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I M A G I N G V I G N E T T E

Imaging the Left Atrial AppendagePrior to, During, and After Occlusion

Siobhan M. Lockwood, MBBS, Jeffery F. Alison, MBBS, Manoj N. Obeyesekere, MBBS,Philip M. Mottram, MBBS, PHD

P A T I E N T S W I T H A T R I A L F I B R I L L A T I O N ( A F ) H A V E I N C R E A S E D R I S K for

thromboembolic stroke, mainly from a thrombus originating in the left atrial appendage (LAA).

Anticoagulation is thus recommended for patients with high risk for stroke but is often underutilized

due to issues concerning its risk, need for monitoring, and compliance. Occlusion of the LAA with a

device such as the LAA occluder (Watchman occluder, Atritech Inc., Plymouth, Minnesota) offers an

alternate method of reducing thromboembolic risk in these patients. Imaging plays an important role

Figure 1. Determination of LAA Size and Anatomy by TEE and MDCT

The LAA imaged at 0° and 90° by TEE (A and B) with corresponding MDCT images (C and D). At 0° and 90°, the LAA width is measuredin a plane from the left coronary artery (*) to 1 to 2 cm from the tip of the left upper pulmonary vein (LUPV) limbus (¥). Ao � aorta; LA� left atrium; LAA � left atrial appendage; LV � left ventricle; LUPV � left upper pulmonary vein; MDCT � multidetector cardiac com-puted tomography; RA � right atrium; RVOT � right ventricular outflow tract; TEE � transesophageal echocardiography.

From the Monash Cardiovascular Research Centre, Monash Heart, Southern Health and Department of Medicine (MMC),Monash University, Melbourne, Australia. The authors have reported that they have no relationships to disclose.

Address for correspondence: Dr. Philip M. Mottram, Monash Heart, 246 Clayton Road, Clayton

Victoria 3168, Australia. E-mail: philip.mottram@southernhealth.org.au.

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Figure 2. Assessment of Potential Exclusion Criteria

(A and B) Demonstrate an LAA with a large dominant lobe (*) and a smaller accessory lobe (**). This anatomy may make successful occluder implantation morechallenging as it is imperative that the device occludes the ostia of both lobes. As implantation of the LAA occluder device involves placing a pigtail catheter inthe LAA, the presence of thrombus must be excluded prior to the procedure. This patient was not suitable for occluder implantation due to probable LAAthrombus demonstrated on MDCT (failure of contrast to fill the distal LAA) (C) (†) and dense spontaneous echo contrast confirmed on TEE (D) (‡). Abbreviations

as in Figure 1.

Figure 3. Access to the LA Via Transseptal Puncture

The LAA occluder is implanted percutaneously under general anesthesia via the femoral vein, with fluoroscopic and TEE guidance. Access to the left atrium is viaa transseptal puncture, performed under TEE guidance in multiple imaging planes, principally 45° and 90°, ensuring a posterior puncture and avoidance of theaortic root. A posterior puncture site appears to assist in accurate delivery and positioning of the device into the LAA. (A and B) Show simultaneous TEE imagesdemonstrating “tenting” of the atrial septum (arrow) due to pressure from the needle prior to puncture. SVC � superior vena cava; other abbreviations as in

Figure 1.

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Figure 4. Occluder Deployment and Release

The occluder is an umbrella-like device with a fabric covering that is permeable to blood and contrast, but not thrombotic particles. It is designed to beimplanted slightly distal to the LAA ostium and has barbs distally to secure its position. The left coronary artery, mitral valve annulus (MVA) and limbus of theLUPV are the anatomic landmarks used to guide correct device positioning. Following deployment and prior to release, the device is assessed by fluoroscopyand TEE through multiple planes for size, position, stability, and seal. (A) (Online Video 1) Demonstrates occluder device deployment in addition to the “stabilitytug” during which the device moves in unison with the LAA and then returns to its original position. (B) Demonstrates a well-seated 27 mm occluder device,sitting flush with the LAA ostium with appropriate device compression (22 mm) (reduction of original device width by 20%). (C) Demonstrates interrogation ofdevice seal using the X-plane feature and color Doppler. The seal is adequate if all lobes are excluded from communication with the left atrium and any colorjets around the device are �5 mm in diameter. (D and E) Demonstrate suboptimal occluder positioning: a device positioned too far into the LAA and failing toocclude an accessory lobe (D, arrow); a suboptimally positioned device with some protrusion into the left atrium (E, arrow). Device repositioning resulted in suc-cessful LAA occlusion in both cases. Abbreviations as in Figure 1.

Figure 5. Assessment of Occluder Device 45 Days After Deployment

We performed follow-up imaging in our patients with a device at 45 days after the procedure. In the majority of patients, the occluder device is well-seated inthe LAA at the time of follow-up (A). (B) Shows a three-dimensional, enface TEE view from the LA. Device seal is assessed at follow-up by TEE color Doppler anddynamic MDCT. (C and D) Are examples of persistent communication (arrow) between the left atrium and LAA as demonstrated by TEE and MDCT in the samepatient. In this situation, anticoagulation is continued and imaging repeated in 6 months. The degree of device endothelialization may also be assessed by TEE,however, we believe that MDCT is superior for this purpose. (E) (Online Video 2) Demonstrates incomplete device endothelialization with unrestricted passage ofcontrast into the LAA. In contrast, (F) demonstrates complete failure of contrast to penetrate the surface of the device at 45 days. PA � pulmonary artery; otherabbreviations as in Figure 1.

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in this procedure. Multiplanar transesophageal echocardiography (TEE) is performed to define LAA size

and anatomy, including the presence of multiple lobes. The LAA is imaged from the mid-esophageal

view through 180° (in particular at 0°, 45°, 90°, and 135°) to define the maximum LAA width and

maximum depth of the dominant lobe. Both measurements are used to determine device size; the

device can accommodate LAA widths ranging from 17 to 32 mm, as long as LAA depth exceeds width.

Additionally, in our center, patients undergo multidetector cardiac computed tomography (MDCT) (320

slice) with contrast prior to occluder implantation for further evaluation of LAA anatomy. The images

(Figs. 1, 2, 3, 4, and 5) illustrate the role of imaging before, during, and after this procedure.