This study was performed to assess the influence of the cryoinjury on the dynamics of wavefronts and to determine whether they can convert ventricular fibrillation (VF) to ventricular tachycardia (VT) in fibrillating right ventricular (RV) of swines using an optical mapping system. A cryoinjury with a diameter of 12 mm was created on the epicardium of perfused RV of swines (n = 6) and optical mapping were taken from baseline until 10 minutes after the cryoinjury. Out of 35 cryoinjuries, the images were possible to be interpreted in 32. The optical action potential could not be observed in either the cryoinjury or peri-injury sites at 1 and 3 minutes, was observed in only the cryoinjury site at 5 minutes, and recovered in both sites at 10 minutes. The cycle length of the tachycardia was 135.9 +/- 23.6 msec at baseline, 176.2 +/- 79.3 msec at 1 minute, 187.6 +/- 97.9 msec at 3 minutes, 185.5 19.2 msec at 5 minutes, and 152.1 +/- 64.1 msec at 10 minutes. The cycle lengths at 1, 3, and 5 minutes after the cryoinjury were significantly more prolonged than that at baseline (p = 0.001, p = 0.006, p = 0.016). After the cryoinjury, the VF changed to VT in 9 (28.0%), and terminated in 2 (6.3%). These changes were observed mainly within 5 minutes after cryoinjury. The cryoinjury had anti-fibrillatory effects on the tissue with VF. This phenomenon was related to a decreasing mass and stabilizing wavefronts.
Ventricular Fibrillation/*physiopathology ; Tachycardia, Ventricular/*physiopathology ; Swine ; Heart Ventricles/*physiopathology/surgery ; Female ; Disease Models, Animal ; *Cryosurgery ; Animals

BACKGROUNDRadiofrequency catheter ablation (RFCA) has been established as an effective and curative therapy for ventricular tachycardia (VT) and severely symptomatic premature ventricular contraction (PVC) from the outflow tract in structurally normal hearts. This study aimed to investigate electrophysiologic characteristics and effects of RFCA for patients with idiopathic VT and symptomatic PVC originating from the valve annulus.

METHODSCharacteristics of body surface electrocardiogram (ECG) and endocardiogram in a successful RFCA target were analyzed in 16 patients with idiopathic VT and symptomatic PVC originating from the valve annulus. Additionally, the ECG characteristics of VT or PVC were compared with those of manifest Wolff-Parkinson-White (WPW) syndrome originating from the same site of origin in 15 patients.

RESULTSThirteen patients were successful, 2 recurrent and 1 failed. The recurrent cases underwent successful ablation the second time guided by the Ensite 3000 mapping system. In all patients with the WPW syndrome, the characteristics of QRS morphology were well matched with those of the VT and PVC that originated from corresponding sites of origin.

CONCLUSIONSRFCA is an effective curative therapy for VT and symptomatic PVC originating from the valve annulus. There are specific characteristics in ECG and the ablation site could be located by means of the WPW syndrome accessory pathway's algorithm.

Adult ; Aged ; Catheter Ablation ; methods ; Electrocardiography ; Female ; Humans ; Male ; Middle Aged ; Mitral Valve ; physiopathology ; surgery ; Tachycardia, Ventricular ; physiopathology ; surgery ; Ventricular Premature Complexes ; physiopathology ; surgery

BACKGROUNDThe aim of this study was to clarify the electrocardiographic characteristics of repetitive monomorphic ventricular tachycardia (RMVT) originating from the left ventricular outflow tract, and to describe the results of treatment with radiofrequency catheter ablation (RFCA).

METHODSRoutine 12-lead surface electrocardiography and electrophysiological studies were performed on 11 RMVT patients with no organic heart disease, who were subsequently treated with RFCA directed at targets identified by pace mapping.

RESULTSThe surface electrocardiogram QRS characteristics of RMVT included an atypical left bundle branch block and right axis deviation, with a low amplitude "rs" or "rS" pattern in lead I, an "rS" or "RS" pattern in V1, and a precordial R wave transition zone in V2 or V3. In 1 patient, a small S wave was observed in V5. Using pace mapping techniques, we selected the left coronary cusp as the ablation target. RMVT was eliminated in all 11 patients immediately after radiofrequency energy delivered. During a follow-up of 13 +/- 7 months, RMVT recurred in only 1 patient.

