Interatrial Conduction Time Research Articles

Interatrial Conduction Measured During Biventricular Pacemaker Implantation Accurately Predicts Optimal Paced Atrioventricular Intervals

Optimizing atrioventricular (AV) delay during biventricular (BiV) pacemaker implantation can require substantial resources. Hence, a simpler method is desirable. We hypothesized that interatrial conduction time (IACT), measured at the time of BiV device implant, could be a surrogate value for the optimal AV delay. This study determined the relationship between paced IACT and the optimal paced AV delay (PAV), as determined by echocardiography. Consecutive subjects (N = 25; age = 66 +/- 10 years; M/F: 17/8) undergoing BiV pacemaker implantation and in sinus rhythm were included. Cannulation of the coronary sinus (CS) was at the operator's discretion. A quadripolar electrophysiology catheter was inserted via the guiding sheath into the inferiolateral CS to measure left atrial depolarization. The IACT was calculated as the interval between right atrial stimulation artifact and earliest deflection on the coronary sinus catheter electrogram. Subsequently, during atrial pacing the PAV was determined using transmitral pulsed wave Doppler echocardiography (iterative method). The relationship between paced IACT and PAV was then determined. The mean +/- SD paced IACT and PAV were 126 +/- 25 msec and 157 +/- 23 msec, respectively. There was a strong positive correlation between the paced IACT and PAV (r = 0.73, P < 0.001). The equation describing the relationship was PAV = 0.68 * (IACT + 104) msec. The paced IACT has a strong correlation with the echo derived optimal PAV. This method may be used to program PAV intervals without need for echocardiography in patients undergoing BiV pacemaker implantation.

Assessment of Atrial Conduction in Patients with Scleroderma by Tissue Doppler Echocardiography and P Wave Dispersion

Background: Atrial conduction abnormalities in patients with scleroderma have not been evaluated in terms of P wave duration, P wave dispersion (P_d) and electromechanical coupling measured by tissue Doppler echocardiography. Methods: Twenty-four patients with scleroderma and 24 control subjects underwent resting electrocardiogram (ECG), M mode and tissue Doppler echocardiography. The P wave duration was calculated in all leads of the surface ECG. The difference between the maximum (P_max) and minimum P wave duration was calculated and defined as P_d. Interatrial and intraatrial electromechanical delays were measured with tissue Doppler tissue echocardiography. Results: The left ventricular dimensions, fractional shortening, and left atrial diameter did not differ between the patients and the controls. P_d and P_max were significantly higher in patients with scleroderma compared with controls: 51 ± 17 versus 28 ± 7 ms (p < 0.01) and 109 ± 10 versus 93 ± 6 ms (p < 0.01), respectively. There was a delay between the onset of the P wave on surface ECG and the onset of the late diastolic wave (A wave; PA) obtained by tissue Doppler echocardiography in patients with scleroderma compared with controls measured at lateral septal annulus (lateral PA; 122 ± 8 vs. 105 ± 7 ms, p = 0.001), septal mitral annulus (104 ± 11 vs. 93 ± 10 ms, p = 0.01) and tricuspid annulus (right ventricular PA; 71 ± 9 vs. 64 ± 7 ms, p = 0.05). Interatrial conduction time (lateral PA – right ventricular PA) was delayed in patients with scleroderma compared with controls (88 ± 13 vs. 76 ± 11 ms, p = 0.01). A positive correlation was detected between interatrial electromechanical delay (lateral PA – right ventricular PA) and P_d (r = 0.5, p = 0.03). Conclusion: Atrial conduction abnormalities as estimated with P_d and P_max are significantly higher in patients with scleroderma compared with controls. There is a delay in both intraatrial and interatrial electromechanical coupling intervals in patients with scleroderma.

