Interatrial Conduction Delay Research Articles

Antiarrhythmic properties of atrial pacing.

Bradycardia, atrial stretch and dilatation, autonomic nervous system disorders, and the presence of triggers such as atrial premature contractions, are factors which predispose a person to paroxysmal AF. Atrial pacing not only eliminates bradycardia but also prevents atrial premature contractions and dispersion of refractoriness, which are a substrate for atrial fibrillation. As the prolonged duration of atrial activation during pacing, especially from locations changing the physiological pattern of this activation (right atrium lateral wall, right atrium appendage), negatively influences both a mechanical and an electrical function of the atria, the atrial pacing site affects an atrial arrhythmogenesis. A conventional atrial lead location in the right atrium appendage causes non-physiological activation propagation, resulting in a prolongation of the activation time of both atria. This location is optimal according to a passive fixation of the atrial lead but the available contemporary active fixation leads could potentially be located in any area of the atrium. There is growing evidence of the benefit of pacing, imitating the physiological propagation of impulses within the atria. It seems that the Bachmann's bundle pacing is the best pacing site within the atria, not only positively influencing the atrial mechanical function but also best fulfilling the so-called atrial resynchronization function, in particular in patients with interatrial conduction delay. It can be effectively achieved using only one atrial electrode, and the slight shortening of atrioventricular conduction provides an additional benefit of this atrial pacing site.

Hemodynamic Assessment of Dyspnea in Post-Left Atrial Radiofrequency Ablation and Maze Procedure

The surgical Maze procedure and radiofrequency ablation to treat atrial fibrillation are associated with complications that may subsequently lead to dyspnea including left atrial noncompliance, interatrial conduction delays, and pulmonary vein stenosis [(1,2)][1]. A 73-year-old woman presented with

Electrophysiological abnormalities in patients with paroxysmal atrial fibrillation in the absence of overt structural heart disease

PurposeThe aim of the present study was to define the atrial electrical substrate in patients with paroxysmal atrial fibrillation (AF) occurring in the absence of overt structural heart disease and to assess if electrophysiological parameters could predict AF recurrence after radiofrequency ablation in this population. Methods and results45 consecutive patients (39 male, age 59 ± 10 years) with paroxysmal AF and without overt structural heart disease, referred for radiofrequency catheter ablation, were prospectively enrolled. A cohort of 12 age-matched patients without a history of AF, served as a control group. Atrial electrical substrate was assessed by P-wave signal-averaging, intracardiac conduction delays and refractory periods. Total P wave duration during signal-averaging was longer in patients with paroxysmal AF than in controls (140 ± 19 ms vs 123 ± 13 ms, p = 0.004). Patients with paroxysmal AF showed an increase in right intra-atrial (40.2 ± 11.3 ms vs 31.7 ± 11.8 ms, p = 0.02) and inter-atrial conduction delays (87.93 ± 22.0 ms vs 65.3 ± 15.6 ms, p = 0.001) in sinus rhythm. Refractory periods in the right atrium were longer in patients with paroxysmal AF (265 ± 44 ms vs 222 ± 32 ms, p = 0.002). After ablation, 22 patients had AF recurrence but showed no differences in electrophysiological parameters compared to patients without recurrence. ConclusionElectrophysiological abnormalities are present in patients with paroxysmal AF without overt structural heart disease. Neither signal-averaged P-wave duration nor intracardiac atrial electrophysiology could predict arrhythmia recurrence after pulmonary vein isolation.

Evaluation of P-Wave Dispersion, Diastolic Function, and Atrial Electromechanical Conduction in Pediatric Patients with Subclinical Hypothyroidism.

