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R Cappato

Publications and source records attributed to R Cappato.

At least 37 records · Page 2Linked to original sources
PubMed1998

Ventricular tachycardia during follow-up in patients resuscitated from ventricular fibrillation: experience from stored electrograms of implantable cardioverter-defibrillators.

OBJECTIVE: The purpose of this study was to use the electrogram storage capabilities of the implantable cardioverter-defibrillator (ICD) to categorize any arrhythmic event during follow-up in a group of patients who had survived an episode of ventricular fibrillation (VF) and to possibly identify clinical predictors of future arrhythmic events. BACKGROUND: Little is known about the electrophysiologic characteristics of ventricular arrhythmias recurring during follow-up in survivors of VF as the sole documented arrhythmia at the time of resuscitation. METHODS: Forty patients (58+/-10 years; 73% men; left ventricular ejection fraction 42+/-18%; 70% with coronary artery disease) who had survived an episode of VF and subsequently received an ICD capable of intracardiac electrogram recording and storage were followed for 23+/-11 months. In all patients, the arrhythmogenic substrate was investigated by means of programmed electrical stimulation (PES). RESULTS: Among the 40 patients, 41 episodes of ventricular arrhythmias were documented in 13 patients (33%): 36 episodes of ventricular tachycardias (VT) were recorded in 11 patients (28%) and 5 episodes of VF were recorded in the remaining 2 patients (5%). Age, gender, cardiac disease and left ventricular ejection fraction failed to distinguish between patients with clinical recurrences and patients without. The sensitivity, specificity and positive accuracy of PES were 29%, 63% and 46%, respectively, for prediction of ventricular arrhythmia recurrence; 45%, 70% and 36%, respectively, for prediction of VT; and 50%, 98% and 50%, respectively, for prediction of VF during follow-up. CONCLUSIONS: In survivors of VF receiving ICD therapy, VT is the most common ventricular arrhythmia recorded on device-incorporated electrograms during follow-up. This finding, associated with the relatively well-preserved ventricular function, may account for the ability of these patients to survive at time of the index arrhythmia; the use of antitachycardia pacing as a modality to treat arrhythmia recurrences may contribute to reduce the incidence of shock during follow-up in these patients.

Aged↗
PubMed1998

[High frequency current ablation of ectopic atrial tachycardia. Different mapping strategies for localization of right- and left-sided origin].

UNLABELLED: Ectopic atrial tachycardia (EAT) is a rare form of supraventricular tachycardia and often drug-resistant. Radiofrequency catheter (RFC) ablation offers an alternative therapy suggesting a high efficacy rate. Localization of the EAT origin is proposed to be efficacious by various mapping strategies. We analyzed the efficacy of different mapping strategies for localization of right and left sided EAT foci. METHODS AND PATIENTS: In a cohort of 48 patients (25 female: age 35 +/- 18 years) RFC ablation of 40 right and 12 left sided EAT foci was performed. Mapping of the right atrium was achieved with 2 ablation catheters using the "encircling" technique (Figure 1). We looked for an early bipolar local electrogram in relation to the onset of the P-wave and a QS-complex in the unipolar electrogram. The bipolar local electrogram was retrospectively analyzed for a fragmented morphology and duration of more than 50 ms (Figure 3). In case of mechanical block of the EAT during mapping P-wave pace mapping over the mapping catheter was performed (Figure 4). RESULTS: RFC ablation succeeded in 44 patients with 46 EAT foci (Figure 5). Left sided EAT origin was in 40% in the region of the pulmonary veins. Two left sided foci were abladed within the coronary sinus. An anteroseptal location in vicinity to the bundle of His was found in 4 cases (Figure 6). There were no differences between left and right sided origin regrading session duration (304 +/- 131 vs 241 +/- 101 min) and fluoroscopic time (39 +/- 29 vs 31 +/- 19 min). The activation time related to the onset of the P-wave was at successful ablation site for left sided origin significantly earlier compared to a right sided origin (45 +/- 22 vs 30 +/- 18 ms). Fragmenation of the bipolar local electrogram was found before successful RFC application in 86% in the left and in 65% in the right atrium. The unipolar electrogram showed in 87% of all cases a QS-complex before the successful RFC pulse. In 16% a beat to beat change of the unipolar electrogram could be found at successful ablation site (Figure 7). Both criteria had a low specify and sensitivity. Mechanical block could be induced during mapping in 10 patients (20%). In these cases RFC application at a site with a perfect match of P-wave pace mapping succeeded in 8 patients. In 2 patients the same EAT occurred within the following 24 hours. During a follow-up of 4 to 58 months there were additionally recurrence of EAT in 3 patients (3 to 6 months after ablation). No influence of the AV nodal conduction was observed after ablation of anteroseptal EAT foci. Other acute or chronic complications were not observed. CONCLUSIONS: 1. RFC ablation of right and left sided EAT foci is a safe and efficacious treatment. There were no differences regarding session duration and fluoroscopic time between right and left sided foci. 2. Activation mapping showed an earlier activation time for left sided origin compared to right sided. 3. Mechanical block could be induced in 20% of cases. P-wave pace mapping might offer a strategy to localize the focus during mechanical block.

