Randomized crossover comparison of right atrial appendage pacing versus interatrial septum pacing for prevention of paroxysmal atrial fibrillation in patients with sinus bradycardia

Alternative atrial pacing site to improve cardiac function: focus on Bachmann's bundle pacing

Pacing from the right atrial appendage (RAA) prolongs the P wave duration and can induce interatrial and especially left-sided atrio-ventricular dyssynchrony. Pacing from Bachmann's bundle closely reproduces normal physiology and has the potential to avoid the electromechanical dysfunction associated with conventional RAA pacing. Interatrial conduction delay is associated with an increased risk of stroke, heart failure, and death. In addition to a reduction in atrial fibrillation, Bachmann's bundle pacing has emerging applications as a hemodynamic pacing modality. This review outlines the pathophysiology of atrial conduction disturbances and their potential remedies and provides the reader with a practical guide to implementing Bachmann's bundle pacing with an emphasis on the recapitulation of normal electrical and mechanical function.

Association between sick sinus syndrome and atrial fibrillation: A systematic review and meta-analysis

AIMS

Sick sinus syndrome (SSS) and atrial fibrillation (AF) frequently coexist and show a bidirectional relationship. This systematic review and meta-analysis aimed to decipher the precise relationship between SSS and AF, further exploring and comparing different therapy strategies on the occurrence or progression of AF in patients with SSS.

METHODS AND RESULTS

A systematic literature search was conducted until November 2022. A total of 35 articles with 37,550 patients were included. Patients with SSS were associated with new-onset AF compared to those without SSS. Catheter ablation was associated with a lower risk of AF recurrence, AF progression, all-cause mortality, stroke and hospitalization of heart failure compared to pacemaker therapy. Regarding the different pacing strategies for SSS, VVI/VVIR has higher risk of new-onset AF than DDD/DDDR. No significant difference was found between AAI/AAIR and DDD/DDDR, as well as between DDD/DDDR and minimal ventricular pacing (MVP) for AF recurrence. AAI/AAIR was associated with higher risk of all-cause mortality when compared to DDD/DDDR, but lower risk of cardiac death when compared to DDD/DDDR. Right atrial septum pacing was associated with a similar risk of new-onset AF or AF recurrence compared to right atrial appendage pacing.

CONCLUSION

SSS is associated with a higher risk of AF. For patients with both SSS and AF, catheter ablation should be considered. This meta-analysis re-emphasizes that high percentage of ventricular pacing should be avoided in patients with SSS in order to decrease AF burden and mortality.

Patient with sick sinus syndrome and implanted dual-chamber pacemaker with reduced P-wave duration following low interatrial septal pacing: Case report

INTRODUCTION

A dual-chamber pacemaker (DDD/R) for a sinus node disease is sometimes referred to as a physiological pacemaker as it maintains atrioventricular synchrony, however several clinical trials have proved its inferiority to a nonphysiological single-chamber ventricular back-up pacing.

PATIENT CONCERNS

A subject of the study is a 74-year-old woman with a sick sinus syndrome (SSS) and a previously implanted physiological DDD/R pacemaker. The SSS was diagnosed because of patient's very slow sinus rhythm of about 36 bpm, and due to several episodes of dizziness. After the DDD/R implantation the percentage of atrial pacing approached 100%, with almost none ventricular pacing.

DIAGNOSES

Sick sinus syndrome, complete Bachmann's bundle block, atrial fibrillation, atrial flutter.

INTERVENTIONS

The patient was previously implanted with a physiological DDD/R pacemaker. Several years after the implantation, the atrial fibrillation was diagnosed and the pulmonary vein isolation was then performed by cryoablation. During the follow-up after pulmonary vein isolation, the improvement of mitral filling parameters was assessed using echocardiography. Shortly thereafter the patient developed the persistent paroxysm of a typical atrial flutter which was successfully terminated using a radiofrequency ablation. No recurrence thereof has been observed ever since (24 months).

