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Left atrial appendage (LAA) closure with a Watchman device (Boston Scientific Corp., Marlborough, MA) has emerged as an alternative strategy to reduce the risk of thromboembolism in patients with atrial fibrillation (AF) at risk for bleeding complications from oral anticoagulation. The device mechanically prevents thrombus formation by occluding the LAA, which is the predominant site of thrombosis in patients with nonvalvular AF.1 Clinical trials have demonstrated the Watchman to be noninferior to anticoagulation with warfarin in preventing a composite endpoint of stroke, systemic embolism, or cardiovascular death.^2–4 Its use was approved by the U.S. Food and Drug Administration in March 2015. Inclusion and exclusion criteria for implant are shown in Table 58.1.

The Watchman device is a parachute-shaped device with a flexible nitinol frame that conforms to the anatomy of the LAA and engages with active fixation anchors. The proximal face of the device is covered with a 160-micron membrane to block emboli and promote endothelialization of the device. The Watchman device, Watchman access sheath, and Watchman delivery system are shown in Figure 58.1. An overview of the implant procedure is shown in Video 58.1.

Patient Screening

Patients must be carefully screened prior to the procedure to ensure that LAA morphology is appropriate for device implantation, that the LAA ostium measures between 17 and 31 mm, and that intracardiac thrombus and other exclusion criteria are absent (Table 58.1)²

Clinical trials mandated that screening be performed via transesophageal echocardiogram (TEE), delineating appendage anatomy in a 0°–180° sweep (typically every 45°) (Figure 58.2).

TEE is the screening modality supported by the largest volume of data. In clinical practice, CT and MRI have also been employed for patient screening. As a general principle, the screening study confirms the presence of suitable anatomy and the absence of contraindications, while selection of device size is based on intraprocedural measurements, which can change between the time of the screening study and the procedure. The procedure is generally performed under TEE guidance. There is a small body of experience using intracardiac echocardiography to guide implantation, but caution should be used until more data is available.

Patient Preparation

Our preference is to perform the procedure under uninterrupted anticoagulation. Due to the inherent risk of perforation, centers new to the experience may prefer to perform the procedure with brief interruption of anticoagulation or bridging therapy.

On arrival to the preoperative suite, patients receive antibiotic prophylaxis per hospital protocol. In the absence of overt volume overload, we typically administer a fluid bolus of 500 cm³ of normal saline over 2 hours to increase LAA volume.

In the United States, the implant procedure is performed with general anesthesia using endotracheal intubation. Outside the United States, it is often done without intubation. We prefer general anesthesia to allow for mandated apnea during device deployment, which reduces cardiac motion, thereby decreasing the risk of LAA perforation and tamponade.

Once anesthesia is administered, the TEE probe is passed into the esophagus and the patient is prepared and draped in the usual sterile fashion.

Transseptal puncture is performed with a standard technique per operator discretion. We employ TEE guidance to allow prescriptive puncture in the mid posterior fossa and typically use an 8-Fr SL0 sheath and BRK needle. The transseptal sheath is advanced to the superior vena cava, the wire is removed, and the transseptal needle is inserted into the sheath after flushing. The needle–sheath assembly is pulled down into the fossa ovalis using TEE and fluoroscopic guidance. We confirm a mid posterior puncture site (mid fossa in the bicaval view and posterior in the short axis view). The transseptal puncture is performed and the sheath advanced into the left atrium (LA; Figure 58.3).

Sheath Exchange

The needle/dilator assembly is replaced with an exchange-length stiff guidewire. The guidewire is advanced into a left pulmonary vein to enable non-traumatic sheath exchange. The transseptal sheath is exchanged for a Watchman access sheath (double-curve, single-curve, or anterior curve), which is advanced into the LA with a dilator after careful flushing. The double-curve is the most commonly used. The single-curve can be considered in the rare case of an unusually posterior target, while the anterior curve can be used in cases of a very anterior appendage take-off. We recommend starting with a double-curve sheath.

The guidewire is replaced with a pigtail catheter. LA pressure is recorded. If the LA pressure is less than 10 mm Hg or if LAA size is borderline small, additional intravenous fluid is administered to enlarge the appendage.

Engagement of the Left Atrial Appendage

While multiple approaches have been explored to enter the LAA, including guidewires and balloon-tipped catheters, we recommend using a 6-Fr straight pigtail catheter. The pigtail catheter is positioned in the LAA using TEE and fluoroscopic guidance. Generally, the 135° view on TEE corresponds to the RAO 30° caudal angulation on cineangiography, and optimally displays the full anterior-posterior extent of the appendage.

The most superior/anterior lobe of the appendage is the preferred target and is typically engaged using counterclockwise torque (keeping the pigtail outside the sheath) to allow optimal coaxial placement of the face of the device. Placement in a posterior lobe typically leaves a large shoulder, and should be avoided if possible (Video 58.1).

Selection of Device Size and Device Preparation

Selection of appropriate device size (21, 24, 27, 30, or 33 mm) is based on TEE and angiographic measurements. As a general principle, TEE is used to guide selection of device size, which should typically be 20% larger than the maximum ostial diameter of the LAA, while angiography confirms sufficient depth for appropriate placement. The access sheath has 3 radiopaque marker bands at 21, 27, and 33 mm from the tip that approximate final device position angiographically. Once ideal sheath placement has been determined, the operator should maintain sheath torque while an assistant prepares the device (Figure 58.4).

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