Adolescent↗
PubMed1998

Nonfluoroscopic endocardial catheter mapping of atrial fibrillation.

The treatment of drug-refractory atrial fibrillation (AF) remains one of the unsolved problems in cardiology. Surgical interventions have demonstrated that AF can be prevented by multiple incisions within both atria. Recently, this strategy has been translated into a catheter procedure. So far, the ablation approach is not based on individual electrophysiologic data, but constitutes only an anatomic approach. Further insight into the spatial and temporal distribution of the local electrograms during AF is needed. Electroanatomic maps acquired by sequential mapping over 45 seconds at each site during AF in six patients with paroxysmal AF were analyzed off-line. Electrograms were sampled at a mean of 36 +/- 12 sites in the left atrium of each patient. A total of 217 sites were sampled, of which 27.3% (59) represented type A (regular) AF, 9.7% (21) represented type B (totally irregular), and 63.1% (137) represented type C (mixture of type A and B) electrograms. The distribution was analyzed in 20 different segments of the left atrium, and a significantly higher incidence of type A electrograms was found in area 3 (upper lateral pulmonary vein) than at all other sites (P < 0.005). This observation needs further confirmation before any conclusion with regard to catheter ablation can be drawn, particularly because the analysis was based on bipolar recordings from a 4-mm tip electrode.

Aged↗
PubMed1997

Effects of permanent pacemaker and oral theophylline in sick sinus syndrome the THEOPACE study: a randomized controlled trial.

BACKGROUND: Pacemakers and theophylline are currently being used to relieve symptoms in patients with sick sinus syndrome (SSS). However, the impact of either therapy on the natural course of the disease is unknown. We conducted a randomized controlled trial to prospectively assess the effects of pacemakers and theophylline in patients with SSS. METHODS AND RESULTS: One hundred seven patients with symptomatic SSS (age, 73 +/- 11 years) were randomized to no treatment (control group, n = 35), oral theophylline (n = 36), or dual-chamber rate-responsive pacemaker therapy (n = 36). They were followed for up to 48 months (mean, 19 +/- 14 months). During follow-up, the occurrence of syncope was lower in the pacemaker group than in the control group (P = .02) and tended to be lower than in the theophylline group (P = .07). Heart failure occurred less often in patients assigned to pacemaker therapy and theophylline than in control patients (both, P = .05), whereas the incidence of sustained paroxysmal tachyarrhythmias, permanent atrial fibrillation, and thromboembolic events did not show any apparent difference among the three groups. Heart rate was higher in the theophylline group than in the control group. Both pacemaker therapy and theophylline improved symptom scores after 3 months of treatment; however, a similar improvement was observed in the control group. CONCLUSIONS: In patients with symptomatic SSS, therapy with theophylline or dual-chamber pacemaker is associated with a lower incidence of heart failure; pacemaker therapy is also associated with a lower incidence of syncope. The therapeutic benefits of pacemakers and theophylline on symptoms are partly a result of spontaneous improvement of the disease.

Administration, Oral↗
PubMed1997

[Anatomic distribution, conduction properties and recurrences after ablation of multiple in comparison with single accessory conduction pathways].

