PMC:6019327 / 204965-208499 JSONTXT

{"project":"2_test","denotations":[{"id":"28506916-20202493-29308150","span":{"begin":461,"end":464},"obj":"20202493"},{"id":"28506916-20202493-29308150","span":{"begin":461,"end":464},"obj":"20202493"},{"id":"28506916-27262767-29308151","span":{"begin":918,"end":921},"obj":"27262767"},{"id":"28506916-27262767-29308151","span":{"begin":918,"end":921},"obj":"27262767"},{"id":"28506916-26001505-29308152","span":{"begin":922,"end":925},"obj":"26001505"},{"id":"28506916-26001505-29308152","span":{"begin":922,"end":925},"obj":"26001505"},{"id":"28506916-27262767-29308153","span":{"begin":1094,"end":1097},"obj":"27262767"},{"id":"28506916-27262767-29308153","span":{"begin":1094,"end":1097},"obj":"27262767"},{"id":"28506916-16684024-29308154","span":{"begin":1635,"end":1638},"obj":"16684024"},{"id":"28506916-16684024-29308154","span":{"begin":1635,"end":1638},"obj":"16684024"},{"id":"28506916-27262767-29308155","span":{"begin":3527,"end":3530},"obj":"27262767"},{"id":"28506916-27262767-29308155","span":{"begin":3527,"end":3530},"obj":"27262767"},{"id":"28506916-26001505-29308156","span":{"begin":3531,"end":3534},"obj":"26001505"},{"id":"28506916-26001505-29308156","span":{"begin":3531,"end":3534},"obj":"26001505"},{"id":"T1708","span":{"begin":461,"end":464},"obj":"20202493"},{"id":"T49100","span":{"begin":461,"end":464},"obj":"20202493"},{"id":"T60528","span":{"begin":918,"end":921},"obj":"27262767"},{"id":"T6221","span":{"begin":918,"end":921},"obj":"27262767"},{"id":"T72541","span":{"begin":922,"end":925},"obj":"26001505"},{"id":"T58310","span":{"begin":922,"end":925},"obj":"26001505"},{"id":"T21503","span":{"begin":1094,"end":1097},"obj":"27262767"},{"id":"T20785","span":{"begin":1094,"end":1097},"obj":"27262767"},{"id":"T69960","span":{"begin":1635,"end":1638},"obj":"16684024"},{"id":"T87424","span":{"begin":1635,"end":1638},"obj":"16684024"},{"id":"T72139","span":{"begin":3527,"end":3530},"obj":"27262767"},{"id":"T91290","span":{"begin":3527,"end":3530},"obj":"27262767"},{"id":"T75154","span":{"begin":3531,"end":3534},"obj":"26001505"},{"id":"T74642","span":{"begin":3531,"end":3534},"obj":"26001505"},{"id":"T4032","span":{"begin":461,"end":464},"obj":"20202493"},{"id":"T58814","span":{"begin":461,"end":464},"obj":"20202493"},{"id":"T28313","span":{"begin":918,"end":921},"obj":"27262767"},{"id":"T37449","span":{"begin":918,"end":921},"obj":"27262767"},{"id":"T26238","span":{"begin":922,"end":925},"obj":"26001505"},{"id":"T62104","span":{"begin":922,"end":925},"obj":"26001505"},{"id":"T65615","span":{"begin":1094,"end":1097},"obj":"27262767"},{"id":"T70784","span":{"begin":1094,"end":1097},"obj":"27262767"},{"id":"T66411","span":{"begin":1635,"end":1638},"obj":"16684024"},{"id":"T97540","span":{"begin":1635,"end":1638},"obj":"16684024"},{"id":"T57808","span":{"begin":3527,"end":3530},"obj":"27262767"},{"id":"T96417","span":{"begin":3527,"end":3530},"obj":"27262767"},{"id":"T55251","span":{"begin":3531,"end":3534},"obj":"26001505"},{"id":"T87467","span":{"begin":3531,"end":3534},"obj":"26001505"}],"text":"Initial localization of an atypical flutter can frequently be facilitated by simply observing the activation sequence on a CS catheter. Proximal to distal activation suggests cavotricuspid isthmus-dependent flutter, right PV tachycardia, or counterclockwise mitral annular flutter, whereas distal to proximal activation suggests a left PV tachycardia or clockwise mitral flutter. An “on time” or fused CS pattern could be suggestive of a roof-dependent flutter.631 When acquiring an electroanatomical activation map, each acquired point should be carefully annotated by the operator, taking care to tag and not include widely split potentials that might indicate a line of block. Multipoint mapping can decrease the time needed for acquiring a map, but automated electrogram annotation might lead to errors and confusing maps. A novel very automated high-density automated mapping system has recently become available.627,632 Early results using this system to determine activation sequences and perform ablation based solely on activation rather than entrainment mapping have been encouraging.627 However, the true clinical value of this type of system is unknown and will require a prospective randomized comparison with conventional electroanatomical and entrainment mapping. When performing ablation of AFL with a conventional 3D mapping system, scar should be labeled as such to identify anatomic obstacles. Focal microreentrant tachycardias can also occur and are typically indicated by centrifugal conduction away from a focal area of onset and by long fractionated potentials with duration \u003e50% of the tachycardia cycle-length.628 The main strength of activation mapping is that it is unlikely that the tachycardia will terminate. The disadvantage is that these activation maps can be extremely difficult to interpret and might not translate to identifying successful ablation sites. When performing ablation of atypical AFL with a conventional 3D mapping system, especially when a stable reentrant circuit is present that allows entrainment, most operators find that entrainment mapping from multiple sites is a better and more accurate approach to localize the reentrant circuit and target ablation lesions. It is for this reason that entrainment mapping is the gold standard for mapping reentrant tachycardias and is the preferred mapping strategy employed by most writing group members at the present time. For atypical flutter, because fusion of the F wave can be difficult to interpret, the primary goal is to identify regions with a postpacing interval within 20 ms of the tachycardia cycle length. Care should be taken to pace at or near threshold, given high-output pacing can capture adjacent tissue that leads to an erroneous postpacing interval. High-output pacing can also lead to electrode polarization that obscures the return electrogram. Once the reentry circuit is delineated, an ablation strategy can be designed to connect anatomic obstacles and interrupt the tachycardia. Despite this current preference, new high-density automated mapping systems have been developed, as noted above, which allow development of successful ablation strategies based on high-density activation mapping alone, without the risk of entrainment pacing resulting in termination of the flutter under study or its degeneration into a different flutter or fibrillation. Prospective randomized clinical trials will need to be performed to determine the true clinical value of these new automated high-density mapping systems.627,632"}