This study aimed to evaluate ventricular diastolic dysfunction, inter- and intraatrial conduction delay, and P-wave dispersion in pediatric patients with subclinical hypothyroidism. The study comprised a total of 30 pediatric patients with subclinical hypothyroidism (SH) (mean age 7.8 ± 3.2 years) and 30 healthy children (mean age 8.4 ± 3.6 years) as the control group. A SH diagnosis was made in the event of increased serum thyroid-stimulating hormone (TSH) and decreased serum free triiodothyronine (T3 ) and free thyroxine (T4 ) concentrations. Conventional Doppler imaging (TDI) showed low mitral early diastolic E-wave velocity and E/A ratio (P < 0.001) and significantly higher mitral late diastolic A-wave velocity (P = 0.001) in hypothyroidism patients. Moreover, patients with hypothyroidism had significantly lower left ventricular (LV) septal Em velocity and Em /Am ratios compared with the control group (P < 0.001), whereas Am velocity was higher in hypothyroidism patients (P = 0.018). LV lateral Em velocity and Em /Am ratio were significantly lower in patients with hypothyroidism compared with the control group (P < 0.001). With regard to atrial electromechanical conduction, atrial electromechanical delay (PA) lateral, PA septum, PA tricuspid, and each of interatrial and intraatrial conduction delay were significantly prolonged in hypothyroidism patients as compared with the control group (P < 0.001, P < 0.001, P = 0.023, P = 0.002, and P = 0.003, respectively). P-wave dispersion was significantly different in the pediatric patients with hypothyroidism (P < 0.001). This study demonstrated atrial electromechanical conduction delay, abnormal P-wave dispersion, and ventricle diastolic dysfunction in pediatric patients with hypothyroidism.

Bachmann's Bundle Pacing not Only Improves Interatrial Conduction but Also Reduces the Need for Ventricular Pacing.

Patients treated for sick sinus syndrome may have interatrial conduction disorder leading to atrial fibrillation. This study was aimed to assess the influence of the atrial pacing site on interatrial and atrioventricular conduction as well as the percentage of ventricular pacing in patients with sick sinus syndrome implanted with atrioventricular pacemaker. The study population: 96 patients (58 females, 38 males) aged 74.1 ± 11.8 years were divided in two groups: Group 1 (n = 44) with right atrial appendage pacing and group 2 (n = 52) with Bachmann's area pacing. We assessed the differences in atrioventricular conduction in sinus rhythm and atrial 60 and 90 bpm pacing, P-wave duration and percentage of ventricular pacing. No differences in baseline P-wave duration in sinus rhythm between the groups (102.4 ± 17 ms vs. 104.1 ± 26 ms, p = ns.) were noted. Atrial pacing 60 bpm resulted in longer P-wave in group 1 vs. group 2 (138.3 ± 21 vs. 106.1 ± 15 ms, p < 0.01). The differences between atrioventricular conduction time during sinus rhythm and atrial pacing at 60 and 90 bpm were significantly longer in patients with right atrial appendage vs. Bachmann's pacing (44.1 ± 17 vs. 9.2 ± 7 ms p < 0.01 and 69.2 ± 31 vs. 21.4 ± 12 ms p < 0.05, respectively). The percentage of ventricular pacing was higher in group 1 (21 vs. 4%, p < 0.01). Bachmann's bundle pacing decreases interatrial and atrioventricular conduction delay. Moreover, the frequency-dependent atrioventricular conduction lengthening is much less pronounced during Bachmann's bundle pacing. Right atrial appendage pacing in sick sinus syndrome patients promotes a higher percentage of ventricular pacing.

Atrial conduction time, and left atrial mechanical and electromechanical functions in patients with polycystic ovary syndrome : interatrial conduction delay : cardiovascular topics

