March 5th Question
A 78-year-old woman with a history of paroxysmal atrial fibrillation, transient ischemic attack, hypertension, and recurrent gastrointestinal bleeds is brought for placement of Watchman (Boston Scientific, Marlborough, MA) left atrial appendage closure device. After transseptal access and anticoagulation with intravenous heparin, a 27-mm Watchman device is implanted in the left atrial appendage guided by fluoroscopy and transesophageal echocardiography. Post-deployment, a contrast injection is performed (Figure; Movie I in the Data Supplement). What is the most appropriate next step?
A. Partially capture Watchman, slightly withdraw, and redeploy to align the polyethylene terephthalate mesh-covered surface flush with the ostium of the left atrial appendage
B. Completely capture Watchman and remove from body
C. Release Watchman, exit left atrium, and reverse anticoagulation
D. Check for release criteria on transesophageal echocardiography (position, anchor, seal, and stability)
E. Place a pericardial drain
ANSWER TO FEBRUARY 26th QUESTION
B. Macroreentrant atrial tachycardia
The surface ECG leads in the Figure show continuous activity without any discrete isoelectric period between P waves—a pattern suggestive of macroreentrant atrial tachycardia (atrial flutter)—as opposed to focal tachycardias (automatic, triggered, microreentrant) that generally have isoelectric period between successive P waves. Overdrive pacing from the cavotricuspid isthmus (CTI) demonstrates manifest constant fusion of the surface P waves (Figure). Even though pure paced morphology from the pacing site is not shown, constant fusion during the pacing train is apparent on account of pacing stimulus occurring after onset of surface P wave. Constant fusion is a feature of reentry and is not observed with automatic/triggered tachycardias.1, 2 Evidence of fusion between antidromically captured atrial tissue from pacing and the orthodromically captured tissue from the reentry circuit on surface P waves implies macroreentry. In contrast, the reentrant circuit is localized within a small spatial region in microreentry, with radial spread of activation from this site. Even though microreentrant tachycardias can be entrained with overdrive pacing, constant fusion is not apparent of surface ECG because the bulk of the atrial tissue is captured antidromically from the pacing site (P-wave morphology like pure pacing) with only a part of the circuit localized within the zone of microreentry captured orthodromically.
Circ Arrhythm Electrophysiol is available at http://circep.ahajournals.org.
The Data Supplement is available at http://circep.ahajournals.org/lookup/suppl/doi:10.1161/CIRCEP.118.006250/-/DC1.
- © 2018 American Heart Association, Inc.
- Asirvatham SJ,
- Stevenson WG
- Waldo AL