Atrial Lead Placement Research Articles

Time-dependent improvements in pacing thresholds with lumenless leads placed in the right atrium

BACKGROUNDTraditional pacemaker implantation often poses risks, such as perforation when positioning atrial leads at the right atrial appendage (RAA). Recent advancements in delivery catheters have enabled atrial lead placement in the right atrial septum, potentially mitigating RAA-related complications. However, the performance of lumenless leads in this context remains unclear. OBJECTIVETo assess the performance of lumenless leads as atrial leads. METHODSForty-four consecutive patients undergoing pacemaker implantation with lumenless atrial leads were enrolled. Lead implantation was performed using a 3830 SelectSecure lead and C315HIS-sheath. Pacing parameters were collected immediately after screwing, 3 and 5 min later, at the end of the procedure, and at every 6-month follow-up. RESULTSLead parameters including P-wave, pacing threshold, and impedance significantly improved over time. The threshold levels from 2.00 ± 0.72 V/0.4 msec immediately after screwing to 1.45 ± 0.57 V/0.4 msec at 5 min, 0.95 ± 0.38 V/0.4 msec at the end of the procedure, and 0.78 ± 0.39 V/0.4 msec at discharge. Initially, threshold levels were >2.5 V/0.4 msec in 15 cases; however, they decreased to <2 V/0.4 msec by the end of the procedure. At discharge, 13 of the 15 cases showed a threshold decrease to <1 V/0.4 msec. During follow-up, no threshold increase (>1 V), lead revision, or battery depletion was observed. CONCLUSIONLumenless lead placement in the right atrium results in threshold decrease over time. Therefore, allowing a waiting period instead of immediately repositioning the lead may be more effective when thresholds are high after screwing.

Mapping-guided atrial lead placement determines optimal conduction across Bachmann's bundle: a rationale for patient-tailored pacing therapy.

Conventional right atrial appendage (RAA) pacing is associated with increased atrial activation time resulting in higher incidences of atrial tachyarrhythmia. Optimal pacing sites ideally shorten inter-atrial conduction delay, thereby decreasing atrial excitation time. We therefore examined the impact of programmed electrical stimulation (PES) from the right atrium (RA) and left atrium (LA) on the electrophysiological properties of Bachmann's bundle (BB). High-resolution epicardial mapping of BB was performed during sinus rhythm (SR) and PES in 34 patients undergoing cardiac surgery. Programmed electrical stimulation was performed from the RAA, junction of the RA with inferior caval vein (LRA), and left atrial appendage (LAA). Pacing from either the RAA or LAA resulted in, respectively, right- and left-sided conduction across BB. However, during LRA pacing in most patients (n = 15), activation started in the centre of BB. The total activation time (TAT) of BB during RAA pacing [63 (55-78) ms] was similar to that of SR [61 (52-68) ms, P = 0.464], while it decreased during LRA [45 (39-62) ms, P = 0.003] and increased during LAA pacing [67 (61-75) ms, P = 0.009]. Reduction of both conduction disorders and TAT was most often achieved during LRA pacing (N = 13), especially in patients who already had a higher amount of conduction disorders during SR [9.8 (7.3-12.3) vs. 4.5 (3.5-6.6)%, P < 0.001]. Pacing from the LRA results in a remarkable decrease of TAT compared with pacing from the LAA or RAA. As the most optimal pacing site varies between patients, individualized positioning of the atrial pacing lead guided by mapping of BB may be one of the new frontiers for atrial pacing.

