or abnormal) the extrinsic sinus node electrophysiological variables did not correlate with age; inversely all the electrophysiological measurements of the intrinsic sinus node (normal or abnormal) lengthened progressively with age, suggesting an ageing phenomenon of the intrinsic sinus node throughout life. Moreover, the study of the percentage of chronotropy of the sinus node electrophysiological variables shows a predominance of vagal tone in young subjects, whereas sympathetic activity is most prominent in elderly patients with and without sick sinus syndrome. The sinus node (normal or pathological) represents an equilibrated system: the age-related modification of the autonomic nervous system counterbalances the senescence of the intrinsic sinus node in such a way that the basal electrophysiological characteristics remain stable throughout life. [ABSTRACT FROM PUBLISHER]

We have performed an electrophysiologic study (EPS) in 18 subjects (mean age 21 ± 17 years) with normal sinus node function (group A) and in 15 patients (mean age 43 ± 26 years) with sinus node dysfunction (group B). Three extrastimulus methods (both Strauss and Kirkorian methods and our modification of the extrastimulus method) were carried out in 31 patients of both groups and sinoatrial conduction times (SACT, SACT, SACT) could be estimated in 27 of them. SACT by the Narula method (SACT) was assessed in 25 patients of both groups. Sinus node electrograms (SNEs) were attempted in 22 patients and were obtained in 17 of them. Among the indirect methods, by comparison with SACTSTR in group A the best correlation was for SACT (r = 0.81) and the weakest for SACT (r = 0.67); there was no significant difference between SACTs estimated by Strauss and other methods. In group B the weakest correlation was also for SACT (r = 0.68), whereas the correlations for both SACT and SACT were similar (r = 0.72 and r = 0.74, respectively); in this group SACT was significantly underestimated only by the Kirkorian method (P<0.01; sensitivity of 45%). By our method sensitivity was 82%, similar to both the Strauss and Narula methods (92 and92%, respectively). By comparison of indirect methods with the direct measurement of SACT we have found similar good correlations for the Strauss, our own, and the Narula methods in group A (r = 0.81, r = 0.75, r = 0.79, respectively) and in group B (r=0.81, r = 0.86, and r = 0 72, respectively); here too the weakest correlation was, in both groups, for the Kirkorian method (r = 0.67, and r = 0.68, respectively). The SACT in group B was the more significantly underestimated (P < 0.001). Significant underestimation of SACT occurred also by our method and the Strauss method (P <0.01, and P <0.001, respectively), whereas the Narula method did not significantly underestimate the directly measuredSACT. From the SNEs after atrial pacing we have shown the limitation of the Kirkorian method and observed the conspicuous beat-to-beat variability of SACT as the possible explanation of chaotic pattern of return cycles by the extrastimulus methods in some patients of group B. We conclude that: (i) SACTs were not significantly distinguished in controls by all indirect methods used, whereas in patients with sinus node dysfunction the Kirkorian method was shown to be incorrect; the chaotic pattern of atrial return cycles was the main limitation of all the extrastimulus methods; (ii) the results of our modified extrastimulus method correlated well with both the Strauss and direct methods; (iii) the direct recordings of SNE have allowed the elucidation of some peculiarities related to the difficulties of indirect estimation of SACT. [ABSTRACT FROM PUBLISHER]

The effect of iv digoxin on normal sinus node function was studied after pharmacologic autonomic blockade (AB) in ten patients. Sinus cycle length (SCL), sinus node recovery time (SNRT) and sinoatrial conduction time (SACT) were determined before and after AB with propranolol (0.2 mg/kg body weight) and atropine sulfate (0.04 mg/kg body weight) iv, and 15 min, 30 min, and 45 min after 1 mg iv digoxin. AB resulted in a significant decrease (P<0.01) in SCL (916±158 to 716±120 ms), in SNRT (1,229±221 to 871±190 ms), and in SACT (79±34 to 44±10 ms). Fifteen minutes after iv digoxin there was no significant change observed in SCL (716±120 to 708±92 ms), in SNRT (871±190 to 864±148 ms), or in SACT (44±10 to 46±15 ms). Similar results were obtained 30 min after digoxin administration. It is concluded that a single therapeutic dose of digoxin has no direct effect on electrophysiologic parameters of normal intrinsic sinus node function. [ABSTRACT FROM AUTHOR]

