Fig. 5.1
The Watchman device consists of a nitinol structure covered with a PET (polyethyl terephthalate) cap of 160 micron filter (Fig. 5.1a). Ten fixation barbs around the middle part of the device perimeter engage the device to the LAA wall for anchoring. Available sizes are: 21, 24, 27, 30 and 33 mm (Fig. 5.1b, c)
Fig. 5.2
Delivery sheaths for Watchman device implantation. Preformed curve shapes guide position into the LAA—most operators use the double curve sheath only. This sheath has an outer diameter of 14F (4.7 mm) and an inner diameter of 12F. The sheath has a working length of 75 cm allowing to use a standard pigtail catheter to negotiate the LAA. The distal markers allow to probe the depth of the LAA and are also useful for normalization of the angiographic measurements. The more proximal markers indicate the landing zone of the different device sizes: from distal to proximal the rings locate at appropriately the landing zone of the 21, 27 and 33 mm device. 24 and 30 are in between
Fig. 5.3
Measurement of the Watchman landing zone diameter and the LAA depth. The proximal part of the ridge to the left superior pulmonary vein (LSPV) is considered to be part of the free left atrium (no trabecularization). The landing zone of the LAA for Watchman sizing is measured between the inferior tissue border close to the coronary circumflex artery visible in TEE. The superior part is located approximately 1–2 cm distal to the LSPV ridge orthogonal from the Cx tissue edge. Depth maybe measured along the visible axis, yet this is often not possible due to a 3D rotation of the LAA. Probing the depth with the Watchman sheath on the pigtail is recommended
Fig. 5.4
Exemplary CT images of two patients illustrating the anatomic location of Watchman landing zone employed for correct sizing. (a, b) Internal and external imaging of a windsock LAA. Watchman landing zone diameters are measure from the Cx ridge to a point approx. 1–2 cm distal to the coumadin ridge. (c, d) Internal and external imaging of a classic chicken wing anatomy
Fig. 5.5
Exemplary CT images of two patients illustrating the anatomic location of Watchman landing zone employed for correct sizing. (a, b) Internal and external imaging of a broccoli-type LAA. Watchman landing zone diameters are measured from the Cx ridge to a point approx. 1–2 cm distal to the coumadin ridge. Note the proximal ridge between the two lobes within the LAA. (c, d) Internal and external imaging of a classic chicken wing anatomy
Fig. 5.6
Sizing scheme of the Watchman device aiming for a compression of around 20% based on TEE measurements. Sizing is done by the largest diameter measured by TEE (mostly 135°) and/or angiography (RAO 15°, caudal 20°). The depth of the LAA is usually not easy to determine; measurement is therefore not required but is visualized by the Watchman sheath and its markers
Successful LAA closure is achieved with a step-by-step approach (Fig. 5.7). The device endothelializes over time until final coverage is achieved after around 3–6 months (Fig. 5.8). Antithrombotic treatment is recommend during this time with dual antiplatelet therapy (DAPT) being the most common choice in Europe whereas the PROTECT-AF Scheme (45 days of warfarin followed by DAPT until 6 months then aspirin alone) is the standard in the US. New data from the EWOLUTION registry point to the possibility of using NOAC during the first three months prior to switching to aspirin (Fig. 5.9).
Fig. 5.7
Watchman LAA closure: Step-by-step
Fig. 5.8
Human histologic and pathologic analysis of implanted Watchman devices completely endothelialized and with organized tissue behind the fabric. Images courtesy of R. Virmani presented at EuroPCR 2013
Fig. 5.9
Antithrombotic treatment options following LAA closure with the Watchman device. Studies supporting the various strategies are named below the options. In Europe most patients receive dual antiplatelet therapy for 3 months following LAA closure. US-based trials have included warfarin-eligible patients and have therefore used warfarin post-procedurally
5.2 Sheath Exchange
The access sheath and dilator are used to gain access to the LAA following a transseptal puncture. The Watchman sheath is available in two variations, the double curve (standard) and the single curve meant to have an easier access to a windsock type LAA (Fig. 5.2). In the early days of LAA occlusion, pericardial effusion both early and delayed was a quite common event that limited the benefit of this prophylactic intervention. It became clear that wire navigation of the fragile LAA and excessive device manipulation prior to device release is often responsible for this life threatening event to occur. Therefore exchange to the Watchman sheath over a stiff wire (Supracore 260 cm or Amplatzer stiff or super stiff 260 cm) located in the left superior pulmonary vein (LSPV) has been adopted as the default strategy as it is the most atraumatic strategy. The author prefers to perform this step in an LAO 40° angiographic angle as this allows to easily visualize the wire entering the LSPV (Fig. 5.10).
Fig. 5.10
Case example: following transseptal puncture, a stiff wire with a soft tip (i.e. Amplatzer superstiff 250 cm, Supracore 260 cm) is advanced into the superior pulmonary vein as seen in a LAO 40° angiographic view. The wire is clearly outside the epicardial border thus documenting the correct position in the LSPV. It is not recommended to exchange the sheath with the wire positioned in the LAA due to several perforations with life threatening pericardial effusions that occurred with this technique
If the optimal position has been achieved through transseptal puncture, passing the wire through the SL1 sheath will automatically land in the LAA. A posterior movement (9 o’clock) is necessary to enter the LSPV after careful pullback of the SL1 sheath best guided by echo; this step has led the sheath to prolapse back into the right atrium or the sheath to be located below the ridge between LSPV and LAA. Some operators therefore favour to use a diagnostic multipurpose catheter together with a soft Terumo wire to negotiate the LSPV and exchange to a stiff wire over the MP catheter. Once the stiff wire has achieved a position deep in the LSPV outside the epicardial border, the Watchman sheath is advanced into the left atrium. Both the groin/pelvic area and the septum may pose some resistance that might lead the wire to prolapse back into the LA or even RA. Careful wire management is necessary to prevent this (Fig. 5.11).
Fig. 5.11
Case example: after exchange to the Watchman sheath a 6F pigtail catheter is advanced into the LAA and used as a rail for atraumatic positioning of the sheath into the distal part of the LAA
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