P-Wave Durations in Patients Experiencing Atrial Fibrillation During Exercise Testing

Augmented sympathoadrenal activity during exercise may contribute to occurrence of various arrhythmias including atrial fibrillation (AF). The prolongation of intraatrial and interatrial conduction times and inhomogeneous propagation of sinus impulses are well-known characteristics of the atrium prone to fibrillate and are evaluated by maximum P-wave duration (P max), P-wave dispersion (PWD). To show the increased P max and PWD values in patients experiencing AF during exercise testing and the role of beta blockade on treatment of exercise-induced AF, 22 of these patients were compared with a control group consisting of 41 patients without AF attacks. P max (p = 0.001) and PWD (p = 0.001) values were significantly higher in patients with AF compared to those without AF. The development of AF during exercise testing was found to be positively correlated with P max (r = 0.87, p < 0.001), PWD (r = 0.83, p = 0.001), and work load (r = 0.34, p = 0.002) and negatively correlated with ejection fraction (r = -0.26, p=0.02). After the treatment with beta-blocking agents for 2 weeks, the decrease in P max and PWD values was accompanied by a much lower prevalence of exercise-induced AF. Consequently, the patients with AF had greater P max and PWD values compared to control subjects, and these simple parameters were well correlated with the occurrence of AF during exercise testing. Furthermore, treatment of these patients with beta blockers would appear to decrease the recurrence of exercise-induced AF and to be associated with a decrease in P-wave durations.

Suppression of atrial fibrillation by interatrial septum pacing

Interatrial septum pacing seems efficient in synchronizing atrial depolarization in patients with delayed interatrial conduction, but its clinical role in preventing atrial fibrillation is still disputed. The aim of this study was to evaluate the clinical efficacy of interatrial septum pacing guided by electrophysiological testing. Thirty patients (22 male, 8 female, 70.2+/−3.4 years) were enrolled, with drug refractory paroxysmal atrial fibrillation, sinus bradycardia, prolonged P wave duration (132.5+/−8.4 ms), enlarged left atria (inner diameter 3.5+/−0.2 cm) and high atrial fibrillation burden (20+/−3%). Multipolar catheters were used for finding the most suitable site for synchronizing the atria. Then an active fixation atrial lead was positioned at this site. During the interatrial septum pacing, the P wave duration decreased significantly (from 132.5+/−8.4 to 80.0+/−8.5 ms, P<0.001) and interatrial conduction time reduced (from 101.5+/−1.1 to 17.1+/−3.9 ms, P<0.001). After three months follow-up, the atrial fibrillation burden of the patients was decreased (from 20+/−3% to 15+/−4%, P<0.05) and sinus rhythm duration increased (from 20+/−2 days to 25+/−4 days, P<0.05). The results suggest that interatrial septum pacing reduced the incidence of drug refractory paroxysmal atrial fibrillation.

Left Atrial Remodeling: Assessment of Size and Shape to Detect Vulnerability to Atrial Fibrillation

The ellipse formula often underestimates left atrial (LA) dilation. Complete echocardiographic analysis of LA shape in relation to electrical remodeling has not been performed. To analyze the relation between LA shape/surface and vulnerability to atrial fibrillation (AF). We studied 112 patients aged 43 +/- 16 years, and referred for electrophysiological study. LA surface (LAS) was measured at end-systole (maximal). Trapezoidal LA shape was defined if the transverse dimension was less than the basal dimension. Decremental index (DI) was calculated as the maximal percentage prolongation of interatrial conduction time during atrial extrastimulation. The LA was considered vulnerable if AF was inducible. DI > 50%, repetitive atrial activity, and fragmented electrograms defined susceptibility to vulnerability. LAS ranged between 10.5 and 36.6 cm(2); 77 patients had a trapezoidal LA. By simple regression analysis LAS correlated with DI (r(2) = 0.38, P = 0.0001). LAS predicted susceptibility to vulnerability better than vulnerability to AF (area under the ROC curve: 0.93 vs 0.81). The best cut-off value for LAS as predictor of susceptibility to vulnerability was 19.5 cm(2) (sensitivity: 89%; specificity: 90.5%; positive predictive value: 93.4%; negative predictive value: 84.4%). Using LAS > 25 cm(2) as a cut-off value, LA vulnerability to AF was detected with a sensitivity of 56.2% and a specificity of 95% (positive predictive value: 81.8%; negative predictive value: 83.3%). LA shape was trapezoidal in 72% patients with LAS > 25 cm(2) and in 30% patients with LAS < 19.5 cm(2) (P < 0.0001). LA dilation and electrical remodeling are related. Progressive LA dilation is accompanied by shape remodeling. Appropriate characterization of LA remodeling should therefore include LAS measurement and LA shape assessment.