SummaryBackgroundPolycystic ovary syndrome (PCOS) is one of the most common endocrine disorders of women during the reproductive period. Cardiovascular risk factors are more frequent in patients with PCOS. We aimed to investigate the P-wave dispersion (Pd), inter- and intra-atrial conduction time and mechanical functions of the left atrium (LA) in patients with PCOS.MethodsForty-eight patients with PCOS and 38 normal healthy women were enrolled in this study. A 12-lead surface electrocardiogram was used to evaluate Pd. Left ventricular (LV) functions were measured using conventional and tissue Doppler imaging (TDI) methods. Inter- and intra-atrial conduction times were measured by TDI. LA volumes were measured echocardiographically with the biplane area–length method from the apical four-chamber view.ResultsHeart rate (82.02 ± 13.15 vs 74.24 ± 11.02 bpm, p = 0.014) and Pd were significantly increased in the PCOS patients [27 ± 5 vs 24 ± 6 ms, p = 0.035]. Transmitral E/A ratio was significantly lower in the PCOS patients than in the controls (1.5 ± 0.3 vs 1.7 ± 0.4 m/s, p = 0.023). Passive emptying volume (12.54 ± 4.39 vs 15.28 ± 3.85 ml/m2, p = 0.004) and passive emptying fraction [54.4 (21–69) vs 59.1% (28–74), p = 0.008] were significantly decreased in PCOS patients. Total emptying volume was significantly decreased (17.9 ± 5.49 vs 20.67 ± 4.29 ml/m2, p = 0.018) in PCOS patients. Interatrial (19 ± 7.4 vs 15 ± 6.4 ms, p = 0.035) and intra-atrial [8.5 (1–19) vs 5 ms (1–20), p = 0.026] electromechanical delays were found to be significantly higher in PCOS patients.ConclusionThis study showed that patients with PCOS had increased inter- and intra-atrial conduction delays, and decreased LA passive emptying volumes and fractions.

Abstract 17452: Inter-atrial Conduction Time Can Predict New-onset Atrial Fibrillation After Radiofrequency Ablation of Isolated, Typical Atrial Flutter

Introduction: Previous studies showed inter-atrial conduction delay (IACT) is an important electrophysiological factor predicting atrial fibrillation (AF) after successful atrial flutter (AFL) ablation. To the best of our knowledge, there has no previous study regarding the prognostic value of IACT as a predictor of new-onset AF after AFL ablation without AF history. Hypothesis: The purpose of this study was to determine the incidence and predictors of new-onset AF after Radiofrequency ablation (RFA) of isolated AFL in a retrospective cohort study. Methods: This study included consecutive patients who underwent successful RFA of isolated, typical AFL from 2004 to 2012. Patients with any history of AF prior to AFL ablation were excluded. IACT was defined as the interval from the onset of P-wave in 12-lead electrocardiogram to atrial intracardiac electrogram at the distal coronary sinus catheter. Results: Eighty patients were included in this study. During a mean follow-up 3.4±2.6 years after successful AFL ablation, 22 patients (27.5%) developed new-onset AF. A Cox regression multivariate analysis demonstrated that IACT was the independent predictor of new-onset AF after AFL ablation (odds ratio: 13.3; 95% confidence interval: 1.36-152.5; p=0.0255). IACT was accurate in predicting new-onset AF (AUC=0.70). The optimal cut-off point of IACT for predicting new-onset AF was ≧120ms, with a sensitivity of 0.476 and a specificity of 0.898. Kaplan-Meier curves showed that new-onset AF after AFL ablation was significantly higher in the patients with IACT ≧120ms compared to the patients with IACT&lt; 120ms (p=0.0016). Conclusions: IACT is an independent risk factor for new-onset AF after AFL ablation without a history of AF.

Evaluating functional capacity, and mortality effects in the presence of atrial electromechanical conduction delay in patients with systolic heart failure.

Objective:Atrial functions are relatively suppressed in heart failure (HF). We aimed to investigate the associations of intra- and inter-atrial electromechanical conduction delay (EMCD) with functional class and mortality over a 12-month follow-up period.Methods:The prospective study included 65 patients with systolic HF and 65 healthy subjects with normal sinus rhythm. Left ventricular (LV) systolic functions and left atrial (LA) dimensions and volumes were evaluated by transthoracic echocardiography. Tissue Doppler imaging (TDI) signals at the lateral border of the mitral annulus (lateral PA’), septal mitral annulus (septal PA’), and tricuspid annulus (tricuspid PA’) were measured. Intra- and inter-atrial EMCD were calculated.Results:Mitral inflow velocities were studied using pulsed-wave Doppler after placing the sample volume at the leaflets’ tips. The peak early (E wave) and late (A wave) velocities were measured. The septal annular E/E’ ratio was relatively higher and lateral, septal, and right ventricular S, E’, and A’ waves were significantly lower in the HF group than in the control group (12.49±6.03 – 7.16±1.75, pE/E’ <0.0001). Intra-atrial EMCD was detected as 117.5 ms and inter-atrial EMCD as 127.5 ms in patients with prolonged atrial EMCD. A significant increase was found in prolonged intra- and inter-atrial EMCD according to functional capacity increase (p=0.012 and p=0.031, respectively). The incidence of mortality was significantly higher in patients with prolonged atrial EMCD (p=0.025), and 5 patients in the HF group died during the study over the 12-month follow-up period.Conclusions:In this study, we found a relationship between prolonged atrial conduction time and increased functional class and mortality in patients with systolic HF. (Anatol J Cardiol 2016; 16: 579-86)