Almost zero-fluoroscopy LBBP-procedure using a 3D-mapping system

Abstract Introduction Cardiac device therapy has recently been extended by the option of Conduction System Pacing, CSP (HIS Bundle Pacing, HBP; Left Bundle Branch Area Pacing, LBBAP). Similar to cardiac resynchronization therapy (CRT), complex procedures can result in long fluoroscopy-duration and considerable radiation exposure for the patient and the implanting team. According to the principle ALARA (As Low As Reasonably Achievable), measures should be taken to reduce radiation, wherever possible. We report the almost fluoroscopy-free implantation of a LBBAP-system using a 3D electroanatomical mapping system (EAMS). The patient was indicated for a pace &amp; ablate concept due to recurrent, highly symptomatic, persistent atrial fibrillation (AF), a history of mitral valve repair and a severely dilated left atrium. ESC guidelines suggest choosing a RV-lead (indication IIa), alternatively either a CRT system or HBP (both IIb). LBBAP as new option for physiological pacing was chosen in this patient because it usually provides excellent stimulation thresholds and the lead – in contrast to HBP – is distant from Koch's triangle, so that AV-nodal-ablation can be performed safely. Methods Surgery was performed under deep sedation. After accessing the cephalic vein, a quick 3D map of relevant structures was acquired (right atrium; coronary sinus; HIS; interventricular septum, IVS). Then a preformed sheath and a stylet-driven pacemaker-lead were advanced. The lead-tip was visualized within the EAMS and maneuvered without fluoroscopy. After approaching the proximal IVS, the implantation site was confirmed by unipolar stimulation and the lead was advanced into the IVS under close monitoring of impedance and signals. Final position was confirmed by sheath-angiography [Fig. 1]. Results During lead fixation, LBBAP-typical ECG-changes (progression to rSR morphology, fixation beats) could be observed. A left bundle branch potential (poLBB) could be documented. The left ventricular activation time (LVAT) as a marker of rapid LV-excitation was shortened from 108 ms to 68 ms. Thresholds for non-selective and selective LBBP were 3 V @ 1 ms and 0.7 V @ 0.4 ms, with a sensing of 8.7 mV, impedance of 643 ohms and a paced QRS-width of 112 ms [Fig. 2]. An atrial lead was added (history of intermittent sinus rhythm) and a dual-chamber pacemaker was connected. Fluoroscopy was required for lead fixation into the IVS, atrial lead placement as well as for sheath angiography and lead length-optimization. Total fluoroscopy time was 1.13 minutes with a radiation dose of 45.04 μGy m2, procedure time 64 minutes. AVN total ablation was performed the following day without complications. Conclusions CSP using a 3D mapping system is simple, facilitates understanding of important anatomical structures and helps to reduce the required radiation dose to a necessary minimum. In individual cases, procedures requiring almost zero-fluoroscopy are possible. Funding Acknowledgement Type of funding sources: None.

Benefit of right inferior pacing on conduction across Bachmanns Bundle

Abstract Background Bachmann's Bundle (BB) is the main preferential route for interatrial conduction and plays an important role in initiation and perpetuation of atrial tachyarrhythmia such as atrial fibrillation (AF). Especially in patients with inter- and intra-atrial conduction disorders, the conventional site for placement of right atrial (RA) pacing lead in the RA appendage (RAA) has been questioned as it results in a higher incidence of AF. However, it remains unknown how pacing from various sites affects conduction at BB. Purpose To examine the impact of programmed stimulation from the left and right atrium on activation and electrophysiological features of BB. Methods Intra-operative high-resolution epicardial mapping of BB was performed during sinus rhythm (SR) and programmed stimulation in 32 patients (29 male, 65±10 years). Programmed stimulation included a fixed rate sequence of average SR cycle length minus 50 ms provided from the RAA, junction of the RA with inferior caval vein (RAinf) and left atrial appendage (LAA). Electrophysiological features included unipolar voltage, conduction velocity, potential type (single, short/long double and fractionated) and conduction delay/block (CDCB). Results The average cycle length during SR was 962 [869–1085] ms. Pacing from RAA resulted in comparable activation patterns as during SR. As expected, pacing from LAA resulted in left-to-right conduction across BB. However, during pacing from RAinf in most patients activation started in the centre of BB. Compared to SR, the least amount of differences in electrophysiological features was found during pacing from the RAA, followed by pacing from RAinf and LAA. Unipolar voltages, conduction velocity and potential type distribution were similar. However, during pacing from RAinf, total activation time decreased compared to SR (44 [38–62] ms vs 60 [51–67] ms, P=0.012), while total activation time increased by pacing from LAA (66 [60–72] ms, P=0.020). The total activation time during pacing from RAinf was lower compared to LAA (P&amp;lt;0.001) and RAA pacing (P=0.001). During pacing from LAA, the amount of CDCB increased compared to SR (6.6 [4.1–9.9] % vs 8.7 [5.6–12.8] %, P=0.009), while there were no differences in CDCB between SR and pacing from both RAA and RAinf. Reduction of CDCB was most often achieved during pacing from RAinf (12 patients), especially in patients who already had a higher amount of CDCB during SR (8.0 [7.3–11.2] % vs 4.3 [3.0–5.9] %, P&amp;lt;0.001). Reduction of both CDCB and total activation time was achieved in 10 patients by pacing from RAinf, while only 6 patients benefitted from RAA pacing. These patients had similar amount of conduction disorders. Conclusions Pacing from the inferior RA results in a remarkable decrease of total activation time and conduction disorders compared to pacing from the LAA or RAA. As specific patients may benefit more from inferior RA pacing, locations for pacing lead placement should be individualized. Funding Acknowledgement Type of funding sources: None.