In 1076 consecutive patients referred for radiofrequency current catheter ablation, the anatomical distribution and conduction properties of accessory pathways (APs) as well as the mode of recurrence after ablation were retrospectively analyzed and compared in patients with multiple and single APs. Except for 17 patients with Ebstein's anomaly, the prevalence of patients of multiple APs in this cohort was 5.4%. Patients with multiple APs. as opposed to patients with a single AP, had significantly more often APs located on the right free wall (23% versus 10%) and--since the prevalence of septal APs was identical in both groups--less frequently APs located on the left free wall (44% versus 56%). Also, concealed APs were significantly more often encountered in patients with multiple APs (45% versus 24%). Recurrence of conduction across an AP which had presumably been ablated was observed in both groups with statistically equal incidence of < 5%. In 11 patients with multiple APs, the additional AP was only found at the repeat session. These "new" APs were mostly concealed (9 out of 11) and necessitated an intervention predominantly late after the initial ablation session. Intermittent concealed conduction appears to be a likely explanation for this phenomenon. Patients with multiple APs exhibit a higher incidence of right free-wall and concealed APs, yet they stand the same, approximately 95%, chance of cure as do patients with a single AP. Nearly 25% percent of repeat sessions in patients initially thought to have a single AP are caused by the late manifestation of an additional AP.

Adolescent↗
PubMed1997

Mapping of the coronary sinus and great cardiac vein using a 2-French electrode catheter and a right femoral approach.

INTRODUCTION: Local electrograms recorded from the coronary sinus and great cardiac vein provide important information for the diagnosis of various arrhythmias and identification of target sites for ablation of left-sided accessory pathways. One limitation of present techniques is the inability, in many cases, to probe the great cardiac vein at the anterior mitral annulus. We tested the feasibility of a new technique for catheterization of the coronary sinus and great cardiac vein by means of a small-diameter electrode catheter advanced via a right femoral approach through an angiography catheter. METHODS AND RESULTS: Of 22 patients (12 men and 10 women; ages 44.5 +/- 13.4 years) undergoing radiofrequency ablation of a supraventricular tachycardia, cannulation of the coronary sinus orifice using a 6-French 1L or 2L Amplatz catheter was achieved in 20 patients (91%) within 0.9 +/- 0.6 minutes; after cannulation, a 2-French octapolar electrode catheter with a soft radiopaque tip and a 3-mm interelectrode distance could be advanced in all 20 patients through the guiding catheter to the great cardiac vein in the anterior region of the AV sulcus within 0.8 +/- 0.7 minutes. Atrial and ventricular local potentials were recorded all along the mitral annulus during sinus rhythm, atrial and ventricular pacing, or supraventricular tachycardia. Variation of local potential amplitude never exceeded 20% of the mean and presented similar stability at all annular regions. The arrhythmogenic substrate was identified in all patients. Of 18 patients with 21 left-sided accessory pathways, an accessory pathway potential could be recorded at the ablation site by one or more adjacent epicardial electrode pairs in 10 pathways. No procedure-related complications were observed. CONCLUSIONS: The technique introduced in this study proved feasible in 91% of patients. Its main advantages are the simplicity and rapidity of coronary sinus cannulation and the ability to advance the electrode catheter to the anterior cardiac vein. In addition, closely spaced bipolar electrograms resulted in enhanced atrial, ventricular, and accessory pathway potential resolution.

Adult↗
PubMed1997

Inappropriate sinus tachycardia after radiofrequency ablation of para-Hisian accessory pathways.

INTRODUCTION: Inappropriate sinus tachycardia (IST) has been observed following radiofrequency ablation (RFA) of the AV nodal fast pathway. This study was aimed to prospectively analyze the incidence and clinical significance of IST following RFA of para-Hisian accessory pathways (APs). METHODS AND RESULTS: Twenty-eight patients (pts) with para-Hisian APs underwent RFA. An AP was defined as para-Hisian whenever its atrial and ventricular insertions were associated with a His-bundle potential > or = 0.1 mV. RF current was always delivered at the atrial aspect of the tricuspid annulus, to a site where the His-bundle potential was < 0.15 mV. Time- and frequency-domain analysis of heart rate variability was performed in 22 patients, before and after RFA. Abolition of AP conduction was obtained in all pts, and no AV conduction alteration occurred. Six pts (21.4%) presented with IST 45 to 240 minutes after the ablation procedure. In 5 of them, IST disappeared spontaneously within 72 hours, whereas in 1 pt beta-blockers were required for 2 months. The atrial potential amplitude (1.217 +/- 0.264 mV vs 0.882 +/- 0.173 mV, P = 0.009) and A/V potential amplitude ratio (2.633 vs 1.686, P = 0.05) were significantly higher in pts who developed IST than in those who did not. A marked decrease in heart rate variability was observed only in pts who developed IST. CONCLUSION: IST is a relatively frequent complication after RFA of para-Hisian APs: it is generally short-lasting and usually does not require any treatment. IST after catheter ablation is likely to depend upon transient parasympathetic denervation of the sinus node.

