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With the rapid development of new mapping and imaging technologies as well as catheter ablation technologies, it is increasingly important to understand the basic concepts of conventional mapping and ablation of cardiac arrhythmias. Prerequisite for successful ablation is the exact identification of the tachycardia mechanism and subsequent localization of the origin or tachycardic substrate. Only intracardiac electrograms provide decisive information regarding activation time and signal morphology. In some arrhythmias, it is necessary to supplement conventional mapping with so-called pace and/or entrainment mapping. This article aims to discuss and demonstrate the fundamentals of intracardiac mapping as it relates to the mapping and ablation of supraventricular and ventricular arrhythmias based on representative clinical cases. Modern three-dimensional mapping methods make it possible to individually optimize established ablation strategies with significantly better spatial resolution. The authors aimed to demonstrate that intracardiac uni- and bipolar electrograms provide essential information about timing and morphology guiding successful catheter ablation. Furthermore, our article provides useful information about conventional cardiac mapping techniques including activation mapping, pace mapping, and individual substrate mapping.

Aims Although Eustachian valves and recesses have been related to resistance to block, the effect of convective cooling by the right coronary artery (RCA) has not been evaluated in the clinical setting. Methods and results The distance and course of the RCA in relation to the cavotricuspid isthmus (CTI) in addition to variants of CTI anatomy and the presence of Eustachian valves were analysed from computed tomography scans of 54 patients. Ablation power was titrated using a step-up protocol. Invasive follow-up was available for 34 patients. The RCA came closest to the CTI inferiorly separated by a mean of 5.3 ± 2.5 mm compared with 7.3 ± 3.3 mm septally and 5.7 ± 2.3 mm anteriorly ( P < 0.01). The maximum power required for CTI block correlated inversely with the distance of the RCA to the CTI, whereas the cumulative energy was highest in the presence of recesses. Neither failure of acute block nor a higher rate of conduction recurrence could be attributed to variants of CTI anatomy or the presence of a Eustachian valve. Using multivariate analysis, a position of the RCA underneath the central part of the CTI was the only significant predictor for late conduction recurrence. These patients showed a 2.7 mm larger distance of the RCA to the tricuspid valve plane ( P = 0.05). Conclusion The RCA affects CTI ablation as higher power settings are required at closer distances to the ablation site. Late conduction recurrences were observed in patients with a variation of the RCA, leaving the atrioventricular groove towards the atrial aspect.

Objectives: The effect of angiotensin-converting enzyme inhibitors (ACE-I) and angiotensin II receptor blockers (ARBs) on the long-term outcome after pulmonary vein isolation (PVI) for paroxysmal atrial fibrillation (PAF) is unknown. Methods: This matched-pair study included 102 patients with PAF treated with ACE-I or ARBs (group 1) and 102 control subjects (group 2) after standardized PVI. Tele-ECG recorders were used to detect the end point of the first PAF recurrence after a 3-month blanking period. Results: Median follow-up was 2.1 years (range 0.3–6.3). In group 1, 51 (50%) patients suffered recurrences, with a mean time to recurrence of 3.2 years (95% CI 2.6–3.8). In group 2, 67 (65.7%) patients presented PAF after a mean period of 2.2 years (95% CI 1.7–2.8; p = 0.009). A second ablation was performed in 31 (50%) patients from the treatment group and in 48 (66.7%) patients from the control group (p = 0.02). Multivariate Cox analysis showed treatment with ACE-I and ARBs to be the only significant predictor of a reduced recurrence rate (HR 0.49, 95% CI 0.32–0.75). Conclusion: ACE-I and ARBs were effective for the preservation of sinus rhythm after PAF ablation, and they reduced the reablation rate.

