Catheter Ablation of Stable and Unstable Ventricular Tachycardia
Catheter Ablation of Stable and Unstable Ventricular Tachycardia
Introduction: A reentrant circuit within an area of abnormal myocardium is suspected as the origin of ventricular tachycardia (VT) in patients with arrhythmogenic right ventricular dysplasia (ARVD).
Objectives: To examine the relationship between the reentrant circuits of VT and the abnormal electrograms in ARVD, and to assess the feasibility of a block line formation in the reentrant circuit isthmus utilizing electroanatomical mapping system (CARTO) guidance.
Methods and Results: An electrophysiological study and catheter ablation (CA) were performed in 17 ARVD patients (13 men, 47 ± 17 year) using CARTO. Endocardial mapping during sinus rhythm demonstrated electrogram abnormalities extended from the tricuspid annulus (TA) or the right ventricular outflow tract in 16 of 17 patients. In 13 hemodynamically stable VTs, the reentrant circuits and critical slow conduction sites for the CA were investigated during VTs. The entire macro-reentrant pathway was identified in 6/13 stable VTs (figure-of-8 in 4, single loop in 2). In the remaining seven VTs, a focal activation pattern was found in four and an unidentifiable pattern in three. CA successfully abolished all the macro-reentrant and focal tachycardias, however, not effective in three unidentifiable VTs. In the 13 cases with unstable VT, the linear conduction block zone was produced between the sites with abnormal electrograms and the TA. Ultimately, 23/26 VTs (88%) became noninducible after the CA. During follow-up (26 ± 15 months), 13/17 patients remained free from any VT episodes.
Conclusions: CARTO is useful for characterizing the anatomical and electrophysiological substrates, and for identifying the optimal ablation sites for VT associated with ARVD.
Arrhythmogenic right ventricular dysplasia (ARVD) is a disease of unknown etiology characterized by right ventricular (RV) arrhythmias and an enlarged and/or asynergic RV due to fibrofatty atrophy of the myocardium.
A reentrant circuit within the area of the abnormal myocardium is suspected as the origin of the ventricular tachycardia (VT), and several studies have demonstrated the critical slow conduction zone of the pathway that exhibits electrophysiological characteristics such as mid-diastolic potentials during VT and/or the concealed entrainment phenomenon with an identical post-pacing interval to the VT cycle length. In the previous studies, however, the areas investigated were limited and exact mapping of the entire reentrant circuit had never been reconstructed by their conventional approach.
The electroanatomical mapping system (CARTO) is expected to resolve the unreliable aspects of the conventional mapping procedure by proving the exact information of both the location and electrical activity at the sites where the roving catheter is located. Under this technology, the precise and detailed mapping of the reentrant pathway may be possible.
On the other hand, CARTO is not thought to be beneficial for nonsustained or hemodynamically unstable VT, because site-by-site roving catheter manipulation is required during the VT. However, several recent studies have reported the usefulness of "substrate mapping" during sinus rhythm for identifying the potential reentrant circuit isthmuses in patients with ischemic heart disease. This unique procedure may become more effective in ARVD patients with "unmappable" VT in order to detect the substrates, when CARTO is used for exact mapping of the RV during sinus rhythm.
The aim of the present study was to (1) assess the reliability of CARTO for characterizing the entire reentrant circuit and/or responsible substrate for reentry, and (2) test the feasibility of CARTO-guided catheter ablation (CA) during VT or sinus rhythm.
Introduction: A reentrant circuit within an area of abnormal myocardium is suspected as the origin of ventricular tachycardia (VT) in patients with arrhythmogenic right ventricular dysplasia (ARVD).
Objectives: To examine the relationship between the reentrant circuits of VT and the abnormal electrograms in ARVD, and to assess the feasibility of a block line formation in the reentrant circuit isthmus utilizing electroanatomical mapping system (CARTO) guidance.
Methods and Results: An electrophysiological study and catheter ablation (CA) were performed in 17 ARVD patients (13 men, 47 ± 17 year) using CARTO. Endocardial mapping during sinus rhythm demonstrated electrogram abnormalities extended from the tricuspid annulus (TA) or the right ventricular outflow tract in 16 of 17 patients. In 13 hemodynamically stable VTs, the reentrant circuits and critical slow conduction sites for the CA were investigated during VTs. The entire macro-reentrant pathway was identified in 6/13 stable VTs (figure-of-8 in 4, single loop in 2). In the remaining seven VTs, a focal activation pattern was found in four and an unidentifiable pattern in three. CA successfully abolished all the macro-reentrant and focal tachycardias, however, not effective in three unidentifiable VTs. In the 13 cases with unstable VT, the linear conduction block zone was produced between the sites with abnormal electrograms and the TA. Ultimately, 23/26 VTs (88%) became noninducible after the CA. During follow-up (26 ± 15 months), 13/17 patients remained free from any VT episodes.
Conclusions: CARTO is useful for characterizing the anatomical and electrophysiological substrates, and for identifying the optimal ablation sites for VT associated with ARVD.
Arrhythmogenic right ventricular dysplasia (ARVD) is a disease of unknown etiology characterized by right ventricular (RV) arrhythmias and an enlarged and/or asynergic RV due to fibrofatty atrophy of the myocardium.
A reentrant circuit within the area of the abnormal myocardium is suspected as the origin of the ventricular tachycardia (VT), and several studies have demonstrated the critical slow conduction zone of the pathway that exhibits electrophysiological characteristics such as mid-diastolic potentials during VT and/or the concealed entrainment phenomenon with an identical post-pacing interval to the VT cycle length. In the previous studies, however, the areas investigated were limited and exact mapping of the entire reentrant circuit had never been reconstructed by their conventional approach.
The electroanatomical mapping system (CARTO) is expected to resolve the unreliable aspects of the conventional mapping procedure by proving the exact information of both the location and electrical activity at the sites where the roving catheter is located. Under this technology, the precise and detailed mapping of the reentrant pathway may be possible.
On the other hand, CARTO is not thought to be beneficial for nonsustained or hemodynamically unstable VT, because site-by-site roving catheter manipulation is required during the VT. However, several recent studies have reported the usefulness of "substrate mapping" during sinus rhythm for identifying the potential reentrant circuit isthmuses in patients with ischemic heart disease. This unique procedure may become more effective in ARVD patients with "unmappable" VT in order to detect the substrates, when CARTO is used for exact mapping of the RV during sinus rhythm.
The aim of the present study was to (1) assess the reliability of CARTO for characterizing the entire reentrant circuit and/or responsible substrate for reentry, and (2) test the feasibility of CARTO-guided catheter ablation (CA) during VT or sinus rhythm.
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