Adolescent↗
PubMed1997

Clinical recurrences after successful accessory pathway ablation: the role of "dormant" accessory pathways.

INTRODUCTION: Recurrence of clinical symptoms after radiofrequency catheter ablation of an accessory atrioventricular pathway (AP) may be due to the late manifestation of an additional AP that was not detected during the initial ablation session. It was the purpose of this study to elucidate the phenomenon of these "dormant" APs. METHODS AND RESULTS: Of 1280 consecutive patients who underwent radiofrequency catheter ablation of an AP, 54 patients (4.2%) developed clinical symptoms postablation, necessitating a repeat ablation session. Recurrence of conduction over the AP targeted at the initial ablation session was found in 45 patients, whereas in the other 9 patients (0.7%) the manifestation of a previously unnoticed AP had caused symptom recurrence. Retrospective analysis of the data from these patients' ablation sessions revealed that the late manifesting AP was ablated at a site clearly different from that of the initially targeted AP, and that the manifestation of conduction over a previously "dormant" AP occurred significantly later than the recovery of a presumably ablated AP. Seven (78%) of the 9 "dormant" APs were concealed, and none exhibited decremental conduction properties. CONCLUSION: The incidence of clinical recurrences mediated by the late manifestation of conduction over a previously "dormant" AP is low. The lack of an anatomic vicinity of these predominantly concealed APs with the initially targeted AP and the lack of evidence for their presence during the initial ablation session suggest intermittent conduction as the most likely explanation for their late manifestation.

Adult↗
PubMed1996

Radiofrequency current catheter ablation of accessory atrioventricular pathways in Ebstein's anomaly.

BACKGROUND: In patients with Ebstein's anomaly, localization of accessory pathways (APs) may be impeded by abnormal local electrograms recorded along the atrialized right ventricle and by the presence of multiple APs. The impact of these factors on radiofrequency (RF) current catheter ablation of APs has not been evaluated yet. METHODS AND RESULTS: Twenty-one patients with Ebstein's anomaly and reentrant atrioventricular tachycardias underwent electrophysiological evaluation and subsequent attempts at RF catheter ablation. Thirty-four right-sided APs were found, with 30 located along the atrialized ventricle. Local electrograms in this region were normal in 10 patients but fragmented in 11. Fragmented electrograms prevented the clear distinction between atrial and ventricular activation potentials as well as the identification of AP potentials. Right coronary artery mapping was performed in 7 patients. Abolition of all 26 APs was achieved in the 10 patients with normal local electrograms and in 6 of 11 patients with abnormal electrograms. Right coronary artery mapping allowed AP localization and ablation in 5 patients. In the 5 patients with abnormal electrograms and a total of 8 APs, 6 APs could not be ablated. Unsuccessfully treated patients received antiarrhythmic drugs. During 22 +/- 12 months of follow-up, 5 patients had clinical recurrences, including 4 who had undergone a successful RF procedure. CONCLUSIONS: In patients with Ebstein's anomaly and reentrant atrioventricular tachycardias, factors likely to account for failure of RF catheter ablation include an AP located along the atrialized right ventricle and the abnormal morphology of endocardial activation potentials generated in this region.

Action Potentials↗
PubMed1996

Programmable polarity: effects on pacing and sensing of bipolar steroid-eluting leads.

