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Key Clinical Message This case is a reminder not to overlook rare causes of electrolyte shifts, which may cause reversible changes in pacemaker pacing thresholds.

Introduction Parasystole refers to an ectopic pacemaker that discharges with a constant rate competing with the primary pacemaker of the heart the sinus node. Parasystolic pacemakers have been described in the atrium, atrioventricular node, His bundle, and in the ventricle. Ventricular parasystole usually carries a benign prognosis, but there are a few reports of ventricular tachyarrhythmia initiated by parasystolic beats. Case presentation We present a case of a 15-year-old otherwise healthy teenager with recurrent most likely arrhythmic syncope who was diagnosed with ventricular parasystole from the left posterior fascicle. After exclusion of structural and primary electrical heart disease, the patient was deemed at increased risk of parasystole-induced tachyarrhythmia, and thus catheter ablation of the ectopic focus was performed. Since catheter ablation the patient continues to be free of any symptoms. Discussion This report highlights the potential risks of parasystole in context of recurrent syncope and reviews the available literature on parasystole and ventricular tachyarrhythmia.

Background The impact of right ventricular (RV) lead location on clinical end points in patients undergoing cardiac resynchronization therapy (CRT) is unclear. We evaluated the impact of different RV lead locations on clinical outcome in CRT patients enrolled in the Septal Positioning of ventricular implantable cardioverter-defibrillator (ICD) Electrodes (SPICE) trial, which randomized recipients of implantable cardioverter defibrillators to apical versus midseptal RV lead positioning. Methods Ninety-eight CRT recipients were included in the multicenter SPICE trial and followed for 12 months: Fifty-three patients were randomized to receive an apical (A) and 45 to receive a midseptal (S) lead position. We compared echocardiographical and electrocardiographical parameters and outcome. Results Echocardiographic response with respect to improvement of left ventricular ejection fraction (A: +15.8 ± 14.6%, S: +9.7 ± 12.6%, P = 0.156) and reduction of left ventricular end-diastolic diameter (A: −4.2 ± 10.7 mm, S: −7.5 ± 10.7 mm, P = 0.141) was comparable in apical and midseptal groups. Paced QRS width neither differed at prehospital discharge (A: 129 ± 21 ms, S: 135 ± 21 ms, P = 0.133) nor at 12-month follow-up (A: 131 ± 23 ms, S: 134 ± 28 ms, P = 0.620). No differences were found with respect to the risk of ventricular tachyarrhythmia or ICD therapy. Septal RV lead position, however, was associated with a significant longer time to a first heart failure event (P = 0.040) and a longer survival time (P = 0.019). Conclusions In CRT recipients, midseptal RV lead position was not superior with respect to improvement of echocardiographic parameters or paced QRS width. It did not predispose to ventricular arrhythmias or ICD therapy. The finding that midseptal lead position was associated with a longer time to first heart failure event and a longer survival time deserves further investigation.

Concerning rates of pulmonary vein (PV) stenosis were reported following PV isolation (PVI) with a circular pulmonary vein ablation catheter (PVAC). As this may depend on intraprocedural imaging, we evaluated the incidence of PV stenosis in patients undergoing PVAC-PVI with continuous surveillance by intracardiac echocardiography (ICE). Multi-slice computed tomography was performed before and 3 months after PVAC-PVI with continuous ICE surveillance in 30 patients (37 % male, 65 ± 9 years). PV areas at two levels (ostial and 1 cm distally) and left atrial (LA) volumes were measured. PV area/LA volume ratio was calculated to correct for reverse LA remodelling. PV stenosis was classified as mild (25–50 %), moderate (50–75 %) and severe (>75 %). One hundred sixteen veins were isolated with PVAC with additional touch-up ablation in one patient. One patient was excluded from analysis for untriggered CT acquisition. Left atrial volume decreased from 109.1 ± 30.9 cm3 before to 98.4 ± 34.4 cm3 after ablation (p

Aims Right ventricular (RV) septum is a non-apical site targeted during lead implantation. Electrocardiographic (ECG) recognition of mid-septal lead location is challenging. The aim of the study is to determine ECG correlates of RV mid-septal pacing. Methods and results The present study is a pre-specified analysis of a prospective, multicenter study, which randomized recipients of an implantable cardioverter defibrillator to an apical vs. mid-septal RV lead positioning. Following implantation, a 12-lead ECG was recorded during intrinsic rhythm and RV pacing. In total, 227 patients, 121 in the apical group (76.9% males, 67.1 ± 11.3 years) and 106 in the mid-septal group (82.1% males, age 64.7 ± 12.7 years) were included. Apically as compared with septally paced patients had significantly longer paced QRS duration (177.0 ± 25.0 vs. 170.4 ± 21.7, respectively, P = 0.03) and significantly more leftward paced QRS axis (−71.6 ± 33.3° vs. 9.4 ± 86.5°, respectively, P < 0.001). A significantly higher proportion of patients in the mid-septal as compared with the apical group displayed predominantly positive QRS in lead V6 (62.3 vs. 4.1%, P < 0.001), predominantly positive QRS in any of the inferior leads (53.8 vs. 4.1%, P < 0.001), and a QR pattern in lead aVL (53.3 vs. 3.3%, P < 0.001). These ECG correlates were incorporated in a stepwise algorithm with total sensitivity of 87% and specificity of 90% for the identification of a mid-septal lead location. Conclusion A mid-septal lead location may be identified using a simple stepwise algorithm, based on the presence of positive QRS in lead V6, positive QRS in any of the inferior leads, and a QR pattern in lead aVL.