Objectives Our purpose was to investigate the impact of short-lasting atrial fibrillation (AF) on the electrophysiological properties of the atria and pulmonary veins (PVs) in patients devoid of AF. Background The presence of AF is associated with electrical remodeling processes that promote a substrate for arrhythmia maintenance in the atria, which has been termed “AF begets AF.” However, it is unclear whether those electrical alterations also occur in the PVs. Methods Thirty-five patients with a left-sided accessory pathway and without a prior history of AF were included. After successful ablation, the effective refractory periods (ERPs) and conduction times of the right atrium (RA), left atrium (LA), and the PVs were determined. Afterwards, AF was induced and maintained for a period of 15 min. Thereafter, the stimulation protocol was repeated. Results At baseline, the PVs had significantly longer ERPs than the atria. After exposure to AF, the ERPs of both the atria and the PVs decreased significantly. The ERPs of the PVs, however, decreased by a significantly greater extent than the ERPs of the atria (PVs: 248 ± 27 ms vs. 211 ± 40 ms, p Conclusions New-onset, short-lasting AF creates electrical characteristics similar to those of patients with AF. However, these alterations are pronounced in the PVs compared with the atria, indicating that “AF begets AF in the PVs” (Electrophysiological Properties of the Pulmonary Veins; NCT00530608).

Background: External cardioversion is effective to terminate persistent atrial flutter. Biphasic shocks have been shown to be superior to monophasic shocks for ventricular defibrillation and atrial fibrillation cardioversion. The purpose of this trial was to compare the efficacy of rectilinear biphasic versus standard damped sine wave monophasic shocks in symptomatic patients with typical atrial flutter. Methods: 135 consecutive patients were screened, 95 (70 males, mean age 62 ± 13 years) were included. Patients were randomly assigned to a monophasic or biphasic cardioversion protocol. Forty-seven patients randomized to the monophasic protocol received sequential shocks of 100, 150, 200, 300 and 360 J. Forty-eight patients with the biphasic protocol received 50, 75, 100, 150 or 200 J. Results: First-shock efficacy with 50-Joule, biphasic shocks (23/48 patients, 48%) was significantly greater than with the 100-Joule, monophasic waveform (13/47 patients, 28%, p = 0.04). The cumulative second-shock efficacy with the 50- and 75-Joule, biphasic waveform (39/48 patients, 81%) was significantly greater than with the 100- and 150-Joule, monophasic waveform (25/47 patients, 53%, p < 0.05). The cumulative efficacy for the higher energy levels showed naturally no significant difference between the two groups. The amount of the mean delivered energy was significantly lower in the biphasic group (76 ± 39 J) compared to the monophasic one (177 ± 78 J, p < 0.05). Conclusions: For transthoracic cardioversion of typical atrial flutter, biphasic shocks have greater efficacy and the mean delivered current is lower than for monophasic shocks. Therefore, biphasic cardioversion with lower starting energies should be recommended.

Objective: Catheter ablation of ventricular tachycardia (VT) after myocardial infarction (MI) can be complex and time-consuming. We only targeted the previously documented VTs and those with similar or longer cycle lengths. Methods: 30 patients with VTs after MI were included in the study. Voltage mapping was performed using an electro-anatomic mapping system (CARTOT). Stable VTs were mapped during tachycardia and unstable VTs during sinus rhythm. Results: Clinical VTs were stable in 16 (53%) and unstable in 14 (47%) patients, and ablation was successful in 11 (69%) and 9 patients (64%), respectively (p = 0.42). During follow-up (14 ± 6 months), 4 patients (25%) treated for stable and 6 (43%) for unstable VTs had recurrences (p = 0.82); ablation was successful in none and 2 (33%) of them, respectively. Non-target VTs were inducible in 11 (55%) of 20 patients after successful ablation and non-inducible in 9 (45%). During follow-up, inducibility of non-target VTs did not predict recurrences (9 vs. 11%, p = 0.88). Conclusions: Catheter ablation of VTs after MI can be successfully performed. Acute success rates seem to be similar for stable and unstable VTs. VTs faster than those documented clinically exert a minor effect on VT recurrences during follow-up.