In Vivo Electropharmacological Effects of Amiodarone and Candesartan on Atria of Chronic Atrioventricular Block Dogs

Electropharmacological effects of chronically administered amiodarone and candesartan on atria that had been remodeled against congestive heart failure were assessed using dogs (about 10 kg in weight) with chronic atrioventricular block. Amiodarone was administered orally in a dose of 200 mg/body per day for the initial 7 days followed by 100 mg for the following 21 days (n = 7). Candesartan was administered in a dose of 12 mg/body per day for 28 days (n = 7). All animals survived the 4-week experimental period, indicating the lack of risks for inducing cardiohemodynamic collapse or torsade de pointes by these drugs. The plasma amiodarone concentration was 353 ng/ml at 4 weeks of treatment. Before candesartan treatment (control), intravenous administration of 30 ng/kg of angiotensin II increased the mean blood pressure by 18 mmHg, which was significantly decreased to 1 mmHg by 4 weeks of treatment. Amiodarone prolonged the atrial effective refractory period without affecting inter-atrial conduction time and decreased the duration of the burst pacing-induced atrial fibrillation, whereas candesartan hardly affected these variables. These results indicate that amiodarone should become a pragmatic pharmacological strategy against atrial fibrillation in patients with chronically compensated heart failure and suggest that a much higher dose of candesartan may be needed to exert its efficacy in this model.

P Wave Dispersion: A Valuable Non-Invasive Marker of Vulnerability to Atrial Arrhythmias

The prolongation of intraatrial and interatrial conduction time and the non-homogeneous propagation of sinus impulses are well known electrophysiologic characteristics in patients with atrial arrhythmias and especially paroxysmal atrial fibrillation (AF). Previous studies have demonstrated that individuals with clinical history of paroxysmal AF show a significantly increased P wave duration in 12-lead surface electrocardiograms (ECG) and signal-averaged ECG recordings. The inhomogeneous and discontinuous atrial conduction in patients with atrial arrhythmias has been studied, during the last years, with a new ECG index, P wave dispersion. P wave dispersion is defined as the difference between the longest and the shortest P wave duration recorded from multiple different surface ECG leads. Extensive clinical evaluation of P wave dispersion has been performed in the assessment of the risk for AF in patients without apparent heart disease, in hypertensive patients, in patients with coronary artery disease, in patients undergoing coronary artery bypass surgery, in patients with congenital heart diseases, as well as in other groups of patients suffering from various cardiac or non-cardiac diseases. P wave dispersion has proven to be a sensitive and specific ECG predictor of AF in the various clinical settings. However, the methodology used for the calculation of P wave dispersion has not been standardized so far and more efforts to improve the reliability and reproducibility of P wave dispersion measurements are needed. In conclusion, P wave dispersion constitutes a significant contribution to the field of non-invasive electrocardiology and seems to be quite promising in the field of AF prediction.

Atrial Stretch in Patients with Paroxysmal Junctional Tachycardias and Atrial Fibrillation but Structurally Normal Heart

to comparatively assess echographic indicators of atrial dilatation and decremental intra and interatrial and conduction in patients (pts) presenting junctional reentrant tachycardias (JT) with or without paroxysmal atrial fibrillation (pAF). 58 pts without structural heart disease, referred to electrophysiological study which underwent ablation for JT were studied; 26 pts aged 41±10 years with pAF episodes/ inducible AF, were compared to 32 control-matched JT pts aged 39±12 years. Parameters: left atrial dimensions (LAd = M-mode, parasternal, LAt and LAl are measurements of short and long-axis apical four chamber view), surface (LAs), volume (LAv using ellipse formula), right atrial surface (RAs), total atrial surface (TAs = LAs+RAs). Decremental index (DI) was calculated as maximum percent prolongation of interatrial conduction time (iaCT) during S2 and S3 delivery. there was no difference between the 2 groups concerning baseline iaCT (59±21 ms vs 53±18 ms p = 0.08), LAd (p = 0.08) and LAt (p = 0.09) while the following parameters were significantly higher in pAF pts: LAl: 5.0±0.5 vs 4.5±0.3cm, (p = 0.001); LAs: 19.6±5.7 vs 16.3±2.1cm2, (p = 0.001); TAs: 35.6±6.9 vs 27.6±5.1 cm2 (p = 0.0001); LAv: 46.6±10.4 vs 37.2±9.3 ml, (p = 0.0001); DI: 41±17% vs 24±14% (p = 0.001). In pAF group, atrial fragmentation and atrial double potentials were recorded in 23 pts. No control pts had this evidence. this study supports the role of atrial stretch in the genesis of AF in pts with junctional tachycardias. Further studies need to investigate the relation between burden of tachycardia and atrial stretch in a larger population.