CONCLUSIONRMVT originating from the left ventricular outflow tract has specific electrocardiographic characteristics, and can be successfully and safely cured using RFCA directed at the left coronary cusp.

Adolescent ; Adult ; Catheter Ablation ; Electrocardiography ; Female ; Humans ; Male ; Middle Aged ; Tachycardia, Ventricular ; physiopathology ; surgery ; Treatment Outcome

Systemic sclerosis (SS) is a connective tissue disease and cardiac involvement is common. Primary cardiac involvement such as conduction system disturbances and arrhythmias can also occur. However, reports of sustained ventricular tachycardia (VT) are rare. We report a case of catheter ablation of sustained ventricular tachycardia in a patient with systemic sclerosis using a conventional mapping system. A 64-yr-old woman with a 10-yr history of SS was referred for management of her ventricular tachycardia. There was no structural abnormality in cardiac chambers. However, electrophysiologic study revealed electrical substrate of ventricular tachycardia which could be ablated with pacemapping and substrate mapping. This case demonstrated successful conventional mapping and catheter ablation in a hemodynamically unstable patient with SS.
*Catheter Ablation ; Electrocardiography ; Female ; Humans ; Middle Aged ; Scleroderma, Systemic/*complications/*diagnosis ; Tachycardia, Ventricular/*etiology/physiopathology/*surgery

OBJECTIVETo simplify the methods of transcatheter mapping and ablation in the pediatric patients with left posterior fascicular tachycardia.

METHODWhile in sinus rhythm, the fascicular potential can be mapped at the posterior septal region (1 - 2 cm below inferior margin of orifice of coronary sinus vein), which display a biphasic wave before ventricular wave, and exist equipotential lines between them. When the fascicular potential occurs 20 ms later than the bundle of His' potential, radiofrequency was applied. Before applying radiofrequency, catheter position must be observed using double angle viewing (LAO 45°RAO 30°), and it should be made sure that the catheter is not at His' bundle. If the electrocardiogram displays left posterior fascicular block, the correct region is identified and ablation can continue for 60 s. Electrocardiogram monitoring should continue for 24 - 48 hours after operation, and notice abnormal repolarization after termination of ventricular tachycardia. Aspirin [2 - 3 mg/(kg·d)] was used for 3 months, and antiarrhythmic drug was discontinued. Surface electrocardiogram, chest X-ray and ultrasound cardiography were rechecked 1 d after operation. Follow-up was made at 1 month and 3 months post-discharge. Recheck was made half-yearly or follow-up was done by phone from then on.

RESULTFifteen pediatric patients were ablated successfully, and their electrocardiograms all displayed left posterior fascicular block after ablation. None of the patients had recurrences during the 3 to 12 months follow-up period. In one case, the electrocardiogram did not change after applying radiofrequency ablation and the ventricular tachycardia remained; however, on second attempt after remapping, the electrocardiogram did change. The radiofrequency lasted for 90 seconds and ablation was successful. This case had no recurrences at 6 months follow-up.

CONCLUSIONTranscatheter ablation of the fascicular potential in pediatric patients with left posterior fascicular tachycardia can simplify mapping, reduce operative difficulty and produce a distinct endpoint for ablation.

Adolescent ; Bundle-Branch Block ; physiopathology ; surgery ; Catheter Ablation ; methods ; Child ; Electrocardiography ; Female ; Humans ; Male ; Tachycardia, Ventricular ; physiopathology ; surgery