Atrial and ventricular signal averaging electrocardiography in pacemaker and cardiac resynchronization therapy

Abstract Cardiac resynchronization therapy with atrioventricular and interventricular delay optimized biventricular pacing is an established therapy for symptomatic heart failure patients with prolongation of QRS duration, left bundle branch block and reduced left ventricular ejection fraction. The aim of the investigation was to evaluate right atrial, right ventricular and left ventricular electrical signals of implantable electronic cardiac devices with and without signal averaging technique with novel LabVIEW software. Electrical interatrial conduction delay and inter-ventricular conduction delay may be useful parameters to evaluate electrical atrial and ventricular desynchronization in heart failure patients.

The impact of cryoballoon-based catheter ablation on left atrial structural and potential electrical remodeling in patients with paroxysmal atrial fibrillation.

While atrial fibrillation (AF) begets AF via structural, contractile, and electrical remodeling, it was shown that successful radiofrequency ablation of AF has effectively reversed left atrial (LA) remodeling. However, there was little data regarding the efficacy of cryoablation on LA remodeling. Herein, we aimed to assess the impact of cryoablation on LA structural and potential electrical remodeling in paroxysmal AF patients. A total of 41 symptomatic patients with non-valvular paroxysmal AF underwent their first catheter ablation via cryoballoon technique. All patients had transthoracic echocardiography before, 6 and 12 months after cryoablation. LA volume index (LAVI), left intra-, right intra-, and inter-atrial electromechanical conduction delay (AEMD) were calculated in all patients. Postprocedural first 3 months was accepted as blanking period. All 179 pulmonary veins were isolated successfully in 41 patients with no major complication. During median 18 months (12-20 months) follow-up, recurrent atrial arrhythmia was found in nine patients (21.9%). In multivariate Cox regression analysis, only early recurrence was found as the independent predictor of late recurrence. At 12th month visit compared to baseline, there was no change in LAVI (p = 0.647) but significant increase in left intra- and inter-AEMD (p < 0.05). However, in non-recurrent group, both LAVI (30.63 ± 3.6 to 28.42 ± 3.63, p < 0.001), left intra-AEMD (18.75 ± 8.77 to 12.5 ± 4.65, p < 0.001), and inter-AEMD (25.2 ± 13.2 to 18.84 ± 8.52, p < 0.001) were significantly decreased. Our study findings revealed that successful cryoballoon-based AF ablation yields LA structural and potential electrical reverse remodeling. However, LA remodeling process cannot be halted by cryoablation in patients with AF recurrence during follow-up.

Evaluation of left atrial mechanical function and atrial conduction abnormalities in Maras powder (smokeless tobacco) users and smokers.

SummaryObjectiveIn Turkey, a type of smokeless tobacco called Maras powder (MP) is widely used in the south-eastern region. Smokeless tobacco is found in preparations for chewing and for absorption by the nasal and oral mucosae. The purpose of this study was to investigate whether MP damages intra- and inter-atrial conduction delay and left atrial (LA) mechanical function as much as cigarette smoking.MethodA total of 150 chronic MP users (50 males, 32.5 ± 5.4 years), smokers (50 males, 32.1 ± 6.0 years) and controls (50 males, 30.1 ± 5.8 years) were included in the study. LA volumes were measured echocardiographically according to the biplane area–length method. Atrial electromechanical coupling was measured with tissue Doppler imaging and LA mechanical function parameters were calculated.ResultsThe LA passive emptying fraction was significantly decreased and LA active emptying volume (LAAEV) was significantly increased in the MP group (p = 0.012 and p = 0.024, respectively), and the LA active emptying fraction (LAAEF) was significantly increased in the smokers (p = 0.003). There was a positive correlation between the amount of MP used and smoking (pack years) with LAAEV and LAAEF (r = 0.26, p = 0.009 and r = 0.25, p = 0.013, respectively). Lateral atrial electromechanical intervals (PA) were significantly higher in MP users, and the septal mitral PA was statistically higher in the smokers (p = 0.05 and p = 0.04, respectively).ConclusionWe suggest that atrial electromechanical coupling intervals were prolonged and LA mechanical function was impaired in MP users and smokers, but there was no significant difference between the MP users and smokers. These findings may be markers of subclinical cardiac involvement and tendency for atrial fibrillation.