Conduction system pacing in paediatric patients: a single centre experience

Abstract Funding Acknowledgements Type of funding sources: None. Background Paediatric patients with conduction abnormalities are generally exposed to life-long dyssynchronous pacing from a very early age. Thus, preservation of cardiac function during chronic ventricular pacing is important. Conduction system pacing (CSP) with His bundle pacing (HBP) or left bundle branch pacing (LBBP) is an alternative method to standard right ventricular (RV) pacing that may preserve physiological ventricular activation and avoid potential pacing-induced cardiomyopathy (1). However, data on feasibility and safety of various CSP approaches in paediatric patients with or without congenital heart disease (CHD) is scarce and mainly relies on case studies (2-4). Purpose To assess feasibility and outcomes of different CSP techniques in paediatric patients. Methods Consecutive paediatric patients in whom CSP was attempted in our centre between November 2019 and December 2021 were analysed. Acute implant success rate, complications, fluoroscopy times, and CSP pacing parameters during follow-up were assessed. To reduce radiation exposure, minimal fluoroscopy technique with three-dimensional (3D) electro-anatomical mapping (EAM) was also used in some cases. Geometry of right atrium and RV, along with mapping of His signal for HBP and potential LBBP sites in the RV septum were created using a decapolar catheter from the right femoral vein. Once relevant anatomy was obtained, HBP or LBBP was attempted using commercially available CSP tools. The pacing lead tip was visualised using the 3D EAM system. Transient fluoroscopy was used only for perpendicular placement of the sheath to the RV septum during LBBP, sheath removal, lead loop assessment to allow linear growth, and atrial lead placement. Results Six patients (100% female, age 9.3 ± 3.9 years, weight 41.8 ± 22.9 kg, baseline QRS 111.5 ± 6.3ms, CHD 50%, previous device 33%) with congenital complete AV block received CSP. One patient received HBP and 5 LBBP. The procedure was acutely successful in all patients (100%), pacing thresholds were low (0.56 ± 0.18V at 0.5ms) and there were no perioperative complications. During mean follow-up of 11.8 ± 7.8 months pacing parameters remained stable. However, significant rise of the pacing threshold (&amp;gt; 2.5V) was registered in the HBP patient, in whom lead revision was performed. Three-dimensional EAM was utilised in 3 patients (1 HBP, 2 LBBP). The use of minimal fluoroscopy technique with 3D EAM reduced fluoroscopy time (4.0, 3.2, 4.5 min vs. 9.5, 11.0, 8.0 min) without increasing procedural time (80, 70, 50 min vs. 110, 60, 75 min) compared to standard fluoroscopy technique. Conclusion Conduction system pacing is feasible and safe in paediatric patients with or without CHD. Additional utilisation of 3D EAM could reduce radiation exposure, without increasing procedural time. Future long-term studies should be considered to provide the ground for wider clinical adoption of CSP in paediatric population.

PO-708-04 HIGH DENSITY ELECTROANATOMICAL MAPPING FOR TARGETED PACING LEAD PLACEMENT IN PATIENTS WITH ATRIAL MYOPATHY

Atrial myopathy can occur secondary to surgical scaring and fibrosis, particularly in patients with congenital heart disease (CHD). Atrial lead placement in these patients can be challenging as intra/inter-atrial conduction may be segmented and with variable atrioventricular (AV) conduction. The feasibility of electroanatomical mapping to facilitate pacing lead placement has been under reported.

Clinical impact of Bachmann's bundle pacing defined by electrocardiographic criteria on atrial arrhythmia outcomes.