OUTCOMES

The atrial electrode of the pacing system was implanted within the low interatrial septal region that resulted in a reduced P-wave duration compared to native sinus rhythm P-waves. The said morphology was deformed because of the complete Bachmann bundle block. That approach, despite a nonphysiological direction of an atrial activation, yielded relatively short P-waves (paced P-wave: 179 ms vs intrinsic sinus P-wave: 237 ms). It also contributed to a significantly shorter PR interval (paced PR: 204 ms vs sinus rhythm PR: 254 ms).

CONCLUSIONS

The authors took into consideration different aspects of alternative right atrial pacing sites. This report has shown that in some patients with a sinus node disease, low interatrial septal pacing can reduce the P-wave duration but does not prevent from the development of atrial arrhythmias.

Nonpharmacological Treatment of Atrial Fibrillation: What Is the Role of Device Therapy?

Atrial fibrillation is the most common arrhythmia in the adult population, and its incidence and prevalence are still rising. Cardiac devices are widely used in clinical practice in the management of various rhythm disturbances and heart failure treatment. Many patients who receive a pacemaker, implantable cardioverter-defibrillator, or cardiac resynchronization therapy also experience atrial fibrillation in the course of their life. Therefore, this review aims to describe the role of these devices in the treatment and prevention of atrial fibrillation in the device recipients. In addition, all these implantable devices also serve as permanent ECG (electrocardiogram) monitors, thus providing important information about the presence and characteristics of atrial fibrillation that may or may not be detected by the patient but can modify our therapeutical approach with regard to the stroke prevention.

Implication of ventricular pacing burden and atrial pacing therapies on the progression of atrial fibrillation: A systematic review and meta-analysis of randomized controlled trials

BACKGROUND

Atrial fibrillation (AF) is common after pacemaker implantation. However, the impact of pacemaker algorithms in AF prevention is not well understood.

OBJECTIVE

The purpose of this study was to evaluate the role of pacing algorithms in preventing AF progression.

METHODS

A systematic search of articles using the PubMed and Embase databases resulted in a total of 754 references. After exclusions, 21 randomized controlled trials (8336 patients) were analyzed, comprising studies reporting ventricular pacing percentage (VP%) (AAI vs DDD, n = 1; reducing ventricular pacing [RedVP] algorithms, n = 2); and atrial pacing therapies (atrial preference pacing [APP], n = 14; atrial antitachycardia pacing [aATP]+APP, n = 3; RedVP+APP+aATP, n = 1).

RESULTS

Low VP% (<10%) lead to a nonsignificant reduction in the progression of AF (hazard ratio [HR] 0.80; 95% confidence interval [CI] 0.57-1.13; P = .21; I² = 67%) compared to high VP% (>10%). APP algorithm reduced premature atrial complexes (PAC) burden (mean difference [MD] -1117.74; 95% CI -1852.36 to -383.11; P = .003; I² = 67%) but did not decrease AF burden (MD 8.20; 95% CI -5.39 to 21.80; P = .24; I² = 17%) or AF episodes (MD 0.00; 95% CI -0.24 to 0.25; P = .98; I² = 0%). Similarly, aATP+APP programming showed no significant difference in AF progression (odds ratio 0.65; 95% CI 0.36-1.14; P = .13; I² = 61%). No serious adverse events related to algorithm were reported.

CONCLUSION

This meta-analysis of randomized controlled trials demonstrated that algorithms to reduce VP% can be considered safe. Low burden VP% did not significantly suppress AF progression. The atrial pacing therapy algorithms could suppress PAC burden but did not prevent AF progression.

Low interatrial septal pacing: A simple method

Background

Sinus node disease is associated with widespread structural and electrophysiological changes in the atria in addition to abnormalities at the sinus node. The atrial conduction disorder in patients with atrial pacing results in higher incidence of atrial fibrillation. Studies have shown that low interatrial septal pacing is superior to right atrial appendage pacing in preventing persistent or permanent atrial fibrillation in these patients. However, implantation of active fixation lead in low interatrial septal position is difficult and time consuming with conventional stylet, inhibiting application of this method in routine practice.