Background— Insights gained from noncontact mapping of ventricular tachycardia (VT) have not been systematically applied to contact maps. This study sought to unify both techniques for an individualized approach to the patient with multiple ischemic VTs irrespective of cycle length. Methods and Results— For 12 consecutive patients with chronic myocardial infarction and recurrent VT, bipolar contact maps were acquired during sinus or paced rhythm. Additional noncontact maps were obtained during 48 induced VTs (cycle length 192 to 579 ms). Endocardial exit sites were superimposed on contact maps and verified by pace-mapping. Radiofrequency lesions were extended for critical borders defined by multiple neighboring exits and followed the isovoltage contour line of contact maps. Nine critical borders were identified in 8 patients and constituted the substrate for 31 VTs. The voltage at exit sites was 0.8 mV (range 0.1 to 2.3). Noncontact maps revealed 23±18% of isthmus conduction. Thirty-seven (77%) of all and 83% of clinically documented VTs were rendered noninducible irrespective of cycle length by application of 27 radiofrequency lesions (range 18 to 56). Spontaneous transitions between distinct VTs along critical borders were demonstrated in 4 patients. Pace-mapping reproduced the QRS morphology of 81% of VTs and was associated with successful ablation ( P P Conclusion— The combined approach of contact and noncontact mapping effectively defines critical borders as the substrate of multiple VTs without limitation for unstable VTs.

With increasing advances in technology, cardiac pacemakers have become highly sophisticated devices that allow diagnostic and therapeutic functions beyond conventional antibradycardic therapy. This review discusses the most promising developments in antibradycardic device therapy, such as novel diagnostic functions, telemonitoring, autoadjustment of programmed parameters, algorithms for support of intrinsic atrioventricular conduction, pacing algorithms for the prevention of atrial arrhythmias and cardiac resynchronization therapy. A short overview of the basic principles of antibradycardic device therapy is also provided.

Background: Vasovagal syncope is triggered by complex cerebral and cardiovascular reflex mechanisms leading to general vasodilatation and bradycardia resulting in cerebral hypoperfusion. Methods: We prospectively studied the correlation of postural blood pressure test (PBT) and head-up tilt table test (TT) in patients with recurrent vasovagal syncope. Sixty-eight patients (37 male, 52.4 ± 18.6 years) were included in the trial. They were asked to participate in a PBT and a TT. Independent samples t-test, ANOVA and Fisher’s exact test were used for statistical analysis. p values Results: Thirty patients (44%) showed a positive TT and thirty-four patients (50%) had a positive PBT. PBT did not show any correlation with TT, although pathophysiological mechanisms in vasovagal syncope and orthostatic hypotension are supposed to be similar. Furthermore neither TT nor PBT nor their combination had any predictive value for the patient’s risk of syncope recurrence. Conclusions: TT and PBT are not correlated with each other. Both investigations cannot predict the patient’s risk of syncope recurrence.

Aims To investigate the effectiveness of additional substrate modification (SM) by left atrial (LA) linear lesions as compared with pulmonary vein isolation (PVI) alone in patients with persistent atrial fibrilla- tion (AF) in a prospective randomized study. Percutaneous PVI has evolved as an accepted treatment for paroxysmal AF but seemed to be less effective in patients with persistent AF. The benefit of PVI alone and additional linear lesions has not been validated in a randomized study so far. Methods and results Sixty-two patients with persistent AF (median duration 7, range 1-18 months) were randomly assigned to either PVI alone (n ¼ 30) or additional SM (n ¼ 32) consisting of a roof line connecting both left superior and right superior PV and LA isthmus ablation between left inferior PV and mitral annulus. Procedures including SM were performed using a three-dimensional mapping system (EnSite NavX TM , St Jude Medical, St Paul, MN, USA). Anti-arrhythmic drugs were discontinued within 8 weeks after ablation in both groups. Follow-up included daily trans-telephonic ECG transmitted irrespective of the patient's symptoms. PVI was successful in 98% of all targeted veins in both groups. Additional SM did not increase fluoroscopy time (72.1+ 18.7 vs. 72.9+ 17.3 min, P ¼ 0.92) because of the use of three-dimensional navigation in the PVI þ SM group. AF recurrences within the first 4 weeks following ablation were more common after PVI alone (77%) than additional SM (44%, P ¼ 0.002). After a follow-up time of 487 (429-570) days, only 20% of patients undergoing stand alone PVI remained in sinus rhythm when compared with 69% following PVI combined with SM (P ¼ 0.0001). Two patients assigned to PVI þ SM experienced procedure-related complications (cardiac tamponade and minor stroke) which resolved without sequelae. Conclusion PVI alone is insufficient in the treatment of persistent AF. However, additional left linear lesions increase the success rate significantly. Early AF-relapses are associated with a negative outcome after PVI alone but not following additional SM.