Evaluate whether Bachmann's bundle pacing (BBp) defined by electrocardiographic (ECG) criteria is associated with less atrial fibrillation/tachycardia (AF/AT) compared with anatomically defined right atrial septal pacing (RASp) and right atrial appendage pacing (RAAp). This is a retrospective study comparing BBp with non-specific RASp and RAAp on new incidence, burden, and recurrence of AF/AT. We included patients who underwent atrial lead placement between 2006 and 2019 and received > 20% atrial pacing. BBp was defined by paced P-wave morphology and fluoroscopic lead position. Compared with RASp (n = 107) and RAAp (n = 108), AF/AT burden was lower in the BBp (n = 134) group by repeated measures ANOVA (P < 0.001). Over 2-year follow-up, AF/AT burden increased in the RASp (P < 0.01) and RAAp (P < 0.01) groups but did not significantly change in the BBp group (P = 0.91). Atrial arrhythmia burden was lower in the BBp group than the RASp and RAAp groups at 12-15, 18-21, and 24-27 months (P < 0.05) after pacemaker placement. Risk of AF/AT recurrence was lower in BBp than RASp (HR 0.43; P < 0.01) and RAAp patients (HR 0.29, P < 0.01). Risk of de novo AF/AT was also lower in BBp than in RASp (OR 0.12; P < 0.01) and RAAp patients (OR 0.20, P < 0.01). Bachmann's bundle pacing defined using P-wave criteria was associated with decreased atrial arrhythmia burden, recurrence, and de novo incidence compared with right atrial septal pacing and right atrial appendage pacing.

Right-Sided Permanent Pacemaker Implantation in Patients with Persistent Left Superior Vena Cava with Absent Right Superior Vena Cava: 3-Case Series, Technique and Discussion

Persistent left superior vena cava (PLSVC) is the most common variant of abnormal venous return to the heart. While usually asymptomatic, it is known to complicate transvenous cardiac procedures, such as implantation of cardiac electronic devices and ablations. PLSVC can present with or without the concomitant absence of right superior vena cava (RSVC). Depending on the operator's preference, implantation of permanent cardiac pacemakers (PPMs) may be performed from the left or right side. As most often the PLSVC is only identified at the time of intervention, it follows that the variant with the absence of RSVC can be diagnosed in practice only when implanting from the right side. For this reason, the true prevalence of this variant is largely unknown because most published cases of cardiac device implantations in patients with PLSVC have been performed from the left side. We present a short 3-case series of PPM implantations in a tertiary center from the right side in patients with PLSVC and absent RSVC. We found that the use of a standard curve for ventricular lead septal placement and a wide C-curve for right atrial lead placement in these patients was a feasible technique with good outcomes.

A minimally invasive approach for atrial and ventricular sew-on epicardial lead placement.

Permanent pacemaker (PPM) placement in pediatric patients is rare. Indications for permanent pacing in children include congenital and postsurgical atrioventricular block, symptomatic sick sinus syndrome, and select neuromuscular disorders.1,2 PPMs are traditionally placed using transvenous systems in adults and larger children. However, young children are often not suitable candidates due to their size or history of congenital cardiac surgery.

Electrograms guided his bundle pacing implant: moving from radiology to electrical signals

Abstract Background The standard technique to His Bundle Pacing (HBP) based on a fluoroscopic approach might be challenging and fluoro consuming. The electrical signals could lead to a precise and rapid lead implant, thus reducing the fluoroscopy time (FT) and X-ray dose. Objective To evaluate the feasibility, efficacy and safety of the electrogram-guided technique to obtain His Bundle pacing (HBP) with minimal or no fluoroscopy use. Methods Between October and December 2018, 41 consecutive patients with indication for pacing underwent HBP with the electrogram-guided approach. Results Successful HBP was obtained in 39/41 (95%) pts, which is the study population (mean age 78±10 years). S-HBP and NS-HBP were achieved in 23 (59%) and 16 (41%) pts, respectively. Final HBP lead position was achieved in 31/39 (79.4%) pts with zero fluoroscopy, only guided by the electrical signals. In the remaining 8 pts a minimal dose of fluoro (mean 8 sec) has been required to locate the His. Fluoroscopy has been routinely used to remove the sheath and to ensure the slack. The atrial lead has been implanted in a standard fashion. No difference was observed in the FT for HBP lead placement in patients with S-HBP and NS-HBP (mean 8.1±25 sec vs 7.5±20 sec, p=0.8; median value 0 sec vs 0 sec). Moreover, no significant differences were observed in the FT needed for the entire procedure, total Dose Area Product (DAP) and total procedural time among both S-HBP and NS-HBP. The His lead dislodgement occurred in 1 (2.6%) patient one day after the procedure. Conclusion HBP could be performed safely and efficiently using the electrograms, with minimal or no fluoroscopy. Fluoroscopy was required during sheath removal and atrial lead placement. Funding Acknowledgement Type of funding source: None

Electrogram-only guided approach to His bundle pacing with minimal fluoroscopy: A single-center experience.