Method

The technique of implanting atrial pacing lead in low interatrial septum with hand-made stylet is presented in this study with emphasis on fluoroscopic landmark and electrocardiographic P wave pattern.

Results

The results indicate acute and short-term success of low interatrial septal pacing in 10 patients out of 11 patients without major complications. Pacing parameters during implantation and 3 months post procedure were within normal limits.

Conclusion

The initial favorable results of this study indicate low interatrial septal pacing with conventional active fixation lead using fluoroscopic landmark and electrocardiographic characteristics is feasible and reproducible with a simple technique.

Electrocardiographic features: Various atrial site pacing

Atrial pacing is done for either symptomatic sinus node dysfunction (SND) or for maintenance of atrio-ventricular synchrony in a dual chamber pacemaker. Conventionally, atrial lead is placed in the right atrial appendage. Atrial conduction disorder in patients with permanent pacing results in higher incidence of atrial fibrillation. Atrial septal pacing has emerged as a solution to this problem. So, it is extremely important to understand the different features of paced P wave from various atrial pacing sites. Conventional right atrial appendage pacing in presence of atrial conduction disorder results in marked latency with prolonged P wave duration with reduced amplitude. The morphology is similar to sinus rhythm. Atrial septal pacing causes short and sharp P wave with negative polarity in inferior leads and positive polarity in lead V1 in lower septal pacing, whereas positive polarity in inferior leads and negative polarity in lead V1 during pacing from upper septum.

Physiological cardiac pacing: Current status

Adverse hemodynamics of right ventricular (RV) pacing is a well-known fact. It was believed to be the result of atrio-ventricular (AV) dyssynchrony and sequential pacing of the atrium and ventricle may solve these problems. However, despite maintenance of AV synchrony, the dual chamber pacemakers in different trials have failed to show its superiority over single chamber RV apical pacing in terms of death, progression of heart failure, and atrial fibrillation (AF). As a consequence, investigators searched for alternate pacing sites with a more physiological activation pattern and better hemodynamics. Direct His bundle pacing and Para-Hisian pacing are the most physiological ventricular pacing sites. But, this is technically difficult. Ventricular septal pacing compared to apical pacing results in a shorter electrical activation delay and consequently less mechanical dyssynchrony. But, the study results are heterogeneous. Selective site atria pacing (atrial septal) is useful for patients with atrial conduction disorders in prevention of AF.

Hybrid therapy in the management of atrial fibrillation

Atrial fibrillation is the most common sustained arrhythmia. Because of the sub-optimal outcomes and associated risks of medical therapy as well as the recent advances in non-pharmacologic strategies, a multitude of combined (hybrid) algorithms have been introduced that improve efficacy of standalone therapies while maintaining a high safety profile. Antiarrhythmic administration enhances success rate of electrical cardioversion. Catheter ablation of antiarrhythmic drug-induced typical atrial flutter may prevent recurrent atrial fibrillation. Through simple ablation in the right atrium, suppression of atrial fibrillation may be achieved in patients with previously ineffective antiarrhythmic therapy. Efficacy of complex catheter ablation in the left atrium is improved with antiarrhythmic drugs. Catheter ablation followed by permanent pacemaker implantation is an effective and safe treatment option for selected patients. Additional strategies include pacing therapies such as atrial pacing with permanent pacemakers, preventive pacing algorithms, and/or implantable dual-chamber defibrillators are available. Modern hybrid strategies combining both epicardial and endocardial approaches in order to create a complex set of radiofrequency lesions in the left atrium have demonstrated a high rate of success and warrant further research. Hybrid therapy for atrial fibrillation reviews history of development of non-pharmacological treatment strategies and outlines avenues of ongoing research in this field.