Electrocardiographic (ECG) identification of prior myocardial infarction (MI) during right ventricular (RV) pacing is of clinical importance. Proposed ECG criteria have been evaluated only during apical pacing. We evaluated the effect of pacing site on the predictive performance of ECG signs of prior MI.The present study is a secondary analysis of a prospective, multicenter study which randomized recipients of an implantable cardioverter defibrillator to an apical versus septal RV lead positioning. ECGs of patients with or without prior MI were analyzed for the presence of the following criteria: Cabrera sign, Chapman sign, QR pattern in leads I, aVL, V5 or V6, QR in inferior leads and notching in the descending slope of the QRS complex in inferior leads.The MI group included 89 patients (55.1% apically paced), while 99 patients had no prior MI (50.5% apically paced). In the total population, the Cabrera sign presented the highest specificity (97%) and diagnostic accuracy (62.2%), with a sensitivity of 23.6%. The Cabrera sign was the only significant predictor of a prior MI [OR=9.9, (95%CI:2.8-34.5), p0.001], among all ECG markers. Pacing site did not significantly influence the sensitivity and specificity of the Cabrera sign for detection of prior MI.In our study, the Cabrera sign was the only ECG marker that predicted the presence of prior MI during ventricular paced rhythm. Septal RV lead positioning did not affect the predictive performance of the Cabrera sign.

Background Detrimental effects of right ventricular (RV) apical pacing have directed the interest toward alternative pacing sites such as the RV mid-septum. As safety data are scarce for implantable cardioverter defibrillator (ICD) recipients the study aims to evaluate ICD lead performance in the mid-septal position. Methods and results A total of 299 ICD recipients (79% male, aged 65.2±12.1years, 83% primary prevention of sudden cardiac death) were randomized to receive the RV ICD electrode either in a mid-septal (n=145) or apical (n=154) location. Event-free survival was evaluated at 3 (primary endpoint) and 12months (secondary endpoint). Events included a composite of lead revision, suboptimal right ventricular electrode performance (including defibrillation thresholds (DFT)>25J) or lead position not in accordance with randomized location. Event-free survival at 3 (12) months was observed in 80.6% (72.3%) of patients randomized to a mid-septal and in 82.2% (72.1%) of patients randomized to an apical lead position, p=0.726 (p=0.969). Pre-defined margins for non-inferiority were not reached at 3 or 12months. High DFT was found in 7 patients (5.0%) of the mid-septal and in 3 (2.2%) patients of the apical group (p=0.209). Conclusion In ICD recipients electrode positioning to the RV mid-septum or the RV apex results in slightly different rates concerning the survival free of lead revision, suboptimal right ventricular electrode performance or non-randomized lead position. Non-inferiority of the mid-septal lead location cannot be concluded. This should be taken into consideration when a mid-septal lead position is pursued. Clinical trial registration ClinicalTrials.gov identifier NCT00745745.

Aims The choice of left ventricular pacing configurations (LVPCs) of quadripolar leads used for cardiac resynchronization therapy (CRT) affects haemodynamic response and thus may be a tool for device optimization. The value of surface electrocardiograms and interventricular time delays (IVDs) for optimization is unknown. Methods and results Sixteen patients implanted with a CRT device with a quadripolar LV lead underwent invasive testing of LV d P /d t . QRS durations at baseline (bl) and during biventricular pacing (biv) were measured using different LVPCs (total of 141 LVPCs; 8.8 per patient). Variations in QRS duration during biv were calculated for each patient (ΔQRS) and, when compared with intrinsic QRS duration, for all LVPCs (ΔQRSLVPC). Interventricular time delays between the poles of the LV lead were obtained from intracardiac electrograms. ΔIVD was calculated as IVDmax − IVDmin. Parameters were correlated with LV d P /d t . ΔQRS and ΔQRSLVPC both significantly correlated with LV d P /d t ( P 168 ms ( P < 0.001), but not

Recovery of pulmonary vein (PV) conduction is a common mechanism of atrial fibrillation recurrence after PV isolation (PVI), underscoring the need for durable lesion formation. We aimed to evaluate the utility of an automated lesion annotation algorithm (ALAA) on acute isolation rates and resulting lesion characteristics. Fifty patients underwent PVI using a contact force (CF) sensing catheter and ALAA. Single antral circles around ipsilateral PVs were performed with ALAA-1 settings including catheter stability (range of motion ≤2 mm, duration >10 s). Target CF was 10–20 g but not part of ALAA-1 settings. If PV conduction persisted after circle completion, force over time was added to automated settings (ALAA-2). Emerging gaps were subsequently ablated, followed by re-assessment for PVI. ALAA-1 isolated 70 % of the left and 78 % of the right PVs using 756.3 ± 212.3 s (left) and 737.1 ± 145.9 s (right) of energy delivery. ALAA-2 settings identified 29 gaps in previously unisolated PVs, closure significantly increased isolation rates to 88 % of the left and 96 % of the right PVs with additional 325.4 ± 354.1 s (left) and 266.8 ± 279.5 s (right) of energy delivery (p = 0.001). Lesion characteristics significantly differed between ALAA-1 (n = 3521 lesions) and ALAA-2 (n = 3037 lesions) settings, and between isolated and non-isolated PV segments, particularly with respect to CF. Interlesion distances with ALAA-2 were significantly longer in the left superior, left superior-anterior, and right superior-posterior segments when compared to ALAA-1. Settings of an ALAA affect lesion characteristics reveal areas of insufficient lesion formation and influence acute effectiveness of PVI. Combination of CF and stability shows superior performance over stability alone.