Presently available bipolar pacemakers connected to bipolar leads allow the programming of polarity to either bipolar or unipolar configuration. The bipolar configuration improves sensing because of its lack of oversensing. In respect to the pacing impulse, it may be beneficial to program the bipolar to unipolar configuration, because the unipolar pacing configuration seems to lead to lower pacing thresholds. The aim of the study was to investigate the effects of the two configurations on pacing and sensing in 11 patients with a new ventricular steroid-eluting lead (Encor Dec 033-301, Telectronics Inc.) connected to the same types of VVI(R) pacemakers. Follow-up was 12 months after implantation. Pacing was assessed by pulse duration thresholds at 0.8- 1.6-, and 2.5-V pulse amplitude and by pacing impedance. Parameters for sensing included sensing thresholds, R wave amplitudes, and amplitude of intrinsic deflection. Pulse duration thresholds were similar for the two configurations. At implantation, pacing impedance was significantly higher with bipolar (672 +/- 60 omega) than with unipolar pacing configuration (626 +/- 82 omega, P < 0.005). The difference lasted until 1 month after implantation (bipolar: 670 +/- 49 omega; unipolar: 63053 omega, P < 0.01). No significant differences were detected after 3 (bipolar: 683 +/- 63 omega; unipolar: 662 +/- 70 omega) and 12 months (bipolar: 658 +/- 64 omega; unipolar: 660 +/- 63 omega) between the 2 configurations. Although intrinsic deflections of ventricular electrograms were different, mean R wave amplitudes were similar in unipolar and bipolar configuration. Pacing and sensing characteristics of unipolar and bipolar configuration were similar for the studied bipolar pacing lead. Pacing impedance was initially higher for bipolar than for unipolar configuration and equilibrated within 3 months after implantation.

Aged↗
PubMed1996

Reliability and variability of impedance measured by real-time telemetry.

UNLABELLED: With the aim to detect dysfunction of pacing leads, most present-day pacemakers measure pacing impedance by means of real-time telemetry. The recommended setting for impedance measurement is 5.0 V for pulse amplitude and 0.5 ms for pulse duration. Availability of reliable settings would facilitate impedance measurements during follow-up. The purpose of the present study was twofold: (1) to assess whether telemetrically measured impedance of the studied pacemaker is similar to impedance measured at implantation; and (2) to evaluate whether the pacemaker setting influences telemetrically measured impedance. Sixty-five consecutive patients receiving VVI(R) pacemakers were studied; in all patients, impedance measured at implantation by a pacing system analyzer was compared to measurements obtained telemetrically within 1 day after implantation. In 44 other patients, impedance was determined 3 months after implantation at 60 and 120 ppm (n = 44), twice at 60 ppm (n = 42), and 12 months after implantation at 60 ppm (n = 34). For each measurement, pulse amplitude was programmed to 0.8, 1.6, 2.5, 5.0, and 8.0 V, and pulse duration to 0.05, 0.25, 0.50, and 1.00 ms. Impedance at implantation (606 +/- 113 ohms) did not differ from the data obtained with telemetry (629 +/- 113 ohms; P = NS). Different pacing rates, repeat measurements, and follow-up time failed to show any influence on impedance. Measurement tolerance was < 10% for 15 of 19 studied settings other than 5.0 V and 0.5 ms. CONCLUSION: The studied pacemakers provide reliable data for telemetrically measured impedance. Telemetrical impedance does not necessarily have to be measured at 5.0 V and 0.5 ms. These findings should be considered for measurement and interpretation of real-time telemetry impedance during follow-up.

Aged↗
PubMed1996

Radiofrequency catheter ablation of left atrial tachycardia originating within the pulmonary vein in a patient with dextrocardia.

A case is presented of a 38-year-old male with dextrocardia in whom radiofrequency current ablation of an incessant atrial tachycardia originating within the infero-lateral pulmonary vein was achieved. Activation mapping with detection of the earliest atrial activation was used for identification of the arrhythmogenic focus. In addition to fluoroscopy, transesophageal echocardiography was used for catheter guidance during the transseptal puncture. The present experience suggests that location of an arrhythmogenic focus within the pulmonary venous system should be considered whenever early atrial activation during ectopic atrial tachycardia is recorded at the junction between the left atrium and the pulmonary veins.

Adult↗
PubMed1995

Metoprolol versus sotalol in the treatment of sustained ventricular tachycardia.