Atrial pacing site and atrioventricular conduction in patients paced for sinus node disease

BACKGROUND

Unnecessary ventricular pacing in sinus node disease (SND) must be avoided. To test the hypothesis that in SND, with or without 1st degree atrioventricular (AV) block, cumulative percent ventricular pacing (cum%VP) can be limited by low right atrial septal (LRAS) instead of right atrial appendage (RAA) pacing.

METHODS

We studied 102 dual-chamber pacemaker recipients with SND. The PQ interval on 12-lead electrocardiogram and the atrial paced to ventricular sensed interval (Ap-Vs) during LRAS and RAA pacing were measured and compared at implantation, 3 months and 1 year of follow-up. Group 1 included 62 patients with baseline PQ interval <200 milliseconds during LRAS (n = 28) versus RAA (n = 34) pacing. Group 2 included 40 patients with baseline PQ ≥200 milliseconds during LRAS (n = 20) versus RAA (n = 20) pacing. cum%VP were measured at 3 months and 1 year.

RESULTS

The characteristics and AV conduction properties were similar and the Ap-Vs interval was significantly shorter in the LRAS than in the RAA pacing group up to 1 year (193 ± 32 milliseconds vs. 220 ± 27 milliseconds in Group 1; P = 0.003, 222 ± 41 milliseconds vs. 281 ± 30 milliseconds in Group 2; P < 0.001). While cumulative percent atrial pacing was consistently similar, cum%VP was significantly smaller during LRAS than RAA pacing (1 ± 1% vs. 8 ± 18% in Group 1; P = 0.03, 7 ± 10% vs. 48 ± 38% in Group 2; P < 0.001). Similar observations were made with or without left atrial (LA) enlargement.

CONCLUSION

Compared with RAA, LRAS pacing showed shorter AV interval in SND patients with or without 1st degree AV block and LA enlargement. This beneficial effect persisted through 1-year follow-up, and decreased cum%VP significantly.

Hisian area and right ventricular apical pacing differently affect left atrial function: an intra-patients evaluation

AIMS

Right ventricular apex (RVA) pacing has adverse effects on left atrial (LA) function and may contribute to atrial arrhythmias. The effects of Hisian area (HA) pacing on LA function are still lacking. The objective of this study is to assess the left ventricular (LV) electromechanical activation/relaxation, systolic (S), diastolic (D) phases, and their effects on LA function during pacing from HA and RVA.

METHODS AND RESULTS

Thirty-seven patients with normal cardiac function underwent permanent HA pacing. In all patients, a RVA backup lead was added. The patients first underwent 3 months of HA pacing, followed by 3 months of RVA pacing. After each 3-month period, we compared by echocardiography: S-D LV electromechanical delay (S-D EMD), S-D intra-LV dyssynchrony, LV S-D phases, and their function evaluated by myocardial performance index (MPI) and mitral annular tissue Doppler early diastolic velocity (E'), pulmonary arterial systolic pressure (PASP), and LA function (LA phasic volumes and their emptying fraction). Right ventricular apex compared with HA pacing increased S-D EMD (P < 0.001) and intra-LV dyssynchrony (P < 0.001). As a consequence, a significant longer LV isovolumetric contraction time (P < 0.001) and LV isovolumetric relaxation time (P = 0.05) were measured during RVA compared with HA pacing, whereas LV ejection time was shorter (P = 0.033). Moreover, HA pacing resulted in significantly better MPI (P = 0.039), higher value of E' (P = 0.049), and lower PASP (P < 0.001). Finally, RVA compared with HA pacing was associated to higher LA volumes pre-atrial contraction (P = 0.001) and minimal volume (P = 0.003) with reduction in passive emptying fraction (P < 0.001) and total emptying fraction (P = 0.005).

CONCLUSION

Hisian area compared with RVA pacing resulted in a more physiological LV electromechanical activation/relaxation and consequently better LA function.