Aims Image integration of three-dimensional (3D) reconstructions of left atrial (LA) and pulmonary vein (PV) anatomy into electroanatomical mapping (EAM) plays a major role in atrial fibrillation (AF) ablation. Point-by-point EAM is commonly used for registration of imported LA and PV anatomy. We aimed to assess the accuracy of intraprocedural rotational angiography-based LA imaging registered by spatial reconstruction of intracardiac echocardiography (ICE) in patients undergoing AF ablation. Methods and results Twenty-two patients (11 males, 66 ± 12 years) were studied. Reconstructions of LA and PVs based on rotational angiography were registered by a second 3D reconstruction based on ICE. In a second step, EAM points were added to ICE 3D reconstructions. A 3D image of the LA and PVs was reconstructed in all patients by both imaging modalities. Rotational angiography and ICE-based LA 3D reconstructions took 11.5 ± 5.2 and 20.4 ± 11.2 min, respectively. A total of 17 ± 6 two-dimensional ICE fans were used for spatial reconstruction of ICE. The deviation between the two 3D shells was 2.6 ± 0.5 mm. Integration of 78 ± 58 EAM points into ICE 3D reconstruction did not significantly reduce the deviation to rotational angiography-based reconstructions (2.7 ± 0.6 mm). All PVs were isolated successfully. Conclusions Intraprocedural 3D reconstruction of LA and PVs for ablation of AF is feasible based on both rotational angiography and ICE. LA reconstructions based on rotational angiography can accurately be registered using 3D ICE shells. Additional EAM does not enhance accuracy. Therefore, registration of rotational angiography-based 3D reconstructions by 3D reconstructions from ICE seems to be an alternative technique to support AF ablation.

DynaCT Cardiac Integration into Electroanatomical Mapping. Introduction: Exact visualization of complex left atrial (LA) anatomy is crucial for safety and success rates when performing catheter ablation of atrial fibrillation (AF). The aim of our study was to validate the accuracy of integrating rotational angiography-based 3-dimensional (3D) reconstructions of LA and pulmonary vein (PV) anatomy into an electroanatomical mapping (EAM) system. Methods and Results: In 38 patients (62 ± 8 years, 25 females) undergoing catheter ablation of paroxysmal (n = 19) or persistent (n = 19) AF, intraprocedural rotational angiography of LA and PVs was performed. The subsequent 3D reconstruction and segmentation of LA and PVs was transferred to the EAM system and registered to the EAM. The distances of all EAM points to corresponding points on the LA syngo® DynaCT Cardiac surface were calculated. Segmentation of LA with clear visualization of adjacent structures was possible in all patients. Also, the integrated segmentation of the LA was used to guide the encirclement of ipsilateral veins, which resulted in PV isolation in all patients. Integration into the 3D mapping system was achieved with a distance error of 2.2 ± 0.4 mm when compared with the EAM surface. Subgroups with paroxysmal and persistent AF showed distance errors of 2.3 ± 0.3 mm and 2.1 ± 0.4 mm, respectively (P = n.s.). Conclusion: Intraprocedural registration of LA and PV anatomy by contrast enhanced rotational angiography was feasible and accurate. There were no differences between patients with paroxysmal or persistent AF. Therefore, integration of rotational angiography-based reconstructions into 3D EAM systems might be helpful to guide catheter ablation for AF. (J Cardiovasc Electrophysiol, Vol. 21, pp. 278–283, March 2010)

In carriers of dual chamber pacemakers and implantable cardioverter-defibrillators (ICD), detection of atrial fibrillation (AF) is crucial for adequate mode switch function and to avoid inappropriate shock delivery. Detection algorithms rely on the atrial rate and on the relationship of atrial to ventricular intracardiac electrograms, but the relative portion of misclassified AF episodes remains high. Although myocardial impedance is a reliable indicator of contraction, little is known about atrial impedance as a marker of atrial arrhythmias. Methods During an electrophysiological study, we investigated the effect of induced AF on impedance at the right atrial free wall (RAFW) and right atrial appendage (RAA) in 20 patients. Using biphasic square-wave pulses (128 Hz, 200 microA/15 micros), impedance changes were recorded during sinus rhythm (SR-1), atrial pacing at 120 beats/min, AF induced by rapid atrial burst pacing, and after spontaneous AF termination (SR-2). Results At the RAA, peak-to-peak impedance amplitude during cardiac cycle (DeltaZ) dropped from 51.7 +/- 35.3 Omega (SR-1) or 49.6 +/- 30.6 Omega (pacing) to 24.6 +/- 22.0 Omega (AF, Por =0.0005), and subsequently increased to 37.7 +/- 24.7 Omega (SR-2, Por = 0.0004 v. AF). At the RAFW, DeltaZ changed from 16.2 +/- 15.5 Omega (SR-1) or 13.5 +/- 9.9 Omega (pacing) to 5.9 +/- 4.1 Omega (AF, Por = 0.003), and to 11.4 +/- 10.7 Omega (SR-2, Por = 0.015). Given a discrimination threshold of 65%, the sensitivity and the specificity of DeltaZ to detect AF were 79 +/- 18 and 89 +/- 14%, respectively (95% confidence interval).AF causes DeltaZ drop in pacemaker and ICD recipients. This impedance based algorithm can be used as an alternative method of AF detection.

