Prior to the implantation of an LAA occlusion device, all patients must undergo preprocedural imaging to explore the anatomy of the LAA and to exclude thrombi in the left atrium and the LAA. The standard imaging technique is 2D and 3D transesophageal echocardiography (TEE). TEE enables measurement of the LAA ostium, the landing zone of the elected occlusions device, and the length of the LAA body, and it allows to characterize the shape of the LAA, especially when there are multiple lobes (number, shape, and localization). Some operators are using additional preprocedural imaging like computed tomography angiography or magnetic resonance imaging. Further important preprocedural information include the anatomical orientation of the LAA body axis, as this has important implications for the location of the transseptal puncture. Most commonly, TEE is performed immediately prior to the intervention. The authors recommend the whole procedure (transseptal puncture, LAA measurement, and device implantation) to be done under echocardiographic guidance (TEE or intracardiac echocardiography, ICE).

No later than 48 h prior to the procedure, patients should receive loading doses of 500 mg aspirin and 600 mg clopidogrel (for patients without previous regular intake). Antibiotic prophylaxis should be administered before and after the procedure. Femoral venous access is obtained under local anesthesia, and transseptal puncture is performed under TEE (or ICE) and fluoroscopic guidance. The procedure is usually performed under local anesthesia at the right femoral access site and slight sedation using midazolam or propofol, if needed. Sedation is foremost needed due to the application of TEE. The usage of ICE may eliminate the need of sedation.

The first crucial step of the procedure is the transseptal puncture. After local anesthesia of the femoral access site, an 8-French transseptal sheath is inserted into the right femoral vein and advanced into the right atrium. Through this sheath, a transseptal needle is advanced to the intra-atrial septum. The transseptal puncture is indicated in the posterior and inferior segment of the fossa ovalis to facilitate an anterior superior trajectory that optimizes device delivery for most LAAs. As the height of the puncture depends on the orientation of the LAA, the puncture should always be done under echocardiographic guidance. In cases with rather cranial orientation of the LAA axis, the puncture site should be rather low and is best seen in bicaval view (90° in TEE). In cases with an anterior or rather caudal orientation of the LAA axis, the puncture should be done in the upper part of the septum. But independent from orientation of the LAA axis, all transseptal punctures should be carried out as far posterior as possible to facilitate access to the LAA. This can best be controlled in 45° view in TEE. Subsequent to transseptal puncture, the transseptal sheath is advanced though the puncture into the left atrium, and the needle is pulled back into the sheath. After echocardiographic exclusion of a pericardial effusion, 10,000 units of heparin should be administered to achieve an activated clotting time (ACT) of at least 250 s. The transseptal needle is exchanged for either a 0.035-in. stiff wire placed in the left upper pulmonary vein or a transseptal pigtail guidewire placed in the left atrium. Next, the transseptal sheath is exchanged over the wire for the occluder specific delivery sheath.

Independent from the LAA occlusion device chosen, the most effective and safe method to avoid air embolism is to wait for adequate back bleeding while holding the proximal end of the delivery catheter below zero. Furthermore, continuous saline infusion through the side arm of the sheath and slow removal of the dilator are recommended to avoid air embolism caused by air suction through the valve of the sheath during removal of the sheath dilator.

The Watchman system is the most commonly implanted LAA occlusion system worldwide. The first procedure was performed in August 2002. Since then, the device has repeatedly been technically modified. The occluder consists of a nitinol frame structure with ten fixation anchors along its waist. When fully deployed, the nitinol frame has a parachute-like configuration (Fig. 17.2). The proximal part of the system, which faces the left atrium after implantation, is covered with a thin polyethylene terephthalate (PET) membrane which is designed to reduce post-implant thrombus formation on the occluder, thus to allow faster endothelialization.

After successful transseptal puncture, the Watchman access sheath is introduced to the left side of the heart, and a pigtail catheter (5 Fr or 6 Fr) is introduced through the access sheath and advanced into the LAA to perform an angiography and make the necessary measurements. We take the fluoroscopic measurements in a caudal RAO projection. Furthermore, additional LAA measurements should be done by TEE in at least four views (0°, 45°, 90°, and 135°) with the ostium of the left circumflex artery as the essential landmark. Measurement should be done from the edge of the LCX to the opposite wall of the LAA, perpendicular to the axis of the LAA. We recommend an occluder size about 20 % bigger than the largest diameter measured to achieve the compression rate needed to engage the fixation barbs of the Watchman device into the wall of the LAA.

