Comparison between novel and standard high-density 3D electro-anatomical mapping systems for ablation of atrial tachycardia.

Ultra-high-density mapping allows very accurate characterization of circuits/mechanisms in atrial tachycardia (AT). Whether these advantages will translate into a better procedural or long-term clinical outcome is unknown. Sixty consecutive AT ablation procedures using ultra-high-density mapping (Rhythmia™, group 1) were retrospectively compared to 60 consecutive procedures using standard high-density mapping (Carto/NavX™, group 2) (total 209 AT, 79% left AT). A higher number of maps were performed in group 1 (4.8 ± 2.5 vs 3.2 ± 1.7, p = 0.0001) with similar acquisition duration (12 ± 5 vs 13 ± 6 min per map, p = ns), although with a greater number of activation points (10,543 ± 5854 vs 689 ± 1827 per map, p < 0.0001). AT location remained undetermined in 5 AT in group 1 vs 10 (p = 0.1). Mechanism remained undetermined in 5 AT from group 1 vs 11 (p = 0.06). Acute complete success was achieved in 77%, in both groups. At 1-year follow-up, AT recurred in 37% in group 1 vs 50% in group 2 (p = 0.046). There are less long-term recurrences after AT ablation using ultra-high-density mapping system compared to standard high-density 3D mapping, possibly because of a better comprehensive approach of AT mechanisms.

Crossroads or "Flyovers" novel insights into ventricular tachycardia mechanisms: The path is twisting.

Diverging channels of activation may be observed in some ventricular tachycardia (VT) using ultra-high-density mapping. We present here cases of such diverging activation patterns as observed from 60 consecutive VT activation maps using the Rhythmia system™ (Boston Scientific, Marlborough, MA, USA). Diverging directions of activation in the same area with "crossroads" or "flyover" pattern can be traced, implying recording of independent multilayer channels. Adaptation of current automated recording by the 3D mapping system is mandatory for better investigating this phenomenon.

High density mapping of inappropriate sinus tachycardia further looks into potential mechanisms.

Inappropriate sinus tachycardia (IST) is an incompletely understood condition associating unexpectedly fast sinus rates and debilitating symptoms whose management by sinus node modification/ablation demonstrated limited long-term success. We report about a case of IST who underwent two RF procedures using high density mapping system, highlighting some possibly specific features and discussing potential mechanisms.

Creation of sinus rhythm and paced maps using a single acquisition step: the "one acquisition-two maps" technique-a feasibility study.

PURPOSE: Scars and abnormal electrograms may significantly differ according to the activation wavefront. We propose a new fast technique for reliable comparison between sinus rhythm and ventricular pacing using a single map acquisition and the Rhythmia™ 3D mapping system. METHODS: A special programming of the external stimulator was assuring full stable regular paced-beat bigeminy during spontaneous rhythm. A first map was acquired for the spontaneous cardiac beat. Then the window of detection was moved to the following paced beat, and a second map was available after recalculation by the system, depicting activation and voltage of the paced cardiac beat at the same locations, with an exactly the same number of beats in both maps. RESULTS: Thirty patients with structural heart disease referred for ablation of ventricular tachycardia underwent this protocol, who were compared with 19 similar patients undergoing repeated maps. Duration of the mapping was significantly shorter compared to controls (34 ± 12 vs 57 ± 14 min, p < 0.0001) without differences in the number of electrograms (6978 ± 7067 vs 9554 ± 4424 for sinus rhythm map and 6610 ± 7240 vs 7783 ± 3804 for paced map, p = ns for both). The technique cannot be completed in five patients (17%), because of arrhythmogenicity, mechanical right bundle branch block, hemodynamical impairment, or bradycardia. CONCLUSION: We propose a novel technique for performing maps during sinus rhythm and ventricular pacing using a single acquisition. Beside time saving, this will allow more strict comparisons between different activation wavefronts.

Atrial Tachycardia With Atrial Activation Duration Exceeding the Tachycardia Cycle Length: Mechanisms and Prevalence.

OBJECTIVES: This study sought to identify atrial tachycardia (AT) demonstrating atrial activation duration (AAD) lasting longer than the length of the tachycardia cycle (TCL); to assess AT prevalence; and to evaluate the mechanisms and characteristics associated with these AT episodes by using the Rhythmia system (Boston Scientific, Marlborough, Massachusetts). BACKGROUND: Ultra-high-density mapping allows very accurate characterization of mechanisms involved in AT. Some complex patterns may involve AAD which is longer than the tachycardia cycle length (TCL) which makes maps difficult to interpret. Prevalence and characteristics of such ATs are unknown. METHODS: A cohort of 100 consecutive patients undergoing ablation of 125 right (n = 21) or left (n = 104) ATs using ultra-high-density mapping were retrospectively included. Offline calculation of right or left AAD was compared to TCL. RESULTS: Mean TCL was 293 ± 65 ms, and mean AAD was 291 ± 74 ms (p = NS). AT mechanisms were macro-re-entry in 74 cases (59%), localized re-entry in 27 cases (22%), and focal AT in 21 cases (17%) (types were mixed in 3 cases). Fifteen ATs (12%) had AADs that were longer than the TCL (71 ± 45 ms longer, from 10 to 150 ms). TCL was equal to the AAD in 97 ATs (78%), whereas 13 ATs (10%) had AAD shorter than the TCL (focal AT in each case). There were no differences between right and left atria for prevalence of ATs with AADs that were longer than the TCLs. There were significant differences in AT mechanisms according to the AAD-to-TCL ratio (p < 0.0001), with localized re-entry showing more often that AAD was longer than the TCL compared to that in focal AT and macro-re-entry. CONCLUSIONS: ATs with AAD lasting longer than the TCL were present in approximately 10% of the ATs referred for ablation, mostly in ATs caused by localized re-entry. Ultra-high-density mapping allows detection of these complex patterns of activation.

The electrical circuit of a hemodynamically unstable and recurrent ventricular tachycardia diagnosed in 35 s with the Rhythmia mapping system.

Herein, we report a 47-year-old woman with ischemic cardiomyopathy who underwent ablation therapy due to an electrical storm without any triggers. The voltage mapping in sinus rhythm with the Rhythmia system and Orion catheter displayed several LAVAs in and around the anteroapical scar area. Although the patient did not tolerate the induced clinical ventricular tachycardia, which was reproductively induced, 35-second-mapping in the scar zone with the Orion catheter demonstrated the VT circuit with the critical isthmus. This report shows the possibility of the new ultra-high density mapping system in a specific ischemic VT patient.