Prediction of midterm performance of active-fixation leads using current of injury

BACKGROUND

There are only limited prospective data on the clinical relevance of current of injury (COI) as a predictor of the midterm performance of active-fixation leads. This study sought to investigate whether it is possible to predict the midterm performance of active-fixation leads using COI recorded at the time of implantation.

METHODS AND RESULTS

One hundred fifty patients (78 men; mean age, 63 ± 19 years) who received active-fixation pacing (n = 201) and defibrillator (n = 51) leads were studied. COI was measured from the intracardiac bipolar electrogram recorded at the time of lead implantation. The study outcome was good lead performance at 6 months, defined as P wave ≥ 1.5 mV, threshold <1.5 V for atrial lead, R-wave ≥ 5 mV, and threshold <1 V for ventricular lead. A total of 102 active-fixation atrial and 150 ventricular leads were implanted. During a 6-month follow-up, invasive intervention was required for seven atrial and seven ventricular leads. In multivariate analysis, COI was the only independent predictor of good outcome for the active-fixation atrial (odds ratio [OR]: 5.67, 95% confidence interval [CI]: 2.18-14.76, P = 0.001) and ventricular leads (OR: 3.99, 95% CI: 1.08-21.26, P = 0.002). Receiver-operating characteristic analysis identified ST-segment elevation ≥2.0 mV for the atrial leads (sensitivity, 75%; specificity, 89%) and ≥10.0 mV for the ventricular leads (sensitivity, 70%; specificity, 87%) as optimal cutoffs for good midterm performance.

CONCLUSIONS

Midterm performance of active-fixation leads is predictable using COI recorded at the time of lead implantation. A ST-segment elevation ≥2.0 mV in the atrial leads and ≥10.0 mV in the ventricular leads are recommended to improve the lead performance at 6 months.

Pacing in sinus node disease to prevent atrial fibrillation

Cardiac pacing is the only effective treatment for patients with symptomatic sinus node disease (SND). The majority of patients with SND have several risk factors associated with development of atrial fibrillation (AF) at the time of pacemaker implantation and are therefore considered a high-risk population. Patients with SND can be treated with any kind of commercially available pacemaker pacing in the atrium, the ventricle or both. Pacing in SND can therefore alter atrial and ventricular conduction and atrioventricular coupling. These mechanisms can prevent or contribute to initiation and maintenance of AF during pacing. Different pacemaker modalities and algorithms have been tested to reduce AF in patients with SND in recent decades. To prevent AF in this population, it seems to be important to mimic the optimal electromechanical function of the heart, especially to preserve an optimal atrioventricular coupling.

Effects of baseline P-wave duration and choice of atrial septal pacing site on shortening atrial activation time during pacing

BACKGROUND

Atrial septal pacing (ASP) has been shown to shorten P-wave duration (PWD) and reduce recurrence of atrial fibrillation (AF) in patients with bradyarrhythmias. However, variability of interatrial connections and atrial conduction properties may explain ASP's modest clinical benefit. The aim of this study was to assess the effect of ASP site on the duration of the paced P wave.

METHODS AND RESULTS

Atrial septal pacing at high atrial septum (HAS), posterior septum behind the fossa ovalis (PSFO), and coronary sinus ostium (CSo) was performed in 69 patients admitted for electrophysiological study (52 ± 16 years, 41 men). Twelve-lead electrocardiogram was recorded at baseline and during pacing, signal-averaged for analysis of PWD and P-wave shortening achieved by ASP (ΔPWD = paced PWD-baseline PWD). Baseline PWD was 128 ± 15 ms. The shortest PWD during pacing was achieved at CSo (112 ± 15 ms) followed by HAS (122 ± 14 ms, P< 0.001 vs. CSo) and PSFO (124 ± 21 ms, P< 0.001 vs. CSo). P wave was shortened during pacing in patients with baseline PWD of > 120 ms (n= 50), whereas those with PWD of ≤ 120 ms showed PWD lengthening (n= 19) when paced at HAS (8 ± 17 vs. -12 ± 15 ms, P< 0.001), PSFO (15 ± 17 vs. -12 ± 26 ms, P< 0.001) and CSo (6 ± 16 vs. -25 ± 18 ms, P< 0.001).