Second-degree interatrial block in hemodialysis patients.

Interatrial conduction delays manifest as a prolonged P-wave duration on surface ECG and the term interatrial block (IAB) has been coined. They are usually fixed, but cases of intermittent IAB have been described, suggesting functional conduction block at the Bachmann bundle region. We report 2 cases of patients on chronic hemodialysis therapy presenting with intermittent IAB.

Long-term follow-up after pacemaker implantation via persistent left superior vena cava

The persistent left superior vena cava (PLSVC) is a relatively common con-genital venous return anomaly. It may have serious clinical implications especially in case of pacemaker/cardioverter-defibrillator implantation, venous catheter insertion, radio-frequency ablation and cardiac surgery. There is also some evidence that PLSVC may be accompanied by arrhythmias. The aim of this report is to present the effectiveness and safety of cardiac pacing via PLSVC, clinical outcome and appearance of arrhythmias in a long-term follow-up. Four cases of pacing electrodes implanted via PLSVC in patients without any other cardiac congenital heart anomalies were observed for at least 6 years. There was 1 patient with AAI, 2 patients with VVI, and 1 with DDD pacemaker. Atrial electrodes were implanted on the free right atrial wall, 2 ventricular electrodes were implanted in right ventricular outflow tract, 1 in postero-lateral cardiac vein. During the mean 110 months of observation, pacing was efficient. One patient underwent an upgrade from AAI to biatrial pac-ing due to progressive interatrial conduction delay during the follow-up. No other intervention or pacemaker related events were noticed except for battery replacement. The presence of PSVC may complicate implantation, but it does not influence the long-term follow-up of pacing parameters.

Extreme interatrial conduction delay and regularization of atrial arrhythmias in a subgroup of patients with hypertrophic cardiomyopathy

BackgroundHypertrophic cardiomyopathy (HCM) patients may develop interatrial activation delay, indicated by a complete separation of the right and left atrial activation on the ECG. This study aimed to determine the prevalence of interatrial activation delay and the relation to atrial tachycardia (AT) cycle length (CL) in HCM patients. Methods159 HCM patients were included (mean age 52 ± 14 y). In group I (n = 15, 9%) patients had atrial arrhythmias and progressive ATCL. In group II (n = 22, 14%) patients had a stable ATCL. In group III (n = 122, 77%) HCM patients without AT were included. P wave morphology and change in P wave duration (ΔP and Pmax) and changes in ATCL (ΔATCL) were analyzed. Mean follow-up was 8.7 ± 4.7 years. ResultsIn group I 33% (n = 5) had separated P waves. In group II no P wave separation was identified (OR 1.50 [1.05–2.15], p = 0.007). In group I patients were older compared to group III (62.6 ± 15.1 vs. 50.2 ± 14.0 y, p = 0.002) and had longer follow-up (13.4 ± 2.2 vs. 7.8 ± 4.6 y, p < 0.001). In group III Pmax and ΔP were significantly lower (105.1 ± 22.0 ms and 8.9 ± 13.2 ms, both p < 0.0001). Group I patients had an increased LA size compared to group II (61.1 ± 11.6 vs. 53.7 ± 7.5 mm, p = 0.028) and higher E/A and E/E prime ratios (p = 0.007; p = 0.037, respectively). In group I 93.3% of the identified mutations were typical Dutch founder mutations of the MYBPC3 gene. ConclusionIn HCM patients a unique combination of separated P waves and regularization of ATs is associated with larger atria, higher LA pressures and myosin binding protein mutations.

