Clinical History We present the case of a 65 year old male, who underwent a pulmonary vein isolation procedure and ablation for recurrent persistent atrial fibrillation with subsequent placement of a "WATCHMAN" (Atritech, Plymouth MN) left atrial appendage (LAA) occlusion device. The patient underwent a contrast enhanced cardiac CT to evaluate for proper placement and to exclude any residual communication between the left atrium and the LAA.
Findings A normal LAA with its pectinate muscles is readily opacified after the administration of an adequately timed intravenous contrast bolus (Fig. 1A and B, asterisk). In our patient, a WATCHMAN device (arrows) in regular position completely occupies the LAA resulting in lack of opacification of LAA (asterisk) by contrast in both early and delayed phases of imaging (Fig. 2A and B), confirming thrombosis and exclusion of the left atrial appendage. In addition, the integrity of the device was demonstrated by 3-D volume rendered images (Fig.3).
(Click on images to enlarge)
Figure 1A. Axial view demonstrating a normal contrast enhanced LAA (asterisk).
Figure 1B.Multiplanar Reconstruction (MPR) 2-chamber view demonstrating a normal contrast enhanced LAA (asterisk).
Figure 2A. Axial image of our patient demonstrating the LA, an unopacified and thrombosed LAA (in asterisk), and the WATCHMAN cage device (arrows) in situ.
Figure 2B.MPR 2-chamber view of our patient demonstrating the WATCHMAN cage (arrows), and an unopacified and thrombosed LAA (asterisk).
Figure 3.3-D Volume rendered reconstruction of the WATCHMAN device.
Discussion Patients with atrial fibrillation carry a 5% annual risk to suffer from stroke, which is 5 times higher than in an aged-matched population in sinus rhythm. The majority of ischemic strokes are attributed to embolization of a thrombus typically originating from the LAA. The WATCHMAN LAA System is a nitinol frame structure covered with a permeable polyester fabric that allows blood flow but excludes passage of thrombi out of the LAA. Anticoagulation for up to 6 months is necessary after implantation in order to ensure adequate endothelialization of the device, following which anticoagulation can be safely discontinued. Preliminary data suggests that LAA occlusion with a WATCHMAN System is safe and feasible, and cardiac CTA is an excellent modality to assess the integrity of the WATCHMAN device.
Prystowsky EN, Benson DW, Fuster V, et al. Management of patients with atrial fibrillation. A statement for healthcare professionals. From the Subcommittee on Electrocardiography and Electrophysiology, American Heart Association. Circulation 1996; 93:1262-77.
Stoddard MF, Dawkins PR, Prince CR, et al. Left atrial appendage thrombus is not uncommon in patients with acute atrial fibrillation and a recent embolic event: a Transesophageal echocardiographic study. J Am Coll Cardiol 1995;25:452-459.
Sick PB, Schuler, G, Hauptmann KE, et al. Initial worldwide experience with the WATCHMAN left atrial appendage system for stroke prevention in atrial fibrillation. J Am Coll Cardiol, 2007;49:1490-1495.
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Editors: Suhny Abbara, MD MGH Department of Radiology Wilfred Mamuya, MD, PhD MGH Division of Cardiology