The efficacy of sotalol in the treatment of sustained ventricular arrhythmias has been proved; however, whether its antiarrhythmic effect is due to a beta-blocking activity, a class III antiarrhythmic activity, or a combination of both is not known. We conducted a prospective randomized study to compare the effects of metoprolol, a "pure" beta-blocking agent, and of sotalol, a beta-blocking agent with additional class III antiarrhythmic properties, in 34 consecutive patients with documented sustained monomorphic ventricular tachycardia (VT) unrelated to transient causes. After undergoing baseline programmed electrical stimulation (PES-1) to assess arrhythmia inducibility, the patients were randomly assigned to a (double-blind) treatment of either metoprolol (16 patients) or sotalol (18 patients). Before the chronic regimen was initiated, arrhythmia inducibility was reassessed after the intravenous administration of either 0.15 mg/kg metoprolol or 1.5 mg/kg sotalol (PES-2), according to drug assignment. During the chronic oral regimen, a third PES (PES-3) was performed after a median follow-up of 72 days. Resting and exercise ECG, Holter monitoring and echocardiography were performed at baseline and during follow-up. During a 2-year follow-up, a non-fatal arrhythmia recurred in 1 patient of the metoprolol arm and in 5 patients of the sotalol arm; 1 patient in the latter group died suddenly 2 months after the recurrence, while receiving amiodarone therapy. Intention-to-treat analysis showed no difference in the incidence of arrhythmia recurrence, sudden death, or total mortality between the two groups. During PES-1, a sustained ventricular arrhythmia was inducible in 18 of 34 patients (53%), 8 in the metoprolol and 10 in the sotalol arm.(ABSTRACT TRUNCATED AT 250 WORDS)

Administration, Oral↗
PubMed1995

Programming of the pacing impulse in pacemakers connected to steroid lead systems.

The purpose of the study was to compare the feasibility of low amplitude output programming (2.5 V/0.5 msec) 3 or more months after pacemaker implantation in patients receiving steroid and nonsteroid lead systems. Chronic pacing voltage, current, and energy thresholds were determined from 0.05- to 1.0-msec pulse duration in 44 patients with steroid lead systems, and in 36 patients with nonsteroid lead systems; all patients received pacemakers from the same manufacturer, which utilized the same programming and telemetry features. Chronaxie, pulse duration at the lowest pacing current, and energy were assessed from individual threshold curves. Steroid-eluting leads had significantly lower pacing voltage, current, and energy thresholds than nonsteroid leads. A 100% safety threshold margin could be achieved in 43 (98%) patients with steroid lead systems and in 27 (75%; P < 0.05) patients with nonsteroid lead systems with output programming of 2.5 V/0.5 msec. Chronaxie (0.22 +/- 0.17 msec vs 0.44 +/- 0.31 msec; P < 0.05), pulse duration at lowest pacing current (0.28 +/- 0.12 msec vs 0.49 +/- 0.22 msec; P < 0.05), and pulse duration at lowest pacing energy (0.31 +/- 0.17 msec vs 0.53 +/- 0.22 msec; P < 0.05) were significantly shorter for steroid than for nonsteroid lead systems. In 42 patients of the former group, a 100% safety margin could be maintained either with a 2.5 V/0.3 msec or with a 1.6 V/0.5 msec output. Conclusions Low amplitude output programming can be obtained in almost all pacemakers connected to steroid-eluting lead systems, and in a significantly higher number of patients than when connected with nonsteroid leads systems.(ABSTRACT TRUNCATED AT 250 WORDS)

Aged↗
PubMed1994

Catheter-induced mechanical conduction block of right-sided accessory fibers with Mahaim-type preexcitation to guide radiofrequency ablation.