Anatomical and Electrical Remodelling in Paroxysmal vs. Persistent Atrial Fibrillation

to assess the relation between decremental interatrial conduction properties and atrial dilatation in patients (pts) with paroxysmal (p) vs persitent (P) atrial fibrillation (AF). pts without structural heart disease and sustained AF episodes <1 month were included. Parameters: left atrial dimensions, surface (LAs), volume (LAv ellipse formula), right atrial surface (RAs), total atrial surface (TAs=LAs+RAs). To examine atrial electrophysiological properties it was calculated maximum percentage prolongation of interatrial conduction time (iaCT) during premature stimulation of high right atrium using S2 and S3 delivery: decremental index (DI) =iaCT S3-iaCTS1/iaCTS1%. 27 pAFpts (53±9 years) were compared to 21 PAFpts (55±13 years). Following parameters were significantly higher in PAFpts: DI: 79±25% vs 51±19%, p<0.0001; LAl: 5.5±0.3 vs 5.2±0.3cm, p = 0.01; LAs: 23.5±3.1 vs 19.5±2.4cm2, p = 0.001; LAv: 59.2±9.3 vs 53.6±10.4 ml, p = 0.001; TAs: 41.6±5.1 vs 35.6±6.9 cm2, p = 0.0001. The simple regression analysis demonstrated a moderate correlation between TAs and DI (r = 0,66, r2=0.44, p<0.0001), LAv and DI (r=0,6 r2=0.36, p<0.0001). This study demonstrates increased atrial stretch in PAFpts compared to pAFpts and that electrical remodelling is associated with anatomic remodelling.

763 Is age correlated with dynamic atrial decremental conduction properties?

Atrial fibrillation (AF) has been associated with premature beats and decreased atrial conduction velocities. On the other hand, prevalence of AF is increased in the elderly. The aim is to evaluate and analyze the relation between age, atrial size and a new index of dynamic interatrial conduction time (iaCT) in a homogeneous population of patients (pts) with structurally normal heart without AF.45 patients (pts) without structural heart disease aged 53 +/- 20 years referred for electrophysiologic study were analyzed. To examine the atrial electrophysiologic characteristics we studied interatrial conduction time (iaCT), double potentials and fragmented atrial activity during premature stimulation of high right atrium; prior to investigation, all antiarrhythmic drugs were withdrawn for an appropriate period of time. The following parameters were assessed: baseline iaCT (iaCTb) between high right atrium (HRA) and distal coronary sinus (CS), iaCT during HRA pacing S1S1 600ms (iaCTS1), maximum prolongation of iaCT during S2 and S3 delivery (iaCTS2, iaCTS3). We calculated a derived parameter: maximum prolongation iaCT/decremental index (DI)= iaCT S3-ia CTS1/iaCTS1%. The following echocardiograhic parameters were assessed: left atrial dimensions and surface (LAs), right atrial dimension and surface (RAs), total atrial surface (TAs=LAs+RAs) and left atrial volume (LAv) calculated using ellipse formula.iaCT ranged from 42 to 87ms; DI ranged from 16 to 52%. Simple regression analysis demonstrated a statistically significant linear correlation between the age of pts and HRA DI (r = 0.76, r2 = 0.55, p <0.0001). A trend toward a significant correlation was found between TAs and DI (r=0.64, r2=0.41, p<0.0001) LAv and DI (r=0.59, r2=0.35, p<0.0001). No significant correlation was found in this group between age and iaCT. Atrial double potentials and fragmentated electrograms were recorded using HRA stimulation in CS leads in 7 pts (15%) all aged >35 years. Pts were divided into two groups: 17 pts with normal electrophysiologic findings and 28 pts with junctional reentrant tachycardia. There were no significant differences between subgroups concerning the main studied parameters.This study shows a direct better correlation for age than atrial size in the relation with the dynamic behaviour interatrial conduction, suggesting that higher incidence in AF in the elderly might be also a consequence of the higher incidence of atrial conduction disturbances.

