Page 16 - Journal of Structural Heart Disease Volume 5, Issue 1

5
Case Report
Video 6. TEE image showing well seated two WATCHMAN de- vices at 44 degrees. View supplemental video at https://doi. org/10.12945/j.jshd.2019.010.18.sup.06.
An autopsy study of the normal heart documented that 80% of the LAA have more than one lobe, with slightly more than half having 2 lobes [12]. Consider- ing the great variability of the LAA anatomy in relation to size, shape, volume, number of lobes, and shape of the orifice, no single device is ideal to fit all [13]. The shape of the LAA ostium is elliptical in approximately 69% of cases, with a maximum depth ranging up to 51 mm, while the rounded shape is present in only 5–6% of cases. The diameters of the ostium show min- imal changes during the cardiac cycle (1–2 mm) and no change during AF [14]. Consequently, implanting a round device into an oval-shaped ostium may lead to incomplete occlusion and peri-device leakage. This problem is reported in 32% of the cases after Watch- man implantation [15]. Incomplete occlusion of the LAA is thought to result in a higher event rate, but 2 analyses that used the PLAATO and Watchman sys- tems, respectively, showed no increased event rate of thromboembolism [16]. Occasionally, if gaps are significant, then it is possible to occlude them by us- ing different devices fully [17]. This eccentricity in the shape of the orifice also poses hurdles in estimating the exact size of the ostium by using two-dimension- al (2-D) TEE and frequently results in an underestima- tion of the exact diameter, which leads to implanta- tion of an undersized device.
In addition to the eccentric shape of the ostium, another problem related to the single-device clo-
sure technique is the maximum body size of the LAA. Even the new-generation ACP and Watchman devic- es can fit into a maximum body diameter of 30 mm [18]. Exclusion of the LAA might require 2 devices in such cases. Enio et al. reported a case series where 5 of their patients underwent double-device implanta- tion using devices other than Watchman, with good anatomical results at follow-up [3]. Implanting 2 Watchman devices in a single patient to close bilob- ulated LAA was previously reported once. The report concluded that occlusion of 2 separate lobes with a common ostium is practically possible, as the main bodies of each lobe are separated by a thick ridge of pectinate muscle [19].
Although it technically sounds feasible, few chal- lenges are associated with double-device implan- tation. First, the polyethylene terephthalate mem- branes and nitinol cage covering the Watchman device can be damaged while releasing the second device, which itself can serve as a nidus for throm- bus formation due to residual leakage and difficult endothelialization. Second, putting 2 round-shaped devices over an elliptical ostium can lead to multi- ple residual flows between the LA and LAA. Third, no long-term data are available to support double-de- vice implantation in the LAA; therefore, delayed me- chanical complications are unknown.
This case shows that sealing of a bilobed LAA is technically feasible especially with a favorable anat- omy, which includes totally separated bodies of both lobes with adequate body sizes. Although this pro- cedure can potentially result in damaging the deli- cate membranous part of the Watchman device, for the time being, no data are available to evaluate the long-term effects of this interaction. We also suggest that 2-D TEE alone can underestimate the size and anatomy of the LAA. Preprocedural assessment using three-dimensional TEE and intraprocedural angiogra- phy is crucial for better occlusion of the LAA.
Conflict of Interest
The authors have no conflict of interest relevant to this publication.
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Alsmadi F. et al.
Double Watchman Device Implantation