-
[show abstract]
[hide abstract]
ABSTRACT: It is pointed out by using the IRDO treatment of Jesaitis et al. that the failure of the CNDO/2 method in predicting the acidity difference between toluene and β-picoline has its reason in the incorrect handling of the nitrogen lone pair. To predict correctly the relative acidity of β-picoline, it is necessary and sufficient to include only those NDDO terms into the IRDO calculation which contain interactions with the nitrogen. The most important interactions are those between the nitrogen and the three centers of the heterocycle which take over a large part of the negative charge in the corresponding β-delocalized carbanion.
International Journal of Quantum Chemistry 10/2004; 9(5):917 - 922. · 1.36 Impact Factor
-
[show abstract]
[hide abstract]
ABSTRACT: The focal origin of ectopic atrial tachycardia (EAT) is occasionally located in the superoparaseptal region adjacent to the bundle of HIS. Radiofrequency catheter ablation (RFCA) of EAT in this anatomic location implies the potential hazard of adverse impairment of the AV conduction. Therefore, careful precise mapping is mandatory. Subthreshold stimulation as defined as the delivery of noncaptured low energy pulses has been introduced as an additional mapping technique for slow pathway ablation in the setting of AV nodal reentrant tachycardia and other reentrant tachycardia. A patient with a right superoparaseptal EAT focus, in which subthreshold stimulation (STS) could determine the site of successful subsequent RFCA is described. During STS with EAT termination no AV conduction disturbances, junction-escape rhythms or atrial capture could be recorded. Thus STS may be used as an additional mapping tool to identify successful ablation sites in EAT.
Pacing and Clinical Electrophysiology 10/2001; 24(9 Pt 1):1430-2. · 1.35 Impact Factor
-
[show abstract]
[hide abstract]
ABSTRACT: Ablation catheters with multiple long coiled electrodes have been recently developed to induce continuous linear lesions for the treatment of atrial fibrillation. The efficacy and safety of ablation catheters with multiple long coiled electrodes has not been evaluated. The aim of the present in vivo study was to investigate the influence of saline irrigation on lesion dimensions and coagulum formation during RF current ablation using those ablation catheters. In 14 anesthetized sheep, the thigh muscle was prepared as a cradle and filled with heparinized blood (37 degrees C). The quadripolar coiled ablation catheter (electrode length 7 mm, electrode distance 2 mm) was placed parallel to the muscle with standardized 10-g contact pressure. RF current energy was delivered sequentially temperature-(70 degrees C) or power-controlled (10, 20, 30, or 40 W) with additional irrigation of the electrode (10 mL/min normal saline) for 90 seconds. Forty-two of 129 RF current lesions were induced by temperature-controlled and 87 by irrigated ablation. Except for three lesions following low energy irrigated application (10 W), all lesions were continuous. Significantly larger lesions following irrigated RF current applications were produced with a power output of 30 W (depth 0.74 +/- 0.13 cm, width 0.78 +/- 0.13 cm) and 40 W (depth 0.75 +/- 0.16 cm, width 0.92 +/- 0.28 cm) as compared to 20 W (depth 0.47 +/- 0.13 cm, width 0.82 +/- 0.22 cm). Coagulum formation adherent to the electrode was exclusively observed following 18 of 42 nonirrigated RF current ablations. In conclusion, irrigated coiled ablation electrodes induce continuous linear lesions with a power output of 20-40 W. The risk of coagulum formation at the coiled electrode can be avoided by irrigation.
Pacing and Clinical Electrophysiology 07/2001; 24(6):933-8. · 1.35 Impact Factor
-
[show abstract]
[hide abstract]
ABSTRACT: This randomized prospective study sought to assess the value of slow pathway (SP) mapping and ablation guided by subthreshold stimulation (STS) in comparison with a strategy based on conventional criteria.
Previous studies have demonstrated that STS can be used as a highly specific and sensitive marker for successful SP ablation in the setting of atrioventricular nodal re-entrant tachycardia (AVNRT). Nonetheless, thus far this mapping strategy has not been investigated in contrast with the conventional approach.
One hundred patients with sustained AVNRT were included. Fifty patients (group A) were randomly assigned to endocardial mapping and SP ablation using currently established criteria. In the other 50 patients (group B), SP ablation was guided by STS mapping. In group B patients, only radiofrequency current (RFC) was applied if additionally constant current STS (up to 5 mA) during AVNRT interrupted the tachycardia due to selective block within the SP.