Right bundle branch block (RBBB) configuration is an unexpected finding during right ventricular (RV) pacing that raises the suspicion of inadvertent left ventricular lead positioning. The aim of this study was to evaluate the prevalence of paced RBBB pattern in relation to RV lead location. This is a secondary analysis of a prospective, multicenter study, which randomized implantable cardioverter defibrillator recipients to an apical versus midseptal defibrillator lead positioning. A 12-lead electrocardiogram was recorded during intrinsic rhythm and RV pacing. Paced RBBB-like pattern was defined as positive (0.05 mV) net amplitude of QRS complex in leads V1 and/or V2. In total, 226 patients (65.6 ± 12.0 years, 20.8% women, 53.1% apical site) were included in the study. The prevalence of paced RBBB pattern in the total population was 15.5%. A significantly lower percentage of patients in the midseptal group demonstrated RBBB-type configuration during RV pacing compared with the apical group (1.9% vs 27.5%, p0.001). Baseline RBBB, prolonged QRS duration during intrinsic rhythm, and reduced ejection fraction were not associated with increased likelihood of paced RBBB. In the subgroup of patients with RBBB type during pacing, 91.4% of patients had a paced QRS axis from -30° to -90°, whereas 100% of patients displayed a negative QRS vector at lead V3. In conclusion, RBBB configuration is encountered in a considerable percentage of device recipients during uncomplicated RV pacing. Midseptal lead positioning is associated with significantly lower likelihood of paced RBBB pattern compared with apical location.

The impact of right ventricular (RV) lead location on clinical end points in patients undergoing cardiac resynchronization therapy (CRT) is unclear. We evaluated the impact of different RV lead locations on clinical outcome in CRT patients enrolled in the Septal Positioning of ventricular implantable cardioverter-defibrillator (ICD) Electrodes (SPICE) trial, which randomized recipients of implantable cardioverter defibrillators to apical versus midseptal RV lead positioning.Ninety-eight CRT recipients were included in the multicenter SPICE trial and followed for 12 months: Fifty-three patients were randomized to receive an apical (A) and 45 to receive a midseptal (S) lead position. We compared echocardiographical and electrocardiographical parameters and outcome.Echocardiographic response with respect to improvement of left ventricular ejection fraction (A: +15.8 ± 14.6%, S: +9.7 ± 12.6%, P = 0.156) and reduction of left ventricular end-diastolic diameter (A: -4.2 ± 10.7 mm, S: -7.5 ± 10.7 mm, P = 0.141) was comparable in apical and midseptal groups. Paced QRS width neither differed at prehospital discharge (A: 129 ± 21 ms, S: 135 ± 21 ms, P = 0.133) nor at 12-month follow-up (A: 131 ± 23 ms, S: 134 ± 28 ms, P = 0.620). No differences were found with respect to the risk of ventricular tachyarrhythmia or ICD therapy. Septal RV lead position, however, was associated with a significant longer time to a first heart failure event (P = 0.040) and a longer survival time (P = 0.019).In CRT recipients, midseptal RV lead position was not superior with respect to improvement of echocardiographic parameters or paced QRS width. It did not predispose to ventricular arrhythmias or ICD therapy. The finding that midseptal lead position was associated with a longer time to first heart failure event and a longer survival time deserves further investigation.

Background The placement of an implantable cardioverter defibrillator (ICD) has become routine practice to protect high risk patients from sudden cardiac death. However, implantation-related myocardial micro-damage and its relation to different implantation strategies are poorly characterized. Methods A total of 194 ICD recipients (64±12 years, 83% male, 95% primary prevention of sudden cardiac death, 35% cardiac resynchronization therapy) were randomly assigned to one of three implantation strategies: (1) ICD implantation without any defibrillation threshold (DFT) testing, (2) estimation of the DFT without arrhythmia induction (modified “upper limit of vulnerability (ULV) testing”) or (3) traditional safety margin testing including ventricular arrhythmia induction. High-sensitive Troponin T (hsTnT) levels were determined prior to the implantation and 6 hours after. Results All three groups showed a postoperative increase of hsTnT. The mean delta was 0.031±0.032 ng/ml for patients without DFT testing, 0.080±0.067 ng/ml for the modified ULV-testing and 0.064±0.056 ng/ml for patients with traditional safety margin testing. Delta hsTnT was significantly larger in both of the groups with intraoperative ICD testing compared to the non-testing strategy (p≤0.001 each). There was no statistical difference in delta hsTnT between the two groups with intraoperative ICD testing (p = 0.179). Conclusion High-sensitive Troponin T release during ICD implantation is significantly higher in patients with intraoperative ICD testing using shock applications compared to those without testing. Shock applications, with or without arrhythmia induction, did not result in a significantly different delta hsTnT. Hence, the ICD shock itself and not ventricular fibrillation seems to cause myocardial micro-damage. Trial Registration ClinicalTrials.gov NCT01230086