Introduction: Currently, definition of success following atrial fibrillation (AF) ablation is commonly based on the lack of symptoms. The purpose of this study was to evaluate the correlation between symptoms and the underlying rhythm after AF ablation. Methods and Results: Eighty consecutive patients (pts) were treated for paroxysmal episodes of AF by segmental ostial ablation of all pulmonary veins and right atrial isthmus ablation. For 6 months pts transmitted transtelephonic (T-) ECG recordings in combination with comments daily or in the event of symptoms. Eligible comments were classified as: (1) asymptomatic, (2) symptomatic. Analysis was performed at 1-month intervals, defining an acute (first month) and chronic period (second to sixth month) after ablation. Overall 6,835 T-ECGs were analyzed. Of these 5,437 (79.5%) showed sinus rhythm (SR) and 1,398 (20.5%) showed AF. Pts in SR reported symptoms for 593 (10.9%) episodes, whereas 4,844 (89.1%) episodes were asymptomatic. During AF, 646 (46.2%) episodes were associated with symptoms, and 752 (53.8%) episodes remained asymptomatic. Exclusively asymptomatic were 7 (8.8%) pts. In 30 (52.6%) of 57 pts with AF, arrhythmic events were confined to the acute phase. Of the remaining 27 pts 14 (52%) reported an improvement, 12 (44%) the same, and 1 (4%) worsened symptoms after 3 months. A significant change (P < 0.01) toward more asymptomatic episodes from the acute (43.5%) to the chronic (57.5 ± 4.5%) period was evident. Conclusion: Assessment of success after AF ablation cannot be based on the absence of symptoms due to a high prevalence of asymptomatic episodes.

Simultaneous occurrence of narrow and broad QRS complex tachycardias in patients with WPW syndrome usually indicates a macroreentry in an orthodromic atrioventricular reentry-tachycardia using the AV node as antegrade and the accessory pathway as retrograde conduction and vice versa in an antidromic circuit. We report on a 32-year-old woman with WPW syndrome presenting with both a narrow and a broad QRS complex tachycardia using two accessory pathways with different unidirectional conduction properties in combination of an exclusively antegrade conducting AV node. This case report describes conventional mapping techniques and ablation of this unusual entity of a WPW syndrome.