CONCLUSION

Pacing at CSo is associated with the shortest PWD. P-wave shortening is greatest in patients with baseline PWD of > 120 ms regardless of the pacing site. The results may have implications on the selection of candidates for ASP and the placement of the atrial septal lead, and warrant further evaluation in cases of permanent pacing in patients with paroxysmal AF.

Efficacy of low interatrial septum and right atrial appendage pacing for prevention of permanent atrial fibrillation in patients with sinus node disease: results from the electrophysiology-guided pacing site selection (EPASS) study

BACKGROUND

The role of pacing sites and atrial electrophysiology on the progression of atrial fibrillation (AF) to the permanent form in patients with sinus node dysfunction (SND) has never been investigated. The aim of the study was to investigate the relationship between atrial electrophysiology and the efficacy of atrial pacing at the low interatrial septum (IAS) or at the right atrial appendage (RAA) to prevent persistent/permanent AF in patients with SND.

METHODS AND RESULTS

The Electrophysiology-Guided Pacing Site Selection (EPASS) Study was a prospective, controlled, randomized study. Atrial refractoriness, basal and incremental conduction times from the RAA to the coronary sinus ostium were measured before implantation, and the difference (ΔCTos) was calculated. Patients with ΔCTos ≥ 50 ms (study group) and those with ΔCTos <50 ms (control group) were randomly assigned to RAA or IAS with algorithms for continuous atrial stimulation "on." The primary end point was time to development of permanent or persistent AF within a 2-year follow-up in the study group, IAS versus RAA. Data were analyzed by intention to treat. One hundred two patients (77 ± 7 years, 44 mol/L) were enrolled, 69 (68%) in the study group and 33 (32%) in the control group. Of these, 97 ended the study, respectively, randomly assigned: 29 IAS versus 36 RAA and 18 IAS versus 14 RAA. After a mean follow-up of 15 ± 7 (median, 17) months, 11 (16.6%) patients in the study group met the primary end point: 2 IAS versus 9 RAA (log rank=3.93, P=0.047).

CONCLUSIONS

In patients with SND and intra-atrial conduction delay, low IAS pacing was superior to RAA pacing in preventing progression to persistent or permanent AF.

CLINICAL TRIAL REGISTRATION

URL: http://www.clinicaltrials.gov. Unique identifier: NCT00239226.

Current concepts in pacing 2010-2011: the right and wrong way to pace

OPINION STATEMENT

Over five decades have passed since the first permanent cardiac pacemakers were introduced into clinical medicine. Evolving technology and falling costs have demanded adaptation to clinical practice and implantation trends and, with the advent of evidenced-based medicine, the specific roles and benefits of individual pacemaker technologies have never been so carefully scrutinized. Pacing mode choice continues to be a subject of great controversy, and there are great regional variations in practice. We believe that single chamber atrial pacing use (AAI/R) has become an anachronism that should generally be abandoned (obviously with rare exceptional cases) and be replaced by dual chamber pacemakers (DDD/R) equipped with modern pacing algorithms that minimize patient exposure to ventricular pacing. Also, in patients with atrioventricular (AV) block, randomized clinical trials have failed to show improvement in clinically relevant outcomes such as mortality, stroke, and heart failure, particularly in the elderly, which has led some to advocate that DDD/R devices should never be offered to elderly AV block patients. However, we believe that the elderly, like the young, come in many "shapes and sizes" and individualized medicine compels us to consider each pacemaker candidate as unique. Implanting DDD/R devices in chronologically older, yet physiologically younger, patients is justifiable and good medical practice. Where right ventricular (RV) pacing is necessary and unavoidable, physicians should consider routinely placing RV leads on the RV mid- or outflow tract septum because these location are as good, if not better, for patients than the current practice of RV apical lead placement. In patients with AV block and asymptomatic yet moderate to severely depressed left ventricular systolic function, primary cardiac resynchronization therapy (CRT) should be strongly considered. Compelling clinical trial evidence does not yet exist to indicate that CRT should be the standard of care in patients with AV block and intact left ventricular systolic function. Right ventricular septal lead placement remains a reasonable option.