The Watchman system consists of three parts: the specific transseptal access sheath with an outer 14-Fr diameter (inner diameter 12 Fr), the 12-Fr delivery catheter, and the Watchman device, which comes preloaded within the delivery catheter. The access sheath is available in three different shapes to facilitate the device placement depending on the orientation of the LAA: a single-curved, a double-curved, and an anterior curved sheath (Fig. 17.3). The access sheath with a dilator is advanced into the left atrium. Once in place, the dilator is removed, and the pigtail catheter is then advanced into the LAA. This allows atraumatic tracking of the access sheath into the LAA.

Knowledge of the specific markers on the access sheath is mandatory for correct device placement. There are four markers, one distal marker at the tip of the sheath as well as three more markers placed more proximally (Fig. 17.4). The three proximal markers provide information on the placement of the most proximal part of the occluder, facing the left atrium when fully deployed. Depending on the size of the chosen occluder, its proximal end will align with one of these markers: the largest device size (33 mm) aligns with the most proximal placed marker, the 27-mm device aligns with the middle marker, and the smallest device (21 mm) aligns with the most distal of the three markers. The 30-mm and the 24-mm devices align between the markers, respectively. Knowledge of these specifications is important in order to place the access sheath correctly. Depending on the selected occluder size, the appropriate marking of the access sheath should align with the imaginary connecting line between the distal edge of the LCX and the opposite wall of the LAA, perpendicular to the LAA axis.

While introducing the delivery catheter into the access sheath, the delivery catheter with the closure device is continuously or intermittently flushed with heparinized saline to avoid air bubbles and air embolism. The delivery catheter is advanced under fluoroscopic guidance until its distal marker almost aligns with the distal marker of the access sheath. The access sheath must then be pulled back gently until the operator feels a click. This interlocks the access sheath with the delivery catheter. After checking the position of the delivery system fluoroscopically, the occluder can be deployed. The interlocked access and delivery sheath are pulled back while holding the delivery cable of the device in a stable position. This allows the device to deploy while still being fixed to the delivery system. The combined delivery system allows complete retrieval of a deployed occluder in case of insufficient placement. When optimal device position, sizing, and device seal are ensured in angiography and in TEE, a last test of stability, a tug test, should be performed before releasing the occluder. For this purpose, the delivery core wire is gently pulled under simultaneous injection of contrast medium to see the movement of the LAA together with the occluder. After successfully passing this test, the device is released from the delivery system by turning the core wire counterclockwise five times. We recommend final contrast injections as well as a final control with TEE in all four views (0°, 45°, 90°, and 135°) to check for residual leaks.

Within the PROTECT-AF trial [3], combined oral anticoagulation with warfarin and with aspirin was continued for at least 45 days after the implantation of the Watchman system to facilitate device endothelialization and to reduce the risk of thrombus formation. If TEE after 45 days showed successful occlusion of the LAA, warfarin was stopped, and an oral dual antiplatelet therapy with 100 mg of aspirin and 75 mg of clopidogrel was started until 6 months of follow-up, from which point aspirin alone was continued indefinitely. The ASAP trial tested the implantation of the Watchman device without temporary post-interventional anticoagulation [4]. The patients received aspirin and clopidogrel for 6 months, followed by lifelong aspirin daily. The rate of device associated thrombus formation within 6 months after Watchman implantation was not increased when compared to the patients examined in the PROTECT-AF trial. Therefore, the authors of this chapter recommend a dual antiplatelet therapy with 100 mg of aspirin and 75 mg of clopidogrel for 6 months after the implantation. In case of successful occlusion of the LAA and missing evidence of thrombus formation on the occluder, thereafter we stop clopidogrel and aspirin.

After other non-dedicated Amplatzer devices have been used for LAA closure, the Amplatzer Cardiac Plug (ACP) was developed as a device designed especially for percutaneous occlusion of the LAA in 2008. The ACP consists of a distal lobe and a proximal disk, connected by a stretchable waist (Fig. 17.5). It is built of a self-expanding nitinol frame including two polyester patches. After its deployment, the distal lobe is placed in the neck of the LAA, while the proximal disk covers the ostium of the LAA. The lobe has six pairs of barbed stabilization wires on its outer circumference to secure itself to the walls of the LAA, thus reducing the risk to device embolization. The polyester filling of the ACP facilitates endothelialization and decreases blood flow through the occluder. It is available in sizes from 16 to 30 mm in 2 mm steps, according to the outer diameter of the lobe. The proximal disk extends the lobe by 4 mm for device sizes from 16 to 22 mm and by 6 mm for device sizes from 24 to 30 mm.