Noncontact Mapping And Catheter Ablation Of Complex Tachyarrhythmias

Part Ⅰ Noncontact Mapping and Catheter Ablation ofAtrial Tachycardias Arising from Crista TerminalisPurpose: Noncontact mapping is a novel, three dimensional mapping system. We used it in the present study to identify the anatomic region of the crista terminalis (CT), to trace the origin of the atrial tachycardias (AT) and to guide catheter ablation of ATs from the CT.Methods: Nine consecutive patients with recurrent palpitations were included in the study. ATs with the earliest activation in the high right atrium were induced during electrophysiological study. The geometry of the right atrium was then created and the conduction block area was analyzed both in sinus rhythm and during right atrial pacing at the drive length of 250ms at sites of posterior wall near CSo and anterior wall. Autofocus mapping was used to find the earliest activation point and the wave front propagation mode of both sinus rhythm and the ATs. Guiding ablation of ATs was made thereafter.Results: Sustained AT could be induced in all 9 patients by high right atrium programmed electrical stimulation, and the mean cycle length was 344 ± 55ms. All ATs could be terminated by burst stimuli and intravenous adenosine triphosphate bolus injection. CT was identified as a short perpendicular conduction blockline near superior vene cava in the lateral wall of the right atrium during pacing at a cycle length of 250ms both at the posterior septal area and the anterior wall. The earliest activation point of all ATs was found to be in the CT with a mean distance of 1.8 ±0.6 cm from sinus breakout point. After a mean of 4. 2 ± 3. 5 RF deliveries, all ATs became non-inducible. No sinus arrest and sino-atrial block happened during RF delivery and no tachycardia recurred after a mean follow-up of 23. 3 + 4. 7 months.Conclusions: The noncontact mapping system can help you to easily identify the anatomic region of CT and to quickly trace the origin of AT, and the guiding ablation can reduce the risk of inadvertent damage to sinus node and sino-atrial conduction. The whole chamber mapping makes it easier to disclose the mechanism of CT-AT.Part II Noncontact Mapping and Radiofrequency Catheter Ablation of Intraatrial Dual-loop ReentrantTachycardiasPurpose: To illustrate the mechanisms of intra-atrial dual-loop tachycardia and its catheter ablation methods. Methods: 3 cases, all female, age from 41 to 66 years old, had the history of tachycardia for 6 months to 10 years. Case 1 had atrial septal defect repairment 22 years before, case 2 had no structural heart disease and case 3 had idiopathic dilatedcardiomyopathy. 9 French baloon catheter was advanced via left femoral vein to the right atrium and deployed at the level between His bundle and coronary sinus. Heparin was used to keep ACT (activative coagulation time) level around 250ms during the procedure.8 French deflectable catheter was inserted through right femoral vein to make geometry of right atrium. Complete tachycardia mapping was performed in the right atrium with noncontact mapping system (EnSite 3000), followed by linear radiofrequency ablation of the narrowest part of each complete loop.Results: 2 different tachycardias could be induced in each of 3 cases. All cases had clockwise cavotricuspid isthmus dependent atrial flutter. In addition to that, case 1 had atrial tachycardia going around atriotomy scar counter-clockwisely, case 2 around the upper part of crista terminalis clockwisely and case 3 around scar tissue clockwisely. Linear ablation was done both in cavotricuspid isthmus and critical isthmus of atrial tachycardia under the guidance of EnSite 3000 guiding system. No tachycardia could be induced after the procedure. There were no recurrences after follow-up of 27-36 months. Conclusions: Dual-loop atrial reentrant tachycardia can occur both in diseased atrium and nondiseased atrium. Noncontact mapping is a good way for such tachycardias not only for its mapping property but also for its guiding system. Linear ablation should be done in two isthmuses in these cases. Part III Further Insight i...