BACKGROUND: Accessory pathways originating at the tricuspid annulus that exhibit decremental antegrade conduction properties (Mahaim-type preexcitation) are amenable to radiofrequency (RF) current catheter ablation. However, a reliable and reproducible strategy for mapping and ablation of these fibers is lacking. METHODS AND RESULTS: Eleven patients with preexcited atrioventricular tachycardia involving a decrementally conducting antegrade accessory pathway underwent complete electrophysiological evaluation and subsequent attempts at RF catheter ablation. Mechanical conduction block at the subannular level of the atrial input to the accessory fiber was induced by catheter manipulation in 8 patients, in 2 of them during atrial fibrillation. RF current was delivered, after resumption of preexcitation, to the site of mechanical block during atrial pacing (n = 6) or atrial fibrillation (n = 2) and eliminated the accessory pathway in all 8 patients. In another patient, mechanical block was not observed, but ablation of the atrial accessory fiber insertion was achieved at the subannular level during atrioventricular tachycardia. The anatomic site of ablation along the tricuspid annulus was anterolateral (n = 1), lateral (n = 3), or posterolateral (n = 5). Failures were encountered in the first patient of the series in whom ablation attempts were directed at the ventricular insertion of the accessory fiber and in a patient in whom ablation of the atrial insertion was attempted at the supraannular level. Recurrence of preexcitation within 12 hours was observed in 5 of 6 patients in whom ablation had been achieved during atrial pacing. Eventually successful repeat sessions were performed the following day using a simplified ablation approach. Thus, a median of 5 RF pulses (range, 1 to 26) per accessory fiber eliminated conduction in 9 (82%) of the 11 patients in 1.9 +/- 0.9 sessions. During a follow-up of 9.5 +/- 2.3 months, preexcitation recurred in 1 patient. CONCLUSIONS: The atrial origin of accessory connections with Mahaim-type preexcitation is apparently confined to the anterolateral-to-posterolateral region of the tricuspid annulus. Mechanical conduction block in the atrial input to the accessory fiber induced at the subannular level by catheter manipulation provides an optimal marker to locate the ablation site, even during atrial fibrillation. To expose early recurrence of antegrade accessory pathway conduction, intermittent atrial pacing in the 12 hours after ablation is advisable; in cases of recurrence, a repeat procedure can readily be performed using just the ablation catheter advanced to the target site at the tricuspid annulus.

Adult↗
PubMed1994

Anatomic, electrical, and mechanical factors affecting bipolar endocardial electrograms. Impact on catheter ablation of manifest left free-wall accessory pathways.

BACKGROUND: The use of bipolar endocardial electrogram characteristics to guide radiofrequency (RF) current catheter ablation of accessory pathways (APs) has been advocated by several investigators. However, the influences of a varying anatomy of the AP and the atrioventricular groove, of different ablative approaches, and of RF current pulses preceding the final pulse have not been adequately addressed. METHODS AND RESULTS: Local bipolar endocardial electrograms were retrospectively analyzed in a uniform cohort of 62 consecutive patients with a single manifest AP located on the left free wall; in all patients, the AP had been ablated by a uniform approach with a single catheter advanced retrogradely toward the mitral annulus. Electrogram parameters assessed were the presence or absence of a presumed AP potential, the atrial-to-ventricular (A/V) amplitude ratio, the A-V interval, and the onset of delta wave to local ventricular activation (delta-V) interval. The AP location was classified on fluoroscopy as anterior, lateral, or posterior. Catheter stability was verified by comparing pre- and post-RF amplitudes of local atrial potentials. The ablation site was ventricular in 52 patients (group A) and atrial in 10 (group B). In group A, 26 APs (50%) required a single RF current pulse for ablation. These APs showed no anatomic predilection and no statistically significant differences in electrogram parameters from 24 APs that were ablated only after a median of three pulses had failed, suggestive of a wider ventricular insertion of the latter APs. A lower A/V ratio and a higher incidence of transient AP block found in the remaining 2 group A patients, who had anteriorly located APs requiring > 10 failed pulses, suggested an adverse anatomy of the A-V groove in that region. A stepwise multivariate logistic regression analysis revealed that the simultaneous presence of (1) a presumed AP potential, (2) an A/V ratio > or = 0.10, (3) an A-V interval < or = 40 milliseconds, and (4) a delta-V interval < or = 0 milliseconds was associated with a specificity of 94% and a positive predictive accuracy of 87% for an RF pulse to be successfully applied to the ventricular insertion to the AP. Compared with APs of group A, APs of group B were distinguished by unsuccessful ventricular pulses associated with a delta-V interval > 10 milliseconds in the presence of an A/V ratio > 0.33 (specificity of 97% and positive predictive accuracy of 82%), which is suggestive of a more epicardial ventricular insertion of these APs. CONCLUSIONS: The effect of anatomic variations of the AP and the A-V groove is reflected in the bipolar endocardial electrogram and needs to be considered in the approach to AP ablation. The stepwise inclusion of the four electrogram criteria introduced in this study may improve the efficacy of RF catheter ablation of a manifest left free-wall AP at its ventricular insertion. Whenever mapping cannot improve on a delta-V interval > 10 milliseconds despite apparently close contact with the mitral annulus ("good" A/V ratio), attempts at ablation are likely to be successful at the atrial aspect of the mitral annulus.

Adult↗