His bundle pacing (HBP) is the most physiological pacing. The standard technique based on fluoroscopic approach might be challenging and fluoro consuming. Targeting the His guided exclusively by the electrical signals could enable a precise lead implant, thus reducing fluoroscopy time (FT) and X-ray dose, desirable both for patients and operators. The aim of the study is to evaluate the feasibility, efficacy, and safety both acutely and at 30 days of the electrogram (EGM)-guided HBP with minimal or no fluoroscopy. Between October and December 2018, 41 consecutive patients underwent EGM-guided HBP. Successful HBP was obtained in 39 (95%) patients, (30 males, 78 ± 10 years). Selective HBP (S-HBP) was achieved in 23 (59%), nonselective HBP (NS-HBP) in 16 (41%) patients. The final HBP lead position was reached in 31 (79.4%) patients without fluoroscopy, only guided by electrical signals. In eight patients a minimal fluoroscopy (mean, 8 seconds) has been required. The sheath's cutting and the slack of the lead were routinely performed under fluoroscopy. No difference was observed in FT for HBP lead placement in S-HBP and NS-HBP (mean, 8.1 ± 25 vs 7.5 ± 20 seconds, P = .8; median value 0 vs 0 seconds). No differences were observed in FT for the entire procedure, total dose area product and total procedural time in S-HBP and NS-HBP. Lead dislodgement occurred in one (2.6%) patient 1 day after the procedure. HBP could be performed safely and efficiently using the EGMs, with minimal or no fluoroscopy. Fluoroscopy was required during sheath removal and atrial lead placement.

Assessment of Signal Quality Algorithms in Distributed Systems

We describe an unusual cause of intermittent rapid ventricular paced rhythm in a patient implanted with a dual chamber pacemaker due to sinus node dysfunction after heart transplantation. During implantation of the pacemaker lead measurements were reported normal, atrial sensing was not documented because of sinus arrest. After implantation the patient complained about intermittent palpitations. Via pacemaker interrogation we could demonstrate electrical isolation of the atrial lead, which was implanted in the donor's atrial myocardium. This led to intermittent pacemaker related tachycardia and AV-dissociation. This case report highlights the difficulty of atrial lead placement in heart transplanted patients using the biatrial surgical technique.

When two hearts do not beat as one – An unusual cause of pacemaker related tachycardia

We describe an unusual cause of intermittent rapid ventricular paced rhythm in a patient implanted with a dual chamber pacemaker due to sinus node dysfunction after heart transplantation. During implantation of the pacemaker lead measurements were reported normal, atrial sensing was not documented because of sinus arrest. After implantation the patient complained about intermittent palpitations. Via pacemaker interrogation we could demonstrate electrical isolation of the atrial lead, which was implanted in the donor's atrial myocardium. This led to intermittent pacemaker related tachycardia and AV-dissociation. This case report highlights the difficulty of atrial lead placement in heart transplanted patients using the biatrial surgical technique.

An irregular approach of right atrial lead placement in a patient with persistent left superior vena cava and concomitant agenesis of the right-sided superior vena cava

Persistent left superior vena cava (PLSVC) is the most common venous anomaly of the thorax. It could lead to catheter malplacement and even vascular injuries. We describe an unusual way to deliver a right atrial (RA) endocardial pacing lead in a 61-year-old female with a PLSVC concomitant agenesis of the right-sided SVC. After failed attempts with the standard procedure, we placed the RA lead tip in the PLSVC near the right auricle. The pacemaker worked well after one and 17 months of follow-up. We conclude that when placement of the RA lead fails, the PLSVC near the right auricle could be a next choice in the RA lead placement in patients with PLSVC concomitant agenesis of the right-sided SVC.