Amiodarone Effect on PV Electrophysiologic Properties. Introduction: Pulmonary veins (PVs) are the predominant location of triggers for atrial fibrillation (AF), but little is known about the electrophysiologic propertiesof PVs. In addition, the influence of amiodarone on the electrophysiologic properties of PVs has not been elucidated. Methods and Results: Fifty-five patients with symptomatic and drug-resistant AF were divided into two groups: group 1 patients (n = 29) without antiarrhythmic drug therapy at the time of electrophysiologic study (EPS), and group 2 patients (n = 26) undergoing continuous long-term treatment with amiodarone. EPS including programmed stimulation of both atria and within the PVs was performed in both groups. In group 1, the effective refractory period (ERP) of all PVs (174 ′ 62 msec) was significantly shorter than the ERP of the left atrium ([LA] 254 ′ 30 msec, P = 0.0001) and right atrium ([RA] 221 ′ 29 msec, P = 0.0001). The same pattern was observed in group 2 (PV: 210 ′ 58 msec; LA: 259 ′ 35 msec, P = 0.0001; RA: 246 ′ 37 msec, P = 0.0255). The ERP of all stimulated PVs was significantly lower in group 1 (174 ′ 62 msec) than in group 2 (210 ′ 58 msec; P = 0.0001). The ERP of the left superior and right superior PVs and RA but not the left inferior PV and LA were significantly increased in patients treated with amiodarone. Decremental conduction properties were observed in all stimulated PVs, and there were no significantly differences between the maximal decrement of both groups. Conclusion: The distinctive electrophysiologic properties of PVs are emphasized by amiodarone therapy. Long-term amiodarone treatment is responsible for heterogeneous alteration of the PV electrophysiology, which may account for the individual antiarrhythmic responses in a subset of patients with paroxysmal AF.

Cooled Versus Large-Tip Catheters for Flutter Ablation. introduction: Open cooled-tip and solid 8-mm-tip catheters have demonstrated safety and effectiveness for radiofrequency current (RFC) ablation of typical atrial flutter (AFL). However, data from prospective and randomized studies in this setting are lacking. Methods and Results: One hundred thirty consecutive patients (104 men; 61 ′ 11 years) with AFL were randomized to undergo RFC catheter ablation either using a solid 8-mm-tip catheter (group A, 65°C, 70 W, 60 s) or an open irrigated-tip catheter (group B, 65°C, 50 W, 60 s, 17 mL/min flow). Endpoint was bidirectional conduction isthmus block. In cases of repeated (two times) transient isthmus block; the catheter was changed (crossed over) to the catheter used in the other randomization arm, but patients remained in the original group following intention-to-treat analysis. The selected endpoint could be achieved in all patients after 12 ′ 6 RFC pulses in group A and 10 ′ 7 RFC pulses in group B (P = 0.11). Procedure times were longer (159 ′ 38 min vs 138 ′ 37 min, P = 0.002) and x-ray exposures higher in group A (fluoroscopy time 25 ′ 17 min vs 21 ′ 10 min, P = 0.08; x-ray dosage 3,133 ′ 2,576 cGy.cm 2 vs 2,326 ′ 1,405 cGy.cm 2 , P = 0.03). Transient isthmus block was observed in 23 group A patients and 12 group B patients (P = 0.03). Onset time of transient isthmus block ranged from 0.5 to 27 minutes. Repeated transient isthmus block occurred in 8 of the 23 patients in group A after 19 ′ 3 RFC applications. After crossover to the cooled-tip catheter, the endpoint was reached another 5 ′ 1 RFC pulses. In group B, all patients could be treated without change of ablation catheter. After a follow-up of 14 ′ 2 months, 2 patients (3%) in group A and 1 patient (1.5%) in group B presented with AFL recurrence. Conclusion: Open cooled-tip catheters are more effective than solid large-tip catheters for AFL ablation. The greater effectiveness is evident in cases showing repeated conduction recovery within the cavotricuspid isthmus. Primary use of open irrigated-tip catheters should be considered for AFL ablation.