Termination of AVNRT without apparent capture was observed during STS in 47 of 50 group B patients (94%). In all cases, this effect was indicative for successful subsequent SP ablation. The mean number of RFC pulses required for successful SP ablation was significantly lower in patients assigned to the STS-guided strategy (1.6 +/- 1.3 vs. 3.9 +/- 3.4; p = 0.0003). Similarly, the mean procedure duration was shorter in the STS group (156.9 +/- 33.5 vs. 173.2 +/- 49.7 min; p = 0.0221); the fluoroscopy time was comparable between both groups (14.1 +/- 8.7 vs. 16.9 +/- 10.6 min; p = 0.1278).
Subthreshold stimulation is an effective method for detection of target sites for selective SP ablation. This technique helps to minimize the number of RFC pulses without prolongation of the overall procedure and fluoroscopy time required for SP ablation.
Journal of the American College of Cardiology 06/2001; 37(6):1645-50. · 14.16 Impact Factor
-
[show abstract]
[hide abstract]
ABSTRACT: Electroanatomical Mapping (CARTO) allows a tridimensional localization of ectopic atrial tachycardia (EAT). No standardized recommendation exists for annotation the local activation time in EAT using this new technology. In the present study bipolar local electrogram were used for CARTO guided RF ablation of EAT. In comparison the same maps were retrospectively analyzed by annotation the unipolar local electrogram.
In 15 consecutive patients (6m, 51+/-14 y) with EAT CARTO mapping was guided by annotation the earliest onset of the bipolar local electrogram. Following successful RF ablation the obtained EAT maps were subsequently evaluated by annotation of the earliest steepest negative intrinsic deflection of the unipolar local electrogram. Both CARTO maps were compared with regard to the region of focal EAT origin.
RF ablation of all 15 EAT foci guided by annotation the bipolar local electrogram with CARTO was successful with a median of 3 [1-18] pulses and a median fluoroscopy time of 10 min [4-25]. All but one focus was located in the right atrium: posterior to posteroinferior region of the terminal crest in 6, septal region in 5, anterior superior region in 3 cases. One left sided EAT was located at the septum. The bipolar CARTO map demonstrated a "small territory" location of earliest activation (extension of the focus < or =0.4 cm(2)) in 14 out of 15 patients. In a single patient the bipolar map showed several sites of earliest local activation (extension >0.4 cm(2)). On the other side the retrospectively achieved unipolar maps demonstrated an extended region of earliest local activation in 6 out of 15 patients (>0.4 cm(2)).
CARTO maps of EAT by annotation the earliest onset of the bipolar local electrogram provide an efficacious guide for location the focal origin. Extended regions of earliest local activation in EAT might be rather determined by annotation the unipolar in comparison to the bipolar local electrogram.
Journal of Interventional Cardiac Electrophysiology 04/2001; 5(1):101-7. · 1.17 Impact Factor
-
[show abstract]
[hide abstract]
ABSTRACT: Radiofrequency catheter (RF) ablation aiming the complete conduction block of the cavotricuspid isthmus has become treatment of choice for common type atrial flutter. Different approaches to guide the ablation procedure are used. For the conventional approach multipolar catheters in the right atrium and in the coronary sinus are required to detect the induction of conduction block via the isthmus. RF current is applied starting at the ventricular site of the cavotricuspid isthmus under fluoroscopic control to recognise dislocation of the ablation catheter and to avoid potential complications. Three-dimensional electroanatomic (CARTO) activation mapping can be helpful to guide atrial flutter ablation. By the help of a magnetic sensor, embedded in the tip of the mapping catheter, a virtual frame of the cavotricuspid isthmus will be reconstructed. The middle region between the virtual septal and posterolateral border of the cavotricuspid isthmus will be targeted for the ablation lesion line. Both approaches have been shown to be associated with a high acute success rate and a low recurrence rate. The major difference is that the CARTO system leads to a substantial reduction of fluoroscopic time required for atrial flutter ablation. Thus, CARTO-guided ablation directed at the cavotricuspid isthmus represent a modern method for rapid and successful treatment of common-type atrial flutter with low radiation exposure. (Fig. 4, Ref. 16.)
Bratislavske lekarske listy 02/2001; 102(9):385-9. · 0.40 Impact Factor
-
[show abstract]
[hide abstract]
ABSTRACT: Three-dimensional electroanatomic (CARTO) activation mapping of the cavotricuspid isthmus can be helpful to guide atrial flutter ablation, but to date has not been investigated in comparison to conventional strategies. The aim of the present study was to assess the efficacy of the CARTO navigation system, especially with respect to the fluoroscopy time required for successful atrial flutter ablation.