PURPOSE: We hypothesized that Purkinje potential and their preferential conduction to the left ventricle (LV) posteroseptum during sinus rhythm (SR) are part of reentrant circuits of idiopathic left ventricular tachycardia (ILVT) and reentry anchors to papillary muscle. MATERIALS AND METHODS: In 14 patients with ILVT (11 men, mean age 31.5+/-11.1 years), we compared Purkinje potential and preferential conduction during SR with VT by non-contact mapping (NCM). If clear Purkinje potential(SR) was observed in the LV posteroseptum and the earliest activation site (EA) of preferential conduction at SR (EASR) was well matched with that of VT (EAVT), EASR was targeted for radiofrequency catheter ablation (RFCA). Also, the anatomical locations of successful ablation sites were evaluated by echocardiography in five additional patients. RESULTS: 1) All induced VTs exhibited clear Purkinje potential(VT) and preferential conduction in the LV posteroseptum. The Purkinje potential(VT) and EAVT was within 5.8+/-8.2 mm of EASR. However, the breakout sites of VT were separated by 30.2+/-12.6 mm from EAVT to the apical side. 2) Purkinje potential(SR) demonstrated a reversed polarity to Purkinje potential(VT), and the interval of Purkinje potential(SR)-QRS was longer than the interval of Purkinje potential(VT)-QRS (p<0.02) 3) RFCA targeting EASR eliminated VT in all patients without recurrence within 23.3+/-7.5 months, and the successful ablation site was discovered at the base of papillary muscle in the five additional (100%) patients. CONCLUSION: NCM-guided localization of EASR with Purkinje potential(SR) matches well with EAVT with Purkinje potential(VT) and provides an effective target for RFCA, potentially at the base of papillary muscle in patients with ILVT.
Adult ; Catheter Ablation ; Electrophysiology ; Female ; Humans ; Male ; Purkinje Fibers/*physiology ; Tachycardia, Ventricular/*physiopathology/surgery ; Ventricular Dysfunction, Left/*physiopathology/surgery ; Young Adult

To investigate an association between surface electrocardiographic (ECG) parameters and sustained ventricular tachycardia (VT) in children after repair of congenital heart disease (CHD), data were obtained and analyzed in three groups (group I, 7 postoperative patients with episode of sustained VT (4 tetralogy of Fallot (TOF), 2 double outlet right ventricle (DORV), 1 truncus arteriosus); group II, 14 children with postoperative TOF not associated with VT; group III, 14 normal children). Mean age at the onset of sustained VT was 129+/-77 months (range 60-232); mean age at corrective surgery, 44+/-33 months (range 10-102); mean follow-up period after surgery, 84+/-74 months (range 20-185); the duration from repair to the onset of sustained VT, range 1-185 months. Compared to group II and III, group I showed longer QRS duration (group I, 137+/-10 msec; group II, 114+/-22 msec; group III, 65+/-12 msec) and shorter corrected J to Tmax interval (group I, 209+/-24 msec; group II, 272+/-44 msec; group III, 249+/-18 msec). QT and corrected QT, J to Tmax interval, and their dispersions in group I and II are significantly different from those of group III. In conclusion, QRS duration and corrected J to Tmax interval could be helpful to predict ventricular tachycardia in postoperative CHD.
Adolescence ; Child ; Child, Preschool ; Electrocardiography ; Female ; Heart Defects, Congenital/surgery* ; Heart Defects, Congenital/physiopathology ; Human ; Infant ; Male ; Tachycardia, Ventricular/etiology*

OBJECTIVETo determine the feasibility and assess the validity of noncontact endocardial mapping to guide ablation of hemodynamically unstable or nonsustained ventricular tachycardia (VT).

METHODSNoncontact mapping permitted individual-beat analysis of ventricular arrhythmias. Three-dimensional electroanatomical mapping allowed detailed reconstruction of a chamber geometry and activation sequence. Eighteen hemodynamically unstable or nonsustained VTs were induced (cycle length: 336 ms +/- 58 ms) in 17 patients and mapped by noncontact mapping using an EnSite 3000 system performed for the guidance of catheter ablation.

RESULTSThree patients were mapped during premature ventricular complexes (PVCs) because sustained VT could not be induced. Analysis of the archived noncontact activation maps was performed to identify the exit site and/or the diastolic pathway of the VT reentry circuit. The endocardial exit sites 10 ms +/- 16 ms before QRS were defined in 9 right ventricular outflow tract (RVOT) and 5 ischemic VTs. The diastolic pathway was identified in 5 ischemic VTs. The earliest endocardial diastolic activity preceded the QRS onset by 60.1 ms +/- 42.6 ms. The earliest activation sites were identify in 3 patients with nonsustained VTs or PVCs. Radiofrequency current was applied around the exit site or to create a line of block across the diastolic pathway. Catheter ablation was performed in 17/18 (94%) VTs and 15/17 (88%) VTs was successfully ablated. Two (67%) of the three patients with non-sustained VTs were mapped and successfully ablated during PVCs. Catheter ablation was not performed in 1 patient (peri-Hisian VT) and was unsuccessful in 2 patients.