Aim Sub-threshold stimulation (STS) applied during atrioventricular nodal re-entrant tachycardia (AVNRT) of the common (slow–fast) type has been shown to effectively characterise target sites suitable for slow pathway (SP) ablation but has not been investigated in the setting of fast–slow and slow–slow variants. Methods and results Seventeen consecutive patients (52±16 years, 12 female) with sustained uncommon type AVNRT (fast–slow: \batchmode \documentclass[fleqn,10pt,legalpaper]{article} \usepackage{amssymb} \usepackage{amsfonts} \usepackage{amsmath} \pagestyle{empty} \begin{document} \(n=13\) \end{document}, slow–slow: \batchmode \documentclass[fleqn,10pt,legalpaper]{article} \usepackage{amssymb} \usepackage{amsfonts} \usepackage{amsmath} \pagestyle{empty} \begin{document} \(n=4\) \end{document}) were investigated. Mapping of the SP was started postero-septally close to the coronary sinus ostium and continued toward mid-septal sites, if required. Target sites for STS were selected according to established criteria including the recording of the earliest retrograde atrial activation during AVNRT. Long duration (5 s) constant current STS during AVNRT variants was performed in a stepwise manner (max 5 mA) at each site eligible for SP ablation until termination or capture occurred. Radiofrequency current (RFC) was delivered following successful STS termination of tachycardia (65 °C, 60 s) and exclusion of catheter dislodgement. Uncommon AVNRT with a mean cycle length of 405±70 ms was induced without spontaneous termination in all patients. Interruption of AVNRT variants due to selective STS-induced block of the retrograde (\batchmode \documentclass[fleqn,10pt,legalpaper]{article} \usepackage{amssymb} \usepackage{amsfonts} \usepackage{amsmath} \pagestyle{empty} \begin{document} \(n=12\) \end{document}) or anterograde (\batchmode \documentclass[fleqn,10pt,legalpaper]{article} \usepackage{amssymb} \usepackage{amsfonts} \usepackage{amsmath} \pagestyle{empty} \begin{document} \(n=2\) \end{document}) SP occurred without capture in 14/17 (82%) patients. This was exclusively observed at sites with successful subsequent RFC application. AVNRT was rendered non-inducible in all patients after a median of 1 (1–11) RFC pulses without complications. Conclusions Uncommon AVNRT can be interrupted by STS delivered at subsequently successful target sites for SP ablation in most patients (82%). The high positive and negative concordance between the effects of STS and following RFC application indicates that STS-mapping is also useful in the setting of AVNRT variants.

The present study sought to investigate the electrophysiological properties of isolated pulmonary veins following successful radiofrequency (RF) catheter ablation in patients with paroxysmal atrial fibrillation (PAF). Overall, 71 pulmonary veins in 37 consecutive patients (age:56 ± 9 years) with recurrent PAF were targeted for RF ablation at the ostial region in order to achieve a complete functional block. Following disconnection, the incidence of dissociated pulmonary vein (PV) activity and its response to orciprenalin were studied. RF ablation abolished conduction in 67 (94%) of 71 potentially arrhythmogenic PVs after a mean of10.7 ± 6.4 RFapplications for each PV. After ablation, spontaneous dissociated automatic activity (9 to 52 beats/min, median 27) was found in 6 out of 67 isolated PVs (left superior:n = 1, left inferior:n = 1, right superior:n = 2, common left PV:n = 2). Slight acceleration (13 to 68 beats/min, median 29) of dissociated PV activity was observed during infusion of orciprenalin. Following isolation, initiation of sustained or nonsustained local fibrillation was recorded in only two cases of the common left sided PV with preceding automatic activity. In one patient PV fibrillation occurred during orciprenalin infusion following a repetitive response to a dissociated automatic rhythm with increasing duration as well as destabilization. In the other patient, PV fibrillation occurred immediately after the occurrence of PV automaticity. Slow dissociated automatic rhythms are detectable within 9% of disconnected PVs. The unique anatomic substrate of common left PVs seem to favor the occurrence of local fibrillation following isolation. The initiation pattern of fibrillation within the isolated PV has pathophysiological implications and underlines the contribution of multiple factors to the onset and sustenance of PAF. (PACE 2003; 26:1363–1370)

A pilot study was performed to determine the efficacy of low energy biphasic external cardioversion in common type atrial flutter. In the majority of patients (70%) successful cardioversion was achieved with low energy levels of 20 or 30 J; however a considerable number of patients (15%) were initially cardioverted to atrial fibrillation, needing an additional cardioversion with an even higher energy level.