Eighty patients with recurrent common-type atrial flutter were randomly assigned to temperature-controlled radiofrequency (RF) catheter ablation, either guided by conventional criteria (group 1) or additionally oriented on electroanatomic mapping (group 2). In all patients, similar multipolar catheters were inserted into the coronary sinus and placed at the tricuspid annulus, respectively. In group 2, positioning of the mapping electrode and delivery of RF pulses within the cavotricuspid isthmus was mainly oriented on the CARTO map to achieve the most linear and continuous RF lesions. Abolition of intra-atrial conduction verified by conventional criteria (group 1) and electroanatomic mapping (group 2) could be verified in all patients. The overall number of RF pulses (group 1: 16.7+/-6.5; group 2: 13.2+/-5.3) and mean procedure duration (group 1: 172.5+/-47.4 min; group 2: 169.3+/-47.3 min) were not different between the two groups, but mean fluoroscopy time was significantly shorter when the CARTO technology was used (group 1: 29.2+/-9.4 min; group 2: 7.7+/-2.8 min; P = 0.0001). Recurrence of atrial flutter was observed in 3 (9%) patients in each group after a mean follow-up of 8.5+/-2.8 months.
Atrial flutter can be abolished effectively using the conventional technique as well as oriented on electroanatomic mapping. However, overall X-ray exposure can be significantly reduced by the CARTO-guided approach without prolongation of procedure duration.
Journal of Cardiovascular Electrophysiology 12/2000; 11(11):1223-30. · 3.06 Impact Factor
-
[show abstract]
[hide abstract]
ABSTRACT: Recurrent ventricular tachycardia in the setting of remote myocardial infarction are frequently resistant to antiarrhythmic drug treatment. Endocardial mapping and ablation is feasible in case of hemodynamically tolerable and reproducibly inducible forms. Identification of critical components of the reentrant circuit is mainly guided by entrainment mapping and the analysis of the post-pacing interval. The emergence of multiple types of ventricular tachycardia is a common limitation of the procedure. Ventricular tachycardia can be acutely abolished by radiofrequency current ablation in 60-70% of cases when only single forms are present. This success rate is substantially lower in case of multiple tachycardia morphologies. The incidence of tachycardia recurrences varies from 20-30%. The overall mortality during follow-up is increased due to progressive heart failure and the occurrence of rapid ventricular tachyarrhythmias. Catheter ablation has been shown to be a useful tool for the treatment of clusters of ventricular tachycardia following implantation of a cardioverter-defibrillator. Furthermore, this method can be life-saving in the setting of incessant forms. Currently, catheter ablation represents an adjunctive treatment to antiarrhythmic drugs and the implantation of a cardioverter-defibrillator. Improvement of mapping and ablation technologies may help to further increase the efficacy of this treatment strategy in the near future.
Zeitschrift für Kardiologie 02/2000; 89 Suppl 3:161-70. · 0.97 Impact Factor
-
[show abstract]
[hide abstract]
ABSTRACT: Induction of complete bidirectional conduction block via the posterior isthmus of the right atrium is introduced as a standard endpoint for catheter ablation of atrial flutter. The present study sought to investigate the impact of changes in P wave duration and morphology detected by the surface ECG during coronary sinus and posterolateral right atrial stimulation as a marker for conduction block. Morphology and duration changes of the paced P wave before and after radiofrequency catheter (RFC) ablation were estimated in 22 patients referred for ablation of atrial flutter. We looked for a morphology change of the terminal portion in the 12-lead ECG and an increment of P wave duration. In 16 of 22 patients in whom atrial flutter ablation resulted in a complete bidirectional block, the conduction block was unidirectional in 4 patients and conduction times remained unchanged in 2 patients. After induction of complete bidirectional block a change of the terminal portion of the P wave towards a more positive morphology in one or more inferior leads was detected in 14 (88%) of 16 patients during coronary sinus stimulation and in 15 (94%) of 16 patients during posterolateral right atrial stimulation. These changes were predominantly observed in the inferior leads. Positive morphology changes of the terminal P wave portion in the inferior leads indicating conduction block with a sensitivity of 86% and a specificity of 100% were observed. An increment of 10 ms or more in P wave duration indicates conduction block with a specificity of 100% and a sensitivity of 67%. There was a significantly larger increment of P wave duration during coronary sinus (CS) stimulation compared to posterolateral right atrial stimulation (38 +/- 21 vs 16 +/- 21 ms). The analysis of P wave duration and morphology in the inferior leads of the surface ECG is a reliable tool to assess the intraatrial conduction after atrial flutter ablation. Different conduction during coronary sinus and posterolateral right atrial pacing may cause a different P wave duration after ablation.