The effects of quinidine on sinus nodal and A–V nodal function were assessed in 20 patients (age: 60±7 years) with sinus bradycardia and a prolonged A–H interval. Electrophysiological studies were performed twice in each patient. In the first study, the measurements of sinus and A–V node function were evaluated both in the basal state and after autonomic blockade (propranolol 0.2 mg kg-1 and atropine 0.04 mg kg-1). Oral quinidine was administered for 3–4 days (1200 mg day-1) and the study was then repeated using the same methods. Comparison of data obtained in the two studies in the basal state allowed us to evaluate the overall effect of quinidine. Comparing the results obtained following autonomic blockade, the direct action of the drug could be assessed. In the basal state quinidine did not significantly change the function of either node. In contrast, after autonomic blockade, significant changes were noted after quinidine. In 3 patients with sinus rate <50 beats min-1 and an abnormal intrinsic heart rate, quinidine induced marked depression of sinus automaticity. These data suggest that: (1) in patients with sinus bradycardia and prolongation of the A–H interval, oral quinidine has a direct depressant effect on sinus and A–V nodal function, but this effect is counteracted by autonomically mediated actions; (2) in patients with moderate or severe bradycardia and an abnormal intrinsic heart rate, the drug can induce marked depression of sinus automaticity. [ABSTRACT FROM PUBLISHER]

The purpose of this study was to evaluate the effects of oral quinidine on the normal sinus node (SN) and A- V node and to determine if the drug exerts in man the same effects observed in cardiac tissue preparations (i.e. both direct and vagolytic action). Electrophysiological studies were performed twice in each of 16 patients (mean age: 57.7± 12 years) with normal resting and intrinsic heart rates and normal A-H intervals. In the first study, the parameters of SN and A-V node were evaluated both in the basal state and following pharmacological autonomic blockade (AB), (propranolol 0.2 mg kg ∼1 and atropine 0.04 mg kg∼1), Oral quinidine was administered for 3–4 days (1200 mg day∼1) and the electrophysiological study was then repeated using the same methods. From the comparison of data obtained in the two studies in the basal state the overall effect of quinidine was evaluated, and by comparing those obtained following ABthe direct action of the drug was assessed. The overall effect of quinidine on SN and A-V nodal functions was very slight since sinus cycle length, corrected SN recovery time, sino-atrial conduction time, A-H interval, Aj-Hj interval at a cycle length of 600 ms and Wenckebach periods did not change significantly after the drug. On the contrary, following AB these measures increased significantly (P≤0.01). These results provide evidence of dual effects of oral quinidine in man: a direct depressant action and an autonomically mediated opposing action, very probably vagolytic. The overall effect of the drug is very slight. [ABSTRACT FROM PUBLISHER]

We hypothesized that the outpatient assessment of SA and AV nodal (SAN, AVN) function could be a useful tool to determine the effectiveness of drugs and other treatments. We sought to examine the reproducibility, safety and ease of acquiring serial measurements of these parameters. Ten patients with permanent pacemakers underwent low current chest wall stimulation while their device was programmed to unipolar atrial triggered mode. Measurements at multiple conditioning drive train frequencies were obtained for: sinus nodal recovery time (SNRT); corrected sinus nodal recovery time (CSNRT); SA conduction time (SACT); AVN block cycle length (AVNBCL): and AVN effective refractory period (AVNERP). AVN function curves were also constructed. All studies were repeated after 2 weeks. Measures of sinus nodal and AVN function did not show significant differences between the two studies. The following coefficients of correlation were obtained: SNHT800. r = 0.79; CSNRT800, r - 0.71; SNRT600, r = 0.71; CSNRT600. r = 0.44; SACT, r = 0.75; AVNBCL, r = 0.98; AVNERP800, r = 0.55; and AVNERP600. r = 0.99. AVN function curves did not significantly differ between week 1 versus week 2 at conditioning drive trains of either 800 ms or 600 ms. These data suggest that serial noninvasive electrophysiological measures of AVN and SAN function are reproducible over 2 weeks. Using data in this study, estimates of the sample size necessary for the evaluation of the effects of investigational drugs on the SAN and AVN in future studies are possible. [ABSTRACT FROM AUTHOR]