Automatic threshold tracking (Autocapture) controls the amplitude of the pacing pulse and adjusts it to the actual pacing threshold. The algorithm is based on the proper detection of the evoked response (ER) amplitude after the pacing pulse. For this reason an intraoperative evaluation of ER and polarization is recommended. The aims of the study were to evaluate the ER signal and polarization and the performance of automatic threshold tracking without any intraoperative testing of the ER signal. In addition, the ER amplitude was correlated with the pacing threshold, pacing impedance, spontaneous R wave amplitude, and with the clinical data. The study included 60 patients who received the VVIR pacemaker Regency connected to the Membrane E 1450/1452 pacing lead (St. Jude-Pacesetter). At implantation, a pacing threshold < 0.7 V at 0.5 ms was achieved in all patients. ER and polarization were assessed for the first time at hospital predischarge testing. Follow-up measurements were conducted at month 1, 3, and 6. The ER amplitude at hospital discharge was 8.4 +/- 4.2 mV and increased to 9.4 +/- 4.8 mV at the 6-month follow-up. The pacemaker recommended not to program automatic threshold tracking on in one patient permanently and in three patients intermittently. The ER amplitudes were not differently distributed in men compared with women or in right-sided compared to left-sided implants. The correlation between age and the evoked response was r = 0.15. The correlation between ER amplitude and pacing threshold was r = -0.08, with pacing impedance r = 0.02, and with R wave amplitude r = 0.44. In conclusion, despite no operative evaluation of the ER amplitude being performed, the mean ER amplitude was about 9 mV at 6-month follow-up. Automatic threshold tracking could be programmed on in 93% of the patients throughout the time. Neither the clinical data nor the conventional electrical parameters help to predict patients who will have low ER amplitude or to optimize the ER signal at implantation.

We report a female patient with a ventricular lead perforation late after implantation. The lead perforated heart and lung parenchyma and caused hemothorax but no cardiac effusion or tamponade. No definitive evidence for lead perforation was found by standard diagnostic assessment. Definitive diagnosis was established by cath-lab fluoroscopy. The surgical treatment including thoracotomy, lead removal, repair suture of the right ventricle and finally placement of an epicardial electrode was successful.

AVNRT in the Elderly. Introduction: Atrioventricular nodal reentrant tachycardia (AVNRT) is the most common regular supraventricular tachycardia in the general population as well as in elderly patients. The purpose of thestudy was to investigate the success and complication rate particularly regarding the induction of an atrioventricular (AV) block by radiofrequency (RF) ablation in elderly patients with and without a preexisting AV block. Methods and Results: Between February 1998 and July 2004, all patients with symptomatic AVNRT referred for slow-pathway ablation in our institution were included and divided into two groups: group 1 patients younger than 75 years (n = 508) and group 2 patients >75 years (n = 70). A preexisting prolonged PR interval was present in 17 (3.3%) patients of group 1 and in 26 (37%, P < 0.0001) patients of group 2. Following successful slow-pathway ablation (follow-up time group 1: 37 ′ 22, group 2: 37 ′ 24 months) no induction of an AV block was observed in group 2 but in four patients of group 1 (0.79%) a complete heart block was induced requiring a pacemaker implantation. In group 1, 15 (2.95%) patients with a recurrence of AVNRT were readmitted for a repeat ablation procedure. No recurrences occurred in group 2. Conclusion: Despite a higher incidence of preexisting prolonged PR intervals slow-pathway ablation in elderly patients is both effective and safe and should be considered as the first line therapy also in this patient population.