Background Cardiac resynchronization therapy (CRT) relies on sufficient left ventricular (LV) pacing with safety margin to phrenic nerve stimulation (PNS). Previous studies introduced LV vector reprogramming in bipolar coronary sinus leads to optimize LV pacing and avoid PNS. We investigated the efficacy and reliability of quadripolar leads in CRT. Methods The EffaceQ study enrolled 344 patients with de novo CRT implantation with a quadripolar LV lead in an observational, prospective multicenter study. The study was powered to demonstrate that in at least 90% of patients with an implanted quadripolar LV lead, a viable LV pacing configuration (LVPC) is available (primary end point: LV pacing threshold ≤2.5 V/0.5 ms, sufficient PNS margin). Results Quadripolar leads were successfully implanted in 96% of patients. A total of 278 of 299 (93.0%) patients with complete data met the criteria for viable LVPC. With the use of traditional LVPCs, a viable LVPC would have been available (268 of 299 patients; P = 0.002) in significantly fewer patients (89.6%). In any LVPC, PNS was inducible in 65.0% of patients and 22.6% of patients reported PNS during ambulatory 3-month follow-up. LVPC reprogramming was performed in 49.8% of patients. PNS inducibility decreased from distal to proximal electrodes, whereas LV pacing thresholds increased from distal to proximal. At prehospital discharge, 5.9 ± 2.8 viable LVPCs were observed, stable during follow-up. The quadripolar electrode offered significantly more LVPC for LV optimization and PNS avoidance. Conclusion Quadripolar LV leads yield high numbers of patients with viable LVPCs and alternatives for noninvasive repositioning of LV pacing.

Aims Duty-cycled radiofrequency ablation (RFA) has been used for atrial fibrillation (AF) for around 5 years, but large-scale data are scarce. The purpose of this survey was to report the outcome of the technique. Methods and results A survey was conducted among 20 centres from seven European countries including 2748 patients (2128 with paroxysmal and 620 with persistent AF). In paroxysmal AF an overall success rate of 82% [median 80%, interquartile range (IQR) 74–90%], a first procedure success rate of 72% [median 74% (IQR 59–83%)], and a success of antiarrhythmic medication of 59% [median 60% (IQR 39–72%)] was reported. In persistent AF, success rates were significantly lower with 70% [median 74% (IQR 60–92%)]; P = 0.05) as well as the first procedure success rate of 58% [median 55% (IQR 47–81%)]; P = 0.001). The overall success rate was similar among higher and lower volume centres and were not dependent on the duration of experience with duty-cycled RFA ( r = −0.08, P = 0.72). Complications were observed in 108 (3.9%) patients, including 31 (1.1%) with symptomatic transient ischaemic attack or stroke, which had the same incidence in paroxysmal and persistent AF (1.1 vs. 1.1%) and was unrelated to the case load ( r = 0.24, P = 0.15), bridging anticoagulation to low molecular heparin, routine administration of heparin over the long sheath, whether a transoesophageal echocardiogram was performed in every patient or not and average procedure times. Conclusion Duty-cycled RFA has a self-reported success and complication rate similar to conventional RFA. After technical modifications a prospective registry with controlled data monitoring should be conducted to assess outcome.

Aims In pacemaker patients with preserved atrio-ventricular (AV) conduction, atrial fibrillation (AF) can lead to symptomatic ventricular rate irregularity and loss of ventricular stimulation. We tested if dynamic ventricular overdrive (DVO) as a potentially pacemaker-integrated algorithm could improve both aspects. Methods and results Different settings of DVO and ventricular–ventricular-inhibited-pacing (VVI) with different base rates were tested in two consecutive phases during electrophysiological studies for standard indications. Mean heart rate (HR), HR irregularity and percentage of ventricular pacing were evaluated. A fusion index (FI) indicative of the proportion of fusion beats was calculated for each stimulation protocol. Dynamic ventricular overdrive from the right ventricular apex was acutely applied in 38 patients (11 females, mean age 62.1 ± 11.5 years) with sustained AF and preserved AV conduction. Dynamic ventricular overdrive at LOW/MEDIUM setting increased the amount of ventricular pacing compared with VVI pacing at 60, 70, and 80 beats per minute (bpm; to 81/85% from 11, 25, and 47%, respectively; P < 0.05). It also resulted in a maximum decrease in interval differences (to 48 ± 18 ms from 149 ± 28, 117 ± 38, and 95 ± 46 ms, respectively; P < 0.05) and fusion (to 0.13 from 0.41, 0.42, and 0.36, respectively; P < 0.05) compared with VVI pacing at 60, 70, and 80 bpm. However, the application of DVO resulted in a significant increase in HR compared with intrinsic rhythm and VVI pacing at 80 bpm (to 97 bpm from 89 and 94 bpm, respectively; P < 0.05). Conclusion Dynamic ventricular overdrive decreases HR irregularity and increases ventricular pacing rate compared with VVI pacing at fixed elevated base rates and spontaneous rhythm. Fusion index might help to refine information on pacing percentages provided by device counters.