Sympathetic stimulation affects atrial vulnerability in paroxysmal supraventricular tachycardia patients with atrial fibrillation

were diagnosed as WPW syndrome, AVNRT or AVRT and treated with RFCA. All antiarrhythmic medications that had an effect on cardiac electrophysiological properties were withdrawn for N 5h alf-lives prior to operation. Exclusion criteria included diabetes mellitus, BMI ≥25 kg/m, thyroid dysfunction, toxic abuse (alcohol, caffeine and nicotine), hypertension, valvular heart disease and atrial tachycardia. Atrial conduction delay and dispersion of atrial refractoriness (dERP), the primary indexes of atrial vulnerability, were measured before and after the ablation respectively as described previously [6,7] .B rie fly, interatrial conduction delay was the interval from beginning of the late diastolic wave of the lateral mitral annulus to the beginning of the late diastolic wave of the tricuspid annulus, intra-atrial conduction delay was the interval from the beginning of the late diastolic wave of the septal mitral annulus to the beginning of the late diastolic wave of the tricuspid annulus. The dERP was defined as the longest atrial effective refractory period (AERP) minus the shortest AERP that was determined at each of the four atrial recording sites, HRA, LRA, distal and proximal CS

Atrial Conduction Delay Predicts Atrial Fibrillation in Paroxysmal Supraventricular Tachycardia Patients after Radiofrequency Catheter Ablation

This study aimed to assess whether intra- and inter-atrial conduction delay could predict atrial fibrillation (AF) for paroxysmal supraventricular tachycardia (PSVT) patients after successful treatment by radiofrequency catheter ablation (RFCA). Echocardiography examination was performed on 524 consecutive PSVT patients (15 patients were excluded). Left atrial dimension, right atrial diameter and intra- and inter-atrial conduction delay were measured before ablation. Patients were divided into group A (n = 32): occurrence of AF after the ablation and group B (n = 477): remained in sinus rhythm during follow-up. Receiver operating characteristic (ROC) curve analysis was performed to estimate the predictive value of intra- and inter-atrial conduction delay. Both intra- and inter-atrial conduction delay were higher in group A than in group B (4.79 ± 0.30 msec vs. 4.56 ± 0.32 msec; 21.98 ± 1.32 msec vs. 20.01 ± 1.33; p < 0.05). Binary logistic regression analysis showed that intra- and inter-atrial conduction were significant influential factors for the occurrence of AF (odds ratio [OR] = 13.577, 95% confidence interval [CI], 3.469–48.914; OR = 2.569, 95% CI, 1.909−3.459, p < 0.05). The ROC cure analysis revealed that intra-atrial conduction delay ≥ 4.45 msec and inter-atrial conduction delay ≥ 20.65 were the most optimal cut-off value for predicting AF in PSVT patients after RFCA. In conclusion, this is the first study to show that the intra- and inter-atrial conduction delay could effectively predict AF in post-ablation PSVT patients.

Atrial Electromechanical Conduction Delay in Patients with Neurocardiogenic Syncope

We aimed to investigate the presence of atrial electromechanical conduction delay in patients with neurocardiogenic syncope, which was diagnosed with head-up tilt table test (HUTT). A total of 29 patients (mean age: 30.6 ± 15.9 years) with vasovagal syncope, as diagnosed by HUTT, and 23 healthy control subjects (mean age: 34.7 ± 16.3 years) with a negative HUTT were enrolled to the study. Atrial electromechanical conduction delay was defined as the time elapsed from the beginning of the P wave in the electrogardiogram to the beginning of the Am wave in tissue Doppler. There was no statistically significant difference between the groups in terms of interatrial conduction delay, whereas the difference was significant with regard to the right intraatrial electromechanical conduction delay (P < 0.01) and the left intraatrial electromechanical conduction delay (P < 0.0001). There was a negative correlation between the left intraatrial electromechanical conduction delay and the right intraatrial electromechanical conduction delay (r = -0.486, P = 0.001), whereas a positive correlation was present with the interatrial electromechanical conduction delay (r = 0.507, P = 0.001). In this study, the tissue Doppler method revealed that there is left and right intraatrial electromechanical conduction delay in patients with vasovagal syncope. The impact and role of atrial conduction delay as a pathophysiological determinant should be confirmed in further studies.