The most widely accepted criterion for successful radiofrequency catheter (RFC) ablation of typical atrial flutter is the development of bi-directional isthmus block. In a subset of patients, conventional RFC ablation fails to achieve this endpoint because deeper and wider lesions are required. We investigated the efficacy of a long 8-mm tip catheter in these cases. One hundred and seventy-four consecutive patients (137 male; 61 +/- 9 years) with recurrent typical atrial flutter underwent conventional RFC ablation first with a standard 4 mm tip catheter. In resistant cases (n = 52), ablation was continued using a large tip 8-mm catheter when the 4-mm tip catheter failed. Resistant atrial flutter was identified when 21 RFC pulses failed to reach the selected endpoint of bi-directional isthmus block or in cases of transient bi- directional block (at least 3 episodes). In 122 of the 174 patients (70%) conventional atrial flutter ablation was successfully performed with 13 +/- 5 RFC applications. In the remaining 52 subjects (30%), the ablation procedure was completed using the large tip electrode catheter. In 30 of these 52 patients (58%), the catheter was changed because of persistent intra-atrial conduction after 21 RFC pulses and in 22 (42%) because of intermittent conduction block after 11 +/- 5 applications. Using the large tip electrode catheter, the selected endpoint was achieved in all patients of both groups with 3 +/- 2 RFC pulses (power output of 50-60 W, pulse duration of 60 sec). No post-procedure complications were observed. After 15 +/- 5 months of follow-up, 16 patients (9%) had recurrence of atrial flutter. Five of the patients had been in the resistant group. In patients with atrial flutter resistant to conventional ablation therapy, the long tip (8-mm) catheter appears to be a safe and effective alternative to use of the conventional 4-mm tip catheter.

Isolation of arrhythmogenic pulmonary veins (PVs) by radiofrequency current (RF) application has been introduced as a curative treatment for patients (pts) with paroxysmal atrial fibrillation (AF). The present study sought to investigate the feasibility and efficacy of this approach guided by conventional and electroanatomical mapping (CARTO).Twenty pts (13 male; 57 +/- 8 years) with recurrent documented focally triggered idiopathic AF refractory to multiple antiarrhythmic drugs were prospectively included. Atrial premature beats were present at baseline in 9 pts and could be provoked in further 8 pts. Empirical ablation of both superior PVs was performed in 3 pts with no focal activity. After transseptal puncture selective angiography of all PVs was obtained. Thirty-six PVs (left superior: n = 18, right superior: n = 10, left inferior: n = 8) were targeted for RF ablation. A complete left atrial CARTO-map including the left atrial (LA) to pulmonary vein (PV) junction was obtained during sinus rhythm and/or coronary sinus pacing. RF was initially applied at the PV-LA junction at areas with the shortest left atrial- to PV potential interval (target 50 degrees C, max. 30 W, duration 60 sec). Isolation was confirmed by the complete disappearance of specific PV potentials. RF lesions were analyzed with respect to the number of segment-quarters covering the PV ostium.Functional isolation could be achieved in 35 out of 36 PVs following 10 +/- 5 RF applications for each PV. RF applications covered 2 or less quarter segments of the overall PV circumference in 29 (80%) PVs. Total session duration was 6.5 +/- 1.6 h with a mean fluoro-time of 54 +/- 18 minutes. For CARTO mapping and ablation a mean fluoro time of 34 +/- 6 min was required. During a mean follow up period of 8.3 +/- 2.5 months AF relapsed in 9 pts (46%). A second approach was performed in 5 pts. and demonstrated either new foci (n = 2) or recurrence of previously isolated PV (n = 8). The second RF ablation procedure led to stable sinus rhythm in 3 out 5 pts. Thus, the overall success rate including the second procedure was 70%.CARTO guided functional isolation of presumed arrhythmogenic PVs by RF lesions covering 2 or less segments of the PV ostium in most patients is feasible. However, repeat procedures are often warranted to permanently treat paroxysmal atrial fibrillation.

Pulmonary vein (PV) isolation for the treatment of atrial fibrillation is limited by procedure related complications, such as PV stenosis and occlusions. We report about a PV isolation using a circumferential cryoablation catheter which applies the ablation energy simultaneously at the entire circumference by cooling down to a minimal temperature of −80°C. (PACE 2004; 27:1024–1025)