A 61-year-old woman presented to our outpatient department because of audible alerts by her implantable cardioverter-defibrillator (ICD) starting about 2 weeks ago. The ICD (Medtronic Maximo VR 7232) was implanted in 2004 after cardiopulmonary resuscitation caused by spontaneous sustained ventricular tachycardia. Her medical history was significant for restrictive cardiomyopathy, with predominant right ventricular dysfunction, high-grade tricuspid valve insufficiency treated with tricuspid prosthetic valve replacement in 2000, mildly impaired left ventricular function, and permanent atrial fibrillation. Because of the prosthetic valve replacement, stimulation electrodes were implanted epimyocardially and 2 single-finger defibrillation leads were positioned subcutaneously (Medtronic 6996/SQ-Finger). All electrodes were connected to the ICD, which was placed beneath the diaphragm. High-voltage B (HVB) lead impedance is measured against the ICD can and superior vena cava (SVC) lead in parallel. The SVC lead impedance is measured between both finger leads. Interrogation of the ICD revealed a decrease in HVB lead impedance below the limit of 20 Ω about 2 weeks before presentation, causing the acoustic alert (Figure 1). At the time of presentation, HVB lead impedance was 21 Ω, SVC lead impedance was 36 Ω, pacing impedance was 544 Ω, pacing threshold was stable at 0.1 ms at 3 V, and ventricular amplitude was >5.6 mV. Since the last interrogation 3 months earlier, 15 episodes of nonsustained ventricular tachycardia were detected without the need for antitachycardia therapy. It is noteworthy that …

Our goal was to evaluate acute effects of left atrial lesion formation and volume overload on hemodynamics during pulmonary vein antrum isolation (PVAI) as it might be a potential cause of acute pulmonary edema. In consecutive patients presenting for PVAI, open irrigation ablation was performed (50 W, 48°C, 15 s lesion duration, saline flow rate 30 mL/min). Blood samples were drawn from the left atrium and the pulmonary artery immediately before and 30 min after PVAI. The cardiac output (CO) and stroke volume (SV) were calculated by the method of Fick. We included 61 (27 female, 61 ± 11 years) patients suffering from paroxysmal (px; 33) or persistent (per; 28) atrial fibrillation (AF) in this study. A total of 2,917 ± 242 mL of volume was infused (2,651 ± 223 mL pxAF vs. 3,184 ± 255 mL perAF, (p

Transgenic rabbits expressing loss-of-function pore mutants of the human gene KCNQ1 (K(v)LQT1-Y315S) have a Long QT-Syndrome 1 (LQT1) phenotype. We evaluated for the first time the effect of nicorandil, an opener of ATP-sensitive potassium channels, and of isoproterenol on cardiac action potential duration and heart rate dependent dispersion of repolarisation in transgenic LQT1 rabbits. In vivo LQT1 and littermate control were subjected to transvenous electrophysiological studies; in vitro monophasic action potentials were recorded from explanted Langendorff-perfused hearts. In vivo ventricular effective refractory periods (VERP) at the right ventricular base were significantly prolonged in LQT1 as compared to littermate control, resulting in a more pronounced VERP dispersion in LQT1. This difference in VERP dispersion between LQT1 and littermate control disappeared after infusion of nicorandil. In vitro, mean action potential durations (APD(75) and APD(90)) of LQT1 were significantly prolonged compared to littermate control at baseline. Nicorandil decreased APD(75) and APD(90) in LQT1 and littermate control at all stimulated heart rates. After adding nicorandil, the APD(90) at all hearts rates and the APD(75) at high heart rates were no longer different. Dispersion of repolarisation (∆APD(75) and ∆APD(90)) was heart rate dependently decreased after nicorandil at all tested stimulation cycle lengths only in LQT1. We demonstrated phenotypic differences of LQT1 and littermate control in vivo and in vitro. Nicorandil 20μmol/l improved repolarisation abnormalities and heterogeneities in transgenic LQT1 rabbits.

A 71-year-old female patient was referred for catheter ablation of drug-refractory, symptomatic atrial fibrillation. Initial intracardiac echocardiography (ICE) incidentally showed a mobile embolus stuck at a bifurcation of the right pulmonary artery. The procedure was suspended and the finding was subsequently confirmed by computed tomography pulmonary angiography. This case illustrates a potential value of real-time imaging by ICE during invasive procedures.

Detrimental effects of right ventricular apical pacing have prompted the search for alternative pacing sites. Data from pacemaker studies suggest that the mid-septum may be a hemodynamically favorable pacing site within the right ventricle. However, data on the safety of implantable cardioverter defibrillator (ICD) lead placement in this location are limited. The aim of the SPICE study is to ascertain that implantation of a ventricular ICD lead at the mid-septum is not inferior to the traditional apical site in terms of feasibility and safety. In total, 286 patients with the indication for ICD implantation will be included in the study and stratified in a 1:1 ratio to have the lead placed in the right ventricular apex or the mid-septum. Primary outcome measure of this randomized, prospective study is the event-free survival of lead-related complications at 3 months. The combined end point includes the feasibility to reach the randomized pacing site in combination with the achievement of adequate pacing, sensing, and defibrillation thresholds. Data analysis and sample size calculation are based on a non-inferiority design. This trial will primarily assess the feasibility, safety, and efficacy of right ventricular ICD lead positioning in the mid-septum compared to the traditional apical position. Documentation of non-inferiority of the novel lead position in terms of applicability and safety will be the prerequisite for potential further trials that may evaluate long-term clinical effects associated with mid-septal lead positions.

