Image Story: Pseudo-Thrombus on Watchman Sheath
Ethan Fry, Clinton Thurber, Keith Suarez, Mark E Lawrence, Dan W Giebel, Javier E Banchs
A 73-year-old man with history of persistent atrial fibrillation and a high risk of bleeding complications was considered for placement of a Watchman device for left atrial appendage (LAA) occlusion. Deployment of a 24mm device was initially attempted and felt to be too deep within the LAA. Partial recapture with repositioning failed on two occasions, which lead to complete withdrawal of the device. It was judged that a larger device was needed to allow for a more proximal positioning, so a 27mm device was successfully implanted. During evaluation of “pass criteria” with transesophageal echocardiography (TEE), a mobile, filamentous, echogenic mass was visualized at the tip of the access sheath (Figure 1) which was suspicious for thrombus formation. The activated clotting time (ACT) was confirmed to be more than 300 sec. The Watchman device was released, the delivery sheath pulled slowly and forceful aspiration was applied. However, as the thrombus-like image persisted, the decision was made to pull the access sheath back into the right atrium. Once the access sheath had been removed from the body it was evident the structure visualized was a thread of the distal radio-opaque ring of the access sheath (Figure 2).
Peri-procedural strokes are rare but of significant concern since the ultimate goal of the therapy is precisely stroke prevention. Thromboembolic events and ischemic strokes have been evaluated in multiple trials with encouraging, but mixed results. A particular concern with watchman placement is the increased risk of stroke in the peri-procedural period and its potential correlation with device related thrombus. Thrombus formation on the surface of the Watchman device, delivery sheath, and wire during percutaneous vascular procedures has been reported. Always maintaining standard safety measures, Watchman operators should recognize that disruption of the delivery sheath during device recapture could result in this image, simulating a thrombus.