20 Appropriate Use of Single-Chamber Ventricular Pacing in a Large DGH – Are we Selecting the Right Patients?

Introduction In the UK, significant numbers of patients are treated with single-chamber ventricular pacing (VVI/R) for bradycardia indications, despite being in sinus rhythm. We evaluated the profile and outcomes of such patients at our institution. We demonstrate that when this mode of pacing is selectively chosen it is effective and well tolerated. Methods Electronic records at Ipswich Hospital NHS Trust from January 2010 to October 2013 were reviewed to identify the total number of new implants, and the underlying rhythm in those receiving VVI/Rs. Records of patients not in chronic atrial fibrillation (AF) were reviewed further to identify reasons for VVI/R implant, whether they developed AF, experienced symptoms of pacemaker syndrome or required an upgrade. Results Table 1 outlines the number and type of new pacemakers implanted, as well as the compliance with NICE guidelines. The three patients falling outside of NICE guidelines were intended to have DDD/R implants but operators were unable to position an atrial lead successfully. Of the remaining 38 patients in sinus rhythm, the choice of pacing mode was influenced by a combination of frailty, limited mobility, age and comorbidities (see Figure 1). The most common indication was atrioventricular block, the mean patient age was 91 (range 80 to 101), and the mean follow up period was 10 months (max. 43) with an expected drop out due to mortality. In those selected for VVI/R there were two new instances of paroxysmal AF and one patient experienced dizziness, which may have been attributable to her pacemaker (one possible mild pacemaker syndrome). In those with failed atrial lead placement, one patient with a prior history of paroxysmal AF developed persistent AF. No patients required a pacemaker upgrade (see Table 2). Conclusions In our institution, 14.6% of the patients treated with VVI/Rs were in sinus rhythm, which extrapolates to approximately 1,500 patients across England and Wales each year. 70% of the patients we selected for such a treatment strategy were over 90 years of age, and all had multiple additional influential factors. We demonstrate a low incidence of further symptoms, pacemaker syndrome and atrial fibrillation. In appropriately selected patients, simple VVI pacing is effective and well tolerated.

Atrial lead placement at the lower atrial septum: a potential strategy to reduce unnecessary right ventricular pacing

Right ventricular (RV) pacing has been shown to be potentially detrimental to left ventricular function. In conventional dual-chamber pacing the position of the atrial lead could influence duration of the atrio-ventricular (AV) intervals, which is one of the variables that could be associated with an increased percentage of RV pacing. We wanted to see if lead placement at selected atrial septal sites could reduce AV intervals in patients receiving a dual-chamber pacemaker or implantable cardioverter defibrillator. This was a prospective, acute, randomized single centre study that enrolled 57 patients. The atrial lead was placed in both the right atrial appendage (RAA) and the lower atrial septum (LAS) in each patient in random order. The P-wave durations, PR intervals, A sense-V sense (As-Vs), and A pace-V sense (Ap-Vs) intervals were measured at both atrial lead locations in each patient during device implant. The P-wave durations during sinus rhythm (SR), RAA pacing, and LAS pacing were 113 ± 19, 144 ± 27, and 84 ± 12 ms (RAA vs. LAS, P < 0.001), respectively. The PR intervals during SR, RAA pacing, and LAS pacing were 195 ± 47, 230 ± 61, and 167 ± 44 ms (RAA vs. LAS, P < 0.001), respectively. The As-Vs interval was 31% shorter in LAS pacing than in RAA pacing (134 ± 44 ms vs. 194 ± 52 ms, P < 0.001). The Ap-Vs interval was 24% shorter during LAS pacing than during RAA pacing (195 ± 45 ms vs. 257 ± 63 ms, P < 0.001). When compared with RAA pacing, LAS pacing was associated with a shorter P wave duration, PR interval, As-Vs, and Ap-Vs intervals. The potential long-term impact of the strategy of pacing from LAS in reducing unnecessary RV pacing needs to be explored in future studies.

Abstract 5891: Incidence and Prognostic impact of Spontaneous Conversion to Sinus Rhythm in Patients with Permanent Atrial Fibrillation treated with Cardiac Resynchronization Devices