Mechanism of Atrial Fibrillation:

Atrial fibrillation (AF) has been associated with premature beats and decreased atrial conduction velocity. This study examined a new index of dynamic inter-atrial conduction time (iaCT) in patients with paroxysmal AF (PAF). We compared 42 consecutive patients with paroxysmal AF (mean age = 52 +/- 16 years) without structural heart disease with 39 age-matched patients (mean age = 49 +/- 15 years) who underwent ablation of junctional tachycardias. Prior to investigation, all antiarrhythmic drugs were discontinued for an appropriate period of time. The following measurements were made: baseline iaCT (iaCTb) between high right atrium (HRA) and distal coronary sinus, iaCT during HRA pacing S1S1 600 ms (iaCTS1), maximum prolongation of iaCT during S2 and S3 delivery (iaCTS2, iaCTS3). We then derived the decremental index (DI), the maximum percent prolongation of iaCT = iaCT S3-iaCTS1/iaCTS1%. In patients with PAF, iaCTb was 81.3 +/- 24 ms versus 59.5 +/- 14 ms in controls (P = 0.0001). Atrial fibrillation was reproducibly and easily induced with a prominent increase in iaCT in 11 patients with AF. In this subgroup DI was 92 +/- 17%, compared to 45 +/- 21% in the other patients with AF (P = 0.0001) and 21 +/- 15% in the control group (P = 0.0001). Spontaneous isolated or repetitive ectopic activity was observed in 11 patients with AF (26%), and decremental atrial conduction was observed in 76% of patients with AF. This study supports the role of dynamic inter-atrial conduction disturbances in patients with lone PAF. The DI may be a new index of vulnerability to paroxysmal AF.

Inter-atrial conduction time shortens after blood pressure control in hypertensive patients with left ventricular hypertrophy

Assuming that blood pressure control could induce a shortening of the inter-atrial conduction time and prevent atrial fibrillation occurrence, we studied the inter-atrial conduction time in hypertensive patients with left ventricular hypertrophy. Methods Sixty-eight (26 male) 58.34±8.08-year-old patient participated in the study. All were in sinus rhythm and had abnormal blood pressure (163±18/95±9 mm Hg). Their cardiac mass index was increased (151±43 g/m 2 SC) and their left atrial dimension was normal (3.67±0.54 cm). The inter-atrial conduction time was measured in the echocardiogram from the beginning of the electrocardiographic P wave to the beginning of the A wave in the mitral Doppler signal and was corrected for heart rate. Heart rhythm disturbances were monitored clinically and by means of a Holter. Most patients were treated with angiotensin antagonists. Results It was found that arterial blood pressure decreased significantly after treatment and that the P–A interval was significantly reduced (71.4±14.5 vs. 63.9±11.5 ms). During the follow-up, no patient complained of arrhythmia symptoms or exhibited atrial fibrillation in the Holter recording. Conclusion In this selected group of patients with hypertensive heart disease (left ventricular hypertrophy), an effective blood pressure control was accompanied by a significant decrease in the inter-atrial conduction time. It is possible that these effects prevent atrial fibrillation.

Evaluation of atrial refractoriness immediately after percutaneous mitral balloon commissurotomy in patients with mitral stenosis and sinus rhythm

Background Chronic atrial stretch and rheumatic inflammatory activity leads to atrial dilatation and conduction slowing, and this increases the susceptibility to atrial fibrillation (AF). The aim of this study was to examine the effects of changes in the chronic atrial stretch on atrial refractoriness in the early period after percutaneous mitral balloon commissurotomy (PMBC) in patients with mitral stenosis and sinus rhythm. Methods Twenty-five patients undergoing PMBC were enrolled in this study. We evaluated the changes in pulmonary arterial pressure (PAP), left atrial (LA) pressure, mean mitral diastolic gradient, and mitral valve area in addition to the changes in atrial effective refractory periods (AERPs), AERP dispersion, and intra-atrial and interatrial conduction times after PMBC. Results There were significant decreases in mean diastolic gradient, PAP, mean LA pressure, and LA size after PMBC. Accompanying these acute hemodynamic changes after PMBC, AERPs in high right atrium (HRA), distal coronary sinus (DCS), and right posterolateral (RPL) were found to be increased ( P <.001), and AERP dispersion, PA HIS (an interval between P wave on the surface electrocardiogram and atrial electrogram at the His bundle site), and HRA-DCS intervals were significantly reduced after PMBC ( P <.001). It was revealed with linear regression and correlation analysis that only the changes in AERP dispersion were correlated with changes in LA pressure. Conclusions Relief of chronic atrial stretch results in an increase in AERPs and decrease in AERP dispersion, suggesting the potential reversibility of the electrophysiological features of chronic atrial dilatation. Our study emphasizes that an acute reduction of chronic atrial stretch in mitral stenosis resulted in favorable effects on atrial electrophysiological characteristics, and our results provide the first detailed insights into the electrophysiological changes after PMBC in patients with sinus rhythm.