Preprocedural imaging and its integration into electroanatomical mapping (EAM) is commonly used in atrial fibrillation (AF) ablation. However, intraprocedural imaging based on rotational angiography (DynaCT Cardiac) may be superior in terms of actuality and may lead to an improved work-flow. Feasibility of integrating Dyna CT Cardiac into EAM has not yet been shown. In 23 patients (62±7 years, 16 male) undergoing catheter ablation of paroxysmal (n=10) or persistent (n=13) AF, we intraprocedurally performed rotational angiography enhanced by contrast agent applied to the pulmonary artery with offline segmentation of left atrium (LA) and pulmonary veins (PV). Fig 1 depicts reconstructed LA and PV-anatomy directly importet into CARTOMerge. Distances between the 2 modalities were analyzed. Direct image integration of prereconstructed 3D-anatomy was feasible in all patients. Procedure time was 156 ± 24 minutes including 11 ± 3 minutes for DynaCT Cardiac registration and segmentation. 132 ± 74 mapping points were taken. Mapping points deviated to intraprocedural DynaCT Cardiac 3D-reconstructions by 2.2 ± 0.4 mm (2.3 ± 0.5 mm in patients suffering from paroxysmal atrial fibrillation (AF) vs. 2.1 ± 0.40 mm persistent AF, n.s.). No complications occured. Integration of intraprocedural Dyna CT Cardiac into EAM was feasible and fast. The work-flow seemed to be improved by avoiding additional preprocedural imaging. The novel modality is highly accurate in comparison to EAM.

Visualization of the left atrium (LA) and pulmonary veins (PVs) is crucial in PV isolation (PVI). Additional delineation of the esophagus might avoid severe side effects. Cardiac C-arm computed tomography (DynaCT Cardiac, Siemens AG, Forchheim, Germany) has been introduced as a novel intraprocedural imaging modality based on a rotational angiography.The purpose of this study was to prove the quantitative accuracy of DynaCT Cardiac as compared with multislice CT (MSCT) in imaging of the LA and PV in patients undergoing PVI.Thirty-four consecutive patients (22 male, age 64 +/- 12 years) with symptomatic atrial fibrillation (AF) and indication for PVI were studied. Diameters of the PV, the LA appendage (LAA), and the descending aorta were measured, and the position of the esophagus was defined using preprocedural MSCT and intraprocedural DynaCT Cardiac.There was a significant correlation between both measurements for diameters of the LAA (r = 0.86, P.05), PV (r = 0.98, P.05), and the descending aorta (r = 0.98, P.05). The overall correlation of vessel diameters was r = 0.99. The LA volumes correlation was r = 0.86 and P.05. A significant difference of the esophageal position was found between preprocedural MSCT and intraprocedural DynaCT Cardiac (r = 0.53, P.05).DynaCT Cardiac is a novel intraprocedural rotational angiographic technique. It is highly accurate in displaying crucial structures for PVI in comparison with the results of MSCT. Therefore, DynaCT Cardiac can be used as an alternative imaging technique to improve PVI accuracy.

Aim The impact of atrial fibrillation (AF) on mortality is not fully understood. We therefore sought to investigate long-term effects of AF on mortality in patients with the need for pacemaker (PM) therapy. Methods and results A total of 1627 PM recipients with AF at implantation were followed in a singlecentre, longitudinal study for up to 35 years. Baseline factors affecting survival and long-term followup were analysed. A total of 7362 patient-years of follow-up (PM implanted between 1971 and 2000, followed until 31 December 31 2005) were analysed. Female PM recipients lived significantly longer than male (P ¼ 0.025; mean survival 91.9 vs. 72.1 months) despite older age at time of inclusion. Mean survival times almost doubled for patients implanted in the last decade, with 139.8 months in the nineties vs. 66.8 months in the seventies and 75.7 months in the eighties (P , 0.001). Male gender, age at implantation, non-syncopal bradycardia, and decade of implantation influenced survival. Conclusion Life expectancy in AF patients after PM implantation has doubled within the last three decades, with a mean survival in the overall population of 7.6 years for women and 6.0 years for men. Survival is influenced by several simple baseline characteristics, which may help to identify patients with very long survival times.

Introduction: Recording of intrathoracic far-field electrocardiograms (FF-ECG) via can and electrodes of implantable cardioverter-defibrillators (ICD) is a promising method for continuous monitoring of myocardial ischemia. We assessed the hypothesis that experimentally induced ischemia provokes segment changes in the FF-ECG that can be detected by the ICD. Methods and Results: In seven pigs with an ICD implanted in the left pectoral region and electrodes placed in the right ventricle and the superior vena cava, we occluded all major coronary arteries in proximal and distal locations for 180 s each. Surface and FF-ECGs were compared for presence and time course of ischemic ST segment changes. Reliable detection of ischemia by ST segment analysis was possible in all (38/38) experiments. Maximum deviation from baseline was larger in FF-ECG (1.21 mV) than surface ECG leads (0.23 mV, P < 0.01) for all occlusion sites. Ischemia could be detected earlier (P < 0.05) in the FF-ECG, with a sensitivity of 100%, 93%, and 100% after occlusions in the left anterior descending, left circumflex, and right coronary arteries, respectively. Conclusion: Intrathoracic FF-ECG allows reliable and reproducible detection of experimentally induced ischemia originating from all major coronary arteries and therefore could be an interesting tool for clinicians in monitoring high risk patients.