Future easy and physiological cardiac pacing

The right atrial appendage (RAA) and right ventricular apex (RVA) have been widely considered as conventional sites for typical dual-chamber atrio-ventricular cardiac (DDD) pacing. Unfortunately conventional RAA pacing seems not to be able to prevent atrial fibrillation in DDD pacing for tachycardia-bradycardia syndrome, and the presence of a left bundle branch type of activation induced by RVA pacing can have negative effects. A new technology with active screw-in leads permits a more physiological atrial and right ventricular pacing. In this review, we highlight the positive effects of pacing of these new and easily selected sites. The septal atrial lead permits a shorter and more homogeneous atrial activation, allowing better prevention of paroxysmal atrial fibrillation. The para-Hisian pacing can be achieved in a simpler and more reliable way with respect to biventricular pacing and direct Hisian pacing. We await larger trials to consider this "easy and physiological pacing" as a first approach in patients who need a high frequency of pacing.

Safety and performance of a system specifically designed for selective site pacing

INTRODUCTION

In the right ventricle, selective site pacing (SSP) has been shown to avoid detrimental hemodynamic effects induced by right ventricular apical pacing and, in the right atrium, to prevent the onset of atrial fibrillation and to slow down disease progression. The purpose of our multicenter observational study was to describe the use of a transvenous 4-French catheter-delivered lead for SSP in the clinical practice of a large number of centers.

METHODS

We enrolled 574 patients in whom an implantable device was indicated. In all patients, SSP was achieved by using the Select Secure System™ (Medtronic Inc., Minneapolis, MN, USA).

RESULTS

In 570 patients, the lead was successfully implanted. In 125 patients, atrial SSP was performed: in 75 (60%) the lead was placed in the interatrial septum, in 31 (25%) in the coronary sinus ostium, and in 19 (15%) in the Bachman bundle. Ventricular SSP was undertaken in 138 patients: in 105 (76%) the high septal right ventricular outflow tract (RVOT) position was paced, in seven (5%) the high free-wall RVOT, in 25 (18%) the low septal RVOT, and in one (1%) the low free-wall RVOT. In the remaining 307 patients, the His zone was paced: in 87 (28%) patients, direct His-bundle pacing and in 220 (72%) patients para-hisian pacing was achieved. Adequate pacing parameters and a lead-related complication rate of 2.6% were recorded during a follow-up of 20 ± 10 months.

CONCLUSIONS

Our results demonstrated that many sites, in the right atrium, in the right ventricle, and in His-bundle region, can be paced using the Select Secure System™.

[Atrial pacing for prevention of atrial fibrillation. Influence of septal atrial pacing, atrial overdrive and AV-delay-optimization on atrial fibrillation burden]

BACKGROUND

Atrial overdrive and optimized interatrial conduction time can reduce atrial fibrillation (AF). Increased ventricular stimulation results in a higher incidence of atrial fibrillation.

PATIENTS AND METHODS

In 25 patients with paroxysmal AF, a dual-chamber pacemaker (Identity DR 5370, St. Jude Medical) was implanted. Atrial leads were placed randomly either septal (n=12) or conventional (n=13). Dynamic atrial overdrive (DAO) was activated and the AV delay was optimized according to Koglek's method. After 3, 6, 9, and 12 months automatic mode switch (AF burden) was analysed.

RESULTS

No difference in implantation parameters were observed between groups. Technical implantation parameters were in the normal range for both groups. After 12 months patients in the septal group had less AF burden (1% vs. 7%, p=0.06), and the total number of AF episodes was reduced.