Pacing and Clinical Electrophysiology 11/1999; 22(10):1457-65. · 1.35 Impact Factor
-
[show abstract]
[hide abstract]
ABSTRACT: Previous retrospective studies could find a predominant incidence of coronary sinus (CS) anomalies in patients with accessory pathways and a characteristic anatomy of the CS ostium in patients with atrioventricular nodal reentrant tachycardias (AVNRT).
In the present prospective study, CS angiograms were prospectively performed to analyze the incidence of CS anomalies and to measure the diameters of the CS ostium.
The study included patients referred for electrophysiologic study and catheter ablation of various tachyarrhythmias. The anatomy of the CS and its side branches was visualized [left anterior oblique (LAO) 30 degrees, right anterior oblique (RAO) 30 degrees] by retrograde angiography in 204 consecutive patients (82 women, 122 men, age 45 +/- 15 years); of these, 120 presented with 123 accessory pathways (45 left-sided, 33 right-sided, 45 septal). The diagnosis in the remaining patients was atrioventricular nodal reentrant tachycardia in 43 cases, atrial tachycardia or atrial fibrillation in 12, and ventricular tachycardia in 15. In 14 patients, the indication for the electrophysiologic study was an unexplained syncope. The CS angiogram was evaluated for anomalies and the size of the CS ostium was manually measured in both projections.
Anomalies of the CS defined as diverticula, persistent left superior vena cava, or enlarged CS ostia were found in 18 patients (9%). Of those, CS diverticula were found in nine patients, all with a posteroseptal or left posterior manifest accessory pathway, which was abolished within the neck of the diverticulum in seven patients and at the posteroseptal tricuspid annulus in two patients. Persistence of the left superior vena cava was found in five patients, four had atrioventricular reentrant tachycardia secondary to five accessory pathways (left free wall in four, right midseptal in one), and one patient had atrioventricular nodal reentrant tachycardia (AVNRT). Enlargement of the CS ostium of > 25 mm width was detected in nine patients (5%), of whom four had AVNRT. However, the width of the CS ostium generally did not differ significantly between patients with AVNRT (LAO: 14.4 +/- 5.6; RAO 9.3 +/- 2.4 mm) compared with the control group (LAO 13.4 +/- 4.1; 8.2 +/- 1.9 mm).
Anomalies of the CS as diverticula, persistent superior vena cava, or enlargement of the CS ostium are predominantly found in patients with accessory pathway-related tachycardias. Diverticula of the proximal CS were found in 7% of patients with accessory pathways; in these cases, ablation succeeded mostly by radiofrequency (RF) current delivery in the neck of the diverticulum. Enlargement of the CS ostium was more often seen in patients with AVNRT than in all other patients. However, in general the measurements of the coronary sinus ostium did not significantly differ in patients with AVNRT compared with the control group.
Clinical Cardiology 09/1999; 22(8):537-43. · 2.15 Impact Factor
-
Pacing and Clinical Electrophysiology 07/1999; 22(6 Pt 1):947-9. · 1.35 Impact Factor
-
[show abstract]
[hide abstract]
ABSTRACT: Catheter ablation orientated on the induction of a functional intraatrial block within the posterior isthmus of the tricuspid annulus has been shown to effectively abolish atrial flutter. In order to improve and simplify the current technique, a strategy based on an electrode catheter for combined right atrial and coronary sinus mapping and stimulation was explored prospectively. Twenty-four consecutive patients referred for catheter ablation of recurrent type I atrial flutter were included. A steerable 7 Fr catheter (Medtronic/Cardiorhythm) composed of two segments with 20 electrodes was used for right atrial and coronary sinus activation mapping and stimulation. Multiple steering mechanisms allowing intubation and positioning of the distal part within the coronary sinus were incorporated into the device. Adequate positioning of the mapping catheter was achieved solely via a transfemoral approach in all patients after 7.7 +/- 4.6 minutes, providing stable electrogram recordings during the entire ablation procedure. Radiofrequency current ablation (16.3 +/- 9.6 pulses) caused a significant bidirectional increase of the mean intraatrial conduction times via the posterior isthmus irrespective to the stimulation interval. Significant changes of intraatrial conduction properties were induced during ablation in 22 of 24 patients (bidirectional block: n = 18, unidirectional block: n = 3, conduction delay: n = 1, unchanged conduction: n = 2). Following ablation atrial flutter was noninducible in all patients. Twenty-two of 24 patients (92%) remained free of atrial flutter episodes during a follow-up of 12.5 +/- 5.7 months. Two of six patients without a bidirectional conduction block had a recurrence of atrial flutter. Atrial flutter ablation guided by the induction of an intraatrial conduction block can be effectively performed with this novel strategy for combined mapping of the posterior tricuspid isthmus, including coronary sinus and right atrial free wall. This transfemoral approach has a high accuracy with respect to the detection of radiofrequency current-induced changes of intraatrial conduction patterns.