INTRODUCTION : Anecdotal reports of spontaneous resumption to stable sinus rhythm (SR) of heart failure (HF) patients with permanent atrial fibrillation (PeAF) after cardiac resynchronization therapy (CRT) have been reported. If this incidence is appreciable, additional interventions may be indicated including placement of an atrial lead. METHODS: We retrospectively reviewed patients with PeAF who received CRT devices; standard CRT indications were applied. PeAF was defined as AF present for more than 1 year refractory to any rhythm control efforts. Rhythm was sampled at each follow-up visit, generally every 6 months. RESULTS: In total, 345 patients with PeAF were implanted with CRT devices (CRT-D 48%); mean age was 70±9 yrs and mostly male gender (83%). Ischemic HF was present in 154 patients (45%). Mean NYHA class was 3,1±0,5, 6MWT distance 308±113 meters, QRS 156±39 ms, LVEF 28±7%, and LVEDD 65±9 mm. PeAF had been present for 2,1 ± 1.6 years. Over a follow-up of 29 ± 24 months, 34 (9,9%) patients spontaneously reverted to stable (&gt; 3 months) SR. Most SR resumptions occurred within the 1 st year after CRT (28/34, 82%), but also occured even after 5 years (2/34). Mortality rate was 20,4 for PeAF compared to 2,5 per 100 patients-year for SR resumption (Log Rank p=0.004, see figure ) (HR= 0.13, 95% CI 0.031–0.512, p&lt; 0.0001). CONCLUSION : Spontaneous resumption to SR in HF patients with PeAF treated with CRT was observed in roughly 10% of cases, generally within 1 year from implant. SR resumption was associated with a significant 87% reduction of total mortality. Identification of predictors for return of SR may be useful to guide routine atrial lead placement in some patients.

Effect of Atrial Lead Position on Atrial Automatic Capture Verification

Optimizing atrial automatic capture verification based on atrial-evoked response (AER) detection requires maximizing the signal artifact ratio (SAR), that is, AER to stimulation artifact (ART). This study evaluated the effect of bipolar atrial lead position on sensed AER, ART, and SAR. A custom-made external research system (INSIGNIA(AC), Boston Scientific Corp. St Paul, MN, USA) was used to perform an automatic voltage step-down atrial pacing protocol at three different right atrial lead positions (A-appendage, L-lateral wall, and S-septal wall) in each studied patient. The atrial pacing and the AER sensing configurations were independent. The pacing was unipolar in an A(tip)-Can configuration while sensing was in A(ring)-I(ndiff). Data from 16 patients (mean age 71.1 +/- 9.6 years) and six-lead models from five different manufacturers were analyzed. Study results show that with all lead types, the atrial lead placement had no significant effect on AER(min), ART(max), and SAR(min) and only one patient had an SAR that was not sufficient to support successful automatic capture verification at all tested atrial pacing sites. The atrial pacing site has minimal effect on AER sensing when using an independent pace/sense configuration. The leads placed at all tested sites were found to have the parameters sufficient to support the atrial automatic capture verification in all but one patient.

Electroanatomical Mapping in Partial Atrial Standstill for Visualization of Atrial Viability and a Suitable Pacing Site

Partial atrial standstill is characterized by the failure of atrial activity either spontaneously or in response to electrical stimulation in restricted site of atria. In this case with bradycardia, atrial standstill was restricted to the lateral and posterior right atrium. The markedly prolonged intraatrial conduction delay was observed in the superior to septal region of the right atrium. The electroanatomical mapping was successfully utilized to estimate atrial activity and to find a suitable site for atrial lead placement. The electroanatomical mapping may become an innovated strategy to estimate atrial electrical status in partial atrial standstill.

The role of pacing mode in the development of atrial fibrillation

Asynchronous ventricular pacing has been shown to increase the risk of development of atrial fibrillation (AF) because of various mechanisms: retrograde atrioventricular (AV) conduction with increase in atrial pressure causing acute atrial stretch and reverse flow in the pulmonary veins, mitral regurgitation, reduced coronary blood flow, adverse neuroendocrine reactions, etc. Dual-chamber pacing preserves atrioventricular synchrony. However, in randomized multicentre trials comparing VVI(R) with DDD(R) pacing, AF is only slightly less frequent in the dual-chamber mode. This is most likely due to unnecessary ventricular pacing, which is frequent in dual-chamber pacing. At nominal values, dual-chamber devices usually do not permit intrinsic AV conduction but promote delivery of the ventricular stimulus at an inappropriate time in an inappropriate place. Programming of long AV delays facilitates spontaneous AV conduction but usually cannot completely avoid unnecessary ventricular pacing and causes other problems in the dual-chamber mode. Atrial septal lead placement can improve left-sided AV synchrony and promote spontaneous AV conduction. Programming of the AAI(R) mode is superior to the dual-chamber mode but cannot be used if AV conduction is impaired intermittently or permanently. Therefore, dedicated algorithms enhancing spontaneous AV conduction in the dual-chamber mode are desirable for a large proportion of pacemaker patients.