The chronotropic response during graded, symptom limited exercise was investigated in 32 cardiac transplant recipients a mean of 49 ± 18 days after transplantation. Ail patients had systematic evaluation of postoperative donor sinus node (SN) function and the cardioacceleratory response was compared according to the SN /unction. Twenty-one patients had normal postoperative SN studies (corrected SN recovery time < 520 msec, group I) while the SN function was impaired postoperatively in the remainder (n = 11, group H, corrected SN recovery time 4,149 ± 6,283 msec in 5 patients, junctionai escape rhythm in 6 patients). All patients had regained sinus rhythm at time of the exercise test. Patients in group II had lower basal sinus rates at the beginning of exercise (91.5 ± 11 vs 101.4 ± 7 beats/min, P < 0.02). This lower chronotropy was maintained over every incremental step [Frate between groups = 30, P = 0.0001, Frate vs workload = 15,P = 0.0001 by two-way ANOVA] and resulted in a significantly lower heart rate at individual peak exercise (108.3 ± 20 vs 124.2 ± 13 beats/min, P < 0.02). A total of 14/16 patients in group I but only 2/16 patients in group 11 accomplished a peak heart rate > 120 beats/min (P = 0.009). The workload achieved did not differ between the groups {107 ± 29 vs 102 ± 32 watts, P > 0.5). These data show a lower SN chronotropy during rest and at peak exercise in cardiac transplant recipients with postoperative SN deficiency and apparent normalization of SN function. [ABSTRACT FROM AUTHOR]

Fifteen cardiac transplant recipients requiring permanent pacing (AAI, n = 9; VVI, n = 6; rate responsive devices, n = 11) for postoperative sinus node (SN) insufficiency underwent evaluation of long-term SN function 240 to 1,461 days after transplantation. The intrinsic rhythm at the time of discharge was sinus in 7 patients; junctional escape in 6 patients; and pacemaker dependent in 2 patients. At follow-up, 5 patients had regained regular sinus rhythm, accounting for a total of 11 patients in sinus rhythm while 4 patients were in junctional bradycardia. The SN recovery time as determined by the permanent pacemaker was normal (< 1,500 msec) in only 1/8 patients in whom it was determined, although 4 of these 8 patients were temporarily overriding the pacemaker during ambulatory monitoring. Patients with pathological SN recovery times included 3 patients with late return of sinus rhythm and 4 patients who had recovered normal sinus rhythm be/ore their discharge from the hospital. Three patients developed late symptoms despite apparent early normalization and underwent delayed pacemaker implantations on postoperative days 35, 52, and 225, respectively. We conclude that, in patients requiring pacemaker implantation after cardiac transplantation, normalization of SN function cannot be inferred from just return of sinus rhythm, regardless of whether it occurs early or late. These findings may have implications when a pacemaker exchange or explantation is being considered. [ABSTRACT FROM AUTHOR]

Objectives: This study aimed to clarify the incidence of sinoatrial nodal artery (SANa) injury in thoracoscopic epicardial surgical ablation for atrial fibrillation (AF) and its impact on postoperative outcomes, which have not been previously elucidated., Methods: We enrolled 103 consecutively patients with AF who underwent thoracoscopic epicardial ablation at our institution. In these patients, we evaluated the postoperative incidence of SANa injury by using enhanced cardiac computed tomography. For patients with confirmed SANa injury, 3-day continuous electrocardiographic monitoring and exercise stress tests were performed to assess the sinus rhythm maintenance and sinus node function., Results: Thirteen patients (12.6%) had a confirmed SANa injury (left anterior type in 6 patients, left posterior type in 2 patients and double-branch type in 5 patients). After a median follow-up of 24 months, the patients with SANa injury were not found to be associated with lower sinus rhythm maintenance (hazard ratio 1.09, 95% confidential interval 0.36-3.31) as compared with those without SANa injury after adjustment for patient characteristics. Sinus node function was evaluated in 7 patients with SANa injury who remained in sinus rhythm after the procedure, and no sinus node dysfunction was confirmed in the 3-day electrocardiographic monitoring and exercise stress tests at a median follow-up of 12 months., Conclusions: The prevalence of SANa injury in the patients who underwent thoracoscopic epicardial ablation for AF was relatively low, and the incidence of SANa injury was not associated with postoperative restoration of sinus rhythm and sinoatrial node dysfunction. More studies are required to better understand SANa injury., (© The Author(s) 2020. Published by Oxford University Press on behalf of the European Association for Cardio-Thoracic Surgery. All rights reserved.)