Aims Lesion formation during catheter ablation crucially depends on catheter-tissue contact. We sought to evaluate the impact of anatomical characteristics of the left atrium (LA) and the pulmonary veins (PVs) on contact force (CF) measurements. Methods and results An anatomical map of the LA was obtained in 25 patients prior to catheter ablation of atrial fibrillation. Contact force (operator blinded) and local bipolar electrogram amplitudes (EGM) were measured in eight pre-defined segments around the PVs. After unblinding, points with low CF (≤5 g) were corrected to CF >5 g, and the distance between points was measured. In a pre-procedural computed tomography of the heart, LA volume as well as sizes and circumferences of the PV ostia were measured and correlated to CF measurements. Four hundred and twenty-six points in eight pre-defined LA locations were assessed. Low CF (

A 56-year-old man with a history of prior myocardial infarction, ischemic cardiomyopathy and nonsustained episodes of ventricular tachycardia had received a subpectorally placed implantable cardioverter-defibrillator (ICD) (Medtronic Micro-Jewel II® 7223 Cx with a single-coil electrode Medtronic Sprint® 6932) for primary prevention of sudden cardiac death three years ago. He was referred to our department after having received twenty-five inappropriate shocks. Interrogation and testing of the device revealed exit-block; incorrect sensing could easily be reproduced and visualized in the ICD’s marker channel by shaking the ICD can. The patient denied tampering with the device, had no history of recent weight loss, psychiatric illness or any other obvious condition with which rotation of the device could be associated. Chest x-ray revealed knotting of the lead just distally of the ICD header (Fig. 1) and multiple twisting of the lead on its way through the anonymous vein. Twiddler’s syndrome with multiple kinks could be confirmed intraoperatively (Fig. 2). The lead was extracted and the whole system replaced. Twiddler’s syndrome, originally described in a pacemaker patient by Bayliss in 1968 [1], denotes a complication in pacemaker and defibrillator patients, in which manipulation with the device leads to twisting of can and electrodes with the consequence of lead displacement. While most of the patients persistently deny manipulation with the device, this is the accepted mechanism leading to lead dislodgement. Previously reported factors that may predispose to device rotation include advanced age, female gender, obesity, small size of the device relative to its pocket and psychiatric disease. Fortunately, Twiddler’s syndrome is a rare complication in ICD patients, however, it may lead to severe complications such as inappropriate shock delivery, which itself may cause ventricular fibrillation, or unrescued sudden cardiac death. Despite the fact that only a small number of Twiddler’s syndromes in subpectorally implanted devices have been published so far [e.g. 2, 3], it cannot be reasoned that ICDs in this position are less predisposed to twiddle.

A 43-year-old woman was referred to our echocardiography laboratory with recent onset, progressive exertional dyspnea. She had been hospitalized 2 months earlier while pregnant for pneumococcal pneumonia with meningitis and severe aortic regurgitation caused by aortic valve endocarditis, a clinical triad first described in 1956 and referred to as Austrian syndrome. In that setting, after caesarean delivery, aortic valve replacement (AVR) was performed. Mother and child recovered well. At the current presentation, 2 months after AVR and after 51 days of antibiotic therapy according to susceptibility testing, transesophageal echocardiography revealed an aortic annular abscess with perforation into the left atrium (Figure 1); the hemodynamic situation resembled severe mitral regurgitation (Figure 2). The AVR and the anterior mitral leaflet were excised, and AVR and mitral valve replacement were performed. No pathogens could be detected in blood cultures, tissue biopsy, or intraoperative smear. The patient recovered well. Unusual infections caused by Streptococcus pneumoniae were frequent in the preantibiotic age but rapidly declined after the introduction of penicillin. The incidence of pneumococcal endocarditis now accounts for less than 3% of all cases and most often occur in patients with risk factors, especially alcoholism, whereas underlying valvular heart disease does not seem to be a strong risk factor. The aortic valve is most commonly involved with a high rate of local and systemic complications and substantial mortality. High suggestion for cardiac involvement should be raised in patients with systemic pneumococcal disease.

OBJECTIVE: Stress-induced release of noradrenaline (NA) from locus coeruleus (LC) neurons is mainly regulated by corticotropin-releasing hormone (CRH). Tyrosine is a precursor of NA and plays an intriguing role in the regulation of NA release. DESIGN: We studied the effects of injecting CRH into the LC using a novel bilateral approach which relies on the mainly ipsilateral projections of LC neurons allowing stimulation of one hemisphere while using the other as control. To analyze the modification of the CRH effect, tyrosine was given intraperitoneally. A combination of CRH and its antagonist d-Phe was administered for validation of the specificity of CRH effects. METHODS: Wistar rats were used in all experiments. Injections were made through fused silica capillaries implanted into both LCs and microdialysis samples were collected bilaterally from the prefrontal cortex (PFM) every 20 min for 1 h before and 3 h after injections. The effects of LC stimulation were investigated by determining 3-methoxy-4-hydroxyphenylglycol (MHPG) in the dialysates. RESULTS: Following CRH injection into one LC and contralateral infusion of artificial cerebrospinal fluid (aCSF), MHPG levels, which are indicative of NA release, increased only in the ipsilateral PFM. These effects were blocked by d-Phe. Simultaneous administration of tyrosine i.p. led to a significant prolongation of MHPG release. CONCLUSIONS: These data provide the first physiological evidence of unilateral LC projections with the bilateral stimulation design proving to be a very valuable tool for the study of LC firing rate, to decrease number of animals and time expenditure. Prolongation of MHPG release after tyrosine supplementation is most likely due to increased NA synthesis.