Pacing and Clinical Electrophysiology 06/1999; 22(5):750-8. · 1.35 Impact Factor
-
[show abstract]
[hide abstract]
ABSTRACT: 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.
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).
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.
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.
Herz 07/1998; 23(4):269-79. · 0.92 Impact Factor
-
DMW - Deutsche Medizinische Wochenschrift 06/1998; 123(19):599-603. · 0.53 Impact Factor
-
Der Internist 01/1998; 39(1):33-7. · 0.30 Impact Factor
-
[show abstract]
[hide abstract]
ABSTRACT: The distribution pattern of perioperative complications of coronary artery bypass graft surgery (CABG) is currently changing, due to the fact that it has become a routine operation with an increasing proportion of patients older than 70 years. Supraventricular and ventricular tachyarrhythmias are among the most commonly observed postoperative adverse events following CABG. The aim of this review is to give an update on epidemiology and mechanisms of postoperative arrhythmias and to present current diagnostic tools and therapeutic strategies.
The Thoracic and Cardiovascular Surgeon 11/1997; 45(5):232-7. · 0.88 Impact Factor
-
[show abstract]
[hide abstract]
ABSTRACT: CASE REPORT: This case presents a 31-year-old male patient with anomalous origin of the left coronary artery from the pulmonary trunc. First symptom of the disease was a survived sudden cardiac death. Subsequent angiographic and echocardiographic studies demonstrated the anomalous origin of the left coronary artery from the pulmonary artery. There were no signs of prior myocardial infarction. After reimplantation of the anomalous originating left coronary artery no myocardial ischemia could be detected in the thallium-201 myocardial imaging, which was present before surgical correction. In this case myocardial ischemia was the only potential triggering mechanism responsible for the sudden cardiac death, which was no longer detectable after surgical correction. Therefore no additional pharmacological and nonpharmacological antiarrhythmic treatment was initiated. CONCLUSION: In rare cases the first manifestation of Bland White Garland syndrome in the adult patient could be sudden cardiac death due to ventricular fibrillation.
Medizinische Klinik 08/1997; 92(7):447-51. · 0.34 Impact Factor
-
[show abstract]
[hide abstract]
ABSTRACT: 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.
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.
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.
Journal of Cardiovascular Electrophysiology 05/1997; 8(4):371-6. · 3.06 Impact Factor
-
[show abstract]
[hide abstract]
ABSTRACT: The present study sought to investigate the role of subthreshold stimulation in patients with atrioventricular node reentrant tachycardia (AVNRT) undergoing catheter ablation of the slow pathway.
Subthreshold stimulation applied to right atrial sites has been demonstrated to terminate AVNRT but has not been correlated with the effects of radiofrequency current delivery to the area of the slow pathway.
Eighteen patients with common AVNRT were prospectively included in the study. Sustained AVNRT was reproducibly inducible in all patients (cycle length 334 +/- 58 ms). Anatomic and electrogram guided mapping of the slow pathway was started posteroseptally and continued to more midseptal sites if required. Subthreshold stimulation (3 s, up to 5 mA) during induced AVNRT was performed at each site eligible for slow pathway ablation until termination of AVNRT or capture was observed. Irrespective of the effect of subthreshold stimulation, radiofrequency current was delivered at each site after exclusion of catheter dislocation.
Termination of AVNRT due to block of the anterograde slow pathway induced by subthreshold stimulation occurred without apparent capture in 15 of 18 patients. This phenomenon was exclusively observed at successful posteroseptal to midseptal ablation sites. Subthreshold stimulation was not successful at any of 30 target sites with ineffective radiofrequency current delivery. Thus, subthreshold stimulation identified successful target sites with 83% sensitivity and 100% specificity. Atrioventricular node reentrant tachycardia was abolished in all patients after a median of two (range one to nine) radiofrequency current applications.
Subthreshold stimulation delivered to the region of the slow pathway terminates AVNRT with high safety and efficacy. High sensitivity and specificity for prediction of the effect of radiofrequency current application suggest that subthreshold stimulation may become a new tool for identifying target sites for slow pathway ablation.
Journal of the American College of Cardiology 03/1997; 29(2):408-15. · 14.16 Impact Factor
-
[show abstract]
[hide abstract]
ABSTRACT: 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.
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.
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.
Circulation 09/1996; 94(3):376-83. · 14.74 Impact Factor