Bachmann's bundle pacing not only improves interatrial conduction but also reduces the need for ventricular pacing

Background: Patients treated for sick sinus syndrome may have interatrial conduction disorder, what often leads to atrial fibrillation. Moreover, up to 20% of them have atrioventricular conduction delay which worsens over time and is responsible for the need of ventricular pacing. Implantation of atrial lead in right atrium appendage (RAA) is the reason for longer interatrial and atrioventricular conduction time even in patients without prior disorders. Purpose: The aim of this study was to assess influence of atrial pacing site on interatrial and atrioventricular conduction and the percentage of ventricular pacing in population with SSS implanted with DDD pacemaker. Methods: The study group consisted of 107 patients (64 F, 43 M) aged 71,2±18,7 years. Patients were divided in two groups: group I (n=51) with RAA pacing, group II (n= 56) with Bachmann's area pacing. Differences in atrioventricular conduction in sinus rhythm and AAI 60 and 90/min pacing were assessed. Also P wave width at sinus rhythm and during atrial pacing as well as percentage of ventricular stimulation were compared. P wave morphology was studied in surface ECG leads I and II. Results: There were no differences in baseline P wave duration in sinus rhythm between the groups (99.7±16 ms vs 103.0±28 ms, p=n.s.). Atrial pacing 60 bpm revealed longer P wave duration with atrial lead location in RAA in comparison to Bachmann's bundle region (141.1±24.3 vs 107.2±14.2 ms, p<0.01). In group II the P wave morphology was more comparable with sinus P wave. The differences between atrioventricular conduction time during sinus rhythm and atrial pacing at 60 and 90 bpm were significantly longer in patients with RAA vs. Bachmann's pacing (42.1±16 vs 8±7 ms p<0.01 and 68±32 vs 22±11 ms p<0.005, respectively). The percentage of ventricular pacing was higher in group I (19±1 vs 3±3%, p<0,01). Conclusions: 1. Right atrium appendage pacing in SSS pts promotes atrioventricular conduction disorder which results in higher percentage of ventricular pacing in DDD mode. 2.The Bachmann's bundle region pacing of right atrium results in less pronounced interatrial and atrioventricular conduction delay.

研究 Disopyramide, Aprindine, Mexiletineによる頻度依存性心房間伝導時間延長の検討

研究 Disopyramide, Aprindine, Mexiletineによる頻度依存性心房間伝導時間延長の検討

Impaired atrial electromechanical function and atrial fibrillation promotion in alloxan-induced diabetic rabbits

Diabetes mellitus (DM) is an independent risk factor for atrial fibrillation (AF). However, the underlying mechanisms are still not clearly elucidated. The aim of this study was to evaluate the atrial electromechanical function, atrial electrophysiological changes and AF inducibility in alloxan-induced diabetic rabbits. In 8 alloxan-induced diabetic rabbits and 8 controls, we evaluated atrial electromechanical function by tissue Doppler imaging. Isolated Langendorff-perfused rabbit hearts were prepared to measure atrial refractory effective period (AERP) and its dispersion (AERPD), interatrial conduction time (IACT) and vulnerability to AF. Atrial interstitial fibrosis was evaluated by Sirius-Red staining. Compared with controls, left atrial lateral wall Pa'-start interval (Pastart) and right atrial wall Pastart were increased in diabetic rabbits. AERPD was increased and IACT was prolonged in diabetic rabbits. Inducibility of AF in diabetic group was significant higher than controls (6/8 vs. 1/8, p < 0.05). Extensive interstitial fibrosis was observed in the DM group (p < 0.01). Correlation analysis showed that right atrial wall Pastart, Pa'-peak interval (Papeak) and total electromechanical activity (TEMA); left atrial lateral wall Papeak and TEMA, left atrial posterior wall TEMA, and IACT were correlated with atrial areas of fibrosis. Atrial electromechanical function is impaired in diabetic rabbits, and is associated with atrial fibrosis and interatrial electrical conduction delay.