CONCLUSION

Septal pacing is safe. In combination with DAO and AV delay optimization it may reduce the AF burden, which can be observed after 12 months.

Selective site pacing: rationale and practical application

Although it has become traditional to place permanent pacemaker leads at the right ventricular apex and right atrial appendage, pacing from these locations poorly mimics normal physiology. A growing evidence base shows that right ventricular apical pacing results in ventricular dyssynchrony and various adverse effects. Provocative data from early trials suggest that pacing from alternate sites in the right ventricle--His bundle pacing, para-Hisian pacing, septal right ventricular outflow tract pacing, and right ventricular midseptal pacing--may lead to improved results. Similarly, early data suggest that right atrial pacing near Bachmann's bundle may lead to superior outcomes when compared with pacing from the right atrial appendage. Several large-scale, randomized clinical trials are now under way to establish the future role of selective site pacing.

Diagnostic tools for atrial tachyarrhythmias in implantable pacemakers: a review of technical options and pitfalls

BACKGROUND

Correct pacemaker (PM) diagnosis of paroxysmal atrial tachyarrhythmias is crucial for their prevention and intervention with specific atrial pacing programmes. The PM mode switch to only ventricular pacing after detection of atrial tachyarrhythmias is often used as the parameter to quantify the 'burden' of atrial tachyarrhythmias.

OBJECTIVES

This review addresses potential errors in the detection and diagnosis of atrial tachyarrhythmias, sometimes resulting in incorrect mode switches. The interpretation of PM-stored data of patients with atrial tachyarrhythmias and the results of trials of pace prevention and intervention can be better appreciated with more insight into the technical options and pitfalls.

RESULTS

Literature and clinical experience demonstrate that the correctness of PM-derived diagnosis of atrial tachyarrhythmias depends on 1) the sensitivity setting to detect the onset and perpetuation of atrial tachyarrhythmias frequently characterised by variable and low-voltage signals, 2) the rejection of far-field R wave sensing by the atrial sense amplifier, 3) the facility for verification of mode switches by a high-quality intracardiac registration of the nonmodified atrial electrogram. The configuration of the atrial lead also contributes to the diagnostic performance of the PM.

CONCLUSION

Not only pacing algorithms and diverse technical PM features but also the atrial lead configuration are currently the limiting factors to the fully reliable, automated detection and diagnosis of atrial tachyarrhythmias. If these technical shortcomings can be improved, better signal processing will result. Then atrial pacing to prevent or suppress atrial tachyarrhythmias will be more justified. (Neth Heart J 2008;16:201-10.).

Characterization and comparison of Na+, K+ and Ca2+ currents between myocytes from human atrial right appendage and atrial septum

Atrial pacing to reduce paroxysmal atrial fibrillation recurrences is performed in right atrial appendage (RAA) traditionally. However, recent studies indicate that atrial septal (AS) pacing produces better outcomes than the RAA pacing. The underlying mechanisms for this difference remained unclear. One possible explanation for the superiority of AS pacing over RAA pacing is that the two different regions have distinct electrophysiological properties. The study was to explore whether there indeed exist regional differences of electrical activities between RAA and AS, using whole-cell patch clamp techniques. The results showed that RAA cells had longer action potential duration, more negative resting potential and greater amplitude of action potential, whereas AS cells had more rapid depolarizing velocity. The sodium current was significantly smaller in RAA cells, whereas the calcium current was markedly smaller in AS cells. The transient outward K(+) current was similar in both regions. The ultrarapid delayed rectifier K(+) current was greater in RAA than that in AS cells. The inward rectifier K(+) current was similar at potentials more negative to -60 mV in both regions. The results indicate that RAA and AS of patients with rheumatic heart disease possess distinct electrophysiological properties. These differences provided a rational explanation for the different efficacies in treating atrial fibrillation by atrial pacing in RAA and AS regions.