CONCLUSIONNoncontact endocardial mapping is able to be used to guide ablation of untolerated or nonsustained VTs.

Adult ; Catheter Ablation ; methods ; Electrophysiologic Techniques, Cardiac ; Feasibility Studies ; Female ; Humans ; Male ; Middle Aged ; Tachycardia, Ventricular ; physiopathology ; surgery

BACKGROUNDVerapamil-sensitive, idiopathic left ventricular tachycardia (ILVT) with right bundle branch block configuration and left-axis deviation is known to be due to re-entry mechanism but the exact nature of reentrant circuit in ILVT is not fully elucidated. Radiofrequency (RF) ablation was applied during ventricular tachycardia (VT) and termination of the VT or abolishing the inducibility of the tachycardia was used as an endpoint for successful RF. In this study, the left posterior fascicular block in surface electrocardiogram (ECG) was used as a new endpoint of ablation to cure ILVT.

METHODSElectrophysiological studies and radiofrequency ablation were performed in 39 consecutive patients [30 men, 9 women; age ranging from 10 to 64 years, mean (29 +/- 16) years] with verapamil-sensitive ILVT and structurally normal hearts. VT could be terminated by the intravenous administration of verapamil in all patients. The target site was the midseptum of LV where the earliest Purkinje potentials were recorded during VT. RF current was applied to the target site with or without late diastolic potential (LDP) during sinus rhythm in 37 patients and during VT in 2 patients to meet the ablation endpoint: the left posterior fascicular block in the surface ECG.

RESULTSThirty-seven patients with ILVT had been treated by RF ablation during sinus rhythm and two had been treated during VT. All of them met the endpoint of the left posterior fascicular block. Thirty-eight cases were symptom-free without medications during the follow-up period (range from 3 to 95 months, median 17 months). One patient developed a clinical recurrence and the left posterior fascicular block in surface ECG disappeared. The patient received another treatment. The endpoint was met and the procedure was successful.

CONCLUSIONSThe left posterior fascicular block in surface ECG used as an endpoint of RF ablation to treat ILVT is effective. It is important especially in those patients whose VT can not be induced or the inducible condition is unstable. The effective endpoint implied that the left posterior fascicle might be a critical part of the re-entrant circuit.

Adolescent ; Adult ; Catheter Ablation ; methods ; Child ; Diastole ; Electrocardiography ; Female ; Humans ; Male ; Middle Aged ; Tachycardia, Ventricular ; physiopathology ; surgery ; Verapamil ; therapeutic use

OBJECTIVETo explore the value of identifying slow conduction zone(SCZ) of idiopathic left ventricular tachycardia(ILVT) by electroanatomic mapping.

METHODSTwelve patients with ILVT were mapped by a 3-dimensional electroanatomic (EA) mapping system. Left posterior fascicular potential (PP) and the SCZ with diastolic potential (DP) in LV during sinus rhythm (SR) and ventricular tachycardia (VT) were mapped after a three-dimensional endocardial geometry of the left ventricular was established. Then we investigated the electrophysiological and anatomic characteristics of SCZ.

RESULTSEA mapping was successfully performed in 9 patients during SR and VT, and in 3 patients during VT. The SCZ with DP was located at the inferoposterior septum, and the length of the SCZ was (25.1 ± 2.2) mm with a conduction velocity of (0.08 ± 0.01) m/s. There was no difference in these parameters between patients during SR and VT (P > 0.05). There was one area with PP located at the posterior septum. The areas with both DP and PP were found in 9 patients during SR and VT. In addition, this area was coincided with such area during VT during SR and radiofrequency ablation targeting the site within the area abolished VT in all patients.

CONCLUSIONSThe ILVT substrate within the junction area of the SCZ and the posterior fascicular can be identified by EA mapping and used to guide the ablation of ILVT.

Adult ; Catheter Ablation ; methods ; Electrocardiography ; methods ; Female ; Follow-Up Studies ; Heart Conduction System ; physiopathology ; Heart Ventricles ; physiopathology ; Humans ; Male ; Middle Aged ; Tachycardia, Ventricular ; physiopathology ; surgery