Improvement of Atrial Signal-Averaged Electrocardiographic Abnormalities After Radiofrequency Catheter Ablation in Persistent Atrial Flutter

It has been reported that abnormalities of atrial conduction are present in patients with atrial flutter (AFL). We analyzed the P wave signal-averaged ECG (PSE) in patients after cardioversion of chronic AFL by radiofrequency catheter ablation (RFCA) to determine whether abnormalities of atrial conduction exist in patients with AFL and whether they recover. We studied 11 patients undergoing ablation of persistent AFL (AFL group), 11 patients with paroxysmal AFL (PAFL group), and 14 patients without any evidence of arrhythmias (control group). The PSEs were recorded 1 day, 7 days, and 1 month after RFCA. The filtered P wave duration (FPD) was calculated from the PSE recording. The FPD correlated with interatrial conduction time (r = 0.644) and left atrial dimension (r = 0.675) in combined assessment of the AFL and PAFL groups. The FPD was longer in the AFL group 1 day (165 +/- 14 ms, P < 0.001) and 1 month (150 +/- 18 ms, P < 0.05) after RFCA than in the control group (134 +/- 10 ms). Our findings suggest that atrial conduction abnormalities detected by PSE are present in patients with persistent AFL and improve 1 month after cardioversion.

P-379 Effects of interatrial septum pacing on interatrial conduction times and on systolic and diastolic ventricular function: An echo-doppler study

P-379 Effects of interatrial septum pacing on interatrial conduction times and on systolic and diastolic ventricular function: An echo-doppler study

P-379 Effects of interatrial septum pacing on interatrial conduction times and on systolic and diastolic ventricular function: An echo-doppler study

P-379 Effects of interatrial septum pacing on interatrial conduction times and on systolic and diastolic ventricular function: An echo-doppler study

P-035 the role of decremential behavior of interatrial conduction time in patients with paroxistic atrial fibrillation

P-035 the role of decremential behavior of interatrial conduction time in patients with paroxistic atrial fibrillation

P-035 The role of decremential behavior of interatrial conduction time in patients with paroxistic atrial fibrillation

Background: Reentering wavelets may initiate atria1 fibrillation (AF) if the intera AF was easily and reproducibly inducible with significant increase in iaCT at PAS in 11 pts of pAF group; in this subgroup DI was 106&11%, while DI was signiiicantly smaller in the rest of the pAF pts (63X DI may be consider as a new index for inducibility of AF in EPS.

Age-related sensitivity to nicotine for inducible atrial tachycardia and atrial fibrillation

The influence of nicotine in modulating vulnerability to atrial tachycardia and fibrillation (AT/AF) remains ill defined. The isolated hearts of six young (2-3 mo) and six old (22-24 mo) male Fischer 344 rats were Langendorff perfused at 5 ml/min with oxygenated Tyrode solution at 37 degrees C, and the whole heart was also super-fused with warmed oxygenated Tyrode solution at 15 ml/min. Nicotine prolonged the interatrial conduction time and effective refractory period that were significantly (P < 0.05) higher in the old than in the young rats in a concentration-dependent manner. Nicotine had a biphasic effect on burst atrial pacing-induced AT in both groups, increasing it at 10-30 ng/ml while decreasing it at 50-100 ng/ml (P < 0.01). Nicotine at 10-100 ng/ml increased burst atrial pacing-induced AF in the young rats but suppressed it in the old rats (P < 0.01). Optical mapping showed the presence of multiple independent wavefronts during AF and a single periodic large wavefront during AT in both groups. Nicotine, at concentrations found in the blood of smokers (30-85 ng/ml), exerts biphasic effects on inducible AT/AF in young rats and suppresses it in the old rats by causing high degrees of interatrial conduction block.

8.1 ECHO-Doppler study of interatrial conduction times with interatrial septum pacing

8.1 ECHO-Doppler study of interatrial conduction times with interatrial septum pacing